Methods and apparatus for controlling series-connected leds

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DESCRIPTION

Procedures and apparatus for controlling LEDs connected in series.

Background

Light Emitting Diodes (LEDs) are semiconductor-based light sources frequently used in low-power instrumentation and appliance applications for indication purposes. LEDs are conventionally available in a variety of colors (eg, red, green, yellow, blue, white), based on the types of materials used in their manufacture. This variety of LED colors has recently been harnessed to create novel LED-based light sources that have sufficient light output for new space lighting applications. For example, as discussed in US Patent No. 6,016,038, multiple LEDs of different color can be combined into one luminaire, in which the intensity of the LEDs of each different color is independently varied to produce several different shades. In one example of such a fixture, red, green, and blue LEDs are used in combination to produce literally hundreds of different shades from a single fixture. Additionally, the relative intensities of the red, green and blue LEDs can be controlled by computer, thereby providing a programmable multi-color light source. Such LED-based light sources have been employed in a variety of lighting applications where lighting effects of varying color are desired.

For example, US Patent No. 6,777,891 (the "'891 patent") contemplates providing a plurality of LED-based lighting units as a computer-controllable "string of lights", wherein each lighting unit constitutes an individually controllable "node" of the string of lights. Suitable applications for such strings of lights include entertainment-oriented and decorative lighting applications (eg, Christmas tree lights, screen lights, theme park lighting, arcade lighting and other games, etc.). Through computer control, one or more arrays of such lights can provide a variety of complex temporal and color changing lighting effects. In many implementations, lighting data is communicated to one or more nodes of a given row of lights in series, according to a variety of different data transmission and processing schemes, while power is provided in parallel to respective lighting units of the row (for example from a rectified high voltage source, in some cases with substantial ripple voltage).

The operating voltage required by each lighting unit (as well as the row, due to the parallel power interconnection of the lighting units) normally refers to the forward voltage of the LEDs in each lighting unit (e.g. from approximately 2 to 3.5 volts depending on the type / color of LED), how many LEDs are used for each “color channel” of the lighting unit and how they are interconnected, and how the respective color channels are arranged to receive power from a power source. For example, the operating voltage for a lighting unit having a parallel arrangement of respective color channels for receiving power, each channel including an LED having a forward voltage on the order of 3 volts and corresponding circuitry to provide current to the channel, can be on the order of 4 to 5 volts, applied in parallel to all channels to house the one LED and current circuitry on each channel. Consequently, in many applications, some type of voltage conversion device is desirable in order to provide a generally lower operating voltage to one or more LED-based lighting units relative to commonly available higher power supply voltages ( for example, 12 VDC, 15 VDC, 24 VDC, a rectified line voltage, etc.).

An impediment to the widespread adoption of low-voltage LEDs and low-voltage LED-based lighting units as light sources in applications where higher power supply voltages are generally readily available is the need to convert power from one voltage to another, which, in many cases, results in wasted energy and conversion inefficiency. Furthermore, power conversion typically involves power management components of a type and size that generally prevent integration. Conventionally, LEDs are provided as individual LED packages, or multiple LEDs connected in series or parallel in a package. Currently, LED packages that include one or more integrated LEDs in conjunction with some type of power conversion circuitry are not available. A significant barrier to the integration of LEDs and power conversion circuitry relates to the type and size of power management components required to convert power to the relatively lower voltage levels normally required to drive LEDs.

For example, a voltage conversion apparatus (eg DC to DC converters) typically uses inductors as energy storage elements, which cannot be efficiently integrated into silicon chips to form integrated circuits. Inductor size is also a major barrier to integrated circuit implementations, both in terms of an individual inductor component as part of any integrated circuit, as well as more specifically in LED packages. Furthermore, inductors cannot normally be made so efficient as to handle a relatively wide voltage range, and inductive converters generally require significant capacitance to store energy during converter operation. Thus, a conventional inductor-based voltage conversion apparatus has quite a significant footprint compared to single or multiple LED packages, and they themselves do not lend themselves to integration with LED packages.

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Capacitive voltage conversion systems present similar challenges. Capacitive systems cannot convert voltage directly, and instead create fixed fractional multiplied or divided voltages. The number of capacitors required is directly related to the product of the whole numbers in the numerator and the denominator of the fraction. Since each capacitor also generally requires multiple switches to connect it between the higher voltage power supply and a relatively lower voltage load, the number of components increases dramatically as the numerator and denominator increase, with a corresponding decrease in efficiency. . If efficiency is a prominent requirement, these systems must have practical reasons with a unit denominator or numerator; Hence, either the input or the output is low voltage at higher current, effectively decreasing efficiency. Therefore, it is inevitably necessary that the efficiency be balanced at any particular operating voltage to decrease the complexity and make the fractions simpler.

Summary of the invention

Applicant has recognized and appreciates that it is often useful to consider connecting multiple lighting units or light sources (eg LEDs), as well as other types of loads, to receive operating power in series rather than in parallel. A series interconnection of multiple LEDs can allow the use of operating voltages that are significantly higher than typical LED forward voltages, and can also allow the operation of multiple LEDs or LED-based lighting units without requiring a transformer between a source. power supplies (for example, line voltage or wall power such as 120 VAC or 240 VAC) and loads (that is, multiple loads connected in series can be operated "directly" from one line voltage).

Accordingly, various embodiments of the present invention generally relate to methods and apparatus for controlling LED-based light sources, wherein respective elements of a multi-element light source, and / or multiple light sources themselves, they are coupled in series to receive operating power. A series interconnection of such components generally allows an increase in the overall operating voltage of the system; for example, three LEDs or LED-based lighting units each having a nominal operating voltage of approximately 3 to 7.4 VDC can be connected in series and operated at voltages of 9 to 24 VDC. Naturally, almost any appropriate number of LEDs or LED-based lighting units can be similarly coupled in series depending at least in part on the nominal operating voltage of each LED or lighting unit, and the expected nominal supply voltage provided by an available power supply. For the purposes of the following discussion, various concepts related to series-connected LEDs are discussed; however, it should be appreciated that many, if not all, of the concepts discussed herein can be applied in a simulated manner to the various arrays of LEDs (series, parallel, and / or series / parallel arrangements), as well as multiple LED-based lighting units, which are coupled in series to receive operating power.

In an exemplary embodiment, multiple LEDs are nominally connected in series between two nodes to which an operating voltage is applied, and one or more controllable current paths are connected in parallel with one or more of the connected LEDs. serially. In various aspects, the controllable current path (s) may be implemented as one or more controllable switches to completely divert current around a given LED, or as fixed or variable controllable current sources configured to divert all or only part of the series current flowing between the two nodes around the given LED. In this way, the brightness of a given LED can be controlled and, in the extreme, the LEDs can be turned off completely by diverting current completely around it. In another aspect, a controller is configured to control the one or more controllable current paths according to any one of several techniques; for example, a controller may operate one or more controllable current paths based on data received as lighting instructions, and / or one or more measured parameters related to the available operating voltage applied to the two nodes.

More specifically, in one embodiment, the ability to partially or fully divert current around one or more series connected LEDs is employed in circumstances where a nominal expected operating voltage, applied to the two nodes between which the LEDs are connected series connected devices, drops below a minimum operating voltage necessary to activate all series connected devices. For example, in automotive applications based on an electrical system that includes a conventional 12 volt car battery, the operating voltage available to automotive accessories when the engine is running and the electrical system is charging is typically between 13 , 8 and 14.5 volts; However, when the engine is not running, the available operating voltage can be rapidly reduced to 12 to 12.8 volts, or even lower (for example, when high loads are present, and / or as the load is further discharged). car battery). Therefore, a series-connected LED-based automotive lighting apparatus must take into account all possible circumstances affecting the available operating voltage.

In view of the above, one embodiment of the present invention relates to a lighting apparatus that includes multiple LEDs connected in series, one or more controllable current paths connected in parallel with one or more of the LEDs connected in series, and a controller for controlling one or more of the controllable current paths based on one or more monitored parameters representative of an available operating voltage for series connected LEDs. It should be appreciated that although an example of an automotive application was provided above, various implementations of this embodiment are not necessarily limited to automotive applications or the particular range of operating voltages contemplated for such applications. More generally, in one aspect of this embodiment, the controller may be configured to control a

ES 2 348 841 T3 or more of the controllable current paths such that an amount of current that deflects around a corresponding LED increases when one or more parameters indicate that the operating voltage is less than that required to activate all LEDs connected in series, thereby reducing the required operating voltage required to power the devices connected in series. For example, in one implementation, the controllable current paths can be switches that completely divert the current around a corresponding LED so that the LEDs are essentially short-circuited and removed from the series connection of devices. In this way, the operating voltage required to operate the remaining series connected LEDs is reduced by the individual operating voltage of each LED that is short-circuited due to current deviation.

In still another embodiment, a lighting apparatus based on multiple LEDs connected in series, one or more controllable current paths connected in parallel with one or more of the LEDs connected in series, and a controller for controlling one or more of the paths of controllable current, it can be implemented as one or more integrated circuits. In addition, integrated circuit implementations can be packaged appropriately for ease of installation, deployment, and / or use in any one of several applications, including those applications where conventional operating voltages are readily available. For example, in one embodiment, an LED-based lighting unit that includes multiple LEDs connected in series, one or more controllable current paths in parallel with one or more of the LEDs, and a controller for controlling current paths can be implemented as one or more integrated circuits in a single package that includes one or more appropriate electrical connectors that can easily be coupled directly to a power source at any one of several conventional operating voltages (e.g. For example, for automotive applications, nominally 12 to 14 volts DC).

In summary, an embodiment of the present invention refers to an apparatus, comprising at least two LEDs connected in series between a first node and a second node, in which a current flows in series between the first node and the second node when an operating voltage is applied across the first node and the second node. The apparatus further comprises at least one controllable current path connected in parallel with at least one first LED of the at least two LEDs to at least partially divert the current in series around the first LED. The apparatus further comprises at least one controller for monitoring at least one parameter representative of the operating voltage and determining a maximum number of LEDs of the at least two LEDs that can be activated by the operating voltage. The at least one controller controls the at least one controllable current path so that it increases an amount of the series current that deflects around at least the first LED when the maximum number is less than the total number of all the at least two. LEDs connected in series.

Another embodiment relates to a method of activating a plurality of LEDs connected in series between a first node and a second node, in which a current flows in series between the first node and the second node when an operating voltage is applied to along the first node and the second node. The method comprises: A) monitoring at least one parameter representative of the operating voltage; B) determining a maximum number of LEDs of the at least two LEDs that can be activated by the operating voltage; and C) when the maximum number is less than the total number of all the at least two LEDs connected in series, causing the short-circuit of at least one of the plurality of LEDs so that fewer than all of the plurality of LEDs are activated simultaneously.

Another embodiment relates to an apparatus, comprising a plurality of LEDs connected in series between a first node and a second node, in which a current flows in series between the first node and the second node when an operating voltage is applied to along the first node and the second node. The apparatus further comprises a plurality of controllable current paths, each current path being connected in parallel with a corresponding LED of the plurality of LEDs to divert current in series around the corresponding LED of the plurality of LEDs, and a connected current source in series with the plurality of LEDs between the first node and the second node to set the series current. The apparatus further comprises at least one controller for monitoring at least one parameter related to operating voltage and for intermittently controlling the plurality of controllable current paths so as to divert the series current around respective corresponding LEDs of the plurality of LEDs in a timed sequence when the at least one monitored parameter indicates that the operating voltage is below a threshold value predetermined, such that fewer than all of the plurality of LEDs are activated simultaneously.

Another embodiment refers to a lighting apparatus for automobiles, comprising at least one integrated circuit chip. The at least one integrated circuit chip comprises: i) a first number of LEDs connected in series between a first node and a second node, in which a current flows in series between the first node and the second node when a voltage is applied operating along the first node and the second node; ii) a second number of controllable current paths, in which the second number is equal to or less than the first number, each current path being connected in parallel with a corresponding LED of the first LED number to divert the current in series around the corresponding LED of the first number of LEDs; iii) a current source connected in series with the first number of LEDs between the first node and the second node to set the series current; and (iv) at least one controller for monitoring at least one parameter representative of the operating voltage and determining a maximum number of LEDs from the first number of LEDs that can be activated by the operating voltage. The at least one controller controls the second number of controllable current paths so that the series current is shunted around respective corresponding LEDs of the first.

ES 2 348 841 T3 number of LEDs when the maximum number is less than the first number, such that a number less than all of the first number of LEDs are activated simultaneously. The automotive lighting apparatus further comprises a package for the at least one integrated circuit chip, the package including at least one first electrical connector configured to mate with a complementary electrical connector or wire harness of an automobile. The at least one first electrical connector includes at least one first conductor electrically connected to the first node and a second conductor electrically connected to the second node for applying operating voltage across the first node and the second node.

Relevant terminology

As used herein for the purposes of the present description, the term "LED" is to be understood to include any light emitting diode or other type of carrier junction / injection based system that can generate radiation in response to an electrical signal. . Thus, the term LED includes, but is not limited to, various semiconductor-based structures that emit light in response to light-emitting polymers, currents, organic light-emitting diodes (OLEDs), electroluminescent bands, and the like.

In particular, the term LED refers to light-emitting diodes of all types (including semiconductor and organic light-emitting diodes) that can be configured to generate radiation in one or more of the infrared spectrum, ultraviolet spectrum, and various parts of the spectrum. visible (which generally include radiation wavelengths from about 400 nanometers to about 700 nanometers). Some examples of LEDs include, but are not limited to, various types of infrared LEDs, ultraviolet LEDs, red LEDs, blue LEDs, green LEDs, yellow LEDs, amber LEDs, orange LEDs, and white LEDs (discussed further below). It should also be appreciated that LEDs can be configured and / or controlled to generate radiation that has various bandwidths (e.g., full widths at half maximum, or FWHM, full width at half maximum) for a given spectrum (e.g. , narrow bandwidth, wide bandwidth), and a variety of dominant wavelengths within a given general color classification.

For example, an implementation of an LED configured to generate essentially white light (eg, a white LED) may include several dice that respectively emit different electroluminescence spectra that, in combination, mix to form essentially white light. In another implementation, a white light LED can be associated with a phosphor material that converts electroluminescence that has a first spectrum to a different second spectrum. In an example of this implementation, an electroluminescence that has a narrow bandwidth spectrum and relatively short wavelength "pumps" the phosphor material, which in turn radiates longer wavelength radiation that has a somewhat shorter spectrum. wider.

It should also be understood that the term LED does not limit the type of physical and / or electrical package of an LED. For example, as discussed above, an LED can refer to a single light emitting device that has multiple dies that are configured to respectively emit different spectra of radiation (eg, that may or may not be individually controlled. Also, an LED can be associated with a phosphor that is considered an integral part of LEDs (for example, some types of white LEDs). Generally, the term LED can refer to packaged LEDs, non-packaged LEDs, surface mount LEDs, chip-on-board LEDs, T-pack mount LEDs, radial pack LEDs, power pack LEDs, LEDs including some type of coating and / or optical element (for example, a diffuser lens), etc.

The term "light source" should be understood to refer to one or more of a variety of radiation sources, including, but not limited to, LED-based sources (including one or more LEDs as defined above), sources incandescent (for example, filament lamps, halogen lamps), fluorescent sources, phosphorescent sources, high intensity discharge sources (for example, sodium vapor, mercury vapor, and metal halide lamps), lasers, electroluminescent sources, pyroluminescent sources (eg flames), candle-based luminescent sources (eg gas jackets, carbon arc radiation sources), photoluminescent sources (eg gas discharge sources), luminescent sources cathode sources using electronic priming, galvanoluminescent sources, crystaloluminescent sources, cineluminescent sources, thermoluminescent sources, triboluminescent sources, sonoluminescent sources, radioluminescent sources, and luminescent polymers.

A given light source can be configured to generate electromagnetic radiation within the visible spectrum, outside the visible spectrum, or a combination of both. Thus, the terms "light" and "radiation" are used interchangeably herein. Additionally, a light source may include as an integral component one or more filters (eg, color filters), lenses, or other optical components. Furthermore, it should be understood that the light sources can be configured for a variety of applications, including, but not limited to, indication, display, and / or lighting. An "illumination source" is a light source that is particularly configured to generate radiation that is of sufficient intensity to effectively illuminate an interior or exterior space. In this context, "sufficient intensity" refers to sufficient radiant power in the visible spectrum generated in space or surroundings (the unit "lumens" is often used to represent the total light emission of a light source in all directions , in terms of radiant power or "luminous flux") to provide ambient lighting (that is, light that can be indirectly perceived and that can, for example, reflected out of one or more of a variety of intermediate surfaces before being perceived in whole or in part).

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The term "spectrum" is to be understood as referring to any one or more frequencies (or wavelengths) of radiation produced by one or more light sources. Consequently, the term "spectrum" refers to frequencies (or wavelengths) not only in the visible range, but also frequencies (or wavelengths) in the infrared, ultraviolet, and other areas of the global electromagnetic spectrum. Furthermore, a given spectrum may have a relatively narrow bandwidth (for example, an FWHM that has essentially few frequency or wavelength components) or a relatively wide bandwidth (several frequency or wavelength components that have various relative intensities). It should also be appreciated that a given spectrum may be the result of a mixing of two or more other spectra (eg, mixing of radiation emitted respectively by multiple light sources).

For the purposes of this description, the term "color" is used interchangeably with the term "spectrum." However, the term "color" is generally used to refer primarily to a property of radiation that can be perceived by an observer (although this use is not intended to limit the scope of this term). Accordingly, the terms "different colors" implicitly refer to multiple spectra having different wavelength components and / or bandwidths. It should also be appreciated that the term "color" can be used in relation to both white and non-white light.

The term "color temperature" is generally used herein in relation to white light, although this use is not intended to limit the scope of this term. Color temperature essentially refers to a particular hue or color content (eg, reddish, bluish) of white light. The color temperature of a given radiation sample is conventionally characterized according to the temperature in degrees Kelvin (K) of a black body radiator that radiates essentially the same spectrum as the radiation sample in question. Blackbody radiator color temperatures generally fall within a range of from about 700 ° K (normally considered the first thing visible to the human eye) to more than 10,000 ° K; generally white light is perceived at color temperatures above 1500-2000 ° K.

Lower color temperatures generally indicate white light that has a more significant red component or a "warmer feel", while higher color temperatures generally indicate white light a more significant blue component or a "cooler feel". As an example, fire has a color temperature of approximately 1,800 ° K, a conventional incandescent light bulb has a color temperature of approximately 2,848 ° K, early morning sunlight has a color temperature of approximately 3,000 ° K, and the overcast sky at noon has a color temperature of about 10,000 ° K. A color image that is viewed under white light that has a color temperature of approximately 3,000 ° K has a relatively reddish cast, while the same color image viewed under white light that has a color temperature of approximately 10,000 ° K has a relatively bluish hue.

The term "luminaire" is used herein to refer to an implementation or arrangement of one or more lighting units in a particular form factor, assembly or package. The term "lighting unit" is used herein to refer to an apparatus that includes one or more light sources of the same or different types. A given lighting unit may have any one of a variety of mounting arrangements for the light source (s), enclosure / housing arrangements and shapes, and / or electrical and mechanical connection configurations. Additionally, a given lighting unit may optionally be associated with (eg, include, coupled and / or packaged together with) various other components (eg, control circuitry) related to the operation of the source (s). (s) of light. An "LED-based lighting unit" refers to a lighting unit that includes one or more LED-based light sources as discussed above, alone or in combination with other than LED-based light sources. A "multi-channel" lighting unit refers to an LED-based or non-LED-based lighting unit that includes at least two light sources configured to respectively generate different radiation spectra, in which each different source spectrum can be called "channel" of the multi-channel lighting unit.

The term "controller" is used herein generally to describe various apparatus related to the operation of one or more light sources. A controller can be implemented in numerous ways (eg, such as with dedicated hardware) to perform various functions discussed herein. A "processor" is an example of a controller that employs one or more microprocessors that can be programmed using software (eg, microcode) to perform various functions discussed herein. A controller can be implemented with or without employing a processor, and can also be implemented as a combination of dedicated hardware to perform some functions and a processor (eg, one or more programmed microprocessors and associated circuitry) to perform other functions. Examples of controller components that may be employed in various embodiments of the present disclosure include, but are not limited to, conventional microprocessors, application-specific integrated circuits (ASICs), and field programmable gate arrangements (FPGAs).

In various implementations, a processor or controller may be associated with one or more storage media (referred to generically herein as "memory", for example, volatile and non-volatile computer memory such as RAM, PROM, EPROM and EEPROM, disks flexible discs, compact discs, optical discs, magnetic tape, etc.). In some implementations, the storage media may be encoded with one or more programs that, when run on one or more processors and / or controllers, perform at least some of the functions discussed herein. Various storage media can be fixed within a

ES 2 348 841 T3 processor or controller or may be transportable, such that the one or more programs stored therein may be loaded into a processor or controller so as to implement various aspects of the present disclosure discussed herein. The terms "program" or "computer program" are used herein in a generic sense to refer to any type of computer code (eg, software or microcode) that can be used to program one or more processors or controllers.

The term "addressable" is used herein to refer to a device (eg, a light source in general, a lighting unit or luminaire, a controller or processor associated with one or more light sources or lighting units. , other related non-lighting devices, etc.) that are configured to receive information (e.g. data) intended for multiple devices, including the same, and to respond selectively to particular information conceived for it. The term "addressable" is often used in connection with a networked environment (or a "network", discussed further below), in which multiple devices are coupled together via certain means or medium of communication.

In a network implementation, one or more devices coupled to a network can serve as the controller for one or more other devices coupled to the network (eg, in a master / slave relationship). In another implementation, a networked environment may include one or more dedicated controllers that are configured to control one or more of the devices attached to the network. Generally, multiple devices coupled to the network may each have access to data that is present on the communication medium (s); however, a given device may be "addressable" in that it is configured to selectively exchange data with (ie, receive data from and / or transmit data to) the network, based, for example, on one or more particular identifiers (for example , “Addresses”) assigned to it.

The term "network" as used herein refers to any interconnection of two or more devices (including controllers or processors) that facilitates the transport of information (eg for device control, data storage, exchange of data, etc.) between any two or more devices and / or between multiple devices attached to the network. As can be readily appreciated, various network implementations suitable for interconnecting multiple devices can include any of a variety of network topologies and employ any of a variety of communication protocols. Additionally, in various networks according to the present description, any connection between two devices can represent a dedicated connection between the two systems, or alternatively a non-dedicated connection. In addition to carrying information intended for the two devices, such a non-dedicated connection may carry information not necessarily intended for either device (eg, an open network connection). Furthermore, it should be readily appreciated that various device networks as discussed herein may employ one or more wireless, wired / cable, and / or fiber optic links to facilitate the transport of information throughout the network.

The term "user interface" as used herein refers to an interface between a human user or operator and one or more devices that allow communication between the user and the device (s). Examples of user interfaces that may be employed in various implementations of the present disclosure include, but are not limited to, switches, knobs, buttons, selectors, sliders, a mouse, keyboard, numeric keypad, various types of game controllers (e.g. , joysticks), joysticks, display screens, various types of graphical user interfaces (GUI), touch screens, microphones and other types of sensors that can receive some form of human-generated stimulus and generate a signal in response to it.

Patents and Related Patent Applications • US Patent No. 6,016,038, issued January 18, 2000, entitled "Multicolored LED Lighting Method and Apparatus";

• US Patent No. 6,211,626, issued April 3, 2001, entitled "Illumination Components";

• US Patent No. 6,608,453, issued August 19, 2003, entitled "Methods and Apparatus for controlling Devices in a Networked Lighting System";

• US Patent No. 6,777,891 issued on August 17, 2004, entitled "Methods and Apparatus for controlling Devices in a Networked Lighting System"; and • US Patent Application Serial No. 11 / 836,560, filed August 9, 2007, entitled "Methods and Apparatus for Simulating Resistive Loads."

Brief description of the drawings

In the drawings, like reference characters generally refer to equal parts throughout the different views. Furthermore, the drawings are not necessarily to scale, emphasis instead being generally placed on illustrating the principles of the invention.

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Fig. 1 is a diagram illustrating a lighting unit according to various embodiments of the invention.

Figure 2 is a diagram illustrating a network lighting system according to various embodiments of the invention.

Figure 3 is a block diagram of a lighting apparatus including multiple LEDs connected in series and one or more controllable current paths, in accordance with one embodiment of the invention.

FIG. 4 is a diagram illustrating an exemplary circuit implementation of the lighting apparatus shown in FIG. 3, in accordance with one embodiment of the present invention.

Figures 5A-5D illustrate respective examples of controllable current paths suitable for use in the circuit of Figure 4, according to various embodiments of the present invention.

Figure 6 illustrates an exemplary package for the lighting apparatus of Figure 4, in accordance with one embodiment of the present invention.

Figure 7 illustrates an exemplary circuit for controlling the nodal voltage across a given LED in a stack of series connected LEDs, in accordance with one embodiment of the present invention.

Figure 8 illustrates a lighting apparatus according to another embodiment of the present invention employing op amp power supplies to generate respective nodal voltages in a stack of series connected LEDs, and individual current sources for each LED.

Figure 9 illustrates a lighting apparatus according to another embodiment of the present invention having different groupings of controllable channels with corresponding current sources.

Figure 10 illustrates a lighting apparatus according to another embodiment of the present invention that is particularly configured to simulate a resistive load.

Figures 11 and 12 illustrate a "rail splitter" architecture for providing power to multiple lighting units from one operating voltage, in accordance with one embodiment of the present invention.

Detailed description

Various embodiments of the present invention are described below, including certain embodiments particularly related to LED-based light sources. It should be appreciated, however, that the present disclosure is not limited to any particular mode of implementation, and that the various embodiments explicitly discussed herein are primarily for purposes of illustration. For example, the various concepts discussed herein can be appropriately implemented in a variety of environments involving LED-based light sources, other types of light sources that do not include LEDs, environments that involve both LEDs, and other types of light sources in combination, and environments involving related non-lighting devices alone or in combination with various types of light sources.

Figure 1 illustrates an example of a lighting unit 100 according to an embodiment of the present disclosure. Some general examples of LED-based lighting units similar to those previously described in connection with Figure 1 can be found, for example, in US Patent No. 6,016,038, issued January 18, 2000 to Mueller et al. al., entitled "Multicolored LED Lighting Method and Apparatus", and US Patent No. 6,211,626, issued April 3, 2001 to Lys et al, entitled "Illumination Components."

The lighting unit 100 shown in Figure 1 may be used alone or in conjunction with other similar lighting units in a lighting unit system (eg, as further discussed below in connection with Figure 2). Used alone or in combination with other lighting units, the lighting unit 100 can be used in a variety of applications including, but not limited to, direct-view or indirect-view indoor or outdoor space lighting (e.g., architectural). and lighting in general, direct or indirect lighting of objects or spaces, lighting for special effects / based on theatrical or other shows, decorative lighting, safety-oriented lighting, vehicle lighting, lighting associated with, or lighting of, exhibitions and / or merchandise (e.g. for advertising and / or in retail / consumer environments), communication systems, and combined lighting or lighting , etc., as well as for various indication, display and information purposes. Additionally, one or more lighting units similar to the one described in relation to Figure 1 may be implemented in a variety of products including, but not limited to, various forms of modules or light bulbs having various shapes and arrangements. It is electrical / mechanical coupling (including replacement or "retrofit" modules or bulbs adapted for use in conventional luminaires or sockets), as well as a variety of household and / or consumer products (for example, night lights, toys, games or game components, entertainment components or systems, utensils, appliances, kitchen robots, cleaning products, etc.) and components architectural (for example, illuminated panels for walls, floors, ceilings, illuminated trim and decorative components, etc.).

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In various implementations and embodiments, the lighting unit 100 shown in Figure 1 includes one or more light sources 104A, 104B, 104C, and 104D (collectively shown as 104), wherein one or more of the light sources may be an LED-based light source that includes one or more light-emitting diodes (LEDs). In one aspect of this embodiment, any two or more of the light sources may be adapted to generate radiation of different colors (eg red, green, blue); in this regard, as discussed above, each of the different colored light sources generates a different source spectrum that constitutes a different "channel" of a "multi-channel" lighting unit. Although Figure 1 shows four light sources 104A, 104B, 104C and 104D, it should be appreciated that the lighting unit is not limited in this regard as different numbers and various types of light sources can be employed (all light sources LED-based, LED-based and non-LED-based light sources in combination, etc.) adapted to generate radiation of a variety of different colors, including essentially white light, in the lighting unit 100, as discussed further below.

As shown in Figure 1, the lighting unit 100 may also include a controller 105 that is configured to output one or more control signals to activate the light sources so that various light intensities are generated from the light sources. light. For example, in one implementation, controller 105 may be configured to output at least one control signal for each light source so that the intensity of light (eg, radiant power in lumens) generated by each light source is independently controlled. light; alternatively, controller 105 may be configured to output one or more control signals to collectively control a group of two or more identically light sources. Some examples of control signals that can be generated by the controller to control light sources include, but are not limited to, pulse modulated signals, pulse width modulated (PWM) signals, amplitude modulated signals pulse amplitude modulated (PAM), pulse code modulated (PCM) signals, analog control signals (e.g. current control signals, voltage control signals), combinations and / or modulations of the above signals, or other control signals. In one aspect, particularly in relation to LED-based sources, one or more modulation techniques provide variable control using a fixed current level applied to one or more LEDs, so as to mitigate possible undesirable or unpredictable variations in the emission of LEDs that can arise if a variable LED drive current is used. In another aspect, controller 105 may control other dedicated circuitry (not shown in FIG. 1) which in turn control the light sources so that their respective intensities are varied.

In general, the intensity (radiant emission power) of the radiation generated by the one or more light sources is proportional to the average power supplied to the light source (s) during a given period of time. Accordingly, one technique for varying the intensity of radiation generated by the one or more light sources involves modulating the power delivered to (ie, the operating power of) the light source (s). For some types of light sources, including LED-based sources, this can be effectively accomplished using a pulse width modulation (PWM) technique.

In an exemplary implementation of a PWM control technique, a fixed predetermined voltage V is periodically applied to each channel of a lighting unit._source along a given light source that constitutes the channel. Applying the voltage V_source can be achieved by one or more switches, not shown in Figure 1, controlled by controller 105. Although the voltage V_source applied along the light source, a set predetermined current I is allowed to flow_source (eg determined by a current regulator, also not shown in figure 1) through the light source. Again, remember that an LED-based light source can include one or more LEDs, such that the voltage V_source can be applied to a group of LEDs that constitute the source, and the current I_source It can be pulled out by the LED group. The set voltage V_source along the light source when activated, and the regulated current I_source drawn by the light source when activated, determines the amount of instantaneous operating power P_source light source (P_source = V_source I_source). As mentioned above, for LED-based light sources, the use of a regulated current mitigates possible undesirable or unpredictable variations in LED emission that can arise if a variable LED drive current is employed. According to the PWM technique, by periodically applying the voltage Vsource to the light source and varying the time the voltage is applied during a given on-off cycle, the average power supplied to the light source can be modulated over time (the average operating power). In particular, the controller 105 may be configured to apply the voltage Vsource to a given light source in pulsed mode (for example, by emitting a control signal that operates one or more switches to apply the voltage to the light source), preferably at a frequency that is greater than that which can be detected by the human eye (eg, greater than about 100 Hz). In this way, an observer of the light generated by the light source does not perceive the differentiated on-off cycles (commonly referred to as the “flicker effect”), but rather the integration function of the eye perceives a generation of light. essentially continuous. By adjusting the pulse width (ie on time, or “duty cycle”) of on-off cycles of the control signal, the controller varies the average amount of time the light source is activated in any given period. of given time, and thus the average operating power of the light source varies. In this way, the perceived brightness of the light generated from each channel can be varied in turn.

As discussed in greater detail below, controller 105 may be configured to control each different light source channel of a multichannel lighting unit at a predetermined average operating power to provide a corresponding radiant emission power for the generated light. for each channel. Alternatively, controller 105 may receive instructions (eg, "lighting commands")

ES 2 348 841 T3 from a variety of sources, such as a user interface 118, a signal source 124, or one or more communication ports 120, which specify recommended operating powers for one or more channels and thus the corresponding radiant emission powers for the light generated by the respective channels. By varying the recommended operating powers for one or more channels (eg, according to different lighting instructions or commands), different levels of brightness and perceived colors of light can be generated by the lighting unit.

In one embodiment of the lighting unit 100, as mentioned above, one or more of the light sources 104A, 104B, 104C, and 104D shown in Figure 1 may include a cluster of multiple LEDs or other types of light sources. (eg, various parallel and / or series connections of LEDs or other types of light sources) that are controlled together by controller 105. Additionally, it should be appreciated that one or more of the light sources may include one or more LEDs that are adapted to generate radiation having any of a variety of spectra (i.e., wavelengths or wavelength bands), including , but are not limited to, various visible colors (including essentially white light), various color temperatures of white, ultraviolet, or infrared light. LEDs having a variety of spectral bandwidths (eg, narrow band, wider band) can be employed in various implementations of the lighting unit 100.

In another aspect of the lighting unit 100 shown in Figure 1, the lighting unit 100 can be constructed and arranged to produce a wide range of variable color radiation. For example, in one embodiment, the lighting unit 100 may be particularly arranged such that light of controllable variable intensity (i.e., variable radiant power) generated by two or more of the light sources is combined to produce a mixed colored light. (including essentially white light that has a variety of color temperatures). In particular, the color (or color temperature) of the mixed colored light can be varied by varying one or more of the respective intensities (radiant power emitted) of the light sources (for example, in response to one or more control signals issued by controller 105). In addition, controller 105 may be particularly configured to provide control signals to one or more of the light sources so as to generate a variety of static or time-varying (dynamic) multi-color (or multi-temperature) lighting effects. color). To this end, in one embodiment, the controller may include a processor 102 (eg, a microprocessor) programmed to provide such control signals to one or more of the light sources. In various aspects, processor 102 may be programmed to provide such control signals autonomously, in response to lighting commands, or in response to various user inputs or signals.

Thus, the lighting unit 100 can include a wide variety of LED colors in various combinations, including two or more red, green, and blue LEDs to produce a mixture of colors, as well as one or more other LEDs to create colors. and variable color temperatures of white light. For example, red, green, and blue can be mixed with amber, white, UV, orange, IR, or other LED colors. Additionally, multiple white LEDs having different color temperatures may be employed (for example, one or more first white LEDs generating a first spectrum corresponding to a first color temperature, and one or more second white LEDs generating a second spectrum corresponding to a second color temperature different from the first color temperature), in a lighting unit with all white LEDs or in combination with other LED colors. Such combinations of different color LEDs and / or white LEDs of different color temperatures in the lighting unit 100 can facilitate accurate reproduction of a large number of desirable lighting spectrum conditions, examples of which include, but are not limited to, a variety of outdoor sunlight equivalent to different times of day, various indoor lighting conditions, lighting conditions to simulate a complex background of multiple colors, and the like. Other desirable lighting conditions can be created by eliminating particular parts of the spectrum that can be specifically absorbed, attenuated or reflected in certain environments. Water, for example, tends to absorb and attenuate the colors of light other than blue and other than green, so that underwater applications can benefit from lighting conditions that are tailored to emphasize or attenuate some spectral elements in relation to others.

As shown in FIG. 1, the lighting unit 100 may also include a memory 114 for storing information. For example, memory 114 can be used to store one or more lighting commands or programs for execution by processor 126 (for example, to generate one or more control signals for light sources), as well as various types of data. useful for generating variable color radiation (eg calibration information, discussed further below). The memory 114 can also store one or more particular identifiers (eg, a serial number, an address, etc.) that can be used either locally or at a system level to identify the lighting unit 100. In various embodiments, such identifiers may be pre-programmed by a manufacturer, for example, and may be either alterable or later unalterable (for example, by some type of user interface located on the lighting unit, by one or more data or signals control received by the lighting unit, etc.). Alternatively, such identifiers can be determined at the time of initial use of the lighting unit in the field, and again can be altered or unalterable later.

Still referring to Figure 1, the lighting unit 100 may optionally include one or more user interfaces 118 that are provided to facilitate any of a number of user selectable settings or functions (e.g., generally controlling the light output of the lamp). lighting unit 100, change and / or select various pre-programmed lighting effects to be generated by the lighting unit, changing and / or selecting various selected lighting effect parameters, setting particular identifiers such as addresses or serial numbers for the lighting unit, etc.). In various embodiments, communication between

ES 2 348 841 T3 the user interface 118 and the lighting unit can be achieved through wireless, wired or cable transmission. In one implementation, the lighting unit controller 105 monitors the user interface 118 and controls one or more of the light sources 104A, 104B, 104C, and 104D based at least in part on a user operation of the interface. . For example, controller 105 may be configured to respond to user interface operation by originating one or more control signals to control one or more of the light sources. Alternatively, processor 126 may be configured to respond by selecting one or more preprogrammed control signals stored in memory, modifying control signals generated by executing a lighting program, selecting and executing a new memory lighting program, or affecting another. mode to radiation generated by one or more of the light sources.

In particular, in one implementation, the user interface 118 may constitute one or more switches (eg, a conventional wall switch) that interrupts power to the controller 105. In one aspect of this implementation, the controller 105 is configured to monitor the power controlled by the user interface, and in turn control one or more of the light sources based at least in part on a duration of a power interruption caused by the operation of the user interface. As discussed above, the controller may be particularly configured to respond to a predetermined duration of a power outage, for example, by selecting one or more preprogrammed control signals stored in memory, modifying control signals generated by executing a program of lighting, selecting and running a new memory lighting program, or otherwise affecting radiation generated by one or more of the light sources.

Figure 1 also illustrates that the lighting unit 100 may be configured to receive one or more signals 122 from one or more other signal sources 124. In one implementation, the lighting unit controller 105 may use the signal (s) 122, either alone or in combination with other control signals (e.g., signals generated by executing a lighting program, one or more outputs from a user interface, etc.), so that one or more of the light sources 104A, 104B, 104C, and 104D are controlled in a manner similar to that discussed above in connection with the user interface.

Examples of signal (s) 122 that may be received and processed by controller 105 include, but are not limited to, one or more audio signals, video signals, power signals, various types of data signals. , signals representing information obtained from a network (eg Internet), signals representing one or more detectable / sensed conditions, lighting unit signals, signals consisting of modulated light, etc. In various implementations, the signal source (s) 124 may be remotely located from the lighting unit 100, or included as a component of the lighting unit. In one embodiment, a signal from one lighting unit 100 could be sent over a network to another lighting unit 100.

Some examples of a signal source 124 that may be employed in, or used in connection with, the lighting unit 100 of FIG. 1 include any of a variety of sensors or transducers that generate one or more signals 122 in response to a certain stimulus. Examples of sensors of this type include, but are not limited to, various types of sensors for environmental conditions, such as thermally sensitive sensors (e.g. temperature, infrared), humidity sensors, motion sensors, photo sensors / light sensors (eg photodiodes, sensors that are sensitive to one or more particular electromagnetic radiation spectra such as spectroradiometers or spectrophotometers, etc.), various types of cameras, sound or vibration sensors or other pressure / force transducers (eg, microphones, piezoelectric devices), and the like.

Additional examples of a signal source 124 include various measurement / detection devices that monitor electrical characteristics or signals (eg, voltage, current, power, resistance, capacitance, inductance, etc.) or chemical / biological characteristics (eg, acidity, presence of one or more particular chemical or biological agents, bacteria, etc.) and provide one or more signals 122 based on measured values ​​of the signals or characteristics. Still other examples of a signal source 124 include various types of scanners, image recognition systems, speech or other sound recognition systems, robotic and artificial intelligence systems, and the like. A signal source 124 could also be a lighting unit 100, another controller or processor, or any one of many available signal generating devices, such as media players, MP3 players, computers, DVD players, CD players, etc. television signal sources, camera signal sources, microphones, speakers, telephones, mobile phones, instant messaging devices, SMS devices, wireless devices, personal organizer devices, and many others.

In one embodiment, the lighting unit 100 shown in FIG. 1 may also include one or more optical elements 130 to optically process radiation generated by the light sources 104A, 104B, 104C, and 104D. For example, one or more optical elements may be configured so that one or both of a spatial distribution and a propagation direction of the generated radiation are changed. In particular, one or more optical elements can be configured to change a diffusion angle of the generated radiation. In one aspect of this embodiment, one or more optical elements 130 may be particularly configured to variably change one or both of a spatial distribution and a direction of propagation of the radiation generated (e.g., in response to some electrical stimulus and / or or mechanical). Examples of optical elements that may be included in the lighting unit 100 include, but are not limited to, reflective materials, refractive materials.

ES 2 348 841 T3 vos, translucent materials, filters, lenses, mirrors and optical fibers. Optical element 130 may also include phosphorescent material, luminescent material, or other material that can respond to or interact with generated radiation.

As also shown in FIG. 1, the lighting unit 100 may include one or more communication ports 125 to facilitate coupling of the lighting unit 100 to any of a variety of other devices. For example, one or more communication ports 125 can facilitate the coupling of multiple lighting units together as a networked lighting system, where at least some of the lighting units are addressable (for example, they have particular identifiers or addresses). and they respond to particular data transported throughout the network.

In particular, in a networked lighting system environment, as discussed in further detail further below (for example, in relation to Figure 2), when data is communicated over the network, the controller 105 of each lighting unit coupled to the network can be configured to respond to particular data (for example, lighting control orders) belonging to it (for example, in some cases, as dictated by the respective identifiers of the networked lighting units). Once a given controller identifies particular data intended to do so, it can read the data and, for example, change the lighting conditions produced by its light sources according to the received data (for example, generating appropriate control signals for the sources of light). In one aspect, the memory 127 of each lighting unit coupled to the network can be loaded, for example, with a table of lighting control signals that correspond to data received by the processor 126 from the controller. Once the processor 126 receives data from the network, the processor can refer to the table to select the control signals that correspond to the received data, and consequently control the light sources of the lighting unit.

In one aspect of this embodiment, the processor 102 of a given lighting unit, whether or not coupled to a network, may be configured to interpret lighting data / instructions that are received in a DMX protocol (as discussed, for For example, in US patents 6,016,038 and 6,211,626), which is a lighting command protocol conventionally used in the lighting industry for some programmable lighting applications. In the DMX protocol, lighting instructions are transmitted to a lighting unit as control data that is formatted into packets that include 512 bytes of data, where each byte of data is made up of 8 bits representing a digital value of between zero and 255. These 512 bytes of data are preceded by a "start code" byte. A complete “packet” including 513 bytes (start code plus data) is transmitted serially at 250 kbit / s in accordance with RS-485 voltage levels and wiring practices, where the start of a packet is expressed for an interrupt of at least 88 microseconds.

In the DMX protocol, each byte of data out of the 512 bytes in a given packet is intended to be a lighting command for a particular "channel" of a multichannel lighting unit, where a digital value of zero indicates that there is no switching power. radiant emission for a given channel of the lighting unit (i.e. channel off), and a digital value of 255 indicates total radiant emission power (100% available power) for the given channel of the lighting unit (i.e. , channel fully on). For example, in one respect, considering for the moment a three-channel lighting unit based on red, green and blue LEDs (ie, an “R-GB” lighting unit), a lighting command in the DMX protocol can specify each of a red channel command, a green channel command, and a blue channel command as eight-bit data (that is, one byte of data) representing a value from 0 to 255. The maximum value of 255 for any one of the color channels instructs the processor 102 to control the corresponding light source (s) to operate at the maximum available power (i.e., 100%) for the channel, thereby generating the maximum radiant power available for that color (such a command structure for an RGB lighting unit is commonly called 24-bit color control). Thus, a command of the format [R, G, B] = [255, 255, 255] would cause the lighting unit to generate the maximum radiant power for each of red, green and blue light (thereby creating white light). .

Thus, a given communication link employing the DMX protocol can conventionally support up to 512 different lighting unit channels. A given lighting unit designed to receive communications formatted in the DMX protocol is generally configured to respond only to one or more bytes of particular data out of the 512 bytes in the packet corresponding to the number of channels of the lighting unit (for example, in the example of a three-channel lighting unit, three bytes are used for the lighting unit), and ignore the other bytes, based on a particular position of the desired data byte (s) in the overall sequence of the 512 data bytes in the packet. To this end, DMX-based lighting units can be equipped with an address selection mechanism that can be manually adjusted by a user / installer to determine the particular position of the data byte (s) to which the control unit responds. lighting in a given DMX package.

It should be appreciated, however, that the lighting units suitable for the purposes of the present description are not limited to a DMX-type command format, as the lighting units according to various embodiments may be configured to respond to other types of protocols. communication / lighting command formats so that their respective light sources are controlled. In general, processor 102 may be configured to respond to lighting commands in a variety of formats expressing recommended operating powers for each different channel of a multichannel lighting unit on some scale representing zero to maximum available operating power. for each channel.

ES 2 348 841 T3

For example, in another embodiment, the processor 102 of a given lighting unit may be configured to interpret lighting data / instructions that are received in a conventional Ethernet protocol (or similar protocol based on Ethernet concepts). Ethernet is a popular computer networking technology often used for local area networks (LANs) that defines cabling and signaling requirements for the interconnected devices that make up the network, as well as frame formats and protocols for data transmitted over the network. . Devices attached to the network have respective unique addresses, and the data for one or more addressable devices on the network is organized as packets. Each Ethernet packet includes a "header" that specifies a destination address (where the packet is going) and a source address (where the packet is coming from), followed by a "payload" that includes several bytes of data (for example , in the type II Ethernet frame protocol, the payload can be from 46 bytes of data to 1500 bytes of data). A packet ends with an error correction code or "checksum". As with the DMX protocol discussed above, the payload of successive Ethernet packets intended for a given lighting unit configured to receive communications on an Ethernet protocol may include information representing respective recommended radiant powers for different available light spectra (e.g. different color channels) that can be generated by the lighting unit.

In yet another embodiment, the processor 102 of a given lighting unit may be configured to interpret lighting data / instructions that are received in a serial communication protocol as described, for example, in US Patent No. 6,777. .891. In particular, according to one embodiment based on a serial base communication protocol, multiple lighting units 100 are coupled together through their communication ports 120 to form a series connection of lighting units (e.g., a topology in ring or daisy chain), in which each lighting unit has an input communication port and an output communication port. The lighting data / instructions transmitted to the lighting units are arranged sequentially based on a relative position in the series connection of each lighting unit. It should be appreciated that although a lighting network is analyzed based on a series interconnection of lighting units, particularly in relation to an embodiment employing a serial communication protocol, the description is not limited in this regard, as they are further discussed below other examples of lighting network topologies contemplated by the present description, in relation to figure 3.

In one embodiment employing a serial communication protocol, as the processor 102 of each lighting unit in the serial connection receives data, it "removes" or extracts one or more initial parts of the data stream intended to do so and transmits the remainder of the data stream to the next lighting unit in the serial connection. For example, again considering a serial interconnection of multiple three-channel lighting units (eg "RGB"), three multi-bit values ​​(one multi-bit value per channel) are extracted for each three-channel lighting unit. channels of the received data stream. Each lighting unit in the serial connection in turn repeats this procedure, namely, removing or extracting one or more initial parts (multi-bit values) from a received data sequence and transmitting the remainder of the sequence. The initial part of a data stream that each lighting unit in turn removes may include respective recommended radiant powers for different available light spectra (eg, different color channels) that can be generated by the lighting unit. As discussed above in connection with the DMX protocol, in various implementations each multi-bit value per channel can be an 8-bit value, or another number of bits (eg, 12, 16, 24, etc.) per channel. , depending in part on a desired control resolution for each channel.

In yet another exemplary implementation of a serial communication protocol, instead of removing an initial portion of a received data stream, an indicator is associated with each portion of a data stream that represents data for multiple channels of a given lighting unit, and a complete data sequence for multiple lighting units is completely transmitted from one lighting unit to another in the serial connection. When a lighting unit in the serial connection receives the data stream, it examines the first part of the data stream in which the indicator indicates that a given part (representing one or more channels) has not yet been read by any unit lighting. Upon finding such a part, the lighting unit reads and processes the part to provide a corresponding light emission, and sets the corresponding flag to indicate that the part has been read. Again, the entire data stream is transmitted entirely from one lighting unit to another, with the status of the indicators indicating the next part of the data stream available for reading and processing.

In an embodiment related to a serial communication protocol, the controller 105 a given lighting unit configured for a serial communication protocol may be implemented as an application specific integrated circuit (ASIC) designed to specifically process a stream of data / instructions. of lighting received according to the process of "elimination / data extraction" or process of "modification with indicator" previously analyzed. More specifically, in an exemplary embodiment of multiple lighting units coupled together in serial interconnection to form a network, each lighting unit includes an ASIC-implemented controller 105 that has the functionality of processor 102, memory 114, and the communication port (s) 120 shown in Figure 1 (of course it is not necessary to include the user interface 118 and optional signal source 124 in some implementations). Such an implementation is discussed in detail in US Patent No. 6,777,891.

In one embodiment, light source 104 may include and / or be coupled to one or more power sources 108. In various respects, examples of power supply (s) 108 include, but are not limited to, power supplies.

ES 2 348 841 T3 AC planting, DC power sources, batteries, solar power sources, thermoelectric or mechanical power sources and the like. Additionally, in one aspect, the power source (s) 108 may include or be associated with one or more power conversion devices or power conversion circuitry (e.g., in some cases internal to the light source 104) that convert the power received by an external power source into a form suitable for the operation of the various internal circuit components and light sources of the light source 104. In an exemplary implementation discussed in US Patent No. 7,256,554, entitled "LED Power Control Methods and Apparatus"; Light source 104 controller 105 may be configured to accept a conventional AC line voltage from power source 108 and provide appropriate DC operating power for light sources and other unit circuitry. based on concepts related to DC-DC conversion, or concepts of “switching” of the power supply. In one aspect of such implementations, the controller 105 may include circuitry not only to accept a conventional AC line voltage but to ensure that power is drawn from the line voltage with a significantly high power factor.

FIG. 2 illustrates an example of a network lighting system 200 according to one embodiment of the present disclosure. In the embodiment of Figure 2, several lighting units 100, similar to those discussed above in connection with Figure 1, are coupled together to form the networked lighting system. It should be appreciated, however, that the particular configuration and arrangement of the lighting units shown in Figure 2 is for illustration purposes only, and that the description is not limited to the particular system topology shown in Figure 2.

Additionally, although not explicitly shown in Figure 2, it should be appreciated that the network lighting system 200 may be flexibly configured to include one or more user interfaces, as well as one or more signal sources such as sensors / transducers. . For example, one or more user interfaces and / or one or more signal sources such as sensors / transducers (as discussed above in connection with Figure 1) may be associated with any one or more of the lighting units of the device. network lighting system 200. Alternatively (or in addition to the above), one or more user interfaces and / or one or more signal sources may be implemented as "stand-alone" components in the network lighting system 200. Whether they are stand-alone components or particularly associated with one or more lighting units 100, these devices can be "shared" by the lighting units of the networked lighting system. Stated differently, one or more user interfaces and / or one or more signal sources such as sensors / transducers can constitute "shared resources" in the networked lighting system that can be used in connection with the control of any one or more. more than the lighting units in the system.

As shown in the embodiment of Figure 2, the lighting system 200 may include one or more lighting unit controllers 208A, 208B, 208C and 208D (hereinafter "LUC", light unit controller), wherein each LUC is responsible for communicating with and generally controlling one or more lighting units 100 coupled thereto. Although Figure 2 illustrates a lighting unit 100 coupled to each LUC, it should be appreciated that the description is not limited in this regard, as different numbers of lighting units 100 can be coupled to a given LUC in a variety of different configurations (connections serial, parallel connections, combinations of serial and parallel connections, etc.) using a variety of different media communication and protocols.

In the system of Figure 2, each LUC may in turn be coupled to a central controller 202 that is configured to communicate with one or more LUCs. Although Figure 2 shows four LUCs coupled to the central controller 202 via a generic connection 212 (which may include any number of a variety of conventional coupling, switching and / or networking devices), it should be appreciated that according to various embodiments, different numbers of LUCs may be coupled to the central controller 202. Additionally, according to various embodiments of the present disclosure, the LUCs and the central controller can be coupled together in a variety of configurations using a variety of different protocols and communication means to form the networked lighting system 200. Furthermore, it should be appreciated that the interconnection of the LUC and the central controller, and the interconnection of lighting units to respective LUCs, can be achieved in different ways (eg, using different configurations, communication media and protocols).

For example, in accordance with one embodiment of the present disclosure, the central controller 202 shown in Figure 2 may be configured to implement Ethernet-based communications with the LUCs, and the LUCs may in turn be configured to implement a communications-based protocol. Ethernet, DMX-based or serial with 100 lighting units (as discussed above, Exemplary serial protocols suitable for various network implementations are discussed in detail in US Patent No. 6,777,891. In particular, in one aspect of this embodiment, each LUC may be configured as an addressable Ethernet-based controller and, consequently, may be identifiable to the central controller 202 via a particular unique address (or a unique group of addresses and / or other identifiers) using an Ethernet-based protocol. In this way, the central controller 202 can be configured to support Ethernet-type communications throughout the network of coupled LUCs, and each LUC can respond to those communications designed for it. In turn, each LUC can communicate lighting control information to one or more lighting units attached to it, for example, via an Ethernet-based, DMX, or serial protocol, in response to Ethernet-type communications with the central controller 202 (in which the lighting units are appropriately configured to interpret information received from the LUCs in Ethernet, DMX or serial based protocols).

ES 2 348 841 T3

The LUC 208A, 208B, and 208C shown in Figure 2 may be configured to be "smart", the central controller 202 may be configured to communicate higher-level commands than the LUC that need to be interpreted by the LUCs before the information can be retransmitted. of lighting control to the lighting units 100. For example, a lighting system operator may want to generate a color-changing effect that varies colors from one lighting unit to another in such a way as to create the appearance of a spreading rainbow of colors ("chasing rainbow ”), given a particular placement of lighting units with respect to each other. In this example, the operator can provide a simple instruction to the central controller 202 to do this, and in turn the central controller can communicate it to one or more LUCs using a high-level Ethernet-based protocol command to generate an "arc chase." iris". The command may contain timing, intensity, hue, saturation, or other relevant information, for example. When a given LUC receives such a command, it can then interpret the command and communicate additional commands to one or more lighting units using any one of a variety of protocols (e.g., Ethernet-based, DMX, serial), in The answer is that the lighting units' respective sources are controlled through any of a variety of signaling techniques (eg, PWM).

In addition, one or more LUCs of a lighting network may be coupled to a series connection of multiple lighting units 100 (for example, see LUC 208A of Figure 2, which is coupled to two series-connected lighting units 100 ). For example, each LUC coupled in this manner is configured to communicate with the multiple lighting units using a serial communication protocol, examples of which were discussed above. More specifically, in an exemplary implementation, a given LUC may be configured to communicate with a central controller 202, and / or one or more other LUCs, using an Ethernet-based protocol, and in turn communicate with the multiple units. lighting using a serial communication protocol. In this way, a LUC can be viewed in a sense as a protocol converter that receives data or lighting instructions in the Ethernet-based protocol, and passes the instructions to multiple serial-connected lighting units using the serial protocol. Naturally, in other network implementations involving DMX-based lighting units arranged in a variety of possible topologies, it should be appreciated that a given LUC can be similarly thought of as a protocol converter that receives data or lighting instructions on the Ethernet protocol. , and passes the instructions formatted in a DMX protocol.

It should be appreciated again that the above example of use of multiple different communication implementations (eg Ethernet / DMX) in a lighting system according to one embodiment of the present description is for the purpose of illustration only, and that the description is not limited. to this particular example.

From the foregoing, it can be appreciated that one or more lighting units as discussed above can generate highly controllable variable color light in a wide range of colors, as well as white light of variable color temperature in a wide range of temperatures. color.

As discussed previously, it is often useful to consider connecting multiple lighting units or light sources (eg LEDs) to receive operating power in series rather than in parallel. A series interconnection of multiple LEDs can allow the use of operating voltages that are significantly higher than typical LED forward voltages, and can also allow the operation of multiple LEDs or LED-based lighting units without requiring a transformer between a source. power supplies (for example, line voltage or wall power such as 120 VAC or 240 VAC) and loads (that is, multiple loads connected in series can be operated "directly" from one line voltage).

Accordingly, other embodiments of the present invention generally relate to methods and apparatus for controlling LED-based light sources, wherein respective elements of a multi-element light source, and / or multiple light sources themselves, they are coupled in series to receive operating power. In various embodiments discussed further below, it should be appreciated that virtually any appropriate number of LEDs or LED-based lighting units may be coupled in series depending at least in part on the rated operating voltage of each LED or lighting unit, and the voltage expected nominal supply supply provided by an available power supply. For the purposes of the discussion below, various concepts related to series-connected LEDs are discussed first; however, it should be appreciated that many, if not all, of the concepts discussed herein can be similarly applied to various arrays of LEDs (series, parallel, and / or series / parallel arrangements), as well as multiple units. LED-based lighting fixtures, which are coupled in series to receive operating power.

FIG. 3 is a block diagram of an LED-based lighting apparatus 100A that includes multiple LEDs connected in series, according to one embodiment of the present invention. In the apparatus of Figure 3, multiple LEDs are nominally connected in series between a first node 108A and a second node 108B to which an operating voltage is applied (a power source 108 was discussed generally above in relation to with Figure 1) to form a "stack" of devices connected in series. For the purposes of the following discussion, the position of one or more LEDs in the "stack" of devices connected in series, with respect to one of the two voltage potentials applied respectively to the first and second nodes, is called the "height" in the "stacking".

In Figure 3, a first light source 104B (represented by a single LED for illustration purposes) is shown at a first height in the stack, and a second light source 104A (again represented by a single

ES 2 348 841 T3

LED for illustration purposes) is displayed at a second height in the stack. Although Figure 3 illustrates an exemplary apparatus with two light sources, as noted above it should be appreciated that the present invention is not limited in this regard as virtually any number of light sources can be connected in series in one given apparatus. Figure 3 also shows a current source 310 connected in series with the LEDs between the first and second nodes; In one aspect, current source 310 sets a series current (I_six) that flows between the first and second nodes, through one or more of the series-connected LEDs, when operating voltage is applied across the first and second nodes.

As discussed above in connection with Figure 1, in various implementations the light sources 104A and 104B of apparatus 100A shown in Figure 3 may each include a single LED or multiple LEDs (eg, interconnected in a parallel arrangement). . Additionally, light sources 104A and 104B can generate radiation having similar or nearly identical spectra (eg, constituting colored or essentially white light), or light sources 104A and 104B can respectively generate different spectra. Accordingly, at each different height in the stack of serially connected devices, in different implementations one or more LEDs may be employed; furthermore, different colored light spectra (or different white light color temperatures) can be generated at different heights in the stack, or essentially the same light spectrum can be generated at each height in the stack. Again, for purposes of illustration in the discussion that follows, each of the light sources 104A and 104B in Figure 3 is simply referred to as an LED, although it should be appreciated that various implementations of the present invention are not limited to having a single LEDs at each height in the stack of devices connected in series.

As also shown in FIG. 3, apparatus 100A includes one or more controllable current paths 312A and 312B (abbreviated as "CCP", controllable current path) connected in parallel with one or more of the LEDs connected in series. In various respects, the controllable current paths can be implemented as controllable switches to completely divert the series current I_six around a given LED, or as controllable fixed or variable current sources configured to divert all or only a portion of the series current around the given LED. In this way, the brightness of a given LED can be controlled and, in the extreme, the LED can be turned off completely by diverting the current completely around it. Although Figure 3 illustrates a one-to-one correspondence between controllable current paths 312A and 312B and LEDs 104A and 104B, it should be appreciated that the invention is not limited in this regard. In particular, according to various embodiments discussed further below, it is not necessary for each LED in the series connection to be associated with a dedicated / corresponding controllable current path; rather, in some implementations, no controllable current path may be associated with one or more LEDs of the series connection, and / or a given controllable current path may be associated with multiple LEDs of the series connection.

In another aspect of the embodiment shown in FIG. 3, apparatus 100A includes a controller 105A configured to control one or more controllable current paths 312A and 312B via respective control signals 314A and 314B. In Figure 3, the controller is shown coupled to the operating voltage applied across the first and second nodes so that operating power is obtained. Alternatively, the controller 105A may be coupled in series with the current source 310 and the LEDs connected in series so that operating power is obtained. In one implementation, controller 105A may operate one or more controllable current paths 312A and 312B based on data received as lighting instructions through one or more communication ports 120A (as discussed above in connection with Figures 1 and 4). 2). To this end, the controller may be configured to respond to a serial data protocol, and include at least two communication ports (for example, a data input port and a data output port) to facilitate communication of serial data between respective controllers of multiple lighting fixtures similar to fixture 100A.

In another implementation, the controller 105A may be configured to operate one or more controllable current paths based on one or more measured parameters related to the available operating voltage applied across the first and second nodes 108A and 108B. More specifically, in one embodiment, the ability to partially or fully divert current around one or more series-connected LEDs is employed in circumstances where a nominal expected operating voltage applied across the first and second nodes decreases below of a minimum operating voltage necessary to activate all devices connected in series. In various implementations, this minimum operating voltage may depend at least in part on the number and type of LEDs used in the series connected stack of devices and, more specifically, the respective forward operating voltages of the individual LEDs used in the stack.

In view of the foregoing, in one embodiment the controller 105A of apparatus 100A shown in Figure 3 controls one or more of the controllable current paths based at least in part on one or more monitored parameters representative of an available operating voltage for the LEDs connected in series. From the monitored parameter (s), the controller determines a maximum number of series-connected LEDs that can be driven by the operating voltage, and controls one or more of the controllable current paths so as to increase the amount of series current that is shunted around one or more of the series-connected LEDs when the maximum number is less than the total number of all series-connected LEDs. For example, in one implementation, the controllable current paths can be switches that completely divert the current around a corresponding LED so that it essentially short-circuits the LED and causes it.

ES 2 348 841 T3 remove devices from serial connection. In this way, the operating voltage required to operate the remaining series connected LEDs is reduced by the individual (direct) operating voltage of each LED that is short-circuited due to current deviation.

In some exemplary implementations, the controller may be configured to control one or more of the controllable current paths so as to increase the amount of current that is shunted around a corresponding LED (e.g., shorting the corresponding LED) when The monitored parameter (s) indicate that the operating voltage is below a predetermined threshold value. In one aspect, the predetermined threshold value may represent a minimum operating voltage necessary to activate all series-connected LEDs in a given fixture and thus may depend at least in part on the number of LEDs in a given fixture and the respective forward voltages of the LEDs. Also, if at any point the operating voltage falls below a certain predetermined threshold value and then rises above the threshold value, the controller can appropriately control one or more of the controllable current paths to add one or more "shorted" LEDs of new in the stack connected in series so that they are activated by the current in series. More generally, through the monitored parameter (s) representative (s) of the operating voltage, the controller can make a determination (and can do so practically continuously or periodically) as to the number LEDs that can be activated effectively based on the available operating voltage at any given time, and consequently control one or more controllable current paths to activate all or fewer than all series connected LEDs on the fixture. As discussed further below, controller 105A may implement a variety of control strategies to statically or dynamically control one or more of the controllable current paths for a given period of time and / or a variety of voltage conditions. of operation.

In still other aspects of the apparatus 100A shown in FIG. 3, the current source 310 may be a fixed current source (i.e., the value of the series current I_six), or the current source may be a controllable current source such that the series current I_Serie It is variable. To this end, in one embodiment the controller 105A may further control the current source 310, as indicated by the shaded control connection 315 shown in FIG. 3. In various aspects, the controller may control the current source to set the series current based at least in part on the monitored parameter (s) representing the operating voltage, and to increase or decrease series current based on changes in available operating voltage according to any of a variety of relationships (eg, proportional, inversely proportional, etc.). For example, the controller may be configured to control the current source so that the series current increases as the operating voltage decreases so that an essentially constant brightness of the light generated by the powered LEDs of the apparatus is maintained. Controller 105A may also change the value of the series current to reduce brightness, or otherwise change the series current based on a change in operating voltage. Controller 105A can effect various dynamic relationships between series current and operating voltage; For example, in one implementation, the series current can be slowly reduced as the operating voltage decreases, but then increased by a certain amount (eg 25%) when the LED shorting process begins. In this way, there would be no sudden decrease in overall brightness as the operating voltage decreases. In yet another aspect, controller 105A may control current source 310 so that it modulates the series current per duty cycle, to provide either fixed or variable average series current.

FIG. 4 is a diagram illustrating an exemplary circuit implementation of the apparatus 100A shown in FIG. 3, in accordance with one embodiment of the present invention. In one aspect of this embodiment, the apparatus of Figure 4 is particularly suitable for automotive lighting applications where the expected nominal operating voltages are in the range of about 12 to 14.5 volts. In particular, in automotive applications based on an electrical system that includes a conventional 12-volt car battery, the operating voltage available to automotive accessories when the engine is running and the electrical system is charging, is typically between 13 , 8 and 14.5 volts; However, when the engine is not running, the available operating voltage can be rapidly reduced to 12 to 12.8 volts, or even lower (for example, when high loads are present, and / or as the load is further discharged). car battery). With the above in mind, consider a lighting fixture similar to that shown in figure 3, in which four LEDs connected in series are used, each having a forward voltage of approximately 3.0 to 3.3 volts (for example, based on GaN technology), such that a series connected stack of the four LEDs, plus a current source in series with the LEDs, requires an operating voltage of approximately 13.0 to 13.5 volts . In one aspect, an apparatus configured in this way is based on a "constant area cost" principle; Specifically, an LED half-conductor structure of a fixed size costs a fixed amount equally to implement, regardless of how many sections it may be divided into. Therefore, if an LED semiconductor structure is divided into four sections that are then connected in series, a device results that is essentially the same cost as an LED, operates at a quarter of the current and has an operating voltage of four times the forward voltage of a single LED.

Naturally, for automotive applications as discussed above, a series-connected LED-based lighting apparatus needs to take into account the full range of possible available operating voltages; that is, if the available operating voltage from the car's electrical system drops below about 13.0 to 13.5 volts, there may not be enough voltage to power all four

ES 2 348 841 T3

LEDs connected in series. To this end, in the circuit of Figure 4, four series-connected LEDs 104A - 104 D are employed together with four controllable current paths 312A-312D, in parallel with the LEDs in a one-to-one correspondence, and responding to Corresponding control signals 314A-314D provided by controller 105A. In Figure 4, the controllable current paths are implemented as single-pole single-throw (SPST) switches SW1 - SW4 so that the series current I is shunted._Seriearound the corresponding LEDs. The current source 310 is implemented by the operational amplifier U7A, the N-type field-effect transistor Q35, and the resistor r41. In the circuit of Figure 4, the current source 310 is not under the control of the controller 105a, but rather the series current I_Serie provided by current source 310 tracks the operating voltage through the voltage divider formed by resistors R43 and R42.

As discussed above in connection with Figure 3, the controller 105A in the Figure 4 circuit (U8) can be coupled between the first and second nodes 108A and 108B to derive operating power directly from the applied operating voltage. to these nodes. Additionally, the controller may optionally include a first communication port 120A and a second communication port 120B for transmitting and receiving data representing various information, as discussed further below. As also discussed above in connection with FIG. 3, the controller 105 in the FIG. 4 circuit can implement a variety of control techniques to operate the controllable current paths formed by the switches SW1-SW4.

For example, as the operating voltage applied to the first and second nodes 108A and 108B decreases below a level required to properly activate all four LEDs 104A-104D, the controller 105A can begin by controlling switches SW1-SW4 so one LED being shorted at one time (for example, in a timed sequence) such that all LEDs appear to remain on to an observer; Stated differently, as the operating voltage decreases to a level that is insufficient to properly power the four LEDs connected in series, only three or less of the LEDs are turned on simultaneously at any given time. In this way, the controller intermittently shunts the series current around the respective LEDs. In one aspect, different clusters of less than four LEDs are activated in succession in a manner that is generally unnoticeable to an observer. In another aspect, more than one LED can be shorted at the same time to allow for further reductions in operating voltage while still generating light from the fixture (for example, only two LEDs can be activated at any given time, with different groups of two LEDs activated in succession at an appropriate speed so that it is generally imperceptible to an observer).

In the circuit of Figure 4, controller 105A may employ any one or more of several techniques to monitor one or more parameters representative of the operating voltage applied between nodes 108A and 108B, and determine an appropriate number of LEDs that can be activated. so that the controllable current paths implemented by the switches SW1-SW4 are effectively controlled. To this end, controller 105A may include one or more inputs to receive signals to monitor one or more of the operating voltage itself (through line 324), a drain voltage from FET Q35 (through line 320 ), and a gate voltage from FET Q35 (through line 322).

In one example, the controller 105A monitors both the gate voltage and the drain voltage of the FET Q35, in which a relatively higher gate voltage indicates that the operating voltage has dropped and there may be a need to short-circuit one. or more LEDs, while a relatively higher drain voltage indicates that the operating voltage has dropped and it may be possible to short-circuit fewer LEDs. For example, in a particular implementation based on a nominal expected operating voltage of about 13.5-14.5 volts (e.g. automotive applications), and a 100A fixture that includes four series-connected LEDs, a gate voltage approximately 4 volts indicates that the operating voltage has dropped to a value where it is necessary to short-circuit at least one LED, and a drain voltage of approximately 5 volts indicates sufficient operating voltage to include all four LEDs in the series connected stack. In another example, the controller 105A monitors only one of the gate and drain voltage of the FET Q35, and relies on the precise detection of high and low drain voltages to make the decision, or the speculative operation of the switches to determine the correct number of LEDs to be shorted. In yet another example, the controller 105A may directly monitor the operating voltage, and employ a predictive strategy in which the monitored operating voltage is mapped directly to a number of shorted LEDs. To this end, in one embodiment the controller may employ one or more predetermined threshold values, and as the operating voltage is reduced below a given predetermined threshold value, one or more LEDs are required to be shorted. Various other techniques can be used, including indirectly estimating the drain, source, and / or gate voltage of the FET Q35, with the goal of determining the correct number of LEDs to be shorted.

Although controller 105A does not control current source 310 in the circuit of Figure 4, those of ordinary skill in the art will readily appreciate that, as discussed above in connection with Figure 3, other circuit implementations may be made in which the 105A controller can also change the value of the series current flowing through the row of activated LEDs, and can modulate the current source by duty cycle, to maintain the overall brightness of the generated light, reduce the brightness, or otherwise change some aspect of

ES 2 348 841 T3 operation of the apparatus based on a change in operating voltage. Furthermore, in alternative implementations of apparatus 100A generally based on the circuit architecture shown in Figure 4, the current source may be implemented in any one of a number of ways known to those of ordinary skill in the relevant arts, including circuits employing one or more operational amplifiers, and non-p-type transistors such as BJTs or FETs. Also, the controllable current paths 312A-312D implemented as switches SW1-SW4 can be of various designs.

For example, Figures 5A to 5D illustrate four circuits by way of non-limiting example, any one of which may be used to implement the switches SW1-SW4 shown in Figure 4. For illustration purposes, the circuit diagrams in Figures 5A-5D represent four different possibilities for switch SW4 (controllable current path 312A) shown in Figure 4, in which nodes 313A and 313B for connection along of the LEDs 104A are indicated in the figures. It should be appreciated that any one of the switch designs shown in Figures 5A-5D may be employed for any one or more of the switches SW1-SW4 shown in Figure 4. As with the different implementations of the current source 310, the switches they may include one or both of non-p-type devices. In other aspects, a capacitive charge pump or boost capacitor architecture may be employed to increase the available switch gate voltages.

Although in one implementation the controller 105A of Figure 4 may successively control different, or multiple different switches, of the switches SW1-SW4 intermittently, as discussed above it should be appreciated that various control techniques can be implemented by the controller 105A according to various embodiments so that controllable current paths are controlled. For example, current paths can be controlled sequentially, in some random or predetermined order, and on a variety of time scales. Naturally, as indicated above, in one implementation the speed at which the different current paths are controlled can be selected to be sufficiently fast than the speed at which a normal observer can distinguish perceptible differences in the characteristics of light (for example, greater than about 50 - 60 Hz). In other lighting apparatus embodiments similar to those shown in Figures 3 and 4, a lighting apparatus may include one or more optical elements (for example, as discussed above in connection with Figure 1) for mixing, diffusing, combine or otherwise optically process the light generated by the respective LEDs, such that the resulting perceived light is relatively independent of which particular LEDs are activated at any given time.

Additionally, for some applications of apparatus 100A shown in Figures 3 and 4, periodic, sequential, or intermittent operation of the controllable current paths may not be necessary to switch one or more LEDs in and out of the series connected stack, or bypass otherwise some part of the current around one or more LEDs; For example, there may be some applications where it is acceptable to simply choose a particular operating state (for example, a certain number of activated LEDs) based on the operating voltage available at any given time, and maintain that state for a certain period of time. or indefinitely. To this end, it should be appreciated whether or not some type of static or dynamic control technique is employed for the controllable current paths, two or more current paths may be controlled simultaneously. Also, the available operating voltage can be monitored / sampled at any of a variety of ranges, and various control techniques implemented based on the sampled operating voltage.

In other aspects of the apparatus shown in Figure 4, it should be appreciated that for some applications (including automotive applications and other applications), not all switches SW1-SW4 may be necessary (that is, it is not necessary that the short-circuit may necessarily be caused of all LEDs connected in series). For example, in conventional automotive electrical systems, it may only be necessary to have the ability to short-circuit two or three LEDs of the four LEDs connected in series if operating voltages substantially less than 10 to 12 are not routinely expected. volts, or even as low as 5 volts. Stated differently, as discussed above in connection with Figure 3, it may be acceptable in some implementations to have one or more LEDs of the stack connected in series that are not associated with a corresponding controllable current path, and remain in the stack. (and on) at lower operating voltages, thereby further reducing the number of controllable current paths required.

In yet another aspect, the controller 105A may be configured to control the controllable current paths or switches SW1-SW4 such that the overall appearance of the generated light changes perceptibly to an observer when the operating voltage is insufficient to operate all. LEDs in series connected stack; that is, it may be useful and / or desirable to make an observer aware of the reduced operating voltage through a perceptible change in the quality (eg, brightness) of the light generated. If LEDs of different colors are used, this type of indication can be quite visible (that is, changes in light quality due to changes in operating voltage can imply brightness and color).

As also discussed above in connection with FIG. 3, it should generally be appreciated that the LEDs of the apparatus 100A shown in FIG. 4 may be of the same color (or color temperature of white) or of different colors (or different temperatures of white). color of white). In one embodiment, the physical arrangement of LEDs of different colors or color temperature in a given apparatus, and / or the control technique implemented by controller 105A, can benefit from the use of LEDs of different colors or different color temperatures to create various effects

ES 2 348 841 T3 for lighting. More generally, the plurality of LEDs connected in series may include at least one first LED for generating a first radiation having a first spectrum, and at least one second LED for generating a second radiation having a second spectrum different from the first spectrum. , and the controller may control the controllable current paths in a predetermined manner based at least in part on the different spectra of the LEDs.

In an exemplary implementation, the first LED may include a first white LED, such that the first spectrum corresponds to a first color temperature, and the second LED may include a second white LED, such that the second spectrum corresponds to a second color temperature different from the first color temperature. In one aspect, the controller can control the controllable current paths such that the overall color temperature of the light generated by the apparatus, based on at least one of the first spectrum and the second spectrum, decreases as the voltage decreases. of operation. For example, if warm white LEDs are used in some positions and cool white LEDs are used in others, then the controller may be configured to preferably keep the warm LEDs on as the operating voltage is reduced to mimic the effect produced by a incandescent light bulb. If the light output from respective activated LEDs is sufficiently mixed optically, the switching action can be quite abrupt, and still create the desired quality of light output. In other respects, it may be desirable to have control over the series current provided by current source 310, and / or deliberately short-circuit LEDs occasionally, even when there is enough operating voltage to operate all LEDs in the stack. connected in series, to achieve color adjustment, color temperature and / or brightness resulting from the generated light.

Although four LEDs connected in series are shown in the apparatus of Figure 4, the apparatus is not limited in this regard, as embodiments with fewer (just two) or more than four LEDs are contemplated according to the present disclosure, as discussed. discussed above in relation to Figure 3. More generally, it should be appreciated that although an example of an automotive application was provided above in connection with the apparatus shown in Figure 4, various implementations of the present invention are not necessarily limited to automotive applications or the particular range of voltages. contemplated operating conditions for such applications. In one aspect, the number of LEDs connected in series in an apparatus having construction and functionality similar to that shown in Figures 3 and 4 may be dictated in part by the nominal operating voltage and the range of operating voltages expected in an application. Dadaist. For example, although four LEDs each having a forward voltage of approximately 3.0 to 3.3 volts may be particularly suitable for operating voltages of approximately 13.0 to 14.5 volts (e.g., as shown found in automotive applications), a fixture based on two LEDs each having a forward voltage of 2.5 to 3 VDC may be particularly suitable for applications involving operating voltages of 6 to 9 VDC, and an apparatus having seven LEDs connected in series may be particularly suitable for applications involving operating voltages of about 24 volts. Again, apparatus according to the present invention that includes any number of LEDs can be contemplated for virtually any range of operating voltage expected for a variety of applications.

As also discussed above in connection with Figure 3, more than one LED can be controlled by a given controllable current path, including groups of LEDs connected in parallel at a given height in the series connected stack, or having a single Controllable current path that controls LEDs at two or more heights in the series connected stack (in which, at each height, there may be one or more LEDs). Naturally, it should be appreciated that as the number of LEDs per controlled group increases (for example, at a given height in the stack), the differential brightness of light generated by the apparatus increases as the current is diverted around different heights. in stacking. For example, in an implementation based on a 24 volt operating voltage, a fixture may comprise seven series-connected LEDs and only five controllable current paths, in which the LEDs are arranged as three controllable groups of two series-connected LEDs. , in series with two individually controllable LEDs. In other implementations based on different controllable clusters of LEDs, odd and even number clusters of LEDs at respective heights may be implemented in the series connected stack such that the overall brightness of the light generated by an apparatus can be adjusted in increments of one. LEDs (i.e. without having any height in the stack with only a single controllable LED). Furthermore, in some embodiments, it is not necessary for all LEDs used in a series connected stack to be controllable with respect to current offset, as also discussed earlier in connection with Figure 3. In an implementation based on one or more 'fixed' (non-controllable) LEDs in a series connected stack (where the uncontrolled LEDs generally supply more light than the other controlled LEDs that are supposed to turn off in some circumstances), the physical organization of LEDs in a realized device can be tailored to optimize optical efficiency (for example, uncontrolled LEDs can be centered within the optical system).

In yet another embodiment, a lighting apparatus similar to that shown in Figures 3 and 4, based on multiple LEDs connected in series, one or more controllable current paths connected in parallel with one or more of the LEDs connected in series; and a controller for controlling one or more of the controllable current paths, can be implemented as one or more integrated circuits. In addition, integrated circuit implementations can be appropriately packaged for ease of installation, deployment, and / or use in any one of several applications, including those applications where conventional operating voltages are readily available.

ES 2 348 841 T3

For example, in an embodiment related to the apparatus shown in Figure 4, particularly in relation to automotive lighting applications, the apparatus may be implemented as one or more integrated circuits and included in a package that facilitates installation and use in a car environment. To this end, all the components of the circuitry shown in Figure 4 can be implemented on a single integrated circuit chip, or the LEDs can be implemented on one chip and the associated control circuitry implemented on another chip and stacked with the LED chip. In typical manufacturing techniques, LEDs are first attached to a "subassembly" which is often a semiconductor device, typically with reverse bias protection diodes, or Zener diodes to prevent device failure due to high voltages or currents. transitory. The circuit assemblies shown in Figure 4 can be fully integrated, and require very low capacitance for operation; therefore, the LEDs and associated circuitry can be fully integrated.

An automobile lighting apparatus according to an embodiment of the present invention, based on the circuit of Figure 4, may further include a package for one or more integrated circuit chips in which the circuit is implemented. Figure 6 illustrates very generally an exemplary package 400 for such a lighting apparatus, wherein the package includes one or more integrated circuit chips 404 in which the apparatus 100A is implemented, one or more optical elements 402 (for example, a lens) to protect the chip (s) and allow the emission of light, and at least one electrical connector 406. In one aspect, electrical connector 406 is configured to mate with a complementary electrical connector 408 coupled to an automobile wire harness 410. In another aspect, electrical connector 406 (as well as electrical connector 408) may include a first conductor 406A electrically connected to first node 108A to which operating voltage is applied, and a second conductor 406B electrically connected to second node 108B to which operating voltage is applied. A wide variety of electrical connectors suitable for automotive applications are known in the relevant arts and are contemplated for various implementations of the lighting apparatus shown in Figure 6.

Accordingly, in an exemplary implementation, a complete package for an automotive lighting apparatus may include four series-connected LEDs and associated control circuitry on one or more integrated circuit chips, grouped under a lens in a a two conductor package, and having an overall operating power in the order of 0.5 to 5 watts.

In still other aspects, the package 400 shown in Figure 6 may include other components, typical examples of which include, but are not limited to, one or more resistors for setting current or current / voltage characteristics, small capacitors for further reduction of IEM, and possibly other filtering or protection components including inductors, capacitors, Zener diodes, etc. The 400 package can also be provided with extra conductors or a conductor rack with other features, such as mounting holes similar to those used in power transistors (for example, the TO-220 or TO-247 package), or anchor zones. retaining clip. The additional conductors can be used for a variety of purposes, including mode or current setting, communications (if such features are added to the control circuit), calibration, or fault detection and determination.

More specifically, since the control circuitry associated with the LEDs in the apparatus of Figure 4 can be manufactured as a substrate for the LEDs, and such substrates can have a minimum size that may be larger than the size necessary to implement the LEDs. own control circuitry, other functions may also be included. Thus, in another embodiment, controller 105A may implement a variety of functions in addition to control of the controllable current paths and / or current source. In this way, significant functionality can be included in such lighting fixtures with a relatively small increase in cost over the cost of producing a typical packaged LED.

For example, as discussed above in connection with Figures 3 and 4, controller 105A may include one or more communication ports (eg, 120A and 120B shown in Figure 4) for receiving and / or transmitting information. Referring again to Figure 6, the electrical connector 406 of the package 400 may include a third conductor 406C electrically connected to the communication port (s), such that the controller can receive a first information through the third driver and at least one of the communication ports. Also, in one embodiment the controller may include a memory for storing second information, and may transmit at least part of the second information from at least one communication port through the third conductor to the automotive wire harness 410.

There are numerous exemplary situations where the ability to communicate information (for example, data representing lighting instructions or external conditions related to some aspect of the automobile) to and from the lighting fixture controller would be extremely powerful, even if the controller performs some function based on information that may have little or nothing to do with the generation of light from the stack of LEDs connected in series. For example, the controller can include a memory that includes various types of registration information (for example, related to device tests), and / or a unique serial, accessible through one of the communication ports 120A and 120B, to allow tracking of auto parts in which the appliance is installed. The information communicated to the controller can be related to the operation of the lighting apparatus itself, for example, detecting an external condition, such as temperature, opening or closing of a door, panel, valve, or operation of a user interface or other switch. , or analog sensor. The information transmitted by the controller can also be used to perform external operations, such as controlling gauges, motors, solenoids, valves, pumps, interlocks, fans, or other light sources in the car. Additionally, the controller memory can be used to

ES 2 348 841 T3 store information about how the controller should respond to external signals. Such a functionality could be implemented as a fully generalized stored computer program.

In view of the foregoing, numerous varieties of automotive lighting fixtures according to the present invention with various functionalities are contemplated. For example, a given lighting fixture could produce as much light for a door handle, as well as provide control of a door lock mechanism. The same device with different programming could be an overhead light, with support for capacitive touch switches to control its operation. A device could operate with both brake light and reverse light functions.

In still other embodiments, multiple lighting fixtures according to Figures 3 or 4 may be employed in parallel or series configurations. In particular, for operating voltages significantly greater than 12 to 15 volts, one or more conventional LEDs or conventional LED packages (i.e. without the control functionality of the apparatus of Figure 4) may be used in series with a control apparatus. Figure 4, in which the control functionality of the apparatus of Figure 4 is used to accommodate decreases in operating voltage applied to multiple devices connected in series. In this way, the apparatus of Figure 4 serves as a "smart" or "active" element in a series connection of such devices, while the one or more conventional LEDs or conventional LED packages are "non-intelligent" or "Passive" in series connection. In one aspect, such an element configuration may be particularly suitable for 24 volt systems.

In other respects, a lighting apparatus according to the present invention similar to those shown in Figures 3 and 4 has an appreciably low capacitance to allow compatibility with so-called "low voltage electronic transformers", which include a bridge rectifier to provide a DC voltage derived from an AC line voltage. In particular, the resistive nature of the lighting apparatus shown in Figure 4 makes the apparatus particularly suitable for applications requiring a relatively high power factor. Specifically, the current source 310 in the circuit of Figure 4 is configured to set the series current I_Serie based on the operating voltage applied to nodes 108A and 108B, through the voltage divider formed by resistors R43 and R42; in this way, resistor R43 performs a "voltage sensing" function and the current drawn by the apparatus follows changes in operating voltage. By configuring an LED-based lighting fixture to appear as an essentially resistive or linear load, transformer saturation, acoustic noise, and input harmonic currents can be reduced, thereby improving the power factor.

In still other embodiments of the invention according to the present disclosure, instead of controlling series-connected LEDs based on changes in operating voltage, A lighting apparatus similar to that shown in Figure 3 may be configured such that the controller 105A controls each of the LEDs 104A and 104B as individually and independently controllable channels of a multi-channel lighting unit according to one or more lighting instructions. or lighting orders received through communication port 120A, as discussed above in connection with Figures 1 and 2. Again, a given lighting apparatus based on the general circuit architecture shown in Figure 3 may have two or more independently controllable channels; For example, in one embodiment, a lighting fixture may comprise only white LEDs, and include a "warm white channel" having one or more warm white LEDs located at a first height in the stack, and a "cool white channel" that has one or more cool white LEDs located at a second height in the stack. Alternatively, a lighting fixture may include a "red" channel that includes one or more red LEDs located at a first height in the stack, a "green" channel that includes one or more green LEDs located at a second height in the stack, and a "blue" channel that includes one or more blue LEDs located at a third height in the stack. Of course, various combinations of colored and white LEDs can be employed in different implementations.

In many applications, LED-based nodal voltage fluctuations that are switched into or out of the series connected stack can have little or no consequence. However, in some circumstances, voltage balancing devices can optionally be used to maintain a power dissipation distribution and avoid voltage surges at nodes at different heights in the LED stack, as this can reduce the power being drawn. it would otherwise be used in activating various capacitances (in some cases including the capacitance of an LED itself). An implementation of a circuit, which includes both voltage balance and current deflection sections for a given LED in a series connected stack, is shown in Figure 7 and employs two operational amplifiers to control both of a pair. of differential transistors. The voltage references for these amplifiers can be changed, or they can be turned off, to lower the output voltage so that they in turn turn on / off the appropriate current path. In various aspects, the voltage references may be set as percentages of the operating voltage, they may contain both radiometric and set stress components, or they may be partially or fully programmable (eg, under the control of controller 105A).

In another embodiment of a lighting apparatus according to the present disclosure, multiple different node voltages are generated with the operational amplifiers, and controllable current sources that drive LEDs are used between each of the node voltages. These circuits are typically more complex, using more devices that must be sized to handle the full current, and thus are less cost effective. Additionally, they can re

ES 2 348 841 T3 want external capacitors to maintain stability. An example with 3 LEDs of such a lighting fixture 100C is shown in Figure 8.

In other aspects of multi-channel lighting apparatus employing series-connected LEDs, it should be appreciated that series-connected circuit arrangements are generally less efficient than multiple channels of controllable LEDs connected in parallel over an operating voltage, in which Current still flows through the entire circuit, rather than turning off on a given channel, when one or more channels are not activated. To mitigate this effect and conserve power, in some embodiments the series current flowing in the stack of devices can be reduced, either linearly, or after the drive signals from the LEDs. In one aspect, it may be advantageous generally to align the LED drive signals so that the large LED current flows through all devices at the same time, and there is a shutdown period, during which the power source can be turned off. current that sets the current in series. In other embodiments of the lighting apparatus according to the present disclosure, the controllable LED channels may be separated into groups, each group having a different current source, as shown by apparatus 100D illustrated in FIG. 9.

Figure 10 illustrates an LED-based lighting unit 100E in accordance with yet another embodiment of the present invention that is generally based on the architecture of series-connected LEDs and current shunt around the respective LEDs. The apparatus of Figure 10 is further configured to behave essentially as a resistive or linear element, based on the concepts disclosed in US Patent Application Serial No. 60 / 883,620, which is incorporated herein by reference. In particular, the apparatus of figure 10 includes LEDs D38, D39 and D40 connected in series and corresponding switches SW1-SW3 (formed, for example, by a transistor in series with a Zener diode) that function in part as voltage regulators of derivation. The apparatus also includes a current mirror circuit 600 that causes the apparatus 100E to appear as an essentially resistive or substantially linear load for an operating voltage coupled to nodes 108A and 108B. Depending on the voltage requirements of the controller 105B, the apparatus may also include a D37 Zener diode to provide a supply voltage for the controller 105B (U7).

In yet another embodiment, the combination of LEDs and a controller to form a lighting unit as discussed above in connection with any one of the figures described above can also be duo-stacked between an operating voltage, as shown in Fig. Figure 11 and, as shown in Figure 12, Multiple such lighting units (marked "A" through "E") may share an amplifier in a "split rail" architecture to divide the operating voltage so that power is provided to all lighting units. The number of lighting units above and below the rail splitting amplifier need not be identical, and the lighting units themselves do not need to be similar (for example, different LEDs can be used in different lighting units, and the data cabling does not need to be related to stacking level). The amplifier may or may not be a dissipation device, for example it could be a switch mode power supply, similar to many audio amplifier designs. Furthermore, the amplifier may or may not be integrated with one of the control circuits. In addition, control circuits can have data inputs, which can either be capacitively coupled, or can use other schemes to communicate with each other.

Although various inventive embodiments have been described and illustrated herein, a variety of other means and / or structures will readily envision a variety of other means and / or structures to perform the function and / or obtain the results and / or one or more of the advantages. described herein, and each such variation and / or modification is considered to be within the scope of the inventive embodiments described herein. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are intended to be exemplary and that actual parameters, dimensions, materials, and / or configurations will depend on the application. or specific applications for which the teachings of the invention are used. Those skilled in the art will recognize, or be able to determine without using more than routine experimentation, many equivalents to the specific inventive embodiments described herein. Therefore, it is to be understood that the above embodiments are presented by way of example only and that they are within the scope of the appended claims and the equivalents thereof.