Light module, illumination system and method incorporating data in light emitted

The invention relates to a light module comprising at least two main light sources which are capable of emitting a base light enabling the light module to emit light having intensity (Y) and color coordinates (x, y). The light module further comprises a modulator being in it will be able to modulate the main light source allowing the data to be placed in the emitted light. Hereinafter, the invention relates to a lighting system comprising such light modules. Furthermore, the invention relates to a method of placing data in the light emitted by light modules. Such devices are of particular interest in advanced control of lighting systems and data transmission in free space in confined spaces.

BACKGROUND OF THE INVENTION [0002] An embodiment of a lighting system of the type described is known from US2007 / 0008258. The document discloses a communication network based on lighting using data transmission in the free space incorporated into the light emitted by the lighting modules of the lighting system as intensity modulations. Light modules contain many light-emitting diodes (LEDs), each emitting light of a different wavelength (primary colors) and provides lighting, usually required from such systems to enhance the visibility of objects to the human eye. What's more, the network contains many detectors, and each contains many elements selectively receiving light of different wavelengths (using a band filter) corresponding to the primary colors emitted by LEDs.

[0003] Light modules transmit data by (i) dividing a series of input signals into a plurality of signals corresponding to different wavelengths of LEDs, (ii) providing each signal to a corresponding LED, (iii) performing codternal multiple access communication by modulating LED emission intensities.

Receiving such a modulated light allows the detector (i) to generate signals from each of the light receiving elements at the appropriate wavelength (ii) correlate signals with the spreading code used to transmit data through the light modules, (iii) decipher signals and regenerate data as output data on the detector's output port.

[0005] A disadvantage of the solution described in US2007 / 0008258 is that the human eye is very sensitive to changes in intensity, especially at certain frequency ranges. Thus, re-use of the lighting system as part of the communication network by implementing data into light emitted as frequency variations can weaken the basic function of the system as aids to human vision, especially when using high-sensitivity human eye frequencies. Therefore, there is a clear need to use an alternative modulation scheme that allows data transmission without (or in a significantly reduced size) weakening the perceived performance of the basic lighting system function over a wide modulation frequency range.

SUMMARY OF THE INVENTION [0006] The invention aims to provide a lighting system and a modulation method that at least in part satisfies the needs described above. The invention fulfills this task according to the first aspect by providing a lighting system comprising a plurality of light modules each comprising at least two primary light sources able to emit a light of primary colors enabling the light module to emit (combined) light having intensity and color coordinates, and modules The lights additionally contain a modulator able to modulate the basic light sources enabling the data to be placed in the emitted light, characterized in that the modulator is arranged to modulate the coordinates of the colors of the emitted light.

[0007] Based on the knowledge that the human eye's sensitivity to color changes is less than to changes in intensity, the invention advantageously allows data to be placed in the light emitted from the illumination system without reducing the efficiency of its original function as an aid to human vision.

[0008] In one embodiment of the invention, the modulator is arranged to modulate light according to a modulation scheme with a spread spectrum. In an embodiment, the data includes the light module identification code. Advantageously, this enables the identification of individual light modules (and consequently their control) by the sensor device, even when they are illuminated by light from multiple light modules at the same time.

[0009] In an embodiment, the light module further comprises a detector arranged to determine the color coordinates (x, y) of the light emitted by the light module to calibrate the emitted light. This advantageously allows feedback to control and stabilize the color point of the emitted light.

[0010] In an embodiment, the modulator is arranged to use a modulation alphabet defining at least two chromaticity co-ordinates (x0, y0) and (x_x, y_x) representing at least logical "0" or logic "1" to modulate color coordinates. In an embodiment, at least two chromaticity co-ordinates (x₀, yo) and (x_x, yi) of the modulation alphabet are set to lie on a common axis with the target chromaticity coordinate (χτ, γτ) of the emitted light. In yet another embodiment, the common axis forms a prolonged axis of the MacAdam ellipse around the target chromaticity coordinate (χ_τ, γτ) of the emitted light. Preferably, this setting minimizes the visibility of the color coordinate modulation for the observer, while maximizing detection for the sensor device.

[0011] In an embodiment, at least two chromaticity co-ordinates (x₀, y0) and (xi, yi) represent a predetermined color transition, Axy, respectively₀ and Axyi. This embodiment has a significant advantage in placing data using modulation in a more homogeneous, undistorted reference color space, such as CIE L * a * b * space and CIE Luv space.

[0012] According to a second aspect, the invention provides a lighting system comprising a plurality of light modules according to the invention. In an embodiment, the lighting system further comprises a remote sensing device arranged to determine the color coordinates (x, y) of the light emitted by the light modules to detect data placed in the emitted light.

According to a third aspect, the invention provides a method for inserting data in the light emitted by a lighting system lighting module comprising the step (i) of setting the light module to include at least two primary light sources that are able to emit a base light to enable the light module. emitting light having intensity and color coordinates, (ii) modulating basic light sources using a modulator, (iii) setting the modulator to modulate the coordinates of the colors of the emitted light.

[0014] These and other aspects of the invention will be apparent and explained with reference to the embodiments described later in this document.

BRIEF DESCRIPTION OF THE DRAWINGS [0015] Additional details, features and advantages of the invention are disclosed in the following description of exemplary and preferred embodiments in conjunction with the drawings.

Fig. 1 shows an embodiment of the lighting system according to the invention

Fig. 2 is a CIE xy chromaticity diagram

Fig. 3 shows an embodiment of a modulator in a light module according to the invention. Fig. 4 shows an embodiment of a sensor device included in a lighting system according to the invention.

DETAILED DESCRIPTION OF EMBODIMENTS [0016] Fig. 1 shows a lighting system 100 according to the invention. The system includes a plurality of light modules 110. Each light module includes at least two primary light sources 111, 112, 113 that are able to emit a base light allowing the light module to emit a combination of intensity (Y) and color coordinates (xy) through mixing the primary colors of the light emitted by the light sources using the appropriate optical mixing 114. The light sources can in principle be of any type, such as a gas-discharge bubble, an inorganic light-emitting diode (LED), organic organic diode (LED), and laser diodes. . Thus, as an example, the light module 110 may include three primary light sources 111, 112, 113 emitting red, green and blue light respectively. Alternatively, the light modules may comprise more than three light sources, such as a fourth amber LED. In yet another alternative, the light modules 110 may even include a (fifth) phosphor-coated LED emitting a broadband predetermined spectrum such as white light. The light modules 110 additionally comprise a modulator 115 which is able to modulate the basic light sources enabling the data to be placed in the emitted light. In an embodiment, the light module 110 further comprises a detector 116 positioned to define the color coordinates (xy) of the light emitted by the light module to calibrate the emitted light. like, for example, the fourth amber LED. In yet another alternative, the light modules 110 may even include a (fifth) phosphor-coated LED emitting a broadband predetermined spectrum such as white light. The light modules 110 additionally comprise a modulator 115 which is able to modulate the basic light sources enabling the data to be placed in the emitted light. In an embodiment, the light module 110 further comprises a detector 116 positioned to define the color coordinates (xy) of the light emitted by the light module to calibrate the emitted light. like, for example, the fourth amber LED. In yet another alternative, the light modules 110 may even include a (fifth) phosphor-coated LED emitting a broadband predetermined spectrum such as white light. The light modules 110 additionally comprise a modulator 115 which is able to modulate the basic light sources enabling the data to be placed in the emitted light. In an embodiment, the light module 110 further comprises a detector 116 positioned to define the color coordinates (xy) of the light emitted by the light module to calibrate the emitted light. The light modules 110 additionally comprise a modulator 115 which is able to modulate the basic light sources enabling the data to be placed in the emitted light. In an embodiment, the light module 110 further comprises a detector 116 positioned to define the color coordinates (xy) of the light emitted by the light module to calibrate the emitted light. The light modules 110 additionally comprise a modulator 115 which is able to modulate the basic light sources enabling the data to be placed in the emitted light. In an embodiment, the light module 110 further comprises a detector 116 positioned to define the color coordinates (xy) of the light emitted by the light module to calibrate the emitted light.

[0017] In an embodiment, the data (including the light module identification code / ./, lighting characteristics of the emitted light, or non-lighting data such as music or information about the object, image, figure placed near the light module 110) are implemented using spectral dispersion techniques. This technique is known as "code multiplexing / multiple access" (CDM or CDMA). For each illumination module 110, a unique ID code is assigned. The ID codes must be orthogonal, i.e. the auto-acceleration value of the code must be significantly higher than the mutual correlation value of two different A sensing device 190, e.g. including a photoelectric sensor, is then able to distinguish between simultaneous transmissions of the modulated light through different light modules 110 so that that the sensor device can identify each of them. Hereinafter, the sensor device 190 may measure the lighting characteristics (intensity, color point, etc.) of the modulated light received from the identified light module 110. For each detected modulated light emission, the sensor device 190 provides data (preferably wirelessly using the ZigBee protocol) including the identification of the emitting light module 110 and the measured light property value to the main controller 200. Acquiring such data enables the main controller to control the light modules 110, changing the intensity or color point of the emitted light to obtain the desired light effects in the area around the sensor device 190. The light effect creates the basic function of the lighting system 100,

[0018] (Combined) light effect, assuming that it will have trichromatic coordinates ΧΥΖ can be characterized in the CIE xyY color space using well-known relationships:

A- = X / (X + F + Z) or X = (7 v) · ay = Y / (X + Y + Z) z = Zf (X + Y + Z) or Z = (F / y) · z = (Y / y) · (l - a - y)

Equation 1 [0019] Fig. 2 schematically depicts a plane xy of the color space, known as a chromaticity diagram. For this explanation, it has been assumed that light modules 110 contain three LEDs emitting a red, green, and blue part of a visible spectrum with intensities of Y respectively._R, Yg and Y_B, and having chromaticity coordinates (xr, y, respectively)_R), {Χΰ, Υε), and (x_Bs_B). The light effect, created by the additional mixing of the colors of these basic light sources, can be characterized in terms of components stored as:

<td>'jr</td><td></td><td>[AND</td><td></td><td>"P</td>

<td>F</td><td>=</td><td>y * y_f; y "</td><td></td><td>1</td>

<td>AND</td><td></td><td>And with_(;</td><td></td><td>Λ</td>

Equation 2 [0020] Coordinates of xyY (combined) light effect can be obtained using Equation 1.

[0021] The modulation scheme in the prior art implements data as orthogonal codes using the spread spectrum technique by modulating the optical output power of each primary light source 111,112,113. For each primary light source corresponding mainly to a different wavelength (or channel), each channel has other specific data assigned. Thus, specific R channel data corresponds to modulations in X_R, Yr, Z_r, and similarly modulations X, respectively_G, Yg, Zg and X_B, Yb, Z_b for specific G &amp; B channel data. Equation 2 shows that the intensity of Y = Y_r+ Yg + Yb does not remain constant, but itself shows modulations, which - depending on the frequencies used can significantly weaken the basic function of the lighting system 100. The concept of the invention, on the other hand, is based on the knowledge that data can be implemented alternatively by modulation of chromaticity coordinates (x, y) the light effect while maintaining constant intensity Y. Preferably, because the human eye has less sensitivity to modulation in the chromaticity of the light effect than for modulation of its intensity, the invention provides a data transmission concept for use in a lighting system without reducing the perceived basic performance of the function lighting system at wide frequency ranges of modulation. [0022] FIG. 3 shows an embodiment of the modulator 115 included in the light module 110 according to the invention. In this example, the light module includes three main light sources 111, 112, 113. Again, however, the concept of placing the invention data works for any light module having at least two primary light sources. Mixing the light emitted from the main light sources 111, 112, 113 creates a light effect. The target light effect 122, provided by the main controller 200 (See Fig. 1) is given by the chromaticity coordinates (χ Mixing the light emitted from the main light sources 111, 112, 113 creates a light effect. The target light effect 122, provided by the main controller 200 (See Fig. 1) is given by the chromaticity coordinates (χ Mixing the light emitted from the main light sources 111, 112, 113 creates a light effect. The target light effect 122, provided by the main controller 200 (See Fig. 1) is given by the chromaticity coordinates (χ_τ, Υτ) (see point T in Fig. 2) and the intensity of Y_T. Modulator 115 includes a modulation alphabet generator 120, (optional) encoder 130, mapper 140, and (optionally) transformer 150.

The modulation alphabet generator 120 generates a modulation alphabet 123 based on an alphabet size input pointer 121. For example, if the alphabet size is 2, the logic "0" and the logic "1" may correspond to the alphabet 123 having chromatographic coordinates (x0, respectively) yo) and (xl, yl). Alternatively, an alphabet size of 4 allows the creation of 2-bit pairs with logical values ​​of "00", "01", "10" and "11" and corresponding chromaticity coordinates (χο, Υο), (χυΥι), (Χ2Α2) and (x3 , Y3) · Relevant mappings can be created for the alphabet size 121 equal to 8.16, etc. Thus, preferably, the larger size of the alphabet 121 makes it possible to improve the modulation alphabet 123, allowing mainly increased data transmission capacity. preferably,_Ts_T) and so on are formed such that their average corresponds to the target chromaticity coordinate (χτ, γτ). Preferably, this minimizes the visibility of the color coordinate modulation for the human eye.

[0024] The data signal 131 to be placed in the (combined) light emitted may be fed into the optional encoder 130 to form the encoded data 132. The encoder 130 may add excess bits fi for error correction. Preferably, this makes data transmission and reception more resistant to errors caused by noise. Examples of such unnecessary bits may be codes using checksums, parity bits, or cyclical redundancy control.

[0025] Subsequently, the introduction of the target light effect 122, the modulation alphabet 123, and the encoded data 132 into the mapper 140 allows to make a data map for the chromaticity coordinates around the target (χτ, γτ) · This results in the stream of symbols 141 defining the light effect (x, y, Y) is formed by the light module 110 and contains inserted data that will be transmitted under the condition that Y remains constant (i.e., equal to Y_T). Transformer 150 transforms the stream of symbols 141 into LED drive signals 151 for individual basic light sources 111, 112, 113. This transformation operation depends on the chromaticity coordinates (xr, Yr), (xg, Yg)> and (x_b, Yb) of the primary light sources present in the light module 110. In other words, the transformer 150 sets up the CIE xyY space with the "RGB" color space obtainable by the primary light sources in the present embodiment. Alternatively, the modulation alphabet generator 120 can be configured to already include knowledge in the chromaticity coordinates of the primary light source This configuration reduces the transformation operation on the transformer 150 for identity operations.

[0026] Fig. 4 shows an embodiment of the sensor device 190 included in the lighting system 100 according to the invention. It includes a color sensor 160, (optional) color transformer 170, a symbol detector 180, and (optional) encoder 135. Hereinafter, the sensing device may include a suitable transceiver unit and a user interface (both not shown) to communicate with the respective, the main controller 200 and the operator.

[0027] Similar to the transformer 150, the color transformer 170 sets up the color space of the color sensor 160 with the CIE xyY color space. This statement is equal to the identity transformation in case the spectral sensitivity of the color sensor is equal to the CIE color matching function. Thus, the color transformer 170 allows the reconstruction of the symbol stream 141 defining (combined) light effect (x, y, Y) that is created by the light module 110 and contains the inserted data to be transmitted under the condition that Y remains constant (i.e. equal to Y_T).

[0028] Subsequently, the symbol detector 180 reconstructs (coded) data from the symbol stream 141. The availability of the modulation alphabet 123 creates a fundamental condition for reconstruction. In an embodiment, the modulation alphabet 123 is predetermined and available in a table on the storage medium included in the sensing device 190. The table includes a list of target chromaticity coordinates (x_T, yr) and the corresponding chromaticity coordinates (x_about, y0), (xi, yi) and so forth of the modulation alphabet 123. Alternatively, information in the alphabet of modulation 123 may be included in the light transmitted by the light modules 110 as a preamble for the actual data. This enables the symbol detector 180 to learn to interpret the symbol stream 141. In the present embodiment, the preamble should be transmitted each time the target chromaticity coordinates (x_Ts_T) the light effect created by the lighting system 100 changes. In yet another embodiment, the modulation alphabet 123 can be generated by implementing a fixed color change, regardless of the target color point (x_Ts_T). Thus, in the present embodiment, the logic "0" corresponds to the change in the colors Axy₀and logic "1" corresponds to Axyi color change. This embodiment has a significant benefit when placing data using modulation in a more homogeneous undistorted color reference space, such as CIE L * a * b * space and CIE Luv space (see below) .

[0029] Like the optional encoder 130 in the modulator 115, the encoder 135 in the sensing device 190 is optional and allows reconstruction of data from the output of the symbol detector 180.

[0030] The above describes the color coordinates for the CIE 1931 xyY color space. There are many other color spaces, such as fi CIE 1960 Luv, CIE 1964 U * V * W *, CIE 1976 L * a * b *, transformation relations. Describing the invention as modulating / demodulating, the coordinates of the color of the emitted light do not limit the range to the space ΧΥΖ or xyY. The range includes any color space.

[0031] In an embodiment, the chromaticity coordinates (x_about, y0), (xi, yi) and so on, the modulation alphabet 123 are positioned to lie on a common axis 124 with the target chromaticity coordinate (χτ, Υτ) of the emitted light (see Fig. 2). In an embodiment, the common axis 124 forms a prolonged axis of the MacAdam ellipse 125 around the target chromaticity coordinate (χτ, Υτ) of the emitted light. Preferably, this setting minimizes the visibility of the color coordinate modulation for the observer, and at the same time maximizes the detectability for the sensor device. While the CIE xyY color space indicates significant distortions in the differences of recognizable colors (i.e., the size and orientation of the MacAdam ellipse 125 varies significantly depending on the test color: large for greenish colors, small for bluish colors and intermediate for reddish colors), other color spaces - such as CIE L * a * b * and CIE Luv - were created to show a much smaller disruption. Therefore, the corresponding ellipses in these spaces become much more circular, but still have a long axis.

[0032] Although the invention has been explained with reference to the embodiments described above, it will be understood that alternative embodiments may be used to achieve the same purpose. Therefore, the scope of the invention is not limited to the embodiments described above. Accordingly, the scope of the invention is limited only by the claims and their equivalents.