Full-color flexible semiconductor light source device

<u>BACKGROUND OF THE INVENTION</u>

1. Field of The Invention

The present invention relates to light source units and more particularly to a full-color flexible light source device comprising chip on board type red, green, and blue light source units (e.g., LEDs).

2. Description of Related Art

A conventional light source strip comprises a plurality of LEDs (light-emitting diodes) serially coupled together in which each LED has a coupled resistor and can emit light of single color. A number of drawbacks have been found when the above light source strip is modified to become a full-color light source strip. This is because brightness difference between any two of R (red), G (green), and B (blue) LEDs is quite large. For example, brightness of three R LEDs is equal to that of one B LED. Brightness of six G LEDs is equal to that of one B LED. For obtaining a uniform brightness of the light source strip, a unit thereof is required to consist of three R LEDs, six G LEDs, and one B LED. Such arrangement (i.e., optimum spacing) is difficult of achieving. It is often that an uneven illumination is occurred on the characters and/or marks of a billboard. This is not desirable. Moreover, the size of a full-color light source strip is about three times of that of a monochromatic light source strip if the former is adapted to emit light having a brightness the same as that of the latter. Also, the circuitry of the former is complicated, resulting in an increase in the manufacturing cost. Further, heat dissipation of LED is poor. As a result, LEDs tend to malfunction.

In <patcit id="pcit0001" dnum="US6540377B"><text>U.S. Pat. No. 6,540,377</text></patcit> there is disclosed a full-color light source unit for solving the above problem. In the patent, the above unit consisting of three R LEDs, six G LEDs, and one B LED is modified to consist of only two R LEDs, two G LEDs, and one B LED. That is, the number of LEDs has decreased from ten to five. This is an improvement. However, the light source unit is rigid as illustrated in figures thereof. Moreover, the size thereof is quite large and spacing between any two LEDs is also relatively large. All of the above are not desirable. Thus, the need for improvement still exists.

<patcit id="pcit0002" dnum="US20030072153A"><text>US20030072153</text></patcit> discloses a plurality of groups of Light Emitting Diodes (LEDs), each group being made up of three LEDs with red, green, and blue luminous colors respectively, are mounted at positioning areas of a flexible substrate, on the wiring patterns formed on the top surface of the substrate. A plurality of heat dissipation boards are adhered to the bottom surface of the substrate using an adhesive so as to cover the areas corresponding to the positioning areas of the groups of LEDs.

<patcit id="pcit0003" dnum="EP1282099A"><text>EP1282099</text></patcit> discloses a circuit for driving a self light-emitting display device which itself emits light when an electric or other energy is inputted thereto and a method thereof. According to the circuit and method, the self light-emitting display device can be driven more stably and with a higher efficiency by adjusting the number of used bits and luminance of respective color components in accordance with a luminance change of an external light and keeping a constant contrast ratio irrespective of the adjustment of the bit numbers.

<patcit id="pcit0004" dnum="JP10012926B"><text>JP10012926</text></patcit> discloses a full color emission diode lamp and display, PROBLEM TO BE SOLVED: To obtain a clear emission display surface of high uminance by realizing high density arrangement. SOLUTION: The LED lamp 10 comprises red, green and blue LED chips 11R, 11G, 11 B arranged at a constant interval in substantially regular triangle on a plane, a lead (lead frame 12), and an enclosure (resin mold) 15 formed substantially into a right prism corresponding to the three LED chips. Since the LED chips 11 R, 11G, 11 B are arranged at respective corners of the substantially regular triangular prism enclosure 15 and occupy a smallest area, an emission display surface where three primary color LED chips are arranged tightly can be formed by arranging the LED chips while abutting on the side face of the enclosure 15. The display comprises nondirectional unit dots where six full color emission LED lamps 10 are arranged adjacently in regular hexagon.

<patcit id="pcit0005" dnum="US20030052594A"><text>US20030052594</text></patcit> discloses a plurality of concaves are provided for one main surface of a flexible substrate by press-forming. Each concave has a flat surface which is substantially parallel to the main surface of the substrate, and mounted on the flat surface are three LEDs each emitting colored light of red, green, and blue respectively.

<patcit id="pcit0006" dnum="DE20018865"><text>DE20018865</text></patcit> discloses a light system having a plurality of light sources attached on modules, wherein each module comprises means for switching and a connection with a control unit.

<patcit id="pcit0007" dnum="DE19608898"><text>DE19608898</text></patcit> discloses a light-emitting diode (LED) device including LEDs (R1 R2; G1 G2; B1 B2) for each of the three primary colours. Alternatively it has several LEDs for each of the three primary colours. It includes a variable resistances arrangement (16r, 16q, 16b) with several variable resistors arranged on a component for each of the primary colours. The variable resistances are connected to one or several terminals of the LEDs for each of the primary colours, in order to variable control the current through the LEDs (R1 G1 B1).

<patcit id="pcit0008" dnum="EP1357331A"><text>EP1357331</text></patcit> discloses a flexible rod light device containing a string of chip on board (C.O.B.) based LED lamps (20) and manufacturing method thereof are disclosed. The device comprises an inner layer (10) including two parallel upward flanges (12,13) on sides and a lengthwise top groove (11) between the flanges; a string of C.O.B. based LED lamps (20) comprising a plurality of series connected units each including a C.O.B. based LED lamp (21) secured on the groove (11) and between the flanges (12,13), one or more conductor means (23), and a resistor (22); a pair of main wires (31,32) parallel disposed within the flanges (12,13); and a jacket (40) wrapped up the inner layer (10) and the string of lamps (20). All lamps are secured and have the same orientation for achieving an increased illumination.

<patcit id="pcit0009" dnum="US20020034074A"><text>US20020034074</text></patcit> discloses a tubular decoration light string comprising inner insulator and outer insulator, said decoration light string equipped and fixed an inner insulator, said inner insulator and decoration light string to be sealed within an outer insulator, and to form a longitudinal direction hollow in said outer insulator, increasing an effect of reflection and refraction of light.

<patcit id="pcit0010" dnum="WO2004023033A"><text>W02004023033</text></patcit> discloses the invention related to LED assembly suitable to form a string provided with an LED mounted with a mounting on a base, which base is provided with electric connection wires wherein the LED mounting and electric contacts to the connection wires are protected from the surroundings by a package of hot melt material. The invention further relates to a string of interconnected LED assemblies, preferably wherein the LED assemblies are separated from each other by length of flexible contact wires.

<patcit id="pcit0011" dnum="FR2833687"><text>FR2833687</text></patcit> discloses a decorative light chain using light-emitting diodes (LEDs), and used e.g. for window displays, comprises miniature light sources (2) each formed of at least two high performance light-emitting diodes (3) emitting light of different colors and connected into a programming circuit (6) that is integrated with the light sources and which provides independent variation of the intensity of the LEDs. Preferred Features: The LEDs (3) are mounted on an electric cable (4) connected to a power supply that includes a low-voltage transformer (6). The LEDs can be mounted on an electric cable connected to an electric cell as the power source, or multicolored LEDs that operated at 230 volts and supplied directly from the power grid can be used. Each light source can comprise a device consisting of one programming circuit and many LEDs (3) emitting different colors. Each light source can comprise three LEDs whose colors, e.g. red. green and blue, can be mixed to produce the colors of the whole range of the visible spectrum, and a programming unit provided with three outputs whose intensities vary independently in a random manner. The programming unit (6) comprises a flashing light with two or more buses as a function of the number of LEDs integrated into each light source (2). The front surface of the LED light sources is provided with an optical element (8) forming a magnifying glass.

<patcit id="pcit0012" dnum="EP0838866A"><text>EP0838866</text></patcit> discloses a system of at least three multi-coloured LED's has an optimized colour rendering index by proper selection of wavelengths of each LED, such system being useful for general illumination purposes. In a preferred embodiment, a blue LED has a wavelength in the range 455 to 490 nm, a green LED has a wavelength in the range 530 to 570 nm, and a red LED has a wavelength in the range 605 to 630 nm.

<u>SUMMARY OF THE INVENTION</u>

It is an aim of the present invention to provide a full-color light source device, comprising: an inner fixing member; first, second, third, and fourth main wires disposed in the inner fixing member; a plurality of light source units coupled in series wherein a first light source unit has first, second, and third conductors extended therefrom, and a last light source unit has three fourth conductors, extended therefrom; and an outer fixing member for surrounding the inner fixing member; characterized in that: the inner fixing member is formed of a transparent or semi-transparent, flexible plastic material, the inner fixing member including a lengthwise channel therethrough; the light source unit further comprises a R LED, a G LED, and a B LED as a C.O.B. type RGB LED, the plurality of light source units are inserted into the channel; the first, second, third, and fourth main wires are parallel each other, spaced from the channel in the inner fixing member, and coupled to an external controller; the first conductor in a forward end of the first light source unit is inserted into a front end of the inner fixing member to couple to the second main wire by a tool, the second conductor in the forward end of the light source unit is inserted into the front end of the inner fixing member to couple to the third main wire by a tool, the third conductor in the forward end of the light source unit is inserted into the front end of the inner fixing member to couple to the first main wire by a tool, and the fourth conductor in a rear end of the light source unit is inserted into a rear end of the inner fixing member to couple to the fourth main wire by a tool for forming an electrical connection; the outer fixing member is made of a transparent or semi-transparent, flexible plastic material, the outer fixing member being formed by extrusion with the inner fixing member and the plurality of light source units surrounded therein; the plurality of light source units are equally spaced; and light emitted from the plurality of light source units are directed to a direction perpendicular to a surface of the outer fixing member.

The above and other objects, features and advantages of the present invention will become apparent from the following detailed description taken with the accompanying drawings.

<u>BRIEF DESCRIPTION OF THE DRAWINGS</u>

<ul id="ul0001" list-style="none" compact="compact"><li><figref idref="f0001">FIG 1</figref> is a perspective view of a light source unit not covered by the claims;</li><li><figref idref="f0001">FIG 2</figref> is a front plan view of the circuit board;</li><li><figref idref="f0001">FIG 3</figref> is a rear plan view of the circuit board;</li><li><figref idref="f0002">FIG 4</figref> is a perspective view of a light source device according to the invention, the light source device comprising a plurality of serially coupled light source units of <figref idref="f0001">FIG 1</figref>;</li><li><figref idref="f0003">FIG 5</figref> depicts the connection of a controller to the LEDs of <figref idref="f0002">FIG 4</figref>;</li><li><figref idref="f0003">FIG. 6</figref> is a circuit diagram of the controller;</li><li><figref idref="f0004">FIG 7</figref> is a perspective view of a preferred embodiment of light source device according to the invention;</li><li><figref idref="f0005">FIG 8</figref> is a partial exploded view of the light source device of <figref idref="f0004">FIG 7</figref>;</li><li><figref idref="f0006">FIG 9</figref> is a slightly enlarged view of <figref idref="f0004">FIG 7</figref> with portions cut away for showing details;</li><li><figref idref="f0007">FIG 10</figref> is an exploded view of a portion of a light source device according to a second preferred embodiment of the invention; and</li><li><figref idref="f0007">FIG 11</figref> is an exploded perspective view of a light source device according to a third preferred embodiment of the invention.</li></ul>

<u>DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS</u>

Referring to <figref idref="f0001 f0002 f0003">FIGS. 1 to 6</figref>, there is shown a light source device 20 constructed in accordance with a first preferred embodiment of the invention. The device 20 comprises a plurality of light source units 21 in which a first group of wires 23R, 23G, and 23B at one side of one light source unit 21 are electrically coupled to a second group of wires 24R, 24G, and 24B at the other side of an adjacent light source unit 21. This forms a serially coupled light source device including a plurality of C.O.B. (chip on board) type RGB light source units 21 (e.g., LEDs). The light source unit 21 comprises a circuit board 21P, a C.O.B. type LED 21R.G.B. Fixedly formed on the circuit board 21P, a first group of wires 23R, 23G, and 23B formed at one side, and a second group of wires 24R, 24G, and 24B formed at the other side.

In <figref idref="f0001">FIGS. 2 and 3</figref>, the circuit board 21P is a board having both surfaces formed with printed circuits. The wire 23R is coupled to one end of a first circuit 23R0 on the circuit board 21P. The other end of the first circuit 23R0 is coupled to a red bare chip (i.e., illuminator) 2 1 R via a conductor 23R0'. The red bare chip 2 1 R is formed on the other end of a second circuit 23R1. The wire 24R is coupled to one end of the second circuit 23R1. Similarly, the wire 23G is coupled to one end of a first circuit 23G0 on the circuit board 21P. The other end of the first circuit 23G0 is coupled to a green bare chip 21 G via a conductor 23G0'. The green bare chip 21G is formed on the other end of a second circuit 23G1'. One end of the second circuit 23G1' is coupled to the other end of a third circuit 23G1. The wire 24G is coupled to one end of the second circuit 23G1. Also, the wire 23B is coupled to one end of a first circuit 23B0 on the circuit board 21P. The other end of the first circuit 23B0 is coupled to a blue bare chip 21B via a conductor 23B0'. The blue bare chip 21B is formed on the other end of a second circuit 23B1'. One end of the second circuit 23B1' is coupled to the other end of a third circuit 23B1. The wire 24B is coupled to one end of the second circuit 23B1. This forms the electrical connection of the light source unit '21.

As shown in <figref idref="f0001">FIG 1</figref>, the R, G, B and blue bare chips 21R, 21G, and 21B are substantially arranged in the shape of an equiangular triangle prior to encapsulation as a C.O.B. type LED (i.e., the light source unit 21). That is, each light source unit 21 comprises a red bare chip, a green bare chip, and a blue bare chip encapsulated as a C.O.B. type LED. Moreover, the brightness ratio among red bare chip 21 R, green bare chip 21G, and blue bare chip 21B is 3:6:1 for obtaining a uniform brightness of the light source unit. Preferably, the wavelength of the red bare chip 21R is in the range of 615x10^-9 to 635x10^-9(ηm), the wavelength of the green bare chip 21 G is in the range of 520x10⁹ to 535x10^-9( ηm), and the wavelength of the blue bare chip 21 B is in the range of 465x10^-9 to 480x 10^-9( ηm) respectively.

By incorporating the above three characteristics, the light source unit 21 can be formed as a single full-color light source unit 21 by including a blue bare chip 21 B, a red bare chip 21R having brightness three times of that of the blue bare chip 21B, and a green bare chip 21 G having brightness six times of that of the blue bare chip 21B. As an end, a bare chip based light source unit capable of emitting a uniform brightness from a number of light sources of different colors is embodied.

The wires 23R, 23G, and 23B coupled between two adjacent light source units 21 are bent. Further, an insulator 25 in the form of sleeve is put on each of the wires 23R, 23G, and 23B. Only the insulator 25 is fixed after extruding from an outer fixing member 40 (see <figref idref="f0004">FIG. 7</figref>). The wires 23R, 23G, and 23B are bent and slightly flexible so as to prevent the wires 23R, 23G, and 23B from being cut while pulling. The outer fixing member 40 will be bent when the light source device is compressed. Also, the wires 23R, 23G, and 23B may slightly contract due to its flexibility. Such enables the light source device has an increased tensile strength and flexibility while compressing.

The light source device is further electrically coupled to a controller 50 which is in turn coupled to a power source. A resistor (e.g., SMD resistor) 22 (or stabilizer) is provided in each of the wires 24R, 24G, and 24B interconnected two adjacent light source units 21. Alternatively, the resistor 22 (or stabilizer) is provided in the controller 50 or any other position of the circuitry. As shown in <figref idref="f0003">FIG. 5</figref>, the controller 50 is a coupled to a first main wire 31, a second main wire 32, a third main wire 33, and a fourth main wire 30 of an inner fixing member 10 (see <figref idref="f0004">FIG 7</figref>) respectively. A ground line of the controller 50 is coupled to the fourth main wire 30 which is in turn coupled to the second group of wires 24R, 24G, and 24B respectively.

As shown in <figref idref="f0003">FIG 6</figref>, the controller 50 comprises a voltage stabilizer 51 including an IC (integrated circuit) IC1, an oscillator 52 including an IC IC2, a frequency divider 53 including an IC IC3, and a driving device 54 including a plurality of diodes D6 to D17, a plurality of resistors R6 to R17, a plurality of capacitors C6 to C11, and three transistors (e.g., SCRs or TRIAC_S). The oscillator 52 is adapted to generate an oscillating frequency which is further divided by the frequency divider 53 based on the spectrum of the RGB light source unit 21. Next, the driving device 54 is adapted to drive the RGB light source units 21 based on set time duration and time sequence. As an end, a desired light having full-color is obtained.

Referring to <figref idref="f0004 f0005 f0006">FIGS. 7 to 9</figref>, there is shown a light source device (i.e., LED strip) 20 constructed in accordance with a preferred embodiment of the invention. The device 20 is elongated and comprises a plurality of light source units 21 enclosed in an elongated, transparent or semi-transparent, flexible inner fixing member 10. First, second, third, and fourth main wires 31, 32, 33 and 30 are extended along the inner fixing member 10. The inner fixing member 10 is surrounded by an outer fixing member 40 formed of the same material as the inner fixing member 10. There is further provided a controller (not shown).

The inner fixing member 10 is formed of a plastic material. A lengthwise groove 11 is formed on a center of either top or bottom surface of the inner fixing member 10. A lengthwise channel 110 having a section of substantially hollow Z is formed in the inner fixing member 10. Two lengthwise ridges 12 and 13 are formed at both sides of the channel 110. The ridges 12 and 13 are adapted to fasten the light source device 20 in the channel 110 without any other fasteners. Each of the first, second, third, and fourth main wires 31, 32, 33 and 30 is spaced from one of four corners of the channel 110. The light source device 20 comprises a plurality of C.O.B. type LEDs 21 each having R, G, and B bare chips, three wires 23 for connecting the C.O.B. type LEDs 21 in series, and resistors 22 (or stabilizers) each disposed in one of three sections of the wires 23 between two adjacent C.O.B. type LEDs 21.

The controller (not shown) is coupled to the first, second, third, and fourth main wires 31, 32, 33 and 30. The first conductor 230 in the forward end of the light source device 20 is inserted into a front end of the inner fixing member 10 by a tool. The first conductor 230 is coupled to the second main wire 32. Similarly, the second conductor 231 in the forward end of the light source device 20 is inserted into a front end of the inner fixing member 10 by a tool. The second conductor 231 is coupled to the third main wire 33. The third conductor 232 in the forward end of the light source device 20 is inserted into a front end of the inner fixing member 10 by a tool. The third conductor 232 is coupled to the first main wire 31. The fourth conductor 233 in the rear end of the light source device 20 is inserted into the rear end of the inner fixing member 10 via the channel 110 by a tool. The fourth conductor 233 is coupled to the fourth main wire 30. This completes the electrical connection.

The outer fixing member 40 is formed by extrusion. The inner fixing member 10 and the light source device 20 are encapsulated in an airtight environment so as to form a light source strip having increased tensile strength and flexibility and being waterproof and vibration-proof. A top or bottom surface of the outer fixing member 40 is flat. Further, the light source device 20 is in turn controlled by the controller 50 for causing the C.O.B. type RGB light source units 21 to emit light with uniform full-color.

The flat top and bottom surfaces of the outer fixing member 40 facilitates the light source device to mount on an object and fasten thereat. Also, light is emitted in a direction perpendicular to the surface of the outer fixing member 40 for obtaining an increased brightness. The light source device 20 is adapted to bend without adversely affecting light emission. This is because, as stated above, the light source device has increased tensile strength and flexibility.

Referring to <figref idref="f0007">FIG 10</figref>, there is shown a light source device 20 constructed in accordance with a second preferred embodiment of the invention. The characteristic of the third preferred embodiment is that three copper wires 24 are interconnected two adjacent C.O.B. type RGB LEDs 21 by soldering.

Referring to <figref idref="f0007">FIG 11</figref>, there is shown a light source device 20 constructed in accordance with a third preferred embodiment of the invention. In the manufacturing process, the device 20 is first placed on an elongated, flexible sheet 26. The sheet 26 comprises a plurality of equally spaced rectangular openings 261 for receiving the C.O.B. type RGB LEDs 21 having a SMD (surface mounting) resistor 22A on its bottom. Three sections of conductive metal wires 27 are disposed between two adjacent openings 261 in which both ends 271 of the wires 27 are exposed for coupling to the C.O.B. type RGB LEDs 21 by soldering. Next, remove the sheet 26 with the light source device 20 fixedly formed in the inner fixing member. Such can provide an equal spacing between any two adjacent light source units 21 for facilitating mass production.

Note that the sheet 26 and the conductive metal wires 27 can be formed as a peeling strip. Further, the plurality of openings 261 are formed by punching on the sheet 26. The conductive metal wires 27 are also cut into a plurality of sections each having two exposed ends 271. Next, turn the peeling strip upside down so that the C.O.B. type RGB LED 21 can be fixedly coupled between two adjacent wires 27 for forming a serially coupled light source device 20.

Further note that the connection of the C.O.B. type RGB LEDs 21 and the wires 27 can be done by a plurality of soldering in one time for saving time and cost in mass production.

While the invention herein disclosed has been described by means of specific embodiments, numerous modifications and variations could be made thereto by those skilled in the art without departing from the scope of the invention set forth in the claims.