Liquid crystal display device

• US 8,525,952 B2
• Filed: 04/16/2008
• Issued: 09/03/2013
• Est. Priority Date: 04/20/2007
• Status: Active Grant

• Current Assignee: Panasonic Intellectual Property Corporation of America (Panasonic Holdings Corporation)
• Original Assignee: Hitachi Displays Limited (Japan Display Incorporated), Panasonic Liquid Crystal Display Company Limited (Panasonic Holdings Corporation)
• Inventors: Tanaka, Toshiaki, Kaneko, Hiroki, Hiyama, Ikuo
• Primary Examiner(s): Glick, Edward
• Assistant Examiner(s): Kim, Dennis Y
• Application Number:
  US12/103,742
• Publication Number:
  US 20080259252A1
• Time in Patent Office: 1,966 Days
• Field of Search: 349/69
• US Class Current: 349/69
• CPC Class Codes: F21K 9/60 Optical arrangements integrated in the light source, e.g. for improving the colour rendering index or the light extraction
• CPC Class Codes: G02F 1/133603 with LEDs
• CPC Class Codes: G02F 1/133612 Electrical details
• CPC Class Codes: G02F 1/133621 providing coloured light G02F1/133617, G02F1/133533 take precedence
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2320/041 Temperature compensation
• CPC Class Codes: G09G 3/3413 Details of control of colour illumination sources
• CPC Class Codes: H05B 45/397 Current mirror circuits
• CPC Class Codes: H05B 45/40 Details of LED load circuits
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

An illumination device includes a light source module, the module comprising: a substrate; a plurality of wiring lines provided on the substrate; and a plurality of LED devices implemented in the wiring lines: wherein the plurality of LED devices include a plurality of red LED devices, a plurality of green LED devices, and a plurality of blue LED devices: wherein the plurality of wiring lines include a wiring line having the plurality of red LED devices implemented in series, a wiring line having the plurality of green LED devices implemented in series, and a wiring line having the plurality of blue LED devices implemented in series; and wherein the plurality of wiring lines are connected in parallel and driven by a single power voltage.

Claims

1. An illumination device including a plurality of light source modules, being connected in parallel and driven by a single power voltage, each of the plurality of light source modules comprising:

a substrate;

at least four red LED devices provided on the substrate;

at least four green LED devices provided on the substrate;

at least four blue LED devices provided on the substrate;

three wiring lines being connected in parallel, including a wiring line having the at least four red LED devices implemented in series;

a wiring line having the at least four green LED devices implemented in series; and

a wiring line having the at least four blue LED devices implemented in series;

at least one zener diode having an operating voltage which varies in accordance with temperature, being provided respectively in at least one of the three wiring lines so as to compensate a voltage variation with temperature of the LED devices provided respectively in the at least one of the three wiring lines under a condition of constant luminance and constant light intensity; and

a power supply circuit for driving both of (a) a control signal timing controller circuit mounted on a liquid crystal display device and (b) the plurality of light source modules connected in parallel according to the single power voltage, the power supply circuit being built in the liquid crystal display device.

2. The illumination device according to claim 1, wherein:

the LED devices provided in each of the plurality of light source modules include n(R) red LED devices, n(G) green LED devices, and n(B) blue LED devices;

the red LED devices, the green LED devices, and the blue LED devices operate on voltages V(R), V(G), and V(B), respectively; and

a relation of n(R)≧

n(G)=n(B) or n(R)×

V(R)=n(G)×

V(G)=n(B)×

V(B) is satisfied.

3. The illumination device according to claim 1, wherein:

the plurality of LED devices provided in the light source module are implemented with a number ratio of 3;

2;

2 for red LED devices;

green LED devices;

blue LED devices.

4. The illumination device according to claim 1, wherein:

the single power voltage has a value of 6 mV (m is an integer).

5. The illumination device according to claim 4, wherein:

each of the plurality of light source modules is composed of six red LED devices, four green LED devices, and four blue LED devices; and

each of the plurality of light source modules operates on a 12V power voltage.

6. A liquid crystal display device including the illumination device according to claim 4, and a liquid crystal display panel which receives light from the illumination device, wherein:

the plurality of light source modules are driven by the same voltage as a 12V power voltage for a timing controller circuit supplied from a power supply mounted on the liquid crystal display panel; and

each of the plurality of light source modules independently performs luminance control.

7. The liquid crystal display device according to claim 6, further comprising a driver circuit which drives the LED devices, wherein the timing controller circuit is utilized together with the driving circuit for control of the LED devices.

8. The illumination device according to claim 1, wherein:

each of the plurality of light source modules is composed of 12 red LED devices, eight green LED devices, and eight blue LED devices; and

each of the plurality of light source modules operates on a 24V power voltage.

9. A liquid crystal display device including the illumination device according to claim 8 and a liquid crystal display panel which receives light from the illumination device, wherein:

the plurality of light source modules are driven by a 24V power supply for AC-DC conversion mounted on the liquid crystal display panel.

10. The liquid crystal display device according to claim 9, wherein:

each of the plurality of light source modules independently performs luminance control.

11. The illumination device according to claim 1, wherein:

any of the plurality of red LED devices, the plurality of green LED devices, or the plurality of blue LED devices include two or more types of LED devices having different wavelengths.

12. The illumination device according to claim 11, wherein:

the plurality of red LED devices include two types of LED devices having different luminescence wavelengths for a light source and infrared communication.

13. The illumination device according to claim 1, wherein:

each of the three wiring lines has a device resistor so as to enable to be driven by the single power voltage at a predetermined temperature.

14. The illumination device according to claim 13, wherein:

each of the three wiring lines has the device resistor with a laser processed cut therein so as to adjust a resistance thereof.

15. The illumination device according to claim 1, wherein:

the at least one zener diode has the operating voltage which varies with a positive temperature coefficient so as to compensate the voltage variation with temperature of the LED devices having a negative temperature coefficient.

16. The illumination device according to claim 15, wherein:

one of a number of the at least four green LED devices and a number of the at least four blue LED devices in each of the plurality of light source modules is four;

the at least one zener diode includes one zener diode provided in one of the wiring lines of the green LED devices and the blue LED devices; and

the power voltage has a value of 24 V.

17. The illumination device according to claim 1, wherein:

the single power voltage has a value of 12 V or 24 V.

18. The illumination device according to claim 17, wherein:

a number of the at least four red LED devices in each of the plurality of light source modules is four;

the at least one zener diode is one zener diode provided in the wiring line of the red LED devices; and

the power voltage has a value of 12 V.

19. A liquid crystal display device comprising:

a liquid crystal display panel including a pair of transparent substrate and a liquid crystal layer arranged between the pair of transparent substrate; and

an illumination device includes a plurality of light source modules, being connected in parallel and driven by a single power voltage, each of the plurality of light source modules comprising;

a substrate;

at least four red LED devices provided on the substrate;

at least four green LED devices provided on the substrate;

at least four blue LED devices provided on the substrate;

three wiring lines being connected in parallel, including a wiring line having the at least four red LED devices implemented in series;

a wiring line having at least four green LED devices implemented in series; and

a wiring line having the at least four blue LED devices implemented in series;

at least one zener diode having an operating voltage which varies in accordance with temperature, being provided respectively in at least one of the three wiring lines so as to compensate a voltage variation with temperature of the LED devices provided respectively in the at least one of the three wiring lines under a condition of constant luminance and constant light intensity; and

a power supply circuit for driving both of (a) a control signal timing controller circuit mounted on the liquid crystal display device and (b) the plurality of light source modules connected in parallel according to the single power voltage, the power supply circuit being built in the liquid crystal display device.

20. The liquid crystal display device according to claim 19, wherein:

each of the plurality of light source modules independently performs luminance control.