Surface illuminator and liquid crystal display having the same

• US 20060221636A1
• Filed: 03/22/2006
• Published: 10/05/2006
• Est. Priority Date: 03/29/2005
• Status: Active Grant

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Ohashi, Noriyuki, Hamada, Tetsuya
• Granted Patent: US 7,736,047 B2
• Time in Patent Office: Days
• US Class Current: 362/612
• CPC Class Codes: G02B 6/0068 Arrangements of plural sources, e.g. multi-colour light sources
• CPC Class Codes: H05B 45/20 Controlling the colour of the light
• CPC Class Codes: H05B 45/48 having LEDs organised in strings and incorporating parallel shunting devices

Abstract

The invention provides a surface illuminator capable of achieving high display quality by employing an array of discrete light sources constituted by a plurality of LEDs and a liquid crystal display having the same. The surface illuminator includes an LED module which is a plurality of LEDs alternately and discretely provided along a light entrance surface and a color irregularity correcting resistor which is connected in parallel with a predetermined LED at an end of the LED module and which provides a bypass for a current supplied to the LED.

Claims

1. A surface illuminator comprising:

a light exit region which spreads in the form of a plane and from which light exits;

a light guide region for guiding light to the light exit region;

a light entrance surface through which light enters the light guide region;

a reflective surface extending from an end of the light entrance surface and reflecting light in the light guide region;

an LED module including a plurality of LEDs alternately and discretely provided along the light entrance surface; and

a color irregularity correcting resistor connected in parallel with predetermined one or more of the LEDs.

2. A surface illuminator according to claim 1, wherein the color irregularity correcting resistor is a variable resistor.

3. A surface illuminator according to claim 1, wherein a switch is provided in series with the color irregularity correcting resistor.

4. A surface illuminator according to claim 1 comprising a second color irregularity correcting resistor connected in series with the predetermined LED.

5. A surface illuminator according to claim 1, wherein the predetermined LED is at least one of three LEDs provided at an end of the LED module located on the side of the reflective surface.

6. A surface illuminator according to claim 1, wherein the predetermined LEDs are at least two among three LEDs provided at an end of the LED module located on the side of the reflective surface.

7. A surface illuminator according to claim 1, wherein the predetermined LEDs are three LEDs or LEDs in a quantity that is a multiple of three, provided at an end of the LED module located on the side of the reflective surface.

8. A surface illuminator according to claim 1, wherein the LEDs have different spectral characteristics.

9. A surface illuminator according to claim 1, wherein the predetermined LEDs are four LEDs or LEDs in a quantity that is a multiple of four having three types of spectral characteristics, provided at an end of the LED module located on the side of the reflective surface.

10. A surface illuminator according to claim 1, wherein the predetermined LEDs are four LEDs or LEDs in a quantity that is a multiple of four having four types of spectral characteristics, provided at an end of the LED module located on the side of the reflective surface.

12. A surface illuminator according to claim 1, wherein four of the LEDs at the end of the LED module on the side of the reflective surface are arranged in the order of green, red, blue, and green from the end.

13. A surface illuminator according to claim 1, wherein four of the LEDs at the end of the LED module on the side of the reflective surface are arranged in the order of green, blue, red, and green from the end.

24. A surface illuminator according to claim 1, wherein the LEDs are arranged in the same order of colors from both ends of the reflective surface.

25. A surface illuminator according to claim 1, wherein optical sensors for controlling luminance and chromaticity are provided at four corners and the center of a back side or front side of the light exit region.

26. A surface illuminator according to claim 1, wherein the LED module is provided on one side of the light entrance surface.

27. A surface illuminator according to claim 1, comprising a housing constituted by a sheet metal or mold having an adjusting hole to allow the color irregularity (luminance irregularity) correcting resistor to be adjusted from outside.

28. A surface illuminator according to claim 1, wherein color irregularities are reduced when displaying white by matching the luminance ratios of beams of light in primary colors from the LEDs at the four corners and making the peripheral luminance ratios of the colors uniform.

29. A liquid crystal display having a liquid crystal sealed between a pair of substrates provided opposite to each other, the display comprising a surface illuminator according to claim 1.

11. A surface illuminator comprising:

a light exit region which spreads in the form of a plane and from which light exits;

a light guide region for guiding light to the light exit region;

a light entrance surface through which light enters the light guide region;

a reflective surface extending from an end of the light entrance surface and reflecting light in the light guide region; and

an LED module including a plurality of LEDs alternately and discretely provided along the light entrance surface, at least one of the LEDs at an end of the module on the side of the reflective surface being separately driven;

14. A surface illuminator comprising:

a light exit region which spreads in the form of a plane and from which light exits;

a light guide region for guiding light to the light exit region;

a light entrance surface through which light enters the light guide region;

a reflective surface extending from an end of the light entrance surface and reflecting light in the light guide region; and

an LED module including a plurality of LEDs alternately and discretely provided along the light entrance surface, at least one white LED being provided at an end of the module on the side of the reflective surface.

15. A surface illuminator according to claim 14, comprising:

a luminance irregularity correcting resistor connected in parallel with the white LED; and

a switch for switching the luminance irregularity correcting resistor.

16. A surface illuminator according to claim 14, the white LED is separately driven.

17. A surface illuminator comprising:

a light exit region which spreads in the form of a plane and from which light exits;

a light guide region for guiding light to the light exit region;

a light entrance surface through which light enters the light guide region;

a reflective surface extending from an end of the light entrance surface and reflecting light in the light guide region; and

an LED module including LEDs in three colors, i.e., yellow, cyan, and magenta provided at an end thereof on the side of the reflective surface and red, green, and blue LEDs alternately and discretely provided along the light entrance surface starting at the fourth place from the end.

19. A surface illuminator according to claim 17, comprising:

a color irregularity correcting resistor connected in parallel with the LED at the end of the module on the side of the reflective surface; and

a switch for switching the color irregularity correcting resistor.

20. A surface illuminator according to claim 17, wherein the LEDs on the side of the reflective surface are separately driven.

18. A surface illuminator comprising:

a light exit region which spreads in the form of a plane and from which light exits;

a light guide region for guiding light to the light exit region;

a light entrance surface through which light enters the light guide region;

a reflective surface extending from an end of the light entrance surface and reflecting light in the light guide region; and

an LED module including LEDs in two colors among three colors, i.e., yellow, cyan, and magenta provided at an end thereof on the side of the reflective surface, one red or blue LED provided in the third place from the end, and red, green, and blue LEDs alternately and discretely provided along the light entrance surface starting at the fourth place from the end.

21. A surface illuminator comprising:

a light exit region which spreads in the form of a plane and from which light exits;

a light guide region for guiding light to the light exit region;

a light entrance surface through which light enters the light guide region;

a reflective surface extending from an end of the light entrance surface and reflecting light in the light guide region;

an LED module including a plurality of LEDs alternately and discretely provided along the light entrance surface; and

a color irregularity correcting LED provided at each of four corners of the light exit region.

22. A surface illuminator according to claim 21, comprising a correcting resistor connecting in parallel with the color irregularity correcting LED.

23. A surface illuminator according to claim 21, wherein the color irregularity correcting LED is separately driven.