Surface illuminator and liquid crystal display having the same

• US 20060215388A1
• Filed: 03/14/2006
• Published: 09/28/2006
• Est. Priority Date: 03/22/2005
• Status: Abandoned Application

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Hamada, Tetsuya
• Application Number:
  US11/375,272
• Publication Number:
  US 20060215388A1
• Time in Patent Office: Days
• US Class Current: 362/29
• CPC Class Codes: G02B 6/0068 Arrangements of plural sources, e.g. multi-colour light sources
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 3/3413 Details of control of colour illumination sources

Abstract

The invention relates to a surface illuminator and a liquid crystal display having the same and provides a low-cost surface illuminator and a liquid crystal display having the same. A liquid crystal display includes a liquid crystal display panel provided by sealing a liquid crystal between a pair of substrates and a backlight unit serving as a surface illuminator. The backlight unit has a light exit surface from which light in a color reproduction range defined by a plurality of chromaticities exit, a light guide having a light guide region for guiding light to the light exit surface, an LED light source having a first group of light sources emitting light having a wavelength shorter than a desired wavelength toward the light guide region and a second group of light sources emitting light having a wavelength longer than the desired wavelength, and a light source driving circuit having first and second driving portions for driving the first and second groups of light sources.

Claims

1. A surface illuminator comprising:

a light exit region from which light in a color reproduction range defined by a plurality of chromaticities exits;

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

a first group of light sources emitting light toward the light guide region, the light having a wavelength shorter than a desired wavelength λ

0 providing a chromaticity X that is one of the plurality of chromaticities;

a second group of light sources emitting light toward the light guide region, the light having a wavelength longer than the desired wavelength λ

0;

a first driving portion for driving the first group of light sources; and

a second driving portion for driving the second group of light sources.

2. A surface illuminator according to claim 1, wherein the quantity of each of the light having a shorter wavelength and the light having a longer wavelength is adjusted such that the chromaticity of light obtained as a result of color mixing between the light having a shorter wavelength and the light having a longer wavelength substantially equals the chromaticity X.

3. A surface illuminator according to claim 1, wherein the light having a shorter wavelength is a monochromatic beam group a constituted by a plurality of monochromatic beams of light within a predetermined range of wavelengths and wherein the light having a longer wavelength is a monochromatic beam group β

constituted by a plurality of monochromatic beams of light within a range of wavelength different from the predetermined range of wavelength.

4. A surface illuminator according to claim 3, wherein an average wavelength λ

1 that is an average of the wavelengths of the plurality of monochromatic beams of light constituting the monochromatic beam group α

is shorter than the desired wavelength λ

0.

5. A surface illuminator according to claim 3, wherein at least one of the wavelengths of the plurality of monochromatic beams of light constituting the monochromatic beam group a is substantially equal to the desired wavelength λ

0.

6. A surface illuminator according to claim 3, wherein an average wavelength λ

2 that is an average of the wavelengths of the plurality of monochromatic beams of light constituting the monochromatic beam group β

is longer than the desired wavelength λ

0.

7. A surface illuminator according to claim 3, wherein at least one of the wavelengths of the plurality of monochromatic beams of light constituting the monochromatic beam group β

is substantially equal to the desired wavelength λ

0.

8. A surface illuminator according to claim 3, wherein the wavelengths of the plurality of monochromatic beams of light constituting the respective monochromatic beam groups α

and β

are an emission peak wavelength or a dominant wavelength.

9. A surface illuminator according to claim 1, wherein the chromaticity X is a chromaticity of red, green, or blue.

10. A surface illuminator according to claim 1, wherein the chromaticity X is any two chromaticities among the plurality of chromaticities and wherein the two chromaticities X are chromaticities of red and green, chromaticities of the red and blue, or chromaticities of the green and the blue.

11. A surface illuminator according to claim 1, wherein the chromaticity X is any three chromaticities among the plurality of chromaticities and wherein the three chromaticities X are chromaticities of red, green, and blue.

12. A surface illuminator according to claim 9, wherein the first group of light sources includes at least any one of:

a first R-emission LED emitting red light having a wavelength shorter than a desired wavelength λ

R0 which provides the chromaticity of red;

a first G-emission LED emitting green light having a wavelength shorter than a desired wavelength λ

G0 which provides the chromaticity of green; and

a first B-emission LED emitting blue light having a wavelength shorter than a desired wavelength λ

B0 which provides the chromaticity of blue and wherein the second group of light sources includes at least any one of;

a second R-emission LED emitting red light having a wavelength longer than the desired wavelength λ

R0;

a second G-emission LED emitting green light having a wavelength longer than the desired wavelength λ

G0; and

a second B-emission LED emitting blue light having a wavelength longer than the desired wavelength λ

B0.

13. A surface illuminator according to claim 12, wherein the first driving portion includes at least any one of:

a first R driving circuit for driving the first R-emission LED;

a first G driving circuit for driving the first G-emission LED; and

a first B driving circuit for driving the first B-emission LED and wherein the second driving portion includes at least any one of;

a second R driving circuit for driving the second R-emission LED;

a second G driving circuit for driving the second G-emission LED; and

a second B driving circuit for driving the second B-emission LED.

14. A surface illuminator according to claim 12, wherein:

the first group of light sources includes a plurality of the first R-emission LEDs, a plurality of the first G-emission LEDs, and a plurality of the first B-emission LEDs;

the first R-emission LED, the first G-emission LED, and the first B-emission LED are disposed such that different colors adjoin each other;

the second group of light sources includes a plurality of the second R-emission LEDs, a plurality of the second G-emission LEDs, and a plurality of the second B-emission LEDs; and

the second R-emission LED, the second G-emission LED, and the second B-emission LED are disposed such that different colors adjoin each other.

15. A surface illuminator according to claim 14, wherein the first R-emission LED, the first G-emission LED or the first B-emission LED is disposed adjacent to the second R-emission LED, the second G-emission LED or the second B-emission LED.

16. A surface illuminator according to claim 14, wherein:

the first group of light sources includes a first R-emission LED group that is a set of a plurality of the first R-emission LEDs, a first G-emission LED group that is a set of a plurality of the first G-emission LEDs, and a first B-emission LED group that is a set of a plurality of the first B-emission LEDs;

the first R-emission LED group, the first G-emission LED group, and the first B-emission LED group are disposed such that different colors adjoin each other;

the second group of light sources includes a second R-emission LED group that is a set of a plurality of the second R-emission LEDs, a second G-emission LED group that is a set of a plurality of the second G-emission LEDs, and a second B-emission LED group that is a set of a plurality of the second B-emission LEDs; and

the second R-emission LED group, the second G-emission LED group, and the second B-emission LED group are disposed such that different colors adjoin each other.

17. A surface illuminator according to claim 16, wherein the first R-emission LED group, the first G-emission LED group or the first B-emission LED group is disposed adjacent to the second R-emission LED group, the second G-emission LED group or the second B-emission LED group.

18. A surface illuminator according to claim 1, wherein the first and second groups of light sources are disposed at a side edge of the light exit surface.

19. A surface illuminator according to claim 1, wherein the first and second groups of light sources are disposed on a bottom side of the light exit surface.

20. A surface illuminator according to claim 19, wherein the first and second groups of light sources are disposed at random in a plane substantially in parallel with the bottom side of the light exit surface.

21. A surface illuminator according to claim 1, comprising:

a storage portion in which a plurality of the color reproduction ranges are stored;

a selection signal input portion to which a selection signal used for selection between the plurality of color reproduction ranges is input; and

a control portion for controlling driving conditions for the first and second driving portions based on the input selection signal.

22. A liquid crystal display comprising a liquid crystal display panel provided by sealing a liquid crystal between a pair of substrates and a surface illuminator for illuminating the liquid crystal display panel, wherein the surface illuminator is a surface illuminator according to claim 1.

23. A liquid crystal display according to claim 22, wherein the surface illuminator serves as a backlight unit.