Backlight and liquid crystal display device

• US 20060262564A1
• Filed: 05/17/2006
• Published: 11/23/2006
• Est. Priority Date: 05/17/2005
• Status: Active Grant

• Current Assignee: HannStar Display Corporation
• Original Assignee: NEC LCD Technologies Limited (Tianma Microelectronics Company Limited)
• Inventors: Baba, Masatake
• Granted Patent: US 7,413,334 B2
• Time in Patent Office: Days
• US Class Current: 362/616
• CPC Class Codes: G02B 6/0018 Redirecting means on the surface of the light guide
• CPC Class Codes: G02B 6/0021 for housing at least a part of the light source, e.g. by forming holes or recesses
• CPC Class Codes: G02B 6/0031 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0076 Stacked arrangements of multiple light guides of the same or different cross-sectional area
• CPC Class Codes: G02B 6/0078 Side-by-side arrangements, e.g. for large area displays

Abstract

A plurality of LEDs are arrayed in a single row between the opposing end faces of a pair of first and second light guide plates that are disposed so that the end faces thereof face each other. A reflective sheet is disposed on the lower surfaces of the pair of first and second light guide plates, and a separation plate is disposed so as to cover the upper surfaces of the first and second light guide plates and the gap therebetween. A reflecting body for guiding light emitted upward from the LEDs to the first and second light guide plates is disposed in the area immediately above the LEDs on the lower surface of the separation plate. A diffusion plate is disposed with a fixed gap above the separation plate, and a hollow area is formed between the diffusion plate and the separation plate. Reflectors for causing light emitted from the first and second light guide plates to enter the hollow area are disposed at the end faces of the first and second light guide plates that face the LEDs. A thin, lightweight, and highly efficient backlight and liquid crystal display device can thereby be obtained without nonuniformity of color and brightness attributable to the LEDs.

Claims

1. A backlight, comprising:

first and second light guide plates disposed so that the end faces thereof face each other having an interval;

a light source disposed between the mutually opposing end faces of said first and second light guide plates;

an emitter having a hollow interior and disposed above said first and second light guide plates and said light source;

wherein said emitter emits light propagated from said light source through said first light guide plate and light propagated from said light source through said second light guide plate.

2. A backlight, comprising:

first and second light guide plates disposed so that the end faces thereof face each other having an interval;

a light source disposed between the mutually opposing end faces of said first and second light guide plates;

a diffusion plate disposed above said first and second light guide plates and said light source with a gap;

a hollow area formed between said first and second light guide plates and said diffusion plate;

first and second reflectors for introducing light propagated from said light source through said first light guide plate and light propagated from said light source through said second light guide plate to said hollow area,

wherein light entered to said hollow area is reflected at the interface between said hollow area and said first and second light guides and is emitted through said diffusion plate.

3. A backlight according to claim 2, further comprising:

a separation plate disposed so as to cover the upper surface of said first and second light guide plates and the gap between said first and second light guide plates, and optically separates said hollow area and said first and second light guide plates.

6. The backlight according to claim 3, wherein said light source includes one or plurality of light-emitting diodes.

8. The backlight according to claim 3, wherein said light source has a first light source for emitting red light, a second light source for emitting green light, and a third light source for emitting blue light.

10. The backlight according to claim 3, wherein the upper surface of said light-emitting light source has two-dimensionally curved surface.

12. The backlight according to claim 3, further comprising a first reflecting member disposed above said light source and reflecting light emitted from said light source toward said first light guide plate or said second light guide plate.

14. The backlight according to claim 12, wherein

said first reflecting member has a cross section whose center portion projects toward said light source and has two sloping surfaces from the center portion toward the two side portions;

the two sloping surfaces are two-dimensionally curved so as to be upwardly convex; and

said sloping surfaces are concave.

16. The backlight according to claim 2, further comprising a second reflecting member formed on said separation plate for changing an angle of light entered to said hollow area.

17. The backlight according to claim 3, further comprising a second reflecting member formed on said separation plate for changing an angle of light entered to said hollow area.

18. The backlight according to claim 14, wherein

R/D is 1 to 2;

and

the thickness T is D−

2 mm or greater and D+2 mm or less, where R is the radius of curvature of the sloping surface of said first reflecting member, D is the diameter of the curved surface of the upper surface of said light source, and T is the thickness of said first and second light guide plates.

20. A liquid crystal display device, comprising:

a liquid crystal panel; and

a backlight disposed behind said liquid crystal panel and supplying light to the liquid crystal panel,

wherein said backlight is the backlight according to claim 3.

4. A backlight, comprising:

first and second light guide plates disposed so that the end faces thereof face each other having an interval;

a light source disposed between the mutually opposing end faces of said first and second light guide plates;

a third light guide plate disposed above said first and second light guide plates and said light source;

a separation plate disposed between said first and second light guide plates and said third light guide plate to separate optically said first and second light guide plates and said third light guide plate; and

first and second reflectors for introducing light propagated from said light source through said first light guide plate and light propagated from said light source through said second light guide plate to said third light guide plate,

wherein light entered to said third light guide plate is reflected at the upper surface of said separation plate and is emitted from the surface of said third light guide plate that is on the opposite side from said separation plate.

5. The backlight according to claim 4, further comprising:

a scattering and reflecting member provided at the surface of the third light guide plate on the separation plate side, wherein light entered said third light guide plate is reflected at the scattering and reflecting member and is emitted from the surface of the third light guide plate that is on the opposite side from the separation plate.

7. The backlight according to claim 4, wherein said light source includes one or plurality of light-emitting diodes.

9. The backlight according to claim 4, wherein said light source has a first light source for emitting red light, a second light source for emitting green light, and a third light source for emitting blue light.

11. The backlight according to claim 4, wherein said light-emitting light source has two-dimensionally curved surface.

13. The backlight according to claim 4, further comprising a first reflecting member disposed above said light source and reflecting light emitted from said light source toward said first light guide plate or said second light guide plate.

15. The backlight according to claim 13, wherein

said first reflecting member has a cross section whose center portion projects toward said light source and has two sloping surfaces from the center portion toward the two side portions;

the two sloping surfaces are two-dimensionally curved so as to be upwardly convex; and

said sloping surfaces are concave.

19. The backlight according to claim 15, wherein

R/D is 1 to 2;

and

the thickness T is D−

2 mm or greater and D+2 mm or less, where R is the radius of curvature of the sloping surface of said first reflecting member, D is the diameter of the curved surface of the upper surface of said light source, and T is the thickness of said first and second light guide plates.

21. A liquid crystal display device, comprising:

a liquid crystal panel; and

a backlight disposed behind said liquid crystal panel and supplying light to the liquid crystal panel,

wherein said backlight is the backlight according to claim 4.