Backlight unit and liquid crystal display apparatus employing the same

• US 20060077692A1
• Filed: 09/22/2005
• Published: 04/13/2006
• Est. Priority Date: 09/25/2004
• Status: Abandoned Application

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Noh, Ji-whan, Lee, Kye-hoon
• Application Number:
  US11/231,929
• Publication Number:
  US 20060077692A1
• Time in Patent Office: Days
• US Class Current: 362/625
• CPC Class Codes: G02B 6/003 Lens or lenticular sheet or layer
• CPC Class Codes: G02B 6/0031 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0068 Arrangements of plural sources, e.g. multi-colour light sources

Abstract

A backlight unit and a liquid crystal display (LCD) apparatus employing the backlight unit. The backlight unit includes a plurality of light-emitting device units disposed on a base plate in an array, each light-emitting device unit including a collimator to collimate light emitted by a light-emitting device so that the light propagates in a principal propagation direction of light emitted from light-emitting device, a plurality of side reflectors disposed in an array above the array of corresponding light-emitting device units and to reflect lateral light incident from the corresponding light-emitting device units, a reflective diffusion plate to reflect and diffuse light incident from the side reflectors, and a transmissive diffusion plate that is disposed above the light-emitting device units, to transmit and diffuse the incident and reflected light.

Claims

1. A backlight unit comprising:

a plurality of light-emitting device units disposed on a base plate in an array, each light-emitting device unit including a collimator to collimate light emitted by a light-emitting device so that the light propagates in a principal propagation direction;

a plurality of side reflectors disposed in the principal propagation direction opposite to the corresponding light-emitting device units, to reflect the light incident from the corresponding light-emitting device units in lateral directions;

a reflective diffusion plate to reflect and diffuse the light reflected by the side reflectors; and

a transmissive diffusion plate that is disposed behind the light-emitting device units in the principal propagation direction, to transmit and diffuse the incident and reflected light.

2. The backlight unit of claim 1, wherein the collimator comprises:

a transparent body;

a reflecting surface formed on an outside surface of the transparent body, reflecting light emitted from the light-emitting device; and

a lens portion formed in a center of the transparent body, to reflect incident light.

3. The backlight unit of claim 2, wherein the reflecting surface has a parabolic or a conical shape.

4. The backlight unit of claim 2, wherein the lens portion has a curved surface to serve as a convex lens.

5. The backlight unit of claim 2, wherein the side reflector is conical or curved cone shaped to uniformly reflect the light in the lateral directions.

6. The backlight unit of claim 2, wherein the side reflectors are disposed on a surface of the transmissive diffusion plate.

7. The backlight unit of claim 1, wherein the side reflector is conical or curved cone shaped to uniformly reflect light beams in the lateral directions.

8. The backlight unit of claim 1, wherein the side reflectors are disposed on a surface of the transmissive diffusion plate.

9. The backlight unit of claim 1, wherein each of the light-emitting device units emits one of red, green, and blue color beams or white light.

10. The backlight unit of claim 1, further comprising:

at least one of a brightness enhancement film (BEF) to improve directivity of the light traveling in the principal propagation direction; and

a polarization enhancement film to increase an efficiency of polarization of the light traveling in the principal propagation direction.

11. A liquid crystal display apparatus comprising:

a liquid crystal panel; and

a backlight including;

a plurality of light-emitting device units disposed on a base plate in an array, each light-emitting device unit including a collimator to collimate light emitted by a light-emitting device so that the light propagates in a principal propagation direction,

a plurality of side reflectors disposed in an array above the array of corresponding light-emitting device units, to reflect in lateral directions the light incident from the corresponding light-emitting device units,

a reflective diffusion plate to reflect and diffuse light reflected by the side reflectors, and

a transmissive diffusion plate that is disposed above the light-emitting device units, to transmit and diffuse the incident and reflected light toward the liquid crystal panel.

12. The apparatus as in claim 11, wherein the collimator comprises:

a transparent body;

a reflecting surface that is formed on the outside surface of the transparent body and reflects the light emitted from the light-emitting device in the principal propagation direction; and

a lens portion that is formed in a center of the transparent body and refracts the incident light in the principal propagation direction.

13. The apparatus of claim 12, wherein the reflecting surface has a parabolic or conical shape.

14. The apparatus of claim 12, wherein the lens portion has a curved surface to serve as a convex lens.

15. The apparatus of claim 12, wherein the side reflector is conical or curved cone shaped to uniformly reflect the light in the lateral directions.

16. The apparatus of claim 12, wherein the side reflectors are disposed on a surface of the transmissive diffusion plate.

17. The apparatus of claim 11, wherein the side reflector is conical or curved cone shaped to uniformly reflect light beams in the lateral directions.

18. The apparatus of claim 11, wherein the side reflectors are disposed on a surface of the transmissive diffusion plate.

19. The apparatus of claim 11, wherein the liquid panel displays a color image, and each of the light-emitting device units emits one of red, green, and blue color beams or white light.

20. The apparatus of claim 11, wherein the backlight unit further comprises:

at least one of a brightness enhancement film (BEF) to improve directivity of the light escaping from the transmissive diffusion plate; and

a polarization enhancement film to increase efficiency of light polarization.

21. A method of providing a backlight to a panel, the method comprising:

emitting light by an array of light-emitting device units disposed on a base plate in an array, each light-emitting device unit including a collimator to collimate light emitted by a light-emitting device so that the light propagates in a principal propagation direction;

reflecting in lateral directions the light incident from the light-emitting units, by a plurality of side reflectors disposed above each light-emitting device unit;

reflecting and diffusing the lateral reflected light; and

transmitting and diffusing the light in the principal propagation direction.

22. A backlight unit comprising:

a base plate;

a reflective diffusing plate formed on the base plate;

a plurality of light-emitting device units disposed on the reflective diffusing plate and spaced apart from each other to emit light in a principal propagation direction;

a transmission diffusion plate spaced apart from the reflecting diffusing plate; and

a plurality of side reflectors formed on the transmissive diffusion plate to reflect the light from corresponding ones of the plurality of light-emitting device units, in a lateral direction.

23. The backlight of claim 22, wherein each of the plurality of light-emitting device units comprises:

a base;

a LED disposed on the base to emit the light; and

a collimator disposed on the base and LED to collimate the light toward the corresponding side reflector.

24. The backlight of claim 23, wherein the collimator comprises:

a reflecting surface to reflect the emitted light; and

a major surface to output the collimated light and the emitted light toward the corresponding side reflector.

25. The backlight of claim 24, wherein the major surface comprises a curved portion and a flat portion.

26. The backlight of claim 25, wherein a surface of each side reflectors comprises a first area to reflect the light from the flat portion of the major surface, and a second area to reflect the light from the curved portion of the major surface, respectively.

27. The backlight of claim 25, wherein the light-emitting device comprises a first light and a second light, and the collimator collimates the first light through the reflecting surface and the flat surface and the collimator collimates the second light through the curved surface.

28. The backlight of claim 24, wherein the collimator comprises a groove formed by the curved portion and a plane of the flat portion to prevent the light emitted from the LED to output directly through the flat surface.

29. The backlight of claim 24, wherein the reflecting surface forms an outer-side surface of the collimator between the major surface and the reflective diffusing plate to reflect the light.

30. The backlight of claim 22, further comprising:

a brightness enhancement film disposed on the transmissive diffusion plate opposite to the plurality of side reflectors to improve directivity of light propagating in the principal propagation direction; and

a polarization enhancement film disposed on the brightness enhancement film opposite to the transmissive diffusion plate to improve select light with one polarization direction.

31. A method to form a backlight unit comprising:

forming a base plate;

forming a reflective diffusing plate formed on the base plate;

placing a plurality of light-emitting device units on the reflective diffusing plate to be spaced apart from each other so that the light-emitting device units emit light in a principal propagation direction;

forming a transmission diffusion plate to be spaced apart from the reflecting diffusing plate; and

forming a plurality of side reflectors formed on the transmissive diffusion plate to reflect the light from each of corresponding light-emitting device units, in lateral directions.