Backlight assembly of liquid crystal display

• US 7,686,494 B2
• Filed: 08/03/2006
• Issued: 03/30/2010
• Est. Priority Date: 08/04/2005
• Status: Active Grant

• Current Assignee: BOE HYDIS Technology Company Limited (SK Hynix Inc.)
• Original Assignee: Hydis Technologies Co Ltd (E Ink Holdings Incorporated)
• Inventors: Song, Young Ki
• Primary Examiner(s): Lee; Gunyoung T
• Application Number:
  US11/498,534
• Publication Number:
  US 20070035967A1
• Time in Patent Office: 1,335 Days
• Field of Search: 362/621, 362/616, 362/615, 362/628, 362/622, 362/612, 362/613, 349/62, 349/65
• US Class Current: 362/612
• CPC Class Codes: G02B 6/0016 Grooves, prisms, gratings, scattering particles or rough surfaces
• 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

Abstract

A backlight assembly having a plurality of light emitting diodes (LEDs) and a light guide plate for uniformly guiding light emitted from the LEDs to a liquid crystal substrate is provided. The backlight assembly includes a reflective structure having at least one reflective surface facing the LEDs and tilted at a constant angle. The light emitted from the LEDs is reflected by the reflective surface to have the shape of light emitted from a line light source and be incident on the light guide plate. In effect, hot spots degrading screen quality and screen brightness distribution non-uniformity can be prevented.

Claims

1. A backlight assembly having a plurality of light emitting diodes (LEDs) and a light guide plate for uniformly guiding light emitted from the LEDs to a liquid crystal substrate, the backlight assembly comprising:

a first reflective structure having at least one reflective surface facing a corresponding LED and tilted at a constant angle and a second reflective structure being independently disposed and spaced a distance from the first reflective structure,

wherein each LED is disposed to emit light to a direction substantially perpendicular to a longitudinal bisector of the light guide plate toward each facing reflective surface and none of the LEDs are disposed to emit light to a direction substantially parallel to the longitudinal bisector of the light guide plate,

wherein each LED corresponds to a single reflective surface so that the ratio of LEDs to reflective surfaces in the backlight assembly is 1 to 1,

wherein the light emitted from each of the LEDs is reflected by the corresponding reflective surface to be incident on the light guide plate in a form of line-shaped light,

wherein the backlight assembly includes at least four combinations of a LED and a corresponding reflective surface and the combinations are disposed substantially symmetrically about the longitudinal bisector of the light guide plate, and

wherein all of the LEDs are arranged along a common line that extends along a side of the light guide plate, and that common line is substantially perpendicular to the longitudinal bisector of the light guide plate.

2. The backlight assembly of claim 1, wherein a pair of LEDs facing each other and a reflective structure having two reflective surfaces disposed between the LEDs, facing the LEDs, and tilted at a constant angle constitute one group, and at least one group is disposed.

3. The backlight assembly of claim 2, wherein the group is disposed at opposite sides of the longitudinal bisector of the light guide plate as a reference.

4. The backlight assembly of claim 2, wherein the group is disposed so as to make a bisector of the reflective structure of the group match the longitudinal bisector of the light guide plate, and at least one more group is symmetrically disposed at both sides of the group as a reference.

5. The backlight assembly of claim 2, wherein the two reflective surfaces of the reflective structure of the group are in end-to-end contact with each other.

6. The backlight assembly of claim 2, wherein at least one of the two reflective surfaces of the reflective structure of the group has a predetermined radius of curvature.

7. The backlight assembly of claim 2, wherein the tilt angle of the two reflective surfaces of the reflective structure of the group ranges from 30°

to 55°

.

8. The backlight assembly of claim 2, wherein at least two groups are disposed close to each other.

9. The backlight assembly of claim 2, wherein at least two groups are spaced apart from each other by a predetermined interval.

10. The backlight assembly of claim 1, wherein a light receiving surface of the light guide plate has the same shape as the reflective surface of the first reflective structure and is disposed close to the reflective surface.

11. The backlight assembly of claim 1, wherein a light receiving surface of the light guide plate has a plurality of “

V”

-shaped grooves which are spaced apart from each other by a constant interval to further increase the divergence of light emitted from the LEDs by means of a scattering effect.

12. A backlight assembly having a plurality of light emitting diodes (LEDs) and a light guide plate for uniformly guiding light emitted from the LEDs to a liquid crystal substrate, the backlight assembly comprising:

one group consisting of a pair of LEDs facing each other, and a first reflective structure having two reflective surfaces disposed between the LEDs, each reflective surface facing one of the LEDs, and being tilted at a constant angle;

one set symmetrically disposed at each of opposite sides of the group as a reference, each set consisting of one LED, and a second reflective structure having a reflective surface tilted at a constant angle, the second reflective structure being independently disposed and spaced a distance from the first reflective structure,

wherein each LED corresponds to a single reflective surface so that the ratio of LEDs to reflective surfaces is 1 to 1,

wherein each LED is disposed to emit light to a direction substantially perpendicular to a longitudinal bisector of the light guide plate toward each facing reflective surface and none of the LEDs are disposed to emit light to a direction substantially parallel to the longitudinal bisector of the light guide plate,

wherein a bisector of the first reflective structure matches the longitudinal bisector of the light guide plate, and light emitted from each of the LEDs is reflected by the corresponding reflective surface to be incident on the light guide plate in a form of line-shaped light,

wherein the backlight assembly comprises at least four combinations of an LED and a corresponding reflective surface and the combinations are disposed substantially symmetrically about the longitudinal bisector of the light guide plate, and

wherein all of the LEDs are arranged along a common line that extends along a side of the light guide plate, and that common line is substantially perpendicular to the longitudinal bisector of the light guide plate.

13. The backlight assembly of claim 12, wherein the LEDs are disposed to emit light toward the longitudinal bisector of the light guide plate.

14. The backlight assembly of claim 12, wherein the LEDs of the one set are disposed to emit light in the opposite direction to light emitted from the LEDs of the group.

15. The backlight assembly of claim 12, wherein the two reflective surfaces of the reflective structure are in end-to-end contact with each other.

16. The backlight assembly of claim 12, wherein at least one of the two reflective surfaces of the first reflective structure has a predetermined radius of curvature.

17. The backlight assembly of claim 12, wherein the reflective surface of the second reflective structure has a predetermined radius of curvature.

18. The backlight assembly of claim 12, wherein the tilt angle of the reflective surfaces of the first and second reflective structures ranges from 30°

to 55°

.

19. The backlight assembly of claim 12, wherein the group and the respective sets are disposed close to each other.

20. The backlight assembly of claim 12, wherein the group and the respective sets are spaced apart from each other by a predetermined interval.

21. A backlight assembly having a plurality of light emitting diodes (LEDs) and a light guide plate for uniformly guiding light emitted from the LEDs to a liquid crystal substrate, the backlight assembly comprising:

at least two sets each consisting of an LED and a reflective structure having a reflective surface facing the LED and tilted at a constant angle, at least one set being symmetrically disposed at each of opposite sides of a longitudinal bisector of the light guide plate, wherein the reflective structure of a first set is independently disposed and spaced a distance from the reflective structure of a second set

wherein each LED is disposed to emit light to a direction substantially perpendicular to the longitudinal bisector of the light guide plate toward each facing reflective surface and none of the LEDs are disposed to emit light to a direction substantially parallel to the longitudinal bisector of the light guide plate,

wherein each LED corresponds to a single reflective surface such that the ratio of LEDs to reflective surfaces is 1 to 1,

wherein the light emitted from each of the LEDs is reflected by the corresponding reflective surface to be incident on the light guide plate in a form of line-shaped light,

wherein the backlight assembly includes at least four combinations of an LED and a corresponding reflective surface and the combinations are disposed substantially symmetrically about the longitudinal bisector of the light guide plate, and

wherein all of the LEDs are arranged along a common line that extends along a side of the light guide plate, and that common line is substantially perpendicular to the longitudinal bisector of the light guide plate.

22. The backlight assembly of claim 21, wherein the LEDs of the set are disposed to emit light toward the longitudinal bisector of the light guide plate.

23. The backlight assembly of claim 21, wherein the LEDs of the set are disposed to emit light in a direction away from the longitudinal bisector of the light guide plate.

24. The backlight assembly of claim 21, wherein the reflective surface of the reflective structure has a predetermined radius of curvature.

25. The backlight assembly of claim 21, wherein the tilt angle of the reflective surface of the reflective structure ranges from 30°

to 55°

.

26. The backlight assembly of claim 21, wherein the sets are disposed close to each other.

27. The backlight assembly of claim 21, wherein the sets are spaced apart from each other by a predetermined interval.