Transflective type liquid crystal display device and method for manufactruing the same

• US 20050140872A1
• Filed: 10/26/2004
• Published: 06/30/2005
• Est. Priority Date: 12/30/2003
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Philips LCD Company Limited (LG Display Co., Ltd.)
• Inventors: Kang, Hoon
• Granted Patent: US 7,365,814 B2
• Time in Patent Office: Days
• US Class Current: 349/114
• CPC Class Codes: G02F 1/133371 Cells with varying thickness of the liquid crystal layer
• CPC Class Codes: G02F 1/133524 Light-guides, e.g. fibre-optic bundles, louvered or jalousie light-guides
• CPC Class Codes: G02F 1/133555 Transflectors

Abstract

A liquid crystal display device includes a first substrate, a second substrate facing the first substrate, a liquid crystal layer made of liquid crystals injected between the first and the second substrates, and a backlight assembly arranged on an outer surface of the first substrate. The first substrate has a light guiding pattern containing a periodic structure formed from a medium whose refractive index is different from the refractive index of the first substrate.

Claims

1. A transflective type liquid crystal display device comprising:

a first substrate having a light guiding pattern containing a medium whose refractive index is different from a refractive index of the first substrate;

a second substrate facing the first substrate;

a liquid crystal layer containing liquid crystals injected between the first and the second substrates; and

a backlight assembly arranged on an outer surface of the first substrate.

2. The transflective type liquid crystal display device according to claim 1, further comprising a reflector disposed on an opposing side of the first substrate as the light guiding pattern, the reflector defining a reflection region and a transmission region such that the reflector is present in the reflection region and the reflector is not present in the transmission region.

3. The transflective type liquid crystal display device according to claim 2, wherein a cell gap in the transmission region is twice a cell gap in the reflection region.

4. The transflective type liquid crystal display device according to claim 2, wherein the reflection region has a greater width than the transmission region.

5. The transflective type liquid crystal display device according to claim 1, further comprising first and second polarizing plates, whose optical transmission axes are perpendicular each other, arranged on outer surfaces of the first and the second substrates, respectively.

6. The transflective type liquid crystal display device according to claim 1, further comprising a collimator arranged between the first substrate and the backlight assembly, the collimator for modulating light provided from the backlight assembly into parallel light.

7. The transflective type liquid crystal display device according to claim 1, wherein the light guiding pattern is formed in a position that corresponds to a transmission region.

8. The transflective type liquid crystal display device according to claim 7, wherein a majority of the light guiding pattern is formed in a position that corresponds to the transmission region.

9. The transflective type liquid crystal display device according to claim 1, wherein a refractive index of the light guiding pattern is greater than a refractive index of the first substrate.

10. The transflective type liquid crystal display device according to claim 1, wherein the light guiding pattern is tapered such that a width of the light guiding pattern decreases with decreasing distance to the liquid crystal layer.

11. The transflective type liquid crystal display device according to claim 1, wherein the light guiding pattern guides light to a transmission region by reflecting light provided from the backlight assembly inside the light guiding pattern using total internal reflection.

12. The transflective type liquid crystal display device according to claim 1, wherein the light guiding pattern is a V-shaped pattern.

13. The transflective type liquid crystal display device according to claim 1, wherein the light guiding pattern is a rectangular shaped pattern.

14. The transflective type liquid crystal display device according to claim 2, further comprising a passivation layer on which the reflector is disposed.

15. The transflective type liquid crystal display device according to claim 14, wherein the passivation layer is disposed only in the reflection region.

16. The transflective type liquid crystal display device according to claim 14, further comprising a pixel electrode on which the passivation layer is disposed.

17. The transflective type liquid crystal display device according to claim 2, wherein each element of the light guiding pattern corresponds with a portion of the transmission region, and a width of each element of the light guiding pattern is greater than a width of the corresponding portion of the transmission region.

18. The transflective type liquid crystal display device according to claim 1, wherein the light guiding pattern is a periodic structure.

19. The transflective type liquid crystal display device according to claim 1, wherein the light guiding pattern extends from the outer surface of the first substrate towards the liquid crystal layer.

20. The transflective type liquid crystal display device according to claim 19, wherein the light guiding pattern terminates before reaching an inner surface of the first substrate opposing the outer surface of the first substrate.

21. The transflective type liquid crystal display device according to claim 19, wherein the light guiding pattern at the outer surface of the first substrate covers substantially all of the outer surface of the first substrate.

22. A method for manufacturing a transflective type liquid crystal display device having first and second substrates, a liquid crystal layer interposed between the first and the second substrates, and a backlight assembly arranged outside the first substrate, the method comprising:

forming a predetermined pattern on a lower side of the first substrate to be adjacent to the backlight assembly; and

depositing a medium in the predetermined pattern to form a light guiding pattern, the medium having refractive index different from a refractive index of the first substrate.

23. The method according to claim 22, wherein the light guiding pattern is tapered such that a width of the light guiding pattern decreases from the lower side of the first substrate.

24. The method according to claim 22, wherein the light guiding pattern is formed by etching.

25. The method according to claim 22, further comprising assembling the device such that the light guiding pattern is disposed at a position that corresponds to a transmission region.

26. The method according to claim 25, wherein a majority of the light guiding pattern is disposed at the position that corresponds to the transmission region.

27. The method according to claim 22, further comprising arranging the first substrate such that the light guiding pattern guides light to a transmission region by reflecting light provided from the backlight assembly inside the light guiding pattern using total internal reflection.

28. The method according to claim 22, wherein a refractive index of the light guiding pattern is greater than that of the first substrate.

29. The method according to claim 22, further comprising forming a reflector on an opposing side of the first substrate as the light guiding pattern, the reflector defining a reflection region and a transmission region such that the reflector is present in the reflection region and the reflector is not present in the transmission region.

30. The method according to claim 29, wherein a cell gap in the transmission region is twice a cell gap in the reflection region.

31. The method according to claim 22, further comprising forming the reflector on a passivation layer.

32. The method according to claim 31, further comprising removing a portion of the reflector and the underlying passivation layer such that the passivation layer is disposed only in the reflection region.

33. The method according to claim 31, further comprising forming the passivation layer on a pixel electrode.

34. The method according to claim 29, wherein each element of the light guiding pattern corresponds with a portion of the transmission region, and a width of each element of the light guiding pattern is greater than a width of the corresponding portion of the transmission region.

35. The method according to claim 22, wherein the light guiding pattern is a periodic structure.

36. The method according to claim 22, wherein the light guiding pattern extends from the outer surface of the first substrate towards the liquid crystal layer.

37. The method according to claim 36, wherein the light guiding pattern terminates before reaching an inner surface of the first substrate opposing the outer surface of the first substrate.

38. The method according to claim 36, wherein the light guiding pattern at the outer surface of the first substrate covers substantially all of the outer surface of the first substrate.

39. A display device comprising:

a light provider; and

a substrate having a periodic light guiding pattern formed therein, the light guiding pattern and substrate having different refractive indices that are different enough such that light from the light provider entering the light guiding pattern is directed by total internal reflection towards a front surface of the display device.

40. The display device according to claim 39, further comprising a reflector disposed on a reflecting region of an opposing side of the substrate as the light guiding pattern, a transmission region of the opposing side of the substrate devoid of the reflector.

41. The display device according to claim 40, wherein a cell gap in the transmission region is twice a cell gap in the reflection region.

42. The display device according to claim 40, wherein the reflection region has a greater width than the transmission region.

43. The display device according to claim 39, wherein the light guiding pattern is tapered such that a width of the light guiding pattern decreases with increasing distance from the light provider.

44. The display device according to claim 40, further comprising a passivation layer on which the reflector is disposed, the passivation layer disposed only in the reflection region.

45. The display device according to claim 44, further comprising a transparent electrode disposed on the substrate and on which the passivation layer is disposed.

46. The display device according to claim 40, wherein each element of the light guiding pattern corresponds with a portion of the transmission region, and a width of each element of the light guiding pattern is greater than a width of the corresponding portion of the transmission region.

47. The display device according to claim 39, wherein the light guiding pattern extends from a surface of the substrate facing the light provider and terminates before reaching an opposing surface.

48. A display device having a front surface viewed by a viewer, the display device comprising:

a light provider;

a reflector to reflect light from a light source external to the device towards the front surface; and

means for redirecting light from the light supplier through total internal reflection towards the front surface.

49. The display device according to claim 48, wherein reflector has holes disposed therein and the means for redirecting directs the light through the holes.

50. The display device according to claim 49, wherein an area of the holes is smaller than an area of the reflector.