Transflective liquid crystal display device and fabrication method thereof

• US 20050001959A1
• Filed: 02/26/2004
• Published: 01/06/2005
• Est. Priority Date: 05/12/2003
• Status: Active Grant

• Current Assignee: HannStar Display Corporation
• Original Assignee: HannStar Display Corporation
• Inventors: Chang, Ching Chao
• Granted Patent: US 6,950,158 B2
• Time in Patent Office: Days
• US Class Current: 349/114
• CPC Class Codes: G02F 1/133555 Transflectors
• CPC Class Codes: G02F 1/133707 Structures for producing distorted electric fields, e.g. bumps, protrusions, recesses, slits in pixel electrodes
• CPC Class Codes: G02F 1/134318 having a patterned common electrode
• CPC Class Codes: G02F 1/1393 the birefringence of the liquid crystal being electrically controlled, e.g. ECB-, DAP-, HAN-, PI-LC cells G02F1/1396, G02F1/141 take precedence

Abstract

A transflective LCD device with a single cell gap. First and second pixel electrodes are formed on the lower substrate. First and second common electrodes are formed on an inner surface of the upper substrate. The first pixel electrodes and the first common electrodes are located in the reflective region. The second pixel electrodes and the second common electrodes are located in the transmissive region. A first orientation control window having a slit width “S_rc” is formed between the first common electrodes in an area corresponding to each first pixel electrode. A second orientation control window having a slit width “S_tc” is formed between the second common electrodes, satisfying S_rc<S_tc. The second orientation control window is in an area corresponding to each second pixel electrode. Accordingly, maximum light efficiency can be achieved in both reflective and transmissive modes.

Claims

1. A transflective liquid crystal display (LCD) device with a single cell gap, comprising:

a first substrate and a second substrate opposite thereto, wherein the transflective LCD device comprises a reflective region and a transmissive region;

a plurality of first pixel electrodes and a plurality of second pixel electrodes on the first substrate, the first pixel electrodes in the reflective region and the second pixel electrodes in the transmissive region;

a plurality of first common electrodes and a plurality of second common electrodes on an inner surface of the second substrate, the first common electrodes in the reflective region and the second common electrodes in the transmissive region;

a vertically aligned liquid crystal layer interposed between the first substrate and the second substrate, wherein orientation of the vertically aligned liquid crystal layer is controlled by an electric field between the pixel and common electrodes;

a first orientation control window having a slit width “

S_rc”

between the first common electrodes in an area corresponding to each first pixel electrode and dividing the liquid crystal layer into a plurality of orientation sections; and

a second orientation control window having a slit width “

S_tc”

between the second common electrodes in an area corresponding to each second pixel electrode and dividing the liquid crystal layer into a plurality of orientation sections;

wherein a relationship between S_rc and S_tc satisfies S_rc<

S_tc.

2. The transflective LCD device according to claim 1, wherein each first common electrode comprises an electrode width “

W_rc” and

each second common electrode comprises an electrode width “

W_tc”

, and a relationship between W_rc and W_tc satisfies W_rc<

W_tc.

3. The transflective LCD device according to claim 1, further comprising:

a first opening having a slit width “

S_rp”

between the first pixel electrodes in an area corresponding to each first common electrode; and

a second opening having a slit width “

S_tp”

between the second pixel electrodes in an area corresponding to each second common electrode;

wherein a relationship between S_rp and S_tp satisfies S_rp<

S_tp.

4. The transflective LCD device according to claim 2, wherein each first pixel electrode comprises an electrode width “

W_rp” and

each second pixel electrode comprises an electrode width “

W_tp”

, and a relationship between W_rp and W_tp satisfies W_rp<

W_tp.

5. The transflective LCD device according to claim 1, wherein the slit width “

S_rc”

of the first orientation control window ranges from 3 μ

m to 7 μ

m.

6. The transflective LCD device according to claim 1, wherein the slit width “

S_tc”

of the second orientation control window ranges from 8 μ

m to 12 μ

m.

7. The transflective LCD device according to claim 2, wherein the electrode width “

W_rc”

of each first common electrode ranges from 5 μ

m to 15 μ

m.

8. The transflective LCD device according to claim 2, wherein the electrode width “

W_tc”

of each second common electrode ranges from 15 μ

m to 25 μ

m.

9. The transflective LCD device according to claim 3, wherein the slit width “

S_rp”

of the first opening ranges from 3 μ

m to 7 μ

m.

10. The transflective LCD device according to claim 3, wherein the slit width “

S_tp”

of the second opening ranges from 8 μ

m to 12 μ

m.

11. The transflective LCD device according to claim 4, wherein the electrode width “

W_rp”

of each first pixel electrode ranges from 5 μ

m to 15 μ

m.

12. The transflective LCD device according to claim 4, wherein the electrode width “

W_tp”

of each second pixel electrode ranges from 15 μ

m to 25 μ

m.

13. The transflective LCD device according to claim 1, further comprising a gap “

d”

between the pixel and common electrodes, ranging from 3 μ

m to 5 μ

m.

14. The transflective LCD device according to claim 1, wherein configuration of the first orientation control window and the second orientation control window is a straight striped pattern.

15. The transflective LCD device according to claim 1, wherein configuration of the first orientation control window and the second orientation control window is a wedge-shaped pattern.

16. The transflective LCD device according to claim 1, further comprising:

an insulating layer on the first substrate;

a reflective layer on the insulating layer in the reflective region; and

a transparent planarization layer on the reflective layer and the insulating layer;

wherein a top surface of the insulating layer in the reflective region is higher than that in the transmissive region.

17. The transflective LCD device according to claim 1, further comprising:

an insulating layer on the first substrate;

a reflective layer on the insulating layer in the reflective region; and

a color filter on the reflective layer and the insulating layer;

wherein a top surface of the insulating layer in the reflective region is higher than that in the transmissive region.

18. The transflective LCD device according to claim 3, wherein S_rc equals S_rp and S_tc equals S_tp.

19. The transflective LCD device according to claim 4, wherein W_rc equals W_rp and W_tc equals W_tp.

20. The transflective LCD device according to claim 3, wherein the first orientation control window faces a center part of each first pixel electrode, the second orientation control window faces a center part of each second pixel electrode, the first opening faces a center part of the first common electrode and the second opening faces a center part of the second common electrode.

21. A method of fabricating a transflective liquid crystal display device, comprising the steps of:

providing a first substrate and a second substrate opposite thereto, wherein the transflective LCD device has a reflective region and a transmissive region;

forming a reflective layer overlying the first substrate in the reflective region;

forming a transparent planarization layer or a color filter overlying the reflective layer and the first substrate;

forming a plurality of first pixel electrodes and a plurality of second pixel electrodes on the transparent planarization layer or the color filter, wherein the first pixel electrodes are located in the reflective region and the second pixel electrodes in the transmissive region;

forming a plurality of first common electrodes and a plurality of second common electrodes on an inner surface of the second substrate, wherein the first common electrodes are located in the reflective region and the second common electrodes in the transmissive region; and

filling a space between the first substrate and the second substrate with liquid crystal molecules to form a vertically aligned liquid crystal layer interposed between the first substrate and the second substrate, wherein orientation of the vertically aligned liquid crystal layer is controlled by an electric field between the pixel and common electrodes;

wherein a first orientation control window having a slit width “

S_rc”

is formed between the first common electrodes in an area corresponding to each first pixel electrode, dividing the vertically aligned liquid crystal layer into a plurality of orientation sections;

wherein a second orientation control window having a slit width “

S_tc”

is formed between the second common electrodes in an area corresponding to each second pixel electrode, dividing the vertically aligned liquid crystal layer into a plurality of orientation sections;

wherein a relationship between S_rc and S_tc satisfies S_rc<

S_tc.

22. The method according to claim 21, wherein each first common electrode has an electrode width “

W_rc” and

each second common electrode an electrode width “

W_tc”

, and a relationship between W_rc and W_tc satisfies W_rc<

W_tc.

23. The method according to claim 21, further comprising the steps of:

forming a first opening having a slit width “

S_rp”

between the first pixel electrodes in an area corresponding to each first common electrode; and

forming a second opening having a slit width “

S_tp”

between the second pixel electrodes in an area corresponding to each second common electrode;

wherein a relationship between S_rp and S_tp satisfies S_rp<

S_tp.

24. The method according to claim 22, wherein each first pixel electrode has an electrode width “

W_rp” and

each second pixel electrode an electrode width “

W_tp”

, and a relationship between W_rp and W_tp satisfies W_rp<

W_tp.

25. The method according to claim 21, wherein the slit width “

S_rc”

of the first orientation control window ranges from 3 μ

m to 7 μ

m.

26. The method according to claim 21, wherein the slit width “

S_tc”

of the second orientation control window ranges from 8 μ

m to 12 μ

m.

27. The method according to claim 22, wherein the electrode width “

W_rc”

of each first common electrode ranges from 5 μ

m to 15 μ

m.

28. The method according to claim 22, wherein the electrode width “

W_tc”

of each second common electrode ranges from 15 μ

m to 25 μ

m.

29. The method according to claim 23, wherein the slit width “

S_rp”

of the first opening ranges from 3 μ

m to 7 μ

m.

30. The method according to claim 23, wherein the slit width “

S_tp”

of the second opening ranges from 8 μ

m to 12 μ

m.

31. The method according to claim 24, wherein the electrode width “

W_rp”

of each first pixel electrode ranges from 5 μ

m to 15 μ

m.

32. The method according to claim 24, wherein the electrode width “

W_tp”

of each second pixel electrode ranges from 15 μ

m to 25 μ

m.

33. The method according to claim 21, wherein a gap “

d”

is formed between the pixel and common electrodes, ranging from 3 μ

m to 5μ

m.

34. The method according to claim 21, wherein configuration of the first orientation control window and the second orientation control window is a straight striped pattern.

35. The method according to claim 21, wherein configuration of the first orientation control window and the second orientation control window is a wedge-shaped pattern.

36. The method according to claim 21, wherein the common electrodes are ITO (indium tin oxide) or IZO (indium zinc oxide) layers.

37. The method according to claim 21, wherein the pixel electrodes are ITO (indium tin oxide) or IZO (indium zinc oxide) layers.

38. The method according to claim 21, wherein the reflective layer is an aluminum or silver layer.

39. The method according to claim 21, wherein the transparent planarization layer is a SiO₂ layer.

40. The method according to claim 21, wherein the liquid crystal molecules are negative type (Δ

ε

<

0).

41. The method according to claim 23, wherein S_rc is equal to S_rp and S_tc equals S_tp.

42. The method according to claim 24, wherein W_rc is equal to W_rp and W_tc equals W_tp.

43. The method according to claim 23, wherein the first orientation control window faces a center part of each first pixel electrode, the second orientation control window faces a center part of each second pixel electrode, the first opening faces a center part of the first common electrode and the second opening faces a center part of the second common electrode.

44. The method according to claim 21, wherein an insulating layer is formed on the first substrate before forming the reflective layer and a top surface of the insulating layer in the reflective region is higher than that in the transmissive region.