Liquid Crystal Display Device

• US 20110134353A1
• Filed: 01/28/2011
• Published: 06/09/2011
• Est. Priority Date: 12/05/2005
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Uochi, Hideki, Kimura, Hajime
• Granted Patent: US 8,164,729 B2
• Time in Patent Office: Days
• US Class Current: 349/46
• CPC Class Codes: G02F 1/133345 Insulating layers G02F1/1335, G02F1/1337, G02F1/135, G02F1/136 take precedence
• CPC Class Codes: G02F 1/133371 Cells with varying thickness of the liquid crystal layer
• CPC Class Codes: G02F 1/133553 Reflecting elements associated to illuminating devices G02F1/133605
• CPC Class Codes: G02F 1/133555 Transflectors
• CPC Class Codes: G02F 1/134363 for applying an electric field parallel to the substrate, i.e. in-plane switching [IPS]
• CPC Class Codes: G02F 1/134372 for fringe field switching [FFS] where the common electrode is not patterned
• CPC Class Codes: G02F 1/13439 characterised by their electrical, optical, physical properties; materials therefor; method of making
• CPC Class Codes: G02F 1/136209 Light shielding layers, e.g. black matrix, incorporated in the active matrix substrate, e.g. structurally associated with the switching element
• CPC Class Codes: G02F 1/136222 Colour filters incorporated in the active matrix substrate
• CPC Class Codes: G02F 1/136227 Through-hole connection of the pixel electrode to the active element through an insulation layer
• CPC Class Codes: G02F 1/136286 Wiring, e.g. gate line, drain line
• CPC Class Codes: G02F 1/1368 in which the switching element is a three-electrode device G02F1/136277 takes precedence
• CPC Class Codes: G02F 2201/121 common or background
• CPC Class Codes: G02F 2201/123 pixel
• CPC Class Codes: G02F 2201/124 interdigital

Abstract

It is an object of the present invention to apply a sufficient electrical field to a liquid crystal material in a horizontal electrical field liquid crystal display device typified by an FFS type. In a horizontal electrical field liquid crystal display, an electrical field is applied to a liquid crystal material right above a common electrode and a pixel electrode using plural pairs of electrodes rather than one pair of electrodes. One pair of electrodes includes a comb-shaped common electrode and a comb-shaped pixel electrode. Another pair of electrodes includes a common electrode provided in a pixel portion and the comb-shaped pixel electrode.

Claims

1. A liquid crystal display device, comprising:

a substrate;

a gate electrode over the substrate;

a first common electrode formed in a same layer as the gate electrode;

an insulating layer over the gate electrode and the first common electrode;

a semiconductor layer over the gate electrode with the insulating layer therebetween;

source and drain electrodes over the semiconductor layer;

a conductive layer being in contact with the first common electrode;

a pixel electrode connected to one of the source and drain electrodes;

a second common electrode connected to the first common electrode with the conductive layer therebetween; and

a liquid crystal material over the pixel electrode and the second common electrode.

2. The liquid crystal display device according to claim 1,

wherein tilting of the liquid crystal material is controlled by an electrical field between the pixel electrode and the first common electrode, and an electrical field between the pixel electrode and the second common electrode.

3. The liquid crystal display device according to claim 1, wherein the semiconductor layer is an amorphous semiconductor layer.

4. The liquid crystal display device according to claim 1, further comprising:

a passivation layer over the first common electrode and the gate electrode;

a color filter over the first common electrode with the passivation layer therebetween, and

a black matrix over the source and drain electrodes.

5. The liquid crystal display device, according to claim 1, wherein the pixel electrode is comb-shaped.

6. The liquid crystal display device according to claim 1, wherein the first common electrode is comb-shaped.

7. The liquid crystal display device according to claim 1, wherein the second common electrode is comb-shaped.

8. The liquid crystal display device according to claim 1, wherein the pixel electrode is formed of a transparent material.

9. The liquid crystal display device according to claim 1, wherein the first common electrode is formed of a transparent material.

10. The liquid crystal display device according to claim 1, wherein the second common electrode is formed of a transparent material.

11. A liquid crystal display device, comprising:

a substrate;

a gate electrode over the substrate;

a conductive layer formed in a same layer as the gate electrode;

a first common electrode being in contact with the conductive layer;

an insulating layer over the gate electrode and the first common electrode;

a semiconductor layer over the gate electrode with the insulating layer therebetween;

source and drain electrodes over the semiconductor layer;

a pixel electrode connected to one of the source and drain electrodes;

a second common electrode connected to the first common electrode; and

a liquid crystal material over the pixel electrode and the second common electrode.

12. The liquid crystal display device according to claim 11,

wherein tilting of the liquid crystal material is controlled by an electrical field between the pixel electrode and the first common electrode, and an electrical field between the pixel electrode and the second common electrode.

13. The liquid crystal display device according to claim 11, wherein the semiconductor layer is an amorphous semiconductor layer.

14. The liquid crystal display device according to claim 11, further comprising:

a passivation layer over the first common electrode and the gate electrode;

a color filter over the source and drain electrodes and the first common electrode with the passivation layer therebetween,

a counter substrate provided to face the substrate, and

a black matrix over the counter substrate.

15. The liquid crystal display device, according to claim 11, wherein the pixel electrode is comb-shaped.

16. The liquid crystal display device according to claim 11, wherein the first common electrode is comb-shaped.

17. The liquid crystal display device according to claim 11, wherein the second common electrode is comb-shaped.

18. The liquid crystal display device according to claim 11, wherein the pixel electrode is formed of a transparent material.

19. The liquid crystal display device according to claim 11, wherein the first common electrode is formed of a transparent material.

20. The liquid crystal display device according to claim 11, wherein the second common electrode is formed of a transparent material.

21. A liquid crystal display device including a plurality of pixels, each pixel comprising:

a first reflective common electrode over a substrate;

a second transparent common electrode over the substrate;

an insulating layer over the first reflective common electrode and the second transparent electrode;

a pixel electrode over the insulating layer, the pixel electrode comprising at least a first portion and a second portion; and

a third common electrode over the insulating layer, the third common electrode comprising at least the first portion and the second portion,

wherein the first portion is located over the first reflective common electrode and the second portion is located over the transparent common electrode.

22. The liquid crystal display device, according to claim 21, wherein the first reflective common electrode and the second transparent common electrode are electrically connected to each other.

23. The liquid crystal display device, according to claim 21, wherein the first reflective common electrode has an uneven surface

24. The liquid crystal display device, according to claim 21, wherein the pixel electrode is comb-shaped.

25. The liquid crystal display device according to claim 21, wherein the first reflective common electrode is comb-shaped.

26. The liquid crystal display device according to claim 21, wherein the second transparent common electrode is comb-shaped.

27. The liquid crystal display device according to claim 21, wherein the pixel electrode is formed of a transparent material.