LIQUID CRYSTAL DISPLAY DEVICE

• US 20100296041A1
• Filed: 08/02/2010
• Published: 11/25/2010
• Est. Priority Date: 12/05/2005
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Kimura, Hajime, Uochi, Hideki
• Granted Patent: US 7,880,848 B2
• Time in Patent Office: Days
• US Class Current: 349/141
• 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 plurality of pixels each including reflective portion and transmissive portion;

the plurality of pixels each comprising;

a thin film transistor over a substrate;

a first common electrode in the transmissive portion;

a reflective electrode in the reflective portion;

a first insulating layer over the first common electrode and the reflective electrode;

a second insulating layer over the first insulating layer in the reflective portion;

a second common electrode and a pixel electrode over the second insulating layer in the reflective portion, the second common electrode and the pixel electrode being over the first insulating layer in the transmissive portion; 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 by an electrical field between the pixel electrode and the second common electrode in the reflective portion.

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

wherein the reflective electrode is electrically connected to the first common electrode.

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

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

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

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

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

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

10. A liquid crystal display device, comprising:

a plurality of pixels each including reflective portion and transmissive portion;

the plurality of pixels each comprising;

a thin film transistor over a substrate;

a first common electrode in the transmissive portion and the reflective portion;

a reflective electrode in the reflective portion;

a first insulating layer over the first common electrode and the reflective electrode;

a second insulating layer over the first insulating layer in the reflective portion;

a second common electrode and a pixel electrode over the second insulating layer in the reflective portion, the second common electrode and the pixel electrode being over the first insulating layer in the transmissive portion;

a third insulating layer interposed between the first common electrode and the reflective electrode; and

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

11. The liquid crystal display device according to claim 10,

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

12. The liquid crystal display device according to claim 10,

wherein the reflective electrode is electrically connected to the first common electrode.

13. The liquid crystal display device, according to claim 10, wherein the pixel electrode is comb-shaped.

14. The liquid crystal display device according to claim 10, wherein the first common electrode is comb-shaped.

15. The liquid crystal display device according to claim 10, wherein the second common electrode is comb-shaped.

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

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

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

19. A liquid crystal display device, comprising:

a plurality of pixels each including reflective portion and transmissive portion;

the plurality of pixels each comprising;

a thin film transistor over a substrate;

a first common electrode in the transmissive portion and the reflective portion;

a reflective electrode in the reflective portion, the reflective electrode being stacked on the first common electrode;

a first insulating layer over the first common electrode and the reflective electrode;

a second insulating layer over the first insulating layer in the reflective portion;

a second common electrode and a pixel electrode over the second insulating layer in the reflective portion, the second common electrode and the pixel electrode being over the first insulating layer in the transmissive portion;

a third insulating layer interposed between the first common electrode and the reflective electrode; and

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

20. The liquid crystal display device according to claim 19,

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

21. The liquid crystal display device, according to claim 19, wherein the pixel electrode is comb-shaped.

22. The liquid crystal display device according to claim 19, wherein the first common electrode is comb-shaped.

23. The liquid crystal display device according to claim 19, wherein the second common electrode is comb-shaped.

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

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

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