Liquid crystal display device

• US 9,823,526 B2
• Filed: 03/14/2016
• Issued: 11/21/2017
• 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
• Primary Examiner(s): Wong, Tina
• Application Number:
  US15/068,801
• Publication Number:
  US 20160195785A1
• Time in Patent Office: 617 Days
• Field of Search: None
• 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 gate electrode;

a first insulating layer over the gate electrode;

a semiconductor layer over and in contact with a top surface of the first insulating layer, wherein the semiconductor layer overlaps with the gate electrode;

a source electrode over the semiconductor layer, the source electrode electrically connected to the semiconductor layer;

a drain electrode over the semiconductor layer, the drain electrode electrically connected to the semiconductor layer;

a pixel electrode over and in contact with a top surface of the first insulating layer, the pixel electrode electrically connected to one of the source electrode and the drain electrode;

a second insulating layer over the first insulating layer, the semiconductor layer, the source electrode and the drain electrode;

a common electrode over the second insulating layer, the common electrode having a first slit and a second slit;

a liquid crystal layer over the common electrode; and

a common wiring under the first insulating layer, the common wiring electrically connected to the common electrode,

wherein the semiconductor layer comprises an amorphous silicon,

wherein the first slit comprises a region overlapping with the pixel electrode, and the second slit comprises a region not overlapping with the pixel electrode, and

wherein a first portion of the common electrode overlaps with the pixel electrode and a second portion of the common electrode does not overlaps with the pixel electrode.

2. The liquid crystal display device according to claim 1, wherein the pixel electrode is electrically connected to the one of the source electrode and the drain electrode through a contact hole of an insulating layer.

3. The liquid crystal display device according to claim 1, wherein the common electrode is in contact with the common wiring.

4. A mobile phone comprising the liquid crystal display device according to claim 1.

5. A liquid crystal display device comprising:

a gate electrode;

a first insulating layer over the gate electrode;

a semiconductor layer over and in contact with a top surface of the first insulating layer,

wherein the semiconductor layer overlaps with the gate electrode;

a source electrode over the semiconductor layer, the source electrode electrically connected to the semiconductor layer;

a drain electrode over the semiconductor layer, the drain electrode electrically connected to the semiconductor layer;

a pixel electrode over and in contact with a top surface of the first insulating layer, the pixel electrode electrically connected to one of the source electrode and the drain electrode;

a second insulating layer over the first insulating layer, the semiconductor layer, the source electrode and the drain electrode;

a common electrode over the second insulating layer, the common electrode having a first slit and a second slit; and

a liquid crystal layer over the common electrode,

wherein the first slit comprises a region overlapping with the pixel electrode, and the second slit comprises a region not overlapping with the pixel electrode, and

wherein a first portion of the common electrode overlaps with the pixel electrode and a second portion of the common electrode does not overlaps with the pixel electrode.

6. The liquid crystal display device according to claim 5, wherein the semiconductor layer comprises an amorphous silicon.

7. The liquid crystal display device according to claim 5, wherein the pixel electrode is electrically connected to the one of the source electrode and the drain electrode through a contact hole of an insulating layer.

8. The liquid crystal display device according to claim 5, further comprising:

a common wiring under the first insulating layer, the common wiring electrically connected to the common electrode.

9. The liquid crystal display device according to claim 8, wherein the common electrode is in contact with the common wiring.

10. A mobile phone comprising the liquid crystal display device according to claim 5.

11. A liquid crystal display device comprising:

a first conductive layer;

a first insulating layer over the first conductive layer;

a semiconductor layer over and in contact with a top surface of the first insulating layer,

wherein the semiconductor layer overlaps with the first conductive layer;

a second conductive layer over the semiconductor layer, the second conductive layer electrically connected to the semiconductor layer;

a third conductive layer over the semiconductor layer, the third conductive layer electrically connected to the semiconductor layer;

a first transparent conductive layer over and in contact with a top surface of the first insulating layer, the first transparent conductive layer electrically connected to one of the second conductive layer and the third conductive layer;

a second insulating layer over the first insulating layer, the semiconductor layer, the second conductive layer and the third conductive layer;

a second transparent conductive layer over the second insulating layer, the second transparent conductive layer having a first slit and a second slit; and

a liquid crystal layer over the second transparent conductive layer,

wherein the first slit comprises a region overlapping with the first transparent conductive layer, and the second slit comprises a region not overlapping with the first transparent conductive layer, and

wherein a first portion of the second transparent conductive layer overlaps with the first transparent conductive layer and a second portion of the second transparent conductive layer does not overlaps with the first transparent conductive layer.

12. The liquid crystal display device according to claim 11, wherein the semiconductor layer comprises an amorphous silicon.

13. The liquid crystal display device according to claim 11, wherein the first transparent conductive layer is electrically connected to the one of the second conductive layer and the third conductive layer through a contact hole of an insulating layer.

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

a fourth conductive layer under the first insulating layer, the fourth conductive layer electrically connected to the second transparent conductive layer.

15. The liquid crystal display device according to claim 14, wherein the second transparent conductive layer is in contact with the fourth conductive layer.

16. A mobile phone comprising the liquid crystal display device according to claim 11.

17. A liquid crystal display device comprising:

a gate electrode;

a first insulating layer over the gate electrode;

a semiconductor layer over and in contact with a top surface of the first insulating layer, wherein the semiconductor layer overlaps with the gate electrode;

a source electrode over the semiconductor layer, the source electrode electrically connected to the semiconductor layer;

a drain electrode over the semiconductor layer, the drain electrode electrically connected to the semiconductor layer;

a pixel electrode over and in contact with a top surface of the first insulating layer, the pixel electrode electrically connected to one of the source electrode and the drain electrode;

a second insulating layer over the pixel electrode, the first insulating layer, the semiconductor layer, the source electrode and the drain electrode;

a common electrode over the second insulating layer, the common electrode having a first slit and a second slit;

a liquid crystal layer over the common electrode; and

a common wiring under the first insulating layer, the common wiring electrically connected to the common electrode,

wherein the first slit comprises a region overlapping with the pixel electrode, and the second slit comprises a region not overlapping with the pixel electrode,

wherein a first portion of the common electrode overlaps with the pixel electrode and a second portion of the common electrode does not overlaps with the pixel electrode, and

wherein the gate electrode and the common wiring comprises a same material.

18. The liquid crystal display device according to claim 17, wherein the semiconductor layer comprises an amorphous silicon.

19. The liquid crystal display device according to claim 17, wherein the pixel electrode is electrically connected to the one of the source electrode and the drain electrode through a contact hole of an insulating layer.

20. The liquid crystal display device according to claim 17, wherein the common electrode is in contact with the common wiring.

21. The liquid crystal display device according to claim 17, wherein the common electrode is in a first pixel and a second common electrode is in a second pixel adjacent to the first pixel, the common electrode being spaced from the second common electrode.

22. A liquid crystal display device comprising:

a gate electrode;

a first insulating layer over the gate electrode;

a semiconductor layer over and in contact with a top surface of the first insulating layer, wherein the semiconductor layer overlaps with the gate electrode;

a source electrode over the semiconductor layer, the source electrode electrically connected to the semiconductor layer;

a drain electrode over the semiconductor layer, the drain electrode electrically connected to the semiconductor layer;

a pixel electrode over and in contact with a top surface of the first insulating layer, the pixel electrode electrically connected to one of the source electrode and the drain electrode;

a second insulating layer over the pixel electrode, the first insulating layer, the semiconductor layer, the source electrode and the drain electrode;

a common electrode over the second insulating layer, the common electrode having a first slit and a second slit;

a liquid crystal layer over the common electrode; and

a common wiring under the first insulating layer, the common wiring electrically connected to the common electrode,

wherein the semiconductor layer comprises an amorphous silicon,

wherein the first slit comprises a region overlapping with the pixel electrode, and the second slit comprises a region not overlapping with the pixel electrode,

wherein a first portion of the common electrode overlaps with the pixel electrode and a second portion of the common electrode does not overlaps with the pixel electrode,

wherein the pixel electrode comprises a transparent conductive layer,

wherein the common electrode comprises a transparent conductive layer,

wherein the gate electrode and the common wiring comprises a same material,

wherein the common electrode is in a first pixel and a second common electrode is in a second pixel adjacent to the first pixel, the common electrode being spaced from the second common electrode.

23. The liquid crystal display device according to claim 22, wherein the pixel electrode is electrically connected to the one of the source electrode and the drain electrode through a contact hole of an insulating layer.

24. The liquid crystal display device according to claim 22, wherein the common electrode is in contact with the common wiring.