Liquid crystal display device

• US 10,324,347 B1
• Filed: 08/20/2018
• Issued: 06/18/2019
• 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 M
• Application Number:
  US15/998,993
• Publication Number:
  US 20190162998A1
• Time in Patent Office: 302 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 the top surface of the first insulating layer, the pixel electrode electrically connected to one of the source electrode and the drain electrode, wherein the pixel electrode and the one of the source electrode and the drain electrode overlap with each other;

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; 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,

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 pixel electrode has no comb-shape and has no slit.

2. The liquid crystal display device according to claim 1, wherein the pixel electrode is in contact with a top surface of the one of the source electrode and the drain electrode.

3. The liquid crystal display device according to claim 1, wherein the pixel electrode comprises a transparent conductive layer.

4. 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 the top surface of the first insulating layer, the pixel electrode electrically connected to one of the source electrode and the drain electrode, wherein the pixel electrode and the one of the source electrode and the drain electrode overlap with each other;

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; and

a liquid crystal layer over the common electrode,

wherein the one of the source electrode and the drain electrode has a stacked-layer structure and comprises metal nitride,

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 common electrode comprises a transparent conductive layer, and

wherein the pixel electrode has no comb-shape and has no slit.

5. The liquid crystal display device according to claim 4, wherein the pixel electrode is in contact with a top surface of the one of the source electrode and the drain electrode.

6. The liquid crystal display device according to claim 4, wherein the pixel electrode comprises a transparent conductive layer.

7. 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 the top surface of the first insulating layer, the pixel electrode electrically connected to one of the source electrode and the drain electrode, wherein the pixel electrode and the one of the source electrode and the drain electrode overlap with each other;

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; and

a liquid crystal layer over the common electrode,

wherein the semiconductor layer comprises an amorphous silicon,

wherein the one of the source electrode and the drain electrode has a stacked-layer structure and comprises metal nitride,

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 a region overlapping with an outer edge of 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 common electrode comprises a transparent conductive layer, and

wherein the pixel electrode has no comb-shape and has no slit.

8. The liquid crystal display device according to claim 7, wherein the pixel electrode is in contact with a top surface of the one of the source electrode and the drain electrode.

9. The liquid crystal display device according to claim 7, wherein the pixel electrode comprises a transparent conductive layer.