Liquid crystal display device

• US 10,539,847 B2
• Filed: 06/10/2019
• Issued: 01/21/2020
• 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:
  US16/435,609
• Publication Number:
  US 20190302501A1
• Time in Patent Office: 225 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 substrate;

a semiconductor layer over the substrate;

a gate insulating layer over the semiconductor layer;

a gate electrode over the gate insulating layer;

a source electrode and a drain electrode over and electrically connected to the semiconductor layer;

a first insulating layer over the gate electrode;

a first conductive layer over the first insulating layer;

a second conductive layer over the first insulating layer;

a second insulating layer over the first conductive layer;

a common conductive layer over the second insulating layer;

a pixel electrode over the second insulating layer, the pixel electrode being electrically connected to one of the source electrode and the drain electrode; and

a liquid crystal material over the common conductive layer and the pixel electrode,

wherein the second conductive layer comprises aluminum,

wherein the common conductive layer is indium tin oxide,

wherein a resistance of the second conductive layer is lower than a resistance of the common conductive layer,

wherein a part of the first conductive layer overlaps with the second conductive layer, the common conductive layer, and the pixel electrode, and

wherein the first conductive layer does not overlap with any of the semiconductor layer, the gate electrode, the source electrode, and the drain electrode.

2. The liquid crystal display device according to claim 1, wherein each of the common conductive layer and the pixel electrode comprises a transparent conductive layer.

3. A liquid crystal display device, comprising:

a substrate;

a semiconductor layer over the substrate, the semiconductor layer comprising polycrystalline silicon;

a gate insulating layer over the semiconductor layer;

a gate electrode over the gate insulating layer;

a source electrode and a drain electrode over and electrically connected to the semiconductor layer;

a first insulating layer over the gate electrode;

a first conductive layer over the first insulating layer;

a second conductive layer over the first insulating layer;

a second insulating layer over the first conductive layer;

a common conductive layer over the second insulating layer;

a pixel electrode over the second insulating layer, the pixel electrode being electrically connected to one of the source electrode and the drain electrode; and

a liquid crystal material over the common conductive layer and the pixel electrode,

wherein the second conductive layer comprises aluminum,

wherein the common conductive layer is indium tin oxide,

wherein a resistance of the second conductive layer is lower than a resistance of the common conductive layer,

wherein a part of the first conductive layer overlaps with the second conductive layer, the common conductive layer, and the pixel electrode, and

wherein the first conductive layer does not overlap with any of the semiconductor layer, the gate electrode, the source electrode, and the drain electrode.

4. The liquid crystal display device according to claim 3, wherein each of the common conductive layer and the pixel electrode comprises a transparent conductive layer.