Liquid crystal display device

• US 9,835,912 B2
• Filed: 08/10/2016
• Issued: 12/05/2017
• 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:
  US15/232,996
• Publication Number:
  US 20160349579A1
• Time in Patent Office: 482 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 1/134309 characterised by their geometrical arrangement
• 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 1/134381 Hybrid switching mode, i.e. for applying an electric field with components parallel and orthogonal to the substrates
• 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 2203/01 transmissive
• CPC Class Codes: H01L 27/12 the substrate being other than a semiconductor body, e.g. an insulating body

Abstract

It is an object of the present invention to provide a liquid crystal display device which has a wide viewing angle and less color-shift depending on an angle at which a display screen is seen and can display an image favorably recognized both outdoors in sunlight and dark indoors (or outdoors at night). The liquid crystal display device includes a first portion where display is performed by transmission of light and a second portion where display is performed by reflection of light. Further, a liquid crystal layer includes a liquid crystal molecule which rotates parallel to an electrode plane when a potential difference is generated between two electrodes of a liquid crystal element provided below the liquid crystal layer.

Claims

1. A liquid crystal display device comprising:

a substrate;

a layer having a convex top surface;

a transistor on the substrate;

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

a common electrode, the common electrode and the pixel electrode overlapping; and

a liquid crystal layer overlapping the pixel electrode and the common electrode,

wherein the common electrode comprises a first conductive layer and a second conductive layer on and in direct contact with the first conductive layer,

wherein the first conductive layer is light-transmitting,

wherein the second conductive layer only partially covers the first conductive layer, and

wherein a region where the second conductive layer is on and in direct contact with the first conductive layer overlaps with the layer having a convex top surface so that, in the region, the common electrode has a convex top surface.

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

wherein the transistor is between the common electrode and the liquid crystal layer.

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

wherein the pixel electrode overlaps both of the first conductive layer and the second conductive layer.

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

wherein the second conducive layer is reflective.

5. The liquid crystal display device according to claim 1, further comprising an FPC mechanically coupled to the substrate and electrically connected to the pixel electrode.

6. An electronic appliance comprising the liquid crystal display device according to claim 1.

7. A liquid crystal display device comprising:

a substrate;

a layer having a convex top surface;

a transistor on the substrate;

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

a common electrode, the common electrode and the pixel electrode overlapping; and

a liquid crystal layer overlapping the pixel electrode and the common electrode,

wherein the common electrode comprises a first conductive layer and a second conductive layer on and in direct contact with the first conductive layer,

wherein the first conductive layer is light-transmitting,

wherein the second conductive layer only partially covers the first conductive layer,

wherein a region where the second conductive layer is on and in direct contact with the first conductive layer overlaps with the layer having a convex top surface so that, in the region, the common electrode has a convex top surface, and

wherein, when seen in a cross-sectional view, the pixel electrode is over the substrate, a first portion of the pixel electrode overlapping with the second conductive layer is higher than a second portion of the pixel electrode not overlapping with the second conductive layer.

8. The liquid crystal display device according to claim 7,

wherein the transistor is between the common electrode and the liquid crystal layer.

9. The liquid crystal display device according to claim 7,

wherein the pixel electrode overlaps both of the first conductive layer and the second conductive layer.

10. The liquid crystal display device according to claim 7,

wherein the second conducive layer is reflective.

11. The liquid crystal display device according to claim 7, further comprising an FPC mechanically coupled to the substrate and electrically connected to the pixel electrode.

12. An electronic appliance comprising the liquid crystal display device according to claim 7.

13. A liquid crystal display device comprising:

a substrate;

a transistor comprising;

a gate electrode;

a semiconductor layer; and

a wiring on and in electrical contact with the semiconductor layer;

a first insulating layer over the transistor;

a common electrode over the transistor;

a second insulating layer over the common electrode;

a pixel electrode electrically connected to the wiring via a first opening in the first insulating layer and a second opening in the second insulating layer, the pixel electrode and the common electrode overlapping; and

a liquid crystal layer overlapping the pixel electrode and the common electrode,

wherein the common electrode comprises a first conductive layer and a second conductive layer on and in direct contact with the first conductive layer,

wherein the first conductive layer is light-transmitting,

wherein the second conductive layer only partially covers the first conductive layer, and

wherein the second conductive layer is over the first insulating layer and has unevenness.

14. The liquid crystal display device according to claim 13,

wherein the first conductive layer is below the first insulating layer.

15. The liquid crystal display device according to claim 13,

wherein the second conductive layer is on an in direct contact with the first conductive layer in an opening of the first insulating layer.

16. The liquid crystal display device according to claim 13,

wherein the pixel electrode overlaps both of the first conductive layer and the second conductive layer.

17. The liquid crystal display device according to claim 13,

wherein the second conducive layer is reflective.

18. The liquid crystal display device according to claim 13, further comprising an FPC mechanically coupled to the substrate and electrically connected to the pixel electrode.

19. An electronic appliance comprising the liquid crystal display device according to claim 13.