Liquid crystal display device

• US 8,675,158 B2
• Filed: 07/23/2013
• Issued: 03/18/2014
• 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:
  US13/948,336
• Publication Number:
  US 20130300969A1
• Time in Patent Office: 238 Days
• Field of Search: None
• US Class Current: 349/114
• 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 first wiring;

a transistor comprising;

a gate electrode of same structure and composition as the first wiring;

a semiconductor layer comprising polycrystalline silicon overlapping the gate electrode; and

a gate insulating layer interposed between the gate electrode and the semiconductor layer;

a first insulating layer over the transistor and the first wiring;

a second wiring on the first insulating layer, in direct contact with the semiconductor layer through a first opening in the first insulating layer;

a third wiring on the first insulating layer, in direct contact with the first wiring through a second opening in the first insulating layer, the third wiring having a same composition and structure as the second wiring;

a second insulating layer over the first insulating layer, the second wiring, and the third wiring;

a common electrode on the second insulating layer, in electrical contact with the first wiring through the third wiring;

an island-shaped conductive layer having a same composition and structure as a portion of the common electrode;

a third insulating layer over the second insulating layer, the common electrode, and the island-shaped conductive layer;

a pixel electrode on the third insulating layer, overlapping the common electrode and in electrical contact with the semiconductor layer through the second wiring and the island-shaped conductive layer.

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

7. The liquid crystal display device according to claim 1, wherein the second wiring is island-shaped.

10. The liquid crystal display device according to claim 1, wherein the pixel electrode comprises slits.

13. The liquid crystal display device according to claim 1, wherein the common electrode comprises a reflecting common electrode and a transmitting common electrode.

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

2. A liquid crystal display device comprising:

a first wiring;

a transistor comprising;

a gate electrode of same structure and composition as the first wiring;

a semiconductor layer comprising polycrystalline silicon overlapping the gate electrode; and

a gate insulating layer interposed between the gate electrode and the semiconductor layer;

a first insulating layer over the transistor and the first wiring;

a second wiring on the first insulating layer, in direct contact with the semiconductor layer through a first opening in the first insulating layer;

a third wiring on the first insulating layer, in direct contact with the first wiring through a second opening in the first insulating layer, the third wiring having a same composition and structure as the second wiring;

a second insulating layer over the first insulating layer, the second wiring, and the third wiring;

a common electrode on the second insulating layer, in electrical contact with the first wiring through the third wiring;

an island-shaped conductive layer having a same composition and structure as a portion of the common electrode;

a third insulating layer over the second insulating layer, the common electrode, and the island-shaped conductive layer;

a pixel electrode on the third insulating layer, overlapping the common electrode and in electrical contact with the semiconductor layer through the second wiring and the island-shaped conductive layer,

wherein the common electrode is in electrical contact with the third wiring through an opening in the second insulating layer, and

wherein the pixel electrode overlaps a portion of the common electrode formed in the opening in the second insulating layer.

5. The liquid crystal display device according to claim 2, wherein the common electrode is in direct contact with the third wiring.

8. The liquid crystal display device according to claim 2, wherein the second wiring is island-shaped.

11. The liquid crystal display device according to claim 2, wherein the pixel electrode comprises slits.

14. The liquid crystal display device according to claim 2, wherein the common electrode comprises a reflecting common electrode and a transmitting common electrode.

17. An electronic appliance comprising the liquid crystal display device according to claim 2.

3. A liquid crystal display device comprising:

a first wiring;

a transistor comprising;

a gate electrode of same structure and composition as the first wiring;

a semiconductor layer comprising polycrystalline silicon overlapping the gate electrode; and

a gate insulating layer interposed between the gate electrode and the semiconductor layer;

a first insulating layer over the transistor and the first wiring;

a second wiring on the first insulating layer, in direct contact with the semiconductor layer through a first opening in the first insulating layer;

a third wiring on the first insulating layer, in direct contact with the first wiring through a second opening in the first insulating layer, the third wiring having a same composition and structure as the second wiring;

a second insulating layer over the first insulating layer, the second wiring, and the third wiring;

a common electrode on the second insulating layer, in electrical contact with the first wiring through the third wiring;

an island-shaped conductive layer having a same composition and structure as a portion of the common electrode;

a third insulating layer over the second insulating layer, the common electrode, and the island-shaped conductive layer;

a pixel electrode on the third insulating layer, overlapping the common electrode and in electrical contact with the semiconductor layer through the second wiring and the island-shaped conductive layer,

wherein the pixel electrode is in direct contact with the island-shaped conductive layer through an opening in the third insulating layer,

wherein the island-shaped conductive layer is in direct contact with the second wiring through an opening in the second insulating layer, and

wherein the island-shaped conductive layer overlaps with the pixel electrode, the opening in the third insulating layer, the opening in the second insulating layer, the second wiring, and the first opening in the first insulating layer.

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

9. The liquid crystal display device according to claim 3, wherein the second wiring is island-shaped.

12. The liquid crystal display device according to claim 3, wherein the pixel electrode comprises slits.

15. The liquid crystal display device according to claim 3, wherein the common electrode comprises a reflecting common electrode and a transmitting common electrode.

18. An electronic appliance comprising the liquid crystal display device according to claim 3.