Electro-optical device

• US 6,621,102 B2
• Filed: 07/27/2001
• Issued: 09/16/2003
• Est. Priority Date: 11/14/1995
• Status: Expired due to Term

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Hirakata, Yoshiharu, Yamazaki, Shunpei
• Primary Examiner(s): Flynn, Nathan J.
• Assistant Examiner(s): Sefer, Ahmed N.
• Application Number:
  US09/916,573
• Publication Number:
  US 20010045556A1
• Time in Patent Office: 781 Days
• Field of Search: 257/72, 257/59, 257/443, 257/448, 349/42, 349/43, 349/141
• US Class Current: 257/72
• 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 1/1368 in which the switching element is a three-electrode device G02F1/136277 takes precedence

Abstract

In a pixel structure of an active matrix liquid crystal display device, a common electrode branching out from a common line which is maintained at a specified voltage and a pixel electrode connected to a drain of a thin-film transistor arranged on a common plane are wound around each other in spiral form. Electric fields generally oriented parallel to a substrate are produced between the common electrode and pixel electrode arranged in each pixel on the substrate. These electric fields drive a liquid crystal material to provide a visual display. The pixel electrode is surrounded, or fenced off, by the common electrode in each pixel so that the former is kept unaffected from interference from a nearby gate line and/or source line.

Claims

1. A display device comprising:

a substrate;

a thin film transistor provided over said substrate;

a pixel electrode provided over said substrate and connected with one of source and drain regions of said thin film transistor; and

a common electrode provided over said substrate and adjacent to said pixel electrode,

wherein said thin film transistor and said pixel electrode and said common electrode are provided in a pixel,

wherein said pixel electrode and said common electrode are opposed to each other to produce an electric field between said pixel electrode and said common electrode, said electric field containing a component parallel to said substrate,

wherein said pixel electrode and said common electrode bend so that said pixel electrode is opposed to said common electrode with a substantially constant distance between said pixel electrode and said common electrode, and

wherein said pixel electrode and said common electrode have a spiral form.

2. A device according to claim 1 wherein said common electrode and said pixel electrode are vertically separated by an intermediate insulating layer.

3. A device according to claim 1 further comprising a liquid crystal wherein said electric field is applied to said liquid crystal.

4. A display device comprising:

a substrate;

a thin film transistor provided over said substrate;

a pixel electrode provided over said substrate and connected with one of source and drain regions of said thin film transistor; and

a common electrode provided over said substrate and adjacent to said pixel electrode,

wherein said thin film transistor and said pixel electrode and said common electrode are provided in a pixel,

wherein said pixel electrode and said common electrode are opposed to each other to constitute a pixel capacitor between said pixel electrode and said common electrode,

wherein said pixel electrode and said common electrode bend so that said pixel electrode is opposed to said common electrode with a substantially constant distance between said pixel electrode and said common electrode, and

wherein said pixel electrode and said common electrode have a spiral form.

5. A device according to claim 4 wherein said common electrode and said pixel electrode are vertically separated by an intermediate insulating layer.

6. A device according to claim 4 further comprising a liquid crystal provided between said pixel electrode and said common electrode.