Electro-optical device

• US 5,977,562 A
• Filed: 11/14/1996
• Issued: 11/02/1999
• 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): Dutton, Brian
• Application Number:
  US08/748,887
• Time in Patent Office: 1,083 Days
• Field of Search: 438/30, 257/59, 257/72, 257/443, 257/448, 349/42, 349/43, 349/54, 349/59, 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. An active matrix electro-optical device comprising:

gate lines and source lines arranged on a substrate to form together a grid pattern;

thin-film transistors located in individual pixels, each of said thin-film transistors having a gate connected to one of said gate lines and a source connected to one of said source lines;

first electrodes individually connected to drains of said thin-film transistors;

common lines maintained at a specified voltage; and

second electrodes branching out from said common lines;

wherein said first and second electrodes are arranged into a spiral form with an arm of each of said first electrodes being wound around an arm of a corresponding one of said second electrodes.

2. The device of claim 1 wherein said second electrodes have such segments that are located at least in gaps between said first electrodes and said source lines or between said first electrodes and said gate lines on said substrate.

3. The device of claim 1 wherein said first electrodes are individually surrounded by said second electrodes to prevent said first electrodes from running side by side with either said gate lines or said source lines on said substrate.

4. The device of claim 1 wherein said first and second electrodes are formed in a common plane.

5. The device of claim 1 wherein said first and second electrodes form auxiliary capacitance connected in parallel with each pixel.

6. An active matrix electro-optical device comprising:

first electrodes individually connected to drains of thin-film transistors formed in respective pixels on a substrate;

second electrodes for producing electric fields between said first and second electrodes, said electric fields containing components parallel to said substrate;

wherein said first and second electrodes are individually shaped into a spiral form with an arm of each of said first electrodes being wound around an arm of a corresponding one of said second electrodes.

7. The device of claim 6 wherein said first and second electrodes form auxiliary capacitance connected in parallel with each pixel.

8. The device of claim 6 wherein said first electrodes are individually surrounded by said second electrodes to prevent said first electrodes from running side by side with either gate lines which are connected to gates of said thin-film transistors or source lines which are connected to sources of said thin-film transistors.

9. The device of claim 7 wherein values of said auxiliary capacitance are determined by the numbers of turns of said first and second electrodes.

10. The device of claim 8 wherein said first and second electrodes are formed in a common plane.

11. An active matrix electro-optical device comprising:

gate lines and source lines arranged on a substrate to form together a grid pattern;

thin-film transistors located in individual pixels, each of said thin-film transistors having a gate connected to one of said gate lines and a source connected to one of said source lines;

first electrodes individually connected to drains of said thin-film transistors;

common lines maintained at a specified voltage; and

second electrodes branching out from said common lines;

wherein said first and second electrodes are arranged into a spiral form with an arm of each of said first electrodes being wound around an arm of a corresponding one of said second electrodes, and

wherein each of said second electrodes has a part located between a corresponding one of said first electrodes and a corresponding one of said source lines.

12. An active matrix electro-optical device comprising:

gate lines and source lines arranged on a substrate to form together a grid pattern;

thin-film transistors located in individual pixels, each of said thin-film transistors having a gate connected to one of said gate lines and a source connected to one of said source lines;

first electrodes individually connected to drains of said thin-film transistors;

common lines maintained at a specified voltage; and

second electrodes branching out from said common lines;

wherein said first and second electrodes are arranged into a spiral form with an arm of each of said first electrodes being wound around an arm of a corresponding one of said second electrodes, and

wherein each of said second electrodes has a part located between a corresponding one of said first electrodes and a corresponding one of said source lines.