Liquid crystal display device

• US 7,456,924 B2
• Filed: 07/18/2007
• Issued: 11/25/2008
• Est. Priority Date: 09/07/1999
• Status: Expired due to Term

• Current Assignee: Japan Display Incorporated
• Original Assignee: Hitachi, Ltd.
• Inventors: Ono, Kikuo, Yamamoto, Tsunenori, Yoneya, Makoto, Nakayoshi, Yoshiaki, Hirakata, Junichi
• Primary Examiner(s): Duong; Thoi V
• Application Number:
  US11/779,416
• Publication Number:
  US 20080013028A1
• Time in Patent Office: 496 Days
• Field of Search: 349/143, 349139-141, 349/43
• US Class Current: 349/141
• CPC Class Codes: G02F 1/133345 Insulating layers G02F1/1335, G02F1/1337, G02F1/135, G02F1/136 take precedence
• CPC Class Codes: G02F 1/13394 spacers regularly patterned on the cell subtrate, e.g. walls, pillars G02F1/133377 takes precedence
• 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 1/13439 characterised by their electrical, optical, physical properties; materials therefor; method of making
• CPC Class Codes: G02F 1/13458 Terminal pads
• 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 1/1393 the birefringence of the liquid crystal being electrically controlled, e.g. ECB-, DAP-, HAN-, PI-LC cells G02F1/1396, G02F1/141 take precedence
• CPC Class Codes: G02F 2201/40 Arrangements for improving the aperture ratio

Abstract

A liquid crystal display device includes first and second substrates with a liquid crystal layer therebetween, a plurality of gate signal lines made of metal and a plurality of drain signal lines made of metal, wherein the gate signal line and the drain signal line have a first overlapping region, and a plurality of counter voltage signal lines, wherein the counter voltage signal line and the drain signal line have a second overlapping region. A plurality of pixel regions are defined by neighboring gate signal lines and drain signal lines, and a pixel electrode is formed on the first substrate in each pixel region. A thin film transistor having a semiconductor layer is formed on the gate signal line, and the semiconductor layer at least overlaps with the drain signal line at the first overlapping region and the second overlapping region.

Claims

1. A liquid crystal display device comprising:

first and second substrates with a liquid crystal layer therebetween;

a plurality of gate signal lines made of metal and a plurality of drain signal lines made of metal, the gate signal line and the drain signal line have a first overlapping region;

a plurality of counter voltage signal lines, the counter voltage signal line and the drain signal line have a second overlapping region;

a plurality of pixel regions defined by neighboring gate signal lines and drain signal lines; and

a pixel electrode and a counter electrode formed on the first substrate in each pixel region;

wherein the pixel electrode has a plurality of slits, the counter electrode has a substantially rectangular shape without a slit, and the pixel electrode is arranged in a position which overlaps with the counter electrode;

wherein a thin film transistor having a semiconductor layer is formed on the gate signal line; and

wherein the semiconductor layer at least overlaps with the drain signal line at the first overlapping region and the second overlapping region.

2. A liquid crystal display device according to claim 1, wherein a line width of the semiconductor layer is wider than a line width of the drain signal line at the first and the second overlapping regions.

3. A liquid crystal display device according to claim 1, wherein a line width of the drain signal line at the first and second overlapping regions is narrower than a line width of the drain signal in major portions of the drain signal line other than at the first and the second overlapping regions.

4. A liquid crystal display device according to claim 1, wherein a line width of the drain signal line at major portions of the drain signal line other than at the first and the second overlapping regions is wider than a line width of the semiconductor layer.

5. A liquid crystal display device according to claim 1, wherein the slits of the pixel electrode have a bent shape.

6. A liquid crystal display device according to claim 1, wherein the counter electrode is positioned between the pixel electrode and the first substrate.