Liquid crystal display device with control capacitors for gray-scale

• US 5,245,450 A
• Filed: 07/19/1991
• Issued: 09/14/1993
• Est. Priority Date: 07/23/1990
• Status: Expired due to Fees

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Hosiden Corporation
• Inventors: Inada, Toshiya, Ukai, Yasuhiro, Sunata, Tomihisa
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): Duong, Tai V.
• Application Number:
  US07/733,177
• Time in Patent Office: 788 Days
• Field of Search: 359/54, 359/55, 359/57, 359/59, 359/79, 359/87, 340/784, 340/793
• US Class Current: 349/144
• CPC Class Codes: G02F 1/134345 Subdivided pixels, e.g. for grey scale or redundancy
• CPC Class Codes: G02F 1/134354 the sub-pixels being capacitively coupled
• CPC Class Codes: G02F 1/136213 Storage capacitors associated with the pixel electrode
• CPC Class Codes: G02F 2203/30 Gray scale

Abstract

Each pixel electrode of a liquid crystal display device is divided into a plurality of subpixel electrodes, which are separated by a gap from each other, and a control capacitor electrode is provided opposite at least one of the subpixel electrodes through a first insulating film. The control capacitor electrode has a region extending the entire length of the gap so that a drive voltage can be applied to liquid crystal in the gap. The control capacitor electrode forms a control capacitor connected in series with a liquid crystal capacitor formed by the above-mentioned least one subpixel electrode between it and a common electrode corresponding thereto. An additional capacitor electrode, which is opposite the at least one subpixel electrode through a second insulating film, is formed, by which is formed an additional capacitor equivalently in parallel to the liquid crystal capacitor.

Claims

1. A liquid crystal display device comprising at least one subpixel electrode occupying a part of a region defined by a pixel, said subpixel electrode being disposed on a first insulating film on a first base plate in opposing relation to a common electrode on a second base plate across liquid crystal, a control capacitor electrode partly opposite said at least one subpixel electrode being provided through said first insulating film to form a control capacitor connected in series with a liquid crystal capacitor formed between said at least one subpixel electrode and said common electrode, means for applying a drive voltage across said control capacitor electrode and said common electrode, and an additional capacitor electrode formed in opposing relation to said at least one subpixel electrode through a second insulating film to form an additional capacitor equivalently in parallel to said liquid crystal capacitor.

2. The liquid crystal display device of claim 1 wherein another subpixel electrode separated by a gap from said at least one subpixel electrode is provided in said region associated with said at least one subpixel electrode, said another subpixel electrode being electrically connected to said control capacitor electrode.

3. The liquid crystal display device of claim 2 wherein said control capacitor electrode substantially encompasses said at least one subpixel electrode and overlaps a marginal portion of said at least one subpixel electrode.

4. The liquid crystal display device of claim 2, wherein said at least one subpixel electrode substantially encompasses said control capacitor electrode and overlaps a marginal portion of said control capacitor.

5. The liquid crystal display device of claim 1 wherein said second insulating film is deposited almost all over said region of the pixel from above said at least one subpixel electrode, and said additional capacitor electrode is formed on said insulating film.

6. The liquid crystal display device of claim 2, wherein said another subpixel electrode is connected to said control capacitor electrode through a contact hole made in said first insulating film.

7. The liquid crystal display device of claim 2, wherein said another subpixel electrode is formed in the same plane as said at least one subpixel electrode but is separated by a gap therefrom, and said control capacitor electrode has a region extending substantially the entire length of said gap.

8. The liquid crystal display device of claim 1, wherein said additional capacitor electrode has an extension connected to an additional capacitor electrode of an adjacent pixel in either one of row and column directions.