System for driving a nematic liquid crystal

• US 6,424,329 B1
• Filed: 09/12/2000
• Issued: 07/23/2002
• Est. Priority Date: 08/06/1996
• Status: Expired due to Term

• Current Assignee: HDT, Inc., Masaya Okita
• Original Assignee: FAD, Inc., Masaya Okita
• Inventors: Okita, Masaya
• Primary Examiner(s): Chow, Dennis-Doon
• Assistant Examiner(s): ENGLISH, ALECIA DIANE
• Application Number:
  US09/660,279
• Time in Patent Office: 679 Days
• Field of Search: 345/94, 345/95, 345/96, 345/92, 345/108, 345/87, 345/97, 345/101
• US Class Current: 345/95
• CPC Class Codes: G09G 2310/0235 Field-sequential colour display
• CPC Class Codes: G09G 3/18 using liquid crystals
• CPC Class Codes: G09G 3/3622 using a passive matrix G09G3/3674 - G09G3/3696 take precedence

Abstract

A system for driving a nematic liquid crystal is used to display high definition color images at a high speed in a liquid crystal display device in which the nematic liquid crystal is confined between a common electrode and a segment electrode that are placed between two polarizing plates. The common electrode is supplied with a sequence of selection pulses, and the segment electrode is supplied with a voltage corresponding to image data to be displayed in response to the selection pulses. the segment electrode is further supplied with a voltage different from the voltage corresponding to the image data in intervals where the selection pulses are not applied to the common electrode.

Claims

1. A system for driving a nematic liquid crystal in a liquid crystal display device in which the nematic liquid crystal is confined between a common electrode and a segment electrode that are placed between two polarizing plates, comprising:

means for applying to said liquid crystal a voltage of a value corresponding to image data to be displayed;

means for applying a constant voltage to said liquid crystal;

means for switching application of said constant voltage and application of said voltage corresponding to image data to be displayed in a predetermined cycle;

ratio of length of time for which said constant voltage is applied relative to length of time for which said voltage corresponding to image data to be displayed being constant; and

one of said constant voltage and said voltage corresponding to image data to be displayed being applied to said liquid crystal after said voltages are switched,

said nematic liquid crystal having electro-optical characteristics that exhibit a transmittance determined by one of the voltages without maintaining any prior hysteresis when said voltages are switched from one to the other.

2. The system for driving a nematic liquid crystal according to claim 1 wherein said liquid crystal has said characteristics at least in a substantial operation range thereof.

3. A system for driving a nematic liquid crystal in a liquid crystal display device in which the nematic liquid crystal is confined between a common electrode and a segment electrode that are placed between two polarizing plates, comprising:

means for applying to said liquid crystal a voltage of a value corresponding to image data to be displayed;

means for applying a constant voltage to said liquid crystal;

means for switching application of said constant voltage and application of said voltage corresponding to image data to be displayed in a predetermined cycle;

ratio of length of time for which said constant voltage is applied relative to length of time for which said voltage corresponding to image data to be displayed being constant; and

one of said constant voltage and said voltage corresponding to image data to be displayed being applied to said liquid crystal after said voltages are switched,

said liquid crystal having electro-optical characteristics that exhibit a definite transmittance determined by a voltage of a value after being changed when the voltage to said liquid crystal is changed to said value corresponding to image data to be displayed.

4. The system for driving a nematic liquid crystal according to claim 3 wherein said liquid crystal has said characteristics at least in a substantial operation range thereof.