Driving apparatus for an electrode matrix suitable for a liquid crystal panel

• US 5,317,332 A
• Filed: 09/09/1991
• Issued: 05/31/1994
• Est. Priority Date: 10/26/1987
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Inoue, Hiroshi, Mizutome, Atsushi, Kanno, Hideo
• Primary Examiner(s): BRIER, JEFFERY A
• Application Number:
  US07/757,009
• Time in Patent Office: 995 Days
• Field of Search: 340/765, 340/784, 340/805, 340/811, 340/812, 340/813, 359/56, 358/230, 358/236, 345/94, 345/101
• US Class Current: 345/101
• CPC Class Codes: G09G 2320/041 Temperature compensation
• CPC Class Codes: G09G 3/36 using liquid crystals
• CPC Class Codes: G09G 3/3629 using liquid crystals having memory effects, e.g. ferroelectric liquid crystals
• CPC Class Codes: G09G 3/3696 Generation of voltages supplied to electrode drivers

Abstract

A driving apparatus comprises a driving unit and a drive voltage generating unit. The driving unit includes a scanning electrode driver and a data electrode driver for driving an electrode matrix formed of scanning electrodes and data electrodes. The drive voltage generating unit includes a first means for generating a fixed voltage, a second means for generating a source voltage for providing drive voltages for driving the electrode matrix, and a third means for generating a first voltage equal to a subtraction of the fixed voltage from the source voltage and a second voltage equal to a subtraction of the source voltage from the fixed voltage. The first and second voltages are preferably controlled so as to vary depending on an external temperature.

Claims

1. A display apparatus, comprising:

a) a driving unit comprising a scanning electrode driver and a data electrode driver for driving an electrode matrix having scanning electrodes and data electrodes;

b) a drive voltage generating unit comprising first means for generating a fixed voltage, second means for generating a source voltage for providing drive voltages for driving the electrode matrix, and third means for generating a first voltage equal to a difference of the fixed voltage from the source voltage and a second voltage equal to a difference of the source voltage from the fixed voltage,

wherein the first voltage and the second voltage are of mutually opposite polarities with respect to the fixed voltage, and the fixed voltage comprises a voltage set to an intermediate value between a maximum output voltage and a minimum output voltage of said drive voltage generating unit;

c) a liquid crystal panel comprising a first substrate having said scanning electrodes thereon, a second substrate having said data electrodes thereon, and a liquid crystal disposed between said first and second substrates; and

d) control means for controlling said scanning electrode driver and said data electrode driver so as to sequentially apply a scanning selection signal to said scanning electrodes and apply data signals corresponding to given data to said data electrodes in synchronism with the scanning selection signal.

2. A display apparatus according to claim 1, wherein said liquid crystal comprises a chiral smectic liquid crystal.

3. A display apparatus according to claim 1, wherein said liquid crystal comprises a ferroelectric liquid crystal.

4. A display apparatus according to claim 3, wherein said ferroelectric liquid crystal shows bistability.