Display apparatus having both refresh-scan and partial-scan

• US 5,321,419 A
• Filed: 06/17/1992
• Issued: 06/14/1994
• Est. Priority Date: 06/18/1991
• Status: Expired due to Fees

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Tsuboyama, Akira, Hotta, Yoshio, Katakura, Kazunori, Mihara, Tadashi, Iwayama, Mitsuo
• Primary Examiner(s): BRIER, JEFFERY A
• Application Number:
  US07/899,720
• Time in Patent Office: 727 Days
• Field of Search: 340/784, 340/811, 345/94, 345/95, 345/97
• US Class Current: 345/97
• CPC Class Codes: G09G 2310/0205 Simultaneous scanning of several lines in flat panels
• CPC Class Codes: G09G 2310/04 Partial updating of the display screen
• CPC Class Codes: G09G 2310/06 Details of flat display driving waveforms
• CPC Class Codes: G09G 2310/061 for resetting or blanking
• CPC Class Codes: G09G 2320/0247 Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes
• CPC Class Codes: G09G 3/3629 using liquid crystals having memory effects, e.g. ferroelectric liquid crystals

Abstract

A display apparatus includes a matrix of electrodes formed of scanning electrodes and information electrodes. A scanning device uses a plurality of scanning methods for selecting scanning electrodes and performs the scanning methods according to respective priorities, and a driving device changes driving conditions according to the scanning methods or the priorities thereof.

Claims

1. A display apparatus comprising:

a matrix of electrodes including scanning electrodes and information electrodes;

driving means for scanning said matrix so as to apply a selected driving waveform comprising driving signals to selected ones of said scanning electrodes, and to apply data signals in synchronism with the driving signals to said information electrodes in parallel; and

control means for controlling said driving means so as to perform, in response to a graphic event to be displayed, either an entire frame scanning in which said matrix is fully rewritten or a partial rewritting scanning in which said matri is partially rewritten, wherein a driving waveform selected for said entire frame scanning is different from a driving waveform selected for said partial rewriting scanning.

2. A display apparatus according to claim 1, further comprising a liquid crystal provided between said scanning electrodes and said information electrodes.

3. A display apparatus according to claim 2, wherein said liquid crystal is a ferroelectric liquid crystal.

4. A display apparatus according to claim 1, wherein during performance of said entire frame scanning, said driving means uses a driving waveform including an erasing pulse and a writing pulse, and during performance of said partial rewriting scanning, said driving means uses a driving waveform including no erasing pulse.

5. A display apparatus according to claim 1, wherein during performance of said entire frame scanning, said driving means performs double driving in which a driving waveform including an erasing pulse and a writing pulse is used to scan two scanning electrodes at a time so that said erasing pulse is applied to one of the two scanning electrodes and said writing pulse is applied to the other scanning electrode, and wherein during performance of said partial rewriting scanning, said driving means performs single driving in which a driving waveform is used to scan one scanning electrode at a time.

6. A display apparatus according to claim 1, wherein during performance of said entire frame scanning, said driving means uses a driving waveform including an erasing pulse and a writing pulse, and during performance of said partial rewriting scanning, said driving means alternately uses a driving waveform including a black erasing pulse and a writing pulse and a driving waveform including a white erasing pulse and a writing pulse.

7. A display apparatus according to claim 1, wherein said driving means uses driving voltages or driving voltage ratios during performance of said entire frame scanning different from driving voltages or driving voltage ratios used during performance of said partial rewriting scanning.

8. A display apparatus according to claim 1, wherein said driving means uses driving signals and data signals during performance of said entire frame scanning having different durations from those of driving signals and data signals during performance of said partial rewriting scanning.

9. A display apparatus according to claim 1, wherein during performance of said entire frame scanning, said driving means uses a driving waveform including a DC component, and during performance of said partial rewriting scanning, said driving means uses a driving waveform including no DC component.