Display apparatus having fast rewrite operation

• US 6,057,824 A
• Filed: 10/07/1997
• Issued: 05/02/2000
• Est. Priority Date: 12/14/1993
• Status: Expired due to Fees

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Inaba, Yutaka, Katakura, Kazunori
• Primary Examiner(s): BRIER, JEFFERY A
• Application Number:
  US08/946,644
• Time in Patent Office: 938 Days
• Field of Search: 345/89, 345/98-100
• US Class Current: 345/100
• CPC Class Codes: G09G 2310/0227 related to multiple interlacing, i.e. involving more fields than just one odd field and one even field
• CPC Class Codes: G09G 2310/0232 Special driving of display border areas
• CPC Class Codes: G09G 2310/0297 Special arrangements with multiplexing or demultiplexing of display data in the drivers for data electrodes, in a pre-processing circuitry delivering display data to said drivers or in the matrix panel, e.g. multiplexing plural data signals to one D/A converter or demultiplexing the D/A converter output to multiple columns
• 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 2320/041 Temperature compensation
• CPC Class Codes: G09G 3/2018 by time modulation using two or more time intervals
• CPC Class Codes: G09G 3/3629 using liquid crystals having memory effects, e.g. ferroelectric liquid crystals

Abstract

A display apparatus includes a display panel having pixels formed at each intersection of scanning electrodes and data electrodes, and a driver for driving the display panel so that a period of each pixel placed in a prescribed display state is determined within a frame period depending on given gradation data. The driver divides one frame period into a first plurality of equivalent blocks of which a second plurality, smaller in number than the first plurality, of mutually non-neighboring blocks are allotted to a partial rewriting for selecting scanning electrodes corresponding to pixels to change display states. The remaining blocks other than the second plurality of blocks are allotted to an entire picture scanning for selecting all the scanning electrodes. Each scanning electrode is subjected to a plurality of selections during the entire picture scanning and during the partial rewriting so as to allow display of an identical number of gradation levels both in the entire picture scanning and in the partial rewriting.

Claims

1. A display apparatus comprising:

a display panel comprising a pair of oppositely disposed substrates having thereon a plurality of scanning electrodes and a plurality of data electrodes, and an optical modulation substance disposed between the substrates so as to form a pixel at each intersection of said scanning electrodes and said data electrodes; and

drive means for driving said display panel so that a period of each pixel being placed in a prescribed display state is determined within a frame period depending on given gradation data,

said drive means further dividing one frame period into a first plurality of equivalent blocks of which a second plurality, smaller in number than the first plurality, of mutually non-neighboring blocks are allotted to a partial rewriting for selecting scanning electrodes corresponding to pixels to change display states, and the remaining blocks other than the second plurality of blocks within the first plurality of blocks are allotted to an entire picture scanning for selecting all the scanning electrodes,

during the entire picture scanning, subjecting each scanning electrode to a plurality of selections including a first selection and a second selection within one frame period while setting an interval from the first to the second selection of each scanning electrode so as to provide a first prescribed ratio of the interval to said one frame period, and

during the partial rewriting, subjecting an identical scanning electrode to a plurality of selections including a first selection and a second selection within one block while setting an interval from the first to the second selection of the identical scanning electrode so as to provide a second prescribed ratio of the interval to said one block period, the second prescribed ratio being identical to said first prescribed ratio during the entire picture scanning, thereby allowing display of an identical number of gradation levels both in the entire picture scanning and in the partial rewriting.

2. A display apparatus according to claim 1, wherein the one frame period is divided to include a plurality n of sub-frames having durations suitable for displaying 2ⁿ gradations in the entire picture scanning period, wherein n denotes a positive integer.

3. A display apparatus according to claim 1, wherein the one frame period is divided to include a plurality n of sub-frames having durations suitable for displaying 2ⁿ gradations in the partial rewrite period, wherein n denotes a positive integer.

4. An apparatus according to claim 3, wherein a first ratio of the interval from the first to the second selection to an interval from the second to a subsequent first selection in the entire scanning is identical to a second ratio of the interval from the first to the second selection to an interval from the second to a subsequent first selection in the partial rewriting.

5. A display apparatus according to claim 1, wherein interlaced scanning is performed in the entire picture scanning period.

6. A display apparatus according to claim 1, wherein said optical modulation substance comprises a ferroelectric liquid crystal.

7. A data processing apparatus, including:

a graphic controller for outputting data signals and a scanning scheme signal;

a scanning signal control circuit for outputting scanning line address data and a scanning scheme signal;

a data signal control circuit for outputting display data and a scanning scheme signal; and

a display apparatus comprised of;

a display panel including a pair of oppositely disposed substrates having thereon a plurality of scanning electrodes and a plurality of data electrodes, and an optical modulation substance disposed between the substrates so as to form a pixel at each intersection of said scanning electrodes and said data electrodes; and

drive means for driving said display panel so that a period of each pixel being placed in a prescribed display state is determined within a frame period depending on given gradation data, said drive means further dividing one frame period into a first plurality of equivalent blocks of which a second plurality, smaller in number than the first plurality, of mutually non-neighboring blocks are allotted to a partial rewriting for selecting scanning electrodes corresponding to pixels to change display states, and the remaining blocks other than the second plurality of blocks within the first plurality of blocks are allotted to an entire picture scanning for selecting all the scanning electrodes,

during the entire picture scanning, subjecting each scanning electrode to a plurality of selections including a first selection and a second selection within one frame period while setting an interval from the first to the second selection of each scanning electrode so as to provide a first prescribed ratio of the interval to said one frame period, and

during the partial rewriting, subjecting an identical scanning electrode to a plurality of selections including a first selection and a second selection within one block while setting an interval from the first to the second selection of the identical scanning electrode so as to provide a second prescribed ratio of the interval to said one block period, the second prescribed ratio being identical to said first prescribed ratio during the entire Picture scanning, thereby allowing display of an identical number of gradation levels both in the entire picture scanning and in the partial rewriting.