Liquid crystal apparatus

• US 5,675,354 A
• Filed: 11/18/1994
• Issued: 10/07/1997
• Est. Priority Date: 01/07/1991
• Status: Expired due to Fees

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Mihara, Tadashi, Hotta, Yoshio, Katakura, Kazunori, Iwayama, Mitsuo
• Primary Examiner(s): Hjerpe, Richard
• Assistant Examiner(s): Mengistu, Amare
• Application Number:
  US08/344,609
• Time in Patent Office: 1,054 Days
• Field of Search: 395/157, 395/158, 345/87, 345/97, 345/98, 345/100, 345/208, 359/55, 359/56, 359/84
• US Class Current: 345/97
• 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 2310/04 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 2310/065 Waveforms comprising zero voltage phase or pause
• CPC Class Codes: G09G 3/3629 using liquid crystals having memory effects, e.g. ferroelectric liquid crystals

Abstract

A liquid crystal apparatus comprises: matrix electrodes which are formed by a scanning electrode group and an information electrode group which intersect the scanning electrode group so as to face the scanning electrode group; a ferroelectric liquid crystal which is arranged between those electrode groups and is driven by an electric field applied through the electrode groups; a drive circuit having a scanning side drive circuit for sequentially generating scan selection signals to the scanning electrode group and for generating scan non-selection signals to the scanning electrodes whose scan is not selected and an information side drive circuit for generating information signals to the information electrode group synchronously with the scan selection signal in accordance with the input information; and a control circuit for controlling the drive circuit in a manner such that an interval between two scan selection signals which are continuously applied to the same scanning electrode is set to a predetermined period of time smaller than a full screen scanning period.

Claims

1. A liquid crystal apparatus comprising:

a matrix of electrodes formed by a scanning electrode group and an information electrode group which intersect said scanning electrode group so as to face the scanning electrode group;

a liquid crystal having a memory function which is arranged between said electrode groups and is driven by an electric field applied through said electrode groups;

means for providing input information;

a drive circuit having a scanning side drive circuit for sequentially supplying scan selection signals to the scanning electrode group and for generating scan non-selection signals to the scanning electrodes whose scan is not selected and an information side drive circuit for supplying information signals to said information electrode group synchronously with the scan selection signal in accordance with the input information; and

control means for controlling said drive circuit by selecting one of first and second modes, wherein, in the first mode the drive circuit is controlled so that the scan selection signal is applied sequentially to each of the scan electrodes to form a full image during one full-image vertical scan interval, and wherein in the second mode the drive circuit is controlled so that each of a plurality of the scan electrodes corresponding to a partial image area of the full image are designated and the scan signal is applied sequentially to each of the designated scan electrodes in a partial vertical scan during a partial-image vertical scan interval,

wherein, when said second mode is selected and partial-image vertical scans are successively and repetitively made at least two times only for the designated same scan electrodes, thereby displaying a movement of a cursor in a horizontal direction, an interval between application of two scan selection signals to a particular one of the designated scan electrodes in successive repetitive partial-image vertical scans is set to be longer than a period of one of the partial-image vertical scans among said repetitive partial-image vertical scans.

2. An apparatus according to claim 1, wherein an application interval between the two scan selection signals to the particular one of the designated scan electrodes is at least 16 times as long as a time for applying the scan selection signal.

3. An apparatus according to claim 1, further including means for setting an application interval between the two scan selection signals shorter than the full image-vertical scan interval.

4. A liquid crystal apparatus according to claim 1, wherein said liquid crystal having the memory function is a chiral smectic liquid crystal.

5. A liquid crystal apparatus according to claim 4, wherein said chiral smectic liquid crystal is a ferroelectric liquid crystal.