Chiral smectic liquid crystal display and method of selectively driving the scanning and data electrodes

• US 5,815,130 A
• Filed: 06/01/1995
• Issued: 09/29/1998
• Est. Priority Date: 04/24/1989
• Status: Expired due to Fees

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Tsuboyama, Akira, Hotta, Yoshio, Inaba, Yutaka, Taniguchi, Osamu, Katakura, Kazunori, Mihara, Tadashi, Iwayama, Mitsuo
• Primary Examiner(s): Saras, Steven J.
• Assistant Examiner(s): Bell, Paul A.
• Application Number:
  US08/456,725
• Time in Patent Office: 1,216 Days
• Field of Search: 345/94, 345/97, 345/103, 345/208, 345/79, 345/96, 345/209, 359/54, 359/55, 359/56, 359/104, 349/37
• US Class Current: 345/94
• 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 liquid crystal apparatus includes: a ferroelectric liquid crystal device comprising an electrode matrix including a plurality of scanning lines and a plurality of data lines intersecting with the scanning lines, and a ferroelectric liquid crystal disposed between the scanning lines and data lines, and a driver for sequentially applying a scanning signal to the scanning lines for selecting a particular scanning line, and for applying data signals for the pixels on the selected scanning line to the data lines. Each of the data signals has a plurality of pulses including a pulse in a controlled phase and a pulse in an auxiliary phase, and the scanning signal for the selected scanning line has a compensation pulse for compensating the pulse in the auxiliary phase of a data signal for a pixel on the selected scanning line.

Claims

1. A liquid crystal apparatus, comprising:

a chiral smectic liquid crystal device having a group of scanning electrodes arranged in a matrix with and spaced apart from a group of signal electrodes with a chiral smectic liquid crystal disposed therebetween so as to provide a picture element at each intersection of the scanning electrodes and the signal electrodes, and signal application means for applying information signals to the signal electrodes in phase with scanning signals selectively applied to the scanning electrodes, said signal application means being arranged;

(a) to apply a preceding scanning selection signal comprising a former voltage of one polarity and a latter voltage of the other polarity to a particular one of the scanning electrodes to select that particular scanning electrode and, in synchronism with the scanning selection signal applied to select the particular scanning electrode, to apply data signals to the signal electrodes so that the pixels on the particular scanning electrode supplied with the former voltage of one polarity are non-selectively erased into one display state and the pixels on the particular scanning electrode supplied with the latter voltage of the other polarity are respectively selected in display states depending on the information signals applied in synchronism with the latter voltages of the other polarity, and

(b) to apply a subsequent scanning selection signal comprising a former voltage of said the other polarity and a latter voltage of said one polarity to a scanning electrode selected subsequent to said particular scanning electrode to select the subsequently selected scanning electrode, so that the former voltage of said the other polarity of the subsequent scanning selection signal is applied during the period of applying the data signals for selecting the display states of the pixels on said particular scanning electrode;

wherein said former voltage of said preceding scanning selection signal and said former voltage of said subsequent scanning selection signal are of mutually opposite polarities, and said latter voltage of said preceding scanning selection signal and said latter voltage of said subsequent scanning selection signal are of mutually opposite polarities,

the voltage polarities being determined with respect to the voltage level of a scanning electrode to which the scanning selection signal is not applied, and

wherein said former voltage of the preceding scanning selection signal and said former voltage of the subsequent scanning selection signal overlap each other for a period of time.

2. A liquid crystal apparatus according to claim 1, wherein said preceding and subsequent scanning selection signals are alternately applied to successively selected scanning electrodes.

3. A liquid crystal apparatus according to claim 1, wherein the picture elements on a scanning electrode receiving said former voltage of the scanning selection signal are non-selectively erased into one display state as a result of application of said former voltage of the scanning selection signal in combination with the data signals applied in synchronism therewith.

4. A liquid crystal apparatus, comprising:

(a) a liquid crystal panel having a group of scanning electrodes, a group of signal scanning electrodes intersecting with the scanning electrodes and a chiral smectic liquid crystal disposed so as to provide a picture element at each intersection of the scanning electrodes and the signal electrodes, and

(b) signal application means for sequentially applying a scanning selection signal having a former voltage of one polarity and a latter voltage of the other polarity to the scanning electrodes and, in synchronism with the scanning selection signal, applying data signals depending on given data,

wherein a preceding scanning selection signal and a subsequent scanning selection signal overlapping each other in time are successively applied to the scanning electrodes, and the former voltage of said preceding scanning selection signal and the former voltage of said subsequent scanning selection signal are of mutually opposite polarities, and the latter voltage of said preceding scanning selection signal and the latter voltage of said subsequent scanning selection signal are of mutually opposite polarities,

the voltage polarities being determined with respect to the voltage level of a scanning electrode to which the scanning selection signal is not applied and,

wherein said former voltage of the preceding scanning selection signal and said former voltage of the subsequent scanning selection signal overlap each other for a period of time.

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

6. A liquid crystal apparatus according to claim 4, wherein said liquid crystal is a ferroelectric liquid crystal.

7. A liquid crystal apparatus according to claim 4, wherein said preceding and subsequent scanning selection signals are alternately applied to successively selected scanning electrodes.