Liquid crystal apparatus

• US 5,267,065 A
• Filed: 12/30/1991
• Issued: 11/30/1993
• 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): Hajec, Donald T.
• Assistant Examiner(s): Ho, Tan
• Application Number:
  US07/814,436
• Time in Patent Office: 701 Days
• Field of Search: 359/54, 359/56, 340/784, 340/765, 340/805
• 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
• CPC Class Codes: G09G 3/3674 Details of drivers for scan electrodes

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 ferroelectric liquid crystal device having an electrode matrix including a plurality of scanning lines and a plurality of data lines intersecting with said scanning lines, and a ferroelectric liquid crystal disposed between said scanning lines and said data lines, and

drive means for sequentially applying a scanning signal to said scanning lines for selecting a particular scanning lines, and for applying data signals for pixels on the selected scanning line to said data lines,

wherein each of the data signals has a plurality of pulses including a pulse in a control phase and a pulse in an auxiliary phase, and the scanning signal comprises at least three pulses of alternating polarities with respect to a voltage level of a non-selected scanning line, a first pulse and a third pulse of the at least three pulses of the scanning signal are of the same polarity, and the third pulse constitutes a compensation pulse for compensating for the pulse in the auxiliary phase of a data signal for a pixel on the selected scanning line so that a clearing phase of the scanning signal sufficient to simultaneously erase all pixels on a scanning line is applied to all the pixels on the selected scanning line prior to the control phase pulse of the data signals for the pixels on the selected scanning line and after the commencement of application of a pulse in the control phase of data signals for pixels on a scanning line to which a scanning signal is applied immediately prior to application of the scanning signal applied to the selected scanning line.

2. An apparatus according to claim 1, wherein the pulse in the control phase and the pulse in the auxiliary phase of a data signal have mutually opposite polarities with respect to the voltage level of a non-selected scanning line.

3. An apparatus according to claim 1, wherein the auxiliary phase is disposed before and after the control phase, and the auxiliary phase has a duration which is one half that of the control phase.

4. An apparatus according to claim 1, wherein the pixels supplied with the clearing phase of the scanning signal are erased into a black state.

5. An apparatus according to claim 1, wherein the period of the clearing phase of the scanning signal for all the pixels on the selected scanning line overlaps the period of the application of the pulse in the control phase of the data signals for the pixels on the scanning line to which a scanning signal is applied immediately prior to the application of the scanning signal applied to the selected scanning line.

6. A liquid crystal apparatus, comprising:

a ferroelectric liquid crystal device having an electrode matrix including a plurality of scanning lines and a plurality of data lines intersecting with said scanning lines, and a ferroelectric liquid crystal disposed between said scanning lines and said data lines, and

drive means for sequentially applying a scanning signal to said scanning lines for selecting a particular scanning line, and for applying data signals for pixels on the selected scanning line to said data lines,

wherein each of the data signals has a plurality of pulses including a pulse in a control phase and a pulse in an auxiliary phase, and the scanning signal comprising at least three pulses of alternating polarities with respect to a voltage level of a non-selected scanning line, a first pulse and a last pulse of the at least three pulses of the scanning signal being of the same polarity, and the last pulse constituting a compensation pulse for compensating for the pulse in the auxiliary phase of a data signal for a pixel on the selected scanning line, so that a clearing phase of the scanning signal sufficient to simultaneously erase all pixels on one of said scanning lines is applied to all the pixels on the selected scanning line prior to the control phase pulse of the data signals for the pixels on the selected scanning line and after the commencement of application of a pulse in the control phase of data signals for pixels on another scanning line to which a scanning signal is applied immediately prior to application of the scanning signal applied to the selected scanning line.

7. An apparatus according to claim 6, wherein the pulse in the control phase and the pulse in the auxiliary phase of a data signal have mutually opposite polarities with respect to the voltage level of a non-selected scanning line.

8. An apparatus according to claim 6, wherein the auxiliary phase is disposed before and after the control phase, and the auxiliary phase has a duration which is one half that of the control phase.

9. An apparatus according to claim 6, wherein the pixels supplied with the clearing phase of the scanning signal are erased into a black state.

10. An apparatus according to claim 6, wherein the period of the clearing phase of the scanning signal for all the pixels on the selected scanning line overlaps the period of the application of the pulse in the control phase of the data signals for the pixels on the scanning line to which a scanning signal is applied immediately prior to the application of the scanning signal applied to the selected scanning line.

11. A liquid crystal apparatus, comprising:

a ferroelectric liquid crystal device having an electrode matrix including a plurality of scanning lines and a plurality of data lines intersecting with said scanning lines, and a ferroelectric liquid crystal disposed between said scanning lines and said data lines, and

drive means for sequentially applying a scanning signal to said scanning lines for selecting a particular scanning line, and for applying data signals for pixels on the selected scanning line to said data lines,

wherein each of the data signals has a plurality of pulses including a pulse in a control phase and a pulse in an auxiliary phase, and the scanning signal comprises at least three pulses of alternating polarities with respect to a voltage level of a non-selected scanning line, a first pulse and a third pulse of the at least three pulses of the scanning signal are of the same polarity, and the third pulse constitutes a compensation pulse for compensating for the pulse in the auxiliary phase of a data signal for a pixel on the selected scanning line, so that a clearing phase of the scanning signal sufficient to simultaneously erase all pixels on a scanning line is applied to all the pixels on the selected scanning line prior to the control phase pulse of the data signals for the pixels on the selected scanning line and before the termination of application of a pulse in the control phase of data signals for pixels on a scanning line to which a scanning signal is applied immediately prior to application of the scanning signal applied to the selected scanning line.

12. An apparatus according to claim 11, wherein the pulse in the control phase and the pulse in the auxiliary phase of a data signal have mutually opposite polarities with respect to the voltage level of a non-selected scanning line.

13. An apparatus according to claim 11, wherein the auxiliary phase is disposed before and after the control phase, and the auxiliary phase has a duration which is one half that of the control phase.

14. An apparatus according to claim 11, wherein the pixels supplied with the clearing phase of the scanning signal are erased into a black state.

15. An apparatus according to claim 11, wherein the period of the clearing phase of the scanning signal for all the pixels on the selected scanning line overlaps the period of the application of the pulse in the control phase of the data signals for the pixels on the scanning line to which a scanning signal is applied immediately prior to the application of the scanning signal applied to the selected scanning line.

16. A liquid crystal apparatus, comprising:

A ferroelectric liquid crystal device having an electrode matrix including a plurality of scanning lines and a plurality of data lines intersecting with said scanning lines, and a ferroelectric liquid crystal disposed between said scanning lines and said data lines, and

drive means for sequentially applying a scanning signal to said scanning lines for selecting a particular scanning line, and for applying data signals for pixels on the selected scanning line to said data lines,

wherein each of the data signals has a plurality of pulses including a pulse in a control phase and a pulse in an auxiliary phase, and the scanning signals comprising at least three pulses of alternating polarities with respect to a voltage level of a non-selected scanning line, a first pulse and a last pulse of the at least three pulses of the scanning signal being of the same polarity, and the last pulse constituting a compensation pulse for compensating for the pulse in the auxiliary phase of a data signal for a pixel on the selected scanning line, so that a clearing phase of the scanning signal sufficient to simultaneously erase all pixels on one of said scanning lines is applied to all the pixels on the selected scanning line prior to the control phase pulse of the data signals for the pixels on the selected scanning line and before the termination of application of a pulse in the control phase of data signals for pixels on another scanning line to which a scanning signal is applied immediately prior to application of the scanning signal applied to the selected scanning line.

17. An apparatus according to claim 16, wherein the pulse in the control phase and the pulse in the auxiliary phase of a data signal have mutually opposite polarities with respect to the voltage level of a non-selected scanning line.

18. An apparatus according to claim 16, wherein the auxiliary phase is disposed before and after the control phase, and the auxiliary phase has a duration which is one half that of the control phase.

19. An apparatus according to claim 16, wherein the pixels supplied with the clearing phase of the scanning signal are erased into a black state.

20. An apparatus according to claim 16, wherein the period of the clearing phase of the scanning signal for all the pixels on the selected scanning line overlaps the period of the application of the pulse in the control phase of the data signals for the pixels on the scanning line to which a scanning signal is applied immediately prior to the application of the scanning signal applied to the selected scanning line.

21. A liquid crystal apparatus, comprising:

a ferroelectric liquid crystal device having an electrode matrix including a plurality of scanning lines and a plurality of data lines intersecting with said scanning lines, and a ferroelectric liquid crystal disposed between said scanning lines and said data lines, and

drive means for sequentially applying a scanning signal to said scanning lines for selecting a particular scanning line, and for applying data signals for pixels on the selected scanning line to said data lines,

wherein each of the data signals has a plurality of pulses including a pulse in a control phase and a pulse in an auxiliary phase, and the scanning signal comprises at least three pulses of alternating polarities with respect to a voltage level of a non-selected scanning line, a first pulse and a third pulse of the at least three pulses of the scanning signal are of the same polarity, and the third pulse constitutes a compensation pulse for compensating for the pulse in the auxiliary phase of a data signal for a pixel on the selected scanning line, so that a clearing phase of the scanning signal sufficient to simultaneously erase all pixels on a scanning line is applied to all the pixels on the selected scanning the prior to the control phase pulse of the data signals for the pixels on the selected scanning line and before the commencement of application of a pulse in the control phase of data signals for pixels on a scanning line to which a scanning signal is applied immediately prior to application of the scanning signal applied to the selected scanning line.

22. An apparatus according to claim 21, wherein the pulse in the control phase and the pulse in the auxiliary phase of a data signal have mutually opposite polarities with respect to the voltage level of a non-selected scanning line.

23. An apparatus according to claim 21, wherein the auxiliary phase is disposed before and after the control phase, and the auxiliary phase has a duration which is one half that of the control phase.

24. An apparatus according to claim 21, wherein the pixels supplied with the clearing phase of the scanning signal are erased into a black state.

25. An apparatus according to claim 21, wherein the period of the clearing phase of the scanning signal for all the pixels on the selected scanning line overlaps the period of the application of the pulse in the control phase of the data signals for the pixels on the scanning line to which a scanning signal is applied immediately prior to the application of the scanning signal applied to the selected scanning line.

26. A liquid crystal apparatus, comprising:

a ferroelectric liquid crystal device having an electrode matrix including a plurality of scanning lines and a plurality of data lines intersecting with said scanning lines, and a ferroelectric liquid crystal disposed between said scanning lines and said data lines, and

drive means for sequentially applying a scanning signal to said scanning lines for selecting a particular scanning line, and for applying data signals for pixels on the selected scanning line to said data lines,

wherein each of the data signals has a plurality of pulses including a pulse in a control phase and a pulse in an auxiliary phase, and the scanning signal comprising at least three pulses of alternating polarities with respect to a voltage level of a non-selected scanning line, a first pulse and a last pulse of the at least three pulses of the scanning signal being of the same polarity, and the last pulse constituting a compensation pulse for compensating for the pulse int he auxiliary phase of a data signal for a pixel on the selected scanning line, so that a clearing phase of the scanning signal sufficient to simultaneously erase all pixels on one of said scanning lines is applied to all the pixels on the selected scanning line prior to the control phase pulse of the data signals for the pixels on the selected scanning line and before the commencement of application of a pulse in the control phase of data signals for pixels on another scanning line to which a scanning signal is applied immediately prior to application of the scanning signal applied to the selected scanning line.

27. An apparatus according to claim 26, wherein the pulse in the control phase and the pulse in the auxiliary phase of a data signal have mutually opposite polarities with respect to the voltage level of a non-selected scanning line.

28. An apparatus according to claim 26, wherein the auxiliary phase is disposed before and after the control phase, and the auxiliary phase has a duration which is one half that of the control phase.

29. An apparatus according to claim 26, wherein the pixels supplied with the clearing phase of the scanning signal are erased into a black state.

30. An apparatus according to claim 26, wherein the period of the clearing phase of the scanning signal for all the pixels on the selected scanning line overlaps the period of the application of the pulse in the control phase of the data signals for the pixels on the scanning line to which a scanning signal is applied immediately prior to the application of the scanning signal applied to the selected scanning line.

31. A display apparatus, comprising:

(a) a display panel comprising an electrode matrix formed by scanning electrodes and data electrodes,

(b) selection means for selectively subjecting the scanning electrodes to a whole-area rewrite scanning operation or a partial rewrite scanning operation, and

(c) pulse generating means for generating a scanning pulse for the whole-area scanning operation and a scanning pulse for the partial rewrite scanning operation, said scanning pulse for the whole-area scanning operation and said scanning pulse for the partial rewrite scanning operation having mutually different waveforms.

32. A display apparatus according to claim 31, wherein said display panel comprises a ferroelectric liquid crystal in combination with the electrode matrix.