Method for driving optical modulation device

• US 5,633,652 A
• Filed: 05/12/1995
• Issued: 05/27/1997
• Est. Priority Date: 02/17/1984
• Status: Expired due to Fees

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Katagiri, Kazuharu, Kanbe, Junichiro
• Primary Examiner(s): BRIER, JEFFERY A
• Application Number:
  US08/440,345
• Time in Patent Office: 746 Days
• Field of Search: 345/89, 345/97, 359/54, 359/56, 359/84, 359/85
• US Class Current: 345/97
• CPC Class Codes: G02F 1/13781 using smectic liquid crystals G02F1/141 takes precedence
• CPC Class Codes: G09G 2310/0205 Simultaneous scanning of several lines in flat panels
• CPC Class Codes: G09G 2310/06 Details of flat display driving waveforms
• CPC Class Codes: G09G 2320/0209 Crosstalk reduction, i.e. to reduce direct or indirect influences of signals directed to a certain pixel of the displayed image on other pixels of said image, inclusive of influences affecting pixels in different frames or fields or sub-images which constitute a same image, e.g. left and right images of a stereoscopic display
• 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 method for driving an optical modulation device having a group of scanning electrodes and a group of signal electrodes arranged so that picture elements are defined at the intersections therebetween and a bistable optical modulation material assuming one of two stable states between the groups of electrodes, by in a first phase orienting the bistable material at the picture elements on an N-th scanning electrode to one stable state, and applying a writing signal to the signal electrodes in synchronism with a scanning signal to the N-th scanning electrode while orienting the bistable material at the picture elements on an N+1-th scanning electrode to the one stable state. Also disclosed is a driving mode wherein a scanning signal is applied to the whole or a part of the scanning electrodes while, in phase therewith, a signal is applied to the whole or a part of the signal electrodes so that the optical modulation material is oriented to a first stable state, and a second step in which a scanning signal is applied to the whole or a part of the scanning electrodes while in phase therewith, a signal is applied to a selected signal electrode among the whole or a part of the signal electrodes so that the bistable optical modulation material is oriented to a second stable state.

Claims

1. A driving method for driving an optical modulation device comprising:

a plurality of picture elements arranged in the form of a matrix having a plurality of rows and a plurality of columns defined by the intersections of scanning electrodes arranged in rows and signal electrodes arranged in columns, and a chiral smectic liquid crystal, the picture elements in each row being selectively supplied with either a voltage for orienting the chiral smectic liquid crystal to one display state, or another voltage for orienting the chiral smectic liquid crystal to another display state, said driving method comprising the steps of;

applying a plurality of scanning selection signals each comprising a former voltage signal of a first voltage and a latter voltage signal of a second voltage different from the first voltage periodically to a particular one of the scanning electrodes to periodically select that particular scanning electrode;

applying data signals to the signal electrodes, each data signal comprising an information signal for selecting a display state of a picture element on the particular scanning electrode and each data signal having a waveform providing a pulse train of voltage applied to picture elements at intersections of scanning electrodes not receiving the scanning section signals and signal electrodes including at least one pulse having a pulse width shorter than that of the latter voltage signal, whereby the picture elements on the particular scanning electrode supplied with the former voltage signal are non-selectively erased into one display state and a selected picture element on the particular scanning electrode supplied with the latter voltage signal is changed into the other display state depending on the selected information signal, and a non-selected picture element on the particular scanning electrode supplied with the latter voltage signal is held in the one display state; and

applying the former voltage signal of a subsequent scanning selection signal to a scanning electrode selected subsequent to the particular scanning electrode during the period of applying the data signals for selecting the display states of the picture elements on the particular scanning electrode.

2. A driving method according to claim 1, wherein the voltage waveform of the information signal is varied depending on given gradation data.

3. A driving method according to claim 2, wherein the picture element supplied with the voltage waveform varied depending on given gradation data comprises chiral smectic liquid crystal molecules in different orientation states.

4. An optical modulation apparatus, comprising an optical modulation device having:

a plurality of picture elements arranged in the form of a matrix having a plurality of rows and a plurality of columns;

scanning electrodes arranged in rows and signal electrodes arranged in columns defining said matrix of picture elements;

a chiral smectic liquid crystal; and

driving means for;

a) applying a plurality of scanning selection signals each comprising a first voltage signal and a second voltage signal periodically to a particular one of the scanning electrodes to periodically select that particular scanning electrode, and applying data signals to the signal electrode, each data signal comprising an information signal for selecting a display state of a picture element on the particular scanning electrode and each data signal having a waveform providing a pulse train of voltage applied to picture elements at intersections of scanning electrodes not receiving the scanning selection signals and signal electrodes including at least one pulse having a pulse width shorter than that of said latter voltage signal, whereby the picture elements on the particular scanning electrode supplied with the first voltage signal are non-selectively erased into one display state and a selected picture element on the particular scanning electrode supplied with the second voltage signal is place in the other display state depending upon a selected information signal, and a non-selected picture element on the particular scanning electrode supplied with the second voltage signal is maintained in said one display state depending upon a non-selected information signal; and

b) applying the first voltage signal of a subsequent scanning selection signal to a scanning electrode selected subsequent to said particular scanning electrode during the period of applying the data signals for selecting the display states of the pixels on said particular scanning electrode.

5. An optical modulation apparatus according to claim 4, which includes means for varying the voltage waveform of the information signal depending on given gradation data.

6. An optical modulation apparatus according to claim 5, wherein the picture element supplied with the voltage waveform varied depending on given gradation data comprises chiral smectic liquid crystal molecules in different orientation states.

7. An optical modulation apparatus, comprising an optical modulation device having:

a plurality of picture elements arranged in the form of a matrix having a plurality of rows and a plurality of columns;

scanning electrodes arranged in rows and signal electrodes arranged in columns defining said matrix of picture elements;

a chiral smectic liquid crystal disposed between the scanning electrodes and signal electrodes; and

driving means for;

a) applying a plurality of scanning selection signals each comprising a first voltage signal and a second voltage signal different from the first voltage signal periodically to a particular one of the scanning electrodes to periodically select that particular scanning electrode, and applying data signals to the signal electrodes, each data signal comprising an information signal for selecting a display state of a picture element on the particular scanning electrode, so that the picture elements on the particular scanning electrode supplied with the first voltage signal are non-selectively erased into one display state and the picture elements on the particular scanning electrode supplied with the second voltage signal are respectively selected in display state depending on the information signals applied in synchronism with the second voltage signal;

b) applying the first voltage signal of a subsequent scanning selection signal to a scanning electrode selected subsequent to the particular scanning electrode during the period of applying the data signals for selecting the display states of the picture elements on said particular scanning electrode; and

c) applying an AC voltage which does not change the selected display states of the picture elements on the particular scanning electrode to the pixels when the particular scanning electrode is not supplied with the scanning selection signal, said AC voltage comprising a pulse train including at least one pulse having a pulse width shorter than that of said second voltage signal.

8. An optical modulation apparatus, comprising an optical modulation device having:

a plurality of picture elements arranged in the form of a matrix having a plurality of rows and a plurality of columns;

scanning electrodes arranged in rows and signal electrodes arranged in columns defining said matrix of picture elements;

a chiral smectic liquid crystal disposed between the scanning electrodes and signal electrodes; and

driving means for;

a) applying a plurality of scanning selection signals each comprising a first voltage signal and a second voltage signal different from the first voltage signal periodically to a particular one of the scanning electrodes to periodically select that particular scanning electrode, and applying data signals to the signal electrodes, each data signal comprising an information signal having a voltage waveform which varies depending on given gradation data so that (i) the picture elements on the particular scanning electrode supplied with the first voltage signal are non-selectively erased into one display state and (ii) the picture elements on the particular scanning electrode supplied with the second voltage signal are respectively selected in gradational display states depending on the information signals applied in synchronism with the second voltage signal;

b) applying the first voltage signal of a subsequent scanning selection signal to a scanning electrode selected subsequent to said particular scanning electrode during the period of applying the scanning selection signal to said particular scanning electrode; and

c) applying an AC voltage to preclude changing the selected display states of the picture elements on the particular scanning electrode while the particular scanning electrode is not supplied with the scanning selection signal, said AC voltage comprising a pulse train including at least one pulse having a pulse width shorter than that of said second voltage signal.

9. An optical modulation apparatus according to claim 8, wherein a picture element which is supplied with the voltage waveform which varies depending on given gradation data comprises chiral smectic liquid crystal molecules in different orientation states.

10. A driving method for driving an optical modulation device comprising:

a plurality of picture elements arranged in the form of a matrix having a plurality of rows and a plurality of columns defined by the intersections of scanning electrodes arranged in rows and signal electrodes arranged in columns, and a liquid crystal having a memory characteristic, the picture elements in each row being selectively supplied with either a voltage for orienting the liquid crystal to one display state, or another voltage for orienting the liquid crystal to another display state, said driving method comprising the steps of;

applying a plurality of scanning selection signals each comprising a former voltage signal of a first voltage and a latter voltage signal of a second voltage different from the first voltage periodically to a particular one of the scanning electrodes to periodically select that particular scanning electrode;

applying data signals to the signal electrodes, each data signal comprising an information signal for selecting a display state of a picture element on the particular scanning electrode and each data signal having a waveform providing a pulse train of voltage applied to picture elements at intersections of scanning electrodes not receiving the scanning signals and signal electrodes including at least one pulse having a pulse width shorter than that of the latter voltage signal, whereby the picture elements on the particular scanning electrode supplied with the former voltage signal are non-selectively erased into an erased state and a selected picture element on the particular scanning electrode supplied with the latter voltage signal is placed in either the one display state or the other display state depending on an information signal; and

applying the former voltage signal of a subsequent scanning selection signal to a scanning electrode selected subsequent to the particular scanning electrode during the period of applying the data signals for selecting the display states of the picture elements on the particular scanning electrode.

11. A driving method according to claim 10, wherein the voltage waveform of the information signal is varied depending on given gradation data.

12. A driving method according to claim 11, wherein the picture element supplied with the voltage waveform varied depending on given gradation data comprises liquid crystal molecules in different orientation states.

13. An optical modulation apparatus, comprising:

a plurality of picture elements arranged in the form of a matrix having a plurality of rows and a plurality of columns;

scanning electrodes arranged in rows and signal electrodes arranged in columns defining said matrix of picture elements;

a liquid crystal having a memory characteristic; and

driving means for;

a) applying a plurality of scanning selection signals each comprising a first voltage signal and a second voltage signal periodically to a particular one of the scanning electrodes to periodically select that particular scanning electrode, and applying data signals to the signal electrode, each data signal comprising an information signal for selecting display state of a picture element on the particular scanning electrode and each data signal having a waveform providing a pulse train of voltage applied to picture elements at intersections of scanning electrodes not receiving the scanning selection signals and signal electrodes including at least one pulse having a pulse width shorter than that of said latter voltage signal, whereby the picture elements on the particular scanning electrode supplied with the first voltage signal are non-selectively erased into an erased state and a picture element on the particular scanning electrode supplied with the second voltage signal is placed in either the one display state or the other display state depending upon an information signal; and

b) applying the first voltage signal of a subsequent scanning selection signal to a scanning electrode selected subsequent to said particular scanning electrode during the period of applying the data signals for selecting the display states of the pixels on said particular scanning electrode.

14. An optical modulation apparatus according to claim 13, which includes means for varying the voltage waveform of the information signal depending on given gradation data.

15. An optical modulation apparatus according to claim 14, wherein the picture element supplied with the voltage waveform varied depending on given gradation data comprises liquid crystal molecules in different orientation states.

16. A driving method for driving an optical modulation device comprising:

a plurality of picture elements arranged in the form of a matrix having a plurality of rows and a plurality of columns defined by the intersections of scanning electrodes arranged in rows and signal electrodes arranged in columns, and a liquid crystal having a memory characteristic;

the picture elements in each row being selectively supplied with either a voltage for orienting the liquid crystal to one display state, or another voltage for orienting the liquid crystal to another display state, said driving method comprising the steps of;

applying periodically a scanning selection signal comprising a former voltage signal of a first voltage and a latter voltage signal of a second voltage different from the first voltage to a particular one of the scanning electrodes to select that particular scanning electrode;

applying data signals to the signal electrodes, each data signal comprising an information signal for selecting a display state of a picture element on the particular scanning electrode and each data signal having a waveform providing a pulse train of voltage applied to picture elements at intersections of scanning electrodes not receiving the scanning selection signals and signal electrodes including at least one pulse having a pulse width shorter than that of said latter voltage signal, whereby the picture elements on the particular scanning electrode supplied with the former voltage signal are non-selectively erased into an erased state and a selected picture element on the particular scanning electrode supplied with the latter voltage signal is placed in either the one display state or the other display state depending on an information signal; and

applying the former voltage signal of a subsequent scanning selection signal to a scanning electrode selected subsequent to the particular scanning electrode during the period of applying the data signals for selecting the display states of the picture elements on said particular scanning electrode.

17. A driving method according to claim 16, wherein the voltage waveform of the information signal is varied depending on given gradation data.

18. A driving method according to claim 17, wherein the picture element supplied with the voltage waveform varied depending on given gradation data comprises liquid crystal molecules in different orientation states.