Driving apparatus for an electrode matrix suitable for a liquid crystal panel

• US 5,066,945 A
• Filed: 10/25/1988
• Issued: 11/19/1991
• Est. Priority Date: 10/26/1987
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Inoue, Hiroshi, Mizutome, Atsushi, Kanno, Hideo
• Primary Examiner(s): Brier, Jeffery A.
• Application Number:
  US07/262,576
• Time in Patent Office: 1,120 Days
• Field of Search: 340/765, 340/784, 340/805, 340/811, 340/812, 340/813, 350/331 T, 350/332, 350/333, 350/350 S, 358/230, 358/236
• US Class Current: 345/101
• CPC Class Codes: G09G 2320/041 Temperature compensation
• CPC Class Codes: G09G 3/36 using liquid crystals
• CPC Class Codes: G09G 3/3629 using liquid crystals having memory effects, e.g. ferroelectric liquid crystals
• CPC Class Codes: G09G 3/3696 Generation of voltages supplied to electrode drivers

Abstract

A driving apparatus comprises a driving unit and a drive voltage generating unit. The driving unit includes a scanning electrode driver and a data electrode driver for driving an electrode matrix formed of scanning electrodes and data electrodes. The drive voltage generating unit includes a first means for generating a fixed voltage, a second means for generating a source voltage for providing drive voltages for driving the electrode matrix, and a third means for generating a first voltage equal to a subtraction of the fixed voltage from the source voltage and a second voltage equal to a subtraction of the source voltage from the fixed voltage. The first and second voltages are preferably controlled so as to vary depending on an external temperature.

Claims

1. A driving apparatus, comprising:

a) a driving unit including a scanning electrode driver and a data electrode driver for driving an electrode matrix formed of scanning electrodes and data electrodes, and

b) a drive voltage generating unit including a first means for generating a fixed voltage, a second means for generating a source voltage for providing drive voltages for driving the electrode matrix, and a third means for generating a first voltage equal to a subtraction of the fixed voltage from the source voltage and a second voltage equal to a subtraction of the source voltage from the fixed voltage,

wherein the first voltage and the second voltage are of mutually opposite polarities with respect to the fixed voltage, and the fixed voltage is a voltage set to an intermediate value between a maximum output voltage and a minimum output voltage of the drive voltage generating unit.

2. An apparatus according to claim 1, wherein said drive voltage generating unit includes means for generating voltages equal to additions of an offset voltage to the first voltage and the second voltage, respectively.

3. An apparatus according to claim 2, wherein said offset voltage is equal to the fixed voltage.

4. An apparatus according to claim 1, wherein said third means includes means for generating division voltages between the first and second voltages.

5. An apparatus according to claim 1, wherein said third means includes a plurality of resistors arranged in series between the output stage for generating the first voltage and the output stage for generating the second voltage.

6. An apparatus according to claim 1, wherein said fixed voltage is a mid voltage between the maximum output voltage and the minimum output voltage of the drive voltage generating unit.

7. A liquid crystal apparatus, comprising:

a) a driving apparatus according to claim 1, and

b) a liquid crystal panel comprising a first substrate having scanning electrodes thereon, a second substrate having data electrodes thereon, and a liquid crystal disposed between the first and second substrates.

8. A liquid crystal apparatus according to claim 7, wherein said liquid crystal is a chiral smectic liquid crystal.

9. A liquid crystal apparatus according to claim 8, wherein said chiral smectic liquid crystal is a liquid crystal having ferroelectric properties.

10. A liquid crystal apparatus according to claim 9, wherein said liquid crystal having ferroelectric properties is bistable.

11. A driving apparatus, comprising:

a) a driving unit including a scanning electrode driver and a data electrode driver for driving an electrode matrix formed of scanning electrodes and data electrodes,

b) a drive voltage generating unit including a first means for generating a fixed voltage, a second means for generating a source voltage for providing drive voltages for driving the electrode matrix, and a third means for generating a first voltage equal to a subtraction of the fixed voltage from the source voltage and a second voltage equal to a subtraction of the source voltage from the fixed voltage, and

c) control means for controlling the drive voltage generating means so that the first and second voltages will be prescribed voltages varying depending on an external temperature,

wherein the first voltage and the second voltage are of mutually opposite polarities with respect to the fixed voltage, and the fixed voltage is a voltage set to an intermediate value between a maximum output voltage and a minimum output voltage of the drive voltage generating unit.

12. An apparatus according to claim 11, wherein said drive voltage generating unit includes means for generating voltages equal to additions of an offset voltage to the first voltage and the second voltage, respectively.

13. An apparatus according to claim 12, wherein said offset voltage is equal to the fixed voltage.

14. An apparatus according to claim 11, wherein said third means includes means for generating division voltages between the first and second voltages.

15. An apparatus according to claim 11, wherein said third means includes a plurality of resistors arranged in series between the output stage for generating the first voltage and the output stage for generating the second voltage.

16. A driving apparatus, comprising:

a) a driving unit including a scanning electrode driver and a data electrode driver for driving an electrode matrix formed of scanning electrodes and data electrodes,

b) a drive voltage generating unit including a first means for generating a fixed voltage, a second means for generating a source voltage for providing drive voltages for driving the electrode matrix, and a third means for generating a first voltage equal to a subtraction of the fixed voltage from the source voltage and a second voltage equal to a subtraction of the source voltage from the fixed voltage, and

c) control means for controlling said second means so that said source voltage will be a prescribed voltage varying depending on an external temperature,

wherein the first voltage and the second voltage are of mutually opposite polarities with respect to the fixed voltage, and the fixed voltage is a voltage set to an intermediate value between a maximum output voltage and a minimum output voltage of the drive voltage generating unit.

17. An apparatus according to claim 16, wherein said drive voltage generating unit includes means for generating voltages equal to additions of an offset voltage to the first voltage and the second voltage, respectively.

18. An apparatus according to claim 17, wherein said offset voltage is equal to the fixed voltage.

19. An apparatus according to claim 16, wherein said third means includes means for generating division voltages between the first and second voltages.

20. An apparatus according to claim 16, wherein said third means includes a plurality of resistors arranged in series between the output stage for generating the first voltage and the output stage for generating the second voltage.

21. A driving apparatus, comprising:

a) a driving unit including a scanning electrode driver and a data electrode driver for driving an electrode matrix formed of scanning electrodes and data electrodes, and

b) a drive voltage generating unit including a first means for holding a plurality of different voltages, a second means for generating a fixed voltage, and a third means for generating a plurality of voltages each obtained from one voltage of the plurality of the different voltages either by subtracting the fixed voltage from the one voltage or by subtracting the one voltage from the fixed voltage,

wherein at least one of said plurality of different voltages has a polarity opposite to that of the other of said plurality of different voltages with respect to the fixed voltage, and the fixed voltage is a voltage set to an intermediate value between a maximum output voltage and a minimum output voltage of the drive voltage generating unit.

22. An apparatus according to claim 21, wherein said drive voltage generating unit includes means for generating voltages equal to additions of an offset voltage to the voltage obtained by the subtraction.

23. An apparatus according to claim 21, which includes a control means;

said first means including a plurality of voltage holding means, and the control means controlling the plurality of holding means so that they will respectively hold one of the plurality of voltages which are serially supplied.

24. An apparatus according to claim 21, wherein said first means comprises a data register and a digital/analog converter.

25. An apparatus according to claim 21, wherein said third means generates a maximum voltage and a minimum voltage which are of mutually opposite polarities with respect to the fixed voltage.

26. An apparatus according to claim 21, wherein said fixed voltage is a mid voltage between the maximum output voltage and the minimum output voltage of the drive voltage generating unit.

27. A liquid crystal apparatus, comprising:

a) a driving apparatus according to claim 21, and

b) a liquid crystal panel comprising a first substrate having scanning electrodes thereon, a second substrate having data electrodes thereon, and a liquid crystal disposed between the first and second substrates.

28. A liquid crystal apparatus according to claim 27, wherein said liquid crystal is a chiral smectic liquid crystal.

29. A liquid crystal apparatus according to claim 28, wherein said chiral smectic liquid crystal is a liquid crystal having ferroelectric properties.

30. A liquid crystal apparatus according to claim 29, wherein said liquid crystal having ferroelectric properties is bistable.

31. A driving apparatus, comprising:

a) a driving unit including a scanning electrode driver and a data electrode driver for driving an electrode matrix formed of scanning electrodes and data electrodes,

b) a drive voltage generating unit including a first means for holding a plurality of different voltages, a second means for generating a fixed voltage, and a third means for generating a plurality of voltages each obtained from one voltage of the plurality of the different voltages either by subtracting the fixed voltage from the one voltage or by subtracting the one voltage from the fixed voltage, and

c) control means for controlling the drive voltage generating means so that the plurality of voltages obtained by the subtraction will be prescribed voltages varying depending on an external temperature,

wherein at least one of said plurality of different voltages has a polarity opposite to that of the other of said plurality of different voltages with respect to the fixed voltage, and the fixed voltage is a voltage set to an intermediate value between a maximum output voltage and a minimum output voltage of the drive voltage generating unit.

32. An apparatus according to claim 31, wherein said drive voltage generating unit includes means for generating voltages equal to additions of an offset voltage to the plurality of the voltages obtained by the subtraction, respectively.

33. An apparatus according to claim 31, which includes a control means;

said first means including a plurality of voltage holding means, and the control means controlling the plurality of holding means so that they will respectively hold one of the plurality of voltages which are serially supplied.

34. An apparatus according to claim 31, wherein said first means comprises a data register and a digital/analog converter.

35. An apparatus according to claim 31, wherein said third means generates a maximum voltage and a minimum voltage which are of mutually opposite polarities with respect to the fixed voltage.

36. An apparatus according to claim 31, wherein said third means generates a maximum voltage and a minimum voltage which are of mutually opposite polarities with respect to the fixed voltage.

37. A driving apparatus, comprising:

a) a driving unit including a scanning electrode driver and a data electrode driver for driving an electrode matrix formed of scanning electrodes and data electrodes,

b) a drive voltage generating unit including a first means for holding a plurality of different voltages, a second means for generating a fixed voltage, and a third means for generating a plurality of voltages each obtained from one voltage of the plurality of the different voltages either by subtracting the fixed voltage from the one voltage or by subtracting the one voltage from the fixed voltage, and

c) control means for controlling the drive voltage generating means so that the plurality of different voltages held by the first means will be prescribed voltages varying depending on an external temperature,

wherein at least one of said plurality of different voltages has a polarity opposite to that of the other of said plurality of different voltages with respect to the fixed voltage, and the fixed voltage is a voltage set to an intermediate value between a maximum output voltage and a minimum output voltage of the drive voltage generating unit.

38. An apparatus according to claim 37, wherein said drive voltage generating unit includes means for generating voltages equal to additions of an offset voltage to the plurality of the voltages obtained by the subtraction, respectively.

39. An apparatus according to claim 37, further comprising a holding control means, wherein said first means comprises a plurality of voltage holding means, and wherein said holding control means controls said plurality of holding means so as to respectively hold one of the plurality of different voltages which are serially supplied.

40. An apparatus according to claim 37, wherein said first means comprises a data register and a digital/analog converter.