Scanning driver circuit for ferroelectric liquid crystal device

• US 4,930,875 A
• Filed: 06/27/1989
• Issued: 06/05/1990
• Est. Priority Date: 02/17/1986
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Inoue, Hiroshi, Inaba, Yutaka, Osada, Yoshiyuki
• Primary Examiner(s): James, Andrew J.
• Assistant Examiner(s): Duong, Tai V.
• Application Number:
  US07/372,169
• Time in Patent Office: 343 Days
• Field of Search: 350/332, 350/333, 350/350 S, 340/718, 340/719, 340/805, 340/811, 340/784, 357/23.7, 377/54
• US Class Current: 345/97
• CPC Class Codes: G09G 2310/061 for resetting or blanking
• 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 3/3629 using liquid crystals having memory effects, e.g. ferroelectric liquid crystals
• CPC Class Codes: G09G 3/3692 suitable for passive matrices only
• CPC Class Codes: G09G 3/3696 Generation of voltages supplied to electrode drivers

Abstract

A driving apparatus includes a scanning driver circuit connected to scanning electrodes and a signal driver circuit connected to signal electrodes. The scanning driver circuit includes: (1) a drive signal voltage generating unit which includes a first signal voltage generating unit for generating a scanning selection signal voltage supplied to a first bus, and a second signal voltage generating unit for generating a scanning nonselection signal voltage supplied to a second bus, (2) a switching circuit unit for selectively supplying the scanning selection signal or the scanning nonselection signal to a scanning electrode, and (3) a switching signal generating unit for supplying a switching control signal to the switching circuit unit.

Claims

1. A driving apparatus, comprising a scanning driver circuit connected to scanning electrodes and a signal driver circuit connected to signal electrodes, said scanning driver circuit comprising:

(1) a driver signal voltage generating unit which includes;

a first signal voltage generating unit comprising;

a first circuit for generating a scanning selection signal including a sequence of three voltages comprising a voltage of one polarity, a voltage of the other polarity, and zero voltage, and

means for controlling said first circuit so as to generate the sequence of three voltages in different phases and for continuously supplying the scanning selection signal comprising the sequence of three voltages to a first bus, the polarities and the zero level of the voltages being defined with respect to a scanning nonselection signal voltage, and

a second signal voltage generating unit for generating a scanning nonselection signal voltage continuously supplied to a second bus;

(2) a switching circuit unit for selectively supplying the scanning selection signal or the scanning nonselection signal to a scanning electrode; and

(3) a switching signal generating unit for supplying a switching control signal to the switching circuit unit.

2. An apparatus according to claim 1, wherein said switching signal generating unit generates a switching control signal for sequentially supplying the scanning selection signal to the scanning electrodes.

3. An apparatus according to claim 1, wherein said switching circuit unit comprises a transistor.

4. An apparatus according to claim 3, wherein the transmitter in the switching circuit unit comprises a field effect transistor.

5. An apparatus according to claim 4, wherein said field effect transistor comprises a thin film transistor.

6. An apparatus according to claim 5, wherein said thin film transistor comprises a semiconductor film of amorphous silicon, polysilicon, CdSe or ZnSe.

7. An apparatus according to claim 1, wherein said switching signal generating circuit includes a shift register and an inverter.

8. An apparatus according to claim 7, wherein said shift register is a dynamic shift register.

9. A driving apparatus for a display panel of a type comprising matrix electrodes formed by scanning electrodes and signal electrodes arranged to intersect with the scanning electrodes, wherein a contrast at each intersection of the scanning electrodes and the signal electrodes is discriminated depending on the direction of an electric field applied to the intersection, said scanning electrodes being connected to a scanning driver circuit and said signal electrodes being connected to a signal driver circuit, said scanning driver circuit comprising:

(1) a driver signal voltage generating unit which includes;

a first signal voltage generating unit comprising;

a first circuit for generating a scanning selection signal including a sequence of three voltages comprising a voltage of one polarity, a voltage of the other polarity, and zero voltage, and

means for controlling said first circuit so as to generate the sequence of three voltages in different phases and for continuously supplying the scanning selection signal comprising the sequence of three voltages to a first bus, the polarities and the zero level of the voltages being defined with respect to a scanning nonselection signal voltage, and

a second signal voltage generating unit for generating a scanning nonselection signal voltage continuously supplied to a second bus;

(2) a switching circuit unit for selectively supplying the scanning selection signal or the scanning nonselection signal to a scanning electrode; and

(3) a switching signal generating unit for supplying a switching control signal to the switching circuit unit.

10. An apparatus according to claim 9, wherein said switching signal generating unit generates a switching control signal for sequentially supplying the scanning selection signal to the scanning electrodes.

11. An apparatus according to claim 9, wherein said scanning nonselection signal voltage comprises a constant voltage, and wherein said scanning selection signal voltage comprises a positive-polarity voltage and a negative-polarity voltage respectively with reference to the scanning nonselection signal voltage.

12. An apparatus according to claim 9, wherein said scanning nonselection signal voltage is a constant voltage, and wherein said scanning selection signal voltage comprises a positive-polarity voltage, a negative polarity voltage and a voltage of the same level, respectively, with reference to the scanning nonselection signal voltage.

13. An apparatus according to claim 9, further comprising synchronizing means for synchronizing the scanning selection signal with a data signal supplied from said signal driver circuit to a signal electrode.

14. An apparatus according to claim 9, wherein said switching circuit unit comprises a transistor.

15. An apparatus according to claim 14, wherein the transistor in the switching circuit unit comprises a field effect transistor.

16. An apparatus according to claim 15, wherein said field effect transistor comprises a thin film transistor.

17. An apparatus according to claim 16, wherein said thin film transistor comprises a semiconductor film of amorphous silicon, polysilicon, CdSe or ZnSe.

18. An apparatus according to claim 9, wherein said switching signal generating circuit includes a shift register and an inverter.

19. An apparatus according to claim 18, wherein said shift register comprises a dynamic shift register.

20. An apparatus according to claim 9, wherein a ferroelectric liquid crystal is disposed at the intersections of the scanning electrodes and the signal electrodes.

21. An apparatus according to claim 20, wherein said ferroelectric liquid crystal comprises a chiral smectic liquid crystal.

22. An apparatus according to claim 21, wherein said chiral smectic liquid crystal is disposed in a layer thin enough to release the helical structure inherent to the chiral smectic liquid crystal in the absence of an electric field.

23. An apparatus according to claim 9, wherein said switching circuit is disposed on a substrate constituting said display panel.

24. An apparatus according to claim 9, wherein said switching circuit, switching signal generating unit, first bus, and second bus are disposed on a substrate constituting said display panel.