Driving method and apparatus for display device

• US 6,028,573 A
• Filed: 09/17/1996
• Issued: 02/22/2000
• Est. Priority Date: 08/29/1988
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Eto, Masahiro, Sakamoto, Kouzou, Okabe, Takeaki, Mikoshiba, Shigeo, Orita, Isamu, Kougami, Akihiko
• Primary Examiner(s): Brier, Jeffrey
• Assistant Examiner(s): LEWIS, DAVID LEE
• Application Number:
  US08/715,166
• Time in Patent Office: 1,253 Days
• Field of Search: 345/60-86, 345/204-208, 315/241 R
• US Class Current: 345/66
• CPC Class Codes: G09G 2310/0267 Details of drivers for scan electrodes, other than drivers for liquid crystal, plasma or OLED displays
• CPC Class Codes: G09G 2310/0275 Details of drivers for data electrodes, other than drivers for liquid crystal, plasma or OLED displays, not related to handling digital grey scale data or to communication of data to the pixels by means of a current
• CPC Class Codes: G09G 2310/0289 Details of voltage level shifters arranged for use in a driving circuit
• CPC Class Codes: G09G 2330/02 Details of power systems and of start or stop of display operation
• CPC Class Codes: G09G 2330/023 using energy recovery or conservation
• CPC Class Codes: G09G 3/20 for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
• CPC Class Codes: G09G 3/296 Driving circuits for producing the waveforms applied to the driving electrodes
• CPC Class Codes: H03K 17/04123 in field-effect transistor switches
• CPC Class Codes: H03K 17/6871 the output circuit comprising more than one controlled field-effect transistor
• CPC Class Codes: H03K 17/6877 the control circuit comprising active elements different from those used in the output circuit

Abstract

In a method for driving a display device, by which energy stored in a plurality of electrodes serving as a capacitive load is recovered through switches, current paths for charging said electrodes from a charge supplying source differ from current paths for discharging the electrodes for the energy recovery.

Claims

1. A method for driving a display device, by which energy is supplied to a plurality of electrodes serving a capacitive load through a first group of switches and is recovered from said electrodes through a second group of switches, said method comprising the steps of:

charging each of a first number of said electrodes through a first path from a charge supplying source to said each of said first number of electrodes, said first path comprising a first inductance and a corresponding one of said first group of switches; and

discharging each of a second number said electrodes through a second path from each of said second number of electrodes to said charge supplying source, said second path comprising a corresponding one of said second group of switches and a second inductance, wherein

said first and second inductances are distinct from one another, and

said charging and discharging are effected at substantially a same time.

2. A method for driving a display device according to claim 1, further comprising the steps of

detecting said first number of electrodes for charging and detecting said second number of electrodes for discharging, and

controlling an inductance value for each of said first and second paths depending on the detected first and second numbers.

3. A circuit for driving a display device having a plurality of electrodes for display elements serving as a capacitive load, said driving circuit comprising:

a charging supply source comprising one of a power supply and a charged capacitor;

a first series circuit including a first switch, a first diode and a first inductance element, said first series circuit being connected, at a first terminal, with said charging supply source, and being connected, at an output terminal, with at least two of said electrodes through at least two corresponding first unidirectional switches so that, when said at least two electrodes are being charged, said first switch, said first diode and said corresponding first unidirectional switches are made conductive; and

a second series circuit including a second switch, a second diode and a second inductance element, said second series circuit being connected, at a first terminal, with said charging supply source, and being connected, at an output terminal, with at least two of said electrodes through at least two corresponding second unidirectional switches so that, when said at least two electrodes are being charged, said second switch, said second diode and said corresponding second unidirectional switches are made conductive, wherein

said first and second inductances are distinct from one another.

4. A circuit for driving a display device according to claim 3, wherein an output terminal of said first inductance element is connected with a switching circuit for holding said output terminal of said first inductance element at a level of a high voltage power supply, and an output terminal of said second inductance element is connected with a switching circuit for holding said output terminal of said second inductance element at a level of a low voltage power supply.

5. A circuit for driving a display device according to claim 3, wherein each of said first and said second unidirectional switches is formed by a series circuit of a diode and an FET.

6. A circuit for driving a display device according to claim 3, wherein each of said first and said second unidirectional switches is formed by a bipolar transistor circuit.

7. A circuit for driving a display device according to claim 3, wherein

a plurality of said first series circuits, each of which includes said first switching circuit, said first diode, and said first inductance elements, are connected in parallel, inductance values of said plurality of first inductance elements forming a binary system, and

a plurality of said second series circuits, each of which include said second switching circuit, said second diode, and said second inductance elements, are connected in parallel, inductance values of said plurality of second inductance elements forming a binary system.

8. A circuit for driving a display device according to claim 3, wherein each of said plurality of electrodes is connected with a voltage hold circuit for holding levels of said electrodes at a level of said high voltage power supply and a voltage hold circuit for holding levels of said electrodes at a level of said low voltage power supply.

9. A circuit for driving a display device according to claim 3, wherein said electrodes of said plurality of display elements are address electrodes of an AC type plasma display.

10. A display apparatus having a display device which has a plurality electrodes for display elements serving as a capacitive load, in which switches are inserted between an energy recovery circuit and said electrodes, and a driving circuit for driving said display, said driving circuit comprising:

a charging supply source;

a first series circuit including a first switch, a first diode and a first inductor, said first series circuit being connected to said charging supply source, and being connected at an output terminal thereof, to a first number of said electrodes through a corresponding number of first unidirectional switches such that, when at least one of said first number of electrodes is charged, said first switch, said first diode and said first unidirectional switches are made conductive; and

a second series circuits including a second switch, a second diode and a second inductor, said second series circuit being connected to said charging supply source, and being connected at an output terminal thereof, to a second number of said electrodes through a corresponding number of second unidirectional switches such that, when at least one of said second number of electrodes is discharged, said second switch, said second diode and said second unidirectional switches are made conductive, wherein

said first and second inductors are distinct from one another.

11. A display apparatus according to claim 10, wherein

an output terminal of said first inductor is connected with a first switching circuit for holding said output terminal of said first inductor at a level of a high voltage power supply, and

an output terminal of said second inductor is connected with a second switching circuit for holding said output terminal of said second inductor at a level of a low voltage power supply.

12. A display apparatus according to claim 10, wherein each of said first and said second unidirectional switches comprises a series circuit having a diode and a FET.

13. A display apparatus according to claim 10, wherein each of said first and said second unidirectional switches comprises a bipolar transistor.

14. A display apparatus according to claim 10, comprising

a plurality of said first series circuits, each of which includes a first switch, a first diode, and a first inductor, are connected in parallel, inductance values of said plurality of first inductors forming a binary system, and

a plurality of said second series circuits, each of which includes a second switch, a second diode, and a second inductor, are connected in parallel, inductance values of said plurality of second inductors forming a binary system.

15. A display apparatus according to claim 10, further comprising

a first voltage hold circuit connected to each of said electrodes, said first voltage hold circuit arranged to hold said each of said electrodes at a high voltage power supply level;

and

a second voltage hold circuit connected to each of said electrodes, said second voltage hold circuit arranged to hold said each of said electrodes at a low voltage power supply level.

16. A display apparatus according to claim 10, wherein said electrodes of said plurality of display elements are address electrodes of an AC type plasma display.

17. A driving circuit for a display device, in which energy is supplied to a plurality of electrodes serving as capacitive loads through a first group of switches and recovered from said plurality of electrodes through a second group of switches, respectively, said driving circuit comprising:

said first group of switches each coupled to corresponding one of said plurality of electrodes;

said second group of switches each coupled to corresponding one of said plurality of electrodes;

a first path including a first inductance, said first path having a first end coupled to a charge supplying source and a second end coupled to said plurality of electrodes though said first group of switches; and

a second path including a second inductance, said second path having a first end coupled to said charge supplying source and a second end coupled to said plurality of electrodes though said second group of switches, wherein

current for charging each of said plurality of electrodes is arranged to flow from said charge supplying source through said first path and said corresponding one of said first group of switches, and

current for discharging each of said plurality of electrodes is arranged to flow from said each of said plurality of electrodes to said charge supplying source through said second path and said corresponding one of said second group of switches, and wherein

charging a first number of said plurality of electrodes and discharging a second number of said plurality of electrodes are effected at substantially a same time.

18. A driving circuit for a display device according to claim 17, further comprising

means for detecting a first number of electrodes to be charged and a second number of electrodes to be discharged at substantially a same time;

and

means for controlling a value of said inductance in each of said first and second paths in accordance with the detected first and second numbers.

19. A driving circuit for a display device according to claim 17, wherein each of said first and second groups of switches comprise unidirectional switches.

20. A display apparatus comprising:

a charge supplying source having a first charging terminal;

a first series circuit comprising a first switch, a first diode and a first inductor arranged in series, said first switch being connected to said first terminal, and said first inductor being connected to a first output terminal, wherein said first diode is arranged to allow current to flow in direction from said first switch to said first inductor;

a second series circuit comprising a second switch, a second diode and a second inductor arranged in series, said second switch being connected to said first charging terminal, and said second inductor being connected to a second output terminal, wherein said second diode is arranged to allow a current to flow in a direction from said second inductor to said second switch, said first and second inductors being distinct from one another;

a plurality of display elements, each of said plurality of display elements having a first electrode connected to corresponding first and second unidirectional switches, said first and second unidirectional switches being connected in series between said first output terminal and said second output terminal;

said first unidirectional switch having a first end connected to said first output terminal and a second end connected to said first electrode and also to a first end of said second unidirectional switch, said first unidirectional switch being arranged to selectively permit a current to flow between said first output terminal and said corresponding display element; and

said second unidirectional switch being connected at its first end to said first electrode and having a second end connected to said second output terminal, said second unidirectional switch being arranged to selectively permit a current to flow between its corresponding display element and said second output terminal.

21. The display apparatus of claim 20, wherein each of said first and second unidirectional switches comprise one of:

a bipolar transistor, and a field-effect transistor connected in series with a diode.

22. The display apparatus of claim 20, further comprising:

a first switching circuit connected to said first output terminal, said first switching circuit arranged to maintain said first output terminal at a high voltage level; and

a second switching circuit connected to said second output terminal, said second switching circuit arranged to maintain said second output terminal at a low voltage level.

23. The display apparatus of claim 20, further comprising:

a first voltage hold circuit connected to said first electrode, said first voltage hold circuit arranged to selectively maintain a voltage of said first electrode at a high voltage level;

a second voltage hold circuit also connected to said first electrode, said second voltage hold circuit arranged to selectively maintain a voltage of said first electrode at a low voltage level.

24. The display apparatus of claim 20 comprising:

a plurality of said first series circuits, each of which is connected between said first charging terminal and said first output terminal; and

a plurality of said second series circuits, each of which is connected between said first charging terminal and said second output terminal.

25. The display apparatus of claim 24, further comprising:

a first switching circuit connected to said first output terminal, said first switching circuit arranged to maintain said first output terminal at a high voltage level; and

a second switching circuit connected to said second output terminal, said second switching circuit arranged to maintain said second output terminal at a low voltage level.