Driver for flat display panel

• US 5,786,794 A
• Filed: 05/17/1995
• Issued: 07/28/1998
• Est. Priority Date: 12/10/1993
• Status: Expired due to Term

• Current Assignee: Hitachi Maxell Limited (Maxell, Ltd.)
• Original Assignee: Fujitsu Limited
• Inventors: Kishi, Tomokatsu, Otsuka, Akira, Kameyama, Shigeki, Yoshikawa, Kazuo, Hirose, Tadatsugu
• Primary Examiner(s): BRIER, JEFFERY A
• Application Number:
  US08/443,038
• Time in Patent Office: 1,168 Days
• Field of Search: 345/60, 345/76, 345/208, 315/169.3, 315/169.4
• US Class Current: 345/60
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 3/296 Driving circuits for producing the waveforms applied to the driving electrodes
• CPC Class Codes: G09G 3/2965 using inductors for energy recovery
• CPC Class Codes: G09G 3/298 using surface discharge panels

Abstract

A flat panel display has a low withstand voltage and performs high speed line sequential scanning and recovers power. An AC type panel display has electrodes arranged in a matrix form, a push-pull type driver circuit, having first and second transistors, provided for each pair of plural pairs, of power supply lines connected to a driver circuit for driving a plurality of display electrodes to be scanned and a power supply which supplies a defined voltage to one of the respective power supply lines of each pair connected to the corresponding driver circuit, and a leakage control switch which leaks the defined voltage applied to the power supply line.

Claims

1. A driver for a panel display system comprising n scan electrodes which are independent of each other, said driver comprising:

n driver circuits, respectively connected to said n scan electrodes;

a power supply for supplying a voltage to each of said n driver circuits; and

a leakage current control circuit which leaks current caused by said voltage applied to each of said n driver circuits.

2. A driver for a panel display system according to claim 1, said voltage comprising a first voltage and a second voltage and wherein said power supply further comprises:

a first power supply circuit supplying the first voltage to the n driver circuits in order to write display data; and

a second power supply circuit supplying the second voltage to the n driver circuits in order to produce discharges, based on said display data.

3. A driver for a panel display system according to claim 1, wherein each of said n driver circuits is a push-pull type driver circuit.

4. A driver for a panel display system according to claim 1, wherein said panel display system further comprises:

m address electrodes each crossing said n scan electrodes and the crossings of the n scan electrodes and the m address electrodes defining m×

n cells between two substrates; and

the m×

n cells selectively generating discharge emissions when predetermined voltages are applied between the respective n scan electrodes and m address electrodes.

5. A driver for a panel display system according to claim 4, wherein said panel display system further comprises common electrodes connected to each other and positioned in parallel to the n scan electrodes and said m address electrodes being provided on one of the two substrates and said n scan electrodes and said common electrodes being provided on the other of the two substrates.

6. A driver for a panel display system according to claim 2, wherein said first power supply circuit comprises a first voltage generator generating a higher potential power supply voltage and a second voltage generator generating a lower potential power supply voltage, said first voltage generator being connected to a first power supply line connected to said n driver circuits and said second voltage generator being connected to a second power supply line connected to said n driver circuits.

7. A driver for a panel display system according to claim 1, wherein said n driver circuits are connected through a first power supply line and a second power supply line to said power supply, and wherein said leakage current control circuit is connected to the first power supply line.

8. A driver for a panel display system according to claim 2, wherein said second power supply circuit comprises a first voltage generator generating a lower potential power supply voltage and a second voltage generator generating a higher potential power supply voltage, said first voltage generator being connected to a first power supply line connected to said n driver circuits and said second voltage generator being connected to a second power supply line connected to said n driver circuits.

9. A driver for a panel display system according to claim 1, further comprising a power recovery circuit, said n driver circuits being connected to said power recovery circuit.

10. A driver for a panel display system according to claim 9, said power recovery circuit comprising a coil functioning as a series resonant circuit together with a panel capacitor, and said n scan electrodes providing one of two conductors of the panel capacitor.

11. A driver for a panel display system according to claim 6, wherein said first and second voltage generators are individually provided with respective switches for applying predetermined voltages to the n driver circuits in response to control signals applied thereto.

12. A driver for a panel display system according to claim 11, further comprising a diode connected between the first voltage generator and the first power supply line.

13. A driver for a panel display system according to claim 8, wherein said first and second voltage generators are individually provided with respective switches for applying predetermined voltages to the first and second power supply lines, respectively, in response to control signals applied thereto.

14. A driver for a panel display system according to claim 13, wherein said second power supply circuit further comprises diodes connected in parallel with said switches.

15. A driver for a panel display system according to claim 7, further comprising a resistor, connected between said leakage current control circuit and said first power supply line, which prolongs a transition time of a trailing edge of a waveform of said power supply.

16. A driver for a panel display system according to claim 8, wherein said first voltage generator of said second power supply circuit concurrently functions as said leakage current control circuit.

17. A driver for a panel display system according to claim 10, wherein said coil comprises a first coil functioning with the panel capacitor as a first series resonance circuit and a second coil functioning with the panel capacitor as a second series resonant circuit, the first and second coils being connected to a first power supply line and a second power supply line, respectively, and the first and the second power supply lines being connected between the power supply and the n driver circuits for supplying the voltage.

18. A driver for a panel display system according to claim 17, wherein said first and second coils have respective, different inductance values.

19. A driver for a panel display system according to claim 3, wherein said push-pull type driver circuit comprises a plurality of transistors and a plurality of diodes, each diode connected in parallel to a respective one of the transistors.

20. A driver for a panel display system according to claim 12, further comprising a resistor connected between the first voltage generator and said diode.

21. A driver for a panel display system according to claim 1, wherein said power supply and said leakage current control circuit are connected to said n driver circuits in common.

22. A driving method for a panel display system comprising a plurality of driver circuits, individually and respectively connected to a plurality of scan electrodes which are independent of each other, and a power supply line, connected in common to the plurality of driver circuits for applying a predetermined voltage to the plurality of driver circuits, comprising the steps of:

applying the predetermined voltage to the power supply line; and

leaking current, caused by the predetermined voltage applied to the power supply line.

23. A driving method for a panel display system according to claim 22, further comprising the steps of:

successively scanning said scan electrodes in a scan period to thereby write display data; and

effecting and sustaining a display based on the written display data in a sustain period after the scan period, wherein said applying step is executed in the scan period and said leaking step is executed at the end of the scan period.

24. A driving method for a panel display system according to claim 23, wherein a potential difference between both ends of the driver circuits is reduced to zero in the leaking step, and thereafter said sustain period starts.

25. A driver for a panel display system comprising n scan electrodes which are independent of each other, said driver comprising:

a plurality of n driver circuits provided between a first power supply line and a second power supply line and connected to the n scan electrodes;

a first power supply circuit supplying a first electric power to the first and second power supply lines, said first electric power writing display data; and

a second power supply circuit supplying a second electric power to the first and second power supply lines, said second electric power producing discharges based on the display data.

26. A driver for a panel display system according to claim 25, wherein:

said first power supply circuit comprises;

a first voltage generator, connected to the first power supply line, generating a higher potential power supply voltage, and

a second voltage generator, connected to the second power supply line, generating a lower potential power supply voltage; and

said second power supply circuit comprises;

a third voltage generator, connected to the first power supply line, generating a lower potential power supply voltage, and

a fourth voltage generator, connected to the second power supply line, generating a higher potential power supply voltage.

27. A driver for a panel display system according to claim 25, wherein each of the n driver circuits comprises a push-pull driver circuit of a plurality of transistors serially connected between the first and the second power supply lines.

28. A driver for a panel display system according to claim 27, wherein each push-pull driver circuit further comprises a plurality of diodes, each diode connected in parallel to a respective transistor of the plurality of serially connected transistors.

29. A driver for a panel display system according to claim 25, wherein each of said first, second, third and fourth voltage generators further comprises respective switches individually associated therewith and applying predetermined voltages to the first and second power supply lines connected thereto in response to control signals applied thereto.

30. A driver for a panel display system according to claim 25, wherein said first and second power supply lines are connected in common to the n driver circuits.

31. A driver circuit for a panel display system comprising a pair of electrodes defining a panel capacitance therebetween, the driver circuit being coupled to, and selectively charging and discharging, the electrodes to drive the panel display system, the driver circuit comprising:

a first path having a first end connected to a selected electrode of the pair of electrodes and a second end connected to a node and comprising, in succession, a first coil, a first diode having an anode thereof oriented toward the selected electrode, and a first switch, the first path providing a discharge path for discharging the electrodes therethrough;

a second path having a first end connected to the second electrode of the pair of electrodes and a second end connected to the node and comprising, in succession, a second coil, a second diode having a cathode thereof oriented toward the selected electrode, and a second switch having a first end connected to the selected electrode and a second end connected to the node, the second path providing a charging path for charging the electrodes therethrough;

a power storage element connected to the node;

a first clamp circuit, connected to the first path at a connection therein between the selected electrode and the first coil and clamping a potential of the first path to a first, low potential power source; and

a second clamp circuit, connected to the second path at a connection therein between the selected electrode and the second coil and clamping a potential of the second path to a second, high potential power source, the high potential being higher than the low potential.

32. A driver circuit for a panel display system according to claim 31, further comprising:

a third diode having a cathode thereof connected to the first path at a connection therein between the first coil and the first diode and having an anode thereof connected to the first, low potential power source; and

a fourth diode having an anode thereof connected to the second path at a connection therein between the second coil and the second diode and having a cathode thereof connected to the second, high potential power source.

33. A driver circuit for a panel display system according to claim 32, further comprising:

a fifth diode having a cathode thereof connected to the first path at a connection therein between the first switch and the first diode, and having a cathode thereof connected to the second, high potential power source; and

a sixth diode having a cathode thereof connected to the second path at a connection therein between the second switch and the second diode, and having an anode thereof connected to the first, low potential power source.

34. A driver circuit for a panel display system according to claim 31, further comprising:

a seventh diode having a cathode thereof connected to the first path at a connection therein between the selected electrode and the first clamp circuit and having an anode thereof oriented toward the selected electrode; and

an eighth diode having a cathode thereof connected to the second path at a connection therein between the second electrode and the second clamp circuit and having a cathode thereof oriented toward the selected electrode.

35. A driver for a panel display system according to claim 31, wherein said first and second coils have respective, different inductance values.

36. A panel display system comprising a pair of electrodes having a panel capacitance and generating discharge emissions therebetween in response to a predetermined voltage applied therebetween and a driver circuit coupled to the electrodes for driving the discharge emissions, said driver circuit comprising:

a first path having a first end connected to a selected electrode of the pair of electrodes and a second end connected to a node and comprising, in succession, a first coil, a first diode having an anode thereof oriented toward the selected electrode and a first switch, the first path providing a discharging path for discharging the electrodes therethrough;

a second path having a first end connected to the selected electrode and a second end connected to the node and comprising, in succession, a second coil, a second diode having a cathode thereof oriented toward the selected electrode and a second switch, the second path providing a charging path for charging the electrodes therethrough;

a power storage element connected to the node;

a first clamp circuit, connected to the first path at a connection therein between the selected electrode and the first coil and clamping a potential of the first path to a low potential; and

a second clamp circuit, connected to the second path at a connection therein between the selected electrode and the second coil and clamping a potential of the second path to a high potential, the high potential being higher than the low potential.

37. A method of driving a panel display system comprising a pair of electrodes having a panel capacitance and generating discharge emissions therebetween in response to a predetermined voltage applied therebetween, the method comprising the steps of:

i) discharging the panel capacitance of the pair of electrodes through a discharging path comprising, in sequence, a first coil and a first diode;

ii) clamping potentials of the electrodes after step i);

iii) reducing a potential difference between opposite end terminals of the first coil to zero, concurrently with step ii);

iv) charging the panel capacitance of the electrodes through a charging path comprising, in sequence, a second diode and a second coil;

v) clamping potentials of the electrodes after step iv); and

vi) reducing a potential difference between opposite end terminals of the second coil to zero concurrently with step v).

38. A method of driving a panel display system according to claim 37, wherein:

step iii) is performed through a conductive path comprising a third diode having a cathode thereof connected to a connection in the discharge path between the first coil and the first diode and having an anode thereof connected to the first, low potential power source; and

step vi) is performed through a conductive path comprising a fourth diode having an anode thereof connected to a connection in the charging path between the second coil and the second diode and having a cathode thereof connected to the second, high potential power source.

39. A method of driving a panel display system according to claim 37, wherein step iv) further comprises a substep of applying a voltage which substantially corresponds to one half of a voltage level to which the panel capacitance is charged.

40. A method of driving a panel display system according to claim 37, wherein step i) further comprises the substep of applying a voltage which substantially corresponds to one half of a voltage level to which the panel capacitance is charged.

41. A method of driving a panel display system according to claim 37, wherein:

the first coil and the panel capacitance define a first serial resonant circuit and the potentials clamped in step ii) correspond to a peak value of a resonant voltage of the first serial resonant circuit; and

the second coil and the panel capacitance define a second serial resonant circuit and the potentials clamped in step v) correspond to a peak value of a resonant voltage of the second serial resonant circuit.