Controller of plasma display panel and method of controlling the same

• US 5,663,741 A
• Filed: 03/18/1996
• Issued: 09/02/1997
• Est. Priority Date: 04/30/1993
• Status: Expired due to Term

• Current Assignee: Hitachi Maxell Limited (Hitachi, Ltd.)
• Original Assignee: Fujitsu Limited
• Inventors: Kanazawa, Yoshikazu
• Primary Examiner(s): SARAS, STEVEN J
• Application Number:
  US08/618,270
• Time in Patent Office: 533 Days
• Field of Search: 345/60-63, 345/66-71, 345/204, 345/208-210, 345/214, 315/169.4, 313/581, 313/585
• US Class Current: 345/66
• CPC Class Codes: G09G 2310/066 Waveforms comprising a gently increasing or decreasing portion, e.g. ramp
• CPC Class Codes: G09G 2320/0228 Increasing the driving margin in plasma displays
• CPC Class Codes: G09G 3/2927 Details of initialising
• CPC Class Codes: G09G 3/2932 Addressed by writing selected cells that are in an OFF state
• CPC Class Codes: G09G 3/296 Driving circuits for producing the waveforms applied to the driving electrodes
• CPC Class Codes: G09G 3/298 using surface discharge panels

Abstract

A controller for a plasma display having a first drive unit to apply voltage to a sustain electrode of a display unit having a memory function and a second drive unit to apply voltage to an address electrode of the display unit. The first drive unit has a discharge control unit to control the discharge wave form of the voltage applied to the sustain electrode of the display unit. The discharge control unit has a delay element and a switching element connected in series between sustain electrodes. Alternatively, the control unit has a delay element and a switching element connected in series between the sustain electrodes and a constant voltage discrimination element connected in parallel with the delay element.

Claims

1. A method of controlling a plasma display which has a plurality of display cells defined by a plurality of electrode pairs disposed between a first panel and a second panel facing each other, and having a gas enclosed between the first and second panels, each of said plurality of display cells having first and second electrodes, wherein the gas causes a discharge by applying a voltage across corresponding ones of the first and the second electrodes, said method comprising the steps of:

applying an erase signal to one of said plurality of display cells to control an amount of wall charges accumulated in the one display cell, wherein a voltage of said erase signal is varied with time;

effecting an addressing discharge to select the one display cell by superimposing an address voltage over the wall charges, after applying the erase signal to the one of said plurality of display cells; and

conducting a sustain discharge for display by causing a discharge on the selected one display cell, after effecting the addressing discharge to select the one display cell.

2. A plasma display device, comprising:

a display panel for holding a discharge gas between first and second insulator substrates, the display panel having a plurality of display cells defined by pairs of first and second electrodes parallely disposed relative to each other on the first insulator substrate and a plurality of third electrodes disposed on the second insulator substrate and intersecting the first and second electrodes of respective said pairs; and

a control circuit for controlling a discharge of each of said plurality of display cells, said control circuit further comprising

a first driver to apply a write pulse and a sustain pulse across the first and the second electrodes of one of said plurality of display cells to cause a writing discharge and a sustaining discharge on the discharge gas, the writing discharge producing wall charges on said first and second insulator substrates,

a discharge circuit to control an amount of the wall charges accumulated on said first insulator substrate,

a switching element to control a discharge timing of said discharge circuit, and

a second driver to apply an address pulse to the third electrode of the one display cell, said address pulse being superimposed over a voltage produced by said wall charges accumulated on said first and second insulator substrates to form a writing voltage;

wherein said switching element drives said discharge circuit at a timing after said write and sustain pulses have been applied to the one display cell and before said address pulse is applied to the one display cell, to control the amount of wall charges accumulated on said first insulator substrate.

3. The plasma display device according to claim 2, wherein said discharge circuit comprises a resistor element having one end connected between said first driver and the first insulator substrate and a second end connected to a ground potential through said switching circuit.

4. The plasma display device according to claim 3, wherein said discharge circuit further comprises a constant voltage discrimination element connect in parallel with said resistor element, to regulate a current flowing through said resistor element.

5. The plasma display device according to claim 4, wherein said constant voltage discrimination element is a zener diode.

6. A method of controlling a plasma display device which has a display panel for holding a discharge gas between first and second insulator substrates, the display panel having a plurality of display cells defined by pairs of first and second electrodes parallely disposed relative to each other on the first insulator substrate and a plurality of third electrodes disposed on the second insulator substrate and intersecting the first and second electrodes of respective said pairs, said control circuit for controlling a discharge of each of said plurality of display cells, said control method comprising the steps of:

applying a write pulse across the first and second electrodes of one of said plurality of display cells to cause a writing discharge of said discharge gas and to accumulate wall charges on said first and second insulator substrates;

applying an erase pulse across the first and second electrodes of the one display cell, subsequent to said write pulse applying step, to regulate an amount of the wall charges accumulated on said first insulator substrate so as to leave a given amount of the wall charges which will cause an addressing discharge when an address pulse is applied across either one of the first and second electrode, and third electrodes of the one display cell, wherein a voltage value of said erase pulse is changed with time;

applying said address pulse across either one of the first and second electrode, and third electrodes of the one display cell to cause the addressing discharge on the one display cell subsequent to said erase pulse applying step; and

applying a sustain pulse across the first and second electrodes of the one display cell to cause a sustaining charge on the one display cell, subsequent to said address pulse applying step.

7. The method according to claim 6, wherein said sustain pulse has an opposite polarity from that of said write pulse, and said applying step is performed between said write pulse applying step and said erase pulse applying step.

8. The control method according to claim 6, wherein said erase pulse has a same polarity as that of the write pulse and increases in voltage from 0 volts to a maximum value within a time interval between several microseconds and several hundred microseconds.

9. The control method according to claim 8, further comprising a step of applying a sustain pulse across the first and second electrodes of the one display cell to cause a sustaining discharge of said discharge gas, said sustain pulse having an opposite polarity from that of said write pulse, wherein said applying step is performed between said write pulse applying step and said erase pulse applying step and said maximum value of said erase pulse is a same value as an absolute value of a voltage of said sustain pulse.

10. The control method according to claim 6, wherein said erase pulse applying step comprises varying said erase pulse in voltage from 0 volts to a maximum value at a uniform rate with respect to time.

11. The control method according to claim 6, wherein said erase pulse applying step comprises varying said erase pulse in voltage from 0 volts to a maximum value nonlinearly with respect to time.

12. The control method according to claim 6, wherein said erase pulse applying step comprises increasing said erase pulse quickly in magnitude within several nanoseconds to several microseconds up to approximately a minimum value for keeping a sustaining discharge on the one display cell, and thereafter, increasing said erase pulse in magnitude at a constant rate for several hundred nanoseconds to several microseconds.

13. The control method according to claim 6, wherein said erase pulse applying step comprises increasing said erase pulse quickly in magnitude within several nanoseconds to several microseconds up to approximately a minimum value for keeping a sustaining discharge on the one display cell, and thereafter increasing said erase pulse in magnitude nonlinearly up to approximately a maximum value for keeping the sustaining discharge.