Display and method for driving the same

• US 6,900,781 B1
• Filed: 11/06/2000
• Issued: 05/31/2005
• Est. Priority Date: 11/12/1999
• Status: Expired due to Term

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Mori, Mitsuhiro, Tachibana, Hiroyuki, Kasahara, Mitsuhiro, Oe, Yoshinao
• Primary Examiner(s): Tran, Henry N.
• Assistant Examiner(s): LESPERANCE, JEAN E
• Application Number:
  US09/868,914
• Time in Patent Office: 1,667 Days
• Field of Search: 345 60- 68, 345/208, 345/210, 345/211, 315/169.1, 315/169.2, 315/169.3, 315/169.4, 313585-587
• US Class Current: 345/60
• CPC Class Codes: G09G 2310/066 Waveforms comprising a gently increasing or decreasing portion, e.g. ramp
• CPC Class Codes: G09G 2320/0626 for control of overall brightness
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 2330/025 Reduction of instantaneous peaks of current
• CPC Class Codes: G09G 2330/06 Handling electromagnetic interferences [EMI], covering emitted as well as received electromagnetic radiation
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 3/294 for lighting or sustain discharge
• CPC Class Codes: G09G 3/2942 with special waveforms to increase luminous efficiency
• CPC Class Codes: G09G 3/2965 using inductors for energy recovery

Abstract

A plasma display having a discharge cell, the emission efficiency of which is improved by generating first and second discharges with one sustaining pulse. A first discharge is generated by increasing a voltage up to a maximal value through a LC resonance formed by a recovery coil and a panel capacitor. A second discharge is generated by connecting the panel capacitor to a power supply when the voltage falls a predetermined amount below the maximal value, thereby increasing the voltage to a predetermined level above the maximal value.

Claims

1. A display device for selectively discharging a plurality of discharge cells to display an image, comprising:

a display panel that includes said plurality of discharge cells;

a first driving circuit that applies a driving pulse to a selected discharge cell in said display panel to induce a first discharge; and

a second driving circuit that increases a voltage of the driving pulse, to induce a second discharge subsequently to said first discharge, after the voltage of said driving pulse is reduced by said first discharge, wherein an interval between a peak of said first discharge and a peak of said second discharge is not less than 100 ns nor more than 550 ns.

2. The display device according to claim 1, characterized in that said second driving circuit induces said second discharge while a priming effect produced by said first discharge is obtained.

3. The display device according to claim 1, characterized in that the interval between the peak of said first discharge and the peak of said second discharge is not less than 300 ns nor more than 550 ns.

4. The display device according to claim 1, characterized in that the peak intensity of said second discharge is not less than the peak intensity of said first discharge.

5. The display device according to claim 1, characterized in that

said plurality of discharge cells respectively include capacitive loads, and

said first driving circuit comprises

an inductance circuit having at least one inductance element having its one end connected to said capacitive load, and

a resonance driving circuit for outputting said driving pulse due to LC resonance by said capacitive load and said inductance element.

6. The display device according to claim 1, characterized in that said first driving circuit comprises a first capacitive element provided outside said display panel as a current supply source for said driving pulse, said first capacitive element recovering charges stored in said discharge cells.

7. The display device according to claim 1, characterized by further comprising a third driving circuit for increasing, after the voltage of the driving pulse is reduced by the second discharge, the voltage of the driving pulse, to induce third discharge subsequently to said second discharge.

8. The display device according to claim 7, characterized in that said third driving circuit repeats an operation for increasing, after the voltage of the driving pulse is reduced by the discharge, the voltage of the driving pulse, to continuously induce discharges a plurality of times subsequently to the second discharge.

9. The display device according to claim 7, characterized in that

said second driving circuit comprises

a second capacitive element provided outside said display panel as a current supply source for said driving pulse, and

a voltage source for charging said second capacitive element to a predetermined voltage.

10. The display device according to claim 7, characterized in that

said third driving circuit repeats an operation for increasing the voltage of the driving pulse after the voltage of the driving pulse is reduced by the discharge, to continuously induce discharges a plurality of times subsequently to the second discharge, and

said control circuit controls said third driving circuit such that said driving pulse is changed depending on the lighting rate detected by said detection circuit.

11. The display device according to claim 1, characterized in that said driving pulse includes a driving pulse which makes a transmission from a first potential to a second potential and takes a maximal value and a minimal value at least once during a transition from the first potential to the second potential, and further comprising

a final driving circuit that drives said driving pulse such that a transition speed from a predetermined extreme value to the second potential is lower than a transition from the first potential to an extreme value immediately aft that and a transition speed from a subsequent extreme value to another extreme value immediately after that.

12. The display device according to claim 11, wherein

said final driving circuit comprises:

a field effect transistor having one end receiving said field potential, and

a current-limiting circuit for limiting a current of a control signal inputted to the gate of said field effect transistor.

13. A display device for selectively discharging a plurality of discharge cells to display in image, comprising:

a display panel that includes said plurality of discharge cells;

a driving circuit that applies a driving pulse to a selected discharge cell in said display panel to induce a first discharge, the driving circuit increasing a voltage of the driving pulse to induce a second discharge subsequent to said first discharge;

a detection circuit that detect a lighting rate of discharge cells simultaneously turned on out of said plurality of discharge cells; and

a control circuit that controls said driving circuit such that said driving pulse is changed depending on the lighting rate detected by said detection circuit.

14. The display device according to claim 13, further comprising:

a conversion circuit that converts in order to divide one field into a plurality of sub-fields and discharge a selected discharge cell for each sub-field to make a gray scale expression, image data in the one field into image data in each sub-field,

said detection circuit comprising a sub-field lighting rate detection circuit that detects the lighting rate for each sub field,

said control circuit controlling said driving circuit such that said driving pulse is changed depending on the lighting rate for each sub-field detected by said sub-field lighting rate detection circuit.

15. The display device according to claim 14, wherein

said driving circuit applies, in the same sub-field, at least one of a first driving pulse for inducing a discharge once by applying one pulse and a second driving pulse for inducing said second discharge after inducing said first discharge, and

said control circuit controls said driving circuit so as to change a ratio of a number of times of application of said first driving pulse to a number of times of application of said second driving pulse depending on the lighting rate for each sub-field detected by said sub-field lighting rate detection circuit.

16. The display device according to claim 14, wherein

said driving circuit applies, in the same sub-field, at least one of a first driving pulse for inducing said first and second discharges at a first time interval and a second driving pulse for inducing said first and second discharges at a second time interval longer than the first time interval, and

said control circuit controls said driving circuit so as to change a ratio of a number of times of application of said first driving pulse to the number of times of application of said second driving pulse depending on the lighting rate for each sub-field detected by said sub-field lighting rate detection circuit.

17. The display device according to claim 16, wherein a period of said second driving pulse is longer than a period of said fist driving pulse.

18. The display device according to claim 16, wherein said control circuit controls said driving circuit such that a higher the lighting rate for each sub-field detected by said sub-field lighting rate detection circuit is, a higher the ratio of the number of times of application of said second driving pulse to the number of times of application of said first driving pulse becomes.

19. The display device according to claim 16, characterized in that said control circuit controls said driving circuit so as to increase the ratio of the number of times of application of said second driving pulse to the number of times of application of the second driving pulse to the number of times of application of the first driving pulse with the increase in the lighting rate when the lighting rate is increased to not less than a predetermined value.

20. The display device according to claim 13, wherein said driving circuit comprises;

a first driving circuit that increases the voltage of said driving pulse to induce said first discharge, and

a second driving circuit that increases the voltage of said driving pulse to induce said second discharge after inducing said first discharge, and

said control circuit controlling said second driving circuit such that said driving pulse is changed depending on the lighting rate detected by said detection circuit.

21. The display device according to claim 20, characterized in that said second driving circuit increases, after the voltage of said driving pulse is reduced by the first discharge, the voltage of the driving pulse, to induce said second discharge subsequently to the first discharge.

22. The display device according to claim 20, wherein said control circuit changes a timing at which said second driving circuit increases the voltage of said driving pulse depending on the lighting rate detected by said detection circuit.

23. The display device according to claim 20, wherein a higher the lighting rate detected by said detecting circuit is, a later a timing at which said second driving circuit increases the voltage of said driving pulse is.

24. The display device according to claim 20, characterized in that said control circuit controls, when the lighting rate detected by said detection circuit reaches not less than a predetermined value, said second driving circuit such that said second discharge is induced subsequently to said first discharge.

25. The display device according to claim 20, wherein said control circuit controls said second driving circuit so as to delay a timing at which the voltage of the driving pulse is increased with an increase in the lighting rate detected by said detection circuit, and advance the timing at which the voltage of said driving pulse is increased to not less than the predetermined value.

26. The display device according to claim 20, wherein said control circuit controls said second driving circuit so as to switch a timing at which the second driving circuit increases the voltage of the driving pulse when the lighting rate detected by said detection circuit reaches not less than a predetermined value and change a number of pulses composing the driving pulse applied to the selected discharge cell in the display panel such that a luminance is approximately equal before and after the switching of the timing at which the voltage of the driving pulse is increased.

27. The display device according to claim 20, characterized in that said first driving circuit comprises a first capacitive element provided outside said display panel as a current supply source for said driving pulse.

28. The display device according to claim 27, characterized in that said first capacitive element recovers charges stored in said discharge cell.

29. The display device according to claim 20, wherein

said driving circuit further comprises a third driving circuit that increases, after the voltage of said driving pulse is reduced by the second discharge, the voltage of said driving pulse, to induce a third discharge subsequently to said second discharge, and

said control circuit controls said third driving circuit such that said driving pulse is changed depending on the lighting rate detected by said detention circuit.

30. The display device according to claim 13, wherein said control circuit controls said diving circuit such that a higher the lighting rate detected by said detecting circuit is, a longer a period of said driving pulse is.

31. The display device according to claim 13, wherein said control circuit controls said driving circuit so as to switch a period of said driving pulse when the lighting rate detected by said detection circuit reaches not less than a predetermined value and change a number of pulses composing the driving pulse applied to the selected discharge cell in said display panel such that a luminance is approximately equal before and after the switching of the period of said driving pulse.

32. A display device for selectively discharging a plurality of discharge cells to display in image, comprising:

a display panel that includes said plurality of discharge cells;

a first driving circuit that applies a driving pulse to a selected discharge cell in said display panel to induce a first discharge;

a second driving circuit that increases a voltage of said driving pulse to induce a second discharge subsequent to said first discharge;

a detection circuit that detects a lighting rate of discharge cells simultaneously turned on out of said plurality of discharge cells; and

a control circuit that controls said first and second driving circuits such that said driving pulse is changed depending on the lighting rate detected by said detection circuit, wherein said plurality of discharge cells respectively include capacitive loads, and

said first driving circuit comprises;

an inductance circuit having at least one inductance element having a first end connected to said capacitive load, and

a resonance driving circuit that outputs said driving pulse due to LC resonance by said capacitive load and said inductance element.

33. The display device according to claim 32, wherein said inductance circuit includes a variable inductance circuit capable of changing an inductance value, and further comprising

an inductance control circuit that changes the inductance value of said variable inductance circuit depending on the lighting rate detected by said detection circuit.

34. A display device for selectively discharging a plurality of discharge cells to display in image, comprising:

a display panel that includes said plurality of discharge cells;

a driving circuit that applies a driving pulse to a selected discharge cell in said display panel to induce a second discharge after inducing a first discharge;

a detection circuit that detects a lighting rate of discharge cells simultaneously turned on out of said plurality of discharge cells; and

a control circuit that controls said driving circuit such that said driving pulse is changed depending on the lighting rate detected by said detection circuit, wherein said driving circuit comprises;

a first driving circuit that induces said first discharge; and

a second driving circuit that increases the voltage of said driving pulse to induce said second discharge subsequent to said first discharge, said second driving circuit comprising;

a second capacitive element provided outside said display panel as a current supply source for said driving pulse, and

a voltage source that charges said second capacitive element to a predetermined voltage.

35. The display device according to claim 34, wherein said voltage source includes a variable voltage source that changes its output voltage, and further comprising

a voltage control circuit that controls the output voltage of said variable voltage source such that a higher the lighting rate detected by said detection circuit is, a lower a charging voltage for said second capacitive element becomes.

36. The display device according to claim 34, wherein said voltage source includes a variable voltage source that changes its output voltage, and further comprising

a potential detection circuit that detects a potential of said driving pulse changed by said first discharge, and

a voltage control circuit that controls an output voltage of said variable voltage source such that a larger an amount of change in the potential detected by said potential detection circuit is, a lower a charging voltage for said second capacitive element becomes.

37. A method of selectively discharging a plurality of discharge cells to display an image, comprising:

applying a driving pulse to a selected discharge cell to induce a first discharge; and

increasing, after a voltage of the driving pulse is reduced by the first discharge, the voltage of the driving pulse, to induce a second discharge subsequently to the first discharge, wherein an interval between a peak of the first discharge and a peak of the second discharge is not less than 100 ns nor more than 550 ns.

38. The method of driving a display deice according to claim 37, further comprising:

increasing, after the voltage of said driving pulse is reduced by the second discharge, the voltage of the driving pulse, to induce a third discharge subsequently to the second discharge.

39. The method of driving a display deice according to claim 38, wherein inducing the third discharge further comprises repeating an operation for increasing, after the voltage of the driving pulse is reduced by the discharge, the voltage of the driving pulse, to continuously induce discharges a plurality of times subsequently to the second discharge.

40. The method of driving a display device according to claim 37, characterized in that said driving pulse includes a driving pulse which makes a transition from a first potential to a second potential and takes a maximal value and a minimal value at least once during a transition from the first potential to the second potential, and further comprising

driving the driving pulse such that a transition speed from a predetermined extreme value to the second potential is lower than a transition speed from the first potential to an extreme value immediately after that and a transition speed from a subsequent extreme value to another extreme value immediately after that.

41. A method of selectivity discharging a plurality of discharge cells to display an image, comprising:

detecting a lighting rate of discharge cells which are simultaneously turned on out of said plurality of discharge cells; and

applying a driving pulse to a selected discharge cell to induce first discharge; and

increasing a voltage of the driving pulse to induce a second discharge subsequent to the first discharge.

42. The method of driving a display device according to claim 41, wherein

inducing the first and second discharges comprises:

increasing the voltage of the driving pulse applied to the selected discharge cell, to induce the first discharge, and

increasing the voltage of the driving pulse to induce the second discharge after inducing the first discharge, and changing the driving pulse in accordance with the detected lighting rate.

43. The method of driving a display deice according to claim 42, wherein inducing the second discharge comprises increasing, after the voltage of the driving pulse is reduced by the first discharge, the voltage of the driving pulse, to induce the second discharge subsequently to the first discharge, and changing the timing at which the voltage of the driving pulse is increased in accordance with the detected lighting rate.

44. A display device for selectively discharging a plurality of discharge cells to display an image, comprising:

a display panel that includes said plurality of discharge cells;

a first driving circuit that applies a driving pulse to a selected discharge cell in said display panel to induce a first discharge; and

a second driving circuit that increases a voltage of the driving pulse, to induce a second discharge subsequently to said first discharge, wherein said plurality of discharge cells respectively include capacitive loads, and said first driving circuit comprises an inductance circuit that has at least one inductance element having a first end connected to a capacitive load, and a resonance driving circuit that drives said driving pulse due to LC resonance by said capacitive load and said inductance element.

45. A display device for selectively discharging a plurality of discharge cells to display an image, comprising:

a display panel that includes said plurality of discharge cells;

a first driving circuit that applies a driving pulse to a selected discharge cell in said display panel to induce a first discharge; and

a second driving circuit that increases a voltage of the driving pulse, to induce a second discharge subsequently to said first discharge, wherein said first driving circuit comprises a first capacitive element provided outside said display panel as a current supply source for said driving pulse, said first capacitive element recovering charges stored in said discharge cells.

46. A display device for selectively discharging a plurality of discharge cells to display an image, comprising:

a display panel that includes said plurality of discharge cells;

a first driving circuit that applies a driving pulse to a selected discharge cell in said display panel to induce a first discharge; and

a second driving circuit that increases a voltage of the driving pulse, to induce a second discharge subsequently to said first discharge, wherein said first driving circuit comprises a first capacitive element provided outside said display panel as a current supply source for said driving pulse, and a voltage source charges said second capacitive element to a predetermined voltage.