Drive unit for light-emitting display panel, and electronic device mounted therewith

• US 20050212408A1
• Filed: 03/24/2005
• Published: 09/29/2005
• Est. Priority Date: 03/29/2004
• Status: Abandoned Application

• Current Assignee: Tohoku Pioneer Company Limited (Pioneer Corporation)
• Original Assignee: Tohoku Pioneer Company Limited (Pioneer Corporation)
• Inventors: Ohshita, Isamu, Yoshida, Takayoshi
• Application Number:
  US11/088,974
• Publication Number:
  US 20050212408A1
• Time in Patent Office: Days
• US Class Current: 313/503
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2310/0256 with the purpose of reversing the voltage across a light emitting or modulating element within a pixel
• CPC Class Codes: G09G 2320/043 Preventing or counteracting the effects of ageing
• CPC Class Codes: G09G 2330/02 Details of power systems and of start or stop of display operation
• CPC Class Codes: G09G 3/3216 using a passive matrix
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element
• CPC Class Codes: G09G 3/3283 in which the data driver supplies a variable data current for setting the current through, or the voltage across, the light-emitting elements
• CPC Class Codes: G09G 3/3291 in which the data driver supplies a variable data voltage for setting the current through, or the voltage across, the light-emitting elements

Abstract

A voltage from a constant voltage source for a voltage of V1 is configured to be supplied to an anode line drive circuit 2. Then, a current larger than that, by which the current image is displayed, is supplied from the constant voltage source for a voltage of V1 to EL elements E11 through Enm by connecting all of drive switches Sa1 through Sam in the anode line drive circuit 2 to the side of the constant voltage source for a voltage of V1, and by connecting all of scanning switches Sk1 through Skm in a cathode-line scanning circuit 3 to the side of the ground potential GND. A leak phenomenon generated in an organic EL element can be rehabilitated, or generation of the leak phenomenon can be prevented by such a large current supplied on a regular basis.

Claims

1. A drive unit for a light-emitting display panel with a pixel configuration including at least a plurality of scanning lines and a plurality of data lines which are intersecting with each other, and self-light-emitting elements with a diode characteristic, each of which is arranged at each intersecting point of each of the scanning lines and each of the data lines, having a configuration in which

a first current can be supplied from the side of the anode terminal in each self-light-emitting element concerned, and a second current larger than the first current can be supplied to the self-light-emitting element in order to drive the self-light-emitting element for lighting.

2. The drive unit for a light-emitting display panel according to claim 1, having a configuration in which

the first current is supplied from a constant current source through a switching unit, and the second current is supplied from another constant current source through another switching unit.

3. The drive unit for a light-emitting display panel according to claim 1, having a configuration in which

the first and second currents are supplied from one constant current source which can change the value of a current.

4. The drive unit for a light-emitting display panel according to claim 1, having a configuration in which

the first current is supplied from a constant current source, and the second current is supplied from a constant voltage source.

5. The drive unit for a light-emitting display panel according to claim 1, wherein

a power supply by which a reverse-bias voltage can be applied to the self-light-emitting element is further provided at either of the side of the anode terminal, or that of the cathode terminal or both of the sides of the self-light-emitting element.

6. The drive unit for a light-emitting display panel according to claim 1, having a configuration in which

the self-light-emitting element is connected in series to a light-emitting drive transistor to form a pixel, and the first current, or the second current can be selectively supplied to the self-light-emitting element according to different levels of gate potential applied to the light-emitting drive transistor.

7. The drive unit for a light-emitting display panel according to claim 1, wherein

the self-light-emitting element is connected in series to a light-emitting drive transistor to form a pixel, and a switching transistor including first and second controlled terminals which open and close between the terminals according to a switching signal input to a control terminal is provided,

the first controlled terminal of the switching transistor is connected to a connecting point of the self-light-emitting element and a light-emitting drive transistor, and a power supply to supply the second current is connected to the second controlled terminal of the switching transistor, and

the first current is supplied to the self-light-emitting element in the OFF period of the switching transistor, and the second current is supplied to the self-light-emitting element in the ON period of the switching transistor.

8. The drive unit for a light-emitting display panel according to claim 7, wherein

a power supply to supply the second current in the forward direction to the self-light-emitting element, and a power supply to supply a reverse-bias voltage to the self-light-emitting element can be selectively connected through switching to the second controlled terminal of the switching transistor.

9. The drive unit for a light-emitting display panel according to claim 1, wherein

the self-light-emitting element is connected in series to a light-emitting drive transistor to form a pixel, and a switching transistor including first and second controlled terminals which open and close between the terminals according to a switching signal input to a control terminal is provided,

the first and second controlled terminals of the switching transistor are connected between the source and the drain of the light-emitting drive transistor, and

the first current is supplied to the self-light-emitting element during the OFF period of the switching transistor, and the second current is supplied to the self-light-emitting element during the ON period of the switching transistor

10. The drive unit for a light-emitting display panel according to claim 9, wherein

a power supply to supply the second current in the forward direction to the self-light-emitting element, and a power supply to supply a reverse-bias voltage to the self-light-emitting element can be selectively connected through switching to the side of the cathode of the self-light-emitting element during the ON period of the switching transistor.

11. The drive unit for a light-emitting display panel according to claim 9, wherein

a power supply to supply the second current in the forward direction to the self-light-emitting element, and a power supply to supply a reverse-bias voltage to the self-light-emitting element can be selectively connected through switching to the side of the source of the light-emitting drive element, and the former power supply and the latter power supply can be selectively connected through switching to the side of the cathode of the self-light-emitting element during the ON period of the switching transistor.

16. The drive unit for a light-emitting display panel according to claim 1, wherein

a first self-repairing mode in which a current flowing in each of the self-light-emitting elements is a second current is provided.

17. The drive unit for a light-emitting display panel according to claim 16, having a configuration in which

all of the self-light-emitting elements arranged on the light-emitting display panel are controlled for lighting in the first self-repairing mode.

21. The drive unit for a light-emitting display panel according to claim 1 or claim 12, wherein

each of the self-light-emitting element is an organic EL element using an organic compound for a light-emitting layer.

22. An electronic device mounted with the light-emitting display panel and the drive unit therefor according to any one of claim 16, claim 18, claim 20, wherein

a timer is mounted in the electronic device, and any one of the first self-repairing mode, the second self-repairing mode, the third self-repairing mode is executed according to the accumulated time of the timer.

23. The electronic device, which uses a rechargeable battery, according to claim 22, wherein

Any one of the first self-repairing mode, the second self-repairing mode, the third self-repairing mode is executed during the charging operation of the battery.

24. The electronic device, in which visibility of the surface of the display panel is configured to be lost by closing the light-emitting display panel, according to claim 22, wherein any one of the first self-repairing mode, the second self-repairing mode, the third self-repairing mode is executed in a state in which the light-emitting display panel is closed.

25. The electronic device, which is operated by a battery, according to claim 22, having a configuration in which

execution of any one of the first self-repairing mode, the second self-repairing mode, the third self-repairing mode is prohibited when the amount of remaining power in the battery is detected to be equal to or lower than a predetermined one.

12. A drive unit for a light-emitting display panel which has a pixel configuration including at least a plurality of scanning lines and a plurality of data lines which are intersecting with each other, and self-light-emitting elements with a diode characteristic, each of which is arranged at each intersecting point of each of the scanning lines and each of the data lines, and has a configuration in which, in order to drive the self-light-emitting element for lighting, a reverse-bias voltage in the backward direction, which is opposed to the forward direction, can be applied to the self-light-emitting element, wherein

the reverse-bias voltage has a first voltage and a second voltage larger than the first voltage.

13. The drive unit for a light-emitting display panel according to claim 12, having a configuration in which

a reverse-bias voltage by the first voltage, and a reverse-bias voltage by the second voltage can be applied to each of self-sight-emitting elements by switching between constant voltage sources at the side of the cathode of each of the self-light-emitting elements.

14. The drive unit for a light-emitting display panel according to claim 12, having a configuration in which

a reverse-bias voltage by the first voltage, and a reverse-bias voltage by the second voltage can be selectively applied to each of self-sight-emitting elements by switching between constant voltage sources at the side of the anode of each of the self-light-emitting elements.

15. The drive unit for a light-emitting display panel according to claim 12, having a configuration in which

a reverse-bias voltage by the first voltage is applied to each of the self-light-emitting elements, and, simultaneously, a reverse-bias voltage by the second voltage is applied to each of the elements every time the reverse voltage by the first voltage is applied to each of the elements a predetermined times.

18. The drive unit for a light-emitting display panel according to claim 12, wherein

a second self-repairing mode in which a reverse-bias voltage applied to each of the self-light-emitting elements is the second voltage is provided.

19. The drive unit for a light-emitting display panel according to claim 18, having a configuration in which

all of the self-light-emitting elements arranged on the light-emitting display panel are controlled for lights-out in the second self-repairing mode.

20. The drive unit for a light-emitting display panel according to claim 12, wherein

a non-lighting scanning period longer than that of the usual lighting time is set during one frame period or one sub-frame period, and a third self-repairing mode in which a reverse-bias voltage is applied to each of the self-light-emitting elements during the non-lighting scanning period is provided.