DISPLAY DEVICE AND DRIVING METHOD THEREOF

• US 20100194716A1
• Filed: 08/03/2009
• Published: 08/05/2010
• Est. Priority Date: 02/05/2009
• Status: Active Grant

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Park, Seong-Il
• Granted Patent: US 8,514,152 B2
• Time in Patent Office: Days
• US Class Current: 345/204
• CPC Class Codes: G09G 2300/0814 used for selection purposes, e.g. logical AND for partial update
• CPC Class Codes: G09G 2300/0819 used for counteracting undesired variations, e.g. feedback or autozeroing
• CPC Class Codes: G09G 2300/0861 with additional control of the display period without amending the charge stored in a pixel memory, e.g. by means of additional select electrodes
• CPC Class Codes: G09G 2300/0866 by means of changes in the pixel supply voltage
• CPC Class Codes: G09G 2310/0251 Precharge or discharge of pixel before applying new pixel voltage
• CPC Class Codes: G09G 2320/043 Preventing or counteracting the effects of ageing
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element

Abstract

A display device and a driving method thereof. The display device includes a plurality of pixels arranged in a matrix. Each pixel includes a light-emitting element, a driving transistor including an input terminal connected to a first node, a control terminal connected to a second node, and an output terminal, a capacitor connected between the second node and a driving voltage terminal, a switching transistor to transmit a data voltage to the first node, an emission control transistor connected between the output terminal of the driving transistor and the light-emitting element, a first compensation transistor connected between the second node and the output terminal of the driving transistor, a second compensation transistor to transmit a mobility compensation voltage to the first node, a driving control transistor to transmit a driving voltage to the first node, and a reset transistor to transmit a reset voltage to the emission control transistor.

Claims

1. A display device, comprising:

a plurality of pixels, wherein each pixel comprises;

a light-emitting element;

a driving transistor comprising an input terminal connected to a first node, a control terminal connected to a second node, and an output terminal;

a capacitor connected between the second node and a driving voltage terminal;

a switching transistor to transmit a data voltage to the first node in response to a first scanning signal;

an emission control transistor connected between the output terminal of the driving transistor and the light-emitting element, the emission control transistor to receive a second scanning signal;

a first compensation transistor connected between the second node and the output terminal of the driving transistor, the first compensation transistor to receive a third scanning signal;

a second compensation transistor to transmit a mobility compensation voltage to the first node in response to a fourth scanning signal;

a driving control transistor to transmit the driving voltage to the first node in response to a fifth scanning signal; and

a reset transistor to transmit a reset voltage to the emission control transistor in response to a sixth scanning signal.

2. The display device of claim 1, wherein

the switching transistor, the second compensation transistor, and the driving control transistor are turned off, and the first compensation transistor, the emission control transistor, and the reset transistor are turned on, such that the second node is applied with the reset voltage.

3. The display device of claim 2, wherein

the reset voltage is less than an emission threshold voltage of the light-emitting element.

4. The display device of claim 2, wherein,

after the second node is applied with the reset voltage,

the second compensation transistor, the driving control transistor, and the emission control transistor are turned off, and the switching transistor and the first compensation transistor are turned on, such that the first node is applied with the data voltage, and the voltage difference between the first node and the second node becomes an absolute value of the threshold voltage of the driving transistor.

5. The display device of claim 4, wherein,

after the first node is applied with the data voltage,

the switching transistor, the driving control transistor, and the emission control transistor are turned off, and the first compensation transistor and the second compensation transistor are turned on, such that the first node is applied with the mobility compensation voltage.

6. The display device of claim 5, wherein

the mobility compensation voltage is greater than the data voltage and less than the driving voltage.

7. The display device of claim 5, wherein

while the first node is applied with the mobility compensation voltage, a change in the voltage of the second node increases as an electric field effect mobility of the driving transistor increases.

8. The display device of claim 5, wherein

the first compensation transistor is turned off after a mobility compensation time elapses beginning when the first node starts to be applied with the mobility compensation voltage.

9. The display device of claim 5, wherein after the first node is applied with the mobility compensation voltage,

the switching transistor, the first compensation transistor, the second compensation transistor, and the reset transistor are turned off, and the driving control transistor and the emission control transistor are turned on, such that the first node is applied with the driving voltage and the light-emitting element emits light.

10. The display device of claim 9, wherein,

after the light-emitting element emits light,

the switching transistor, the first compensation transistor, the second compensation transistor, and the driving control transistor are turned off, and the emission control transistor and the reset transistor are turned on, such that the light-emitting element does not emit light.

11. The display device of claim 1, wherein

the third scanning signal applied to a pixel row is identical to the second scanning signal applied to a previous pixel row.

12. The display device of claim 1, wherein

the first scanning signal applied to a pixel row is an inversion signal of the fourth scanning signal applied to a previous pixel row.

13. The display device of claim 1, wherein

the sixth scanning signal is the same signal as the fifth scanning signal.

14. A method for driving a display device comprising a light-emitting element, a driving transistor comprising an input terminal connected to a first node and a control terminal connected to a second node, a capacitor connected between the second node and a driving voltage terminal, a switching transistor to transmit a data voltage to the first node, an emission control transistor connected between the driving transistor and the light-emitting element, a first compensation transistor connected between the second node and an output terminal of the driving transistor, a second compensation transistor to transmit a mobility compensation voltage to the first node, a driving control transistor to transmit the driving voltage to the first node, and a reset transistor to transmit a reset voltage to the emission control transistor, the method comprising:

applying the reset voltage to the second node;

compensating a threshold voltage of the driving transistor;

compensating a mobility of the driving transistor; and

emitting light at the light-emitting element.

15. The method of claim 14, wherein

in the applying of the reset voltage to the second node, the switching transistor, the second compensation transistor, and the driving control transistor are turned off, and the first compensation transistor, the emission control transistor, and the reset transistor are turned on.

16. The method of claim 14, wherein

the reset voltage is less than an emission threshold voltage of the light-emitting element.

17. The method of claim 14, wherein,

in the compensating of the threshold voltage of the driving transistor, the second compensation transistor, the driving control transistor, and the emission control transistor are turned off, and the switching transistor and the first compensation transistor are turned on, such that the first node is applied with the data voltage, and a voltage difference between the first node and the second node becomes an absolute value of the threshold voltage of the driving transistor.

18. The method of claim 14, wherein,

in the compensating of the mobility of the driving transistor, the switching transistor, the driving control transistor, and the emission control transistor are turned off, and the first compensation transistor and the second compensation transistor are turned on, such that the first node is applied with the mobility compensation voltage and a voltage of the second node is changed.

19. The method of claim 14, wherein

the mobility compensation voltage is larger than the data voltage and less than the driving voltage.

20. The method of claim 14, wherein

in the compensating of the mobility of the driving transistor, the first compensation transistor is turned off after a time elapses beginning when the first node starts to be applied with the mobility compensation voltage.

21. The method of claim 14, wherein

in the emitting of light at the light-emitting element, the switching transistor, the first compensation transistor, the second compensation transistor, and the reset transistor are turned off, and the driving control transistor and the emission control transistor are turned on.

22. The method of claim 14, further comprising

separating the first node from the driving voltage after the emitting of light at the light-emitting element.

23. The method of claim 22, wherein,

in the separating of the first node from the driving voltage, the switching transistor, the first compensation transistor, the second compensation transistor, and the driving control transistor are turned off, and the emission control transistor and the reset transistor are turned on.