Display device and driving method thereof
View Patent ↗The present invention relates to a pixel and a data driver, and a driving method thereof to measure degradation of an organic light emitting element and a threshold voltage and mobility of a driving transistor in an organic light emitting device, wherein the degradation of the organic light emitting element and the threshold voltage and the mobility of the driving transistor are measured in a turn-on interval or a frame interval of the display device to amend the data voltage applied to the pixel, and thereby images of improved and uniform quality may be displayed.
1. A display device, comprising:
a data driver;
a plurality of data lines and a plurality of sensing lines connected to the data driver; and
a pixel connected to each data line and sensing line, the pixel to display images,
wherein the pixel comprises:
a light-emitting element comprising a first terminal and a second terminal,
a driving transistor comprising a control terminal, an input terminal, and an output terminal, the driving transistor to output a driving current to drive the light-emitting element,
a first switching transistor controlled by a first scanning signal, and connected between the respective data line and the control terminal of the driving transistor;
a second switching transistor controlled by a second scanning signal, and connected between the respective sensing line and the output terminal of the driving transistor;
a third switching transistor controlled by a third scanning signal, and connected between the output terminal of the driving transistor and the first terminal of the light-emitting element;
a fourth switching transistor controlled by a fourth scanning signal, and connected between the control terminal of the driving transistor and the respective sensing line; and
a capacitor connected between the control terminal of the driving transistor and a driving voltage terminal.
2. The display device of claim 1 , wherein
the data driver determines at least one of a threshold voltage of the driving transistor, a mobility of the driving transistor, and a degradation of the light-emitting element.
3. The display device of claim 2 , wherein
the data driver comprises a threshold voltage sensor to determine the threshold voltage of the driving transistor.
4. The display device of claim 3 , wherein
the threshold voltage sensor comprises a ground terminal or a voltage application terminal with a lower voltage than the driving voltage, and a switch to control on/off of the respective sensing line.
5. The display device of claim 4 , wherein
the threshold voltage sensor detects the threshold voltage through the voltage of the control terminal of the driving transistor after the switch is turned on and off during a time in a state in which the first scanning signal and the third scanning signal are applied with an off voltage, and the second scanning signal and the fourth scanning signal are applied with an on voltage.
6. The display device of claim 2 , wherein
the data driver comprises a mobility sensor to determine the mobility of the driving transistor.
7. The display device of claim 6 , wherein
the mobility sensor comprises a current source to apply the same current as a maximum current that is applied to the driving transistor and a switch to turn on/off the current and the respective sensing line.
8. The display device of claim 7 , wherein
the mobility sensor determines the mobility of the driving transistor through the voltage of the control terminal of the driving transistor, which is measured by turning on the switch in a state in which the first scanning signal and the third scanning signal are applied with the off voltage, and the second scanning signal and the fourth scanning signal are applied with the on voltage.
9. The display device of claim 2 , wherein
the data driver comprises a degradation sensor to determine the degradation of the light-emitting element.
10. The display device of claim 9 , wherein
the degradation sensor comprises at least two current sources and at least two switches to turn on/off the at least two current sources and the sensing line.
11. The display device of claim 10 , wherein
the degradation sensor determines the voltage of the output terminal of the driving transistor, and determines the degradation degree of the light-emitting element by using at least two measured voltages in a state in which the at least two switches are sequentially turned on, and the switches are turned on.
12. The display device of claim 2 , further comprising
a fifth switching transistor controlled by a fifth scanning signal, and connected between the first terminal of the light-emitting element and the respective sensing line.
13. The display device of claim 12 , wherein
the degradation degree of the light-emitting element is determined through the voltage of the first terminal of the light-emitting element in a state in which the first scanning signal, the second scanning signal, and the fourth scanning signal are applied with the off voltage, and the third scanning signal and the fifth scanning signal are applied with the on voltage.
14. The display device of claim 12 , wherein
the second scanning signal and the fourth scanning signal are the same signal.
15. The display device of claim 12 , wherein:
the data driver comprises a threshold voltage sensor to measure the threshold voltage of the driving transistor, and a mobility sensor to measure the mobility of the driving transistor;
the threshold voltage sensor comprises a ground terminal and a first switch to control on/off of the sensing line; and
the mobility sensor comprises a current source to apply the same current as a maximum current that is applied to the driving transistor, and a second switch to turn the current source and the sensing line on and off.
16. The display device of claim 15 , wherein:
the data driver further comprises a degradation sensor to determine the degradation of the light-emitting element; and
the degradation sensor comprises at least two current sources and at least two switches to turn on/off the at least two current sources and the sensing lines.
17. A method for driving a display device having a display panel comprising a pixel comprising a light-emitting element comprising a first terminal and a second terminal, a driving transistor to output a driving current to drive the light-emitting element and comprising a control terminal, an input terminal, and an output terminal, a first switching transistor controlled by a first scanning signal and connected between a data line and the control terminal of the driving transistor, a second switching transistor controlled by a second scanning signal and connected between a sensing line and the output terminal of the driving transistor, a third switching transistor controlled by a third scanning signal and connected between the output terminal of the driving transistor and the first terminal of the light-emitting element, a fourth switching transistor controlled by a fourth scanning signal and connected between the control terminal of the driving transistor and the sensing line, and a capacitor connected between the control terminal of the driving transistor and a terminal of a driving voltage,
a plurality of data lines and a plurality of sensing lines connected to the pixel, and
a data driver connected to the data lines and the sensing lines, the method comprising:
is executing at least one of determining a threshold voltage of the driving transistor, determining a mobility of the driving transistor, and determining a degradation of the light-emitting element; and
amending and converting input data into a data voltage based on the determined result to apply the data voltage to the pixel according to the respective data line.
18. The method of claim 17 , wherein
all of the determining of the threshold voltage of the driving transistor, the determining of the mobility of the driving transistor, and the determining of the degradation of the light-emitting element are executed in a turn-on interval after turning on the display device before displaying images of the pixel.
19. The method of claim 17 , wherein:
the determining of the threshold voltage of the driving transistor and the determining of the mobility of the driving transistor are executed in a turn-on interval after turning on the display device before displaying images of the pixel; and
the determining of the degradation of the light-emitting element is executed in an emission interval in which the light-emitting element emits light.
20. The method of claim 17 , wherein:
the determining of the degradation of the light-emitting element is executed in an emission interval in which the light-emitting element emits light; and
the determining of the threshold voltage and the determining of the mobility are executed in a black interval in which the light-emitting element displays black between the emission intervals.