ORGANIC LIGHT-EMITTING DISPLAY DEVICE WITH DATA DRIVER OPERABLE WITH SIGNAL LINE CARRYING BOTH DATA SIGNAL AND SENSING SIGNAL

• US 20130147694A1
• Filed: 12/10/2012
• Published: 06/13/2013
• Est. Priority Date: 12/12/2011
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Display Co., Ltd.
• Inventors: KIM, Seung Tae, KIM, Jin Hyoung, HA, Won Kyu, SHIM, Jong Sik
• Granted Patent: US 9,129,554 B2
• Time in Patent Office: Days
• US Class Current: 345/82
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2320/029 by monitoring one or more pixels in the display panel, e.g. by monitoring a fixed reference pixel
• CPC Class Codes: G09G 2320/0295 by monitoring each display pixel
• CPC Class Codes: G09G 2320/045 Compensation of drifts in the characteristics of light emitting or modulating elements
• CPC Class Codes: G09G 3/32 semiconductive, e.g. using light-emitting diodes [LED]
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element
• CPC Class Codes: G09G 3/3275 Details of drivers for data electrodes
• CPC Class Codes: G09G 3/3659 the addressing of the pixel involving the control of two or more scan electrodes or two or more data electrodes, e.g. pixel voltage dependant on signal of two data electrodes

Abstract

An organic light emitting display device having a data line that is used for sending data voltage signals to pixels from a data driver as well as send sensor signals for detecting threshold voltage levels of driving transistors in the pixels at different times. By using the same data line to transmit the data voltage signals and the sensor signals, the number of signal lines in the organic light emitting display can be reduced. The data driver also includes switches for selectively coupling the data line to a driver unit or an analog to digital converter (ADC) unit.

Claims

1. An organic light-emitting display device, comprising:

a plurality of data lines;

a plurality of pixels connected to each of the plurality of data lines; and

a data driver comprising;

a driver unit configured to generate a first data voltage signal to operate a pixel and a second data voltage signal;

a sensing unit configured to detect a threshold voltage of a driving transistor for controlling current through an organic light emission element in the pixel;

a switching unit configured to;

connect the driver unit to the pixel via a data line of the plurality of data lines during first times to transmit the first data voltage signal from the driver unit to the pixel,

connect the driver unit to the pixel via the data line during second times to transmit second data voltage signal from the driver unit to the pixel, and

connect the sensing unit to the pixel via each of the data line to detect the threshold voltage of the driving transistor during third times.

2. The organic light-emitting display device of claim 1, wherein the pixel comprises a first node coupled to a gate of the driving transistor and a second node coupled to the data line.

3. The organic light-emitting display device of claim 2, wherein the second data voltage signal configured to set a voltage difference between the first node and the second node.

4. The organic light-emitting display device of claim 1, wherein the switching unit comprises:

a first switch configured to turn on during the first times to transmit the first data voltage signal to the pixel and turn on during the second times to transmit the second data voltage signal to the pixel, the first switch configured to turn off during the third times, and

a second switch configured to turned on to connect the sensing unit to the pixel during the third times, the second switch configured to turned off during the first times and the second times.

5. The organic light-emitting display device of claim 2, wherein the pixel includes:

a first transistor configured to switch connection between the first node and a reference voltage source;

a second transistor configured to switch connection between the second node and the data line;

an organic light emission element coupled to the second node and a first supply voltage source;

the driving transistor between a power supply line and the first and second nodes, the driving transistor further configured to generate sensing current; and

a storage capacitor connected between the first and second nodes and configured to maintain a voltage difference between the first node and the second node.

6. The organic light-emitting display device of claim 5, wherein the first transistor in the pixel is turned on to connect the reference voltage source to the first node.

7. The organic light-emitting display device of claim 1, wherein the driving transistor generates the current through the organic light emission element based on the first data voltage.

8. The organic light-emitting display device of claim 5, wherein the first transistor is operated by a first scan signal and the second transistor is operated by a second scan signal, wherein the first scan signal rises to an active state before the second scan signal and drops to inactive state after the second scan signal drops to an inactive state.

9. The organic light-emitting display device of claim 8, wherein the first scan signal drops to an inactive state before the second scan signal.

10. The organic light-emitting display device of claim 5, wherein during the second times,

the first transistor is turned on to connect the reference voltage source to the first node,

the second transistor is turned on to couple the second node to the driver unit to receive the second data voltage signal, and

the first switch is turned on to connect the driver unit to the second node.

11. The organic light-emitting display device of claim 10, wherein during the third times, the first switch is turned off and the second switch is turned on to connect the pixel to the sensing unit.

12. The organic light-emitting display device of claim 1, wherein a voltage level of the second data voltage is higher than a threshold voltage of the driving transistor but lower than a threshold voltage of the organic light emission element.

13. The organic light-emitting display device of claim 1, wherein the third times comprise vertical blank periods.

14. The organic light-emitting display device of claim 1, further comprising a controller configured to generate a compensated data signal based on the detected threshold voltage of the driving transistor, the data driver generating another first data voltage signal for a subsequent frame based on the compensated data signal.

15. A method of operating an organic light-emitting display device, comprising:

generating a first data voltage signal to operate a pixel and a second data voltage signal at a driver unit of a data driver;

connecting the driver unit to the pixel via a data line during first times to transmit the first data voltage signal from the driver unit to the pixel;

controlling current through an organic light emission element based on the first data voltage signal at the first times;

connecting the driver unit to the pixel via the data line during second times to transmit second data voltage signal from the driver unit to the pixel;

connecting a sensing unit of the data driver to the pixel via each of the data line during third times to transmit sensing signal from the pixel to the sensing unit;

detecting a threshold voltage of a driving transistor based on the sensing signal at the third times; and

receiving a compensated data signal by the driver unit to generate another first data voltage signal, the compensated data signal generated based on the detected threshold voltage of the driving transistor.

16. The method of claim 15, further comprising setting a voltage difference between a first node in the pixel coupled to a gate of the driving transistor in the pixel and a second node in the pixel coupled to the data line.

17. The method of claim 15, further comprising:

turning on a first switch during the first times to transmit the first data voltage signal to the pixel;

turning on the first switch during the second times to transmit the second data voltage signal to the pixel;

turning off the first switch during the third times, and

turning on a second switch to connect the sensing unit to the pixel during the third times; and

turning off the second switch during the first times and the second times.

18. The method of claim 15, wherein the third times comprise vertical blank periods.

19. The method of claim 15, further comprising:

turning on a first transistor in the pixel during the second time to connect a reference voltage source to a first node coupled to a gate of the driving transistor;

turning on a second transistor in the pixel to connect a second node to the data line during the second times;

switching the driving transistor between a first supply voltage source and the second node based on a voltage level at the first node and another voltage level at the second node to generate driving current; and

operating the organic light-emitting element to emit light by passing the driving current through the organic light-emitting element to a second supply voltage source.

20. The method of claim 15, wherein a voltage level of the second data voltage is higher than a threshold voltage of the driving transistor but lower than a threshold voltage of the organic light emission element.