Organic light-emitting display device having a high aperture raatio and driving method thereof

1. An organic light-emitting display device comprising:

a display panel including a plurality of data lines, a plurality of first gate lines and a plurality of second gate lines, which define a plurality of pixels;

a data driver supplying a data signal through at least one of the plurality of data lines;

a first gate driver supplying a sensing signal through at least one of the plurality of first gate lines that cross the plurality of data lines in the display panel;

a second gate driver supplying a scanning signal through at least one of the plurality of second gate lines that are substantially parallel with the plurality of first gate lines in the display panel; and

a timing controller controlling driving timings of the data driver, the first gate driver and the second gate driver,

wherein one of the plurality of pixels includes an organic light-emitting diode, a driving transistor having a first node, a second node and a third node, a first transistor controlled by the sensing signal and connected between the respective data line and the first node of the driving transistor, a second transistor controlled by the scanning signal and connected between the respective data line and the second node of the driving transistor, and a storage capacitor connected between the first and second nodes of the driving transistor; and

a sensing unit sensing a threshold voltage or a mobility of the driving transistor,

wherein the sensing unit is connected to a driving voltage line connected to the third node of the driving transistor, the sensing unit comprises:

an analog-to-digital converter measuring a voltage of a sensing node connected to the driving voltage line, and

a switch switching a connection between a precharge voltage supply node and the sensing node and switching a connection between a connection node of the analog-to-digital converter and the sensing node.

2. The organic light-emitting display device according to claim 1 , wherein the data driver is configured for supplying the respective data line a reference voltage or a data voltage according to an operating timing of a corresponding pixel.

3. The organic light-emitting display device according to claim 1 , wherein, the first gate driver is configured to supply a sensing signal which turns on or off the first transistor, the data driver is configured to supply a reference voltage or a data voltage to the respective data line, and the second gate driver is configured to supply a scanning signal which turns on or off the second transistor, wherein, in an emission mode of the organic light-emitting display device, the first gate driver, the second gate driver and the data driver are configured to operate the one of the plurality of pixels such that:

in an initial step of the emission mode, the first transistor is turned on by the first gate driver and the reference voltage is applied to the first node of the driving transistor by the data driver,

in a writing step following the initial step, the first transistor is turned off by the first gate driver and the second transistor is turned on by the second gate driver and a data voltage is applied to the second node of the driving transistor by the data driver, and

in an emission step following the writing step, the second transistor is turned off by the second gate driver so that a current flows through the organic light-emitting diode.

4. The organic light-emitting display device according to claim 1 , wherein the sensing unit comprises:

a current measuring unit measuring a current flowing through a sensing node connected to the driving voltage line; and

a switch switching a connection between a precharge voltage supply node and the sensing node and switching a connection between a connection node of the current measuring unit and the sensing node.

5. A driving method of an organic light-emitting display device, the method comprising driving the organic light-emitting display device in an emission mode and a sensing mode, wherein:

in the emission mode, the driving method comprising:

turning on a first transistor connected between a data line and a first node of the driving transistor and applying a reference voltage through the data line to the first node of the driving transistor;

subsequently turning off the first transistor to float a voltage of the first node of the driving transistor, and applying a data voltage through the data line to a second node of the driving transistor through a second transistor connected between the data line and the second node of the driving transistor;

subsequently turning off the second transistor to allow a current to flow through an organic light-emitting diode connected to a third node of the driving transistor; and

in the sensing mode, the driving method comprising:

turning on a precharge switch coupled to a sensing node which is connected to the third node of the driving transistor to apply a precharge voltage to the sensing node, and turning on the second transistor and applying a data voltage to the second node of the driving transistor;

subsequently turning off the precharge switch, and turning on the first transistor and applying the data voltage to the first node, so that a voltage of the sensing node increase;

subsequently turning off the first transistor when the voltage increase of the sensing node stops and turning on a sampling switch coupled to the sensing node to sense the voltage of the sensing node; and

subsequently determining the threshold voltage of the driving transistor from the sensed voltage of the sensing node.

6. A driving method of an organic light-emitting display device, the method comprising driving the organic light-emitting display device in an emission mode and a sensing mode, wherein:

in the emission mode, the driving method comprising:

turning on a first transistor connected between a data line and a first node of the driving transistor and applying a reference voltage through the data line to the first node of the driving transistor;

subsequently turning off the first transistor to float a voltage of the first node of the driving transistor, and applying a data voltage through the data line to a second node of the driving transistor through a second transistor connected between the data line and the second node of the driving transistor;

subsequently turning off the second transistor to allow a current to flow through an organic light-emitting diode connected to a third node of the driving transistor; and

in the sensing mode, the driving method comprising:

turning on a precharge switch coupled to a sensing node which is connected to the third node of the driving transistor to apply a precharge voltage to the sensing node, and turning on the first and second transistors to apply a data voltage to the first and second nodes of the driving transistor;

subsequently turning off the second transistor;

subsequently turning off the precharge switch, so that a voltage of the sensing node increase;

subsequently turning off the first transistor, so that the voltage increase of the sensing node stops, and turning on a sampling switch coupled to the sensing node to sense the voltage of the sensing node; and

subsequently determining the mobility of the driving transistor from the sensed voltage of the sensing node.

7. The organic light-emitting display device according to claim 1 , further comprising a resistor connected between the driving voltage line and the sensing node.

8. The organic light-emitting display device according to claim 1 , further comprising a driving voltage line capacitor formed in the driving voltage line and the voltage of the sensing node is a voltage charged in the driving voltage line capacitor.