Method of sensing characteristic value of circuit element and display device using it

1. A display device, comprising:

a display panel including a plurality of gate lines, a plurality of data lines, and a plurality of subpixels;

a gate driver circuit driving the plurality of gate lines;

a data driver circuit driving the plurality of data lines; and

a timing controller applying signals to the gate driver circuit and the data driver circuit,

wherein, for each of the plurality of subpixels, the timing controller initializes a state of a driving transistor by controlling a data voltage applied to the display panel from the data driver circuit in a sensing period for sensing a characteristic value of the driving transistor,

wherein the sensing period for sensing the characteristic value of the driving transistor includes:

an initializing period in which a data voltage-for-sensing is supplied to the subpixel to be sensed through the data line, and a reference voltage-for-sensing is supplied to the subpixel to be sensed through a reference voltage line;

a tracking period in which the reference voltage-for-sensing is blocked; and

a sampling period in which a current flowing through the reference voltage line is sensed.

2. The display device according to claim 1 , wherein each of the plurality of subpixels includes:

an organic light-emitting diode driven by the driving transistor;

a switching transistor electrically connected between a gate node of the driving transistor and a data line among the plurality of data lines;

a sensing transistor electrically connected between either a source node or a drain node of the driving transistor and a reference voltage line; and

a storage capacitor electrically connected between the gate node of driving transistor and either a source node or a drain node of the switching transistor.

3. The display device according to claim 1 , wherein a voltage of the reference voltage line is increased in response to the reference voltage-for-sensing being blocked during the tracking period.

4. The display device according to claim 1 , wherein the timing controller controls the data voltage applied to the display panel to a first initializing voltage and a second initializing voltage in the initializing period to swing a gate node-source node voltage of the driving transistor between a positive value and a negative value.

5. The display device according to claim 1 , wherein the reference voltage-for-sensing has a positive level in the initializing period.

6. The display device according to claim 1 , further comprising a deterioration sensing circuit for sensing a characteristic value of the driving transistor.

7. The display device according to claim 6 , wherein the deterioration sensing circuit includes:

an amplifier having an inverting input terminal electrically connected to the reference voltage line and a non-inverting input terminal supplied with a reference voltage-for-comparing;

a feedback capacitor electrically connected between the inverting input terminal and an output terminal of the amplifier;

an initializing switch electrically connected to the feedback capacitor; and

a sampling switch electrically connected to the output terminal of the amplifier.

8. The display device according to claim 7 , wherein the initializing switch is electrically connected in parallel with the feedback capacitor.

9. The display device according to claim 7 , wherein the initializing switch is in a turn-off state and the sampling switch is in a turn-on state during the sampling period.

10. A method of sensing a characteristic value of a circuit element in a display panel, the method comprising:

supplying a first initializing voltage to a subpixel to be sensed through a data line, and supplying a second initializing voltage to the subpixel to be sensed through the data line;

supplying a data voltage-for-sensing to the subpixel to be sensed through the data line, and supplying a reference voltage-for-sensing to the subpixel to be sensed through a reference voltage line;

blocking the reference voltage-for-sensing and increasing a voltage of the reference voltage line in response to the reference voltage-for-sensing being blocked; and

sensing a current flowing through the reference voltage line.

11. The method according to claim 10 , wherein the reference voltage-for-sensing has a positive level.

12. The method according to claim 10 , wherein the subpixel includes:

an organic light-emitting diode;

a driving transistor driving the organic light-emitting diode, the driving transistor including a source node, a gate node, and a drain node;

a switching transistor electrically connected between the gate node of the driving transistor and a data line;

a sensing transistor electrically connected between either the source node or the drain node of the driving transistor and the reference voltage line; and

a storage capacitor electrically connected between the gate node of the driving transistor and either a source node or a drain node of the switching transistor.

13. The method according to claim 11 , wherein the display panel further includes:

an amplifier having an inverting input terminal electrically connected to the reference voltage line and a non-inverting input terminal supplied with a reference voltage-for-comparing;

a feedback capacitor electrically connected between the inverting input terminal and an output terminal of the amplifier;

an initializing switch electrically connected to the feedback capacitor; and

a sampling switch electrically connected to the output terminal of the amplifier,

wherein the initializing switch is in a turn-off state and the sampling switch is in a turn-on state when the current flowing through the reference voltage line is sensed.

14. The method according to claim 10 , wherein the first initializing voltage and the second initializing voltage are set to different levels to swing a gate node-source node voltage of the driving transistor between a positive value and a negative value.