Display device having a compensation power generator for adjusting input voltages and driving method thereof

1. A display device comprising:

a pixel array comprising a data line through which a data voltage is supplied, a gate line through which a gate signal is supplied, and pixel circuits;

a first power supply line configured to supply a pixel driving voltage to the pixel circuits;

a second power supply line configured to supply a low-potential power supply voltage lower than the pixel driving voltage to the pixel circuits;

a third power supply line configured to supply a reference voltage for initializing the pixel circuits;

a gamma reference voltage generator configured to receive first and second input reference voltages and generate gamma reference voltages having different voltage levels;

a data driver configured to receive the gamma reference voltages, generate the data voltage of pixel data, and supply the data voltage to the data line; and

a compensation power generator configured to receive the pixel driving voltage through a feedback line connected to the pixel circuits or the first power supply line, and change the reference voltage and the first and second input reference voltages according to a variation of the pixel driving voltage,

wherein the compensation power generator is configured to:

increase the reference voltage when the pixel driving voltage increases; and

decrease the reference voltage when the pixel driving voltage decreases.

2. The display device of claim 1 , wherein the pixel array includes first and second screens sharing the first, second and third power supply lines, and different content images are displayed on the first and second screens.

3. The display device of claim 1 , wherein the compensation power generator is configured to:

increase the first and second input reference voltages when the pixel driving voltage increases; and

decrease the first and second input reference voltages when the pixel driving voltage decreases.

4. The display device of claim 1 , wherein the first and second input reference voltages have gains that are set differently for each grayscale level of the pixel data.

5. The display device of claim 1 , wherein the first and second input reference voltages have gains that are set to be higher at low grayscale levels of the pixel data than at high grayscale levels of the pixel data.

6. The display device of claim 1 , wherein the compensation power generator comprises:

a first non-inverting amplifier configured to receive the first input reference voltage and the pixel driving voltage and change the first input reference voltage according to a variation of the pixel driving voltage;

a second non-inverting amplifier configured to receive the second input reference voltage and the pixel driving voltage and change the second input reference voltage according to a variation of the pixel driving voltage; and

a third non-inverting amplifier configured to receive the reference voltage and the pixel driving voltage and change the reference voltage according to a variation of the pixel driving voltage.

7. The display device of claim 1 , wherein each of the pixel circuits comprises:

a light-emitting element;

a driving element comprising a first electrode connected to the first power supply line, a gate connected to a second node, and a second electrode connected to a third node;

a capacitor connected between a first node and the second node;

a first switch element turned on according to a gate-on voltage of a first scan signal to supply the data voltage to the first node;

a second switch element turned on according to a gate-on voltage of a second scan signal to connect the gate and the second electrode of the driving element;

a third switch element turned on according to a gate-on voltage of an emission control signal to connect the first node to the third power supply line during an initialization period and an emission period,

a fourth switch element turned on according to the gate-on voltage of the emission control signal to connect the third node to an anode of the light-emitting element during the initialization period and the emission period; and

a fifth switch element turned on according to the gate-on voltage of the second scan signal to connect the third power supply line to the anode of the light-emitting element during the initialization period and a data writing period,

wherein the data writing period is set between the initialization period and the emission period.

8. The display device of claim 7 , wherein,

a pulse of the first scan signal defines the data writing period,

a pulse of the second scan signal is inverted into the gate-on voltage before a pulse of the first scan signal to define the initialization period and is inverted into a gate-off voltage simultaneously with the pulse of the first scan signal, and

a pulse of the emission control signal is inverted into the gate-off voltage when the first scan signal is inverted into the gate-on voltage and inverted into the gate-on voltage after the first and second scan signals are inverted into the gate-off voltage.

9. A driving method of a display device, the driving method comprising:

supplying a pixel driving voltage, a low-potential power supply voltage, and a reference voltage to pixel circuits;

receiving first and second input reference voltages and generating gamma reference voltages having different voltage levels;

receiving the gamma reference voltages and generating a data voltage of pixel data;

changing the first and second input reference voltages according to a variation of the pixel driving voltage;

increasing the reference voltage when the pixel driving voltage increases; and

decreasing the reference voltage when the pixel driving voltage decreases.

10. The driving method of claim 9 , further comprising divisionally displaying first and second content images on a screen of a pixel array where the pixel circuits are arranged.

11. The driving method of claim 9 , further comprising:

increasing the first and second input reference voltages when the pixel driving voltage increases; and

decreasing the first and second input reference voltages when the pixel driving voltage decreases.

12. The driving method of claim 9 , further comprising setting gains of the first and second input reference voltages to be higher at low grayscale levels of the pixel data than at high grayscale levels of the pixel data.

13. The driving method of claim 9 , further comprising:

receiving the first input reference voltage and the pixel driving voltage and changing the first input reference voltage according to a variation of the pixel driving voltage through a first non-inverting amplifier;

receiving the second input reference voltage and the pixel driving voltage and changing the second input reference voltage according to a variation of the pixel driving voltage through a second non-inverting amplifier, and

receiving the reference voltage and the pixel driving voltage and changing the reference voltage according to a variation of the pixel driving voltage through a third non-inverting amplifier.

14. A display device comprising:

a pixel array comprising a data line through which a data voltage is supplied, a gate line through which a gate signal is supplied, and pixel circuits;

a first power supply line configured to supply a pixel driving voltage to the pixel circuits;

a second power supply line configured to supply a low-potential power supply voltage lower than the pixel driving voltage to the pixel circuits;

a third power supply line configured to supply a reference voltage to the pixel circuits;

a compensation power generator configured to:

receive the pixel driving voltage through a feedback line connected to the pixel circuits or the first power supply line;

increase the data voltage and the reference voltage when the pixel driving voltage increases; and

decrease the data voltage and the reference voltage when the pixel driving voltage decreases.