Display apparatus and method of driving display panel using the same

1 . A display apparatus comprising:

a display panel including a pixel and configured to display an image based on input image data;

a gate driver configured to output a gate signal to the pixel;

a data driver configured to output a data voltage to the pixel; and

a gamma reference voltage generator including a gamma bias circuit configured to generate a bias current based on a gamma voltage range which is from a voltage level corresponding to a zero grayscale to a voltage level corresponding to a setting luminance and a gamma amplifying circuit configured to receive the bias current, the gamma reference voltage generator being configured to generate gamma reference voltages and to output the gamma reference voltages to the data driver;

wherein the gamma reference voltage generator further comprises a gamma voltage setting circuit configured to output a high gamma reference voltage and a low gamma reference voltage based on the input image data, and wherein the gamma bias circuit comprises:

a gamma bias setting circuit configured to output a gamma bias code based on the gamma voltage range;

a gamma bias controlling circuit configured to receive the gamma bias code and configured to output a gamma bias current code based on the gamma bias code; and

a bias current outputting circuit configured to receive the gamma bias current code and configured to output a bias current based on the gamma bias current code.

2 . The display apparatus of claim 1 , wherein, based on the voltage level corresponding to the setting luminance of the gamma voltage range being higher than a voltage level of a reference luminance, a first bias current is applied to the gamma amplifying circuit.

3 . The display apparatus of claim 2 , wherein, based on the voltage level corresponding to the setting luminance of the gamma voltage range being lower than the voltage level of the reference luminance, a second bias current lower than the first bias current is applied to the gamma amplifying circuit.

4 . The display apparatus of claim 2 , wherein, based on the voltage level corresponding to the setting luminance of the gamma voltage range being a voltage level of a maximum luminance, a third bias current higher than the first bias current is applied to the gamma amplifying circuit.

5 . The display apparatus of claim 1 , wherein the bias current is updated on frame by frame.

6 . The display apparatus of claim 5 , wherein, based on the gamma voltage range of a present frame being wider than the gamma voltage range of a previous frame, the bias current of the present frame is higher than the bias current of the previous frame.

7 . The display apparatus of claim 5 , wherein, based on the gamma voltage range of a present frame being narrower than the gamma voltage range of a previous frame, the bias current of the present frame is lower than the bias current of the previous frame.

8 . The display apparatus of claim 1 , wherein the low gamma reference voltage is generated based on the setting luminance.

9 . The display apparatus of claim 1 , wherein the gamma amplifying circuit comprises a first gamma amplifier and a second gamma amplifier,

wherein the gamma bias circuit comprises a first gamma bias circuit and a second gamma bias circuit,

wherein a first amp bias current generated by the first gamma bias circuit is applied to the first gamma amplifier,

wherein a second amp bias current generated by the second gamma bias circuit is applied to the second gamma amplifier and

wherein the first amp bias current and the second amp bias current are different.

10 . The display apparatus of claim 1 , wherein the gamma amplifying circuit comprises a first gamma amplifier and a second gamma amplifier,

wherein a first amp bias current generated based on the setting luminance and the gamma voltage range is applied to the first gamma amplifier,

wherein a second amp bias current generated based on the setting luminance and the gamma voltage range is applied to the second gamma amplifier, and

wherein the first amp bias current and the second amp bias current are different.

11 . The display apparatus of claim 1 , wherein the gamma reference voltage generator comprises a first gamma amplifying circuit configured to generate first gamma reference voltages corresponding to an image of a first color, a second gamma amplifying circuit configured to generate second gamma reference voltages corresponding to an image of a second color and a third gamma amplifying circuit configured to generate third gamma reference voltages corresponding to an image of a third color and

wherein the first gamma amplifying circuit, the second gamma amplifying circuit and the third gamma amplifying circuit have different bias currents.

12 . The display apparatus of claim 1 , wherein the data driver and the gamma reference voltage generator are formed as an integrated data driver.

13 . A method of driving a display panel, the method comprising:

outputting a gate signal to a display panel;

generating gamma reference voltages using a gamma reference voltage generator and a gamma bias circuit;

wherein generating gamma reference voltages comprises using a gamma voltage setting circuit configured to output a high gamma reference voltage and a low gamma reference voltage based on the input image data, and

wherein using the gamma bias circuit comprises:

using a gamma bias setting circuit configured to output a gamma bias code based on the gamma voltage range;

using a gamma bias controlling circuit configured to receive the gamma bias code and configured to output a gamma bias current code based on the gamma bias code; and

using a bias current outputting circuit configured to receive the gamma bias current code and configured to output a bias current based on the gamma bias current code;

and a gamma amplifying circuit configured to receive the bias current; and

outputting a data voltage to the display panel based on input image data and the gamma reference voltages.

14 . The method of claim 13 , wherein based on a voltage level corresponding to the setting luminance of the gamma voltage range being higher than a voltage level of a reference luminance, applying a first bias current to the gamma amplifying circuit.

15 . The method of claim 14 , wherein based on the voltage level corresponding to the setting luminance of the gamma voltage range being lower than the voltage level of the reference luminance, applying a second bias current lower than the first bias current to the gamma amplifying circuit.

16 . The method of claim 14 , wherein based on the voltage level corresponding to the setting luminance of the gamma voltage range being a voltage level of a maximum luminance, applying a third bias current higher than the first bias current to the gamma amplifying circuit.

17 . The method of claim 13 , further comprising updating the bias current frame by frame.

18 . The method of claim 17 , wherein based on the gamma voltage range of a present frame being wider than the gamma voltage range of a previous frame, the bias current of the present frame is higher than the bias current of the previous frame.

19 . The method of claim 17 , wherein based on the gamma voltage range of a present frame being narrower than the gamma voltage range of a previous frame, the bias current of the present frame is lower than the bias current of the previous frame.