Method of compensating gamma reference voltages, and gamma reference voltage compensation circuit

1. A method of compensating gamma reference voltages, the method comprising:

setting a plurality of emission signal on-duty ratios that have different values in a range from 0% to 100%;

setting a plurality of data offsets for the emission signal on-duty ratios, each of the data offsets being set based on a color shift, the color shift being caused according to the emission signal on-duty ratios;

generating a plurality of compensation gamma reference voltages by multiplying a gamma reference voltage by the data offsets; and

applying the compensation gamma reference voltages to an organic light emitting display (OLED) panel in dimming ranges that include the emission signal on-duty ratios, respectively.

2. The method of claim 1 , wherein each of the emission signal on-duty ratios is a ratio of an on-period of an emission signal to another period corresponding to one frame, each of the emission signal on-duty ratios being proportional to a luminance of the OLED panel.

3. The method of claim 2 , wherein a magnitude of the color shift is greater as the emission signal on-duty ratio is smaller.

4. The method of claim 3 , wherein each of the data offsets for the emission signal on-duty ratios includes a red data offset for a red color, a green data offset for a green color, and a blue data offset for a blue color.

5. The method of claim 4 , wherein the red data offset, the green data offset, and the blue data offset are determined based on a magnitude of the color shift of the red color, a magnitude of the color shift of the green color, and a magnitude of the color shift of the blue color, respectively.

6. The method of claim 5 , wherein the dimming ranges are selected based on the luminance of the OLED panel.

7. The method of claim 6 , wherein the emission signal on-duty ratios include a first on-duty ratio and a second on-duty ratio, the second on-duty ratio being smaller than the first on-duty ratio.

8. The method of claim 7 , wherein generating the compensation gamma reference voltages includes:

generating a first compensation gamma reference voltage by multiplying the gamma reference voltage by a data offset for the first on-duty ratio, and

generating a second compensation gamma reference voltage by multiplying the gamma reference voltage by a data offset for the second on-duty ratio.

9. The method of claim 8 , wherein an absolute value of the data offset for the second on-duty ratio is greater than an absolute value of the data offset for the first on-duty ratio.

10. The method of claim 7 , wherein setting the data offsets includes:

setting a second data offset for the second on-duty ratio, and

obtaining a first data offset for the first on-duty ratio by multiplying the second data offset for the second on-duty ratio by a constant factor that is inversely proportional to a magnitude of at least one of the emission signal on-duty ratios.

11. A gamma reference voltage compensation circuit, comprising:

a gamma reference voltage generating unit that generates a gamma reference voltage; and

an offset setting unit that sets a plurality of emission signal on-duty ratios based on a duty ratio control signal, and that sets a plurality of data offsets for the emission signal on-duty ratios, each of the data offsets being based on a color shift, the color shift being caused according to the emission signal on-duty ratios, wherein:

a plurality of compensation gamma reference voltages are generated by multiplying the gamma reference voltage by the data offsets for the emission signal on-duty ratios, and

the compensation gamma reference voltages are applied to an organic light emitting display (OLED) panel.

12. The circuit of claim 11 , wherein each of the emission signal on-duty ratios are proportional to a luminance of the OLED panel, each of the emission signal on-duty ratio being controlled by the duty ratio control signal.

13. The circuit of claim 12 , wherein the offset setting unit sets a red data offset for a red color, a green data offset for a green color, and a blue data offset for a blue color, respectively.

14. The circuit of claim 13 , wherein the red data offset, the green data offset, and the blue data offset are determined based on a magnitude of the color shift of the red color, a magnitude of the color shift of the green color, and a magnitude of the color shift of the blue color, respectively.

15. The circuit of claim 14 , wherein:

the duty ratio control signal is applied to a power voltage generating unit, the duty ratio control signal being generated by a duty ratio controlling unit,

the power voltage generating unit provides a power voltage to the OLED panel based on the duty ratio control signal, and

the OLED panel displays an image based on a data signal during an on-period of the power voltage, and displays an image based on a black data during an off-period of the power voltage, the black data indicating a black state.

16. The circuit of claim 11 , wherein the offset setting unit sets a data offset for a minimum emission signal on-duty ratio among the emission signal on-duty ratios, and obtains the data offsets for the emission signal on-duty ratios by multiplying the data offset for the minimum emission signal on-duty ratio by a constant factor, the constant factor being inversely proportional to a magnitude of at least one of the emission signal on-duty ratios.