Display device and driving method thereof

1. A display device comprising:

an afterimage compensator generating output grayscales by applying at least one of a first weight and a second weight to input grayscales when the input grayscales correspond to a still image; and

pixels displaying an image based on the output grayscales,

wherein the afterimage compensator applies the first weight having an initial value greater than 1 to the input grayscales designated as a first group, and converges the first weight to 1, and

wherein the afterimage compensator applies the second weight having an initial value less than 1 to the input grayscales designated as a second group, and converges the second weight to 1.

2. The display device of claim 1 , wherein a representative value of the input grayscales designated as the first group is smaller than a corresponding representative value of a previous frame, and

wherein a representative value of the input grayscales designated as the second group is greater than the corresponding representative value of the previous frame.

3. The display device of claim 2 , wherein as a difference between the representative value of the input grayscales designated as the first group and the corresponding representative value of the previous frame increases, the initial value of the first weight increases, and

wherein as a difference between the representative value of the input grayscales designated as the second group and the corresponding representative value of the previous frame increases, the initial value of the second weight decreases.

4. The display device of claim 1 , wherein the afterimage compensator includes:

a look-up table in which the initial value of the first weight and the initial value of the second weight are recorded.

5. The display device of claim 4 , wherein the afterimage compensator further includes:

a pixel group representative value calculator calculating pixel group representative values that are representative values in units of pixel groups with respect to the input grayscales.

6. The display device of claim 5 , wherein the afterimage compensator further includes:

a counter providing a counted value by counting the number of pixel group representative values falling within a threshold range among the pixel group representative values.

7. The display device of claim 6 , wherein the afterimage compensator further includes:

a still image detector determining whether a plurality of frames correspond to the still image based on input grayscales for the plurality of frames, and generating a still image detection signal when the plurality of frames correspond to the still image.

8. The display device of claim 7 , wherein the afterimage compensator further includes:

a selector generating the output grayscales by applying at least one of the first weight and the second weight to the input grayscales when the still image detection signal is received, and generating the output grayscales to be the same as the input grayscales when the still image detection signal is not received.

9. The display device of claim 8 , wherein the afterimage compensator further includes:

a line representative value calculator calculating line representative values that are representative values in units of pixel rows with respect to the pixel group representative values.

10. The display device of claim 9 , wherein the afterimage compensator includes:

a memory outputting the line representative values of a previous frame and storing the line representative values of a current frame.

11. The display device of claim 10 , wherein the afterimage compensator includes:

a weight calculator determining the input grayscales designated as the first group, the first weight, the input grayscales designated as the second group, and the second weight based on a difference between the line representative values of the current frame and the line representative values of the previous frame when the counted value is greater than a threshold value.

12. The display device of claim 11 , wherein the weight calculator determines the first weight and the second weight to be 1 when the counted value is less than the threshold value.

13. The display device of claim 10 , wherein the afterimage compensator includes:

a weight calculator determining the input grayscales designated as the first group, the first weight, the input grayscales designated as the second group, and the second weight based on a difference between the line representative values of the current frame and the line representative values of the previous frame and the pixel group representative values when the counted value is greater than a threshold value.

14. The display device of claim 10 , wherein the afterimage compensator includes:

a weight calculator determining the input grayscales designated as the first group, the first weight, the input grayscales designated as the second group, and the second weight based on a difference between the pixel group representative values and the line representative values of the previous frame when the counted value is greater than a threshold value.

15. The display device of claim 8 , wherein the afterimage compensator further includes:

a frame representative value calculator calculating a frame representative value that is a representative value in units of frames with respect to the pixel group representative values.

16. The display device of claim 15 , wherein the afterimage compensator includes:

a memory outputting the frame representative value of a previous frame and storing the frame representative value of a current frame.

17. The display device of claim 16 , wherein the afterimage compensator includes:

a weight calculator determining the input grayscales designated as the first group, the first weight, the input grayscales designated as the second group, and the second weight based on a difference between the frame representative value of the current frame and the frame representative value of the previous frame and the pixel group representative values when the counted value is greater than a threshold value.

18. The display device of claim 16 , wherein the afterimage compensator includes:

a weight calculator determining the input grayscales designated as the first group, the first weight, the input grayscales designated as the second group, and the second weight based on a difference between the pixel group representative values and the frame representative value of the previous frame when the counted value is greater than the threshold value.

19. A driving method of a display device comprising:

generating a still image detection signal when input grayscales correspond to a still image;

generating output grayscales by applying first and second weights to the input grayscales when the still image detection signal is generated; and

displaying an image based on the output grayscales,

wherein in the generating the output grayscales, applying the first weight having an initial value greater than 1 to the input grayscales designated as a first group, and converging the first weight to 1, and

wherein in the generating the output grayscales, applying the second weight having an initial value less than 1 to the input grayscales designated as a second group, and converging the second weight to 1.

20. The driving method of claim 19 , wherein a representative value of the input grayscales designated as the first group is smaller than a corresponding representative value of a previous frame, and

wherein a representative value of the input grayscales designated as the second group is greater than the corresponding representative value of the previous frame.