Organic light emitting display device and method for driving the same

1. An organic light emitting display device comprising:

a pixel unit including a plurality of pixels respectively coupled to a plurality of scan lines and a plurality of data lines;

a scan driver configured to sequentially supply a scan signal to the pixels through the scan lines, wherein the scan signal includes k (k is a natural number) bias pulses for applying a bias voltage to a driving transistor of each of the pixels and one write pulse for applying a data voltage corresponding to actual emission to the driving transistor;

a data corrector configured to correct a first grayscale value that is a grayscale value of a (j, i) pixel (i and j are natural numbers) among the pixels, based on a difference between the first grayscale value and a second grayscale value that is a grayscale value of a (j+2k, i) pixel among the pixels; and

a data driver configured to supply a data voltage corresponding to each of the grayscale values to the pixel unit through the data lines.

2. The organic light emitting display device of claim 1 , wherein the first grayscale value is included in an ultra-low grayscale range.

3. The organic light emitting display device of claim 2 , wherein, when the difference between the first grayscale value and the second grayscale value exceeds a preset reference, the data corrector is configured to provide the data driver with a correction grayscale value obtained by increasing the first grayscale value.

4. The organic light emitting display device of claim 3 , wherein the data driver is configured to output a correction data voltage corresponding to the correction grayscale value to the pixel unit,

wherein the correction data voltage is smaller than the data voltage corresponding to the first grayscale value, and

a luminance corresponding to the correction data voltage is higher than that corresponding to the first grayscale value.

5. The organic light emitting display device of claim 3 , wherein, when the difference between the first grayscale value and the second grayscale value is the preset reference or less, the data corrector is configured to not correct the first grayscale value.

6. The organic light emitting display device of claim 3 , wherein a correction data voltage corresponding to the correction grayscale value corresponds to the bias voltage applied to the (j+2k, i) pixel.

7. The organic light emitting display device of claim 6 , wherein the correction data voltage is applied to the (j+2k, i) pixel in synchronization with a first bias pulse supplied first of all among the bias pulses supplied to the (j+2k, i) pixel.

8. The organic light emitting display device of claim 2 , wherein the data corrector includes:

a grayscale determiner configured to determine whether the first grayscale value is included in the ultra-low grayscale range by receiving input image data;

a comparator configured to compare the second grayscale value and a preset reference grayscale, when the first grayscale value is included in the ultra-low grayscale range; and

a corrector configured to supply a correction grayscale value obtained by increasing the first grayscale value to the data driver, when the second grayscale value exceeds the reference grayscale.

9. The organic light emitting display device of claim 8 , wherein, when the first grayscale value is not included in the ultra-low grayscale range, the comparator and the corrector are not operated.

10. The organic light emitting display device of claim 8 , further comprising: an image determiner configured to determine whether a current image is a moving image, based on the input image data.

11. The organic light emitting display device of claim 10 , wherein, when the current image is determined as the moving image, an operation of the grayscale determiner is stopped, and

wherein, when the current image is determined as a still image, the grayscale determiner is operated.

12. The organic light emitting display device of claim 10 , wherein an increment where the first grayscale value when the current image is determined as the moving image is corrected is smaller than that where the first grayscale value when the current image is determined as a still image is corrected.

13. The organic light emitting display device of claim 1 , wherein the data corrector is configured to detect a black pattern of an image by analyzing input image data.

14. The organic light emitting display device of claim 13 , wherein, when the (j+2k, i) pixel is a pixel just under a lower boundary portion of the black pattern, and the (j, i) pixel to the (j+2k−1, i) pixel are detected as the black pattern, the data corrector is configured to increase grayscale values corresponding to the (j, i) pixel to the (j+2k−1, i) pixel and to provide the increased grayscale values to the data driver.

15. The organic light emitting display device of claim 14 , wherein data voltages corresponding to the (j, i) pixel to the (j+2k−1, i) pixel are smaller than a data voltage corresponding to a black grayscale.

16. A method for driving an organic light emitting display device, the method comprising:

determining whether a first grayscale value that is a grayscale value of a (j, i) pixel (i and j are natural numbers) is included in an ultra-low grayscale range, based on image data;

when the first grayscale value is included in the ultra-low grayscale range, comparing a difference between the first grayscale value and a second grayscale value that is a grayscale value of a (j+2k, i) pixel (k is a natural number of 1 or more);

when the difference between the second grayscale value and the first grayscale value exceeds a set reference, generating a correction grayscale value obtained by increasing the first grayscale value; and

supplying a correction data voltage corresponding to the correction grayscale value to a pixel unit,

wherein a scan signal supplied to the pixel unit includes k bias pulses for applying a bias voltage to a driving transistor of a pixel and one write pulse for applying a data voltage corresponding to actual emission to the driving transistor, and

wherein the correction data voltage is different from an original data voltage corresponding to the first grayscale value.

17. The method of claim 16 , wherein the correction data voltage is smaller than the original data voltage.

18. The method of claim 16 , wherein the correction data voltage of the (j, i) pixel with respect to the first grayscale value is smaller than a data voltage applied to a (j−1, i) pixel corresponding to the first grayscale value.

19. An organic light emitting display device comprising:

a pixel unit including a plurality of pixels respectively coupled to a plurality of scan lines and a plurality of data lines;

a scan driver configured to sequentially supply a scan signal to the pixels through the scan lines, wherein the scan signal includes k (k is a natural number) bias pulses for applying a bias voltage to a driving transistor of each of the pixels and one write pulse for applying a data voltage corresponding to actual emission to the driving transistor; and

a data corrector configured to detect a black pattern, and correct a data voltage corresponding to the black pattern among 2k pixel lines corresponding to a lower boundary portion of the black pattern in a scan direction to a preset correction data voltage and then supply the correction data voltage to the pixel unit.

20. The organic light emitting display device of claim 19 , wherein the correction data voltage is smaller than the data voltage corresponding to another portion of the black pattern.