Display driving device for reducing brightness deviation of display panel

1. A display driving device comprising:

a clock generator configured to generate a clock signal having a predetermined frequency;

a sync signal generator configured to:

receive a first vertical sync signal having a first vertical period, and a first horizontal sync signal having a first horizontal period shorter than the first vertical period; and

generate a second vertical sync signal, using the first vertical sync signal, and to generate a second horizontal sync signal having a second horizontal period different from the first horizontal period, using the clock signal; and

a timing controller configured to drive a display panel based on the second vertical sync signal and the second horizontal sync signal,

wherein the sync signal generator counts the first vertical period by the first horizontal period to generate a first value, counts the first vertical period by a target value of the second horizontal period to generate a second value, counts the first horizontal period b the clock signal to generate a third value, and determines the second horizontal period based on the first, second, and third values.

2. The display driving device of claim 1 , wherein, when a porch period included in the first vertical period is less than a predetermined reference value, the second horizontal sync signal has the first horizontal period.

3. The display driving device of claim 1 , wherein the first vertical period includes a first porch period, an active period, and a second porch period.

4. The display driving device of claim 3 , wherein, for at least a portion of the second porch period, the first horizontal sync signal is inactivated, and the second horizontal sync signal is activated.

5. The display driving device of claim 1 , wherein the second horizontal period is longer than the first horizontal period.

6. The display driving device of claim 1 , wherein the sync signal generator generates the third value by dividing a count value by an integer N, and

wherein the count value is obtained by counting a time period having N number of first horizontal periods using the clock signal.

7. The display driving device of claim 1 , wherein the sync signal generator generates a plurality of count values by counting the first horizontal period using the clock signal, and generates the third value by averaging values other than values greater than a first reference value or less than a second reference value, among the plurality of count values.

8. The display driving device of claim 1 , wherein the sync signal generator generates the second vertical sync signal by delaying the first vertical sync signal by a predetermined delay time, when a back porch period of the first vertical sync signal is longer than a predetermined reference time.

9. The display driving device of claim 1 , wherein the first vertical period is determined by a refresh rate of the display panel.

10. The display driving device of claim 1 , further comprising a buffer configured to store at least a portion of image data.

11. The display driving device of claim 10 , wherein the buffer stores a portion of the image data that is not output to the display panel during an active period of the first vertical period.

12. A display driving device comprising:

a sync signal generator configured to:

receive a first vertical s vile signal having a first vertical period, and a first horizontal sync signal having a first horizontal period shorter than the first vertical period; and

generate a second vertical sync signal having the first vertical period, and a second horizontal sync signal having a second horizontal period longer than the first horizontal period;

a timing controller configured to receive image data to a display panel in response to the second horizontal sync signal during an active period of the first vertical period; and

a buffer configured to store a portion of the image data that is not output to the display panel during the active period,

wherein the sync signal generator counts the first vertical period by the first horizontal period to generate a first value, counts the first vertical period by a target value of the second horizontal period to generate a second value, counts the first horizontal period by a clock signal to generate a third valve, and determines the second horizontal period based on the first, second, and third values.

13. The display driving device of claim 12 , wherein the timing controller outputs the portion of the image data stored in the buffer to the display panel during a porch period after the active period.

14. The display driving device of claim 13 , wherein the timing controller outputs the portion of the image data stored in the buffer to the display panel in response to the second horizontal sync signal.

15. A display driving device comprising:

a sync signal generator configured to:

receive a first vertical sync signal having a first vertical period that includes a first vertical back porch period, a first vertical active period, and a first vertical front porch period; and

generate a second vertical sync signal having a second vertical period that is the same with the first vertical period; and

a timing controller configured to receive image data in response to a first horizontal sync signal having a first horizontal period, and to output to a display panel during the second vertical period in response to a second horizontal sync signal having a second horizontal period,

wherein the sync signal generator generates the second vertical sync signal by delaying the first vertical sync signal by a predetermined delay time, and

wherein the sync signal generator counts the first vertical period by the first horizontal period to generate a first value, counts the first vertical period by a target value of the second horizontal period to generate a second value, counts the first horizontal period by a clock signal to generate a third value, and determines the second horizontal period based on the first, second, and third values.

16. The display driving device of claim 15 , wherein the second vertical period includes a second vertical back porch period, a second vertical active period and a second vertical front porch period.

17. The display driving device of claim 16 , wherein a sum of the second vertical back porch period and the predetermined delay time is longer than the first vertical back porch period.

18. The display driving device of claim 16 , further comprising a buffer configured to store a portion of the image data that is not output to the display panel during the second vertical active period,

wherein the timing controller outputs the portion of the image data stored in the buffer to the display panel, during a porch period after the second vertical active period.

19. The display driving device of claim 15 , wherein the second horizontal period is longer than the first horizontal period based on a porch period included in the first vertical period being greater than a predetermined reference value.