Display driver, operating method thereof, host for controlling the display driver, and system having the display driver and the host

1. A method for operating a display driver comprising:

generating a count value by counting a period of a synchronization signal related to a synchronization packet received from a host;

receiving a mode change command from the host, the mode change command indicating a change from a video mode transmitting first image data to a display by bypassing a frame memory to a command mode transmitting second image data to the display through the frame memory; and

generating an internal synchronization signal having a period substantially equal to the period of the synchronization signal by using the count value based on the mode change command after a last pulse of the synchronization signal is generated, a time interval between the last pulse and a first pulse of the internal synchronization signal being equal to the period of the synchronization signal.

2. The method of claim 1 , further comprising:

writing the first image data in the frame memory as soon as bypassing the first image data to the display during at least one frame after receiving the mode change command.

3. The method of claim 1 , further comprising:

writing the first image data in the frame memory as soon as bypassing the first image data to the display during the time interval.

4. The method of claim 1 , wherein a frame rate of the first image data is greater than a frame rate of the second image data.

5. The method of claim 1 , further comprising:

calculating a difference between the period of the synchronization signal and the period of the internal synchronization signal; and

adjusting generation timing of a tearing effect control signal by using the difference and transmitting the tearing effect control signal to the host.

6. An image processing system comprising:

a display driver; and

a host configured to control an operation of the display driver, the display driver configured to generate a count value by counting a period of a synchronization signal related to a synchronization packet transmitted from the host, receive a first mode change command, which indicates a change from a video mode transmitting first image data to a display by bypassing a frame memory to a command mode transmitting second image data to the display through the frame memory, from the host, and generate an internal synchronization signal having a period substantially equal to the period of the synchronization signal by using the count value after a last pulse of the synchronization signal is generated, and a time interval between the last pulse and a first pulse of the internal synchronization signal is equal to the period of the synchronization signal, and the host does not transmit a new synchronization packet to the display driver after the video mode is changed into the command mode.

7. The system of claim 6 , wherein the display driver is configured to write the first image data in the frame memory as soon as bypassing the first image data to the display during at least one frame after receiving the mode change command.

8. The system of claim 6 , wherein the display driver is configured to calculate a difference between the period of the synchronization signal and the period of the internal synchronization signal, adjust generation timing of a tearing effect control signal by using the difference after receiving a second mode change command, which indicates change from the command mode to the video mode, from the host, and transmit the tearing effect control signal to the host, and the host is configured to generate a new synchronization packet based on the tearing effect control signal.

9. The system of claim 8 , wherein the display driver is configured to adjust the generation timing of the tearing effect control signal such that a time interval between a first pulse of a synchronization signal restored in the display driver and a last pulse of the internal synchronization signal is equal to the period of the internal synchronization signal based on the new synchronization packet.

10. A method of operating a display driver, the method comprising:

generating a control signal based on a period of a synchronization signal and a period of an internal synchronization signal, the control signal including error information, the error information including a difference between the period of the synchronization signal and the period of internal synchronization signal;

sending the control signal to a host; and

receiving a packet from the host, a transmission timing of the packet being based on the control signal, wherein the generating includes generating the internal synchronization signal using a count value, the count value determined by counting a period of a synchronization packet received from the host.

11. The method of claim 10 , wherein the generating includes generating the control signal based on the period of the synchronization signal, the period of the internal synchronization signal, and a control value received from the host, the control value including error information previously received by the host.

12. The method of claim 10 , further comprising:

processing the packet received from the host to generate a restored image signal and the synchronization signal; and

transmitting the restored image signal and at least one of the synchronization signal and the internal synchronization signal to a display.

13. The method of claim 12 , wherein

transmitting the restored image signal includes transmitting the restored image signal through a frame memory if the restored image signal is a still image signal, and

transmitting the internal synchronization signal to the display.

14. The method of claim 12 , wherein

transmitting the restored image signal includes the restored image signal bypassing a frame memory if the restored image signal is a moving image signal, and

transmitting the synchronization signal to the display.

15. The method of claim 10 , further comprising:

receiving a mode change command from the host, the mode change command indicating a change from a video mode to a command mode, the video mode being a mode in which first image data is transmitted to a display by bypassing a frame memory, the command mode being a mode in which second image data is transmitted to the display through the frame memory.

16. The method of claim 10 , wherein the period of the internal synchronization signal is substantially equal to the period of the synchronization signal.

17. The method of claim 10 , wherein the internal synchronization signal is generated by using the count value after a last pulse of the synchronization signal is generated, a time interval between the last pulse and a first pulse of the internal synchronization signal being equal to the period of the synchronization signal.

18. The method of claim 10 , further comprising:

calculating the difference between the period of the synchronization signal and the period of the internal synchronization signal.