Patent ID: 8531604

Claim:
A synchronization signal generating device configured to receive an input video signal and to output a display vertical synchronization signal, the synchronization signal generating device comprising: a cycle measuring unit configured to measure the vertical synchronization interval of the input video signal; a phase difference detecting unit configured to detect a phase difference between an input vertical synchronization signal associated with the input video signal and the display vertical synchronization signal; a vertical cycle determining unit configured to control a cycle of the display vertical synchronization signal so that the phase difference is decreased within a range of a compensation interval by advancing or delaying a phase of the display vertical synchronization signal, the compensation interval comprising a range between a minimum vertical synchronization interval and a maximum vertical synchronization interval, the vertical cycle determining unit further configured to determine a timing of the display vertical synchronization signal to be generated next based on a measurement result of the cycle measuring unit and a detection result of the phase difference detecting unit and to set 1/n of the cycle of the display vertical synchronization signal obtained based on the timing of the display vertical synchronization signal to be generated next as a cycle of an n-times-speed driving vertical synchronization signal; and a display vertical synchronization generating unit configured to generate the display vertical synchronization signal of the cycle based on the vertical cycle determining unit.