Patent ID: 7667774
Filing Date: 2010-02-23
Classification: H04N

Abstract:
1. A video switcher which transmits a video signal and a synchronization signal corresponding to the video signal to a video display unit, the transmitted video signal and synchronization signal are supplied from one video input unit selected from a plurality of video input units by a switching operation, the video switcher comprising: a video signal switching device which switches a video signal to be transmitted to the video display unit from a first video signal supplied from a first video input unit before a completion of the switching operation to a second video signal supplied from a second video input unit after the completion of the switching operation; a synchronization signal switching device which switches the synchronization signal to be transmitted to the video display unit from a first synchronization signal supplied from the first video input unit to a second synchronization signal supplied from the second video input unit; and a storage unit for storing a time period between a stop of transmission of the first synchronization signal to the video display unit and a start of transmission of the second synchronization signal to the video display unit, wherein the synchronization signal switching device stops transmitting the first synchronization signal after a first time period after a stop of transmission of the first video signal lapses and starts to transmit the second synchronization signal to the video display unit after a lapse of a constant time period T (T>0) from the stop of transmission of the first synchronization signal based on the time period stored in the storage unit, and the video signal switching device starts transmitting the second video signal to the video display unit after the stop of transmission of the first video signal to the video display unit, leading to no signal sent to the video display unit, and after a second time period after the start of transmission of the second synchronization signal to the video display unit lapses, to display a black video on the video display unit between the stop of transmission of the first video signal and the start of transmission of the second video signal to the video display unit.