Video switcher and video switching method

Abstract

A video switcher includes: a video signal switching device for switching a video signal to be transmitted to a video display unit from a first video signal supplied from a first video input unit into a second video signal supplied from a second video input unit; and a synchronization signal switching device for switching a synchronization signal to be transmitted to the video display unit from a first synchronization signal supplied from the first video input unit into a second synchronization signal supplied from the second video input unit. The synchronization signal switching device starts transmission of the second synchronization signal to the video display unit after stops transmission of the first synchronization signal to the video display unit. The video signal switching device starts transmission of the second video signal to the video display unit, after stop of transmission of the first video signal to the video display unit and start of transmission of the second synchronization signal to the video display unit.

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 constant 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 switches from the first synchronization signal to the second synchronization signal while the video signal switching device switches from the first video signal to the second video signal, and   starts to transmit the second synchronization signal after a lapse of the constant time period from the stop of transmission of the first synchronization signal.   
     
     
         2 . The video switcher according to  claim 1 , wherein:
 the storage unit stores a time period between a stop of transmission of the first video signal to the video display unit and the stop of transmission of the first synchronization signal to the video display unit, and   the synchronization signal switching device stops the transmission of the first synchronization signal to the video display unit based on the time period.   
     
     
         3 . The video switcher according to  claim 1 , wherein:
 the storage unit stores a time period between the start of transmission of the second synchronization signal to the video display unit and the start of transmission of the second video signal to the video display unit, and   the video signal switching device starts the transmission of the second video signal to the video display unit based on the time period.   
     
     
         4 . The video switcher according to  claim 1 , further comprising:
 a time setting unit which sets the constant time period stored in the storage unit.   
     
     
         5 . A video switching method for transmitting 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 among a plurality of video input units by a switching operation of a video switcher, the video switcher contains:
 a video signal switching device for switching a video signal to be transmitted to the video display unit from a first video signal supplied from a first video input unit to a second video signal supplied from a second video input unit;   a synchronization signal switching device for switching a 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 constant 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,   the method comprising:   stopping to transmit the first synchronization signal to the video display unit; and   starting to transmit the second synchronization signal to the video display unit after a lapse of the constant time period from the stop of transmission of the first synchronization signal,   wherein the synchronization signal switching device switches from the first synchronization signal to the second synchronization signal while the video signal switching device switches from the first video signal to the second video signal.   
     
     
         6 . The video switching method according to  claim 5 , further comprising:
 storing a time period between a stop of transmission of the first video signal to the video display unit and the stop of transmission of the first synchronization signal to the video display unit in the storage unit; and   stopping to transmit the first synchronization signal to the video display unit based on the time period.   
     
     
         7 . The video switching method according to  claim 5 , further comprising:
 storing a time period between the start of transmission of the second synchronization signal to the video display unit and a start of transmission of the second video signal to the video display unit in the storage unit; and   starting to transmit the second video signal to the video display unit based on the time period.   
     
     
         8 . The video switching method according to  claim 5 , further comprising:
 setting the constant time period in the storage unit which a time setting unit.