System distinction manner and multiscan monitor null of entry image signal of multiscan

摘要

PURPOSE:To allow the setting of user systems of the number meeting a need and the well automatic discriminating of the system of an input video signal without being limited by the horizontal frequency fH of the input video signal, the state of a synchronizing signal, etc. CONSTITUTION:A memory 1 having a fixed system region 1a and a user system region 1b and a detecting means 2 which detects the horizontal frequency fH of the input video signal, the horizontal scanning line during one vertical period and the polarity of the synchronizing signal are provided. The user system region 1b of the memory 1 is first searched and thereafter the fixed system region la is searched in order to judge the system of this input video signal by the result of the detection with this detecting means 2 and the system information stored in the memory 1.