| 摘要 |
PROBLEM TO BE SOLVED: To solve a problem that conventional video image signal receiver indispensable of horizontal scanning frequency modulation through digital processing has had possibility of malfunction of a horizontal scanning frequency modulation circuit because no synchronizing signal is received in a non-signal state. SOLUTION: Detection circuits 13, 14 detect trailing timing and leading timing of a received horizontal synchronizing pulse Hsync respectively, a supplement signal generating circuit 15 generates a supplement synchronizing pulse DUMMY to supplement the horizontal synchronizing pulse Hsync on the basis of the detection timing, a signal presence discrimination circuit 16 discriminates the presence of the input of the horizontal synchronizing pulse Hsync for each period, and a selector switch 18 selects the horizontal synchronizing pulse Hsync when the signal is received or the supplement synchronizing pulse DUMMY when no signal is received on the basis of the discrimination result and provides an output of the selected signal.
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