JPH0165573U - - Google Patents

Description

[Brief explanation of the drawing]

FIG. 1 is a block diagram of one embodiment of the video presence/absence determining device of this invention, and FIGS. 2 a to 2 f are timing charts for explaining the operation of FIG. 1. 3...Counter circuit, 7...Latch circuit, 8...
...Comparison circuit, 9...Operation pulse generation circuit.

Claims (1)

[Claims for Utility Model Registration] In a video presence/absence determination device that is installed in a video device such as a playback device for an electronic still camera and determines whether or not a video signal is input, the device is provided with a video signal that is obtained by synchronously separating input signals of the video device. a counter circuit that digitally counts the number of pulses during the period in which the vertical synchronization pulse of the composite synchronization signal exists; a latch circuit that holds the count data of the counter circuit with a one-field delay; A comparator circuit that compares reference data and the counting data field by field and outputs a judgment result signal, and a free-running cycle of the pulse and horizontal synchronizing pulse of the counter circuit whose level is inverted every time the counter circuit finishes counting. and an operation pulse generation circuit that outputs an exclusive logic gate pulse, which is obtained by counting clocks and whose timing is slightly delayed from the end of counting of the counter circuit, as an operation pulse of the latch circuit.