| 摘要 |
PURPOSE:To perform the reproduction of an image by internal synchronization automatically when no video signal is inputted, even in an activity state where no operating input is supplied from an external device, by selecting an oscillation circuit by a synchronization change-over switch, responding to an output which represents the absence of a video signal. CONSTITUTION:A synchronization change-over switch 68 is controlled by a synchronization change-over control signal SYNCH. When the signal SYNCH is at an H level, a switch 68 is connected to a waveform arranging circuit 66 side, and when the signal SYNCH goes to an L level, the switch 68 is connected to an oscillation circuit 67 side. Assuming that the level of the control signal SYNCH outputted from a control device 50 is divided into the first operation, and the second operation, in the first operation, synchronization is taken by an external synchronization in a picture recording mode, and by the internal synchronization in a reproducing mode, and in the second operation, it is taken by the external synchronization in principle in both modes. A low-pass filter 77, and a switching transistor 78 is provided to perform the switching so as to connect the change-over switch 68 to the oscillation circuit 67 by detecting the control signal SYNCH when no video signal is inputted, and converting the control signal SYNCH supplied to the change-over switch 68 to the L level compulsorily.
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