| 摘要 |
PURPOSE:To enable to convert to analog video signals having amplitude of specified horizontal synchronizing signals by selecting D/A conversion characteristic of video signals for which amplitude of horizontal synchronizing signals is compressed and A/D converted. CONSTITUTION:Digital video signals having horizontal synchronizing signals of compressed amplitude are inputted to the first comparator 10 through an input terminal 1. Amplitude of the video signals are pedestal level from a reference circuit 12 are compared in the comparator 10, and when amplitude of the video signals is more than pedestal, high voltage is outputted in an output terminal 11. On the other hand, digital video signals are inputted to a delay circuit 13 and the second comparator 14, and detect horizontal synchronizing signals in an AND circuit 23 through an FF19. As the first switching circuit 3 is short- circuited and the second switching circuit 5 is opened, D/A conversion is made by reference voltage of the first DC power source, and video signals with horizontal synchronizing signals having specified amplitude can be obtained. |
