| 摘要 |
PURPOSE:To quickly obtain a normal picture at quick start, by fixing a target potential of an image pickup device compulsively to a potential of the standard pickup state in the quick start standby state. CONSTITUTION:In the quick start standby state, a switch circuit 6 is selected to the b side, a preheat current flows to a heater 1a of a pickup tube 1, a base of a transistor TRQ is positively biased, and no video signal is outputted from the pickup tube 1. In quick start, a quick signal QU is applied to a circuit 6 of a heater control circuit 5, the circuit 6 is selected to the position (a) side, a heating current flows to the heater 1a of the pickup tube 1 and the pickup tube 1 is in operating state. At the same time, the base of the TRQ is at ground potential, and the TRQ is in cut-off state. Thus, a video signal outputted from the pickup tube 1 is video-amplified 2 at the point A, a detected 4 signal is given for automatic sensing adjustment. |
