| 摘要 |
PURPOSE:To facilitate easy automatic for the adjustment and detecting process of white and dark clips and checking processes by measuring the clamp potential, white peak potential and dark clip potential of the video signal to be recorded as digital signals. CONSTITUTION:In a clamp potential measurement mode, the voltage VCC is applied to a resistance 1b via a switch 6c. Then a transistor (TR) 1c is turned on, and the clamp potential ECL of a reference voltage source 1d is supplied to an S/H circuit 4 via an emphasizing circuit 2. This potential is measured by a voltmeter 7. In a white clip potential measurement mode, a switch 6d is turned on with a switch 6e closed to the VCC side. Then the DC potential VCC higher than EWL is applied to the circuit 2, and the voltage corresponding to the base potential of a TR3b is measured by the voltmeter 7. With the dark clip potential, the switch 6d is closed to the earth side. Then a TR3c is active, and the voltage EDC corresponding to the base potential of the TR3c is supplied to the circuit 4 and measured by the voltmeter 7. |
