| 摘要 |
PURPOSE:To attain optimum beam control over a wide range even when an image pickup tube where gm depends on the 1st grid voltage is used by operating a signal from a preamplifier with a signal from a cathode after passing it through a knee and slope circuit. CONSTITUTION:When an image pickup tube 1 is scanned and operated, a picture signal outputted from a target 2 is amplified at a preamplifier 10 and fed to a process amplifier via a pre-process 11 after being amplified at a amplifier 10. A part of the signal is inputted to the knee and slop circuit 13 via a variable resistor circuit 12 from the preamplifier 10 at the same time, and the signal is processed at the circuit 13 and inputted to a differential amplifier 14. On the other hand, a signal obtained from a cathode 7 is inputted also to the differential amplifier 14 and both the signals are operated and processed. After the operated and processed signal passes through a drive circuit 15, the signal is outputted from a DC power supply 17 and mixed with the DC component and applied to the 1st grid 6. Since the knee and slope circuit 13 is provided in this way, even if an output signal of the preamplifier 10 is increased rapidly, the saturation of the differential amplifier 14 is prevented and the dynamic range is widened. |
