| 摘要 |
PURPOSE:To realize the same gamma characteristic independently of the change in luminous intensity, by moving the set point level of the approximate gamma characteristic corresponding to the change in the gain of an AGC amplifier circuit at the change in the luminous intensity. CONSTITUTION:When an output signal of an AGC detection circuit 62 is decreased through the decrease in the luminous intensity, a transistor TR702 starts conduction, TRs 703-707 start operation and a current corresponding to the collector current of a TR702 flows to the TRs 705-707. In this case, the base voltage of TRs 103, 104 is decreased by the voltage drop of resistors 717, 718 through a current flowing to the collector of the TRs 706, 707. That is, the level of the gamma set voltage can be lowered equivalently and the control of the gamma set level corresponding to the gain change of an AGC amplifier circuit 61 is made. |
