| 摘要 |
PURPOSE:To prevent a signal of a middle and a low luminance signal from being compressed too excessively even if a high luminance component exists on a pattern by correcting an AGC control voltage generated at the high luminance part with a control voltage subject to DC conversion at an opposite phase. CONSTITUTION:After a signal from an image pickup tube 1 is amplified by a preamplifier 2, the signal passes through an electronic attenuator 3 and is fed through a cable via a signal processing section 4. Further, the signal from the signal processing section 4 is converted into a DC by a DC converting section 5, then fed to a mixing section 8 and fed back to the electronic attenuator 3 as an AGC control signal. The signal subject to DC conversion at an opposite phase at the DC conversion section 7 from the signal of the output of the preamplifier 2 via the high luminance detection section 6 is fed to the mixing section 8, and the two synthesis signals are used as the AGC control signal. Even if the high luminance part enters the object, the middle and low luminance components are not compressed too excessively and an easy to see image on the monitor screen is obtained.
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