| 摘要 |
<p>PURPOSE:To obtain a control circuit which can control the level of a signal obtained from a television camera, etc., to a constant value easily, by making use of characteristics of an A/D converter. CONSTITUTION:A black-and-white video signal, supplied to input terminal 1 from a pickup unit, for example, is supplied to via DC regenerating circuit 2 to A/D converter 3, where it is converted into a digital signal and then extracted from output terminal 4. This digital signal is supplied to D/A converter 5 and then converted into an analog signal, which is semipeak-detected by semipeak detection circuit 6. Comparator 7 compares this detection voltage with reference voltage E0 and a voltage equivalent to the difference between the both is supplied to A/D converter 3 as its comparative reference voltage.</p> |
