| 摘要 |
<p>PURPOSE:To convert an analog video signal to a digital one with an excellent balance by varying the intermediate-level setting voltage of an A/D converter to process a video signal associatively with at least either black-level setting voltage or white-level setting voltage. CONSTITUTION:The white-level voltage is obtained by voltage-dividing the power source voltage Vcc by resistors R4 and R5. The intermediate level voltage and the black-level voltage are respectively obtained by voltage-dividing the power source voltage Vcc by resistors R1, R2 and R3 when a black-level setting circuit 1 is not operating. When the circuit 1 operates and the black-level setting voltage goes to VL, the setting voltage of intermediate level also varies goes to VL, the setting voltage of intermediate level also varies associatively from VM to V'M, and the video signal can be converted to a digital signal with excel lent balance.</p> |
