| 摘要 |
PURPOSE:To attain the luminous quantity control not causing fluctuation in the entire level area of a picture signal by using bias control and gain control to set two points where setting voltages with respect to the picture signal cross together in a characteristic cure of a luminous quantity versus voltage. CONSTITUTION:A bias control circuit 11 which sets two reference voltages, two setting voltages and two points on their characteristic curve so as to control automatically two points of setting voltages with respect to a picture signal on a characteristic curve of a luminous quantity versus a voltage and a gain control circuit 3 controlling the amplification factor are provided to this circuit. Then the luminous quantity characteristic is made coincident in a range of an intermediate tone recording nonlinear component of the system. That is, two points of setting voltage in crossing with the characteristic curve of luminous quantity versus voltage with respect to a picture signal are set. Thus, dispersion in the gain is avoided and the luminous quantity control not causing fluctuation in the entire level of the picture signal is attained. |
