| 摘要 |
PURPOSE:To adjust white balance automatically, by subtracting and smoothing a color signal that did not pass through a gain controlling circuit and a color signal that passed through the gain controlling circuit, and controlling the gain of the gain controlling circuit of small variable range of gain by the signal. CONSTITUTION:Voltage of manual variable voltage generating circuits 4, 5 is changed manually beforehand to make the amplitude of output of gain controlling circuits 2, 3 a desired value. The range of gain cntrol of gain controlling circuits 19, 20 is made smaller than the range of gain control of gain controlling circuits 2, 3. A color signal that passed through gain controllin circuits 2, 19 or 3, 20 and a color signal that did not pass through the controlling circuits are subtracted by subtraction circuits 21, 22. Output of subtraction circuits 21, 22 is smoothended by smoothing circuits 23, 24 and the gain of gain controlling circuits 19, 20 is controlled. |
