| 摘要 |
PURPOSE:To improve detection accuracy by outputting a control signal based upon the output ratio of specified colors of color temperature information. CONSTITUTION:The outputs of four kinds of photodetectors 16-19 which have spectral characteristics of green, red, blue, and yellow are converted by logarithmic amplifiers 20-23 into logarithmic values and differential amplifiers 24-26 find the ratios of specific outputs. Namely, the amplifier 24 finds the difference between the outputs of the amplifiers 20 and 21 and the amplifiers 25 and 26 find the differences between the outputs of the amplifiers 21 and 22, and 22 and 23 similarly. A white balance adjusting voltage generating circuit WB 27 generates a control voltage for controlling the gain of a variable gain amplifier with the outputs of the amplifiers 24 and 25. A decision circuit 28 judges an incident light source from the outputs of the amplifiers 25 and 26. The output of the decision circuit 28 controls adding circuits 29 and 30. Namely, the addition and subtraction of a compensating voltage from a compensating voltage generating circuit 31 are controlled for the control voltage from the circuit 27. Consequently, the kind of the light source is securely discriminated to improve the detection accuracy.
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