摘要 |
PURPOSE:To detect a color with high reliability only by one color detection element, by sweeping the color detection element on the basis of the bias signal thereof to detect the max. sensitivity corresponding to input light and judging the color of an object to be measured from the detection result. CONSTITUTION:When the bias voltage VB of a triangle wave is applied to a color detection element 1 from a bias signal oscillator 2, the element 1 is swept. Now, when light having a center wavelength at lambdaB2 is inputted to the element 1, the output signal from the element 1 becomes max. at the point of time when the bias voltage is VB2. When the output of the element 1 changing like this is applied to a peak detector 3, a pulse signal is generated the moment at the point of time tB2. At this time, the reference voltage of a comparator is set to VS and this value is the bias value corresponding to the color of a boundary desired to be discriminated as a color mark, that is, to the max. sensitivity wavelength lambdaS. Therefore, output becomes H at the time of VB>VS and this output is detected on the basis of the output signal of a detector 3 to obtain the discrimination output of the color of an object to be measured.
|