| 摘要 |
In order to provide an apparatus which has a simple arrangement, can be easily adjusted, and can authenticate a bill, negotiable instrument, and the like with high reliability, adjustment is performed in advance in the absence of an identification target to equalize outputs from a photoelectric converter with respect to light sources A and B that emit light beams having different wavelengths. In this state, the difference in output between detection signals based on the light beams transmitted through an identification target is detected as an output from a high-pass filter. A sampling circuit samples a signal proportional to the difference in output between the detection values based on the light sources A and B, which is based on this output difference. Authentication is performed on the basis of the sampled value. A deterioration in the light sources is suppressed by periodically setting the interval during which only emission is stopped while the adjusted level is held in the absence of an identification target, instead of continuing adjustment by always causing the light sources A and B to alternately emit light beams.
mit light beams.
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