| 摘要 |
PURPOSE:To improve S/N by providing a temperature detecting element in a light detecting section and adding a controlling circuit that compensates for characteristic values of photoelectric current/dark current. CONSTITUTION:Plural positions of a metallic base plate 4 of a light detecting section 2a are pierced and a thermistor 7 is added to each position to detect the unevenness in temperature at every position of a photoelectric conversion element array. Further, a dard current offset circuit is provided as a temperature compensating circuit of an a-Si photoconductor. by changing offset in differential amplification from temperature changes of impedance in the thermistor 7, the compensated value of read signal is detected in an output 9. By this way, the zero level of the read signal is offset, and accordingly, sharp signals are obtained, and the S/N can be improved.
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