| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical sensor that comprises a simple means for discharging electric charges left in a parasitic capacitance of a photoelectric conversion element to be initialized in order to suppress an after-image. SOLUTION: The optical sensor where a sensor current flowing through a photoelectric conversion element in response to an incident luminous quantity at photo detection in a weak inverting state by an overflow drain operation of a transistor is converted into a voltage signal with a logarithmic characteristic so as to produce a sensor output corresponding to the converted voltage signal, is provided with a means that emits a pulse light prior to photo detection to a photoelectric conversion element to inject electric charges to a parasitic capacitance of the photoelectric conversion element to initialize it.
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