| 摘要 |
PROBLEM TO BE SOLVED: To provide a photodetector making allowing appropriate adjustment of variations in the emission output of a light emitting element among products and correction of the temperature characteristic of the light emitting element even in the absence of the subject of inspection. SOLUTION: A detection control portion 41 causes a LED 14 to emit a primary light beam before a paper sheet reaches a position where the LED 14 with the paper sheet inserted therein emits the primary light beam, based on a signal output from a main control portion 51, and reads the value of a voltage output from a second PD 16 and a value of adjustment reference data stored in an EEPROM 45. The detection control portion 41 controls the operation of an LED drive circuit portion 43 so that the value of the voltage output from the second PD 16 coincides with the value of the adjustment reference data. Once the paper sheet has reached the position where the primary light beam is applied thereto from the LED 14, the detection control portion 41 causes the LED 14 to emit the primary light beam while controlling the operation of the LED drive circuit portion 43 so that the value of the voltage output from the second PD 16 coincides the value of the adjustment reference data. |
