| 摘要 |
PROBLEM TO BE SOLVED: To collect stable optical data even if the passage position of paper sheets changes by alternately changing-over the light projecting side and the light receiving side of a pair of LED and detecting the presence or absence, etc., of the paper sheets based on light receiving signals on the both sides of the paper sheets. SOLUTION: A sensor means 10 reading optical data of paper sheets is composed of a pair of LEDs(light emitting diode) 11 and 12 and LED 11 and 12 are arranged on the upper and lower route surfaces opposedly to each other. LED 11 and 12 are of the same material. When one is operated as a light source, the other LED is operated as a light receiving sensor and the light projecting side and the light receiving side are controlled by a light projection/ reception change-over means 20 so as to be alternately changed-over. Storage means 41 and 42 respectively store a light receiving signal value from light receiving LED before/after change-over by the change-over means 20. A comparing means 50 calculates the addition and average of the light receiving signal value after/before change-over stored in the storage means 41 and 42 so as to compare it with a previously fixed value. |
