| 摘要 |
<p>PURPOSE:To certainly detect a paper-sheet even if the distance to a sensor is large, by installing a light-emitting element and a photodetector which receives blinks, and integrating the output of the photodetector and using the signal reduced by a certain level as a standard signal. CONSTITUTION:A light emitting diode 13 is tuned ON and OFF with a certain duty ratio by turnign ON and OFF a transistor 12 by the output of a pulse oscillation circuit 11 on a luminous side 10. While, on a light receiving side 20, the pulse light of the light emitting diode 13 is received by a phototransistor 21, and a pulse signal S4 is generated on a collector side and input into the + terminal of a comparator 23. At the same time, the signal S4 is delay- smoothed to form a signal S5 in an integration circuit (R6, C1), and further the signal S5 is level-decreased to form a standard signal S6 through a diode 22 and compared with the signal S4 in the comparator 23. The paper-existence signal or not- existence signal S7 is output according to the result of the above-described comparison.</p> |
