| 摘要 |
<p>PURPOSE: To securely detect the soil of a sensor itself without increasing the circuit scale. CONSTITUTION: A paper sheet detecting device is provided with a sensor 60, which is provided with a light emitting part 62 and a light receiving part 64 and which optically detects the existence of a paper sheet, and a comparing circuit 66, which compares the light receiving signal of the sensor 60 with the predetermined first reference level Vref1 and which outputs the paper sheet detecting signal when the light receiving signal at the first reference level Vref1 or less is detected. The device is also provided with a reference level switching circuit, which switches the first reference level Vref1 of the comparing circuit 66 to the second reference level Vref2 lower than the first reference level and for detecting the soil with a switch 68 and which outputs the soil detecting signal when the light receiving signal at the second reference level Vref2 or less is detected. Furthermore, existence of the soil detected by the soil detecting signal is displayed by a LED 70.</p> |
