| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a sensor fouling detection circuit that detects fouling of the light projecting/receiving surface of a photo sensor and informs a person in charge thereof. <P>SOLUTION: The output voltage level (sensor level Vin) of a photo transistor (Tr) 33 in a photo sensor 31 is compared with a fouling determination reference value (VL). The sensor level Vin of the photo transistor (Tr) 33 increases as light receiving quantity decreases. Therefore, when stain is adhered to the photo transistor (Tr) 33 or a light emitting diode (LED) 32, the light receiving quantity of the photo transistor (Tr) 33 decreases and the sensor level Vin thereof increases. As a result, the degree of the sensor level Vin is determined to detect fouling of the photo sensor 31. <P>COPYRIGHT: (C)2008,JPO&INPIT</p> |
