| 摘要 |
PROBLEM TO BE SOLVED: To provide a detector which is hardly influenced by external light, by which an object to be detected can be detected with high reliability and which is small and power-saving, regarding the detector which detects the exis tence of the object to be detected by using a light-emitting signal. SOLUTION: A light-emitting part and a light-receiving part are reversed between a first light-emitting diode 14 and a second light-emitting diode 15, at prescribed time intervals. Whether or not a light-receiving signal in the light-receiving part is in a prescribed shape is discriminated. A side, whose influence on the light receiving signal due to the external light is small, is selected, and the existence of the object to be detected 13 between the first and second light-emitting diodes 14, 15 can be confirmed. The object can be detected with high reliability, without being hardly influenced by external light, the distance between the first and second light-emitting diodes 14, 15 can be shortened, and effect of providing the small and power-saving detector can be obtained. |
