| 摘要 |
A plurality of sensing arms are provided at intervals on a sensor case so as to project outwardly of the case. A light-projecting element and a photoreceptor element forming a pair are provided in the sensor case so as to correspond to respective ones of the sensing arms. Projected light from the light-projecting element advances along the longitudinal direction of the respective sensing arm and is reflected by a reflecting surface so as to be directed toward the neighboring sensing arm through a sensing area. The projected light is reflected twice by reflecting surfaces on the neighboring sensing arm so as to return to the original sensing arm through the sensing area again. The light is reflected by the reflecting surface of this sensing arm, advances along the longitudinal direction of this sensing arm again and is received by the photoreceptor element. |
