| 摘要 |
<p>PROBLEM TO BE SOLVED: To prevent detection errors caused when light from a light emitting element is reflected by a protective cover. SOLUTION: A light path through which light produced by emission from a light emitting element 4 leads to a photocell after being reflected by an object is surrounded by a slit 12, and the end of the slit 12 is covered with a translucent protective cover 14 to seal the light emitting element 4 and the incident surface 14a of light from the light emitting element 4 at a protecting cover is tilted in the orthogonal direction to the optical axis. Therefore, if the light from the light emitting element 4, mostly transmitted through the protective cover 14, is partly reflected by the incidence plane 14a and exit plane 14b of the protective cover 14, the reflected light deviates from the detecting area of the photocell as it is guided by the internal wall of the slit 12, then detecting errors are prevented.</p> |
