| 摘要 |
PURPOSE:To decrease the number of parts and to improve a dust-proof effect and switching characteristic by providing a dust-proof cover of a single body which has a shielding region for transmitted light and is provided with the effect of closing both light transmitting windows. CONSTITUTION:A light emitting element 21 is housed in a light emitting element housing chamber 20, and a housing chamber 22 for a photodetector 23 is provided oppositely to the chamber 2. Light transmitting windows 24a, 24b are formed on the opposed walls of the chambers 20 and 22. A dust-proof cover 26 having a roughly U-shaped section formed with projecting parts 25 to fit into the windows 24a, 24b on both side faces is fitted between the chambers 20 and 22. The cover 26 is formed of a light transmittable member and is formed with a through-hole 27 at the central part of the bottom thereof. The hole 27 serves as a shielding region for the transmitted light to absorb the light propagating in the cover 26. |
