| 摘要 |
PURPOSE:To exactly detect a position of an object of a different reflection factor by providing a light emitting element, a photodetector and a housing, and forming an optical path of the housing to a recessed shape optical path. CONSTITUTION:Among the lights of a light emitting diode 12 loaded on a housing 11, a light 20 going to a window 17 advances toward a detecting object, but lights 18, 19 which have been turned aside a little are shut up in an optical path 14 because the optical path 14 is formed in a recessed shape, scarcely emitted from the window 17, and even if they are emitted, many reflections are repeated and an intensity of the light becomes extremely weak, and it is not detected by a phototransistor. Also, the photodetecting side is the same, too, a light 10 which has gone straight on toward the phototransistor from a window 16 arrives at the phototransistor, but an oblique light 26 repeats a reflection by a recessed shape optical path 15 and does not arrive at the phototransistor easily, and even if it has arrived, it becomes a sufficiently weak light. By constituting the recessed shape optical path in this way, a position can be detected exactly and stably even in case of an object whose reflection factor is different remarkably. |
