| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a reflection type sensor that can totally reflect divergent light from a light source at the boundary surface with the outside of a package without any light shielding means, thereby preventing the divergent light from entering a light receiving element. <P>SOLUTION: A light beam L0 is a light beam group out of light beams emitted from a light emitting element 23, which is refracted and passes at a boundary surface 53, is reflected at a reflection scale 21 and is guided to a light receiving area S2, and this optical path is effective light to obtain a sensor signal. A light beam La is a light beam which is totally reflected at the boundary surface 53 and propagates in a package. This light beam La is noise light irrelevant to sensor signal light, and a light beam which should not be received. When the light beam La enters a light receiving area S2, S/N of the sensor signal is reduced. Furthermore, a light beam Lb passes through the boundary surface 53 and emits to the outside without reaching the reflection scale 21, and thus it does not substantially affect the precision or the like. The light receiving area S2 is determined on the basis of a light emission area S1 of the light emitting element 23 so that an unnecessary light beam La is not incident to the light receiving area S2 of a light receiving element 24. <P>COPYRIGHT: (C)2013,JPO&INPIT |
