| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To prevent the incidence of diffusion light from a light source into a photodetector through total reflection at the boarder surface of a package with the outside thereof without employing any light shielding means. <P>SOLUTION: Light beam L0 among light beams outgoing from a light emitting element 23 is transmitted after refracting at the boarder surface 53, then, reflected by a reflection scale 21, and finally guided to a photo detecting region S2. This light path becomes effective in order to obtain a sensor signal. Light beam La is one which undergoes total reflection at the boarder surface 53, and propagates in the package while the light beam La is noise light having no relation with the sensor signal light and is a light beam which is not to be received. When this light beam La carries out incidence into the photo detecting region S2, the S/N of the sensor signal is deteriorated after all. In order to prevent the incidence of unnecessary light beam La into the photo detecting region S2 of the photodetector 24, the photo detecting region S2 is determined based on the reference of the light emitting region S1 of the light emitting element 23. <P>COPYRIGHT: (C)2008,JPO&INPIT</p> |
