| 摘要 |
<p>PURPOSE: To eliminate the shield of a sensor entirely by arranging a light receiving element and a conductive layer for shielding the wiring within a case and connecting the conductive layer with one lead thereby protecting the main circuit against burning due to electromagnetic noise. CONSTITUTION: A light emitting element 23 opposing a light receiving element 22 through a detection recess 24 of a resin case body 21 emits light through a slit 31 toward the light receiving element 22. When an object is inserted between both elements 22, 23, light is not received by the light receiving element 22 and thereby no current flow through the wiring 29 of the light receiving element 22. Since the light receiving element has high impedance, noise is picked up mainly on the side of the light receiving element 22 which is thereby influenced. Consequently, at least the light receiving side 22 must be covered with metal layers 32, 33 including the wiring 29. The metal layers 32, 33 provide the shield effect and protect the light receiving element 22 and the circuitry against burning. This structure eliminates the need of coating the microphotosensor with a conductive material and earthing.</p> |
