| 摘要 |
PURPOSE:To correctly detect a raining condition, by a method wherein a light receiving element is located so that it detects only the light which is scattered resulting from the contact of direct light from a light emitting element with a rain drop. CONSTITUTION:A light emitting element 2 and a light receiving element 3 are attached to a cylinder 1 made of a light-shielding material so that the element 3 does not receive the direct light from the light emitting element 2 and receives light being scattered resulting from the contact of direct light with a rain drop 7. With the light emitting element 2 driven, light is radiated from a drive circuit 8 toward a detecting space 4, and the light receiving element 3 receives light scattered due to the rain drop 7 passing through the detecting space 4. The output from the receiving element 3 is amplified by a pulse amplifying circuit 9, and a pulse exceeding a given level is discriminated by a level discriminating circuit 10. The output is inputted to a level discriminating circuit 13 via a monostable multivibrator 11 and an integration circuit 12, and when an integrated output exceeds the discriminating level, an alarm circuit 14 is actuated. |
