| 摘要 |
PURPOSE:To enhance detection accuracy by preventing the mixing-in of an error caused by disturbance light, by providing a light emitting element constituting a liquid detector to the inner surface of a windshield while providing a light receiving element above the light emitting element. CONSTITUTION:A light receiver 40 is secured to a front glass inner surface 10b so as to position above a light emitter 20 in such a state that the light receiving axis thereof is directed downwardly and beam light upwardly emitted from the light emitter 20 is received along the light receiving axis by the light receiver 40. Therefore, even if direct rays of the sun are incident to the front glass 10, they can not transmit a prism 43 from the bottom surface thereof toward a first flat surface, a semiconductor light receiving element 41 is prevented from receiving direct rays of the sun and a receiving signal is not accompanied by the error caused by direct rays of the sun while, even if beam light is emitted from a car running on the opposite lane during night running, it is not directly incident to the light receiver 40 and an error is not caused thereby. In addition, even if beam light is incident to the semiconductive light receiving element 41, this situation does not result in an error because of the difference in a wavelength. |
