| 摘要 |
PURPOSE:To detect the water drop stuck on the outside surface of glass, by providing a light source which irradiates light to the glass roughly perpendicularly from the inside surface side thereof and disposing a condenser lens and a photodetector at the optical axis which is made roughly coincident with the optical axis of the light source. CONSTITUTION:A water drop detector consists of a light emitting part 4, a photodetection part 5, a condenser lens 14 opened with a hole at the central part, and an optical filter 15, all of which are arranged on the same optical axis and are installed in a dashboard 12. An optical axis 16 is roughly perpendicular to the plane of a windshield 3. The water drop 6 stuck in the detection area acts as a concave mirror and the reflected light from the direction of the glass 3 is sorted to two kinds. Therefore, a coarse part 40 and a dense part 41 are made in the reflected light, and the signal from a photodetection part 5 has the increase and decrease signals corresponding to the coarse part and the dense part. The water drop stuck on the glass 3 is thus detected. |
