| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a liquid drop detection apparatus which can be hung in a simple operation without processing a window glass, etc. SOLUTION: The light emitted from a light-emitting element 4 is introduced into a light guide body 7 via a diffraction grating 15, totally reflected inside the light guide body 7 and introduced into a front glass G passing through a silicone member 10, a light guide body 9 and the silicone member 10. After the light is repeatedly totally reflected in the front glass G, the light is detected by a photodetecting element 5 via the silicone member 10, the light guide body 9, the silicone member 10 and a light guide body 8. At this time, if a rain drop adheres to an outer side face of the front glass G and a point where the rain drop adheres is a total reflection point of the light, the light introduced in the front glass G is not totally reflected, but passes through the front glass G. As a result, a quantity of the light detected at the photodetecting element 5 decreases, whereby the adhesion of the rain drop is detected.</p> |
