| 摘要 |
PURPOSE:To secure the initial rain-drop detection area, by covering rain-drop detecting surface having comb-tooth electrodes arranged with a water/oil repelling film while the rain-drop detecting surface is inclined to remove rain drops attached onto the detecting surface and wash away dirts and dust. CONSTITUTION:Comb-tooth electrodes 2 are arranged on a rain-drop detecting surface 1a of a rain drop sensor body 1. The comb-tooth electrodes 2 are covered with a water/oil repelling film, such as ethylene tetrafluoride film 3 while the rain-drop detecting surface 1a is inclined. With such an arrangement, rain drops are allowed to cross the electrodes 2 with comb-tooth facing one another thus to increase the capacity between the electrodes 2 so that the frequency of a transmission circuit 2ill be changed to detect rain drops. Thus, as the comb-tooth electrodes on the rain-drop detecting surface are covered with the water/oil repelling film while the sensor body is inclined, dirts or the like on the detection surface is washed away to secure the initial rain drop detection area along with a higher durability of the comb-tooth electrodes.
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