| 摘要 |
PURPOSE:To raise the safety of an operation by detecting a waterdrop adhering to a detecting surface by a variation of an electrostatic capacity and driving a wiper. CONSTITUTION:A detecting electromagnetic plate 1 is connected to an oscillating circuit 2, and an oscillating output is provided to a detecting circuit 3, by which a waterdrop detecting sensor 7 is constituted. In this state, an output of the sensor 7 is amplified 20, and this amplified output is provided to a differentiating circuit 21 in order to eliminate a variation of an oscillating amplitude such as a temperature variation over many hours of the circuit 2, the circuit 3 and the amplifying circuit 20, and a variation for many hours, caused by stain adhesion, etc. of a window pane. The circuit 21 transmits only a variation of an oscillation amplitude of a short time caused by adhesion of a waterdrop, to a comparing circuit 22. Also, a prescribed reference voltage is applied in advance to the circuit 22 from a setting device 23, and the setting device 23 adjusts sensitivity for operating a wiper, and sets its reference value level as Vref. In case when an input signal exceeds this reference value Vref, the circuit 22 transmits a detecting output to a wiper driving part 24. The driving part 24 executes electric conduction for a prescribed time to a wiper 10 provided on a vehicle based on the detecting output, and the wiper 10 is operated thereby. |
