| 摘要 |
PURPOSE:To fully automatically operate a wiper, by both driving the wiper when a rain fall sensor detects a rain drop and stopping to drive the wiper when an output of a frictional force sensor, which detects frictional force between a wiped surface and wiper blade, exceeds a prescribed value. CONSTITUTION:At running of a vehicle when it begins to rain, and a rain fall sensor 2 operates, an output of a waveform shaper circuit 17 becomes a level L to operate a differentiating circuit 18 and generate a negative pulse signal. This signal causes an output end 19c of RS-FF19 to be a level H, and a transistor T1 is turned on to close a contact S1 by operation of an exciting coil RE1. In this way, a wiper motor M is driven intermittently by an intermittent amplifier 20 or the like. Thereafter, when the rain stops, frictional force between a wiped surface and wiper blade is increased larger, an output of a comparator 16, to which an output of a frictional force sensor 2 is input after passing through an amplifier 13, rectifier 14 and integrator 15, becomes a level L, then an output of FF19 is inverted to turn off the transistor T1 and stop a wiper. |
