| 摘要 |
PURPOSE:To exclude intermittently stuck motion and deterioration of the visual range of a wiper by lowering the detection capability for rainfall in its beginning so that a wiper is put in action after a comparatively large quantity of waterdrops are cumulated. CONSTITUTION:A waterdrop detector A, composed of a luminous element 1 and a light receiving element 2, sends out a signal inversely proportional to the quantity of waterdrops cumulated on a window glass. The signal is inputted to a microcomputer 50 after amplification 20, noise removale 30 and A/D conversion. The microcomputer 50, which drives a wiper 70 by means of a driving circuit 60, has a small reference value in early stage of its action and does not put the wiper in action until a large quantity of raindrops are cumulated. Thus, the visual range can be prevented from deterioration due to intermittently stuck motion of a blade and stain on it. After predetermined times of action, the reference value is increased to make a normal operation. |
