| 摘要 |
<p>PURPOSE:To obtain a detecting device which has excellent discriminating property of a detected signal, disturbance light, noise and the like and can be formed with simple circuits by judging the presence of water droplets when the outputs of an A/D converter circuit which converts the outputs of a peak holding circuit into digital quantities continuously exceed a preset value by a specified number of times. CONSTITUTION:A water-droplet detecting means 5 projects light having a specified frequency on the surface of the window glass of a vehicle, detects the reflected light from the surface of the glass and detects the presence or absence of the rain drops. A control unit 1 has the following parts: a peak holding circuit which detects the peak value of the analog signal from the detecting means 5; an A/D converter circuit quantities at every specified period; and a reset means which resets the peak holding circuit in synchronization with the A/D conversion. When the outputs from the A/D conversion circuit continuously exceed a preset value by a specified times, the presence of the water- droplets is judged.</p> |
