| 摘要 |
PROBLEM TO BE SOLVED: To provide an apparatus for detecting raindrop amount, capable of detecting the amount of raindrops with higher accuracy, even when strong ambient light is incident. SOLUTION: A raindrop amount detecting section 16 sets the ground potential of an amplifying circuit 70 to the ground potential in a light emission period of a light-emitting element 3 and acquires a digital value of an output voltage Vs of the amplifying circuit 70 through an A/D conversion section 13. Furthermore, the raindrop amount detecting section 16 sets the ground potential of the amplifying circuit 70 to a reference potential, generated by a constant-voltage circuit 30, in a light non-emission period of the light-emitting element 3 and acquires the variation gradientΔVg of the output voltage of the amplifying circuit 70 via the A/D conversion section 13. Then, the raindrop amount detecting section 16 makes a correction section 15 to correct the output voltage Vs which is to be acquired in the light emission period, by using the variational gradientΔVg, which is acquired in the light non-emission period, and detects the amount of raindrops, based on the correction processed output voltage Vg' which has been corrected. COPYRIGHT: (C)2008,JPO&INPIT
|
