| 摘要 |
PROBLEM TO BE SOLVED: To exactly determine rainy by a simple constitution, even in a great amount of rain fall. SOLUTION: This rain sensor 400 includes an amplifier circuit 22 for amplifying a detected voltage V<SB>1</SB>of a photoelectric conversion element (photodiode 21) to be input into a processing circuit (CPU 3), and determines the rain based on a decrease of an output voltage V<SB>3</SB>from a fixed value, for example, 3.0 V, after the output voltage V<SB>3</SB>of the amplifier circuit 22 is set to the fixed value. The amplifier circuit 22 conducts offset amplification. The processing circuit 3 determines the propriety of saturation in the output voltage decrease, and directs the offset amplification in the amplifier circuit 22 to be reset, when determining the saturation in the output voltage decrease. COPYRIGHT: (C)2005,JPO&NCIPI
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