| 摘要 |
PROBLEM TO BE SOLVED: To suppress variations in object detectable ranges of sensors with fluctuating power source voltages. SOLUTION: A gain adjustment circuit 20f detects a voltage level of power source voltage inputted to an ultrasonic sensor 20, adjusts the gain according to the detected voltage level so that the ratio of the detected voltage level to the gain to be adjusted is constant, voltage-amplifies a reflected signal outputted from a microphone 20e with the adjusted gain, and outputs an amplified signal. COPYRIGHT: (C)2007,JPO&INPIT
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