| 摘要 |
<P>PROBLEM TO BE SOLVED: To compensate a change in physical property of a wall member due to variation of an ambient temperature to improve accuracy in detecting the existence of an obstacle in an obstacle detector using the wall member as a transmission path of vibration. Ž<P>SOLUTION: The obstacle detector is equipped with a transmission means attached to an internal surface of a resin wall member and transmitting ultrasonic waves via the wall member, and a reception means attached to the internal surface of the wall member and receiving the ultrasonic waves via the wall member. The detector includes a first reception means attached to a different location from the transmission means as a reception means; a propagation detecting means for detecting a first reception signal generated along with ultrasonic wave transmission and caused by propagation vibration propagated through the wall member among the reception signals of the first reception means; a temperature information detecting means for detecting, based on the first reception signal, temperature information which varies due to an ambient temperature; a threshold value setting means for setting a threshold value in accordance with temperature information; and a determining means for determining existence of the obstacle based on the results of comparison by comparing a second reception signal by a reflected wave of the obstacle detected in the reception means with the threshold value. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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