| 摘要 |
<p>PROBLEM TO BE SOLVED: To improve short distance performance of an ultrasonic sensor by allowing the sensor to distinguish a received signal due to reflection waves from an echo voltage.SOLUTION: A transmission unit modulates the phase of a drive signal 11 into a phase different from that of a drive signal 11 when the transmission started, during transmission of the drive signal 11, so that a phase detection unit detects change in phase of a received signal. This means that, when the phase detection unit detects change in phase of the received signal (t), the received signal contains a received signal 14 generated by reflection waves. Thus, according to the ultrasonic sensor of the present invention, a ranging unit can detect reception of reflection waves from a detection target based on a detection result of the phase detection unit even when the reception signal 14 generated by reflection waves from the detection target is received while an echo voltage 13 still remains, such as when reflection waves from a detection target in the vicinity (of a transceiver) of the ultrasonic sensor are received.</p> |
