| 摘要 |
PROBLEM TO BE SOLVED: To provide an ultrasonic sensor which suppresses noise radiated from a transmission line. SOLUTION: A controller part 20 is equipped with a power supply circuit 22 which supplies electric power to a sensor head part 10, an oscillation circuit 21 which outputs a transmission drive signal, a superposing circuit 26 which superposes the transmission drive signal on the source voltage supplied from the power supply circuit 22, and an amplitude limiting circuit 22 which limits the amplitude of the transmission drive signal outputted to the sensor head part 10 while superposed on the source voltage to less than the source voltage value of the power supply circuit 22. Thus, the amplitude of the transmission drive signal is limited to a small amplitude and then the noise radiated from the transmission line 1 can be suppressed.
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