| 摘要 |
PROBLEM TO BE SOLVED: To switch a transmitter and a receiver without thermal noise and without energy loss by constituting a circuit for stopping flowing of a transmission signal to the receiver by using a capacitor or an inductor without using a resistor. SOLUTION: In a transmitter-receiver switching circuit 24 between a transmitter 10, an ultrasonic transducer 12 and a receiver 14 in an ultrasonic flaw detector or the like, for example, inductors L1 to L3 and capacitors C1 to C4 constitute a transmission side band pass filter 26, and inductors L4, L6 and capacitors C3, C4 constitute a reception side band pass filter 28. When transmitted, a part of transmission signals from the transmitter 10 is passed through the capacitor C4, but short-circuited by a diode 18 to protect the receiver 14. The filters 26, 28 are respectively constituted as tertiary and secondary Butterworth filters respectively having desired flat band pass regions, and do not deteriorate frequency characteristics when transmitted and received. |
