PURPOSE: To take out an efficient vibration by setting the overall length of a longitudinal-torsional composite ultrasonic vibrator so that the overall length takes respectively specific values relative to longitudinal and torsional vibrations. ;CONSTITUTION: A longitudinal-torsional composite ultrasonic vibrator is formed when metal blocks 10 composed of e.g. duralumin are arranged on both sides of a ring electrostrictive element 2 and the ring electrostrictive element 2 is held between the metal blocks. Then, the overall length of the longitudinal- torsional composite ultrasonic vibrator is set so as to be almost 3/2 wavelength×N of longitudinal vibration or almost 5/2 wavelength×N of torsional vibration. In this case, N is an integer. When the overall length is set in this manner, longitudinal and torsional vibration modes can match with each other and the maximum amplitude can be generated in the end face. Thus, it is possible to take out an efficient vibration.;COPYRIGHT: (C)1994,JPO
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