JPS5686524A - Torsional oscillation type electromechanical conversion element - Google Patents

Abstract

PURPOSE:To suppress the even order harmonics specific to mechanical oscillator, by providing the fine wire having the length suppressing the even number harmonics on the circle near the center of the circular cylinder lengthwise, of the torsional type conversion element. CONSTITUTION:A flat plate 3 having piezoelectric effect is provided between metal rods 1 and 2, and electric signal input terminals 4 and 5 are located at both ends, to constitute a columnar torsional oscillation type electromechanical conversion element. Further, at the point (b) on the circumference near the center lengthwise the circular column cylinder of the conversion element, a fine wire 6 for unnecessary oscillation wave suppression is mounted with the method such as electric welding. In this case, when the oscillation of the conversion element is the basic wave, the suppressed fine wire 6 is mounted on the node of oscillation and no effect is given to the said oscillation, but if the even number harmonics, the wire 6 is on the top of the oscillation and subjected to the effect. Thus, the even number harmonics can be suppressed by selecting the length of the suppressed fine wire 6 to that the harmonics propagate in the wire 6 as longitudinal oscillation wave at the loading position (b), they reflect at the free end (c), the amplitude and phase of the reflected wave reaching the position (b) is in agreement with the progressing wave to be opposite phase.