JPS5485713A - Ultrasonic wave converting method - Google Patents

Abstract

PURPOSE:To produce good parallel ultrasonic wave beams by applying high frequency signals while subsequently changing over electrodes to grating form electrodes of a uniform period. CONSTITUTION:A piezoelectric material having grating form electrodes combining Cr and Al is provided in a vessel containing liquid such as water, ether or other. If these electrodes are alternately interdigitally disposed to provide the signale phase electrodes applying AC signal to terminals (c) and ai and the 3 phase electrides applying 3 phase AC signal from terminals ai, bi, ci by connecting the interdigitally constituted electrodes at every third one (every fourth one in the case of n phase), then two ultrasonic waves are obtainable in both directions in the case of the signale phase electrodes and one in the single direction in the case of the 3 phase electrodes, respectively. The relations of the period (d) of the electrodes and the direction theta of the maximum output of the ultrasonic beams becomes sintheta=lambdaf/d where lambdaf is let to be the wavelength in the liquid of the acoustic wave of the frequency (f) and therefore if the period (d) is made uniform, the parallel ultrasonic beams of good angle theta direction may be generated from the grating form electrodes.