Patent ID: 8905934

Claim:
An ultrasound transducer comprising: a laminated piezoelectric material having n piezoelectric material layers, where n is an integer of 3 or more, each having an equal thickness, and electrodes between the piezoelectric material layers and on both end surfaces of the laminated piezoelectric material for input and output of an electrical signal, each of the piezoelectric material layers having a remanent polarization in a thickness direction, and a de-matching layer provided on an opposite surface side of a transmission of an ultrasound wave, wherein the de-matching layer has a larger acoustic impedance than the laminated piezoelectric material and reflects a vibration propagated from the laminated piezoelectric material to the de-matching layer side, wherein the ultrasound transducer resonates by a thickness stretch of the piezoelectric materials, a relationship between a direction of an electrical displacement by the direct piezoelectric effect or a direction of an electrical field of a piezoelectric material generated by a voltage applied to the electrodes and a direction of the remanent polarization in the (4P+1)th layer from the de-matching layer side, where P is 0 or a positive integer, is defined as a basic relationship, and piezoelectric material layers are periodically arranged so that (4P+2)th layer of the piezoelectric materials, adjacent to (4P+1)th layer, and (4P+3)th layer thereon each has an opposite relationship to the basic relationship, and (4P+4)th layer has the same relationship as the basic relationship.