Dependence of the electromechanical coupling coefficient on the width-to-thickness ratio of plank-shaped piezoelectric transducers used for electronically scanned ultrasound diagnostic systems

Abstract

A finite element analysis method is used to obtain the electromechanical coupling coefficient ke for plank-shaped piezoelectric transducers with a width W to thickness T ratio of not more than two. Calculation results for typical piezoelectric ceramics show that there exist maximum values of ke at certain values of W/T. For PCM-5R material the maximum value of ke is 0.69 at a W/T of 0.6. It is shown that only one vibrational mode is very strongly coupled around this value of W/T. This vibrational mode is very useful for application to electronically scanned arrayed transducers.