PIEZOELECTRIC ELEMENT, OSCILLATORY WAVE MOTOR, AND OPTICAL APPARATUS

摘要

A piezoelectric element that can decrease the output voltage for detection relative to the input voltage for driving without requiring a step-down circuit between a detection phase electrode and a phase comparator and an oscillatory wave motor including the piezoelectric element are provided. A piezoelectric element (20) includes a piezoelectric material having a first surface and a second surface, a common electrode (2) disposed on the first surface, and a drive phase electrode (3) and a detection phase electrode (8)disposed on the second surface. An absolute value d(1) of a piezoelectric constant of the piezoelectric material in a first portion sandwiched between the drive phase electrode (3) and the common electrode (2) and an absolute value d(2) of a piezoelectric constant of the piezoelectric material in a second portion sandwiched between the detection phase electrode (8) and the common electrode (2) satisfy d(2) < d(l). An oscillatory wave motor includes this piezoelectric element.