DEVICE WITH ELEMENT HAVING CAPACITANCE

摘要

PROBLEM TO BE SOLVED: To provide a technique capable of detecting more accurately than before change of the capacitance of an element in a device such as an electromechanical conversion device using change of the capacitance.SOLUTION: A device such as an electromechanical conversion device comprises: an element 109 having a cell 106; first application means 111 for applying a DC voltage between electrodes; and second application means 112 for applying a detection signal to detect the capacitance of the element to one of the electrodes. A signal conversion unit 114 converts a current signal output from the other electrode into a voltage signal. A band rejection filter unit 113, disposed between the other electrode and the signal conversion unit, has a cutoff frequency in a frequency region outside the main band of the current signal generated at the other electrode by the vibration of a vibration film due to reception of an acoustic wave.