ELECTRET CAPACITOR MICROPHONE

摘要

PROBLEM TO BE SOLVED: To solve the problem in a conventional electret capacitor microphone that it is difficult to enhance detection sensitivity by preventing stray capacitance of a back electrode and the nonoperating region of a diaphragm or a capacitance loss due to an acoustic hole. SOLUTION: The electret capacitor microphone comprises a back electrode substrate having an electret layer formed on a back electrode, and a diaphragm unit having a diaphragm bonded to a supporting frame which are laid in layer through a spacer. The back electrode substrate comprises an insulation substrate on which the back electrode, the electret layer and an acoustic hole are formed wherein stray capacitance or capacitance loss is prevented by providing at least a part of the acoustic hole on the outside of a region for forming the back electrode.