To provide an apparatus for measuring membrane stiffness, which can measure the stiffness of a vibrating diaphragm of an ECM or MEMS microphone inexpensively, simply, and nondestructively.
The apparatus includes: a vacuum container 10 that retains a completed ECM 20 in vacuum; a voltage source 30 that functions to overlap an excitation voltage with a direct-current voltage for operating the ECM 20; an input-output response measuring unit 40 for measuring the voltage and phase of a power supply terminal B that is connected to an FET 72 of the ECM 20 with respect to the excitation voltage; and a stiffness calculation unit 50 for calculating a resonant frequency from the frequency response characteristic thus measured, and for calculating the membrane stiffness of the vibrating diaphragm 105 from the resonant frequency.
Toshimitsu Ichikawa
Kimihide Hashimoto