| 摘要 |
PROBLEM TO BE SOLVED: To measure the tension of a diaphragm safely and with high reliability even in a noisy place. SOLUTION: The method for measuring the tension of the diaphragm by measuring the tension from a resonant frequency using the diaphragm for a condenser microphone as the diaphragm 1 to be measured includes steps of: hermetically fitting a dynamic headphone unit 20 in the opening 12 of a sealed box 10 so that a sounding diaphragm 21 faces inside the sealed box 10; arranging the diaphragm 1 to be measured in the backside of the magnetic circuit 23 of the headphone unit 20 to form a sealed space; vibrating the sounding diaphragm 21 by applying an alternating current signal in a frequency variable state from a constant voltage alternating current signal generating part to a voice coil 213; and measuring, as the resonant frequency of the diaphragm 1 to be measured, the frequency of the alternating current signal when the voltage between both terminals of the voice coil 213 measured by a voltage measuring means 40 shows the maximum value. COPYRIGHT: (C)2011,JPO&INPIT
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