| 摘要 |
<P>PROBLEM TO BE SOLVED: To obtain a capacitor microphone which makes sensitivity adjustment possible without the need for changing a voltage between a diaphragm and a fixed pole, and is free of electrostatic attraction of the diaphragm and a fluctuation in acoustic characteristics due to sensitivity adjustment. <P>SOLUTION: The capacitor microphone includes: a capacitor microphone unit 5 which does electroacoustic conversion by a change in electrostatic capacitance between a diaphragm 52 and a fixed pole 51; a non-inverting amplifier 1, connected to one of the diaphragm 52 and the fixed pole 51, which includes an impedance converter to convert the output impedance of the microphone unit 5 into low impedance; an inverting amplifier 2 which accepts as its input the output signal of the non-inverting amplifier 1 via an input resistor R10 and which also has a feedback resistor R11; and a variable resistor VR, connected between the outputs of the non-inverting amplifier 1 and the inverting amplifier 2, which has its slider connected to either the diaphragm 52 or the fixed pole 51 which is not connected to the non-inverting amplifier 1. Sensitivity changes depending on the slider position of the variable resistor VR. <P>COPYRIGHT: (C)2013,JPO&INPIT |
