| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To obtain a stereo microphone in which a power supply circuit does not serve as a noise source and a resistance serves as neither a load of an amplifier nor a noise source, and the angle to be formed mutually between right and left directional axes is made variable. <P>SOLUTION: An output circuit of a bidirectional side microphone element 20 includes an inverting amplifier 25 inverting a phase and outputting an inverted signal, adds a non-inverted output signal of the side microphone element 20 to an output signal of a middle microphone element 10 having unidirectivity to produce a signal for one channel of the right and left channels; and adds an inverted output signal of a side microphone element 20 being the output signal from the inverting amplifier 25 to the output signal of the middle microphone element 10 to produce another signal for the other channel. An input resistor and a feedback resistor to the inverting amplifier 25 are dividable. The division ratio of the input resistor to the feedback resistor is varied to change the levels of the non-inverted output signal of the middle microphone element 10 and the inverted output signal of the side microphone element 20, and to change the angle between the right and left directional axes. <P>COPYRIGHT: (C)2011,JPO&INPIT</p> |
