| 摘要 |
<p>A sound collector comprises switch means (55) for selecting one of the microphones (50a, 50b) directed to sound collection objects (60, 65) the angle between which is &thetas;. The microphone is an optical microphone comprising a diaphragm (2), a light source (3) for irradiating the diaphragm (2), a photodetector (5) outputting a vibration signal of the diaphragm (2), a light source driving circuit (13), and a negative feedback circuit (100) for supplying the output from the photodetector (5) to the light source driving circuit (13). The difference of the sensitivity between the sound collecting objects is eliminated by selecting one of the microphones through the switch means (55) and thereby changing the amount of negative feedback. <IMAGE></p> |
