Patent ID: 7697702
Filing Date: 2010-04-13
Classification: H04R

Abstract:
1. A condenser microphone comprising: a phantom power source as a predetermined DC power source, a proximity sensor including an infrared light emitting diode and an infrared photodetector, the infrared light emitting diode being lighted at a predetermined frequency by an oscillation circuit using an AC component, a microphone output turned on and off by an output signal from the infrared photodetector which is tuned to a predetermined frequency, and two DC-DC converters connected in parallel with the DC power source, one of the DC-DC converters supplying power to the infrared light emitting diode and the oscillation circuit, and the other DC-DC converter supplying power to the infrared photodetector wherein said two DC-DC converters are switched capacitor voltage converters as a half voltage drop type and are connected in parallel with feeding line from the phantom power source via constant current diodes, to separate the power supply lines.