Condenser microphone
US4491697A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 13, 1982 |
| Grant date | Jan 1, 1985 |
| Priority date | — |
| Expiry date | May 13, 2002 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04R3/00
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A condenser microphone including an electrostatic transducer provided with at least one conductive vibrating plate and at least one fixed electrode arranged opposite the vibrating plate, and through which output voltages can be obtained in response to an acoustic input, and an impedance converter circuit connected to output terminals of electrostatic transducer, wherein said electrostatic transducer is arranged in such a way that two output voltages out of phase with respect to each other are obtained through its first and second output terminals, and said impedance converter circuit includes first and second field effect transistors of same conductivity channel type whose gates are connected to output terminals of electrostatic transducer, respectively, and whose drains are connected to a DC power supply, first and second impedance elements connected between gates of field effect transistors and ground to hold the DC potential of each gate at ground level, and an output circuit means for generating an output signal corresponding to the difference between source potentials of field effect transistors.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.