EP0065746A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Condenser microphone
Assignee: Toshiba Corp
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Filing: 1982-05-18
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Granted: —
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Expires: 2002-05-18
Abstract
Abstract A condenser microphone including an electrostatic transducer (100) provided with at least one conductive vibrating plate (101) and at least one fixed electrode (103, 104) arranged opposite the vibrating plate (101), and through which output voltages can be obtained in response to an acoustic input, and an impedance converter circuit (200) connected to output terminals of electrostatic transducer (100), wherein said electrostatic transducer (100) is arranged in such a way that two output voltages (V l , V 2 ) out of phase with respect to each other are obtained through its first and second output terminals (111, 112), and said impedance converter circuit (200) includes first and second field effect transistors (201, 202) of same conductivity channel type whose gates (G) are connected to output terminals (111,112) of electrostatic transducer (100), respectively, and whose drains (D) are connected to a DC power supply (205), first and second impedance elements (203, 204) connected between gates (G) of field effect transistors (201, 202) and ground to hold the DC potential of each gate (G) at ground level, and an output circuit means (206) for generating an output signal corresponding to the difference between source potentials of field effect transistors (201, 202).
Inventors
- 👤 Masanori Tanaka
- 👤 Kenjiro Endoh
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-01 00:44
CPC Classifications
H; H04; H04R; H04R19/00; H04R19/01; H04R19/016; H04R3/00
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
260 words
A condenser microphone including an electrostatic transducer (100) provided with at least one conductive vibrating plate (101) and at least one fixed electrode (103) arranged opposite the vibrating plate (101), and through which output voltages are obtained in response to an acoustic input, and an impedance converter circuit (200) connected to an output terminal (111-113) of said electrostatic transducer (100), characterized in that said electrostatic transducer (100) has a first output terminal (111) and a second output terminal (112) and is so arranged that two output voltages out of phase with respect to each other are obtained through said first and second output terminals (111, 112), and that said impedance converter circuit (200) includes a first field effect transistor (201) and a second field effect transistor (202) both of the same conductivity channel type, gates of said first and second field effect transistors (201, 202) being connected to the first and second output terminals (111, 112) of said electrostatic transducer (100), respectively, and drains of said first and second field effect transistors (201, 202) being connected to a DC power supply (205), a first impedance element (203) and a second impedance element (204) both connected between the gate of said first field effect transistor (201) and ground and between the gate of said second field effect transistor (202) and ground, respectively, to hold the DC potential of each gate at ground level, and output circuit means (206) for generating an output signal corresponding to the difference between the source potentials of said first and second field effect transistors (201, 202).
Claim 2
Dependent Claim
260 words
A condenser microphone including an electrostatic transducer (100) provided with at least one conductive vibrating plate (101) and at least one fixed electrode (103) arranged opposite the vibrating plate (101), and through which output voltages are obtained in response to an acoustic input, and an impedance converter circuit (200) connected to an output terminal (111-113) of said electrostatic transducer (100), characterized in that said electrostatic transducer (100) has a first output terminal (111) and a second output terminal (112) and is so arranged that two output voltages out of phase with respect to each other are obtained through said first and second output terminals (111, 112), and that said impedance converter circuit (200) includes a first field effect transistor (201) and a second field effect transistor (202) both of the same conductivity channel type, gates of said first and second field effect transistors (201, 202) being connected to the first and second output terminals (111, 112) of said electrostatic transducer (100), respectively, and drains of said first and second field effect transistors (201, 202) being connected to a DC power supply (205), a first impedance element (203) and a second impedance element (204) both connected between the gate of said first field effect transistor (201) and ground and between the gate of said second field effect transistor (202) and ground, respectively, to hold the DC potential of each gate at ground level, and output circuit means (206) for generating an output signal corresponding to the difference between the source potentials of said first and second field effect transistors (201, 202).
Claim 3
Dependent Claim
41 words
A condenser microphone according to claim 1, wherein said electrostatic transducer (100) includes two fixed electrodes (103, 104) arranged on both sides of a sheet of vibrating plate (101) and connected to said first and second output terminals (111, 112), respectively.
Claim 4
Dependent Claim
14 words
A condenser microphone according to claim 2, wherein said vibrating plate (101) is grounded.
Claim 5
Dependent Claim
95 words
A condenser microphone according to claim 1, wherein said electrostatic transducer has a first vibrating plate (101), a second vibrating plate (102), a first fixed electrode (103) and a second fixed electrode (104), said first and second fixed electrodes being interposed between said first and second vibrating plates, wherein one of said first vibrating plate (101) and said first fixed electrode (103) is connected to said first (111) or second (112) output terminal, and wherein one of said second vibrating plate (102) and said second fixed electrode (104) is connected to the remaining output terminal.
Claim 6
Dependent Claim
42 words
A condenser microphone according to claim 4, wherein those of said first and second vibrating plates (101, 102) and said first and second fixed electrodes (103, 104) which are not connected to said first or second output terminal (111, 112) are grounded.
Claim 7
Dependent Claim
44 words
A condenser microphone according to claim 1, 2, 3, 4 or 5, wherein said electrostatic transducer has at least one electret (105) and a DC bias voltage is applied between the vibrating plate (101, 102) and the fixed electrode (103, 104) by said electret.
Claim 8
Dependent Claim
29 words
A condenser microphone according to claim 6, wherein said electret (105) is bonded to that side of said fixed electrode (103, 104) which faces the vibrating plate (101, 102).
Claim 9
Dependent Claim
31 words
A condenser microphone according to claim 1, 2, 3, 4, 5, 6 or 7, wherein said electrostatic transducer is covered by a conductive electrostatic shield member (121, 122) which is grounded.
Claim 10
Dependent Claim
18 words
A condenser microphone according to claim 1, wherein said first and second impedance elements (203, 204) are resistors.
Claim 11
Dependent Claim
18 words
A condenser microphone according to claim 1, wherein said first and second impedance elements (231, 232) are inductors.
Claim 12
Dependent Claim
48 words
A condenser microphone according to claim 1, wherein said output circuit means includes a transformer (206) whose primary coil (207) is connected between the sources of said first and second field effect transistors (201,202), and output signals are obtained through a secondary coil (208) of said transformer (206).
Claim 13
Dependent Claim
27 words
A condenser microphone according to claim 11, wherein said primary coil (207) of said transformer has an intermediate tap (P) thereon, and said intermediate tap is grounded.
Claim 14
Dependent Claim
36 words
A condenser microphone according to claim 11, wherein said output circuit means further includes two resistors (221, 222) and the sources of said first and second field effect transistors (201, 202) are grounded through said resistors.
Claim 15
Dependent Claim
53 words
A condenser microphone according to claim 1, wherein said output circuit means includes two inductors (231, 232) connected between the source of said first field effect transistor (201) and ground and between the source of said second field effect transistor (202) and ground, respectively, and an output signal is generated accross said sources.
Claim 16
Dependent Claim
52 words
A condenser microphone according to claim 1, wherein said output circuit means includes two resistors (241, 242) connected between the source of said first field effect transistor (201) and ground and between the source of said second field effect transistor (202) and ground, and an output signal is generated across said sources.
References Cited (Backward Citations)
No citation records indexed.
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