US3190972A - Condenser microphone - Google Patents
Condenser microphone Download PDFInfo
- Publication number
- US3190972A US3190972A US205667A US20566762A US3190972A US 3190972 A US3190972 A US 3190972A US 205667 A US205667 A US 205667A US 20566762 A US20566762 A US 20566762A US 3190972 A US3190972 A US 3190972A
- Authority
- US
- United States
- Prior art keywords
- air
- microphone
- volume
- membrane
- housing structure
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R19/00—Electrostatic transducers
- H04R19/04—Microphones
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R1/00—Details of transducers, loudspeakers or microphones
- H04R1/20—Arrangements for obtaining desired frequency or directional characteristics
- H04R1/32—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only
- H04R1/34—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only by using a single transducer with sound reflecting, diffracting, directing or guiding means
- H04R1/38—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only by using a single transducer with sound reflecting, diffracting, directing or guiding means in which sound waves act upon both sides of a diaphragm and incorporating acoustic phase-shifting means, e.g. pressure-gradient microphone
Definitions
- the invention includes a condenser microphone, comprising, in combination, a housing structure; a membrane mounted in said housing structure and having a front face facing the front side thereof and being adapted to constitute one condenser electrode; a counter electrode mounted in said housing structure at a predetermined spacing from the rear face of said membrane and insulated therefrom; means for conice fining a predetermined volume of air at the rear side of said membrane within said housing structure; and adjustment means for varying the directional characteristic of the microphone and including adjustable connection means for selectively controlling the connection between said volume of air and the outside air at the rear side of said housing structure which includes restricting said connection and establishing a substantially friction-free connection between said volume of air and said outside all.
- FIG. 1 is a diagrammatic cross-sectional elevation of one embodiment of the invention
- FIG. 2 is a plan view in direction of the arrow II of the counter electrode in the arrangement of FIG. 1;
- FIG. 3 is a diagrammatic cross-sectional elevation of a second embodiment of the invention.
- FIG. 4 is a similar view of a further embodiment of the invention.
- FIG. 5 is a similar view of one more embodiment of the invention.
- FIG. 6 is a similar view of a further modified embodiment of the invention.
- a membrane 1 is attached to a cylindrical housing 3 by means of a holding ring 2.
- These members may be assembled in any suitable and conventional manner e.g. by soldering, screwing or clamping.
- the membrane 1 faces one side of the housing 3 so as to be in direct contact with the surrounding air in front of the housing.
- a counter electrode 4 usually called the back plate is supported in the housing 3 by means of an interconnecting insulating annular member 6.
- the counter electrode 4 is provided at its rear or outer side with a threaded stud 5.
- the membrane 1 made entirely or in part of electrically conductive material and the metallic back plate 4 constitute the two electrides of a condenser. Leads for connecting the two electrodes in a circuit are not shown in the drawings because they have no significance for this invention.
- a disc member is mounted so as to surround the stud 5 with a central bore fitting over the latter.
- the disc 8 has a preferably cylindrical recess 8 on its rear or outer side and a further preferably cylindrical recess 8 at its other side which faces the rear side of the counter electrode 4.
- the recess 8 is surrounded by a rim composed of comparatively short portions 9 projecting toward and abutting against the rear face of the counter electrode 4, openings 10 being left between consecutive projecting portions 9.
- a further disc member 11 with an interior thread is screwed onto the threaded portion of the stud 5 and holds the disc 8 firmly in its shown position.
- the counter electrode 4 is provided with a plurality of perforations 7 which are distributed over the entire area thereof in dilferent manners, e.g. in different numbers along different circles concentric with the center of the member 4 as can be seen clearly from FIG. 2.
- the perforations 7 in the outer marginal zone of the surface of the member 4 are more numerous and more closely spaced than the perforations 7 nearer to the center.
- a ring member 12 is mounted slideably in axial direction on the cylindrical circumference of the disc 8.
- the ring 12 is provided at its side facing the rear surface ofthe counter electrode 3 4 with a recess 13 which provides an annular air space communicating both with the marginal row or rows of perforations 7 and with the air space 16 in the recess 8 through the above-mentioned openings 10.
- a shallow recess 14 is provided in the margin of the disc 11 on the side thereof adjacent to the outer surface of the disc 8. The latter is provided with a plurality of perforations 15 which constitute a connection between the recess 14 and the above-mentioned air space 16.
- a ring member 18 is mounted slideably in axial direction on the cylindrical circumference of the disc 11 so as to be movable between the illustrated position in which the ring 18 abuts against a shoulder 20, and a second position in which the opposite face of the ring 18 abuts against the rear surface of the disc 8 in the recess 8' so as to close in this position the connection between the outer air and the recess 14.
- the microphone thus described is so constructed that alternatively and selectively three different directional characteristics of the microphone can be adjusted by purely mechanical means.
- the entire-air volume; existing behind the membrane 1 acts as an elastic stiffening cushion. It is easy to choose the shape and dimension of this air volume in designing the microphone in such a manner that the cooperation of that elastic stiffening cushion with the other elements of the oscillatory system especially the mass of the membrane complies with the well-known conditions of a pressure responsive microphone.
- the microphone according to the invention has a spherical directional characteristic.
- the ring 12 is shifted in the direction of the arrow a from the illustrated position to a second position determined by the abutment 19, then the air volume behind the membrane 1 is in communication with the sound field behind the microphone so that in addition to the .sound impinging on the forward face of the membrane 1 also sound from the rear of the microphone can reach the rear side of the membrane 1.
- the microphone has now an 8-shape or substantially 8-shape directional characteristic. In this setting of the microphone it is practically immaterial whether the ring 18 is in the position illustrated in FIG. 1 or in its other end position.
- the frictional element formed by the annular recess 14 constitutes a predetermined constant factor
- the inside of the ring 13 could be threaded and cooperate with an outside thread on the circumference of the disc 11 so that by turning the ring 18 any desired adjustment of the access to the recess 14 can be achieved.
- the counter electrode 4 in its marginal zone cooperating with the ring 12 with a comparatively large number of perforations.
- the same effect may be obtained by giving the individual perforations in the marginal zone comparatively large cross-section.
- Such an arrangement is illustrated by way of example in FIG. 2.
- FIG. 3 which illustrates another embodiment of the invention all those elements which are identical with those shown in FIGS. 1 and 2 are designated by the same reference numerals.
- a disc 21 is mounted behind the counter electrode 4 and is held in assembled position by being threaded onto a threaded portion of the stud 5.
- Thedisc 21 is provided on the side facing the rear face of the member 4 with a recess 22 surounded by a continuous rim 2.3 abutting against the insulating ring 6 and fitting the circumference of the member 4.
- the ring 21 is provided with large openings 24.
- the outer smooth end of the stud 5 carrie a disc 25 which is slideable in axial direction along the portion 5 of the stud 5.
- the disc 25 In the illustrated position of the disc 25 a portion of its inner face abuts against the outer face of the disc 21.
- the other outer end position of the disc 25 is determined by a snap ring 26.
- the inner face of the disc 25 is provided with a shallow recess 27 which establishes in this position a narrow access for sound from the outside air in the rear of the microphone to the openings 24.
- the disc 25 serves to establish in the illustrated position a friction through the narrow path across recess 27 left between the opposing faces of the disc 25 and the disc 21. If, however, the disc 25 is moved in the direction of the arrow 0 into its other end position then the surrounding air behind the microphone communicates freely through the openings 24 with the air volume otherwise existing behind the membrane 1 so that in this setting of the microphone an 8-shape or predominantly S-shape directional characteristic of the microphone is obtained. In this embodiment only two alternative settings of the microphone are provided.
- a sound-permeable plate 28 is mounted on top of the holding ring 2.
- This plate may be perforated or may be may for example of metal mesh or fabric or any other suitable porous material.
- An air volume 29 exists between the plate 28 and the membrance 1.
- the embodiment according to FIG. 3 may be slightly modified by not providing the recess 27 in the disc 25.
- its rear face would abut entirely in the shown position of disc 25 against the outer face of the disc 21 and completely close the openings 24.
- the air volume existing behind the membrane 1 would be completely closed off against the outside air.
- a microphone is obtained which has, in one position of the disc 25, not a unidirectional characteristic but a spherical characteristic, and in the other position of the disc 25 an S-shape directional characteristic.
- the embodiment according to FIG. 3 is based on the concept that a disc 25 is'shifted to an end position in which a friction-free connection between the outside air in the rear of the microphone with the air volume existing behind the membrane is established whereby the microphone is set for an 8-shape directional characteristic. It was further understood that the disc 25 is either provided with a recess 27 for establishing a frictional element or is formed without this recess 27 so as to be able to completely close in the illustrated position the openings 24.
- FIG. 4 illustrates a modification in which a member corresponding to the disc 25 is stationarily mounted on the stud 5 while a separate perforated disc is shiftable between a position in which free access of the outside air to the membrane or a frictional element can be established.
- a disc 31 is screwed onto the threaded portion of the stud 5 and held in that position for instance by a nut 5".
- a disc 32 having small perforations 37 at a certain radial distance from the center and larger perforations 33 at a lesser distance from the center is shiftable in axial direction between a position, as illustrated, in which its outer face abuts against the inner face of the disc 31, and a position in which the slightly projecting inner rim of the disc 32 abuts against the outer face of the counter electrode 4.
- the variable air volume 34 between the counter electrode 4 and the disc 32 is confined by a projecting rim 35 of the counter electrode 4 which fits closely over the circumference of the disc 32.
- the microphone has the desired 8-shape directional characteristic. If the latter is to be changed to a unidirectional characteristic then the disc 31 is to be provided with a shallow recess 36 cooperating with the small perforations 37 so that in the illustrated position of disc 32 only a predetermined narrow path for sound waves from the rear of the microphone to the inner air volume behind the membrane 1 is provided.
- the separate narrow perforations 37 may also be omitted in which case the shallow recess 36 has to extend so much toward the center of the microphone that, in the same manner as in FIG. 3, the recess 36 communicates with the openings 33.
- FIG. 5 illustrates a further embodiment in which the characteristic of the microphone can be changed between unidirectional characteristic and 8-shape directional characteristic.
- the member 41 designed to constitute the rearward boundary of the air volume existing behind the membrane 1 is held in the illustrated position on the stud 5 by a disc 42 screwed onto the threaded portion of stud 5 whereby the outer rim of member 41 is caused to abut against the insulating ring 6 while also fitting closely over the circumference of the counter electrode 4.
- the disc 42 is provided with a shallow recess 43 communicating with correspondingly positioned perforations 41' in the member 41. In this manner a friction element for producing a unidirectional characteristic is provided for.
- the member 41 is provided in its marginal area with large perforations 44 communicating with the air volume behind the membrane 1 and closed against the outside air in the rear of the microphone by a ring member 46 when the latter is in the illustrated position.
- the ring member 46 is slideable in axial direction along the circumference of the annular portion 45 of member 41. If the ring 46 is moved from the illustrated position in the direction of the arrow 2 to end position determined by the shoulder 45, then a practically friction free connection of the outside air behind the microphone through openings 44 with the inner air volume behind the membrane 1 is established.
- the desired 8-shape directional characteristic is obtained.
- FIG. 5 illustrates a further modification of the arrangement according to the invention so as to show by way of example that this microphone may also be operated in push-pull fashion.
- a second counter electrode 48 with perforations 49 is mounted opposite the front face of the membrane 1 and is supported by an insulating ring 47 arranged on the holding ring 2. It will be understood that this second counter electrode 48 may also be formed in such a manner that it may simultaneously serve as an element producing a phase shift of the sound waves impinging on the front face of the membrane 1.
- the movable elements are moved either by hand or by mechanical means not shown. However, it may be sometimes desirable to adjust the microphones and to move the movable elements by remote control.
- the members 12 and 18 of FIG. 1 or the movable elements of the other embodiments may be made of ferromagnetic material and may be moved into one of their positions by the application of a magnetic field against the action of an elastic returning force or element so that they are returned to their other position upon the disappearance of the magnetic field.
- FIG. 6 illustrates by way of example a microphone according to the invention which can be operated with remote control.
- the structure of the microphone according to FIG. 6 is analogous to that illustrated by FIG. 1.
- solenoid coils 51 and 52 are provided and so arranged that upon energization thereof the ferromagnetic members 12 and 18, respectively, are moved in the direction of the arrows 7 and g, respectively, against the elastic resistance of the members 53 and 54, respectively, e.g. rubber rings.
- the dimensionsof the cooperating parts are so chosen that the elastic force of the members 53 and '54 is sufficient for moving the members 12 and 18, respectively, safely into the closing positions illustrated in FIG.
- stereophonic sound recording or transmission tw-o microphones may be combined with each other in a manner generally known per se in which case the two microphones are preferably set for reception in two different directions and are arranged closely adjacent to each other and preferably one above the other in order to determine in this way a more or less common reference point.
- a condenser microphone comprising, in combination,
- a condenser electrode including an at least partly conductive membrane mounted in said housing structure and having a front face facing the front side thereof;
- a counter electrode mounted in said housing structure 7 at a predetermined spacing from the rear face of said membrane; 7
- first air passage means for establishing a restricted connection between said volume of .air and the outside air at the rear of said'housing structure
- mechanical adjustment means for varying the directional characteristic of the microphone including movable control means which in a first position render said second air passage means inoperative and leave said first air passage means operative only to a predetermined degree so that the microphone obtains a directional characteristic depending upon said degree of operativeness of said first air passage means and which in a second position render said second air passage means operative so that irrespective of the operative condition of said first air passage means a 'bi-directional 8-shape characteristic of the microphone is established by the friction-free connection between said volume of air and said outside air.
- said housing structure includes a stationary closure member along its rear side and defining an air space between itself and the rear face of said counter electrode, said counter electrode and said closure member being provided each with a plurality of perforations for establishing a connection from the air immediately behind said membrane and from said air space to said outer air, and wherein said adiustment means include control means movable between a first position in which said volume of air is in substantially friction-free connection with said outside air through at least some of said perforations, and a second position in which said connection is restricted to a predetermined degree.
- said housing structure includes a stationary member mounted on the outside of said closure member and including a narrow channel portion communicating with said perforations of said closure member and with said outside air and located so as to constitute a frictional connection between said volume of air and said outside air when said second control member is in said first position thereof, and to be closed when said second control member is in said second position thereof.
- control means include a control member provided with a narrow channel portion communicating with said perforations of said closure member and with said outside air, said control member being movable between a first posi tion in which said perforations of said closure member are in friction-free communication with said outside air, and a second position in which said perforations are in communication with said outside air only through said channel portion so as to establish a frictional connection between said volurne of air and said outside air.
- a microphone as claimed in claim 2 wherein said closure member is provided with a first group of perforations in one area and a second group of perforations in a second area thereof, narrow channel means being arranged in communication with said second group of perforations of said closure member and with said outside air for establishing a frictional connection between said volume of air and said outside air, and wherein a control member is movable between a first position in which said first group of perforations of said closure member is in friction-free communication with said outside air, and a second position in which said first group of perforations is closed against said outside air.
- said housing structure comprises a stationary member arranged to leave a space between itself and the rear face of said counter electrode and provided with narrow channel means open to said space and to said outside air, said counter electrode being provided with a plurality of perforations, and wherein a control member provided with a plurality of perforations is movable in the space between said rear face of said counter electrode and said stationary member and between a first position in which at least some of said perforations of said control member are in friction-free communication with said outside air, and a second position in which at least some of said perforations of said control member are in communication with said outside air only through said narrow channel means so as to establish a frictional connection between said volume of air and said outside air.
- a microphone as claimed in claim 1 including phase shift means mounted opposite said membrane on the front side of said housing structure for influencing the sound waves impinging on said front face of said membrane.
- a microphone as claimed in claim 1 including a second counter electrode mounted on said housing structure at a predetermined spacing from the front face of said membrane and insulating means for insulating it therefrom, for rendering the microphone operable in pushpull fashion.
- adjustment means include control means movable between two positions and made at least partly of ferromagnetic material, solenoid means energizable for moving 7 said control means from one position in one direction to a second position, and return means for returning said control means from said second to said one position when said solenoid means are de-energized.
- a condenser microphone comprising, in combination,
- a counter electrode mounted in said housing structure at a predetermined spacing from the rear face of said membrane
- first air passage means for establishing a restricted connection between said volume of air and the outside air at the rear of said housing structure
- mechanical adjustment means for varying the directional characteristic of the microphone including movable control means which in a first position render said second air passage means inoperative and blocks said first air passage means so that the microphone obtains said poly-directional characteristic, and which in a second position render said second air passage means operative so that irrespective of the operative condition of said first air passage means a bi-directional 8-shape characteristic of the microphone is established by the friction-free connection between said volume of air and said outside air.
- a condenser microphone comprising, in combination,
- a condenser electrode including an at least partially conductive membrane mounted in said housing structure and having a front face facing the front side thereof;
- a counter electrode mounted in said housing structure at a predetermined spacing from the rear face of said membrane
- first air passage means for establishing a restricted connection between said volume of air and the outside air at the rear of said housing structure
- -mechanical adjustment means for varying the directional characteristic of the microphone and including movable control means which in a first position render said second air passage means inoperative and blocks said first air passage means so that the microphone obtains said poly-directional characteristic, which in a second position render said second air passage means inoperative and leave said first air passage means operative to a degree so restricted as to constitute a frictional connection between said volume of air and said outside air whereby the microphone ob- 5Q is established by the friction-free connection between said volume of air and said outside air.
- a condenser microphone comprising, in combination,
- a condenser electrode including an at least partly conductive membrane mounted in said housing structure and having a front face facing the front side thereof;
- a counter electrode mounted in said housing structure at a predetermined spacing from the rear face of said membrane
- first air passage means for establishing a restricted connection between said volume of air and the outside air at the rear of said housing structure
- mechanical adjustment means for varying the directional characteristic of the microphone including movable control means which in a first position render said second air passage means inoperative and leave said first air passage means operative only to a predetermined degree so restricted as to constitute a frictional connection between said volume of air and said outside air whereby the microphone obtains a substantially unidirectional characteristic, and which in a second position render said second air passage means operative so that irrespective of the operative condition of said first air passage means a bi-directional S-shape characteristic of the microphone is established by the friction-free connection between said volume of air and said outside air.
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- Health & Medical Sciences (AREA)
- Otolaryngology (AREA)
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Acoustics & Sound (AREA)
- Signal Processing (AREA)
- Electrostatic, Electromagnetic, Magneto- Strictive, And Variable-Resistance Transducers (AREA)
- Details Of Audible-Bandwidth Transducers (AREA)
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DESCH29963A DE1171960B (de) | 1961-07-08 | 1961-07-08 | Kondensatormikrophon mit mehreren wahlweise einstellbaren Richtcharakteristiken |
Publications (1)
Publication Number | Publication Date |
---|---|
US3190972A true US3190972A (en) | 1965-06-22 |
Family
ID=7431584
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US205667A Expired - Lifetime US3190972A (en) | 1961-07-08 | 1962-06-27 | Condenser microphone |
Country Status (4)
Country | Link |
---|---|
US (1) | US3190972A (fr) |
DE (1) | DE1171960B (fr) |
FR (1) | FR1371762A (fr) |
GB (1) | GB967088A (fr) |
Cited By (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3418436A (en) * | 1964-07-21 | 1968-12-24 | Neumann Georg | Unidirectional condenser microphone |
US3504137A (en) * | 1965-12-10 | 1970-03-31 | Tesla Np | Condenser microphone with improved acoustical circuit |
US4042438A (en) * | 1974-07-16 | 1977-08-16 | Sony Corporation | Method of assembling a diaphragm assembly for an electro-acoustic transducer |
US4281221A (en) * | 1978-07-12 | 1981-07-28 | Societa Italiana Telecomunicazioni Siemens S.P.A. | Condenser microphone |
US4648480A (en) * | 1984-09-10 | 1987-03-10 | Doryokuro Kakunenryo Kaihatsu Jigyodan | Condenser microphone having resistance against high-temperature and radioactive rays |
US4796725A (en) * | 1981-09-14 | 1989-01-10 | Matsushita Electric Works, Ltd. | Electrostatic transducer |
US6760462B1 (en) | 2003-01-09 | 2004-07-06 | Eminent Technology Incorporated | Planar diaphragm loudspeakers with non-uniform air resistive loading for low frequency modal control |
US8948434B2 (en) | 2013-06-24 | 2015-02-03 | Michael James Godfrey | Microphone |
US9107007B2 (en) | 2010-04-09 | 2015-08-11 | Sennheiser Electronic Gmbh & Co. Kg | Microphone unit |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB1067344A (en) * | 1964-09-11 | 1967-05-03 | Standard Telephones Cables Ltd | Electro-mechanical transducer arrangement |
CN105972251B (zh) * | 2016-07-14 | 2018-05-18 | 康以宣 | 用于气动三通阀的膜片和气动三通阀 |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2387845A (en) * | 1943-06-24 | 1945-10-30 | Bell Telephone Labor Inc | Electroacoustic transducer |
US2852620A (en) * | 1954-08-13 | 1958-09-16 | Schoeps Karl | Adjustable condenser microphone |
US2939922A (en) * | 1955-05-26 | 1960-06-07 | Gorike Rudolf | Directional microphone having a low susceptibility to shock and wind |
US2958739A (en) * | 1954-08-13 | 1960-11-01 | Schalltechnik Dr Ing K Schoeps | Electroacoustic transducer |
Family Cites Families (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE822249C (de) * | 1948-10-02 | 1951-11-22 | Klangfilm G M B H | Kondensator-Mikrophon |
-
1961
- 1961-07-08 DE DESCH29963A patent/DE1171960B/de active Pending
-
1962
- 1962-01-25 GB GB2938/62A patent/GB967088A/en not_active Expired
- 1962-06-08 FR FR7434A patent/FR1371762A/fr not_active Expired
- 1962-06-27 US US205667A patent/US3190972A/en not_active Expired - Lifetime
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2387845A (en) * | 1943-06-24 | 1945-10-30 | Bell Telephone Labor Inc | Electroacoustic transducer |
US2852620A (en) * | 1954-08-13 | 1958-09-16 | Schoeps Karl | Adjustable condenser microphone |
US2958739A (en) * | 1954-08-13 | 1960-11-01 | Schalltechnik Dr Ing K Schoeps | Electroacoustic transducer |
US2939922A (en) * | 1955-05-26 | 1960-06-07 | Gorike Rudolf | Directional microphone having a low susceptibility to shock and wind |
Cited By (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3418436A (en) * | 1964-07-21 | 1968-12-24 | Neumann Georg | Unidirectional condenser microphone |
US3504137A (en) * | 1965-12-10 | 1970-03-31 | Tesla Np | Condenser microphone with improved acoustical circuit |
US4042438A (en) * | 1974-07-16 | 1977-08-16 | Sony Corporation | Method of assembling a diaphragm assembly for an electro-acoustic transducer |
US4281221A (en) * | 1978-07-12 | 1981-07-28 | Societa Italiana Telecomunicazioni Siemens S.P.A. | Condenser microphone |
US4796725A (en) * | 1981-09-14 | 1989-01-10 | Matsushita Electric Works, Ltd. | Electrostatic transducer |
US4648480A (en) * | 1984-09-10 | 1987-03-10 | Doryokuro Kakunenryo Kaihatsu Jigyodan | Condenser microphone having resistance against high-temperature and radioactive rays |
US6760462B1 (en) | 2003-01-09 | 2004-07-06 | Eminent Technology Incorporated | Planar diaphragm loudspeakers with non-uniform air resistive loading for low frequency modal control |
US9107007B2 (en) | 2010-04-09 | 2015-08-11 | Sennheiser Electronic Gmbh & Co. Kg | Microphone unit |
US9197955B2 (en) | 2010-04-09 | 2015-11-24 | Sennheiser Electronic Gmbh & Co. Kg | Microphone unit |
US8948434B2 (en) | 2013-06-24 | 2015-02-03 | Michael James Godfrey | Microphone |
Also Published As
Publication number | Publication date |
---|---|
FR1371762A (fr) | 1964-09-11 |
DE1171960B (de) | 1964-06-11 |
GB967088A (en) | 1964-08-19 |
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