US3201516A - Capsule-enclosed electro-acoustic transducer and transistor amplifier - Google Patents

Capsule-enclosed electro-acoustic transducer and transistor amplifier Download PDF

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Publication number
US3201516A
US3201516A US194265A US19426562A US3201516A US 3201516 A US3201516 A US 3201516A US 194265 A US194265 A US 194265A US 19426562 A US19426562 A US 19426562A US 3201516 A US3201516 A US 3201516A
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US
United States
Prior art keywords
transducer
sound
capsule
diaphragm
sensitivity
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
Application number
US194265A
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English (en)
Inventor
Weingartner Bernhard
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
AKG Acoustics GmbH
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AKG Akustische und Kino Geraete GmbH
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Publication date
Application filed by AKG Akustische und Kino Geraete GmbH filed Critical AKG Akustische und Kino Geraete GmbH
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Publication of US3201516A publication Critical patent/US3201516A/en
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Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; 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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S181/00—Acoustics
    • Y10S181/40—Wave coupling

Definitions

  • This invention relates to an electro-acoustic transducer incorporated in a capsule and comprising a transistor amplifier, particularly for telephone handsets, which transducer, which is in most cases of electro-dynamic type, is of midget size and disposed approximately at the center of an annular disc which is disposed in the capsule and serves as a mounting panel and, if desired, as a circuit panel, for a transistor amplifier.
  • transistor microphone has the same external dimensions as the previously used carbon microphones so that a direct replacement is possible.
  • the transistor microphones have special advantages, such as freedom from distortion, long life etc., they have an important disadvantage compared to carbon microphones in that they are highly sensitive to interfering noise.
  • the carbon microphone is known to have a response threshold such that acoustic signals (sound waves) on a level below a certain threshold cannot be received by the microphone.
  • interfering noise the sound pressure level of which is generally much lower than the signal level, is not transmitted because the vibrating mechanism causes a virtually automatic suppression of noise.
  • the acoustic transducer more particularly electro-dynamic transducer, which is incorporated in the capsule, is designed as a noise-compensating pressure gradient transmitter, the sensitivity of which decreases toward the low frequencies in a plane sound field (noise field) whereas it varies substantially linearly with frequency in a spherical sound field (signal
  • the electro-acoustic transducer incorporated in the capsule is characterized in that the noise-compensating transmitter is a higher-order pressure gradient transmitter of higher order, preferably of second order, and has associated with it a tore-shaped directional pattern, which is obtained by the rotation of an approximately figure eight-shaped, plane figure about its center line at right angles to the longitudinal axis.
  • this is achieved by the provision of coupling volumes disposed before and behind the diaphragm and communicating with the open air by one or more ducts of any desired form and of such lengths that the paths of sound from any possible sound entrance point to both coupling Volumes are at least approximately equal, whereas the joint impedance of the duct or ducts extending from the front side or" the diaphragm is at least approximately equal to the inn pedance of the duct or ducts extending from the rear side of the diaphragm.
  • the attenuation of the noise from remote sources is primarily elfected according to the invention, by the acoustic compensation of the remote field, and that this compensation is considerably assisted by additional features as a result of which the directional pattern is such that the axis of main sensitivity thereof extends toward the mouth of the speaker.
  • FIG. 1 shows a usual directional pattern and PEG. 2 the directional pattern of a transducer according to the invention.
  • FIGS. 3 and 5 are sectional views taken through two illustrative embodiments and FIGS. 4 and 6 are corresponding top plan views.
  • a transducer in which the invention may be embodied and which has the required properties is the known transmitter which is responsive to the particle velocity and the resonant frequency of which lies in the middle of the frequency range to be transmitted, whereas the diaphragm In that case the force acting on the diaphragm increases in proportion with frequency in a plane sound field at least as long as the dimensions of the diaphragm are less than the wavelength of the highest frequency to be transmitted.
  • the sensitivity decreases by 6 decibels per octave in dependence on frequency below a limiting frequency, which is determined by the sound detour, i.e., by the sound path from the center of the front side to the center of the rear side of the diaphragm.
  • the three-dimensional directional pattern of the previously known systems has the shape or" a figure eight, which becomes narrower as the ordinal number increases and which rotates about its longitudinal axis. In a system of first order, this results in a directional pattern which can be represented by two contiguous spheres (FIG. 1).
  • This pattern and that of systems of higher order has the disadvantage that in the planes of section for which zconstant the sensitivity varies according to a figure eight-shaped pattern and that the sensitivity is theoretically zero in the plane of section z:0.
  • a capsule provided with such a transducer cannot be incorporated in the handset in any desired position but the position must be such that the direction of the axis of highest sensitivity (z axis) coincides with the longitudinal axis of the handset.
  • the system proposed by the invention which is of second order and comprises one diaphragm and has a toreshaped directional pattern, is free from this disadvantage.
  • FIG. 2 shows the directional pattern in a three-dimen-l sional showing, a portion being cut out for a better representation of the transverse sectional shape.
  • the shape may be considered obtained by the rotation of a figure eight, which is slenderer because the system is of higher (second) order, about an axis which extends at right angles to the longitudinal axis and through the center, the z axis (FIG. 2) coinciding with the axis of the trans ducer.
  • a transducer having such a pattern as contrasted to the usual form shown in FIG. 1 has the lowest sensitivity in the direction of the z axis, whereby the possibility of a reception of noise from the space is further restricted.
  • the highest sensitivity is in a plane extending at right angles to the longitudinal axis of the handset.
  • FIG. 3 the vibratory system actuated by the sound comprises the circular diaphragm 1 and the moving coil 2 moving in the air gap of a magnet system.
  • Coupling volumes 3 of equal size are provided before and behind the diaphragm. Each of these cavities has one or more sound ducts connected to it.
  • a duct 4 having an opening exactly in the axis of the transducer system leads into the open from the front side of the diaphragm.
  • this duct is equal to the length of the sound path from the rear side of the diaphragm into the open and the acoustic impedance of this duct equals the acoustic impedance of all sound ducts leading to the rear side of the diaphragm.
  • At least four sound ducts 6 extend into the open from. the rear side of the diaphragm and have openings 7 disposed in the same plane as the opening 5 of duct 4.
  • the ducts 6 form corners of a square, through the center of which the axis of the transducer extends.
  • the carrier panel 8 is suitably made from coppercoated insulating plastic for receiving the printed circuit.
  • the panel carries the electrical circuit elements 9, such as transistors, resistors, capacitors etc.
  • the housing 10 provided with the cover 11 has the same standardized dimensions as a carbon microphone.
  • the resulting transducer is a pressure gradient microphone of second order.
  • a pressure gradient microphone of second order will be analogously obtained if the absolute value of the sound pressures and the distances of the openings 7 from the center are of equal size.
  • a cos pattern will also be obtained for voice actuation from all intermediate directions.
  • the directional pattern will be torelike and axially symmetrical with respect to the z axis and its meridian section will be a cos s figure.
  • the mechanical impedance of the vibratory system should be selected so that the frequency response of the transmission level in the plane sound field decreases by 6 decibels per octave toward the low frequencies. This will result in an approximately linear frequency response in a spherical sound field.
  • the mechanical impedance should be mainly a mass, so that the natural frequency of the vibratory system should be at the lower end of the frequency range to be transmitted (mass control).
  • any desired other system e.g., a magnetic, piezoelectric or capacitive system may be coupled to the diaphragm.
  • FIG. 5 shows a modified embodiment of FIG. 3.
  • Analogous references are used. More than four openings 7 may lead to the rear side of the diaphragm. Separate openings may be replaced by an annular passage, which may be intersected by tubular sound ducts. It is essential that the sound paths from any possible sound entrance point to the coupling volumes before and behind the diaphragm are of equal length and that both sound paths have the same acoustic impedance. To obtain directional patterns deviating from the pure cos 3: shape the lengths of the sound paths to the front and rear side of the diaphragm may differ slightly.
  • An electro-acoustic transducer assembly comprising, in combination, an encasing capsule; an annular disc extending completely across said capsule; a transistor amplifier having its components mounted on said disc; a noise compensating pressure gradient transducer disposed substantially within the center opening of said disc; means providing a pair of substantially equal coupling volumes each communicating with respective different faces of said transducer; and duct means communicating with each of said coupling volumes and having air openings located in a common plane substantially parallel to said transducer; said transducer having a sensitivity decreasing with sound frequency for sound waves having a plane sound field at the location of said transducer, and having a sensitivity varying substantially linearly with sound frequency for sound waves having a spherical field.
  • a transducer assembly as set forth in claim l which is incorporated in a telephone handset.
  • An electro-acoustic transducer assembly as claimed in claim 1, in which said transducer includes a diaphragm having a front face and a rear face; said means providing a pair of substantially equal coupling volumes comprising a first coupling air chamber in communication with said front face and a second coupling air chamber in communication with said rear face; said duct means including first duct means connecting said first chamber to the open air and second duct means connecting said second chamber to the open air; said duct means having lengths such that the paths of sound from any possible sound entry point to both of said chambers are substantially equal, and said first duct means and said second duct means having approximately equal acoustic impedance values; the air openings of the duct means communicating with the first coupling air chamber being located in an inner zone substantially centrally of said common plane; and an outer zone of said common plane surroundig said central zone, the air openings of said second duct means being located in said outer zone.

Landscapes

  • Health & Medical Sciences (AREA)
  • Otolaryngology (AREA)
  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Telephone Set Structure (AREA)
  • Piezo-Electric Transducers For Audible Bands (AREA)
  • Electrostatic, Electromagnetic, Magneto- Strictive, And Variable-Resistance Transducers (AREA)
US194265A 1961-02-06 1962-05-14 Capsule-enclosed electro-acoustic transducer and transistor amplifier Expired - Lifetime US3201516A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
AT97061A AT228283B (de) 1961-02-06 1961-02-06 In eine Kapsel eingebauter elektroakustischer Wandler mit einem Transistorverstärker, insbesondere für Handapparate von Fernsprechstationen

Publications (1)

Publication Number Publication Date
US3201516A true US3201516A (en) 1965-08-17

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US194265A Expired - Lifetime US3201516A (en) 1961-02-06 1962-05-14 Capsule-enclosed electro-acoustic transducer and transistor amplifier

Country Status (4)

Country Link
US (1) US3201516A (de)
AT (2) AT228283B (de)
DE (1) DE1186108B (de)
GB (1) GB961369A (de)

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4401859A (en) * 1981-05-29 1983-08-30 Electro-Voice, Incorporated Directional microphone with high frequency selective acoustic lens
US4625828A (en) * 1985-09-09 1986-12-02 The Boeing Company Acoustic reflector for ground plane microphone
US4633045A (en) * 1985-02-13 1986-12-30 Crown International, Inc. Differential microphone
US20050271798A1 (en) * 2004-04-02 2005-12-08 Maxwell Technologies, Inc. Electrode formation by lamination of particles onto a current collector
US20060146475A1 (en) * 2003-07-09 2006-07-06 Maxwell Technologies, Inc Particle based electrodes and methods of making same
US20070026317A1 (en) * 2004-02-19 2007-02-01 Porter Mitchell Composite electrode and method for fabricating same
US20070122698A1 (en) * 2004-04-02 2007-05-31 Maxwell Technologies, Inc. Dry-particle based adhesive and dry film and methods of making same
US20080117565A1 (en) * 2003-07-09 2008-05-22 Maxwell Technologies, Inc. Dry particle based energy storage device product
US20080266752A1 (en) * 2005-03-14 2008-10-30 Maxwell Technologies, Inc. Thermal interconnects for coupling energy storage devices
US20090290288A1 (en) * 2003-09-12 2009-11-26 Maxwell Technologies, Inc. Electrical energy storage devices with separator between electrodes and methods for fabricating the devices
US20100033901A1 (en) * 2003-07-09 2010-02-11 Maxwell Technologies, Inc. Dry-particle based adhesive electrode and methods of making same
WO2016001615A1 (en) * 2014-07-01 2016-01-07 Audiogravity Holdings Limited Wind noise reduction apparatus
US20220400334A1 (en) * 2021-06-15 2022-12-15 Quiet, Inc. Precisely Controlled Microphone Acoustic Attenuator with Protective Microphone Enclosure

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4145769B2 (ja) 2003-10-20 2008-09-03 本田技研工業株式会社 強制開閉式動弁装置
DE102013221752A1 (de) 2013-10-25 2015-04-30 Kaetel Systems Gmbh Ohrhörer und verfahren zum herstellen eines ohrhörers

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2228886A (en) * 1938-10-31 1941-01-14 Rca Corp Electroacoustical apparatus
US2299620A (en) * 1938-08-19 1942-10-20 Associated Electric Lab Inc Acoustic apparatus
US2463762A (en) * 1941-11-14 1949-03-08 Automatic Elect Lab Electroacoustical transducer
AT190988B (de) * 1956-02-09 1957-07-25 Henry Radio Heinrich & Co Tauchspulenmikrophon
DE1014595B (de) * 1955-02-15 1957-08-29 Lab Wennebostel Richtmikrophon
US2870255A (en) * 1954-01-11 1959-01-20 Remler Company Ltd Microphone assembly
US3048659A (en) * 1959-03-30 1962-08-07 Motorola Inc Microphone preamplifier

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE912821C (de) * 1935-11-13 1954-06-03 Siemens Ag Einrichtung zur Sprachuebertragung aus geraeuscherfuellten Raeumen

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2299620A (en) * 1938-08-19 1942-10-20 Associated Electric Lab Inc Acoustic apparatus
US2228886A (en) * 1938-10-31 1941-01-14 Rca Corp Electroacoustical apparatus
US2463762A (en) * 1941-11-14 1949-03-08 Automatic Elect Lab Electroacoustical transducer
US2870255A (en) * 1954-01-11 1959-01-20 Remler Company Ltd Microphone assembly
DE1014595B (de) * 1955-02-15 1957-08-29 Lab Wennebostel Richtmikrophon
AT190988B (de) * 1956-02-09 1957-07-25 Henry Radio Heinrich & Co Tauchspulenmikrophon
US3048659A (en) * 1959-03-30 1962-08-07 Motorola Inc Microphone preamplifier

Cited By (23)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4401859A (en) * 1981-05-29 1983-08-30 Electro-Voice, Incorporated Directional microphone with high frequency selective acoustic lens
US4633045A (en) * 1985-02-13 1986-12-30 Crown International, Inc. Differential microphone
US4625828A (en) * 1985-09-09 1986-12-02 The Boeing Company Acoustic reflector for ground plane microphone
US7791861B2 (en) 2003-07-09 2010-09-07 Maxwell Technologies, Inc. Dry particle based energy storage device product
US10547057B2 (en) 2003-07-09 2020-01-28 Maxwell Technologies, Inc. Dry-particle based adhesive and dry film and methods of making same
US20060146475A1 (en) * 2003-07-09 2006-07-06 Maxwell Technologies, Inc Particle based electrodes and methods of making same
US9525168B2 (en) 2003-07-09 2016-12-20 Maxwell Technologies, Inc. Dry-particle based adhesive and dry film and methods of making same
US8072734B2 (en) 2003-07-09 2011-12-06 Maxwell Technologies, Inc. Dry particle based energy storage device product
US20080117565A1 (en) * 2003-07-09 2008-05-22 Maxwell Technologies, Inc. Dry particle based energy storage device product
US7791860B2 (en) 2003-07-09 2010-09-07 Maxwell Technologies, Inc. Particle based electrodes and methods of making same
US20100033901A1 (en) * 2003-07-09 2010-02-11 Maxwell Technologies, Inc. Dry-particle based adhesive electrode and methods of making same
US7920371B2 (en) 2003-09-12 2011-04-05 Maxwell Technologies, Inc. Electrical energy storage devices with separator between electrodes and methods for fabricating the devices
US20090290288A1 (en) * 2003-09-12 2009-11-26 Maxwell Technologies, Inc. Electrical energy storage devices with separator between electrodes and methods for fabricating the devices
US7722686B2 (en) 2004-02-19 2010-05-25 Maxwell Technologies, Inc. Composite electrode and method for fabricating same
US20070026317A1 (en) * 2004-02-19 2007-02-01 Porter Mitchell Composite electrode and method for fabricating same
US20110165318A9 (en) * 2004-04-02 2011-07-07 Maxwell Technologies, Inc. Electrode formation by lamination of particles onto a current collector
US20070122698A1 (en) * 2004-04-02 2007-05-31 Maxwell Technologies, Inc. Dry-particle based adhesive and dry film and methods of making same
US20050271798A1 (en) * 2004-04-02 2005-12-08 Maxwell Technologies, Inc. Electrode formation by lamination of particles onto a current collector
US7859826B2 (en) 2005-03-14 2010-12-28 Maxwell Technologies, Inc. Thermal interconnects for coupling energy storage devices
US20080266752A1 (en) * 2005-03-14 2008-10-30 Maxwell Technologies, Inc. Thermal interconnects for coupling energy storage devices
WO2016001615A1 (en) * 2014-07-01 2016-01-07 Audiogravity Holdings Limited Wind noise reduction apparatus
US20220400334A1 (en) * 2021-06-15 2022-12-15 Quiet, Inc. Precisely Controlled Microphone Acoustic Attenuator with Protective Microphone Enclosure
US11785375B2 (en) * 2021-06-15 2023-10-10 Quiet, Inc. Precisely controlled microphone acoustic attenuator with protective microphone enclosure

Also Published As

Publication number Publication date
DE1186108B (de) 1965-01-28
GB961369A (en) 1964-06-17
AT228283B (de) 1963-07-10
AT234171B (de) 1964-06-25

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