US3136867A - Electrostatic transducer - Google Patents

Electrostatic transducer Download PDF

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Publication number
US3136867A
US3136867A US140551A US14055161A US3136867A US 3136867 A US3136867 A US 3136867A US 140551 A US140551 A US 140551A US 14055161 A US14055161 A US 14055161A US 3136867 A US3136867 A US 3136867A
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United States
Prior art keywords
plates
diaphragms
transducer
diaphragm
transformer
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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US140551A
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English (en)
Inventor
George A Brettell
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Ampex Corp
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Ampex Corp
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Filing date
Publication date
Priority to NL281549D priority Critical patent/NL281549A/xx
Application filed by Ampex Corp filed Critical Ampex Corp
Priority to US140551A priority patent/US3136867A/en
Priority to DEA40777A priority patent/DE1188139B/de
Application granted granted Critical
Publication of US3136867A publication Critical patent/US3136867A/en
Anticipated expiration legal-status Critical
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; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R19/00—Electrostatic transducers
    • H04R19/02—Loudspeakers

Definitions

  • transducers encompass devices for transforming one form of energy into a second form of energy.
  • the term transducer is used to define a means for changing electrical energy into energy taking the form of pressure variations in a fluid, or vice versa.
  • such devices have been generally electromagnetic in nature and have been the combination of a current carrying coil and a magnetic core structure with one being moved through its influence on the other to make the energy transformation. combination of coil and core are, for most applications, bulky and heavy where the output power requirements are large and a wide band of frequency response is de-- sired, in addition to having other limitations and disadvantages well-known in the art.
  • compensation may be made by suitable design of the frequency response characteristic of the audio amplifier that drives the transducer, or by the use of an acoustic absorbent material, or both. In either instance the low power output limitation is the result of the limited maximum excursions demanded of the flexible diaphragm.
  • Another object of the invention is to provide a new and improved electrostatic transducer.
  • Still another object of the invention is to provide an electrostatic transducer having a greater power output
  • a further object of the invention is to provide a simple electrical-to-acoustical transducer wherein the required backing chamber volume is substantially reduced over that of the prior art for equal frequency response characteristics.
  • a still further object of the invention is to provide a simple, multi-purpose, and sensitive transducer.
  • a plurality of flexible diaphragms is mounted in a suitable system of stacked frames with rigid plates interleaved therebetween.
  • Both the diaphragms and plates are of conductive ma terials and plates are provided with a plurality of apertures. With such an arrangement, alternate ends of a center-tapped winding of a transformer are respectively connected to successive plates. to the diaphragms by connecting successive diaphragms to opposite terminals of a center-tapped source of unidirectional voltage with the center tap of the source con nected to the center tap of the Winding.
  • the diaphragms are each subjected to electrostatic forces in the same direction with the direction being reversed for all diaphragms for successive alterations of the signal.
  • the same type of element such as the rigid apertured plates, at both ends of the laminar structure, the result is that the force contribution of each diaphragm is additive to that of the others.
  • the increase in force is provided by the laminar type of construction without difference in displacement from diaphragm to diaphragm, except at very high frequencies, where provision must be made for wave propagation velocity for stacks having a large number of elements.
  • FIGURE 1 is a schematic view of a simple electrostatic transducer of the prior art
  • FIGURE 2 is a perspective view, partly broken away, of a transducer in accordance with the present invention.
  • FIGURE 3 is a partial cross section view of the invention of FIGURE 2 showing suitable electrical connections;
  • FIGURE 4 is a cross section of-the invention of FIG- URE 2 as mounted in a wall of a backing chamber;
  • FIGURE 5 is an exploded View of an embodiment of the present invention.
  • FIGURE 6 is a schematic view of the invention of FIGURES.
  • FIGURE 7 is an illustration of another manner of applying variable voltages to rigid plates of FIGURE 3 for high frequency applications.
  • FIGURE 1 in particular, there is illustrated a typical electrostatic transducer 11 of the prior art.
  • a flexible diaphragm 12 such as Mylar with a conductive coating 13 of silver or the like, is provided as a principal element.
  • rigid conductive plates 14 and 15 are rigid conductive plates 14 and 15, each having a plurality of apertures 17, 18, respectively, therein.
  • an electrical circuit 19 is provided to assert a pushpull component of electrostatic forces on the diaphragm 12.
  • the circuit 19 comprises a transformer 21 having one winding 22 connected between two terminals 23 and 24 and a second winding 26 having a center tap 27.
  • One lead 28 of the center-tapped winding 26 is connected to one plate 14 and another lead 29 is connected to the plate 15.
  • a bias supply 31 such as a series of batteries as shown
  • a resistor 32 is connected between the center tap 27 and the diaphragm 12.
  • the two rigid plates 17 and 18 are given opposite potentials with respect to the center tap during each alternation of the signal. Because of the bias potential of the diaphragm 12 and the connection of the diaphragm to the center tap 27, a net electrostatic force is developed on the diaphragm in a direction corresponding to the polarity of the input signal and the result is a movement of the diaphragm corresponding to the amplitude and polarity of the signal.
  • FIGURE 2 of the drawings In such figure three rigid conductive plates 41, 42, and 43 are respectively mounted in parallel and spaced-apart relation within suitable frames 46, 47, and 48. In the two spaces, thus provided, between the successive plates 41, 42, and 43 there are respectively disposed two thin flexible and slightly conductive diaphragms 51 and 52.
  • the rigid plates 41, 42, and 43 are respectively provided with a plurality of apertures 53, 54, and 55, similar to the previously described plates 17 and 18.
  • the diaphragms 51 and 52 may be similar to the previously described diaphragm 12, but having less conductivity.
  • the foregoing elements are clamped together in a suitable manner (not shown) to provide a unitary structure.
  • the mid-point 68 between the batteries 66 and 67 is connected to ground, as is a center tap 69 of the winding 59, or the mid-point may be directly connected to the center tap.
  • the plates 41, 42, and 43 extend into suitable slots (not num- 4- bered) of the frames 46, 47, and 48, respectively, and the leads between the winding 59 and the plates extend through communicating openings 71, 72, and 73, respectively.
  • the two diaphragms 51 and 52 are subjected to forces in the same direction.
  • the two diaphragms 51 and 52 are respectively connected to oppositely polarized terminals of the sources 66 and 67 of bias.
  • the two diaphragms 51 and 52 are respectively connected to oppositely polarized terminals of the sources 66 and 67 of bias.
  • a reasonably dimensioned closed backing-chamber may be used for reproduction of sound over an extremely wide range of audio frequencies.
  • prior high power loudspeakers it is necessary to provide a large volume backing chamber because of the necessity of limiting the forces needed to compress the enclosed air.
  • the prior art teaches the use of bafiles, or other substitutes for the closed backing chamber.
  • bafiles have been proposed, with or without the use of bafiles.
  • One type requires that the loudspeaker be placed in the corner of a room with the backward dimensions from the moveable element of the transducer to the walls of the room having a specific relation with respect to the frequencies to be faithfully reproduced. Such arrangements are still compromises and fall far short of the ideal.
  • a transducer 81 similar to that described with respect to FIGURES 2 and 3, is mounted in one wall of a closed rectangular box-like structure 82. Electrical connections to the various active elements of the transducer 81 are suitably made through the wall structure 82, though not shown for simplicity of illustration, in the manner of FIGURE 3. The relationship between the dimensions of the transducer 81 and those of the backing-structure 82 is dependent on the number of diaphragms of the transducer stack.
  • the laminar structure of the invention permits a considerable reduction in the required dimensions of the backing chamber for faithful reproduction of the entire audio band of frequencies.
  • the backing chamber 82 may be provided with acoustically absorbent material (not shown), either mounted on the Walls thereof, or inserted in the manner of a loose packing.
  • the structure shown in FIGURE 4 may also be used to provide controlled air impulses.
  • the transducer 81 is confined within one end of an air column, such as that provided by a pipe or conduit (not shown), extended away from the backing-chamber structure 82.
  • electrical connections are made in the manner of FIGURE 3 and a pulse of one polarity applied at the terminals 63 and 64 results in a flow of air in one direction with respect to the transducer 81 while a pulse of the opposite polarity causes an air flow in the opposite direction.
  • the foregoing structure and connections provide an electrical output at-the terminals 63 and 64 in response to diiferences in air pressure upon the transducer 81.
  • a transducer 91 is provided having three apertured rigid plates 92, 93, and 94 with two interleaved flexible diaphragms 96 and 97.
  • Frames 101 and 102 of the two rigid plates 92 and 94 at the outermost portions of the transducer 91 are three sided with the open portion of each facing in the same direction while a similar frame 103 of the intermediate rigid plate 93 is disposed with the open portion facing in the opposite direction.
  • top and bottom cover plates 108 and 109 are disposed adjacent to the respective end plates 92 and 94.
  • the foregoing elements are then suitably clamped together, as by bolts (not shown) extended through the frame elements.
  • a transformer 111 has a first winding 112 connected between two terminals 113 and 114 and a second, center-tapped, winding 116.
  • One lead 117 of the center-tapped winding 116 is connected to the two outer rigid plates 92 and 94 of the stack and a second lead 118 is connected to the intermediate plate 93.
  • Bias is applied to the diaphragms 96 and 97 by connecting one terminal of a source 121 of direct current, such as the battery shown, to both of the diaphragms and the other terminal of the source directly to the center tap of the winding 116, or, as shown, through ground connections.
  • a signal coupled to the terminals 113 and 114 of the transformer 111 results in electrostatic forces being applied to the two diaphragms 96 and 97 in opposite directions.
  • both of the diaphragms 96 and 97 are connected to the same terminal of the bias source 121, the outer plates 92 and 94 are each connected to the lead 117, and the intermediate plate 93 is connected to the lead 118.
  • the resulting forces upon the diaphragm 96, 97 are such that the diaphragms are distorted in opposite directions, either toward or away from each other.
  • the principle is the same as that previously stated, that is, the bias and signal are additive between the diaphragm and plate on one side and subtractive on the other side.
  • the diaphragms 96, 97 are forced away from each other to increase the volume of the chamber therebetween, which includes the central apertured plate 93, and decrease the volume of the two outermost chambers of the stack. Air, or other fluid, is then pulled in at opening 126 and forced out at openings 127 and 128.
  • a reversal of the applied signal results in the diaphragms 96, 97 being distorted toward each other so that the central volume is decreased and outer volumes increased. In the latter instance then air, or other fluid, is pulled in at openings 127 and 128 and forced out at opening 126. Because the diaphragms 96 and 97 are forced in opposite directions in the present embodiment of the invention the amount of air, or other fluid, displaced for a single input signal is greatly increased over any other arrangement.
  • the movement of the fluid in and out of opposite sides of the transducer 91 may be readily controlled by applying pulses of selected polarity to the two terminals 113 and 114.
  • the transducer 91 may, for example, with suitable conduit connections be used for applying selective pneumatic pressures to control the movement of magnetic tape in passage between supply and takeup reels across magnetic transducers.
  • the transducer ,91 of FIGURES 5 and 6 may be used to sense pressure, as Well as pressure differential.
  • the electrical connections may be as shown in FIGURE 6 with the output being taken from the terminals 113 and 114 and with no applied alternating signal.
  • one source is coupled to the openings 127 and 128 and the second source is coupled to the oppositely disposed opening 126.
  • the electrical connections may be the same as for the preceding application and, in both instances, the terminals 113 and 114 are connected to a measuring device or a utilization circuit, such as a servo loop to maintain the pressure constant.
  • FIGURE 7 the frequency response of such a system where a large plurality of interleaved plates and diaphragms are used for high power applications, is improved in the manner illustrated in FIGURE 7.
  • the connections to the diaphragms are the same as shown in FIGURE 3 and are not further illustrated here.
  • the source of signals applied to the plates 121-127 is the same as in FIGURE 3 as connected to the terminals 57 and 58 and bears the same series of reference numerals.
  • the mass of the diaphragms is analogous to a capacitor in an electrical analogue sense and, likewise, the compliance of air between the diaphragms is analogous to an inductance.
  • the mass of the diaphragms and compliance of the air serves to delay the wave with respect to the exciting electrical signal so that at the output end of the stack improper phase relationships exist between the wave and the signal. The result is improper reproduction of the audio signals, particularly at the higher frequencies.
  • the inherent electrical capacitance between the diaphragms is complemented by the addition of inductors 131 in the connecting leads between the terminals 57, 58 and the successive plates 121127.
  • the result is an electrical delay line for the input signals to match the delay of the resultant air wave proceeding from the rear to the front, or output, of the laminar stack.
  • the wave and signal arrive at the plates at the same time and prevent cancellations in the output.
  • Such efiects are principally noticeable at the higher frequencies.
  • the present invention has been principally shown and described with respect to a laminar structure for an electrostatic transducer having two flexible diaphragms; however, it is to be realized that, while such arrangement increases the output power by a factor of two over a single diaphragm system, as the number of diaphragms is increased so is the output.
  • a similar system having three diaphragms increases the output by a factor of three
  • a four diaphragm system increases the output by a factor of four, and so forth with the output increasing in direct proportion to the number of diaphragms.
  • An electrostatic transducer assembly comprising a plurality of parallel mounted and apertured rigid plates; a similar plurality, less one, of flexible diaphragms respectively interleaved between the plates, the diaphragms being substantially coextensive with and parallel to the plates; a transformer having a center-tapped winding with two leads alternately connected to successive ones of the plates; a center-tapped source of bias having two electrodes of opposite polarity with successive diaphragms being alternately connected to the two electrodes and the center tap of the source coupled to the center tap of the transformer winding; and a transmission line having a time constant matching the inherent mechanical time constant of the plate and diaphragm combinations included between the two transformer leads and the successive plates.
  • An electrostatic transducer assembly comprising a plurality of parallel mounted and apertured rigid plates; a similar plurality, less one, of flexible diaphragms respectively interleaved between the plates, the diaphragms being substantially coextensive with and parallel to the plates; open-sided, electrically-insulating frames for supporting each of the apertured plates with the open side of successive frames oppositely disposed; cover plates disposed across the frames of each outermost plate of the plurality of plates; a transformer having a centertapped winding with two leads alternately connected to successive ones of the plates; and a source of bias having two electrodes of opposite polarity with one electrode connected to each of the diaphragms and the second electrode coupled to the center tap of the transformer winding.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Electrostatic, Electromagnetic, Magneto- Strictive, And Variable-Resistance Transducers (AREA)
US140551A 1961-09-25 1961-09-25 Electrostatic transducer Expired - Lifetime US3136867A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
NL281549D NL281549A (fr) 1961-09-25
US140551A US3136867A (en) 1961-09-25 1961-09-25 Electrostatic transducer
DEA40777A DE1188139B (de) 1961-09-25 1962-07-20 Elektrostatische Wandleranordnung

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US140551A US3136867A (en) 1961-09-25 1961-09-25 Electrostatic transducer

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US3136867A true US3136867A (en) 1964-06-09

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DE (1) DE1188139B (fr)
NL (1) NL281549A (fr)

Cited By (58)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3345469A (en) * 1964-03-02 1967-10-03 Rod Dev Corp Electrostatic loudspeakers
US3389226A (en) * 1964-12-29 1968-06-18 Gen Electric Electrostatic loudspeaker
US3403234A (en) * 1964-09-11 1968-09-24 Northrop Corp Acoustic transducer
US3413573A (en) * 1965-06-18 1968-11-26 Westinghouse Electric Corp Microelectronic frequency selective apparatus with vibratory member and means responsive thereto
US3422324A (en) * 1967-05-17 1969-01-14 Webb James E Pressure variable capacitor
US3562429A (en) * 1968-04-29 1971-02-09 Teachout West Electro Acoustic Sound transmitter with feedback and polarization circuitry
US3604251A (en) * 1969-04-18 1971-09-14 Atomic Energy Commission A capacitive ultrasonic device for nondestructively testing a sample
US3654403A (en) * 1969-05-01 1972-04-04 Chester C Pond Electrostatic speaker
US3783202A (en) * 1971-01-07 1974-01-01 Pond C Speaker system and electrostatic speaker
US3941946A (en) * 1972-06-17 1976-03-02 Sony Corporation Electrostatic transducer assembly
US3980838A (en) * 1974-02-20 1976-09-14 Tokyo Shibaura Electric Co., Ltd. Plural electret electroacoustic transducer
US4006317A (en) * 1975-02-14 1977-02-01 Freeman Miller L Electrostatic transducer and acoustic and electric signal integrator
US4146800A (en) * 1975-10-08 1979-03-27 Gregory Stephen E Apparatus and method of generating electricity from wind energy
US4338489A (en) * 1979-02-12 1982-07-06 Akg Akustische U. Kino-Gerate Gesellschaft M.B.H. Headphone construction
EP0065810A2 (fr) * 1981-05-15 1982-12-01 BEARD, Terry D. Système transducteur électroacoustique à onde progressive et un microphone et hautparleur comportant un tel système
WO1984004865A1 (fr) * 1983-05-23 1984-12-06 Harold Norman Beveridge Electrode pour transducteur electrostatique et procedes de production
FR2559981A1 (fr) * 1984-02-17 1985-08-23 Thomson Csf Dispositif de reproduction sonore pour televiseur
US4799265A (en) * 1986-07-08 1989-01-17 U.S. Philips Corporation Electrostatic transducer unit
EP0595221A1 (fr) * 1992-10-24 1994-05-04 Sony Corporation Système de haut-parleur électrostatique
US5388163A (en) * 1991-12-23 1995-02-07 At&T Corp. Electret transducer array and fabrication technique
US5682075A (en) * 1993-07-14 1997-10-28 The University Of British Columbia Porous gas reservoir electrostatic transducer
US5862239A (en) * 1997-04-03 1999-01-19 Lucent Technologies Inc. Directional capacitor microphone system
US6175636B1 (en) * 1998-06-26 2001-01-16 American Technology Corporation Electrostatic speaker with moveable diaphragm edges
US6188772B1 (en) 1998-01-07 2001-02-13 American Technology Corporation Electrostatic speaker with foam stator
US6199655B1 (en) 1999-10-22 2001-03-13 American Technology Corporation Holographic transparent speaker
US6304662B1 (en) 1998-01-07 2001-10-16 American Technology Corporation Sonic emitter with foam stator
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US6483924B1 (en) * 1996-02-26 2002-11-19 Panphonics Oy Acoustic elements and method for sound processing
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US20030118203A1 (en) * 2000-03-07 2003-06-26 George Raicevich Layered microphone structure
US20040113526A1 (en) * 2001-04-11 2004-06-17 Kari Kirjavainen Electromechanical transducer and method for transforming energies
US20050089176A1 (en) * 1999-10-29 2005-04-28 American Technology Corporation Parametric loudspeaker with improved phase characteristics
US20050100181A1 (en) * 1998-09-24 2005-05-12 Particle Measuring Systems, Inc. Parametric transducer having an emitter film
US20050195985A1 (en) * 1999-10-29 2005-09-08 American Technology Corporation Focused parametric array
US20060072770A1 (en) * 2004-09-22 2006-04-06 Shinichi Miyazaki Electrostatic ultrasonic transducer and ultrasonic speaker
US20060233404A1 (en) * 2000-03-28 2006-10-19 American Technology Corporation. Horn array emitter
US20060280315A1 (en) * 2003-06-09 2006-12-14 American Technology Corporation System and method for delivering audio-visual content along a customer waiting line
US20070189548A1 (en) * 2003-10-23 2007-08-16 Croft Jams J Iii Method of adjusting linear parameters of a parametric ultrasonic signal to reduce non-linearities in decoupled audio output waves and system including same
US20090154730A1 (en) * 2007-12-14 2009-06-18 Sony Ericsson Mobile Communications Ab Electrostatic Speaker Arrangement for a Mobile Device
US8275137B1 (en) 2007-03-22 2012-09-25 Parametric Sound Corporation Audio distortion correction for a parametric reproduction system
US8767979B2 (en) 2010-06-14 2014-07-01 Parametric Sound Corporation Parametric transducer system and related methods
US8903104B2 (en) 2013-04-16 2014-12-02 Turtle Beach Corporation Video gaming system with ultrasonic speakers
US8934650B1 (en) 2012-07-03 2015-01-13 Turtle Beach Corporation Low profile parametric transducers and related methods
US8958580B2 (en) 2012-04-18 2015-02-17 Turtle Beach Corporation Parametric transducers and related methods
US8988911B2 (en) 2013-06-13 2015-03-24 Turtle Beach Corporation Self-bias emitter circuit
US9036831B2 (en) 2012-01-10 2015-05-19 Turtle Beach Corporation Amplification system, carrier tracking systems and related methods for use in parametric sound systems
US9332344B2 (en) 2013-06-13 2016-05-03 Turtle Beach Corporation Self-bias emitter circuit
WO2016127119A1 (fr) * 2015-02-06 2016-08-11 Clean Energy Labs, Llc Haut-parleur doté de transducteurs à membrane électroconductrice
WO2016187325A1 (fr) * 2015-05-20 2016-11-24 Clean Energy Labs, Llc Système de haut-parleur et de transducteur électro-acoustique compact, et son procédé d'utilisation
US20160366521A1 (en) * 2015-06-09 2016-12-15 Brane Audio, LLC Electroacousitic loudspeaker system for use in a partial enclosure
CN107710788A (zh) * 2015-06-08 2018-02-16 怀斯迪斯匹有限公司 静电扬声器及其方法
CN108028973A (zh) * 2015-07-06 2018-05-11 怀斯迪斯匹有限公司 声收发换能器
WO2018128673A1 (fr) * 2016-10-25 2018-07-12 Clean Energy Labs, Llc Système compact de haut-parleur et de transducteur électro-acoustique, et sa méthode d'utilisation
US20190251944A1 (en) * 2018-01-31 2019-08-15 Raymond Sobol System and Method For Altering Sound Waves
US20190287511A1 (en) * 2018-01-31 2019-09-19 Zerosound Systems Inc. Apparatus and method for active noise reduction
US11151975B2 (en) 2018-01-31 2021-10-19 Zerosound Systems Inc. Apparatus and method for sound wave generation

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GB838024A (en) * 1956-10-11 1960-06-22 Pye Ltd Improvements in electrostatic loudspeakers
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US1082248A (en) * 1912-08-13 1913-12-23 Josef Unterholzner Condenser-telephone.
US1983377A (en) * 1929-09-27 1934-12-04 Gen Electric Production of sound
US1978200A (en) * 1930-03-24 1934-10-23 Bell Telephone Labor Inc Electrostatic acoustic device
FR1083302A (fr) * 1953-09-11 1955-01-07 Haut-parleur et microphone électrostatiques
US3008014A (en) * 1954-07-20 1961-11-07 Ferranti Ltd Electrostatic loudspeakers
GB838024A (en) * 1956-10-11 1960-06-22 Pye Ltd Improvements in electrostatic loudspeakers

Cited By (84)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3345469A (en) * 1964-03-02 1967-10-03 Rod Dev Corp Electrostatic loudspeakers
US3403234A (en) * 1964-09-11 1968-09-24 Northrop Corp Acoustic transducer
US3389226A (en) * 1964-12-29 1968-06-18 Gen Electric Electrostatic loudspeaker
US3413573A (en) * 1965-06-18 1968-11-26 Westinghouse Electric Corp Microelectronic frequency selective apparatus with vibratory member and means responsive thereto
US3422324A (en) * 1967-05-17 1969-01-14 Webb James E Pressure variable capacitor
US3562429A (en) * 1968-04-29 1971-02-09 Teachout West Electro Acoustic Sound transmitter with feedback and polarization circuitry
US3604251A (en) * 1969-04-18 1971-09-14 Atomic Energy Commission A capacitive ultrasonic device for nondestructively testing a sample
US3654403A (en) * 1969-05-01 1972-04-04 Chester C Pond Electrostatic speaker
US3783202A (en) * 1971-01-07 1974-01-01 Pond C Speaker system and electrostatic speaker
US3941946A (en) * 1972-06-17 1976-03-02 Sony Corporation Electrostatic transducer assembly
US3980838A (en) * 1974-02-20 1976-09-14 Tokyo Shibaura Electric Co., Ltd. Plural electret electroacoustic transducer
US4006317A (en) * 1975-02-14 1977-02-01 Freeman Miller L Electrostatic transducer and acoustic and electric signal integrator
US4146800A (en) * 1975-10-08 1979-03-27 Gregory Stephen E Apparatus and method of generating electricity from wind energy
US4338489A (en) * 1979-02-12 1982-07-06 Akg Akustische U. Kino-Gerate Gesellschaft M.B.H. Headphone construction
EP0065810A2 (fr) * 1981-05-15 1982-12-01 BEARD, Terry D. Système transducteur électroacoustique à onde progressive et un microphone et hautparleur comportant un tel système
EP0065810A3 (fr) * 1981-05-15 1983-07-20 BEARD, Terry D. Système transducteur électroacoustique à onde progressive et un microphone et hautparleur comportant un tel système
WO1984004865A1 (fr) * 1983-05-23 1984-12-06 Harold Norman Beveridge Electrode pour transducteur electrostatique et procedes de production
US4533794A (en) * 1983-05-23 1985-08-06 Beveridge Harold N Electrode for electrostatic transducer
FR2559981A1 (fr) * 1984-02-17 1985-08-23 Thomson Csf Dispositif de reproduction sonore pour televiseur
US4799265A (en) * 1986-07-08 1989-01-17 U.S. Philips Corporation Electrostatic transducer unit
US5388163A (en) * 1991-12-23 1995-02-07 At&T Corp. Electret transducer array and fabrication technique
EP0595221A1 (fr) * 1992-10-24 1994-05-04 Sony Corporation Système de haut-parleur électrostatique
US5471540A (en) * 1992-10-24 1995-11-28 Sony Corporation Electrostatic loudspeaker having stationary electrodes formed as multiple sheets insulated from each other
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DE1188139B (de) 1965-03-04

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