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US3833770A - Electrostatic acoustic transducer - Google Patents

Electrostatic acoustic transducer Download PDF

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Publication number
US3833770A
US3833770A US00230435A US23043572A US3833770A US 3833770 A US3833770 A US 3833770A US 00230435 A US00230435 A US 00230435A US 23043572 A US23043572 A US 23043572A US 3833770 A US3833770 A US 3833770A
Authority
US
United States
Prior art keywords
fixed electrodes
conductive layer
acoustic transducer
vibrating film
electrodes
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
US00230435A
Other languages
English (en)
Inventor
N Atoji
T Aoi
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.)
Panasonic Holdings Corp
Original Assignee
Matsushita Electric Industrial Co Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Matsushita Electric Industrial Co Ltd filed Critical Matsushita Electric Industrial Co Ltd
Application granted granted Critical
Publication of US3833770A publication Critical patent/US3833770A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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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
    • H04R19/01—Electrostatic transducers characterised by the use of electrets
    • H04R19/013—Electrostatic transducers characterised by the use of electrets for loudspeakers

Definitions

  • An object of the present invention is to provide an electrostatic acoustic transducer comprising a pair of fixed electrodes with a multiplicity of openings, said electrodes being supported opposite to each other, and
  • the acoustic transducer according to the present invention requires no DC voltage as in the conventional acoustic transducer. Simple in construction and easy to operate, the acoustic transducer according to the invention permits higher harmonic distortion to be reduced greatly. In addition, since a very thin plastic vibrating film electret is employed, the acoustic efficiency is improved, resulting in a great commercial value.
  • FIGS. 1 and 2 are diagrams showing the operating principle of a speaker embodying the present invention
  • FIG. 3 is a diagram for explaining the operation of shown in FIGS. 1 and 2.
  • the referencenumeral 1 shows a vibratin gfilm electret made of a high polymersuch as plastic resin with permanent surface charges.
  • film electret is coated or deposited by evaporation a very thin layer 2 of conductive paint or metal such as aluminum or silver.
  • the numerals 4 and 4' show fixed electrodes with numerous openings necessary for acoustic radiation, and the numerals 3 and 3 layers of air existing betweenthe vibrating film l and the fixed electrode 4 and between thevibrating film l and the ness of the vibrating film l is negligibly small compared with the distances d, and d
  • the symbol E denotes an electrostatic field caused by the electret.
  • the force dF is defined as a force acting on a minute area dS on the vibrating film 1 due to an electric field generated in an airgap between the fixed electrode 4 and the conductive layer 2, and the force dF is defined as a force acting on the minute area dS on the vibrating film 1 due to an electric field generated in an airgap between the fixed electrode 4 and the vibrating film 1.
  • An electrostatic voltage U is generated between the fixed electrode 4 and the vibrating film l by the permanent electric charges Q, on the surface of the vibrating film electret 1.
  • the conductive layer 2 on the vibrating film 1 equivalently acts as being electrostatically grounded, the electric force lines due to the charge Q charged on the vibrating film 1 exist in the airgap 3' but do not exist in the airgap 3. Accordingly, in the airgap 3, no static electricity (DC. voltage) U, due to the charge Q, is generated between the vibrating film 1 (the conductive layer 2) and the fixed electrode 4.
  • the force dF which is generated only due to an AC signal e is expressed as F. o ei /ztd.
  • FIG.. 2 shows an example in which a push-pull transfonner T is employed as a power source.
  • the acoustic transformer according to the present invention employs a sheet of plastic vibrating film electret with a conductive layer'on one side thereof, whereby an AC-derived force is generated in one of the opposite fixed electrodes by superimposing an AC signal upon the electrostatic voltage U due to the permanent surface charge Q Higher harmonics generated at this time are eliminated'by the other fixed electrode.
  • FIG. 4 An electret capacitor speaker is shown in FIG. 4 as an exampleof the present invention.
  • the reference numerals 1 to 5 denote like components sis those shown in FIGS. 1 and 2.
  • the numeral 6 shows fa ring of metal or plastics to which a vibrating film is a tached by fusion or supersonic wave or by the agency of a high polymer bonding agent.
  • the numerals 7 an d 7 show fastening means of plastic for applying tensio to the vibrating film 1, the fixed electrodes 4 and being secured to the fastening means 7 and 7.
  • n i merals 8 and 9 show a boltand a nut respectively f r securing the whole transducer, and numerals 10 and 10 take-out portions of lead wires made of conductive paint or printed member for the fixed electrodes 4 an 4, which are connected to the lead wires 12 and 13.
  • the conductive layer 2 of the vibrating film l is i contact with the lead wire 11.
  • the resistor R as show in FIGS. 1 and 2 is very high in resistance value, an
  • FIG. 5th higher harmonic distortion characteristics of the speaker constructed as above described are compare with those of the conventional speaker of the electrostatic type. It is obvious from the figure that the second higher harmonic distortion characteristic A according to the present invention is superior to the like characteristic B of the conventional speaker.
  • the characteristic curve C shows'an output soundpressure level according to the present invention.
  • An electrostatic acoustic transducer comprising a pair of fixed electrodes each with a multiplicity of openings,,said electrodes being supported opposite to each other, and a single vibrating film electret with a conductive layer formed on one outer surface thereof facing only one of said electrodes, said vibrating film connected capacitors is inserted between said output terminals of said boosting transformer, and a' junction point between the pair of capacitors is connected through a resistor to said conductive layer.
  • An electrostatic acoustic transducer in which said conductive layer is connected with an intermediate terminalof the secondary winding of a push-pull transformer, and the end terminals of said secondary winding of said push-pull transformer are connected with the fixed electrodes respectively.
  • An electrostatic acoustic transducer comprising an annular frame, a single layer vibrating film electret having a conductive layer formed on one outer surface and attached to the uppersurface of said frame, a pair of fixed electrodes between which said vibrating film electret is interposed, said conductive layer being in spaced facing relation to only one of said electrodes, and a fastening means for supporting said annular frame and said fixed electrodes, said fastening means beingprovided with a conductive layer and terminals electrically connected withsaid fixed electrodes.

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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)
US00230435A 1971-03-11 1972-02-29 Electrostatic acoustic transducer Expired - Lifetime US3833770A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP1382871A JPS5632839B1 (fr) 1971-03-11 1971-03-11

Publications (1)

Publication Number Publication Date
US3833770A true US3833770A (en) 1974-09-03

Family

ID=11844119

Family Applications (1)

Application Number Title Priority Date Filing Date
US00230435A Expired - Lifetime US3833770A (en) 1971-03-11 1972-02-29 Electrostatic acoustic transducer

Country Status (6)

Country Link
US (1) US3833770A (fr)
JP (1) JPS5632839B1 (fr)
CA (1) CA947856A (fr)
DE (1) DE2211729A1 (fr)
FR (1) FR2186799B1 (fr)
GB (1) GB1387453A (fr)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3921167A (en) * 1974-06-14 1975-11-18 Ibm Capacitive circuitboard
US3991285A (en) * 1973-10-01 1976-11-09 U.S. Philips Corporation Microphone having an electrostatic cartridge having a structural electrical resistor
US4331840A (en) * 1980-02-22 1982-05-25 Lectret S.A. Electret transducer with tapered acoustic chamber
US4419545A (en) * 1980-07-30 1983-12-06 U.S. Philips Corporation Electret transducer
EP0371620A2 (fr) * 1988-11-30 1990-06-06 Matsushita Electric Industrial Co., Ltd. Microphone à électret
US20090016551A1 (en) * 2007-07-12 2009-01-15 Industrial Technology Research Institute Electrostatic electroacoustic transducers
US20090154730A1 (en) * 2007-12-14 2009-06-18 Sony Ericsson Mobile Communications Ab Electrostatic Speaker Arrangement for a Mobile Device
US20110033079A1 (en) * 2009-08-10 2011-02-10 Industrial Technology Research Institute Flat loudspeaker structure

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20100079379A1 (en) * 2008-09-26 2010-04-01 Sony Ericsson Mobile Communications Ab Portable communication device having an electroluminescent driven haptic keypad
WO2019218697A1 (fr) * 2018-05-14 2019-11-21 Dong Yaobin Générateur électronique, dispositif de génération de charge nette et haut-parleur électrostatique

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3008014A (en) * 1954-07-20 1961-11-07 Ferranti Ltd Electrostatic loudspeakers
US3118022A (en) * 1961-08-07 1964-01-14 Bell Telephone Labor Inc Electroacoustic transducer
US3160715A (en) * 1960-11-15 1964-12-08 Gussing Nils Torsten Alson Electrostatic loudspeakers

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1354631A (fr) * 1962-05-22 1964-03-06 Western Electric Co Transducteur électroacoustique

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3008014A (en) * 1954-07-20 1961-11-07 Ferranti Ltd Electrostatic loudspeakers
US3160715A (en) * 1960-11-15 1964-12-08 Gussing Nils Torsten Alson Electrostatic loudspeakers
US3118022A (en) * 1961-08-07 1964-01-14 Bell Telephone Labor Inc Electroacoustic transducer

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3991285A (en) * 1973-10-01 1976-11-09 U.S. Philips Corporation Microphone having an electrostatic cartridge having a structural electrical resistor
US3921167A (en) * 1974-06-14 1975-11-18 Ibm Capacitive circuitboard
US4331840A (en) * 1980-02-22 1982-05-25 Lectret S.A. Electret transducer with tapered acoustic chamber
US4419545A (en) * 1980-07-30 1983-12-06 U.S. Philips Corporation Electret transducer
EP0371620A2 (fr) * 1988-11-30 1990-06-06 Matsushita Electric Industrial Co., Ltd. Microphone à électret
EP0371620A3 (fr) * 1988-11-30 1991-07-10 Matsushita Electric Industrial Co., Ltd. Microphone à électret
US20090016551A1 (en) * 2007-07-12 2009-01-15 Industrial Technology Research Institute Electrostatic electroacoustic transducers
US8559660B2 (en) * 2007-07-12 2013-10-15 Industrial Technology Research Institute Electrostatic electroacoustic transducers
US20090154730A1 (en) * 2007-12-14 2009-06-18 Sony Ericsson Mobile Communications Ab Electrostatic Speaker Arrangement for a Mobile Device
US8184833B2 (en) * 2007-12-14 2012-05-22 Sony Ericsson Mobile Communications Ab Electrostatic speaker arrangement for a mobile device
US20110033079A1 (en) * 2009-08-10 2011-02-10 Industrial Technology Research Institute Flat loudspeaker structure
US8385586B2 (en) * 2009-08-10 2013-02-26 Industrial Technology Research Institute Flat loudspeaker structure

Also Published As

Publication number Publication date
JPS5632839B1 (fr) 1981-07-30
FR2186799B1 (fr) 1975-03-07
DE2211729A1 (de) 1972-09-28
CA947856A (en) 1974-05-21
FR2186799A1 (fr) 1974-01-11
GB1387453A (en) 1975-03-19

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