US3646280A - Backplate for electret loudspeaker - Google Patents

Backplate for electret loudspeaker Download PDF

Info

Publication number
US3646280A
US3646280A US67187A US3646280DA US3646280A US 3646280 A US3646280 A US 3646280A US 67187 A US67187 A US 67187A US 3646280D A US3646280D A US 3646280DA US 3646280 A US3646280 A US 3646280A
Authority
US
United States
Prior art keywords
electret
electroacoustic transducer
vibrating film
electrets
electrostatic electroacoustic
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
US67187A
Inventor
Masahiko Tamura
Kiyonori Iwama
Mitsuo Asahina
Kensuke Okuda
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.)
Pioneer Corp
Original Assignee
Pioneer Electronic Corp
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 Pioneer Electronic Corp filed Critical Pioneer Electronic Corp
Application granted granted Critical
Publication of US3646280A publication Critical patent/US3646280A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

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

  • ABSTRACT An electrostatic electroacoustic transducer comprising a vibrating film, an electret having many small holes and a fixed electrode adhered closely thereto.
  • the fixed electrode is made of an electroconductive fiber.
  • This invention relates to an electrostatic electroacoustic transducer, and more particularly to an improvement of an electrostatic electroacoustic transducer using an electret and electroconductive fiber.
  • FIG. 1 is a sectional plane view of a prior art electrostatic electroacoustic transducer using an electret.
  • FIG. 2 is a sectional plane view of the structure of an electrostatic electroacoustic transducer of the preferred embodiment of the present invention.
  • electrostatic electroacoustic transducers using an electret for example a push-pull speaker, are constructed as shown in FIG. 1.
  • a vibrating film 1 is located between charged electrets 2 and 3.
  • Fixed electrodes 4 and 5 which are made of electroconductive materials are adhered closely to electrets 2 and 3 respectively. They are firmly held in place by holding members 6 and 7.
  • an alternating signal is applied between the fixed electrode 4 or 5 and an electrode 10
  • the vibrating film l is vibrated whereby the sound generated is radiated through holes 8 and 9.
  • FIG. 2 wherein the preferred embodiment of the present in- .vention is shown.
  • Numeral l1 designates a vibrating film
  • the electroconductive fiber may be, for example, a carbon fiber, a graphite fiber, a metal fiber, or a nonelectroconductive fiber such as a glass fiber which is coated with metal or carbon so as to make it electroconductive. Further, these fibers can be used singly or can be mixed with other nonelectroconductive fibers. Usually, these fibers are used as cloth being composed of single or mixed fibers ina sheet, net or felt, which is hereinafter referred to as "a fiber.”
  • 16 and 17 are insulated pressing boards having many holes 16a and 17a for the acoustic radiation.
  • 18 and 19 are rings having screw portions and 19a, whereby the fibers 14 and 15 are pressed toward the electrets 12 and 13 through the pressing boards 16 and I7.
  • Holding members 20 and 21 are made of insulated materials and hold above-mentioned components in place and have screw portions 20a and 21a whereby rings 18 and 19 are secured.
  • An electrode 22 applies a signal into the vibrating film ll
  • electrode 23 applies a signal into the fiber l4
  • electrode 24 applies a signal into the fiber 15.
  • the electrets 12 and 13 can be manufactured with many holes, having no relation to the fibers l4 and 15 which are the fixed electrodes.
  • the fibers l4 and 15 are between the electrets l2 and 13 and the pressing boards 16 and 17, it is not necessary to make the hole 12a precisely coincide with hole 16a and the hole 13a with hole 17a. Therefore problems in making both holes precisely coincide are solved and the level of efficiency of mass production is raised.
  • the fixed electrode the fibers l4 and 15
  • the electrode can be pressed with the electret 12 or 13 equally on its whole surface.
  • the acoustic characteristics can be selected by changing the elasticity or thickness or length of the fibers l4 and 15, or by adjusting the pressure ofthe pressing board 16 or 17 with the ring 18 or 19. Ifit is unnecessary to adjust the pressure of the pressing board 16 and 17, rings 18 or 19 may be omitted and the pressing board 16 or 17 may be fixed to the holding member 20 or 21. In such case, the level of efficiency of mass production is further increased. Fifth, it is not necessary to provide a dustproof layer since the electrets l2 and 13 are kept free of dust by fibers l4 and 15. Therefore, the charge on the electrets lasts for many years.
  • An electrostatic electroacoustic transducer comprising a vibrating film, an electret having one side juxtapositioned to said vibrating film said electret having a plurality of holes therein for passing acoustic radiation, a fixed electrode made of an electroconductive fiber which is adhered to the other side of said electret, and a pressing board pushing said fixed electrode against said electret, said pressing board having a plurality of holes therein for passing acoustic radiation.
  • An electrostatic electroacoustic transducer comprising a vibrating film, two electets each having one side juxtapositioned to said vibrating film each electret having a plurality of holes therein for passing acoustic radiation, fixed electrodes made of an electroconductive fiber said electrodes adhered to the other side of each of said electrets, and pressing boards pushing said fixed electrodes against said electrets, said pressing boards having a plurality of holes therein for passing acoustic radiation.
  • electrostatic electroacoustic transducer as set forth in claim 1, wherein said electroconductive fiber is a carbon fiber.
  • electrostatic electroacoustic transducer as set forth in claim 2, wherein said electroconductive fiber is a carbon fiber.

Abstract

An electrostatic electroacoustic transducer comprising a vibrating film, an electret having many small holes and a fixed electrode adhered closely thereto. The fixed electrode is made of an electroconductive fiber.

Description

trite States atem Tamara et a1.
BACKPLATE FOR ELECTRET LOUDSPEAKER inventors: Masahiko Tamura; Kiyonori iwama, both of Tokorozawa; Mitsuo Asahina; Kensuke Okuda, both of Tokyo, all of Japan Assignee: Pioneer Electronic Corporation, Ohtaku,
Tokyo, Japan Filed: Aug. 26, 1970 App]. No.: 67,187
Foreign Application Priority Data Aug. 28, 1969 Japan ..44/676l3 1 Feb. 29, 1972 [52] U.S.Cl l79/lll E [51] Int. Cl ..H04r 19/02 [58] Field ofSearch ..l79/l ll R, I H E, 106
Primary Examinerl(athleen H. Claffy Assistant ExaminerThomas L. Kundret AttorneySughrue, Rothwell, Mion, Zinn and Macpeak [57] ABSTRACT An electrostatic electroacoustic transducer comprising a vibrating film, an electret having many small holes and a fixed electrode adhered closely thereto. The fixed electrode is made of an electroconductive fiber.
6 Claims, 2 Drawing Figures Patented Feb. 29, 1972 3,646,280
F56. i PRIOR ART BACKPLATE FOR ELECTRET LOUDSPEAKER BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to an electrostatic electroacoustic transducer, and more particularly to an improvement of an electrostatic electroacoustic transducer using an electret and electroconductive fiber.
2. Description of the Prior Art In prior art electrostatic electroacoustic transducers using electrets, such as a push-pull speaker, a vibrating film is located between two charged electrets. The electrets are affixed to fixed electrodes and the device is held together by holding members. When an alternating signal is applied to the fixed electrodes, the film is vibrated and a sound is generated.
There are many disadvantages in prior art devices of this type. First, it is difficult to uniformly adhere the electrets to the fixed electrodes. Second, the position of the holes of the electrets and that of the fixed electrode must coincide with each other. It therefore requires great skill to adhere the electrets to the fixed electrodes. Third, because of the difficulty of construction in adding an acoustical adjusting function, it is almost impossible to select an acoustical characteristic. Fourth, if the device is not dustproof, the charging characteristics ofthe electrets will deteriorate.
SUMMARY OF THE INVENTION It is therefore the main object of this invention to provide a novel and improved electrostatic electroacoustic transducer in which the above-mentioned defects are solved.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional plane view of a prior art electrostatic electroacoustic transducer using an electret.
FIG. 2 is a sectional plane view of the structure of an electrostatic electroacoustic transducer of the preferred embodiment of the present invention.
In prior art electrostatic electroacoustic transducers using an electret, for example a push-pull speaker, are constructed as shown in FIG. 1. A vibrating film 1 is located between charged electrets 2 and 3. Fixed electrodes 4 and 5 which are made of electroconductive materials are adhered closely to electrets 2 and 3 respectively. They are firmly held in place by holding members 6 and 7. When an alternating signal is applied between the fixed electrode 4 or 5 and an electrode 10, the vibrating film l is vibrated whereby the sound generated is radiated through holes 8 and 9.
DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention will be explained in detail referring to FIG. 2 wherein the preferred embodiment of the present in- .vention is shown. Numeral l1 designates a vibrating film, the
surface of which is electroconductive. l2 and 13 show electrets having many holes 12a and 13a for the acoustic radiation. 14 and 15 show electroconductive fibers. The electroconductive fiber may be, for example, a carbon fiber, a graphite fiber, a metal fiber, or a nonelectroconductive fiber such as a glass fiber which is coated with metal or carbon so as to make it electroconductive. Further, these fibers can be used singly or can be mixed with other nonelectroconductive fibers. Usually, these fibers are used as cloth being composed of single or mixed fibers ina sheet, net or felt, which is hereinafter referred to as "a fiber." 16 and 17 are insulated pressing boards having many holes 16a and 17a for the acoustic radiation. 18 and 19 are rings having screw portions and 19a, whereby the fibers 14 and 15 are pressed toward the electrets 12 and 13 through the pressing boards 16 and I7. Holding members 20 and 21 are made of insulated materials and hold above-mentioned components in place and have screw portions 20a and 21a whereby rings 18 and 19 are secured. An electrode 22 applies a signal into the vibrating film ll, electrode 23 applies a signal into the fiber l4, and electrode 24 applies a signal into the fiber 15.
The present invention has many improvements over prior art devices. First, the electrets 12 and 13 can be manufactured with many holes, having no relation to the fibers l4 and 15 which are the fixed electrodes. Second, since the fibers l4 and 15 are between the electrets l2 and 13 and the pressing boards 16 and 17, it is not necessary to make the hole 12a precisely coincide with hole 16a and the hole 13a with hole 17a. Therefore problems in making both holes precisely coincide are solved and the level of efficiency of mass production is raised. Third, as the fixed electrode (the fibers l4 and 15) is fibroid, the electrode can be pressed with the electret 12 or 13 equally on its whole surface. Fourth, the acoustic characteristics can be selected by changing the elasticity or thickness or length of the fibers l4 and 15, or by adjusting the pressure ofthe pressing board 16 or 17 with the ring 18 or 19. Ifit is unnecessary to adjust the pressure of the pressing board 16 and 17, rings 18 or 19 may be omitted and the pressing board 16 or 17 may be fixed to the holding member 20 or 21. In such case, the level of efficiency of mass production is further increased. Fifth, it is not necessary to provide a dustproof layer since the electrets l2 and 13 are kept free of dust by fibers l4 and 15. Therefore, the charge on the electrets lasts for many years.
What is claimed is:
1. An electrostatic electroacoustic transducer comprising a vibrating film, an electret having one side juxtapositioned to said vibrating film said electret having a plurality of holes therein for passing acoustic radiation, a fixed electrode made of an electroconductive fiber which is adhered to the other side of said electret, and a pressing board pushing said fixed electrode against said electret, said pressing board having a plurality of holes therein for passing acoustic radiation.
2. An electrostatic electroacoustic transducer comprising a vibrating film, two electets each having one side juxtapositioned to said vibrating film each electret having a plurality of holes therein for passing acoustic radiation, fixed electrodes made of an electroconductive fiber said electrodes adhered to the other side of each of said electrets, and pressing boards pushing said fixed electrodes against said electrets, said pressing boards having a plurality of holes therein for passing acoustic radiation.
3. An electrostatic electroacoustic transducer as set forth in claim 1, wherein said electroconductive fiber is a carbon fiber.
4. An electrostatic electroacoustic transducer as set forth in claim 2, wherein said electroconductive fiber is a carbon fiber.
5. An electrostatic electroacoustic transducer as set forth in claim 1, further comprising a holding member for securing said vibrating film, said electret and said pressing board together,
6. An electrostatic electroacoustic transducer as set forth in claim 2, further comprising a holding member for securing said vibrating film,. said two electrets and said two pressing boards together.

Claims (6)

1. An electrostatic electroacoustic transducer comprising a vibrating film, an electret having one side juxtapositioned to said vibrating film said electret having a plurality of holes therein for passing acoustic radiation, a fixed electrode made of an electroconductive fiber which is adhered to the other side of said electret, and a pressing board pushing said fixed electrode against said electret, said pressing board having a plurality of holes therein for passing acoustic radiation.
2. An electrostatic electroacoustic transducer comprising a vibrating film, two electets each having one side juxtapositioned to said vibrating film each electret having a plurality of holes therein for passing acoustic radiation, fixed electrodes made of an electroconductive fiber said electrodes adhered to the other side of each of said electrets, and pressing boards pushing said fixed electrodes against said electrets, said pressing boards having a plurality of holes therein for passing acoustic radiation.
3. An electrostatic electroacoustic transducer as set forth in claim 1, wherein said electroconductive fiber is a carbon fiber.
4. An electrostatic electroacoustic transducer as set forth in claim 2, wherein said electroconductive fiber is a carbon fiber.
5. An electrostatic electroacoustic transducer as set forth in claim 1, further comprising a holding member for securing said vibrating film, said electret and said pressing board together.
6. An electrostatic electroacoustic transducer as set forth in claim 2, further comprising a holding member for securing said vibrating film, said two electrets and said two pressing boards together.
US67187A 1969-08-28 1970-08-26 Backplate for electret loudspeaker Expired - Lifetime US3646280A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP44067613A JPS4815867B1 (en) 1969-08-28 1969-08-28

Publications (1)

Publication Number Publication Date
US3646280A true US3646280A (en) 1972-02-29

Family

ID=13349963

Family Applications (1)

Application Number Title Priority Date Filing Date
US67187A Expired - Lifetime US3646280A (en) 1969-08-28 1970-08-26 Backplate for electret loudspeaker

Country Status (6)

Country Link
US (1) US3646280A (en)
JP (1) JPS4815867B1 (en)
CA (1) CA933277A (en)
FR (1) FR2059726B1 (en)
GB (1) GB1318734A (en)
ZA (1) ZA705815B (en)

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3787642A (en) * 1971-09-27 1974-01-22 Gte Automatic Electric Lab Inc Electrostatic transducer having resilient electrode
US3894198A (en) * 1971-11-04 1975-07-08 Kureha Chemical Ind Co Ltd Electrostatic-piezoelectric transducer
US3894199A (en) * 1969-11-19 1975-07-08 Pioneer Electronic Corp Electret electrostatic electroacoustic transducer
US3894333A (en) * 1972-09-08 1975-07-15 Uniroyal Ltd Electromechanical transducer and method of making same
US3896274A (en) * 1973-10-04 1975-07-22 Thermo Electron Corp Electret earphone
US20060072770A1 (en) * 2004-09-22 2006-04-06 Shinichi Miyazaki Electrostatic ultrasonic transducer and ultrasonic speaker
US20090016551A1 (en) * 2007-07-12 2009-01-15 Industrial Technology Research Institute Electrostatic electroacoustic transducers
US20100177926A1 (en) * 2007-03-23 2010-07-15 Sennheiser Electronic Gmbh & Co. Kg Capacitive Electroacoustic Transducer and Microphone
US20110033079A1 (en) * 2009-08-10 2011-02-10 Industrial Technology Research Institute Flat loudspeaker structure
US20110146056A1 (en) * 2009-12-23 2011-06-23 Industrial Technology Research Institute Method and device of manufacturing speaker
US20120002826A1 (en) * 2010-06-30 2012-01-05 Tsung-Hung Wu Electret electroacoustic transducer
US20120014543A1 (en) * 2010-07-15 2012-01-19 Taiwan Electrets Electronics Co., Ltd. Electrostatic speaker and manufacturing method thereof and conductive backplate of the speaker
US20150023529A1 (en) * 2013-07-18 2015-01-22 Infineon Technologies Ag MEMS Devices, Interface Circuits, and Methods of Making Thereof
US20160157022A1 (en) * 2012-12-20 2016-06-02 The Regents Of The University Of California Electrostatic graphene speaker

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2330800C3 (en) * 1973-06-16 1981-10-01 Sennheiser Electronic Kg, 3002 Wedemark Electroacoustic transducer based on the electrostatic principle and process for its manufacture
JP5262288B2 (en) * 2007-09-27 2013-08-14 ヤマハ株式会社 Electrostatic speaker
EP2043386A3 (en) 2007-09-27 2013-04-24 Yamaha Corporation Electrostatic speaker

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1469120A (en) * 1964-12-28 1967-02-10 Matsushita Electric Ind Co Ltd Condenser microphone
US3373251A (en) * 1965-02-23 1968-03-12 Shure Bros Electrostatic transducer

Cited By (26)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3894199A (en) * 1969-11-19 1975-07-08 Pioneer Electronic Corp Electret electrostatic electroacoustic transducer
US3787642A (en) * 1971-09-27 1974-01-22 Gte Automatic Electric Lab Inc Electrostatic transducer having resilient electrode
US3894198A (en) * 1971-11-04 1975-07-08 Kureha Chemical Ind Co Ltd Electrostatic-piezoelectric transducer
US3894333A (en) * 1972-09-08 1975-07-15 Uniroyal Ltd Electromechanical transducer and method of making same
US3896274A (en) * 1973-10-04 1975-07-22 Thermo Electron Corp Electret earphone
US20060072770A1 (en) * 2004-09-22 2006-04-06 Shinichi Miyazaki Electrostatic ultrasonic transducer and ultrasonic speaker
US7668323B2 (en) * 2004-09-22 2010-02-23 Seiko Epson Corporation Electrostatic ultrasonic transducer and ultrasonic speaker
US20100177926A1 (en) * 2007-03-23 2010-07-15 Sennheiser Electronic Gmbh & Co. Kg Capacitive Electroacoustic Transducer and Microphone
US8406451B2 (en) * 2007-03-23 2013-03-26 Sennheiser Electronic Gmbh & Co. Kg Capacitive electroacoustic transducer and microphone
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
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
US20110146056A1 (en) * 2009-12-23 2011-06-23 Industrial Technology Research Institute Method and device of manufacturing speaker
US8322018B2 (en) * 2009-12-23 2012-12-04 Industrial Technology Research Institute Method of manufacturing speaker
US20120002826A1 (en) * 2010-06-30 2012-01-05 Tsung-Hung Wu Electret electroacoustic transducer
US20120014543A1 (en) * 2010-07-15 2012-01-19 Taiwan Electrets Electronics Co., Ltd. Electrostatic speaker and manufacturing method thereof and conductive backplate of the speaker
US8600083B2 (en) * 2010-07-15 2013-12-03 Taiwan Electrets Electronics Co., Ltd. Electrostatic speaker and manufacturing method thereof and conductive backplate of the speaker
US20140013581A1 (en) * 2010-07-15 2014-01-16 Taiwan Electrets Electronics Co., Ltd. Electrostatic speaker and manufacturing method thereof and conductive backplate of the speaker
US20160157022A1 (en) * 2012-12-20 2016-06-02 The Regents Of The University Of California Electrostatic graphene speaker
US10425742B2 (en) * 2012-12-20 2019-09-24 The Regents Of The University Of California Electrostatic graphene speaker
US10582305B2 (en) 2012-12-20 2020-03-03 The Regents Of The University Of California Electrostatic graphene speaker
US10771903B2 (en) 2012-12-20 2020-09-08 The Regents Of The University Of California Electrostatic graphene speaker
US11252512B2 (en) 2012-12-20 2022-02-15 The Regents Of The University Of California Electrostatic graphene speaker
US20150023529A1 (en) * 2013-07-18 2015-01-22 Infineon Technologies Ag MEMS Devices, Interface Circuits, and Methods of Making Thereof
US9179221B2 (en) * 2013-07-18 2015-11-03 Infineon Technologies Ag MEMS devices, interface circuits, and methods of making thereof

Also Published As

Publication number Publication date
JPS4815867B1 (en) 1973-05-17
DE2042351A1 (en) 1972-03-02
DE2042351B2 (en) 1972-07-27
FR2059726A1 (en) 1971-06-04
ZA705815B (en) 1971-04-28
FR2059726B1 (en) 1974-04-26
GB1318734A (en) 1973-05-31
CA933277A (en) 1973-09-04

Similar Documents

Publication Publication Date Title
US3646280A (en) Backplate for electret loudspeaker
US3118022A (en) Electroacoustic transducer
US3008013A (en) Electrostatic loudspeakers
US3829623A (en) Planar voice coil loudspeaker
US3894199A (en) Electret electrostatic electroacoustic transducer
US2045404A (en) Piezoelectric vibrator device
GB2044583A (en) Capacitor microphones
JP2021507551A (en) Ultra-small flat speaker
US3118979A (en) Electrostatic transducer
JP2022174260A (en) Electroacoustic transducer and electroacoustic transducing device
US3066200A (en) Speaker device
GB2028056A (en) Lelctro-acoustic tranducers
US3896274A (en) Electret earphone
US20100111335A1 (en) Electronic device with electret electro-acoustic transducer
US3654402A (en) Transducer for converting acoustic vibrations into electrical oscillations, and vice versa, in the form of a diaphragm coated with at least one layer of a piezo-electric material
JPS6163193A (en) Electroacoustic transducer
US3894333A (en) Electromechanical transducer and method of making same
US2934612A (en) Electrostatic speaker
US4494032A (en) Transducer plate for electro-acoustic transducers
US2406119A (en) Microphone
KR101500562B1 (en) Piezoelectric Speaker
JPH0378040B2 (en)
US1839130A (en) Electrostatic loud speaker
US3649775A (en) Electro-static phonograph pickup
US1639924A (en) Device for transmitting or reproducing sound