US3836733A - Electro-acoustic armature transducer - Google Patents
Electro-acoustic armature transducer Download PDFInfo
- Publication number
- US3836733A US3836733A US00308381A US30838172A US3836733A US 3836733 A US3836733 A US 3836733A US 00308381 A US00308381 A US 00308381A US 30838172 A US30838172 A US 30838172A US 3836733 A US3836733 A US 3836733A
- Authority
- US
- United States
- Prior art keywords
- armature
- transducer
- electro
- lamina
- acoustic
- 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
- H04R11/00—Transducers of moving-armature or moving-core type
Definitions
- ABSTRACT A balanced armature electro-acoustic transducer has small permanent magnets on its armature and on the pole-pieces with each armature magnets poles facing like poles on the pole-pieces. Thus equal centering forces are set up.
- the arrangement uses rareear'th/cobalt alloys, which have a very high coercivity.
- the present invention relatesto an elfectro-acoustic transducer of the so-calle dmoving-iron:type,i.e. to one in which. the armature which drives (in the case of a loudspeaker orxa telephone earpiece) or is drivenby (in the case of a microphone) the diaphragm is a-member of aferro-magnetic material.
- anelectro-acoustic transducer inwhich an armature of amagnetically soft material is pivotally mounted so as to drive ,,on to be drivenby adiaphragrminwhich.
- each said pole-piece i'sv to microphones, loudspeakers and telephone earpieces,
- the-armature carries-amagnet at each of'its ends, each such: magnet, cooperating with two stationary magnets, as set out. above.
- FIG. 1' shows for explanatory purposes a conventionalrocking armature transducer
- FIG. 2 is an-explanatory-diag'ram of one embodiment of thepresent invention.
- FIG; 3 is'a slightlymore detailed representationzof a second embodiment:oftheinvention- DESCRIPTION. OF THE .P-REF ERRED EMBODIMENTS In one conventional rocking-armaturetransducer, a
- permanent magnet 1' is provided -with'two pole-piece members 2, 3,v each of' which has twopole-pieces as shown. Between thesepole-pieces there is-a pivoted armature 4 toone end'of whichis :coupled adiaphragm 5. Coilsaremounted on the pole+piecemembers 2 and 3. In the case. of.atelephone earpiece, the application of speech currents tothe coils causesthe armature 4 to rock aboutitscentralpivot andthus to drive the diaphragrn 5.
- the transducer has certain practicallir'nita- *tions-in:that'ifithearmature is deflected too far it is liable-to stick (or freeze) to the pole-pieces,,and that to keep itin acentralaposition a highrstiffnessisneeded in its pivotbearing.
- FIG. 2 The basic construction ofone form ofifloating armature transducer according to-the invention is shown in FIG. 2.
- the armature 10 carries smallmagnetsll, l2 atzeach of its ends, and (as inthe deviceof FIG. l)is.coupled to a diaphragm13;.
- magnet 11- is between two similar: magnets .14 and 15,
- the armature l0 is softly magnetic and has a coil wound on it to carry a signal current. If this current is in-sucha direction (as shown) as to make the left-hand end of the armature of a South polarity, then the lefthand endof the armature 10 moves upwards towards the magnet 14. When the current reverts to zero the armature, by virtue of the respulsive-forces on*it ,.is.immediately re-centralized. Thus it will be seen that with an alternating current in the coil, the armature oscillates 1 in sympathy with that current to drive the armature 13.
- the magnets used are rare-earth cobalt magnets whose coercivity is of the order of 10,000 oersted; compared with which Alnico V has a coercivity of about 500.
- the magnets can be small, and in the case of one transducer using magnets of a Samariumcobalt alloy they were 1mm cubes. With such an arrangement it is possible to obtain a floating armature with alow stiffness.
- the central magnet/armature arrangement is highly stablesince any deflection closes the spacing between magnetic. poles. of like polarity, which increases the centering force. Thus it is possible toobtain anarmature mounting of nearly zero stiffness,
- the overall acoustic impedanceof the transducer can be reduced until itis comparable-with theear impedance or with the air-'loadedi impedance. in the case of a microphone.
- the magnets themselvesform the pole-pieces, and since they work in a demagnetizing'field'they can exist in isolation without the usualsoft magnetic circuit; As will be seen below, however, the latter can still be used where this is convenient. As will be seen from the above discussion the magnets can be'very small, i.e. 1 mm cubes, so that their dimensions are comparable with'the dimensions of the other parts of the device,
- the transducer shown in FIG. 3 has a softiron return path 20 to the center of which is pivoted'anarmature 21, the left-hand end of which drives(or is driven by) a diaphragm.
- the armature and also the ends of the retum path 20 carry small magnets-poled as shown so that magnetically speaking the device of FIG. 3 is half that of FIG. 2, but with a soft ironreturn path.
- the armature is laminated with the outer laminae bent as shown into horns as at 22, 23 aimed at the two air gaps.
- the coil is wound about-the armature 21.
- the'central magnet provides positivestiffness to the armature vibrations, .while the outer laminae act like a conventionalbalanced armature giving negative stiffness.
- the dimensions are such that over small excursions from a central position the addition of the positive and negative stiffnesse's approach zero, and that for larger excursions positive stiffness exceeds negative stiffness.
- the coils can be mounted on the v within said field, and a diaphragm responsive to the movement of said armature-wherein theimprovement.
- an armature of laminated construction having a central lamina which carries a permanent magnet, two 1 other lamina one on each side of said central lamina, wherein each'said other-lamina has onegof its ends formed t'o'i a horn-like portion extending "to wards said magnetic field.
- a transducer according to claim 1 wherein said magnet is comprised of rare-earth cobalt alloys having a-coerc ivity in the order of 10,000 oersteds.
Landscapes
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Engineering & Computer Science (AREA)
- Acoustics & Sound (AREA)
- Signal Processing (AREA)
- Electrostatic, Electromagnetic, Magneto- Strictive, And Variable-Resistance Transducers (AREA)
- Audible-Bandwidth Dynamoelectric Transducers Other Than Pickups (AREA)
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB5993071A GB1364669A (en) | 1971-12-23 | 1971-12-23 | Electro acoustic transducers |
Publications (1)
Publication Number | Publication Date |
---|---|
US3836733A true US3836733A (en) | 1974-09-17 |
Family
ID=10484678
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US00308381A Expired - Lifetime US3836733A (en) | 1971-12-23 | 1972-11-21 | Electro-acoustic armature transducer |
Country Status (5)
Country | Link |
---|---|
US (1) | US3836733A (es) |
AU (1) | AU465688B2 (es) |
ES (1) | ES409986A1 (es) |
GB (1) | GB1364669A (es) |
IT (1) | IT972504B (es) |
Cited By (18)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3937904A (en) * | 1974-08-07 | 1976-02-10 | Hitachi Magnetics Corporation | Moving magnet electroacoustic transducer |
DE2810459A1 (de) * | 1977-03-14 | 1978-09-21 | Burundukov | Elektrodynamischer wandler von mechanischen schwingungen in elektrische signale und umgekehrt, stereo- und monophonie-tonkoepfe und elektrodynamisches mikrophon |
WO1994010817A1 (en) * | 1992-10-29 | 1994-05-11 | Knowles Electronics Co. | Electroacoustic transducer |
US5647013A (en) * | 1992-10-29 | 1997-07-08 | Knowles Electronics Co. | Electroacostic transducer |
US6075870A (en) * | 1996-12-02 | 2000-06-13 | Microtronic B.V. | Electroacoustic transducer with improved shock resistance |
US6658134B1 (en) | 1999-08-16 | 2003-12-02 | Sonionmicrotronic Nederland B.V. | Shock improvement for an electroacoustic transducer |
US20040027221A1 (en) * | 2002-04-02 | 2004-02-12 | Mikhail Godkin | Linear voice coil actuator as a controllable electromagnetic compression spring |
US20110243365A1 (en) * | 2010-03-31 | 2011-10-06 | Richard Tucker Carlmark | Moving Magnet Levered Loudspeaker |
US20110243366A1 (en) * | 2010-03-31 | 2011-10-06 | Richard Tucker Carlmark | Loudspeaker Moment and Torque Balancing |
CN104284279A (zh) * | 2014-11-03 | 2015-01-14 | 常州阿木奇声学科技有限公司 | 一种动铁喇叭的磁路系统 |
US9055370B2 (en) | 2012-08-31 | 2015-06-09 | Bose Corporation | Vibration-reducing passive radiators |
US9258648B2 (en) | 2014-03-07 | 2016-02-09 | Bose Corporation | Levered loudspeakers |
US9357279B2 (en) | 2014-03-07 | 2016-05-31 | Bose Corporation | Elastomeric torsion bushings for levered loudspeakers |
US9497549B2 (en) | 2014-03-07 | 2016-11-15 | Bose Corporation | Levered loudspeakers |
US9601969B2 (en) | 2014-03-07 | 2017-03-21 | Bose Corporation | Inhibiting rocking of loads driven by plural levers |
US20170118560A1 (en) * | 2015-10-23 | 2017-04-27 | Bose Corporation | Bushings Constrained by Compression in Levered Apparatus |
US9763013B2 (en) | 2013-03-15 | 2017-09-12 | Bose Corporation | Moving magnet motors |
CN108337587A (zh) * | 2017-01-20 | 2018-07-27 | 苏州三色峰电子有限公司 | 一种适用于自动化装配的受话器及其制作方法 |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US1559158A (en) * | 1923-12-11 | 1925-10-27 | Gen Electric | Sound-emitting device |
US1761745A (en) * | 1927-08-09 | 1930-06-03 | Paramount Famous Lasky Corp | Speaker |
US2073561A (en) * | 1934-08-16 | 1937-03-09 | Mccracken John | Sound reproducing means |
US3695945A (en) * | 1970-04-30 | 1972-10-03 | Gen Electric | Method of producing a sintered cobalt-rare earth intermetallic product |
-
1971
- 1971-12-23 GB GB5993071A patent/GB1364669A/en not_active Expired
-
1972
- 1972-11-21 US US00308381A patent/US3836733A/en not_active Expired - Lifetime
- 1972-12-04 AU AU49595/72A patent/AU465688B2/en not_active Expired
- 1972-12-19 IT IT33100/72A patent/IT972504B/it active
- 1972-12-22 ES ES409986A patent/ES409986A1/es not_active Expired
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US1559158A (en) * | 1923-12-11 | 1925-10-27 | Gen Electric | Sound-emitting device |
US1761745A (en) * | 1927-08-09 | 1930-06-03 | Paramount Famous Lasky Corp | Speaker |
US2073561A (en) * | 1934-08-16 | 1937-03-09 | Mccracken John | Sound reproducing means |
US3695945A (en) * | 1970-04-30 | 1972-10-03 | Gen Electric | Method of producing a sintered cobalt-rare earth intermetallic product |
Cited By (23)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3937904A (en) * | 1974-08-07 | 1976-02-10 | Hitachi Magnetics Corporation | Moving magnet electroacoustic transducer |
DE2810459A1 (de) * | 1977-03-14 | 1978-09-21 | Burundukov | Elektrodynamischer wandler von mechanischen schwingungen in elektrische signale und umgekehrt, stereo- und monophonie-tonkoepfe und elektrodynamisches mikrophon |
WO1994010817A1 (en) * | 1992-10-29 | 1994-05-11 | Knowles Electronics Co. | Electroacoustic transducer |
US5647013A (en) * | 1992-10-29 | 1997-07-08 | Knowles Electronics Co. | Electroacostic transducer |
US6075870A (en) * | 1996-12-02 | 2000-06-13 | Microtronic B.V. | Electroacoustic transducer with improved shock resistance |
US6658134B1 (en) | 1999-08-16 | 2003-12-02 | Sonionmicrotronic Nederland B.V. | Shock improvement for an electroacoustic transducer |
US20040027221A1 (en) * | 2002-04-02 | 2004-02-12 | Mikhail Godkin | Linear voice coil actuator as a controllable electromagnetic compression spring |
US6831538B2 (en) * | 2002-04-02 | 2004-12-14 | Bei Sensors And Systems Company, Inc. | Linear voice coil actuator as a controllable electromagnetic compression spring |
US8295536B2 (en) * | 2010-03-31 | 2012-10-23 | Bose Corporation | Moving magnet levered loudspeaker |
US20110243365A1 (en) * | 2010-03-31 | 2011-10-06 | Richard Tucker Carlmark | Moving Magnet Levered Loudspeaker |
US8295537B2 (en) * | 2010-03-31 | 2012-10-23 | Bose Corporation | Loudspeaker moment and torque balancing |
US20110243366A1 (en) * | 2010-03-31 | 2011-10-06 | Richard Tucker Carlmark | Loudspeaker Moment and Torque Balancing |
US9055370B2 (en) | 2012-08-31 | 2015-06-09 | Bose Corporation | Vibration-reducing passive radiators |
US9763013B2 (en) | 2013-03-15 | 2017-09-12 | Bose Corporation | Moving magnet motors |
US10028062B2 (en) | 2013-03-15 | 2018-07-17 | Bose Corporation | Driving plural armatures with a common stator |
US9258648B2 (en) | 2014-03-07 | 2016-02-09 | Bose Corporation | Levered loudspeakers |
US9357279B2 (en) | 2014-03-07 | 2016-05-31 | Bose Corporation | Elastomeric torsion bushings for levered loudspeakers |
US9497549B2 (en) | 2014-03-07 | 2016-11-15 | Bose Corporation | Levered loudspeakers |
US9601969B2 (en) | 2014-03-07 | 2017-03-21 | Bose Corporation | Inhibiting rocking of loads driven by plural levers |
CN104284279A (zh) * | 2014-11-03 | 2015-01-14 | 常州阿木奇声学科技有限公司 | 一种动铁喇叭的磁路系统 |
US20170118560A1 (en) * | 2015-10-23 | 2017-04-27 | Bose Corporation | Bushings Constrained by Compression in Levered Apparatus |
US10154347B2 (en) * | 2015-10-23 | 2018-12-11 | Bose Corporation | Bushings constrained by compression in levered apparatus |
CN108337587A (zh) * | 2017-01-20 | 2018-07-27 | 苏州三色峰电子有限公司 | 一种适用于自动化装配的受话器及其制作方法 |
Also Published As
Publication number | Publication date |
---|---|
ES409986A1 (es) | 1975-12-01 |
IT972504B (it) | 1974-05-31 |
AU4959572A (en) | 1974-06-06 |
AU465688B2 (en) | 1975-10-02 |
GB1364669A (en) | 1974-08-29 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: STC PLC, 10 MALTRAVERS STREET, LONDON, WC2R 3HA, E Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:INTERNATIONAL STANDARD ELECTRIC CORPORATION, A DE CORP.;REEL/FRAME:004761/0721 Effective date: 19870423 Owner name: STC PLC,ENGLAND Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:INTERNATIONAL STANDARD ELECTRIC CORPORATION, A DE CORP.;REEL/FRAME:004761/0721 Effective date: 19870423 |