US3700829A - Magnetic stereophonic phonograph pickup - Google Patents

Magnetic stereophonic phonograph pickup Download PDF

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Publication number
US3700829A
US3700829A US885220A US3700829DA US3700829A US 3700829 A US3700829 A US 3700829A US 885220 A US885220 A US 885220A US 3700829D A US3700829D A US 3700829DA US 3700829 A US3700829 A US 3700829A
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US
United States
Prior art keywords
magnetic
armature
portions
permanent magnet
pair
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Expired - Lifetime
Application number
US885220A
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English (en)
Inventor
Vilhelm Anneberg
Ellen Clemmensen
Robert Gudmandsen
Axel Scheibel
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FONOFILM IND
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FONOFILM IND
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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
    • H04R1/00—Details of transducers, loudspeakers or microphones
    • H04R1/16—Mounting or connecting stylus to transducer with or without damping means
    • 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
    • H04R11/08—Gramophone pick-ups using a stylus; Recorders using a stylus
    • H04R11/12—Gramophone pick-ups using a stylus; Recorders using a stylus signals being recorded or played back by vibration of a stylus in two orthogonal directions simultaneously

Definitions

  • MAGNETIC STEREOPHONIC PHONQGRAPH PICKUP [72] Inventors: Vllhelm Anneberg, l-ierlev; Ellen Clemmensen, Birkerod; Robert Gudmandsen, Tastrup; Axel Schelbel,
  • SHEET 2 [IF 2 MAGNETIC STEREOPHONIC PHONOGRAPH PICKUP each other the signals produced by movements of the stylus can be decomposed into two components each corresponding to its respective recording track of a stereophonic record.
  • the armature itself is constituted by a pennanentmagnet.
  • the still increasing requirements as to reproduction of signals at the upper end of the tone frequency spectrum has led to the development of pickups in which the effective stylus mass has been reduced by using a permanent magnet placed outside the oscillatcommon with other magnetic pickup'assemblies that the armature is coupled magnetically in series with the coil carrying legs, so that the signal producing flux changes are produced by alterations of the overall reluctance of the magnetic circuit caused by movements of the armature.
  • a novel structure in which the armature is so placed that it forms a magnetic load coupled in parallel to the permanent magnet or magnets, meaning that the armature and the magnet or magnets form a magnetic circuit independently of the four coil carrying legs which form two magnetic conductors each having both ends engaging the same poleface of said magnet or pole faces of the same polarity of said magnets.
  • both ends of each magnetic conductor are at the same magnetic potential and hence no flux is flowing through the coil carrying legs.
  • An object of the invention is to provide an improved electromagnetic transducer in which the effective mass of the oscillating stylus system is reduced by placing the permanent magnet or magnets outside said system.
  • a still further object of the invention is to provide a magnetic structure for use in a transducer in which the coil carrying legs can be made very thin thus allowing the use of signal coils having low resistance and capaci-
  • Another object of the invention is to providean electromagnetic transducer which is easy and cheap to produce.
  • Still another object of the invention is to provide a magnetic stereo pickup having improved sound reproduction characteristics, particularly at the upper end of the tone frequency range.
  • FIG. 1 is a longitudinal section of an embodiment of the pickup according to the invention.
  • FIG. 2 is a section along the line IIII in FIG. 1,
  • FIG. 2A shows a monophonic variation of the section shown in FIG. 2,
  • FIG. 3 is a perspective view of the front end of the magnetic system and the stylus assembly mounted therein,
  • FIGS. 4 and 4a show schematically one half of the magnetic system with the armature in the neutral and deflected position, respectively,
  • FIGS. 5 and 5A are similar schematics showing a second embodiment of the magnetic system in which the armature is constituted by a permanent magnet.
  • the pickup shown in FIGS. 1-3 comprises a housing 1 cast in a suitable plastics material. At one end the housing has a recess 7 in which is mounted a contact member 2 with four legs 3, of which only two are shown in FIG. 1. At the other end of the housing is provided a replaceable stylus assembly comprising a 'cast plastic support body 4 which, by means of a projecting hollow guide pin 5 of non-circular cross-section, engages a recess 6 formed in the housing 1 and having the same cross-section.
  • a through-going recess with a rear portion 8 of substantially square cross-sec tion and a front portion 9 the cross-section of which, as indicated in FIG. 2, is formed as a middle circle and four peripheral circles tangential to the middle circle and equally spaced along the periphery thereof.
  • the said through-going recess 8, 9 serves as accomodationfor the magnetic system which comprises four cylindrical legs of permalloy, the front portions of which are disposed in their respective cylindrical edge portions of the recess 9 and extend rearwardly through the recess 8.
  • the rear ends of the legs 10 are attached to and interconnected magnetically by a cross member 11, which is likewise made of permalloy.
  • a cross member 11 which is likewise made of permalloy.
  • a coil 12 which is mounted in the recess 8, and each pair of diametrically opposed coils are connected to one another and to two of the legs 3 by leads 13.
  • an annular permanent magnet 14 which is magnetized in an axial direction and consists of a ceramic, magnetically anisotropic material.
  • the magnet 14 is disposed in an enlarged section of the recess 9 at the front of the housing 1.
  • an inclined cylindrical, throughgoing channel 15 opening in the under face of the body and forming an elongation of the recess 9 in the housing 1.
  • a tube 16 of a non-magnetic material, for instance aluminium which projects from the support body 4 and, when the stylus assembly 3 is fitted, enters the cylindrical central portion of the recess-9.
  • tubular soft iron armature 17 is mounted by means of an annular, resilient pad 18, for instance of rubber or neoprene, to be freely pivotable in all directions about a point disposed in or adjacent to the center of the pad.
  • the armature 17 is slightly-longer than the annular magnet 14 and is disposed co-axial with and symmetrically with respect to the magnet.
  • To the armature is attached one end of a tubular, thinwalled aluminium stylus arm 19 extending through the channel 15. The free end of the stylus arm 19 projecting outwardly of the support body' 4 is flattened and supports a stylus20.
  • ic annular magnet 14 shows great reluctance in all directions perpendicular to the axial directionand is therefore magnetically equivalent to two permanent rod magnets 14a and 14b disposed at the end and in ex-' tension of their respective legs as indicatedin FIGS. 4A and 4B, in which the said magnets 14a and 14b are presumed to have their north pole at the leg end.
  • the magnetic conductor formed by the legs 10 and the cross member 11 will have the same magnetic potential at its two end faces in the shown neutral positionof the armature 17, and no flux will therefore flow through this conductor.
  • the magnetic conductor 10, 11, 10 leads only the effective signal flux which changes direction in response to the annature oscillations, and the legs 10 can therefore be designed very thin without risking that the magnetic point of. operation deviates from the rectilinear part of the magnetization curve.
  • the stereo pickup described above and shown in FIGS. 1-3 of the drawings can be changed into a mono pickup, as shown in FIG. 2A, merely by removing one pair of legs 10 and rotating the remaining pair an angle of approximately 45 about the common axis of the magnetic structure with respect to the stylus assembly.
  • the armature 17 is constituted by a thin-walled tube of soft iron, by which the effective inertia of-the oscillating stylus assembly is minimized.
  • FIGS. 5 and 5A is schematically shown the magnetic circuit of an embodiment in reluctance of the magnets this will cause the magnetic which the armature 17 is constituted by a permanent magnet which may be tubular or rod shaped and which is poled oppositely to the fixed, outer magnet 14 or magnets 14a and 14b, so that it increases the short circuit flux. In this way the sensitivity of the pickup can be increased to. some degree.
  • legs 10 may be square or rectangularlin cross-section instead of circular as also the armature may have other cross-section shapes.
  • a magnetic structure for a stereophonic pickup in the form of an electromechanical transducer comprising a hollow cylindrical magnet made of amagnetizable ceramic material and having magnetic poles of opposite polarity at the end .faces thereof,- four elongated core members abutting one end face of said magnet and extending therefrom in a direction parallel to the axis thereof, said core members being arranged symmetrically with respect tosaid axis, means for magnetically interconnecting said core members'at the. ends thereof remote from said magnet, further comprising a stylus carrying armature, and means supporting said armature within and coaxial with said hollow cylindrical magnet for pivotal movement in all directions about a point of said axis spaced from the center point of said magnet.
  • An electromagnetic transducer comprising in combination: a housing having a bore extending obliquely from one surface thereof, an annular permanent magnet of a ceramic material supported within said housing coaxially with and surrounding said bore a small distance from the outer end thereof, a ring of elastic material mounted within and engaging the walls of said bore adjacent the outer end of said magnet, a tubular armature supported by said ring and extending coaxially with said bore and said magnet beyond the inner end of the latter, a stylus arm fixed tosaid armature and carrying a stylus on its outer end extending beyond said surface of said housing, four rods of a high permeance material and with circular cross-section extending parallel to and equiangularly spaced around the axis of said bore, said rods abutting the inner end face of said magnet with their outer ends and extending beyond the inner end of said bore, a cross-piece of magnetizable material magnetically interconnecting the inner ends of said rods and fixedly held in said housing, and'four coils mounted on
  • An electromechanical transducer comprising a magnetic structure defining an airgap and symmetrically disposed with respect to an axis therein, a stylus carrying armature extending through said airgap and means pivotally mounting said armature around a pivot located on said axis adjacentone end of the airgap, said magnetic structure comprising magnetic means surrounding the armature .and having magnetic poles of one polarity adjacent one end of the armature and magnetic poles of the opposite polarity adjacent the other end of the armature, two pairs of core members symmetrically disposed with respect to the axis of the airgap and defining planes forming a right angle, said core members abutting magnetic pole faces of the same polarity at one end of said magnetic means, means for magnetically interconnecting the core members of each of said pairs at the ends thereof remote from said pole faces, and a coil mounted on each of said core members.
  • An electromagnetic transducer comprising:
  • magnetic conductor means magnetically connecting two pole faces of said permanent magnet means having the same polarity, said two pole faces being connected to said magnetic conductor means;
  • said permanent magnet means comprises four bar magnets arranged symmetrically and equiangularlyspaced around said commonlongitudinal
  • said magnetic conductor means comprises four rodshaped members of a high permeance material and a common cross-piece magnetically interconnecting respective one ends of said four rod-shaped members, said four bar magnets connected to and forming extensions of the opposite ends of respective ones of said rod-shaped members;
  • said coil means and further coil'means together comprise two pairs of series connected coil pairs oppositely disposed on portions of said rod-shaped members.
  • An electromagnetic transducer having a magnetic structure comprising an annular cylindrical. magnet of a ceramic material magnetized in an axial direction and having a plurality of angularly spaced portions, magnetic conductor means, portions of which are sur rounded'by a coil, interconnecting a first pair of said angularly spaced portions, a stylus carrying armature, means mounting said armature between said first pair of angularly spaced portions for pivotal movement in response to stylus movements in the plane of said first pair of spaced portions to cause variations in the magnetic load imparted to said spaced portions by said armature, said magnetic conductor means interconnecting two pole faces of the same polarity of said first pair of angularly spaced portions.
  • An electromagnetic transducer as defined in claim 9, further comprising a second magnetic structure having a second pair of angularly spaced portions arranged in spaced parallel relationship and interconnected by a second magnetic conductor, portions of which are surrounded by a second coil, wherein the planes of said first and second pairs of spaced portions form substantially right angles with respect to each other and wherein said first and second magnetic structures have a common longitudinal axis, said armature being mounted for pivotal movement in all direction between said first and second pairs of spaced portions.
  • said first and second magnetic conductors comprise four parallel rods of a high permeance material arranged symmetrically and equiangularly spaced around the axis of said cylindrical magnet with one end of said rods abutting one end face thereof, the opposite ends of said rods being magnetically interconnected by a common cross piece.
  • An electromechanical transducer comprising:
  • yoke means magnetically connecting pole faces of like polarity of each said pair of permanent magnet portions together,.said pole faces being connected to saidyoke means;
  • said yoke means magnetically connects further pole faces of like polarity of said further pair of permanent magnet portions
  • said mounting means mounting said armature for pivotal movement in all directions about a pivot point on the central axis of said airgap and spaced therealong from a central point of symmetry of said pair and further pair of permanent magnet portions.
  • said permanent magnetic portions comprise respective angularly spaced integral parts of a hollow cylindrical body of a magnetizable anisotropic material and having its direction of maximum permeability substantially'parallel to its axis, said body being permanently magnetized in said direction, and surrounding said airgap.
  • An electromechanical transducer as defined .in
  • An electromechanical transducer asv defined in claim 14, wherein said means for mounting said armature comprises a ring of resilient material supported along its outer periphery and engaging the armature along its inner eriphery.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Electromagnetism (AREA)
  • Reciprocating, Oscillating Or Vibrating Motors (AREA)
  • Electromagnets (AREA)
US885220A 1969-03-25 1969-12-15 Magnetic stereophonic phonograph pickup Expired - Lifetime US3700829A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DK163669AA DK124049B (da) 1969-03-25 1969-03-25 Magnetisk pick-up.

Publications (1)

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US3700829A true US3700829A (en) 1972-10-24

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US885220A Expired - Lifetime US3700829A (en) 1969-03-25 1969-12-15 Magnetic stereophonic phonograph pickup

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US (1) US3700829A (enrdf_load_stackoverflow)
JP (1) JPS4927441B1 (enrdf_load_stackoverflow)
CH (1) CH522996A (enrdf_load_stackoverflow)
DK (1) DK124049B (enrdf_load_stackoverflow)
FR (1) FR2033011A5 (enrdf_load_stackoverflow)
GB (1) GB1293636A (enrdf_load_stackoverflow)
HK (1) HK64276A (enrdf_load_stackoverflow)
NL (1) NL7003987A (enrdf_load_stackoverflow)
NO (1) NO126413B (enrdf_load_stackoverflow)
SE (1) SE341968B (enrdf_load_stackoverflow)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3846592A (en) * 1973-03-29 1974-11-05 W Stanton Phonograph pickup cartridge for four channel recordings
US3851117A (en) * 1972-06-21 1974-11-26 Electroacustic Gmbh Electromagnetic sound pickup for the reproduction of quadrophonic sound recordings and the like
US3878342A (en) * 1972-08-18 1975-04-15 Fonofilm Ind A S Replaceable stylus for stereophonic phonograph pickup
US3881073A (en) * 1973-11-12 1975-04-29 Joseph F Grado Replaceable stylus-lever generator module for an electromagnetic cartridge
US4031336A (en) * 1975-02-10 1977-06-21 Grado Joseph F Electromagnetic pickup with magnetic gap displacement generator
US4037060A (en) * 1975-07-09 1977-07-19 Nippon Atsudenki Kabushiki Kaisha T/A Japan Piezo Co., Ltd. Stereophonic pickup cartridge
US4103116A (en) * 1974-12-05 1978-07-25 Nippon Gakki Seizo Kabushiki Kaisha Pickup cartridge with moving magnet armature
US4221937A (en) * 1978-08-10 1980-09-09 Fidelity-Research, Inc. Moving iron type cartridge
US4364120A (en) * 1978-10-06 1982-12-14 Kabushiki Kaisha Audio-Technica Pickup cartridge of moving coil type for phonograph

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3683128A (en) * 1970-06-29 1972-08-08 Joseph F Grado Flux-bridging stereophonic pickup
US7408433B1 (en) * 2007-01-12 2008-08-05 Saia-Burgess Inc. Electromagnetically actuated bistable magnetic latching pin lock
CN112606610B (zh) * 2020-12-24 2024-10-18 湖北科技学院 一种具有缓冲功能的无级调速微雕笔

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3294405A (en) * 1963-12-11 1966-12-27 Audio Dynamics Corp Phonograph pick-up
US3538266A (en) * 1967-10-06 1970-11-03 Micro Seiki Co Ltd Magnetic pickup with inducing magnet axially aligned with the armature

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3294405A (en) * 1963-12-11 1966-12-27 Audio Dynamics Corp Phonograph pick-up
US3538266A (en) * 1967-10-06 1970-11-03 Micro Seiki Co Ltd Magnetic pickup with inducing magnet axially aligned with the armature

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3851117A (en) * 1972-06-21 1974-11-26 Electroacustic Gmbh Electromagnetic sound pickup for the reproduction of quadrophonic sound recordings and the like
US3878342A (en) * 1972-08-18 1975-04-15 Fonofilm Ind A S Replaceable stylus for stereophonic phonograph pickup
US3846592A (en) * 1973-03-29 1974-11-05 W Stanton Phonograph pickup cartridge for four channel recordings
US3881073A (en) * 1973-11-12 1975-04-29 Joseph F Grado Replaceable stylus-lever generator module for an electromagnetic cartridge
US4103116A (en) * 1974-12-05 1978-07-25 Nippon Gakki Seizo Kabushiki Kaisha Pickup cartridge with moving magnet armature
US4031336A (en) * 1975-02-10 1977-06-21 Grado Joseph F Electromagnetic pickup with magnetic gap displacement generator
US4037060A (en) * 1975-07-09 1977-07-19 Nippon Atsudenki Kabushiki Kaisha T/A Japan Piezo Co., Ltd. Stereophonic pickup cartridge
US4221937A (en) * 1978-08-10 1980-09-09 Fidelity-Research, Inc. Moving iron type cartridge
US4364120A (en) * 1978-10-06 1982-12-14 Kabushiki Kaisha Audio-Technica Pickup cartridge of moving coil type for phonograph

Also Published As

Publication number Publication date
NO126413B (enrdf_load_stackoverflow) 1973-01-29
HK64276A (en) 1976-10-22
DK124049B (da) 1972-09-04
SE341968B (enrdf_load_stackoverflow) 1972-01-17
DE2007469A1 (de) 1970-10-08
JPS4927441B1 (enrdf_load_stackoverflow) 1974-07-18
FR2033011A5 (enrdf_load_stackoverflow) 1970-11-27
GB1293636A (en) 1972-10-18
DE2007469B2 (de) 1975-08-21
CH522996A (de) 1972-05-15
NL7003987A (enrdf_load_stackoverflow) 1970-09-29

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