US3878342A - Replaceable stylus for stereophonic phonograph pickup - Google Patents

Replaceable stylus for stereophonic phonograph pickup Download PDF

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Publication number
US3878342A
US3878342A US281810A US28181072A US3878342A US 3878342 A US3878342 A US 3878342A US 281810 A US281810 A US 281810A US 28181072 A US28181072 A US 28181072A US 3878342 A US3878342 A US 3878342A
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US
United States
Prior art keywords
stylus
armature
housing
permanent magnet
rods
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
US281810A
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English (en)
Inventor
Henning Schmidt Madsen
Robert Gudmandsen
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.)
FONOFILM IND
FONOFILM INDUSTRI AS
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FONOFILM IND
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 FONOFILM IND filed Critical FONOFILM IND
Priority to US281810A priority Critical patent/US3878342A/en
Priority to DE19727242940U priority patent/DE7242940U/de
Priority to DE2257284A priority patent/DE2257284A1/de
Priority to CH1767572A priority patent/CH546528A/de
Priority to GB2991973A priority patent/GB1384968A/en
Priority to JP48091818A priority patent/JPS4960504A/ja
Application granted granted Critical
Publication of US3878342A publication Critical patent/US3878342A/en
Priority to HK746/76*UA priority patent/HK74676A/xx
Priority to JP11331180A priority patent/JPS5635595A/ja
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
    • 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

  • ABSTRACT A magnetic stereophonic phono cartridge having a replaceable stylus unit.
  • the stylus unit comprises a sup port body including an armature of permeance mate- 26 Claims, 3 Drawing Figures l6 1 I N a REPLACEABLE STYLUS FOR STEREOPHONIC PHONOGRAPI-I PICKUP BACKGROUND OF THE INVENTION 1.
  • Field of the Invention This invention, like that of U.S. Pat. application Ser. No. 885,220, filed Dec. 15, 1969, now U.S. Pat. No. 3,700,829 relates to electromagnetic transducers for reproduction of stereophonic phonograph records and particularly to replaceable stylus assemblies in which a portion of the magnetic circuit is incorporated into the replaceable assembly.
  • the invention relates to such transducers having a magnetic structure defining an airgap and comprising four magnetic legs each surrounded by its respective coil and forming an airgap in which a stylus carrying armature is pivotally mounted; the armature also carries permanent magnetic means for producing a magnetic field which cooperates with the magnetic legs to form a magnetic circuit loop.
  • the armature itself is constituted by a permanent magnet.
  • the still increasing requirements as to reproduction of signals at the upper end of te 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 oscillating stylus system for producing the magnetizing force, so that the armature may be constituted by a light tube of magnetically conducting material such as soft iron.
  • the known pickups of this kind have the feature in common 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 movement of the armature.
  • a novel structure in which the armature is so placed that it forms a magnetic load coupled in parallel with the permanent magnet or magnets, the four coil carrying legs forming two magnetic conductors each having both ends engaging the same pole face of the permanent magnet or pole faces of the same polarity of the permanent magnet.
  • 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 capacity.
  • Another object is to provide a replaceable stylus assembly in which the permanent magnet portion is incorporated into the replaceable assembly.
  • Another object of the invention is to provide an 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. 3 is a perspective view of the front end of the magnetic system with the stylus assembly partially removed.
  • 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 plastics support body 4 which, by means of a projecting holow 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 v a rear portion 8 of substantially square cross-section 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 accommodation for the magnetic system which comprises four cylindrical legs 10 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 II, which is likewise made of permalloy.
  • a cross member II 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.
  • a -tube 16 of a nonmagnetic material, for instance aluminum which projects from the support body 4 and, when the stylus assembly is fitted, enters the cylindrical central portion of the recess 9.
  • An annular permanent magnet 14, which is magnetized in the axial direction and which consists of a ceramic, magnetically anisotropic material is coaxially mounted about the exterior portion of tube 16 adjacent the face of body 4.
  • a tubular soft iron armature 17 is mounted within the tube 16 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 coaxially with and symmetrically with respect to the magnet.
  • To the armature is attached one end of a tubular, thinwalled aluminum stylus are 19 extending through the channel 15.
  • the free end of the sytlus arm 19 projecting outwardly of the support body 4 is flattened and supports a stylus 20.
  • a magnetic screen 21 which extends upwardly along the front face of the housing between the housing and the support body 4 of the stylus assembly.
  • the annular magnet is firmly attached to the replaceable stylus unit.
  • the armature could consist not only of a permeance material but also of a magnet having its poles positioned opposite the poles of the annular magnet. If such an embodiment is used, it is, of course, of greatest importance that during the production of the stylus unit the two magnets be positioned correctly relatively to one another. Further, it would completely spoil the armature magnet if, by replacement ofthe stylus unit, this armature magnet were removed from its position within the annular magnet. It might also be mentioned that in the novel contruction disclosed herein the annular magnet will have a tendency to support the forces holding the stylus unit firmly in its position with the annular magnet abutting the free ends of the four rods in the housing.
  • the anisotropic ceramic annular magnet 14 shows great reluctance in all directions perpendicular to the axial direction and is therefore magnetically equivalent to two permanent rod magnets disposed at the end and in extension of their respective legs 10. Assuming the two magnets to be of equal strength, the magnetic conductor formed by the legs and the cross member 11 will have the same magnetic potential at its two end faces in the neutral position of the armature 17, and no flux will therefore flow through this conductor.
  • the armature as a result of the stylus movement oscillates upwards in the plane of the paper it will approach the upper magnet and thereby reduce the reluctance in the short circuit flux path for said magnet and simultaneously move away from the lower magnet, with the result that the short circuit flux thereof meets increased reluctance.
  • the upper short circuit flux will be increased and the lower short circuit flux will be reduced.
  • this will cause the magnetic potential at the north pole of the upper magnet to be reduced, while the magnetic potential at the north pole of the lower magnet will be increased.
  • Armature oscillations resulting from the other sound channel follow a direction perpendicular to the plane of the paper and are converted in the same manner to electrical voltages in the second half of the electromagnetic system disposed in this plane.
  • the magnetic conductor l0, ll, 10 leads only the effective signal flux which changes direction in response to the armature 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, 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. It is within the scope of the invention, however, to replace the soft iron armature by a permanent magnet which may be tubular or rod shaped and which is poled oppositely to the fixed, outer magnet, so that it increases the short circuit flux. in this way, the sensitivity of the pickup can-be increased to some degree.
  • the invention is not limited to the embodiments shown and described and that it will be possible within the scope of the invention to modify the structure in various respects.
  • the legs 10 may be square or rectangular in cross-section instead of circular as also the armature may have other cross-section shapes.
  • An electromechanical transducer comprising a housing having a bore extending at one end obliquely into one surface thereof and a replaceable stylus unit adapted to be removably inserted into said bore, said stylus unit comprising an annular permanent magnet, a stylus carrying armature resiliently pivotally supported within said unit and disposed coaxially with said annular magnet, plural rods of a high permeance material disposed within said housing and spaced around the axis of said bore, means including magnetizable material magnetically interconnecting the inner ends of said rods, and coils mounted on said rods, thearrangemjent of said rods within said housing being such that their free end faces abut one pole face of the annular permanent magnet when said stylus unit is inserted into said housing.
  • said armature is a hollow a'nnular cylinder havin g an axial length greater than the axial length of said permanent magnet.
  • an electromechanical transducer comprising a housing having at one obliquely 'into one surface thereof, four rods ofa high permeancematerial extending parallel to and equiangularly spaced around the axis of said bore and having outer and inner ends, means magnetically interconnecting the inner ends of said rods, and four coils mounted on said rods respectively between the other end of said bore and said inner ends, said coils being series connected in pairs each comprising oppositely disposed coils and connected to respective terminals, the provision of a replaceable stylus unit adapted to be inserted into the housing by sliding the unit in the direction of the axis of said bore in the housing, said stylus unit comprising a hollow tube of nonmagnetic material, an armature of permeance material provided with a stylus arm with a stylus at the free end thereof, said armature being supported with respect to said hollow tube by means ofa ring of elastic material, and an annular permanent magnet magnetized in the axial direction mounted on and externally of said hollow tube, said
  • said armature is a hollow cylinder
  • said stylus unit includes a stylus support rod having ne end supported internally of said hollow cylinder and having another end supporting a stylus.
  • said armature is a hollow cylinder of magnetically permeant material.
  • a transducer comprising a plastic body having terminals extending therefrom, a stylus bearing replaceable cartridge, said body including a recess, said cartridge having an extension mating into said recess to provide a rigid mounting for said cartridge relative to said body, said body mounting four relatively spaced permanent rods having inner ends and outer ends, means magnetically shorting said outer ends, said cartridge including a stylus assembly which includes an annular permanent magnet having its ends of opposite polarilties, a magnetic armature passing through said annular permanent magnet, means mounting said armature for free pivoting with respect to said permanent magnet, a stylus arm secured to said armature at one end of said sytlusarm, a stylus secured to the other end of said stylus arm, said permanent magnet being positioned to abut said inner ends when said cartridge is inserted into said body, and coils connected to said terminalsand respectively wound about said rods.
  • said body includes a further recess for accepting said stylus mounting, said further recess and said first mentioned recess having parallel axes.
  • said body includes a further recess for accepting said stylus mounting, said further recess and said first mentioned recess having parallel axes.
  • said body includes a further recess for accepting said stylus mounting, said further recess and said first mentioned recess having parallel axes.
  • said body includes a further recess for accepting said stylus mounting, said further recess and said first mentioned recess having parallel axes.
  • a replaceable stylus assembly for a phonograph record reproducer comprising a non-magnetic hollow cylinder, a cylindrical axially hollow permanent magnet mounted externally on said hollow cylinder, said magnet having oppositely polarized ends, a flexible annulus mounted interiorly of said hollow cylinder, said flexible annulus being coaxial with said magnet and offset axially from said magnet, a hollow cylindrical permeance armature mounted interiorly of said annulus, said atmature extending axially beyond said magnet in two directions, a stylus arm having one end secured within said hollow of said armature and having another end externally of said armature, and a stylus secured to said another end.
  • An electromechanical transducer comprising a housing having a bore extending at one end obliquely from one surface thereof and a replaceable stylus unit adapted to be removably inserted into said bore, said stylus unit comprising an annular permanent magnet, a stylus carrying armature pivotally supported within said unit and disposed coaxially with said annular magnet, four rods of a high permeance material disposed within said housing extending parallel to and equiangularly spaced around the axis of said bore and extending beyond the other end thereof, a cross piece of magnetizable material magnetically interconnecting the inner ends of said rods and fixably held in the said housing, and four coils mounted on said rods at the inner ends thereof adjacent said cross-piece, said coils being series connected in pairs each comprising oppositely disposed coils and connected to respective terminals, the arrangement of said rods within said housing being such that their free end faces will abut one pole face of the annular permanent magnet, when the said stylus unit is inserted into the housing with
  • An electromechanical transducer as claimed in claim 21 in which the stylus unit comprises a connecting member extending parallel to the axis of the armature, and wherein the housing comprises a recess adapted to receive the connecting member when mounting the stylus unit on the housing.
  • replaceable stylus unit further comprises a tubular member of a non-magnetizable material, an annular member of an elastic material for pivotally supporting the stylus carrying armature with said tubular member coaxially therewith, said annular permanent magnet surrounding said tubular member coaxially therewith and adjacent said annular supporting member therein.
  • an electromechanical transducer comprising a housing having a bore extending at one end obliquely from one surface thereof, four rods of a high permeance material extending parallel to and equiangularly spaced around the axis of said bore and extending beyond the other 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 said rods respectively between the other end of said bore and said cross-piece, said coils being series connected in pairs each comprising oppositely disposed coils and connected to respective terminals, the provision of a replaceable stylus unit adapted to be inserted into the housing by sliding the unit in the direction of the axis of said bore in the housing, said stylus unit comprising an armature of permeance material and being provided with a stylus arm with a stylus at the free end thereof, said armature being supported in the unit by means of a ring of elastic material, and an annular permanent magnet being magnet

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Knitting Machines (AREA)
  • Reciprocating, Oscillating Or Vibrating Motors (AREA)
US281810A 1972-08-18 1972-08-18 Replaceable stylus for stereophonic phonograph pickup Expired - Lifetime US3878342A (en)

Priority Applications (8)

Application Number Priority Date Filing Date Title
US281810A US3878342A (en) 1972-08-18 1972-08-18 Replaceable stylus for stereophonic phonograph pickup
DE19727242940U DE7242940U (de) 1972-08-18 1972-11-22 Austauschbares nadelgeraet fuer tonabnehmer
DE2257284A DE2257284A1 (de) 1972-08-18 1972-11-22 Austauschbares nadelgeraet fuer tonabnehmer
CH1767572A CH546528A (de) 1972-08-18 1972-12-05 Elektromechanischer tonabnehmer.
GB2991973A GB1384968A (en) 1972-08-18 1973-06-22 Electromechanical transducers
JP48091818A JPS4960504A (de) 1972-08-18 1973-08-17
HK746/76*UA HK74676A (en) 1972-08-18 1976-12-02 Electromechanical transducers
JP11331180A JPS5635595A (en) 1972-08-18 1980-08-18 Stereo exchangeable stylus unit

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US281810A US3878342A (en) 1972-08-18 1972-08-18 Replaceable stylus for stereophonic phonograph pickup

Publications (1)

Publication Number Publication Date
US3878342A true US3878342A (en) 1975-04-15

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US281810A Expired - Lifetime US3878342A (en) 1972-08-18 1972-08-18 Replaceable stylus for stereophonic phonograph pickup

Country Status (6)

Country Link
US (1) US3878342A (de)
JP (2) JPS4960504A (de)
CH (1) CH546528A (de)
DE (2) DE7242940U (de)
GB (1) GB1384968A (de)
HK (1) HK74676A (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4272652A (en) * 1978-05-25 1981-06-09 Nippon Atsudenki K.K. Moving coil type stereophonic pickup cartridge
FR2502882A1 (fr) * 1981-03-26 1982-10-01 Mimran Guy Lecteur (stylet porte pointe) pour phonocapteur magnetodynamique

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5832398Y2 (ja) * 1976-04-30 1983-07-18 パイオニア株式会社 電磁型カ−トリッジ
JPS538102A (en) * 1976-07-12 1978-01-25 Torio Kk Pickup cartridge

Citations (5)

* 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
US3694586A (en) * 1969-11-03 1972-09-26 Joseph F Grado Toroidal armature stereophonic pickup
US3700829A (en) * 1969-03-25 1972-10-24 Fonofilm Ind As Magnetic stereophonic phonograph pickup
US3763335A (en) * 1971-02-23 1973-10-02 Matsushita Electric Ind Co Ltd Pickup cartridge with magnet armature having opposite axial sides of like polarity and central portion of opposite polarity

Patent Citations (5)

* 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
US3700829A (en) * 1969-03-25 1972-10-24 Fonofilm Ind As Magnetic stereophonic phonograph pickup
US3694586A (en) * 1969-11-03 1972-09-26 Joseph F Grado Toroidal armature stereophonic pickup
US3763335A (en) * 1971-02-23 1973-10-02 Matsushita Electric Ind Co Ltd Pickup cartridge with magnet armature having opposite axial sides of like polarity and central portion of opposite polarity

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4272652A (en) * 1978-05-25 1981-06-09 Nippon Atsudenki K.K. Moving coil type stereophonic pickup cartridge
FR2502882A1 (fr) * 1981-03-26 1982-10-01 Mimran Guy Lecteur (stylet porte pointe) pour phonocapteur magnetodynamique

Also Published As

Publication number Publication date
JPS4960504A (de) 1974-06-12
JPS5635595A (en) 1981-04-08
DE7242940U (de) 1973-04-05
HK74676A (en) 1976-12-10
CH546528A (de) 1974-02-28
GB1384968A (en) 1975-02-26
DE2257284A1 (de) 1974-03-07

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