US3627931A - Moving magnet type stereo pickup - Google Patents

Moving magnet type stereo pickup Download PDF

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Publication number
US3627931A
US3627931A US699936A US3627931DA US3627931A US 3627931 A US3627931 A US 3627931A US 699936 A US699936 A US 699936A US 3627931D A US3627931D A US 3627931DA US 3627931 A US3627931 A US 3627931A
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United States
Prior art keywords
armature
magnet
cantilever arm
moving
pickup
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Expired - Lifetime
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US699936A
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English (en)
Inventor
Hitoshi Matsuda
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Nippon Columbia Co Ltd
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Nippon Columbia Co Ltd
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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
    • 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
    • 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

Definitions

  • ABSTRACT A Stereo Pickup havingvan arm for carrying a Field olSearch 179/1004] D 00 41 K loo 41 Z 4 M 100 41 s stylus at one end and an armature comprlsmg a flat magnet magnetized in the direction of its thickness attached to the [56] References m other end of the arm and the pickup Supported so that the ar- UNITED STATES PATENTS mature has 1ts center of gravltyat substantlally the center of vlbratton of the vlbratlon system and a.
  • This invention relates to a novel stereo pickup for use with 45-45 stereo records and more particularly refers to a moving msving-magnet'type stereo pickup.
  • a cantilever arm is mounted on one end of a bar magnet
  • a stylus is fixedly mounted on one end of the cantilever arm and the bar magnet is supported by a damper in a casing of a substantially square cross section.
  • a moving-coil type namely Ortofon-type stereo pickup has been proposed as an improvement of the aforementioned moving-magnet-type pickup.
  • this moving-coil-type pickup its center of vibration is definitely settled in the vicinity of the center of gravity of the armature to thereby eliminate one of the problems encountered in the moving-magnet-type pickup.
  • this moving-coil-type pickup has great mass which is a disadvantage.
  • This invention is to provide a novel stereo pickup which is free from the drawbacks experienced in the prior art, and in which a vibration system consists of a flat armature magnet magnetized in the direction of its thickness and a cantilever arm having a stylus and secured to the armature magnet, the center of vibration is settled in the vicinity of the center of gravity of the armature magnet and specific signal-generating means are provided in relation to the armature magnet, thereby reducing mechanical impedance relative to the stylus, minimizing crosstalk and distortion and facilitating the manu facture and replacement of the stylus.
  • FIG. I is an enlarged front view schematically illustrating one example of the stereo pickup produced according to this invention.
  • FIG. 2 is an enlarged cross-sectional view taken along the line ll-]I in FIG. 11;
  • FIGS. 3A to 3C are schematic diagrams for explaining the principle of this invention.
  • FIGS. IA and 4B are schematic diagrams for explaining the principle of generation of the stereo pickup of this invention.
  • FIGS. 5A and 5B are similar schematic diagrams for explaining the principle of generation of the stereo pickup of this invention.
  • FIG. 6 is a graph showing the relationship between the position of an armature and magnetic flux
  • FIGS. 7 and 8 are enlarged front views illustrating other examples of the stereo pickup of this invention.
  • FIG. 9 is an enlarged side view illustrating one example of a magnetic core usable in the stereo pickup of this invention.
  • FIG. I0 is a side view showing another example of the stereo pickup of this invention.
  • FIGS. MA to 11C are enlarged front views illustrating other examples of the armature usable in the pickup of this invention.
  • FIG. 12 is a perspective view schematically illustrating the pickup of this invention and one part of its attachment portion.
  • reference numeral 1 indicates a cantilever arm carrying at one end a stylus 2 and fixed at the other end to a flat armature 3 magnetized with north and south magnetic poles in the direction of its thickness.
  • the armature 3 is designed so that its center of gravity lies centrally of its center axis 2-2, and is shaped in such a configuration as to be symmetrical relative to two assumed straight lines X--X and Y- Y intersecting with the center axis Z.--Z and each other at right angles and relative to an assumed line O--O crossing the lines X---)( and YY at an angle of 45 thereto and intersecting with the center axis 2-2.
  • the armature 3 may be made in the form of a plate having a thickness of, for example, approximately 0.5 mm. and a square cross section measuring 2 mm. by 2 mm.
  • the cantilever arm I is mounted on the armature 3 at such a location that the center axis Z--Z of the armature 3 in the direction of its thickness is substantially in agreement with the axis of the cantilever arm 1 in its lengthwise direction, that the center G of gravity of the armature 3 lies at or near the center of vibration of a vibration system and that the line O-O runs in substantially the same direction as that of the stylus 2.
  • a pair of magnetic cores 4R and 41.. are disposed on the extensions of the lines X-X and YY symmetrically relative to the line O--O in opposing relation to the peripheral surface of the armature 3.
  • the magnetic cores 41R and 4L are positioned under the armature 3.
  • the magnetic cores 4R and 4L are, for example, the socalled E-shaped cores, as exemplified in FIG. 3, which have three platelike magnetic poles P P and P equally spaced from adjacent ones and interconnected at one end with one another.
  • the relative position of each of the magnetic cores 4R and 4L to the armature 3 is such that where the stylus 2 is not subjected to vibration, namely in its stationary condition, the central magnetic pole P lies on a line L-L passing the center of gravity of the armature 3, namely the center G of vibration of the vibration system and intersecting with the center axis Z-Z of the cantilever arm 1 at right angles thereto.
  • the central magnetic poles P have wound thereon windings SR and SL respectively.
  • Reference numeral 6 designates a fine core wire formed of, for example, a flexible metal material, which is positioned to pass through a cylindrical caulking member 102 inserted into an aperture 101i formed through the support 7 and is secured at one end to one end of the caulking member 1102 by means of, for example, an adhesive binder or the like.
  • the caulking member 102 is fixed by a setscrew I04 threadably engaged with a female screw 103 formed in the support 7. While, the other end of the core wire 6 is secured, by means of, for example, an adhesive hinder or the like, to a ring 106 fixed in the cantilever arm 1, passing through a central aperture of a damper 8 disposed between the armature 3 and the support 7 and through an O-ring I05.
  • the core wire 6 is secured at both ends to the cantilever arm I and the support 7 respectively, as previously described, shifting of the vibration system in the direction of the line 2-2 such as mentioned above is prevented.
  • the core wire 6 is flexible and fine, and hence it does not obstruct vibrations of all directions about the center of vibration of the vibration system except that of the direction of the line Z-Z.
  • FIGS. 4 and 5 a description will be given in connection with the manner in which the armature 3 is displ ed x thqxeqw an r ithoth yprtigaleqaizonent R, of the vector R, the armature 3 and the cantilever arm 1 are displaced as shown by dotted lines in FIG. 4A. If the displacement of the armature 3 from its full-line position to the cantilever side is defined to be minus displacement, upper corners 3C and 3D of the square-shaped armature 3 are displaced by +A and the lower comers 3A and 3B are displaced by ---A.
  • the vector R causes the comer 3A of the ar mature 3 to be displaced by .2A from its neutral position and the corner 3C to be displaced by +2A from its neutral position. While, the displacements of the corners 3B and 3D by the vertical and horizontal components Ry and R,., are opposite in direction, so that the displacements are cancelled and the corners 3B and 3D are not displaced.
  • the armature 3 With the vertical component Ry of the vector -R, the armature 3 is displaced as indicated by broken lines in FIG. 4A, namely the comers 3A and 3B of the armature 3 are displaced by +A and the corners 3C and 3D are displaced by -A. With the horizontal component R, of the vector -R, the armature 3 is, in turn, displaced as shown by broken lines in FIG. 5A. Namely, the displacements of the corners 3B and 3C are A, while those of the corners 3A and 30 are +A. Thus, the vector -R provides displacement of the corners 3A and 3C by +2A and 2A from their neutral positions respectively.
  • the corners 3A and 3C vibrate as described above.
  • the corners 3A and 3B are respectively disposed opposite to the magnetic cores 4R and 4L, as illustrated in FIGS. 1 and 3.
  • the corner 3A (or 3B) of the armature 3 assumes a position opposite to the central magnetic pole P of the magnetic core 4R (or 4L), as depicted in FIG. 3B.
  • a magnetic flux 1 starting from the armature 3, passing through the magnetic poles P, and P and returning to the armature 3 and a magnetic flux 1 starting from the armature 3, passing through the magnetic poles P, and P and returning to the armature 3 are equal in magnitude in the central magnetic pole P, but is opposite in direction. Therefore, no electromotive force is generated in the winding SR (or 5L) wound on the central magnetic pole P,.
  • the magnetic flux 1 reaches its greatest value. This introduces variations in the magnetic flux of the central magnetic pole P providing an electromotive force in the winding 5R.
  • the armature 3 Having returned to its initial position such as depicted in FIG. 3B, the armature 3stands opposite to the central magnetic pole P Under such conditions, the magnetic fluxes b, and 9, are equal in magnitude in the central magnetic pole P, and is opposite in direction, so that these magnetic fluxes are cancelled. As a result of this, no magnetic flux flows through the central magnetic pole P and a magnetic flux flows from the magnetic pole P, to the magnetic pole P, as a whole. Therefore, no electromotive force is generated in the winding 5R.
  • the magnetic core is not provided with the right-hand magnetic pole P and hence is composed of the left-hand magnetic pole P, and the central magnetic pole P, in the form of a U.
  • the magnetic flux 4 is at its maximum value when the corner 3A of the armature 3 lies at the center between the magnetic poles P, and P,, as depicted in FIG. 3A, and the magnetic flux I gradually decreases as the corner 3A moves from the central position.
  • FIGS. 3A, 3B and 3C illustrate the relationship between the magnitude of the magnetic flux I and the relative position of the corner 3A of the armature 3 to the magnetic core, in which the ordinate represents the magnitude of the magnetic flux I and the abscissa the position of the armature 3 relative to the magnetic core.
  • a curve 9 indicates the magnetic flux l points a, b and c on the abscissa indicating the positions of the armature 3 depicted in FIGS. 3A, 3B and 3C.
  • the magnetic flux D flowing from the central magnetic pole P, to the right-hand magnetic pole P will be discussed similarly in connection with a U-shaped magnetic core consisting of the magnetic poles P and P
  • the magnetic flux D reaches its maximum value when the armature 3 lies at the center between the magnetic poles P and P and the magnetic flux I gradually decreases as the armature 3 leaves the central position.
  • the characteristics of the magnetic flux b is as indicated by a curve 10 in FIG. 6.
  • a magnetic flux D flowing through the central magnetic pole P, having wound thereon the winding 5R(5L) is composed of the magnetic fluxes Q, and D which is indicated by a full-line curve 11 in FIG. 6. That is, the magnetic flux flowing through the central magnetic pole P is zero when the armature 3 assumes a position opposite to the central magnetic pole P, as shown in FIG. 3B.
  • the magnetic flux I flowing through the central magnetic pole P varies linearly about the point b close the points a and c where the magnetic fluxes b, and D, reach their maximum values. Consequently, the magnetic flux I is in direct proportion to the displacement of the armature 3 to ensure that a distortionless output voltage is obtained from the winding wound on the central magnetic pole P, through which the magnetic flux I flows.
  • the pickup of this invention exhibits excellent performance as a pickup for use with stereo records.
  • the use of flat armature 3 and positioning the vibration center of the vibration system on or above the center G of gravity of the armature 3 reduces the mechanical impedance from the stylus 2 and eliminate distortion and crosstalk in the reproduced sound.
  • the flat armature is magnetized in the direction of its thickness, the magnetization can readily be effected to enhance efiiciency of manufacturing operations.
  • the magnetic cores 4R and 4L are disposed opposite to the underside of the armature 3 in the foregoing example, it is also possible to arrange the magnetic cores 4R and 4L above the armature 3 on the lines X-)( and Y-Y in the same relation as that described above, as shown in FIG. 7, or to dispose four magnetic cores 4R, 41R and dL, 4L opposite to all the corners of the armature 3 respectively in the same relation as the above-described one.
  • windings SR and SR wound on central magnetic poles P of the magnetic cores 4R and lR'are connected in series to each other, and windings 5L and 51. wound on the magnetic cores ll. and All. are similarly connected in series to each other. Further, these windings are connected together in such a manner that their outputs are added together to provide a large output.
  • the foregoing example employs the platelike E-shaped magnetic core 4 having the magnetic poles P P and P but it will be apparent that the top end portions of the magnetic poles P, and P can be bent inwardly as shown in FIG. 9.
  • the E-shaped magnetic core may also be formed in the shape of a cylinder with the poles P and P forming the outer walls of a cylinder and with a center pole 1P extending upwardly at the center of the cylinder.
  • winding is wound on the central magnetic pole P of the magnetic core d for leading out an electrical signal.
  • windings 15R and llSL and 15R, 151. are wound on the magnetic poles P, and P of the magnetic core ll as illustrated in FIG. and in this case the windings R and 115R are connected in series to each other and the windings ISL and llSL' are similarly connected in series to each other.
  • the turning directions of the windings and their connections are selected so that when the armature 3 stands opposite to the central magnetic pole P, outputs induced in the windings 15R and 15R, 15!. and 15L by the magnetic fluxes l and D produced in the magnetic poles I, and P may be cancelled by each other.
  • the armature 3 is mounted on the cantilever arm 1 in such a manner that the lines X-X and Y-Y respectively form an angle of approximately 45 with the plane including the extension of the stylus 2 and the axial direction of the cantilever arm 1. It is preferred in practice to position the armature 3 as close to the magnetic cores 4 R and 41.. as possible.
  • P10. 12 there is illustrated one example of a support S for supporting the pickup of this invention.
  • a support rod R is fixed on the support 7 and a hole H for supporting the rod R fitted therein is formed in the support 5. Insertion of the rod R into the hole H leads to supporting of the support 7 and consequently the stereo pickup on the support S.
  • a groove conforming to the configuration of the support 7 is provided in the support S.
  • a plurality of cylindrical members 1 1 can be mounted about the cantilever arm ll, as shown in FIG. 2 by dotted line in a manner to gradually increase its diameter as the fixed portion of the cantilever arm l to the armature 3 is approached. This prevents vibration of the cantilever arm I itself due to its slenderness and hence prevents generation of noise.
  • a moving-magnet-type stereo pickup comprising a cantilever arm carrying atone end a stylus, an armature attached to the other end of said cantilever arm, said armature comprising a flat permanent magnet which is magnetized in the direction of its thickness and longitudinally of the arm, said cantilever arm fixed to said armature so that the longitudinal direction of said cantilever arm crosses the plane of said armature at right angles, means for supporting the armature in such a manner that the center of vibration of the vibration system including said stylus, cantilever arm and armature lie substantially at the center of gravity of said armature, E-shaped magnetic pathforming means comprising core means for forming a plurality of magnetic paths in cooperation with said armature, said E- shaped magnetic core means mounted adjacent said armature and disposed relative to said armature: so that the legs of said E-shaped magnetic core means are arranged one after another along an axis parallel to the north and south poles of said armature, and the center leg of said E-shaped magnetic core means is
  • a moving-magnet-type stereo pickup comprising a cantilever arm carrying at one end a stylus, an armature attached to the other end of said cantilever arm; said armature comprising a flat permanent magnet which is magnetized in the direction of its thickness and longitudinally of the arm, said cantilever arm fixed to said armature so that the longitudinal direction of said cantilever arm crosses the plane of said armature at right angles, means for supporting the armature in such a manner that the center of vibration of the vibration system including said stylus, cantilever arm and armature lie substantially at the center of gravity of said armature, E-shaped magnetic pathforming means comprising core means for forming a plurality of magnetic paths in cooperation with said armature, said E- shaped magnetic core means mounted adjacent said armature and disposed relative to said armature so that the legs of said E-shaped magnetic core means are arranged one after another along an axis parallel to the north and south poles of said armature, and the center leg of said E-shaped magnetic core means is adjacent
  • a moving-magnet-type stereo pickup as claimed in claim 2 in which said windings are wound on the center leg of said E- shaped magnetic core means.
  • a moving-magnet-type stereo pickup as claimed in claim 2 in which said windings are wound on both outside legs of said E-shaped magnetic core means.
  • a moving-magnet-type stereo pickup as claimed in claim 2 comprising a first support means for supporting said vibration system, a pin attached to said first support means, and a second support means formed with a hole into which said pin is inserted to support said stereo pickup.

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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)
  • Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)
US699936A 1968-01-23 1968-01-23 Moving magnet type stereo pickup Expired - Lifetime US3627931A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US69993668A 1968-01-23 1968-01-23

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US699936A Expired - Lifetime US3627931A (en) 1968-01-23 1968-01-23 Moving magnet type stereo pickup

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US (1) US3627931A (enrdf_load_stackoverflow)
DE (1) DE1772683B2 (enrdf_load_stackoverflow)
GB (1) GB1233791A (enrdf_load_stackoverflow)
NL (1) NL149019B (enrdf_load_stackoverflow)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
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
US4004108A (en) * 1974-06-11 1977-01-18 Pioneer Electronic Corporation Armature for sound pick-up cartridge
US4103116A (en) * 1974-12-05 1978-07-25 Nippon Gakki Seizo Kabushiki Kaisha Pickup cartridge with moving magnet armature
US4136884A (en) * 1976-03-18 1979-01-30 Nippon Gakki Seizo Kabushiki Kaisha Electromagnet type pickup device
US4547874A (en) * 1981-09-10 1985-10-15 Sony Corporation Moving coil type cartridge mounted on cantilever within central opening of ring magnet
US4597071A (en) * 1982-05-31 1986-06-24 Nippon Gakki Seizo Kabushiki Kaisha Pickup cartridge of moving magnet type
US4630253A (en) * 1977-12-23 1986-12-16 Alps Electric Co., Ltd. Electromagnetic pickup cartridge having elongate core elements

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2093540A (en) * 1931-12-14 1937-09-21 Emi Ltd Sound-transmission, sound-recording, and sound-reproducing system
US2398666A (en) * 1942-04-27 1946-04-16 Taylor Taylor & Hobson Ltd Apparatus for measuring or indicating the roughness or undulations of a surface
US2415681A (en) * 1944-09-07 1947-02-11 Gen Electric Electric pickup
US2553715A (en) * 1947-08-12 1951-05-22 George L Miller Segmented magnetic armature for phonograph pickups
US2829210A (en) * 1951-08-15 1958-04-01 Donald J Baker Magnetic pickup
US3005060A (en) * 1958-03-03 1961-10-17 Weathers Paul Signal transducing systems
GB1000035A (en) * 1960-10-22 1965-08-04 Fonofilm Ind As A stereophonic electrodynamic pickup
CA718099A (en) * 1965-09-14 N.V. Philips Gloeilampenfabrieken Converting device for recording or scanning groove-like record tracks
US3294405A (en) * 1963-12-11 1966-12-27 Audio Dynamics Corp Phonograph pick-up
US3299219A (en) * 1958-11-10 1967-01-17 Bang & Olufsen Produktionssels Stereophonic transducer cartridge

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA718099A (en) * 1965-09-14 N.V. Philips Gloeilampenfabrieken Converting device for recording or scanning groove-like record tracks
US2093540A (en) * 1931-12-14 1937-09-21 Emi Ltd Sound-transmission, sound-recording, and sound-reproducing system
US2398666A (en) * 1942-04-27 1946-04-16 Taylor Taylor & Hobson Ltd Apparatus for measuring or indicating the roughness or undulations of a surface
US2415681A (en) * 1944-09-07 1947-02-11 Gen Electric Electric pickup
US2553715A (en) * 1947-08-12 1951-05-22 George L Miller Segmented magnetic armature for phonograph pickups
US2829210A (en) * 1951-08-15 1958-04-01 Donald J Baker Magnetic pickup
US3005060A (en) * 1958-03-03 1961-10-17 Weathers Paul Signal transducing systems
US3299219A (en) * 1958-11-10 1967-01-17 Bang & Olufsen Produktionssels Stereophonic transducer cartridge
GB1000035A (en) * 1960-10-22 1965-08-04 Fonofilm Ind As A stereophonic electrodynamic pickup
US3294405A (en) * 1963-12-11 1966-12-27 Audio Dynamics Corp Phonograph pick-up

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
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
US4004108A (en) * 1974-06-11 1977-01-18 Pioneer Electronic Corporation Armature for sound pick-up cartridge
US4103116A (en) * 1974-12-05 1978-07-25 Nippon Gakki Seizo Kabushiki Kaisha Pickup cartridge with moving magnet armature
US4136884A (en) * 1976-03-18 1979-01-30 Nippon Gakki Seizo Kabushiki Kaisha Electromagnet type pickup device
US4630253A (en) * 1977-12-23 1986-12-16 Alps Electric Co., Ltd. Electromagnetic pickup cartridge having elongate core elements
US4547874A (en) * 1981-09-10 1985-10-15 Sony Corporation Moving coil type cartridge mounted on cantilever within central opening of ring magnet
US4597071A (en) * 1982-05-31 1986-06-24 Nippon Gakki Seizo Kabushiki Kaisha Pickup cartridge of moving magnet type

Also Published As

Publication number Publication date
DE1772683C3 (enrdf_load_stackoverflow) 1974-09-26
DE1772683B2 (de) 1974-02-21
NL6808674A (enrdf_load_stackoverflow) 1969-12-23
DE1772683A1 (de) 1972-02-24
NL149019B (nl) 1976-03-15
GB1233791A (enrdf_load_stackoverflow) 1971-05-26

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