US3899827A - Method of manufacturing pole piece assembly for electromagnetic type pickup - Google Patents

Method of manufacturing pole piece assembly for electromagnetic type pickup Download PDF

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Publication number
US3899827A
US3899827A US468575A US46857574A US3899827A US 3899827 A US3899827 A US 3899827A US 468575 A US468575 A US 468575A US 46857574 A US46857574 A US 46857574A US 3899827 A US3899827 A US 3899827A
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US
United States
Prior art keywords
arms
portions
pole piece
joint portion
fixing member
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
US468575A
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English (en)
Inventor
Norihiko Takami
Osamu Hattori
Manabu Wakabayashi
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Hitachi Ltd
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Hitachi Ltd
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Publication date
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Publication of US3899827A publication Critical patent/US3899827A/en
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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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/49—Method of mechanical manufacture
    • Y10T29/49002—Electrical device making
    • Y10T29/4902—Electromagnet, transformer or inductor
    • Y10T29/49021—Magnetic recording reproducing transducer [e.g., tape head, core, etc.]
    • Y10T29/49032—Fabricating head structure or component thereof
    • Y10T29/49048—Machining magnetic material [e.g., grinding, etching, polishing]
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/49—Method of mechanical manufacture
    • Y10T29/49002—Electrical device making
    • Y10T29/4902—Electromagnet, transformer or inductor
    • Y10T29/49021—Magnetic recording reproducing transducer [e.g., tape head, core, etc.]
    • Y10T29/49032—Fabricating head structure or component thereof
    • Y10T29/49055—Fabricating head structure or component thereof with bond/laminating preformed parts, at least two magnetic
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/49—Method of mechanical manufacture
    • Y10T29/49799—Providing transitory integral holding or handling portion

Definitions

  • a pole piece unit including a set of pole pieces integrally interconnected with each other is first punched from a sheet of magnetic material and then the punched pole pieces are bent into a predetermined shape.
  • the pole piece unit having the predetermined shape is next fixed to a fixing member of nonmagnetic material, and then cut apart at the interconnecting portion thereof into magnetically separated pole pieces constituting the pole piece assembly.
  • the present invention relates to a method of manufacturing a pickup assembly used for reproducing sound recorded on a disk record and, more particularly, to a method of manufacturing a pole piece assem bly forming a magnetic circuit in an electromagnetictype pickup.
  • FIG. 1 is a schematic diagram illustrating the structure of a conventional electromagnetic-type pickup used for reproducing a stereo sound.
  • Pole pieces are denoted by numerals l to 4, and a pair of pole pieces 1 and 3 and another pair of pole pieces 2 and 4 are connected magnetically by yokes 9 and 10, respectively.
  • Coils 7a to 7d are mounted on a magnetic circuit consisting of the pole pieces 1 to 4 and the yokes 9 and 10.
  • the vibration of a stylus 6 transfers through a cantilever to an armature which might be made of a permanent magnet.
  • the vibration of the armature 5 is then detected by the coils 7a to 7d, thereby obtaining the electrical signal corresponding to the vi bration of the armature as originated from the stylus.
  • each of four pole pieces is punched from a thin plate of a high-permeability, and then the punched pole pieces are bent into the shape as shown in FIG. 2.
  • the shaped pole pieces are denoted by numerals 1 to 4. These four pole pieces may theoretically be the same in shape, but, in fact, these pole pieces often take different shapes for reasons of practical operation of the pickup.
  • the so constructed pole pieces 1 to 4 are prepared with an arrangement as shown in FIG. 2, and are inserted into the slots of a holder 11 by the aid of a jig 12. An assembly after the insertion is illustrated in FIG. 3.
  • the pole pieces 1 to 4 and the holder 11 are mutually secured.
  • the connection may be made with an adhesive or by a plastic filling.
  • the jig 12 is removed, the coils 7a to 7d are mounted, and the respective pairs of the pole pieces are magnetically connected by yokes 9 and 10.
  • the four pole pieces take different shapes, respectively. Thus, different bending processes are required for each pole piece, which results in that the number of manufacturing steps increases and parts management is complicated.
  • the four pole pieces used for a single pickup are punched from different thin plates. Thus, there can occur a different permeability among those pole pieces. This difference of permeability causes crosstalk and unbalance between channels.
  • An object of the present invention is to provide a method of manufacturing a pole piece assembly for an electromagnetic-type pickup by which a magnetic circuit of the electromagnetic-type pickup is readily formed.
  • Another object of the present invention is to provide a method of manufacturing a pole piece assembly for an electromagnetic-type pickup which provides a magnetic circuit with little disparity in the performance thereof.
  • Another object of the present invention is to provide a method of manufacturing a pole piece assembly for an electromagnetic-type pickup, wherein management of the parts during the manufacturing process is easy.
  • a method of manufacturing a pole piece assembly for an electromagnetic-type pickup comprising the following steps. That is, a pole piece unit including four pole pieces is punched from a thin plate of a high permeability. The punched pole piece unit is bent into a desired shape and then fixed to a holder. Finally, a part of the pole piece unit, together with a part of the holder, is cut off to provide four independent pole pieces.
  • FIG. 1 is a perspective view of an example of conventional pickups.
  • FIG. 2 is a view for explaining a conventional method of manufacturing a pole piece assembly, in which a set of pole pieces and a holder for holding the pole pieces are illustrated.
  • FIG. 3 is a perspective view of the pole piece assembly constructed by the pole pieces and the holder shown in FIG. 2.
  • FIGS. 4A to 4E are diagramatic illustrations for explaining the manufacturing process according to an embodiment of the present invention.
  • FIGS. 5A to 5D are diagramatic illustrations for explaining the manufacturing process according to another embodiment of the present invention.
  • FIGS. 4A to 4E illustrate the manufacturing process of a pole piece assembly for a electromagnetic-type pickup according to an embodiment of the present invention.
  • a cross-shaped pole piece unit 13 is punched from a thin plate of a high-permeability as shown in FIG. 4A.
  • the crossshaped pole piece unit 13 has a hole 14 within the intersection or joint portion thereof and four radially extending arms which are later separated to form magnetic pole pieces 31 to 34 are connected with each other at the intersection.
  • the cross-shaped pole piece unit 13 is then bent into a shape such as shown FIG. 4B in such a manner that first portions of the arms, starting from the joint portion, extend parallel to each other, forming a quadrangular cup, second portions of the arms extend gradually outward from the first portions axially and radially to form a flared area, and third portions of the arms extend from the second portions in parallel to each other in the axial direction.
  • the pole piece unit so shaped will be referred to as a bent pole piece unit and designated by numeral 16.
  • the hole 14 may be used as a guide in the bending step.
  • the bent pole piece unit is subject to a magnetic annealing in accordance with the material thereof.
  • the bent pole piece unit 16 is inserted, by the aid ofajig 17, into a hollow of a fixing block 18 of non-magnetic material, so that the bent pole piece unit 16 is so fixed as to arrange the pole pieces 31 to 34 in position.
  • the hollow of the fixing block 18 has a square cross section with which the jig 17 of a square cross sectional solid bar can just engage and which is provided with, on each side of the square, a groove into which the pole piece of the bent pole piece unit is just inserted, and such hollow as above is formed at the rear end side (at the right hand side in FIG. 4D) by a hollow having a shape of a frustum of a right pyramid suitable for receiving the parts of the pole pieces expanding outwardly.
  • the fixing of the bent pole piece unit 16 to the fixing block 18 is made with an adhesive or by casting plastic onto the bent pole piece unit within the block 18.
  • FIG. 4E is a front view of the fixing block fixedly provided therein with the pole pieces 31 to 34 obtained after the cutting off process.
  • the reference numeral 20 designates a space defined by the respective pole pieces 31 to 34 which was used to accept the jig 17 when the bent pole piece unit 16 is inserted into the fixing block 18, and which will be used to accommodate an armature such as a magnet when the pickup is assembled completely.
  • FIGS. 5A to 5D illustrate the manufacturing process of a pole piece assembly for an electromagnetic pickup according to another embodiment of the present invention.
  • a pole piece unit 21 having a shape as shown in FIG. 5A is stamped out from a thin plate of a high permeability.
  • the pole piece unit 21 has a hole 22 at the central portion whose surrounding portion (denoted by a broken line 23) interconnects four pole pieces.
  • the pole piece unit 21 is bent into a shape as shown in FIG. 5B.
  • the bent pole piece unit so shaped is subjected to a magnetic annealing in accordance with the material thereof.
  • the bent pole piece unit 24 is then secured at its front portion to a fixing block 25 of non-magnetic material, as shown in FIG. 5C.
  • plastic is cast onto the front portion of the bent pole piece unit 24 and is solidified.
  • the fixing block 25 is provided with a hole 26 at the portion corresponding to the hole 22 of the bent pole piece unit 24.
  • the bent pole piece unit 24 is separated into individual pole pieces by cutting the portion denoted by the broken .4 line 23 shown in FIGS. 5A and 5B with a drill 27 guided along the hole 26. That is, the bent pole piece unit 24 is magnetically separated into four pole pieces 41 to 44. This cutting operation may also be carried out by a reaming or an internal grinding.
  • the subsequent steps to be taken after the four pole pieces are secured to the fixing block i.e. steps of mounting coils and providing yokes, are performed in a similar manner to a conventional method.
  • a single kind of a punch die is sufficient for punching a thin plate of a high-permeability.
  • a set of four pole pieces used for a single pickup is punched from the same sheet of a thin plate of a high-permeability. Thus, no disparity in performance among the pole pieces will occur.
  • Pole pieces are integrally interconnected before they are fixed to a fixing block. Handling and parts management with respect to those pole pieces is easy. Additionally, the relative positioning of the respective pole pieces is made with high accuracy, which results in little amount of disparity in finished goods.
  • pole piece unit stamping a pole piece unit from a thin plate of magnetic material, said pole piece unit having four arms extending outwardly from a joint portion with opposite ones of said arms from said joint portion being joined symmetrically with said joint portion,
  • said bent pole piece unit thereafter inserting said bent pole piece unit into a fixing member of non-magnetic material, said fixing member having a hollow recess for receiving said joint portion and the bent arms of said pole piece unit thereinto,
  • step of bending said four arms includes bending first portions of said arms from said joint portion to extend parallel to each other in the axial direction, thereby forming a quadrangular-shaped cup, bending second portions of said arms from said first portions gradually outwardly from said first portions, both axially and radially, to form a flared area.
  • said hollow recess of said fixing member includes a first section having a square crosssection with a groove on each side wall into which said first portions of said arms are inserted, and further including a second section having a flared cross-section for receiving said flared area of said second portions of said arms, such that said step of severing forms said two pairs of spaced pole pieces from said axially extending parallel first portions of said opposing ones of said arms.
  • step of severing includes cutting off a portion of said fixing member where said joint portion is provided.
  • said step of bending provides first portions of said opposing ones of said arms coplanar with said joint portion, and bends second portions of said opposing ones of said arms from said first portions into a parallel axially extending direction, said joint portion being provided with a hole at the center thereof, and wherein said hollow recess of said fixing member includes a section receiving said joint portion with said coplanar first portions of said opposing ones of said arms therein, while said second portions of said opposing ones of said arms extend outwardly from said fixing member, said fixing member including a second hole being aligned with said hole in said joint portion, such that said step of severing is effected by enlarging said holes, thereby removing said joint portion so that said two pairs of spaced pole pieces are formed from opposing ends of said coplanar first portions of said arms.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Manufacture Of Motors, Generators (AREA)
US468575A 1973-05-11 1974-05-09 Method of manufacturing pole piece assembly for electromagnetic type pickup Expired - Lifetime US3899827A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP48051738A JPS5121769B2 (enrdf_load_stackoverflow) 1973-05-11 1973-05-11

Publications (1)

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US3899827A true US3899827A (en) 1975-08-19

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JP (1) JPS5121769B2 (enrdf_load_stackoverflow)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4161631A (en) * 1974-12-13 1979-07-17 Nippon Columbia Kabushikikaisha Pickup cartridge

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5824556Y2 (ja) * 1977-09-16 1983-05-26 パイオニア株式会社 ピツクアツプカ−トリツジ
JPS5661895A (en) * 1979-10-25 1981-05-27 Matsushita Electric Ind Co Ltd Electromagnetic type pickup cartridge
JP2010502798A (ja) * 2006-09-07 2010-01-28 チバ ホールディング インコーポレーテッド 表面変性剤としてのペルフルオロアルキル基で置換されたフェノール誘導体

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1631461A (en) * 1924-12-01 1927-06-07 Gen Phonograph Mfg Co Commutator and method of making same
US3092692A (en) * 1959-07-13 1963-06-04 Zenith Radio Corp Magnetic transcriber
US3163720A (en) * 1959-02-05 1964-12-29 Webcor Inc Magnetic head
US3229355A (en) * 1962-01-02 1966-01-18 Ibm Method of making a magnetic transducer head
US3383474A (en) * 1963-12-23 1968-05-14 Electroacustic Gmbh Electromagnetic pickup with exchangeable stylus assembly for phonograph records
US3828426A (en) * 1972-12-26 1974-08-13 Phelon Co Inc Method of fabricating magnetomotive devices

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1631461A (en) * 1924-12-01 1927-06-07 Gen Phonograph Mfg Co Commutator and method of making same
US3163720A (en) * 1959-02-05 1964-12-29 Webcor Inc Magnetic head
US3092692A (en) * 1959-07-13 1963-06-04 Zenith Radio Corp Magnetic transcriber
US3229355A (en) * 1962-01-02 1966-01-18 Ibm Method of making a magnetic transducer head
US3383474A (en) * 1963-12-23 1968-05-14 Electroacustic Gmbh Electromagnetic pickup with exchangeable stylus assembly for phonograph records
US3828426A (en) * 1972-12-26 1974-08-13 Phelon Co Inc Method of fabricating magnetomotive devices

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4161631A (en) * 1974-12-13 1979-07-17 Nippon Columbia Kabushikikaisha Pickup cartridge

Also Published As

Publication number Publication date
JPS503303A (enrdf_load_stackoverflow) 1975-01-14
JPS5121769B2 (enrdf_load_stackoverflow) 1976-07-05

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