US3466405A - Permanent magnet basket assembly for a speaker - Google Patents

Permanent magnet basket assembly for a speaker Download PDF

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Publication number
US3466405A
US3466405A US515322A US3466405DA US3466405A US 3466405 A US3466405 A US 3466405A US 515322 A US515322 A US 515322A US 3466405D A US3466405D A US 3466405DA US 3466405 A US3466405 A US 3466405A
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United States
Prior art keywords
speaker
return path
permanent magnet
basket
magnet
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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
US515322A
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English (en)
Inventor
Rollin J Parker
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General Electric Co
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General Electric Co
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Publication date
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Publication of US3466405A publication Critical patent/US3466405A/en
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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
    • H04R9/00—Transducers of moving-coil, moving-strip, or moving-wire type
    • H04R9/06—Loudspeakers
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R9/00—Transducers of moving-coil, moving-strip, or moving-wire type
    • H04R9/02—Details
    • H04R9/025—Magnetic circuit

Definitions

  • Typical permanent magnet speakers contain a basket to which are attached a permanent magnet, a pole piece and return path elements, the latter making up the yoke structure of the magnetic circuit.
  • the return path elements in a conventional speaker will comprise one or more components which together form a cup-shaped structure surrounding the usually cylindrical speaker magnet.
  • the return path elements must have sufficient cross-sectional area so that the flux density does not exceed the saturation point of the metal.
  • the return path elements are therefore generally of more substantial gauge than the metal which makes up the speaker basket. This factor plus the shape of the path of magnetic flux in the return path circuit has resulted in the two components-basket and return pathbeing hitherto comprised of at least two separate units.
  • the present invention has as its principal object a simplified permanent magnet-basket assembly for a speaker made up of an integral return path-basket unit. It is an additional object to provide such an assembly which permits greater speaker magnet efficiency and performance. A still further object of the invention is to provide a process for manufacturing permanent magnet-speaker assemblies more simply and economically than has heretofore been possible by manufacturing the speaker baskets and return path element as an integral unit.
  • the speaker magnet assembly of the present invention comprises a basket having a central aperture therein, a return path element depending from said central aperture which is formed from and integral with said basket, and a permanent magnet disposed within said return path element.
  • the magnetic circuit of the speaker assembly is made up only of the permanent magnet itself and the return path element formed from the basket. No pole 3,466,405 Patented Sept. 9, 1969 ice piece or bottom return path elements are necessary.
  • the return path element of the speaker assembly is tubular, i.e., a hollow tube open at both the bottom and the top.
  • the speaker magnet assemblies of the invention are manufactured by shaping that portion of the basket, from which one or more of the apertures in the basket are formed, into the return path element.
  • a permanent magnet is then fitted within the thus shaped return path element such that the magnet contacts the return path element at a lower axial extremity of the return path element and is separated from the return path element at an upward axial extremity of the return path element, the separation serving to form an air gap adapted to receive the coil of the speaker.
  • FIGURES 1 through 8 illustrate schematically the successive steps of manufacture of a speaker magnet assembly of the invention.
  • FIGURES 9 through 13 illustrate schematically the successive steps of manufacture of a second embodiment of a speaker magnet assembly of the invention.
  • a sheet 1 of relatively light-gauge, low-carbon steel is first drawn to form a central depression 2, as shown in FIG. 1.
  • This central depression is then elongated as shown in FIG. 2.
  • Such elongation also acts to thin out somewhat the gauge of the steel forming the depression.
  • the depression 2 is now reverse-drawn as shown in FIG. 3, to approximately double the gauge of the walls of the depression, at the same time, of course, reducing the length of the depression approximately in half.
  • the depression 2 is now pierced as shown in FIG. 4 to form an opening 3.
  • the reverse-drawn and pierced depression 2 must now be accurately sized and crimped at a die station to form the precise shape and tolerances required for optimum performance in a speaker circuit.
  • the depression is now shaped to form a tubular return path element 4.
  • tube 4 is crimped at a lower axial extremity thereof to form an annular collar 5 of reduced diameter.
  • the inner surface of the collar 5 is flat to form continuous and close contact with the speaker magnet between the inner surface of the collar and the lower axial extremity of the magnet.
  • the remainder of the tube is also accurately sized in order to form at 6 the precise air gap distance required upon insertion of the permanent magnet.
  • a typical sheet, such as 1 in FIG. 1, is about 0.040" gauge in thickness.
  • the thickness of the reverse-drawn tube in FIG. 3 will be approximately 0.070" gauge, or somewhat less than twice the original gauge, the difference resulting from the elongation that has occurred in the tube.
  • the basket is then shaped and cut as illustrated in cross section in FIGS. 6 and 7 and in plan in FIG. 8.
  • four Windows 8 are blanked out.
  • a cylindrical permanent magnet 9 is press-fit within integral return path element 4 as shown in FIGS. 7 and 8.
  • Four holes 10 at each corner of the basket are also pierced to provide apertures for attachment of the speaker to a radio receiver housing or other amplification .device.
  • the complete permanent magnet circuit and basket thus consist of but two elements-the integral basketreturn path element and a permanent magnet.
  • FIGS. 9 through 13 The process of manufacturing a speaker magnet assembly in accordance with a second embodiment of the invention is illustrated in FIGS. 9 through 13.
  • a sheet of steel 15 is drawn as illustrated in FIG. 9 to form a depression 16 and is then pierced to form an opening 17.
  • the pierced depression is partially reverse-drawn as shown in FIG. to form an annular collar 18 of reduced diameter.
  • the sheet is now shaped and cut as illustrated in FIGS. 11 and 12 to form the conical portion of the speaker basket. This is accomplished by first shaping the sheet 15 in conical form to form the basket 19 and then piercing four holes, two of which are in the form of windows 20 and 20', as illustrated in FIG. 11. The remaining two holes 21 and 21' are pierced so as to leave T-shaped tabs 22 and 22 integral with the basket. Each of the T-shaped tabs is then bent downward and away from the basket and shaped into the form of a half of a hollow cylinder or tube, as illustrated in FIG. 12. Upon further bending down and back, tabs 22 and 22 form intimate contact with depression 16.
  • a permanent magnet may be press-fit within the shaped return path element to form the speaker magnet assembly as shown in connection with the first embodiment.
  • the invention is, to a considerable extent, made possible by the utilization of a permanent magnet oriented in a manner set forth in my above-referred-to co-pending application S.N. 515,401.
  • the permanent magnet is oriented along an axially disposed curve. Such orientation is shown at 11 in FIG. 7 of the drawing of the present application.
  • This permits a number of significant advantages in the construction of the permanent magnet speaker. Measurements indicate that 90% of the total magnetomotive force is made available at the air gap as opposed to 65-75% in conventional magnet structures. Additionally, virtually 100% of the total magnetic flux may by made to enter the general region of the voice coil vs. a loss of as much as 20% of such flux to regions outside the voice coil regions in conventional magnet structures.
  • FIG. 7 Aother advantage of the invention is also illustrated in FIG. 7.
  • the width of the air gap 12 is the same as the width of the throat 13 formed between the remainder of the return path element and the lateral sides of the permanent magnet. While this structure is not unknown in the speaker art, it has almost always been avoided because greatest efficiency in speaker structures is obtained by maintaining a large degree of separation between the axialfiow of magnetic flux in the magnet and return axial flow in the lateral portion of the return path. This discourages radiation of flux from the sides of the magnet to the return path element at areas other than the air gap. In conventional speaker assemblies the flux flows in an axial direction through the permanent magnet-any radial flow of flux other than at the extremities of the magnet must be discouraged. In the speaker magnet construction shown in FIG.
  • a permanent magnet-basket assembly for a speaker comprising:
  • a permanent magnet-basket assembly for a speaker comprising:
  • said return path element surrounding said permanent magnet laterally only and open at the bottom thereof, the magnetic circuit of said assembly consisting essentially only of said permanent magnet and integral return path element, the lower axial extremity of the return path element contacting the speaker magnet, the upper axial extremity of the return path element being spaced from the speaker magnet to form an air gap, and the intermediate portions of the return path element being spaced from the speaker magnet by a distance substantially equal to the width of the air gap.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Audible-Bandwidth Dynamoelectric Transducers Other Than Pickups (AREA)
  • Diaphragms For Electromechanical Transducers (AREA)
US515322A 1965-12-21 1965-12-21 Permanent magnet basket assembly for a speaker Expired - Lifetime US3466405A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US51532265A 1965-12-21 1965-12-21

Publications (1)

Publication Number Publication Date
US3466405A true US3466405A (en) 1969-09-09

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ID=24050877

Family Applications (1)

Application Number Title Priority Date Filing Date
US515322A Expired - Lifetime US3466405A (en) 1965-12-21 1965-12-21 Permanent magnet basket assembly for a speaker

Country Status (6)

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US (1) US3466405A (es)
BE (1) BE691587A (es)
DE (1) DE1300146B (es)
FR (1) FR1505287A (es)
GB (1) GB1164306A (es)
NL (1) NL6616887A (es)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104028639A (zh) * 2014-06-24 2014-09-10 梧州恒声电子科技有限公司 一种采用超薄卷料制造的扬声器盆架的加工工艺

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2260063A (en) * 1938-02-28 1941-10-21 Operadio Mfg Company Loud-speaker
US2320402A (en) * 1940-09-30 1943-06-01 Rca Corp Loud-speaker
US3133162A (en) * 1961-09-06 1964-05-12 Aldo L Coen Loud speaker structure

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH168489A (de) * 1932-01-30 1934-04-15 Rca Corp Verfahren zum Zusammenbau von Antriebssystemen für elektrodynamische Lautsprecher, Mikrophone oder dergleichen und nach diesem Verfahren hergestelltes Antriebssystem.
DE1002394B (de) * 1954-12-01 1957-02-14 Siemens Ag Lautsprecher, insbesondere Hochtonlautsprecher

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2260063A (en) * 1938-02-28 1941-10-21 Operadio Mfg Company Loud-speaker
US2320402A (en) * 1940-09-30 1943-06-01 Rca Corp Loud-speaker
US3133162A (en) * 1961-09-06 1964-05-12 Aldo L Coen Loud speaker structure

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104028639A (zh) * 2014-06-24 2014-09-10 梧州恒声电子科技有限公司 一种采用超薄卷料制造的扬声器盆架的加工工艺
CN104028639B (zh) * 2014-06-24 2016-04-27 梧州恒声电子科技有限公司 一种采用超薄卷料制造的扬声器盆架的加工工艺

Also Published As

Publication number Publication date
NL6616887A (es) 1967-06-22
DE1300146B (de) 1970-02-05
FR1505287A (es) 1968-02-21
GB1164306A (en) 1969-09-17
BE691587A (es) 1967-06-21

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