US2270320A - Magnetic head for electromagnetic sound recording and reproducing apparatus - Google Patents

Magnetic head for electromagnetic sound recording and reproducing apparatus Download PDF

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Publication number
US2270320A
US2270320A US274399A US27439939A US2270320A US 2270320 A US2270320 A US 2270320A US 274399 A US274399 A US 274399A US 27439939 A US27439939 A US 27439939A US 2270320 A US2270320 A US 2270320A
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United States
Prior art keywords
hole
magnetizable
recording
reproducing apparatus
sound recording
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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
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US274399A
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English (en)
Inventor
Liguori Giovanni
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Individual
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Individual
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Publication date
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Publication of US2270320A publication Critical patent/US2270320A/en
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    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/127—Structure or manufacture of heads, e.g. inductive

Definitions

  • This invention relates to an electromagnetic sound recording and reproducing device, in which a magnetizable elongated element, such as a wire or ribbon of steel or other suitable-magnetizable material is unwound from one reel and wound upon another reel.
  • the member on its way from one to the other reel passes ⁇ a so-called magnet head, which is capable either to magnetize the passing member in the rhythm of sound waves' received, and thus to record sound upon the member, or to be influenced by a member on which sound has previously been recorded magnetically in a similar or other way.
  • Magnet heads used in those devices comprise two magnetizable soft iron cores anda coil around each core, each constituting an electromagnet. These electromagnets are slideably held in a 'support on opposite sides of the path of the magnetizable member, and the axes are aligned. The -juxtaposed ends of the cores contact the magnetizable member and in order to maintain a permanent contact, the individual electromagnets are pressed by a spring against the member. ⁇ 1
  • Fig. 1 shows in elevation a magnet head.
  • the magnet head is mounted in the recording and reproducing apparatus of an otherwise Y known structure by meansy of a hollow tube or member 9 to which a vvertical base 8 is secured.
  • a support or block I ⁇ is mounted and provided with a longitudinal and preferably cylindrical hole I6, which improve the slideable ararngem'ent of the electromagnets of a sound recording and reproducing device in their support.
  • the electromagnets each comprise a telescopelike structure or member Il, IS.
  • Portion Il is of larger diameter than portion I8 and snugly ts into hole I6; portion I8 of considerably smaller diameter than hole I6 is spaced from it, and in this space elastic means, such as a coil spring 20, are arranged so as to resiliently press member I'I, I3 towards the magnetizable member 5.
  • the outer ends of portions I8 are screw threaded and project through a hole in the top and bottom, respectively, of blocks I and 2; caps I9 screw threaded on their inside arel screwed upon those projecting ends of portions I8, whereby a kind of adjustment of the position of members or structures I1, I8 relative to the magnetizable member can be effected.
  • Portions I'I are each provided with a hole 2I open toward the magnetizable element 5.
  • a rigid electromagnet structure is arranged, comprising an exciting coil 22 and a core 26 which preferably is flat and as thin as possible.
  • are closed by rigid covers 24 preferably of non-magnetic material, such as hard stone, which are somewhat convex on their outside.
  • cover 24 is provided with a slot 25 in which the flat core 26 is rigidly seated and passes to the outer surface ofr cover 24 from which it projects preferably by a fraction of one millimeter so as to contact the magnetiza'ble element 5.
  • the space between coil 22 and hole 2I is advantageously lled with plastic or soft substance so as to prevent any relative vibrations between the coil and member I1, if'vibrations were still possible.
  • the latter are practically excluded by the rigid mounting of the electromagnetic structure proper in the rigid cover 24 and by the rigid attachment of the latter to member I1, I8.
  • Portion I1 snugly contacts hole I6 over a large surface, and thus any vibrations of the unit formed by the electromagnet proper and its supporting member are eliminated.
  • the units once properly set by adjusting screws 'I, I5 and caps I9 will maintain their position relative to the magnetizable member during operation and thereby continuous accurate recording andreproducing without distortions and scratching and other disturbing noise eiects can be made.
  • cover 24 can be chosen .so as to be non-resonantwithin sound range and it may be made heavy enough to prevent selfvibrations within audible range.
  • the magnetizable lmember grinds a groove into the projecting end of core 26 until the member contacts the outer surface of cover 24, the material of which is preferably as-hard as a steel commonly used for the magnetizable ⁇ element, or even harder; then the groove ground into the projecting end of core 26 is flush with the outer'suriace of cover 24 and Yfurzlier grinding of core 26 ceases.
  • the device can be operated over a long period of time without facing trouble as to insufficient contact bey 2,270,320 with hole is of block l.
  • the rails m may be tween core .26 and member 5 and weer ofwthe former. ,4
  • coil 22 is entirely relieved from any pressure of spring 2U and incapable of vibrating during operation.
  • the surface area of the magnet core is kept constant during operation by the action of the hard and rigid cover 24.
  • the electromagnet proper is rigidly held by that cover in the Supporting member to form a unit therewith which slideably fits into the support or block in such a manner that vibrations due to the friction between the magnet cores and covers on one hand and the magnetizable'member on the other hand are completely eliminated.
  • the pressure of springs 20 can be made such that a constant and resilient contact between the electromagnet cores and the magnetizable member issecured throughout operation and repeated adjustments as necessary with other known devices of this type and replacements of the electromagnets are avoided.
  • a magnet head arranged to contact a movable magnetizable recording eleH ment, such as a steel wire, said head comprising a support provided with a longitudinal hole directed vertically to and open toward the recording element and a unit slidably arranged in said hole, said unit comprising a member fitting a part of said hole adjacent to its opening and spaced from the remaining part of said hole, springy means arranged in said space between said support and said member for pressing the latter.
  • said member provided with a hole open toward the recording element, a rigid electro-magnet structure comprising a coil and a core spacedly arranged Within said latter hole, and a rigid cover of non-magnetic material, as exemplified by hard stone, for said latter hole xedly attached to said member and projecting from said support for contacting with its outer surface the recording element, said core rigidly seated in and passing through said cover to its outer surface so as to contact the recording element.
  • a magnet head larranged to contact a ymovable magnetizable recording element, such as a steel wire, said head comprising a support arranged vertically to the recording element and comprising a support provided with a longitudinal cylindrical holedirected vertically to and open toward the recording element and a unit slidably arranged in said hole, said unit comprising two portions of different diameter, the portion of larger diameter fitting a part of said hole.
  • a coil spring arranged around said latter portion between said member and support for pressing said member against the recording element, means for preventing relative rotation of said member and support without insupport, said coverV provided with a substantially 1 convex outer surface for contactingth'e recording element, and said core rigidly held in and passing through theslot of said cover so as to project by a fraction of a ⁇ millimeter fromV the' outer surface of ⁇ said cover and to contact the recording element.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Electromagnets (AREA)
US274399A 1938-06-30 1939-05-18 Magnetic head for electromagnetic sound recording and reproducing apparatus Expired - Lifetime US2270320A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
IT2270320X 1938-06-30

Publications (1)

Publication Number Publication Date
US2270320A true US2270320A (en) 1942-01-20

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ID=11435350

Family Applications (1)

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US274399A Expired - Lifetime US2270320A (en) 1938-06-30 1939-05-18 Magnetic head for electromagnetic sound recording and reproducing apparatus

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US (1) US2270320A (fr)
FR (1) FR856860A (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2514577A (en) * 1946-09-11 1950-07-11 Herman S Heller Magnetic recorder pole piece and assembly
US2574898A (en) * 1947-12-06 1951-11-13 Indiana Steel Products Co Electromagnetic transducer head assembly
US2790966A (en) * 1951-02-23 1957-04-30 Nat Res Dev Magnetic recording and reproducing device
US2910544A (en) * 1954-03-18 1959-10-27 Ibm Magnetic transducer

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2514577A (en) * 1946-09-11 1950-07-11 Herman S Heller Magnetic recorder pole piece and assembly
US2574898A (en) * 1947-12-06 1951-11-13 Indiana Steel Products Co Electromagnetic transducer head assembly
US2790966A (en) * 1951-02-23 1957-04-30 Nat Res Dev Magnetic recording and reproducing device
US2910544A (en) * 1954-03-18 1959-10-27 Ibm Magnetic transducer

Also Published As

Publication number Publication date
FR856860A (fr) 1940-08-13

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