US2210770A - Magnetic sound recording - Google Patents

Magnetic sound recording Download PDF

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Publication number
US2210770A
US2210770A US290696A US29069639A US2210770A US 2210770 A US2210770 A US 2210770A US 290696 A US290696 A US 290696A US 29069639 A US29069639 A US 29069639A US 2210770 A US2210770 A US 2210770A
Authority
US
United States
Prior art keywords
record carrier
width
polar
sound recording
magnetic
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
US290696A
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English (en)
Inventor
Muller-Ernesti Rolf
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.)
Licentia Patent Verwaltungs GmbH
Original Assignee
Licentia Patent Verwaltungs GmbH
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 Licentia Patent Verwaltungs GmbH filed Critical Licentia Patent Verwaltungs GmbH
Application granted granted Critical
Publication of US2210770A publication Critical patent/US2210770A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • 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
    • 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
    • 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
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S29/00—Metal working
    • Y10S29/028—Magnetic recording digest

Definitions

  • This invention relates to magnetic sound recording and particularly to erasing heads'or electromagnets for imparting a uniform magnetic condition to a telegraphone record carrier as it approaches the recording head or magnet.
  • Erasing heads have been employed that establish a saturating magnetic field and a weaker leakage field through which the record carrier passes in succession, the fields being in the longitudinal direction of the record carrier but of opposite sense.
  • the two fields were obtained by forming the magnetic core with a pole piece,- at the side of the core at which the record carrier departs from the core, that projects beyond its associated cor-e leg and extends along the record carrier to terminate in a polar tip.
  • the polar surfaces were made but slightly wider than the record carrier as it was thought that narrow polar surfaces and the attendant; high flux densities would insure uniform results. intensity noise or disturbing sounds would appear in the reproduction, thus indicating that the erasing system had not established an entirely uniform magnetic condition in all parts of the record carrier.
  • An object of the present invention is to provide a magnetic structure or erasing head that is more eflicient and effective than the prior designs.
  • An object is to provide an erasing head of the type in which a high intensity saturating field and a lower intensity leakage field act in succession on the record carrier, the erasing head having such width with respect to the rece ord carrier that lateral fluctuations of the record carrier do not destroy the homogeneity of the leakage field. More specifically, an object is to provide an erasing head having polar surfaces of from two to four times the width of the record carrier that travels along the polar surfaces.
  • Fig. 1 is a somewhat diagrammatic side elevation of an embodiment of the invention.
  • Fig. 2 is a plan view of the same.
  • the reference numeral l identifies the approximately circular core of a magnet having a winding 2 for establishing a strong unidirectional magnetic field at the gap 3 across which the record carrier or band 4 travels in the direction indicated by the arrow m.
  • the pole piece 5 at the approach side of the core has It was observed, however, that low a hat surface along which the band it travels towards the gap 8, and the pole piece 8 at the departure side of the erasing magnet is extended along the band 4, beyond the associated core leg, to terminate in a polar tip I.
  • the magnetic field at the gap 3 is in the di- 5 rectlon indicated by the arrow 0. and several lines of force are indicated by the dotted lines a.
  • the field at the polar tip I is indicated generally by the arrow 11 and the paths of typical lines of force are shown by the lines I).
  • the width of the polar surfaces is approximately three times that of the record carrier 4, and the leakage field, as indicated by lines D, is substantially parallel to the direction of travel of the record carrier.
  • Small lateral fluctuations of the record carrier do not destroy the homogeneity of the leakage field, and the magnetization characteristic of the carrier as it leaves the polar tip 1 is therefore substantially constant in spite of lateral fluctuations that cannot be entirely eliminated in a practical magnetic recorder.
  • the width ratio of 3 to I is not critical. Disturbing residiual noises will be substantially eliminated when the polar surfaces are twice the width of the record carrier if the lateral fluctuations are held to a low value. Increase of the polar width beyond about four times that of the record carrier will not add materially to the suppression of residual noise.
  • the polar surfaces are of uniform width but it will be apparent that the essential requirement is that the width of the polar tip I be adequate to insure a homogeneous leakage fleld.
  • the width of the core at the gap 3 may be somewhat smaller, if desired, but it is usually preferable and economical to have constant width polar sinfaces.
  • an erasing head comprising a core having pole pieces spaced apart by a gap across which the record carrier travels, and a direct current winding on the core, the pole piece at the departure side of the core being extended along the record t5 carrier to form a leakage polar tip having a width from two to four times the width of the record carrier.
  • each pole piece has a polar surface along which said record carrier travels, and said polar surfaces are of a constant width equal to from two to four times the width of the record carrier.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Magnetic Heads (AREA)
US290696A 1938-08-24 1939-08-17 Magnetic sound recording Expired - Lifetime US2210770A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE212669X 1938-08-24

Publications (1)

Publication Number Publication Date
US2210770A true US2210770A (en) 1940-08-06

Family

ID=5809258

Family Applications (1)

Application Number Title Priority Date Filing Date
US290696A Expired - Lifetime US2210770A (en) 1938-08-24 1939-08-17 Magnetic sound recording

Country Status (4)

Country Link
US (1) US2210770A (de)
CH (1) CH212669A (de)
FR (1) FR859259A (de)
NL (1) NL53432C (de)

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2425857A (en) * 1943-09-24 1947-08-19 Walter C Barnes Apparatus for detecting flaws in rails
US2427421A (en) * 1940-06-22 1947-09-16 Rieber Frank Apparatus and method for making and analyzing geophysical records
US2428002A (en) * 1945-03-09 1947-09-30 Edward L Barrett Wire type recording and reproducing apparatus
US2532803A (en) * 1945-01-09 1950-12-05 Gen Electric Magnetic recording, reproducing, and erasing apparatus
US2535481A (en) * 1946-10-15 1950-12-26 Brush Dev Co Demagnetizing apparatus for magnetic recorders
US2536029A (en) * 1946-12-05 1951-01-02 Armour Res Found Magnetic record member
US2635149A (en) * 1949-12-03 1953-04-14 Wilcox Gay Corp Erasing means for magnetic recorders
US2655561A (en) * 1948-08-09 1953-10-13 Lawrence H Connell Apparatus for magnetic recording
US2666813A (en) * 1949-01-12 1954-01-19 Armour Res Found Magnetic duplicating method and means
US3060279A (en) * 1957-11-06 1962-10-23 Emi Ltd Magnetic transducing heads
US3117065A (en) * 1959-09-02 1964-01-07 Magnetic Film And Tape Company Method and apparatus for making magnetic recording tape
US4043297A (en) * 1973-11-17 1977-08-23 Basf Aktiengesellschaft Device for the magnetic orientation of magnetic recording media

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2427421A (en) * 1940-06-22 1947-09-16 Rieber Frank Apparatus and method for making and analyzing geophysical records
US2425857A (en) * 1943-09-24 1947-08-19 Walter C Barnes Apparatus for detecting flaws in rails
US2532803A (en) * 1945-01-09 1950-12-05 Gen Electric Magnetic recording, reproducing, and erasing apparatus
US2428002A (en) * 1945-03-09 1947-09-30 Edward L Barrett Wire type recording and reproducing apparatus
US2535481A (en) * 1946-10-15 1950-12-26 Brush Dev Co Demagnetizing apparatus for magnetic recorders
US2536029A (en) * 1946-12-05 1951-01-02 Armour Res Found Magnetic record member
US2655561A (en) * 1948-08-09 1953-10-13 Lawrence H Connell Apparatus for magnetic recording
US2666813A (en) * 1949-01-12 1954-01-19 Armour Res Found Magnetic duplicating method and means
US2635149A (en) * 1949-12-03 1953-04-14 Wilcox Gay Corp Erasing means for magnetic recorders
US3060279A (en) * 1957-11-06 1962-10-23 Emi Ltd Magnetic transducing heads
US3117065A (en) * 1959-09-02 1964-01-07 Magnetic Film And Tape Company Method and apparatus for making magnetic recording tape
US4043297A (en) * 1973-11-17 1977-08-23 Basf Aktiengesellschaft Device for the magnetic orientation of magnetic recording media

Also Published As

Publication number Publication date
CH212669A (de) 1940-12-15
NL53432C (de) 1900-01-01
FR859259A (fr) 1940-12-14

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