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US4953049A Expired / Lapsed US ⏱️ 0.0 years remaining

Metal-in-gap head with heat resistant layers

Assignee: OL Security LLC
•
Filing: 1988-07-12
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Granted: 1990-08-28
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Expires: 2008-07-12
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Abstract

Abstract A magnetic head comprises a pair of magnetic core halves, heat-resistant thin films and ferromagnetic thin films, the pair of magnetic core halves being opposed to each other through a non-magnetic material such as SiO 2 to form a magnetic gap. The magnetic core halves are made of a ferromagnetic oxide such as ferrite and have gap forming faces to be opposed to each other to form the magnetic gap. The gap forming faces are etched by phosphoric acid solution and then purified by reverse sputtering, so that a grown crystal of the ferromagnetic oxide is exposed on the gap forming faces. A heat-resistant thin film of a heat-resistant material such as SiO 2 is formed on each of the gap forming faces. A ferromagnetic thin film of a ferromagnetic metal material such as sendust is formed on each heat-resistant thin film. Preferably, the thickness of the heat-resistant thin film to be formed is 1 nm or more and one tenth or less of the width of the magnetic gap. For example, SiO 2 films of 5 nm in thickness as the heat-resistant thin films are formed on the respective gap forming faces and sendust films of 3 μm in thickness as the ferromagnetic metal thin films are formed on the respective SiO 2 films. In this case, the gap length of the magnetic gap is set to 0.2 μm.

Inventors

  • 👤 Hiroyuki Okuda
  • 👤 Yoshiaki Shimizu
  • 👤 Kazuo Ino
  • 👤 Kousou Ishihara
  • 👤 Takashi Ogura

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-11-03 15:03
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/127; G11B5/187; G11B5/23; G11B5/1871; G11B5/1872; G11B5/1874; G11B5/1875; G11B5/1877; G11B5/1878; Y; Y02; Y02E; Y02E50/00; Y02E50/10; Y02E50/30

Claims Analysis

Total Claims: 11
Claim 1
Independent Claim 93 words
A magnetic head having a magnetic gap between a pair of magnetic core halves opposed to each other through a non-magnetic material, said magnetic head comprising: said pair of magnetic core halves made of a ferromagnetic oxide and having gap forming faces to be opposed to each other to form said magnetic gap, said gap forming faces being purified at least by etching; heat-resistant thin films made of a heat-resistant material provided on said gap forming faces; and ferromagnetic thin films made of a ferromagnetic metal material provided on said heat-resistant thin films.
Claim 2
Dependent Claim 93 words
A magnetic head having a magnetic gap between a pair of magnetic core halves opposed to each other through a non-magnetic material, said magnetic head comprising: said pair of magnetic core halves made of a ferromagnetic oxide and having gap forming faces to be opposed to each other to form said magnetic gap, said gap forming faces being purified at least by etching; heat-resistant thin films made of a heat-resistant material provided on said gap forming faces; and ferromagnetic thin films made of a ferromagnetic metal material provided on said heat-resistant thin films.
Claim 3
Dependent Claim 35 words
A magnetic head in accordance with claim 1, wherein a thickness of each of said heat-resistant thin films is 1 nm or more and one tenth or less of a length of said magnetic gap.
Claim 4
Dependent Claim 35 words
A magnetic head in accordance with claim 1, wherein a thickness of each of said heat-resistant thin films is 2 nm or more and one twentieth or less of a length of said magnetic gap.
Claim 5
Dependent Claim 21 words
A magnetic head in accordance with claim 1, wherein the material of said heat-resistant thin films includes metal of high-melting point.
Claim 6
Dependent Claim 19 words
A magnetic head in accordance with claim 1, wherein the metal material of said ferromagnetic thin films includes sendust.
Claim 7
Dependent Claim 18 words
A magnetic head in accordance with claim 1, wherein the oxide of said magnetic core halves includes ferrite.
Claim 8
Dependent Claim 30 words
A magnetic head in accordance with claim 1, wherein a surface roughness degree of said gap forming faces is less than ten times the thickness of said heat-resistant thin films.
Claim 9
Dependent Claim 27 words
A magnetic head according to claim 1, wherein each of said gap forming faces having an appearance exposing part of a grown crystal of said ferromagnetic oxide.
Claim 10
Dependent Claim 18 words
A magnetic head in accordance with claim 1, wherein the material of said heat-resistant thin films includes oxide.
Claim 11
Dependent Claim 19 words
A magnetic head in accordance with claim 9, wherein the oxide of said heat-resistant thin films includes silicon oxide.

References Cited (Backward Citations)

US4439794A Cited
WO1983003918A1 Cited
US4841400A Cited
JPS6257115A Cited
JPS62145510A Cited
EP0238793A2 Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1993-08-27 1994-02-26 1994-08-28 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1997-08-27 1998-02-26 1998-08-28 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 2001-08-27 2002-02-26 2002-08-28 $7700.00 Window Closed / Lapsed

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