Patent US5018038A successfully refreshed from Google Patents.
US5018038A
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US
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Thin film magnetic head with laminated metal and non magnetic film
Assignee: Fujifilm Holdings Corp
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Filing: 1989-09-27
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Granted: 1991-05-21
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Expires: 2009-09-27
Abstract
Abstract A thin film magnetic head adapted for recording and/or reproducing signals at a frequency of 1 MHz or higher, in which a soft magnetic film having uniaxial magnetic anisotropy is used as a magnetic pole film material and the direction of the magnetic path of the magnetic circuit of the head is arranged to be substantially orthogonal to the axis of easy magnetization, wherein a magnetic pole film constituting the magnetic path is formed as a lamination of at least two, particularly four soft magnetic films, with an intervening nonmagnetic film between the adjacent soft magnetic films, the length W of the magnetic pole film along the direction of the axis of easy magnetization is 30 μm≦W≦300 μm, and the uniaxial magnetic anisotropy constant Ku is Ku≦300 J/m 3 . This provides a relative permeance of at least 1000.
Inventors
- 👤 Kanji Nakanishi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 18:28
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/127; G11B5/31; G11B5/3109; G11B5/3113
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
141 words
A thin film magnetic head adapted for recording and/or reproducing signals at a high frequency of 1 MHz or higher, in which a soft magnetic metal film having uniaxial magnetic anisotropy is used as a magnetic pole film material and the direction of the magnetic path of the magnetic circuit of the head is arranged to be substantially orthogonal to the axis of easy magnetization, wherein the improvement comprises: the magnetic pole film material constituting the magnetic path being formed as a lamination of two or more soft magnetic metal films, with an intervening nonmagnetic film between the adjacent soft magnetic metal films, the length W of the magnetic pole film material along the direction of the axis of easy magnetization being such that 30 μm≦W≦300 μm, and the uniaxial magnetic anisotropy constant Ku being such that Ku≦300 J/m 3 .
Claim 2
Dependent Claim
141 words
A thin film magnetic head adapted for recording and/or reproducing signals at a high frequency of 1 MHz or higher, in which a soft magnetic metal film having uniaxial magnetic anisotropy is used as a magnetic pole film material and the direction of the magnetic path of the magnetic circuit of the head is arranged to be substantially orthogonal to the axis of easy magnetization, wherein the improvement comprises: the magnetic pole film material constituting the magnetic path being formed as a lamination of two or more soft magnetic metal films, with an intervening nonmagnetic film between the adjacent soft magnetic metal films, the length W of the magnetic pole film material along the direction of the axis of easy magnetization being such that 30 μm≦W≦300 μm, and the uniaxial magnetic anisotropy constant Ku being such that Ku≦300 J/m 3 .
Claim 3
Dependent Claim
22 words
The thin film magnetic head as defined in claim 1, in which said intervening nonmagnetic film is 0.002 to 0.1 μm thick.
Claim 4
Dependent Claim
22 words
The thin film magnetic head as defined in claim 1, in which said intervening nonmagnetic film is 0.002 to 0.05 μm thick.
Claim 5
Dependent Claim
20 words
The thin film magnetic head as defined in claim 1, in which said soft magnetic films are of two-layered lamination.
Claim 6
Dependent Claim
28 words
The thin film magnetic head as defined in claim 4, in which W is 90 to 300 μm and Ku is not more than 200 J/m 3 .
Claim 7
Dependent Claim
25 words
The thin film magnetic head as defined in claim 5, in which the soft magnetic layers have a relative magnetic permeability of at least 1100.
Claim 8
Dependent Claim
20 words
The thin film magnetic head as defined in claim 1, in which said soft magnetic films are of four-layered lamination.
Claim 9
Dependent Claim
21 words
The thin film magnetic head as defined in claim 7, in which Ku is not more than 250 J/m 3 .
Claim 10
Dependent Claim
25 words
The thin film magnetic head as defined in claim 8, in which the soft magnetic layers have a relative magnetic permeability of at least 1100.
Claim 11
Dependent Claim
28 words
The thin film magnetic head as defined in claim 7, in which W is 50 to 200 μm and Ku is not more than 200 J/m 3 .
Claim 12
Dependent Claim
25 words
The thin film magnetic head as defined in claim 10, in which the soft magnetic layers have a relative magnetic permeability of at least 1300.
Claim 13
Dependent Claim
25 words
The thin film magnetic head as defined in claim 1, in which the soft magnetic layers have a relative magnetic permeability of at least 1000.
Claim 14
Dependent Claim
26 words
The thin film magnetic head as defined in claim 1, in which said soft magnetic layers have a total thickness of not more than 12 μm.
Claim 15
Dependent Claim
27 words
The thin film magnetic head as defined in claim 13, in which each of the soft magnetic layers has a thickness of not more than 6 μm.
Claim 16
Dependent Claim
27 words
The thin film magnetic head as defined in claim 14, in which each of the soft magnetic layers has a thickness of not more than 3 μm.
Claim 17
Dependent Claim
20 words
The thin film magnetic head as defined in claim 15, in which the soft magnetic layers are of four-layer lamination.
Claim 18
Dependent Claim
24 words
The thin film magnetic head as defined in claim 1, in which said soft magnetic metal layers are an amorphous Co-base alloy or permalloy.
Claim 19
Dependent Claim
20 words
The thin film magnetic head as defined in claim 1, in which said intervening nonmagnetic film is oxide of metal.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-05-20 | 1994-11-19 | 1995-05-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-05-20 | 1998-11-19 | 1999-05-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-05-20 | 2002-11-19 | 2003-05-21 | $7700.00 | Window Closed / Lapsed |