Patent US3639701A successfully refreshed from Google Patents.
US3639701A
Expired / Lapsed
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Magnetic recording head having a nonmagnetic ferrite gap
Assignee: International Business Machines Corp
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Filing: 1970-07-02
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Granted: 1972-02-01
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Expires: 1990-07-02
Abstract
Abstract A magnetic head assembly is claimed. The magnetic head assembly comprises a pair of magnetic ferrites having mating surfaces and a transducing gap comprising a nonmagnetic crystalline ceramic, which may particularly be a nonmagnetic ferrite, formed as a bond between the mating surfaces. More particularly, the bond is formed by solid-state diffusion.
Inventors
- 👤 Duane R Secrist
- 👤 Harold L Turk
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 23:46
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/127; G11B5/133; G11B5/187; G11B5/23; G11B5/235; Y; Y10; Y10T; Y10T29/00; Y10T29/49; Y10T29/49002; Y10T29/4902; Y10T29/49021; Y10T29/49032; Y10T29/49055; Y10T29/49057
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
29 words
A magnetic head assembly comprising: a pair of magnetic ferrites having mating surfaces; and a transducing gap comprising a continuous nonmagnetic crystalline ferrite diffusion bonded between said mating surfaces.
Claim 2
Dependent Claim
29 words
A magnetic head assembly comprising: a pair of magnetic ferrites having mating surfaces; and a transducing gap comprising a continuous nonmagnetic crystalline ferrite diffusion bonded between said mating surfaces.
Claim 3
Dependent Claim
22 words
The magnetic head assembly set forth in claim 1 wherein said nonmagnetic ferrite has substantially the same hardness as said magnetic ferrite.
Claim 4
Dependent Claim
20 words
The magnetic head assembly set forth in claim 1 wherein said nonmagnetic ferrite has a thickness of approximately 30 microinches.
Claim 5
Dependent Claim
17 words
The magnetic head assembly set forth in claim 1 wherein said ferrites comprises a nickel-zinc ferrite composition.
Claim 6
Dependent Claim
37 words
The magnetic head assembly set forth in claim 4 wherein said nonmagnetic nickel-zinc ferrite has a chemical composition set forth by the equation Ni1 Zn Fe2O4 and wherein 0.75 < or = Delta < or = 1.0.
Claim 7
Dependent Claim
12 words
The magnetic head assembly set forth in claim 5 wherein Delta 0.9.
Claim 8
Dependent Claim
21 words
The magnetic head assembly set forth in claim 4 wherein said nonmagnetic nickel-zinc ferrite has a Curie temperature below 21* C.
Claim 9
Dependent Claim
25 words
The magnetic head assembly set forth in claim 1 wherein the constituents of said magnetic and said nonmagnetic ferrites have substantially the same diffusion coefficients.
Claim 10
Dependent Claim
25 words
The magnetic head assembly set forth in claim 1 wherein said nonmagnetic ferrite contains an element from the following group: manganese, cobalt, nickel and magnesium.
Claim 11
Dependent Claim
32 words
The magnetic head assembly set forth in claim 1 wherein said diffusion bonding is solid-state and occurs when the magnetic head assembly is heated to a temperature of at least 950* C.
Claim 12
Dependent Claim
23 words
The magnetic head assembly set forth in claim 1 wherein said nonmagnetic ferrite contains an element from the following group: zinc and cadmium.
Claim 13
Dependent Claim
65 words
A magnetic head assembly comprising: a pair of magnetic ferrites having mating surfaces; and a transducing gap comprising a nonmagnetic ferrite that is solid-state diffusion bonded between said mating surfaces; said ferrites having a nickel-zinc composition and wherein said nonmagnetic nickel-zinc ferrite has a chemical composition set forth by the equation Ni1 Zn Fe2O4 and wherein 0.75 < or = Delta < or = 1.0.
Claim 14
Dependent Claim
65 words
A magnetic head assembly comprising: a pair of magnetic ferrites having mating surfaces; and a transducing gap comprising a nonmagnetic ferrite that is solid-state diffusion bonded between said mating surfaces; said ferrites having a nickel-zinc composition and wherein said nonmagnetic nickel-zinc ferrite has a chemical composition set forth by the equation Ni1 Zn Fe2O4 and wherein 0.75 < or = Delta < or = 1.0.
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) | 1975-01-31 | 1975-08-02 | 1976-02-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-01-31 | 1979-08-02 | 1980-02-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-01-31 | 1983-08-02 | 1984-02-01 | $7700.00 | Window Closed / Lapsed |