Patent US4787004A successfully refreshed from Google Patents.
US4787004A
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Magnetic head including single crystal and polycrystalline ferrites with interfacial oxide layer
Assignee: Sony Corp
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Filing: 1987-07-06
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Granted: 1988-11-22
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Expires: 2007-07-06
Abstract
Abstract A composite magnetic head in which a single crystal ferrite is used at the slide contact portion with the magnetic recording medium and a polycrystalline ferrite is used at the portion constituting the back magnetic circuit, is disclosed. An oxide magnetic thin film is formed at the junction interface between the single crystal ferrite and the polycrystalline ferrite for providing a magnetic head free from diffusion at the junction surface and evidencing only a low slide noise level.
Inventors
- 👤 Hiraku Akiho
- 👤 Hideaki Karamon
- 👤 Sadayuki Nishiuchi
- 👤 Toru Sugai
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 22:43
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/127; G11B5/133; G11B5/187; G11B5/193
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
84 words
A composite type magnetic head including a single crystal ferrite having a magnetic gap at the portion which contacts the magnetic recording medium and a polycrystalline ferrite magnetically coupled to said single crystal ferrite and having a portion constituting a back magnetic circuit, and an oxide magnetic thin film at the junction interface between said single crystal ferrite portion and the polycrystalline ferrite portion, said thin film resulting from crystal grains of very fine and uniform size which exhibit non-uniform grain growth when heated.
Claim 2
Dependent Claim
84 words
A composite type magnetic head including a single crystal ferrite having a magnetic gap at the portion which contacts the magnetic recording medium and a polycrystalline ferrite magnetically coupled to said single crystal ferrite and having a portion constituting a back magnetic circuit, and an oxide magnetic thin film at the junction interface between said single crystal ferrite portion and the polycrystalline ferrite portion, said thin film resulting from crystal grains of very fine and uniform size which exhibit non-uniform grain growth when heated.
Claim 3
Dependent Claim
85 words
A composite type magnetic head including a single crystal ferrite having a magnetic gap at the portion which contacts a magnetic recording medium and a polycrystalline ferrite facing said single crystal ferrite and having a portion constituting a back magnetic circuit, and at least one oxide magnetic thin film at the junction interface between said single crystal ferrite portion and the polycrystalline ferrite portion, said single crystal ferrite portion including a plurality of magnetic thin films which contact each other to form a magnetic gap.
Claim 4
Dependent Claim
85 words
A composite type magnetic head including a single crystal ferrite having a magnetic gap at the portion which contacts a magnetic recording medium and a polycrystalline ferrite facing said single crystal ferrite and having a portion constituting a back magnetic circuit, and at least one oxide magnetic thin film at the junction interface between said single crystal ferrite portion and the polycrystalline ferrite portion, said single crystal ferrite portion including a plurality of magnetic thin films which contact each other to form a magnetic gap.
Claim 5
Dependent Claim
26 words
A composite type magnetic head according to claim 1 wherein the oxide magnetic film is a ferrite magnetic thin film having a spinel type crystal structure.
Claim 6
Dependent Claim
27 words
A composite type magnetic head according to claim 2 wherein the oxide magnetic thin film is a ferrite magnetic thin film having a spinel type crystal structure.
Claim 7
Dependent Claim
27 words
A composite type magnetic head according to claim 1 wherein the oxide magnetic thin film has a film thickness in the range of 0.8 to 3 microns.
Claim 8
Dependent Claim
27 words
A composite type magnetic head according to claim 2 wherein the oxide magnetic thin film has a film thickness in the range of 0.8 to 3 microns.
Claim 9
Dependent Claim
24 words
A composite type magnetic head according to claim 1 wherein the single crystal ferrite has a depthwise dimension of not larger than 100 microns.
Claim 10
Dependent Claim
24 words
A composite type magnetic head according to claim 2 wherein the single crystal ferrite has a depthwise dimension of not larger than 100 microns.
References Cited (Backward Citations)
US4409633A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-11-22 | 1992-05-23 | 1992-11-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-11-22 | 1996-05-23 | 1996-11-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-11-22 | 2000-05-23 | 2000-11-22 | $7700.00 | Window Closed / Lapsed |