US5041189A
Expired / Lapsed
US
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Method of producing a core for magnetic head
Assignee: NGK Insulators Ltd
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Filing: 1990-09-10
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Granted: 1991-08-20
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Expires: 2010-09-10
Abstract
Abstract A composite core for magnetic head composed of ferrite and Sendust, in which a difference between a track width of ferrite track and a track width of Sendust track is so small can be obtained by subjecting a gapped bar composed of ferrite and Sendust to a laser-induced etching in an alkali metal hydroxide aqueous solution into which additives for generating aluminate ion in the aqueous solution.
Inventors
- 👤 Hideto Sandaiji
- 👤 Koji Ikeda
- 👤 Yuji Onishi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 18:38
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/127; G11B5/187; C; C04; C04B; C04B41/00; C04B41/009; C04B41/53; C04B41/5338; C04B41/5353; C04B41/80; C04B41/91; C23; C23F; C23F1/00; C23F1/02; G11B5/1871
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
69 words
In a method of producing a composite core for magnetic head composed of ferrite and ferromagnetic FE-Si-Al alloy, wherein a track width of the core for magnetic head is defined by a laser machining, the improvement comprising machining said core by a laser-induced etching in an alkali metal hydroxide aqueous solution into which at least one kind of additives for generating aluminate ion in the aqueous solution is added.
Claim 2
Dependent Claim
69 words
In a method of producing a composite core for magnetic head composed of ferrite and ferromagnetic FE-Si-Al alloy, wherein a track width of the core for magnetic head is defined by a laser machining, the improvement comprising machining said core by a laser-induced etching in an alkali metal hydroxide aqueous solution into which at least one kind of additives for generating aluminate ion in the aqueous solution is added.
Claim 3
Dependent Claim
19 words
In a method according to claim 1, wherein: said alkali metal hydroxide aqueous solution is potassium hydroxide aqueous solution.
Claim 4
Dependent Claim
29 words
In a method according to claim 1, wherein; said additives are aluminum, aluminum hydroxide, aluminum nitrate, aluminum chloride, aluminum sulfate, sodium aluminate, potassium aluminum sulfate and sodium aluminum sulfate.
References Cited (Backward Citations)
US2869267A
Cited
US3356550A
Cited
US3300349A
Cited
US3475241A
Cited
SU1320260A1
Cited
US4948460A
Cited
US4982065A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-08-19 | 1995-02-18 | 1995-08-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-08-19 | 1999-02-18 | 1999-08-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-08-19 | 2003-02-18 | 2003-08-20 | $7700.00 | Window Closed / Lapsed |