US4568993A
Expired / Lapsed
US
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Magnetic head
Assignee: US Philips Corp
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Filing: 1983-01-24
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Granted: 1986-02-04
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Expires: 2003-01-24
Abstract
Abstract Magnetic head for a magnetic recording and playback apparatus includes a core of a Mn--Zn-ferrous ferrite having a very high saturation magnetization. The Mn--Zn-ferrous ferrite has a composition (not counting optional substitutions) according to the formula Mn.sub.a Zn.sub.b Fe.sub.c.sup.II Fe.sub.e.sup.III O.sub.4 with 0<a≦0.55 0.06≦b≦0.4 0.25≦c≦0.9 (a+b+c=1). The result is that the magnetic head may be used in combination with magnetic tapes having a very high coercive force (up to 104 kA/m (1300 Oersted) and may be used for transducing signals having a frequency of a few MHz.
Inventors
- 👤 Doeko Stoppels
- 👤 Piet F. Bongers
- 👤 Johannes P. M. Damen
- 👤 Eelco G. Visser
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 21:53
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/127; G11B5/187; G11B5/193; C; C04; C04B; C04B35/00; C04B35/01; C04B35/26; C04B35/2658; C30; C30B; C30B11/00; C30B29/00; C30B29/10; C30B29/16; C30B29/22; C30B29/26; G11B5/133; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/11; Y10T428/115; Y10T428/26; Y10T428/263; Y10T428/264; Y10T428/265
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
68 words
A magnetic head suitable for a magnetic recording and playback apparatus, the head comprising a core having two magnetic core parts which form a transducing gap therebetween, characterized in that the magnetic core parts consist essentially of a monocrystalline Mn--Zn-ferrous ferrite having a composition Mn.sub.a Zn.sub.b Fe.sub.c.sup.II Fe.sub.2.sup.III O.sub.4 wherein: 0<a≦0.55, 0.06<b≦0.4, 0.25<c≦0.9, (a+b+c=1); and in that the core has a thickness of not greater than 200 micrometers.
Claim 2
Dependent Claim
68 words
A magnetic head suitable for a magnetic recording and playback apparatus, the head comprising a core having two magnetic core parts which form a transducing gap therebetween, characterized in that the magnetic core parts consist essentially of a monocrystalline Mn--Zn-ferrous ferrite having a composition Mn.sub.a Zn.sub.b Fe.sub.c.sup.II Fe.sub.2.sup.III O.sub.4 wherein: 0<a≦0.55, 0.06<b≦0.4, 0.25<c≦0.9, (a+b+c=1); and in that the core has a thickness of not greater than 200 micrometers.
Claim 3
Dependent Claim
12 words
A magnetic head as claimed in claim 1, characterized in that 0.3≦c≦0.9.
Claim 4
Dependent Claim
14 words
A magnetic head as claimed in claim 1, characterized in that 0<a≦0.39 and 0.55≦c≦0.9.
Claim 5
Dependent Claim
16 words
A magnetic head as claimed in claim 1 or 2, characterized in that 0.2≦a≦0.5; 0.1≦b≦0.40; 0.25≦c≦0.40.
References Cited (Backward Citations)
US2636860A
Cited
US2886529A
Cited
DE1300859B
Cited
US3145452A
Cited
US3605258A
Cited
JPS4928076A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-02-03 | 1989-08-05 | 1990-02-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-02-03 | 1993-08-05 | 1994-02-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-02-03 | 1997-08-05 | 1998-02-04 | $7700.00 | Window Closed / Lapsed |