US4439794A
Expired / Lapsed
US
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Magnetic head
Assignee: Hitachi Ltd
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Filing: 1981-05-18
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Granted: 1984-03-27
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Expires: 2001-05-18
Abstract
Abstract A magnetic head which uses single crystal Mn-Zn ferrite containing up to 7% by weight of SnO2 occluded therein without being allowed to separate and which has such a construction that glass having a contraction rate lower than that of ferrite is filled in the narrowed portion near the gap, the plane forming the principal magnetic circuit of the core is allowed to coincide with the {110} plane of the ferrite and an angle theta between the <100> direction inside the {110} plane of the ferrite and the gap-forming plane is from 5 DEG to 40 DEG or 85 DEG to 120 DEG . The magnetic head having such a construction has a reduced modulation noise and extremely excellent write-and-read characteristics.
Inventors
- 👤 Yoshihiro Shiroishi
- 👤 Hideo Fujiwara
- 👤 Takeshi Kimura
- 👤 Noriyuki Kumasaka
- 👤 Nobuo Kobayashi
- 👤 Takeo Yamashita
- 👤 Teizo Tamura
- 👤 Hideo Zama
- 👤 Mitsuhiro Kudo
- 👤 Tsutomu Iimura
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 16:31
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/127; G11B5/133; G11B5/187; G11B5/193
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
156 words
A magnetic head characterized in that at least one of two magnetic blocks of high permeability facing each other via a gap consists of single crystal Mn-Zn ferrite containing up to 7% by weight of SnO 2 that is occluded therein without being allowed to separate thereby reducing the modulation noise of said magnetic head; the {110} plane of at least one of said single crystal Mn-Zn ferrite is made substantially parallel to the plane forming the principal magnetic circuit; an angle θ of the direction of <100> existing inside said {110} plane with respect to the gap-forming plane is 5° to 40° or 85° to 120°; and glass having a contraction rate at the time when the temperature is reduced from the glass setting temperature down to room temperature is lower than the contraction rate of said ferrite is fuse-attached to the surfaces of said magnetic blocks of high permeability at least near the gap.
Claim 2
Dependent Claim
156 words
A magnetic head characterized in that at least one of two magnetic blocks of high permeability facing each other via a gap consists of single crystal Mn-Zn ferrite containing up to 7% by weight of SnO 2 that is occluded therein without being allowed to separate thereby reducing the modulation noise of said magnetic head; the {110} plane of at least one of said single crystal Mn-Zn ferrite is made substantially parallel to the plane forming the principal magnetic circuit; an angle θ of the direction of <100> existing inside said {110} plane with respect to the gap-forming plane is 5° to 40° or 85° to 120°; and glass having a contraction rate at the time when the temperature is reduced from the glass setting temperature down to room temperature is lower than the contraction rate of said ferrite is fuse-attached to the surfaces of said magnetic blocks of high permeability at least near the gap.
Claim 3
Dependent Claim
25 words
The magnetic head as defined in claim 1 wherein said single crystal Mn-Zn ferrite contains 2 to 5% by weight of SnO 2 occluded therein.
Claim 4
Dependent Claim
22 words
The magnetic head as defined in claim 1 or 2 wherein said angle θ is 10° to 34° or 94° to 115°.
Claim 5
Dependent Claim
22 words
The magnetic head as defined in claim 1 or 2 wherein said angle θ is 20° to 30° or 100° to 110°.
Claim 6
Dependent Claim
20 words
The magnetic head as defined in claim 1 or 2 wherein said angle θ is about 25° or about 105°.
Claim 7
Dependent Claim
53 words
The magnetic head as defined in claim 1 or 2 wherein the balance obtained by subtracting the contraction rate of said ferrite from the contraction rate of said glass at the time when the temperature is reduced from the glass setting temperature down to room temperature is -0.2×10 -3 to -1.3×10 -3 .
Claim 8
Dependent Claim
49 words
The magnetic head as defined in claim 1 or 2 wherein said single crystal Mn-Zn ferrite in which SnO 2 is to be occluded consists of 40 to 66 mol% of Fe 2 O 3 , 10 to 50 mol% of MnO and 5 to 35 mol% of ZnO.
Claim 9
Dependent Claim
50 words
The magnetic head as defined in claim 1 or 2 wherein said single crystal ferrite in which SnO 2 is to be occluded consists of 58 (exclusive) to 65 mol% of Fe 2 O 3 , 21 to 30 mol% of MnO and 5 to 21 mol% (exclusive) of ZnO.
Claim 10
Dependent Claim
48 words
The magnetic head as defined in claim 1 or 2 wherein said single crystal ferrite in which SnO 2 is to be occluded consists of 50 to 58 mol% of Fe 2 O 3 , 26 to 30.5 mol% of MnO and 11.5 to 24 mol% of ZnO.
Claim 11
Dependent Claim
49 words
The magnetic head as defined in claim 1 or 2 wherein said single crystal ferrite in which SnO 2 is to be occluded consists of 50 to 58 mol% of Fe 2 O 3 , 21 to 26 mol% (exclusive) of MnO and 16 to 25 mol% of ZnO.
Claim 12
Dependent Claim
50 words
The magnetic head as defined in claim 1 or 2 wherein said single crystal ferrite in which SnO 2 is to be occluded consists of 50 to 58 mol% of Fe 2 O 3 , 30.5 (exclusive) to 38.5 mol% of MnO and 10 to 19.5 mol% (exclusive) of ZnO.
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) | 1987-03-27 | 1987-09-26 | 1988-03-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-03-27 | 1991-09-26 | 1992-03-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-03-27 | 1995-09-26 | 1996-03-27 | $7700.00 | Window Closed / Lapsed |