US4152741A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Ferrite core magnetic head with improved reinforcement filler
Assignee: Victor Company of Japan Ltd
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Filing: 1977-12-02
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Granted: 1979-05-01
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Expires: 1997-12-02
Abstract
Abstract A ferrite core magnetic head useful in a video tape recorder is reinforced in regions near its magnetic gap by the application of a filling material which is a mixture of a glass composition such as a lead glass and a powdered electrically conducting and nonmagnetic material such as a conducting metal oxide or a metal. In thermal expansion coefficient, the glass for the filling material must be comparable to the core material of the head. The use of this filling material precludes cracking of the core by heat treatments during fabrication and deposition of dust on the head surface during operation.
Inventors
- 👤 Hideaki Mizuno
- 👤 Toshio Konno
- 👤 Kunihide Sakai
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 19:17
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/127; G11B5/133; G11B5/1335; G11B5/187; G11B5/193; G11B5/23; G11B5/235
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
136 words
A magnetic head for magnetic recording and reproducing systems, comprising: a core of an oxide ferromagnetic material shaped to provide a magentic gap with a width corresponding to the track width of a magnetic tape two which the the head is to be applied, resulting in the presence of depressions in said core in regions adjacent to said magnetic gap in the width direction of said magnetic gap; and a solid mass of a reinforcement filling material which fills up each of said depressions, said filling material being a mixture of a glass composition the thermal expansion coefficient of which is nearly equal to the thermal expansion coefficient of said oxide ferromagnetic material and a powdered electrically conducting and nonmagnetic material, said filling material having been once in a fluidized state in each of said depressions.
Claim 2
Dependent Claim
136 words
A magnetic head for magnetic recording and reproducing systems, comprising: a core of an oxide ferromagnetic material shaped to provide a magentic gap with a width corresponding to the track width of a magnetic tape two which the the head is to be applied, resulting in the presence of depressions in said core in regions adjacent to said magnetic gap in the width direction of said magnetic gap; and a solid mass of a reinforcement filling material which fills up each of said depressions, said filling material being a mixture of a glass composition the thermal expansion coefficient of which is nearly equal to the thermal expansion coefficient of said oxide ferromagnetic material and a powdered electrically conducting and nonmagnetic material, said filling material having been once in a fluidized state in each of said depressions.
Claim 3
Dependent Claim
33 words
A magnetic head as claimed in claim 1, wherein the amount of said conducting and nonmagnetic material in said filling material is in the range from about 10 to about 80% by volume.
Claim 4
Dependent Claim
19 words
A magnetic head as claimed in claim 2, wherein said conducting and nonmagnetic material is a metal oxide system.
Claim 5
Dependent Claim
30 words
A magnetic head as claimed in claim 3, wherein said metal oxide system is a Zn-ferrite expressed by the general formula Fe 2 Zn 1-x Ti x O 4 .
Claim 6
Dependent Claim
15 words
A magnetic head as claimed in claim 4, wherein x in said formula is 0.05.
Claim 7
Dependent Claim
17 words
A magnetic head as claimed in claim 2, wherein said conducting and nonmagnetic material is a metal.
Claim 8
Dependent Claim
17 words
A magnetic head as claimed in claim 2, wherein said conducting and nonmagnetic material is a cermet.
Claim 9
Dependent Claim
17 words
A magnetic head as claimed in claim 2, wherein said glass composition is a lead glass composition.
Claim 10
Dependent Claim
28 words
A magnetic head as claimed in claim 1, wherein each of said depressions is a linear groove extending generally normal to the length direction of said magnetic gap.
Claim 11
Dependent Claim
27 words
A magnetic head as claimed in claim 9, wherein said magnetic gap is provided by a thin glass film sandwhiched between two opposed surfaces of said core.
Claim 12
Dependent Claim
25 words
A magnetic head as claimed in claim 10, wherein said core is an assembly of two core members which are bonded with said glass film.
Claim 13
Dependent Claim
28 words
A magnetic head as claimed in claim 10, wherein said glass composition has a softening point higher than the softening point of the material of said glass film.
Claim 14
Dependent Claim
18 words
A magnetic head as claimed in claim 8, wherein said electrically conducting and nonmagnetic material is a Zn-ferrite.
Claim 15
Dependent Claim
31 words
A magnetic head as claimed in claim 5, wherein the amount of said Zn-ferrite in said filling material is in the range from about 20 to about 50 % by volume.
References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-04-30 | 1982-10-30 | 1983-05-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-04-30 | 1986-10-30 | 1987-05-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-04-30 | 1990-10-30 | 1991-05-01 | $7700.00 | Window Closed / Lapsed |