US4180835A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic erasing head with gaps utilizing high flux density and high permeability
Assignee: Sony Corp
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Filing: 1978-06-05
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Granted: 1979-12-25
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Expires: 1998-06-05
Abstract
Abstract In a magnetic erasing head having a first gap and a second gap formed respectively between ferrite cores, one or more magnetic material layers (Fe-layers) are arranged in the gaps respectively, and the magnetic material layers have the magnetic flux density (B 10 ) of more than 5000 gauss, the permeability of more than 5000 and the thickness of 5μ to 30μ.
Inventors
- 👤 Haruhiko Okumura
- 👤 Masanori Kanaya
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 20:44
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/127; G11B5/265; G11B5/2652; G11B5/2654; G11B5/2655; G11B5/2657; G11B5/187
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
156 words
A magnetic erasing head for erasing recorded signals on a magnetic recording medium which is facing to the front surface of said magnetic erasing head, comprising: (A) first, second and third core elements made of ferrite; (B) first and second gaps formed between said first and second core elements, and between said second and third core elements, respectively, facing toward said magnetic recording medium; (C) one or more magnetic material layers having higher magnetic flux density and higher permeability than the magnetic flux density of said ferrite core elements mounted in said first and second gaps, respectively, said layers having magnetic flux density B 10 of more than 5000 gauss, permeability μ of more than 5000, and thicknesses of 5 to 30μ in the lengthwise direction of said gaps; and (D) a winding provided around at least one of said core elements to generate magnetic flux in said core elements by an application of AC current.
Claim 2
Dependent Claim
156 words
A magnetic erasing head for erasing recorded signals on a magnetic recording medium which is facing to the front surface of said magnetic erasing head, comprising: (A) first, second and third core elements made of ferrite; (B) first and second gaps formed between said first and second core elements, and between said second and third core elements, respectively, facing toward said magnetic recording medium; (C) one or more magnetic material layers having higher magnetic flux density and higher permeability than the magnetic flux density of said ferrite core elements mounted in said first and second gaps, respectively, said layers having magnetic flux density B 10 of more than 5000 gauss, permeability μ of more than 5000, and thicknesses of 5 to 30μ in the lengthwise direction of said gaps; and (D) a winding provided around at least one of said core elements to generate magnetic flux in said core elements by an application of AC current.
Claim 3
Dependent Claim
24 words
A magnetic erasing head according to claim 1, in which said magnetic flux density B 10 of said layers is more than 7000 gauss.
Claim 4
Dependent Claim
44 words
A magnetic erasing head according to claim 1, in which said first and third core elements are C-shaped, and said second core element is I-shaped, and said first and third core elements being abutted with said third core element to form an E-shaped core.
Claim 5
Dependent Claim
28 words
A magnetic erasing head according to claim 1, in which the total gap length of said first and second gaps is within the range of 50 to 300μ.
Claim 6
Dependent Claim
46 words
A magnetic erasing head according to claim 1, in which at least said layers are mounted in said gaps adjacent the edges of said gaps by which portions of said magnetic recording medium initially pass the transporting direction of said magnetic recording medium, in said gaps.
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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) | 1982-12-24 | 1983-06-25 | 1983-12-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-12-24 | 1987-06-25 | 1987-12-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-12-24 | 1991-06-25 | 1991-12-25 | $7700.00 | Window Closed / Lapsed |