US4271441A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Integral shield and bias element for magnetic tape cassettes
Assignee: Vacuumschmelze GmbH and Co KG
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Filing: 1979-07-26
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Granted: 1981-06-02
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Expires: 1999-07-26
Abstract
Abstract A flexible and resilient, magnetic shielding element fabricated out of a soft magnetic alloy is provided. This shielding element not only provides magnetic shielding, but also may be used to provide a biasing force. Thus, for example, when a magnetic head is inserted into a tape cassette, a shielding element, as provided by this invention and positioned adjacent to the magnetic head opening of the cassette and on the other side of the magnetic tape from the tape head, both shields the tape head and biases the tape against the head to afford intimate contact with the tape head. Alloys which manifest a static coercive field intensity of less than 200 mA/cm, a relative static permeability, (measured as the continuous or d.c. field permeability at 4 mA/cm), of at least 2000, a Vickers hardness of at least 180, and an elastic limit of at least 500 N/mm 2 are appropriate. Crystalline as well as amorphous, soft magnetic alloys are suitable.
Inventors
- 👤 Joachim Greiner
- 👤 Albrecht Mager
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 23:34
CPC Classifications
G; G11; G11B; G11B15/00; G11B15/60; G11B23/00; G11B23/02; G11B23/04
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
85 words
In a magnetic tape cassette of the type having upper and lower cassette housing parts with side walls, the front wall provided with an entry aperture for a magnetic head associated with a recording/playback apparatus and, facing this aperture, a magnetic screening shield and a tape biasing means comprising: a single magnetic element of uniformly resilient, "soft" magnetic alloy with an elastic limit of at least 500 N/mm 2 , whereby the uniform alloy element is both a magnetic shield and a tape biasing means.
Claim 2
Dependent Claim
85 words
In a magnetic tape cassette of the type having upper and lower cassette housing parts with side walls, the front wall provided with an entry aperture for a magnetic head associated with a recording/playback apparatus and, facing this aperture, a magnetic screening shield and a tape biasing means comprising: a single magnetic element of uniformly resilient, "soft" magnetic alloy with an elastic limit of at least 500 N/mm 2 , whereby the uniform alloy element is both a magnetic shield and a tape biasing means.
Claim 3
Dependent Claim
27 words
An improved shielding element for employment in a magnetic tape cassette as claimed in claim 1, wherein said element comprises a resilient strip of "soft" magnetic material.
Claim 4
Dependent Claim
20 words
A shielding element as described in claim 2, wherein said strip has a thickness of between 0.07 to 0.25 mm.
Claim 5
Dependent Claim
43 words
A shielding element as described in claim 1, wherein said soft magnetic alloy manifests a static coercive field intensity of less than 200 mA/cm, a relative static permeability, μ 4 , of at least 2000, and a Vickers hardness of at least 180.
Claim 6
Dependent Claim
80 words
An improved shielding element as described in claim 1, wherein said "soft" magnetic alloy consists of 72 to 77% by weight nickel, 1 to 3.5% by weight niobium, 1.5 to 2.5% by weight titanium, 4 to 11% by weight copper, 0 to 4% by weight molybdenum, minor amounts of deoxidizing additives and manufacturing--induced impurities of a total maximum of 1% by weight, and iron; provided that the total amount of copper and molybdenum lies between 4 and 13% by weight.
Claim 7
Dependent Claim
114 words
A shielding element as described in claim 1, wherein said soft magnetic alloy consists of 35 to 87% by weight nickel, 0 to 10% by weight niobium, 0 to 5% by weight titanium, 0 to 12% by weight copper, 0 to 6% by weight molybdenum, 0 to 4% by weight chromium, minor amounts of deoxidizing additives and manufacturing--induced impurities, and iron; provided that the total amount of niobium and titanium lie between 1.5 and 10% by weight and the total amount of copper, molybdenum, and chromium lie between 0 and 13% by weight; provided further that where the amount of titanium is 0% by weight, the niobium amount is at least 5% by weight.
Claim 8
Dependent Claim
116 words
An improved shielding element as described in claim 1, wherein said "soft" magnetic alloy consists of 68 to 81% by weight nickel, 0 to 10% by weight niobium, 0 to 5% by weight titanium, 0 to 12% by weight copper, 0 to 6% by weight molybdenum, 0 to 4% by weight chromium, minor amounts of deoxidizing additives and manufacturing--induced impurities, and iron; provided that the total amount of niobium and titanium lies between 1.5 and 10% by weight and the total amount of copper, molybdenum, and chromium lies between 1.5 and 13% by weight; provided further that where the amount of titanium is 0% by weight, the amount of niobium is at least 5% by weight.
Claim 9
Dependent Claim
68 words
An improved shielding element as described in claim 7 wherein the total amount of niobium and titanium lies between 2 and 9% by weight; provided that where the amount of niobium is 0% by weight, the amount of titanium lies between 2 and 3% by weight, and that where the amount of titanium is 0% by weight, the amount of niobium lies between 7 and 9% by weight.
Claim 10
Dependent Claim
26 words
An improved shielding element for employment in a magnetic tape cassette as described in claim 1, wherein said element exhibits curvature while in a relaxed state.
Claim 11
Dependent Claim
15 words
A shielding element as described in claim 1, wherein said soft magnetic alloy is amorphous.
Claim 12
Dependent Claim
43 words
A shielding element as described in claim 10, wherein said amorphous alloy has the composition Ni a Fe b X c , with 35≦a≦45, 35≦b23 45, c=20, a+b+c=100, and where X is selected from the group consisting of: phosphorous, boron, carbon, and silicon.
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) | 1984-06-01 | 1984-12-01 | 1985-06-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-06-01 | 1988-12-01 | 1989-06-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-06-01 | 1992-12-01 | 1993-06-02 | $7700.00 | Window Closed / Lapsed |