Patent US3775178A successfully refreshed from Google Patents.
US3775178A
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Dual-layer quadruplex video recording tape
Assignee: 3M Co
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Filing: 1971-08-26
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Granted: 1973-11-27
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Expires: 1991-08-26
Abstract
Abstract Quadruplex video recording tape having a dual-layer magnetizable coating to provide improved RF output and video signal-to-noise ratio and also greater audio output and sensitivity. The magnetizable particles of the inner layer should be magnetically oriented longitudinally and provide a coercivity of 240-600 oersteds in the longitudinal direction. The magnetizable particles of the outer layer are magnetically oriented in the crosswise direction and provide a crosswise coercivity of 3751,000 oersteds.
Inventors
- 👤 K Perrington
- 👤 P Vogelgesang
- 👤 J Knudsen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 14:12
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/716
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
25 words
Quadruplex video recording tape as defined in claim 1 wherein the magnetizable particles of the outer layer comprise cobalt oxide modified acicular gamma-iron oxide particles.
Claim 2
Dependent Claim
21 words
Quadruplex video recording tape as defined in claim 1 wherein the magnetizable particles of at least one layer comprise chromium dioxide.
References Cited (Backward Citations)
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US3505109A
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US3470021A
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US3597273A
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US3573980A
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US3679476A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-11-26 | 1977-05-28 | 1977-11-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-11-26 | 1981-05-28 | 1981-11-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-11-26 | 1985-05-28 | 1985-11-27 | $7700.00 | Window Closed / Lapsed |