US4200678A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Flexible multilayer magnetic recording medium
Assignee: BASF SE
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Filing: 1978-03-30
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Granted: 1980-04-29
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Expires: 1998-03-30
Abstract
Abstract A flexible multilayer magnetic recording medium exhibiting an improved signal-to-print-through ratio coupled with an improved maximum output level and diminished dc noise, comprising a non-magnetic base and, applied thereto, at least two superposed layers consisting of a binder with magnetizable particles uniformly dispersed therein, the upper magnetic layer containing a magnetic pigment giving a signal-to-print-through ratio of less than 55db and the lower magnetic layer(s) containing a magnetic pigment giving a signal-to-print-through ratio of 55 db or more.
Inventors
- 👤 Philipp Pister
- 👤 Franz Buettner
- 👤 Fritz Hammon
- 👤 Manfred Ohlinger
- 👤 Heinz Stritzinger
- 👤 Job-Werner Hartmann
- 👤 Walter Schneider
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 16:26
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/716; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/25; Y10T428/256; Y10T428/257
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
93 words
A magnetic recording medium comprising a base and, applied thereto, at least two magnetic layers containing an acicular magnetic material in an organic binder system, wherein the upper magnetic layer contains a magnetic pigment giving a signal-to-print-through ratio of less than 55 db and the lower magnetic layer(s) contain magnetic pigments giving a signal-to-print-through ratio of 55 db or more, wherein the said magnetic pigments do not differ essentially in their magnetic properties, and wherein the minimum difference between the signal-to-print-through ratios of the upper and lower layers is at least 2.5 db.
Claim 2
Dependent Claim
93 words
A magnetic recording medium comprising a base and, applied thereto, at least two magnetic layers containing an acicular magnetic material in an organic binder system, wherein the upper magnetic layer contains a magnetic pigment giving a signal-to-print-through ratio of less than 55 db and the lower magnetic layer(s) contain magnetic pigments giving a signal-to-print-through ratio of 55 db or more, wherein the said magnetic pigments do not differ essentially in their magnetic properties, and wherein the minimum difference between the signal-to-print-through ratios of the upper and lower layers is at least 2.5 db.
Claim 3
Dependent Claim
117 words
A magnetic recording medium comprising a base and, applied thereto, three magnetic layers containing an acicular magnetic pigment in an organic binder system, the magnetic pigment of the upper layer giving a signal-to-print-through ratio of less than 53 db, the magnetic pigment of the middle layer giving values of from 53 to 56 db and the magnetic pigment of the lower layer, which is directly in contact with the base, giving values of more than 56 db, wherein the said magnetic pigments do not differ essentially in their magnetic properties, and wherein the minimum difference between the signal-to-print-through ratios of the upper layer and the layer directly in contact with the base is greater than 3 db.
Claim 4
Dependent Claim
117 words
A magnetic recording medium comprising a base and, applied thereto, three magnetic layers containing an acicular magnetic pigment in an organic binder system, the magnetic pigment of the upper layer giving a signal-to-print-through ratio of less than 53 db, the magnetic pigment of the middle layer giving values of from 53 to 56 db and the magnetic pigment of the lower layer, which is directly in contact with the base, giving values of more than 56 db, wherein the said magnetic pigments do not differ essentially in their magnetic properties, and wherein the minimum difference between the signal-to-print-through ratios of the upper layer and the layer directly in contact with the base is greater than 3 db.
Claim 5
Dependent Claim
47 words
A magnetic recording medium as set forth in claim 2, wherein the upper magnetic layer accounts for from 10 to 40% of the total thickness of the layers, the middle layer accounts for from 20 to 60% and the lower layer accounts for from 50 to 80%.
References Cited (Backward Citations)
US3761311A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-04-29 | 1983-10-29 | 1984-04-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-04-29 | 1987-10-29 | 1988-04-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-04-29 | 1991-10-29 | 1992-04-29 | $7700.00 | Window Closed / Lapsed |