US4439795A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic recording medium
Assignee: Fujifilm Holdings Corp
•
Filing: 1981-12-09
•
Granted: 1984-03-27
•
Expires: 2001-12-09
Abstract
Abstract A magnetic recording medium is described having formed on a non-magnetic base at least two magnetic layers, each of the magnetic layers comprising ferromagnetic particles dispersed in a binder, wherein the ferromagnetic particles in the outermost layer have an average length of 0.3μ or less and a length to width ratio of greater than 1/1 but not greater than 3/1, and the ferromagnetic particles in an underlying layer have a length to width ratio of more than 3/1.
Inventors
- 👤 Tatsuji Kitamoto
- 👤 Goro Akashi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 22:43
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/706; G11B5/70626; Y; Y10; Y10T; Y10T428/00; Y10T428/12; Y10T428/12014; Y10T428/12028; Y10T428/12049
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
73 words
A magnetic recording medium having formed on a non-magnetic base at least two magnetic layers, each comprising ferromagnetic particles dispersed in a binder, wherein the ferromagnetic particles in the outermost magnetic layer have an average length of 0.3μ or less and a length to width ratio greater than 1/1 but not greater than 3/1, and the ferromagnetic particles in an underlying magnetic layer have a length to width ratio of more than 3/1.
Claim 2
Dependent Claim
73 words
A magnetic recording medium having formed on a non-magnetic base at least two magnetic layers, each comprising ferromagnetic particles dispersed in a binder, wherein the ferromagnetic particles in the outermost magnetic layer have an average length of 0.3μ or less and a length to width ratio greater than 1/1 but not greater than 3/1, and the ferromagnetic particles in an underlying magnetic layer have a length to width ratio of more than 3/1.
Claim 3
Dependent Claim
22 words
A magnetic recording medium as in claim 1, wherein the outermost magnetic layer has a thickness of from about 0.1 to 3μ.
Claim 4
Dependent Claim
21 words
A magnetic recording medium as in claim 1, wherein the outermost magnetic layer has a thickness of from 0.3 to 1.5μ.
References Cited (Backward Citations)
US3855016A
Cited
US3761311A
Cited
US4075384A
Cited
US4246316A
Cited
US4072501A
Cited
US4259392A
Cited
US4237506A
Cited
US4307156A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-03-27 | 1987-09-26 | 1988-03-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-03-27 | 1991-09-26 | 1992-03-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-03-27 | 1995-09-26 | 1996-03-27 | $7700.00 | Window Closed / Lapsed |