US3904540A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic impulse record member
Assignee: ISK MAGNETICS Inc
•
Filing: 1973-06-18
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Granted: 1975-09-09
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Expires: 1993-06-18
Abstract
Abstract A magnetic impulse record member comprising a binding medium and synthetic magnetic gamma ferric oxide, said member having an orientation ratio of at least 2.4 in a 1000 oersted field, said ferric oxide produced from synthetic lepidocrocite by coating same with at least one 8-24 carbon atom hydrophobic aliphatic monocarboxylic acid, reducing and oxidizing the coated lepidocrocite, and mechanically densifying the gamma ferric oxide product, said synthetic lepidocrocite having very fine-grained, needle-like crystalline particles at least 70 percent of which have a length to width ratio greater than 10:1 and a length up to 2 microns.
Inventors
- 👤 Leonard M Bennetch
- 👤 Harry S Greiner
- 👤 Kenneth R Hancock
- 👤 Mark Hoffman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 13:25
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/706; G11B5/70626; G11B5/70642; G11B5/70652; G11B5/70663; C; C01; C01G; C01G49/00; C01G49/02; C01G49/06; G11B5/70647; C01P; C01P2004/00; C01P2004/10; C01P2004/51; C01P2004/54; C01P2004/60; C01P2004/61; C01P2006/00; C01P2006/40; C01P2006/42
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
108 words
A MAGNETIC IMPULSE RECORD MEMBER COMPRISING A BLINDING MEDIUM HAVING THEREIN SYNTHETIC MAGNETIC GAMMA FERRIC OXIDE, SAID MEMBER CHARACTERIZED BY HAVING AN ORIENTATION RATIO OF AT LEAST 2.4 IN A 1000 OERSTED FIELD, SAID FERRIC OXIDE PRODUCED FROM SYNTHETIC LEPIDOCROCITE BY COATING THE LEPIDOCROCITE PARTICLES WITH AT LEAST ONE HYDROPHOBIC ALIPHATIC MONOCARBOXYLIC ACID HAVING 8-24 CARBON ATOMS, REDUCING AND OXIDIZING THE COATED LEPIDOCROCITE, AND MECHANICALLY DENSIFYING THE GAMMA FERRIC OXIDE PRODUCT, SAID SYNTHETIC LEPIDOCROCITE CHARACERIZED BY HAVING VERY FINE-GRAINED, NEEDLE-LIKE CRYSTALLINE PARTICLES WITH AT LEAST ABOUT 70 PERCENT OF THE PARTICLES HAVING A LENGTH TO WIDTH RATIO GREATER THAN 10:1 AND A LENGHT UP TO BOUT 2 MICRONS.
Claim 2
Dependent Claim
108 words
A MAGNETIC IMPULSE RECORD MEMBER COMPRISING A BLINDING MEDIUM HAVING THEREIN SYNTHETIC MAGNETIC GAMMA FERRIC OXIDE, SAID MEMBER CHARACTERIZED BY HAVING AN ORIENTATION RATIO OF AT LEAST 2.4 IN A 1000 OERSTED FIELD, SAID FERRIC OXIDE PRODUCED FROM SYNTHETIC LEPIDOCROCITE BY COATING THE LEPIDOCROCITE PARTICLES WITH AT LEAST ONE HYDROPHOBIC ALIPHATIC MONOCARBOXYLIC ACID HAVING 8-24 CARBON ATOMS, REDUCING AND OXIDIZING THE COATED LEPIDOCROCITE, AND MECHANICALLY DENSIFYING THE GAMMA FERRIC OXIDE PRODUCT, SAID SYNTHETIC LEPIDOCROCITE CHARACERIZED BY HAVING VERY FINE-GRAINED, NEEDLE-LIKE CRYSTALLINE PARTICLES WITH AT LEAST ABOUT 70 PERCENT OF THE PARTICLES HAVING A LENGTH TO WIDTH RATIO GREATER THAN 10:1 AND A LENGHT UP TO BOUT 2 MICRONS.
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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) | 1978-09-08 | 1979-03-10 | 1979-09-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-08 | 1983-03-10 | 1983-09-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-08 | 1987-03-10 | 1987-09-09 | $7700.00 | Window Closed / Lapsed |