US5279877A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magneto optical disc
Assignee: TDK Corp
•
Filing: 1992-08-27
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Granted: 1994-01-18
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Expires: 2012-08-27
Abstract
Abstract A protective coating made of resin, preferably a radiation curable resin containing fluoroplastic fine particles having a low surface energy is provided in the form of the uppermost layer facing a magnetic head, thereby improving the frictional properties and durability of a magneto-optical disc that is used with a magnetic field modulation system in which the magnetic head comes in constant contact therewith.
Inventors
- 👤 Ryota Uchiyama
- 👤 Hiroyuki Endo
- 👤 Isamu Kuribayashi
- 👤 Shin-ichi Tezuka
- 👤 Tsuneo Kuwahara
- 👤 Hideki Hirata
- 👤 Setsuko Shibuya
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 22:46
CPC Classifications
G; G11; G11B; G11B11/00; G11B11/10; G11B11/105; G11B11/10582; G11B11/10584; C; C09; C09D; C09D127/00; C09D127/02; C09D127/12; C09D127/18; G11B5/00; G11B5/62; G11B5/72; G11B5/726; G11B5/74; G11B5/82; Y; Y10; Y10T; Y10T428/00; Y10T428/25; Y10T428/254; Y10T428/31504; Y10T428/3154; Y10T428/31544
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
126 words
A magnetic field modulation type of magneto-optical disc, comprising: a substrate; a recording layer formed on said substrate; a protecting coating formed on said recording layer; and said protecting coating is a layer of a resin containing fine particles of polytetrafluoroethylene having a molecular weight of 600 to 200,000, said protecting coating having a thickness of 1 to 30 μm and further including a fluorine-containing nonionic surfactant in accordance with the following formula: ##STR5## wherein: Rf designates a perfluoroalkyl group having 4 to 12 carbon atoms; L 1 denotes a sulfonyl group; L 2 denotes a carbonyl or carbonyloxy group; R 1 denotes a hydrogen atom or an alkyl group; R 2 denotes an alkyl group; and m denotes a positive integer of 1 to 20.
Claim 2
Dependent Claim
126 words
A magnetic field modulation type of magneto-optical disc, comprising: a substrate; a recording layer formed on said substrate; a protecting coating formed on said recording layer; and said protecting coating is a layer of a resin containing fine particles of polytetrafluoroethylene having a molecular weight of 600 to 200,000, said protecting coating having a thickness of 1 to 30 μm and further including a fluorine-containing nonionic surfactant in accordance with the following formula: ##STR5## wherein: Rf designates a perfluoroalkyl group having 4 to 12 carbon atoms; L 1 denotes a sulfonyl group; L 2 denotes a carbonyl or carbonyloxy group; R 1 denotes a hydrogen atom or an alkyl group; R 2 denotes an alkyl group; and m denotes a positive integer of 1 to 20.
Claim 3
Dependent Claim
22 words
A magneto-optical disc as recited in claim 1, wherein said fine particles have a mean particle diameter of 0.1 to 10 μm.
Claim 4
Dependent Claim
22 words
A magneto-optical disc as recited in claim 1, wherein said protecting coating contains 2 to 40% by weight of said fine particles.
Claim 5
Dependent Claim
20 words
A magneto-optical disc as recited in claim 1, wherein said resin containing said fine particles is a radiation curing resin.
Claim 6
Dependent Claim
25 words
A magneto-optical disc as recited in claim 1, wherein said nonionic surfactant contains a component having a molecular weight of substantially no greater than 20,000.
Claim 7
Dependent Claim
25 words
A magneto-optical disc as recited in claim 1, wherein the amount of said nonionic surfactant in said protecting coating is 0.1 to 5% by weight.
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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) | 1997-01-17 | 1997-07-19 | 1998-01-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-01-17 | 2001-07-19 | 2002-01-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-01-17 | 2005-07-19 | 2006-01-18 | $7700.00 | Window Closed / Lapsed |