EP0511622A2
Expired / Lapsed
EP
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Magnetic disk
Assignee: Maxell Ltd
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Filing: 1992-04-28
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Granted: —
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Expires: 2012-04-28
Abstract
Abstract There is provided a magnetic disk with excellent durability and high reliability and less occurrence of dropout. Discontinuous recessed portions (31) an average depth of which from the portion where the magnetic disk comes into contact with a magnetic head unit is regulated to the range of 0.01 to 0.5 micron are formed on the recording track (16) of a magnetic layer. Further, a total length (Tc = c1 + c2) in a recording track-widthwise direction of the recessed portions (31) is regulated to 50 % or less of a recording track width (b).
Inventors
- 👤 Kazuya Fukunaga
- 👤 Nobuhiro Umebayashi
- 👤 Mikio Kishimoto
- 👤 Kunio Mizushima
- 👤 Toshio Doi
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-07 13:27
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/84; G11B5/855; G11B5/74; G11B5/82; G11B5/825
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
105 words
A magnetic disk (2) having a substrate (13) composed of a non-magnetic material and a magnetic layer (14; 14a, 4b) formed on a surface thereof, comprising a multiplicity of discontinuous recessed portions (15; 31), formed on the recording tracks (16) of said magnetic layer, an average depth of which from a portion where said magnetic disk (2) comes into contact with a magnetic head unit (8a; 8b) is regulated to a range of 0.01 to 0.5 micron, wherein a total length in a recording track-widthwise direction of said recessed portions (15; 31) is regulated to 50 % or less of a recording track width (b).
Claim 2
Dependent Claim
53 words
A magnetic disk according to claim 1, wherein an average depth of said recessed portions (15; 31) is regulated to a range of 0.1 to 0.5 micron and a total length in a recording track-widthwise direction of said recessed portions is regulated to 40 % or less of a recording track width (b).
Claim 3
Dependent Claim
38 words
A magnetic disk according to claim 1, wherein said magnetic layer (14; 14a, 14b) includes magnetic powder and binder and are formed by deposition, and said recessed portions (15; 31) are formed by partially compressing said magnetic layer.
Claim 4
Dependent Claim
51 words
A magnetic disk according to claim 3, wherein projected portions (17; 33) projected from a flat surface of said magnetic layer (14; 14a, 14b) by an average of 0.01 to 0.1 micron are formed around a periphery of said recessed portions (15; 31) by formation of said recessed portions by compression.
Claim 5
Dependent Claim
18 words
A magnetic disk according to claim 3, wherein said recessed portions (15; 31) have a substantially-inverted-trapezoid-shaped cross section.
Claim 6
Dependent Claim
27 words
A magnetic disk according to claim 1, wherein said discontinuous recessed portions (15; 31) are concentrically formed about a center of rotation of said magnetic disk (2).
Claim 7
Dependent Claim
28 words
A magnetic disk according to claim 1, wherein said discontinuous recessed portions (31) are formed eccentrically with respect to the center of rotation of said magnetic disk (2).
Claim 8
Dependent Claim
35 words
A magnetic disk according to claim 1, wherein magnetic layers (14a, 14b) are formed on both surfaces of said substrate (13) and said discontinuous recessed portions (15; 31) are formed in said both magnetic layers.
Claim 9
Dependent Claim
61 words
A magnetic disk according to claim 1, wherein magnetic layers (14a, 14b) are formed on both surfaces of said substrates (13), said discontinuous recessed portions (31) are formed in a recording track of one of said magnetic layers (14a), and recessed portions (15) for tracking servo are formed in the other of said magnetic layers (14b) adjacent to a recording track.
Claim 10
Dependent Claim
111 words
A magnetic disk (2) having a substrate (13) composed of a non-magnetic material and a magnetic layer (14; 14a, 14b) formed on a surface thereof, comprising discontinuous recessed portions (15; 31) formed in a recording track of said magnetic layer (14; 14a, 14b) and having an average depth from a portion where said magnetic disk (2) comes into contact with a magnetic head unit (8a; 8b) in a range of 1/80 to 1/8 of a shortest wavelength of a signal recorded to said magnetic disk (2), wherein a total length in a recording track-widthwise direction of said recessed portions is regulated to 50 % or less of a recording track width.
Claim 11
Dependent Claim
66 words
A magnetic disk according to claim 1, wherein an average depth of said recessed portions (15; 31) is regulated to a range of 1/80 to 1/8 of a wavelength of a signal recorded to said magnetic disk (2) and a total length in a recording track-widthwise direction of said recessed portions (15; 31) is regulated to 40 % or less of a recording track width (b).
References Cited (Backward Citations)
No citation records indexed.
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