EP0399747A2
Expired / Lapsed
EP
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Substrate used for magnetic disk and magnetic recording medium using the substrate
Assignee: Hoya Corp
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Filing: 1990-05-21
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Granted: —
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Expires: 2010-05-21
Abstract
Abstract A substrate (1) for magnetic disk comprising a non-magnetic support has a material for forming pits deposited on its surface, wherein the material (2) for forming the surface pits. The material (2) is a low melting point metal and is deposited to form an island structure discontinuous in directions in the plane at the surface of the non-magnetic support (1), thereby enabling production of a magnetic disk of excellent magnetic property at high productivity, as well as a magnetic recording medium using such a substrate. An oxygen trap layer (3) is deposited over the substrate (1) and the pit forming material (2) to prevent oxygen reaching a magnetic layer (5) deposited over a support layer (4). The layers (1,3,4,5) may be respectively of sodalime glass, Ti, Cr and Coo.7 Ni o.3 and a protective carbon layer (6) may be applied.
Inventors
- 👤 Toshihiro C/O Nippon Sheet Glass Co. Ltd. Kogure
- 👤 Tomoyasu C/O Nippon Sheet Glass Co. Ltd. Shimizu
- 👤 Shinya C/O Nippon Sheet Glass Co.Ltd. Katayama
- 👤 Toshiyuki C/O Nippon Sheet Glass Co.Ltd. Sato
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-31 16:11
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/73; G11B5/739; G11B5/73911; G11B5/73921; G11B5/7368; G11B5/7369; G11B5/737
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
52 words
A substrate for a magnetic disk comprising a non-magnetic substrate in which pit-forming material is disposed to the surface thereof, wherein the material for forming the surface pit comprises a low melting metal and has an island structure discontinuous in the direction within a plane on the surface of said non-magnetic support.
Claim 2
Dependent Claim
52 words
A substrate for a magnetic disk comprising a non-magnetic substrate in which pit-forming material is disposed to the surface thereof, wherein the material for forming the surface pit comprises a low melting metal and has an island structure discontinuous in the direction within a plane on the surface of said non-magnetic support.
Claim 3
Dependent Claim
39 words
A substrate used for a magnetic disk as defined in claim 1, wherein the material for forming pits at the surface of the non-magnetic support is coated at a covering rate from 10 to 85% on the non-magnetic support.
Claim 4
Dependent Claim
36 words
A substrate used for a magnetic disk as defined in claim 1 or 2, wherein the average roughness of the material forming pits at the surface of the non-magnetic substrate is from 2 to 8 nm.
Claim 5
Dependent Claim
45 words
A substrate used for a magnetic disk as defined in any one of claims 1 to 3, wherein the low melting metal is a metal selected form the group consisting of Ag, Al, Cu and Au, or an alloy consisting of-two or more of them.
Claim 6
Dependent Claim
31 words
A substrate used for a magnetic disk as defined in any one of claims 1 to 4, wherein the non-magnetic support his a float glass plate having a soda lime composition.
Claim 7
Dependent Claim
89 words
A magnetic recording medium in which a magnetic layer is present between a non-magnetic support and a protection layer, wherein material comprising a low melting metal having an island structure discontinuous in the direction within a plane at the inner surface of the non-magnetic support is formed such that pits are formed on the surface of said protection layer, and an oxygen trap layer and a magnetic film underlying layer are disposed between the surface of said non-magnetic support formed with said low melting material and said magnetic layer.
Claim 8
Dependent Claim
89 words
A magnetic recording medium in which a magnetic layer is present between a non-magnetic support and a protection layer, wherein material comprising a low melting metal having an island structure discontinuous in the direction within a plane at the inner surface of the non-magnetic support is formed such that pits are formed on the surface of said protection layer, and an oxygen trap layer and a magnetic film underlying layer are disposed between the surface of said non-magnetic support formed with said low melting material and said magnetic layer.
Claim 9
Dependent Claim
35 words
A magnetic recording medium as defined in claim 6, wherein the material forming pits to the surface of the non-magnetic support is covered at a covering rate from 10 to 85% on said non-magnetic support.
Claim 10
Dependent Claim
33 words
A magnetic recording medium as defined in claim 6 or 7, wherein the average roughness of the material forming pits to the surface of the non-magnetic support is from 2 to 8 nm.
Claim 11
Dependent Claim
43 words
A magnetic recording medium as defined in any one of claims 6 to 8, wherein the low melting metal is a metal selected from the group consisting of Ag, Al, Cu and Au, or an alloy consisting of two or more of them.
Claim 12
Dependent Claim
27 words
A magnetic recording medium as defined in any one of claims 6 to 9, wherein the non-magnetic support is a float glass having a soda lime composition.
References Cited (Backward Citations)
No citation records indexed.
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