EP0441611A1
Expired / Lapsed
EP
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Magneto-optical recording medium and method for processing the surface
Assignee: Sharp Corp
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Filing: 1991-02-06
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Granted: —
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Expires: 2011-02-06
Abstract
Abstract A surface of a magneto-optical recording medium of the present invention is textured with fine and physical protrusions and recessions. The shapes of physical protrusions and recessions vary at each radial locations on the medium such that, for example, rough protrusions and recessions are formed in inner parts of the recording medium and fine protrusions and recessions are formed in outer parts thereof. Therefore, floating force given to a floating head from the medium being rotated based on the constant angular velocity method through an air layer in the outer parts equals floating force in the inner parts. Consequently, since the floating height of the floating head becomes constant irrespective of radial locations on the medium, information can be recorded under constant recording conditions, permitting the accuracy of the recording to improve. Regarding a method for processing the surface of a magneto-optical recording medium relating to the present invention, for example, a texture tape whose roughness is large is used in inner parts of the medium while a texture tape whose roughness is small is used in outer parts thereof. As a result, a magneto-optical recording medium having the above characteristics is produced.
Inventors
- 👤 Junichiro Nakayama
- 👤 Yoshiteru Murakami
- 👤 Hiroyuki Katayama
- 👤 Kenji Ohta
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-07 16:01
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/48; G11B5/58; G11B5/60; G11B5/6005; G11B11/00; G11B11/10; G11B11/105; G11B11/1055; G11B11/1058; G11B11/10582; G11B11/10584; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10S428/922; Y10S428/9265; Y10S428/928; Y10T; Y10T428/00; Y10T428/21; Y10T428/218; Y10T428/24; Y10T428/24355; Y10T428/31504; Y10T428/31855; Y10T428/31935
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
72 words
A magneto-optical recording medium comprising fine and physical protrusions and recessions forming a texture of the surface thereof, wherein the shapes of the physical protrusions and recessions vary at each radial locations on the magneto-optical recording medium whereby floating force given to a floating type magnetic head from the magneto-optical recording medium through an air layer becomes the same in both inner parts of the magneto-optical recording medium and outer parts thereof.
Claim 2
Dependent Claim
63 words
A magneto-optical recording medium as defined in claim 1, wherein the the protrusions and recessions forming the texture of the recording medium surface are aligned in a direction which crosses the rotating direction of the recording medium at substantially right angle in the inner parts of the recording medium and is substantially in parallel with the rotating direction in the outer parts thereof.
Claim 3
Dependent Claim
84 words
A magneto-optical recording medium as defined in claim 1, wherein the respective lengths of the protrusions and recessions are longer than their respective widths and the average orientation of the respective physical protrusions and recessions with respect to their lengths vary successively so that the average orientation crosses the rotating direction of the recording medium at substantially right angle in the inner parts of the recording medium and the average orientation is substantially in parallel with the rotating direction in the outer parts thereof.
Claim 4
Dependent Claim
36 words
A magneto-optical recording medium as defined in claim 1, wherein the texture of the surface in the inner parts of the recording medium is more rough than the texture of the surface in the outer parts.
Claim 5
Dependent Claim
57 words
A magneto-optical recording medium as defined in claim 4, wherein the maximum height R MAX of the protrusions and recessions forming the texture in the inner parts of the recording medium is 100nm to 2500nm and the maximum height R MAX of protrusions and recessions forming the texture in the outer parts is not more than 200nm.
Claim 6
Dependent Claim
63 words
A magneto-optical recording medium as defined in claim 1, wherein the physical protrusions and recessions are folds, lines representing the tops of the folds extend radially in a radial directions of the recording medium, the maximum height R MAX of the folds is 100nm to 2500nm, and the height decreases from the inner parts of the recording medium toward the outer parts thereof.
Claim 7
Independent Claim
101 words
A method for processing the surface of a magneto-optical recording medium, comprising the steps: pressing a tape having fine and physical protrusions and recessions on the surface thereof onto the surface of the rotating magneto-optical recording medium by pressure means; and moving the tape and the pressure means so that fine and physical protrusions and recessions to be formed on the recording medium surface are aligned in a direction which crosses the rotating direction of the recording medium at substantially right angle in inner parts of the recording medium and is in parallel with the rotating direction in outer parts thereof.
Claim 8
Independent Claim
71 words
A method for processing the surface of a magneto-optical recording medium, comprising the step: pressing a tape having fine and physical protrusions and recessions on the surface thereof onto the surface of the rotating magneto-optical recording medium by pressure means, wherein a tape having a relatively large roughness is used in inner parts of the recording medium while a tape having a relatively small roughness is used in outer parts thereof.
Claim 9
Independent Claim
65 words
A method for processing the surface of a magneto-optical recording medium, comprising the step: pressing a tape having fine and physical protrusions and recessions on the surface thereof onto the surface of the rotating magneto-optical recording medium by pressure means, wherein the depressing force of the pressure means is strengthened in inner parts of the recording medium while it is weakened in outer parts thereof.
Claim 10
Independent Claim
60 words
A method for processing the surface of a magneto-optical recording medium to form fine and physical protrusions and recessions whose shapes vary at each radial locations on the magneto-optical recording medium on the surface thereof, comprising the step: copying features etched on a stamper, corresponding to the features of protrusions and recessions to be formed, onto the magneto-optical recording medium.
Claim 11
Dependent Claim
45 words
A method for processing the surface of a magneto-optical recording medium as defined in claim 10, further comprising the step: coating a resin on the surface of the magneto-optical recording medium, wherein the features of the stamper are copied onto the surface of the resin.
Claim 12
Dependent Claim
27 words
A method for processing a magneto-optical recording medium as defined in claim 11, wherein a resin of an ultra violet hardening type is used as the resin.
Claim 13
Independent Claim
105 words
A method for processing a magneto-optical recording medium, comprising the steps: producing magneto-optical recording media coated with a resin on a production board for magneto-optical recording media; disposing stampers, whereon features corresponding to the respective features of fine and physical protrusions and recessions to be formed on the respective surfaces of the magneto-optical recording media are etched, in positions on the surface of copying means corresponding to the respective magneto-optical recording media; and copying the respective features of the stampers onto the respective surfaces of the resin on the magneto-optical recording media by pressing the copying means onto the production board with a constant pressure.
Claim 14
Independent Claim
110 words
A method for processing the surface of a magneto-optical recording medium, comprising the steps: producing magneto-optical recording media on a production board for magneto-optical recording media; disposing stampers, whereon features corresponding to the features of fine and physical protrusions and recessions to be formed on the surfaces of the respective magneto-optical recording media are etched, in positions on the surface of copying means corresponding to the respective magneto-optical recording media; suppling a heated thermoplastic resin to the copying means; and pressing the copying means onto the production board so that the thermoplastic resin is coated on the magneto-optical recording media while copying the features of the stampers on the resin.
Claim 15
Dependent Claim
47 words
A magneto-optical recording medium as defined in claim 1, further comprising: a substrate made of an optically transparent material; a magneto-optical recording film; and a protective film, wherein a surface of the protective film facing the floating type magnetic head is textured with the protrusions and recessions.
Claim 16
Dependent Claim
60 words
A magneto-optical recording medium as defined in claim 4, wherein the roughness of the texture decreases from the inner parts of the magneto-optical recording medium toward the outer parts thereof corresponding to the relative velocity between the magneto-optical recording medium and the floating type magnetic head when the magneto-optical recording medium is rotated based on the constant angular velocity method.
Claim 17
Dependent Claim
105 words
A magneto-optical recording medium for use in a recording and/or reproducing apparatus employing a magnetic head which in use floats over the surface of the medium on a flow of air entrained between said magnetic head and said surface at a relative linear velocity which varies in accordance with the position on the medium, said medium having physical surface characteristics which affect a floating force applied, in use, to said magnetic head to cause it to float, characterised in that said characteristics vary according to the position on said surface so as to regulate said floating force by compensating for said variation in linear velocity.
References Cited (Backward Citations)
DE3629582A1
Cited
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