Magnetic recording disk medium having a magnetic layer with uniform properties over the disk surface
AssigneeHitachi, Ltd.
InventorsShinji Fukaya, Yoshinori Honda, Akira Kato, Shuichi Kojima
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Abstract
A magnetic recording has very low warp characteristics but excellent film characteristics. Particularly, the recording medium has a high coercivity with a small range of coercivity distribution, with a warp characteristic below 3 .mu.m per radial inch. The medium is formed by heating a substrate at a high temperature with a temperature distribution on the substrate that is improved by the use of a heat distribution mask, which reduces the temperature distribution of the substrate to below .+-.3%.
Claims57
A magnetic disk recording medium, comprising:
- a substrate;
- a base layer on the substrate;
- a magnetic layer on the base layer;
- a protective layer on the magnetic layer;
- and
- a lubricating layer on the protective layer;
- wherein the magnetic disk recording medium is fabricated by heating the substrate through a heat radiation distribution mask to produce a substrate of elevated temperature, and then forming the magnetic layer on the substrate of elevated temperature;
- and
- wherein the magnetic disk recording medium has a radial warp due to said substrate heating that does not exceed 3 .mu.m/inch from a center thereof.
A magnetic disk recording medium, comprising:
- a substrate;
- a base layer on the substrate;
- a magnetic layer on the base layer:
- protective layer on the magnetic layer;
- and
- a lubricating layer on the protective layer;
- wherein the magnetic disk recording medium is fabricated by heating the substrate through a heat radiation distribution mask to introduce a substrate of elevated temperature, and then forming the magnetic layer on the substrate of elevated temperature;
- and
- wherein no part of the magnetic disk recording medium periphery has a warp due to said heating that exceeds 10 .mu.m relative to the magnetic disk recording medium center.
A magnetic disk recording medium, comprising:
- a substrate;
- a base layer on the substrate;
- a magnetic layer on the base layer;
- a protective layer on the magnetic layer;
- and
- a lubricating layer on the protective layer;
- wherein the magnetic layer has a coercive force of at least 2000 Oe and a range of in-plane coercive force distribution of .+-.5%;
- and
- wherein the magnetic disk recording medium is fabricated by heating the substrate through a heat radiation distribution mask to produce a substrate of elevated temperature, and then forming the magnetic layer on the substrate of elevated temperature.
Dependencies are inferred from the claim text.