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US 5,846,628 AGranted
Magnetic disc
AssigneeMitsubishi Kasei Corporation
InventorsToru Kuroe, Fumiaki Yokoyama, Daisuke Mouri
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AssigneeMitsubishi Kasei Corporation
InventorsToru Kuroe, Fumiaki Yokoyama, Daisuke Mouri
Estimating the term…
Disclosed herein is a substrate for a magnetic disc comprising a glass substrate having fine protrusions on its surface, the protrusions having a height of 50 to 1000 .ANG., a width of 0.01 to 1 .mu.m, a density of 10 to 1000 per 100 .mu.m.sup.2 and an area ratio of 0.1 to 50%, and a ratio of peak height on a mean line (R.sub.p) to maximum height (R.sub.max) with respect to surface roughness of the substrate being at least 60%. Further, a process for preparing the substrate and a magnetic disc having the substrate are disclosed. Because the substrate according to the present invention has appropriate protrusions on its surface, a friction force and an adsorbing force between a head and a magnetic disc can be reduced, leading to the improvement of the CSS and the anti-head stick properties. In addition, the S/N ratio is not affected because the fine concave portions formed on the surface of the substrate are shallow.
A magnetic disc comprising a glass substrate on which an undercoat film, a magnetic film and a protective film are successively formed, the substrate having protrusions on the surface on which the films are formed, the protrusions having a height of 50 to 1000 .ANG., a width of 0.01 to 1 .mu.m, a density of 10 to 1000 per 100 .mu.m.sup.2 and an area ratio of 0.1 to 50%, and its surface roughness complying with the ratio R.sub.p /R.sub.max wherein R.sub.p represents a peak height from a mean line which equally divides the area of the surface profile and R.sub.max represents a maximum height (peak-to-valley) of the surface profile and R.sub.p /R.sub.max is greater than or equal to 60%.
A substrate for a magnetic disc comprising a glass substrate having protrusions on its surface, the protrusions having a height of 50 to 1000 .ANG., and a height deviation of less than or equal to .+-.50 .ANG., a width of 0.01 to 1 .mu.m, a density of 10 to 1000 per 100 .mu.m.sup.2 and an area ratio of 0.1 to 50%, and its surface roughness complying with the ratio R.sub.p /R.sub.max wherein R.sub.p represents a peak height from a mean line which equally divides the area of the surface profile and R.sub.max represents a maximum height peak-to-valley of the surface profile wherein R.sub.p /R.sub.max is greater than or equal to 60%.
Dependencies are inferred from the claim text.