Substrate for information recording medium, information recording medium, and method for controlling surface of substrate for information recording medium
AssigneeHoya Corporation
InventorsTomotaka Yokoyama, Takemi Miyamoto, Hiroshi Tomiyasu, Kouji Takahashi
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Abstract
A substrate for an information recording medium, wherein the period of microwaviness is 2 μm to 4 mm, and if we let wa be the maximum height of this microwaviness and Rmax be the maximum height measured by atomic force microscope, the main surface of the substrate has a wa of no more than 5 nm and an Rmax of no more than 12 nm, provided that wa is the difference between the highest and lowest points on a measurement curve of all measured points in a measurement area.
Claims11
A substrate for an information recording medium, wherein the period of microwaviness is 2 μm to 4 mm, and if we let wa be the maximum height of this microwaviness and Rmax be the maximum height measured by atomic force microscope, the main surface of the substrate has a wa of no more than 5 nm and an Rmax of no more than 12 nm, provided that wa is the difference between the highest and lowest points on a measurement curve of all measured points in a measurement area.
A substrate for an information recording medium, wherein the period of microwaviness is 2 μm to 4 mm, the product of multiplying the maximum height wa (units:
- nm) of this microwaviness by the maximum height Rmax (units:
- nm) measured by atomic force microscope is compared with the result of forming at least a magnetic layer on the main surface of the substrate for an information recording medium and conducting a touchdown height test, and a specific Rmax×wa is set so that the desired touchdown height value will be obtained for the correlation between the product of Rmax and wa and the touchdown height.
A method for controlling the surface of a substrate for an information recording medium, wherein the period of microwaviness measured for the main surface of the substrate for an information recording medium is 2 μm to 4 mm, the correlation is found between the product of the maximum height wa (units:
- nm) of this microwaviness and the maximum height Rmax (units:
- nm) measured by atomic force microscope and the touchdown height T of said information recording medium when at least a magnetic layer is formed on the main surface of the substrate for an information recording medium, and the Rmax×wa of the substrate for an information recording medium is determined such that the information recording medium will have the desired touchdown height for the found correlation.
Dependencies are inferred from the claim text.