Glass substrate for a magnetic disk, magnetic disk, and methods of producing the glass substrate and the magnetic disk
AssigneeHoya Corporation
InventorsTakemi Miyamoto, Masao Takano
Life of this patent
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Abstract
On a principal surface of a glass disk substrate, a texture comprising a combination of an isotropic texture for stabilizing a flight of a magnetic head flying and traveling over a magnetic disk and an anisotropic texture for imparting a magnetic anisotropy to a magnetic layer of the magnetic disk is formed.
Claims9
A glass substrate, wherein said glass substrate is useable for a magnetic disk comprising a texture formed on at least an inner region of a principal surface of a glass disk, wherein the texture is obtained by cooperatively superposing and combining a first texture comprising at least one of protrusions and recesses ,which are continuously or discretely distributed and a second texture for imparting a magnetic anisotropy to a magnetic layer of the magnetic disk,
- wherein a ratio Ra(r)/Ra(c) of a surface roughness Ra(r) in a radial direction of the disk with respect to a surface roughness Ra(c) in a circumferential direction of the disk is greater than 1 and Ra(c) is 0.2 nm to 0.8 nm.
A glass substrate for a magnetic disk, which is obtained by forming, on a principal surface of a glass disk, a first texture and thereafter forming a second texture for imparting a magnetic anisotropy to a magnetic layer of the magnetic disk,
- wherein the first and second textures are cooperatively superposed and combined,
- the first texture comprises at least one of protrusions and recesses, which are continuously or discretely distributed, and
- a ratio Ra(r)/Ra(c) of a surface roughness Ra(r) in a radial direction of the disk with respect to a surface roughness Ra(c) in a circumferential direction of the disk is greater than 1 and Ra(c) is 0.2 nm to 0.8 nm.
A magnetic disk, operable in connection with a magnetic head frying and traveling over said magnetic disk, comprising:
- a glass substrate;
- a texture formed on at least an inner region of a principal surface of said glass substrate, wherein the texture is obtained by cooperatively superposing and combining a first texture and a second texture for imparting a magnetic anisotropy to a magnetic layer of the magnetic disk,
- wherein the first texture comprises at least one of protrusions and recesses, which are continuously or discretely distributed, and
- a ratio Ra(r)/Ra(c) of a surface roughness Ra(r) in a radial direction of the disk with respect to a surface roughness Ra(c) in a circumferential direction of the disk is greater than 1 and Ra(c) is 0.2 nm to 0.8 nm.
A magnetic disk, having a magnetic layer and being operable in connection with a magnetic head flying and traveling over said magnetic disk, comprising:
- a glass disk having a principal surface;
- a first texture formed first on said principal surface of said glass disk, and
- a second texture subsequently formed on said principal surface of said glass disk, said second texture being operative to impart a magnetic anisotropy to the magnetic layer of the magnetic disk,
- wherein the first and second textures are cooperatively superposed and combined,
- the first texture comprises at least one of protrusions and recesses, which are continuously or discretely distributed, and
- a ratio Ra(r)/Ra(c) of a surface roughness Ra(r) in a radial direction of the disk with respect to a surface roughness Ra(c) in a circumferential direction of the disk is greater than 1 and Ra(c) is 0.2 nm to 0.8 nm.
Dependencies are inferred from the claim text.