Magnetic-disk glass substrate and magnetic disk
US-2015213826-A1 · Jul 30, 2015 · US
Magnetic-disk glass substrate and magnetic disk
US9607647B2 · US · B2
| Field | Value |
|---|---|
| Publication number | US-9607647-B2 |
| Application number | US-201314432184-A |
| Country | US |
| Kind code | B2 |
| Filing date | Sep 30, 2013 |
| Priority date | Sep 28, 2012 |
| Publication date | Mar 28, 2017 |
| Grant date | Mar 28, 2017 |
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Abstract
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A magnetic-disk glass substrate of the present invention has a pair of main surfaces, and an arithmetic mean roughness (Ra) for wavelength components of 10 to 50 nm of the surface of the main surfaces is 0.15 nm or less.
First claim
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The invention claimed is: 1. A magnetic-disk glass substrate for use as a magnetic disk, the magnetic-disk glass substrate comprising: a pair of main surfaces, an arithmetic mean roughness for wavelength components of 10 to 50 nm of a surface of the main surfaces being 0.15 nm or less when an area of 1 μm square is divided into sections of 512 by 512 and each section is measured using an atomic force microscope, there is no texture in a circumferential direction on the main surfaces, and the magnetic disk having a linear recording density of at least 2000 kbpi. 2. A magnetic disk in which at least a magnetic recording layer is formed on a surface of the magnetic-disk glass substrate according to claim 1 . 3. The magnetic-disk glass substrate according to claim 1 , wherein in addition to the arithmetic mean roughness for wavelength components of 10 to 50 nm of the surface of the main surfaces being 0.15 nm or less, the arithmetic mean roughness of the surface of the main surfaces is 0.15 nm or less when a wavelength band is not specified. 4. A magnetic disk in which at least a magnetic recording layer is formed on a surface of the magnetic-disk glass substrate according to claim 3 . 5. A magnetic-disk glass substrate for use as a magnetic disk, the magnetic-disk glass substrate comprising: a pair of main surfaces, an arithmetic mean roughness for wavelength components of 10 to 30 nm of a surface of the main surfaces being 0.12 nm or less when an area of 1 μm square is divided into sections of 512 by 512 and each section is measured using an atomic force microscope, there is no texture in a circumferential direction on the main surfaces, and the magnetic disk having a linear recording density of at least 2000 kbpi. 6. A magnetic disk in which at least a magnetic recording layer is formed on a surface of the magnetic-disk glass substrate according to claim 5 . 7. The magnetic-disk glass substrate according to claim 5 , wherein in addition to the arithmetic mean roughness for wavelength components of 10 to 30 nm of the surface of the main surfaces being 0.12 nm or less, the arithmetic mean roughness of the surface of the main surfaces is 0.15 nm or less when a wavelength band is not specified. 8. A magnetic disk in which at least a magnetic recording layer is formed on a surface of the magnetic-disk glass substrate according to claim 7 . 9. A magnetic-disk glass substrate for use as a magnetic disk, the magnetic-disk glass substrate comprising: a pair of main surfaces, an arithmetic mean roughness of a surface of the main surfaces when an area of 1 μm square is divided into sections of 512 by 512 and each section is measured using an atomic force microscope being 0.15 nm or less when a wavelength band is not specified, the arithmetic mean roughness of the surface of the main surfaces when wavelength components of 10 to 20 nm are extracted being 0.10 nm or less, there is no texture in a circumferential direction on the main surfaces, and the magnetic disk having a linear recording density of at least 2000 kbpi. 10. A magnetic disk in which at least a magnetic recording layer is formed on a surface of the magnetic-disk glass substrate according to claim 9 .
Assignees
Inventors
Classifications
by application of a magnetic field, e.g. magnetron sputtering {(C23C14/3457 takes precedence)} · CPC title
Magnetic recording media substrates · CPC title
- G11B5/7315Primary
Physics · mapped topic
Base layers {, i.e. all non-magnetic layers lying under a lowermost magnetic recording layer, e.g. including any non-magnetic layer in between a first magnetic recording layer and either an underlying substrate or a soft magnetic underlayer} · CPC title
- G11B5/73921Primary
Glass or ceramic substrates · CPC title
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- What does patent US9607647B2 cover?
- A magnetic-disk glass substrate of the present invention has a pair of main surfaces, and an arithmetic mean roughness (Ra) for wavelength components of 10 to 50 nm of the surface of the main surfaces is 0.15 nm or less.
- Who is the assignee on this patent?
- Hoya Corp
- What technology area does this patent fall under?
- Primary CPC classification G11B5/7315. Mapped technology areas include Physics.
- When was this patent published?
- Publication date Tue Mar 28 2017 00:00:00 GMT+0000 (Coordinated Universal Time) (B2). Legal status and post-grant events are not shown on this page.
- What related patents are in patentsdb?
- We list 1 related publication on this page (citations in our corpus or others sharing the same primary CPC).