Magnetic-disk substrate, magnetic disk, and magnetic-disk drive device
US-11094345-B2 · Aug 17, 2021 · US
Magnetic-disk substrate, magnetic disk, and magnetic-disk drive device
US11682424B2 · US · B2
| Field | Value |
|---|---|
| Publication number | US-11682424-B2 |
| Application number | US-202117385787-A |
| Country | US |
| Kind code | B2 |
| Filing date | Jul 26, 2021 |
| Priority date | Mar 31, 2015 |
| Publication date | Jun 20, 2023 |
| Grant date | Jun 20, 2023 |
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- Title
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Abstract
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A magnetic-disk substrate has a pair of main surfaces, and an arithmetic average roughness Ra of each of the main surfaces is 0.11 nm or less. The arithmetic average roughness Ra is a value obtained through measurement using an atomic force microscope provided with a probe having a probe tip provided with a carbon nanofiber rod-shaped member. The magnetic-disk substrate is made of glass or aluminum alloy.
First claim
Opening claim text (preview).
What is claimed is: 1. A magnetic-disk substrate, comprising: a pair of main surfaces, in surface unevenness of the main surfaces, an average area of regions occupied by a plurality of protrusions having a height of 0.2 nm or more from an average plane of the surface unevenness being 13 nm 2 /protrusion or less, and the surface unevenness of the main surfaces being a value obtained through measurement using an atomic force microscope provided with a probe having a probe tip provided with a carbon nanofiber rod-shaped member. 2. The magnetic-disk substrate according to claim 1 , wherein an arithmetic average roughness Ra of the main surfaces is 0.15 nm or less. 3. The magnetic-disk substrate according to claim 1 , wherein the magnetic-disk substrate has a nominal 3.5-inch size. 4. The magnetic-disk substrate according to claim 1 , wherein the magnetic-disk substrate is a magnetic-disk substrate for energy-assisted magnetic recording. 5. The magnetic-disk substrate according to claim 1 , wherein the magnetic-disk substrate is a magnetic-disk glass substrate made of glass, and a glass transition point of glass of the magnetic-disk glass substrate is 600° C. or more. 6. The magnetic-disk substrate according to claim 1 , wherein a difference between an average area of regions occupied by a plurality of protrusions having a height of 0.1 nm or more from the average plane of the surface unevenness and the average area of regions occupied by the plurality of protrusions having the height of 0.2 nm or more from the average plane of the surface unevenness is 13 nm 2 /protrusion or less. 7. A magnetic disk, wherein at least a magnetic film is formed on a surface of the magnetic-disk substrate according to claim 1 . 8. A magnetic disk, wherein at least a magnetic film is formed on a surface of the magnetic-disk substrate according to claim 2 . 9. A magnetic disk, wherein at least a magnetic film is formed on a surface of the magnetic-disk substrate according to claim 3 . 10. A magnetic disk, wherein at least a magnetic film is formed on a surface of the magnetic-disk substrate according to claim 4 . 11. A magnetic disk, wherein at least a magnetic film is formed on a surface of the magnetic-disk substrate according to claim 5 . 12. A magnetic disk, wherein at least a magnetic film is formed on a surface of the magnetic-disk substrate according to claim 6 . 13. A magnetic-disk substrate, comprising: a pair of main surfaces, in surface unevenness of the main surfaces, a difference between an average area of regions occupied by a plurality of protrusions having a height of 0.1 nm or more from an average plane of the surface unevenness and an average area of regions occupied by a plurality of protrusions having a height of 0.2 nm or more from the average plane of the surface unevenness being 13 nm 2 /protrusion or less, and the surface unevenness of the main surfaces being a value obtained through measurement using an atomic force microscope provided with a probe having a probe tip provided with a carbon nanofiber rod-shaped member. 14. The magnetic-disk substrate according to claim 13 , wherein an arithmetic average roughness Ra of the main surfaces is 0.15 nm or less. 15. The magnetic-disk substrate according to claim 13 , wherein the magnetic-disk substrate has a nominal 3.5-inch size. 16. The magnetic-disk substrate according to claim 13 , wherein the magnetic-disk substrate is a magnetic-disk substrate for energy-assisted magnetic recording. 17. The magnetic-disk substrate according to claim 13 , wherein the magnetic-disk substrate is a magnetic-disk glass substrate made of glass, and a glass transition point of glass of the magnetic-disk glass substrate is 600° C. or more. 18. A magnetic disk, wherein at least a magnetic film is formed on a surface of the magnetic-disk substrate according to claim 13 . 19. A magnetic disk, wherein at least a magnetic film is formed on a surface of the magnetic-disk substrate according to claim 14 . 20. A magnetic disk, wherein at least a magnetic film is formed on a surface of the magnetic-disk substrate according to claim 15 .
Assignees
Inventors
Classifications
Aluminium or titanium elemental or alloy substrates · CPC title
Glass or ceramic substrates · CPC title
manufacturing base layers · CPC title
Composites or coated substrates · CPC title
- G11B5/84Primary
Processes or apparatus specially adapted for manufacturing record carriers · CPC title
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Frequently asked questions
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- What does patent US11682424B2 cover?
- A magnetic-disk substrate has a pair of main surfaces, and an arithmetic average roughness Ra of each of the main surfaces is 0.11 nm or less. The arithmetic average roughness Ra is a value obtained through measurement using an atomic force microscope provided with a probe having a probe tip provided with a carbon nanofiber rod-shaped member. The magnetic-disk substrate is made of glass or alum…
- Who is the assignee on this patent?
- Hoya Corp
- What technology area does this patent fall under?
- Primary CPC classification G11B5/84. Mapped technology areas include Physics.
- When was this patent published?
- Publication date Tue Jun 20 2023 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 6 related publications on this page (citations in our corpus or others sharing the same primary CPC).