ϵ-iron oxide type ferromagnetic powder and magnetic recording medium
US-11090716-B2 · Aug 17, 2021 · US
Magnetic recording medium and magnetic recording and reproducing device
US11501798B2 · US · B2
| Field | Value |
|---|---|
| Publication number | US-11501798-B2 |
| Application number | US-202016830980-A |
| Country | US |
| Kind code | B2 |
| Filing date | Mar 26, 2020 |
| Priority date | Mar 28, 2019 |
| Publication date | Nov 15, 2022 |
| Grant date | Nov 15, 2022 |
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Abstract
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The magnetic recording medium includes a non-magnetic support; and a magnetic layer including a ferromagnetic powder, in which the ferromagnetic powder is a ferromagnetic powder selected from the group consisting of a hexagonal strontium ferrite powder and an ε-iron oxide powder, the number of recesses having a depth which is ⅓ or more of a minimum recording bit length existing on a surface of the magnetic layer is less than 10/10,000 μm 2 , and a ratio d/t mag of a value d which is ⅓ of the minimum recording bit length to a thickness t mag of the magnetic layer is 0.15 to 0.50.
First claim
Opening claim text (preview).
What is claimed is: 1. A magnetic recording medium comprising: a non-magnetic support; and a magnetic layer including a ferromagnetic powder, wherein the ferromagnetic powder is a ferromagnetic powder selected from the group consisting of a hexagonal strontium ferrite powder and an ε-iron oxide powder, the number of recesses having a depth which is ⅓ or more of a minimum recording bit length existing on a surface of the magnetic layer is less than 10/10,000 μm 2 , a ratio d/t mag of a value d which is ⅓ of the minimum recording bit length to a thickness t mag of the magnetic layer is 0.20 to 0.50, and the anisotropy magnetic field Hk of the magnetic layer is equal to or greater than 18 kOe. 2. The magnetic recording medium according to claim 1 , further comprising: a non-magnetic layer including a non-magnetic powder between the non-magnetic support and the magnetic layer. 3. The magnetic recording medium according to claim 1 further comprising: a back coating layer including a non-magnetic powder on a surface of the non-magnetic support opposite to a surface provided with the magnetic layer. 4. The magnetic recording medium according to claim 1 , wherein the number of recesses is 1/10,000 μm 2 to 9/10,000 μm 2 . 5. The magnetic recording medium according to claim 1 , which is a magnetic tape. 6. A magnetic recording and reproducing device comprising: the magnetic recording medium according to claim 1 ; and a magnetic head. 7. The magnetic recording and reproducing device according to claim 6 , wherein a minimum recording bit length of the magnetic recording and reproducing device is 10 nm to 40 nm. 8. The magnetic recording and reproducing device according to claim 6 , wherein the magnetic recording medium further comprises a non-magnetic layer including a non-magnetic powder between the non-magnetic support and the magnetic layer. 9. The magnetic recording and reproducing device according to claim 6 , wherein the magnetic recording medium further comprises a back coating layer including a non-magnetic powder on a surface of the non-magnetic support opposite to a surface provided with the magnetic layer. 10. The magnetic recording and reproducing device according to claim 6 , wherein the number of recesses is 1/10,000 μm 2 to 9/10,000 μm 2 . 11. The magnetic recording and reproducing device according to claim 6 , wherein the magnetic recording medium is a magnetic tape.
Assignees
Inventors
Classifications
- G11B5/70678Primary
Ferrites · CPC title
characterised by the surface treatment or coating of magnetic particles · CPC title
Base layer characterised by composition or structure · CPC title
- G11B5/70642Primary
iron oxides · CPC title
on longitudinal tracks only, e.g. for serpentine format recording · CPC title
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Frequently asked questions
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- What does patent US11501798B2 cover?
- The magnetic recording medium includes a non-magnetic support; and a magnetic layer including a ferromagnetic powder, in which the ferromagnetic powder is a ferromagnetic powder selected from the group consisting of a hexagonal strontium ferrite powder and an ε-iron oxide powder, the number of recesses having a depth which is ⅓ or more of a minimum recording bit length existing on a surface of …
- Who is the assignee on this patent?
- Fujifilm Corp
- What technology area does this patent fall under?
- Primary CPC classification G11B5/70678. Mapped technology areas include Physics.
- When was this patent published?
- Publication date Tue Nov 15 2022 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).