Magnetic recording medium and magnetic recording and reproducing apparatus

Patent metadata

Field	Value
Publication number	US-11074935-B2
Application number	US-202016801371-A
Country	US
Kind code	B2
Filing date	Feb 26, 2020
Priority date	Feb 27, 2019
Publication date	Jul 27, 2021
Grant date	Jul 27, 2021

Abstract

The magnetic recording medium includes: a non-magnetic support; and a magnetic layer including ferromagnetic powder and a binding agent, wherein the ferromagnetic powder is selected from the group consisting of hexagonal strontium ferrite powder and ε-iron oxide powder, and has an average particle size of 5 nm or more and 20 nm or less, wherein the magnetic layer has a servo pattern, and wherein an average area Sdc of magnetic clusters of the magnetic recording medium in a DC demagnetization state, measured by a magnetic force microscope is 0.2×10 4 nm 2 or more and less than 5.0×10 4 nm 2 .

First claim

What is claimed is:

1. A magnetic recording medium comprising:
a non-magnetic support; and
a magnetic layer including ferromagnetic powder and a binding agent,
wherein the ferromagnetic powder is selected from the group consisting of hexagonal strontium ferrite powder and ε-iron oxide powder, and has an average particle size of 5 nm or more and 20 nm or less,
wherein the magnetic layer has a servo pattern, and
wherein an average area Sdc of magnetic clusters of the magnetic recording medium in a DC demagnetization state, measured by a magnetic force microscope is 0.2×10 4 nm 2 or more and less than 5.0×10 4 nm 2 .

2. The magnetic recording medium according to claim 1 ,
wherein a ratio Sdc/Sac of the Sdc to an average area Sac of magnetic clusters of the magnetic recording medium in an AC demagnetization state, measured by a magnetic force microscope is 0.8 or more and 2.0 or less.

3. The magnetic recording medium according to claim 1 ,
wherein the magnetic recording medium is a magnetic tape,
wherein the servo pattern is a timing-based servo pattern, and
wherein an edge shape of the timing-based servo pattern, specified by magnetic force microscopy is a shape in which a difference L 99.9 −L 0.1 between a value L 99.9 of a cumulative distribution function of 99.9% and a value L 0.1 of a cumulative distribution function of 0.1% in a position deviation width from an ideal shape of the magnetic tape in a longitudinal direction is 180 nm or less.

4. The magnetic recording medium according to claim 2 ,
wherein the magnetic recording medium is a magnetic tape,
wherein the servo pattern is a timing-based servo pattern, and
wherein an edge shape of the timing-based servo pattern, specified by magnetic force microscopy is a shape in which a difference L 99.9 −L 0.1 between a value L 99.9 of a cumulative distribution function of 99.9% and a value L 0.1 of a cumulative distribution function of 0.1% in a position deviation width from an ideal shape of the magnetic tape in a longitudinal direction is 180 nm or less.

5. The magnetic recording medium according to claim 1 ,
wherein the Sdc is 0.2×10 4 nm 2 or more and less than 0.3×10 4 nm 2 .

6. The magnetic recording medium according to claim 2 ,
wherein the Sdc is 0.2×10 4 nm 2 or more and less than 0.3×10 4 nm 2 .

7. The magnetic recording medium according to claim 3 ,
wherein the Sdc is 0.2×10 4 nm 2 or more and less than 0.3×10 4 nm 2 .

8. The magnetic recording medium according to claim 4 ,
wherein the Sdc is 0.2×10 4 nm 2 or more and less than 0.3×10 4 nm 2 .

9. A magnetic recording and reproducing apparatus comprising:
the magnetic recording medium according to claim 1 ; and
a magnetic head.

10. The magnetic recording and reproducing apparatus according to claim 9 ,
wherein a ratio Sdc/Sac of the Sdc to an average area Sac of magnetic clusters of the magnetic recording medium in an AC demagnetization state, measured by a magnetic force microscope is 0.8 or more and 2.0 or less.

11. The magnetic recording and reproducing apparatus according to claim 9 ,
wherein the magnetic recording medium is a magnetic tape,
wherein the servo pattern is a timing-based servo pattern, and
wherein an edge shape of the timing-based servo pattern, specified by magnetic force microscopy is a shape in which a difference L 99.9 −L 0.1 between a value L 99.9 of a cumulative distribution function of 99.9% and a value L 0.1 of a cumulative distribution function of 0.1% in a position deviation width from an ideal shape of the magnetic tape in a longitudinal direction is 180 nm or less.

12. The magnetic recording and reproducing apparatus according to claim 10 ,
wherein the magnetic recording medium is a magnetic tape,
wherein the servo pattern is a timing-based servo pattern, and
wherein an edge shape of the timing-based servo pattern, specified by magnetic force microscopy is a shape in which a difference L 99.9 −L 0.1 between a value L 99.9 of a cumulative distribution function of 99.9% and a value L 0.1 of a cumulative distribution function of 0.1% in a position deviation width from an ideal shape of the magnetic tape in a longitudinal direction is 180 nm or less.

13. The magnetic recording and reproducing apparatus according to claim 9 ,
wherein the Sdc is 0.2×10 4 nm 2 or more and less than 0.3×10 4 nm 2 .

14. The magnetic recording reproducing apparatus according to claim 10 ,
wherein the Sdc is 0.2×10 4 nm 2 or more and less than 0.3×10 4 nm 2 .

15. The magnetic recording and reproducing apparatus according to claim 11 ,
wherein the Sdc is 0.2×10 4 nm 2 or more and less than 0.3×10 4 nm 2 .

16. The magnetic recording and reproducing apparatus according to claim 12 ,
wherein the Sdc is 0.2×10 4 nm 2 or more and less than 0.3×10 4 nm 2 .

Assignees

• Fujifilm Corp

Inventors

• Naoi Kenji

Classifications

• G11B5/5926

  recorded in separate tracks, e.g. servo tracks · CPC title

• G11B5/735

  characterised by the back layer {(magnetic recording media substrates G11B5/739)} · CPC title

• G11B5/70678 Primary

  Ferrites · CPC title

• G11B5/584

  for track following on tapes · CPC title

• G11B5/00817

  on longitudinal tracks only, e.g. for serpentine format recording · CPC title