Magnetic recording and reproducing device

Patent metadata

Field	Value
Publication number	US-11538494-B2
Application number	US-202117155536-A
Country	US
Kind code	B2
Filing date	Jan 22, 2021
Priority date	Jan 24, 2020
Publication date	Dec 27, 2022
Grant date	Dec 27, 2022

Abstract

In the magnetic recording and reproducing device, a distal end width of the first magnetic pole in the recording element is substantially the same as a distal end width of the second magnetic pole; the reproducing element width of the reproducing element is equal to or less than 0.8 μm; and in the magnetic recording medium, a number distribution A of equivalent circle diameters of a plurality of bright areas in a binarized image of a secondary electron image obtained by imaging a surface of the magnetic layer with a scanning electron microscope at an acceleration voltage of 5 kV, and a number distribution B of equivalent circle diameters of a plurality of dark areas in a binarized image of a secondary electron image obtained by imaging the surface of the magnetic layer with a scanning electron microscope at an acceleration voltage of 2 kV satisfy predetermined number distribution, respectively.

First claim

What is claimed is:

1. A magnetic recording and reproducing device comprising:
a magnetic recording medium;
a recording element; and
a reproducing element;
wherein the recording element is an inductive recording element including
a first magnetic pole which generates a magnetic field, and
a second magnetic pole which is separated from the first magnetic pole with a write gap interposed therebetween,
a distal end width of the first magnetic pole is substantially the same as a distal end width of the second magnetic pole,
a reproducing element width of the reproducing element is equal to or less than 0.8 μm,
the magnetic recording medium includes
a non-magnetic support, and a magnetic layer including a ferromagnetic powder,
a number distribution A of equivalent circle diameters of a plurality of bright areas in a binarized image of a secondary electron image obtained by imaging a surface of the magnetic layer with a scanning electron microscope at an acceleration voltage of 5 kV satisfies the following (1) to (3):
(1) the number of bright areas having an equivalent circle diameter of 1 nm to 50 nm is 1,000 to 30,000,
(2) the number of bright areas having an equivalent circle diameter of 51 nm to 100 nm is 1,000 to 25,000, and
(3) the number of bright areas having an equivalent circle diameter equal to or greater than 101 nm is 100 to 7,000, and

a number distribution B of equivalent circle diameters of a plurality of dark areas in a binarized image of a secondary electron image obtained by imaging the surface of the magnetic layer with a scanning electron microscope at an acceleration voltage of 2 kV satisfies the following (4) to (6):
(4) the number of dark areas having an equivalent circle diameter of 1 nm to 50 nm is 10 to 25,000,
(5) the number of dark areas having an equivalent circle diameter of 51 nm to 100 nm is 200 to 5,000, and
(6) the number of dark areas having an equivalent circle diameter equal to or greater than 101 nm is 0 to 200.

2. The magnetic recording and reproducing device according to claim 1 ,
wherein a total thickness of the magnetic recording medium is equal to or less than 5.3 μm.

3. The magnetic recording and reproducing device according to claim 1 ,
wherein the magnetic recording medium includes a non-magnetic layer including a non-magnetic powder between the non-magnetic support and the magnetic layer.

4. The magnetic recording and reproducing device according to claim 1 ,
wherein the magnetic recording medium includes 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.

5. The magnetic recording and reproducing device according to claim 1 ,
wherein the magnetic layer includes two or more kinds of non-magnetic powder.

6. The magnetic recording and reproducing device according to claim 5 ,
wherein the non-magnetic powder of the magnetic layer includes an alumina powder.

7. The magnetic recording and reproducing device according to claim 5 ,
wherein the non-magnetic powder of the magnetic layer includes carbon black.

8. The magnetic recording and reproducing device according to claim 1 ,
wherein the ferromagnetic powder is a hexagonal barium ferrite powder.

9. The magnetic recording and reproducing device according to claim 1 ,
wherein the ferromagnetic powder is a hexagonal strontium ferrite powder.

10. The magnetic recording and reproducing device according to claim 1 ,
wherein the ferromagnetic powder is an ε-iron oxide powder.

11. The magnetic recording and reproducing device according to claim 1 ,
wherein the magnetic recording medium is a magnetic tape.

Assignees

• Fujifilm Corp

Inventors

• Musha Atsushi
• Matsuyama So
• Kasada Norihito

Classifications

• G11B5/00826

  comprising a plurality of single poles or gaps or groups thereof operative at the same time · CPC title

• G11B5/70678 Primary

  Ferrites · CPC title

• G11B5/714

  characterised by the dimension of the magnetic particles · CPC title

• G11B5/7356 Primary

  comprising non-magnetic particles in the back layer, e.g. particles of TiO2, ZnO or SiO2 · CPC title

• G11B5/7085

  non-magnetic abrasive particles · CPC title