Magnetic tape with particular refractive index characteristics, magnetic tape cartridge, and magnetic tape apparatus

Patent metadata

Field	Value
Publication number	US-11423935-B2
Application number	US-202117328620-A
Country	US
Kind code	B2
Filing date	May 24, 2021
Priority date	Dec 28, 2018
Publication date	Aug 23, 2022
Grant date	Aug 23, 2022

Abstract

Provided are a magnetic tape including: a non-magnetic support; and a magnetic layer including ferromagnetic powder and a binding agent on the non-magnetic support, in which a total thickness of the magnetic tape is equal to or smaller than 5.30 μm, the magnetic layer has a servo pattern, a center line average surface roughness Ra measured on a surface of the magnetic layer is equal to or smaller than 1.8 nm, and an absolute value ΔN of a difference between a refractive index Nxy of the magnetic layer, measured in an in-plane direction and a refractive index Nz of the magnetic layer, measured in a thickness direction is 0.25 to 0.40, a magnetic tape cartridge and a magnetic tape apparatus including this magnetic tape, a magnetic tape cartridge and a magnetic tape apparatus including this magnetic tape.

First claim

What is claimed is:

1. A magnetic tape comprising:
a non-magnetic support;
a magnetic layer including ferromagnetic powder on the non-magnetic support; and
a non-magnetic layer including non-magnetic powder between the non-magnetic support and the magnetic layer,
wherein a total thickness of the magnetic tape is equal to or smaller than 5.30 μm,
a thickness of the non-magnetic layer is 0.10 nm to 1.50 μm,
the magnetic layer has a servo pattern,
a center line average surface roughness Ra measured on a surface of the magnetic layer is equal to or smaller than 1.8 nm, and
an absolute value ΔN of a difference between a refractive index Nxy of the magnetic layer, measured in an in-plane direction and a refractive index Nz of the magnetic layer, measured in a thickness direction is 0.25 to 0.40.

2. The magnetic tape according to claim 1 ,
wherein a difference Nxy−Nz between the refractive index Nxy and the refractive index Nz is 0.25 to 0.40.

3. The magnetic tape according to claim 1 ,
wherein the total thickness of the magnetic tape is 3.00 μm to 5.30 μm.

4. The magnetic tape according to claim 1 , further comprising:
a back coating layer including non-magnetic powder on a surface of the non-magnetic support opposite to a surface provided with the magnetic layer.

5. The magnetic tape according to claim 1 ,
wherein the center line average surface roughness Ra measured on the surface of the magnetic layer is 1.2 nm to 1.8 nm.

6. The magnetic tape according to claim 1 ,
wherein the servo pattern is a timing-based servo pattern.

7. The magnetic tape according to claim 1 ,
wherein the thickness of the non-magnetic layer is 0.10 μm to 1.00 μm.

8. The magnetic tape according to claim 1 ,
wherein the thickness of the non-magnetic layer is 0.10 μm to 0.70 μm.

9. The magnetic tape according to claim 1 ,
wherein the thickness of the non-magnetic layer is 0.10 μm to 0.50 μm.

10. A magnetic tape cartridge comprising:
a magnetic tape, which comprises:
a non-magnetic support;
a magnetic layer including ferromagnetic powder on the non-magnetic support; and
a non-magnetic layer including non-magnetic powder between the non-magnetic support and the magnetic layer,
wherein a total thickness of the magnetic tape is equal to or smaller than 5.30 μm,
a thickness of the non-magnetic layer is 0.10 μm to 1.50 μm,
the magnetic layer has a servo pattern,
a center line average surface roughness Ra measured on a surface of the magnetic layer is equal to or smaller than 1.8 nm, and
an absolute value ΔN of a difference between a refractive index Nxy of the magnetic layer, measured in an in-plane direction and a refractive index Nz of the magnetic layer, measured in a thickness direction is 0.25 to 0.40.

11. The magnetic tape cartridge according to claim 10 ,
wherein a difference Nxy−Nz between the refractive index Nxy and the refractive index Nz is 0.25 to 0.40.

12. The magnetic tape cartridge according to claim 10 ,
wherein the magnetic tape further comprises:
a back coating layer including non-magnetic powder and on a surface of the non-magnetic support opposite to a surface provided with the magnetic layer.

13. The magnetic tape cartridge according to claim 10 ,
wherein the thickness of the non-magnetic layer is 0.10 μm to 1.00 μm.

14. The magnetic tape cartridge according to claim 10 ,
wherein the thickness of the non-magnetic layer is 0.10 μm to 0.70 μm.

15. The magnetic tape cartridge according to claim 10 ,
wherein the thickness of the non-magnetic layer is 0.10 μm to 0.50 μm.

16. A magnetic tape apparatus comprising:
a magnetic head; and
a magnetic tape, which comprises:
a non-magnetic support;
a magnetic layer including ferromagnetic powder and on the non-magnetic support; and
a non-magnetic layer including non-magnetic powder between the non-magnetic support and the magnetic layer,
wherein a total thickness of the magnetic tape is equal to or smaller than 5.30 μm,
a thickness of the non-magnetic layer is 0.10 μm to 1.50 μm,
the magnetic layer has a servo pattern,
a center line average surface roughness Ra measured on a surface of the magnetic layer is equal to or smaller than 1.8 nm, and
an absolute value ΔN of a difference between a refractive index Nxy of the magnetic layer, measured in an in-plane direction and a refractive index Nz of the magnetic layer, measured in a thickness direction is 0.25 to 0.40.

17. The magnetic tape apparatus according to claim 16 ,
wherein a difference Nxy−Nz between the refractive index Nxy and the refractive index Nz is 0.25 to 0.40.

18. The magnetic tape apparatus according to claim 16 ,
wherein the thickness of the non-magnetic layer is 0.10 μm to 1.00 μm.

19. The magnetic tape apparatus according to claim 16 ,
wherein the thickness of the non-magnetic layer is 0.10 μm to 0.70 μm.

20. The magnetic tape apparatus according to claim 16 ,
wherein the thickness of the non-magnetic layer is 0.10 μm to 0.50 μm.

Assignees

• Fujifilm Corp

Inventors

• Kasada Norihito

Classifications

• G11B5/70678

  Ferrites · CPC title

• G11B5/7358 Primary

  specially adapted for achieving a specific property, e.g. average roughness [Ra] · CPC title

• G11B5/70689

  Magnetite · CPC title

• G11B5/70 Primary

  on a base layer · CPC title

• G11B23/107

  using one reel or core, one end of the record carrier coming out of the magazine or cassette · CPC title