Magnetic tape with specific servo pattern edge shape and magnetic tape device using same

• US 9,773,519 B2
• Filed: 12/22/2016
• Issued: 09/26/2017
• Est. Priority Date: 12/25/2015
• Status: Active Grant

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Inventors: Kasada, Norihito, Kaneko, Tetsuya
• Primary Examiner(s): EVANS, JEFFERSON A
• Application Number:
  US15/388,864
• Publication Number:
  US 20170186460A1
• Time in Patent Office: 278 Days
• Field of Search: 360134
• CPC Class Codes: G11B 5/584 for track following on tapes
• CPC Class Codes: G11B 5/5928 Longitudinal tracks
• CPC Class Codes: G11B 5/70 on a base layer
• CPC Class Codes: G11B 5/78 Tape carriers

Abstract

The magnetic tape has a magnetic layer containing ferromagnetic powder and binder on a nonmagnetic support, wherein the coercive force measured in the longitudinal direction of the magnetic tape is less than or equal to 167 kA/m, a timing-based servo pattern is present on the magnetic layer, and the edge shape specified by observing the timing-based servo pattern with a magnetic force microscope is a shape in which the difference between the value L_99.9 of the 99.9% cumulative distribution function of the width of misalignment from the ideal shape in the longitudinal direction of the magnetic tape and the value L_0.1 of the 0.1% cumulative distribution function, L_99.9−L_0.1, is less than or equal to 180 nm.

Claims

1. A magnetic tape,

which comprises a magnetic layer comprising ferromagnetic powder and binder on a nonmagnetic support, wherein

a coercive force measured in a longitudinal direction of the magnetic tape is less than or equal to 167 kA/m;

a timing-based servo pattern is present on the magnetic layer; and

an edge shape of a portion of a servo pattern specified by observing the timing-based servo pattern with a magnetic force microscope is a shape in which a difference between a value L_99.9 of 99.9% cumulative distribution function of a width of misalignment from an ideal shape in the longitudinal direction of the magnetic tape and a value L_0.1 of 0.1% cumulative distribution function, L_99.9−

L_0.1, is less than or equal to 180 nm.

2. The magnetic tape according to claim 1,

wherein the timing-based servo pattern is a linear servo pattern continuously or discontinuously running from one side to the other in a direction of width of the magnetic tape.

3. The magnetic tape according to claim 2,

wherein the timing-based servo pattern is a linear servo pattern inclined by an angle θ

relative to the direction of width of the magnetic tape and running continuously from one side to the other side in the direction of width of the magnetic tape, and

the ideal shape is a linear shape running in a direction of angle θ

.

4. The magnetic tape according to claim 3,

wherein a Δ

SFD calculated with Equation 1;

Δ

SFD=SFD<sub>25°

C.</sub>−

SFD<sub>−

190°

C.</sub> 

 

Equation 1

in the longitudinal direction of the magnetic tape is less than or equal to 0.50, and in Equation 1, SFD<sub>25°

C.</sub> denotes a switching field distribution measured in the longitudinal direction of the magnetic tape in an environment with a temperature of 25°

C., and SFD<sub>−

190°

C.</sub> denotes a switching field distribution measured in the longitudinal direction of the magnetic tape in an environment with a temperature of −

190°

C.

5. The magnetic tape according to claim 4,

wherein the Δ

SFD is greater than or equal to 0.03 but less than or equal to 0.50.

6. The magnetic tape according to claim 2,

wherein a Δ

SFD calculated with Equation 1;

Δ

SFD=SFD<sub>25°

C.</sub>−

SFD<sub>−

190°

C.</sub> 

 

Equation 1

in the longitudinal direction of the magnetic tape is less than or equal to 0.50, and in Equation 1, SFD<sub>25°

C.</sub> denotes a switching field distribution measured in the longitudinal direction of the magnetic tape in an environment with a temperature of 25°

C., and SFD<sub>−

190°

C.</sub> denotes a switching field distribution measured in the longitudinal direction of the magnetic tape in an environment with a temperature of −

190°

C.

7. The magnetic tape according to claim 6,

wherein the Δ

SFD is greater than or equal to 0.03 but less than or equal to 0.50.

8. The magnetic tape according to claim 1,

wherein a Δ

SFD calculated with Equation 1;

Δ

SFD=SFD<sub>25°

C.</sub>−

SFD<sub>−

190°

C.</sub> 

 

Equation 1

in the longitudinal direction of the magnetic tape is less than or equal to 0.50, and in Equation 1, SFD<sub>25°

C.</sub> denotes a switching field distribution measured in the longitudinal direction of the magnetic tape in an environment with a temperature of 25°

C., and SFD<sub>−

190°

C.</sub> denotes a switching field distribution measured in the longitudinal direction of the magnetic tape in an environment with a temperature of −

190°

C.

9. The magnetic tape according to claim 8,

wherein the Δ

SFD is greater than or equal to 0.03 but less than or equal to 0.50.

10. The magnetic tape according to claim 1,

wherein the coercive force is greater than or equal to 119 kA/m but less than or equal to 167 kA/m.

11. A magnetic tape device,

which comprises a magnetic tape, a magnetic head, and a servo head, and

wherein the magnetic tape is a magnetic tape, which comprises a magnetic layer comprising ferromagnetic powder and binder on a nonmagnetic support, wherein

a coercive force measured in a longitudinal direction of the magnetic tape is less than or equal to 167 kA/m;

a timing-based servo pattern is present on the magnetic layer; and

an edge shape of a portion of a servo pattern specified by observing the timing-based servo pattern with a magnetic force microscope is a shape in which a difference between a value L_99.9 of 99.9% cumulative distribution function of a width of misalignment from an ideal shape in the longitudinal direction of the magnetic tape and a value L_0.1 of 0.1% cumulative distribution function, L_99.9−

L_0.1, is less than or equal to 180 nm.

12. The magnetic tape device according to claim 11,

wherein the timing-based servo pattern is a linear servo pattern continuously or discontinuously running from one side to the other in a direction of width of the magnetic tape.

13. The magnetic tape device according to claim 12,

wherein the timing-based servo pattern is a linear servo pattern inclined by an angle θ

relative to the direction of width of the magnetic tape and running continuously from one side to the other side in the direction of width of the magnetic tape, and

the ideal shape is a linear shape running in a direction of angle θ

.

14. The magnetic tape device according to claim 13,

wherein a Δ

SFD calculated with Equation 1;

Δ

SFD=SFD<sub>25°

C.</sub>−

SFD<sub>−

190°

C.</sub> 

 

Equation 1

in the longitudinal direction of the magnetic tape is less than or equal to 0.50, and in Equation 1, SFD<sub>25°

C.</sub>denotes a switching field distribution measured in the longitudinal direction of the magnetic tape in an environment with a temperature of 25°

C., and SFD<sub>−

190°

C.</sub> denotes a switching field distribution measured in the longitudinal direction of the magnetic tape in an environment with a temperature of −

190°

C.

15. The magnetic tape device according to claim 14,

wherein the Δ

SFD is greater than or equal to 0.03 but less than or equal to 0.50.

16. The magnetic tape device according to claim 12,

wherein a Δ

SFD calculated with Equation 1;

Δ

SFD=SFD<sub>25°

C.</sub>−

SFD<sub>−

190°

C.</sub> 

 

Equation 1

in the longitudinal direction of the magnetic tape is less than or equal to 0.50, and in Equation 1, SFD<sub>25°

C.</sub> denotes a switching field distribution measured in the longitudinal direction of the magnetic tape in an environment with a temperature of 25°

C., and SFD<sub>−

190°

C.</sub> denotes a switching field distribution measured in the longitudinal direction of the magnetic tape in an environment with a temperature of −

190°

C.

17. The magnetic tape device according to claim 16,

wherein the Δ

SFD is greater than or equal to 0.03 but less than or equal to 0.50.

18. The magnetic tape device according to claim 11,

wherein a Δ

SFD calculated with Equation 1;

Δ

SFD=SFD<sub>25°

C.</sub>−

SFD<sub>−

190°

C.</sub> 

 

Equation 1

in the longitudinal direction of the magnetic tape is less than or equal to 0.50, and in Equation 1, SFD<sub>25°

C.</sub> denotes a switching field distribution measured in the longitudinal direction of the magnetic tape in an environment with a temperature of 25°

C., and SFD<sub>−

190°

C.</sub> denotes a switching field distribution measured in the longitudinal direction of the magnetic tape in an environment with a temperature of −

190°

C.

19. The magnetic tape device according to claim 18,

wherein the Δ

SFD is greater than or equal to 0.03 but less than or equal to 0.50.

20. The magnetic tape device according to claim 11,

wherein the coercive force is greater than or equal to 119 kA/m but less than or equal to 167 kA/m.