MAGNETIC TAPE DEVICE AND HEAD TRACKING SERVO METHOD

• US 20190096437A1
• Filed: 11/08/2018
• Published: 03/28/2019
• Est. Priority Date: 03/29/2017
• Status: Active Grant

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Inventors: OZAWA, Eiki, KASADA, Norihito
• Granted Patent: US 10,497,386 B2
• Time in Patent Office: Days
• CPC Class Codes: G11B 5/00813 magnetic tapes
• CPC Class Codes: G11B 5/3909 Arrangements using a magnetic tunnel junction
• CPC Class Codes: G11B 5/584 for track following on tapes
• CPC Class Codes: G11B 5/70 on a base layer
• CPC Class Codes: G11B 5/70615 containing Fe metal or alloys G11B5/70621 takes precedence
• CPC Class Codes: G11B 5/714 characterised by the dimension of the magnetic particles

Abstract

The magnetic tape device includes a TMR head (servo head); and a magnetic tape, in which a magnetic layer of the magnetic tape includes fatty acid ester, Ra measured regarding a surface of the magnetic layer is equal to or smaller than 2.0 nm, full widths at half maximum of spacing distribution measured by optical interferometry regarding a surface of the magnetic layer before and after performing a vacuum heating with respect to the magnetic tape are greater than 0 nm and equal to or smaller than 7.0 nm, a difference between spacings before and after the vacuum heating is greater than 0 nm and equal to or smaller than 8.0 nm, and ΔSFD (=SFD_{25° C.}−SFD_{−#° C.}) in a longitudinal direction of the magnetic tape is equal to or smaller than 0.50.

Claims

1. A magnetic tape device comprising:

a magnetic tape; and

a servo head,

wherein the servo head is a magnetic head including a tunnel magnetoresistance effect type element as a servo pattern reading element,

the magnetic tape includes a non-magnetic support, and a magnetic layer including ferromagnetic powder, a binding agent, and fatty acid ester on the non-magnetic support,

the magnetic layer includes a servo pattern,

a full width at half maximum of spacing distribution measured by optical interferometry regarding the surface of the magnetic layer before performing a vacuum heating with respect to the magnetic tape is greater than 0 nm and equal to or smaller than 7.0 nm,

a full width at half maximum of spacing distribution measured by optical interferometry regarding the surface of the magnetic layer after performing the vacuum heating with respect to the magnetic tape is greater than 0 nm and equal to or smaller than 7.0 nm,

a difference S_after−

S_before between a spacing S_after measured by optical interferometry regarding the surface of the magnetic layer after performing the vacuum heating with respect to the magnetic tape and a spacing S_before measured by optical interferometry regarding the surface of the magnetic layer before performing the vacuum heating with respect to the magnetic tape is greater than 0 nm and equal to or smaller than 8.0 nm, and

Δ

SFD in a longitudinal direction of the magnetic tape calculated by Expression 1 is equal to or smaller than 0.50,

Δ

SFD=SFD<sub>25°

C.</sub>−

SFD<sub>−

190°

C.</sub> 

 

Expression 1

in Expression 1, the SFD<sub>25°

C.</sub> is a switching field distribution SFD measured in a longitudinal direction of the magnetic tape at a temperature of 25°

C., and the SFD<sub>−

190°

C.</sub> is a switching field distribution SFD measured in a longitudinal direction of the magnetic tape at a temperature of −

190°

C.

2. The magnetic tape device according to claim 1,

wherein the full width at half maximum of spacing distribution measured by optical interferometry regarding the surface of the magnetic layer before performing the vacuum heating with respect to the magnetic tape is 3.0 nm to 7.0 nm.

3. The magnetic tape device according to claim 1,

wherein the full width at half maximum of spacing distribution measured by optical interferometry regarding the surface of the magnetic layer after performing the vacuum heating with respect to the magnetic tape is 3.0 nm to 7.0 nm.

4. The magnetic tape device according to claim 1,

wherein the difference S_after−

S_before is 2.0 nm to 8.0 nm.

5. The magnetic tape device according to claim 1,

wherein the Δ

SFD is 0.03 to 0.50.

6. The magnetic tape device according to claim 1,

wherein the magnetic tape includes a non-magnetic layer including non-magnetic powder and a binding agent between the non-magnetic support and the magnetic layer.

7. A head tracking servo method comprising:

reading a servo pattern of a magnetic layer of a magnetic tape by a servo head in a magnetic tape device,

wherein the servo head is a magnetic head including a tunnel magnetoresistance effect type element as a servo pattern reading element,

the magnetic tape includes a non-magnetic support, and a magnetic layer including ferromagnetic powder, a binding agent, and fatty acid ester on the non-magnetic support, the magnetic layer includes the servo pattern,

a full width at half maximum of spacing distribution measured by optical interferometry regarding the surface of the magnetic layer before performing a vacuum heating with respect to the magnetic tape is greater than 0 nm and equal to or smaller than 7.0 nm,

a full width at half maximum of spacing distribution measured by optical interferometry regarding the surface of the magnetic layer after performing the vacuum heating with respect to the magnetic tape is greater than 0 nm and equal to or smaller than 7.0 nm,

a difference S_after−

S_before between a spacing S_after measured by optical interferometry regarding the surface of the magnetic layer after performing the vacuum heating with respect to the magnetic tape and a spacing S_before measured by optical interferometry regarding the surface of the magnetic layer before performing the vacuum heating with respect to the magnetic tape is greater than 0 nm and equal to or smaller than 8.0 nm, and

Δ

SFD in a longitudinal direction of the magnetic tape calculated by Expression 1 is equal to or smaller than 0.50,

Δ

SFD=SFD<sub>25°

C.</sub>−

SFD<sub>−

190°

C.</sub> 

 

Expression 1

in Expression 1, the SFD<sub>25°

C.</sub> is a switching field distribution SFD measured in a longitudinal direction of the magnetic tape at a temperature of 25°

C., and the SFD<sub>−

190°

C.</sub> is a switching field distribution SFD measured in a longitudinal direction of the magnetic tape at a temperature of −

190°

C.

8. The head tracking servo method according to claim 7,

wherein the full width at half maximum of spacing distribution measured by optical interferometry regarding the surface of the magnetic layer before performing the vacuum heating with respect to the magnetic tape is 3.0 nm to 7.0 nm.

9. The head tracking servo method according to claim 7,

wherein the full width at half maximum of spacing distribution measured by optical interferometry regarding the surface of the magnetic layer after performing the vacuum heating with respect to the magnetic tape is 3.0 nm to 7.0 nm.

10. The head tracking servo method according to claim 7,

wherein the difference S_after−

S_before is 2.0 nm to 8.0 nm.

11. The head tracking servo method according to claim 7,

wherein the Δ

SFD is 0.03 to 0.50.

12. The head tracking servo method according to claim 7,

wherein the magnetic tape includes a non-magnetic layer including non-magnetic powder and a binding agent between the non-magnetic support and the magnetic layer.