Magnetic tape device and head tracking servo method

• US 10,170,144 B2
• Filed: 03/14/2018
• Issued: 01/01/2019
• 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
• Primary Examiner(s): Hindi, Nabil
• Application Number:
  US15/920,635
• Publication Number:
  US 20180286452A1
• Time in Patent Office: 293 Days
• Field of Search: 360 75, 360 7301, 360 7304, 360 7309, 360134, 428826
• 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 and a magnetic tape, in which the magnetic tape includes fatty acid ester in a magnetic layer, Ra measured regarding a surface of the magnetic layer is 2.0 nm or smaller, 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 7.0 nm or smaller, a difference between spacings before and after the vacuum heating is greater than 0 nm and 8.0 nm or smaller, and a ratio of an average area Sdc of a magnetic cluster of the magnetic tape in a DC demagnetization state and an average area Sac of a magnetic cluster thereof in an AC demagnetization state measured with a magnetic force microscope is 0.80 to 1.30.

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 center line average surface roughness Ra measured regarding a surface of the magnetic layer is equal to or smaller than 2.0 nm,

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

a ratio Sdc/Sac of an average area Sdc of a magnetic cluster of the magnetic tape in a DC demagnetization state and an average area Sac of a magnetic cluster of the magnetic tape in an AC demagnetization state measured with a magnetic force microscope is 0.80 to 1.30.

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 center line average surface roughness Ra measured regarding the surface of the magnetic layer is 1.2 nm to 2.0 nm.

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 center line average surface roughness Ra measured regarding a surface of the magnetic layer is equal to or smaller than 2.0 nm,

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

a ratio Sdc/Sac of an average area Sdc of a magnetic cluster of the magnetic tape in a DC demagnetization state and an average area Sac of a magnetic cluster of the magnetic tape in an AC demagnetization state measured with a magnetic force microscope is 0.80 to 1.30.

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 a 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 center line average surface roughness Ra measured regarding the surface of the magnetic layer is 1.2 nm to 2.0 nm.

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.