Magnetic tape device and head tracking servo method

• US 10,062,403 B1
• Filed: 02/20/2018
• Issued: 08/28/2018
• Est. Priority Date: 02/20/2017
• Status: Active Grant

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Inventors: Kasada, Norihito, Ozawa, Eiki
• Primary Examiner(s): YOUNG, WAYNE R
• Assistant Examiner(s): Habermehl, James L
• Application Number:
  US15/900,412
• Publication Number:
  US 20180240477A1
• Time in Patent Office: 189 Days
• Field of Search: 360 55, 360 69, 360 75, 360 7712, 360134
• CPC Class Codes: G11B 5/3909 Arrangements using a magnetic tunnel junction
• CPC Class Codes: G11B 5/68 comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent
• CPC Class Codes: G11B 5/70 on a base layer
• CPC Class Codes: G11B 5/702 characterised by the bonding agent
• CPC Class Codes: G11B 5/78 Tape carriers
• CPC Class Codes: G11B 5/84 Processes or apparatus specially adapted for manufacturing record carriers

Abstract

The magnetic tape device includes a magnetic tape; and a servo head, in which the servo head is a TMR head, the magnetic tape includes a servo pattern in the magnetic layer, 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 logarithmic decrement acquired by a pendulum viscoelasticity test performed regarding the surface of the magnetic layer is equal to or smaller than 0.050, 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 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 and a binding agent 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 logarithmic decrement acquired by a pendulum viscoelasticity test performed regarding the surface of the magnetic layer is equal to or smaller than 0.050, 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 logarithmic decrement is 0.010 to 0.050.

3. The magnetic tape device according to claim 2,

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

4. 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.

5. 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.

6. 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 and a binding agent 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 logarithmic decrement acquired by a pendulum viscoelasticity test performed regarding the surface of the magnetic layer is equal to or smaller than 0.050, 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.

7. The head tracking servo method according to claim 6,

wherein the logarithmic decrement is 0.010 to 0.050.

8. 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.

9. The head tracking servo method according to claim 6,

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

10. The head tracking servo method according to claim 6,

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.