Magnetic disk device and control method of magnetic disk device
AssigneesKabushiki Kaisha Toshiba, Toshiba Electronic Devices & Storage Corporation
InventorToru Watanabe
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Abstract
A magnetic disk device of an embodiment includes: a head structure including at least one reproducing head and main magnetic pole gap installation portion behind a flying slider and including at least two thermal actuators; and a control unit that can independently control the thermal actuators and that sets spacing of the reproducing head and the main magnetic pole gap installation portion with respect to a recording medium by setting a rotational speed at the time of contact, which rotational speed is a rotational speed of the recording medium, to be lower than a normal rotational speed when the reproducing head and the main magnetic pole gap installation portion are brought into contact with the recording medium.
Claims8
A magnetic disk device comprising:
- a head structure comprising a reproducing head and a main magnetic pole gap installation portion behind a flying slider and including at least two thermal actuators;
- and
- a control unit that can independently control the at least two thermal actuators, and that sets spacing of the reproducing head and the main magnetic pole gap installation portion with respect to a recording medium by setting a rotational speed at a time of contact, the rotational speed being a rotational speed of the recording medium, to be lower than a normal rotational speed when the reproducing head and the main magnetic pole gap installation portion are brought into contact with the recording medium, wherein
- the control unit sets the spacing by using harmonic amplitude of a signal, the signal being previously recorded in the recording medium, at the rotational speed at the time of the contact of the reproducing head and the main magnetic pole gap installation portion, and
- the control unit measures a spacing change amount Δd by using a following expression (1) on a basis of primary component amplitude V01 and tertiary component amplitude V03 in a contact state of a spacing measurement pattern, and primary component amplitude V11 and tertiary component amplitude V13 of a reproduction signal,
- Δ
-
- d
- =
- λ
- 4
-
- π
-
- (
- ln
-
- V
- 11
- V
- 13
- -
- ln
-
- V
- 01
- V
- 03
- )
- expression
-
- (
- 1
- )
- here, λ is a wavelength of a fundamental frequency.
A control method of a magnetic disk device that includes a head structure comprising a reproducing head and a main magnetic pole gap installation portion behind a flying slider and including at least two thermal actuators, and a control unit that can independently control the at least two thermal actuators, the control method comprising:
- setting, when bringing the reproducing head and the main magnetic pole gap installation portion into contact with a recording medium, a rotational speed at a time of contact, the rotational speed being a rotational speed of the recording medium, to be lower than a normal rotational speed in a state of being capable of independently controlling the at least two thermal actuators;
- and
- setting spacing of the reproducing head and the main magnetic pole gap installation portion with respect to the recording medium at the rotational speed at the time of the contact, wherein
- setting of the spacing is performed by utilization of harmonic amplitude of a signal, the signal being previously recorded in the recording medium, at the rotational speed at the time of the contact of the reproducing head and the main magnetic pole gap installation portion, and
- in setting of the spacing, a spacing change amount Δd is measured by utilization of a following expression (1) on a basis of primary component amplitude V01 and tertiary component amplitude V03 in a contact state of a spacing measurement pattern, and primary component amplitude V11 and tertiary component amplitude V13 of a reproduction signal,
- Δ
-
- d
- =
- λ
- 4
-
- π
-
- (
- ln
-
- V
- 1
-
- 1
- V
- 1
-
- 3
- -
- ln
-
- V
- 0
-
- 1
- V
- 0
-
- 3
- )
- expression
-
- (
- 1
- )
- here, λ is a wavelength of a fundamental frequency.
Dependencies are inferred from the claim text.