Magnetic recording medium, servo signal recording apparatus and method of producing magnetic recording medium

A servo signal recording apparatus comprising:

• a servo signal recording unit configured to apply a magnetic field to a part of a magnetic layer included in a magnetic recording medium, thereby recording a servo signal by magnetizing a part of the magnetic layer in a first direction, the first direction containing a component of a perpendicular direction that is perpendicular to a top surface of the magnetic layer, an absolute value of the product of (1) a rate of an amount of magnetization in the perpendicular direction with respect to a maximum amount of magnetization that would be obtained if amounts of magnetization of the magnetic recording medium were measured while turning the magnetic recording medium and (2) a squareness ratio of the magnetic layer in a longitudinal direction that is parallel to the top surface being 0.05 or more and 0.25 or less;
• and
• a pre-processing unit configured to apply a magnetic field to the magnetic layer before the servo signal is recorded by the servo signal recording unit, thereby pre-magnetizing the magnetic layer in a second direction, the second direction containing the component of the perpendicular direction, which second direction is opposite to the first direction.

A method of producing a magnetic recording medium, the method comprising:

• applying a magnetic field to a part of a magnetic layer included in a magnetic recording medium, thereby recording a servo signal by magnetizing a part of the magnetic layer in a first direction, the first direction containing a component of a perpendicular direction that is perpendicular to a top surface of the magnetic layer, an absolute value of the product of (1) a rate of an amount of magnetization in the perpendicular direction with respect to a maximum amount of magnetization that would be obtained if amounts of magnetization of the magnetic recording medium were measured while turning the magnetic recording medium and (2) a squareness ratio of the magnetic layer in a longitudinal direction that is parallel to the top surface being 0.05 or more and 0.25 or less;
• and
• applying a magnetic field to the magnetic layer before recording of the servo signal, thereby pre-magnetizing the magnetic layer in a second direction, the second direction containing the component of the perpendicular direction, which second direction is opposite to the first direction.

A magnetic recording medium comprising:

• a magnetic layer having a servo signal recorded thereon by a magnetic leakage field occurring from at least one magnetic gap facing the magnetic layer, the magnetic gap having a gap width of 1 μm or less, the servo signal being recorded on the magnetic layer by magnetizing a part of the magnetic layer in a first direction, the first direction containing a component of a perpendicular direction that is perpendicular to a top surface of the magnetic layer, and an absolute value of the product of (1) a rate of an amount of magnetization in the perpendicular direction with respect to a maximum amount of magnetization that would be obtained if amounts of magnetization of the magnetic recording medium were measured while turning the magnetic recording medium and (2) a squareness ratio of the magnetic layer in a longitudinal direction that is parallel to the top surface being 0.05 or more and 0.25 or less,
• the servo signal being configured to allow a reproduced waveform corresponding to a pulse input duration, resulting from reading the servo signal, to have a distance indicated by an interval between adjacent positive and negative output peaks of 1.2 μm or less.

A servo signal recording apparatus comprising:

• a servo signal recording unit provided with at least one magnetic gap, the magnetic gap itself having a gap width of 1 μm or less, the magnetic gap being configured to produce a magnetic leakage field to record a servo signal onto a magnetic layer included in a magnetic recording medium by magnetizing a part of the magnetic layer in a first direction, the first direction containing a component of a perpendicular direction that is perpendicular to a top surface of the magnetic layer, and an absolute value of the product of (1) a rate of an amount of magnetization in the perpendicular direction with respect to a maximum amount of magnetization that would be obtained if amounts of magnetization of the magnetic recording medium were measured while turning the magnetic recording medium and (2) a squareness ratio of the magnetic layer in a longitudinal direction that is parallel to the top surface being 0.05 or more and 0.25 or less, so that the recorded servo signal allows a reproduced waveform, resulting from reading the servo signal, to have a distance indicated by an interval between adjacent positive and negative output peaks of 1.2 μm or less.

A method of producing a magnetic recording medium, the method comprising:

• recording a servo signal onto a magnetic layer included in a magnetic recording medium by a magnetic leakage field occurring from at least one magnetic gap, the magnetic gap itself having a gap width of 1 μm or less, the servo signal being recorded on the magnetic layer by magnetizing a part of the magnetic layer in a first direction, the first direction containing a component of a perpendicular direction that is perpendicular to a top surface of the magnetic layer, and an absolute value of the product of (1) a rate of an amount of magnetization in the perpendicular direction with respect to a maximum amount of magnetization that would be obtained if amounts of magnetization of the magnetic recording medium were measured while turning the magnetic recording medium and (2) a squareness ratio of the magnetic layer in a longitudinal direction that is parallel to the top surface being 0.05 or more and 0.25 or less, so that the recorded servo signal allows a reproduced waveform, resulting from reading the servo signal, to have a distance indicated by an interval between adjacent positive and negative output peaks of 1.2 μm or less.