Magnetic disk device and method
View Patent ↗According to an embodiment, a processing circuit of a magnetic disk device modulates a recording width in the radial direction of a first data sequence depending on a first combination and a second combination when writing data to a first track. The first track is adjacent to a second track in which data is already written. The first combination is a combination of the first data sequence that is data written to the first track and a second data sequence that is data already written to the second track. The second combination is a combination of polarities at the bit position of the first track and the bit position of the second track adjacent to each other in the radial direction.
1 . A magnetic disk device comprising:
a magnetic disk including a plurality of tracks;
a magnetic head that writes data to and reads data from the magnetic disk; and
a processing circuit that modulates a recording width in a radial direction of a first data sequence depending on a first combination and a second combination when data is written in a first track among the plurality of tracks by the magnetic head, the first data sequence being the data to be written in the first track, the first track being a track adjacent to a second track that is a track on which the data is already written among the plurality of tracks, the first combination being a combination of the first data sequence and a second data sequence that is data already written in the second track, the second combination being a combination of polarities at a bit position of the first track and a bit position of the second track adjacent to each other in the radial direction.
2 . The magnetic disk device according to claim 1 , wherein
the processing circuit increases the recording width in the radial direction at the bit position of the first track when the second combination corresponds to a combination of a same polarity.
3 . The magnetic disk device according to claim 1 , wherein
the processing circuit reduces the recording width in the radial direction at the bit position of the first track when the second combination corresponds to a combination of different polarities.
4 . The magnetic disk device according to claim 1 , wherein
the processing circuit:
is set with a first data pattern and a second data pattern, and
executes modulation of the recording width depending on the second combination in a case where both a condition that the first data sequence coincides with the first data pattern and a condition that the second data sequence coincides with the second data pattern are satisfied.
5 . The magnetic disk device according to claim 1 , further comprising:
a controller that stops control of modulation of the recording width in response to a positional deviation amount in a circumferential direction between the bit position of the first track and the bit position of the second track adjacent to each other in the radial direction exceeding a threshold value.
6 . The magnetic disk device according to claim 1 , further comprising:
a controller that stops writing data to the first track in response to a positional deviation amount in a circumferential direction between the bit position of the first track and the bit position of the second track adjacent to each other in the radial direction exceeding a threshold value, waits for rotation of the magnetic disk after stopping the writing, and executes writing of the data again.
7 . The magnetic disk device according to claim 1 , further comprising:
a controller that stops writing data to the first track in response to a positional deviation amount in a circumferential direction between the bit position of the first track and the bit position of the second track adjacent to each other in the radial direction exceeding a threshold value, and after stopping the writing, restarts writing data to the first track from a position different from a position where the writing has been stopped.
8 . The magnetic disk device according to claim 1 , wherein
the processing circuit modulates an amplitude of a recording current supplied to the magnetic head to modulate the recording width.
9 . The magnetic disk device according to claim 1 , wherein
the magnetic head includes an assist element that applies energy to the magnetic disk, and
the processing circuit controls an amount of the energy applied to the magnetic disk by the assist element to modulate the recording width.
10 . The magnetic disk device according to claim 1 , wherein
the processing circuit comprises a read and write channel and a preamplifier electrically connected to the read and write channel and the magnetic head, and
the read and write channel generates a control signal indicating whether or not to execute modulation of the recording width and transfers the control signal to the preamplifier.
11 . A method comprising
writing data to a first track among a plurality of tracks included in a magnetic disk using a magnetic head, wherein
the first track is a track adjacent to a second track that is a track on which data is already written among the plurality of tracks, and
the writing includes
modulating a recording width in a radial direction of a first data sequence depending on a first combination and a second combination, the first data sequence being the data to be written in the first track, the first combination being a combination of the first data sequence and a second data sequence that is the data already written in the second track, the second combination being a combination of polarities at a bit position of the first track and a bit position of the second track adjacent to each other in the radial direction.
12 . The method according to claim 11 , wherein
the modulating includes increasing the recording width in the radial direction at the bit position of the first track in response to the second combination corresponding to a combination of a same polarity.
13 . The method according to claim 12 , wherein
the modulating includes modulating an amplitude of a recording current supplied to the magnetic head to modulate the recording width.
14 . The method according to claim 12 , wherein
the magnetic head includes an assist element that applies energy to the magnetic disk, and
the modulating includes controlling an amount of the energy applied to the magnetic disk by the assist element to modulate the recording width.
15 . The method according to claim 11 , wherein
the modulating includes reducing the recording width in the radial direction at the bit position of the first track in response to the second combination corresponding to a combination of different polarities.
16 . The method according to claim 11 , wherein
the writing further includes executing modulation of the recording width depending on the second combination in response to both a condition that the first data sequence coincides with a first data pattern and a condition that the second data sequence coincides with a second data pattern being satisfied.
17 . The method according to claim 11 , wherein
the writing further includes stopping control of modulation of the recording width in response to a positional deviation amount in a circumferential direction between the bit position of the first track and the bit position of the second track adjacent to each other in the radial direction exceeding a threshold value.
18 . The method according to claim 11 , wherein
the writing further includes:
stopping writing data to the first track in response to a positional deviation amount in a circumferential direction between the bit position of the first track and the bit position of the second track adjacent to each other in the radial direction exceeding a threshold value; and
waiting for rotation of the magnetic disk after stopping the writing and executing writing of the data again.
19 . The method according to claim 11 , wherein
the writing further includes:
stopping writing data to the first track in response to a positional deviation amount in a circumferential direction between the bit position of the first track and the bit position of the second track adjacent to each other in the radial direction exceeding a threshold value; and
after stopping the writing, restarting writing data to the first track from a position different from a position where the writing has been stopped.
20 . The method according to claim 11 , wherein
the modulating includes modulating an amplitude of a recording current supplied to the magnetic head to modulate the recording width.