MAGNETIC DISK APPARATUS
A preamplifier receives a servo gate signal indicating whether magnetic information read out from a disk by a head is servo data for positioning-use or user data stored in a user area available for reading and writing of given data. In the preamplifier, a servo data gain and a user data gain are set in advance. Based on a received servo gate signal, the preamplifier changes the gain depending on whether the head outputs the servo data or the user data.
1 . A magnetic disk apparatus comprising:
a head that reads out magnetic information from a magnetic disk surface;
a servo gate signal generator that generates a servo gate signal indicating whether the magnetic information read out by the head is servo data for positioning-use or user data stored in a user area available for reading and writing of given data;
a read-write processor that performs reading from and writing to the magnetic disk based on the servo gate signal;
a preamplifier that amplifies an output from the head; and
a gain controller that changes a gain of the preamplifier based on the servo gate signal.
2 . The magnetic disk apparatus according to claim 1 , wherein
the head includes a plurality of heads each of which is provided for each of a plurality of magnetic disks,
the preamplifier amplifies outputs from the heads, and
the gain controller changes the gain depending on which of the heads outputs a signal to be amplified by the preamplifier.
3 . A magnetic disk apparatus comprising:
a head that reads out magnetic information from a magnetic disk surface;
a servo gate signal generator that generates a servo gate signal indicating whether the magnetic information read out by the head is servo data for positioning-use or user data stored in a user area available for reading and writing of given data;
a read-write processor that performs reading from and writing to the magnetic disk based on the servo gate signal;
a heater that adjusts a temperature of the head to a setting temperature; and
a temperature controller that changes the setting temperature based on the servo gate signal.