Apparatus for assisting write operation using high frequency magnetic field in disk drive
According to one embodiment, a disk drive having a spin torque oscillator and designed to perform high frequency assisted writing. The disk drive has a magnetic disk, a magnetic head, a coil, and a drive current controller. The drive current controller controls a drive current to supply to the spin torque oscillator. To record data magnetically in the disk, the drive current controller supplies to the spin torque oscillator the drive current that changes in synchronism with the polarity inversion of the recording current supplied to the coil, which excites the recording magnetic pole of the magnetic head.
1. A disk drive comprising:
a magnetic disk;
a magnetic head comprising a recording magnetic pole, a read head element, and a spin torque oscillator arranged near the recording magnetic pole and configured to perform high frequency assisted writing;
a current source configured to supply a recording current to a coil for exciting the recording magnetic pole in order to record data magnetically on the magnetic disk; and
a drive current control module configured to supply a drive current to the spin torque oscillator that changes in synchronism with a polarity inversion of the recording current.
2. The disk drive of claim 1 , wherein the drive current control module is configured to superpose a predetermined direct current over the drive current, and to supply the drive current with the direct current to the spin torque oscillator.
3. The disk drive of claim 1 , wherein the drive current control module is configured to supply the drive current to the spin torque oscillator, after inverting polarity of the drive current in synchronism with the polarity inversion of the recording current.
4. The disk drive of claim 1 , wherein the drive current control module is configured to change amplitude of the drive current in accordance with the polarity of the drive current.
5. The disk drive of claim 1 , further comprising a recording-signal outputting module configured to output a recording signal containing data in order to record the data magnetically on the magnetic disk,
wherein the drive current control module is configured to divide a current, changing in synchronism with the recording signal, into two currents, and to supply the two currents to the coil and the spin torque oscillator, respectively.
6. The disk drive of claim 1 , wherein the drive current control module is configured to adjust the drive current, thereby to make the spin torque oscillator oscillate at a constant frequency, regardless of the value or polarity of the recording current.
7. The disk drive of claim 1 , further comprising a pre-phase compensator configured to either advance or delay the timing of changing the drive current from the timing of inverting the recording current in polarity.
8. The disk drive of claim 2 , further comprising a pre-phase compensator configured to either advance or delay the timing of changing the drive current from the timing of inverting the recording current in polarity.
9. A disk drive comprising:
a magnetic disk;
a magnetic head comprising a write head element and a read head element configured to record on the magnetic disk, and to reproduce data from the magnetic disk;
a spin torque oscillator arranged near the recording magnetic pole of the write head element and configured to apply a high-frequency magnetic field to the magnetic disk in order to perform high frequency assisted writing;
a current source configured to supply a recording current to a coil for exciting the recording magnetic pole in order to record data magnetically in the magnetic disk; and
a drive current control module configured to supply a drive current to the spin torque oscillator that changes in synchronism with a polarity inversion of the recording current.
10. The disk drive of claim 9 , further comprising a head amplifier configured to amplify a reproduced signal output from the magnetic head, and to supply a recording current to the magnetic head,
wherein the head amplifier comprises the current source and the drive current control module.
11. The disk drive of claim 9 , further comprising a read/write channel configured to output a recording signal for recording the data, the recording signal having been generated by modulating the data,
wherein the drive current control module is configured to supply the drive current which is synchronous with the change of the recording signal to the spin torque oscillator.
12. The disk drive of claim 10 , further comprising a read/write channel configured to output a recording signal for recording the data, the recording signal having been generated by modulating the data,
wherein the drive current control module is configured to supply the drive current synchronous with the change of the recording signal to the spin torque oscillator.