Signal-extraction laser-pulse system architecture for thermally-assisted magnetic recording
View Patent ↗A thermal-assisted magnetic recording (TAMR) system is described which generates laser-pulse signals from the write data line. Additionally, training signals for initial synchronization are fed to the preamp IC using the write data line during servo read cycle. This requires no increase in the number of wires going to read-write driver chip (R/W IC) (preamp). In embodiments of the invention the R/W IC also includes registers that are set using serial data from the system electronics to influence the characteristics of the drive signal to the laser.
1. A disk drive comprising:
a slider containing a read head, a write head and a laser;
a disk with thin film magnetic material that includes a plurality of angularly spaced servo sectors with servo information readable by the read head as the disk rotates and the servo sectors periodically pass under the read head;
a read-write IC that is connected through a flexible cable to a write data line as input, the read-write IC supplying a pulsing drive signal to the laser to heat magnetic material on the disk and supplying write signals to the write head, the read-write IC including a pulse extraction circuit that uses training signals on the write data line to derive a timing of the pulsing drive signal for the laser; and
system electronic circuits that periodically place the training signals on the write data line as input to read-write IC through the flexible cable when receiving servo information from the read head.
2. The disk drive of claim 1 further comprising one or more registers in the read-write IC that are set with data sent from the system electronic circuits to the read-write IC on a serial data line, the data in the registers influencing characteristics of the pulsing drive signal for the laser.
3. The disk drive of claim 2 further comprising a laser power sensor that supplies a power level signal to a first amplifier in the read-write IC which compares the power level signal to reference value, the first amplifier generating an output signal that is added to a pulse train by a second amplifier to generate the pulsing drive signal for the laser and wherein the reference value is determined using data in the registers.
4. The disk drive of claim 1 further comprising a laser power sensor that supplies a power level signal to a first amplifier in the read-write IC which compares the power level signal to a reference value, the first amplifier generating a bias output signal that is added to a pulse train by a second amplifier to generate the pulsing drive signal for the laser.
5. The disk drive of claim 1 wherein the read-write IC includes a differentiator that takes the write data line as input and supplies a signal to a rectifier, the output of the rectifier going as input to a PLL which generates a pulse train that is processed to become the pulsing drive signal for the laser.
6. The disk drive of claim 5 wherein the PLL locks to a write data clock frequency using the training signal and remains locked to the write data clock frequency between times that servo sectors periodically pass under the read head.
7. A method of operating a disk drive comprising:
periodically reading servo signals from angularly spaced servo sectors on a rotating disk with thin film magnetic material as the servo sectors pass under the read head;
periodically sending training signals to a read-write IC on write data lines while reading the servo signals; and
generating a pulsing drive signal from the training signals in the read-write IC to drive a laser to heat a spot of magnetic material on the disk before a write head applies a magnetic field to the spot of magnetic material.
8. The method of claim 7 wherein the training signals are passed through a differentiator and a rectifier before being fed into a PLL in the read-write IC, and the output from the PLL locking to a frequency that is equal to a frequency of a write data clock and remaining locked to a frequency of a write data clock between servo signals.
9. The method of claim 7 further comprising setting one or more registers in the read-write IC using data received by the read-write IC on a serial data line, and using the data in the registers to set characteristics of the pulsing drive signal for the laser.
10. The method of claim 7 further comprising comparing a power level signal from laser power sensor to reference value, and using a difference between the power signal and the reference value to adjust a DC bias that is included in the pulsing drive signal for the laser.
11. The method of claim 10 wherein the reference value is determined using data in a register that is set using data received by the read-write IC on a serial data line.
12. A disk drive comprising:
a disk with thin film magnetic material organized in concentric tracks and including a plurality of angularly spaced servo sectors with servo information readable by a read head as the disk rotates and the servo sectors periodically pass under the read head;
a slider containing the read head, a write head, a laser, and a laser power level sensor, the slider being selectively positionable over each track;
a read-write IC that is connected through a flexible cable to a write data line as input, the read-write IC supplying a pulsing drive signal to the laser to heat magnetic material on the disk and supplying write signals to the write head, the read-write IC including a pulse extraction circuit that uses training signals on the write data lines to derive a timing of the pulsing drive signal for the laser, the read-write IC including a first amplifier that compares a signal from the laser power level sensor to a reference value to generate a DC bias output signal that is added to the pulsing drive signal for the laser; and
system electronic circuits that periodically place the training signals on the write data line as input to read-write IC when the servo sectors pass under the read head.
13. The disk drive of claim 12 further comprising one or more registers in the read-write IC that are set with data sent from the system electronic circuits to the read-write IC on a serial data line, the data in the registers influencing characteristics of the pulsing drive signal for the laser.
14. The disk drive of claim 13 wherein the reference value is determined using data in the registers.
15. The disk drive of claim 12 wherein the read-write IC includes a differentiator that takes the write data line as input and supplies a signal to a rectifier, the output of the rectifier providing input to a PLL which generates a pulse train that is processed to become the pulsing drive signal for the laser.
16. The disk drive of claim 15 wherein the PLL locks to a write data clock frequency using the training signal and remains locked to the write data clock frequency between times that servo sectors periodically pass under the read head.