Magnetic servo of a recording head
View Patent ↗A method of aligning a magnetic read/write head to data tracks on a magnetic surface of a digital linear tape. The method includes writing a signal over a track of optical servo marks located on the magnetic surface of the tape with a servo channel writer, generating a position error signal from read back signals obtained from a servo channel reader and positioning the magnetic read/write head in accordance with the position error signal.
1. A method of aligning a magnetic read/write head to a plurality of data tracks on a magnetic surface of a digital linear tape comprising:
writing a signal over a track of optical servo marks located on the magnetic surface of the tape with a servo channel writer;
generating a position error signal from read back signals obtained from a servo channel reader, the servo channel reader including a first read head and a second read head for reading the signal written over the track of optical servo marks; and
positioning the magnetic read/write head in accordance with the position error signal,
wherein the read back signals include a first signal from the first read head and a second signal from the second read head, and
the position error signal includes a difference between the first signal and the second signal, wherein an absolute value of the difference is a magnitude of an offset and a sign of the difference is a direction of the offset.
2. The method of claim 1 wherein the track of optical servo marks is applied during manufacture of the tape.
3. The method of claim 1 wherein the track of optical servo marks is formed by printing.
4. The method of claim 1 wherein the track of optical servo marks is formed by embossing.
5. The method of claim 1 wherein the track of optical servo marks is formed by patterning/ablation by a laser beam.
6. The method of claim 1 wherein the signal is produced by writing a DC signal.
7. The method of claim 1 wherein the signal is produced by writing an AC signal.
8. The method of claim 1 wherein the servo channel reader is a center-tapped reader having a first read head and a second read head.
9. The method of claim 1 wherein the magnitude is correlated to micrometers.
10. The method of claim 9 wherein positioning the magnetic read/write head in accordance with the position error signal comprises driving the read/write head up relative the track of optical servo marks if the sign is negative.
11. The method of claim 9 wherein positioning the magnetic read/write head in accordance with the position error signal comprises driving the read/write head down relative the track of optical servo marks if the sign is positive.
12. A magnetic recording head servo system comprises:
a plurality of recording channels;
at least one magnetic servo channel, the magnetic servo channel generating servo signals from a track of optical servo marks;
a servo processing system connected to the magnetic servo channel for processing the servo signals, wherein the servo processing system comprises:
means for determining a difference between amplitudes detected by heads,
means for converting the difference into a linear position instruction, and
means for sending the linear position instruction to the motor; and
a motor connected and responsive to servo instructions received from the servo processing system, the motor controlling a position of the recording head servo system relative the position of the track of optical servo marks.
13. The system of claim 12 wherein the servo channel comprises:
a write head;
a first read head; and
a second read head.
14. The system of claim 13 wherein the write head writes a signal tone. signal tone.
15. The system of claim 14 wherein the read heads detect amplitudes of a signal tone.
16. A method of aligning a magnetic read/write head to a digital linear tape comprising:
reading a signal disposed over a track of optical servo marks located on the magnetic surface of the tape with a servo channel reader, the servo channel reader including two laterally displaced read heads for reading the signal;
generating a position error signal from read back signals obtained from the servo channel reader; and
positioning the magnetic read/write head in accordance with the position error signal.
17. The method of claim 16 wherein a magnitude of the position error signal is correlated to micrometers.
18. The method of claim 17 wherein positioning the magnetic read/write head in accordance with the position error signal comprises driving the read/write head up relative to the track of optical servo marks if the sign is negative.
19. The method of claim 17 wherein positioning the magnetic read/write head in accordance with the position error signal comprises driving the read/write head down relative to the track of optical servo marks if the sign is positive.