Hard disk drive employing a reference track to compensate for tracking error

Claim 2

A magnetic disc apparatus comprising: a magnetic disc having a plurality of track groups thereon each of which comprises plural data tracks and at least two reference tracks on which a servo signal is recorded, wherein the reference tracks are recorded in the center of each of the track groups: transducer means for reading and writing data signals from and on the data tracks and reading the servo signal from a reference track; actuator means for positioning the transducer means over a desired one of the tracks; means connected to the transducer means for computing and generating a tracking error signal as a function of the servo signal read from the reference tracks; memory means for storing the tracking error signal with respect to each of the track groups; position sensing means for sensing the position of the transducer means relative to the magnetic disc and outputting a corresponding position signal, wherein the position sensing means generates N periodic signals, where N is an integer, which are out of phase with each other and there are N reference tracks within one track group; and controller means, supplied with the output of the position sensing means, for controlling the actuator means according to the stored tracking error signal corresponding to the track group within which the transducer is to be positioned.

Claim 3

A magnetic disc apparatus comprising: a magnetic disc having a plurality of concentric data tracks and a reference region having N concentric servo tracks on which servo signals are prerecorded, wherein N is an integer larger than 2; transducer means for reading and writing data signals on the data tracks and reading the servo signals from the servo tracks; actuator means for positioning the transducer means over a desired one of the tracks; position sensor means for sensing the position of the transducer means relative to the magnetic disc, and for generating N periodic position signals each of which is equally 160°/N out of phase with each other, each of the N servo tracks corresponding to each of the N periodic position signals; computing means for computing and generating N tracking error signals according to the servo signals read from each of the servo tracks; memory means for storing the tracking error signals; controller means for controlling the actuator means according to the periodic position signals and the tracking error signals stored in the memory means; temperature detecting means for detecting the temperature of the apparatus and generating a corresponding output signal; and means connected to the temperature detecting means for compensating the tracking error signals according to the output signal of the temperature detecting means and generating N compensated error signals, wherein the controller means controls the actuator means according to the compensated error signals.

Claim 4

A magnetic disc apparatus comprising: a magnetic disc having a plurality of concentric data tracks and a reference region having N concentric servo tracks on which servo signals are prerecorded, wherein N is an integer larger than 2; transducer means for reading and writing data signals on the data tracks and reading the servo signals from the servo tracks; actuator means for positioning the transducer means over a desired one of the tracks; position sensor means for sensing the position of the transducer means relative to the magnetic disc, and for generating N periodic position signals each of which is equally 160°/N out of phase with each other, each of the N servo tracks corresponding to each of the N periodic position signals; computing means for computing and generating N tracking error signals according to the servo signals read from each of the servo tracks; memory means for storing the tracking error signals; controller means for controlling the actuator means according to the periodic position signals and the tracking error signals stored in the memory means; temperature detecting means for detecting the temperature of the apparatus and generating a corresponding output signal; and means connected to the temperature detecting means for compensating the tracking error signals according to the output signal of the temperature detecting means and generating N compensated error signals, wherein the controller means controls the actuator means according to the compensated error signals.

Claim 5

A magnetic disc apparatus comprising: (a) a magnetic disc having plurality of data tracks and at least two concentric reference regions each having four concentric reference tracks on which a servo signal is recorded at angularly spaced apart locations along the servo track; (b) transducer means for reading and writing data signals from and on the data tracks and reading the servo signals from the reference tracks; (c) actuator means for positioning the transducer means over a desired one of the tracks; (d) means connected to the transducer means for computing and generating tracking error signals as a function of the servo signal read at any selected angular location on the reference tracks; (e) memory means for storing the tracking error signal; (f) position sensing means for sensing the position of the transducer means relative to the magnetic disc and outputting a corresponding position signal, wherein the position sensing means generates at least N periodic signals which are at least 90° out of phase with each other, where N is an integer equal to or greater than 2; and (g) controller means, supplied with the output of the position sensing means, for controlling the actuator means according to the stored tracking error signal corresponding to the data track to which the transducer is to be positioned.

Claim 6

A magnetic disc apparatus comprising: (a) a magnetic disc having plurality of data tracks and at least two concentric reference regions each having four concentric reference tracks on which a servo signal is recorded at angularly spaced apart locations along the servo track; (b) transducer means for reading and writing data signals from and on the data tracks and reading the servo signals from the reference tracks; (c) actuator means for positioning the transducer means over a desired one of the tracks; (d) means connected to the transducer means for computing and generating tracking error signals as a function of the servo signal read at any selected angular location on the reference tracks; (e) memory means for storing the tracking error signal; (f) position sensing means for sensing the position of the transducer means relative to the magnetic disc and outputting a corresponding position signal, wherein the position sensing means generates at least N periodic signals which are at least 90° out of phase with each other, where N is an integer equal to or greater than 2; and (g) controller means, supplied with the output of the position sensing means, for controlling the actuator means according to the stored tracking error signal corresponding to the data track to which the transducer is to be positioned.

Claim 7

The magnetic disc apparatus as defined in claim 3, further comprising temperature detecting means for detecting the temperature of the apparatus and generating a corresponding output signal, and wherein the controller means is connected to the temperature detecting means for compensating the tracking error signals according to the output signal of the temperature detecting means and generating N compensated error signals, wherein the controller means controls the actuator means according to the compensated error signals.

Claim 8

The magnetic disc apparatus as defined in claim 4, wherein the controller means computes gradients of the error signals with respect to the tracks at individual temperatures and stores the gradients in the memory means and, after the actual temperature of the apparatus is detected by the detecting means, the error signal for a selected track is corrected in accordance with the stored gradient of the error signal at the detected temperature to produce the compensated error signal.

Claim 9

A magnetic disc apparatus comprising: (a) a magnetic disc having a plurality of concentric data tracks and at least two reference regions each having at least four concentric reference tracks on which servo signals are circumferentially prerecorded; (b) transducer means for reading and writing data signals on the data tracks and reading the servo signals from the servo tracks; (c) actuator means for positioning the transducer means over a desired one of the tracks; (d) position sensor means for sensing the position of the transducer means relative to the magnetic disc, and for generating N periodic position signals each of which is at least 90° out of phase with each other, wherein N is an integer equal to or larger than 2, the period of the periodic position signals corresponding to the reference tracks; (e) computing means for computing and generating tracking error signals according to the servo signals read from each of the servo tracks; (f) memory means for storing the tracking error signals; and (g) controller means for controlling the actuator means according to the periodic position signals and the tracking error signals stored in the memory means.

Claim 10

A magnetic disc apparatus comprising: (a) a magnetic disc having a plurality of concentric data tracks and at least two reference regions each having at least four concentric reference tracks on which servo signals are circumferentially prerecorded; (b) transducer means for reading and writing data signals on the data tracks and reading the servo signals from the servo tracks; (c) actuator means for positioning the transducer means over a desired one of the tracks; (d) position sensor means for sensing the position of the transducer means relative to the magnetic disc, and for generating N periodic position signals each of which is at least 90° out of phase with each other, wherein N is an integer equal to or larger than 2, the period of the periodic position signals corresponding to the reference tracks; (e) computing means for computing and generating tracking error signals according to the servo signals read from each of the servo tracks; (f) memory means for storing the tracking error signals; and (g) controller means for controlling the actuator means according to the periodic position signals and the tracking error signals stored in the memory means.

Claim 11

A magnetic disc apparatus according to claim 6, wherein the magnetic disc has an additional reference region having N additional concentric servo tracks on which servo signals are circumferentially prerecorded.