US 5,694,265 AGranted

Disk apparatus for detecting position of head by reading phase servo pattern

AssigneeFujitsu Limited

InventorsTatsuhiko Kosugi, Susumu Yoshida, Makoto Chiba, Syuichi Hashimoto, Masahide Kanegae

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Abstract

A duty pulse is formed by setting in response to a leading edge of a clock synchronized with a peak detection of a servo frame read signal by a peak detecting circuit and by resetting by a signal by which a zero-cross point of a read signal of a phase servo pattern was detected. A head position signal is formed by integrating the duty pulse. Since there is a deviation of the timings between the peak detection and the zero-cross detection, a duty ratio is measured so as to be adjusted to 50% in the on-track state of a target cylinder. The timings for a reference clock and a zero-cross detection pulse are delayed and adjusted accordingly.

Claims51

Dependent claims

A disk apparatus comprising:

a disk medium having a servo surface
said servo surface having a plurality of servo frames arranged in the circumferential direction of each of a plurality of cylinders each sequentially including a timing region having timing information used to phase synchronize a clock, a marker region having marker information indicative of a servo region start position, and a servo region having servo information;
a servo head, movable in the radial direction of said disk medium, for reading said timing, marker and servo information;
a read pulse detecting circuit section for detecting a read signal for said timing marker, and servo regions of said servo frames read by said servo head and for generating read pulses for said timing, marker and servo regions in accordance with a timing signal obtained from said timing information;
a clock generating circuit section for generating a reference clock in sync with the read pulse generated by said read pulse detecting circuit section;
a master clock forming circuit section for producing a plurality of master clocks having phases different from a reference phase of the reference clock of said clock generating circuit section and for selecting and outputting the master clock of a reference phase corresponding to a target cylinder in which said servo head is located on a track;
a duty pulse forming circuit section for generating a duty pulse signal of a duty ratio corresponding to a phase difference in a range from the reference phase of the master clock to a detection timing of said servo information by said read pulse detecting circuit section;
an integrating circuit section for integrating the duty pulse signal to obtain an integrated duty pulse signal and for generating a position signal indicative of the position of said servo head;
a duty measuring circuit section for measuring the duty ratio of said duty pulse signal for a specific target cylinder during an initializing process executed just after a power source is turned on;
a duty adjusting circuit section for producing an adjusting state for maintaining the duty ratio of said duty pulse signal at 50% using the result of the measurement of said duty measuring circuit section;
a speed detecting circuit section for detecting a head moving speed of the servo head during a seeking operation on the basis of a difference of the head position signals generated by the integrating circuit section at sampling periods;
and
a position predicting circuit section for predicting the servo head position corresponding to a target cylinder at the next sampling time point at said every sampling period, said clock generating circuit section selecting the master clock of a phase corresponding to the head position predicted by said position prediction.

10 more elements

A disk apparatus comprising:

a disk medium having a servo surface
said servo surface having a plurality of servo frames arranged in the circumferential direction of each of a plurality of cylinders each sequentially including a timing region having timing information used to phase synchronize a clock, a marker region having marker information indicative of a servo region start position, and a servo region having servo information;
a servo head, movable in the radial direction of said disk medium, for reading said timing, marker and servo information;
a read pulse detecting circuit section for detecting a read signal for said timing marker, and servo regions of said servo flames read by said servo head and for generating read pulses for said timing, marker and servo regions in accordance with a timing signal obtained from said timing information;
a clock generating circuit section for generating a reference clock in sync with the read pulse generated by said read pulse detecting circuit section;
a master clock forming circuit section for producing a plurality of master clocks having phases different from a reference phase of the reference clock of said clock generating circuit section and for selecting and outputting the master clock of a reference phase corresponding to a target cylinder in which said servo head is located on a track;
a duty pulse forming circuit section for generating a duty pulse signal of a duty ratio corresponding to a phase difference in a range from the reference phase of the master clock to a detection timing of said servo information by said read pulse detecting circuit section;
an integrating circuit section for integrating the duty pulse signal to obtain an integrated duty pulse signal and for generating a position signal indicative of the position of said servo head;
a duty measuring circuit section for measuring the duty ratio of said duty pulse signal for a specific target cylinder during an initializing process executed just after a power source is turned on;
a duty adjusting circuit section for producing an adjusting state for maintaining the duty ratio of said duty pulse signal at 50% using the result of the measurement of said duty measuring circuit section;
a data surface on an opposite side of the disk medium from said servo surface;
a data head for moving in the radial direction of the disk medium with said servo head and for reading out information recorded on said data surface;
a data surface servo writing circuit section for recording servo information having a phase shift in one direction and for recording servo information having a phase shift in another opposite direction for each of a plurality of servo frames arranged in a circumferential direction of a specific cylinder on the data surface, thereby forming a servo region on the data surface, wherein;
said data surface servo writing circuit section divides the servo region of the data surface into four fields, records the servo information having the phase shift in the one direction into the first and fourth fields among said four fields, and records the servo information having the opposite phase shift into the second and third fields among said four fields;
and
said data surface servo writing circuit section writes servo information to be used for measurement of a yaw angle offset of a head driving mechanism which drives the servo and data heads onto both an outer rim cylinder and an inner rim cylinder separate from a user accessible region on the data surface.

13 more elements

A disk apparatus comprising:

a disk medium having a servo surface
said servo surface having a plurality of servo frames arranged in the circumferential direction of each of a plurality of cylinders each sequentially including a timing region having timing information used to phase synchronize a clock, a marker region having marker information indicative of a servo region start position, and a servo region having servo information;
a servo head, movable in the radial direction of said disk medium, for reading said timing, marker and servo information;
a read pulse detecting circuit section for detecting a read signal for said timing marker, and servo regions of said servo frames read by said servo head and for generating read pulses for said timing, marker and servo regions in accordance with a timing signal obtained from said timing information;
a clock generating circuit section for generating a reference clock in sync with the read pulse generated by said read pulse detecting circuit section;
a master clock forming circuit section for producing a plurality of master clocks having phases different from a reference phase of the reference clock of said clock generating circuit section and for selecting and outputting the master clock of a reference phase corresponding to a target cylinder in which said servo head is located on a track;
a duty pulse forming circuit section for generating a duty pulse signal of a duty ratio corresponding to a phase difference in a range from the reference phase of the master clock to a detection timing of said servo information by said read pulse detecting circuit section;
an integrating circuit section for integrating the duty pulse signal to obtain an integrated duty pulse signal and for generating a position signal indicative of the position of said servo head;
a duty measuring circuit section for measuring the duty ratio of said duty pulse signal for a specific target cylinder during an initializing process executed just after a power source is turned on;
a duty adjusting circuit section for producing an adjusting state for maintaining the duty ratio of said duty pulse signal at 50% using the result of the measurement of said duty measuring circuit section;
D/A converting means for converting servo control head drive data into an analog signal;
a reference voltage generating circuit section for generating a reference voltage to determine a center value of the analog signal corresponding to a center value of data input to said D/A converting means;
a drive circuit section for supplying a drive current to a head driving section in accordance with the polarity and magnitude of analog signal;
a center error measuring circuit section for changing the head drive data for said D/A converting means from said input center value at the time of said initializing process and for measuring errors which occur until said analog signal coincides with said reference voltage;
and
a center error correcting circuit section for correcting the head drive data after completion of said initializing process based upon the measured errors.

13 more elements

Dependencies are inferred from the claim text.