Resolution enhancement of absolute track position using iterative process and position bursts

Apparatus for generating a head positioning signal comprising:

• head position information recognition apparatus comprising:
• at least two peak holders for holding peak values of reproduced signal amplitudes of respective sub-servo-patterns having a periodic interval of the width of M tracks (M is an integer of 2 or more) formed in a servo pattern formed discretely in the circular direction of a rotatable recording medium,
• at least one comparator for comparing said at least two peak values,
• a first latch for memorizing the output of said comparator, thereby to hold a first binary-valued information,
• an offset decoder for determining to which peak holder an offset is to be added in compliance with the contents of said first latch,
• an offset-adder for adding an offset to a specified peak holder in compliance with the instruction of the offset decoder,
• a second latch for holding a second binary-valued information by memorizing momentarily a result obtained by a comparison between a peak value held by the peak holder to which the offset was already added and a peak value held by the peak holder to which offset was not added using said comparator again,
• N latches for latching N binary-valued informations from 1st to N-th binary-valued information, and
• a head position information discrimination element for detecting the relative position relation of a head with respect to tracks with a precision up to 1/(2.sup.N) of the information track width by using contents of said from the 1st latch to the N-th latch, and
• a central processing means (.mu.CPU) for generating an expanded position signal having a dynamic range of the interval of the width of M tracks in periodic interval of said M tracks, by computing a relative distance in radial direction of a rotatable recording medium between a head and a predetermined track up to a precision of 1/(2.sup.N) of a track width.

Apparatus for head positioning comprising:

• a head for reproducing information of servo-patterns formed discretely in circular direction of a rotatable recording medium,
• a servo information demodulator for taking out the servo Information included in said discrete servo-patterns out of reproduced signal from said head,
• head positioning signal generating apparatus comprising:
• head position information recognition apparatus comprising:
• at least two peak holders for holding peak values of reproduced signal amplitudes of respective sub-servo-patterns having a periodic interval of the width of M tracks (M is an Integer of 2 or more) formed in a servo pattern formed discretely in the circular direction of a rotatable recording medium,
• at least one comparator for comparing said at least two peak values,
• a first latch for memorizing the output of said comparator, thereby to hold a first binary-valued information,
• an offset decoder for determining to which peak holder an offset is to be added in compliance with the contents of said first latch,
• an offset-adder for adding an offset to a specified peak holder in compliance with the instruction of the offset decoder,
• a second latch for holding a second binary-valued information by memorizing momentarily a result obtained by a comparison between a peak value held by the peak holder to which the offset was already added and a peak value held by the peak holder to which offset was not added using said comparator again,
• N latches for latching N binary-valued informations from 1st to N-th binary-valued information, and
• a head position information discrimination element for detecting the relative position relation of a head with respect to tracks with a precision up to 1/(2.sup.N) of the information track width by using contents of said from the 1st latch to the N-th latch, and
• a central processing means (.mu.CPU) for generating an expanded position signal having a dynamic range of the interval of the width of M tracks in periodic interval of said M tracks, by computing a relative distance In radial direction of a rotatable recording medium between a head and a predetermined track up to a precision of 1/(2.sup.N) of a track width,
• velocity instruction means for issuing track access velocity instruction in compliance with the distance to a target track based on the output of said head positioning signal generating apparatus,
• velocity recognition means for acquiring a moving velocity of the head in the radial direction of the recording medium,
• positioning means for moving the head to an arbitrary position in the radial direction of said recording medium, by feeding back a signal based on the output of said head positioning signal generating apparatus in track tracing control and a signal based on a velocity error between the output of said velocity instruction means and the output of said velocity recognition means in track access control to said positioning means.