Track seeking and following
AssigneeInternational Business Machines Corporation
InventorsJoseph Philip Baca, Peter Thomas Marino
Life of this patent
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Abstract
A servo sector record track location pattern provides both seeking and following capability. The durations of servo signals within a servo sector uniquely identify track location lines within a band of such track location lines. A first-appearing servo signal pattern always provides full amplitude readback signals for normalizing track following operations. Subsequently appearing servo signal patterns yield an amplitude representative of energy content which is comparable with the signal amplitude and energy content of the first-appearing servo signal for yielding track position error signals. Apparatus for employing the novel servo pattern is also disclosed.
Claims21
The method of track seeking and following using a pattern of servo signals for grouping the tracks into bands with servo signal durations for each track within each band being in a unique combination, and a plurality of servo signals for each track disposed along a given sector length of each said track;
- the improvement including the following steps in combination:
- measuring durations of said servo signals for indicating track position within a band;
- and
- measuring energy of each said servo signals and comparing same for indicating position error with respect to said indicated track.
A record member having a magnetically coated surface for receiving signals in a plurality of parallel tracks having equally spaced and parallel track location lines defined by a plurality of servo position signals spaced along the track lengths in servo sectors, each sector having a leading portion;
- the improvement including in combination:
- each of said sectors having a plurality of recorded servo signal groups, each said group including a plurality of recorded servo signals disposed transversely to said track location lines;
- a first of said recorded signal groups being disposed in said leading portion having a recorded servo signal disposed and centered on each of said track location lines for yielding a full amplitude servo signal when sensed by a transducer for each track location line;
- and
- a second of said recorded signal groups being disposed so as to be sensed after said recorded servo signals in said first group and having diverse transverse positional relationships to said track location lines, each said diverse relationship indicating position errors when measured for signal energy contained in each such signal in said second signal group with respect to said first group recorded servo signal.
A record member having a magnetically coated surface for receiving signals in a plurality of parallel record tracks having track location lines defined by a plurality of servo position signal sectors spaced along the track length;
- the improvement including in combination:
- each sector having a plurality of servo signal groups extending transversely to said track location lines and being spaced along the tracks within each said sector;
- a first of said groups having a servo signal pattern centered on each respective one of said track location lines;
- a second of said groups having a plurality of servo signal patterns extending between predetermined ones of said track location lines;
- and
- certain ones of said servo signal patterns having diverse durations for identifying a band of said track location lines.
The method of operating a positioning apparatus having two relatively movable members including the steps of:
- seeking an addressed position by relatively moving said members;
- once said members are approximately at said addressed position, keeping said positioned members thereat by a position following operation;
- and
- during said position following operation simultaneously and continuously seeking said addressed position even though said members are at said addressed positional whereby any position perturbations from said addressed position are automatically compensated for.
The method of locating and centering a sensing transducer with respect to a given record track disposed in a given group of record tracks of a plurality of such groups;
- each record track being identifiable by a pattern of servo signals of unique duration and transverse placement within each said group;
- including the steps of:
- locating said given group of record tracks;
- measuring durations of servo signals being scanned in said given group and indicating the track being scanned in accordance with said measured durations;
- determining transverse locations of said servo signals being scanned for indicating transverse location with respect to said track being scanned;
- comparing said indications with a desired indication of said given track;
- and
- positioning said sensing transducer in accordance with said indications.
Dependencies are inferred from the claim text.