Positioning misaligned disk heads

Claim 3

The method according to Claim 1 for effectively optimizing registration between external indicia sensed by said servo subsystem and servo signals embedded on said disks, wherein consecutive recording tracks are assigned consecutive odd and even identifying numbers, and wherein servo signals associated with odd and even numbered tracks are respectively stored on opposite surfaces of a disk and sensed by opposite head elements in said head assembly, said method comprising: commanding an initial movement of said head assembly to a reference track position prior to commanding said series of track seeking movements; at completion of said initial movement, determining if the assembly is offset from the center of the reference track by an even or odd number of track widths; and conditionally switching odd/even associations of said opposite head elements if the offset from the reference track is an odd number of track widths.

Claim 4

The initializing method of Claim 2 comprising: at completion of said initial movement determining a proper order of application of said signals for avoiding ambiguities in said offset measurements; and applying said signals in said order to said subsystem for conducting said offset measuring steps.

Claim 5

In a disk storage system in which a transducing head assembly is moved relative to recording tracks on disks by a servo subsystem, and in which said subsystem derives its positional reference for controlling track seeking movements of said assembly from indicia external to said disks and its positional reference for controlling said assembly to follow a particular track from both said external indicia and pre-recorded servo signals embedded in said recording tracks, a method for maintaining alignment between said subsystem and said tracks regardless of the physical alignment between either said head assembly or the external indicia and said tracks comprising: varying the effective alignment between said external indicia and said subsystem in discrete phase increments corresponding to predetermined fractions of the width of a said recording track; for each variation in effective alignment, commanding said subsystem to move said head assembly through a predetermined series of track positions relative to said disks; in association with each of said series of movements sensing embedded servo signals located at said track positions and determining therefrom offset measurements representing displacements of said assembly from centers of tracks at said positions; comparing offset measurements determined for all of said variations in effective alignment and determining which of said variations has the smallest offsets; establishing an effective alignment between said subsystem and external indicia corresponding to the variation having said smallest offsets; and conditioning said system for conducting normal track seeking and transducing operations relative to said disks with said established effective alignment.

Claim 6

In a disk storage system in which a transducing head assembly is moved relative to recording tracks on disks by a servo subsystem, and in which said subsystem derives its positional reference for controlling track seeking movements of said assembly from indicia external to said disks and its positional reference for controlling said assembly to follow a particular track from both said external indicia and pre-recorded servo signals embedded in said recording tracks, a method for maintaining alignment between said subsystem and said tracks regardless of the physical alignment between either said head assembly or the external indicia and said tracks comprising: varying the effective alignment between said external indicia and said subsystem in discrete phase increments corresponding to predetermined fractions of the width of a said recording track; for each variation in effective alignment, commanding said subsystem to move said head assembly through a predetermined series of track positions relative to said disks; in association with each of said series of movements sensing embedded servo signals located at said track positions and determining therefrom offset measurements representing displacements of said assembly from centers of tracks at said positions; comparing offset measurements determined for all of said variations in effective alignment and determining which of said variations has the smallest offsets; establishing an effective alignment between said subsystem and external indicia corresponding to the variation having said smallest offsets; and conditioning said system for conducting normal track seeking and transducing operations relative to said disks with said established effective alignment.

Claim 7

The method of Claim 4 wherein said step of varying effective alignment is accomplished by: generating a plurality of electrical signals as said head assembly is moved relative to said indicia, each signal varying periodically as said head assembly is moved across successive indicia with a periodicity corresponding to an integral multiple of the width of a track; said signals being staggered in phase relative to each other by discrete phase increments corresponding to predetermined fractions of a track width; and applying said signals separately to said servo subsystem as positioning references for respective said series of commanded movements.

Claim 8

The method of Claim 4 wherein said step of varying effective registration is accomplished by: generating a plurality of pairs of phase staggered electrical signals, each pair varying periodically as said head assembly is moved relative to said indicia with a periodicity corresponding to an integral multiple of a track width, the signals of each pair being in phase quadrature; said pairs being staggered in phase relative to each other by discrete phase increments corresponding to predetermined fractions of a track width; and applying each of said pairs of signals separately to said servo subsystem as positioning references for respective said series of commanded movements; predetermined phase transitions in one signal of each applied pair thereby serving as positioning references for I b cating boundaries between successive tracks and corresponding transitions in the other signal of the same pair serving as references for locating centers of tracks.