Positioning system for data storage apparatus and record medium for use therewith

A positioning system for positioning a positionable member transversely with respect to a moving record medium having a plurality of contiguous position reference tracks of equal width recorded thereon, extending in the direction of movement of said record medium;

• each of said tracks being divided longitudinally into a plurality of first and second sections, each of said first sections being laterally offset with respect to its immediately adjacent second sections by a distance of less than one track width, and each of said sections having recorded thereon at least one position reference signal at a predefined point in said section, to permit said signal to be sensed independently of any other transducer detectable signal on said record medium;
• said system comprising:
• a single position transducer adapted to sense each of said position reference signals;
• means coupled to said position transducer for moving said transducer from a first position to a second position in response to control signals supplied thereto;
• control circuit means connected to said transducer for receiving signals detected by said transducer from said position reference tracks,
• said control circuit means comprising
• means for deriving first and second incremental position signals from position reference signals detected by said transducer in said first and second sections respectively, said incremental position signals being displaced in phase by an amount dependent upon said lateral offset and varying cyclically as said tracks are crossed during said movement;
• a velocity signal generating circuit for deriving from linear portions of said first and second incremental position signals
• a velocity signal indicative of the velocity of said transducer;
• a velocity error signal generator for generating a velocity error signal indicative of the difference between said velocity signal and a reference velocity signal;
• and
• means connected to apply said velocity error signal to said moving means to control the velocity thereof during said movement.

Data storage apparatus comprising:

• record means on which data can be stored;
• means defining a predetermined path of movement for said record means;
• at least one data transducer for transferring data between said record means and external apparatus during movement of said record means in said predetermined path;
• transducer support means for carrying said data transducer between different transducing positions relative to said record means;
• actuator means for positioning said transducer support means in response to actuator control signals;
• and a servo transducer, supported by said transducer support means at a fixed position relative to said at least one data transducer;
• said record means having a plurality of contiguous servo tracks of equal width thereon, extending in the direction of said predetermined path of said record means past said servo transducer,
• said servo tracks being divided longitudinally into a plurality of interleaved sections, each section being laterally displaced with respect to its immediately adjacent sections by a distance of less than one track width, and each sectional portion of each track having recorded thereon at least one transducer detectable position reference signal which is not contiguous with any other transducer detectable signal on said record means,
• said apparatus further comprising control circuit means connected to receive signals detected by said servo transducer from said servo tracks,
• said control circuit means being responsive to said detected signals to derive at least one actuator control signal and being connected to apply said at least one actuator control signal to said actuator means.

Data storage apparatus comprising a plurality of magnetic disk records;

• a spindle upon which said disk records are mounted for rotation therewith;
• a plurality of data transducers for reading data recorded on said disk records at least one servo transducer for detecting servo information in a plurality of servo tracks of equal width recorded concentrically on one of said disk records associated with said servo transducer;
• transducer support means supporting said data and servo transducers in fixed positional relationship;
• and actuator means coupled to said transducer support means for positioning said transducer support means radially of said disk records;
• each said servo track storing servo information in the form of transitions from one magnetic state to another along its length, alternate transitions from one magnetic state to another being aligned with corresponding transitions along adjacent tracks, intervening transitions being staggered from one track to the next, and tracks on one side of aligned transitions being laterally displaced from tracks on the other side by a distance of less than one track width;
• said apparatus further comprising control circuit means connected to receive servo signals detected by said servo transducer from said servo tracks, said control circuit means being responsive to said detected servo signals to derive at least one actuator control signal and being connected to apply said at least one actuator signal to said actuator means.

A record medium for use in a positioning system, said medium having a plurality of transducer detectable position information signals recorded thereon in a pattern defining a plurality of paths of relative motion in a common direction between said medium and such a transducer, each of said signals being physically separate from every other transducer detectable signal on said medium;

• said position information signals including first and second groups of signals lying respectively in alternate laterally contiguous bands of equal width extending longitudinally in said direction of relative motion,
• said first and second groups of signals having a fixed longitudinal displacement from each other, and
• said position information signals further including third and fourth groups of signals also lying respectively in alternate laterally contiguous bands of the same equal width extending longitudinally in said direction of motion,
• said third and fourth groups of signals having a fixed longitudinal displacement from each other and from said first and second groups of signals,
• said bands in which said first and second groups of signals lie being laterally displaced by less than the width of one band from said bands in which said third and fourth groups of signals lie.