Data transducer position control system for rotating disk data storage equipment

In a data storage device including a frame, a data storage disk journalled to the frame and rotatingly driven by motor means at a constant velocity and characterized by a multiplicity of concentric data tracks on the major surfaces thereof, at least one data transducer head in close proximity to a said disk surface, the improvement comprising:

• a bidirectionally moveable electromechanical mover supported by said frame adjacent to said disk being moveable between and stabilized at a position related to each said data track,
• a head mounting structure securing said data transducer head at one end thereof and secured to said mover at the other end thereof for moving said head across said multiplicity of concentric data tracks,
• bidirectional mover driver means connected to said mover and capable of moving said structure to any selected one of said concentric data tracks in accordance with externally supplied track position information and of maintaining said structure substantially within said selected data track during read and/or write operations by reference to said frame,
• data track stabilization means including said mover for stabilizing said structure within a range between the boundaries of each said data track,
• a time sampled fine position closed loop servo connected to said driver and including a single, data masked servo sector on a data surface of said disk containing track centerline servo control data therein readible by said head, a sample and hold circuit connected to said head during passes over said sector for holding control data read therefrom, and correction signal generator means connected to said sample and hold circuit for generating an offset signal for application to said driver means to promote and maintain track centerline alignment of said head during read and write operations.

In a data storage device including a frame, a disk drive motor secured to the frame and connected to a source of electricity, a magnetic data storage disk rotatingly driven by said drive motor at a constant velocity and characterized by a multiplicity of concentric data tracks on at least one major surface thereof, and at least one read and write head held in close proximity to said disk surface by air bearing effect, the improvement comprising:

• a bidirectionally rotatable electromechanical rotor journalled to said frame adjacent to said disk and having an axis of rotation parallel with the axis of said disk,
• a beam securing said head at one end thereof and secured to said rotor at a counterbalanced axis of rotation near the other end thereof for arcuately moving said head across said multiplicity of concentric data tracks,
• bidirectional rotor driver means connected to said rotor for rotating said beam to maintain said head within a selected data track during read and/or write operations and to move said head from a departure track to a destination track during track seeking operations,
• a head position transducer mechanically linked to said beam and responsive to absolute position of said head relative to said frame and providing track position signals in quadrature,
• head controller means connected to said head position transducer, said rotor driver and to an external source of track selection information, for recording the track position of said head, for calculating a track seeking command in response to known head position and said track selection information, and for commanding said head to move from a known departure track to a requested destination track during a track seeking operation by commanding at said rotor a first head position spatial increment of maximum forward direction acceleration followed by a similar head position spatial increment of maximum reverse direction acceleration and then by commanding adaptively a slewing rate dependent upon incremental quadrature crossing head position information from said head position transducer until said destination track is reached,
• a position dependent closed loop servo connected to said head position transducer and to said rotor driver for operatively controlling said driver to keep said head positioned within a selected one of said data tracks during read and/or write operations, said loop being opened during track seeking operations,
• a fine position closed loop servo connected to said driver and further including a single, data masked servo sector on said disk containing track centerline servo control data therein readible by said head, a sample and hold circuit connected to said head during passes over said sector for holding control data read therefrom, and correction signal generator means for generating an offset signal for application to said driver to promote and maintain track centerline alignment of said head during read and write operations, said fine position loop being opened during track seeking operations.

In a data storage device including a rotating rigid magnetic medium data storage disk, a read and write head held in close proximity to the surface of said disk by the air-bearing effect, and a head carriage mechanism for positioning said head at one of a multiplicity of concentric data tracks during data read and/or write operations in substantially unrestricted data format within each track and for moving said head from track to track during track seeking operations of said device, the improvement comprising:

• driver means drivingly connected to said head carriage mechanism for arcuately moving said head from one track to a selected other track located beyond a predetermined minimum radial distance during an opened loop servo track seek movement characterized by a first spatial increment of maximum forward direction acceleration of said carriage for about half the radial distance between said tracks and by a second similar increment of maximum reverse direction acceleration until said mechanism reaches reaches the vicinity of said selected other track, and for closed loop generally constant velocity microstepping of said mechanism within said minimum radial distance in small radial increments from track to track until said other track is reached, and for maintaining said head accurately within a selected track during data read and write operations,
• a summing circuit connected to drive said driver means,
• coarse servo control loop means including coarse position sensor means mechanically linked to said carriage mechanism for sensing radial position of said head relative to said tracks, and coarse position feedback control loop means connected to said driver means through said summing circuit for controlling said driver means to keep said head positioned within each said selected one of said defined tracks during read and write operations,
• index detector means electromechanically coupled to said disk for detecting each rotation thereof and generating an index signal,
• fine position servo control loop means including a single data-masked servo sector region on the surface of said disk containing servo information therein, sample and hold means connected to said head for sampling and holding said servo information read in said servo sector for each revolution of said disk, correction signal generator means connected to said sample and hold means for generating offset signals, and analog to digital converter means connected to said correction signal generator means, for converting said offet signals into digital values,
• programmed digital microprocessor means connected to said analog to digital converter means, said index detector means, said coarse servo control loop means and to a source of an externally supplied digital track selection command signal, and including clocked latch means, and digital to analog converter means drivingly connected to said driver means through said summing network for calculating and supplying a digital head positioning signal directly to said driver means in order to move said head from a predetermined departure track to a predetermined destination track, said head positioning signal overriding said summing circuit during acceleration phases of track seeking operations, for calculating and supplying a track microstepping head positioning signal to said driver means through said digital to analog converter means and said summing network during track seek microstepping, and for calculating and applying a fine position offset signal to said driver means through said digital to analog converter means and said summing network to maintain said head in centerline alignment in said track during read and/or write operations interactively with said coarse servo control loop means.

In a data storage method including the steps of rotating a data storage disk at a constant velocity, providing a multiplicity of concentric data tracks on the major surfaces thereof, reading and/or writing data from and to said tracks with at least one data transducer head structure in close proximity to said disk surfaces, and moving said structure from a departure track to a destination track during track seeking operations, the improved method comprising:

• moving said head structure across said multiplicity of concentric data tracks with a bidirectionally rotatable electromechanical rotor journalled to said frame adjacent to said disk and secured to said rotor at the other end thereof,
• rotating said structure with bidirectional rotor driver means connected to said rotor to maintain said head within a selected data track during read and/or write operations and to move said head from a departure track to a destination track during track seeking operations,
• providing a polyphase signal responsive to position of said head structure relative to said frame with a head position transducer,
• providing track selection information to head controller means connected to said head position transducer, said rotor driver and to an external source of track selection information, and then
• recording the track position of said head structure,
• calculating a track seeking command in response to known head position and said track selection information,
• commanding said head to move from a known departure track to a requested destination track during a track seeking operation by commanding at said rotor a first head position spatial increment of maximum forward direction acceleration followed by a similar head position spatial increment of maximum reverse direction acceleration and then by commanding adaptively a slewing rate dependent upon incremental head structure position information from said head position transducer until said destination track is reached, and
• operatively controlling said driver to keep said head positioned within a selected one of said data tracks during read and/or write operations with a position dependent, coarse position closed loop servo connected to said head position transducer and to said rotor driver and overriding said coarse position loop to keep it open during track seeking operations,
• providing a fine position closed loop servo connected to said driver and further including:
• providing a single, data masked servo sector on a data surface of said disk,
• prerecording track centerline servo control data in said servo sector,
• reading said data with a head of said structure adjacent to said surface,
• sampling and holding data read by said head during passes over said sector and generating an offset correction signal,
• applying said offset signal to said driver to promote and maintain track centerline alignment of said head during read and/or write operations, and
• overriding said fine position servo loop during track seeking operations.

In a data storage device including a frame, a data storage disk journalled to the frame and rotatingly driven by motor means at a constant velocity and characterized by a multiplicity of concentric data tracks on the major surfaces thereof, at least one data transducer head structure in close proximity to said disk surfaces, the improvement comprising:

• a bidirectionally moveable electromechanical mover mounted to said frame adjacent to said disk,
• a head mounting structure securing said head at one end thereof and secured to said mover at the other end thereof for moving said head across said multiplicity of concentric data tracks,
• bidirectional mover driver means connected to said mover for moving said structure to maintain it within a selected data track during read and/or write operations and to move said structure from a departure track to a destination track during track seeking operations,
• a head position transducer providing a polyphase position signal in response to sensed actual position of said head structure relative to said frame,
• head controller means connected to said head position transducer, said mover driver and to an external source of track selection information, for recording the present track position of said head structure, for calculating a track seeking command in response to known head position and said track selection information, and for commanding said head to move from a known departure track to a requested destination track during a track seeking operation by commanding at said mover a first head position spatial increment of maximum forward direction acceleration followed by a similar head position spatial increment of maximum reverse direction acceleration and then by commanding adaptively a slewing rate dependent upon said polyphase incremental head structure position information from said head position transducer until said destination track is reached,
• a position dependent closed loop servo connected to said head position transducer and to said mover driver for operatively controlling said driver to keep said head positioned within a selected one of said data tracks during read and/or write operations, said loop being open during track seeking operations until occurrence of adaptively commanded slewing,
• a time sampled fine position closed loop servo connected to said driver and further including a single, data masked servo sector on a data surface of said disk containing track centerline servo control data therein readible once per disk revolution by a head of said structure adjacent to said surface, a sample and hold circuit connected to said head during passes over said sector for holding sampled control data read therefrom, and correction signal generator means for generating an offset signal for application to said driver through said position dependent closed loop servo to promote and maintain track centerline alignment of said head during read and write operations, said fine position loop being opened during track seeking operations.

In a data storage device including a frame, a data storage disk journalled to the frame and rotatingly driven by motor means at a constant velocity and characterized by a multiplicity of concentric data tracks on the major surfaces thereof, at least one data transducer head structure in close proximity to said disk surfaces, the improvement comprising:

• a bidirectionally moveable electromechanical mover mounted to said frame adjacent to said disk,
• a head mounting structure securing said head at one end thereof and secured to said mover at the other end thereof for moving said head across said multiplicity of concentric data tracks,
• bidirectional mover driver means connected to said mover for moving said structure to maintain it within a selected data track during read and/or write operations and to move said structure from a departure track to a destination track during track seeking operations,
• data track stabilization means including said mover for stabilizing said structure within a range between the boundaries of each said data track,
• head controller means connected to said mover driver means and to an external source of track selection information, for commanding said mover to move said head from a known departure track to a requested destination track during a track seeking operation until said destination track is reached,
• a time sampled fine position closed loop servo including said head controller means and further including a single, data masked servo sector on a data surface of said disk containing track centerline servo control data therein readible once per revolution by a head of said structure adjacent to said surface, a sample and hold circuit connected to said head during passes over said sector for holding sampled control data read therefrom, and correction signal generator means for generating an offset signal for application to said driver means through said position dependent closed loop servo to promote and maintain track centerline alignment of said head during read and write operations.

In a data storage method including the steps of rotating a plurality of commonly journalled rigid data storage disks at a constant velocity, providing a multiplicity of aligned concentric data track locations on data storage major surfaces of said disks, reading and/or writing data from and to said tracks with commonly mounted data transducers held in close proximity to said disk surfaces by air-bearing effect, and moving said structure from a departure track to a destination track during track seeking operations, the improved method comprising:

• providing a bidirectionally moveable electromechanical mover for maintaining each said transducer within a selected data track location during read and/or write operations and for moving said transducer from a departure track location to a destination track location during track seeking operations,
• providing a transducer position encoder for generating a polyphase signal responsive to position of said mover relative to said frame and for providing binary track boundary marking signals,
• providing a reference track signal corresponding to a reference track location,
• providing at least one servo sector on a said surface with prerecorded track centerline servo control data for each data track location in the form of a first occurring marker burst of constant frequency radially offset in one direction from track location centerline and a second occurring marker burst of constant frequency radially offset in the opposite direction from track location centerline,
• providing track selection information from an external source,
• providing controller means including programmed digital microprocessor means for:
• determining track location of said transducers by calibrating a digital track counter with said reference track signal and by incrementing and decrementing said track counter with said binary track boundary marking signals as said mover moves said transducers away from and toward said reference track,
• calculating a track seeking command in response to present track location of said transducers and said track selection information,
• commanding said mover to move said transducers from a known departure track location to a selected track location during a track seek operation by commanding said mover to accelerate for a first spatial increment of movement and to decelerate for a second spatial increment of movement and by commanding adaptively a slewing rate dependent upon said binary track boundary marking signals from said transducer encoder until said destination track is reached,
• operatively controlling said mover by a control servo to keep said transducers positioned in substantial alignment with track location centerline of a selected one of said data track locations during data read and/or write operations, by repeatedly:
• separately reading and holding peak amplitude values of said first and second occurring marker bursts,
• comparing said held values to provide an offset signal,
• calculating a transducer position correction signal from said offset signal, and
• applying said correction signal to said mover to correct transducer position to track centerline alignment.

In a data storage device including a frame, a plurality of non-removeable rigid rotating data storage disks commonly journalled to said frame, a plurality of data transducers travelling in close proximity to each major data storage and retrieval surface of each said disk upon an air-bearing cushion, and electrically powered transducer mover means for commonly moving said transducer among aligned concentric data track locations of said surfaces in response to externally supplied track selection information, an improved transducer mover control system comprising:

• reference track sensor means for sensing a reference track location,
• transducer position encoder means for generating a polyphase signal responsive to position of said transducer mover means relative to said frame and for providing binary track boundary marking signals,
• at least one servo sector on a said surface having prerecorded track centerline servo control data for each data track location in the form of a first occurring marker burst of predetermined frequency radially offset in one direction from track centerline and a second occurring marker burst of predetermined frequency radially offset in the opposite direction from track centerline,
• controller means comprising programmed digital microprocessor means, memory means, analog to digital converter means, and digital to analog converter means, said controller means having data inputs connected to said reference track sensor means, said transducer position encoder means, and a said transducer reading said servo sector bursts, and having a control output connected to said mover means, said controller means for:
• recording track location of said transducers and including a digital track counter initialized by a signal from said reference track sensor means and which is incremented and decremented by said binary track boundary marking signals as said mover means moves said transducers relatively away from and toward said reference track,
• calculating a desired track seek command from recorded present track location and said externally supplied track selection information,
• commanding said mover means to move said transducers from said presently recorded track location to said desired track location, including means for commanding said mover means to accelerate for a first spatial increment of movement and to decelerate for a second spatial increment of movement and for commanding said mover means to move at an adaptive slewing rate dependent upon said binary track boundary marking signals until said desired track location is reached by said transducers,
• closed loop servo means for controlling said mover means to keep said transducers positioned in substantial alignment with track centerline of each selected data track location during read and/or write operations, and further comprising:
• peak amplitude detection and holding means for reading and holding peak amplitude values of said first and second occurring marker bursts,
• comparator means for comparing said held peak amplitude values to generate an offset signal,
• correction signal calculation means for calculating a transducer position correction signal from said offset signal, and
• correction signal application means including said digital to analog converter means for applying said correction signal to said mover means to correct transducer position to achieve track centerline alignment.