Rotating rigid disk data storage device

An improved data storage device comprising:

• a unitary base casting;
• a plurality of non-removable rotating rigid magnetic media data storage disks journalled to said base casting for common rotation relative thereto, each disk having a series of concentric data tracks for storing data;
• means for rotating said disks;
• a plurality of commonly mounted read/write data transducers held in close proximity to the major surfaces of said disks by air-bearing effect;
• moveable carriage means mounted to said base casting for commonly moving said data transducers relative to data tracks of said disks;
• electromechanical actuator means for moving said carriage means in response to analog electrical control signals;
• optical encoder means operative between said carriage means and said base casting for generating a plurality of periodic, phase related signals indicating position of said carriage means relative to said base casting;
• at least one of the data surfaces of said disks contaning servo sectors prerecorded with a plurality of first bursts offset from track centerline in a first radial direction for odd numbered tracks and offset from track centerline in a first radial direction for odd numbered tracks and offset from track centerline in an opposite second radial direction for even numbered tracks, and a plurality of second bursts adjacently interleaved between said first bursts, said second bursts being offset from track centerline in said second direction for odd numbered tracks and offset in said first direction for even numbered tracks, each said burst not being phase coherent with any other burst;
• one of said data transducers for reading every said servo sector during track following of a said data track location;
• sector boundary generator means operative between said disks and said base casting for generating electrical pulses indicative of boundaries of said servo sectors on said surface on which said bursts are prerecorded;
• peak detection means connected to said servo transducer for detecting and putting out average peak amplitude values for each burst read by said servo transducer;
• analog switch means connected to said optical encoder means and to said peak detector means for switching between said plurality of phase related position signals and said peak amplitude values of said bursts;
• analog to digital converter means connected to said analog switch means for converting each analog position signal and peak amplitude value received from said switch means into a digital word;
• user interface circuit means including transducer select circuitry connected to said data transducers and to a host system for receiving digital disk surface and data track selection control data and data to be written through a selected one of said transducers to a selected data track;
• programmed digital controller means connected to said analog to digital converter means, said analog switch means, said sector boundary generator means and said user interface means, for controlling said analog switch means, for receiving digital words from said analog to digital converter means and said disk surface and data track selection control data from said user interface means, and for calculating therefrom digital control words:
• for controlling said actuator means to move said carriage from a departure track location to a destination track location and to settle thereat during track seeking operations, and to maintain said transducers in track centerline alignment during track following operations;
• digital to analog converter means connected to said digital controller means for receiving said digital data control words and for converting them into proportional analog signal values;
• actuator driver amplifier means connected to said digital to analog converter means for amplifying said analog signal values and for powering said actuator to move in accordance with said values.

An improved data storage method comprising the steps of:

• rotating a plurality of rigid magnetic media data storage disks relative to a base,
• reading data from and writing data to major surfaces of said disks with read/write data transducers held in close proximity to said surfaces by air-bearing effect,
• positioning said data transducers at selected ones of a multiplicity of concentric data tracks on said surfaces with a current operated transducer mover mounted to said base,
• providing a plurality of phase related signals indicating transducer position relative to said base,
• prerecording at least one surface of one of said disks with a plurality of radial servo sectors, each sector prerecorded with a plurality of first bursts offset from track centerline in a first direction for odd numbered tracks and offset from track centerline position in a second direction for even numbered tracks, and prerecorded with a plurality of second bursts spatially interleaved between said first bursts and offset from track centerline in said second direction for odd numbered tracks and offset from track centerline in said first direction for even numbered tracks,
• detecting and putting out average peak amplitude values for each sector servo burst read by a transducer for said servo surface,
• switching in a controlled manner between said plurality of phase related signals and said peak amplitude values of said servo bursts,
• converting each switched analog signal into a digital word,
• receiving digital disk surface and track selection control data from a user interface,
• generating clock signals representing sector boundaries with tachometer means coupled mechanically to said disks,
• processing said converted digital words and said control data from said user interface to calculate digital control words in order to command digitally said current operated transducer mover to move from a departure data track location to a destination track location during track seek operations and in order to command digitally said transducer mover to adjust said transducers to data track centerline alignment during track following data read/write operations, and
• converting said digital commands into analog driving currents for application to said transducer mover.

An improved microprocessor-based servo control system for a rotating rigid disk data storage device including a base, at least one non-removable rotating data storage disk journalled to said base having data storage surfaces, means for rotating said disk, a data transducer for every data storage surface, moveable carriage means mounted to said base for moving said transducer relative to concentric data track locations defined on said surfaces, electromechanical actuator means for moving said carriage means in response to electrical analog signal values, position encoder means for signalling relative position of said transducer and said base including boundaries of said data tracks, track following and centering servo information prerecorded on at least one storage surface and readible by a said transducer associated with said servo surface and operating within servo transducer means, and user interface means for receiving digital disk data surface and track location control data from a host computer system, said improved servo control system comprising:

• programmed digital microprocessor means connected to said position encoder means, said servo transducer means and to said user interface means, for receiving digitized relative position data from said encoder means during track seeking operations, for receiving digitized track following and centering data from said servo transducer means during track following operations, and for receiving said data surface and track location control data from said user interface means from time to time, for calculating digital control words:
• for commanding said actuator means to move from a departure track location to a destination track location and to settle thereat based on said relative position data during track seeking, and for commanding said actuator means to maintain said transducer in track centerline alignment based on said track following and centering data during track following operations;
• digital to analog converter means connected to said microprocessor means for receiving and converting said digital control words into analog signal values,
• actuator driver amplifier means connected to said digital to analog converter means for receiving and amplifying said analog signal values and for applying them to operate said actuator means.