A control system and method for simultaneously regulating the operation of a plurality of different types of switching power converters. The system utilizes in regulating the power converters sampled data and nonlinear feedback control loops.

Power converter circuitry and method

A servo track following system for positioning a moving read/write head relative to a magnetic storage disc. A plurality of servo tracks are recorded in sectors on the disc for identifying radial positions or informational tracks. The servo tracks have a nonuniform radial track density varying from more dense at the periphery of the disc to less dense at the interior, established with a method that allows the unique performance characteristics of the head to determine the actual spacing of the tracks. A clock track is written by writing a single pulse on a fixed clock track head, phase-lock looping to an intermediate clock track, which is written on a moving head, and then phase-lock looping up to the final clock track which is written on the fixed clock track head. Radial track density is then determined by moving a head to a limit stop and writing a reference track. Thereafter, the head is displaced an amount sufficient to reduce the amplitude of the reference track by a predetermined percentage which is related to the ultimate average track density. Thereafter, another reference track is written and the head is again stepped away from the second reference track an amount sufficient to again reduce the amplitude of the reference track by a predetermined percentage. This is continued until the disc is filled with reference tracks. If the average track density thus achieved is unsatisfactory, the reduction number is adjusted and the process is repeated. Once the correct reduction number is determined for a predetermined average track density, the servo tracks are written by alternatively writing servo and reference in alternating servo and informational sectors. The reduction number is used to determine the pitch of all tracks.

Embedded servo track following system and method for writing servo tracks

A misposition correction system for correcting misposition errors due to spindle runout and other slowly varying errors in a servo positioning system of a magnetic disk storage device The system includes means for dynamically measuring misposition error with respect to a data track centerline using an anti-aliasing analog filter, means for digitizing the measured analog signal and for removing selected harmonics of the fundamental-frequency of the resulting cyclic error signal, means for transforming the digitized error signal by a matched digital filter whose transfer function contains independently adjustable DC gain, fundamental-frequency gain, and phase lead components thereby to generate a misposition error correction signal that matches the electrical and mechanical response characteristics of the servo system Further, the system includes means to iteratively refine the correction signal by re-applying it to the servo controller when measuring misposition errors with respect to the data track centerline The system stores separate misposition correction signals for each transducer on the disk so that one of several correction signals can be selected depending on which transducer in the device is selected The system further includes means for generating a bias force correction signal to correct for non-linear position errors resulting from variations in bias forces acting on the transducer carriage over its range of radial displacement

Adaptive misposition correcting method and apparatus for magnetic disk servo system

A track means defined by magnetic recording media on a substrate, the media along the track means having two levels, one for recording of data, and the other for recording of servo information, wherein recorded magnetic transitions at the second level define the servo information, the transitions arrayed along the track means as groups of converging lines which extend in crosswise or spanwise relation to multiple tracks. The data is recorded without any wasted magnetic space between tracks (zero guardband) using alternating angles (azimuthal) of magnetic orientation so that they do not interfere with each other when read. The read bead cores or gaps may be "oriented" to read recorded data transitions extending at different angles relative to track length direction.

Systems using superimposed, orthogonal buried servo signals

A magnetic tape comprises a substrate having on one side thereof a magnetic layer serving as a recording surface, and on the other side thereof at least two layers containing inorganic particles which serve as a non-recording surface, wherein said magnetic tape has a region on the side of the non-recording surface along the longitudinal direction of the tape in which a regular pattern for servo tracking having different optical properties from the other major region of the side of the non-recording surface is or can be formed. The layers on the non-recording surface are characterized in that the inorganic particles in the outermost layer are larger than the inorganic particles in the underlying layer(s).

Multiple-layer backcoating for magnetic tape

Magnetic track following servo system

A phase-locked oscillator useful for a magnetic storage system receives timing pulses from a means for generating reference pulses connected to a rotary storage medium. Variations in the angular velocity and phase of the rotating storage medium result in corresponding variations of frequency and phase of a voltagecontrolled oscillator, which controls the write or record circuitry. During readout, the phase-locked oscillator is employed to locate the selected data records accurately.

Frank J Sordello

Papers

Magnetic track following servo system

Phase locked oscillator for storage apparatus

Digital-analog servo system

Digital comparison-to-analog signal converter

Dual servo loop oscillator frequency synchronizing circuitry