Bootstrap method for writing servo tracks on a disk drive

Details Bootstrap method for writing servo tracks on a disk drive Bootstrap method for writing servo tracks on a disk drive

1994-11-21

1996-07-30

Psitos, Aristotelis

Dynamic magnetic information storage or retrieval

Automatic control of a recorder mechanism

Controlling the head

360 7704, 360 7706, G11B 5012

Patent

active

055417841

ABSTRACT:
A method for defining and writing parallel and concentric magnetic signal tracks to a spinning disk surface of a magnetic data storage disk drive system using the components of the Head Disk Assembly (HDA) implemented by an appropriately programmed digital signal central processing unit (CPU) or micro code in an integrated circuit (IC) and a digital signal random access memory RAM is described wherein an initial magnetic signal track is written under least (minimum) energy equilibrium conditions with undulating boundaries and a meandering center line relative to axes of the spinning disk surface for one revolution of the surface. Then servoing to an edge of the just written track, a digitized position signal table is created in memory for storing digital position signals representing the amplitude of the signals read from n sampling points per disk revolution over a number of disk revolutions, where n is determined with reference to `Nyquist criteria`. A comparison/demand signal is derived by the CPU for input to the serve controller for each sampling point by first obtaining a target position signal comprising an average of the digitized position signals stored in the memory table and the just read digitized signal for that sampling point and by then comparing that target position signal to the just read digitizing position signals. The resulting current command signal energizing the actuator is normalized, and variation therein thereafter clamped in steps to bring the slider head to a quiet, least energy equilibrium or coast status relative to the spinning disk surface. A second memory table is generated and stores coast digital position signals for the n sampling points for a plurality of coast or least energy disk revolutions. Servo position then is initiated using averaged values in the second memory table such that any position error signal command to the actuator is a response to random noise or forces. Then preserving the least energy equilibrium state to the extent possible, a subsequent track of servo burst pattern is written onto and around the disk and the procedure repeated referencing the edge of the newly written track. A fiducial track concentric with the axes of the spinning disk is defined by each two iterations of the procedure after writing of the initial track. In this manner track densities in excess of 10,000 tracks per inch (track pitches<100 .mu.in.) can be reliably achieved.

REFERENCES:
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patent: 5416652 (1995-05-01), Lewis
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Fowler and Granger-Brown, "Regenerative Clock Technique for Servo Track Writers," IBM Technical Disclosure Bulletin, vol. 33, No. 5, pp. 310-11.

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