US 4,371,904 A · Flexible magnetic disk system

Abstract

A simple flexible magnetic disk memory system is provided which enables precise positioning of a read/write head to follow a data track, despite non-uniform expansion or contraction of the disk. Several positioning sectors of the disk are formed which have positioning tracks recorded thereon, and several corresponding holes are punched in the disk to enable an optical sensor to determine the sector locations. Although a step motor positions a head at the approximate middle of a selected data track, an analog circuit repeatedly adjusts the head location as each positioning sector passes the head. Four positioning sectors can be used which are each aligned with or angled by 90.degree. from the direction of machining of the sheet material of which the disk was made, to minimize track run-out in each data region that lies between positioning sectors.

Claims8

Dependent claims

In a flexible disk drive system which includes a rotatable flexible disk and a disk having a read/write head mounted on a carriage to move radially along the rotating disk, the improvement wherein:

said disk defines a plurality of narrow positioning sectors angularly spaced about the disk, and a corresponding plurality of sector-indicating holes in the disk with each hole angularly spaced by the same amount from its corresponding positioning sector, each positioning sector defining a plurality of magnetically recorded positioning tracks;
said disk drive including optical sensor means positioned to detect said holes and head adjustment circuit means responsive to said optical sensor means and the output of said head for generating an error signal indicating the deviation of the head from a positioning track;
and motor means responsive to said error signal for adjusting the radial position of said head.

A disk drive system including:

a circular disk having a magnetic surface and a plurality of radially spaced concentric data tracks recorded thereon;
means for mounting said disk for rotation about the axis thereof;
a head for writing on or reading from said disk surface;
head positioning means for radially moving said head along said disk surface including first means for moving said head in steps equal to multiples of a predetermined nominal spacing between adjacent data tracks;
said disk surface having recorded thereon a plurality of positioning sectors angularly spaced around said disk axis such that they successively move into operative coupling with said head, each positioning sector having a plurality of radially spaced positioning tracks oriented such that each boundary between adjacent positioning tracks lies along the center line of one of said data tracks;
said disk carrying a plurality of sector indicating marks, each positioned in fixed relationship with respect to a different one of said positioning sectors;
sensor means mounted to said sense the movement of each sector indicating mark therepast to indicate the operative coupling of one of said positioning sectors with said head;
and wherein
said head positioning means includes proportional control means responsive both to said sensor means sensing a sector indicating mark and to positioning track information read by said head for adjusting the radial position of said head by a fraction of said predetermined nominal spacing.

6 more elements

Dependencies are inferred from the claim text.

Flexible magnetic disk system

Life of this patent

Flexible magnetic disk system

Life of this patent

Abstract

Claims8