Magnetic disc calibration track with diminishing apertures

Claim 2

Apparatus for use in a disc file of a magnetic disc memory system to align, relative to an axial spindle, the position of a head unit having a read-head capable of performing transducing operations on a magnetic recording surface, comprising: a rotatable record disc interchangeably mounted on the spindle of the disc file and having a magnetic recording surface on a nonmagnetic substrate; and a calibration track pattern accurately positioned on said rotatable record disc and formed by providing nonmagnetic areas on the magnetic recording surface, the pattern being disposed on the record disc to provide signals from the read-head of the head unit which signals are indicative of the position of the read-head relative to the calibration pattern rotating with the record disc about the spindle; and wherein said calibration track pattern includes an aperture set having an aligning aperture and a boundary aperture of significantly different arc lengths on the record disc which produce signals from the read-head that are easily distinguished one from another by the time duration of the signals as the record disc rotates past the head unit about the spindle.

Claim 3

The invention in accordance with claim 1 wherein said calibration track pattern includes a plurality of aperture sets, the aligning apertures of different sets having different widths which provide for measuring the amount of displacement of the read-head relative to the calibration pattern rotating past the head unit.

Claim 4

The invention in accordance with claim 1 wherein said calibration track pattern includes a set of apertures having an aligning aperTure and an inner and an outer boundary aperture adjacent to the aligning aperture and located at a shorter and longer radial distance, respectively, relative to the aligning aperture of the record disc.

Claim 5

The invention in accordance with claim 3 wherein the aligning aperture and the boundary apertures are of different arc lengths on the record disc and produce signals from the read-head that are easily distinguished by the time duration of the signals as the record disc rotates past the head unit about the spindle.

Claim 6

Apparatus for use in a disc file to align, relative to an axial spindle, the position of a head unit having a read-head capable of performing transducing operations on a magnetic recording surface, comprising: a rotatable record disc interchangeably mounted on the spindle of the disc file and having a magnetic recording surface on a nonmagnetic substrate; an aligning aperture on said record disc formed by an aperture in the magnetic recording surface exposing an area of the nonmagnetic substrate; and an inner and an outer boundary aperture adjacent to the aligning aperture located at a shorter and longer radial distance, respectively, relative to the aligning aperture on the record disc, the aligning and boundary apertures forming a pattern disposed on the record disc to provide signals from the read-head of the multiple head unit which signals are indicative of the position of the read-head relative to the calibration pattern rotating with the record disc about the axial spindle.

Claim 7

Apparatus for use in a disc file to align, relative to an axial spindle, the position of a head unit having a read-head capable of performing transducing operations on a magnetic recording surface, comprising: a rotatable record disc interchangeably mounted on the spindle of the disc file and having a magnetic recording surface on a nonmagnetic substrate; an aligning aperture on said record disc formed by an aperture in the magnetic recording surface exposing an area of the nonmagnetic substrate; and an inner and an outer boundary aperture adjacent to the aligning aperture located at a shorter and longer radial distance, respectively, relative to the aligning aperture on the record disc, the aligning and boundary apertures forming a pattern disposed on the record disc to provide signals from the read-head of the multiple head unit which signals are indicative of the position of the read-head relative to the calibration pattern rotating with the record disc about the axial spindle.

Claim 8

The invention in accordance with claim 5 wherein said aligning aperture and said boundary apertures are of significantly different arc lengths on the record disc and produce signals from the read-head that are easily distinguished one from another by the time duration of the signals as the record disc rotates past the head unit about the spindle.

Claim 9

The invention in accordance with claim 5 wherein a plurality of aligning apertures are provided on an arc of the record disc, each aligning aperture having an inner and outer boundary aperture located adjacent to it, and said aligning apertures being of various widths to provide for measuring the amount of displacement of the multiple head unit relative to the arc common to the rotating aligning apertures.

Claim 10

The invention in accordance with claim 5 wherein said rotatable record disc has a magnetic recording surface of a thin film of cobalt plated on the nonmagnetic substrate, and said calibration pattern is formed by etching selected areas of the cobalt film to expose a surface of the nonmagnetic substrate.

Claim 11

Apparatus for use in a disc file of a magnetic disc memory system to align, relative to an axial spindle, the position of a multiple head unit having a plurality of read-heads capable of performing transducing operations on a magnetic recording surface, comprising: a rotatable record disc interchangeably mounted on the spindle of the disc file and having a magnetic recording surface on a nonmagnetic substrate; and a plurality of calibration track patterns formed by apertures in the magnetic recording surface exposing areas of the nonmagnetic substrate, and individual calibration track pattern accurately positioned on said rotatable record disc for different read-heads of the multiple head unit, each of said calibration patterns being disposed on the record disc to provide signals from a corresponding read-head of the multiple head unit which signals are indicative of the read-head position relative to the calibration track pattern rotating with the record disc about the spindle; wherein each of said calibration track patterns includes an aperture set having an aligning aperture and a boundary aperture of significantly different arc lengths on the record disc which produce signals distinguishable by their time duration from their respective read-heads as the record disc rotates past the head unit about the spindle.

Claim 12

Apparatus for use in a disc file of a magnetic disc memory system to align, relative to an axial spindle, the position of a multiple head unit having a plurality of read-heads capable of performing transducing operations on a magnetic recording surface, comprising: a rotatable record disc interchangeably mounted on the spindle of the disc file and having a magnetic recording surface on a nonmagnetic substrate; and a plurality of calibration track patterns formed by apertures in the magnetic recording surface exposing areas of the nonmagnetic substrate, and individual calibration track pattern accurately positioned on said rotatable record disc for different read-heads of the multiple head unit, each of said calibration patterns being disposed on the record disc to provide signals from a corresponding read-head of the multiple head unit which signals are indicative of the read-head position relative to the calibration track pattern rotating with the record disc about the spindle; wherein each of said calibration track patterns includes an aperture set having an aligning aperture and a boundary aperture of significantly different arc lengths on the record disc which produce signals distinguishable by their time duration from their respective read-heads as the record disc rotates past the head unit about the spindle.

Claim 13

The invention in accordance with claim 9 wherein each of said calibration track patTerns includes a plurality of aperture sets, the aligning aperture of different sets having different widths which provide for measuring the amount of displacement of the read-head relative to its calibration track pattern rotating with the record disc about the spindle.

Claim 14

The invention in accordance with claim 9 wherein each of said calibration track patterns includes a set of apertures having an aligning aperture and an inner and outer boundary aperture located at a corresponding shorter and longer radial distance relative to the aligning aperture on the record disc.

Claim 15

The invention in accordance with claim 11 wherein the alignment aperture and the inner and outer boundary apertures are sequentially rotated past the read-head to produce signals indicative of the direction of displacement of the read-head relative to the aligning aperture of the track pattern.

Claim 16

The invention in accordance with claim 11 wherein the aligning aperture and the boundary apertures are of significantly different arc lengths on the record disc and produce signals that are easily distinguished by the time duration of the signals as the record disc rotates past the head unit.