System and a method for controlling position of a magnetic head relative to a servo track of a tape by optical detection of an edge of the tape
AssigneeTandberg Data A/S
InventorPer O. Pahr
Life of this patent
Estimating the term…
Abstract
A method and apparatus performs the detection of an edge of a tape and further controls the read/write head to position itself relative to the detected edge. An array of photodetectors in an integrated circuit chip senses the intensity of light illuminating the chip with the tape running between the light source and the photodetectors. A light-to-dark transition is formed which is indicative of the edge of the tape.
Claims19
An apparatus for controlling the position of a magnetic head relative to the detection of a servo track of a tape, said tape comprising a format with at least one dedicated servo track, said at least one dedicated servo track correlated with respect to an edge of said tape, comprising:
- a matrix of photodetectors in an integrated circuit chip disposed behind said tape wherein the position of each photodetector in said matrix is known from the manufacture of said chip and each photodetector generates an electrical signal corresponding to the intensity of light incident thereon;
- illumination means for projecting light on said tape and said matrix so that said tape casts a shadow on said matrix wherein said shadow has a transition region at the tape edges from light to dark covering a plurality of photodetectors in said matrix;
- analyzing means for processing signals from said photodetectors in said transition region to determine the location, relative to said known photodetector positions, of a sharpest light-to-dark transition wherein the location of a servo track of said tape is determined by the location of said sharpest light-to-dark transition;
- and
- positioning means responsive to the location of said servo track for positioning said head relative to said servo track of said tape.
A method for controlling the position of a magnetic head relative to the detection of a servo track of a tape, said tape comprising a format with at least one dedicated servo track, said at least one servo track correlated with respect to an edge of said tape, comprising:
- disposing said tape in front of a matrix of photodetectors in an integrated circuit chip, the position of each photodetector in said matrix being known from the manufacture of said chip, wherein each photodetector generates an electrical signal corresponding to the intensity of light incident thereon;
- illuminating said tape and said matrix so that said tape casts a shadow on said matrix, said shadow having a transition region at the tape edges from light to dark covering a plurality of photodetectors in said matrix;
- analyzing the signals from said photodetectors in said transition region to determine the location, relative to said known photodetector positions, of a sharpest light-to-dark transition;
- using the location of said sharpest light-to-dark transition as the location of a servo track of said tape;
- and
- positioning said magnetic head relative to said servo track of said tape.
Dependencies are inferred from the claim text.