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US 5,294,803 AGranted
System and a method for optically detecting an edge of a 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.
Claims57
A method for detecting an edge of a tape comprising the steps of:
- 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 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;
- and
- using the location of said sharpest light-to-dark transition as the location of the edge of said tape.
2 more elements
A method for detecting an edge of a tape comprising the steps of:
- disposing the tape in front of a matrix of photodetectors and 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 from light to dark covering a plurality of photodetectors in said matrix;
- analyzing the signals from said photodetectors using spatial averaging to determine the contribution of current from each photodetector on a node of a resistive network to determine a location, relative to said known photodetector positions, of a sharpest light-to-dark transition;
- and
- using the location of said sharpest light-to-dark transition as the location of the edge of said tape.
2 more elements
A method for controlling the position of a magnetic head relative to the detection of an edge of a tape comprising the steps of:
- 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 the tape casts a shadow on said matrix, said shadow having a transition region 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 the edge of said tape;
- and
- positioning the magnetic head relative to the edge of said tape.
3 more elements
An apparatus for detecting an edge of a 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 from light to dark covering a plurality of photodetectors in said matrix;
- and
- 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 the edge of said tape is the location of said sharpest light-to-dark transition.
1 more element
An apparatus for detecting an edge of a 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 onto the tape and said matrix so that said tape casts a shadow on said matrix wherein said shadow has a transition region from light to dark covering a plurality of photodetectors in said matrix;
- and
- analyzing means for processing signals from said photodetectors using spatial averaging to determine the contribution of current from each photodetector on a node of a resistive network to determine the location, relative to said known photodetector positions, of a sharpest light-to-dark transition wherein the location of said edge of said tape is the location of said sharpest light-to-dark transition.
1 more element
An apparatus for controlling the position of a magnetic head relative to the detection of an edge of a 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 from light to dark covering a plurality of photodetectors;
- 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 the edge of said tape is the location of said sharpest light-to-dark transition;
- and
- positioning means responsive to the location of said edge for positioning said head relative to the edge of said tape.
2 more elements
Dependencies are inferred from the claim text.