Method and apparatus utilizing magnetic field sensing for detecting discontinuities in a conductor member associated with a glass sheet
AssigneePPG Industries, Inc.
InventorHarry S. Koontz
Life of this patent
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Abstract
A method and apparatus for detecting discontinuities in electric conductor heating lines in automobile heated back lights is disclosed. The apparatus includes a "Hall effect" probe, a microprocessor, a display, a stepping motor drive, an optical scanner and associated circuitry. The method includes the steps of energizing the heating grid and moving a Hall effect probe in the vicinity of each conductor line. Any heater line having discontinuity will lack a detectable magnetic field.
Claims13
A method of detecting electrical discontinuities in a plurality of electrically connected conductive resistive heater grid lines disposed on a major surface of a glass sheet, comprising the steps of:
- applying electric current to the heater grid lines;
- providing a magnetic field detection means in spaced relation to the glass sheet;
- moving the glass sheet and said magnetic field detection means relative to one another;
- wherein said magnetic field detection means is disposed nearer to said glass sheet major surface on which the grid lines are disposed than to the opposite major surface of the glass sheet;
- wherein said detection means detects the magnetic field associated with each of the grid lines;
- and
- providing information about the magnetic field associated with each of the grid lines in response to said detection means detecting step, wherein the lack of a detectable magnetic field associated with any particular grid line(s) denotes electrical discontinuity of said any particular grid line(s).
A method of detecting electrical discontinuities in a plurality of electrically connected conductive resistive heater grid lines disposed on a major surface of a glass sheet, comprising the steps of:
- providing a magnetic field detection means in spaced relation to the glass sheet;
- applying electric current to the heater grid lines;
- moving the glass sheet and said magnetic field detection means relative to one another;
- wherein said magnetic field detection means is disposed nearer to said glass sheet major surface on which the grid lines are disposed than to the opposite major surface of the glass sheet;
- detecting the leading edge of the glass sheet;
- automatically determining the expected/proper location of each of the grid lines with reference to said glass sheet leading edge, in response to said edge detecting step;
- and
- providing information about the magnetic field detected by the magnetic field detection means at each of said automatically determined proper locations, wherein the lack of a detectable/discernible magnetic field which should be associated with each said determined proper location, denotes electrical discontinuity of or total absence of the grid line(s) which should be located at said proper location(s) whereat no magnetic field is detectable.
Dependencies are inferred from the claim text.