Apparatus and method for monitoring web conductivity
AssigneeImperial Chemical Industries PLC
InventorAnthony R. Blythe
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Abstract
The invention provides an apparatus and method for monitoring the electrical conductivity of a web surface in which a forwardly moving web is exposed to an electrical field generated by a forwardly extending high voltage source so disposed adjacent the web as to induce a transverse redistribution of the electrical charges present on the web surface, the electrical field signal generated by the redistributed surface charges of opposite polarity to that of the source being monitored by a suitable field detector.
Claims10
A method of assessing the electrical conductivity of a surface of a moving web comprising feeding the web in a forward direction, generating an electrical field by supplying a high voltage to an electrode extending in said forward direction and disposed adjacent the web, exposing said surface of the moving web to said electrical field so as to induce a redistribution, in a direction transverse to said forward direction, of the electrical charges present on that surface, whereby an electrical field signal is generated by the redistributed surface charges of opposite polarity to that of the electrode, and monitoring said electrical field signal.
An apparatus for assessing the electrical conductivity of a surface of a web travelling in a forward direction along a web path, said apparatus comprising an elongate electrode to be disposed adjacent the web path with the major axis of the electrode extending in said forward direction, a charging assembly to raise the electrode to an electrical potential sufficient to induce a redistribution, in a direction transverse to said forward direction, of the electrical charges present on the web surface, and an electrical field-sensitive detector assembly, disposed adjacent the web path to monitor the electrical field signal generated by the redistributed surface charges of opposite polarity to that of the electrode.
Dependencies are inferred from the claim text.