Apparatus and method for measuring lateral charge distribution on a moving web

摘要

Apparatus for measuring lateral charge distribution on a moving web includes a cylindrical roller having at least a pair of charge measuring segments on the cylinder surface which are electrically isolated from each other and aligned end-to-end in the direction of the axis of rotation of the cylinder. Each of the measurement segments is adapted to be connected to a separate electrometer. The cylinder is mounted on a support to move the cylinder in a direction perpendicular to the longitudinal direction of conveyance of the web over the surface of the cylinder. A measuring device for measuring lateral displacement of the cylinder is used for calculation of the proportion of web area in contact with one segment relative to the total web area in contact with both segments. The proportionate measured charge represents the integral charge on a fraction of the web and by taking periodic measurements as the cylinder is moved laterally across the web, a profile of lateral integral charge distribution is determined. The corresponding profile of lateral charge density distribution is then readily determined by differentiation of the charge distribution profile curve.