Genrad, Inc.

Paul R Pilotte

Henry P Hall

A test method for a switch matrix (10) of a liquid-crystal display employs a signal source (40, 42) to drive a row line (20) of the matrix and employs current sensors (56, 58, and 60) to measure the resultant current flow. Errors are detected by observing departures of the measured currents from expected values. To increase the sensitivity of the current measurement to the capacitance in the location at which the associated column line (14, 16, or 18) intersects the driven row line (20), return connections for the source (40, 42) are made directly to the contact pads (26, 28) of the row lines not currently being driven and column lines not currently being sensed.

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Arlington, MA, United States of America

Paul R Pilotte