A method of producing an optical panel assembly including the polarizing film in a continuous manner by laminating a polarizing film to a surface of a rectangular-shaped optical panel, is disclosed. An electronic sensor is attached to the back of the gadget. A determination is made as to whether the trace command is for a full trace or a differential trace, where the full trace traces all the one or more specified fields, and the differential trace traces specified fields only in response to the specified fields having a value that has changed during processing.