CIRCUIT AND METHOD OF REVISING BELT DEFECT OF LASER BEAM PRINTER

摘要

PURPOSE: A belt defect revising circuit is provided to be capable of effectively recovering a mechanical defect generated at a belt edge. CONSTITUTION: A defect judging part(600) judges a mechanical defect of a belt edge according to whether an absolute value of a subtraction value is over a predetermined defect judgment value, wherein the subtraction value is obtained by subtracting a belt edge length of a previous scan line from that of a current scan line. The defect judging part(600) outputs a defect operation signal when the currently measured belt edge is treated as the mechanical defect part and a normal operation signal when it is treated as a normal operation part. A normal accumulating part(602) is enabled based on the normal operation signal and outputs a correction belt edge length, which is calculated by applying the belt edge lengths of the current and previous scan lines according to a weighted value rate. A defect application part(604) is enabled based on the defect operation signal and outputs a correction belt edge length, which is calculated by applying a directional component average value of all previous scan lines to the belt edge length of the previous scan line. A multiplexer(606) selectively outputs the correction belt edge lengths from the normal accumulating part(602) and the defect application part(604) in response to the normal and defect operation signals.