| 摘要 |
A charge roller displacement mechanism (30) prevents the build up of a sharply defined circumferential ring of contaminants on the surface of a charge roller (3) in an electrophotographic printing system, thereby reducing the severity of the print defect caused by the contaminants. By cyclically laterally displacing the charge roller (3) parallel to the longitudinal axis of a photoconductor drum (2) as the photoconductor drum (2) rotates, contaminants which reach the surface of the charge roller (3) will not form a sharply defined circumferential ring that interferes with the uniform charging of a photoconductor drum (2) charged by the charge roller (3). The charge roller displacement mechanism includes a first gear (31) that engages the gear (32) used to rotate paddles in a waste hopper of an electrophotographic printer cartridge (10). A second gear (34) engages the first gear (31) to provide a reduction of approximately 400 to 1. The charge roller (3) is forced against a face of the second gear (34) by a spring (35) or, alternatively, by angling the longitudinal axis of the charge roller (3) with respect to the longitudinal axis of the photoconductor drum (2). The face of the second gear (34) contacting the charge roller (3) includes cam (40). As the second gear (34) rotates, the charge roller (3) is laterally displaced across the surface of the photoconductor drum (2). The cam (40) is shaped so that one rotation of the second gear (34) corresponds to one cycle of displacement of the charge roller (3).
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