Banding Reduction in Electrophotographic Printer

摘要

The Banding is an image artifact that appears as light and dark bands periodically across a page. Banding can be classified into two categories: fine and rough ones. Fine banding artifact could be caused by the periodic vibration or motion of optical devices on the optical path with the excitation frequency of the polygon mirror motor. The periodic vibration is mainly related to excitation force due to an imbalance of the rotor part of polygon mirror motor or the structural weakness of laser scanning unit. The periodic motion is mainly caused by pyramidal errors of the polygon mirror motor. Rough banding artifact in printed images could be caused by the inaccurate motion or vibration of the OPC part or the fusing part driven by main driving unit. Printed image patterns have several frequencies, which can be obtained from the position of dots in a specific pattern of printed image and Fast Fourier Transform (FFT) result of the position data. The identified frequencies can be confirmed by referring to the tooth frequencies of the parts on the gearing table. This paper proposes a secure way to identify the causes of banding from FFT of the measured position data of dots in a specific pattern of printed images. The experiment was conducted to verify the identified causes of bandings.