Electrophotographic image forming apparatus with non-uniformity correction of recording elements

Abstract

An electrophotographic printer uses plural recording elements such as LEDs for grey level recording. Redundant memory tables are provided that store redundant, but different, correction factors for correcting for nonuniformities of the LEDs at different grey levels. A nonlinear exposure clocking system is also provided for generating clock pulses at non-uniform intervals for use in controlling exposure durations for recording pixels. The clocking system includes a memory for storing binary signals that may be clocked out of a register and used as exposure clock pulses. The clock memory also includes redundant, but different, sets of possible clock pulses. As each new line of data is recorded, a signal is used to select one of the redundant sets of correction factors and a corresponding one of the redundant sets of exposure clock pulses. The use of this line-by-line change of exposure conditions tends to minimize production of image artifacts as errors in exposure by a particular LED are not continued from recording line to recording line.

Dependencies are inferred from the claim text.