Patent ID: 8736894
Filing Date: 2014-05-27
Classification: G03G,H04N

Abstract:
1. A method of producing correction data for a printer, comprising: arranging a plurality of rotatable imaging members along a receiver feed path in the printer; arranging one or more period sensors in operative arrangement with respective rotatable imaging members, the period sensors sensing a period and a phase of the respective rotatable imaging members; printing a test image using the rotatable imaging members and simultaneously using the period sensors to record the respective periods and phases of the corresponding rotatable imaging members, the test image defining an aim density pattern; measuring the printed test image along a selected measurement direction, determining a reproduced density pattern from the measurements, and determining a reproduction error signal using the aim density pattern and the reproduced density pattern; a member-variation-determining step of, for each period sensor, determining a respective autocorrelation of the reproduction error signal for the corresponding period and, if the determined autocorrelation exceeds a selected threshold, decomposing the reproduction error signal at the corresponding period to determine a respective member-variation signal and removing the determined respective member-variation signal from the reproduction error signal to produce an adjusted reproduction error signal and a respective adjusted member variation signal; a remaining-variation-determining step of, after the member-variation-determining step, separating the adjusted reproduction error signal into one or more remaining-variation signals, each having a respective significance; a modifying step of, if the significance of any of the remaining-variation signals exceeds a selected threshold, modifying the adjusted reproduction error signal by removing that remaining-variation signal from the adjusted reproduction error signal and producing a respective adjusted remaining-variation signal; repeating the remaining-variation-determining and modifying steps until no remaining-variation signal has significance exceeding the selected threshold; and a correction step of automatically producing a correction signal using the adjusted member-variation signals and the adjusted remaining-variation signals using a processor, wherein the correction signal varies with the determined phases of the rotatable imaging members having autocorrelations that exceed the selected threshold; using the correction signal to print image data using the printer, thereby compensating for banding artifacts.