Lexmark International, Inc.

Craig Eric Hadady

Christopher Dane Jones

John Lemaster

Fei Chen

Keith Bryan Hardin

Philip Jerome Heink

Cary Patterson Ravitz

Thomas Austin Fields

Simarpreet Singh Rattan

A system and method for reducing scan line jitter caused by facet cut variation in scan systems employing a plurality of laser sources and a sensor for generating the timing for the laser sources. The system includes a controller for determining a unique time delay for each facet of the rotating mirror, and controlling the laser sources so that video provided by each laser source is delayed in a scan line by the unique time delay corresponding to the facet of the rotating mirror used in creating the scan line.

Laser scan unit for an imaging device

The invention describes a method and system for correcting linearity error of an electrophotographic device with a reduced number of lenses. The method and system insert additional time-slices in the data being processed by the electrophotographic device. The additional time-slices are inserted in the data in a predefined order based on a plurality of random numbers. The insertion of additional time-slices corrects the linearity error of the electrophotographic device.

Method and system for correcting the linearity error in electrophotographic devices

A system and method for reducing scan line jitter in laser scan systems employing a rotating mirror, including a controller for determining a unique time delay for each mirror facet and controlling laser sources so that video provided by each laser source is delayed in a scan line by the unique time delay corresponding to the mirror facet used in creating the scan line. The controller computes a facet map signature vector corresponding to each mirror facet matches the signature to a previously stored signature and assigns measured distance offset data to the mirror facets based upon the matching.

System and method for reducing scan line jitter in a laser scan unit for an imaging device

A method of minimizing visual artifacts resulting from a laser scan process in an electrophotographic machine, the electrophotographic machine including a photoconductive device having an image forming surface. The method including the steps of obtaining correction data relative to a bowed image and offsetting at least a portion of non-bowed image data dependent upon the correction data, and additionally dependent upon halftone cell growth of a halftone cell.

Method and apparatus for minimizing visual artifacts in images generated by an electrophotographic machine

An improved spread spectrum clock generator circuit is provided which automatically compensates for variations in passive component values and system gain and charge pump current in a Phase Locked Loop circuit. The pulse widths of the UP and DOWN outputs of the Phase Frequency Detector are monitored at particular intervals to determine the deviation error of these UP and DOWN signals, as compared to typical or nominal pulse-width durations. After an error is determined in the actual values of the pulse-width durations, the Phase Locked Loop (PLL) system is adjusted depending upon the magnitude and direction of the error signal. Changes in the PLL gain parameters, especially the VCO gain and charge pump current, have a significant effect on the PFD outputs, such that the width of the UP and DOWN signals vary as the frequency changes along the spread spectrum profile. At one portion of the spread spectrum profile, the &ldquo;peak&rdquo; (i.e., maximum) pulse width of these UP and DOWN signals will be a function of the spread spectrum's modulation profile and the PLL parameters. In addition to sampling for maximum pulse widths at the profile locations exhibiting peaks and valleys, the actual error profile may also exhibit a similarly large deviation from the target error profile at times just before the occurrence of the maximum peak and minimum peak (or &ldquo;valley&rdquo;). While determining precisely where within the profile these other substantial deviations occur is more difficult than monitoring the same signals at their maximum peaks, there are certain advantages to using the alternative locations along the error profile, which are described below.

Method and apparatus for compensating a spread spectrum clock generator

A method and apparatus provides for minimizing visual artifacts resulting from laser scan process direction position errors in an electrophotographic machine. The electrophotographic machine has defined therein a process direction, and includes a photoconductive device having an image forming surface. A printhead unit is provided for generating a laser beam, wherein the printhead unit includes optics for scanning the laser beam to form a plurality of scan lines extending across the photoconductive device in a scan direction which traverses the process direction. Adjacent scan lines of the plurality of scan lines are separated by a scan line separation distance. A controller is electrically coupled to the printhead unit for controlling the power of the laser beam during the scanning of an adjacent pair of scan lines to form a synthesized dot which lies at a synthesized position between the adjacent pair of scan lines.

Method and apparatus for minimizing visual artifacts generated by an electrophotographic machine during imaging

A method for compressing a data stream, where a first portion of the data stream is read into a window having a history buffer and look-ahead buffer. An index, based on a fourth portion of the data stream in the look-ahead buffer is used to select an entry in a pointer array. An initial entry in a record array is selected based on the pointer array entry. A third portion of the data stream is selected. The third portion is compared to a second portion in the look-ahead buffer. If the third portion does not match the second portion, then a subsequent entry in the record array is selected, and the is designated as the initial entry. These steps are repeated until either the third portion matches the second portion, or no more entries are left in the record array. When there are no more entries left in the record array, the second portion is written to the output file, and the first portion read into the window is incremented by a predetermined amount. When the third portion matches the second portion, the history buffer address of the third portion and a length value, representing how many bytes of the third portion and the second portion matched, are output to the output file, and the first portion read into the window is incremented by the number of bytes matched.

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Lexington, KY, United States of America

Craig Eric Hadady