Xerox Corporation

Rosario A Bracco

Cathleen J Raker

Louis D Mailloux

Hung M Pham

Farhad D Rostamian

Daniel D Truong

Sue K Lam

Robert R Thompson, Jr

Cheryl A Pence

Hoan N Nguyen

George L Harer

Robert P Loce

David C Robinson

Michael John Martin

John A Durbin

Michael Branciforte

Joseph W Ward

Thomas Robson

Robert M Mara

Joseph A Mastrandrea

Thomas M Baretsky

James W Stevens

James O Mitchel

Daniel R Maurer

Carlos O Alva

Raymond L Mongeon

Anne Fitzpatrick

Ronald E Shaul

Patrick O Waller

Sue K Lam-Chon

Patricia A Papaleo

Colleen Tremaine

Reflex writing is a group of algorithms developed to maintain color registration in xerographic systems using multiple imagers, in which sequential color separations are written based on events in the spatial domain. The imaging system includes a raster output scanner imager for the black station and a light emitting diode bar for the color station. A simulated machine clock signal is generated based on a running average of a plurality of actual machine clock periods determined from pulses received from a photoreceptor module drive roll encoder. For each black scanline written the distance the belt travels is tracked using the simulated machine clock signal, and when the black latent image scanline has traveled the known distance between the two imagers, the light emitting diode scanline is written registered with respect to the raster output scanner scanline.

Hybrid imager printer using reflex writing to color register an image

A system and method for spatially matching the output of two imaging stations in an electro-photographic device by using a second order polynomial curve and a third order polynomial curve to approximate the non-linearity errors between the two imaging stations and using the second order polynomial curve and the third order polynomial curve to modify the frequency of a pixel clock.

System and method for reducing non-linearity errors between two imaging stations

There is provided a method for use with a printing machine having a movable imaging member and a projecting system for modulating a beam and projecting an image into the movable imaging member. The printing machine further includes a developer for application of developer material to the image projected onto the movable imaging member for transfer of the image to a print media sheet. The method, which is intended for use in controlling exposure of a test patch on the movable imaging member includes the steps of: a) providing a time-keeping device with the time-keeping device including a variable value which is either incrementable or decrementable; b) detecting a signal indicating that the movable imaging member is positioned relative to the beam in a selected orientation, wherein the movable imaging member passes by the beam at a selected speed; c) providing a reference value with the reference value varying as a function of the selected speed; d) in response to the detecting of (b), modulating the beam, relative to the movable imaging member, so as to expose a portion for the test patch; e) concurrent with the modulating of (d), incrementing or decrementing the variable value of the time keeping device; and f) repeating said modulating of (d) until the value of the variable value is about equal to the reference value and the test patch is exposed.

Control system for test patch area exposure in a printing machine

A method and apparatus for the control of darkness/lightness in a digital image rendered by a printing system. The technique preferably employs templates to selectively apply different amounts of darkening (lightening) to borders of structures detected within the image dependent upon the need for darkening (lightening).

Method and apparatus for digital image darkness control using quantized fractional pixels

A system for providing an output from a digital printing apparatus which is of higher resolution than the native resolution of the original image data. For a given center pixel area, image data corresponding to pixel areas generally neighboring the center pixel area are attempted to be matched to various templates which are consistent with curved lines in which resolution enhancement of the center pixel would be desirable. In a second stage of template matching, a second set of image data, corresponding to pixel areas further away from the center pixel than the first set of pixel areas, is also attempted to be matched to templates. The second stage of template matching helps to avoid resolution enhancement of image data which is related to a halftone image.

Resolution enhancement for a digital printing apparatus

A lead edge lightening circuit which will lighten a scan line based on a seven by seven pixel area surrounding the current pixel. The area is divided into four sub-areas, each of four by four pixels, and each having the current pixel at one corner. Each sub-area is summed and compared to a threshold number. If the threshold number is equalled or exceeded by at least one of the four sums, an overlay bit, which can be white or black, is output. The current pixel is replaced by a white pixel if a white pixel has been output, otherwise the current pixel remains unchanged.

Quadrant-based density detection for lead edge lightening

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Webster, NY, United States of America

Rosario A Bracco