US 5,479,175 AGranted

Method and apparatus for enhancing discharged area developed regions in a tri-level pringing system

AssigneeXerox Corporation

InventorsMichael S. Cianciosi, Robert P. Loce, Martin E. Banton, Ronald E. Jodoin

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Abstract

The present invention is a an apparatus for enhancing the output along edges of discharged area developed regions in a tri-level imaging system employing a pulse width and position modulated signal ROS for exposure. The invention enables the identification and selective alteration of video data used to drive the ROS so as to extend the developed regions by a selected amount and eliminate digitization artifacts present in the image to be printed. The extension of the discharged area developed regions is accomplished by extending the width of, or adding separate, exposure pulses in adjacent areas to enable development within a portion of those regions.

Claims18

Dependent claims

In a pulsed imaging, pulse width modulated printing system for creating tri-level images on a photoresponsive member, where a color pixel is produced in response to a video pulse that is on for a full pixel period and a background pixel is produced in response to a video pulse that is on for an intermediate portion of a pixel period, a method for enhancing a discharged area developed region on the photoresponsive member, comprising the steps of:

converting a series of data words representing image pixels into a series of composite analog video pulses corresponding to a plurality of pixel periods, each pixel period having a composite video pulse representing a charged image area, discharged image area, and intermediate discharged image area to be formed on the surface of said photoreceptor member, said composite video pulses being applied to an acoustooptic modulator to modulate a laser beam used to expose regions of the photoresponsive member;
identifying a subset of the data words to be altered so as to improve the appearance of the discharged area developed regions of the output image;
and
altering a selected data word within the subset by modifying a video pulse corresponding to the selected data word.

1 more element

An apparatus for enhancing the discharged area developed regions in a pulsed imaging, pulse width modulated printing system capable of creating tri-level images on a photoresponsive member, where a color pixel is produced in response to a video pulse that is on for a full pixel period and a background pixel is produced in response to a video pulse that is on for an intermediate portion of a pixel period, including:

an acoustooptic modulator to modulate a laser beam used to expose regions of the photoresponsive member;
means for converting a stream of video data, representing a plurality of pixels, into composite analog video pulses having uniform pixel periods, each pixel period defining a composite video pulse representing a charged area, discharged area, and intermediate discharged area to be formed on the surface of said photoreceptor member, said composite video pulses being applied to the acoustooptic modulator;
means, responsive to the stream of video data, for identifying a subset of video data therein to be altered so as to improve the appearance of the discharged area developed regions of the output image;
and
means for altering the video data representing a selected pixel within the subset by modifying the video pulse corresponding to the selected pixel.

2 more elements

Dependencies are inferred from the claim text.