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Print Enhancement for Laser Printers

IP.com Disclosure Number: IPCOM000044021D
Original Publication Date: 1984-Oct-01
Included in the Prior Art Database: 2005-Feb-05
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Bassetti, LW: AUTHOR [+2]

Abstract

This article describes a print-enhancement circuit where "gray" energy density levels are created near pel (picture element) transitions on the photoconductor of an electrophotographic printing machine which utilizes a solid-state laser as the light source. The purpose of the print-enhancement circuit is to smooth pel transition so that digitization effects become much less apparent. These effects or errors in printed characters are caused by the fact that discrete dots are used to form the character strokes and are particularly noticeable in slanted character strokes, that is, strokes which are neither perpendicular nor parallel to the print direction. The print-enhancement circuit, described in this article, causes the creation of "gray" energy density areas on the photoconductor near pel transitions.

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Print Enhancement for Laser Printers

This article describes a print-enhancement circuit where "gray" energy density levels are created near pel (picture element) transitions on the photoconductor of an electrophotographic printing machine which utilizes a solid-state laser as the light source. The purpose of the print-enhancement circuit is to smooth pel transition so that digitization effects become much less apparent. These effects or errors in printed characters are caused by the fact that discrete dots are used to form the character strokes and are particularly noticeable in slanted character strokes, that is, strokes which are neither perpendicular nor parallel to the print direction. The print-enhancement circuit, described in this article, causes the creation of "gray" energy density areas on the photoconductor near pel transitions. The combined effects of the "gray" areas on the photoconductor and the electrophotographic process yield a more continuous black line in which the digitization has been greatly reduced. Gray energy density levels can be generated in one of two ways when using a solid-state laser. The first method is to vary the current through the laser to produce an area of gray energy density on the photoconductor. This method requires a relatively complex drive circuit in which laser current can be varied, and, in addition, a second feedback loop may be required to maintain the desired "gray" current level. The second method of generating gr...