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PROJECTED ADDITIVE SCREEN

IP.com Disclosure Number: IPCOM000023956D
Original Publication Date: 1979-Jun-30
Included in the Prior Art Database: 2004-Apr-01
Document File: 2 page(s) / 287K

Publishing Venue

Xerox Disclosure Journal

Abstract

A beam splitter is used to produce an additively screened output image from two projectors. An original in the form of a slide or film (not shown) is projected by an image projector through a beam splitter, reflected from a mirror passed through a Fresnel lens onto the photoconductive surface of an electrostatographic printing machine. A screen (not shown) is projected by a screen projector, and the image is

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XEROX DISCLOSURE JOURNAL

PROJECTED ADDITIVE SCREEN
L. D. Mailloux

Proposed Classification
U.S. Cl. 96/43 Int. Cl. G03f 5/00

A beam splitter is used to produce an additively screened output image from two projectors. An original in the form of a slide or film (not shown) is projected by an image projector through a beam splitter, reflected from a mirror passed through a Fresnel lens onto the photoconductive surface of an electrostatographic printing machine. A screen (not shown) is projected by a screen projector, and the image is reflected by the beam splitter and mirror through the Fresnel lens onto the same photoconductive surface. The Fresnel lens is conveniently located on the platen of the printing machine. In this manner, an additively screened output image is produced, The projector brightness required for producing such an additively screened output image is considerably less than for an image multiplicatively produced by placing the screen on the platen of the printing machine.

Optionally, a separate screen may be placed at the platen adjacent the Fresnel lens to provide a small amount of multiplicative screening for the image highlight areas. The additive and multiplicative screens so used need not be registered nor of the same frequency, but their relationship must be chosen to avoid Moire problems.

In a further embodiment, the beam splitter and screen projector are eliminated and both additive and multiplicative screening are provided at the platen. The...