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DOCUMENT SCREENS FOR ELECTROPHOTORAPHIC RANGE EXTENSION

IP.com Disclosure Number: IPCOM000023292D
Original Publication Date: 1977-Jun-30
Included in the Prior Art Database: 2004-Mar-29
Document File: 2 page(s) / 283K

Publishing Venue

Xerox Disclosure Journal

Abstract

It is well known that the tonal range of electrophotographic copies can be extended by inserting spatially modulated ab-sorbing screens in the optical path during image exposure. The problem with these screens is that they absorb light, and thus they require substantially more exposure light. In order to reduce the required light exposure and to further extend the tonal range, the following types of optical patterns can be used on document screens (i.e., optical screens that are placed in front of the document to be copied) : (1) diffusely reflecting patterns, (2) specularly reflecting patterns, (3) partially absorbing partially transmitting patterns (gray patterns) , (4) partially reflecting partially transmitting patterns (either diffusely or specularly reflecting) , (5) any combination of all of the above, The optimum arrangement will depend upon many factors including the reproduction character-istics of the entire electrophotographic system under consid-erat ion.

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XEROX DISCLOSURE JOURNAL

DOCUMENT SCREENS FOR ELECTROPHOTO~- Proposed Classification
GRAPHIC RANGE EXTENSION U.S. Cl, 355/3
C. F. Gallo mt. Cl, G03g 15/00
W. L. Rhodes

It is well known that the tonal range of electrophotographic
copies can be extended by inserting spatially modulated ab~
sorbing screens in the optical path during image exposure.
The problem with these screens is that they absorb light, and
thus they require substantially more exposure light. In order
to reduce the required light exposure and to further extend
the tonal range, the following types of optical patterns can
be used on document screens (i.e., optical screens that are
placed in front of the document to be copied) : (1) diffusely
reflecting patterns, (2) specularly reflecting patterns, (3)
partially absorbing partially transmitting patterns (gray
patterns) , (4) partially reflecting partially transmitting
patterns (either diffusely or specularly reflecting) , (5) any
combination of all of the above, The optimum arrangement will
depend upon many factors including the reproduction character~
istics of the entire electrophotographic system under consid~
erat ion.

In order to extract the maximum tonal range from the above
described document screens, the following conditions should be
met: (1) The document screens should be used along with an
electrophotographic development system that has inherent solid
area capability. (2) The profiles of the spatial optical
modulation of the document screens should be soft and sm...