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VARIABLE THICKNESS CORRECTOR PLATE

IP.com Disclosure Number: IPCOM000025667D
Original Publication Date: 1987-Feb-28
Included in the Prior Art Database: 2004-Apr-04
Document File: 2 page(s) / 69K

Publishing Venue

Xerox Disclosure Journal

Abstract

Document imaging systems are prone to uneven exposure levels at an image plane due to factors such as uneven object plane illumination, cos 4 fall-off and the like. One method for correcting for this uneven light distribution is to use an illumination plate of var ing thickness to vary the transmission of light

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XEROX DISCLOSURE JOURNAL

VARIABLE THICKNESS CORRECTOR PLATE Melvin E. Deibler
John A. Durbin
George A. Charnitski Richard A. Spinelli

Proposed Classification
U.S. C1.355/8 Int. C1. G03g 15/28

J 18

I

I '90 0/l2

I I I

       I I 20 \i

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Document imaging systems are prone to uneven exposure levels at an image plane due to factors such as uneven object plane illumination, cos 4 fall-off and the like. One method for correcting for this uneven light distribution is to use an illumination plate of var ing thickness to vary the transmission of light

linear lamps 10 and 12 to illuminate a document 14 placed on a glass platen
16. A plastic corrector film 18, of varying thickness is applied to the bottom surface of the platen. For this configuration, it was assumed that 'an illumination profile of 216 mm was provided by lamps 10,12. The central illumination was approximately 33% of that of the edges nearest the lamps. To compensate for this uneven light distribution, the edges of film 18 would have to be 1.74 times the thickness of the center, For this example, the center thickness was taken to be 0.010 inch requiring a 0.0174 inch edge.

The light corrector could also be in the form of a varying thickness plate located along the optical axis on either the object or image side of lens 20. If the correction required is radially symmetrical about the center, the plate can be injection molded or ground and polished. If the illumination correction is symmetrical about a line, the plate...