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EXPOSURE ADJUSTMENT DEVICE FOR LINEAR ARRAY OPTICS

IP.com Disclosure Number: IPCOM000024917D
Original Publication Date: 1982-Oct-31
Included in the Prior Art Database: 2004-Apr-04
Document File: 2 page(s) / 79K

Publishing Venue

Xerox Disclosure Journal

Abstract

Figure 1 shows an optical system employed in a copier where a document 19, placed on a platen 12, is illuminated by means of a lamp 14, reflector 16 combination. As the platen is moved in the indicated direction, the document is incrementally scanned with the reflected images projected through a linear gradient index lens 18 onto a photoreceptor 20. In order to enable continuous exposure adjustment of this projected image, there is inserted a thin transparent plate 22 in a suitable location between lens 18 and photoreceptor 20. Exposure adjustment is achieved by rotating plate 22 from the horizontal plane (least attenuation) toward the vertical (greatest attenuation). The attenuation is a result of higher specular reflections at the plate surface as the angle of incidence increases. The total plate transmittance, as calculated from Fresnel reflection equations is:

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Page 1 of 2

XEROX DISCLOSURE JOURNAL

EXPOSURE ADJUSTMENT DEVICE FOR LINEAR ARRAY OPTICS
Paul H. Stiebitz

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

W 0 z

U
t-

I-

- I

v)

z

INCIDENCE OF ANGLE FIG. 2

Volume 7 Number 5 September/October 1982 333

[This page contains 1 picture or other non-text object]

Page 2 of 2

EXPOSURE ADJUSTMENT DEVICE FOR LINEAR ARRAY OPTICS (Cont'd)

Figure 1 shows an optical system employed in a copier where a document 19, placed on a platen 12, is illuminated by means of a lamp 14, reflector 16 combination. As the platen is moved in the indicated direction, the document is incrementally scanned with the reflected images projected through a linear gradient index lens 18 onto a photoreceptor 20. In order to enable continuous exposure adjustment of this projected image, there is inserted a thin transparent plate 22 in a suitable location between lens 18 and photoreceptor 20. Exposure adjustment is achieved by rotating plate 22 from the horizontal plane (least attenuation) toward the vertical (greatest attenuation). The attenuation is a result of higher specular reflections at the plate surface as the angle of incidence increases. The total plate transmittance, as calculated from Fresnel reflection equations is:

T = 114

cosa I cos 8

L where

         T = plate transmittance; 8 = angle of incidence (approximate lens optical axis to plate normal); 8 = angle of refracted ray in plate.

Figure 2 shows the calculated transmittance T for a clear material with i...