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AN OPTICAL SYSTEM

IP.com Disclosure Number: IPCOM000023270D
Original Publication Date: 1977-Apr-30
Included in the Prior Art Database: 2004-Mar-29
Document File: 4 page(s) / 475K

Publishing Venue

Xerox Disclosure Journal

Abstract

An exposure station used in an electrophotographic printing machine and including lamps 25 moving across platen 26 to illuminate original document 24 disposed face down thereon. Lens 18 and filter 22 move in synchronism with lamps 25. The light rays reflected from original document 24 are transmitted through platen 26 onto mirror 70. Mirror 70 reflects the light rays through lens 18 and filter 22 onto mirror 72. Mir-ror 72 reflects the light image through screen 28 onto the charged portion of photoconductive surface 12. Lens 18 has an opaque member 20 interposed therebetween. Opaque member 20 is a flat sheet having a plurality of spaced holes or slots therein. As shown in Figure 1, opaque member 20 is interposed between the front component l8a and back component 18b of lens l8- The size of the holes or slots in opaque member 20 may be equal to one another or variable to adjust the intensity pat-tern.

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Page 1 of 4

XEROX DISCLOSURE JOURNAL

AN OPTICAL SYSTEM
R.N. Goren

Proposed Classification
U.S. Cl. 355/3
mt. Cl. G03g 15/00

~72

FIG.I

FIG. 2

,.-.. /0

Volume 2 Number 2 March/April 1977 71

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

Page 2 of 4

AN OPTICAL SYSTEM (Cont'd)

An exposure station used in an electrophotographic printing
machine and including lamps 25 moving across platen 26 to
illuminate original document 24 disposed face down thereon.
Lens 18 and filter 22 move in synchronism with lamps 25. The
light rays reflected from original document 24 are transmitted
through platen 26 onto mirror 70. Mirror 70 reflects the
light rays through lens 18 and filter 22 onto mirror 72. Mir-
ror 72 reflects the light image through screen 28 onto the
charged portion of photoconductive surface 12. Lens 18 has an
opaque member 20 interposed therebetween. Opaque member 20 is
a flat sheet having a plurality of spaced holes or slots
therein. As shown in Figure 1, opaque member 20 is interposed
between the front component l8a and back component 18b of lens
l8~ The size of the holes or slots in opaque member 20 may be
equal to one another or variable to adjust the intensity pat-
tern.

There is a prescribed geometrical relationship between screen
28, opaque member 20 and photoconductive surface 12. The
spacing between screen 28 and photoconductive surface 12 is
given by the following relationship:

D S PF

P is the center-to--center distance between adjacent

apertures;

S is the distance between opaque member 20 and

photoconductive surface 12; and

F is the half-tone screen line frequency.

When the foregoing relationship is maintained, the light rays
transmitted through each of the holes or slits in opaque mem-
ber 20 will be coincident with one another on the image plane.
Thus, the intensity...