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REDUCING IMAGE SLIP

IP.com Disclosure Number: IPCOM000025509D
Original Publication Date: 1985-Oct-31
Included in the Prior Art Database: 2004-Apr-04
Document File: 2 page(s) / 63K

Publishing Venue

Xerox Disclosure Journal

Abstract

In order to enable an increase in the slit width of the image plane exposure slit of a xerographic copier, a Fresnel lens (1) is placed close to the photoreceptor drum (2). The Fresnel lens focusses the imaging lens (3) at infinity. If it is placed less than 5mm from the photoreceptor, insignificant changes in other conjugate distances are required. Such an arrangement eliminates lateral image slip (leaving only the considerably smaller defocussing) and the major part of longitudinal image slip.

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XEROX DISCLOSURE JOURNAL

REDUCING IMAGE SLIP
355/8 CI. U.S. Proposed G. H. S. Rokos Classification

Int. Cl. G03g 15/28

3

In order to enable an increase in the slit width of the image plane exposure slit of a xerographic copier, a Fresnel lens (1) is placed close to the photoreceptor drum
(2). The Fresnel lens focusses the imaging lens (3) at infinity. If it is placed less than 5mm from the photoreceptor, insignificant changes in other conjugate distances are required. Such an arrangement eliminates lateral image slip (leaving only the considerably smaller defocussing) and the major part of longitudinal image slip.

If the Fresnel lens is perfectly focussed on the imaging lens, we find that the defocus of the image becomes equal to the original lateral image slip when the slit width (along the scan direction) is 2/33, and the longitudinal slip reaches this same value when the slit width is 3/6. Either of these would limit the increase in slit width to x.1.8. Together, the limit will be about x.1.6.

Volume 10 Number 5 September/October 1985 303

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REDUCING IMAGE SLIP (Cont'd) More commonly, a single Fresnel lens will be used at a number of magnifications. As magnification change is commonly achieved by moving the imaging planes and the lens, this means that its focus will not actually be at infinity. For a x0.65 minimum magnification range, the consequent residual "lateral image slip" wil I reduce the...