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Electrophotographic Copier Erase Function

IP.com Disclosure Number: IPCOM000086838D
Original Publication Date: 1976-Nov-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 42K

Publishing Venue

IBM

Related People

Routt, WM: AUTHOR

Abstract

In an electrophotographic copier it is conventional to change the entire photoconductor and to thereafter expose only a portion of the photoconductor to the discharging light image of a document to be copied, thereby forming a latent electrostatic image of this document on the photoconductor.

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Electrophotographic Copier Erase Function

In an electrophotographic copier it is conventional to change the entire photoconductor and to thereafter expose only a portion of the photoconductor to the discharging light image of a document to be copied, thereby forming a latent electrostatic image of this document on the photoconductor.

In Fig. 1, photoconductor drum 10 rotates in a clockwise direction. Charge corona 11 charges the photoconductor. Thereafter imaging station 12 discharges the drum's portion 13-14. The drum portion 15 called the interimage portion, is charged by corona 11, but is not used for the latent image. Thus, interimage erase lamp 16 is controlled by a drum position sensor (not shown) to expose and discharge portion 15. As a result, portion 15 does not pick up toner as it passes through developer 17.

Timing errors in the control of lamp 16 are controlled by a closed loop optical servo system which senses a small toner stripe or bar at the boundaries of portion 15. This servo system includes a light source 18 and a photocell 19 (Fig.
2), located after transfer station 20 and before clearing station 21. Since untransferred, unfused toner is highly diffuse and of very low reflectance, whereas the photoconductor's surface is specular and of moderate reflectance, the presence of toner is indicated by a low-level photocell signal. The effect of the drum's curvature is minimized by arranging axis 22 of the optical system parallel to the drum's axis (F...