Browse Prior Art Database

COLOR COPIER

IP.com Disclosure Number: IPCOM000024364D
Original Publication Date: 1980-Jun-30
Included in the Prior Art Database: 2004-Apr-02
Document File: 4 page(s) / 123K

Publishing Venue

Xerox Disclosure Journal

Abstract

In a xerographic-type copier utilizing a laser output scanner, document creation (such as forms printing) could be greatly enhanced if the form itself could be printed in color with the data or information printed in black or vice versa. However, typical black and white xerographic machines have only one development housing, which limits the possibility of accomplishing this end. One means of adding color to the document would be to add a second development housing. However, such a technique seriously reduces the machine throughput as two passes are required to produce each copy.

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Page 1 of 4

XEROX DISCLOSURE JOURNAL

COLOR COPIER
F. Ruckdeschel
0. Hauser

Proposed Classification

Int. C1. G03g 15/01


U.S. a. 355/4

c- DENSITY in]

FIG. 1

DENSITY [COLOR]

FIG. 2a

EXPOSURE

1

DENSITY [BACK]

FIG. 26

Volume 5 Number 3 May/June 1980 269

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

Page 2 of 4

COLOR COPIER (Cont'd)

In a xerographic-type copier utilizing a laser output scanner, document creation (such as forms printing) could be greatly enhanced if the form itself could be printed in color with the data or information printed in black or vice versa. However, typical black and white xerographic machines have only one development housing, which limits the possibility of accomplishing this end. One means of adding color to the document would be to add a second development housing. However, such a technique seriously reduces the machine throughput as two passes are required to produce each copy.

The proposed technique uses two development housings, which are charged with developer materials which behave oppositely to the laser written electrostatic image. Thus, the latent image containing both forms-related and data-related information passes sequentially through the two development zones, each zone developing a different color.

A typical discharge curve is shown in Figure 1. Normally, the bias is placed at level B, and A-B represents the maximum electrostatic contrast. Intermediate exposures are represented by C with an electrostatic contrast B-C. The residual is represented by R, and B-R is a bias voltage which acts to reduce background.

The proposed electrostatic scheme com bines the intelligence of electronic scanning and biasing to create two electrostatic images simultaneously on the same photoconductor. The bias voltage is raised to about half the value of A. Color information areas on the photoconductor are discharged by the laser scanner to a point far enough below B to suppress background development with conventional magnetic brush developing units. For example, this may be as high as 400 volts with a 450 volt bias. Black information areas on the photoconductor on the other hand can be discharged to levels substantially below the bias (for instance, to about 50 volts) or somewhere near the residual. Thus, the net electr...