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Dual Mode Electrostatic Copier

IP.com Disclosure Number: IPCOM000075439D
Original Publication Date: 1971-Sep-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Luttman, EW: AUTHOR

Abstract

A method of producing both negative and positive copy from an electrostatic reproduction machine is described.

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This is the abbreviated version, containing approximately 86% of the total text.

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Dual Mode Electrostatic Copier

A method of producing both negative and positive copy from an electrostatic reproduction machine is described.

A discharged-area development system normally is used to produce negative to positive output.

To produce positive-to-positive output from this system, the photoconductor is charged by conventional techniques to a potential V. The photoconductor is then exposed in the normal manner, with the exception that the exposure must be limited so that the potential in the discharged area remains at above half the original potential. The image is then developed in conventional fashion. However, the image is not transferred from the photoconductor, but the photoconductor is then exposed by a suitable means, such as an erase lamp, so that the undeveloped area of the photoconductor is discharged to near zero potential. The toned areas of the photoconductor retain their potential because the toner acts as a light shield. The developed image is then cleaned and the image is then redeveloped to produce a positive copy of the original image. The cleaning and redeveloping steps can be combined when the developer acts to redistribute the toner such as magnetic brush development, for example.

To produce a reversed output from a charged-area development system, the photoconductor is charged to an intermediate voltage such as above half of the previous potential V/2. The photoconductor is then exposed using conventional techniques and the resulta...