Browse Prior Art Database

Contact Reflex Image Area Device

IP.com Disclosure Number: IPCOM000074492D
Original Publication Date: 1971-May-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 3 page(s) / 34K

Publishing Venue

IBM

Related People

Clarke, FR: AUTHOR [+2]

Abstract

A contact-reflex imaging mode with dichroic photoconductor does not allow the normal, slight enlargement, method of eliminating the edge of paper being copied. Here a polarizer is used to eliminate the edge effect and to eliminate toner particles being accumulated on the photoconductor outside the document area.

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Contact Reflex Image Area Device

A contact-reflex imaging mode with dichroic photoconductor does not allow the normal, slight enlargement, method of eliminating the edge of paper being copied. Here a polarizer is used to eliminate the edge effect and to eliminate toner particles being accumulated on the photoconductor outside the document area.

In lens-reflex imaging of electrophotographic materials, light impinging on the document is diffracted by the edge of the document. Such diffraction causes discontinuity in the light energy impinging the photoconductor at that point. This, in turn, causes a charge differential which is recognized by the developer and a developed line appears around the perimeter of the document. Imperfect registration between copy paper and photoconductor allows this line to be copied.

In one solution, this problem is minimized by a slight, usually around 2%, enlargement in the lens system. Enlargement provides that the edge diffraction is outside the area of the copy paper and thus not copied. Also, the lens is slightly out of focus which integrates the diffraction and further minimizes the problem. However, in a contact-reflex system, such enlargement is not possible.

The machine, at A, includes a photoconductor belt which, having previously been charged, is stopped and held in contact with the document. The exposure lights are turned on briefly. The photoconductor is released and moves through the developer and subsequently through the transfer station. The photoconductor is reversed and moves back through the developer unit, whose function is now cleaning, past the charge corona and over the document.

In order to negate end effects in the charge corona, it is longer than the width of the photoconductor. Thereby the entire photoconductor width is charged. The exposure lamps cause electrical decay at the edges of...