Browse Prior Art Database

Document Feeder Jam Prevention

IP.com Disclosure Number: IPCOM000048730D
Original Publication Date: 1982-Mar-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 2 page(s) / 84K

Publishing Venue

IBM

Related People

Brannan, RC: AUTHOR [+2]

Abstract

This article describes controls which determine when document withdrawal or document skew causes a copier's entry sensor to detect a document's trailing edge before the copier's pre-entry sensor detects the document, thus averting jams and damage to documents.

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Document Feeder Jam Prevention

This article describes controls which determine when document withdrawal or document skew causes a copier's entry sensor to detect a document's trailing edge before the copier's pre-entry sensor detects the document, thus averting jams and damage to documents.

In Fig. 1, a copier starts copying only if the trailing edge of a document is first detected by the pre-entry sensor, then by the entry sensor, as the document is moved onto the glass. If movement is in the opposite direction, i.e., the operator withdraws the document, the deactivation sequence of the two sensors will be in reverse order and the machine will not start. The entry sensor is located downstream from the pre-entry sensor and very close to the copier's reference edge to assure proper registration. This arrangement makes it possible for the copier to incorrectly assume that document withdrawal has taken place if a document skews in the entry tray or momentarily bounces away from the entry sensor as it enters. If withdrawal is incorrectly assumed (when in fact the document has been accepted, and the next document is fed), a misfeed and damage to both documents will occur, or an undetected double-feed condition will exist.

In Fig. 2, document entry is initiated after the document is properly aligned,
i.e., the document is under both the pre-entry and entry sensors.As the document enters, the entry sensor monitors the movement of the document. Once the entry sensor detects a trailing edge, a check is made to determi...