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Browse Prior Art Database

SIMPLEX - DUPLEX INTERMIX THROUGHPUT INCREASE OF JOBS

IP.com Disclosure Number: IPCOM000026784D
Original Publication Date: 1993-Aug-31
Included in the Prior Art Database: 2004-Apr-06
Document File: 4 page(s) / 209K

Publishing Venue

Xerox Disclosure Journal

Abstract

This system provides optimization of simplex - duplex image printing mixes in a printer. It efficiently accommodates printing of electronic image input of simplex, duplex and mixes thereof. The basic algorithm will work for both a duplex tray system and a trayless duplex path system. The efficiency savings are believed to be comparable.

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Page 1 of 4

XEROX DISCLOSURE JOURNAL

THROUGHPUT INCREASE OF

JOBS

David W. Covert

C1.355/308 US. Proposed SIMPLEX - DUPLEX INTERMIX Classification

Int. C1. GO36 21/00

This system provides optimization of simplex - duplex image printing mixes in a printer. It efficiently accommodates printing of electronic image input of simplex, duplex and mixes thereof. The basic algorithm will work for both a duplex tray system and a trayless duplex path system. The efficiency savings are believed to be comparable.

Key features of the disclosed embodiment here include: The running of simplex sheets as if they were duplex in special cases; and the optimization of a mixture of simplex and duplex prints as a mix of simplex and duplex sheets in the duplex path return loop or "racetrack" from the image transfer station and back thereto after sheet inversion. When encountering a mix of simplex and duplex images to be printed, the system here will automatically optimize the use of the duplex path to avoid skipped pitches or printing pauses. Once a true desired duplex sheet is to enter the duplex "racetrack", then enough, but only enough, simplex sheets to fill the rest of the duplex racetrack will be fed therethrough also.

This system can be extended to use in a duplex buffer tray system, rather than a racetrack or endless simplex buffer loop, although the algorithm may change somewhat. It is easily extendible for different length racetrack paper paths.

In the proposed embodiment, the present printer scheduling algorithm for an intermixed simplex and duplex job is changed so that simplex sheets to be printed when a duplex sheet is in the duplex path racetrack are treated as duplex sheets with a blank second side. Currently, such simplex sheet images are held (not printed) until the second (opposite) side of the duplex sheet is imaged; this leads to skipping more pitches than necessary in some situations. Here, when a simplex copy sheet follows a duplex copy sheet, the simplex sheet is run through the system as if it were a duplex sheet being imaged on only one side. All the immediately following simplex copy sheets will also be processed as if they were duplex until the duplex path loop or racetrack is full. Once the duplex racetrack is full, further simplex sheets will be treated normally as simplex sheets and not run through the duplex path until another duplex sheet followed by one or more simplex sheets is encountered and scheduled for printing.

XEROX DISCLOSUm JOURNAL - VO~. 18, NO. 4 July/August 1993 431

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THROUGHPUT INCREASE OF SIMPLEX - DUPLEX INTERMIX

JOBS (Cont'd)

Using this scheme increases the throughput rate of printer jobs that contain a mix of simplex and duplex sheets. It can provide a 0 to 2.25 times copying speed improvement, depending on the actual mix of simplex and duplex images to be printed. This will result in a 0 to 125% increase in throughput. This is done here by always che...