Browse Prior Art Database

Duplex Print Processing for Minimal Memory Requirements for A Page Printer

IP.com Disclosure Number: IPCOM000120849D
Original Publication Date: 1991-Jun-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 3 page(s) / 134K

Publishing Venue

IBM

Related People

Damon, BW: AUTHOR [+2]

Abstract

Disclosed is a processing method that reduces the minimum memory requirements to perform duplex printing with a single imaging device using a simple duplex mechanism that provides a means to "turn the page over."

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 48% of the total text.

Duplex Print Processing for Minimal Memory Requirements for A Page
Printer

      Disclosed is a processing method that reduces the minimum
memory requirements to perform duplex printing with a single imaging
device using a simple duplex mechanism that provides a means to "turn
the page over."

      Duplex printing in a page printer with a single imaging device
that also provides collated simplex output typically requires the
printer to store at least two page images to provide collated duplex
output also.  Even more pages may be required to run the mechanism at
maximum throughput. Simplex printing can be done with much less than
a full bit map if the imaging engine process is faster than the
imaging mechanism.  Duplex printing not only requires at least twice
the memory to process an image but also complicates the determination
of when resources, such as fonts and overlays, can be released from
memory.  This either reduces the complexity of the page that can be
printed in duplex or increases the minimum size of memory required
for duplex. In addition, if the side 1 image is complete but
insufficient storage is available for side 2, side 2 must be printed
incompletely or side 1 must be printed first which will cause that
page to be collated improperly.

      Memory requirements for page printers can vary from very little
(for flat text printing) to very large (for complex images with
multiple fonts or graphics).  The worst case for a monochrome print
mechanism would require enough memory to store a whole page at the
desired print resolution.  If the paper path is long and print error
recovery is a desired feature, several pages must be stored to
maintain the maximum throughput of the mechanism. Typical usage of a
page printer, however, would need much less than that so page
printers include memory to handle the typical case and "slow down"
(keep fewer pages in the paper path, even down to doing a single
page) for more complex printing conditions.  Many page printers have
base memory configurations that are insufficient to print a single
complex page; some report the error, some print incompletely.  This
is done to provide a minimum price point for a printer.
Printing System

      Assume a printer with a single imaging mechanism and a duplex
mechanism.  That duplex mechanism can, on command, return a printed
page to the source drawer turned over so that the reverse side can be
printed.  For the simplest duplex mechanism, one of the pages must be
printed upside-down, i.e., if a normal page orientation is described
as portrait orientation, one side must be printed in reverse portrait
orientation.  Otherwise, the duplex mechanism must actually flip the
page over.  With the image reversal, it must only have a means to
reverse its path.

      Without essentially infinite memory available there will exist
some class of complex pages that cannot be printed on the duplex
printer.  This class of pages increases with...