4,924,275
1 2
page into the input of the print engine in a flipped mode
PRINTER SWITCHABLE BETWEEN DUPLEX so the other side of the printed page can be printed by
AND SIMPLEX MODE ON A PAGE BY PAGE the print engine. This printer also includes apparatus
BASIS that dynamically switches the operation of the printer
5 from duplex to simplex mode when the printing com
FIELD OF THE INVENTION mands input from the associated processor indicates
This invention relates to printers and, in particular, to that the other side of a simplex printed page is a blank
a printing system that can be dynamically switched page. This enables the print engine to eject the simplex
between duplex and simplex mode of operation on a printed page directly to the output paper bin without
page by page basis. 10 having to cycle this simplex printed page back through
the print engine even though there are no characters to
PROBLEM be ... thereon. This blank page suppression or sim
It is a problem in the field of printing systems to plex/duplex mode switching thereby increases the
dynamically switch between simplex and duplex mode throughput of this printer system by avoiding the un
of operation. Non-impact printing systems typically 15 necessary delays occasioned by cycling a page of paper
make use of a single simplex print engine to accomplish through the print engine when nothing is to be printed
duplex printing. The simplex print engine has an input thereon.
for receiving blank pages of paper and an output for „
ejecting pages that have been printed by the print en- BRIEF DESCRIPTION OF THE DRAWING gine. The print characters along with overlays and 20 FIG. 1 illustrates the basic architecture of the subject segments are downloaded from an associated processor printer in block diagram form; and that is equipped with a print driver. The processor FIG. 2 illustrates in flow diagram form the operatransmits print data signals via the print driver to the tional steps taken by the control apparatus in this printer non-impact printing system. A print controller located system, in the non-impact printing system converts this print 25
data into control signals for the print engine and the DETAILED DESCRIPTION associated paper handling apparatus to thereby imprint Non-impact printing systems typically make use of a the characters on the page of paper as designated by the single simplex print engine t0 accomplish dupiex printprint data received from the associated processor. To ■ The si lex rint ine has an { t for receiving achieve duplex printing using a single simplex print 30 ^ and an { for engine, the print engine prints one side of the page of ^ haye bgen inted b {he rim ine The mt
paper and then ejects this page via its output. The characters along with overlays and Segments are down
ejected page is then flipped and reinserted into the input . , , c ° . , , ., . . ,
J. tl_ • * ■ u ,u „ ... • . • loaded from an associated processor that is equipped
of the print engine such that the print engine can now . , , . _, r ^ 7 , rJT
. *• v. * B • « with a print driver. The processor transmits print data
print the successive page of characters on the previ- 35 . ^. . ^ . r . .
ously unused side of the page of paper. In this fashion, slSnals vlAa the Prlnt drl^er 0 *e non-impact printing
a single simplex print engine can perform a duplex print- ... A Prmt controller located in the non-impact
ing function printing system converts this print data into control
A significant disadvantage of this architecture is that si§nals for the Print en§ine and the associated paper
every page of paper must be cycled through the print 40 handling apparatus to thereby imprint the characters on
engine twice in order to achieve the duplex printing. the Pa8e of PaPer as designated by the print data re
This halves the printing throughput of the print engine celved from the associated processor. To achieve du
since it must handle the same page of paper twice before Plex printing using a single simplex print engine, the
the page is finally printed. A further delay is occasioned Print engine prints one side of the page of paper and
by the additional time required to receive the simplex 45 then ejects this page via its output. The ejected page is
printed page of paper output by the print engine, flip then flipped and reinserted into the input of the print
this printed page and then reinsert it into the input of the engine such that the print engine can now print the
print engine. During the time that this simplex printed successive page of characters on the previously unused
page of paper is being flipped and reinserted into the side of the page of paper. In this fashion, a single sim
print engine, the print engine is idle. Therefore, this 50 plex print engine can perform a duplex printing func
simple and economical architecture suffers a speed dis- tlon
advantage in having to cycle every page of paper The printer of the present invention is dynamically
through the print engine twice with the delay occa- switchable between simplex and duplex mode of opera
sioned in this additional paper handling as mentioned. tion on a page by page basis. This printer includes appa
This is especially counterproductive when the second 55 ratus that dynamically switches the operation of the
side of a page does not contain any printing thereon but printer from duplex to simplex mode when the printing
still must be cycled through the print engine in order to input commands from the associated processor indicates
maintain the proper sequencing and formatting of the that the other side of a simplex printed page is a blank
document that is being printed. page. This enables the print engine to eject the simplex
60 printed page directly to the output paper bin without
SOLUTION having to cycle this simplex printed page back through
The above described problems are solved and techni- the print engine even though there are no characters to
cal advance achieved in the field by the printer of the be printed thereon. This blank page suppression or sim
present invention that is dynamically switchable be- plex/duplex mode switching thereby increases the
tween simplex and duplex mode of operation on a page 65 throughput of this printer system by avoiding the un
by page basis. This printer makes use of the basic single necessary delays occasioned by cycling a page of paper
simplex print engine architecture and accomplishes through the print engine when nothing is to be printed
duplex printing by the reinsertion of a simplex printed thereon.
