Electrophotography – Document handling
Reexamination Certificate
2000-11-30
2001-07-10
Eickholt, Eugene (Department: 2854)
Electrophotography
Document handling
C399S016000, C399S364000, C399S381000, C101S211000
Reexamination Certificate
active
06259884
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention is directed to a method for printing individual sheets in a printer or a copier, whereby a both-sided printing process on individual sheets ensues.
2. Description of the Related Art
High-performance printers can be operated in what is referred to as duplex mode, which is also called duplex color spot mode. In this operating mode, individual sheets are printed on both sides. When only one print ensues on the one side and two prints with different colors ensue on the other side, then this is called the duplex printing mode with three-fold printing. When respectively two prints ensue on both sides of the individual sheet, then this is called duplex printing mode with four-fold printing.
Various duplex printing systems with ate least two printing units are disclosed by U.S. Pat. No. 4,591,884 A. Another high-performance printer device with two printing units is disclosed by WO 91/13386 A1. It comprises two printing units and turnover channels for turning the individual sheets over. A transfer printing transport path is allocated to each printing unit.
When individual sheets are supplied such in such a high-performance printer device with two printing units that the spacing between two individual sheets is greater than the length of an individual sheet viewed in transport direction, then a safety margin is created between two individual sheets that allows a further individual sheet to be transferred in upon transport of the individual sheets in gaps between two successive individual sheets at intersections of the sheet transport paths. Given this procedure, however, the sheet throughput is relatively low due to the relatively large sheet spacings.
U.S. Pat. No. 5,159,395 discloses a printer device having only a single printing unit wherein spaces are likewise created between two successive sheets of a sheet stream in order to subsequently transfer further individual sheets into the sheet stream.
U.S. Pat. No. 5,337,135 discloses a further printer device with only a single printing unit wherein a first printing operating condition with a first, relatively close printing spacing is provided and a second operating condition with a second, larger sheet spacing [is provided], whereby following sheets are again transferred into an existing sheet stream in the second operating condition.
SUMMARY OF THE INVENTION
An object of the invention is to specify a method for printing individual sheets in a printer or in a copier in the duplex printing operating mode, whereby a high throughput of individual sheets given low wear and reduced risk of jams are achieved.
This object is achieved by the features of claim
1
. Advantageous ddevs are recited in the dependent claims.
In the invention, the individual sheets are conducted in groups on the transport path within the printer. In this way, a slight spacing can be set between the individual sheets given transfer printing speed. The drive elements for the transport are not stressed by an additional start-stop mode, so that the wear on the overall transport system is reduced. The control outlay is also reduced since path and switching tolerances do not occur and corresponding buffer zones are not required. The throughput of individual sheets through the printer or, respectively, the copier is increased, since the group of individual sheets can be conducted with maximum speed on the transport path.
According to a further aspect of the invention, a method for printing individual sheets is recited wherein a predetermined plurality of single sheets have a predetermined distance from one another at transfer printing speed that is smaller than the length of an individual sheet as viewed in transport direction, the individual sheets of this group are supplied successively to a first printing unit for printing with a first color on the first side, the individual sheets of the first group are successively re-supplied, turned over, to the first printing unit for printing with the first color on the second side, and wherein, subsequently, the individual sheets of the group are supplied to the second printing unit for printing with the second color on the second side and are then output.
This aspect of the invention relates to the duplex printing mode with three-fold printing. The individual sheets are conducted past two printing units in groups in order to apply one print on one side and two differently colored prints on the other side. Given this aspect of the invention, too, the spacing between two individual sheets can be minimal and the transport speed can be maximum. A high throughput given low wear for the drive elements is thus achieved.
In a preferred exemplary embodiment of the invention, the first individual sheet of a following group of individual sheets is supplied following the last individual sheet of a preceding group of individual sheets after said preceding group has been supplied twice to the first transfer printing path. As a result of these measures, a throughput that is high overall is achieved given a multitude of individual sheets, since the spacing between the last individual sheet of a preceding group and the individual sheet of a following group can be kept slight.
Preferably, the path spacing between the last individual sheet of the preceding group and the first individual sheet of the following group is approximately the predetermined spacing.
According to a further exemplary embodiment of the invention, at least some of the individual sheets of the group are conveyed in alternation to the first ring and to the second ring via the connecting channel. In this way, the number of individual sheets of the group can be high since, due to the alternating conveying, individual sheets at the start of the group and individual sheets at the end of the group can be conveyed nearly simultaneously in the connecting channel and distributed onto both rings at the end of the conveying path in the connecting channel. A great number of individual sheets in a group leads to an improved utilization of the printing capacity offered by the two printing units.
In a preferred development, the alternating conveying of the individual sheets to the two rings and/or the transporting of the individual sheets into the proximity of the printing units ensues with increased speed compared to the transfer printing speed of the printing units. As a result of this increased conveying speed, the spacing between successive individual sheets of a group is enlarged. This spacing is used in order to convey individual sheets at the start of the group and individual sheets at the end of the group in alternation and distribute them onto the two rings.
A practical exemplary embodiment provides that, following the renewed pass of the individual sheets of the group past the first printing unit, these are output or the individual sheets are supplied to the second printing unit for printing with the second color on the second side and are then output. In the first version, a duplex printing mode with three-fold printing is realized, and a duplex printing mode with four-fold printing of the individual sheets is realized in the second version.
REFERENCES:
patent: 4591884 (1986-05-01), Miyamoto et al.
patent: 4972236 (1990-11-01), Hasegawa
patent: 5049946 (1991-09-01), Harada
patent: 5150167 (1992-09-01), Goada et al.
patent: 5162845 (1992-11-01), Ariyama et al.
patent: 5337135 (1994-08-01), Malachowski et al.
patent: 5369480 (1994-11-01), Isobe
patent: 5384619 (1995-01-01), Yokomizo et al.
patent: 5449166 (1995-09-01), Lohmann et al.
patent: 5499091 (1996-03-01), Kasiwahara
patent: 5598257 (1997-01-01), Keler
patent: 5730535 (1998-03-01), Keller et al.
patent: 5746526 (1998-05-01), Hirose
patent: 6101364 (2000-08-01), Boehmer et al.
patent: 6134418 (2000-10-01), Kain et al.
patent: 39 18 961 C2 (1989-12-01), None
patent: 2 144 296 (1985-02-01), None
patent: 2 229 137 (1990-09-01), None
patent: WO 91/13386 (1991-09-01), None
Eickholt Eugene
Oce Printing Systems GmbH
Schiff & Hardin & Waite
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