Patent Application
20080056787
The above-mentioned and other features and objects of this invention and the manner of attaining them will become more apparent and the invention itself will be better understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying figures wherein:
a-1d are diagrammatical views of an embodiment of the system at successive stages in performing an embodiment of the method. The sequence of sheet supports used corresponds to the numbers on the sheets in
a is a partial diagrammatical view of the conveyor of the apparatus of
b is the same view as
In the method and system, print media sheets are continuously printed in a sequential order that is maintained in the finished print product. The printing is accomplished with one recto-printing pass and one verso-printing pass through the printing apparatus. Two-side printable sheets are subject to both recto- and verso-printing. One-pass printable sheets are introduced at an appropriate place in the sequential order and are printed on only one side.
The terms “recto-printing” and “verso-printing” and like terms are used herein to refer to the printing of opposite sides of the print media sheets. The term “recto” is used to refer to the front side of a sheet and the term “verso” to the reverse side of the sheet, during printing. It will be understood that, in some cases, either side of a media sheet can be the front or recto side, while in other cases the front is defined by a difference in the two sides. It will also be understood that the front and back may be interchanged by later finishing operations and to that extent, the terms “recto” and “ventro” are arbitrary.
The order of the sheets during printing matches the sequential order of the sheets in the printed output, both before and after finishing. For example, a print job has a stack of two-side printable sheets topped by a one-pass printable cover. The last two-side printable sheet of the print job can be printed first and the first two-side printable sheet can be printed last each time, during recto- and verso-printing passes through a press. The cover sheet is then introduced and printed at the end of the verso-printing pass. The two-side printable sheet could be DIN A4 size and the one-pass printable sheet could be an outer cover of DIN A3 size, with the cover being folded over the other sheets during finishing following verso-printing.
Referring now to
The type and number of print engines is not critical. For example, a single page-width ink jet printhead could be used. The system is particularly advantageous for electrophotographic print engines, since the contamination risk presented by plastic sheets with such print engines is commonly encountered. The locations of the print engines along the transport path are not critical, except that two passes, that is, circuits, of a sheet along the transport path are required to print both sides of the sheet. It is currently preferred that the same one or more print engines are used to print both sides of the sheet. The data input units supply digital images suitable for printing to the one or more print engines.
The conveyor has a sequence of sheet supports 26 (indicated by reference arrows 26 and in
A sheet support can be a physical subdivision of the conveyor or can be a virtual subdivision of a continuous conveyor having dimensions sufficient to receive a respective printable sheet. In a particular embodiment, the conveyor is an endless belt and the sheet supports are arranged in a continuous sequence in which gaps between adjoining sheet supports are absent or insufficiently small to receive a media sheet.
Referring to
Sheet supports can either be limited to sheets of a specific size or can receive sheets in a variety of sizes. The latter allows flexibility in selection of media sheets, including mixing sheets of different sizes in the same print job. With virtual sheet supports, the dimensions of the sheet supports can be fixed, that is, unchanging, or can be variable to meet the requirements of different size sheets.
The sheet supply units deliver sheets one-by-one to the sheet supports. In the illustrated embodiment, there are first and second sheet supply units. Other numbers of supply units could be provided. Equipment and methods for supplying sheets are well known to those of skill in the art.
An inverter flips the transported sheets over and returns them to respective sheet supports. Inverters are well known to those of skill in the art.
The output holder and finishing equipment can be limited to a simple bin or the like or can provide any of the various features known to those of skill in the art. Once fully printed, the sheets are delivered to and collected in the output holder and, optionally, are then finished in the finishing equipment. Finishing can include one or more of: binding, punching, and stapling. Equipment and methods for these purposes are well known to those of skill in the art.
The control unit operates the other components of the system utilizing stored software and data based upon signals from input devices (not shown). Appropriate sensors are utilized to provide control signals for the apparatus. Some operations of the control unit are discussed below in relation to the method. The control unit can include, but is not limited to, a programmable digital computer, a programmable microprocessor, a programmable logic processor, a series of electronic circuits, a series of electronic circuits reduced to the form of an integrated circuit, or a series of discrete components. Necessary programs can be provided on fixed or removable memory or the control processor can be programmed, as is well known in the art, for storing the required software programs internally. Different numbers of the processors can be provided, as appropriate or convenient to meet particular requirements, or a single processor can be used. Parameters for the processors are supplied from memory. “Memory” refers to one or more suitably sized logical units of physical memory provided in semiconductor memory or magnetic memory, or the like. Memory can include conventional memory devices including solid state, magnetic, optical or other data storage devices and can be fixed within system or can be removable. Data including but not limited to control programs can also be stored in a remote memory system such as a personal computer, computer network or other digital system. In addition to functions necessary to operate the system, other functions can be provided, such as image rendering, enhancement, and restoration, manual editing and intervention in automated (machine-controlled) operations. Those skilled in the art will recognize that the equivalent of software can also be readily constructed in hardware. Because image manipulation algorithms and systems are well known, the present description emphasizes algorithms and features forming part of, or cooperating more directly with, the method and system. General features of the types of computerized systems discussed herein are well known, and the present description is generally limited to those aspects directly related to the invention. Other aspects of such algorithms and apparatus, and hardware and/or software for producing and otherwise processing the image signals involved therewith, not specifically shown or described herein may be selected from such systems, algorithms, components, and elements known in the art. Given the description as set forth herein, all additional software/hardware implementation is conventional and within the ordinary skill in the art. The system can be implemented in a combination of software and/or hardware and is not limited to devices, which are physically connected and/or located within the same physical location. One or more of the components can be located remotely and can be connected via a network.
In a particular embodiment, the printing system includes a color electrophotographic printer (not shown). In this case, color separation images are formed and transferred in register by four color toner units to each sheet supported on the conveyor. The toner units can be configured to be mechanically operated by the conveyor, which operates continuously during printing. The conveyor is an endless belt having a top layer of a material having a bulk electrical resistivity. The belt material can be of any of a variety of flexible materials such as a fluorinated copolymer (such as polyvinylidene fluoride), polycarbonate, polyurethane, polyethylene terephthalate, polyimides (such as Kapton®), polyethylene napthoate, or silicone rubber. An additive can be used, such as an anti-stat (e.g. metal salts) or small conductive particles (e.g. carbon), to impart the desired resistivity. When materials with high resistivity are used, additional corona charger(s) may be needed to discharge any residual charge remaining on the web once the substrate has been removed. The belt can have a conducting layer beneath the resistive layer, which is electrically biased to urge toner image transfer. The conducting layer can be the support layer or an additional layer. Alternatively, the conducting layer is absent and the transfer bias is applied through either one or more of the support rollers or with a corona charger.
In feeding sheets from the sheet supplies into the sheet supports, charge can be provided on the sheets by a charger to electrostatically attract the sheets and “tack” them to the conveyor. A blade associated can be provided to press the sheets onto the belt and remove entrained air. The color toner units each transfer a respective toner from a toner supply to a photoconductor, which is charged responsive to image information. The resulting toner image is then transferred, either directly or indirectly, to the sheet in the sheet supply. After toning, the sheets are detacked from the sheet supports and sent to a fusing station to fuse the dry toner images to the sheets. A detack charger can deposit a neutralizing charge on the sheets to facilitate separation from the sheet supports. The sheets are then delivered to the output unit.
Referring again to
The two-side printable sheets in the second and third segments then move to the print engine or engines and are verso-printed. After verso-printing, the two-side printable sheets move to the inverter and are flipped over and replaced in respective sheet supports. The sequence of sheet supports is then moved in a second pass through the printer. During the second pass, the two-side printable sheets in the first segment are recto-printed. One-pass printable sheets are then introduced into respective sheet supports of the second segment. The one-pass printable sheets in the second segment and the two-side printable sheets in the third segment are then recto-printed. This completes the printing. The printed sheets are then delivered to an output holder in the order of the sheet supports, which corresponds to the order, in which the sheets were recto-printed. The sheets can then be finished. The order is maintained during finishing. In a particular embodiment, the printed sheets are collected in a single stack following the recto-printing steps. The stack has the sheets in front-to-back order, which is maintained during finishing.
The invention is inclusive of combinations of the embodiments described herein. References to “a particular embodiment” and the like refer to features that are present in at least one embodiment of the invention. Separate references to “an embodiment” or “particular embodiments” or the like do not necessarily refer to the same embodiment or embodiments; however, such embodiments are not mutually exclusive, unless so indicated or as are readily apparent to one of skill in the art. The use of singular and/or plural in referring to the “method” or “methods” and the like is not limiting.
The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102006040527.7 | Aug 2006 | DE | national |
