Patent Application
20080053327
Various exemplary embodiments of the systems and methods are described in detail below, with reference to the attached drawing figures, in which:
The embodiments herein are useful with printing/copying devices such as those discussed in U.S. Patent Application 2003/0039491, the complete disclosure of which is incorporated herein by reference, and portions of which are incorporated herein.
This invention relates to a printing system which is used to produce color output in a single pass of a photoreceptor belt. It will be understood, however, that it is not intended to limit the invention to the embodiment disclosed. On the contrary, it is intended to cover all alternatives, modifications and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims, including a multi-pass color process system, a single or multiple pass highlight color system and a black and white printing system.
Turning now to
With continued reference to
Next, the charged portion of photoconductive surface is advanced through an imaging station B. At exposure station B, the uniformly charged belt 10 is exposed to a laser based output scanning device 24 which causes the charge retentive surface to be discharged in accordance with the output from the scanning device. The scanning device can be a laser Raster Output Scanner (ROS). Alternatively, the ROS could be replaced by other xerographic exposure devices such as LED arrays.
The photoreceptor, which is initially charged to a voltage Vc undergoes dark decay to a level Vddp equal to about −500 volts. When exposed at the exposure station B it is discharged to Vimage equal to about −50 volts. Thus after exposure, the photoreceptor contains a monopolar voltage profile of high and low voltages, the former corresponding to charged areas and the latter corresponding to discharged or image areas.
At a first development station C, developer structure, indicated generally by the reference numeral 32 utilizing a hybrid jumping development (HJD) system, the development roll, better known as the donor roll, is powered by two development fields (potentials across an air gap). The first field is the AC jumping field which is used for toner cloud generation. The second field is the DC development field which is used to control the amount of developed toner mass on the photoreceptor. The toner cloud causes charged toner particles 26 to be attracted to the electrostatic latent image. Appropriate developer biasing is accomplished via a power supply. This type of system is a noncontact type in which only toner particles (magenta, for example) are attracted to the latent image and there is no mechanical contact between the photoreceptor and a toner delivery device to disturb a previously developed, but unfixed, image.
The developed but unfixed image is then transported past a second charging device 36 where the photoreceptor and previously developed toner image areas are recharged to a predetermined level.
A second exposure/imaging is performed by imaging device 38 which comprises a laser based output structure and is utilized for selectively discharging the photoreceptor on toned areas and/or bare areas, pursuant to the image to be developed with the second color toner. At this point, the photoreceptor contains toned and untoned areas at relatively high voltage levels and toned and untoned areas at relatively low voltage levels. These low voltage areas represent image areas which are developed using discharged area development (DAD). To this end, a negatively charged, developer material 40 comprising color toner is employed. The toner, which by way of example may be yellow, is contained in a developer housing structure 42 disposed at a second developer station D and is presented to the latent images on the photoreceptor by way of a second HSD developer system. A power supply serves to electrically bias the developer structure to a level effective to develop the discharged image areas with negatively charged yellow toner particles 40.
The above procedure is repeated for a third image for a third suitable color toner such as cyan, and for a fourth image and suitable color toner such as black. The exposure control scheme described below may be utilized for these subsequent imaging steps. In this manner a full color composite toner image is developed on the photoreceptor belt.
To the extent to which some toner charge is totally neutralized, or the polarity reversed, thereby causing the composite image developed on the photoreceptor to consist of both positive and negative toner, a negative pre-transfer dicorotron member 50 is provided to condition the toner for effective transfer to a substrate using positive corona discharge.
Subsequent to image development, a sheet of support material 52 is moved into contact with the toner images at transfer station G. The sheet of support material is advanced to transfer station G by a sheet feeding apparatus to the pretransfer device which directs the advancing sheet of support material into contact with photoconductive surface of belt 10 in a timed sequence so that the toner powder image developed thereon contacts the advancing sheet of support material at transfer station G.
Transfer station G includes a transfer dicorotron 54 which sprays positive ions onto the backside of sheet 52. This attracts the negatively charged toner powder images from the belt 10 to sheet 52. A detack dicorotron 56 is provided for facilitating stripping of the sheets from the belt 10.
After transfer, the sheet continues to move, in the direction of arrow 58, onto a conveyor which advances the sheet to fusing station H. Fusing station H includes a fuser assembly, indicated generally by the reference numeral 60, which permanently affixes the transferred powder image to sheet 52. The fuser assembly 60 comprises a heated fuser roller 62 and a backup or pressure roller 64. Sheet 52 passes between fuser roller 62 and backup roller 64 with the toner powder image contacting fuser roller 62. In this manner, the toner powder images are permanently affixed to sheet 52 after it is allowed to cool. After fusing, the sheet is separated from the fuser roll by the corrugating air knife, to a chute, not shown, which guides the advancing sheets 52 to a catch tray 32 (shown in
After the sheet of support material is separated from photoconductive surface of belt 10, the residual toner particles carried by the non-image areas on the photoconductive surface are removed therefrom. These particles are removed at cleaning station I using a cleaning brush structure contained in a housing 66.
Referring now to
During the remainder of the printing of the non-test production print job, the method continues the printing of the sheets and the monitoring as shown by the arrow running from item 104 to item 100. After the printing is completed, the identifier sheet can be subjected to specific inspection or can be used to indicate a specific sheet count within the stack of sheets as shown by item 106. Then, the stack of sheets can be subjected to subsequent processing such as trimming and binding, wherein the trimming process removes the edge region from the printed sheets as shown by item 108.
During the remainder of the printing of the non-test production print job, the method continues the printing of the sheets and the monitoring as shown by the arrow running from item 104 to item 100. After the printing is completed, the identifier sheet can be subjected to specific inspection by the user or technician can be used to indicate a specific sheet count within the stack of sheets as shown by item 110. Then, the stack of sheets can be subjected to subsequent processing such as trimming and binding, wherein the trimming process removes the edge region from the printed sheets as shown by item 108.
The embodiments herein print the edge markings on actual sheets used in actual production jobs as opposed to test jobs or test sheets. Thus, the embodiments herein allow continuous printing, even when machine parameters or printing quality may be outside normal ranges. In other words, the embodiments herein are different than those systems that involve the printing of testing or calibration sheets because the embodiments herein print the edge markings on actual production sheets of production runs made for customers. It is intended that all production runs should be printed error-free; however, because of various imperfections, occasionally errors occur during the printing of the production runs, and it is at this point in the process that some embodiments herein come into play. This situation is to be distinguished from set-up or testing situations where the output from the printing device will not be provided to the customer and, instead where the output is used merely to test and set up the printer. Therefore, the term production printing job comprises a printing operation that produces output intended to be provided to the customer (publisher, end user, public, etc.) as contrasted with output used to setup or test the printer itself.
The “monitoring” process in item 104 can comprise many different activities from quality monitoring to sheet number counting. Thus, in one embodiment, the “monitoring” process 104 comprises counting the number of printed sheets and the “event” comprises a predetermined number of sheets being printed from the start of the printing process or from the printing of the most recent identifier sheet. For example, an identifier sheet having the edge marking can be output at every 50th sheet, every 100th sheet, every 200th sheet, etc., or can be output at the end of every job or sub-job. Thus, embodiments herein can add the edge marking to any printing sheet being printed to create an identifier sheet whenever necessary to alert the printer technician of different items or amounts that are within the output stack of sheets.
Similarly, the monitoring 104 can comprise observing the image quality of the printed sheets and the “event” can comprise the image quality being outside of a predetermined normal range. Also, the monitoring 104 can comprise monitoring parameters of a printer performing the printing (e.g., ink or toner levels, temperatures, sensors, etc.) and the “event” can comprise a parameter being out of a predetermined normal range. The image quality and the parameters of the printer can be monitored automatically and/or manually. Therefore, embodiments herein allow the printer itself to automatically produce identifier sheets whenever preset parameters are exceeded, and also allow the printer technician to manually add edge markings to the sheets being printed to create identifier sheets that are then sent to the output to the stack. Note, that there may be a slight delay (of one or more sheets) before the edge marking may be added because the quality monitoring is performed on sheets that have already been printed and the edge marking is added to sheets that are being printed after the quality defect is detected. Therefore, the technician must inspect not only the sheets to which the edge marking has been added, but also a few sheets ahead of the one or ones to which the markings were added.
One feature of embodiments herein is that the unique edge marking 24 is visible from the side of the stack of sheets. While the edge marking 24 is printed using the same printing engines that print the data, graphics, and text 22 (and therefore prints on the front or back side of the media sheet) the edge marking 24 is printed all the way to the edge (and sometimes past the edge) of the sheet 20, which allows the edge marking 24 to be visible from the edge of the sheet. Therefore, the edge marking is visible from the edge of the sheet when the edge marked identifier sheet is included within a stack of sheets 30, as shown in
For purposes of this application the print media sheet (which can comprise paper, transparencies, card stock, plastic transfers, polymers, or any other substance capable of being printed upon) is generally flat and includes a front side and a back side with a top edge, bottom edge and two side edges. The edge marking 24 is printed on the front and/or back side where one of the sides meets one or more of the top, bottom, or side edges. Similarly, for purposes of this application, the stack of sheets will have a top where the front or back side of the top sheet appears, a bottom opposite the top, and four sides where the top, bottom, and side edges of the sheets are visible.
Further, not all potentially defective sheets need be marked and embodiments herein can simply identify a range of potentially incorrectly printed sheets using a beginning identifier sheet having the edge marking that is output when a parameter goes outside of the normal range and using an ending identifier sheet having the edge marking when a parameter returns to within the normal range. Thus, for example, as shown in
Further, the beginning identifier sheet could have an edge marking that is a different color than the edge marking of the ending identifier sheet. In addition, different colored edge markings can be used to indicate different types of errors or different types of counts, and item 24 in
The embodiments herein allow continuous printing, even when machine parameters or printing quality may be outside normal ranges. This allows the printer to remain running at full capacity even during temporary periods when the print quality may be degraded. By marking the potentially improperly printed sheets with edge markings, the technician operating the printer can be easily directed to the sheets which need to be inspected for possible reprinting. While embodiments herein may require some sheets to be reprinted, by maintaining a printer at full capacity, overall productivity increases.
The word “printer” or “image output terminal” as used herein encompasses any apparatus, such as a digital copier, bookmaking machine, facsimile machine, multi-function machine, etc. which performs a print outputting function for any purpose. The details of printers, printing engines, etc. are well-known by those ordinarily skilled in the art and are discussed in, for example, U.S. Pat. No. 6,032,004, the complete disclosure of which is fully incorporated herein by reference. The embodiments herein can encompass embodiments that print in color, monochrome, or handle color or monochrome image data. All foregoing embodiments are specifically applicable to electrostatographic and/or xerographic machines and/or processes.
It will be appreciated that the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims. The claims can encompass embodiments in hardware, software, and/or a combination thereof. Unless specifically defined in a specific claim itself, steps or components of the invention should not be implied or imported from any above example as limitations to any particular order, number, position, size, shape, angle, color, or material.
