JP2005223381A - Image forming system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming system capable of arranging image positions of both sides of a recording medium without increasing the memory capacity. <P>SOLUTION: At printing of a front side in the case of double side printing, a register attaching processing section 626A allows an expansion processing section 610 to produce page data for printing registers being indices for measuring a print image size at blank parts on four corners of form P together with an original image to be printed. Then an image forming apparatus 11 prints page data on the front side, a line sensor section 90 reads an image printed on the front side when the form whose front side is printed is carried on a reverse carrying path for rear side printing, and a print image size calculation section 92 calculates an actual distance between the registers printed on the front side of the form on the basis of a result of the reading. A rear side magnification rate setting section 626B uses the calculated distance as an actual print image size printed on the front side of the form and compares the size with a substantial print image size (the substantial distance between the registers) to grasp an expanding/contracted state of the form resulting in determining a magnification/reduction rate of the image to be printed on the rear side. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image forming system, and more particularly to an image forming system having a function of forming an image on both sides of a recording medium, that is, a so-called double-sided printing function.

  In conventional printing (for example, offset printing), intermediate products such as paper printing (printing paper) such as photosetting, block printing, net negative, net positive, PS plate (printing plate) are generated, and these intermediate products are used as the original. Printing and bookbinding. In recent years, with the spread of DTP (DeskTop Publishing / Prepress), “direct printing” or “on-demand printing” for directly printing from DTP data is known. In DTP, printing data obtained by processing a page layout on a computer is formed on photographic paper or a plate-making film, and a printing plate is created and printed based on the printing data. In addition, CTP (Computer To Plate) that directly forms a printing plate with electronic data without generating an intermediate product is also attracting attention. As an apparatus that can be used for such a printing process, an image forming apparatus having a printing function such as a printer or a copying machine is known. Image forming apparatuses in recent years have been improved in color with improved image quality. For example, a color printer using an electrophotographic process (xerography) can form high-quality and high-speed images. In this image forming apparatus, print data can be output without receiving print data and generating a printing plate or the like.

  FIG. 8 is a schematic diagram of a conventional image forming system. As shown in FIG. 8A, the image forming system includes an image forming apparatus 11 and a DFE (Digital Front End Processor) apparatus that sends print data to the image forming apparatus 11 and gives a print instruction. ing. FIG. 8B shows a data flow. The image forming apparatus 11 is an apparatus having a so-called printing function for forming an image on a predetermined recording medium, such as a color copying machine, a facsimile, or a printer.

  The DFE device has a drawing function and a printer controller (print control device) function. For example, the DFE device sequentially receives print data described in a page description language (PDL) from a client terminal, and the print data is rasterized. The image data is converted into an image (RIP processing; RIP processing), and the RIP processed image data and print control information (job ticket) such as the number of printed sheets and paper size are sent to the image forming apparatus 11, and the print engine of the image forming apparatus 11 And the paper conveyance system is controlled to cause the image forming apparatus 11 to execute the printing process. That is, the printing operation of the image forming apparatus 11 is controlled by a printer controller by the DFE apparatus. The print data includes four colors (YMCK) of three basic colors for color printing, ie, yellow (Y), cyan (C), and magenta (M), and black (K). Sent to.

  The image forming apparatus 11 records an image on printing paper using an electrophotographic process. The image output terminal (IOT) module 12 and a feed module (FM; Feeder Module) connected to the IOT module 12 are used. 5) A user interface device 18 for supporting the input of various data including an output module 17 and a touch panel. The IOT module 12 includes a toner supply unit 22 on which YMCK toner cartridges 24 are mounted, and an IOT core unit 20. The IOT core unit 20 has a so-called tandem configuration in which print engines (printing units) 30 having an optical scanning device, a photosensitive drum, and the like are arranged in a line for each color and in the belt rotation direction, and controls the print engine 30. An electric system control storage unit 39 for storing an electric circuit or the like is provided. The IOT core unit 20 sequentially transfers (primary transfer) the toner images on the photosensitive drums to the intermediate transfer belt 43. As a result, YMCK color toner images are multiple-transferred to the intermediate transfer belt 43. The image (toner image) transferred onto the intermediate transfer belt 43 is transferred (secondary transfer) onto the printing paper conveyed from the feed module 15 at a predetermined timing, and is subjected to fixing processing (fixing processing (fuser) 70). Melting and fixing). Thereafter, the paper is discharged out of the apparatus via the paper discharge processing device 72. Further, during double-sided printing, a sheet of paper that has already been printed on one side is temporarily held on a paper discharge tray (stacker) 74, pulled out from the paper discharge tray 74, reversed through a reverse conveyance path 49, and again IOT core unit 20 Passed to.

By the way, since the sheet expands and contracts when the fixing process is performed by the fixing device, the print image on the sheet expands and contracts as the sheet expands and contracts. As a result, during double-sided printing, the position of the image printed on the front surface and the back surface is shifted. For this reason, in the image forming system, the expansion / contraction rate of the substitute sample paper is obtained by experiment and stored, and the value is used to uniformly enlarge the image so that the positions of the images on both the front and back sides are matched. -Printing was reduced (see Patent Document 1).
JP 2002-314800 A

  However, since the expansion / contraction rate of the paper varies depending on the material of the paper and the temperature fluctuation of the fixing device, the uniform enlargement / reduction correction using the experimental values on the sample paper described above determines the printing positions on the front and back sides. Sometimes it was not possible to match. In other words, when a different type of paper from the sample paper is used, or when the expansion / contraction rate changes suddenly due to temperature fluctuations of the fixing device, the position of the printed image is shifted between the front and back surfaces.

  For this reason, it is conceivable that the expansion / contraction rate is obtained and stored in the apparatus for each paper type and for each fixing device temperature. It is disadvantageous.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an image forming system capable of aligning the image positions on both sides of a recording medium without increasing the memory capacity.

  In order to achieve the above object, an image forming system according to a first aspect of the present invention is an image forming unit capable of forming images on both sides of a recording medium, and the image forming unit forms an image on the first surface of the recording medium. An image size measuring unit that measures the size of the image that has been measured, the size of the image measured by the image size measuring unit, and the size of the image that should be originally formed, and based on the comparison result, The image forming unit includes an enlarging / reducing unit that enlarges / reduces an image to be formed on the second surface of the recording medium so as to substantially coincide with the image forming position on the first surface.

  According to the first aspect of the present invention, when an image is formed on both sides of a recording medium such as paper, the image size measuring unit performs the image size measurement when the image is formed on the first side of the recording medium by the image forming unit. The size of the formed image is measured. Then, the size of the image actually formed on the first surface (actual image size) is compared with the size of the image to be originally formed (original image size) by the enlargement / reduction means. Based on the comparison result, after the image to be printed on the second surface is enlarged / reduced so as to substantially coincide with the image forming position on the first surface, the image formed on the second surface of the recording medium by the image forming means Formation is made.

  Thus, by comparing the actual image size formed on the first surface with the original image size, the actual expansion / contraction state of each recording medium after the image is formed on the first surface (the recording medium Change in the image size of the first surface due to expansion / contraction), and the magnification / reduction ratio of the image on the second surface is determined based on the comparison result. Even if the expansion / contraction rate of the recording medium changes, the image positions of both the first surface and the second surface can be made uniform. Further, it is not necessary to store in advance the setting values such as for each paper type and for each temperature of the fixing device, so that the memory capacity can be saved.

  Note that images formed during image formation vary, and it may be difficult to measure the size of the image itself formed on the first surface of the recording medium.

  In order to cope with such a case, in the above image forming system, as described in claim 2, an index for image size measurement is added at the time of image formation of the first surface. The image forming apparatus further includes index adding means for forming an image, and the image size measuring means detects a position of the index formed on the first surface, and an image formed on the first surface based on the detected position. It is better to ask for the size.

  According to a third aspect of the present invention, the image size measuring unit measures the size of the recording medium after the image is formed on the first surface, and the first size is based on the measurement result. You may make it obtain | require the size of the image formed in the surface.

  As described above, according to the present invention, the actual image size formed on the first surface is measured and compared with the original image size. The expansion / contraction state (change in the image size of the first side due to the expansion / contraction of the recording medium) can be grasped, and the image to be printed on the second side is enlarged / reduced based on the comparison result, thereby increasing the memory capacity. The image position on both sides of the recording medium can be aligned without causing the image to be aligned.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[Image forming system]
FIG. 1 is a diagram showing an overall schematic configuration of an image forming system according to the present embodiment. The image forming system includes a high-speed LAN (Local Area Network) using a general-purpose communication protocol, and a client terminal for inputting, for example, electronic data (print data) described in a page description language (PDL) to the high-speed LAN. 400 and 402 are connected. The client terminals 400 and 402 are computers capable of executing various application programs under different operating systems (OS). A scanner device 410 that reads an image of a document and outputs the image data is also connected to the high-speed LAN. The high-speed LAN includes DFE devices 500, 502, 504, 506, and 508, BEP (Back End Processor) devices 600, 602, and 604 as image forming support devices according to the present invention, which will be described in detail later. A CTP device 702 that directly creates a printing plate with data is connected.

  Printing is performed in the press device 710 using the printing plate created by the CTP device 702. Further, a BEP device 600 is connected to the CTP device 702 in parallel (to a high-speed LAN). A high-speed printer 746 similar to the image forming apparatus 11 is connected to the BEP device 600.

  An output device 730, high-speed printers 740 and 742 having the same configuration, and a CTP device 700 are connected to the output side of the BEP device 604 connected to the high-speed LAN. The output device 730 and the high-speed printers 740 and 742 perform print output, and the CTP device 700 creates a printing plate. The DFE device 502 is connected to printer proofers 720 and 722 having the same configuration via the BEP device 602. The printer proofers 720 and 722 are for confirming output for printing, and may function as an image forming apparatus.

  The DFE device 504 is connected to a high-speed printer 744 similar to that of the image forming apparatus 11, and the DFE device 504 and the high-speed printer 744 are responsible for a department in charge of on-demand printing processing. The DFE device 506 is connected to the output device 732, and the DFE device 508 is connected to the large output device 750. The configuration including the DFE device 506 and the output device 732 and the configuration including the DFE device 508 and the large output device 750 are the same as the configuration of the conventional image forming apparatus.

  The image forming system according to the present embodiment has a configuration in which CTP and an apparatus having a POD (print on demand) function can be mixed in the same system. This is because the BEP device according to the present embodiment has a function for variously processing the data after the print data from the client is converted into raster data (RIP processing).

[Configuration example]
In the image forming system having the above configuration, in order to simplify the description of the embodiment of the present invention, a representative example of a configuration in which a printing plate is created and printed and a configuration in which printing is performed without creating a printing plate are described as an embodiment. Will be described. That is, the configuration A in the case of forming an image using the client terminal 400, the DFE device 500, the CTP device 702, and the press device 710, the client terminal 400, the DFE device 500, the BEP device 600, and the high-speed printer 746 ( The configuration B in the case of forming an image using the apparatus of the image forming apparatus 11) will be described.

  The DFE device 500 has a function of converting data from the client terminal 400 into raster data (RIP processing) and compressing the converted raster image. In this embodiment, the DFE device 500 has a high-speed printer 746 (image It does not require a printer controller function that performs a print control function depending on the forming apparatus 11). That is, the DFE device 500 may have a configuration mainly having only a function of RIP processing. Although detailed description is omitted, in the case where reading data is input from the scanner device 410 instead of data from the client terminal 400, the DFE device 500 matches the characteristics of the scanner device 410. Shading correction, gray balance correction, and the like may be performed.

  FIG. 2 is a diagram showing an embodiment of an image forming system according to the present invention. In other words, the configuration A in which an image instructed to be printed by the client terminal 400 is RIPed by the DFE device 500 and a printing plate is created by the CTP device 702 and then printed by the press device 710, and the RIP image is sent via the BEP device 600. The configuration B for printing by the high-speed printer 746 (image forming apparatus 11) will be described as an embodiment of the image forming system according to the present invention. FIG. 2A shows an outline of a system configuration including the configuration A and the configuration B in the present embodiment, and FIG.

[Configuration A]
In the configuration A, printing is performed using a CTP device 702 that creates a printing plate, a DFE device 500 that outputs print data to the CTP device 702 and instructs printing plate creation, and a printing plate created by the CTP device 702. The press apparatus 710 constitutes a system.

  Since the configuration A is the same as the conventional print processing, detailed description thereof is omitted. However, the DFE apparatus 500 is configured by a front end processor (FEP) unit or ROP (Raster Operation) processing by a front engine. A function of converting data from the client terminal 400 into raster data (RIP processing) and compressing the converted raster image is provided. The DFE apparatus 500 mainly executes only the RIP process in order to create a printing plate. A plate is created by the CTP device 702 from the raster data of the RIP-processed raster image (compressed image). An image is pressed on a printing medium by a press device 710 using the printing plate created by the CTP device 702, and printing is performed.

  In the configuration A, the case where the CTP device 702 is connected to the high-speed LAN and the printing plate is created from the print data from the DFE device 500 has been described. However, the CTP device 702 is connected via the BEP device 600. Alternatively, the BEP device 604 and the CTP device 700 in FIG. 1 may be configured. In this case, as described in the configuration B below, the BEP apparatus 600 performs processing depending on the downstream apparatus such as the image forming apparatus 11 and outputs the data based on the print data from the DFE apparatus 500. When the CTP device 700 is adopted as the downstream device, the BEP device 600 performs processing depending on the CTP device 700 and outputs data.

[Configuration B]
Next, the configuration B is provided between the image forming apparatus 11 (high-speed printer 746), the DFE apparatus 500 that passes print data to the image forming apparatus 11 and gives a print instruction, and the image forming apparatus 11 and the DFE apparatus 500. A system is configured from the BEP device 600 to be used.

  The image forming apparatus 11 includes an IOT module (IOT main body) 12, a feed module (FM: Feeder Module) 15, an output module 17, a personal computer (PC) and the like corresponding to the image forming unit of the present invention. And a user interface device 18. The feed module 15 may have a multistage configuration. Moreover, you may provide the connection module which connects between each module as needed. In addition, a finisher module may be connected to the subsequent stage of the output module 17. As the finisher module, for example, there are a stacker for stacking sheets and a stapler for binding one or more places, or a punching mechanism for punching holes.

  The DFE device 500 has a function of converting data from the client terminal 400 into raster data (RIP processing) and compressing the converted raster image, and mainly performs RIP processing. This data is processed by the BEP device 600 and output to the image forming apparatus 11.

  The BEP device 600 has a process control function depending on the image forming apparatus 11, but this control function may be instructed by the user interface device 18 or may be determined in advance. When instructing by the user interface device 18, the user interface device 18 has an input device such as a keyboard or a GUI (Graphic User Interface) function that accepts an instruction input while presenting an image to the user, and depends on the image forming device 11. What is necessary is just to comprise so that a process may be instruct | indicated.

  The BEP device 600 enables efficient high-speed output by using the RIP processed data stored in the DFE device. That is, the BEP device 600 generates a command code based on the print control information received from the DFE device 500, and controls the processing timing of each unit in the image forming apparatus 11 according to the engine characteristics. In addition, the BEP device 600 completes the spool processing so as to match the engine characteristics of the IOT module 12, the feed module 15, the output module 17, etc., and then passes the image data to the IOT module 12.

  For example, data including a raster base image subjected to RIP processing is sent from the DFE device 500 to the BEP device 600. As this data, in addition to compressed raster-based image file data such as the TIFF (Tagged Image File Format) format, the number of copies, double-sided / single-sided, color / monochrome, composite printing, sort presence, presence / absence of stapler, etc. are printed. Control information and the like are included. Hereinafter, data in which various control commands related to the print processing are described as print control information is referred to as a job ticket.

  Rotation, page allocation (N-UP) in one sheet, repeat processing, sheet size adjustment, CMS (Color Management System) for correcting device differences, resolution conversion, contrast adjustment Processing related to RIP processing such as compression ratio designation (low / medium / high) is processed by the DFE device 500, and the control command is not notified to the BEP device 600 (non-notification).

  In addition, collation (booking), double-sided printing, stamping / punching / stapler finisher devices or paper tray alignment processing, discharge surface (up / down) alignment, calibration processing such as gray balance and color shift correction As for screen designation processing and the like (IOT-dependent processing) that is strongly related to the processing characteristics of the image forming apparatus 11, the BEP device 600 processes the control command through the DFE device 500.

  As described above, the DFE device side of this embodiment transfers one job (JOB) unilaterally to the BEP device side in the order of RIP processing without depending on the engine characteristics, and rearranges pages for printing on the BEP device side. To do.

  FIG. 3 is a conceptual block diagram that focuses on the flow of data when the BEP device 600 is interposed between the DFE device 500 and the image forming device 11.

  The DFE device 500 receives print data (hereinafter referred to as PDL data) described in PDL from the client terminal 400, and temporarily stores the PDL data once and reads the PDL data from the data storage unit 509 for interpretation. And RIP processing unit 510 that generates (rasterizes) image data (raster data) in units of pages, and a compression processing unit 530 that compresses the image data generated by RIP processing unit 510 according to a predetermined format. An interface unit 542 is provided following the compression processing unit 530. The RIP processing unit 510 develops PDL data to generate image data. Therefore, the RIP processing unit 510 incorporates a PDL interpretation unit and a decomposer functioning as an imager, a so-called RIP engine. The compression processing unit 530 compresses the image data from the RIP 510 and immediately transfers the compressed image data to the BEP device 600.

  On the other hand, the BEP device 600 receives and holds compressed image data processed by the DFE device 500 regardless of the print job and the processing characteristics of the print engine 30 (for example, processed asynchronously with the processing speed of the print engine 30). The image storage unit 605 that reads the compressed image data from the image storage unit 605, performs a decompression process corresponding to the compression process of the compression processing unit 530 on the DFE device 500 side, and stores the decompressed image data in the IOT An expansion processing unit 610 is provided for sending to the core unit 20 side. The decompression processing unit 610 has an image editing function such as image rotation, image position adjustment on paper, enlargement or reduction, and the like for image data read from the image storage unit 605 and decompressed. A data receiving unit 601 is provided in the previous stage of the image storage unit 605, and an output side interface unit 650 is provided in the subsequent stage of the decompression processing unit 610.

  The BEP device 600 also includes a print control unit 620 that functions as a printer controller that controls each unit of the BEP device 600 and the IOT core unit 20 depending on the processing performance of the IOT core unit 20. The print control unit 620 interprets (decodes) the job ticket from the DFE device 500 or receives a user instruction via the GUI unit 80, and outputs an output form (in accordance with the processing characteristics of the print engine 30, the fixing device 70, or the finisher). An output form specifying unit 622 for specifying the image position in the page or the page discharge order and orientation), and each part such as the print engine 30, the fixing device 70 or the finisher so that the printed matter is output in the specified output form. And a control unit 624 for controlling. The output form specifying unit 622 has a function as an output form information acquiring unit that receives information related to an output form desired by the client.

  Accordingly, in the DFE device 500, the image data rasterized (drawn and developed) from the page description language by the RIP processing unit 510 and compressed by the compression processing unit 530 is transferred to the BEP device 600 side in page order. The BEP device 600 temporarily stores the image data transferred from the DFE device 500 in the image storage unit 605 that functions as a buffer. The decompression processing unit 610 reads the compressed image data from the image storage unit 605 and decompresses it, and assembles page data according to a print job designated from the client terminal or the DFE device 500 (rearrangement of page data). Prepare for transfer to the designated print engine. The BEP device 600 sends page data to the IOT core unit 20 in a predetermined order at a speed that maximizes engine productivity while exchanging control commands in synchronization with the processing speed of the print engine 30.

  In this way, the DFE device 500 side only needs to unilaterally transfer one job (JOB) to the BEP device 600 side in the order of RIP processing without depending on the engine characteristics. The BEP device 600 is in charge of processing depending on the print job and the print engine 30 such as rearranging pages for printing.

  As described above, in the configuration B, the BEP device 600 having the printer controller function that performs control depending on the output side is interposed between the image forming apparatus 11 and the DFE device 500, and the BEP device 600 includes the DFE device 500 and the DFE device 500. When the sent image data is received, the image data is sequentially sent to the image recording device according to the processing characteristics on the output side, and the image recording device is controlled to perform the printing process. It can respond flexibly to functionalization.

  As a result, when processing or recovery processing adapted to an output form based on a request from a client is performed, it is possible to cope with the processing regardless of the front-end processor. That is, the processing related to the RIP processing is performed by the DFE device, but when the RIP processing needs to be performed again, the image storage unit does not request the DFE device 500 to perform the re-RIP processing (independent of the DFE device 500). The data held in 605 can be reused. Thereby, the re-RIP process in the DFE apparatus 500 becomes unnecessary. In addition, the BEP device 600 having a performance adapted to the processing characteristics on the output side such as the print engine can be processed depending on the processing characteristics on the output side in the BEP device 600 connected to the print engine 30 or the like.

  For example, when outputting in the output format desired by the client, an example of requiring processing that depends on processing characteristics on the output side, and reprocessing related to RIP processing is a page within one sheet. There are layout (N-UP), repeat processing, paper size adjustment, CMS (Color Management System) for correcting device differences, resolution conversion, contrast adjustment, compression rate designation (low / medium / high), and the like.

  In addition, as an example of the case where processing dependent on processing characteristics of the image forming apparatus 11 (for example, a print engine) on the output side (dependent processing strongly related to the processing characteristics on the output side) is required, image rotation (Rotation) is required. , Collation, double-sided printing, stamping, punching, stapler, and other finisher devices or paper trays (Shift: image shift), discharge surface (up / down) alignment, gray balance and color There are calibration processing such as misalignment correction and screen designation processing.

  When the proofer is configured by the BEP device, a color proof print is directly output from the DTP data by the printer proofer 720 prior to direct printing by the high-speed and high-function image forming device 11, for example, a digital direct color. Proofing) system can be constructed. In this system, when the proof data is received as a print job, the BEP device outputs image data in a data format suitable for proofing (for example, low video rate) to the proofer, and instructs the color proof print output. When a print job is received, image data at a high video rate is output to a high-speed and high-performance machine, and a high-speed and high-function print instruction is output. In this case, it is desirable to install a color management system (CMS) that corrects subtle differences (device differences) in different color outputs between the high-speed and high-function machine and the models connected to the proofer or cascade. .

[Configuration for duplex printing]
Next, a configuration relating to double-sided printing in the configuration B will be described.

  As described above, the image forming apparatus 11 is provided with the reverse conveyance path 49 for performing duplex printing. As shown in FIG. 4, the reverse conveyance path 49 includes a conveyance belt 49A that moves at a constant speed in the sheet conveyance direction, and an image is transferred to the front surface (corresponding to the first surface of the present invention) during duplex printing. The paper P after the fixing process by the fixing device 70 is placed on the transport belt 49A with the front side facing up, and is transported by the movement of the transport belt 49A.

  In the present embodiment, a line sensor unit 90 for reading an image from the paper P placed on the transport belt 49A and transported is provided above the transport belt 49A.

  The line sensor unit 90 includes a light source 90A for irradiating light toward the paper P on the conveyor belt 49A, and a plurality of CCDs (Charge Coupled Devices) with their light receiving surfaces facing the belt surface of the conveyor belt 49A. The CCD line sensor 90B arranged in a line over the width direction of the conveyance belt 49A (the direction orthogonal to the conveyance direction of the paper P) and the reflected light of the light output from the light source are imaged on the light receiving surface of each CCD. And a plurality of lenses 90C, which reads an image for each line and outputs an image signal indicating the read result. At this time, the image reading position on the paper P by the CCD line sensor 90B is moved by the paper P being transported to the transport belt 49A. Therefore, the line sensor unit 90 scans the paper P in the transport direction and scans the image. Can be read.

  In the present embodiment, the line sensor unit 90 is disposed in the reverse conveyance path 49, but the position of the line sensor unit 90 is not limited to this. It is sufficient that the printed image on the front side can be read before the paper P printed on the front side is printed on the back side (corresponding to the second side of the present invention). For example, the output of the fixing unit 70 such as the paper discharge tray stacker 74 can be read. The line sensor unit 90 may be disposed anywhere on the conveyance path of the paper P until it is passed to the IOT core unit 20 via the reverse conveyance path 49 later.

  The output of the line sensor unit 90 is connected to a print image size calculation unit 92 via an A / D converter (not shown) (see FIGS. 3 and 5). The print image size calculation unit 92 measures the actual size of the printed image (actual print image size) based on the read result of the image printed on the surface of the paper P by the line sensor unit 90. is there. Therefore, in the present embodiment, the line sensor unit 90 and the print image size calculation unit 92 constitute the image size measuring means of the present invention.

  The output of the print image size calculation unit 92 is connected to the BEP device 600 via an interface unit for communicating with the BEP device 600 (not shown), and the measurement result of the print image size by the print image size calculation unit 92 is the BEP. The device 600 is notified.

  On the other hand, on the BEP device 600 side, as shown in FIG. 3, the control unit 624 is provided with an enlargement / reduction control unit 626 that enlarges / reduces an image to be printed on the back side during double-sided printing.

  Specifically, as shown in FIG. 5, the enlargement / reduction control unit 626 uses a registration mark for printing a registration mark (hereinafter referred to as registration mark) T (refer to FIG. 4) in the margins of the four corners as an index for measuring the print image size. An additional processing unit 626A and a back side magnification setting unit 626B that sets an enlargement / reduction rate of an image to be printed on the back side based on the print image size notified from the image forming apparatus 11 are provided. The index for measuring the print image size may be other than the register mark as long as the mark has a predetermined shape.

  The registration mark addition processing unit 626A generates registration marks T in the margins at the four corners together with the original image to be printed on the front surface when the expansion processing unit 610 generates the page data for the front surface in accordance with the print job instructed for duplex printing. The decompression processing unit 610 is instructed to generate page data representing the added state. The page data generated in accordance with this instruction is output to the image forming apparatus 11, and printing is performed on the surface of the paper P in the image forming apparatus 11. Therefore, in the conveyance belt 49A, register marks T are printed in the margins at the four corners of the surface. The conveyed paper P is conveyed. That is, the registration mark addition processing unit 626A corresponds to the mark addition means of the present invention.

  Therefore, the above-described CCD line sensor 90B reads an image including the register mark T from the paper P. The print image size calculation unit 92 detects the registration marks T printed on the paper P from the image data input from the CCD line sensor 90B, and the detected distance between the registration marks is the actual print image size on the paper P. As a value corresponding to. At this time, the distance between the registration marks is calculated for each of the main scanning direction and the sub-scanning direction. Regarding the calculation of the distance between the registration marks T in the main scanning direction and the sub-scanning direction by providing a print image size calculation unit 92 on the BEP device 600 side and sending the reading result of the line sensor unit 90 to the BEP device 600. Alternatively, it may be performed on the BEP device 600 side.

  Also, the registration mark addition processing unit 626A has a distance between the added registration marks T in the original main scanning direction (corresponding to the width direction of the transport belt 49A) and the sub-scanning direction (corresponding to the transport direction of the paper P by the transport belt 49A). Is sent to the back side magnification setting unit 626B as a value corresponding to the size of the image to be originally printed (original print image size).

  The back surface magnification setting unit 626B receives the print image size notified from the image forming apparatus 11 (ie, the distance between the registration marks T obtained by the print image size calculation unit 92) and the original image size (ie, registration mark addition processing unit 626A). Is compared with the original distance between the register marks T notified from the above, and the change in the print image size due to the expansion / contraction of the paper P, that is, the expansion / contraction state of the paper P is obtained. Then, on the basis of the expansion / contraction state of the paper P, the enlargement / reduction ratio of the image to be printed on the back surface is determined so that the printing position on the back surface substantially coincides with the printing position on the front surface, and double-sided printing is instructed When the page data for the back side is generated by the expansion processing unit 610 according to the job, the expansion processing unit 610 is instructed to enlarge / reduce the image to be printed on the back side with the obtained enlargement / reduction magnification. The expansion processing unit 610 generates image data by enlarging / reducing the image to be printed on the back side according to this instruction, and the generated image data is output to the image forming apparatus 11 and printed on the back side of the paper P. Used for. That is, the back surface magnification setting unit 626B corresponds to the expansion / contraction means of the present invention.

[Operation when printing on both sides]
Next, with reference to FIGS. 6 and 7, as an operation of the present embodiment, an operation in the case of performing double-sided printing on a print job input from the client terminal 400 in the system of configuration B will be described. FIG. 6 shows the control processing executed by the control unit 624 (mainly the enlargement / reduction control unit 626) of the BEP device 600 in this case, and FIG. 7 shows the operation of the image forming apparatus 11 in this case.

  The DFE device 500 receives PDL data and a job ticket indicating the print processing contents from the client terminal 400 as a print job. When a print job is input, the DFE device 500 refers to the PIP data of the print job in the RIP processing unit 510 as a logical page because it differs from the page at the time of actual printing (when N-up is set, for example). ) And rasterize each time to generate image data, and the generated image data is compressed by the compression processing unit 530. At this time, among the various control commands related to the printing process described in the job ticket of the print job, the process according to the control command is simultaneously performed for the process related to the RIP process. Then, the DFE device 500 transmits the compressed image data and job ticket to the BEP device 600. The job ticket transmitted at this time describes a control command for instructing double-sided printing.

  When the BEP device 600 receives, as a print job, compressed image data and a job ticket in which a control command for instructing double-sided printing is described, the image data is stored in the image storage unit 605 and the job ticket is output. Interpreted (decoded) by the form specifying unit 622. When it is determined by the job ticket interpretation processing of the output form specifying unit 622 that the print job is instructed to be printed on both sides, the control unit 624 (mainly the enlargement / reduction control unit 626) performs the control processing shown in FIG. Executed.

  That is, the control unit 624 first causes the expansion processing unit 610 to generate image data for the surface with the registration marks added to the margins at the four corners by the registration mark addition processing unit 624 in step 200, and this generation is performed in the next step 202. The image data for the front surface is sent to the image forming apparatus 11 (IOT core unit 20), and the front surface is printed.

  As shown in FIG. 7, when the image forming apparatus 11 receives image data for the front surface from the BEP device 600, the process proceeds from step 300 to step 302, and an image is printed on the surface of the paper P based on this image data. That is, one sheet P loaded in the sheet tray 52 is taken out by the feed module 15 and supplied to the IOT core unit 20. In the IOT core unit 20, the print engine 30 is operated based on the surface image data from the BEP device 600 to form a toner image that is an image based on the surface image data, and the formed toner image is fed to the feed module 15. Then, the image is transferred to the paper P supplied from, and fixed (dissolved) by the fixing device 70. As a result, an image with the register mark T added to the margin is printed on the surface of the paper P. Since the paper P at this time expands and contracts due to heat during the fixing process, the image printed on the surface also expands and contracts due to the expansion and contraction, and is different from the original size. The paper P with the image printed on the front surface is temporarily held on the paper discharge tray 74, then pulled out from the paper discharge tray 74, transported by the reverse transport path 49, and reversed to the IOT core unit 20. Delivered again.

  In the next step 304, the image forming apparatus 11 scans an image from the surface of the sheet P being conveyed on the reverse conveyance path 49 by the line sensor unit 90 while scanning. Specifically, in the case of FIG. 4, the registration marks T1 and T2 arranged in the main scanning direction (corresponding to the width direction of the conveyor belt 49A) are first read by the line sensor unit 90, and then the print image portion and finally the main scanning are performed. The register marks T3 and T4 aligned in the direction are read.

  The results read by the line sensor unit 90 are sequentially sent to the print image size calculation unit 92 as line-unit image data. In the next step 306, the print image size calculation unit 92 uses the image data in the main scanning direction. The dragonfly T aligned is detected. The registration mark T can be easily detected from image data by pattern matching using image data for a plurality of continuous lines.

  If the registration mark T is not detected, the process returns from step 306 to step 304, and the image data of the next line is read by the line sensor unit 90, assuming that it is a part other than the registration mark, such as a blank portion before the registration mark T. If the registration mark T is detected, it is the first detection, and the process advances from step 306 to step 310 via step 308.

  In step 310, a distance in the main scanning direction between the registration marks T arranged in the main scanning direction is calculated as a value corresponding to the actual print image size in the main scanning direction. Accordingly, in the example of FIG. 4, the distance L1 between the register marks T1 and T2 is obtained as the actual print image size in the main scanning direction.

  Thereafter, the process returns to step 304 again to receive the image data of the next line, and in the next step 306, the register marks T aligned in the main scanning direction are detected again. If the registration mark T is not detected, it is determined that the part is a part other than the registration mark, such as a print image part, and the process returns from step 306 to step 304. If the registration mark T is detected, this time is the second detection. Go to step 312 via step 308.

  In step 312, as a value corresponding to the actual print image size in the sub-scanning direction, the sub-scanning direction (paper on the conveyor belt 49A) between the registration mark T detected first time and the registration mark T detected this time (second time). (Corresponding to the transport direction of P). Specifically, the distance between registration marks T in the sub-scanning direction (L2 in FIG. 4) is calculated by measuring the detection time difference t between the first and second registration marks and by the product (t × v) with the conveyance speed v. Is done. Accordingly, in the example of FIG. 4, the distance L2 between the registration marks T1 and T3 (or registration marks T2 and T4) is obtained as the actual print image size in the sub-scanning direction.

  In the next step 314, data indicating the distance between the registration marks T in the main scanning direction calculated in step 310 and the distance between the registration marks T in the sub-scanning direction calculated in step 312 is transmitted to the BEP device 600. . As a result, the BEP device 600 is notified of the actual print image size. Thereafter, the image forming apparatus 11 enters a standby state for the back side image data.

  When the BEP device 600 receives data indicating the distance between the registration marks T in the main scanning direction and the sub-scanning direction from the image forming device 11, that is, when the actual print image size is notified, the step from step 204 in FIG. Proceeding to 206, the back surface magnification setting unit 626B compares the distance between the register marks T in the original main scanning direction and the sub-scanning direction. As a result, the actual print image size in the main scanning direction and the sub-scanning direction are compared with the original print image size. By this comparison, the expansion / contraction state of the paper P (expansion / contraction of the paper P) is compared. Change in the size of the printed image on the surface).

  Subsequently, in the next step 208, on the basis of the comparison result, the enlargement / reduction ratio of the image printed on the back surface is determined so that the print positions of the front surface and the back surface are the same in each of the main scanning direction and the sub scanning direction. To do. In step 210, the decompression processing unit 610 generates page data for the back surface obtained by enlarging / reducing the image two-dimensionally at the determined magnification. Finally, in step 212, the generated image data for the back surface is converted into an image. The sheet is sent to the forming apparatus 11 (IOT core unit 20) and printing on the back side is executed, and the control process of FIG.

  When the image forming apparatus 11 receives the image data for the back side, the process proceeds from step 316 to step 318 in FIG. 7, and an image is printed on the front surface of the paper P based on the image data. That is, the IOT core unit 20 operates the print engine 30 based on the back side image data from the BEP device 600 to form a toner image that is an image based on the back side image data. Then, the toner image formed on the paper P that has been turned upside down by the reversing conveyance path 49 and sent again to the IOT core unit 20 is transferred, subjected to fixing processing (melting fixing) by the fixing device 70, and then discharged. It is discharged out of the machine via the device 72. Note that the paper P at this time hardly expands or contracts because it is after the fixing process is performed once at the time of surface printing.

  As described above, in the present embodiment, when performing double-sided printing, when printing on the front surface, the registration mark addition processing unit 626A, along with the original image to be printed, is an index for measuring the print image size in the four corners of the paper P. The decompression processing unit 610 generates page data that also prints the registration marks. Then, the image forming apparatus 11 prints the front surface based on the page data, and prints on the front surface by the line sensor unit 90 when the front surface printed paper is transported on the reverse transport path for back surface printing. The printed image is read, and the distance between the actual registration marks printed on the surface of the paper is calculated by the print image size calculation unit 92 based on the read result. The back surface magnification setting unit 626B compares the calculated distance as the actual print image size printed on the front surface of the paper with the original print image size (original distance between registration marks), thereby expanding the paper.・ Understand the contraction state and determine the enlargement / reduction ratio of the image to be printed on the back side.

  As a result, the expansion / contraction state of each sheet after front side printing can be actually detected, and the enlargement / reduction ratio of the back side image can be determined based on the expansion / contraction state. Even if the expansion / contraction rate changes suddenly due to temperature fluctuations of the fixing device, the positions of the front and back images can be made to coincide. Further, it is not necessary to store in advance the setting values such as for each paper type and for each temperature of the fixing device, so that the memory capacity can be saved.

  Further, there are various images to be printed, and it is difficult to measure the size of the image itself printed on the surface of the paper P. However, as in this embodiment, an index for measuring the print image size is used. Thus, the size of the print image can be easily measured. If, for example, two-sided printing of the same size photo image is performed, the print image size calculation unit 92 detects the boundary between the margin part of the surface of the paper P and the photo image, thereby printing the print image on the paper P. Since the size of itself can be easily measured, it is not necessary to use an index for measuring the print image size. In this case, the registration mark addition processing unit 626A can be omitted.

  In the above description, the index (print mark T) for measuring the print image size is printed in the margins at the four corners of the paper when printing on the surface of the duplex printing. However, the present invention is not limited to this. .

  In other words, the recording of the index for measuring the print image size can be performed by a method other than printing, for example, by forming a minute hole in the paper as the index for measuring the print image size, or by magnetic recording. It goes without saying that a sensor corresponding to the recording method is appropriately selected for detection. Further, the position and the number of indices for measuring the print image size are not limited to the above. For example, the registration marks T (for example, in FIG. 4) are provided only at two places on the same diagonal line in the margins at the four corners. Even when the registration marks T1 and T4 are recorded), the print image size in the main scanning direction and the sub-scanning direction can be measured.

  Alternatively, a sheet on which an index for measuring the print image size is recorded in advance may be loaded into the sheet tray 52 and used for printing in the image forming apparatus 11. In addition, if a print job in which a mark such as a register mark is originally printed in a margin part, such as collation (booking), without newly adding an index for measuring the print image size, This mark may be used as an index for measuring the print image size. In these cases, the register mark addition processing unit 626A can be omitted.

  By the way, when the margin part is cut in the subsequent process (for example, collation is specified), an index for measuring the print image size, such as printing the register mark T on the margin part as described above, is used. There is no problem even if it is recorded on the paper P, but there are cases where the printing result is not preferable in the state where the index for measuring the print image size is printed on the paper P.

  In such a case, the size of the paper P may be measured. That is, since the printed image on the surface is enlarged / reduced by expansion / contraction of the paper P, the actual print image size printed on the surface of the paper P can be grasped from the size of the paper P after expansion / contraction.

  Specifically, as described above, the line sensor unit 90 uses the CCD line sensor 90B in which CCDs are arranged in a line over the width direction of the transport belt 49A, and the line sensor unit 90 uses the width direction of the transport belt 49A. Since the image is read throughout, if the width dimension of the paper P is shorter than the width dimension of the transport belt 49A, the image including the transport belt 49A is read. In other words, if the width dimension of the conveyance belt 49 is designed to be longer than the width dimension of the paper P, the boundary between the conveyance belt 49A and the paper P can be detected from the reading result of the line sensor unit 90. The print image size calculation unit 92 may calculate the size of the paper P from the boundary detected by the boundary detection. In this case, in order to detect the boundary easily and with high accuracy, the conveyance belt 49A is made a color that can be easily distinguished from the paper P (for example, since the color of the paper is generally white, the conveyance belt 49A is black). Is preferable. In this case, since the index for measuring the print image size is not necessary, the registration mark addition processing unit 626A can be omitted.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. Various changes or improvements can be added to the above-described embodiment without departing from the gist of the invention, and embodiments to which such changes or improvements are added are also included in the technical scope of the present invention.

  Moreover, said embodiment does not limit the invention which concerns on a claim, and all the combinations of the characteristics demonstrated in embodiment are not necessarily essential for the solution means of invention. The embodiments described above include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. Even if some constituent requirements are deleted from all the constituent requirements shown in the embodiment, as long as an effect is obtained, a configuration from which these some constituent requirements are deleted can be extracted as an invention.

  For example, in the above description, the example in which the present invention is applied to a system in which the BEP apparatus 600 is installed between the DFE apparatus 500 and the image forming apparatus 11 has been described, but the present invention is not limited to this. The present invention can also be applied to a system including the image forming apparatus 11 and the DFE apparatus 500 as shown in FIG. Further, the enlargement / reduction control unit 626 may be provided in the image forming apparatus 11 so that the image forming apparatus 11 alone constitutes the image forming system of the present invention.

  In the compression / decompression process, image objects (line drawing character object LW (Line Work)) represented mainly by binary such as line drawings and characters, and background portions, photograph portions, etc. are mainly represented by multi-gradations. The processing can be adapted according to characteristics of an image object such as an image object (multi-tone image object CT (Continuous Tone)).

1 is a schematic diagram illustrating an overall configuration of an image forming system according to an exemplary embodiment. 1 is a diagram illustrating an embodiment of an image forming system. It is a block diagram which shows one Embodiment of a DFE apparatus and a BEP apparatus. FIG. 3 is a perspective view illustrating a reverse conveyance path of the image forming apparatus. FIG. 2 is a block diagram illustrating a configuration relating to double-sided printing of a BEP device and an image forming apparatus. 6 is a flowchart illustrating a control process executed by a control unit of a BEP device when a print job instructed to perform duplex printing is input. 6 is a flowchart illustrating an operation of the image forming apparatus during duplex printing. 1 is a diagram illustrating an outline of a conventional image forming system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Image forming apparatus 12 IOT module 15 Feed module 17 Output module 20 IOT core part 49 Reverse conveyance path 70 Fixing device 90 Line sensor part 92 Print image size calculation part 400, 402 Client terminal 410 Scanner apparatus 500, 502, 504, 508 DFE Device 600, 602, 604 BEP device 601 Data receiving unit 605 Image storage unit 610 Decompression processing unit 620 Print control unit 622 Output form specifying unit 624 Control unit 626 Enlargement / reduction control unit 626A Registration mark addition processing unit 626B Back surface magnification setting unit 700, 702 CTP Device 710 Press device 720, 722 Printer proofer 730, 732 Output machine 740, 744, 746 High speed printer 750 Large output machine T Dragonfly

Claims (3)

Image forming means capable of forming images on both sides of the recording medium;
Image size measuring means for measuring the size of the image formed on the first surface of the recording medium by the image forming means;
The size of the image measured by the image size measuring means is compared with the size of the image that should be originally formed, and based on the comparison result, the image forming position on the first surface is substantially matched. Enlargement / reduction means for enlarging / reducing an image to be formed on the second surface of the recording medium by the image forming means;
An image forming system comprising: An index adding means for forming an image with an image size measuring index added to the image forming means at the time of image formation on the first surface;
The image size measuring means detects the position of the index formed on the first surface, and obtains the size of the image formed on the first surface based on the detected position;
The image forming system according to claim 1. The image size measuring means measures the size of the recording medium after the image is formed on the first surface, and obtains the size of the image formed on the first surface based on the measurement result;
The image forming system according to claim 1.

Images