Image forming system and image forming method

Abstract

To provide an image forming system that can read the front and back positions of images formed on a sheet accurately at low cost, and can easily detect unexpected front and back misregistration of the images.SOLUTION: An image forming system comprises: an image forming unit that forms marks as images on a sheet; a conveying unit that conveys the sheet on which the images are formed by the image forming unit along a conveyance path 700; a scanner 701 that reads the marks formed on the sheet conveyed by the conveying unit; and an alignment adjustment unit that, during formation of continuous images continuing over a plurality of sheets, according to the deviation from a reference position that is determined based on positions of marks formed on the n-th sheet read by the scanner 701 and positions of marks formed as images on a sheet before the n-th sheet read by the scanner 701 during the continuous image formation, adjusts the positions of marks formed as images on a sheet after the n-th sheet during the continuous image formation.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an image forming system. and image forming method Regarding. [Background technology]

[0002] Conventionally, there has been an image forming system equipped with a printing machine capable of double-sided printing and an image reading device including a scanner, in which one scanner is used to measure and adjust the front and back positions of an image formed on paper (see, for example, Patent Document 1).

[0003] In the conventional technology described in Patent Document 1, the paper is transported twice in order to read the front and back positions of an image formed on the paper with one scanner. Therefore, as the operation of reading the front and back positions of an image is performed for each paper, the time required for transporting the paper to read the image formed on the paper increases. As a result, the productivity of the image forming system is reduced.

[0004] [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2006-072075 A Summary of the Invention [Problem to be solved by the invention]

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[0007]

[0009] The present invention has been made to solve the problems in the past, and its object is to When continuously forming images on multiple sheets of paper, it is necessary to prevent differences in the positions of the images formed on the multiple sheets of paper. Image forming system and image forming method The purpose of this invention is to provide [Means for solving the problem]

[0010] In order to achieve the above object, an image forming system according to the present invention includes an image forming unit that forms an image of a mark on a sheet of paper, and a scanner that reads the image of the mark formed on the sheet of paper by the image forming unit, and when the image forming unit continuously forms images on a plurality of sheets of paper, Among the plurality of sheets of paper The mark image formed on the first sheet is read by the scanner. Tori Based on the information obtained A first reference position is determined by The position of the indicia imaged on a second sheet after the first sheet. is the first reference position. So that there is no difference adjustment The image forming method according to the present invention includes an image forming step of forming a mark on a sheet of paper, and a reading step of reading the mark formed on the sheet of paper in the image forming step by a scanner, and when forming images continuously on a plurality of sheets of paper in the image forming step, Among the plurality of sheets of paper The mark formed as an image on the first sheet is read in the reading step. Tori Based on the information obtained The second 1 reference position and among the plurality of sheets of paper, The position of the indicia imaged on a second sheet after the first sheet. is the first reference position. So that there is no difference adjustment do.

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[0030] Effect of the Invention

[0031] According to the present invention, When continuously forming images on multiple sheets of paper, the position of the images formed on the multiple sheets of paper should be uniform. It is possible. [Brief description of the drawings]

[0032] [Figure 1] FIG. 1 is a diagram showing an example of an overall configuration of an image forming system 1 according to a first embodiment of the present invention. [Diagram 2] 1 is a diagram illustrating an example of the configuration of an image forming apparatus 5 according to a first embodiment of the present invention. [Diagram 3] 1 is a diagram showing an example of the configuration of an image reading device 7 according to a first embodiment of the present invention. [Figure 4] 2 is a diagram illustrating an example of a functional configuration of a control unit 51 according to the first embodiment of the present invention. [Diagram 5] 3 is a diagram showing an example of a mark A formed on a sheet P according to the first embodiment of the present invention. FIG. [Figure 6] 7 is a diagram showing an example of conveying the same sheet of paper P along a conveying path 700 of the sheet of paper P according to the first embodiment of the present invention. FIG. [Figure 7] 4 is a flowchart illustrating an example of control in the first embodiment of the present invention. [Figure 8] 10A to 10C are diagrams illustrating an example of adjusting the front and back positions of the mark A in the first embodiment of the present invention. [Figure 9]7 is a diagram showing an example in which different sheets of paper P are transported along a transport path 700 for the sheets of paper P according to the first embodiment of the present invention. FIG. [Figure 10] 7 is a diagram showing an example of a transport path 700 for a paper sheet P according to a second embodiment of the present invention. [Figure 11] 10 is a flowchart illustrating an example of control in the second embodiment of the present invention. [Figure 12] 13A and 13B are diagrams illustrating an example of adjusting the front and back positions of a mark A in the second embodiment of the present invention. [Figure 13] 7 is a diagram showing an example in which different sheets of paper P are transported along a transport path 700 for the sheets of paper P according to a third embodiment of the present invention. FIG. [Figure 14] 13 is a flowchart illustrating a control example in the third embodiment of the present invention. [Figure 15] 13A to 13C are diagrams illustrating an example of adjusting the front and back positions of a mark A in the third embodiment of the present invention. [Figure 16] 7 is a diagram showing an example of conveying the same sheet of paper P along a conveying path 700 for the sheet of paper P according to a third embodiment of the present invention. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] Hereinafter, an embodiment of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiment.

[0034] Embodiment 1. Fig. 1 is a diagram showing an example of the overall configuration of an image forming system 1 according to a first embodiment of the present invention. As shown in Fig. 1, the image forming system 1 includes a paper feeder 3, an image forming device 5, an image reading device 7, and a paper discharge device 8. The paper feeder 3 feeds paper P to the image forming device 5. The image forming device 5 forms an image on the paper P fed from the paper feeder 3. The image reading device 7 reads the paper P on which an image has been formed by the image forming device 5, and executes various processes. The paper discharge device 8 includes a paper discharge tray 9, and discharges the paper P transported from the image reading device 7 to the paper discharge tray 9.

[0035] Next, the image forming apparatus 5 will be described in detail. Fig. 2 is a diagram showing an example of the internal configuration of the image forming apparatus 5 according to the first embodiment. As shown in Fig. 2, the image forming apparatus 5 is an example of a color copying machine, and is a device that obtains image information by reading a color image formed on an original T, and forms a color image by superimposing colors based on the obtained image information. The image forming apparatus 5 is suitable for use in color copying machines, as well as color printers or facsimile machines, and multifunction machines thereof.

[0036] The image forming device 5 includes an image forming device main body 11. A color image reading unit 12 and an automatic document feeder 14 are disposed on the upper portion of the image forming device main body 11. The image forming device main body 11 includes a control unit 41, an image processing unit 43, an image forming unit 60, a paper feeding unit 20, and a conveying unit 30, the details of which will be described later.

[0037] Next, the automatic document feeder 14 will be described. The automatic document feeder 14 is provided above the image reading unit 12, and in an automatic document feed mode, performs an operation of automatically feeding one or more documents T. Here, the automatic document feed mode is an operation of feeding the document T placed on the automatic document feeder 14 and reading the image printed on the document T.

[0038] Specifically, the automatic document feeder 14 includes a document placement section 141, rollers 142a, 142b, rollers 143, roller 144, a reversing section 145, and a paper discharge tray 146. One or more documents T are placed on the document placement section 141. Rollers 142a and 142b are provided downstream of the document placement section 141. Roller 143 is provided downstream of rollers 142a and 142b. In addition, the automatic document feeder 14 includes a positioning detection section 81 on the outer circumferential side of roller 143.

[0039] When the automatic feed mode is selected, the document T fed out from the document placement unit 141 is conveyed by rotating in a U shape by the rollers 143. When the document T is placed on the document placement unit 141 and the automatic feed mode is selected, it is preferable that the recording surface of the document T faces upward.

[0040] After being read by image reading unit 12, original T is transported by rollers 144 and discharged onto discharge tray 146. By transporting original T to reversing unit 145, automatic document feeder 14 can cause image reading unit 12 to read not only the recording surface of original T, but also the back side of the recording surface of original T.

[0041] Next, the positioning detection unit 81 will be described. The positioning detection unit 81 detects the original T on which an image is printed. The positioning detection unit 81 is composed of, for example, a reflective photosensor. When the positioning detection unit 81 detects the original T, the output signal rises, and when the original T is no longer detected, the output signal falls, and the result is transmitted to the control unit 41. In other words, during the period when the original T is passing through the positioning detection unit 81, the output signal maintains a constant value.

[0042] Next, the image reading unit 12 will be described. The image reading unit 12 operates to read a color image formed on the original T, that is, a color image printed on the original T. The image reading unit 12 is provided with a one-dimensional image sensor 128. In addition to the image sensor 128, the image reading unit 12 is also provided with a first platen glass 121, a second platen glass 122, a light source 123, mirrors 124, 125, and 126, an imaging optical unit 127, and an optical driving unit (not shown).

[0043] The light source 123 irradiates light onto the original T. An optical drive unit (not shown) relatively moves the original T or the image sensor 128 in the sub-scanning direction. Here, the sub-scanning direction is a direction perpendicular to the main scanning direction when the arrangement direction of the multiple light receiving elements that make up the image sensor 128 is defined as the main scanning direction.

[0044] Thus, the original T is transported by the automatic document feeder 14, and the image on one or both sides of the original T is scanned and exposed by the optical system of the image reading unit 12. Next, the incident light reflecting the image reading operation is read by the image sensor 128. In the Plato mode, the image sensor 128 outputs an image reading signal Sout in the RGB color system obtained by reading the original T. Here, the Plato mode is an operation in which an optical driving unit (not shown) drives to automatically read an image printed on the original T placed on a platen glass such as the first platen glass 121 or the second platen glass 122.

[0045] Next, the image sensor 128 will be described in detail. A three-line color CCD imaging device is used for the image sensor 128. The image sensor 128 is configured with a plurality of light receiving element rows arranged in the main scanning direction. Specifically, the reading sensors for detecting light of red (R), green (G), and blue (B) divide the pixels at different positions in the sub-scanning direction perpendicular to the main scanning direction, and simultaneously read the optical information of R, G, and B. For example, in the automatic paper feed mode, when the original T is inverted in a U-shape by the rollers 143, the image sensor 128 reads the surface of the original T and outputs an image read signal Sout.

[0046] More specifically, the image sensor 128 photoelectrically converts incident light and is connected to the image processing unit 43 via the control unit 41. The analog image reading signal Sout photoelectrically converted by the image sensor 128 is subjected to analog processing, A / D conversion, shading correction, image compression processing, magnification change processing, etc. in the image processing unit 43. As a result, the image reading signal Sout becomes digital image data including R color components, G color components, and B color components. The image processing unit 43 converts the image data, i.e., RGB code, into Y (yellow), M (magenta), C (cyan), and K (black) color image data, i.e., Dy, Dm, Dc, and Dk, using a three-dimensional color information conversion table. The image processing unit 43 transfers the converted image data to the LED writing units 611Y, 611M, 611C, and 611K included in the image forming unit 60.

[0047] Next, a detailed description will be given of the image forming unit 60. The image forming unit 60 uses electrophotographic process technology and forms color images by an intermediate transfer method. The image forming unit 60 employs a vertical tandem method.

[0048] Specifically, the image forming section 60 forms a color image based on the image data, i.e., Dy, Dm, Dc, and Dk, transferred from the image processing section 43. The image forming section 60 includes image forming units 601Y, 601M, 601C, and 601K for each color, an intermediate transfer section 620, and a fixing section 630 that fixes the toner images.

[0049] Next, the image forming unit 601Y will be described. The image forming unit 601Y forms an image of Y (yellow). The image forming unit 601Y includes a photosensitive drum 613Y, a charging unit 614Y, an LED writing unit 611Y, a developing unit 612Y, and a cleaning unit 616Y.

[0050] The photosensitive drum 613Y forms a Y-color toner image. The charging section 614Y is disposed around the photosensitive drum 613Y, and uniformly charges the surface of the photosensitive drum 613Y to a negative polarity by corona discharge. The LED writing unit 611Y irradiates the photosensitive drum 613Y with light corresponding to an image of the Y-color component. The developing section 612Y adheres toner of the Y-color component to the surface of the photosensitive drum 613Y, thereby visualizing the electrostatic latent image and forming a toner image. The cleaning section 616Y removes the transfer residual toner remaining on the surface of the photosensitive drum 613Y after the primary transfer.

[0051] Image forming units 601M, 601C, and 601K have the same configuration and function as image forming unit 601Y except for the color of the images they form, and therefore a description thereof will be omitted.

[0052] The image forming units 601Y, 601M, 601C, and 601K are collectively referred to as image forming units 601. The LED writing units 611Y, 611M, 611C, and 611K are collectively referred to as LED writing units 611. The developing units 612Y, 612M, 612C, and 612K are collectively referred to as developing units 612. The photosensitive drums 613Y, 613M, 613C, and 613K are collectively referred to as photosensitive drums 613. The charging units 614Y, 614M, 614C, and 614K are collectively referred to as charging units 614. The cleaning units 616Y, 616M, 616C, and 616K are collectively referred to as cleaning units 616.

[0053] Next, a description will be given of the intermediate transfer unit 620. The intermediate transfer unit 620 includes an intermediate transfer belt 621, primary transfer rollers 622Y, 622M, 622C, and 622K, a secondary transfer roller 623, a belt cleaning device 624, and the like.

[0054] The intermediate transfer belt 621 is an endless belt that is stretched in a loop shape by a plurality of support rollers. At least one of the support rollers is a drive roller, and the others are driven rollers. For example, it is preferable that the support roller disposed downstream of the primary transfer roller 622K for the K component in the belt running direction is a drive roller. As the drive roller rotates, the intermediate transfer belt 621 runs at a constant speed in the direction of the arrow Z.

[0055] The primary transfer rollers 622Y, 622M, 622C, and 622K are disposed on the inner circumferential surface side of the intermediate transfer belt 621, facing the photosensitive drums 613 of the respective color components. The primary transfer rollers 622Y, 622M, 622C, and 622K are pressed against the photosensitive drums 613Y, 613M, 613C, and 613K, sandwiching the intermediate transfer belt 621. This forms a primary transfer nip for transferring a toner image from the photosensitive drums 613Y, 613M, 613C, and 613K to the intermediate transfer belt 621.

[0056] The primary transfer rollers 622Y, 622M, 622C, and 622K are collectively referred to as primary transfer rollers 622.

[0057] The secondary transfer roller 623 faces one of the multiple support rollers and is disposed on the outer circumferential surface side of the intermediate transfer belt 621. The support roller disposed facing the intermediate transfer belt 621 is called a backup roller. The secondary transfer roller 623 is pressed against the backup roller with the intermediate transfer belt 621 sandwiched therebetween, thereby forming a secondary transfer nip for transferring a toner image from the intermediate transfer belt 621 to the paper P.

[0058] When the intermediate transfer belt 621 passes through the primary transfer nip, the toner images on the photosensitive drum 613 are primarily transferred onto the intermediate transfer belt 621 in a sequentially overlapping manner. Specifically, a primary transfer bias is applied to the primary transfer roller 622, and a charge of the opposite polarity to that of the toner is applied to the back side of the intermediate transfer belt 621, i.e., the side that contacts the primary transfer roller 622, so that the toner images are electrostatically transferred onto the intermediate transfer belt 621.

[0059] Thereafter, when the paper P passes through the secondary transfer nip, the toner image on the intermediate transfer belt 621 is secondarily transferred to the paper P. Specifically, a secondary transfer bias is applied to the secondary transfer roller 623, and a charge of the opposite polarity to the toner is applied to the back side of the paper P, i.e., the side in contact with the secondary transfer roller 623, so that the toner image is electrostatically transferred to the paper P. The paper P to which the toner image has been transferred is transported toward the fixing unit 630.

[0060] The belt cleaning device 624 has a belt cleaning blade or the like that slides and contacts the surface of the intermediate transfer belt 621. The belt cleaning device 624 removes untransferred toner remaining on the surface of the intermediate transfer belt 621 after the secondary transfer.

[0061] In addition, in the intermediate transfer section 620, instead of the secondary transfer roller 623, a so-called belt-type secondary transfer unit may be used in which a secondary transfer belt (not shown) is stretched in a loop shape around multiple support rollers including the secondary transfer roller 623.

[0062] Next, a description will be given of the fixing unit 630. The fixing unit 630 includes a heat roller 631, a pressure roller 632, a heating unit 633, and a temperature detection unit 83, and fixes the toner image transferred by the image forming unit 60 onto the paper P.

[0063] Specifically, heating unit 633 is provided inside heating roller 631 and intermittently heats heating roller 631. Pressure roller 632 is disposed opposite heating roller 631 and pressurizes heating roller 631. Temperature detection unit 83 is provided around heating roller 631 and detects the temperature of heating roller 631. The sampling period of temperature detection unit 83 is, for example, 100 ms.

[0064] In the fixing unit 630, the heating unit 633 heats the heating roller 631 in accordance with the detection result of the temperature detection unit 83 that detects the temperature of the heating roller 631. In the fixing unit 630, the heating roller 631 and the pressure roller 632 are pressed against each other to form a fixing nip between the heating roller 631 and the pressure roller 632.

[0065] The fixing unit 630 fixes the transferred toner image onto the paper P through the action of pressure from the pressure roller 632 and heat from the heating roller 631. An image is printed on the paper P on which the image has been fixed by the fixing unit 630. The paper P on which the image has been printed is discharged outside the machine by the paper discharge rollers 304, and is transported to, for example, the image reading device 7. Note that the paper P on which the image has been printed may be stacked on the paper discharge tray 305 without being transported to the image reading device 7.

[0066] Next, a description will be given of the paper feed unit 20. The paper feed unit 20 includes a paper feed cassette 200 and a feed roller 201. The paper feed cassette 200 stores paper P. The feed roller 201 takes in the paper P stored in the paper feed cassette 200 and sends it out to the transport unit 30.

[0067] Next, a description will be given of the transport section 30. The transport section 30 is configured with a transport path 300, and transports the paper P along the transport path 300. The transport path 300 includes a paper feed roller 302A, transport rollers 302B, 302C, and 302D, a registration roller 303, and the like.

[0068] The conveying path 300 conveys the paper P fed from the paper feeding unit 20 to the image forming unit 60. When an image is also formed on the back side of the paper P, after the image is formed on the front side of the paper P, the paper P is conveyed by the branching unit 306 to the circulation paper path 307A, the reversing conveying path 307B, and the re-feeding conveying path 307C in this order.

[0069] Next, the control system will be described. In the image forming apparatus 5, various processes are executed via the control unit 41. For example, the image reading signal Sout output from the image reading unit 12 is transmitted to an image memory (not shown) or an image processing unit 43 via the control unit 41. The image memory is, for example, a hard disk.

[0070] Specifically, the control unit 41 is mainly composed of a CPU, a ROM, a RAM, and an I / O interface (not shown). The control unit 41 controls the operation of each part of the image forming apparatus 5 by the CPU reading out various programs corresponding to the processing contents from the ROM or a storage unit (not shown), expanding the programs in the RAM, and working together with the various expanded programs.

[0071] That is, the control unit 41 controls the operation of the image forming apparatus 5, and can be realized by a microcomputer mainly composed of a CPU, a ROM, a RAM, and an I / O interface (not shown). The control unit 41 executes a predetermined control program to realize various functions.

[0072] Next, the image reading device 7 will be specifically described. Fig. 3 is a diagram showing an example of the configuration of the image reading device 7 in the first embodiment of the present invention. Fig. 4 is a diagram showing an example of the functional configuration of the control unit 51 in the first embodiment of the present invention.

[0073] The image reading device 7 is disposed downstream of the image forming device 5, and reads an image printed on one or both sides of the paper P. The image reading device 7 determines the amount of correction for the image based on the results of reading the color, position, magnification, and the like of the image printed on the paper P, and feeds back the determined amount of correction for the image to the image forming device 5.

[0074] The image reading device 7 includes a control unit 51, a first scanner 701a, a second scanner 701b, a colorimeter 703, calibration units 705a to 705c, transport rollers 731, and a transport path 700. The transport path 700 is a path along which the paper P supplied from the image forming device 5 passes, and the paper P is transported by the drive of the transport rollers 731.

[0075] For example, when the image reading device 7 receives a paper sheet P supplied from the image forming device 5, the image reading device 7 causes the first scanner 701a, the second scanner 701b, or the colorimeter 703 to detect the image formed on the paper sheet P. The result of the image detection is output to the control unit 51 of the image reading device 7.

[0076] The control unit 51 controls the operation of the image reading device 7, and can be realized by a microcomputer mainly composed of a CPU, ROM, RAM, and an I / O interface (not shown). The control unit 41 executes a predetermined control program to realize various functions including a position adjustment unit 511, a monitoring unit 513, and a machine difference adjustment unit 515, as shown in Fig. 4. The control unit 51 executes various processes based on the image detection results, and transmits the execution results to the control unit 41 of the image forming device 5.

[0077] The position adjustment unit 511 adjusts the front and back positions of the mark A based on the printing position of the mark A read by at least one of the first scanner 701a and the second scanner 701b. Here, the mark A formed on the paper P will be described.

[0078] Fig. 5 is a diagram showing an example of mark A formed on paper P in embodiment 1 of the present invention. As shown in Fig. 5, mark A is a crosshair and is used to detect misalignment between the front and back sides. Mark A is formed at a position T1 away from each corner of paper P in both the vertical and horizontal directions. Because paper P has four corners, four marks A are formed, but marks A do not need to be formed at all corners as long as misalignment between the front and back sides can be detected using mark A. Also, mark A does not have to be a crosshair.

[0079] Returning to Fig. 4, the monitoring unit 513 monitors the deviation in the front and back positions of the mark A based on the front and back positions of the mark A adjusted by the position adjustment unit 511. The mechanical difference adjustment unit 515 adjusts the mechanical difference between the first scanner 701a and the second scanner 701b based on the printing position of the mark A read by the first scanner 701a and the printing position of the mark A read by the second scanner 701b.

[0080] When the mechanical difference between the first scanner 701a and the second scanner 701b is adjusted by the mechanical difference adjustment unit 515, the position adjustment unit 511 determines an adjustment reference position of the mark A that serves as a basis for monitoring the front-back position shift of the mark A by the monitoring unit 513.

[0081] The first scanner 701a and the second scanner 701b are each disposed facing the paper P passing through the transport path 700, and read the image printed on the paper P. The first scanner 701a reads the back side of the paper P, and the read result is used, for example, to check for misalignment between the front and back of the image printed on the paper P, and to check for the presence or absence of an unexpected image. On the other hand, the second scanner 701b reads the front side of the paper P, and performs an operation of reading the image printed on the paper P, for example, a patch (not shown). Note that the first scanner 701a and the second scanner 701b will be referred to as scanner 701 when there is no particular distinction between them.

[0082] The image reading device 7 operates in either an in-line mode or an offline mode.

[0083] The inline system is configured to feed paper P with an image formed thereon, which is supplied from the image forming device 5, directly to the image reading device 7. On the other hand, the offline system is not configured to feed paper P with an image formed thereon, which is supplied from the image forming device 5, directly to the image reading device 7, but rather is configured such that the image forming device 5 and the image reading device 7 are independent of each other. Here, the following explanation will be given on the premise of the inline system, but the offline system may also be used.

[0084] The colorimeter 703 is located downstream of the scanner 701 and is disposed at a position facing the paper P passed through the transport path 700. The colorimeter 703 guarantees the absolute value of the color of the image formed on the paper P, for example, by measuring the color of a patch in the image formed on the paper P.

[0085] Specifically, the colorimeter 703 irradiates the patch with visible light from a visible light source (not shown), obtains the spectrum of the reflected visible light reflected by the calibration unit 705c, and based on the obtained spectrum, a calculation is performed into a predetermined color system to derive the color of the patch.

[0086] The color measurement results of the patches are generated as numerical data, ie, colorimetric values, expressed in a predetermined color system, for example, Lab color space data or XYZ color space data, and output to control unit 51 or control unit 41.

[0087] The color measurement range of the colorimeter 703, i.e., the viewing angle, is set to be narrower than the reading range of the scanner 701 and narrower than the width of the patch along the paper width direction. Specifically, the lens portion that captures the reflected light of the patch is, for example, about 4 mm.

[0088] In this way, the colorimeter 703 measures colors within a limited range of viewing angles, and therefore can reproduce color information with higher accuracy than the scanner 701.

[0089] Control unit 51 corrects color information of the patch read by scanner 701 based on the colorimetric value of the patch measured by colorimeter 703. Specifically, control unit 51 associates color information of the patch measured by colorimeter 703 with color information of the patch read by scanner 701. If color information of the patch measured by colorimeter 703 is associated with color information of the patch measured by scanner 701, the colorimetric result of colorimeter 703 can be reflected in the reading result of scanner 701, and an accurate correction amount can be obtained.

[0090] The image processing unit 43 optimizes the image to be formed by the image forming unit 60 based on the correction amount calculated by the control unit 51. The image optimization process executed by the image processing unit 43 includes adjustment of the front and back positions of the image to be printed on the paper P, density adjustment, color adjustment, and the like.

[0091] That is, the image processing unit 43 corrects the color, position, or magnification of the image to be formed on the paper P in accordance with the result of reading the paper P by the image reading device 7. Specifically, the image processing unit 43 corrects the image to be formed on the paper P based on the corrected color information. The image processing unit 43 issues a command to the image forming unit 60 to form an image on the paper P based on the correction result.

[0092] The calibration units 705a and 705b are disposed at positions facing the scanner 701, and reflect the light irradiated onto the paper P when an image is read.

[0093] Next, the transport path 700 will be specifically described. Fig. 6 is a diagram showing an example of transporting the same paper P on the transport path 700 for the paper P in the first embodiment of the present invention. As shown in Fig. 6, a reversing path 751a is provided between the first scanner 701a and the second scanner 701b along the transport path 700. The reversing path 751a reverses the paper P read by the first scanner 701a on the upstream side, and transports it to the second scanner 701b on the downstream side.

[0094] Therefore, when the paper sheet P passes through the inversion path 751a, the first scanner 701a can read the first side P_1f of the paper sheet P, and the second scanner 701b can read the first side P_1f of the paper sheet P.

[0095] Therefore, the conveying path 700 in FIG. 6 allows the mark A formed on the same surface of the same paper P to be read by the first scanner 701a and the second scanner 701b.

[0096] Furthermore, if the paper sheet P does not pass through the inversion path 751a, the first scanner 701a can read the first side P_1f of the paper sheet P, and the second scanner 701b can read the second side P_2f of the paper sheet P.

[0097] Therefore, the conveying path 700 in FIG. 6 allows the mark A formed on each of different sides of the paper P to be read by the first scanner 701a and the second scanner 701b.

[0098] In addition, the first side P_1f of the paper P means either the front side or the back side of the paper P, and the second side P_2f of the paper P means the other side of the front side or the back side of the paper P. The same applies in the following explanation.

[0099] 6, the mechanical difference adjustment unit 515 adjusts the mechanical difference of each scanner 701 based on the mark A formed on the same side of the paper P. Also, in the transport path 700 of FIG. 6, when monitoring the front-to-back positional deviation of the mark A formed on the paper P, the monitoring unit 513 monitors the first adjustment reference deviation amount between the first adjustment reference position of the mark A formed on the first side P_1f of the paper P among the adjustment reference positions of the mark A determined by the position adjustment unit 511 and the printing position of the mark A formed on the first side P_1f of the paper P read by the first scanner 701a. In addition, in the conveying path 700 of Figure 6, when monitoring the front-to-back positional deviation of the mark A formed on the paper P, the monitoring unit 513 monitors the second adjustment reference deviation amount between the second adjustment reference position of the mark A formed on the second surface P_2f of the paper P among the adjustment reference positions of the mark A determined by the position adjustment unit 511, and the printing position of the mark A formed on the second surface P_2f of the paper P read by the second scanner 701b.

[0100] Further, in the transport path 700 in FIG. 6, the position adjustment unit 511 adjusts the front and back positions of the mark A based on the first adjustment standard deviation amount monitored by the monitoring unit 513 and the second adjustment standard deviation amount monitored by the monitoring unit 513.

[0101] Note that the adjustment of the front and back positions of the mark A is not limited to a specific adjustment process as long as it results in the adjustment of the front and back positions of the mark A. For example, the reading time of each scanner 701 may be adjusted, and a correction amount based on the adjustment result may be fed back to the image forming apparatus 5. Also, for example, a correction amount based on the reading result of each scanner 701 may be fed back to the image forming apparatus 5, and when the image forming apparatus 5 forms the mark A on the paper P, the image forming apparatus 5 may actually adjust the printing position of the mark A.

[0102] Next, a description will be given of a control example of the control unit 51 in the transport path 700 in Fig. 6. Fig. 7 is a flowchart illustrating a control example in the first embodiment of the present invention.

[0103] In step S11, the first scanner 701a reads the mark A formed on the first side P_1f of the paper P. In step S12, the second scanner 701b reads the mark A formed on the first side P_1f of the paper P. In step S13, the mechanical difference between the first scanner 701a and the second scanner 701b is adjusted.

[0104] The above-mentioned processing in steps S11 to S13 constitutes the machine difference adjustment processing.

[0105] In step S14, the first scanner 701a reads the mark A formed on the first side P_1f of the paper P. In step S15, the second scanner 701b reads the mark A formed on the second side P_2f of the paper P. In step S16, based on the printing position of the mark A formed on the first side P_1f of the paper P and the printing position of the mark A formed on the second side P_2f of the paper P, an adjustment reference position is determined.

[0106] The above-mentioned processes in steps S14 to S16 are processes for determining the adjustment reference position to be performed when monitoring the positional deviation between the front and back sides of the paper P.

[0107] In step S17, the first scanner 701a reads the mark A formed on the first surface P_1f of the paper P. In step S18, it is determined whether or not there is a deviation between the mark A formed on the first surface P_1f of the paper P and the first adjustment reference position of the first surface P_1f among the adjustment reference positions. If it is determined that there is a deviation between the mark A formed on the first surface P_1f of the paper P and the first adjustment reference position of the first surface P_1f among the adjustment reference positions, the process proceeds to step S19, where the deviation of the first surface P_1f is adjusted in step S19, and the process proceeds to step S20. On the other hand, if it is determined that there is no deviation between the mark A formed on the first surface P_1f of the paper P and the first adjustment reference position of the first surface P_1f among the adjustment reference positions, the process proceeds to step S20.

[0108] In step S20, the second scanner 701b reads the mark A formed on the second surface P_2f of the paper P. In step S21, it is determined whether or not there is a deviation between the mark A formed on the second surface P_2f of the paper P and the second adjustment reference position of the second surface P_2f among the adjustment reference positions. If it is determined that there is a deviation between the mark A formed on the second surface P_2f of the paper P and the second adjustment reference position of the second surface P_2f among the adjustment reference positions, the process proceeds to step S22, where the deviation of the second surface P_2f is adjusted, and the process proceeds to step S23. On the other hand, if it is determined that there is no deviation between the mark A formed on the second surface P_2f of the paper P and the second adjustment reference position of the second surface P_2f among the adjustment reference positions, the process proceeds to step S23.

[0109] In step S23, it is determined whether or not the monitoring is to be ended. If it is determined that the monitoring is to be ended, the process ends. On the other hand, if it is determined that the monitoring is not to be ended, the process returns to step S17.

[0110] The above-mentioned processes in steps S17 to S23 constitute the monitoring process and the position adjustment process.

[0111] There are conditions that affect the occurrence of misalignment between the front and back of printing. The first is the environmental condition, which is the temperature and humidity of the printing location. Specifically, there are a high temperature and humidity environment, a low temperature and humidity environment, and a general environment. In a high temperature and humidity environment, the moisture content of the paper P is likely to increase, making it more likely for misalignment to occur. In a low temperature and low humidity environment, the paper P is more likely to slip, making it more likely for misalignment to occur. In a general environment, the paper P is stable, making it less likely for misalignment to occur.

[0112] In the following description, a high temperature and high humidity environment is referred to as an HH environment, a low temperature and low humidity environment is referred to as an LL environment, and a general environment is referred to as an NN environment.

[0113] The second is the paper P to be printed. Paper P can be high basis weight paper, large size paper, thick paper, etc. High basis weight paper is paper with a large basis weight, and is often thick paper P, so the moisture content is prone to change and the print position is likely to shift. Large size paper has a large print image, so the print position is likely to shift due to the print magnification. Thick paper is paper that is thick for its basis weight, so the moisture content is prone to change and the print position is likely to shift.

[0114] The third is mechanical deterioration of the printer body due to durability. For example, if the various parts of the image forming device 5 are mechanically deteriorated due to long-term use, misalignment of the print position is likely to occur.

[0115] The period for monitoring the front and back positions is set by the environmental conditions or the user. For example, when printing in an HH or LL environment, or when printing on thick paper P, it is preferable to monitor every time a copy is printed. In other words, this is a short-term monitoring in which it is assumed that sudden misalignment of the front and back positions is likely to occur.

[0116] Also, for example, if the mechanical wear of the printing press body becomes severe, it is preferable to monitor every six hours. In other words, it is a medium-term monitoring, and it is the case when it is suspected that there is a possibility of sudden front-back position deviation.

[0117] Also, for example, when printing in an NN environment or when printing on standard recommended paper, it is preferable to monitor once a day in the morning, that is, for a long period of time when it is assumed that sudden misalignment between the front and back sides is unlikely to occur.

[0118] Next, the adjustment of the machine difference and the adjustment of the front-back position deviation will be specifically described. Fig. 8 is a diagram showing an example of the adjustment of the front-back position of the mark A in the first embodiment of the present invention. The 0th sheet in Fig. 8 corresponds to the sheet P for the machine difference adjustment performed before monitoring, and the 1st sheet and onwards correspond to the sheets P for monitoring performed after the machine difference adjustment.

[0119] Specifically, for the 0th sheet, an adjustment of the machine difference between the scanners 701 is performed before monitoring the front-back positional deviation of the mark A formed on the paper P. For example, the printing position of the mark A on the first side P_1f read by the second scanner 701b is adjusted to match the printing position of the mark A read by the first scanner 701a.

[0120] Furthermore, for the first sheet, a process is performed to determine an adjustment reference position to be used for monitoring. For the second sheet and thereafter, the front-rear position shift of the mark A is monitored based on the adjustment reference position determined for the first sheet. For example, for the nth sheet, the printing position of the mark A on the second side P_2f read by the second scanner 701b is adjusted to match the second adjustment reference position determined for the first sheet.

[0121] Even if the printing position of the mark A matches the design value, when the adjustment reference position is determined for the first sheet, the printing position is adjusted so that there is no difference from the adjustment reference position determined for the first sheet.

[0122] In the case of the reversing path 751a provided on the transport path 700 in Fig. 6, the same paper P is read by each scanner 701, but this is not limited to the above. Fig. 9 is a diagram showing an example in which different paper sheets P are transported on the transport path 700 for the paper P in the first embodiment of the present invention.

[0123] The conveying path 700 in Fig. 9 is provided with a reversing path 751b on the upstream side of the first scanner 701a. Therefore, the reversing path 751b in Fig. 9 allows the first scanner 701a to read the paper P' with the first side P'_1f facing up, and the second scanner 701b to read the paper P with the first side P_1f facing down. As a result, the reversing path 751b in Fig. 9 allows each scanner 701 to read the same side of different papers P, P', i.e., the first side P_1f and the first side P'_1f. Note that when there is no need to distinguish between the reversing paths 751a and 751b, they are referred to as the reversing path 751.

[0124] As described above, the image reading device 7 adjusts the front and back positions of the mark A based on the printing positions of the mark A formed on the front and back sides of the paper P read by at least one of the first scanner 701a and the second scanner 701b.

[0125] For example, if the front and back positions of the mark A are adjusted based on the printing position of the mark A read by the first scanner 701a, the front and back position deviation of the mark A caused by the first scanner 701a alone is adjusted. Also, for example, if the front and back positions of the mark A are adjusted based on the printing position of the mark A read by the second scanner 701b, the front and back position deviation of the mark A caused by the second scanner 701b alone is adjusted. Also, for example, if the front and back positions of the mark A are adjusted based on the printing positions of the mark A read by each of the first scanner 701a and the second scanner 701b, the front and back position deviation of the mark A caused by the machine difference of each scanner 701 is adjusted.

[0126] Furthermore, the image reading device 7 monitors the deviation of the front and back positions of the mark A based on the adjusted front and back positions of the mark A. For example, if monitoring is performed based on the front and back positions of the mark A adjusted based on the reading result of the first scanner 701a, even if there is a machine difference between the first scanner 701a and the second scanner 701b, the deviation of the front and back positions of the mark A can be monitored without being affected by the machine difference.

[0127] Furthermore, for example, if monitoring is performed based on the front and back positions of the mark A adjusted based on the reading results of the second scanner 701b, even if there is a machine difference between the second scanner 701b and the first scanner 701a, the front and back position deviation of the mark A can be monitored without being affected by the machine difference.

[0128] Furthermore, for example, by monitoring based on the front and back positions of the mark A adjusted based on the respective reading results of the first scanner 701a and the second scanner 701b, it is possible to monitor the front and back position deviation of the mark A with the machine difference between the first scanner 701a and the second scanner 701b adjusted.

[0129] In any case, the influence of the differences between the scanners 701 can be eliminated without mechanical adjustment.

[0130] In addition, since the misalignment of the front and back of the mark A can be detected, it is possible to detect the misalignment of the front and back of an image formed based on the mark A. The misalignment of the front and back of the mark A can be easily detected without being overlooked, because the detection target is simple and limited, compared to the case where only the misalignment of the front and back of an image is detected. Therefore, even sudden misalignment of the front and back of an image can be easily detected.

[0131] In other words, the image reading device 7 adjusts the front-back positions of the mark A based on the printing positions of the mark A formed on the front and back of the paper P read by at least one of the first scanner 701a and the second scanner 701b, and monitors the front-back position shift of the mark A based on the adjusted front-back position of the mark A. This eliminates the influence of the machine differences of each scanner 701 without mechanical adjustment and can detect the front-back position shift of the mark A, so that the front-back positions of the image formed on the paper P can be accurately read at low cost while easily detecting sudden front-back position shift of the image.

[0132] In addition, in the image reading device 7, when the machine difference between the first scanner 701a and the second scanner 701b is adjusted based on the printing position of the mark A read by the first scanner 701a and the printing position of the mark A read by the second scanner 701b, an adjustment reference position of the mark A that is a reference for monitoring the front-back positional deviation of the mark A is determined, and the adjustment reference position of the mark A becomes a reference in a state in which the machine difference between the scanners 701 is adjusted, so that the front-back positional deviation of the mark A can be monitored using both the first scanner 701a and the second scanner 701b. Therefore, since the mark A formed on the front and back of the paper P can be monitored simultaneously in one conveyance, if there is a front-back positional deviation of the mark A, the time required to detect the front-back positional deviation of the mark A can be shortened compared to the case of conveying the paper P twice with one scanner 701.

[0133] In addition, in the image reading device 7, the mechanical difference between each scanner 701 is adjusted based on the mark A formed on the same side of the paper P. Since the mark A read by each scanner 701 is formed on the same side, the same comparison object is compared, and the mechanical difference between each scanner 701 can be accurately detected.

[0134] In addition, in the image reading device 7, a first adjustment reference deviation amount between the printing position of the mark A formed on the first side P_1f of the paper P read by the first scanner 701a and the adjustment reference position of the mark A formed on the first side P_1f of the paper P is monitored, and a second adjustment reference deviation amount between the printing position of the mark A formed on the second side P_2f of the paper P read by the second scanner 701b and the adjustment reference position of the mark A formed on the second side P_2f of the paper P is monitored, and the front and back positions of the mark A are adjusted based on the first adjustment reference deviation amount and the second adjustment reference deviation amount.

[0135] Therefore, since the front and back positions of the mark A are adjusted based on the relative front and back positional deviation of the mark A, the front and back positional deviation of the mark A can be monitored at low cost.

[0136] In this way, according to this embodiment, it is possible to monitor the front-back positional deviation of the mark A without being affected by the machine difference between the scanners 701. Therefore, there is no need for high-precision component accuracy and high-precision mounting position accuracy that are required when mechanically adjusting component accuracy and mounting position accuracy, etc. Therefore, the image forming system 1 can be formed at low cost.

[0137] The machine difference between the scanners 701 is caused by a combination of various factors such as individual lens differences, lens mounting position variations, and scanner 701 mounting position variations. In particular, the individual lens differences are caused by lens distortion, which causes deviations in magnification or partial magnification in the main scanning direction of reading. Therefore, being able to detect the front-rear position deviation of the mark A without being affected by machine differences between the scanners 701 contributes to a significant reduction in the cost of the entire system when constructing the image forming system 1.

[0138] Furthermore, as the image forming apparatus 5 performs double-sided printing, even if the print settings are not changed, the image position may shift between the front and back sides of the mark A, or the image may shift due to the shift between the front and back sides of the mark A. Such shifts are sudden, as they occur due to environmental conditions such as the temperature and humidity of the printing location or deterioration in the durability of the machine. Therefore, in the past, the front and back positions of the mark A were measured at regular intervals, but side effects also occur due to the frequency of measuring the front and back positions of the mark A.

[0139] For example, if the frequency of measuring the front and back positions of the mark A is increased, the misalignment of the front and back positions of the mark A can be detected early, but since it takes more time, the productivity of the entire system decreases. On the other hand, if the frequency of measuring the front and back positions of the mark A is decreased, more time can be allocated to production, but there is a risk that the misalignment of the front and back positions of the mark A cannot be detected, and the output printed without the misalignment of the front and back positions of the mark A being detected will be wasted, which will be a factor in increasing costs.

[0140] Therefore, by monitoring the front-back position shift of mark A as in this embodiment, sudden front-back position shift of mark A due to changes in environmental conditions can be easily detected, thereby reducing the cost of the entire system.

[0141] In other words, by being equipped with image reading device 7 and image forming device 5, image forming system 1 can, as in the case of image reading device 7, accurately read the front and back positions of an image formed on paper P at low cost while easily detecting sudden misalignment of the front and back positions of the image.

[0142] Furthermore, the image forming system 1 can easily and inexpensively detect misalignment between the front and back sides of the output of the image forming apparatus 5 by the image reading device 7, so that the entire system can provide a low-cost feedback system.

[0143] In this way, according to the image reading device 7 of this embodiment, a mark A is formed on the front and back of a sheet of paper P by the image forming device 5, and the image reading device 7 is equipped with a first scanner 701a that reads the mark A, and a second scanner 701b that is provided downstream of the first scanner 701a and reads the mark A, and is equipped with a position adjustment unit 511 that adjusts the front and back position of the mark A based on the printing position of the mark A read by at least one of the first scanner 701a and the second scanner 701b, and a monitoring unit 513 that monitors the front and back position deviation of the mark A based on the front and back position of the mark A adjusted by the position adjustment unit 511.

[0144] This makes it possible to accurately read the front and back positions of an image formed on a sheet of paper P at low cost, while easily detecting any sudden misalignment of the front and back positions of the image.

[0145] In addition, the image reading device 7 of this embodiment is further provided with a mechanical difference adjustment unit 515 that adjusts the mechanical difference between the first scanner 701a and the second scanner 701b based on the printing position of the mark A read by the first scanner 701a and the printing position of the mark A read by the second scanner 701b, and when the mechanical difference is adjusted by the mechanical difference adjustment unit 515, the position adjustment unit 511 determines an adjustment reference position of the mark A that serves as a basis for monitoring the front and back positional deviation of the mark A by the monitoring unit 513.

[0146] As a result, if there is a positional deviation between the front and back of the mark A, the image reading device 7 can reduce the time required to detect the positional deviation between the front and back of the mark A, compared to the case where one scanner 701 transports the mark A twice.

[0147] Moreover, in the image reading device 7 according to this embodiment, the machine difference adjustment section 515 adjusts the machine difference based on the mark A formed on the same side of the paper P.

[0148] This allows the image reading device 7 to accurately detect the machine difference between the scanners 701.

[0149] Furthermore, according to the image reading device 7 of this embodiment, when monitoring the front-back positional deviation of the mark A formed on the paper P, the monitoring unit 513 monitors a first adjustment reference deviation amount between a first adjustment reference position of the mark A formed on the first surface P_1f of the paper P among the adjustment reference positions of the mark A determined by the position adjustment unit 511 and the printing position of the mark A formed on the first surface P_1f of the paper P read by the first scanner 701a, and also monitors a second adjustment reference deviation amount between a second adjustment reference position of the mark A formed on the second surface P_2f of the paper P among the adjustment reference positions of the mark A determined by the position adjustment unit 511 and the printing position of the mark A formed on the second surface P_2f of the paper P read by the second scanner 701b, and the position adjustment unit 511 adjusts the front-back position of the mark A based on the first adjustment reference deviation amount monitored by the monitoring unit 513 and the second adjustment reference deviation amount monitored by the monitoring unit 513.

[0150] This allows the image reading device 7 to monitor the positional deviation between the front and back of the mark A at low cost.

[0151] Moreover, the image forming system 1 according to the present embodiment includes the image reading device 7 described above and the image forming device 5 that forms an image on the paper P.

[0152] As a result, the image forming system 1, like the image reading device 7, can accurately read the front and back positions of an image formed on paper P at low cost while easily detecting sudden misalignment of the front and back positions of the image.

[0153] Moreover, the image forming system 1 can provide a low-cost feedback system as a whole.

[0154] Furthermore, according to the program of this embodiment, a mark A is formed on each of the front and back sides of paper P by the image forming device 5, and a computer that controls an image reading device 7 equipped with a first scanner 701a that reads the mark A and a second scanner 701b that is provided downstream of the first scanner 701a and reads the mark A is made to function as a position adjustment unit 511 that adjusts the front and back position of the mark A based on the printing position of the mark A read by at least one of the first scanner 701a and the second scanner 701b, and a monitoring unit 513 that monitors the front and back position deviation of the mark A based on the front and back position of the mark A adjusted by the position adjustment unit 511.

[0155] This allows the program to accurately read the front and back positions of an image formed on paper P at low cost, as in the case of image reading device 7, while easily detecting sudden misalignment of the front and back positions of the image.

[0156] Embodiment 2. In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted. In the second embodiment, the machine difference of each scanner 701 is adjusted using a master document, and the front-back positional deviation of the mark A on the paper P is monitored using the mark A formed on the master document as a design reference.

[0157] Fig. 10 is a diagram showing an example of a transport path 700 for a sheet P in the second embodiment of the present invention. As shown in Fig. 10, a first scanner 701a and a second scanner 701b are provided along the transport path 700. Therefore, the transport path 700 in Fig. 10 allows the first scanner 701a to read the first side P_1f of the sheet P, and the second scanner 701b to read the second side P_2f of the sheet P.

[0158] 10, when the machine difference between the scanners 701 is adjusted, a master document is used as the paper P. In the master document, the printing position of the mark A formed on the first surface P_1f and the printing position of the mark A formed on the second surface P_2f are formed at the same position in the penetrating direction of the paper P.

[0159] In addition, in the transport path 700 of Figure 10, the mechanical difference adjustment unit 515 adjusts the mechanical difference of each scanner 701 based on the printing position of the mark A formed on the first side P_1f of the master document read by the first scanner 701a and the printing position of the mark A formed on the second side P_2f of the master document read by the second scanner 701b.

[0160] In addition, in the conveying path 700 of Figure 10, when the mechanical difference adjustment unit 515 adjusts the mechanical difference of each scanner 701 using a master document, the position adjustment unit 511 sets the printing position of mark A formed on the master document to the design standard position of mark A as the adjustment standard position of mark A.

[0161] In addition, in the conveying path 700 of Figure 10, when monitoring the front-to-back positional deviation of the mark A formed on the paper P, the monitoring unit 513 monitors the first design standard positional deviation amount between the printing position of the mark A formed on the first surface P_1f of the paper P read by the first scanner 701a and the first design standard position of the mark A formed on the first surface P_1f of the master document among the design standard positions of the mark A set by the position adjustment unit 511.

[0162] In addition, in the conveying path 700 of Figure 10, when monitoring the front-to-back positional deviation of the mark A formed on the paper P, the monitoring unit 513 monitors the second design standard positional deviation amount between the printing position of the mark A formed on the second surface P_2f of the paper P read by the second scanner 701b and the second design standard position of the mark A formed on the second surface P_2f of the master document among the design standard positions of the mark A set by the position adjustment unit 511.

[0163] In addition, in the conveying path 700 of Figure 10, the position adjustment unit 511 adjusts the front and back positions of the mark A based on the first design standard deviation amount monitored by the monitoring unit 513 and the second design standard deviation amount monitored by the monitoring unit 513.

[0164] Next, a description will be given of an example of control by the control unit 51 on the transport path 700 in Fig. 10. Fig. 10 is a diagram showing an example of a transport path 700 for the paper P in the second embodiment of the present invention.

[0165] In step S41, the first scanner 701a reads the mark A formed on the first side P_1f of the master document. In step S42, the second scanner 701b reads the mark A formed on the second side P_2f of the master document. In step S43, the mechanical difference between the first scanner 701a and the second scanner 701b is adjusted.

[0166] The above-mentioned processing in steps S41 to S43 constitutes the machine difference adjustment processing.

[0167] In step S44, the mark A formed on the master document is set to the design reference position.

[0168] The process of step S44 is a process for determining the design reference position to be performed when monitoring the positional deviation between the front and back sides of the paper P.

[0169] In step S45, the first scanner 701a reads the mark A formed on the first surface P_1f of the paper P. In step S46, it is determined whether or not there is a deviation between the mark A formed on the first surface P_1f of the paper P and the first design standard position of the first surface P_1f among the design standard positions. If it is determined that there is a deviation between the mark A formed on the first surface P_1f of the paper P and the first design standard position of the first surface P_1f among the design standard positions, the process proceeds to step S47, where the deviation of the first surface P_1f is adjusted in step S47, and the process proceeds to step S48. On the other hand, if it is determined that there is no deviation between the mark A formed on the first surface P_1f of the paper P and the first design standard position of the first surface P_1f among the design standard positions, the process proceeds to step S48.

[0170] In step S48, the second scanner 701b reads the mark A formed on the second surface P_2f of the paper P. In step S49, it is determined whether or not there is a deviation between the mark A formed on the second surface P_2f of the paper P and the second design standard position of the second surface P_2f among the design standard positions. If it is determined that there is a deviation between the mark A formed on the second surface P_2f of the paper P and the second design standard position of the second surface P_2f among the design standard positions, the process proceeds to step S50, where the deviation of the second surface P_2f is adjusted in step S50, and the process proceeds to step S51. On the other hand, if it is determined that there is no deviation between the mark A formed on the second surface P_2f of the paper P and the second design standard position of the second surface P_2f among the design standard positions, the process proceeds to step S51.

[0171] In step S51, it is determined whether or not monitoring is to be ended. If it is determined that monitoring is to be ended, the process ends. On the other hand, if it is determined that monitoring is not to be ended, the process returns to step S45.

[0172] The above-mentioned processes in steps S45 to S51 constitute the monitoring process and the position adjustment process.

[0173] Next, the adjustment of the machine difference and the adjustment of the front-back position deviation will be specifically described. Fig. 12 is a diagram showing an example of the adjustment of the front-back position of the mark A in the second embodiment of the present invention. The 0th sheet in Fig. 12 corresponds to the master document for the machine difference adjustment performed before monitoring, and the 1st sheet and onwards correspond to the paper P for monitoring performed after the machine difference adjustment.

[0174] Specifically, for the 0th sheet, an adjustment of the machine difference of each scanner 701 is performed before monitoring the front-rear positional deviation of the mark A formed on the master document. For example, the printing position of the mark A on the second side P_2f read by the second scanner 701b is adjusted to match the printing position of the mark A on the second side P_2f of the master document. In addition, before the first sheet for monitoring is read by each scanner 701, a process of setting the design reference position to be used for monitoring is performed.

[0175] Furthermore, for the first sheet and thereafter, the front-back positional deviation of the mark A is monitored based on the design standard position set before the first sheet. For example, for the nth sheet, the printing position of the mark A on the second surface P_2f read by the second scanner 701b is adjusted to match the second design standard position set before the first sheet.

[0176] The design reference position for monitoring is set to the printing position of the mark A formed on the master document, but is not limited to this. For example, when the machine difference adjustment is performed on the 0th sheet, the adjustment is made to match the master document, so the design reference position for monitoring may be the printing position of the mark A adjusted for the machine difference on the 0th sheet.

[0177] In the above description, an example in which a master document is used has been described, but the present invention is not limited to the master document, and may be any document T that has no misalignment like the master document. In other words, the present invention may be any document T whose positional relationship can be read from the front and back with the same reference.

[0178] Specifically, the document T may have a round or square hole that penetrates from the front to the back of the document T. In this case, it is possible to read the same hole position from both the front and back of the document T. The document T may also have a front / back position mark made of special ink that permeates from the front to the back of the document T, or from the back to the front of the document T. The document T may also have a member attached that penetrates from the front to the back of the document T and does not interfere with paper passage, such as a stapler needle.

[0179] As described above, in the image reading device 7, the machine difference of each scanner 701 is adjusted based on the mark A formed on the master document, and the mark A formed on the master document is set to the design reference position of the mark A.

[0180] Therefore, the mechanical error of each scanner 701 is adjusted based on an absolute standard, and the front-back position deviation of the mark A formed on the paper P is monitored based on the absolute standard, so that the mechanical error of each scanner 701 and the front-back position of the mark A can be adjusted with high precision.

[0181] In addition, in the image reading device 7, a first design standard deviation amount between the printing position of the mark A formed on the first side P_1f of the paper P read by the first scanner 701a and the design standard position of the mark A formed on the first side P_1f of the master document is monitored, and a second design standard deviation amount between the printing position of the mark A formed on the second side P_2f of the paper P read by the second scanner 701b and the design standard position of the mark A formed on the second side P_2f of the master document is monitored, and the front and back positions of the mark A are adjusted based on the first design standard deviation amount and the second design standard deviation amount.

[0182] Therefore, since the front and back positions of the mark A are adjusted based on the absolute front and back positional deviation of the mark A, the front and back positional deviation of the mark A can be monitored with high accuracy.

[0183] From the above explanation, according to the image reading device 7 of this embodiment, when the mechanical difference is adjusted, a master document is used as the paper P, and the printing position of the mark A formed on the first side P_1f of the master document and the printing position of the mark A formed on the second side P_2f of the master document are each formed at the same position in the penetrating direction of the paper P, and the mechanical difference adjustment unit 515 adjusts the mechanical difference based on the printing position of the mark A formed on the first side P_1f of the master document read by the first scanner 701a and the printing position of the mark A formed on the second side P_2f of the master document read by the second scanner 701b, and when the mechanical difference adjustment unit 515 adjusts the mechanical difference using the master document, the position adjustment unit 511 sets the printing position of the mark A formed on the master document to the designed standard position of the mark A as the adjustment standard position of the mark A.

[0184] This allows the image reading device 7 to accurately adjust the machine difference between the scanners 701 and the front and back positions of the mark A.

[0185] Furthermore, according to the image reading device 7 of this embodiment, when monitoring the front-back positional deviation of the mark A formed on the paper P, the monitoring unit 513 monitors a first design standard deviation amount between the printing position of the mark A formed on the first surface P_1f of the paper P read by the first scanner 701a and a first design standard position of the mark A formed on the first surface P_1f of the master document among the design standard positions of the mark A set by the position adjustment unit 511, and also monitors a second design standard deviation amount between the printing position of the mark A formed on the second surface P_2f of the paper P read by the second scanner 701b and a second design standard position of the mark A formed on the second surface P_2f of the master document among the design standard positions of the mark A set by the position adjustment unit 511, and the position adjustment unit 511 adjusts the front-back position of the mark A based on the first design standard deviation amount monitored by the monitoring unit 513 and the second design standard deviation amount monitored by the monitoring unit 513.

[0186] This allows the image reading device 7 to monitor the positional deviation between the front and back of the mark A with high accuracy.

[0187] Embodiment 3. In the third embodiment, the same components as those in the first and second embodiments are denoted by the same reference numerals, and the description thereof will be omitted. In the third embodiment, the second scanner 701b monitors the deviation of the front and back positions of the mark A based on the front and back positions of the mark A adjusted by the first scanner 701a.

[0188] FIG. 13 is a diagram showing an example of conveying different sheets of paper P on a conveying path 700 of the paper P according to the third embodiment of the present invention. The conveying path 700 in FIG. 13 is provided with an inversion path 751b on the upstream side of the first scanner 701a. The inversion path 751b in FIG. 13 conveys the face-up sheet of paper P conveyed from the upstream side face-down to the first scanner 701a on the downstream side. Therefore, if the sheet of paper P passes through the inversion path 751b, the first scanner 701a can read the second side P_2f of the sheet of paper P, and the second scanner 701b can read the first side P_1f of the sheet of paper P. Also, if the sheet of paper P does not pass through the inversion path 751b, the first scanner 701a can read the first side P_1f of the sheet of paper P, and the second scanner 701b can read the second side P_2f of the sheet of paper P.

[0189] 13, the position adjustment unit 511 adjusts the front-back position of the mark A based on the printing position of the mark A formed on the first surface P_1f of the paper P read by the first scanner 701a and the printing position of the mark A formed on the second surface P_2f of the paper P read by the first scanner 701a. Furthermore, in the transport path 700 of FIG. 13, when the position adjustment unit 511 adjusts the front-back position of the mark A, it determines an adjustment reference position of the mark A that becomes a reference for monitoring the front-back position deviation of the mark A by the monitoring unit 513.

[0190] 13, the second scanner 701b reads the mark A formed on the paper P when the monitoring unit 513 monitors the front-to-back positional deviation of the mark A. Also, in the transport path 700 of Fig. 13, when the monitoring unit 513 monitors the front-to-back positional deviation of the mark A formed on the paper P, the monitoring unit 513 monitors the adjustment reference position deviation amount between the adjustment reference position of the mark A determined by the position adjustment unit 511 and the printing position of the mark A read by the second scanner 701b.

[0191] 13, the position adjustment unit 511 adjusts the front and back positions of the mark A based on the adjustment reference deviation amount monitored by the monitoring unit 513.

[0192] Next, a control example of the control unit 51 in the transport path 700 in Fig. 13 will be described. Fig. 14 is a flowchart illustrating a control example in the third embodiment of the present invention.

[0193] In step S71, the first scanner 701a reads the mark A formed on the first surface P_1f of the paper P. In step S72, the first scanner 701a reads the mark A formed on the second surface P_2f of the paper P. In step S73, it is determined whether the front and back positions of the mark A have been adjusted. If it is determined that the front and back positions of the mark A have been adjusted, the process proceeds to step S75, where an adjustment reference position is determined based on the printing position of the mark A formed on the first surface P_1f of the paper P and the printing position of the mark A formed on the second surface P_2f of the paper P. On the other hand, if it is determined that the front and back positions of the mark A have not been adjusted, in step S74, the front and back positions of the mark A are adjusted based on the printing position of the mark A formed on the first surface P_1f of the paper P and the printing position of the mark A formed on the second surface P_2f of the paper P, and the process returns to step S71.

[0194] The above-mentioned processes in steps S71 to S75 are processes for determining the adjustment reference position to be performed when monitoring the positional deviation between the front and back sides of the sheet P.

[0195] In step S76, the second scanner 701b reads the mark A formed on the first surface P_1f of the paper P. In step S77, it is determined whether or not there is a deviation between the mark A formed on the first surface P_1f of the paper P and the first adjustment reference position of the first surface P_1f among the adjustment reference positions. If it is determined that there is a deviation between the mark A formed on the first surface P_1f of the paper P and the first adjustment reference position of the first surface P_1f among the adjustment reference positions, the process proceeds to step S78, where the deviation of the first surface P_1f is adjusted in step S78, and the process proceeds to step S79. On the other hand, if it is determined that there is no deviation between the mark A formed on the first surface P_1f of the paper P and the first adjustment reference position of the first surface P_1f among the adjustment reference positions, the process proceeds to step S79.

[0196] In step S79, the second scanner 701b reads the mark A formed on the second surface P_2f of the paper P. In step S80, it is determined whether or not there is a deviation between the mark A formed on the second surface P_2f of the paper P and the second adjustment reference position of the second surface P_2f among the adjustment reference positions. If it is determined that there is a deviation between the mark A formed on the second surface P_2f of the paper P and the second adjustment reference position of the second surface P_2f among the adjustment reference positions, the process proceeds to step S81, where the deviation of the second surface P_2f is adjusted in step S81, and the process proceeds to step S82. On the other hand, if it is determined that there is no deviation between the mark A formed on the second surface P_2f of the paper P and the second adjustment reference position of the second surface P_2f among the adjustment reference positions, the process proceeds to step S82.

[0197] In step S82, it is determined whether or not the monitoring is to be ended. If it is determined that the monitoring is to be ended, the process ends. On the other hand, if it is determined that the monitoring is not to be ended, the process returns to step S76.

[0198] The above-mentioned processes in steps S76 to S83 constitute the monitoring process and the position adjustment process.

[0199] Next, the adjustment of the front and back position deviation will be specifically described. Fig. 15 is a diagram showing an example of the adjustment of the front and back position of the mark A in the third embodiment of the present invention. The 0th front and back in Fig. 15 corresponds to the paper P for the front and back position adjustment performed before monitoring, and only the reading result of the first scanner 701a is used. The 1st front and back in Fig. 15 and thereafter correspond to the paper P for the monitoring performed after the front and back position adjustment, and only the reading result of the second scanner 701b is used.

[0200] Specifically, in the 0th front / back scan, the first scanner 701a performs front / back position adjustment before monitoring the front / back position deviation of the mark A formed on the paper P. For example, the printing position of the mark A on the second side P_2f read by the first scanner 701a is adjusted to match the printing position of the mark A on the first side P_1f read by the first scanner 701a.

[0201] Furthermore, in the first front and back printing, a process for determining an adjustment reference position to be used for monitoring is performed. In the second and subsequent front and back printings, the front and back positional deviation of the mark A is monitored based on the adjustment reference position determined in the first front and back printing. For example, in the nth sheet, the printing position of the mark A on the second side P_2f read by the second scanner 701b is adjusted to match the second adjustment reference position determined in the first sheet.

[0202] Even if the printing position of the mark A matches the design value, when the adjustment reference position is determined for the first sheet, the printing position is adjusted so that there is no difference from the adjustment reference position determined for the first sheet.

[0203] In the case of the reversing path 751b provided on the transport path 700 in Fig. 13, the front and back positions are adjusted for different sheets of paper P, but this is not limited to this. Fig. 16 is a diagram showing an example in which the same sheet of paper P is transported on the transport path 700 for the sheet of paper P in the third embodiment of the present invention.

[0204] The transport path 700 in FIG. 16 is provided with a reversing path 751a between the first scanner 701a and the second scanner 701b. Therefore, the first scanner 701a can read the paper P transported face-up. Also, the reversing path 751a can transport the paper P transported face-up face-down to the downstream side. Therefore, the reversing path 751a in FIG. 16 can make the first scanner 701a read the first side P_1f of the paper P the first time and read the second side P_2f of the paper P the second time. As a result, the reversing path 751a in FIG. 9 can make each scanner 701 read different sides of the same paper P, i.e., the first side P_1f and the second side P_2f.

[0205] As described above, in the image reading device 7, the first scanner 701a adjusts the front and back positions of the mark A based on the printing position of the mark A formed on the first surface P_1f of the paper P and the printing position of the mark A formed on the second surface P_2f of the paper P.

[0206] Furthermore, in the image reading device 7, when the front and back positions of the mark A are adjusted by the first scanner 701a, an adjustment reference position of the mark A that serves as a reference for the front and back position shift of the mark A is determined.

[0207] Therefore, since the positional deviation between the front and back of the mark A is monitored based on the reading result of the first scanner 701a, there is no need to adjust the machine difference between the scanners 701. Therefore, the positional deviation between the front and back of the mark A can be monitored without being affected by the machine difference between the scanners 701.

[0208] In the image reading device 7, the second scanner 701b monitors the amount of positional deviation between the front and back of the mark A, and the positional deviation between the front and back of the mark A is adjusted based on the monitoring result.

[0209] Therefore, even if there is a mechanical difference between the second scanner 701b and the first scanner 701a, the second scanner 701b only needs to detect the relative difference from the adjustment reference position of the mark A determined based on the reading result of the first scanner 701a, and therefore the front and back position deviation of the mark A can be monitored particularly remarkably without being affected by the mechanical difference between each scanner 701.

[0210] From the above explanation, according to the image reading device 7 of this embodiment, when the position adjustment unit 511 adjusts the front and back positions of the mark A based on the printing position of the mark A formed on the first surface P_1f of the paper P read by the first scanner 701a and the printing position of the mark A formed on the second surface P_2f of the paper P read by the first scanner 701a, it determines an adjustment reference position of the mark A that serves as a basis for monitoring the front and back position shift of the mark A by the monitoring unit 513.

[0211] This makes it possible to monitor the positional deviation between the front and back of the mark A without being affected by differences in the scanners 701 .

[0212] Furthermore, according to the image reading device 7, when the monitoring unit 513 monitors the front-to-back positional deviation of the mark A formed on the paper P, the second scanner 701b reads the mark A formed on the paper P, and when the monitoring unit 513 monitors the front-to-back positional deviation of the mark A formed on the paper P, the monitoring unit 513 monitors the adjustment reference deviation amount between the adjustment reference position of the mark A determined by the position adjustment unit 511 and the printing position of the mark A read by the second scanner 701b, and the position adjustment unit 511 adjusts the front-to-back position of the mark A based on the adjustment reference deviation amount monitored by the monitoring unit 513.

[0213] This makes it possible to monitor the positional deviation between the front and back of the mark A particularly remarkably without being affected by differences in the scanners 701 .

[0214] The image forming device 5 and image reading device 7 according to the present invention have been described above based on an embodiment, but the present invention is not limited to this, and modifications may be made without departing from the spirit of the present invention.

[0215] For example, in the present embodiment, an example of an arrangement in which the paper P is transported horizontally and the colorimeter 703 and the calibration unit 705 are provided above and below the paper P has been described, but the present invention is not particularly limited to this. For example, the paper P may be transported vertically and the colorimeter 703 and the calibration unit 705 may be provided to the left and right of the paper P.

[0216] In addition, an example has been described in which the image reading signal Sout is determined in the RGB color system as digital image data (RGB code) including R, G, and B color components, but this is not limited to this and the image reading signal Sout may be determined in a different color system such as the L*a*b* color system. [Explanation of symbols]

[0217] 1. Image forming system 3 Paper feeder 5. Image forming device 7 Image reader 8 Paper ejection device 9 Output tray 11 Image forming device main body 12 Image reading unit 121 First platen glass 122 Second Platen Glass 123 Light source 124~126 Mirror 127 Imaging optics 128 Image Sensor 14 Automatic document feeder 141 Document placement section 142a, 142b, 143, 144 Roller 145 Inversion section 146 Paper output tray 20 Paper feed section 200 Paper Cassette 201 Delivery roller 30 Conveyor 300 Transport Route 302A Feed roller 302B, 302C, 302D Transport rollers 303 Resist Roller 304 Paper ejection roller 305 Output Tray 306 Branch 307A Circulating paper path 307B Reversing conveyor 307C Refeed transport path 41 Control section 43 Image Processing Section 51 Control section 511 Position adjustment section 513 Monitoring Department 515 Machine difference adjustment section 60 Image forming section 601, 601Y, 601M, 601C, 601K Image forming unit 611, 611Y, 611M, 611C, 611K LED writing unit 612, 612Y, 612M, 612C, 612K Development Unit 613, 613Y, 613M, 613C, 613K Photosensitive drum 614, 614Y, 614M, 614C, 614K Charging section 616, 616Y, 616M, 616C, 616K Cleaning Department 620 Intermediate transfer unit 621 Intermediate transfer belt 622, 622Y, 622M, 622C, 622K Primary transfer roller 623 Secondary transfer roller 624 Belt cleaning device 630 Fixing unit 631 Heated Roller 632 Pressure Roller 633 Heating section 81 Positioning detection unit 83 Temperature detection unit 700 Transport Route 701 Scanner 701a 1st Scanner 701b 2nd Scanner 703 Colorimeter 705,705a~705c Calibration section 731 Transport Roller 751,751a,751b Reverse route P paper

Claims

1. an image forming unit that forms an image of a mark on a sheet; a scanner for reading a mark formed on a sheet by the image forming unit, An image forming system in which, when forming continuous images across multiple sheets of paper in the image forming section, a first reference position is determined based on information obtained by reading a mark image-formed on a first sheet of paper among the multiple sheets of paper with the scanner, and the position of the mark image-formed on a second sheet of paper after the first sheet of paper among the multiple sheets of paper is adjusted so that it does not differ from the first reference position.

2. 2. The image forming system according to claim 1, wherein the first paper is a single sheet of paper.

3. 3. The image forming system according to claim 2, wherein the first sheet is a first sheet in the continuous image formation.

4. An image forming system as described in any one of claims 1 to 3, wherein the position of a mark formed on the second sheet after the third sheet is adjusted so as not to differ from the first reference position based on a third position determined based on information obtained by reading the mark formed on the third sheet after the first sheet with the scanner and the first reference position.

5. the image forming unit forms an image of a first mark as a mark on a first surface of the paper and a second mark as a mark on a second surface of the paper opposite to the first surface; The scanner reads a first mark formed on the first side of the paper and reads a second mark formed on the second side of the paper; An image forming system as described in any one of claims 1 to 4, wherein when the image forming unit forms the continuous image across the multiple sheets of paper, the first reference position is determined based on information obtained by reading a first mark formed on the first sheet of paper with the scanner, and the position of the first mark formed as an image on the second sheet of paper is aligned with the first reference position, and a second reference position is determined based on information obtained by reading a second mark formed on the first sheet of paper with the scanner, and the position of the second mark formed as an image on the second sheet of paper is aligned with the second reference position.

6. The image forming system according to claim 5 , wherein the scanner comprises a first scanner that reads a first mark formed on the first side of the paper, and a second scanner that reads a second mark formed on the second side of the paper.

7. The scanner reads marks formed on a sheet of paper transported on a transport path, The image forming system according to claim 6 , wherein the first scanner and the second scanner are disposed on either side of the transport path.

8. The image forming system according to claim 7 , wherein the first scanner and the second scanner are arranged to be shifted from each other in a paper transport direction.

9. 9. The image forming system according to claim 1, wherein the scanner is of an in-line type.

10. The scanner reads the patch formed on the paper, 10. The image forming system according to claim 1, further comprising: a step of adjusting density and / or color of the image formed by the image forming unit based on color information of the read patch.

11. 11. The image forming system according to claim 1, further comprising a colorimeter for measuring the color of a patch formed on a sheet of paper.

12. 12. The image forming system according to claim 11, wherein a result of measuring the color of the patch by the colorimeter is reflected in color information of the patch read by the scanner.

13. an imaging step of imaging a mark on a sheet of paper; a reading step of reading the mark formed on the paper in the image forming step by a scanner, An image forming method in which, when continuously forming images across multiple sheets of paper in the image forming process, a first reference position is determined based on information obtained by reading a mark image formed on a first sheet of paper among the multiple sheets of paper in the reading process, and the position of the mark image formed on a second sheet of paper after the first sheet of paper among the multiple sheets of paper is adjusted so that it does not differ from the first reference position.

14. 14. The image forming method according to claim 13, wherein the first paper is one sheet of paper.

15. 15. The image forming method according to claim 14, wherein the first sheet is a first sheet in the continuous image formation.

16. In the image forming process, The image forming method according to any one of claims 13 to 15, further comprising adjusting a position of a mark formed on the second sheet of paper behind the third sheet of paper so as not to differ from the first reference position based on a third position determined based on information obtained by reading the mark formed on the third sheet of paper behind the first sheet of paper in the reading process and the first reference position.

17. In the image forming step, a first mark is formed as a mark on a first surface of the paper, and a second mark is formed as a mark on a second surface of the paper opposite to the first surface, The reading step includes reading a first mark formed on the first surface of the paper and reading a second mark formed on the second surface of the paper; The image forming method according to any one of claims 13 to 16, wherein when forming the continuous image across the plurality of sheets of paper in the image forming process, the first reference position is determined based on information obtained by reading a first mark formed on the first sheet of paper in the reading process, and the position of the first mark formed as an image on the second sheet of paper is aligned with the first reference position, and a second reference position is determined based on information obtained by reading a second mark formed on the first sheet of paper in the reading process, and the position of the second mark formed as an image on the second sheet of paper is aligned with the second reference position.

Images