JP7639876B2 - Image forming system and image forming method - Google Patents

Description

The present invention relates to an image forming system and an image forming method .

Conventionally, there is an image forming system equipped with a printer capable of double-sided printing and an image reading device including a scanner, in which the front and back positions of an image formed on a sheet of paper are measured and adjusted using one scanner (see, for example, Patent Document 1).

Conventional technology such as that described in Patent Document 1 transports the paper twice in order to read the front and back positions of an image formed on the paper with a single scanner. Therefore, as the operation of reading the front and back positions of an image is performed for each sheet of 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.

JP 2006-072075 A

The present invention has been made to solve the problems of the related art, and its object is to provide an image forming system and an image forming method that can ensure that there is no difference in the position of images formed on multiple sheets of paper when continuously forming images on multiple sheets of paper .

In order to achieve the above object, an image forming system according to the present invention includes an image forming unit which forms an image of a mark on a sheet of paper, and a scanner which reads the image of the mark formed on the sheet of paper by the image forming unit, and when the image forming unit forms images continuously on a plurality of sheets of paper , a first reference position is determined based on information obtained by reading the image of the mark formed on a first sheet of paper among the plurality of sheets of paper by the scanner, and a position of the mark formed on a second sheet of paper after the first sheet of paper among the plurality of sheets of paper is adjusted so as not to differ from the first reference position . Also, an image forming method according to the present invention includes an image forming step of forming an image of a mark on a sheet of paper, and a reading step of reading the image of the mark formed on the sheet of paper in the image forming step by the scanner, and when the image forming step forms images continuously on a plurality of sheets of paper, a first reference position is determined based on information obtained by reading the image of the mark formed on the first sheet of paper among the plurality of sheets of paper by the reading step, and a position of the mark formed on a second sheet of paper after the first sheet of paper among the plurality of sheets of paper is adjusted so as not to differ from the first reference position .

According to the present invention, when images are continuously formed on a plurality of sheets of paper, it is possible to prevent a difference in the positions of the images formed on the plurality of sheets of paper .

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. 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. 1 is a diagram illustrating an example of the configuration of an image reading device 7 according to a first embodiment of the present invention. FIG. 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. 3A and 3B are diagrams illustrating an example of a mark A formed on a sheet P according to the first embodiment of the present invention. 7 is a diagram showing an example of transporting the same sheet P along a transport path 700 of the sheet P according to the first embodiment of the present invention. FIG. 4 is a flowchart illustrating an example of control in the first embodiment of the present invention. 11A to 11C are diagrams illustrating an example of adjusting the front and back positions of the mark A according to the first embodiment of the present invention. 7A to 7C are diagrams illustrating an example in which different sheets of paper P are transported along a transport path 700 of the sheets of paper P according to the first embodiment of the present invention. FIG. 7 is a diagram showing an example of a transport path 700 of a paper P according to a second embodiment of the present invention. 10 is a flowchart illustrating an example of control in the second embodiment of the present invention. 13A to 13C are diagrams illustrating an example of adjusting the front and back positions of a mark A according to a second embodiment of the present invention. 7A and 7B are diagrams illustrating an example in which different types of paper P are transported along a transport path 700 of the paper P according to a third embodiment of the present invention. 13 is a flowchart illustrating an example of control in the third embodiment of the present invention. 13A to 13C are diagrams illustrating an example of adjusting the front and back positions of the mark A according to the third embodiment of the present invention. 7 is a diagram showing an example of transporting the same sheet P along a transport path 700 of the sheet P according to a third embodiment of the present invention. FIG.

The following describes an embodiment of the present invention with reference to the drawings, but the present invention is not limited to the following embodiment.

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.

Next, the image forming device 5 will be described in detail. FIG. 2 is a diagram showing an example of the internal configuration of the image forming device 5 according to the first embodiment. As shown in FIG. 2, the image forming device 5 is an example of a color copier, 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 device 5 is suitable for use in color copiers, color printers or facsimile machines, and multifunction machines thereof.

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 feed unit 20, and a transport unit 30, the details of which will be described later.

Next, the automatic document feeder 14 will be described. The automatic document feeder 14 is provided above the image reading unit 12, and in the 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.

Specifically, the automatic document feeder 14 includes a document placement section 141, rollers 142a, 142b, 143, 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. The automatic document feeder 14 also includes a positioning detector 81 on the outer periphery of roller 143.

When the automatic feed mode is selected, the document T fed from the document loading section 141 is transported by rotating in a U-shape by the rollers 143. When the document T is loaded on the document loading section 141 and the automatic feed mode is selected, it is preferable that the recording surface of the document T is facing upward.

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

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 original T is detected, the output signal of the positioning detection unit 81 rises, and when the original T is no longer detected, the output signal falls, and the result is sent to the control unit 41. In other words, while the original T is passing through the positioning detection unit 81, the output signal maintains a constant value.

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, i.e., a color image printed on the original T. The image reading unit 12 is equipped with a one-dimensional image sensor 128. In addition to the image sensor 128, the image reading unit 12 is equipped 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 drive unit (not shown).

The light source 123 irradiates light onto the original T. An optical drive unit (not shown) moves the original T or the image sensor 128 relatively 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.

The original T is then 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 drive unit (not shown) drives the original T 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.

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 multiple light receiving element rows arranged in the main scanning direction. Specifically, the light detection reading sensors for 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 light 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 reading signal Sout.

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, and magnification processing 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., the 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.

Next, the image forming unit 60 will be described in detail. The image forming unit 60 uses electrophotographic process technology and forms color images using an intermediate transfer method. The image forming unit 60 employs a vertical tandem method.

Specifically, the image forming section 60 forms a color image based on the image data transferred from the image processing section 43, i.e., Dy, Dm, Dc, and Dk. 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 image.

Next, the image forming unit 601Y will be described. The image forming unit 601Y forms an image in Y (yellow) color. 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.

The photosensitive drum 613Y forms a Y-color toner image. The charging unit 614Y is arranged 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 unit 612Y visualizes the electrostatic latent image and forms a toner image by adhering toner of the Y color component to the surface of the photosensitive drum 613Y. The cleaning unit 616Y removes residual toner remaining on the surface of the photosensitive drum 613Y after the primary transfer.

Note that 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, so their description will be omitted.

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

Next, the intermediate transfer unit 620 will be described. The intermediate transfer unit 620 includes an intermediate transfer belt 621, primary transfer rollers 622Y, 622M, 622C, and 622K, a secondary transfer roller 623, and a belt cleaning device 624.

The intermediate transfer belt 621 is an endless belt that is stretched in a loop by multiple support rollers. At least one of the multiple support rollers is a drive roller, and the others are driven rollers. For example, it is preferable that the support roller that is located 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.

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 each color component. 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 the toner image from the photosensitive drums 613Y, 613M, 613C, and 613K to the intermediate transfer belt 621.

When referring to primary transfer rollers 622Y, 622M, 622C, and 622K collectively, they are referred to as primary transfer rollers 622.

The secondary transfer roller 623 is disposed on the outer peripheral surface side of the intermediate transfer belt 621, facing one of the multiple support rollers. 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.

When the intermediate transfer belt 621 passes through the primary transfer nip, the toner image on the photosensitive drum 613 is 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 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 image is electrostatically transferred to the intermediate transfer belt 621.

Then, 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 that contacts the secondary transfer roller 623, so that the toner image is electrostatically transferred to the paper P. The paper P with the transferred toner image is transported toward the fixing unit 630.

The belt cleaning device 624 has a belt cleaning blade that slides against the surface of the intermediate transfer belt 621. The belt cleaning device 624 removes residual toner remaining on the surface of the intermediate transfer belt 621 after the secondary transfer.

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.

Next, the fixing unit 630 will be described. The fixing unit 630 includes a heating 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.

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

In the fixing unit 630, the heating unit 633 heats the heating roller 631 in response to the detection result of the temperature detection unit 83, which 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.

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

Next, the paper feed unit 20 will be described. 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.

Next, the transport unit 30 will be described. The transport unit 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, and a registration roller 303.

The transport path 300 transports the paper P fed from the paper feed 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 transported by the branch unit 306 to the circulation paper path 307A, the reversal transport path 307B, and the re-feed transport path 307C in that order.

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

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

In other words, the control unit 41 controls the operation of the image forming device 5, 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.

Next, the image reading device 7 will be described in detail. FIG. 3 is a diagram showing an example of the configuration of the image reading device 7 in embodiment 1 of the present invention. FIG. 4 is a diagram showing an example of the functional configuration of the control unit 51 in embodiment 1 of the present invention.

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

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, a transport roller 731, and a transport path 700. The transport path 700 is a path along which paper P supplied from the image forming device 5 passes, and the paper P is transported by driving the transport roller 731.

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

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.

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, we will explain the mark A formed on the paper P.

Figure 5 is a diagram showing an example of mark A formed on paper P in embodiment 1 of the present invention. As shown in Figure 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 the mark A can detect misalignment between the front and back sides. Also, mark A does not have to be a crosshair.

Returning to FIG. 4, the monitoring unit 513 monitors the misalignment of the front and back of the mark A based on the front and back positions of the mark A adjusted by the position adjustment unit 511. The machine difference adjustment unit 515 adjusts the machine 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.

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 the adjustment reference position of the mark A that serves as the basis for monitoring the front-back position shift of the mark A by the monitoring unit 513.

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 reading 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 unexpected images. Meanwhile, the second scanner 701b reads the front side of the paper P, and performs an operation to read the image printed on the paper P, for example, a patch (not shown). Note that when there is no particular distinction between the first scanner 701a and the second scanner 701b, they are referred to as scanner 701.

The image reading device 7 operates in either an inline or offline manner.

The inline method is configured to feed paper P with an image formed thereon supplied from the image forming device 5 directly to the image reading device 7. On the other hand, the offline method is not configured to feed paper P with an image formed thereon supplied from the image forming device 5 directly to the image reading device 7, but rather is a method in which the image forming device 5 and the image reading device 7 are configured independently. Here, the following explanation will be given assuming the inline method, but the offline method may also be used.

The colorimeter 703 is located downstream of the scanner 701 and is disposed in a position facing the paper P passing 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.

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 performs a calculation into a predetermined color system based on the obtained spectrum to derive the color of the patch.

The color measurement results of the patch are generated as numerical data, i.e., colorimetric values, expressed in a predetermined color system, such as Lab color space data or XYZ color space data, and output to the control unit 51 or control unit 41.

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.

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

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

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 performed 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, etc.

In other words, the image processing unit 43 corrects the color, position, or magnification of the image to be formed on the paper P according to the results 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.

The calibration units 705a and 705b are positioned opposite the scanner 701 and reflect the light irradiated onto the paper P when reading an image.

Next, the transport path 700 will be described in detail. FIG. 6 is a diagram showing an example of transporting the same paper P on the transport path 700 for paper P in embodiment 1 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.

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

Therefore, the transport path 700 in FIG. 6 allows the first scanner 701a and the second scanner 701b to read the mark A formed on the same side of the same paper P.

In addition, if the paper P does not pass through the inversion path 751a, the first scanner 701a can read the first side P_1f of the paper P, and the second scanner 701b can read the second side P_2f of the paper P.

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

Note that the first side P_1f of the paper P refers to either the front side or the back side of the paper P, and the second side P_2f of the paper P refers to the other side of the front side or the back side of the paper P. This also applies to the following explanations.

6, the machine difference adjustment unit 515 adjusts the machine 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 transport path 700 of FIG. 6, when the monitoring unit 513 monitors the front-back positional deviation of the mark A formed on the paper P, it 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.

In addition, in the conveying 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 reference deviation amount monitored by the monitoring unit 513 and the second adjustment reference deviation amount monitored by the monitoring unit 513.

The adjustment of the front and back positions of mark A need only result in the adjustment of the front and back positions of mark A, and the specific adjustment process is not limited. 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 image forming device 5. Also, for example, a correction amount based on the reading result of each scanner 701 may be fed back to image forming device 5, and when image forming device 5 forms mark A on paper P, it may actually adjust the printing position of mark A.

Next, a control example of the control unit 51 on the transport path 700 in FIG. 6 will be described. FIG. 7 is a flowchart illustrating a control example in embodiment 1 of the present invention.

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.

The above steps S11 to S13 are the machine difference adjustment process.

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, an adjustment reference position is determined 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.

The above steps S14 to S16 are the process of determining the adjustment reference position when monitoring the front/back position misalignment of paper P.

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 misalignment 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 misalignment 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 misalignment of the first surface P_1f is adjusted, and the process proceeds to step S20. On the other hand, if it is determined that there is no misalignment 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.

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 misalignment 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 misalignment 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 misalignment 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 misalignment 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.

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

The above steps S17 to S23 are the monitoring process and position adjustment process.

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

In the following explanation, a high temperature and humidity environment will be referred to as an HH environment, a low temperature and low humidity environment will be referred to as an LL environment, and a general environment will be referred to as an NN environment.

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, 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.

The third problem is the deterioration of the mechanical durability of the printing machine itself. For example, if the various parts of the image forming device 5 deteriorate mechanically due to long-term use, misalignment of the printing position is likely to occur.

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 after each 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.

For example, if mechanical wear on the printing press body becomes severe, it is preferable to monitor every six hours. In other words, this is mid-term monitoring, and it is the case when it is suspected that there is a possibility of sudden misalignment of the front and back sides.

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. In other words, this is long-term monitoring, and it is assumed that sudden misalignment of the front and back sides is unlikely to occur.

Next, the adjustment of the machine difference and the adjustment of the front-back position misalignment will be described in detail. Figure 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 Figure 8 corresponds to the paper P 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.

Specifically, for the 0th sheet, an adjustment of the machine difference of each scanner 701 is performed before monitoring the misalignment between the front and back sides 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.

Furthermore, for the first sheet, a process is carried out to determine an adjustment reference position to be used for monitoring. For the second sheet and onwards, the front-to-back positional deviation of 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 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.

Even if the printing position of mark A matches the design value, if the adjustment reference position is determined for the first sheet, it will be adjusted so that there is no difference from the adjustment reference position determined for the first sheet.

Note that 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 P is transported on the transport path 700 for paper P in embodiment 1 of the present invention.

The transport path 700 in FIG. 9 is provided with a reversing path 751b upstream of the first scanner 701a. Therefore, the reversing path 751b in FIG. 9 allows the first scanner 701a to read a sheet P' with the first side P'_1f facing up, and the second scanner 701b to read a sheet 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 sheets P, P', i.e., the first side P_1f, 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.

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 of the paper P read by at least one of the first scanner 701a and the second scanner 701b.

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 mechanical difference of each scanner 701 is adjusted.

The image reading device 7 also monitors the misalignment of the front and back 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 results of the first scanner 701a, even if there is a machine difference between the first scanner 701a and the second scanner 701b, the misalignment of the front and back of the mark A can be monitored without being affected by the machine difference.

In addition, for example, if the front and back positions of the mark A are monitored based on the adjusted position 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.

In addition, 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 deviation in the front and back positions of the mark A with the machine difference between the first scanner 701a and the second scanner 701b adjusted.

In any case, the effects of differences between the scanners 701 can be eliminated without the need for mechanical adjustments.

In addition, because it is possible to detect the misalignment between the front and back of the mark A, it is possible to detect the misalignment between the front and back of an image formed based on the mark A. The misalignment between 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 when only the misalignment between the front and back of an image is detected. Therefore, even sudden misalignment between the front and back of an image can be easily detected.

In other words, the image reading device 7 adjusts the front-back position of the mark A based on the printing position 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 makes it possible to eliminate the influence of the machine differences of each scanner 701 without mechanical adjustment and to detect the front-back position shift of the mark A, thereby making it possible to accurately read the front-back position of the image formed on the paper P at low cost while easily detecting sudden front-back position shift of the image.

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, the adjustment reference position of the mark A that is the reference for monitoring the front-back positional deviation of the mark A is determined, and the adjustment reference position of the mark A becomes the reference in the state in which the machine difference of each scanner 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 twice with one scanner 701.

In addition, in the image reading device 7, the machine difference of 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 machine difference of each scanner 701 can be accurately detected.

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.

Therefore, the front and back positions of mark A are adjusted based on the relative front and back positional deviation of mark A, making it possible to monitor the front and back positional deviation of mark A at low cost.

In this way, according to this embodiment, it is possible to monitor the positional deviation between the front and back of the mark A without being affected by the mechanical differences 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. This makes it possible to form the image forming system 1 at low cost.

The differences between the scanners 701 are caused by a combination of various factors, such as individual lens differences, variations in lens mounting positions, and variations in the mounting positions of the scanners 701. In particular, 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 deviation in the front and back positions of the mark A without being affected by the differences between the scanners 701 will contribute to a significant reduction in the cost of the entire system when building the image forming system 1.

In addition, as the image forming device 5 performs double-sided printing, even if the print settings are not changed, misalignment between the front and back sides of the mark A, or image misalignment due to the misalignment between the front and back sides of the mark A, may occur. Such misalignment is sudden, as it occurs due to environmental conditions such as the temperature and humidity of the printing location or deterioration of the machine's durability. Therefore, conventionally, the front and back positions of the mark A are measured at regular intervals, but side effects also occur due to the frequency of measuring the front and back positions of the mark A.

For example, if the frequency of measuring the front and back positions of mark A is increased, the misalignment of the front and back positions of mark A can be detected early, but it takes more time, which reduces the productivity of the system as a whole. On the other hand, if the frequency of measuring the front and back positions of 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 mark A cannot be detected, and the output printed without the misalignment of the front and back positions of mark A being detected will be wasted, which will be a factor in increasing costs.

Therefore, if the positional deviation between the front and back of the mark A is monitored as in this embodiment, it is possible to easily detect sudden positional deviation between the front and back of the mark A caused by changes in environmental conditions, thereby reducing the cost of the entire system.

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

In addition, the image forming system 1 can easily and inexpensively detect the misalignment of the front and back of the output of the image forming device 5 using the image reading device 7, so the entire system can provide a low-cost feedback system.

In this way, according to the image reading device 7 of this embodiment, the image forming device 5 forms a mark A on both the front and back of the paper P, 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. The image reading device 7 is also 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.

This makes it possible to 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.

In addition, the image reading device 7 according to this embodiment further includes a machine difference adjustment unit 515 that adjusts the machine 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 machine difference is adjusted by the machine difference adjustment unit 515, the position adjustment unit 511 determines the adjustment reference position of the mark A that serves as the reference for monitoring the front-back position shift of the mark A by the monitoring unit 513.

As a result, if there is a positional shift between the front and back of the mark A, the image reading device 7 can reduce the time required to detect the positional shift between the front and back of the mark A compared to when the mark A is transported twice with one scanner 701.

In addition, in the image reading device 7 according to this embodiment, the machine difference adjustment unit 515 adjusts the machine difference based on the mark A formed on the same side of the paper P.

This allows the image reading device 7 to accurately detect the machine differences between each scanner 701.

In addition, 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 the first adjustment reference deviation amount between the 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 print position of the mark A formed on the first surface P_1f of the paper P read by the first scanner 701a, and 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 print 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.

This allows the image reading device 7 to monitor the misalignment of the front and back of the mark A at low cost.

The image forming system 1 according to this embodiment includes the image reading device 7 described above and an image forming device 5 that forms an image on paper P.

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.

In addition, the image forming system 1 can provide a low-cost feedback system as a whole system.

In addition, according to the program of this embodiment, the image forming device 5 forms a mark A on both sides of the paper P, and the computer that controls the image reading device 7, which 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, functions as a position adjustment unit 511 that 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, and a monitoring unit 513 that monitors the front and back position deviation of the mark A based on the front and back positions of the mark A adjusted by the position adjustment unit 511.

As a result, the program can accurately read the front and back positions of an image formed on paper P at low cost, just as in the case of the image reading device 7, while easily detecting sudden misalignment of the front and back positions of the image.

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.

Figure 10 is a diagram showing an example of a transport path 700 for paper P in embodiment 2 of the present invention. As shown in Figure 10, a first scanner 701a and a second scanner 701b are provided along the transport path 700. Therefore, the transport path 700 in Figure 10 allows the first scanner 701a to read the first side P_1f of the paper P, and the second scanner 701b to read the second side P_2f of the paper P.

When the machine difference of each scanner 701 is adjusted in the transport path 700 in FIG. 10, a master document is used as the paper P. The master document is one in which 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.

In addition, in the transport path 700 of FIG. 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.

In addition, in the transport path 700 in FIG. 10, when the machine difference adjustment unit 515 adjusts the machine difference of each scanner 701 using a master document, the position adjustment unit 511 sets the printing position of the mark A formed on the master document to the design reference position of the mark A as the adjustment reference position of the mark A.

In addition, in the transport path 700 of FIG. 10, when the monitoring unit 513 monitors the front-back positional deviation of the mark A formed on the paper P, it 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.

In addition, in the transport path 700 of FIG. 10, when the monitoring unit 513 monitors the front-back positional deviation of the mark A formed on the paper P, it 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.

In addition, in the conveying path 700 of FIG. 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.

Next, an example of control by the control unit 51 on the transport path 700 in FIG. 10 will be described. FIG. 10 is a diagram showing an example of the transport path 700 for paper P in embodiment 2 of the present invention.

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.

The above steps S41 to S43 are the machine difference adjustment process.

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

The process in step S44 is a process for determining the design reference position to be used when monitoring the front/back positional deviation of the paper P.

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 misalignment between the mark A formed on the first surface P_1f of the paper P and the first design reference position of the first surface P_1f among the design reference positions. If it is determined that there is a misalignment between the mark A formed on the first surface P_1f of the paper P and the first design reference position of the first surface P_1f among the design reference positions, the process proceeds to step S47, where the misalignment of the first surface P_1f is adjusted, and the process proceeds to step S48. On the other hand, if it is determined that there is no misalignment between the mark A formed on the first surface P_1f of the paper P and the first design reference position of the first surface P_1f among the design reference positions, the process proceeds to step S48.

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 misalignment between the mark A formed on the second surface P_2f of the paper P and the second design reference position of the second surface P_2f among the design reference positions. If it is determined that there is a misalignment between the mark A formed on the second surface P_2f of the paper P and the second design reference position of the second surface P_2f among the design reference positions, the process proceeds to step S50, where the misalignment of the second surface P_2f is adjusted, and the process proceeds to step S51. On the other hand, if it is determined that there is no misalignment between the mark A formed on the second surface P_2f of the paper P and the second design reference position of the second surface P_2f among the design reference positions, the process proceeds to step S51.

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

The above steps S45 to S51 are the monitoring process and position adjustment process.

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.

Specifically, for the 0th sheet, a machine error adjustment is performed for each scanner 701 before monitoring the front-to-back 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 is performed to set the design reference position to be used for monitoring.

Furthermore, for the first sheet and thereafter, the front-back positional deviation of the mark A is monitored based on the design reference 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 reference position set before the first sheet.

The design reference position for monitoring is set to the printing position of 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, it is adjusted to match the master document, so the design reference position for monitoring may be the printing position of mark A that has been adjusted for the machine difference on the 0th sheet.

In the above explanation, an example of using a master document has been described, but the document is not limited to the master document as long as there is no misalignment like in the master document. In other words, the document T may be one whose positional relationship can be read from the front and back with the same reference.

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 the passage of paper, such as a stapler needle.

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.

Therefore, the machine error of each scanner 701 is adjusted based on an absolute standard, and the positional deviation between the front and back of the mark A formed on the paper P is monitored based on an absolute standard, so that the machine error of each scanner 701 and the front and back positions of the mark A can be adjusted with high precision.

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.

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

From the above explanation, according to the image reading device 7 of this embodiment, when the machine 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 direction of penetration of the paper P, and the machine difference adjustment unit 515 adjusts the machine 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 the position adjustment unit 511 sets the printing position of the mark A formed on the master document to the design reference position of the mark A as the adjustment reference position of the mark A when the machine difference adjustment unit 515 adjusts the machine difference using the master document.

This allows the image reading device 7 to precisely adjust the machine differences between the scanners 701 and the front and back positions of the mark A.

In addition, 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 the 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 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, and monitors the 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 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, 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.

This allows the image reading device 7 to accurately monitor the misalignment of the front and back of the mark A.

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.

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

In the transport path 700 in FIG. 13, 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 side P_1f of the paper P read by the first scanner 701a and the printing position of the mark A formed on the second side P_2f of the paper P read by the first scanner 701a. Also, in the transport path 700 in FIG. 13, when the position adjustment unit 511 adjusts the front and back positions of the mark A, it determines an adjustment reference position of the mark A that serves as a reference for monitoring the front and back position deviation of the mark A by the monitoring unit 513.

In addition, in the transport path 700 in FIG. 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. In addition, in the transport path 700 in 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.

In addition, in the transport path 700 in FIG. 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.

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 embodiment 3 of the present invention.

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.

The above steps S71 to S75 are the process of determining the adjustment reference position when monitoring the front/back position misalignment of paper P.

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 misalignment 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 misalignment 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 misalignment of the first surface P_1f is adjusted, and the process proceeds to step S79. On the other hand, if it is determined that there is no misalignment 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.

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 misalignment 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 misalignment 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 misalignment of the second surface P_2f is adjusted, and the process proceeds to step S82. On the other hand, if it is determined that there is no misalignment 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.

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

The above steps S76 to S83 are the monitoring process and position adjustment process.

Next, the adjustment of the front and back position deviation will be described in detail. FIG. 15 is a diagram showing an example of the adjustment of the front and back position of the mark A in embodiment 3 of the present invention. The 0th front and back in FIG. 15 corresponds to the paper P for front and back position adjustment performed before monitoring, and only the reading results of the first scanner 701a are used. The 1st front and back in FIG. 15 and thereafter correspond to the paper P for monitoring performed after the front and back position adjustment, and only the reading results of the second scanner 701b are used.

Specifically, on the 0th front/back printing, the first scanner 701a performs a 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.

In addition, during the first front and back printing, a process is carried out to determine the adjustment reference position to be used for monitoring. From the second front and back printing onwards, the front and back positional deviation of mark A is monitored based on the adjustment reference position determined during the first front and back printing. For example, on the nth sheet, the printing position of mark A on the second side P_2f read by the second scanner 701b is adjusted to match the second adjustment reference position determined on the first sheet.

Even if the printing position of mark A matches the design value, if the adjustment reference position is determined for the first sheet, it will be adjusted so that there is no difference from the adjustment reference position determined for the first sheet.

Note that 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 the above. 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 embodiment 3 of the present invention.

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. In addition, 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 cause the first scanner 701a to read the first side P_1f of the paper P the first time, and the second side P_2f of the paper P the second time. As a result, the reversing path 751a in FIG. 9 can cause each scanner 701 to read different sides of the same paper P, i.e., the first side P_1f and the second side P_2f.

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.

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 misalignment of the front and back positions of the mark A is determined.

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 each scanner 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 each scanner 701.

In addition, in the image reading device 7, the second scanner 701b monitors the amount of misalignment between the front and back of the mark A, and the misalignment between the front and back of the mark A is adjusted based on the monitoring results.

Therefore, even if there is a 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, so it is possible to monitor the positional deviation between the front and back of the mark A particularly notably without being affected by the difference between the scanners 701.

From the above explanation, according to the image reading device 7 of this embodiment, when 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 side P_1f of the paper P read by the first scanner 701a and the printing position of the mark A formed on the second side P_2f of the paper P read by the first scanner 701a, it determines the adjustment reference position of the mark A that becomes the basis for monitoring the front-back position deviation of the mark A by the monitoring unit 513.

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

In addition, according to the image reading device 7, the second scanner 701b reads the mark A formed on the paper P when the monitoring unit 513 monitors the front-back positional deviation of the mark A formed on the paper P, and when the monitoring unit 513 monitors the front-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-back position of the mark A based on the adjustment reference deviation amount monitored by the monitoring unit 513.

This makes it possible to monitor the misalignment of the front and back of the mark A particularly notably, without being affected by differences in the scanners 701.

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.

For example, in this 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 this is not particularly limited. 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.

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 limiting and the image reading signal Sout may be determined in a different color system, such as the L*a*b* color system.

REFERENCE SIGNS LIST 1 Image forming system 3 Paper feed device 5 Image forming device 7 Image reading device 8 Paper discharge device 9 Paper discharge tray 11 Image forming device main body 12 Image reading section 121 First platen glass 122 Second platen glass 123 Light source 124-126 Mirror 127 Imaging optical section 128 Image sensor 14 Automatic document feeder 141 Document placement section 142a, 142b, 143, 144 Roller 145 Reversal section 146 Paper discharge tray 20 Paper feed section 200 Paper feed cassette 201 Feed roller 30 Transport section 300 Transport path 302A Paper feed roller 302B, 302C, 302D Transport roller 303 Registration roller 304 Paper discharge roller 305 Paper discharge tray 306 Branching section 307A Circulating paper path 307B Reversing conveying path 307C Re-feeding conveying path 41 Control section 43 Image processing section 51 Control section 511 Position adjustment section 513 Monitoring section 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 section 613, 613Y, 613M, 613C, 613K Photosensitive drum 614, 614Y, 614M, 614C, 614K Charging section 616, 616Y, 616M, 616C, 616K Cleaning unit 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 Heating roller 632 Pressure roller 633 Heating unit 81 Positioning detection unit 83 Temperature detection unit 700 Conveying path 701 Scanner 701a First scanner 701b Second scanner 703 Colorimeter 705, 705a to 705c Calibration unit 731 Conveying roller 751, 751a, 751b Reversing path P Paper

Claims (17)

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 continuous images are formed 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 . The image forming system of claim 1, wherein the first paper is a single sheet of paper. The image forming system according to claim 2, wherein the first sheet is the first sheet in the continuous image formation. 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 that it does not 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. 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 . The image forming system according to claim 5, wherein the scanner includes 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. 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. The image forming system according to claim 7, wherein the first scanner and the second scanner are arranged offset in the paper transport direction. The image forming system according to any one of claims 1 to 8, wherein the scanner is an inline type. 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. The image forming system according to any one of claims 1 to 10, further comprising a colorimeter that measures the color of a patch formed on paper. 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. 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 formed as an image on a first sheet of paper among the multiple sheets of paper in the reading process, and the position of the mark formed as an image 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 . The image forming method according to claim 13, wherein the first paper is a single sheet of paper. The image forming method according to claim 14, wherein the first sheet is the first sheet in the continuous image formation. 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. 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