Image forming apparatus, image forming method, and program

Abstract

To enable detection of color shift caused by local variation in a sub-scanning direction.SOLUTION: An image forming apparatus which forms a color image by superimposing a plurality of images on a medium, comprises: an image arrangement unit which arranges, in image forming data, a pattern including a first image formed of an image having a first color and a second image formed of an image having a second color different from the first color; a reading unit which reads an image formed on the medium using the image forming data; and a detection unit which detects positional deviation information on at least one of the image having the first color and the image having the second color on the basis of the image read by the reading unit.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus, an image forming method, and a program. [Background technology]

[0002] In production printing, there is a need to determine whether or not there is an abnormality in the print output of a printer. To address this, a technique is known in which the print output of a printer is read using a camera or a line sensor of a scanner, and the read results are used to check whether printing is being performed normally.

[0003] Patent document 1 discloses that the device includes a control unit that forms a resist patch outside the job image forming area of a recording medium, and a correction unit that corrects the image forming position of the formed image based on a read image including the resist patch, and that the resist patch has a reference color patch formed from a color material of a reference color and at least one measurement target color patch formed from a color material of each measurement target color. Summary of the Invention [Problem to be solved by the invention]

[0004] However, the conventional technology has a problem in that it is not possible to detect color misregistration caused by local variations in the sub-scanning direction.

[0005] The present invention has been made in view of the above, and has as its object to enable detection of color misregistration caused by local variations in the sub-scanning direction. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the object, the present invention provides an image forming device that forms a color image by superimposing multiple images on a medium, and is characterized by comprising: an image arrangement unit that arranges a pattern including a first image formed of an image having a first color and a second image formed of an image having a second color different from the first color in image formation data; a reading unit that reads the image formed on the medium using the image formation data; and a detection unit that detects positional deviation information of at least one of the image having the first color and the image having the second color based on the image read by the reading unit. [Effects of the Invention]

[0007] The present invention has the effect of being able to detect color misregistration caused by local variations in the sub-scanning direction. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 illustrates an example of a system configuration of an image forming apparatus according to the first embodiment. [Figure 2] FIG. 2 is a diagram illustrating an example of a hardware configuration of the printer unit. [Figure 3] FIG. 3 is a diagram illustrating an example of functional blocks of the printer unit. [Figure 4] FIG. 4 is a diagram showing an example of the format of the inspection chart. [Figure 5] FIG. 5 is a diagram showing an example of print data for an inspection chart to be placed on the left or right side of the paper. [Figure 6] FIG. 6 is a diagram showing an example of read data from the inspection chart. [Figure 7] FIG. 7 is a diagram showing the size and position of patterns arranged in the print data of the inspection chart. [Figure 8] FIG. 8 is a diagram showing the positions on the paper of the patterns arranged in the print data. [Figure 9] FIG. 9 is a diagram illustrating an example of a functional configuration of the chart generating unit. [Figure 10]FIG. 10 is a diagram showing an example of the chart setting screen. [Figure 11] FIG. 11 is a diagram showing an example of a screen displayed in the pattern setting area. [Figure 12] FIG. 12 is a diagram showing an example of a screen displayed in the paper setting area. [Figure 13] FIG. 13 is a diagram showing an example of the functional configuration of the inspection unit 20. As shown in FIG. [Figure 14] FIG. 14 is a diagram showing an example of a pattern of read data. [Figure 15] FIG. 15 is a diagram showing an example of a screen displayed in the display setting area. [Figure 16] FIG. 16 is a flowchart showing the procedure of the positional deviation determination process. [Figure 17] FIG. 17 is a diagram illustrating an example of a detection result generated in the detection process according to the first embodiment. [Figure 18] FIG. 18 is a diagram showing an example of another display method for the table of detection results according to the first embodiment. [Figure 19] FIG. 19 is a flowchart showing the procedure for obtaining statistical values of positional deviation information through detection processing. [Figure 20] FIG. 20 is a diagram showing an example of statistical values of the positional deviation information of each pattern generated in the detection process. [Figure 21] FIG. 21 is a diagram showing an example of print data and read data of a pattern of an inspection chart. [Figure 22] FIG. 22 is a diagram illustrating an example of a functional configuration of an inspection unit according to the second embodiment. [Figure 23] FIG. 23 is a diagram showing an example of coordinates of a pattern in print data and coordinates of each image in read data. [Figure 24] FIG. 24 is a diagram illustrating an example of a display setting area according to the second embodiment. [Figure 25] FIG. 25 is a diagram illustrating an example of a detection result generated by the detection process according to the second embodiment. [Figure 26]FIG. 26 is a diagram showing an example of another display method for a table of detection results according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An image forming apparatus, an image forming method, and a program according to embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0010] (First embodiment) FIG. 1 illustrates an example of a system configuration of an image forming apparatus according to the first embodiment.

[0011] The image forming apparatus 1 includes a printer unit 10, an inspection unit 20, and a stacker unit 40. These units are communicably connected via a communication line or a communication network.

[0012] The printer unit 10 receives print job data including user images from an external device such as a DFE (Digital Front End) device. The printer unit 10 then executes printing in response to an execution instruction from the received print job data or a user operation on an operation panel 117 or the like provided on the printer unit 10. The print job data includes job information indicating attributes such as the number of copies to be printed, the number of pages, whether double-sided or single-sided, and the type of paper, as well as image data.

[0013] The printer unit 10 has a configuration in which photosensitive drums 112Y, 112M, 112C, and 112K of the respective colors are arranged along a conveyor belt 111, which is an endless moving means.

[0014] Specifically, the printer unit 10 includes photosensitive drums 112Y, 112M, 112C, and 112K arranged in this order from the upstream side in the conveying direction of a conveyor belt 111. The conveyor belt 111 is an intermediate transfer belt on which an intermediate transfer image is formed to be transferred onto paper fed from a paper feed tray 113 along the conveyor belt 111. Here, the paper is an example of a medium on which a color image is formed.

[0015] The printer unit 10 forms a full-color image by transferring toner images of K (black), C (cyan), M (magenta), and Y (yellow) developed with toner on the surface of the photosensitive drum of each color onto the conveyor belt 111 in a superimposed manner. Here, these colors are examples of a first color and a second color, and the toner images of these colors are examples of a plurality of images superimposed on a medium to form a color image.

[0016] The printer unit 10 transfers the full-color image formed on the conveyor belt 111 onto the surface of the paper being conveyed along the path, using the function of the transfer roller 114, at the position closest to the paper conveying path shown by the dashed line in the figure.

[0017] Printer unit 10 further transports the paper on which the image has been formed, fixes the image with fixing roller 115, and then transports the paper to reading unit 131. Reading unit 131 reads the paper transported via fixing roller 115, generates read image data, and inputs it to inspection unit 20. The read image is, for example, an RGB format image with 8 bits per color and 200 dpi (1 pixel is approximately 0.127 mm wide). Reading unit 131 may acquire an image after toner has been fixed by fixing roller 115, or may acquire an image after transfer by transfer roller 114 and before entering fixing roller 115.

[0018] In the case of single-sided printing, the printer unit 10 directly discharges the paper read by the reading unit 131 to the stacker unit 40. In the case of double-sided printing, the printer unit 10 reverses the paper read by the reading unit 131 using the reversing path 116 and transports it again to the transfer position of the transfer roller 114.

[0019] Next, the printer unit 10 transfers and fixes a toner image onto the opposite side of the paper that has been printed on one side. The reader unit 131 then reads the printed side. The printer unit 10 then ejects the paper that has been printed on both sides to the stacker unit 40.

[0020] The stacker unit 40 stores the paper sheets discharged from the printer unit 10 in a stack on a tray 141 .

[0021] Inspection unit 20 inspects the read image read by reading unit 131 using a method described below, and detects misalignment (misalignment information) that occurs during printing. Operation panel 117 acquires information indicating the inspection result from inspection unit 20 and displays it.

[0022] FIG. 2 is a diagram showing an example of the hardware configuration of the printer unit 10. As shown in FIG.

[0023] The printer unit 10 includes a controller 1110 , a short-range communication circuit 1120 , an engine control unit 1130 , an operation panel 117 , and a network I / F 1150 .

[0024] Of these, the controller 1110 has a CPU (Central Processing Unit) 1101, which is the main part of the computer, a system memory (MEM-P) 1102, a north bridge (NB) 1103, a south bridge (SB) 1104, an ASIC (Application Specific Integrated Circuit) 1106, a local memory (MEM-C) 1107, which is a storage unit, an HDD (Hard Disk Drive) controller 1108, and an HD 1109, which is a storage unit. Note that an SSD (Solid State Drive) may be used as the storage unit.

[0025] The NB 1103 and the ASIC 1106 are connected by an AGP (Accelerated Graphics Port) bus 1121 .

[0026] Of these, the CPU 1101 is a control unit that performs overall control of the image forming apparatus 1 including the printer unit 10. The NB 1103 is a bridge that connects the CPU 1101 with the MEM-P 1102, the SB 1104, and the AGP bus 1121, and includes a memory controller that controls reading and writing to the MEM-P 1102, a PCI (Peripheral Component Interconnect) master, and an AGP target.

[0027] The MEM-P 1102 includes a ROM (Read Only Memory) 1102a, which is memory for storing programs and data that realize the functions of the controller 1110, and a RAM (Random Access Memory) 1102b, which is used for expanding the programs and data, and as a drawing memory during memory printing. The programs stored in the RAM 1102b may be provided by being recorded in an installable or executable file format on a computer-readable recording medium such as a CD-ROM, CD-R, or DVD.

[0028] The SB 1104 is a bridge for connecting the NB 1103 with PCI devices and peripheral devices. The ASIC 1106 is an integrated circuit (IC) for image processing purposes that has hardware elements for image processing, and serves as a bridge for connecting the AGP bus 1121, PCI bus 1122, HDD controller 1108, and MEM-C 1107.

[0029] The ASIC 1106 includes a PCI target and AGP master, an arbiter (ARB) that forms the core of the ASIC 1106, a memory controller that controls the MEM-C 1107, a plurality of DMACs (Direct Memory Access Controllers) that perform image data rotation and the like using hardware logic, and a PCI unit that transfers data between the scan processing unit 1131 and the print processing unit 1132 via a PCI bus 1122. The ASIC 1106 may be connected via an interface such as a USB (Universal Serial Bus) interface or IEEE 1394 (Institute of Electrical and Electronics Engineers 1394).

[0030] The MEM-C 1107 is a local memory used as an image buffer for copying and a code buffer. The HD 1109 is a storage for storing image data, font data used during printing, forms, etc. The HD 1109 controls the reading and writing of data from and to the HD 1109 under the control of the CPU 1101.

[0031] The AGP bus 1121 is a bus interface for a graphics accelerator card proposed to speed up graphics processing. The AGP bus 1121 can speed up the graphics accelerator card by directly accessing the MEM-P 1102 with high throughput.

[0032] The short-range communication circuit 1120 also includes a short-range communication antenna 1120a. The short-range communication circuit 1120 is a communication circuit such as NFC or Bluetooth (registered trademark).

[0033] Furthermore, the engine control unit 1130 is composed of a scan processing unit 1131 and a print processing unit 1132. The operation panel 117 includes a panel display unit 117a, such as a touch panel, that displays current setting values, selection screens, etc. and accepts inputs from an operator, and operation keys 117b, such as a numeric keypad that accepts setting values for image formation conditions such as density setting conditions, and a start key that accepts a copy start command. Here, the panel display unit 117a is an example of a display unit. The panel display unit 117a accepts touch inputs from the user, and the user can use a finger or a pen to enter numbers into input boxes displayed on the screen, select from pull-down menus, turn check boxes on / off, and so on. The operation keys 117b may include input means such as a trackball or a touchpad in addition to a numeric keypad, etc.

[0034] The controller 1110 controls the entire image forming apparatus including the printer unit 10, for example, drawing, communication, input from the operation panel 117, reading of print results by the reading unit 131, and inspection of read data by the inspection unit 20. The scan processing unit 1131 reads an image formed on a transport medium such as paper and generates image data. The print processing unit 1132 includes a transfer unit that transfers an image using color materials such as a toner image to the transport medium such as paper, a fixing unit that fixes the image, a heating unit or a drying unit, etc., and forms an image on paper. The scan processing unit 1131 or the print processing unit 1132 also performs image processing such as error diffusion and gamma conversion.

[0035] The paper is an example of a transport medium. The transport medium may be other than paper, such as a film or a plastic sheet, as long as it can be placed in a paper feed tray provided in the printer unit 10 and transported and output in response to a paper output instruction.

[0036] The network I / F 1150 is an interface for performing data communication using a communication network. The short-range communication circuit 1120 and the network I / F 1150 are electrically connected to the ASIC 1106 via a PCI bus 1122.

[0037] Although FIG. 2 shows an example in which the printer unit 10 has an electrophotographic image forming mechanism, the printer unit 10 may have another image forming mechanism such as an inkjet type.

[0038] 3 is a diagram showing an example of functional blocks of the printer unit 10. The printer unit 10 includes a system control unit 1001, a display control unit 1002, a network I / F control unit 1003, an external I / F control unit 1004, a storage unit 1005, a mechanism control unit 1006, a print job receiving unit 1007, an image processing control unit 1008, and a printing control unit 1009. Each of these units is realized by the CPU 1101 or the ASIC 1106 executing processing defined in a program stored in the MEM-P 1102 or the MEM-C 1107, etc.

[0039] The system control unit 1001 controls the entire printer unit 10. The system control unit 1001 includes a job information processing unit 1011, a RIP (Raster Image Processor) processing unit 1012, a job information generating unit 1013, and a chart generating unit 1014.

[0040] A job information processing unit 1011 processes job information included in print job data transmitted from a DFE device, etc. A RIP processing unit 1012 processes RIP image data included in print job data transmitted from a DFE device, etc. Note that the RIP image is, for example, an image in CMYK format with 8 bits per color and 600 dpi, and is an example of print data (image formation data).

[0041] When the job information generating unit 1013 receives information instructing the insertion of a sheet for inspection from the inspection unit 20, it generates job information for inserting the sheet.

[0042] The chart generation unit 1014 generates print data in which an inspection chart (described later) is arranged. Here, the chart generation unit 1014 is an example of an image arrangement unit, and the print data in which the inspection chart is arranged is an example of image formation data.

[0043] A display control unit 1002 controls the display of various information including job information on the operation panel 117. A network I / F control unit 1003 controls the network I / F 1150 and controls connection with a communication network. When another device is connected, an external I / F control unit 1004 controls connection with the connected other device. A storage unit 1005 stores various information including job information.

[0044] The mechanism control unit 1006 controls the operation of the mechanisms of the printer unit 10, such as the paper transport and transfer process of the printer unit 10, including the print processing unit 1132, etc. The print job receiving unit 1007 receives print job data from a DFE device, etc. The image processing control unit 1008 processes the print image to be transferred by the mechanism control unit 1006. The printing control unit 1009 controls the formation of an image on the transported medium. The mechanism control unit 1006, image processing control unit 1008, and printing control unit 1009 work together to function as an image forming unit that forms an image on the transported medium.

[0045] 4 is a diagram showing an example of the format of an inspection chart used in this embodiment. The inspection chart is printed (formed) by the image forming apparatus 1, read by the reading unit 131, and the read data is used for inspection by the inspection unit 20. In FIG. 4, the X axis represents the main scanning direction, and the Y axis represents the sub-scanning direction.

[0046] As shown in Figure 4, the inspection charts are formed in the areas indicated by dashed lines on the left and right sides of the paper (medium). The chart on the left side is defined by the paper edge distance (left), which is the distance from the edge of the paper, the paper edge distance (top), and the paper edge distance (bottom), as well as the size and pattern spacing of each image of the pattern, which will be described later. Similarly, the chart on the right side is defined by the paper edge distance (right), which is the distance from the edge of the paper, the paper edge distance (top), and the paper edge distance (bottom), as well as the size and pattern spacing of each image of the pattern, which will be described later.

[0047] In addition to the inspection chart, the paper is printed with a user image and cutting marks. The area on the paper excluding the user image is called the margin area. The position of the cutting marks is defined by the paper cutting distance (left), paper cutting distance (right), paper cutting distance (top), and paper cutting distance (bottom), as shown in Figure 4. The area outside the dot-dash line is removed by cutting, so the inspection chart is placed outside the dot-dash line.

[0048] 5A and 5B are diagrams showing examples of print data for an inspection chart to be placed on the left or right side of the paper. Fig. 5A shows an example of a conventional chart, in which a pattern of one color is arranged in the X-axis direction, and patterns of multiple different colors are repeatedly arranged at equal intervals in the Y-axis direction. Fig. 5B shows an example of a chart according to this embodiment, in which a pattern of multiple different colors is arranged in the X-axis direction at a Y-coordinate position of y1, and the same pattern is repeatedly arranged at equal intervals in the Y-axis direction.

[0049] The print data for the inspection chart described above is printed on paper, and the reading unit 131 reads it to generate read data. Fig. 6 is a diagram showing an example of read data for the inspection chart. Fig. 6(a) is read data corresponding to the chart in Fig. 5(a), and Fig. 6(b) is read data corresponding to the chart in Fig. 5(b).

[0050] In Fig. 6, the color C is shifted upward at the Y coordinate position of y3, the color M is shifted downward at the Y coordinate position of y5, and the color B is shifted upward and the color Y is shifted downward at the Y coordinate position of y8. When such misalignment occurs, the chart in Fig. 5(a) does not show any shift in the pattern spacing in the Y axis direction of the read data as in Fig. 6(a), but the chart in Fig. 5(b) shows a shift in the pattern spacing in the Y axis direction of the read data for the misaligned colors as in Fig. 6(b). In this embodiment, misalignment information is detected by inspecting the shift in the Y axis direction that has occurred in the read data.

[0051] 7A and 7B are diagrams showing the sizes and positions of patterns arranged in the print data of the inspection chart. In FIG. 7A, Kw, Cw, Mw, and Yw are the widths of the K, C, M, and Y images included in the pattern, respectively. Kh, Ch, Mh, and Yh are the heights of the K, C, M, and Y images included in the pattern, respectively. The images of each color are arranged so that their top edges are aligned in the Y-axis direction. Here, the images of each color are examples of the first and second images.

[0052] In Figure 7(b), WH is the width of the white area added to the top and bottom of each color image. The color of the white area has the same value for each RGB data, and is white when the data is at its maximum, black when the data is at its minimum, and gray when the data is in-between. The white area serves to facilitate detection of the coordinates of the top and bottom of the pattern image. In particular, it is preferable to provide a white area when the pattern is superimposed on a user image. Therefore, if detection of the bottom coordinate is not necessary, it is not necessary to add a white area to the bottom. Also, to facilitate detection of the coordinates of the right and left edges, white areas may be added to the right and left edges of the pattern. Note that the white area may be set inside the pattern.

[0053] The colors of the pattern may be spaced apart from one another or may overlap. Also, there may be cases where the colors overlap due to misalignment during printing. In such cases, the width of the non-overlapping portions will be smaller than the width of each image. Taking this into consideration, it is preferable to set the number of pixels in the non-overlapping portions of each image to n x t pixels or more when setting the number of pixels n required for coordinate detection. Here, t is a correction value that takes misalignment into account, and is, for example, a value greater than 1.

[0054] FIG. 8 is a diagram showing the positions on paper of patterns arranged in print data. The first pattern from the top of the chart on the left is arranged at coordinates (OFx, OFy) as shown in FIG. 8. The coordinates of the top left corner of the paper are (0,0). In FIG. 8, the offset in the main scanning direction (main scanning offset) from the left edge of the pattern of each image is 0 for the K image, Kw for the C image, Kw+Cw for the M image, and Kw+Cw+Mw for the Y image. Here, the main scanning position (OFx) of the K image is an example of a first main scanning position, and the main scanning positions (OFx+Kw, OFx+Kw+Cw, or OFx+Kw+Cw+Mw) of the C image, M image, or Y image are an example of a second main scanning position.

[0055] The second pattern from the top is positioned at coordinates (OFx, OFy+Py) that are Py apart in the sub-scanning direction from the first pattern. Here, the sub-scanning position (OFy) of the first pattern is an example of a first sub-scanning position, and the sub-scanning position (OFy+Py) of the second pattern is an example of a second sub-scanning position. Similarly, the third and subsequent patterns are periodically positioned at coordinates Py apart in the sub-scanning direction from the pattern immediately above, within a range that does not exceed the lower limit of the chart area shown in FIG. 4. Each pattern is positioned so that its right edge (the right edge including the white area, if a white area is provided at the right edge) is within the cutting area indicated by the cutting mark. Furthermore, when repeatedly positioning patterns, if a pattern overlaps a cutting mark, only the overlapping pattern may be shifted in the sub-scanning direction to avoid the cutting mark.

[0056] 9 is a diagram showing an example of the functional configuration of the chart generation unit 1014. As shown in FIG. 9, the chart generation unit 1014 has a position setting unit 1020, a size setting unit 1021, a border area setting unit 1022, and a cutting area setting unit 1023.

[0057] The position setting section 1020 is a section for setting the position of a pattern included in a chart and the position of an image of each color included in a pattern. The size setting section 1021 is a section for setting the size of an image of each color. The border area setting section 1022 is a section for setting the size and color of an outline area. Furthermore, the cutting area setting section 1023 is a section for setting information about the cutting area.

[0058] 10 is a diagram showing an example of a chart setting screen. The chart setting screen is displayed on the operation panel 117 and is a screen for accepting input from the user to set the size, position, etc. of each image of a pattern, and includes a chart image display area 410, a pattern setting area 500, a display setting area 600, and a paper setting area 700.

[0059] The chart image display area 410 is an area that displays an image of the chart that is generated according to the set values. The dashed line on the left side of the chart image display area 410 displays an image of the chart that is generated at the left edge of the paper, and the dashed line on the right side displays an image of the chart that is generated at the right edge of the paper.

[0060] 11 is a diagram showing an example of a screen displayed in the pattern setting area 500. The pattern setting area 500 has a color setting area 510, a size setting area 520, a main scanning offset setting area 530, a pattern spacing setting area 540, a paper edge distance setting area 550, and a white area setting area 560.

[0061] The color setting area 510 is an area for setting the color of the images to be included in the pattern. The user can set the color of each image using a pull-down menu with an inverted triangle mark or the like. In FIG. 11, the colors K, C, M, and Y are set in order from left to right in the pattern. The user can copy the color settings on the left side to the color settings on the right side by checking the check box labeled "Left and Right" on the left side of the color setting area 510. Furthermore, if the "Left and Right" check box is unchecked, the user can set the color of each image on the right side using the color setting pull-down menu on the right. If the "Left and Right" check box is checked, there is no need to operate the color settings on the right side, so the pull-down menu or the like may be grayed out to make it inoperable.

[0062] The size setting area 520 is an area where the user inputs the size of each image in the pattern. Based on this information and the spacing between each pattern in the sub-scanning direction (pattern spacing), the size setting unit 1021 sets the size of each image. The name of the color set in the color setting area 510 is displayed to the left of the input box. In FIG. 11, the color names K, C, M, and Y are displayed from top to bottom, and the user can input and set the size (height and width) of each color in the input box. By checking the checkbox labeled "All Colors," the user can reflect the size of one image in other images and set the same size. If the "All Colors" checkbox is unchecked, the size of each image can be set individually. If the "All Colors" checkbox is unchecked, no setting operations are required other than the size of one image. Therefore, the size setting input boxes for other colors may be grayed out to prevent operation. Also, as with the color setting area 510, if the "Left and Right" checkbox is unchecked, the size of the right side can be set separately from the left side. If the "Left and Right" checkbox is checked, there is no need to perform setting operations on the right side, so the input box may be grayed out to make it impossible to operate.

[0063] The main scanning offset setting area 530 is an area where the user inputs the offset in the main scanning direction (main scanning offset) of each image of the pattern, and the position setting unit 1020 sets the main scanning position of each image based on this information and the paper edge distance information described below. As with the color setting area 510, if the "left and right" checkbox is OFF, the main scanning offset for the right side can be set separately from the left side, and if the "left and right" checkbox is ON, the input box on the right side can be grayed out so that it cannot be operated.

[0064] The pattern spacing setting area 540 is an area where the user inputs the pattern spacing (Py in FIG. 8). As with the color setting area 510, if the "left and right" checkbox is OFF, the main scanning offset for the right side can be set separately from the left side, and if the "left and right" checkbox is ON, the input box for the right side may be grayed out to make it impossible to operate.

[0065] The paper edge distance setting area 550 is an area where the user inputs the distance from the paper edge of the area where the pattern is to be placed (paper edge distance). The user can set the values for "paper edge distance (left)," "paper edge distance (right)," "paper edge distance (top)," and "paper edge distance (bottom)" shown in FIG. 4 using the input boxes. If the "left and right" check box is OFF, the value on the right side can be set separately from the left side, and if the "left and right" check box is ON, the right input box may be grayed out to prevent operation. Furthermore, if the "top and bottom" check box is OFF, the value on the bottom side can be set separately from the top side, and if the "top and bottom" check box is ON, the lower input box may be grayed out to prevent operation.

[0066] The white area setting area 560 is an area where the user inputs the width (WH in FIG. 7(b) and FIG. 8) and color of the white area, and based on this information, the border area setting unit 1022 sets the position and color of the white area. If the "inside" checkbox is OFF, the white area is placed outside the pattern, and if the "inside" checkbox is ON, the white area is placed inside the pattern.

[0067] As mentioned above, the chart on the left requires that the right edge of each pattern (including the white area) be positioned inside the cutting area indicated by the cutting mark. If the settings in the pattern setting area 500 do not satisfy this condition, the display control unit 1002 prompts the user to correct the settings by displaying a warning screen, displaying the setting values in red, or the like. FIG. 12 is a diagram showing an example of a screen displayed in the paper setting area 700. The paper setting area 700 has a paper cutting position setting area 720.

[0068] The paper cutting position setting area 720 is an area where the user inputs the paper cutting position, and based on this information, the cutting area setting unit 1023 sets the placement position of the cutting marks. In addition, the "Left and Right" and "Top and Bottom" check boxes have the same functions as the paper edge distance setting area 550.

[0069] In the above description, an example has been given in which the user sets the numerical values etc. of each area in the pattern setting area 500 and the paper setting area 700, but some of these numerical values etc. may be set in advance. For example, the preset values may be 30.2 mm and 10 mm for the top and bottom and left and right distances to the paper edge, respectively, the pattern spacing may be 10 mm, the paper cutting position may be 25.5 mm for both the left and right, the width of the white area may be 0.8 mm, and the pixel value may be 255.

[0070] 13 is a diagram showing an example of the functional configuration of the inspection unit 20. The inspection unit 20 includes a system control unit 2001, a display control unit 2002, a network I / F control unit 2003, an external I / F control unit 2004, a storage unit 2005, a mechanism control unit 2006, and a reading unit 2007. Each of these units is realized by the CPU 1101 or the ASIC 1106 executing processing defined in a program stored in the MEM-P 1102 or the MEM-C 1107, etc.

[0071] The system control unit 2001 controls the entire inspection unit 20. It extracts information to be processed by a post-processing device (for example, a device that performs post-processing, such as the stacker 40) from the job information and transmits it to the post-processing device via the external I / F control unit 2004. The system control unit 2001 also transfers the job information, excluding the information to be processed by the post-processing device, to the reading unit 2007 and the mechanism control unit 2006.

[0072] The system control unit 2001 also includes a paper information storage unit 2011 , a coordinate detection unit 2012 , a positional deviation information calculation unit 2013 , a threshold value setting unit 2014 , and a positional deviation determination unit 2015 .

[0073] The paper information storage unit 2011 stores paper information. The paper information is information indicating attributes such as the size of the paper, and includes, for example, coordinate values indicating the edges of the paper obtained from the print job data.

[0074] The coordinate detection unit 2012 detects the coordinates of the top edge of the image for each color from the scanned data of the inspection chart input from the scanning unit 2007 using pattern matching or the like.

[0075] The positional deviation information calculation unit 2013 calculates positional deviation information for the image of each color based on the coordinates detected by the coordinate detection unit 2012 .

[0076] The threshold value setting unit 2014 sets a threshold value based on a numerical value input into a threshold value setting area 620 of the display setting area 600, which will be described later.

[0077] The positional deviation determination unit 2015 determines the positional deviation based on the positional deviation information and a threshold value, and outputs the determination result to the display control unit 2002 .

[0078] Fig. 14 is a diagram showing an example of a pattern of scanned data. As shown in Fig. 14, when the C, M, and Y images are printed shifted in the sub-scanning direction relative to the K image due to misalignment during printing, the amounts of misalignment of the C, M, and Y images are Cd, Md, and Yd based on the coordinates of the images of each color. The threshold values for determining misalignment for these amounts of misalignment are set to Ct, Mt, and Yt, respectively.

[0079] 15 is a diagram showing an example of a screen displayed in the display setting area 600. The display setting area 600 has a reference color setting area 610 and a threshold value setting area 620.

[0080] The reference color setting area 610 is an area where the user inputs a reference color for calculating the difference included in the misalignment information, and the misalignment information calculation unit 2013 calculates the misalignment information using this information. In Fig. 15, the reference color is set to K, and in this case, the coordinates of the K image in Fig. 14 are used as a reference, and the differences between the coordinates of each of the C, M, and Y images are calculated as misalignment information. The reference color may be set to any of C, M, and Y other than K.

[0081] The threshold setting area 620 is an area where the user inputs a threshold value for each color image. FIG. 15(a) is an example of a screen in which the same threshold value is set for the left and right charts for the misalignment of each color image, and FIG. 15(b) is an example of a screen in which different threshold values can be set for the left and right charts. If the "Left and Right" checkbox in FIG. 15(b) is checked, the same threshold value is set for the left and right charts, as in FIG. 15(a). If the values are set as in FIG. 15, the threshold values Ct, Mt, and Yt in FIG. 14 are all set to 0.25 mm. Note that because positional deviation information relative to the reference color is not calculated, the threshold value corresponding to the reference color (K in FIG. 15) is displayed as "-" or the like in the threshold setting area 620.

[0082] In the above example, the user sets the values of each area in the display setting area 600, but some of these values may be preset. For example, the preset values may be K for the reference color and 0.25 mm for the threshold value.

[0083] The display control unit 2002 controls the display of various information including the test results on the operation panel 117 or other devices. The other devices include terminal devices such as personal computers and tablets used by users, DFE devices, etc. The display control unit 2002 may receive a request from software such as a web browser of the other devices and perform processing to return information stored in the test unit 20, etc.

[0084] Furthermore, the display control unit 2002 and the software of the other device may use a two-way communication protocol such as WebSocket to transmit information from the inspection unit 20 to the other device and display it in real time. For example, if the software of the other device accesses the inspection unit 20 and displays a list of misaligned printed sheets, the list is automatically updated each time a misalignment occurs, and additional information about the misaligned printed sheets or paper is displayed.

[0085] The display control unit 2002 may be included as a web server in the inspection unit 20 or the like, or may be included on a cloud server that receives information on the inspection results from the inspection unit 20.

[0086] A network I / F control unit 2003 controls a network with external devices. An external I / F control unit 2004 controls an interface with external devices such as an I / F 205.

[0087] The memory unit 2005 stores various types of information. Specifically, it stores job execution history information for jobs for which control has been completed, read image data, inspection result information, etc. The mechanism control unit 2006 controls the operation of the mechanism of the inspection unit 20. The reading unit 2007 acquires read image data (read data of paper on which an inspection chart is printed) from the reading unit 131. Note that the reading unit 2007 may also have a function for reading images.

[0088] 16 is a flowchart showing the procedure for misalignment determination processing according to this embodiment. First, the chart generation unit 1014 generates an inspection chart, the reading unit 131 reads data printed on the inspection chart, and the reading unit 2007 acquires the read image data (step S10).

[0089] The coordinate detection unit 2012 detects the coordinates of each color from the read data for the first pattern on the inspection chart (step S11). Next, the positional deviation information calculation unit 2013 calculates positional deviation information for the image of each color based on the coordinates detected by the coordinate detection unit 2012 (step S12).

[0090] The misalignment determination unit 2015 compares the amount of misalignment found from the misalignment information calculated by the misalignment information calculation unit 2013 with the threshold value set by the threshold value setting unit 2014 (step S13). Here, the amount of misalignment is the absolute value of the difference between the images of each color included in the misalignment information (the difference between the coordinates of the image of the reference color and the coordinates of the image of a color other than the reference color).

[0091] If the amount of misalignment of at least one image included in one pattern is greater than the threshold value (step S13: Yes), the misalignment determination unit 2015 adds the misalignment information to the display data showing the inspection result (step S14). Note that if the amounts of misalignment of all images included in one pattern are equal to or less than the threshold value (step S13: No), the misalignment information of that pattern is not added to the display data.

[0092] If the processing of all patterns has not been completed, the system control unit 2001 detects the coordinates of the next pattern from the read data and returns the process to step S12 (steps S15 and S16). The system control unit 2001 repeats the processes of steps S12 to S16, and ends the detection process when the processing of all patterns has been completed.

[0093] 17 is a diagram showing an example of the detection results generated by the above-described detection process. The detection results displayed on the operation panel 117 have a read data area 810 and a detection result area 820. In the read data area 810, the left and right inspection charts and the number of the pattern determined to have a positional deviation greater than the threshold (detection No.) are displayed in a detected pattern area 811. Note that the read data area 810 may display a cutting mark or a user image as in FIG. 17, but it may also display only the left and right inspection charts and the detected pattern area 811.

[0094] The detection result area 820 displays the reference color used in the inspection, the threshold value, and a table of the detection results. The detection result table displays the detection number, the coordinates of the upper left corner of the pattern, and positional deviation information for the image of each color. In this example, the calculated difference is displayed as positional deviation information regardless of the threshold value, but differences that exceed the threshold value may be displayed in red or other noticeable way.

[0095] The misalignment information may display only the difference exceeding the threshold value, or the coordinates of the sub-scanning position may be used instead of the difference. Fig. 18 shows an example of another method of displaying a table of detection results. Fig. 18(a) is an example in which only the difference exceeding the threshold value is displayed, and only information exceeding the threshold value of 0.25 mm is displayed. Figs. 18(b) and 18(c) are examples in which coordinates are obtained as misalignment information instead of differences. Fig. 18(b) displays misalignment information regardless of the threshold value, while Fig. 18(c) displays coordinates as misalignment information only when the difference exceeds the threshold value.

[0096] In this embodiment, multiple pages of inspection charts can be printed and read to determine statistical values of misalignment information for each pattern. FIG. 19 is a flowchart showing the procedure for determining statistical values of misalignment information through detection processing according to this embodiment. This differs from FIG. 16 in that step S24, which updates the number of misalignments, is used instead of step S14, and steps S26 and S28 are added for processing multiple pages. Other aspects are similar to FIG. 16, and therefore will not be described further.

[0097] If the amount of misalignment of at least one image included in one pattern is greater than the threshold value, the misalignment determination unit 2015 updates the number of misalignments (misalignment count) for the corresponding image of that pattern (step S24). Note that the initial value of the misalignment count is set to 0 for each image of each pattern, and is updated so that it increases by 1 each time a misalignment amount greater than the threshold value is detected.

[0098] When processing one page is completed, the system control unit 2001 checks whether processing of all pages is completed (step S26), and if not, reads the data of the next page and returns the process to step S20 (step S28). The system control unit 2001 repeats the processes of steps S20 to S28, and ends the detection process when processing of all pages is completed.

[0099] 20 is a diagram showing an example of statistical values of positional deviation information for each pattern generated in the above detection process. The detection results displayed on operation panel 117 have a read data area 910 and a detection result area 920. The read data area 910 displays the left and right inspection charts and the number of each pattern (pattern No.). Note that the read data area 910 may also display cutting marks and a user image.

[0100] The detection result area 920 displays the reference color used in the inspection, the threshold value, the number of pages inspected, and a table of the detection results. The detection result table displays the pattern number, the coordinates of the upper left corner of the pattern, and the number of image misalignments for each color. The user may be able to switch between the number of misalignments as shown in FIG. 20 and the misalignment information for a specific page as shown in FIG. 17. In this case, the page number of the inspection chart is displayed in the detection result area 820 in FIG. 17. Alternatively, an upper limit for the number of misalignments may be set in advance. If the number of misalignments exceeds the upper limit, the system control unit 2001 may notify the user that maintenance is required for the color for which the number of misalignments exceeds the upper limit. If the image forming apparatus 1 has a mechanism for automatically performing maintenance, maintenance of the color for which the number of misalignments exceeds the upper limit may be performed automatically. For example, when performing maintenance on the misalignment of M in detection No. 1 in FIG. 17, the printing position of M is adjusted to be 0.28 mm in the positive direction. Furthermore, if all the other colors are misaligned in the same direction relative to the reference color, the print positions of the colors may be adjusted in the direction opposite to the misalignment, or only the reference color may be adjusted in the direction of the misalignment.

[0101] As described above, according to this embodiment, misregistration information can be detected using a pattern in which an image of a reference color and an image of a non-reference color are arranged at the same sub-scanning position in the main scanning direction, making it possible to detect color misregistration due to local variations in the sub-scanning direction. Furthermore, the chart setting screen can be used to set the reference color, the size and position of the images included in the pattern, the pattern spacing, etc., making it possible to use a desired inspection chart to match the paper. Furthermore, since the edge area of the pattern can be set, the coordinates of each image in the pattern can be easily detected even when the pattern is superimposed on a user image.

[0102] (Second embodiment) Fig. 21 is a diagram showing an example of print data and read data of the above-mentioned inspection chart pattern. As shown on the right side of Fig. 21, due to printing misalignment of each color, the read data has a positional deviation in the sub-scanning direction compared to the print data. In this embodiment, the positional deviation of the images of each color is detected by comparing the coordinates of the sub-scanning position of the print data with the coordinates of the sub-scanning position of the read data.

[0103] 22 is a diagram showing an example of the functional configuration of the inspection unit 20 according to the second embodiment. The difference from the first embodiment is that the inspection unit 20 includes a chart data input unit 2008, and a system control unit 2001 calculates misalignment information and determines misalignment using the coordinates of the print data and the coordinates of each image in the read data input from the reading unit 2007, and generates display data. The other operations are the same as those in the first embodiment, so a description thereof will be omitted.

[0104] The chart data input unit 2008 inputs the setting data for the inspection chart. The coordinate detection unit 2012 calculates the coordinates of the pattern in the print data from the input setting data for the inspection chart, and detects the coordinates of the top edge of the image for each color from the read data using pattern matching or the like.

[0105] A positional deviation information calculation unit 2013 calculates positional deviation information for the image of each color based on the coordinates detected by the coordinate detection unit 2012. A threshold setting unit 2014 sets a threshold for determining the amount of deviation for each color.

[0106] Since the misalignment information in this embodiment indicates the amount of misalignment relative to the print data, no reference color is set, and misalignment information is calculated for each color. Fig. 23 is a diagram showing an example of the coordinates of the pattern in the print data and the coordinates of each image in the read data. As shown in Fig. 23, if the K, C, M, and Y images are printed shifted in the sub-scanning direction relative to the print data pattern due to misalignment during printing, the amounts of misalignment of the B, C, M, and Y images are calculated from the coordinates of the read images of each color as Bd, Cd, Md, and Yd. Furthermore, thresholds for determining misalignment relative to these amounts of misalignment are set to Bt, Ct, Mt, and Yt, respectively.

[0107] The positional deviation determination unit 2015 determines the positional deviation based on the positional deviation information and a threshold value, and outputs the determination result to the display control unit 2002 .

[0108] 24 is a diagram showing an example of a display setting area 600 according to this embodiment. As described above, no reference color is set, so the display setting area 600 includes only a threshold setting area 620. The other configurations are the same as those described in FIG. 15.

[0109] 25 is a diagram showing an example of the detection results generated by the above-described detection process. The detection results displayed on the operation panel 117 have a read data area 860 and a detection result area 870. In the read data area 860, the pattern numbers of the left and right inspection charts are displayed in a pattern number area 861. As with the read data area 810 in FIG. 17, the read data area 860 may also display cutting marks and user images, or may display only the number (detection number) of a pattern determined to have a positional deviation greater than the threshold value.

[0110] The detection result area 870 displays the threshold value, page information, and a table of detection results. For example, when printing and scanning multiple pages of inspection charts to obtain statistical values for misalignment information for each pattern, the page information indicates which page of the inspection chart the result is from. The detection result table displays the pattern number, the upper left coordinate of the pattern in the print data, and misalignment information for each color image. In this example, regardless of the threshold value, the calculated difference is displayed as misalignment information, but differences that exceed the threshold value may be displayed in red or other visible way.

[0111] As in the first embodiment, the misalignment information may display only the difference exceeding the threshold value, or may use the coordinates of the sub-scanning position of each image in the read data instead of the difference. Fig. 26 shows an example of another display method for the detection result table. Fig. 26(a) shows an example in which only the difference exceeding the threshold value is displayed, and only information exceeding the threshold value of 0.25 mm is displayed. Figs. 26(b) and 26(c) show examples in which coordinates in the read image are obtained as misalignment information instead of differences. Fig. 26(b) displays misalignment information regardless of the threshold value, while Fig. 26(c) displays coordinates as misalignment information only when the difference exceeds the threshold value.

[0112] As described above, according to this embodiment, misregistration information can be detected using the coordinates of the pattern in the print data and the coordinates in the read data, making it possible to detect color misregistration due to local variations in the sub-scanning direction. Also, since the coordinates of the pattern in the print data can be used as a reference, misregistration information can be detected for images of all colors in the read data.

[0113] Although various embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. For example, the function of the chart generating unit 1014 may be provided in the inspection unit 20 instead of the printer unit 10. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These novel embodiments and modifications thereof are within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as set forth in the claims. Furthermore, components from different embodiments and modifications may be combined as appropriate.

[0114] Furthermore, each function of the above-described embodiments can be realized by one or more processing circuits. Here, the term "processing circuit" in this specification includes a processor programmed to execute each function by software, such as a processor implemented by an electronic circuit, as well as devices such as an ASIC, a DSP (Digital Signal Processor), an FPGA (Field Programmable Gate Array), and conventional circuit modules designed to execute each of the above-described functions.

[0115] For example, aspects of the present invention are as follows. <1> An image forming device that forms a color image by superimposing multiple images on a medium, comprising: an image arrangement unit that arranges a pattern including a first image formed of an image having a first color and a second image formed of an image having a second color different from the first color in image formation data; a reading unit that reads the image formed on the medium using the image formation data; and a detection unit that detects positional deviation information of at least one of the image having the first color and the image having the second color based on the image read by the reading unit, wherein the image arrangement unit arranges the first image at a first main scanning position and a first sub-scanning position, and arranges the second image at a second main scanning position different from the first main scanning position and the first sub-scanning position. <2> a position setting unit that sets positions of at least the first image and the second image that are arranged by the image arrangement unit, wherein the position setting unit sets the first sub-scanning position and also sets an interval at which the pattern is repeated in the sub-scanning direction; <1> 2. The image forming apparatus according to claim 1, wherein: <3> a position setting unit that sets positions of at least the first image and the second image that are arranged by the image arrangement unit, and the position setting unit sets the first main scanning position; <1> or <2> 2. The image forming apparatus according to claim 1, wherein: <4> The image processing device further includes a size setting unit that sets sizes of at least the first image and the second image to be arranged by the image arrangement unit, and the size setting unit sets a height and width of the first image and a height and width of the second image. <1> ~ <3> 10. The image forming apparatus according to claim 9, wherein the first and second electrodes are arranged parallel to each other. <5> The image forming method further includes a border area setting unit that sets information about a border area formed in a color different from the first color and the second color, wherein the border area setting unit sets a size and a color of the border area, and the image placement unit places the first image and the second image having border areas of the size and color set by the border area setting unit in the image formation data. <1> ~ <4> 10. The image forming apparatus according to claim 9, wherein the first and second electrodes are arranged parallel to each other. <6> The image placement unit further includes a cutting area setting unit that sets information about a cutting area of the medium, the cutting area setting unit sets a position of the cutting area, and the image placement unit places the first image and the second image within the cutting area based on the position of the cutting area. <1> ~ <5> 10. The image forming apparatus according to claim 9, wherein the first and second electrodes are arranged parallel to each other. <7> The detection unit detects coordinates of a sub-scanning position of the first image read by the reading unit. and determining, as positional deviation information of the second image, the coordinates of the sub-scanning position of the second image, a first difference which is a difference between the sub-scanning position of the first image and the sub-scanning position of the second image, or a second difference which is a difference between the sub-scanning position arranged by the image arrangement unit and the sub-scanning position read by the reading unit. <1> ~ <6> 10. The image forming apparatus according to claim 9, wherein the first and second electrodes are arranged parallel to each other. <8> The method further includes a display unit that displays the positional deviation information. <1> ~ <7> 10. The image forming apparatus according to claim 9, wherein the first and second electrodes are arranged parallel to each other. <9> a display unit that displays the positional deviation information, the display unit displaying the positional deviation information when an absolute value of the first difference or the second difference exceeds a threshold value; <1> ~ <7> 10. The image forming apparatus according to claim 9, wherein the first and second electrodes are arranged parallel to each other. <10> The method further includes a threshold value setting unit that sets the threshold value. <9> 2. The image forming apparatus according to claim 1, wherein: <11> the image forming apparatus executes a detection operation to detect the positional deviation information a plurality of times; the display unit displays the number of detection operations in which the absolute value of the first difference or the second difference exceeds the threshold value for the second image; <9> or <10> 2. The image forming apparatus according to claim 1, wherein: <12> An image forming method for forming a color image by superimposing multiple images on a medium, the image forming method comprising: an image arranging step for arranging a pattern including a first image formed of an image having a first color and a second image formed of an image having a second color different from the first color in image formation data; a reading step for reading the image formed on the medium using the image formation data; and a detection step for detecting positional deviation information of at least one of the image having the first color and the image having the second color based on the image read by the reading means, wherein the image arranging step arranges the first image at a first main scanning position and a first sub-scanning position, and arranges the second image at a second main scanning position different from the first main scanning position and the first sub-scanning position. <13> This program causes a computer to function as an image arrangement means for arranging a pattern in image formation data, the pattern including a first image formed of an image having a first color and a second image formed of an image having a second color different from the first color, in an image formation process in which a color image is formed by superimposing multiple images on a medium; a reading means for reading the image formed on the medium using the image formation data; and a detection means for detecting positional deviation information of at least one of the image having the first color and the image having the second color based on the image read by the reading means, wherein the image arrangement means arranges the first image at a first main scanning position and a first sub-scanning position, and arranges the second image at a second main scanning position different from the first main scanning position and the first sub-scanning position. [Explanation of symbols]

[0116] 1. Image forming device 10 Printer section 20 Inspection Department 1014 Chart Generation Unit 1020 Position setting section 1021 Size setting section 1022 border area setting section 1023 Cutting area setting section 2001 System Control Unit 2007 Reading Unit 2008 Chart Data Input Department 2012 Coordinate detection unit 2013 Position deviation information calculation section 2014 Threshold setting section 2015 Position deviation detection unit [Prior art documents] [Patent documents]

[0117] [Patent Document 1] Japanese Patent Publication No. 2023-040333

Claims

1. An image forming apparatus for forming a color image by superimposing a plurality of images on a medium, an image arrangement unit that arranges, in image formation data, a pattern including a first image formed of an image having a first color and a second image formed of an image having a second color different from the first color; a reading unit that reads the image formed on the medium using the image formation data; a detection unit that detects positional deviation information of at least one of the image having the first color and the image having the second color based on the image read by the reading unit; Equipped with The image placement unit disposing the first image at a first main scanning position and a first sub-scanning position; an image forming apparatus that positions the second image at a second main scanning position different from the first main scanning position and at the first sub-scanning position;

2. a position setting unit that sets positions of at least the first image and the second image to be arranged by the image arrangement unit, 2. The image forming apparatus according to claim 1, wherein the position setting unit sets the first sub-scanning position and also sets an interval at which the pattern is repeated in the sub-scanning direction.

3. a position setting unit that sets positions of at least the first image and the second image to be arranged by the image arrangement unit, The image forming apparatus according to claim 1 , wherein the position setting unit sets the first main scanning position.

4. a size setting unit that sets sizes of at least the first image and the second image to be arranged by the image arrangement unit, The image forming apparatus according to claim 1 , wherein the size setting unit sets the height and width of the first image and the height and width of the second image.

5. a border area setting unit that sets information about a border area formed in a color different from the first color and the second color; the border region setting unit sets a size and a color of the border region; The image forming apparatus according to claim 1 , wherein the image arrangement section arranges the first image and the second image, each having a border area of a size and color set by the border area setting section, in the image formation data.

6. a cutting area setting unit that sets information about a cutting area of the medium; the cutting area setting unit sets the position of the cutting area, The image forming apparatus according to claim 1 , wherein the image placement section places the first image and the second image within the cutting area based on the position of the cutting area.

7. The detection unit coordinates of a sub-scanning position of the first image read by the reading unit; and determining the coordinates of the sub-scanning position of the second image read by the reading unit; obtain, as positional deviation information of the second image, coordinates of a sub-scanning position of the second image, a first difference which is a difference between the sub-scanning position of the first image and the sub-scanning position of the second image, or a second difference which is a difference between the sub-scanning position arranged by the image arrangement unit and the sub-scanning position read by the reading unit; The image forming apparatus according to claim 1 .

8. The image forming apparatus according to claim 1 , further comprising a display unit that displays the misregistration information.

9. a display unit that displays the positional deviation information, The image forming apparatus according to claim 7 , wherein the display unit displays the positional deviation information when an absolute value of the first difference or the second difference exceeds a threshold value.

10. The image forming apparatus according to claim 9 , further comprising a threshold value setting unit that sets the threshold value.

11. the image forming apparatus executes a detection operation to detect the positional deviation information a plurality of times; The image forming apparatus according to claim 9 , wherein the display unit displays the number of detection operations in which the absolute value of the first difference or the second difference exceeds the threshold value for the second image.

12. An image forming method for forming a color image by superimposing a plurality of images on a medium, comprising: an image arranging step of arranging a pattern including a first image formed of an image having a first color and a second image formed of an image having a second color different from the first color in image forming data; a reading step of reading an image formed on the medium using the image formation data; a detecting step of detecting positional deviation information of at least one of the image having the first color and the image having the second color based on the image read in the reading step; Equipped with The image arrangement step includes: disposing the first image at a first main scanning position and a first sub-scanning position; the second image is disposed at a second main scanning position different from the first main scanning position and at the first sub-scanning position.

13. Computer, In an image forming process in which a plurality of images are superimposed on a medium to form a color image, an image arrangement means for arranging a pattern including a first image formed of an image having a first color and a second image formed of an image having a second color different from the first color, in image formation data; a reading means for reading an image formed on the medium using the image formation data; a detecting means for detecting positional deviation information of at least one of the image having the first color and the image having the second color based on the image read by the reading means; It functions as The image placement means disposing the first image at a first main scanning position and a first sub-scanning position; a program for placing the second image at a second main scanning position different from the first main scanning position and at the first sub-scanning position;

Images