Image formation device, color chart formation method and color chart formation program

Abstract

To avoid influence of an abnormal image, even if there is an abnormal image among formed images.SOLUTION: An image formation device comprises an image formation part that forms, on a recording medium, a color image including a color chart constituted of colors generated using a plurality of standard colors, and a detection part that detects an abnormal image by reading out the color chart formed on the recording medium by the image formation part. When the detection part detects the abnormal image, the image formation part switches a color in an area in which the abnormal image is detected with a color not using the standard colors causing the abnormal image and forms a color chart again.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] In image forming apparatuses, calibration and profile creation are performed to adjust image formation conditions. When performing calibration and profile creation, the image forming apparatus prints a color chart and measures the colors using a colorimeter built into the apparatus or an external colorimeter. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-177041 A Summary of the Invention [Problem to be solved by the invention]

[0004] When an image abnormality such as a streak occurs on a patch image that constitutes a printed color chart, the color measurement accuracy of that part decreases, and as a result, accurate calibration and profile creation cannot be performed. Furthermore, printing work cannot be continued until the cause of the image abnormality is resolved.

[0005] Patent Document 1 shows that when an abnormality occurs in an image read from a color chart or the like, such as black streaks caused by dust or dirt, the image forming conditions are adjusted, excluding the data at the position corresponding to the pixel where the abnormality was detected.

[0006] In the technology disclosed in Patent Document 1, the image forming conditions can be adjusted by the above-mentioned method, but this adjustment is made under the influence of image abnormalities, and the influence increases as the range of black streaks, for example, becomes wider. Therefore, even if the formed image has image abnormalities, it is desired to print a color chart or a desired image by avoiding the influence of the image abnormalities.

[0007] An object of the present invention is to provide an image forming apparatus, a color chart forming method, and a color chart forming program that are capable of avoiding the influence of image abnormalities even if the image to be formed contains image abnormalities. [Means for solving the problem]

[0008] The image forming apparatus according to the present invention comprises: an image forming unit that forms a color image including a color chart on a recording medium, the color image being made up of colors generated using a plurality of standard colors; a detection unit that detects an image abnormality by reading the color chart formed on the recording medium by the image forming unit; Equipped with When the image abnormality is detected by the detection unit, the image forming unit replaces the color of the area where the image abnormality is detected with a color that does not use the standard color that is the cause of the image abnormality, and reforms the color chart.

[0009] The method for forming a color chart according to the present invention comprises the steps of: forming a color chart on a recording medium, the color chart being composed of colors generated using a plurality of standard colors; The formed color chart is read to detect image abnormalities, When the image abnormality is detected, the color of the area where the image abnormality is detected is replaced with a color that does not use the standard color and that is the cause of the image abnormality, and the color chart is regenerated.

[0010] The color chart forming program according to the present invention comprises: On the computer, A process of forming a color chart on a recording medium, the color chart being composed of colors generated using a plurality of standard colors; A process of reading the formed color chart and detecting image abnormalities; When the image abnormality is detected, a process of replacing the color of the area where the image abnormality is detected with a color that does not use the standard color and is the cause of the image abnormality, and regenerating the color chart; Execute the command. Effect of the Invention

[0011] According to the present invention, even if an image abnormality exists in a formed image, the influence of the image abnormality can be avoided. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram illustrating an example of an overall configuration of an image forming apparatus according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a block diagram showing an example of a main part of a control system of the image forming apparatus shown in FIG. [Diagram 3] FIG. 3 is a flowchart illustrating an example of a method for forming a color chart in the image forming apparatus shown in FIG. [Figure 4] FIG. 4 is a diagram for explaining an example of changing the layout of a color chart, showing the color chart before the change. [Diagram 5] FIG. 5 is a diagram for explaining an example of changing the layout of a color chart, showing the color chart after the change. [Figure 6] FIG. 6 is a diagram for explaining another example of changing the arrangement of a color chart, showing the color chart before the change. [Figure 7] FIG. 7 is a diagram for explaining another example of changing the arrangement of the color chart, showing the color chart after the change. [Figure 8] FIG. 8 is a diagram for explaining another example of changing the arrangement of the color chart, showing the color chart after being changed again. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0014] [Image forming device] Fig. 1 is a diagram illustrating an example of an overall configuration of an image forming apparatus 1 according to the present embodiment, and Fig. 2 is a block diagram illustrating an example of a main part of a control system of the image forming apparatus 1.

[0015] The image forming apparatus 1 is an apparatus for forming an image on paper such as a sheet of paper (a recording medium in the present invention). As shown in Fig. 1, the image forming apparatus 1 includes an image forming apparatus main body 100, a paper feed section 200, an inspection section 300 (a detection section in the present invention), a paper discharge section 400, etc.

[0016] The image forming apparatus main body 100 is, for example, a color image forming apparatus of an intermediate transfer type that utilizes electrophotographic process technology. The image forming apparatus main body 100 performs printing by primarily transferring the toner images of each color of CMYK formed on a photoconductor onto an intermediate transfer body, superimposing the four color toner images on the intermediate transfer body, and then secondary transferring the images onto paper. Note that CMYK stands for C (cyan), M (magenta), Y (yellow), and K (black).

[0017] The image forming apparatus main body 100 employs a tandem system in which, for example, photoconductors corresponding to the four colors, CMYK, are arranged in series in the running direction of an intermediate transfer body, and toner images of each color are transferred sequentially to the intermediate transfer body in a single step.

[0018] As shown in FIG. 2, the image forming apparatus 1 includes an image processing unit 10, an image forming unit 20, a fixing unit 30, a paper transport unit 40, an operation display unit 50, a control unit 60, a communication unit 71, a memory unit 72, a paper feed unit 200, an inspection unit 300, a paper discharge unit 400, etc.

[0019] The control unit 60 includes a CPU (Central Processing Unit) 61, a ROM (Read Only Memory) 62, and a RAM (Random Access Memory) 63. The CPU 61 reads out a program corresponding to the processing contents from the ROM 62, loads it in the RAM 63, and centrally controls the operation of each block of the image forming apparatus 1 in cooperation with the loaded program. At this time, various data such as a LUT (Look Up Table) stored in the storage unit 72 is referenced.

[0020] The storage unit 72 may be, for example, a hard disk drive (HDD) or a solid state drive (SSD), and may also be used in combination with a dynamic random access memory (DRAM).

[0021] The control unit 60 transmits and receives various data to and from an external device (e.g., a personal computer) connected to a communication network such as a LAN (Local Area Network) or a WAN (Wide Area Network) via the communication unit 71. The control unit 60 receives, for example, image data transmitted from an external device, and prints on paper based on this image data (input image data). The communication unit 71 is, for example, configured from a communication control card such as a LAN card.

[0022] The image processing unit 10, the image forming unit 20, the fixing unit 30, the paper transport unit 40, the operation display unit 50, the communication unit 71, the memory unit 72, the paper feed unit 200, the inspection unit 300, the paper discharge unit 400, etc. are connected to the control unit 60. These units execute predetermined processes based on instructions from the control unit 60.

[0023] The image processing unit 10 includes a circuit for performing image processing on input image data according to initial settings or user settings, etc. The image forming unit 20 is controlled based on the image data that has been subjected to the image processing.

[0024] The image forming section 20 includes an image forming unit 21, an intermediate transfer unit 22, a secondary transfer unit 23, etc. The image forming unit 21 performs printing using color toners of each color component based on image data from the image processing section 10. In other words, the image forming section 20 forms a color image including a color chart on paper, the color image being made up of colors generated using a plurality of standard colors, CMYK.

[0025] The image forming unit 21 has, for each color, an exposure device, a developing device, a photosensitive drum, a charging device, a drum cleaning device, etc. Since known technologies can be adopted for the exposure device, the developing device, the photosensitive drum, the charging device, and the drum cleaning device, detailed description thereof will be omitted here.

[0026] The intermediate transfer unit 22 includes an intermediate transfer belt and the like. The intermediate transfer belt is stretched in a loop shape around a number of support rollers and travels in the direction of arrow A. The support rollers include a backup roller, a primary transfer roller, a drive roller, and other rollers, but these are not shown here. The intermediate transfer belt is pressed against a photosensitive drum, thereby transferring a toner image from the photosensitive drum to the intermediate transfer belt.

[0027] The intermediate transfer unit 22 may be configured to include a belt cleaning device having a plate-shaped belt cleaning blade or the like that is in sliding contact with the surface of the intermediate transfer belt. The belt cleaning device removes residual toner and the like that remains on the surface of the intermediate transfer belt after the secondary transfer.

[0028] The secondary transfer unit 23 includes a secondary transfer roller, etc. The secondary transfer roller is in pressure contact with the intermediate transfer belt, so that a secondary transfer nip is formed between the intermediate transfer belt and the secondary transfer roller.

[0029] In the secondary transfer unit 23, when the paper is transported to the secondary transfer nip, the toner images of each color carried on the intermediate transfer belt are transferred onto the paper at once. The paper onto which the toner images have been transferred is transported toward the fixing unit 30 by the secondary transfer roller.

[0030] Incidentally, the secondary transfer unit 23 may be a belt-type secondary transfer unit having a secondary transfer belt stretched around a plurality of support rollers, instead of a roller-type secondary transfer unit having a secondary transfer roller or the like.

[0031] The fixing unit 30 includes a fixing roller, a pressure roller, etc. The fixing roller is heated to a predetermined fixing temperature, and the pressure roller forms a fixing nip between the fixing roller and the pressure roller to sandwich and transport the paper. In the fixing unit 30, the toner image is fixed to the paper by heating and pressurizing the paper, which has been secondarily transferred and transported, in the fixing nip.

[0032] Paper transport section 40 is composed of, for example, a path for transporting paper, a plurality of transport rollers, a drive motor for driving and rotating these transport rollers, and the like.

[0033] The paper transport section 40 transports the paper supplied from the paper feed section 200 to the secondary transfer unit 23 and the fixing section 30 , and then transports the paper to the inspection section 300 and the paper discharge section 400 .

[0034] The operation display unit 50 is composed of, for example, a liquid crystal display (LCD) with a touch panel, and functions as a display unit and an operation unit. The display unit displays various operation screens, image status display, operation status of each function, etc., according to a display control signal input from the control unit 60. The operation unit has various operation keys such as a numeric keypad and a start key, and accepts various input operations by the user and outputs operation signals to the control unit 60.

[0035] The paper feed unit 200 is disposed upstream of the image forming apparatus main body 100 in the paper transport direction D, and is connected to the image forming apparatus main body 100. The paper feed unit 200 has a plurality of paper feed trays 201-203, and each of the paper feed trays 201-203 stores paper sheets (standard paper, special paper) identified based on basis weight, size, etc., by preset type. The paper feed unit 200 supplies the specified paper to the image forming apparatus main body 100 based on an instruction from the image forming apparatus main body 100.

[0036] The inspection section 300 is disposed between the image forming apparatus main body 100 and the paper discharge section 400, and in the paper transport direction D, is connected to the image forming apparatus main body 100 on the upstream side and connected to the paper discharge section 400 on the downstream side.

[0037] The inspection unit 300 reads an image formed on a sheet and judges the presence or absence of image abnormalities such as image density, color shift, streaks, etc. The inspection unit 300 has a sensor 310 that reads the sheet conveyed from the image forming apparatus main body 100, a judgment unit 320, etc.

[0038] The sensor 310 is disposed above the path along which the paper is transported, facing the paper being transported, and configured to read the front (upper) surface of the paper being transported.

[0039] The sensor 310 acquires information about the paper. The sensor 310 acquires, as the information about the paper, for example, image data of an image printed by the image forming apparatus main body 100 (data about image density, color shift, etc.). Image forming conditions, etc. are set based on the information acquired by the sensor 310. As the sensor 310 that acquires such information, an in-line sensor or an area sensor having a CCD (Charge Coupled Device), a CIS (Contact Image Sensor), a spectrophotometer, etc. can be used.

[0040] The determination unit 320 determines the presence or absence of image abnormalities such as image density, color shift, streaks, etc., by comparing, for example, with standard data based on the results of reading a color chart (see FIGS. 4 to 8) described later by the sensor 310. Furthermore, the determination unit 320 determines the presence or absence of image abnormalities such as image density, color shift, streaks, etc., based on the results of reading a line pattern (see FIG. 8) described later by the sensor 310, ascertains the standard color that causes the image abnormality and the position where the image abnormality is detected, and determines whether or not image formation is possible.

[0041] The sensor 310 may be configured to acquire other information related to the paper in addition to data related to image density, color shift, etc. For example, the sensor 310 may acquire the position of the printed image, etc.

[0042] The paper discharge unit 400 is disposed downstream of the image forming apparatus main body 100 in the paper transport direction D, and is connected to the image forming apparatus main body 100 via the inspection unit 300. The paper discharge unit 400 discharges the paper transported from the image forming apparatus main body 100 to a paper discharge tray 401.

[0043] With the above-described configuration, the image forming apparatus 1 receives paper from the paper feed section 200, forms a color image on the paper in the image forming apparatus main body 100, and discharges the paper on which the color image has been formed to the paper discharge section 400.

[0044] In the image forming apparatus 1, calibration and profile creation for adjusting image formation conditions are performed using the inspection unit 300. When performing calibration and profile creation, the image forming apparatus 1 forms an image of a color chart on paper using the image forming apparatus main body 100, and measures the color using the sensor 310 of the inspection unit 300.

[0045] Conventionally, when an image abnormality such as a streak occurs on a patch image of a color chart formed on paper, the color measurement accuracy of that part decreases, and as a result, accurate calibration and profile creation cannot be performed. In addition, work cannot be continued until the cause of the image abnormality is resolved.

[0046] Therefore, in this embodiment, when an image abnormality is detected by the inspection unit 300, the image forming unit 20 replaces the color of the area where the image abnormality was detected with a color that does not use the standard color that is the cause of the image abnormality, and re-forms the color chart.

[0047] Although the details will be described below, as an example, in a color chart consisting of a plurality of patch images, a patch image in which an image abnormality has been detected is replaced with a patch image that does not use the standard color that causes the image abnormality, and the color chart is re-formed. In this way, even if an image abnormality exists, it is possible to form a color chart that allows color measurement while avoiding the influence of the image abnormality, and to perform color measurement.

[0048] The image formation of the color chart in this embodiment will be described with reference to Fig. 3, Fig. 4 and Fig. 5. In this embodiment, for example, a color chart forming program for executing the color chart forming method described below is stored in the ROM 62 of the control unit 60 or the like.

[0049] [How to form a color chart] Fig. 3 is a flow chart for explaining an example of a method for forming a color chart in the image forming apparatus 1. Figs. 4 and 5 are diagrams for explaining an example of changing the layout of a color chart, with Fig. 4 showing the color chart before the change and Fig. 5 showing the color chart after the change. Note that the color charts shown in Figs. 4 and 5 are actually made up of many colors, but are shown in grayscale in Figs. 4 and 5 due to drawing constraints. In Figs. 4 and 5, the horizontal direction is the paper width direction, the vertical direction is the paper transport direction, and the paper width direction and the paper transport direction are perpendicular to each other.

[0050] (Step S11) The control unit 60 instructs the image forming apparatus 1 to print a color chart.

[0051] The color chart here is a random chart in which a large number of colors are randomly arranged, which are a random combination of the four CMYK colors (standard colors) described above. The color chart, as an example, is made up of a plurality of patch images that are different from each other. One patch image is made up of a plurality of color measurement areas that are different from each other. Each color measurement area is made up of a single color. In the color chart shown in Figs. 4 and 5, if the horizontal direction is columns and the vertical direction is rows, a plurality of patch images are arranged in a matrix, with one patch image being a color measurement area of ​​1 column x 6 rows. Note that hereinafter, a patch image may also be referred to as a patch.

[0052] (Step S12) The control unit 60 controls the image processing unit 10 to rasterize the color chart. That is, the image processing unit 10 bitmaps the color chart in accordance with the image resolution of the image formed by the image forming apparatus main body 100.

[0053] (Step S13) The control unit 60 controls the image forming unit 20 to form an image of the rasterized color chart. Thereafter, the control unit 60 controls the fixing unit 30 to fix the formed color chart on the paper, and controls the paper transport unit 40 to transport the paper on which the color chart has been fixed to the inspection unit 300.

[0054] (Step S14) The control unit 60 controls the inspection unit 300 to have the sensor 310 read the color chart on the conveyed paper, and to detect image abnormalities such as streaks that affect color measurement based on the read result.

[0055] 4, as an example, it is assumed that a white vertical stripe occurs at position Pos1. In this case, the inspection unit 300 detects that a vertical stripe occurs at position Pos1.

[0056] (Step S15) The control unit 60 checks whether an image abnormality has been detected by the inspection unit 300. If an image abnormality has been detected (YES), the process proceeds to step S16, and if an image abnormality has not been detected (NO), the process ends.

[0057] (Step S16) The control unit 60 determines whether all patches at positions where image abnormalities are detected can be replaced with patches at positions where image abnormalities are not detected, that is, whether they can be rearranged, based on the image abnormality determination results by the inspection unit 300. If rearrangement is possible (YES), the process proceeds to step S17, and if rearrangement is not possible (NO), the process ends.

[0058] 4, vertical stripes occur at position Pos1, so the control unit 60 determines the color of the toner that causes the vertical stripes based on the colors of the toners used in the patches P1 and P2 at position Pos1. For example, if all the colorimetric areas of the patches P1 and P2 use yellow toner, and toners of other colors are used or not used depending on the colorimetric area, it can be determined that the yellow toner is the cause of the vertical stripes.

[0059] Then, the control unit 60 exchanges the positions of the patches, that is, rearranges the patches, so that the patch that does not use yellow toner is placed at position Pos1 in the color chart. The target patch for the exchange of positions of the patches P1 and P2 is a patch that does not use yellow toner in a row that contains a patch that uses yellow toner and does not have vertical streaks.

[0060] For example, in the color chart shown in Fig. 4, patch P4 in column C1 is a patch that uses yellow toner and does not have vertical streaks, and patch P3 in the same column C1 is a patch that does not use yellow toner. Similarly, patch P6 in column C2 is a patch that uses yellow toner and does not have vertical streaks, and patch P5 in the same column C2 is a patch that does not use yellow toner. Therefore, the target patches for position exchange of patches P1 and P2 are patches P3 and P5.

[0061] (Step S17) If rearrangement is possible in step S16 (YES), the control unit 60 performs processing to change the arrangement of the color chart and returns to step S12. Thereafter, steps S12 to S17 are repeated until no image abnormality is detected or rearrangement is impossible.

[0062] As described above, in the color chart shown in Fig. 4, the target patches for the position exchange of patches P1 and P2 are patches P3 and P5. Therefore, through step S17, steps S12 and S13, a color chart is formed in which the positions of patches P1 and P3 are exchanged and the positions of patches P2 and P5 are exchanged, for example, as shown in Fig. 5.

[0063] In this way, the patches P1 and P2 in which image abnormalities were detected are replaced with patches P3 and P5 that do not use yellow toner, which is the standard color that causes image abnormalities, thereby preventing vertical streaks from appearing on the re-formed color chart.

[0064] If no image abnormality is detected in step S15 (NO), the control unit 60 ends the series of processes, but notifies the user that the image forming device 1 is in a state where it can operate without any problems. In this case, the image forming device 1 waits for the next operation instruction from the user, for example, a print job.

[0065] If rearrangement is not possible in step S16 (NO), the control unit 60 ends the series of processes, but notifies the user that the image forming apparatus 1 is not in a state where accurate color measurement is possible. The control unit 60 notifies the user of this fact by, for example, displaying an error message or an error sound via the operation display unit 50, and prompts the user to solve the cause of the image abnormality.

[0066] In this way, the patch image in which the image abnormality is detected is replaced with a patch image that does not use the standard color that causes the image abnormality, and the color chart is reformed. This essentially means that the color chart is reformed in the area in which the image abnormality is detected (for example, the area of ​​the patch image) using a color that does not use the standard color that causes the image abnormality, or using a color generated by replacing the standard color with a different standard color. In other words, the color in the area in which the image abnormality is detected is replaced with a color that does not use the standard color that causes the image abnormality, and the color chart is reformed.

[0067] As described above, in the present embodiment, the image forming apparatus 1 includes at least the image forming unit 20 and the inspection unit 300. When an image abnormality is detected by the inspection unit 300, the image forming unit 20 replaces the color of the area where the image abnormality is detected with a color that does not use the standard color that is the cause of the image abnormality, and re-forms the color chart.

[0068] According to the image forming apparatus 1 of the present embodiment configured as described above, even if an image abnormality occurs in the formed image, it is possible to avoid the influence of the image abnormality and re-form a measurable color chart. As a result, the color measurement accuracy is not reduced, and accurate calibration and profile creation can be performed. As a result, it is possible to avoid wasting paper used for color measurement and redoing the color measurement work.

[0069] In this embodiment, a patch image having vertical streaks along the paper transport direction (sub-scanning direction) is replaced with a patch image at a different position in the paper width direction (main scanning direction), while a patch image having horizontal streaks along the paper width direction is replaced with a patch image at a different position in the paper transport direction.

[0070] <Variation 1> In the above embodiment, a case has been described in which a random chart in which patch images are randomly arranged is used as the color chart. However, a case in which a gradation chart is used will be described below with reference to FIGS. 6 to 8.

[0071] Here, Figures 6 to 8 are diagrams for explaining another example of changing the layout of a color chart, where Figure 6 is a diagram showing the color chart before the change, Figure 7 is a diagram showing the color chart after the change, and Figure 8 is a diagram showing the color chart after the second change. Note that the color chart shown in Figures 6 to 8 is actually made up of four colors (standard colors), CMYK, but is shown in grayscale in Figures 6 to 8 due to drawing constraints.

[0072] In the case of this modification, the image forming apparatus may be the image forming apparatus 1 described in the above embodiment, and therefore a duplicated description of the image forming apparatus 1 will be omitted.

[0073] Although the color chart may be formed in the same manner as described with reference to Fig. 3, this modified example describes a case in which patch images are further rearranged. Hereinafter, the color chart forming method in this modified example will be described with reference to Fig. 3.

[0074] (Step S11) This step is the same as step S11 in the above embodiment. The control unit 60 instructs the image forming apparatus 1 to print a color chart.

[0075] The color chart in this modified example is a gradation chart using the above-mentioned four colors (standard colors) of CMYK, and arranging the shades of each standard color with a gradation. In the example shown in Figs. 6 to 8, if the horizontal direction (paper width direction) is the columns and the vertical direction (paper transport direction) is the rows, the standard colors are arranged in four columns, and the shades of each standard color are gradated in the row direction. In this case, each standard color is one patch image, and one patch image is made up of multiple colorimetric areas. In one patch image, the multiple colorimetric areas have the same standard color but different shades.

[0076] (Step S12) This step is also similar to step S12 in the above embodiment. The control unit 60 controls the image processing unit 10 to rasterize the color chart.

[0077] (Step S13) This step is also similar to step S13 in the above embodiment. The control unit 60 controls the image forming unit 20 to form an image of the rasterized color chart, controls the fixing unit 30 to fix the formed color chart on paper, and controls the paper transport unit 40 to transport the paper on which the color chart has been fixed to the inspection unit 300.

[0078] (Step S14) This step is also similar to step S14 in the above embodiment. The control unit 60 controls the inspection unit 300 to have the sensor 310 read the color chart on the conveyed paper and detect image abnormalities such as streaks that affect color measurement based on the read result.

[0079] 6, the color chart is in the order of YMCK from left to right, and in this case, as an example, it is assumed that a vertical stripe occurs at position Pos2 in the yellow patch P11. In this case, the inspection unit 300 detects that a vertical stripe occurs at position Pos2.

[0080] (Step S15) This step is also similar to step S15 in the above embodiment. The control unit 60 checks whether an image abnormality has been detected by the inspection unit 300. If an image abnormality has been detected (YES), the process proceeds to step S16, and if an image abnormality has not been detected (NO), the process ends.

[0081] (Step S16) This step is also the same as step S16 in the above embodiment. The control unit 60 determines whether the patch at the position where the image abnormality was detected can be replaced with a patch at the position where the image abnormality was not detected, that is, whether the patch can be rearranged, based on the image abnormality determination result by the inspection unit 300. If the patch can be rearranged (YES), the process proceeds to step S17, and if the patch cannot be rearranged (NO), the process ends.

[0082] 6, vertical stripes occur at position Pos2, so the control unit 60 determines the color of toner that causes the vertical stripes based on the color of toner used in patch P11 at position Pos2. Here, patch P11 uses only yellow toner, so it can be determined that yellow toner is the cause of the vertical stripes.

[0083] Then, the control unit 60 exchanges the positions of the patches, that is, rearranges the patches, so that the patch that does not use yellow toner is placed in the area of ​​the patch P11. The target patch for the exchange of the position of the patch P11 is, for example, patch P12 that uses cyan toner and is a patch that does not use yellow toner.

[0084] If no image abnormality is detected in step S15 (NO) or if rearrangement is not possible in step S16 (NO), the control unit 60 performs the same process as that described in the above embodiment.

[0085] (Step S17) This step is also the same as step S17 in the above embodiment. If rearrangement is possible in step S16 (YES), the control unit 60 performs a color chart rearrangement process and returns to step S12. Thereafter, steps S12 to S17 are repeated until image abnormalities are no longer detected or rearrangement is impossible.

[0086] As described above, in the color chart shown in Fig. 6, the target patch for exchanging the position of patch P11 is, for example, patch P12. Therefore, through step S17, steps S12, and S13, a color chart is formed in which the positions of patch P11 and patch P12 are exchanged, as shown in Fig. 7, for example. In Fig. 7, the color chart is arranged in the order of CMYK from left to right.

[0087] In this way, the patch P11 in which an image abnormality was detected is replaced with a patch P12 that does not use yellow toner, which is the standard color that causes the image abnormality, thereby preventing vertical streaks from appearing in the newly formed color chart.

[0088] However, in this modified example, it is assumed that even if the patch P11 and the patch P12 are swapped, a vertical streak occurs at a position Pos3 in the area of ​​the rearranged patch P11. In this case, after step S14, the inspection unit 300 detects that a vertical streak occurs at the position Pos3.

[0089] Then, the control unit 60 performs steps S15 and S16 to change the layout of the color chart.

[0090] 7, vertical stripes also occur at position Pos3, so the control unit 60 determines the color of toner that causes the vertical stripes based on the color of toner used in patch P11 at position Pos3. Again, patch P11 uses only yellow toner, so it can be determined that yellow toner is the cause of the vertical stripes. In other words, even if the position of yellow toner patch P11 is changed, vertical stripes still occur.

[0091] Therefore, the control unit 60 exchanges the positions of the patches, that is, rearranges the patches, so that a different patch (a patch different from patch P12) that does not use yellow toner is placed in the area of ​​patch P11. The target patch for the exchange of position of patch P11 here is, for example, patch P13 that uses black toner and does not use yellow toner.

[0092] Then, the control unit 60 performs step S17, steps S12, and S13 to form a color chart in which the positions of the patch P11 and the patch P13 are swapped, as shown in Fig. 8. In Fig. 8, the color chart is in the order of KMCY from the left to the right.

[0093] In this way, the patch P11 in which an image abnormality was detected is replaced with a patch P13 that does not use yellow toner, which is the standard color that causes the image abnormality, thereby preventing vertical streaks from appearing in the newly formed color chart.

[0094] At this time, in this modified example, the control unit 60 instructs the image forming device 1 to print a line pattern patch P14 of the four colors (standard colors) of CMYK extending across the paper width direction (scanning direction) at the bottom (or top) of the color chart on the paper.

[0095] In this modified example, even if it is determined in step S16 that rearrangement of the patch is not possible (NO), the control unit 60 instructs the image forming apparatus 1 to print the patch P14 of the line pattern described above.

[0096] By forming such patch P14, the vertical streaks that occurred at positions Pos2 and Pos3 on the color chart shown in Figures 6 and 7 also occur at positions Pos4 and Pos5 on the yellow line pattern of patch P14. The control unit 60 controls the inspection unit 300 and reads the color chart shown in Figure 8 with the sensor 310, thereby making it possible to grasp the standard color and the positions Pos4 and Pos5 where the vertical streaks occur.

[0097] When printing, if the image specified by the user does not use yellow at positions Pos4 and Pos5, or if no image is to be printed at positions Pos4 and Pos5, the above-mentioned judgment unit 320 judges that printing is possible, and the image forming device 1 can perform the printing operation.

[0098] Therefore, the image forming apparatus 1 is able to execute commercial printing work under the above-mentioned conditions after grasping the standard color where the image abnormality is present and the position of the image abnormality. Furthermore, even if an image abnormality occurs during commercial printing work, the image forming apparatus 1 is able to continue the commercial printing work under the above-mentioned conditions. In such a case, the control unit 60 notifies the user of the standard color where the image abnormality is present and the position of the image abnormality via the operation display unit 50, for example, so that the user can recognize that printing is possible under certain conditions.

[0099] As described above, in this modified example, even if an image abnormality occurs and the cause of the image abnormality has not been resolved, the printing operation can be executed and continued by the image forming apparatus 1, provided that the corresponding standard color is not used at the position where the image abnormality was detected. The same is true even if it is determined in step S16 that rearrangement of the patch is not possible (if NO), and the printing operation can be executed and continued by the image forming apparatus 1, provided that the above-mentioned conditions are met.

[0100] 8 is printed with a line pattern patch P14 extending across the paper width direction (main scanning direction), but it may also be printed with a line pattern patch of four colors (standard colors) of CMYK extending across the paper transport direction (sub-scanning direction). When an image abnormality due to horizontal streaks occurs, the horizontal streaks occur in the line pattern patch in the paper transport direction, so the control unit 60 can grasp, via the inspection unit 300, the standard color and position where the horizontal streaks occur.

[0101] In addition, the above-mentioned line pattern patch P14 in the paper width direction and the line pattern patch in the paper transport direction may be printed together with the color chart (random chart) shown in Figures 4 and 5 to identify the standard color and position where streaks will occur.

[0102] The above-mentioned embodiments are merely examples of the embodiment of the present invention, and the technical scope of the present invention should not be interpreted as being limited by these. In other words, the present invention can be embodied in various forms without departing from the gist or main characteristics of the present invention.

[0103] For example, in the above embodiment, the occurrence of streaks has been described as an example of an image abnormality, but the present invention is also applicable to cases where such image abnormalities occur as long as they are caused by the same reasons as streaks.

[0104] Furthermore, in the above embodiment, a color image forming apparatus using electrophotographic process technology has been described as an example, but the present invention is also applicable to a color image forming apparatus using inkjet technology. [Explanation of symbols]

[0105] 1. Image forming device 10 Image processing section 20 Image forming section 30 Fixing section 40 Paper transport section 50 Operation display section 60 Control section 100 Image forming apparatus body 200 Paper feed section 300 Inspection Department 310 Sensors 320 Judgment section 400 Paper output section

Claims

1. an image forming unit that forms a color image including a color chart on a recording medium, the color image being made up of colors generated using a plurality of standard colors; a detection unit that detects an image abnormality by reading the color chart formed on the recording medium by the image forming unit; Equipped with When the image abnormality is detected by the detection unit, the image forming unit replaces the color of the area where the image abnormality is detected with a color that does not use the standard color that is the cause of the image abnormality, and re-forms the color chart. Image forming device.

2. the color chart is made up of a plurality of patch images, the image forming unit replaces the patch image in which the image abnormality has been detected with a patch image that does not use the standard color that causes the image abnormality, and re-forms the color chart. The image forming apparatus according to claim 1 .

3. the color chart is a chart in which the plurality of patch images are arranged in a matrix, the image forming unit uses the standard color causing the image abnormality for the patch image in which the image abnormality has been detected, and replaces the patch image in which the image abnormality has not been detected with another patch image in a row or column in which the patch image in which the image abnormality has not been detected is a patch image in which the standard color causing the image abnormality is not used, thereby re-forming the color chart. The image forming apparatus according to claim 2 .

4. When re-forming the color chart, the image forming unit forms a line pattern of each of the plurality of standard colors on the recording medium so as to extend across a width direction of the recording medium or a direction perpendicular to the width direction. The image forming apparatus according to claim 1 .

5. a determination unit that determines whether or not an image can be formed by grasping the standard color causing the image abnormality and a position where the image abnormality is detected based on a result of reading the line pattern by the detection unit, the determination unit, when an image designated by a user is to be formed, determines whether or not the designated image can be formed based on the standard color causing the image abnormality and a position where the image abnormality is detected. The image forming apparatus according to claim 4 .

6. When the determination unit determines that the image formation of the specified image is possible, the image formation unit performs the image formation of the specified image. The image forming apparatus according to claim 5 .

7. an image processing unit that rasterizes a color chart specified by a user; The image forming apparatus according to claim 1 .

8. The image forming unit forms the color chart based on the data rasterized by the image processing unit. The image forming apparatus according to claim 7.

9. forming a color chart on a recording medium, the color chart being composed of colors generated using a plurality of standard colors; The formed color chart is read to detect image abnormalities, When the image abnormality is detected, the color of the area where the image abnormality is detected is replaced with a color that does not use the standard color and is the cause of the image abnormality, and the color chart is regenerated. How to form a color chart.

10. On the computer, A process of forming a color chart on a recording medium, the color chart being composed of colors generated using a plurality of standard colors; A process of reading the formed color chart and detecting image abnormalities; When the image abnormality is detected, a process of replacing the color of the area where the image abnormality is detected with a color that does not use the standard color and is the cause of the image abnormality, and regenerating the color chart; Execute the Color chart formation program.

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