Image forming apparatus, image forming method, and image forming program

Abstract

To provide an image forming apparatus, an image forming method and an image forming program which facilitate shortening a time required for forming a test image and facilitate reducing an amount of consumption of consumables.SOLUTION: An image forming apparatus includes an image forming unit, an image reading unit, and a test processing unit. The image forming unit forms an image on a sheet Sh1 using a plurality of recording elements. The image reading unit reads the image on the sheet Sh1. The test processing unit causes the image forming unit to form a test image Im1 in a marginal region of the sheet Sh1, and causes the image reading unit to read the test image Im1. The test processing unit is capable of executing a divisional test in which only some of the plurality of recording elements are used for forming a single test image Im1 to be formed on a single sheet Sh1 and all of the plurality of recording elements are used for forming a test image group constituted of the plurality of test images Im1 to be formed on the plurality of sheets Sh1.SELECTED DRAWING: Figure 5

Description

[Technical field]

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

[0002] As a related technique, an image forming apparatus (inkjet recording apparatus) having a function for detecting defective ink ejection is known (see, for example, Patent Document 1). The image forming apparatus according to the related technique forms an image on a sheet (recording medium) by ejecting ink from multiple arranged nozzles onto the sheet. This image forming apparatus is capable of compensating for degradation in the quality of the formed image caused by defective ink ejection from a nozzle by adjusting the amount of ink ejected from adjacent nozzles based on the inspection results of the ink ejection state from the nozzles.

[0003] In an image forming apparatus according to the related art, when inspecting the ink ejection state, ink is ejected from a plurality of nozzles onto a sheet, a halftone image of a predetermined density is formed on the sheet as an inspection image (test image), and the inspection image is read. Then, the image forming apparatus determines whether there is an ejection defect from the nozzle based on the density of the read inspection image. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2015-58602 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the configuration of the related art described above, a test image is formed by ejecting ink from all of the multiple nozzles onto a single sheet, which means that it tends to take a long time to form a test image onto a single sheet and tends to consume a large amount of consumables (ink).

[0006] An object of the present invention is to provide an image forming apparatus, an image forming method, and an image forming program that can easily shorten the time required to form an inspection image and can easily reduce the consumption of consumables. [Means for solving the problem]

[0007] According to one aspect of the present invention, an image forming apparatus includes an image forming section, a sheet conveying section, an image reading section, and an inspection processing section. The image forming section forms an image on a sheet using a plurality of recording elements. The sheet conveying section conveys the sheet along a conveying path leading to a discharge destination of the sheet via the image forming section. The image reading section is disposed downstream of the image forming section on the conveying path and reads the image on the sheet. The inspection processing section causes the image forming section to form an inspection image for a marginal area of ​​the sheet, and causes the image reading section to read the inspection image. The inspection processing section is capable of performing a split inspection in which only a portion of the plurality of recording elements is used to form a single inspection image formed on one of the sheets, and all of the plurality of recording elements are used to form an inspection image group consisting of a plurality of the inspection images formed on a plurality of the sheets. In the split inspection, each of the inspection images included in the inspection image group is formed periodically. The inspection processing unit inspects the inspection image each time the inspection image included in the inspection image group is read by the image reading unit, and if the inspection image is determined to be defective, reports this fact and identifiably discharges a specific sheet including a sheet surface on which an image will be formed next to the sheet surface including the inspection image one period before the inspection image determined to be defective.

[0008] An image forming method according to another aspect of the present invention is executed by an image forming apparatus including an image forming unit that forms an image on a sheet using a plurality of recording elements, a sheet conveying unit that conveys the sheet along a conveying path to a discharge destination of the sheet via the image forming unit, and an image reading unit that is disposed downstream of the image forming unit on the conveying path and reads the image on the sheet, and includes an inspection step. In the inspection step, an inspection image is formed on a marginal area of ​​the sheet by the image forming unit, and the inspection image is read by the image reading unit. In the inspection step, a split inspection is performed in which only a portion of the plurality of recording elements is used to form a single inspection image formed on one of the sheets, and all of the plurality of recording elements are used to form an inspection image group consisting of a plurality of the inspection images formed on a plurality of the sheets. In the split inspection, each of the inspection images included in the inspection image group is formed periodically. In the inspection step, the image reading unit inspects the inspection image each time it reads an inspection image included in the inspection image group, and if the inspection image is determined to be defective, a notification to that effect is given and a specific sheet including a sheet surface on which an image will be formed next to the sheet surface including the inspection image one period before the inspection image determined to be defective is identifiably discharged.

[0009] An image forming program according to another aspect of the present invention is a program for causing one or more processors to execute the image forming method. Effect of the Invention

[0010] According to the present invention, it is possible to provide an image forming apparatus, an image forming method, and an image forming program that can easily reduce the time required to form an inspection image and the consumption of consumables. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of an image forming system according to the first embodiment. [Diagram 2]FIG. 2 is a block diagram showing the configuration of the image forming apparatus according to the first embodiment. [Diagram 3] FIG. 3 is a schematic diagram showing a configuration of the image forming unit of the image forming apparatus according to the first embodiment. [Figure 4] FIG. 4 is a schematic diagram showing an example of an inspection process in the image forming apparatus according to the first embodiment. [Diagram 5] FIG. 5 is a schematic diagram showing an example of the inspection process in the image forming apparatus according to the first embodiment. [Figure 6] FIG. 6 is a schematic diagram showing an example of the inspection process in the image forming apparatus according to the first embodiment. [Figure 7] FIG. 7 is a schematic diagram showing an example of the inspection process in the image forming apparatus according to the first embodiment. [Figure 8] FIG. 8 is a schematic diagram showing an example of the inspection process in the image forming apparatus according to the first embodiment. [Figure 9] FIG. 9 is a schematic diagram showing an example of the inspection process in the image forming apparatus according to the first embodiment. [Figure 10] FIG. 10 is a flowchart illustrating an example of the operation of the inspection processing unit in the image forming apparatus according to the first embodiment. [Figure 11] FIG. 11 is a schematic diagram showing an example of an inspection process in the image forming apparatus according to the second embodiment. [Figure 12] FIG. 12 is a schematic diagram showing an example of an inspection process in the image forming apparatus according to the second embodiment. [Figure 13] FIG. 13 is a schematic diagram showing an example of an inspection process in the image forming apparatus according to the second embodiment. [Figure 14] FIG. 14 is a schematic diagram showing the configuration of an image forming system according to the third embodiment. [Figure 15] FIG. 15 is a schematic diagram showing an example of an inspection process in the image forming system according to the third embodiment. [Figure 16] FIG. 16 is a flowchart illustrating an example of the operation of the inspection processing unit in the image forming system according to the third embodiment. [Figure 17]FIG. 17 is a schematic diagram showing the configuration of an image forming system according to the fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. The following embodiment is an example of the present invention, and is not intended to limit the technical scope of the present invention.

[0013] (Embodiment 1) [1] Overall configuration of image forming device First, the overall configuration of an image forming apparatus 10 according to the present embodiment will be described with reference to FIGS. 1 to 3. FIG.

[0014] As an example in this embodiment, the image forming apparatus 10 is an inkjet recording apparatus (printer) that has a recording head 51 that ejects ink onto the surface of a sheet Sh1 and is capable of performing a print process by an inkjet method in which an image is formed on the sheet Sh1 by the recording head 51. The print process is a process in which an image is formed on an image forming target. The sheet Sh1 is an example of an image forming target (recording medium) on which an image is formed by the image forming apparatus 10, and is a sheet-like medium such as paper or a resin film.

[0015] The image forming device 10 only needs to have a function of forming an image by an inkjet method, and may be, for example, a multifunction machine having multiple functions such as a scanning function for reading image data from a document, a facsimile function, and a copy function in addition to a print function. The image forming device 10 may also be a facsimile machine or a copy machine.

[0016] As shown in FIG. 1, the image forming apparatus 10 constitutes an image forming system 100 together with a paper feeder 11, a dryer 12, and a discharger 13. In other words, the image forming system 100 according to the present embodiment includes the image forming apparatus 10, the paper feeder 11, the dryer 12, and the discharger 13. Here, the image forming apparatus 10, the paper feeder 11, the dryer 12, and the discharger 13 are connected in the order of the paper feeder 11, the image forming apparatus 10, the dryer 12, and the discharger 13 from the upstream side with respect to the conveyance direction of the sheet Sh1. As a result, the image forming system 100 can continuously perform a series of processes performed by each of the paper feeder 11, the image forming apparatus 10, the dryer 12, and the discharger 13 on the sheet Sh1. In addition, each device of the image forming system 100 is centrally managed by a control device 7 of the image forming apparatus 10. However, this configuration is not limited, and a control device that centrally manages each device may be provided separately from the control device 7.

[0017] The paper feeder 11 can store a plurality of sheets Sh1. The paper feeder 11 supplies the sheets Sh1 one by one to the image forming apparatus 10. The image forming apparatus 10 ejects ink from a recording head 51 onto the sheet Sh1 supplied from the paper feeder 11, and forms an image (ink image) on the sheet by an inkjet method. The image forming apparatus 10 sends the sheet Sh1 on which the image has been formed to a drying apparatus 12 in the downstream stage.

[0018] The drying device 12 has a drying chamber therein, and has a heater or a heat pump type heating unit or the like in the drying chamber. The drying device 12 dries the ink image formed on the sheet Sh1 by heating the surface of the sheet Sh1 conveyed from the image forming device 10 into the drying chamber. The drying device 12 has an exhaust fan that exhausts (discharges) moisture from the drying chamber. The drying device 12 sends the sheet Sh1 that has been subjected to the drying process to the discharge device 13 at the downstream stage. As a result, the sheet Sh1 on which the image has been formed by the image forming device 10 using the inkjet method is discharged to the discharge device 13.

[0019] The discharge device 13 stores the sheet Sh1 conveyed from the drying device 12. The discharge device 13 may also have a post-processing function such as a staple function or a punch function. In this case, the discharge device 13 can perform appropriate post-processing on the sheet Sh1 on which an image has been formed. In single-sided printing in which an image is formed only on one side of the sheet Sh1, the sheet Sh1 that has been dried by the drying device 12 is sent to the discharge device 13, but in double-sided printing in which images are formed on both sides of the sheet Sh1, the sheet Sh1 is returned to the image forming device 10 after being dried by the drying device 12. Then, an image is formed on the back side by the image forming device 10, and the sheet Sh1 is sent to the discharge device 13 after being dried by the drying device 12.

[0020] 1 and 2, the image forming apparatus 10 includes a sheet transport device 4, an image forming unit 5, an ink supply unit 6, a control device 7, an image reading unit 8, etc. The image forming unit 5 has a plurality of recording heads 51. The sheet transport device 4, the image forming unit 5, the ink supply unit 6, the control device 7, the image reading unit 8, etc. are housed in a housing 21 that forms the outer shell of the image forming apparatus 10.

[0021] The sheet conveying device 4 conveys the sheet Sh1 supplied from the paper feeder 11 one by one through the conveying path 40. As a result, the sheet Sh1 taken into the housing 21 of the image forming device 10 from the paper feeder 11 is conveyed below the image forming unit 5 in the conveying direction D1 through the conveying path 40 and discharged to the drying device 12. The conveying path 40 is a path for conveying the sheet Sh1 within the housing 21, and includes a front-stage conveying path 401 on the upstream side with respect to the image forming unit 5 and a rear-stage conveying path 402 on the downstream side. The sheet conveying device 4 conveys the sheet Sh1 supplied from the paper feeder 11 to the image forming unit 5 through the front-stage conveying path 401, and discharges the sheet Sh1 from the image forming unit 5 to the drying device 12 through the rear-stage conveying path 402.

[0022] The sheet transport device 4 includes a sheet output section 41, one or more pairs of front-stage transport rollers 42, a main transport unit 43, and a discharge roller pair 44. The sheet output section 41 outputs the sheet Sh1 supplied from the paper feeder 11 to a front-stage transport path 401 one by one. The multiple pairs of front-stage transport rollers 42 take over the transport of the sheet Sh1 from the sheet output section 41, and transport the sheet Sh1 toward the main transport unit 43.

[0023] The main transport unit 43 is disposed below the image forming unit 5. The front transport path 401 is a path that leads from the paper feeder 11 to below the image forming unit 5 (above the main transport unit 43). The main transport unit 43 transports the sheet Sh1 while facing the first surface (front surface) of the sheet Sh1 to the image forming unit 5. The first surface of the sheet Sh1 is the surface on which an ink image is formed. The main transport unit 43 has a plurality of tension rollers 431 and a main transport belt 432, and the main transport belt 432 is supported and rotated by the plurality of tension rollers 431. As a result, the main transport unit 43 places the sheet Sh1 on the main transport belt 432 and transports it toward the discharge roller pair 44.

[0024] The discharge roller pair 44 discharges the sheet Sh1 on which the ink image is formed to the drying device 12. The rear transport path 402 is a path leading to the drying device 12 from below the image forming section 5 (above the main transport unit 43).

[0025] The image forming unit 5 is located above the main transport unit 43. The image forming unit 5 ejects inks of a plurality of colors toward the sheet Sh1 transported by the main transport unit 43 of the sheet transport device 4, thereby forming an ink image on a first surface of the sheet Sh1.

[0026] The image forming unit 5 includes a plurality of recording heads 51 and a head frame 52 that supports the plurality of recording heads 51. The plurality of recording heads 51 form an image on the sheet Sh1 by ejecting ink of a plurality of colors onto the sheet Sh1 being transported by the main transport unit 43.

[0027] In the example of FIG. 1, the multiple recording heads 51 are divided into four line heads 50 corresponding to the inks of the respective colors of black, cyan, magenta, and yellow. The ink supply unit 6 supplies the inks of the respective colors (K, C, M, Y) to the recording heads 51 of the corresponding line heads 50. The four line heads 50 are arranged side by side in the sub-scanning direction D12 and are fixed in a predetermined positional relationship (see FIG. 3). The number of line heads 50 provided in the image forming unit 5 is not limited to four, and may be, for example, two, three, five or more. The sub-scanning direction D12 is the same as the transport direction D1 of the sheet Sh1 on the main transport belt 432.

[0028] The recording heads 51 are arranged at positions where a gap of about 1 millimeter is formed between the ink ejection surface provided on the lower surface of each of the recording heads 51 and the upper surface of the sheet Sh1 on the main transport belt 432. As shown in FIG. 3, the recording heads 51 are arranged with their longitudinal directions aligned with the main scanning direction D11. In the present embodiment, as an example, each line head 50 of each color includes three recording heads 51. The ink ejection surface of each of the recording heads 51 is formed with a plurality of ink nozzles 53 that eject ink onto the sheet Sh1 transported along the transport path 40. Each of the recording heads 51 includes a plurality of piezoelectric elements corresponding to the plurality of ink nozzles 53. Each of the piezoelectric elements vibrates when a drive signal is supplied from the control device 7, thereby pressurizing the ink and ejecting (squirting) the ink from each ink nozzle 53.

[0029] The image reading unit 8 reads the image on the sheet Sh1. The image reading unit 8 reads the image from the sheet Sh1, and outputs image data corresponding to the read image to the control device 7. The image reading unit 8 includes a light source, a plurality of mirrors, an optical lens, a CCD (Charge Coupled Device), and the like.

[0030] In this embodiment, the image reading unit 8 is located above the rear conveying path 402. The image reading unit 8 is disposed downstream of the image forming unit 5 in the conveying direction D1 of the sheet Sh1 by the sheet conveying device 4. This allows the image reading unit 8 to read the image formed on the sheet Sh1 by the image forming unit 5 downstream. In other words, while the sheet Sh1 is being conveyed by the sheet conveying device 4, it is possible to both form an image on the sheet Sh1 and read the image.

[0031] The control device 7 performs overall control of the image forming apparatus 10. The control device 7 is mainly composed of a computer system having one or more processors and one or more non-volatile memories. In the image forming apparatus 10, the functions of the control device 7 are realized by the one or more processors executing a program. The program may be pre-recorded in a memory (storage unit), may be provided via a telecommunication line such as the Internet, or may be recorded and provided on a non-transitory recording medium readable by a computer system such as a memory card or an optical disk. The one or more processors are composed of one or more electronic circuits including a semiconductor integrated circuit. Furthermore, the computer system referred to here includes a microcontroller having one or more processors and one or more memories.

[0032] The control device 7 controls the sheet conveying device 4, the image forming unit 5, the ink supply unit 6, the image reading unit 8, and the like, which are included in the image forming apparatus 10. In other words, the control device 7 is electrically connected to each part of the image forming apparatus 10, and can, for example, control the image forming unit 5 to form a desired image on a sheet Sh1, or control the image reading unit 8 to read an image from the sheet Sh1. In other words, the control device 7 implements an image forming method that controls each part of the image forming apparatus 10 by executing an image formation program recorded in the memory.

[0033] In this embodiment, the control device 7 has at least the function of an inspection processing unit 71, as shown in Fig. 2. The inspection processing unit 71 inspects the operating state of the image forming unit 5. The inspection processing unit 71 controls the image forming unit 5 to form an inspection image on the sheet Sh1, controls the image reading unit 8 to read the inspection image, and inspects the operating state of the image forming unit 5 based on whether the inspection image is formed correctly or not. In this embodiment, since the image forming unit 5 is of an inkjet type, the inspection processing unit 71 inspects the ink ejection state from each ink nozzle 53.

[0034] When the inspection processing unit 71 detects an operational malfunction (ink ejection malfunction) of the image forming unit 5, the control device 7 executes a countermeasure process for the operational malfunction. As an example of the countermeasure process, the control device 7 corrects the variation in the ink ejection amount from the multiple ink nozzles 53 by shading correction or the like. Alternatively, when the ink ejection malfunction cannot be eliminated by changing only the ink ejection amount, the control device 7 may stop the image forming operation by the image forming unit 5 as a countermeasure process. In this case, the control device 7 may further cause the maintenance unit to perform a wiping operation, or may cause the operation display unit or the like to present (display, etc.) a message to the user to perform maintenance (replacement of the recording head 51, etc.) as a countermeasure process. The inspection processing unit 71 may be provided separately from the main control device 7 that controls the image forming apparatus 10 in an integrated manner.

[0035] The image forming apparatus 10 further includes a head cooling device, a maintenance unit, a cap unit, and an operation display unit. The head cooling device cools the recording head 51. The maintenance unit performs a wiping operation to wipe the ink ejection surface (the lower surface of the recording head 51) and clean the ink ejection surface. The cap unit covers the ink ejection surface of the recording head 51 to protect it from drying. The operation display unit is a user interface in the inkjet recording apparatus. The operation display unit has a display unit such as a liquid crystal display that displays various information in response to control instructions from the control device 7, and an operation unit such as a switch or touch panel that inputs various information to the control device in response to user operations.

[0036] [2] Details of the inspection processing unit Next, the inspection processing unit 71 of the image forming apparatus 10 according to this embodiment will be described in more detail with reference to Fig. 4 to Fig. 9. In this embodiment, as described above, the inspection processing unit 71 provided in the control device 7 inspects the image forming unit 5 for operational malfunctions (ink ejection malfunctions).

[0037] Specifically, the inspection processing unit 71 causes the image forming unit 5 to form an inspection image Im1 in the margin area R2 of the sheet Sh1, as shown in Fig. 4. Then, the inspection processing unit 71 causes the image reading unit 8 to read the inspection image Im1. Fig. 4 is a schematic diagram of the sheet Sh1 conveyed by the main conveying unit 43 of the sheet conveying device 4, as seen from above, and shows an enlarged view of the leading portion (range Z1) of the sheet Sh1 in the conveying direction D1 (the same as the sub-scanning direction D12) on the right side.

[0038] The sheet Sh1 includes an original region R1 and a margin region R2. The original region R1 and the margin region R2 are separated by a boundary line L1, and the region inside the boundary line L1 is the original region R1, and the region outside the boundary line L1 is the margin region R2. In FIG. 4 and other figures, the boundary line L1 is shown by an imaginary line (two-dot chain line), but the boundary line L1 is not actually formed on the sheet Sh1. The original region R1 is an area where a desired image is formed by the image forming unit 5. The margin region R2 is an area not used for forming the desired image, and is an area where, for example, a trim mark (register mark) M1 for cutting is formed.

[0039] That is, the inspection processing unit 71 forms an inspection image Im1 in such marginal area R2, and uses the marginal area R2 to inspect the operating state of the image forming unit 5. More specifically, as shown on the left side of Fig. 4, the image forming unit 5 forms the inspection image Im1 in the marginal area R2 on the leading side of the sheet Sh1 conveyed in the conveying direction D1 by the sheet conveying device 4. Then, the image reading unit 8 disposed downstream of the image forming unit 5 reads the inspection image Im1 formed on the sheet Sh1, thereby enabling inspection by the inspection processing unit 71.

[0040] The inspection processing unit 71 determines whether or not there is a defect caused by poor ink ejection, such as missing dots, in the read inspection image Im1, and if there is such a defect, determines that there is an operational malfunction (poor ink ejection) of the image forming unit 5. Furthermore, the inspection processing unit 71 can identify which of the multiple ink nozzles 53 has the ink ejection defect, based on the position where the defect occurs in the inspection image Im1.

[0041] As a related technique, an image forming apparatus (inkjet recording apparatus) having a function for detecting defective ink ejection is known. The image forming apparatus according to the related technique forms an image on a sheet (recording medium) by ejecting ink from a plurality of arranged nozzles onto the sheet. This image forming apparatus can compensate for the deterioration of the quality of the formed image caused by defective ink ejection from a nozzle by adjusting the amount of ink ejected from adjacent nozzles based on the inspection result of the ink ejection state from the nozzle.

[0042] In an image forming apparatus according to the related art, when inspecting the ink ejection state, ink is ejected from a plurality of nozzles onto a sheet, a halftone image of a predetermined density is formed on the sheet as an inspection image (test image), and the inspection image is read. Then, the image forming apparatus determines whether there is an ejection defect from the nozzle based on the density of the read inspection image.

[0043] However, in the configuration of the related art described above, a test image is formed by ejecting ink from all of the multiple nozzles onto a single sheet, which means that it tends to take a long time to form a test image onto a single sheet and tends to consume a large amount of consumables (ink).

[0044] In contrast, the image forming apparatus 10 according to this embodiment has the following configuration, which makes it possible to realize an image forming apparatus 10 that can easily shorten the time it takes to form an inspection image and reduce the consumption of consumables.

[0045] That is, the image forming apparatus 10 according to the present embodiment includes an image forming unit 5, an image reading unit 8, and an inspection processing unit 71. The image forming unit 5 forms an image on a sheet Sh1 using a plurality of recording elements. The image reading unit 8 reads the image on the sheet Sh1. The inspection processing unit 71 causes the image forming unit 5 to form an inspection image Im1 in the margin area R2 of the sheet Sh1, and causes the image reading unit 8 to read the inspection image Im1. Here, the inspection processing unit 71 is capable of performing a split inspection in which only a portion of the plurality of recording elements is used to form a single inspection image Im1 formed on one sheet Sh1, and all of the plurality of recording elements are used to form an inspection image group consisting of a plurality of inspection images Im1 formed on a plurality of sheets Sh1.

[0046] In this embodiment, the ink nozzles 53 are an example of a recording element. That is, the image forming unit 5 has a plurality of ink nozzles 53 (recording elements), and forms an image on the sheet Sh1 with the plurality of ink nozzles 53. Particularly in this embodiment, as shown in FIG. 3, the image forming unit 5 has four color line heads 50 each including three recording heads 51, and therefore the total number of the ink nozzles 53 provided in the total of 12 recording heads 51 is the total number of the ink nozzles 53 (recording elements) included in the image forming unit 5. In this way, the total number of ink nozzles 53 as recording elements included in the image forming unit 5 will also be referred to as a "predetermined number" below.

[0047] In short, in the divisional inspection, all of the predetermined number of ink nozzles 53 (recording elements) are not used to form a single inspection image Im1 for one sheet Sh1, but are used to form an inspection image group consisting of multiple inspection images Im1 for multiple sheets Sh1. In other words, in the divisional inspection, an inspection image Im1 using all of the predetermined number of ink nozzles 53 (recording elements) is not formed on a single sheet Sh1, but is formed in a divided manner on multiple sheets Sh1. As a result, the inspection of the predetermined number of ink nozzles 53 (recording elements) is performed using multiple sheets Sh1, rather than one sheet Sh1.

[0048] Therefore, the image forming apparatus 10 according to this embodiment has an advantage that it is easier to reduce the time required to form the test image Im1 for one sheet Sh1 and to reduce the consumption of consumables (ink) compared to the related art. Moreover, since all of the multiple recording elements (ink nozzles 53) can be inspected by the test image groups formed by dividing the multiple sheets Sh1, it is possible to inspect the entire image forming unit 5 (a predetermined number of recording elements).

[0049] A specific example of the inspection image Im1 used by the inspection processing unit 71 in the image forming apparatus 10 according to this embodiment will be described below with reference to Fig. 5 to Fig. 9. Here, the case will be described where the image forming unit 5 is a four-color printing machine that uses inks of the colors black (K), cyan (C), magenta (M), and yellow (Y).

[0050] FIG. 5 shows the inspection image group of the first pattern. As shown in FIG. 5, the inspection image group of the first pattern includes four inspection images Im11 to Im14 formed by dividing four sheets Sh11 to Sh14. Each of the inspection images Im11 to Im14 is divided into four in the main scanning direction D11, and four color images are arranged in the four divided areas. The inspection image Im11 formed on the first sheet Sh11 is arranged in the order of C, M, Y, and K from the left, and the inspection image Im12 formed on the second sheet Sh12 is arranged in the order of K, C, M, and Y from the left. The inspection image Im13 formed on the third sheet Sh13 is arranged in the order of Y, K, C, and M from the left, and the inspection image Im14 formed on the fourth sheet Sh14 is arranged in the order of M, Y, K, and C from the left.

[0051] The inspection processing unit 71 repeatedly forms these four inspection images Im11 to Im14 for each of the four sheets Sh11 to Sh14. The inspection image group of the first pattern is an ideal case in which the number of ink colors matches the number of inspection images Im1 that constitute the inspection image group.

[0052] Fig. 6 shows the inspection image group of the second pattern. As shown in Fig. 6, the inspection image group of the second pattern includes four inspection images Im11-Im14 formed by dividing four sheets Sh11-Sh14. The four inspection images Im11-Im14 are images of the colors C, M, Y, and K, respectively. The inspection image Im11 formed on the first sheet Sh11 is C, the inspection image Im12 formed on the second sheet Sh12 is M, the inspection image Im13 formed on the third sheet Sh13 is Y, and the inspection image Im14 formed on the fourth sheet Sh14 is K.

[0053] The inspection processing unit 71 repeatedly forms these four inspection images Im11 to Im14 for each of the four sheets Sh11 to Sh14. In the second pattern inspection image group, an inspection image Im1 of one color is formed for each sheet Sh1.

[0054] FIG. 7 shows the inspection image group of the third pattern. As shown in FIG. 7, the inspection image group of the third pattern includes two inspection images Im11-Im12 formed by dividing two sheets Sh11-Sh12. Each of the inspection images Im11-Im12 is divided into four in the main scanning direction D11, and images of different colors are arranged in two rows in the sub-scanning direction D12. The inspection image Im11 formed on the first sheet Sh11 is arranged in the order of C, M, C, M from the left in the first row, and K, Y, K, Y from the left in the second row. The inspection image Im12 formed on the second sheet Sh12 is arranged in the order of M, C, M, C from the left in the first row, and Y, K, Y, K from the left in the second row.

[0055] The inspection processing unit 71 repeatedly forms these two inspection images Im11-Im12 for each of two sheets Sh11-Sh12. In the inspection image group of the third pattern, the number of inspection images Im1 constituting the inspection image group is half the number of ink colors.

[0056] FIG. 8 shows the inspection image group of the fourth pattern. As shown in FIG. 8, the inspection image group of the fourth pattern includes three inspection images Im11 to Im13 formed by dividing three sheets Sh11 to Sh13. Each of the inspection images Im11 to Im13 is divided into three in the main scanning direction D11, and images of different colors are arranged in two rows in the sub-scanning direction D12. In the inspection image Im11 formed on the first sheet Sh11, the first row is arranged in the order of C, M, and Y from the left, and K is arranged at the left end of the second row. In the inspection image Im12 formed on the second sheet Sh12, the first row is arranged in the order of Y, C, and M from the left, and K is arranged in the middle of the second row. In the inspection image Im13 formed on the third sheet Sh13, the first row is arranged in the order of M, Y, and C from the left, and K is arranged at the right end of the second row.

[0057] The inspection processing unit 71 repeatedly forms these three inspection images Im11 to Im13 for each of the three sheets Sh11 to Sh13. In the inspection image group of the fourth pattern, the number of inspection images Im1 constituting the inspection image group is less than the number of ink colors.

[0058] FIG. 9 shows the fifth pattern of the inspection image group. As shown in FIG. 9, the fifth pattern of the inspection image group includes three inspection images Im11 to Im13 formed by dividing three sheets Sh11 to Sh13. Each of the inspection images Im11 to Im13 is divided into three in the main scanning direction D11, and images of different colors are arranged in two rows in the sub-scanning direction D12. In the inspection image Im11 formed on the first sheet Sh11, the first row is arranged in the order of C, M, and Y from the left, and K is arranged in the second row. In the inspection image Im12 formed on the second sheet Sh12, the first row is arranged in the order of Y, C, and M from the left, and K is arranged in the second row. In the inspection image Im13 formed on the third sheet Sh13, the first row is arranged in the order of M, Y, and C from the left, and K is arranged in the second row.

[0059] The inspection processing unit 71 repeatedly forms these three inspection images Im11-Im13 for each of the three sheets Sh11-Sh13. In the inspection image group of the fifth pattern, the number of inspection images Im1 constituting the inspection image group is less than the number of ink colors. In this case, for the most frequently used color (e.g., K), it is possible to inspect all ink nozzles 53 on all of the three sheets Sh11-Sh13.

[0060] In the image forming apparatus 10 according to the present embodiment, for example, like the above-mentioned first to fifth patterns, the number of inspection images Im1 included in the inspection image group can be set appropriately. That is, the inspection processing unit 71 can change the number of inspection images Im1 included in the inspection image group. Therefore, for example, depending on the purpose or frequency of use of the image forming apparatus 10, it is possible to set so that the inspection of a predetermined number of recording elements is completed with an appropriate number of sheets Sh1.

[0061] [3] Image forming method Hereinafter, an image forming method executed by the inspection processing unit 71 in the image forming apparatus 10 having the above-described configuration will be described with reference to the flowchart in Fig. 10. Here, steps S1, S2, etc. indicate the numbers of the processing procedures (steps) executed by the inspection processing unit 71.

[0062] <Steps S1 and S2> First, in step S1, the inspection processing unit 71 forms an inspection image Im1 on a first sheet Sh1 by controlling the image forming unit 5. In the next step S2, the inspection processing unit 71 controls the image reading unit 8 to read the inspection image Im1 from the first sheet Sh1.

[0063] <Step S3> In step S3, the inspection processing unit 71 determines whether the number of sheets Sh1 from which the inspection images Im1 were read in step S2 (the number of read sheets) has reached a predetermined number N. Here, the predetermined number N is the number of inspection images Im1 included in the inspection image group, and for example, in the inspection image group of the first pattern, N=4. Then, when the number of read sheets reaches the predetermined number N (S3: Yes), the inspection processing unit 71 shifts the process to step S4. On the other hand, when the number of read sheets has not reached the predetermined number N (S3: No), the inspection processing unit 71 returns the process to step S1.

[0064] <Steps S4 and S5> In step S4, the inspection processing unit 71 performs inspection on the inspection images Im1 for a predetermined number N. After that, in step S5, the inspection processing unit 71 resets the number of read sheets (to "0"), and the process returns to step S1.

[0065] The procedure of the image forming method described above is merely an example, and the order of the processes shown in the flowchart of FIG. 10 may be changed as appropriate, and processes may be added or omitted as appropriate.

[0066] [4] Variations A plurality of components included in the image forming apparatus 10 may be provided in a distributed manner in a plurality of housings. For example, the image forming unit 5 and the ink supply unit 6 may be provided in separate housings.

[0067] Conversely, in the first embodiment, at least one of the components provided separately from the image forming apparatus 10 may be provided in the image forming apparatus 10 as a component of the image forming apparatus 10. For example, at least one of the paper feeder 11, the dryer 12, and the discharger 13 may be provided in the housing 21, or the like, and may be configured integrally with the image forming apparatus 10.

[0068] Furthermore, the image forming target on which the image is formed by the image forming apparatus 10 is not limited to a sheet Sh1 such as paper or a resin film, but may be, for example, a roll of fabric such as a nonwoven fabric or cloth. In this case, the image forming apparatus 10 is a textile printing machine (textile printer) that ejects ink onto the fabric and dyes the fibers of the fabric with the ink, thereby recording an image on the fabric.

[0069] Furthermore, the "recording element" is not limited to the ink nozzle 53, but may be, for example, the recording head 51 or the line head 50. Furthermore, if the image forming apparatus 10 is of a type other than the inkjet type, the recording element is changed as appropriate depending on the type of the image forming apparatus 10, etc.

[0070] (Embodiment 2) 11 to 13, the image forming apparatus 10 according to this embodiment differs from the image forming apparatus 10 according to the first embodiment in that it is adapted to accommodate changes in attributes of sheets Sh1 during the process of forming images on the sheets Sh1. Hereinafter, the same components as those in the first embodiment will be denoted by the same reference numerals and descriptions thereof will be omitted as appropriate.

[0071] The attributes of the sheet Sh1 here include, for example, the size (paper size) and orientation of the sheet Sh1. In this embodiment, as an example, it is assumed that the size of the sheet Sh1 is changed midway. In addition, in this embodiment, the inspection processing unit 71 performs a divided inspection according to the inspection image group of the first pattern.

[0072] For example, as shown in FIG. 11, assume that when images are formed on sheets Sh11-Sh15, the sheets Sh11-Sh12 are changed from "A4 portrait" to "A3 portrait" sheets Sh13-Sh15. In this case, for sheets Sh11-Sh12, the inspection processing unit 71 sequentially forms inspection images Im11-Im12 according to the inspection image group of the first pattern. Then, when the attribute (size) of sheet Sh1 is changed, the inspection processing unit 71 temporarily suspends the division inspection, and performs a full inspection using all of the predetermined number of ink nozzles 53 on the top sheet Sh13 after the size change. In other words, the inspection image Im13 formed on sheet Sh13 is an image that uses all of the multiple ink nozzles 53 of C, M, Y, and K.

[0073] Then, for the second and subsequent sheets Sh14-Sh15 after the size change, the inspection processing unit 71 resumes the division inspection by sequentially forming inspection images Im14-Im15 in accordance with the inspection image group of the first pattern. Here, the inspection images Im14-Im15 formed on the sheets Sh14-Sh15 are images expanded to fit the width of the "A3 portrait" sheets Sh14-Sh15 compared to the inspection images Im11-Im12.

[0074] That is, in the image forming apparatus 10 according to the present embodiment, the inspection processing unit 71 changes the state of the inspection image Im1 in synchronization with the timing of the change in the attribute of the sheet Sh1. This makes it possible to perform an appropriate inspection process suited to the sheet Sh1 without deteriorating the inspection quality even when the attribute of the sheet Sh1 is changed.

[0075] In particular, in this embodiment, for the first sheet Sh1 after the attribute change, the inspection processing unit 71 performs a full inspection using all of the multiple recording elements (ink nozzles 53) to form a single inspection image Im1 on one sheet Sh1. This makes it possible to guarantee the operating state of all of a predetermined number of recording elements at the timing when the attribute of the sheet Sh1 changes. Moreover, compared to performing a full inspection on all sheets Sh1, this has the advantage that it is easier to shorten the time required to form the inspection image Im1 on one sheet Sh1 and easier to reduce the consumption of consumables (ink).

[0076] As another example, the inspection processing unit 71 may adopt a configuration in which the entire inspection is not performed when the attribute of the sheet Sh1 is changed, as shown in FIG. 12. In the example of FIG. 12, the inspection processing unit 71 sequentially forms inspection images Im11 to Im12 for the sheets Sh11 to Sh12 according to the inspection image group of the first pattern. Then, when the attribute (size) of the sheet Sh1 is changed, the inspection processing unit 71 forms an inspection image Im13 as exemplified in FIG. 12 for the top sheet Sh13 after the size is changed. The inspection image Im13 includes an image using all of the multiple ink nozzles 53 of C, M, Y, and K only for the area of ​​the sheet Sh13 that cannot be inspected by the sheets Sh11 to Sh12 of the size before the change. Here, the inspection image Im13 forms an image in which Y, K, C, and M are arranged in this order from the left according to the inspection image group of the first pattern for the area that has already been inspected by the sheets Sh11 to Sh12 of the size before the change.

[0077] Then, for the second and subsequent sheets Sh14-Sh15 after the resizing, the inspection processing unit 71 sequentially forms inspection images Im14-Im15 according to the inspection image group of the first pattern. Here, the inspection images Im14-Im15 formed on the sheets Sh14-Sh15 are images expanded to fit the width of the "A3 portrait" sheets Sh14-Sh15, compared to the inspection images Im11-Im12. In short, in the example of Fig. 12, the inspection processing unit 71 continuously performs division inspection on both the sheets Sh11-Sh15 before and after the resizing.

[0078] 13, when the size of the sheet Sh1 is reduced, the inspection processing unit 71 may simply continue the division inspection without inserting any special processing. For example, as shown in FIG. 13, when forming images on the sheets Sh11 to Sh14, a case is assumed in which the sheets Sh11 to Sh12 are changed from "A3 portrait" to "A4 portrait" sheets Sh13 to Sh14. In this case, for the sheets Sh11 to Sh12, the inspection processing unit 71 sequentially forms the inspection images Im11 to Im12 according to the inspection image group of the first pattern. Then, when the attribute (size) of the sheet Sh1 is changed, the inspection processing unit 71 sequentially forms the inspection images Im13 to Im14 on the sheets Sh13 to Sh14 after the size change according to the inspection image group of the first pattern. However, the inspection images Im13 to Im14 formed on the sheets Sh13 to Sh14 are images reduced in size to fit the width of the "A4 portrait" sheets Sh13 to Sh14, as compared with the inspection images Im11 to Im12.

[0079] Here, the case where the attribute of the sheet Sh1 is changed between the "A3 portrait" sheet Sh1 and the "A4 portrait" sheet Sh1 is illustrated, but the same applies to the attributes of the other sheets Sh1.

[0080] (Embodiment 3) In the image forming system 100 according to this embodiment (one example of the image forming apparatus of the present invention), the sheet feeding device 11, the sheet conveying device 4 of the image forming apparatus 10, the drying device 12, and the discharge device 13 function as a sheet conveying section that conveys the sheet Sh1 along a conveying path K1 (see FIG. 14) that passes through the image forming section 5 and reaches the first discharge section 14 (see FIG. 14) that is the discharge destination of the sheet Sh1. For example, the first discharge section 14 is a paper discharge tray. Also, in the image forming system 100 according to this embodiment, the processing contents of the inspection processing section 71 are different from those of the image forming apparatus 10 according to the first embodiment. Hereinafter, the same configurations as those in the first embodiment will be denoted by the same reference numerals and the description thereof will be omitted as appropriate.

[0081] In the division process of this embodiment, each of the inspection images Im1 included in the inspection image group is formed periodically. Also, in the division process of this embodiment, as shown in FIG. 15, any one of the inspection images Im1 is formed every time an image (page image) is formed in the document area R1 of the sheet Sh1. That is, in the division process of this embodiment, the multiple inspection images Im1 included in the inspection image group are formed in order at the image formation intervals for the document area R1 of the sheet Sh1 by the image forming unit 5. For example, when the number of inspection images Im1 included in the inspection image group is four, as shown in FIG. 15, the four inspection images Im11 to Im14 are formed in the order of inspection image Im11, inspection image Im12, inspection image Im13, inspection image Im14, inspection image Im11, ... at the image formation intervals for the document area R1 of the sheet Sh1 by the image forming unit 5. Note that FIG. 15 illustrates a case where the division inspection is performed according to the inspection image group of the second pattern.

[0082] Furthermore, the inspection processing unit 71 of this embodiment inspects the read inspection image Im1 every time the image reading unit 8 reads an inspection image Im1 included in the inspection image group. If the inspection processing unit 71 determines that the inspection image Im1 is defective, it notifies the inspection processing unit 71 of the defect and identifiably discharges a specific sheet including a sheet surface on which an image is to be formed next to the sheet surface including the inspection image Im1 one cycle before the inspection image Im1 determined to be defective. The sheet surface may include only the front surface of the sheet, or may include both the front and back surfaces of the sheet.

[0083] Specifically, at the timing when the specific sheet is discharged to the first discharge unit 14, the inspection processing unit 71 notifies the user that the inspection image Im1 is determined to be defective.

[0084] For example, as shown in Fig. 15, in the case where page images from page 1 to page 8 are formed in sequence, it is assumed that the inspection image Im13 formed together with the page image of page 7 includes a defective image Er1 such as a white streak. In this case, the inspection processing unit 71 determines that the sheet Sh1 including the sheet surface on which an image is formed next to the sheet surface including the inspection image Im13 (inspection image Im13 formed together with the page image of page 3) one cycle before the inspection image Im13 including the defective image Er1 is the specific sheet. In other words, the inspection processing unit 71 determines that no operational malfunction occurred in the image forming unit 5 when the inspection image Im13 one cycle before the inspection image Im13 including the defective image Er1 was formed, but that there is a possibility that an operational malfunction occurred in the image forming unit 5 when the image of the next page was formed, and discharges the specific sheet that may include a defective image in an identifiable manner.

[0085] In addition, the inspection processing unit 71 of this embodiment sets the number of inspection images Im1 included in the inspection image group based on the number of undeleted sheets Sh1 that are present in the section downstream of the sheet Sh1 containing the inspection image Im1 to be inspected on the transport path K1 when inspecting the inspection image Im1.

[0086] For example, in the image forming system 100, assume that the number of undischarged sheets Sh1 (Sh22) present in the section downstream of the sheet Sh1 (Sh21) containing the inspection image Im1 to be inspected in the transport path K1 during inspection of the inspection image Im1 is three (see FIG. 14). In this case, the inspection processing unit 71 adds "1" to the number of undischarged sheets Sh1 (Sh22) and sets the number of inspection images Im1 included in the inspection image group to "4". As a result, as shown in FIG. 15, when it is determined that the inspection image Im13 formed on the sheet Sh21 is defective, it is possible to set the specific sheet (sheet Sh22 on which the page image of the fourth page is formed) to an undischarged state. In addition, in the image forming system 100, when inspecting the inspection image Im1, the number of undischarged sheets Sh1 present in the section downstream of the sheet Sh1 containing the inspection image Im1 to be inspected on the transport path K1 can be determined based on the length of the section, the size of the sheet Sh1 to be transported, and the paper spacing of the sheets Sh1 during transport.

[0087] In addition, the inspection processing unit 71 may set the number of inspection images Im1 included in the inspection image group to a number equal to or less than the number of unejected sheets Sh1 present in the section downstream of the sheet Sh1 containing the inspection image Im1 to be inspected on the transport path K1 when inspecting the inspection image Im1.

[0088] Hereinafter, an image forming method executed by the inspection processing unit 71 in the image forming system 100 having the above-described configuration will be described with reference to the flowchart of FIG.

[0089] <Steps S11 and S12> First, in step S11, the inspection processing unit 71 forms an inspection image Im1 on the first sheet Sh1 by controlling the image forming unit 5. In the next step S12, the inspection processing unit 71 controls the image reading unit 8 to read the inspection image Im1 from the first sheet Sh1.

[0090] <Step S13> In step S13, the inspection processing unit 71 performs an inspection on the inspection image Im1 read in step S12.

[0091] <Step S14> In step S14, the inspection processing unit 71 determines whether or not a defect was detected in the inspection performed in step S13. If it is determined that a defect was detected (S14: Yes), the inspection processing unit 71 shifts the process to step S15. On the other hand, if no defect was detected (S14: No), the inspection processing unit 71 shifts the process to step S16.

[0092] <Step S15> In step S15, the inspection processing unit 71 notifies the user that the inspection image Im1 has been determined to be defective, and identifiably ejects the specific sheet including the sheet surface on which an image is to be formed next to the sheet surface including the inspection image Im1 one cycle before the inspection image Im1 determined to be defective.

[0093] Specifically, the inspection processing unit 71 notifies the user at the timing when the specific sheet is discharged that the inspection image Im1 has been determined to be defective, that is, that a malfunction has occurred in the image forming unit 5. For example, the inspection processing unit 71 causes the operation display unit of the image forming apparatus 10 to display a message indicating that a malfunction has occurred in the image forming unit 5. This enables the user of the image forming system 100 to easily identify the first sheet Sh1 that may include a defective image.

[0094] <Step S16> In step S16, the inspection processing unit 71 determines whether the number of sheets Sh1 from which the inspection images Im1 were read in step S12 (the number of read sheets) has reached a predetermined number N. If the number of read sheets reaches the predetermined number N (S16: Yes), the inspection processing unit 71 shifts the process to step S17. On the other hand, if the number of read sheets has not reached the predetermined number N (S16: No), the inspection processing unit 71 returns the process to step S11.

[0095] <Step S17> In step S17, the inspection processing unit 71 resets the number of read sheets (to "0"), and returns the process to step S11. The processes in steps S11 to S17 are an example of the inspection step of the present invention.

[0096] The inspection processing unit 71 may set the number of inspection images Im1 included in the inspection image group in response to a predetermined user operation. That is, the number of inspection images Im1 included in the inspection image group may be arbitrarily set by the user.

[0097] In this case, the inspection processing unit 71 may notify the user when the number of inspection images Im1 included in the inspection image group set by the user's operation exceeds a first specific number based on the number of undischarged sheets Sh1 present in the section downstream of the sheet Sh1 containing the inspection image Im1 to be inspected on the transport path K1 at the time of inspection of the inspection image Im1. The first specific number is a number obtained by adding "1" to the number of undischarged sheets Sh1 present in the section downstream of the sheet Sh1 containing the inspection image Im1 to be inspected on the transport path K1 at the time of inspection of the inspection image Im1. This makes it possible to notify the user that the image forming unit 5 will not be able to notify the user that a malfunction has occurred at the timing of ejection of the first sheet Sh1 that may contain a defective image.

[0098] (Embodiment 4) As shown in Fig. 17, the image forming system 100 according to this embodiment differs from the image forming system 100 according to the third embodiment in that it includes a second discharge section 15 in addition to a first discharge section 14. For example, the second discharge section 15 is a paper discharge tray. Also, in the image forming system 100 according to this embodiment, the processing contents of the inspection processing section 71 differ from those of the image forming system 100 according to the third embodiment. Hereinafter, the same components as those in the third embodiment will be denoted by the same reference numerals and the description thereof will be omitted as appropriate.

[0099] In this embodiment, the inspection processing unit 71 switches the discharge destination of the sheet Sh1 after the specific sheet from the first discharge section 14 to the second discharge section 15, instead of notifying that the inspection image Im1 has been determined to be defective at the time the specific sheet is discharged.

[0100] In addition, the inspection processing unit 71 of this embodiment sets the number of inspection images Im1 included in the inspection image group based on the number of undischarged sheets Sh1 that are present in the section of the transport path K1 downstream of the sheet Sh1 containing the inspection image Im1 to be inspected, up to the branching position P1 (see Figure 17) between the transport path leading to the first discharge section 14 and the transport path leading to the second discharge section 15, when inspecting the inspection image Im1.

[0101] For example, in the image forming system 100, it is assumed that the number of undischarged sheets Sh1 (Sh22) existing in the section from the downstream side of the sheet Sh1 (Sh21) including the inspection image Im1 to the branch position P1 on the conveying path K1 during inspection of the inspection image Im1 is two (see FIG. 17). In this case, the inspection processing unit 71 sets the number of inspection images Im1 included in the inspection image group to "3", which is the number of undischarged sheets Sh1 (Sh22) plus "1". This makes it possible to switch the discharge destination of the specific sheet when it is determined that the inspection image Im1 formed on the sheet Sh21 is defective. Note that, in the image forming system 100, the number of undischarged sheets Sh1 existing in the section from the downstream side of the sheet Sh1 including the inspection image Im1 to the branch position P1 during inspection of the inspection image Im1 can be determined based on the length of the section, the size of the sheet Sh1 to be conveyed, and the paper interval of the sheets Sh1 during conveyance.

[0102] The inspection processing unit 71 may set the number of inspection images Im1 included in the inspection image group in response to a predetermined user operation.

[0103] In this case, the inspection processing unit 71 may notify the user when the number of inspection images Im1 included in the inspection image group set by the user's operation exceeds a second specific number based on the number of unejected sheets Sh1 present in the section from the downstream side of the sheet Sh1 including the inspection image Im1 to the branch position P1 on the transport path K1 at the time of inspection of the inspection image Im1. The second specific number is a number obtained by adding "1" to the number of unejected sheets Sh1 present in the section from the downstream side of the sheet Sh1 including the inspection image Im1 to the branch position P1 on the transport path K1 at the time of inspection of the inspection image Im1. This makes it possible to notify the user that it will be impossible to distinguish and eject sheets Sh1 after the first sheet Sh1 that may include a defective image. [Explanation of symbols]

[0104] 4 Sheet transport device 5. Image forming section 8 Image reading unit 10 Image forming device 53 Ink nozzle (recording element) 71 Inspection processing section D1 Transport direction R2 Margin area Sh1 sheet Im1 Inspection image

Claims

1. an image forming unit that forms an image on a sheet using a plurality of recording elements; a sheet conveying section that conveys the sheet along a conveying path that passes through the image forming section and reaches a discharge destination of the sheet; an image reading unit disposed downstream of the image forming unit on the conveying path and configured to read an image on the sheet; an inspection processing unit that causes the image forming unit to form an inspection image in a margin area of ​​the sheet and causes the image reading unit to read the inspection image; The inspection processing unit is capable of performing a divided inspection in which only a part of the plurality of recording elements is used to form a single inspection image formed on one of the sheets, and all of the plurality of recording elements are used to form an inspection image group consisting of a plurality of the inspection images formed on a plurality of the sheets, In the divided inspection, each of the inspection images included in the inspection image group is formed periodically, the inspection processing unit inspects the inspection image each time the inspection image included in the inspection image group is read by the image reading unit, and if the inspection image is determined to be defective, notifies the user of the defect and identifiably discharges a specific sheet including a sheet surface on which an image is to be formed next to a sheet surface including the inspection image one cycle before the inspection image determined to be defective. Image forming device.

2. the inspection processing unit notifies a user that the inspection image is determined to be defective at a timing when the specific sheet is discharged. The image forming apparatus according to claim 1 .

3. the inspection processing unit sets the number of the inspection images included in the inspection image group based on the number of the undischarged sheets present downstream of the sheet including the inspection image to be inspected on the transport path when inspecting the inspection images. The image forming apparatus according to claim 2 .

4. the inspection processing unit notifies a user when the number of the inspection images included in the inspection image group set by a user operation exceeds a first specific number based on the number of the undischarged sheets present downstream of the sheet including the inspection image to be inspected on the transport path during inspection of the inspection images.

4. The image forming apparatus according to claim 2 or 3.

5. the inspection processing unit switches a discharge destination of the sheets after the specific sheet from a first discharge unit to a second discharge unit. The image forming apparatus according to claim 1 .

6. the inspection processing unit sets the number of the inspection images included in the inspection image group based on the number of the undischarged sheets present in a section of the transport path downstream of the sheet including the inspection image to be inspected and up to a branch position of the transport path leading to the first discharge unit and the transport path leading to the second discharge unit when inspecting the inspection images. The image forming apparatus according to claim 5 .

7. the inspection processing unit notifies a user when the number of the inspection images included in the inspection image group set by a user operation exceeds a second specific number based on the number of the undischarged sheets present in a section of the transport path downstream of the sheet including the inspection image to be inspected and up to a branch position of the transport path leading to the first discharge unit and the transport path leading to the second discharge unit at the time of inspection of the inspection images.

7. The image forming apparatus according to claim 5 or 6.

8. An image forming method executed by an image forming apparatus including: an image forming unit that forms an image on a sheet by a plurality of recording elements; a sheet transport unit that transports the sheet along a transport path that passes through the image forming unit and reaches a destination of the sheet; and an image reading unit that is disposed downstream of the image forming unit on the transport path and reads the image on the sheet, an inspection step of causing the image forming unit to form an inspection image in a margin area of ​​the sheet and causing the image reading unit to read the inspection image; In the inspection step, a divided inspection is performed in which only a part of the plurality of recording elements is used to form a single inspection image formed on one of the sheets, and all of the plurality of recording elements are used to form an inspection image group consisting of a plurality of the inspection images formed on a plurality of the sheets; In the divided inspection, each of the inspection images included in the inspection image group is formed periodically, In the inspection step, each time the image reading unit reads an inspection image included in the inspection image group, the inspection image is inspected, and if the inspection image is determined to be defective, a notification to that effect is issued, and a specific sheet including a sheet surface on which an image is to be formed next to the sheet surface including the inspection image one cycle before the inspection image determined to be defective is identifiably discharged. Image forming method.

9. An image forming program for causing one or more processors to execute the image forming method according to claim 8.

Images