Image forming apparatus and inkjet head.

Abstract

To provide an image forming device and an inkjet head which can suppress occurrence of an image defect caused by poor discharging of ink.SOLUTION: An image forming device comprises an inkjet head having nozzles for discharging ink arranged along a plurality of rows and a head unit having the inkjet head. The inkjet head is mounted on the head unit, in a mounting direction in accordance with inspected results of discharging states of ink for the nozzles.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus and an inkjet head. [Background technology]

[0002] Conventionally, there is an inkjet image forming apparatus that forms an image on a recording medium conveyed by a conveying device by ejecting ink from the nozzle openings of a plurality of nozzles arranged in an inkjet head. In this inkjet image forming apparatus, ink ejection defects (also called nozzle failure) can occur, such as when the amount of ink ejected from the nozzle openings decreases from the initial value due to clogging of the nozzles or the ink is not ejected at all, or the ink ejection direction changes.

[0003] In inkjet image forming devices, such ink ejection defects lead to a decline in the quality of images formed. Therefore, conventionally, inkjet image forming devices periodically inspect the ink ejection status from the nozzle openings. One method for inspecting the ink ejection status involves capturing an image of a test image formed on a recording medium and analyzing the captured image data. This method involves ejecting ink from each nozzle opening individually, checking the presence or absence of ink ejection and the ink density, thereby determining whether or not ink ejection from each nozzle opening is defective.

[0004] Patent Document 1 describes an image forming apparatus that suppresses image degradation caused by abnormal ejection nozzles. The technology described in Patent Document 1 reads and analyzes a check pattern printed by a droplet ejection head, and sorts the multiple nozzles provided in the droplet ejection head into normal ejection nozzles and abnormal ejection nozzles based on the droplet landing region and landing area. The abnormal ejection nozzle is then disabled to prohibit droplet ejection, and the input image dot data is corrected so that the area where the abnormal ejection nozzle should have ejected is filled in by normal nozzles surrounding the abnormal ejection nozzle. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-129112 Summary of the Invention [Problem to be solved by the invention]

[0006] However, when nozzles are arranged in multiple nozzle rows in an inkjet head, depending on the position in the recording medium transport direction of the row in which the nozzle with the ink ejection defect is located, there is a problem that the nozzles surrounding the nozzle with the ink ejection defect (normal nozzles that are not experiencing the ink ejection defect) may not be able to compensate sufficiently for the nozzle with the ink ejection defect, resulting in a defective image.

[0007] SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus and an inkjet head that are capable of suppressing the occurrence of image defects due to ink ejection defects. [Means for solving the problem]

[0008] The image forming apparatus according to the present invention comprises: an inkjet head in which nozzles for ejecting ink are arranged in a plurality of nozzle rows; a head unit having the inkjet head; a control unit that controls the inkjet head so as to form an image on a recording medium with the ink; Equipped with The inkjet head is configured to inspect the state of ink ejection from the nozzles. Based on this, the nozzle row including the defective nozzle is arranged on the upstream side in the conveying direction of the recording medium, and the nozzle row not including the defective nozzle is arranged on the downstream side in the conveying direction. It is attached to the head unit in an attachment direction. The image forming apparatus according to the present invention comprises: an inkjet head in which nozzles for ejecting ink are arranged in a plurality of nozzle rows; a head unit having the inkjet head; a control unit that controls the inkjet head so as to form an image on a recording medium with the ink; a display unit that displays information; Equipped with the inkjet head has a first storage unit that stores mounting direction information indicating a mounting direction according to an inspection result of an ink ejection state of the nozzles, the display unit displays the mounting direction information stored in the first storage unit, The inkjet head is attached to the head unit in the attachment direction. The image forming apparatus according to the present invention comprises: an inkjet head in which nozzles for ejecting ink are arranged in a plurality of nozzle rows; a head unit having the inkjet head; a control unit that controls the inkjet head so as to form an image on a recording medium with the ink; an acquisition unit that acquires information stored in a second storage unit of the external device; a display unit that displays the information acquired by the acquisition unit; Equipped with Identification information for identifying the inkjet head is attached to the inkjet head or an attachment of the inkjet head, mounting direction information indicating a mounting direction according to an inspection result of the ink ejection state for the nozzles is stored in the second storage unit in association with the identification information; the acquisition unit acquires the mounting direction information stored in the second storage unit, the display unit displays the mounting direction information acquired by the acquisition unit, The inkjet head is attached to the head unit in the attachment direction. The image forming apparatus according to the present invention comprises: an inkjet head in which nozzles for ejecting ink are arranged in a plurality of nozzle rows; a head unit having the inkjet head; a control unit that controls the inkjet head so as to form an image on a recording medium with the ink; an acquisition unit that acquires information stored in a second storage unit of the external device; a display unit that displays the information acquired by the acquisition unit; Equipped with the inkjet head has a first storage unit that stores identification information for identifying the inkjet head; installation direction information indicating an installation direction according to an inspection result of the ink ejection state for the nozzles is stored in a second storage unit of the external device in association with the identification information; the acquisition unit acquires the attachment direction information stored in the second storage unit based on the identification information stored in the first storage unit; the display unit displays the mounting direction information acquired by the acquisition unit, The inkjet head is attached to the head unit in the attachment direction.

[0009] The inkjet head according to the present invention comprises: An inkjet head that is attached to a head unit of an image forming apparatus in an attachment direction according to an inspection result of an ink ejection state of the nozzles, A second restricting portion is provided to restrict the mounting direction of the inkjet head relative to the head unit. The inkjet head according to the present invention comprises: picture Attached to the head unit of the image forming device , nozzles that eject ink are arranged in a plurality of nozzle rows. An inkjet head, The aforementioned For head unit Mounting direction information indicating the mounting direction is attached to the inkjet head or an accessory of the inkjet head. R, The mounting direction information is information that indicates a mounting direction in which a nozzle row including a defective nozzle is arranged on the upstream side in the transport direction of the recording medium, and a nozzle row that does not include a defective nozzle is arranged on the downstream side in the transport direction, based on the inspection result of the ink ejection state of the nozzles. . The inkjet head according to the present invention comprises: picture Attached to the head unit of the image forming device , nozzles that eject ink are arranged in a plurality of nozzle rows. An inkjet head, The aforementioned For head unit A first storage unit is provided for storing attachment direction information indicating the attachment direction. picture, The mounting direction information is information that indicates a mounting direction in which a nozzle row including a defective nozzle is arranged on the upstream side in the transport direction of the recording medium, and a nozzle row that does not include a defective nozzle is arranged on the downstream side in the transport direction, based on the inspection result of the ink ejection state of the nozzles. . The inkjet head according to the present invention comprises: picture Attached to the head unit of the image forming device , nozzles that eject ink are arranged in a plurality of nozzle rows. An inkjet head, Identification information for identifying the inkjet head is attached to the inkjet head or an attachment of the inkjet head, The aforementioned For head unit Mounting direction information indicating the mounting direction is stored in association with the identification information in a second storage unit of the external device. R, The mounting direction information is information that indicates a mounting direction in which a nozzle row including a defective nozzle is arranged on the upstream side in the transport direction of the recording medium, and a nozzle row that does not include a defective nozzle is arranged on the downstream side in the transport direction, based on the inspection result of the ink ejection state of the nozzles. . The inkjet head according to the present invention comprises: picture Attached to the head unit of the image forming device , nozzles that eject ink are arranged in a plurality of nozzle rows. An inkjet head, a first storage unit for storing identification information for identifying the inkjet head; picture, Mounting direction information indicating a mounting direction with respect to the head unit is stored in a second storage unit of the external device in association with the identification information; The mounting direction information is information that indicates a mounting direction in which a nozzle row including a defective nozzle is arranged on the upstream side in the transport direction of the recording medium, and a nozzle row that does not include a defective nozzle is arranged on the downstream side in the transport direction, based on the inspection result of the ink ejection state of the nozzles. . [Effects of the Invention]

[0010] According to the present invention, it is possible to suppress the occurrence of image defects due to ink ejection defects. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram illustrating a schematic configuration of an inkjet image forming apparatus. [Figure 2] FIG. 2 is a schematic diagram illustrating the configuration of a head unit. [Figure 3] FIG. 2 is a schematic cross-sectional view illustrating the configuration of an image reading unit. [Figure 4] 1 is a block diagram showing a main functional configuration of an inkjet image forming apparatus; [Figure 5] FIG. 10 is a diagram showing an example of a test chart used to detect defective nozzles. [Figure 6] 10 is a flowchart illustrating an example of a defective nozzle detection process according to the present embodiment. [Figure 7] FIG. 1 is a diagram illustrating a problem with the prior art. [Figure 8] 3A and 3B are diagrams illustrating a manner in which an inkjet head is attached to a head unit. DETAILED DESCRIPTION OF THE INVENTION

[0012] The present embodiment will be described below with reference to the drawings.

[0013] 1 is a diagram showing a schematic configuration of an inkjet image forming apparatus 1. The inkjet image forming apparatus 1 (functioning as the "image forming apparatus" of the present invention) includes a paper feed unit 10, an image forming unit 20, a paper discharge unit 30, and a control unit 40 (see FIG. 4).

[0014] Under the control of the control unit 40, the inkjet image forming apparatus 1 transports the recording medium P stored in the paper feed unit 10 to the image forming unit 20, where an image is formed on the recording medium P, and transports the recording medium P with the image formed to the paper discharge unit 30. As the recording medium P, various media can be used, such as paper such as plain paper or coated paper, as well as fabric or sheet-like resin, on whose surface the ink that has landed can be fixed.

[0015] The paper feed unit 10 has a paper feed tray 11 that stores the recording medium P, and a medium supply unit 12 that transports and supplies the recording medium P from the paper feed tray 11 to the image forming unit 20. The medium supply unit 12 has a ring-shaped belt supported on the inside by two rollers, and transports the recording medium P from the paper feed tray 11 to the image forming unit 20 by rotating the rollers with the recording medium P placed on this belt.

[0016] The image forming section 20 includes a conveying section 21, a delivery unit 22, a heating section 23, a head unit 24, a fixing section 25, an image reading section 26, a delivery section 28, a rotary encoder 29, and the like.

[0017] The transport unit 21 holds the recording medium P placed on the transport surface 211a (mounting surface) of a cylindrical transport drum 211, and performs a transport operation of transporting the recording medium P on the transport drum 211 in the transport direction (Y direction) by the transport drum 211 rotating and moving around a rotation axis (cylindrical axis) extending in the X direction. The transport drum 211 is equipped with claws and an air intake unit (not shown) for holding the recording medium P on the transport surface 211a. The recording medium P is held on the transport surface 211a by having its edges pressed by the claws and being drawn to the transport surface 211a by the air intake unit. The transport unit 21 is connected to a transport drum motor (not shown) for rotating the transport drum 211. The transport drum 211 rotates by an angle proportional to the amount of rotation of the transport drum motor.

[0018] The transfer unit 22 transfers the recording medium P transported by the medium supply unit 12 of the paper feed unit 10 to the transport unit 21. The transfer unit 22 is provided at a position between the medium supply unit 12 of the paper feed unit 10 and the transport unit 21, and holds and picks up one end of the recording medium P transported from the medium supply unit 12 with a swing arm unit 221, and transfers it to the transport unit 21 via a transfer drum 222.

[0019] The heating unit 23 is provided between the position where the delivery drum 222 is disposed and the position where the head unit 24 is disposed, and heats the recording medium P conveyed by the conveying unit 21 so that the temperature of the recording medium P falls within a predetermined temperature range. The heating unit 23 has, for example, an infrared heater or the like, and energizes the infrared heater based on a control signal supplied from the control unit 40 (see FIG. 4) to cause the infrared heater to generate heat.

[0020] The head units 24 eject ink onto the recording medium P from nozzle openings provided on an ink ejection surface facing the transport surface 211a of the transport drum 211 at appropriate timing according to the rotation of the transport drum 211 on which the recording medium P is held, thereby forming an image. The head units 24 are arranged so that the ink ejection surface and the transport surface 211a are separated by a predetermined distance. In the inkjet image forming apparatus 1 of this embodiment, four head units 24 corresponding respectively to four colors of ink, yellow (Y), magenta (M), cyan (C), and black (K), are arranged at predetermined intervals from the upstream side in the transport direction of the recording medium P in the order of Y, M, C, and K.

[0021] 2 is a schematic diagram showing the configuration of the head unit 24. Here, the surface of the head unit 24 that faces the transport surface 211a of the transport drum 211 is shown.

[0022] The head unit 24 includes four recording heads 242 (which function as "inkjet heads" according to the present invention) attached to a mounting member 244. Each of the recording heads 242 is provided with a plurality of recording elements, each of which has a pressure chamber that stores ink, a piezoelectric element provided on the wall of the pressure chamber, and a nozzle 243. When a drive signal that causes the piezoelectric element to deform is input, the pressure chamber of this recording element is deformed due to the deformation of the piezoelectric element, changing the pressure inside the pressure chamber, and ink is ejected from the nozzle that communicates with the pressure chamber.

[0023] The recording head 242 is formed with two nozzle rows each made up of nozzles 243 arranged at equal intervals in a direction intersecting the transport direction of the recording medium P (in this embodiment, a direction perpendicular to the transport direction, i.e., the X direction). These two nozzle rows are arranged such that the arrangement positions of the nozzles 243 are shifted from each other in the X direction by half the arrangement interval of the nozzles 243 in each nozzle row.

[0024] Furthermore, in the recording head 242, nozzles 243 that fail to eject ink (faulty nozzles) may occur due to variations in processing when forming the nozzles 243, variations in the characteristics of the piezoelectric elements, clogging of the nozzles 243, or blockage due to the adhesion of foreign matter to the nozzle openings. A method for detecting faulty nozzles will be described later.

[0025] The four recording heads 242 are arranged in a staggered pattern so that the arrangement range of the nozzle rows in the X direction is continuous without any breaks. The arrangement range in the X direction of the nozzles 243 included in the head unit 24 covers the width in the X direction of the area on the recording medium P conveyed by the conveyance unit 21 where an image is formed, and the head unit 24 is used while its position is fixed with respect to the rotation axis of the conveyance drum 211 when forming an image. In other words, the head unit 24 has a line head that can eject ink across the image formable width in the X direction on the recording medium P, and the inkjet image forming apparatus 1 is a single-pass type inkjet image forming apparatus.

[0026] The number of nozzle rows in the recording head 242 may be one or three or more, instead of two. The number of recording heads 242 in the head unit 24 may be three or less, or five or more, instead of four.

[0027] The ink ejected from the nozzles of the recording elements is energy ray curable, changing phase to a gel or sol state depending on the temperature and curing when irradiated with energy rays such as ultraviolet rays. Also used is ink that is in a gel state at room temperature and becomes a sol state when heated. The head unit 24 includes an ink heating section (not shown) that heats the ink stored within the head unit 24. The ink heating section operates under the control of the control section 40, and heats the ink to a temperature at which it becomes a sol.

[0028] The recording head 242 ejects ink that has been heated and turned into a sol. When this sol ink is ejected onto the recording medium P, the ink droplets land on the recording medium P, and then the ink quickly turns into a gel and solidifies on the recording medium P due to natural cooling.

[0029] The fixing unit 25 has a light-emitting unit arranged across the width of the transport unit 21 in the X direction, and irradiates the recording medium P placed on the transport unit 21 with energy rays such as ultraviolet rays from the light-emitting unit to cure and fix the ink ejected onto the recording medium P. The light-emitting unit of the fixing unit 25 is arranged opposite the transport surface 211a in the transport direction between the position where the head unit 24 is arranged and the position where the delivery drum 281 of the delivery unit 28 is arranged.

[0030] The ink ejected from the nozzles of the recording elements may be energy ray curable ink that changes phase to a gel or sol depending on the temperature and hardens when irradiated with an electron beam (energy beam). In this case, the fixing unit 25 irradiates the recording medium P placed on the conveying unit 21 with an electron beam to harden and fix the ink ejected onto the recording medium P.

[0031] The image reading unit 26 is disposed so as to be able to read the surface of the recording medium P on the conveying surface 211a at a position in the conveying direction between the position where the ink is fixed by the fixing unit 25 and the position where the delivery drum 281 is disposed. In this embodiment, the image reading unit 26 reads the surface of the recording medium P conveyed by the conveying unit 21 within a predetermined reading range and outputs the captured image data to the control unit 40.

[0032] Fig. 3 is a schematic cross-sectional view illustrating the configuration of image reading unit 26. Fig. 3 shows a schematic configuration of image reading unit 26 in a cross section perpendicular to the X direction. Image reading unit 26 includes a housing 261, and a pair of light sources 262, mirrors 2631 and 2632, an optical system 264, and a line sensor 265 housed inside housing 261.

[0033] The housing 261 is a rectangular parallelepiped member arranged with one surface facing the transport surface 211a. The surface of the housing 261 facing the transport surface 211a is a light-transmitting surface 261a made of a light-transmitting material such as glass. In the following, the transport direction of the recording medium P at the position facing the light-transmitting surface 261a is defined as the Y direction, and the direction perpendicular to the XY plane is defined as the Z direction.

[0034] Each of the pair of light sources 262 is a line light source having a plurality of LEDs (Light Emitting Diodes) arranged in a range in the X direction that encompasses the range in which an image can be formed by the head unit 24. The pair of light sources 262 are arranged at symmetrical positions with respect to a predetermined reference plane A perpendicular to the conveyance direction, and emit light to the recording medium P on the conveyance surface 211a through the light transmitting surface 261a of the housing 261. The angle of each light source 262 is adjusted so that when the distance between the light transmitting surface 261a and the recording medium P on the conveyance surface 211a is a predetermined standard distance d, light is irradiated at the same angle of incidence onto a line of the recording medium P that intersects with the reference plane A.

[0035] The mirror 2631 has a length in the X direction corresponding to the arrangement range of the light source 262, and reflects, in the direction of the mirror 2632, light that is emitted from the light source 262 and reflected by the recording medium P and that travels on the reference plane A. The mirror 2632 is provided at a position closer to the light transmitting surface 261a than the mirror 2631, and reflects the light reflected by the mirror 2631 in the direction of the optical system 264. By providing the mirrors 2631 and 2632 in this manner, an appropriate optical path length is ensured within the housing 261.

[0036] The optical system 264 focuses the incident light from the mirror 2632 onto the position of the image sensor of the line sensor 265. The optical system 264 is adjusted so that an image of the surface of the recording medium P is formed at the position of the image sensor of the line sensor 265, that is, so that the surface of the recording medium P is in focus, when the distance between the light transmitting surface 261a and the recording medium P on the conveying surface 211a is a predetermined standard distance d.

[0037] The line sensor 265 has a configuration in which a plurality of imaging elements, each of which outputs a signal corresponding to the intensity of incident light, are arranged in the Y direction. Specifically, the line sensor 265 has three rows of imaging elements arranged in the Y direction, and each row of imaging elements outputs a signal corresponding to the intensity of the R (red), G (green), and B (blue) wavelength components of the incident light. The imaging elements corresponding to R, G, and B, respectively, can be, for example, a CCD (Charge Coupled Device) sensor having a photodiode as a photoelectric conversion element or a CMOS (Complementary Metal Oxide Semiconductor) sensor having a color filter that transmits R, G, or B wavelength component light disposed in the light receiving section. Note that an area sensor may be used in the image reading unit 26 instead of the line sensor 265.

[0038] The signal output from the line sensor 265 undergoes current-to-voltage conversion, amplification, noise removal, analog-to-digital conversion, etc. in an analog front end (not shown), and is output as imaging data indicating the luminance value of the read image to the control unit 40. In this embodiment, the pixel value of the imaging data indicates the intensity of light detected by the imaging element in 256 gradations from 0 to 255.

[0039] The delivery section 28 has a belt loop 282 having a circular belt supported on the inside by two rollers, and a cylindrical transfer drum 281 that transfers the recording medium P from the conveying section 21 to the belt loop 282, and the recording medium P transferred from the conveying section 21 onto the belt loop 282 by the transfer drum 281 is transported by the belt loop 282 and sent to the paper discharge section 30.

[0040] The paper discharge unit 30 has a plate-shaped paper discharge tray 31 on which the recording medium P sent out from the image forming unit 20 by the delivery unit 28 is placed.

[0041] 4 is a block diagram showing the main functional configuration of the inkjet image forming apparatus 1. The inkjet image forming apparatus 1 includes a heating unit 23, a recording head driving unit 241 and a recording head 242, a fixing unit 25, an image reading unit 26, a control unit 40, a conveyance driving unit 51, an operation display unit 52, an input / output interface 53, a bus 54, and the like.

[0042] The recording head driving unit 241 supplies a driving signal to the recording element of the recording head 242 at an appropriate timing to deform the piezoelectric element in accordance with the image data (and thus the ejection data), thereby ejecting an amount of ink from the nozzle 243 of the recording head 242 in accordance with the pixel value of the image data.

[0043] The control unit 40 has a CPU 41 (Central Processing Unit), a RAM 42 (Random Access Memory), a ROM 43 (Read Only Memory), a storage unit 44, and an image correction unit 45. The control unit 40 functions as an "attachment direction detection unit," an "acquisition unit," an "inspection execution unit," and a "determination unit" of the present invention.

[0044] The CPU 41 reads out various control programs and setting data stored in the ROM 43, stores them in the RAM 42, and executes the programs to perform various arithmetic processing. The CPU 41 also performs overall control of the overall operation of the inkjet image forming apparatus 1.

[0045] The RAM 42 provides a working memory space for the CPU 41 and stores temporary data. The RAM 42 may include a non-volatile memory.

[0046] The ROM 43 stores various control programs and setting data executed by the CPU 41. Note that the ROM 43 may be replaced by a rewritable non-volatile memory such as an EEPROM (Electrically Erasable Programmable Read Only Memory) or a flash memory.

[0047] The storage unit 44 stores print jobs (image formation commands) input from the external device 2 via the input / output interface 53, image data related to the print jobs, image data 44c such as test charts (test images) used in the defective nozzle detection process described below, image data 44a captured by the image reading unit 26, defective nozzle data 44b indicating defective nozzles with ejection problems, etc. Of these, the print job includes information specifying the image data related to the image to be formed, as well as information related to the type of recording medium P on which the image is to be formed (for example, the size and thickness of the recording medium P). As the storage unit 44, for example, an HDD (Hard Disk Drive) is used, and a DRAM (Dynamic Random Access Memory) or the like may also be used in combination.

[0048] The image correction unit 45 performs correction processing on the image data 44c stored in the storage unit 44 based on the defective nozzle data 44b stored in the storage unit 44.

[0049] The transport drive unit 51 supplies a drive signal to the transport drum motor of the transport drum 211 based on a control signal supplied from the control unit 40, thereby rotating the transport drum 211 at a predetermined speed and timing.

[0050] In addition, the conveying drive unit 51 supplies drive signals to motors for operating the medium supply unit 12, the transfer unit 22, and the delivery unit 28 based on control signals supplied from the control unit 40, thereby supplying the recording medium P to the conveying unit 21 and discharging it from the conveying unit 21.

[0051] The operation display unit 52 includes a display device such as a liquid crystal display or an organic EL display, and an input device such as operation keys and a touch panel overlaid on the screen of the display device. The operation display unit 52 displays various information on the display device, and converts user input operations on the input device into operation signals and outputs them to the control unit 40. The operation display unit 52 functions as the "display unit" and "warning output unit" of the present invention.

[0052] The input / output interface 53 mediates the transmission and reception of data between the external device 2 and the control unit 40. The input / output interface 53 is configured, for example, by any one of various serial interfaces, various parallel interfaces, or a combination of these.

[0053] The bus 54 is a path for transmitting and receiving signals between the control unit 40 and other components.

[0054] The external device 2 is, for example, a personal computer or a cloud server, and supplies print jobs, image data, and the like to the control unit 40 via an input / output interface 53.

[0055] Next, a method for detecting defective nozzles in the inkjet image forming apparatus 1 will be described.

[0056] In the inkjet image forming apparatus 1 of this embodiment, defective nozzles are detected at a predetermined timing or based on a predetermined input operation by the user on the operation display unit 52. Defective nozzles are detected by recording a predetermined test chart on the recording medium P, capturing an image of this test chart with the image reading unit 26, and analyzing the captured image data.

[0057] Fig. 5 is a diagram showing an example of a test chart used to detect defective nozzles. The test chart 60 shown in Fig. 5 is an image formed on the recording medium P by the head unit 24, and includes a line pattern made up of multiple lines 61 extending in the transport direction.

[0058] 5 shows a portion of the test chart 60 on which an image is formed by one of the recording heads 242. Similar line patterns are also recorded by the other recording heads 242 of the head unit 24.

[0059] Each line 61 of the test chart 60 is formed by ink ejected from a single nozzle 243 of the head unit 24. Furthermore, in this test chart 60, the lines 61 recorded by nozzles 243 that are adjacent in position in the X direction are recorded with a shift in the Y direction, and the positions of the lines 61 recorded by every seventh nozzle 243 are aligned in the Y direction.

[0060] Each of the multiple lines 61 in this test chart 60 corresponds to one of the multiple nozzles 243, so if an abnormality is found in a specific line 61 in the image data of the test chart 60 captured by the image reading unit 26, the nozzle 243 corresponding to that specific line 61 can be identified as a faulty nozzle. For example, if the line 61a shown in Figure 5 is missing in the image data of the test chart 60, the nozzle 243 corresponding to that line 61a will be identified as a faulty nozzle that does not eject ink.

[0061] Furthermore, if the density of a specific line 61 in the image data of the test chart 60 is outside the predetermined reference range, the nozzle 243 corresponding to that specific line 61 is identified as a faulty nozzle having an abnormality in the amount of ink ejected.

[0062] Furthermore, if a specific line 61 in the image data of the test chart 60 is not formed within a predetermined range corresponding to the position of the nozzle 243, the nozzle 243 corresponding to the specific line 61 is identified as a faulty nozzle having an abnormality in the direction of ink ejection. When a faulty nozzle is identified, faulty nozzle data 44b indicating the array number of the faulty nozzle in the head unit 24 is stored in the memory unit 44.

[0063] After the faulty nozzle has been identified, the print job is stored in the storage unit 44, and when an image forming operation is performed to form an image related to the print job on the recording medium P, the faulty nozzle data 44b is referenced, and the ejection data is corrected so that the ink ejection failure of the faulty nozzle is compensated for. Specifically, the faulty nozzle is made non-ejectable to prohibit ink ejection, and the ejection data is corrected so that the area where the faulty nozzle should have ejected is compensated for by the normal nozzles around the faulty nozzle (more specifically, the amount of ink ejected from the nozzle opening of the normal nozzle is increased from the initial value). The image is then formed based on this corrected ejection data. This makes it possible to form an image with appropriate image quality even when there is a faulty nozzle.

[0064] Next, a defective nozzle detection process for detecting defective nozzles and an ejection data correction process using the defective nozzle detection results will be described.

[0065] 6 is a flowchart showing an example of the faulty nozzle detection process. This faulty nozzle detection process is executed when a predetermined input operation is performed by the user to instruct the execution of faulty nozzle detection on the operation display unit 52. The faulty nozzle detection process may also be executed at a predetermined timing, such as when the inkjet image forming apparatus 1 is manufactured or shipped, or when images have been formed on a predetermined number of recording media P by the inkjet image forming apparatus 1.

[0066] First, the control unit 40 controls the head unit 24 to form the test chart 60 on the recording medium P (step S101). That is, the control unit 40 causes the conveyance drive unit 51 to output a drive signal to the conveyance drum motor of the conveyance drum 211, causing the conveyance drum 211 to rotate at a predetermined speed. Then, the control unit 40 causes the recording head drive unit 241 to supply test image data (ejection data) related to the test chart 60 stored in the storage unit 44 to the recording head 242, thereby causing the head unit 24 to eject ink onto the recording medium P and forming the test chart 60 on the recording medium P.

[0067] In addition, when the recording medium P to which the ink has been applied moves to the position of the fixing unit 25, the control unit 40 causes the fixing unit 25 to irradiate the ink with a predetermined energy beam, thereby fixing the ink to the recording medium P.

[0068] Next, the control unit 40 causes the image reading unit 26 to read the recording medium P on which the test chart 60 is formed (step S102). That is, the control unit 40 causes the image reading unit 26 to repeatedly read the test chart 60 on the recording medium P at appropriate timing according to the rotation of the conveying drum 211, acquire imaging data 44a, and store it in the memory unit 44.

[0069] Finally, the control unit 40 detects faulty nozzles based on the image data of the test chart 60 (step S103). That is, the control unit 40 identifies a line 61 where an abnormality is found from the image data of the test chart 60, and identifies the nozzle 243 corresponding to that line 61 as a faulty nozzle. The control unit 40 then generates faulty nozzle data 44b indicating the array number in the head unit 24 of the identified faulty nozzle, and stores this in the storage unit 44. When the processing of step S103 is completed, the control unit 40 ends the faulty nozzle detection processing.

[0070] Thereafter, the image correction unit 45 performs correction processing on the image data 44c transmitted from the external device 2 and stored in the storage unit 44, based on the defective nozzle data 44b stored in the storage unit 44. In other words, when image data to be printed by a defective nozzle exists, the image correction unit 45 corrects the image data to be printed by the surrounding nozzles (normal nozzles) to image data corresponding to ink droplets with a larger volume.

[0071] However, when the nozzles 243 are arranged in multiple nozzle rows in the recording head 242, depending on the position in the transport direction of the nozzle row in which the nozzle (faulty nozzle) experiencing the ink ejection failure is arranged, there is a problem that the nozzles (normal nozzles) surrounding the faulty nozzle may not be able to sufficiently compensate for the defective nozzle, resulting in a defective image.

[0072] 7A is a diagram illustrating the above problem. Fig. 7A shows a case where, among nozzles 243a, 243b, 243c, 243d, 243e, 243f, 243g, 243h, and 243i arranged in multiple nozzle arrays (two in the example shown in Fig. 7) in a print head 242, the nozzle array in which faulty nozzles 243b and 243d are arranged is located upstream in the transport direction. In this case, when ink droplets are ejected onto a recording medium P from the nozzle array located upstream (upstream nozzle array) and then large-volume ink droplets are ejected onto the recording medium P from the nozzle array located downstream (downstream nozzle array), the area where ink droplets should have been ejected from the faulty nozzles 243b and 243d is complemented by large-volume ink droplets ejected from normal nozzles 243f, 243g, 243h, and 243i (downstream nozzle array) surrounding the faulty nozzles 243b and 243d. At this time, under the influence (e.g., surface tension) of the ink ejected by the upstream nozzle row, the large volume ink droplets ejected by the normal nozzles 243f, 243g, 243h, and 243i move toward the area where the defective nozzles 243b and 243d should have ejected, thereby filling in the area.

[0073] 7B shows a case where the nozzle array in which the faulty nozzles 243b and 243d are arranged is located downstream in the transport direction among the nozzles 243a, 243b, 243c, 243d, 243e, 243f, 243g, 243h, and 243i arranged in multiple nozzle arrays (two in the example shown in FIG. 7) in the print head 242. In this case, even if the nozzle array located upstream (upstream nozzle array) ejects large volumes of ink droplets onto the recording medium P and then the nozzle array located downstream (downstream nozzle array) ejects ink droplets onto the recording medium P, the area where the faulty nozzles 243b and 243d should have ejected ink may not be filled with the large volumes of ink droplets ejected by the normal nozzles 243f, 243g, 243h, and 243i (upstream nozzle array) surrounding the faulty nozzles 243b and 243d. This is because the large volume of ink droplets ejected by the normal nozzles 243f, 243g, 243h, and 243i is not affected by the ink ejected by the downstream nozzle row (for example, by surface tension), and does not move toward the area where the defective nozzles 243b and 243d should have ejected, i.e., the area may not be filled. This tendency is particularly pronounced when the surface energy of the recording medium P is low, i.e., when the ink repellency is high.

[0074] 7B, when the nozzle row in which the faulty nozzle is arranged is located downstream in the transport direction, the nozzles (normal nozzles) surrounding the faulty nozzle do not sufficiently compensate for the faulty nozzle, which can easily result in a defective image. Furthermore, the above problem is likely to occur when the ink ejected from the nozzle has a tendency to thicken and harden after landing on the recording medium P (for example, a tendency to change phase from gel (solid) to sol (liquid) depending on the temperature).

[0075] Therefore, in this embodiment, from the viewpoint of suppressing the occurrence of image defects due to defective ink ejection, the recording head 242 is attached to the head unit 24 in an attachment direction that corresponds to the inspection results of the ink ejection state for the nozzles 243. Specifically, the recording head 242 is attached to the head unit 24 in an attachment direction that causes the nozzle row in which the defective nozzle is arranged to be positioned upstream in the transport direction. This allows the nozzles surrounding the defective nozzle (normal nozzles arranged downstream in the transport direction) to sufficiently complement the defective nozzle, making it possible to suppress the occurrence of image defects due to defective ink ejection.

[0076] 8 is a diagram illustrating how the recording head 242 is attached to the head unit 24. Here, the surface of the head unit 24 that faces the transport surface 211a of the transport drum 211 is shown.

[0077] 8A, the recording head 242 is positioned relative to the head unit 24 by positioning members 246a and 246b and then attached to the head unit 24. The positioning members 246a and 246b engage with V-shaped recesses formed on the sides (left side and right side) of the recording head 242, thereby positioning the recording head 242 at a preset position relative to the head unit 24.

[0078] The recording head 242 is provided with a regulating member 245 (which functions as a "second regulating section" of the present invention) that regulates the mounting direction of the recording head 242 relative to the head unit 24. Depending on the inspection results of the ink ejection state of the nozzles 243, the user attaches the regulating member 245 to a predetermined position on the recording head 242 so that the position in the transport direction of the nozzle row in which the defective nozzle is arranged is an upstream position.

[0079] The head unit 24 has a regulating member 246c (which functions as the "first regulating portion" of the present invention) that regulates the mounting direction of the recording head 242. As a result, even if a user mistakenly mounts the recording head 242 so that the nozzle row in which the defective nozzles are arranged is positioned downstream in the transport direction, interference between the regulating member 245 and the regulating member 246c prevents the recording head 242 from being mounted to the head unit 24 in the wrong mounting direction (a mounting direction in which the recording head 242 is rotated 180 degrees from the correct mounting direction). This reliably prevents the recording head 242 from being mounted to the head unit 24 mistakenly so that the nozzle row in which the defective nozzles are arranged is positioned downstream in the transport direction.

[0080] 8B, mounting direction information indicating the correct mounting direction may be attached as mark 247 to the exterior member (outer surface) of recording head 242 on the side of the nozzle row in which the faulty nozzles are arranged. In this case, the user checks mark 247 attached to the exterior member of recording head 242 and attaches recording head 242 to head unit 24 so that the nozzle row in which the faulty nozzles are arranged is positioned upstream in the transport direction. This reliably prevents recording head 242 from being erroneously attached to head unit 24 so that the nozzle row in which the faulty nozzles are arranged is positioned downstream in the transport direction.

[0081] Note that mounting direction information indicating the correct mounting direction may be attached as mark 247 to accessory 242b of recording head 242 (see FIG. 4, for example, the packaging box or enclosed document of recording head 242). In this case, the user checks mark 247 attached to accessory 242b of recording head 242, and attaches recording head 242 to head unit 24 so that the nozzle row in which the defective nozzle is arranged is positioned upstream in the transport direction. Alternatively, mark 247 may be attached to recording head 242 in advance, and then, depending on the inspection results of the ink ejection state for nozzles 243, mark 247 may be attached to the side of the nozzle row in which the defective nozzle is arranged.

[0082] Furthermore, in this embodiment, the recording head 242 includes a storage unit 242a (see FIG. 4, which functions as the "first storage unit" of the present invention) that stores mounting direction information indicating the correct mounting direction. The operation and display unit 52 then reads out and displays the mounting direction information stored in the storage unit 242a of the recording head 242. In this case, the user checks the mounting direction information displayed by the operation and display unit 52, and mounts the recording head 242 relative to the head unit 24 so that the nozzle row in which the faulty nozzle is arranged is positioned upstream in the transport direction. This reliably prevents the recording head 242 from being erroneously mounted relative to the head unit 24 so that the nozzle row in which the faulty nozzle is arranged is positioned downstream in the transport direction.

[0083] Furthermore, in this embodiment, the control unit 40 detects the attachment direction of the recording head 242 relative to the head unit 24, for example, by detecting the electrical connection state between the head unit 24 and the recording head 242. If the attachment direction indicated in the attachment direction information stored in the memory unit 242a of the recording head 242 does not match the detected attachment direction, the operation and display unit 52 outputs a warning, for example, that the attachment direction is incorrect. In this case, the user checks the warning output by the operation and display unit 52 and attaches the recording head 242 relative to the head unit 24 so that the nozzle row in which the defective nozzle is arranged is positioned upstream in the transport direction. This reliably prevents the recording head 242 from being erroneously attached to the head unit 24 so that the nozzle row in which the defective nozzle is arranged is positioned downstream in the transport direction.

[0084] Furthermore, in this embodiment, identification information (e.g., a head ID) that uniquely identifies the recording head 242 is attached to the recording head 242 (e.g., the outer surface of the recording head 242) or to an accessory 242b of the recording head 242 (see FIG. 4, for example, a packaging box or enclosed documentation for the recording head 242). Attachment direction information indicating the correct attachment direction is stored in association with the identification information in the storage unit 2a of the external device 2 (functioning as the "second storage unit" of the present invention). When the identification information attached to the recording head 242 or the accessory 242b is input by a user operation on the operation / display unit 52, the control unit 40 acquires the attachment direction information associated with the identification information from the storage unit 2a of the external device 2 via the input / output interface 53. The operation / display unit 52 then displays the attachment direction information acquired by the control unit 40. In this case, the user checks the attachment direction information displayed on the operation / display unit 52 and attaches the recording head 242 to the head unit 24 so that the nozzle row in which the defective nozzle is arranged is positioned upstream in the transport direction. Therefore, it is possible to reliably prevent the recording head 242 from being mistakenly attached to the head unit 24 so that the nozzle row in which the defective nozzles are arranged is positioned downstream in the transport direction.

[0085] Furthermore, in this embodiment, the control unit 40 detects the attachment direction of the recording head 242 relative to the head unit 24, for example, by detecting the electrical connection state between the head unit 24 and the recording head 242. If the attachment direction indicated in the attachment direction information acquired by the control unit 40 does not match the attachment direction detected by the control unit 40, the operation display unit 52 outputs a warning, for example, that the attachment direction is incorrect. In this case, the user checks the warning output by the operation display unit 52 and attaches the recording head 242 to the head unit 24 so that the nozzle row in which the defective nozzle is arranged is positioned upstream in the transport direction. This reliably prevents the recording head 242 from being erroneously attached to the head unit 24 so that the nozzle row in which the defective nozzle is arranged is positioned downstream in the transport direction.

[0086] Furthermore, in this embodiment, the recording head 242 includes a storage unit 242a that stores identification information (e.g., a serial number) that uniquely identifies the recording head 242. Mounting direction information indicating the correct mounting direction is stored in association with the identification information in the storage unit 2a of the external device 2. The control unit 40 references the identification information stored in the storage unit 242a and acquires the mounting direction information associated with the identification information from the storage unit 2a of the external device 2 via the input / output interface 53. The operation / display unit 52 then displays the mounting direction information acquired by the control unit 40. In this case, the user checks the mounting direction information displayed on the operation / display unit 52 and mounts the recording head 242 relative to the head unit 24 so that the nozzle row in which the defective nozzle is arranged is positioned upstream in the transport direction. This reliably prevents the recording head 242 from being erroneously mounted relative to the head unit 24 so that the nozzle row in which the defective nozzle is arranged is positioned downstream in the transport direction.

[0087] Furthermore, in this embodiment, the control unit 40 determines in which of the multiple nozzle rows (e.g., the upstream nozzle row or the downstream nozzle row) the nozzle experiencing the ink ejection failure is arranged, based on the inspection results of the ink ejection state of the nozzles 243. Then, the operation and display unit 52 outputs a warning (specifically, a warning urging the user to change the attachment direction of the recording head 242 relative to the head unit 24) in accordance with the determination results of the control unit 40. In this case, the user checks the warning output by the operation and display unit 52, understands that the nozzle row in which the defective nozzle is arranged is located downstream in the transport direction, and attaches the recording head 242 to the head unit 24 so that the nozzle row in which the defective nozzle is arranged is located upstream in the transport direction. This reliably prevents the recording head 242 from being erroneously attached to the head unit 24 so that the nozzle row in which the defective nozzle is arranged is located downstream in the transport direction.

[0088] As explained in detail above, the recording head 242 is attached to the head unit 24 in an attachment direction that corresponds to the inspection results of the ink ejection state for the nozzles 243. Specifically, the recording head 242 is attached to the head unit 24 in an attachment direction that causes the nozzle row in which the defective nozzle is arranged to be positioned upstream in the transport direction. According to this embodiment configured in this manner, the defective nozzle is sufficiently complemented by the nozzles around it (normal nozzles arranged downstream in the transport direction), making it possible to suppress the occurrence of image defects due to defective ink ejection.

[0089] In the above embodiment, an example has been described in which a test chart 60 including a plurality of lines 61 is used to detect faulty nozzles, but the present invention is not limited to this. For example, a gray chart consisting of gradation patterns formed by each nozzle 243 may be formed as a test image, and faulty nozzles may be detected from uneven density in the reading results of the gray chart. Such a gray chart makes it possible to detect abnormalities in the ink ejection direction of the nozzles 243, as well as easily and appropriately detect abnormalities in the ink ejection amount of the nozzles 243.

[0090] Furthermore, in the above embodiment, an example has been described in which the recording medium P being moved by the rotation of the transport drum 211 is read by the image reading unit 26 and ink is ejected from the head unit 24 onto the moving recording medium P, but the present invention is not limited to this. For example, the reading of the recording medium P by the image reading unit 26 and the ejection of ink onto the recording medium P by the head unit 24 may be performed while the rotation of the transport drum 211 is temporarily stopped.

[0091] Furthermore, in the above embodiment, the image reading unit 26 provided in the inkjet image forming apparatus 1 is used to inspect the ink ejection state from the nozzles 243 of the recording head 242, but the ink ejection state may also be inspected using a different inspection device. That is, an image recorded by the recording head 242 may be read by an image reading unit similar to the image reading unit 26 provided outside the inkjet image forming apparatus 1, and the ink ejection state may be inspected. Alternatively, a known method may be used, such as inspecting the ink ejection state by directly observing ink droplets ejected from the nozzles 243 of the recording head 242 with a camera device, a photoelectric sensor, or the like.

[0092] Furthermore, in the above embodiment, an example has been described in which the recording medium P is transported by the transport drum 211, but the present invention is not limited to this. For example, the recording medium P may be transported by a transport belt that is supported by two rollers and moves in accordance with the rotation of the rollers. Furthermore, the recording medium P may be transported by a transport member that moves back and forth on the same plane.

[0093] Furthermore, in the above embodiment, an inkjet image forming apparatus 1 was described as an example in which ink that is in a gel state at room temperature and turns into a sol state when heated is heated into a sol state and then ejected. However, the present invention is not limited to this, and various known inks including inks that are in a sol state or liquid state at room temperature may be used.

[0094] Furthermore, the above-described embodiments are merely examples of specific embodiments for carrying out the present invention, and the technical scope of the present invention should not be construed as being limited by these embodiments. In other words, the present invention can be carried out in various forms without departing from the gist or main features thereof. [Explanation of symbols]

[0095] 1. Inkjet image forming device 2 External device 2a Storage section 10 Paper feed section 11 Paper tray 12 Media supply section 20 Image forming unit 21 Conveyor 211 Transport drum 211a Conveying surface 22 Delivery Unit 23 Heating section 24 Head Unit 241 Recording head drive unit 242 recording head 242a Storage section 242b Appendage 243, 243a, 243b, 243c, 243d, 243e, 243f, 243g, 243h, 243i nozzles 244 Mounting parts 245,246c Regulatory members 246a, 246b Positioning members 247 marks 25 Fixing section 26 Image reading unit 261 Case 261a Light transmission surface 262 Light source 2631,2632 Mirror 264 Optical system 265 Line Sensor 28 Delivery Department 30 Paper output section 31 Paper output tray 40 Control Unit 41 CPU 42 RAM 43 ROM 44 Memory section 44a Imaging data 44b Bad nozzle data 44c Image data 45 Image correction section 51 Conveyor drive unit 52 Operation display section 53 Input / Output Interface 54 Bus 60 Test Charts 61,61a line P Recording medium

Claims

1. an inkjet head in which nozzles for ejecting ink are arranged in a plurality of nozzle rows; a head unit having the inkjet head; a control unit that controls the inkjet head so as to form an image on a recording medium with the ink; Equipped with the inkjet head is attached to the head unit in an attachment direction such that, based on an inspection result of the ink ejection state of the nozzles, a nozzle row including a defective nozzle is disposed on the upstream side in a transport direction of the recording medium, and a nozzle row not including a defective nozzle is disposed on the downstream side in the transport direction; Image forming device.

2. the head unit has a first restricting portion that restricts the mounting direction of the inkjet head; The image forming apparatus according to claim 1 .

3. the inkjet head has a first storage unit that stores mounting direction information indicating the mounting direction, a display unit that displays the mounting direction information stored in the first storage unit, 3. The image forming apparatus according to claim 1.

4. an inkjet head in which nozzles for ejecting ink are arranged in a plurality of nozzle rows; a head unit having the inkjet head; a control unit that controls the inkjet head so as to form an image on a recording medium with the ink; a display unit that displays information; Equipped with the inkjet head has a first storage unit that stores mounting direction information indicating a mounting direction according to an inspection result of an ink ejection state of the nozzles, the display unit displays the mounting direction information stored in the first storage unit, the inkjet head is attached to the head unit in the attachment direction; Image forming device.

5. an attachment direction detection unit that detects an attachment direction of the inkjet head relative to the head unit; a warning output unit that outputs a warning when the mounting direction indicated in the mounting direction information stored in the first storage unit does not match the mounting direction detected by the mounting direction detection unit; The image forming apparatus according to claim 3 or 4, comprising:

6. Identification information for identifying the inkjet head is attached to the inkjet head or an attachment of the inkjet head, mounting direction information indicating the mounting direction is stored in a second storage unit of the external device in association with the identification information; an acquisition unit that acquires the mounting direction information stored in the second storage unit; a display unit that displays the mounting direction information acquired by the acquisition unit; The image forming apparatus according to claim 1 or 2, comprising:

7. an inkjet head in which nozzles for ejecting ink are arranged in a plurality of nozzle rows; a head unit having the inkjet head; a control unit that controls the inkjet head so as to form an image on a recording medium with the ink; an acquisition unit that acquires information stored in a second storage unit of the external device; a display unit that displays the information acquired by the acquisition unit; Equipped with Identification information for identifying the inkjet head is attached to the inkjet head or an attachment of the inkjet head, mounting direction information indicating a mounting direction according to an inspection result of the ink ejection state of the nozzles is stored in the second storage unit in association with the identification information, the acquisition unit acquires the mounting direction information stored in the second storage unit, the display unit displays the mounting direction information acquired by the acquisition unit, the inkjet head is attached to the head unit in the attachment direction; Image forming device.

8. the inkjet head has a first storage unit that stores identification information for identifying the inkjet head; mounting direction information indicating the mounting direction is stored in a second storage unit of the external device in association with the identification information; an acquisition unit that acquires the mounting direction information stored in the second storage unit based on the identification information stored in the first storage unit; a display unit that displays the mounting direction information acquired by the acquisition unit; The image forming apparatus according to claim 1 or 2, comprising:

9. an inkjet head in which nozzles for ejecting ink are arranged in a plurality of nozzle rows; a head unit having the inkjet head; a control unit that controls the inkjet head so as to form an image on a recording medium with the ink; an acquisition unit that acquires information stored in a second storage unit of the external device; a display unit that displays the information acquired by the acquisition unit; Equipped with the inkjet head has a first storage unit that stores identification information for identifying the inkjet head; installation direction information indicating an installation direction according to an inspection result of the ink ejection state for the nozzles is stored in a second storage unit of the external device in association with the identification information; the acquisition unit acquires the attachment direction information stored in the second storage unit based on the identification information stored in the first storage unit; the display unit displays the mounting direction information acquired by the acquisition unit, the inkjet head is attached to the head unit in the attachment direction; Image forming device.

10. an attachment direction detection unit that detects an attachment direction of the inkjet head relative to the head unit; a warning output unit that outputs a warning when the mounting direction indicated in the mounting direction information acquired by the acquisition unit does not match the mounting direction detected by the mounting direction detection unit; 10. The image forming apparatus according to claim 6, further comprising:

11. an inspection execution unit that inspects the ink ejection state of the nozzles; The image forming apparatus according to any one of claims 1 to 10.

12. a determination unit that determines in which of the plurality of nozzle rows a nozzle experiencing an ink ejection defect is arranged based on the result of the inspection; a warning output unit that outputs a warning in accordance with a determination result of the determination unit; The image forming apparatus according to claim 11 ,

13. the warning output unit outputs a warning to prompt the user to change the mounting direction of the inkjet head relative to the head unit. The image forming apparatus according to claim 12.

14. An inkjet head that is attached to a head unit of an image forming apparatus in an attachment direction according to an inspection result of an ink ejection state of the nozzles, a second restricting portion that restricts the mounting direction of the inkjet head relative to the head unit; Inkjet head.

15. An inkjet head attached to a head unit of an image forming apparatus, in which nozzles for ejecting ink are arranged in a plurality of nozzle rows, attachment direction information indicating an attachment direction with respect to the head unit is attached to the inkjet head or an accessory of the inkjet head, the mounting direction information is information that indicates, based on an inspection result of the ink ejection state of the nozzles, an mounting direction in which a nozzle row including a defective nozzle is arranged on the upstream side in a transport direction of a recording medium, and a nozzle row that does not include a defective nozzle is arranged on the downstream side in the transport direction. Inkjet head.

16. An inkjet head attached to a head unit of an image forming apparatus, in which nozzles for ejecting ink are arranged in a plurality of nozzle rows, a first storage unit that stores mounting direction information indicating a mounting direction with respect to the head unit; the mounting direction information is information that indicates, based on an inspection result of the ink ejection state of the nozzles, an mounting direction in which a nozzle row including a defective nozzle is arranged on the upstream side in a transport direction of a recording medium, and a nozzle row that does not include a defective nozzle is arranged on the downstream side in the transport direction. Inkjet head.

17. An inkjet head attached to a head unit of an image forming apparatus, in which nozzles for ejecting ink are arranged in a plurality of nozzle rows, Identification information for identifying the inkjet head is attached to the inkjet head or an attachment of the inkjet head, Mounting direction information indicating a mounting direction with respect to the head unit is stored in a second storage unit of the external device in association with the identification information, the mounting direction information is information that indicates, based on an inspection result of the ink ejection state of the nozzles, an mounting direction in which a nozzle row including a defective nozzle is arranged on the upstream side in a transport direction of a recording medium, and a nozzle row that does not include a defective nozzle is arranged on the downstream side in the transport direction. Inkjet head.

18. An inkjet head attached to a head unit of an image forming apparatus, in which nozzles for ejecting ink are arranged in a plurality of nozzle rows, a first storage unit that stores identification information for identifying the inkjet head; Mounting direction information indicating a mounting direction with respect to the head unit is stored in a second storage unit of the external device in association with the identification information, the mounting direction information is information that indicates, based on an inspection result of the ink ejection state of the nozzles, an mounting direction in which a nozzle row including a defective nozzle is arranged on the upstream side in a transport direction of a recording medium, and a nozzle row that does not include a defective nozzle is arranged on the downstream side in the transport direction. Inkjet head.

Images