Nozzle check pattern and image forming apparatus

Abstract

The present invention provides a nozzle check pattern and an image forming apparatus that can easily determine the presence or absence of abnormal nozzles without using a scanner. [Solution] The nozzle check pattern is formed on a recording medium by the ejection of ink from a plurality of nozzles arranged in a predetermined nozzle arrangement direction, and a ladder-shaped pattern row is formed by a plurality of ladder lines formed at predetermined intervals in the nozzle arrangement direction, and auxiliary lines are formed between adjacent plurality of ladder lines.

Description

Technical Field

[0001] The present disclosure relates to a nozzle check pattern and an image forming apparatus.

Background Art

[0002] Conventionally, an inkjet type image forming apparatus (hereinafter sometimes appropriately referred to as an “inkjet image forming apparatus”) that discharges ink onto a recording medium such as cloth or paper to form an image on the recording medium has been known. In such an inkjet image forming apparatus, problems with image quality may occur due to streaks caused by nozzle abnormalities such as missing or weak discharge, unstable discharge, and bending by the nozzles mounted thereon.

[0003] Regarding the occurrence of such nozzle abnormalities, various methods for identifying abnormal nozzles have been proposed. For example, Patent Document 1 discloses a recording apparatus that prints a predetermined test pattern on a recording medium and determines non-discharging nozzles and the inclination of a head based on the printing result of the test pattern. In this recording apparatus, non-discharging nozzles and the inclination of the head are specified by reading the printed test pattern with a scanner.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the technology described in Patent Document 1 requires a scanner to identify abnormal nozzles, which leads to problems such as increased design man-hours, larger recording devices, and increased costs. While it is conceivable to identify abnormal nozzles using an external scanner instead of integrating one into the recording device, this would require reading the test patterns with an external scanner, thus increasing the overall workload.

[0006] Furthermore, if a scanner is not used, abnormal nozzles are identified by visual inspection by the operator. However, with conventional test patterns, it is not possible to visually determine the curvature of the nozzle, making it difficult to properly identify abnormal nozzles.

[0007] The purpose of this disclosure is to provide a nozzle check pattern and an image forming apparatus that can easily determine the presence or absence of abnormal nozzles without using a scanner. [Means for solving the problem]

[0008] The nozzle check pattern relating to this disclosure is A nozzle check pattern formed on a recording medium by the ejection of ink from a plurality of nozzles arranged in a predetermined nozzle arrangement direction, A ladder-like pattern is formed by a plurality of ladder lines formed at predetermined intervals in the nozzle arrangement direction. Auxiliary lines are formed between multiple adjacent ladder lines.

[0009] The image forming apparatus relating to this disclosure is An inkjet head in which multiple nozzles for ejecting ink are arranged along a predetermined nozzle arrangement direction, A control unit that controls the ejection of the ink from the nozzle, Equipped with, The control unit, The above nozzle check pattern is formed on the recording medium. [Effects of the Invention]

[0010] According to this disclosure, the presence or absence of abnormal nozzles can be easily determined without using a scanner. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a schematic diagram showing an example of the configuration of an inkjet image forming apparatus according to this embodiment. [Figure 2] Figure 2 is a schematic diagram showing an example of the configuration of a head unit. [Figure 3] Figure 3 is a schematic diagram showing an example of the configuration of an inkjet head arranged in a head unit. [Figure 4] Figure 4 is a block diagram showing the main functional configuration of an image forming apparatus. [Figure 5] Figure 5 is a schematic diagram illustrating a conventional nozzle check pattern. [Figure 6] Figure 6 is a schematic diagram illustrating the identification of abnormal nozzles using a conventional nozzle check pattern. [Figure 7] Figure 7 is a schematic diagram showing an enlarged portion of the nozzle check pattern in Figure 6. [Figure 8] Figure 8 is a schematic diagram illustrating the nozzle check pattern according to this embodiment. [Figure 9] Figure 9 is a schematic diagram illustrating the identification of abnormal nozzles using the nozzle check pattern according to this embodiment. [Figure 10] Figure 10 is a schematic diagram showing an enlarged portion of the nozzle check pattern in Figure 9. [Modes for carrying out the invention]

[0012] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The present disclosure is not limited to the following embodiments, and various modifications can be made without departing from the gist of the present disclosure. Also, in each figure, those with the same reference numerals are the same or corresponding ones, which is common throughout the entire specification.

[0013] [Configuration of Inkjet Image Forming Apparatus 1] Hereinafter, this embodiment will be described with reference to the drawings. FIG. 1 is a schematic diagram showing an example of the configuration of an inkjet image forming apparatus 1 according to this embodiment. As shown in FIG. 1, an inkjet image forming apparatus (hereinafter simply referred to as "image forming apparatus") 1 includes a supply unit 10, an image forming unit 20, a discharge unit 30, and a control unit 40 (see FIG. 4).

[0014] Under the control of the control unit 40, the image forming apparatus 1 conveys the recording medium P stored in the supply unit 10 to the image forming unit 20. Then, the image forming apparatus 1 forms an image on the recording medium P in the image forming unit 20, and conveys the recording medium P on which the image is formed to the discharge unit 30.

[0015] As the recording medium P, for example, paper such as plain paper or coated paper is used. Note that the present invention is not limited to this, and as the recording medium P, for example, various media capable of forming an image by fixing the ink landing on the surface of cloth or resin may be used.

[0016] The supply unit 10 includes a storage unit 11 that stores the recording medium P, and a medium supply unit 12 that conveys and supplies the recording medium P from the storage unit 11 to the image forming unit 20. The medium supply unit 12 includes an annular belt whose inside is supported by two rollers, and conveys the recording medium P from the storage unit 11 to the image forming unit 20 by rotating the rollers with the recording medium P placed on this belt.

[0017] The image forming unit 20 includes a conveyance unit 21, a delivery unit 22, a heating unit 23, a head unit 24, a drying unit 25, a delivery unit 28, and the like.

[0018] The transport unit 21 holds the recording medium P placed on the transport surface 211a (mounting surface) of the cylindrical transport drum 211. The transport unit 21 also performs a transport operation in which the transport drum 211 is transported in the transport direction by rotating and moving around a rotation axis (cylindrical axis) that extends in the X direction (perpendicular to the plane of the paper in Figure 1).

[0019] The transport drum 211 includes claws and an air intake (not shown) for holding the recording medium P on its transport surface 211a. The recording medium P is held on the transport surface 211a by its ends being pressed down by the claws and being drawn towards the transport surface 211a by the air intake. 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.

[0020] The transfer unit 22 transfers the recording medium P, which has been transported by the media supply unit 12 of the supply unit 10, to the transport unit 21. The transfer unit 22 is positioned between the media supply unit 12 and the transport unit 21 of the supply unit 10. The transfer unit 22 holds one end of the recording medium P transported from the media supply unit 12 with its swing arm 221, picks it up, and transfers it to the transport unit 21 via the transfer drum 222.

[0021] The heating unit 23 is positioned between the transfer drum 222 and the head unit 24. The heating unit 23 heats the recording medium P, which is transported by the transport unit 21, so that it reaches a temperature within a predetermined temperature range. The heating unit 23 has, for example, an infrared heater, and energizes the infrared heater to generate heat based on a control signal supplied from the control unit 40 (see Figure 4).

[0022] The head unit 24 ejects ink onto the recording medium P held on the transport drum 211 to form an image. Specifically, the head unit 24 ejects ink onto the recording medium P from an ink ejection port formed on the nozzle surface 245 (see Figure 2) facing the transport surface 211a of the transport drum 211 at an appropriate timing corresponding to the rotation of the transport drum 211. The head unit 24 is positioned such that the ink ejection port and the transport surface 211a are separated by a predetermined distance.

[0023] In the image forming apparatus 1 of this embodiment, four head units 24 are arranged, each corresponding to one of the four ink colors: yellow (Y), magenta (M), cyan (C), and black (K). Specifically, for example, the four head units 24 are arranged at predetermined intervals from the upstream side in the transport direction of the recording medium P, in the order of the colors Y, M, C, and K.

[0024] Figure 2 is a schematic diagram showing an example of the configuration of the head unit 24. Figure 3 is a schematic diagram showing an example of the configuration of the inkjet head 242 located on the head unit 24. Here, the nozzle surface of the head unit 24 that faces the transport surface 211a of the transport drum 211 is shown.

[0025] The head unit 24 has multiple inkjet heads 242 arranged on a mounting member 244. In Figure 2, as an example, the head unit 24 is shown with four inkjet heads 242 arranged on the mounting member 244. Each inkjet head 242 has multiple image forming elements (recording elements) formed on it, each having a pressure chamber for storing ink, a piezoelectric element positioned on the wall of the pressure chamber, and a nozzle 243. When a drive signal is input to deform the piezoelectric element, the pressure chamber deforms due to the deformation of the piezoelectric element, changing the pressure inside the pressure chamber, and ink is ejected from the nozzle 243 that communicates with the pressure chamber.

[0026] In the inkjet head 242, for example, multiple nozzle rows consisting of nozzles 243 arranged at equal intervals in a direction intersecting the transport direction of the recording medium P (in this embodiment, in a direction perpendicular to the transport direction, i.e., the X direction) are formed on the nozzle surface 245. In the example shown in Figure 3, six nozzle rows LA, LB, LC, RA, RB, and RC are formed on the nozzle surface 245. These multiple nozzle rows are arranged such that the positions of the nozzles 243 are offset from each other in the X direction by a predetermined amount of the spacing between the nozzles 243 in each nozzle row.

[0027] The four inkjet heads 242 are arranged in a staggered pattern so that the arrangement range of the nozzle rows in the X direction is seamlessly connected. The arrangement range of the nozzles 243 included in the head unit 24 in the X direction covers the width in the X direction of the area on the recording medium P transported by the transport unit 21 in which the image is formed. At this time, the position of the head unit 24 is fixed with respect to the rotation axis of the transport drum 211 during image formation. That is, the head unit 24 has a line head capable of ejecting ink over the image-forming width in the X direction relative to the recording medium P. Therefore, the image forming apparatus 1 is a single-pass image forming apparatus.

[0028] Furthermore, the number of nozzle rows in the inkjet head 242 may be one or three or more, rather than two. Also, the number of inkjet heads 242 in the head unit 24 may be three or fewer, or five or more, rather than four.

[0029] Returning to Figure 1, the drying unit 25 has a heat source such as a heater and an air blower such as a fan, and dries the ink on the recording medium P by blowing hot air onto the image forming surface (upper surface) of the recording medium P placed on the transport unit 21. The drying unit 25 is positioned facing the transport surface 211a in the transport direction, between the position of the head unit 24 and the position of the transfer drum 281 of the delivery unit 28.

[0030] In this example, the drying section 25 is described as being integrally formed inside the image forming section 20, but this is not limited to this configuration, and the drying section 25 may be constructed separately from the image forming section 20. If the drying section 25 is constructed separately from the image forming section 20, it may be positioned, for example, between the image forming section 20 and the discharge section 30.

[0031] The delivery unit 28 includes a cylindrical transfer drum 281 that transfers the recording medium P from the transport unit 21 to the belt loop 282, and a belt loop 282 that has a ring-shaped belt supported on the inside by two rollers. The delivery unit 28 transports the recording medium P transferred from the transport unit 21 to the belt loop 282 by the transfer drum 281 and sends it to the discharge unit 30.

[0032] The discharge unit 30 has a mounting unit 31 on which the recording medium P sent out from the image forming unit 20 by the delivery unit 28 is placed.

[0033] Figure 4 is a block diagram showing the main functional configuration of the image forming apparatus 1. As shown in Figure 4, the image forming apparatus 1 includes a heating unit 23, a head drive unit 241 and an inkjet head 242, a drying unit 25, a control unit 40, a transport drive unit 51, an operation display unit 52, and an input / output interface 53.

[0034] The head drive unit 241 supplies a drive signal to the image forming element of the inkjet head 242 at an appropriate timing to deform the piezoelectric element according to the image data. As a result, the head drive unit 241 ejects an amount of ink from the nozzle 243 of the inkjet head 242 that corresponds to the pixel value of the image data.

[0035] The control unit 40 controls the entire image forming apparatus 1. In particular, in this embodiment, the control unit 40 controls the head drive unit 241 of the head unit 24. As a result, in this embodiment, a process is performed to check the state of the nozzles 243 and form a nozzle check pattern on the recording medium P to identify abnormal nozzles. The nozzle check pattern will be described later.

[0036] The control unit 40 includes a CPU 41 (Central Processing Unit), RAM 42 (Random Access Memory), ROM 43 (Read Only Memory), and a storage unit 44.

[0037] The CPU 41 reads various control programs and setting data stored in the ROM 43, stores them in the RAM 42, and executes the programs to perform various calculations. The CPU 41 also provides overall control over the operation of the image forming apparatus 1.

[0038] RAM42 provides the CPU41 with a working memory space and stores temporary data. RAM42 may also include non-volatile memory.

[0039] ROM43 stores various control programs and setting data executed by the CPU41. Alternatively, rewritable non-volatile memory such as EEPROM (Electrically Erasable Programmable Read Only Memory) or flash memory may be used instead of ROM43.

[0040] The storage unit 44 stores print jobs (image formation commands) and image data related to those print jobs that are input from the external device 2 via the input / output interface 53. The print job includes information specifying the image data to be formed, as well as information relating to the type of recording medium P on which the image is formed (for example, the type, size, and thickness of the recording medium P). For example, an HDD (Hard Disk Drive) can be used as the storage unit 44, and DRAM (Dynamic Random Access Memory) may also be used in combination.

[0041] Furthermore, the storage unit 44 stores various information necessary for the control unit 40 to control each part. For example, in this embodiment, the storage unit 44 stores data for forming a nozzle check pattern on the recording medium P.

[0042] 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, causing the transport drum 211 to rotate at a predetermined speed and timing.

[0043] Furthermore, the transport drive unit 51 supplies drive signals to motors that operate the medium supply unit 12, the transfer unit 22, and the delivery unit 28 based on control signals supplied from the control unit 40. As a result, the transport drive unit 51 supplies the recording medium P to the transport unit 21 and discharges it from the transport unit 21.

[0044] The operation display unit 52 comprises a display device such as a liquid crystal display or an organic EL display, and an input device such as operation keys or a touch panel superimposed on the screen of the display device. The operation display unit 52 displays various information on the display device and converts user input operations to the input device into operation signals and outputs them to the control unit 40.

[0045] 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 composed of, for example, various serial interfaces, various parallel interfaces, or a combination thereof.

[0046] External device 2 is, for example, a personal computer, which supplies print jobs and image data, etc., to the control unit 40 via the input / output interface 53.

[0047] [Nozzle check pattern] Next, a nozzle check pattern printed by the inkjet image forming apparatus 1 having the above configuration will be described.

[0048] Conventionally, in an image forming apparatus 1, when identifying an abnormal nozzle, a process is performed to print an image on a recording medium P on which a nozzle check pattern is formed, allowing the ink ejection state of each nozzle 243 to be confirmed. Based on the state of the nozzle check pattern, abnormalities in the nozzles 243, such as missing or non-ejecting nozzles and bends due to head tilt, are determined by visual inspection by an operator or other person, and the abnormal nozzle is identified.

[0049] Figure 5 is a schematic diagram illustrating a conventional nozzle check pattern. The nozzle check pattern shown in Figure 5 is a so-called ladder-type test pattern, where ladder-shaped lines are formed. In the following explanation, the ladder-shaped lines in the nozzle check pattern will be referred to as "ladder lines" as appropriate.

[0050] As shown in Figure 5, this nozzle check pattern consists of patterns corresponding to nozzle rows LA, LB, LC, RA, RB, and RC, each consisting of multiple nozzles 243 arranged on the inkjet head 242. Each nozzle row has multiple ladder lines formed at predetermined nozzle intervals, and multiple ladder-shaped pattern rows are formed by these ladder lines. This is formed by sequentially performing a process in which, after the pattern rows are formed by ejecting ink at predetermined nozzle intervals, the nozzles 243 that eject ink are shifted by one nozzle in the nozzle arrangement direction while the recording medium P is being transported, thereby forming the pattern rows.

[0051] Figure 6 is a schematic diagram illustrating the identification of abnormal nozzles using a conventional nozzle check pattern. In Figure 6, one example of the nozzle check patterns shown in Figure 5 is the nozzle check pattern corresponding to the nozzle row LC.

[0052] In Figure 6, the areas enclosed by dashed lines A and B are parts where the pattern was not printed properly due to a nozzle malfunction. Here, it can be seen that the ladder lines were not properly formed due to unstable ejection from nozzle 243, resulting in streaky printing abnormalities.

[0053] Figure 7 is a schematic diagram showing a magnified portion of the nozzle check pattern in Figure 6. Figure 7 is a magnified view of the area within the bounding box C in the nozzle check pattern of Figure 6. In Figure 7, the area enclosed by the dashed line D shows how the ladder lines are not printed in the correct position due to the bending of nozzle 243.

[0054] If nozzle 243 is bent, the ink ejected from nozzle 243 will land at a different location than it should. As a result, the ladder lines formed by the bent nozzle 243 will have different spacing in the nozzle arrangement direction between adjacent ladder lines in the upper and lower rows compared to normal spacing. Therefore, the operator can identify the abnormal nozzle by visually checking the spacing of these ladder lines.

[0055] However, conventional nozzle check patterns make it difficult to accurately distinguish between the spacing between ladder lines under normal conditions and the spacing between ladder lines when there is a nozzle malfunction. Therefore, when conventional nozzle check patterns are used, it is difficult to identify the bending of the nozzle 243.

[0056] Thus, with conventional nozzle check patterns, it is difficult to determine all nozzle abnormalities, including the bending of nozzle 243, and it may not be possible to properly identify abnormal nozzles. Therefore, the inkjet image forming apparatus 1 according to this embodiment is designed to form a nozzle check pattern that can appropriately detect various types of nozzle abnormalities.

[0057] Figure 8 is a schematic diagram illustrating the nozzle check pattern according to this embodiment. As shown in Figure 8, the nozzle check pattern according to this embodiment is a ladder-type test pattern and, like conventional nozzle check patterns, is composed of patterns corresponding to nozzle rows LA, LB, LC, RA, RB, and RC.

[0058] Furthermore, the nozzle check pattern according to this embodiment has multiple auxiliary lines formed so that slits are provided between the ladder lines. The auxiliary lines are formed by nozzles 243 other than the nozzles 243 corresponding to the ladder lines, and are formed at equal intervals.

[0059] In the nozzle check pattern formed in this embodiment, the length of the ladder lines is determined, for example, by considering the size of the recording medium P on which the nozzle check pattern is formed and the ease of pattern inspection. For example, if the ladder lines are short, it is difficult to determine nozzle abnormalities due to unstable ejection. Also, if the ladder lines are long, the image of the entire nozzle check pattern becomes large, and the visibility of the entire pattern decreases. Therefore, the length of the ladder lines is preferably, for example, about 1 mm to 5 mm.

[0060] In this case, the auxiliary lines are formed to be shorter than the ladder lines. By making the auxiliary lines shorter than the ladder lines, the visibility of abnormal areas during pattern inspection is improved. Specifically, for example, it is preferable that the length of the auxiliary lines be about 1 / 2 to 1 / 4 of the length of the ladder lines.

[0061] The width of the guide lines is determined according to the characteristics of the recording medium P and the ink used, and is preferably determined based on the wetting spread characteristics determined by the recording medium P and the ink. Determining the width of the guide lines based on the wetting spread characteristics improves the visibility of abnormal areas during pattern inspection. Specifically, for example, the width of the slit is preferably about 0.1 mm to 0.5 mm.

[0062] Furthermore, it is preferable that the widths of the ladder lines and auxiliary lines be the same, considering the ease of pattern inspection. The widths of the ladder lines and auxiliary lines may also be determined according to the recording medium P and the type of ink (including color) used.

[0063] Furthermore, the nozzle check pattern is formed based on the resolution of the inkjet head 242, the number of rows of nozzles, and the number of nozzles 243 positioned on the inkjet head 242. In addition, the spacing between the multiple ladder lines is also determined based on the resolution of the inkjet head 242, the number of rows of nozzles, and the number of nozzles 243 positioned on the inkjet head 242.

[0064] Figure 9 is a schematic diagram illustrating the identification of abnormal nozzles using the nozzle check pattern according to this embodiment. In Figure 9, one example of the nozzle check patterns shown in Figure 8 is shown, which corresponds to the nozzle row LC.

[0065] In Figure 9, the areas enclosed by dashed lines A and B are parts where the pattern was not printed properly due to a nozzle malfunction. Note that the areas enclosed by dashed lines A and B are the same as those shown in Figure 6 above.

[0066] Here, the ladder lines and auxiliary lines are not properly formed due to the unstable ejection of nozzle 243. As a result, when viewing the entire pattern of the nozzle row LC, streaky printing abnormalities are more clearly visible compared to conventional methods.

[0067] Figure 10 is a schematic diagram showing a magnified portion of the nozzle check pattern in Figure 9. Figure 10 is a magnified view of the area within the bounding box C in the nozzle check pattern of Figure 9. The area indicated by the bounding box C is the same as the area shown in Figure 6 above.

[0068] In Figure 10, the area enclosed by dashed line D shows how the ladder lines are not printed in the correct position due to the bending of nozzle 243. Note that the area enclosed by dashed line D is the same as the area shown in Figure 7 above.

[0069] As shown in Figure 10, in locations where abnormalities due to bending of the nozzle 243 are observed, it can be visually confirmed that the spacing between the ladder line and the auxiliary line adjacent to the ladder line in the nozzle arrangement direction is wider or narrower compared to the spacing between other auxiliary lines.

[0070] As described above, in the nozzle check pattern according to this embodiment, auxiliary lines are formed between adjacent ladder lines, making it easier for the operator to visually identify nozzle abnormalities. Therefore, compared to conventional methods, it is possible to easily determine whether or not there is an abnormal nozzle. [Industrial applicability]

[0071] The nozzle check pattern relating to this disclosure can be suitably used for inspection purposes when forming solder resist. [Explanation of symbols]

[0072] 1. Inkjet image forming apparatus 10 Supply section 11 Storage Unit 12 Media supply section 20 Image forming unit 21 Conveying section 22 Transfer Unit 23 Heating section 24 Head Units 25 Drying section 28 Delivery Department 30 Discharge section 31 Mounting section 40 Control Unit 41 CPU 42 RAM 43 ROM 211 Conveyor Drum 211a Conveying surface 221 Swingarm section 222 Transfer Drum 241 Head drive unit 242 Inkjet Heads 243 Nozzles 244 Mounting components 245 Nozzle surface 281 Transfer Drum 282 Belt Loops

Claims

1. A nozzle check pattern formed on a recording medium by the ejection of ink from a plurality of nozzles arranged in a predetermined nozzle arrangement direction, A ladder-like pattern is formed by a plurality of ladder lines formed at predetermined intervals in the nozzle arrangement direction. Auxiliary lines are formed between multiple adjacent ladder lines. Nozzle check pattern.

2. The auxiliary line is formed to be shorter than the ladder line. The nozzle check pattern according to claim 1.

3. The spacing between adjacent ladder lines or auxiliary lines is determined according to the characteristics of the recording medium and the ink. The nozzle check pattern according to claim 1.

4. The spacing between adjacent ladder lines or auxiliary lines is determined according to the wetting characteristics of the recording medium and the ink. The nozzle check pattern according to claim 3.

5. The width of the ladder line and the auxiliary line is determined according to the characteristics of the recording medium and the ink. The nozzle check pattern according to claim 1.

6. The width of the ladder line and the auxiliary line is determined according to the recording medium and the type of ink. The nozzle check pattern according to claim 5.

7. The widths of the ladder line and the auxiliary line are the same. The nozzle check pattern according to claim 1.

8. An inkjet head in which multiple nozzles for ejecting ink are arranged along a predetermined nozzle arrangement direction, A control unit that controls the ejection of the ink from the nozzle, Equipped with, The control unit, The nozzle check pattern described in claim 1 is formed on the recording medium. Image forming apparatus.

9. The control unit, Based on the resolution of the inkjet head and the number of nozzles arranged in the nozzle arrangement direction, the nozzle check pattern is formed. The image forming apparatus according to claim 8.

10. The control unit, Based on the resolution of the inkjet head and the number of nozzles arranged in the nozzle arrangement direction, the spacing between the plurality of ladder lines is determined. The image forming apparatus according to claim 8.

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