Image forming apparatus, posture adjustment method, and image forming method

Abstract

To provide an image forming apparatus, a posture adjustment method, and an image forming method capable of outputting an image in which an inclination degree of an ejection portion can be easily recognized.SOLUTION: An image forming apparatus includes: a recording head 30 that has a plurality of nozzles 30A arranged along a width direction D12, each of the nozzles 30A ejecting ink toward a sheet; a first forming processing unit that alternately ejects the ink from a first nozzle included in a first nozzle row L11 and a second nozzle included in a second nozzle row L12 in the plurality of nozzles 30A to form a first line image IM1 on the sheet; and a second forming processing unit that alternately ejects the ink from the first nozzle and a third nozzle included in a third nozzle row L13 to form a second line image IM2 on the sheet.SELECTED DRAWING: Figure 5

Description

[Technical Field]

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

[0002] An inkjet image forming apparatus includes a discharge unit such as a recording head, which has a plurality of nozzles arranged along a width direction of a recording medium such as a sheet, which is perpendicular to the conveyance direction of the recording medium, and discharges ink from each of the nozzles toward the recording medium.

[0003] Patent document 1 also discloses an image forming device that uses the ejection unit to print a predetermined test pattern and obtains the inclination of the ejection unit based on a human or machine evaluation of the print result of the test pattern. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-178205 Summary of the Invention [Problem to be solved by the invention]

[0005] The test pattern is not specifically disclosed in the above-mentioned Patent Document 1. Here, it is desirable that the test pattern be an image that makes it easy to recognize the degree of inclination of the ejection section.

[0006] An object of the present invention is to provide an image forming apparatus, an attitude adjustment method, and an image forming method that are capable of outputting an image in which the degree of inclination of a discharge portion is easily recognized. [Means for solving the problem]

[0007] According to one aspect of the present invention, an image forming apparatus includes a discharge unit, a first forming processing unit, and a second forming processing unit. The discharge unit has a plurality of nozzles arranged along a width direction perpendicular to a transport direction of a recording medium, and causes each of the nozzles to discharge ink toward the recording medium. The first forming processing unit alternately discharges ink from a first nozzle located on one side of two adjacent nozzles in the width direction among the plurality of nozzles in the transport direction and a second nozzle of one of the two adjacent nozzles, thereby forming a first line image along the transport direction on the recording medium. The second forming processing unit alternately discharges ink from the first nozzle and a third nozzle, different from the second nozzle among the two adjacent nozzles, thereby forming a second line image along the transport direction on the recording medium.

[0008] According to another aspect of the present invention, an attitude adjustment method is performed using the image forming apparatus and includes an acquisition step and an adjustment step. In the acquisition step, an inclination angle of the ejection unit with respect to the width direction is acquired based on the first line image and the second line image formed on the recording medium. In the adjustment step, an attitude of the ejection unit is adjusted based on the results acquired in the acquisition step.

[0009] An image forming method according to another aspect of the present invention is carried out by an image forming apparatus having a plurality of nozzles arranged along a width direction perpendicular to a transport direction of a recording medium and including an ejection unit that ejects ink from each of the nozzles toward the recording medium, and includes a first forming step and a second forming step. In the first forming step, the ink is alternately ejected from a first nozzle located on one side of two adjacent nozzles adjacent in the width direction among the plurality of nozzles in the transport direction and a second nozzle of either of the two adjacent nozzles, thereby forming a first line image along the transport direction on the recording medium. In the second forming step, the ink is alternately ejected from the first nozzle and a third nozzle different from the second nozzle among the two adjacent nozzles, thereby forming a second line image along the transport direction on the recording medium. [Effects of the Invention]

[0010] According to the present invention, it is possible to output an image that allows the degree of inclination of the ejection portion to be easily recognized. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a cross-sectional view showing the configuration of an image forming apparatus according to an embodiment of the present invention. [Figure 2] FIG. 2 is a plan view showing the configuration of the image forming section and the transport unit in the image forming apparatus according to the embodiment of the present invention. [Figure 3] FIG. 3 is a block diagram showing the system configuration of the image forming apparatus according to the embodiment of the present invention. [Figure 4] FIG. 4 is a diagram showing a plurality of nozzles provided in a recording head of an image forming apparatus according to an embodiment of the present invention, and a first line image and a second line image formed by the plurality of nozzles. [Figure 5] FIG. 5 is a diagram showing a plurality of nozzles provided in a recording head of an image forming apparatus according to an embodiment of the present invention, and a first line image and a second line image formed by the plurality of nozzles. [Figure 6] FIG. 6 is a diagram showing a plurality of nozzles provided in a recording head of an image forming apparatus according to an embodiment of the present invention, and a first line image and a second line image formed by the plurality of nozzles. [Figure 7] FIG. 7 is a flowchart showing an example of the tilt angle acquisition process executed by the image forming apparatus according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. Note that the following embodiment is an example of a specific embodiment of the present invention and does not limit the technical scope of the present invention.

[0013] [Configuration of image forming apparatus 100] First, the configuration of an image forming apparatus 100 according to an embodiment of the present invention will be described with reference to Figures 1 to 4. In Figure 1, a sheet transport path R11 is indicated by a two-dot chain line.

[0014] Image forming apparatus 100 is a printer capable of forming an image on a sheet (an example of a recording medium of the present invention) using an inkjet method. Note that the recording medium of the present invention is not limited to a sheet, and may be cloth, a resin film, or the like. The present invention may also be applied to a fax machine, a copier, or a multifunction machine capable of forming an image on a sheet using an inkjet method.

[0015] 1, the image forming apparatus 100 includes a housing 1, a sheet conveying section 2, an image forming section 3, a conveying unit 4, and an image reading section 5. The image forming apparatus 100 also includes an operation display section 6 and a control section 7 shown in FIG.

[0016] The housing 1 houses each component of the image forming apparatus 100. A paper feed cassette 11 (see FIG. 1) is removably provided in the housing 1. The paper feed cassette 11 stores sheets on which images are to be formed. A paper output tray 12 (see FIG. 1) is provided on the outer surface of the housing 1. Sheets on which images are formed by the image forming unit 3 are discharged to the paper output tray 12. Inside the housing 1, the sheets stored in the paper feed cassette 11 are transported along a sheet transport path R11 (see FIG. 1) that passes through an image formation position by the image forming unit 3 and reaches the paper output tray 12.

[0017] The sheet transport unit 2 transports sheets stored in the paper feed cassette 11 along a sheet transport path R11 (see FIG. 1). As shown in FIG. 1, the sheet transport unit 2 includes a pickup roller 21 and multiple transport rollers 22. The pickup roller 21 picks up the top sheet of the stack of sheets stored in the paper feed cassette 11 and sends the sheet to the sheet transport path R11. The multiple transport rollers 22 are arranged side by side along the sheet transport path R11. Each transport roller 22 transports the sheet along the sheet transport path R11. Each transport roller 22 transports the sheet in a transport direction D11 (see FIG. 1) from the paper feed cassette 11 to the paper output tray 12.

[0018] The image forming unit 3 forms an image on a sheet transported along a sheet transport path R11 (see FIG. 1). As shown in FIG. 1, the image forming unit 3 includes line heads 31 to 34 and a head frame 35.

[0019] 2, each of the line heads 31 to 34 is elongated in a width direction D12 perpendicular to the conveying direction D11. Specifically, each of the line heads 31 to 34 has a length in the width direction D12 corresponding to the width of the largest size sheet that can be accommodated in the paper feed cassette 11. The line heads 31 to 34 are arranged side by side at equal intervals along the conveying direction D11.

[0020] The line head 31 ejects black ink toward the sheet being transported by the transport unit 4. The line head 32 ejects cyan ink toward the sheet being transported by the transport unit 4. The line head 33 ejects magenta ink toward the sheet being transported by the transport unit 4. The line head 34 ejects yellow ink toward the sheet being transported by the transport unit 4.

[0021] Except for the fact that the color of ink ejected is different, the line heads 32 to 34 have the same configuration as the line head 31. Only the line head 31 will be described below.

[0022] 2, the line head 31 has three recording heads 30. Each of the recording heads 30 is elongated in the width direction D12. The three recording heads 30 are arranged in a staggered pattern along the width direction D12.

[0023] The recording head 30 has a plurality of nozzles 30A (see FIG. 2) arranged along a width direction D12 perpendicular to a sheet conveyance direction D11. The recording head 30 ejects ink from each nozzle 30A toward the sheet. The recording head 30 is an example of an ejection section of the present invention.

[0024] In the recording head 30, the plurality of nozzles 30A are arranged at a density corresponding to the printing resolution of the image forming apparatus 100 along the width direction D12.

[0025] For example, as shown in FIG. 4, the recording head 30 includes three nozzle arrays L10 (L11, L12, L13) formed by a plurality of nozzles 30A aligned along the width direction D12. In each nozzle array L10, the plurality of nozzles 30A are aligned at intervals of two pixels of the printing resolution of the image forming unit 3. The three nozzle arrays L10 are arranged in the following order along the transport direction D11: a first nozzle array L11, a third nozzle array L13, and a second nozzle array L12. The first nozzle array L11 is arranged so as to be offset by one pixel of the printing resolution of the image forming unit 3 toward a first direction D21 (see FIG. 4) along the width direction D12 relative to the second nozzle array L12. The third nozzle array L13 is arranged so as to be offset by one pixel of the printing resolution of the image forming unit 3 relative to the first nozzle array L11 toward the first direction D21. The second nozzle row L12 is arranged so as to be shifted by one pixel of the printing resolution of the image forming unit 3 in the first direction D21 with respect to the third nozzle row L13.

[0026] All the nozzles 30A included in the line head 31 are arranged along the width direction D12. Specifically, the three recording heads 30 included in the line head 31 are arranged in a staggered pattern along the width direction D12 so that all the nozzles 30A included in the line head 31 are arranged along the width direction D12 at a density corresponding to the printing resolution of the image forming apparatus 100.

[0027] Each recording head 30 includes a pressure chamber (not shown), a discharge element (not shown), and an individual flow path (not shown) corresponding to each nozzle 30A. The pressure chamber communicates with the nozzle 30A and stores ink. The discharge element discharges ink from the nozzle 30A in response to an input of a drive signal. For example, the discharge element is a piezoelectric element. The discharge element discharges ink from the nozzle 30A by changing the volume of the pressure chamber in response to an input of the drive signal. The individual flow path is an ink flow path provided between the pressure chamber and a common flow path (not shown) common to the multiple nozzles 30A. The common flow path is connected to a multiple individual flow path corresponding to the multiple nozzles 30A. The common flow path is connected to an ink supply unit (not shown) that supplies ink to each of the pressure chambers.

[0028] The head frame 35 supports the line heads 31 to 34. The head frame 35 is supported by the housing 1. The number of line heads provided in the image forming unit 3 does not have to be four. Also, the number of recording heads 30 provided in each of the line heads 31 to 34 does not have to be three.

[0029] As shown in FIG. 1, the transport unit 4 is disposed below the line heads 31 to 34. The transport unit 4 transports a sheet while facing the recording head 30. As shown in FIG. 1, the transport unit 4 includes a transport belt 41 on which the sheet is placed, a first tension roller 42, a second tension roller 43, and a third tension roller 44 that tension the transport belt 41, and a transport frame 45 that supports these. The gap between the transport belt 41 and the recording head 30 is adjusted so that the gap between the surface of the sheet and the recording head 30 during image formation is a predetermined distance (for example, 1 mm).

[0030] The first tension roller 42 is rotationally driven by a rotational driving force supplied from a motor (not shown). As a result, the conveyor belt 41 rotates in a direction that allows the sheet to be conveyed in the conveying direction D11 (see FIG. 1). The conveying unit 4 is also provided with a suction unit (not shown) that sucks air through a number of through holes formed in the conveyor belt 41 to attract the sheet to the conveyor belt 41.

[0031] The image reading unit 5 reads the image formed on the sheet by the image forming unit 3. The image reading unit 5 reads the image formed on the sheet at a reading resolution lower than the printing resolution of the image forming unit 3.

[0032] As shown in FIG. 3, the image reading unit 5 includes a line sensor 51 and an AFE (analog front end) circuit 52.

[0033] As shown in FIG. 1, the line sensor 51 is disposed downstream of the image forming unit 3 in the sheet conveying direction D11 on the sheet conveying path R11. The line sensor 51 is capable of reading an image of one line along the width direction D12 (see FIG. 2) from a sheet conveyed by the sheet conveying unit 2. For example, the line sensor 51 is a CIS (contact image sensor). The line sensor 51 includes a plurality of imaging elements arranged side by side in the width direction D12. Each of the imaging elements includes a light-emitting unit and a light-receiving unit. The light-emitting unit emits light toward the sheet conveyed by the sheet conveying unit 2. The light-receiving unit is configured to receive light emitted from the light-emitting unit and reflected by the sheet, and outputs an analog electrical signal corresponding to the amount of received light. The line sensor 51 outputs an analog electrical signal corresponding to an image of one line at predetermined intervals in response to a control signal input from the control unit 7.

[0034] The AFE 52 is an electronic circuit that performs predetermined processing on the analog electrical signal output from the line sensor 51. Specifically, the AFE 52 includes a signal conversion unit that converts the analog electrical signal output from the line sensor 51 into a digital electrical signal (image data). The AFE 52 also includes an image processing unit that performs predetermined image processing, such as shading correction, on the image data output from the signal conversion unit. The AFE 52 outputs the image data that has been output from the image processing unit and has undergone the image processing to the control unit 7.

[0035] The operation display unit 6 is a user interface of the image forming apparatus 100. The operation display unit 6 includes a display unit and an operation unit. The display unit displays various information in response to control instructions from the control unit 7. For example, the display unit is a flat panel display such as a liquid crystal display. The operation unit inputs various information to the control unit 7 in response to user operations. For example, the operation unit includes operation keys and a touch panel.

[0036] The control unit 7 performs overall control of the image forming apparatus 100. As shown in FIG. 3, the control unit 7 includes a CPU 61, a ROM 62, and a RAM 63. The CPU 61 is a processor that executes various types of arithmetic processing. The ROM 62 is a non-volatile storage device that stores in advance information such as control programs for causing the CPU 61 to execute various types of processing. The RAM 63 is a volatile or non-volatile storage device that is used as a temporary storage memory (work area) for the various types of processing executed by the CPU 61. The CPU 61 performs overall control of the image forming apparatus 100 by executing the various control programs that are stored in advance in the ROM 62.

[0037] Incidentally, there is known an image forming apparatus that uses the recording head 30 to print a predetermined test pattern, and acquires the tilt of the recording head 30 based on a human or machine evaluation of the print result of the test pattern.

[0038] Here, it is desirable that the test pattern be an image that allows the degree of inclination of the recording head 30 to be easily recognized.

[0039] In contrast to this, the image forming apparatus 100 according to the embodiment of the present invention is capable of outputting an image that makes it easy to recognize the degree of inclination of the recording head 30, as will be described below.

[0040] [Configuration of control unit 7] Next, the configuration of the control unit 7 will be described with reference to FIG.

[0041] As shown in FIG. 3, the control unit 7 includes a first forming processing unit 64, a second forming processing unit 65, a reading processing unit 66, and an acquisition processing unit 67.

[0042] Specifically, a tilt angle acquisition program for causing the CPU 61 to function as each of the above-mentioned processing units is stored in advance in the ROM 62 of the control unit 7. The CPU 61 executes the tilt angle acquisition program stored in the ROM 62 to function as each of the above-mentioned processing units.

[0043] The tilt angle acquisition program may be recorded on a computer-readable recording medium such as a CD, a DVD, or a flash memory, and may be read from the recording medium and stored in a storage device provided in image forming apparatus 100. Some or all of the processing units included in control unit 7 may be configured with electronic circuits. The tilt angle acquisition program may also be a program for causing multiple processors to function as the processing units included in control unit 7.

[0044] The first forming processing unit 64 alternately ejects ink from a first nozzle among the multiple nozzles 30A that is located on one side of the conveying direction D11 relative to two adjacent nozzles adjacent to it in the width direction D12, and a second nozzle of either of the two adjacent nozzles, thereby forming a first line image IM1 (see Figure 4) along the conveying direction D11 on the sheet.

[0045] For example, the first nozzles are nozzles 30A included in a first nozzle row L11 (see FIG. 4), and the second nozzles are nozzles 30A included in a second nozzle row L12 (see FIG. 4).

[0046] For example, the first formation processing unit 64 forms first line images IM1 that are arranged at equal intervals along the width direction D12. For example, the first formation processing unit 64 forms the first line images IM1 that are arranged at equal intervals along the width direction D12 using all the nozzles 30A included in the first nozzle row L11 and all the nozzles 30A included in the second nozzle row L12.

[0047] The second forming processing unit 65 alternately ejects ink from the first nozzle and a third nozzle, which is one of the two adjacent nozzles and is different from the second nozzle, to form a second line image IM2 (see Figure 4) on the sheet along the conveying direction D11.

[0048] For example, the third nozzle is the nozzle 30A included in the third nozzle row L13 (see FIG. 4).

[0049] For example, the second formation processing unit 65 forms second line images IM2 that are arranged at equal intervals along the width direction D12. For example, the second formation processing unit 65 forms the second line images IM2 that are arranged at equal intervals along the width direction D12 using all the nozzles 30A included in the first nozzle row L11 and all the nozzles 30A included in the third nozzle row L13.

[0050] The reading processing unit 66 reads the first line image IM1 and the second line image IM2 formed on the sheet.

[0051] For example, the reading processing unit 66 uses the image reading unit 5 to read the first line image IM1 and the second line image IM2 formed on the sheet.

[0052] The reading processing unit 66 may use a scanner communicably connected to the image forming apparatus 100 to read the first line image IM1 and the second line image IM2 formed on the sheet.

[0053] The acquisition processing unit 67 acquires the tilt angle θ (see FIG. 5) of the recording head 30 with respect to the width direction D12 based on the reading result by the reading processing unit 66.

[0054] Fig. 5 shows the recording head 30 in a state inclined with respect to the width direction D12. Specifically, Fig. 5 shows the recording head 30 in a state inclined with respect to the width direction D12 so that an end of the recording head 30 in a first direction D21 is located upstream in the transport direction D11 of an end of the recording head 30 in a second direction D22 (see Fig. 5) opposite to the first direction D21. In this specification, when the recording head 30 is inclined as shown in Fig. 5, the sign of the inclination angle θ (see Fig. 5) of the recording head 30 with respect to the width direction D12 is assumed to be negative.

[0055] 6 also shows the recording head 30 in a state inclined with respect to the width direction D12. Specifically, Fig. 6 shows the recording head 30 in a state inclined with respect to the width direction D12 so that the end of the recording head 30 in the first direction D21 is located downstream in the transport direction D11 of the end of the recording head 30 in the second direction D22. In this specification, when the recording head 30 is inclined as shown in Fig. 6, the sign of the inclination angle θ of the recording head 30 with respect to the width direction D12 (see Fig. 6) is assumed to be positive.

[0056] FIG. 4 shows the recording head 30 in a state where the tilt angle θ is zero.

[0057] As shown in FIG. 5, when the inclination angle θ is a negative value, the distance between the first nozzle and the second nozzle in the width direction D12 is narrower. Therefore, the width of the first line image IM1 is narrower than when the inclination angle θ is zero (see FIG. 4). Also, as shown in FIG. 5, when the inclination angle θ is a negative value, the distance between the first nozzle and the third nozzle in the width direction D12 is widened. Therefore, the width of the second line image IM2 is thicker than when the inclination angle θ is zero (see FIG. 4). In other words, when the width of the second line image IM2 is thicker than the width of the first line image IM1, it is possible to determine that the sign of the inclination angle θ is negative. Furthermore, it is possible to identify the inclination angle θ based on the width of the second line image IM2, the width of the first line image IM1, or the ratio between the width of the second line image IM2 and the width of the first line image IM1.

[0058] As shown in FIG. 6, when the inclination angle θ is a positive value, the distance between the first nozzle and the second nozzle in the width direction D12 is wide. Therefore, the width of the first line image IM1 is thicker than when the inclination angle θ is zero (see FIG. 4). Also, as shown in FIG. 6, when the inclination angle θ is a positive value, the distance between the first nozzle and the third nozzle in the width direction D12 is narrower. Therefore, the width of the second line image IM2 is narrower than when the inclination angle θ is zero (see FIG. 4). In other words, when the width of the second line image IM2 is narrower than the width of the first line image IM1, it is possible to determine that the sign of the inclination angle θ is positive. Furthermore, it is possible to identify the inclination angle θ based on the width of the second line image IM2, the width of the first line image IM1, or the ratio between the width of the second line image IM2 and the width of the first line image IM1.

[0059] Here, in the image forming apparatus 100, the first forming processing unit 64 forms first line images IM1 arranged at equal intervals along the width direction D12. That is, in the image forming apparatus 100, a rectangular first region including the first line images IM1 arranged at equal intervals along the width direction D12 is formed. The first region is recognized as a monochromatic color region by a person or by the image reading unit 5, whose reading resolution is lower than the printing resolution of the image forming unit 3. As the width of the first line image IM1 included in the first region becomes narrower, the density of the first region recognized by a person or the image reading unit 5 becomes lighter. Furthermore, as the width of the first line image IM1 included in the first region becomes wider, the density of the first region recognized by a person or the image reading unit 5 becomes darker.

[0060] Furthermore, in the image forming apparatus 100, the second forming processing unit 65 forms second line images IM2 that are arranged at equal intervals along the width direction D12. That is, in the image forming apparatus 100, a rectangular second region including second line images IM2 that are arranged at equal intervals along the width direction D12 is formed. The second region is recognized as a monochrome color region by a person or by the image reading unit 5, whose reading resolution is lower than the printing resolution of the image forming unit 3. As the width of the second line image IM2 included in the second region becomes narrower, the density of the second region recognized by a person or the image reading unit 5 becomes lighter. As the width of the second line image IM2 included in the second region becomes wider, the density of the second region recognized by a person or the image reading unit 5 becomes darker.

[0061] That is, when the density of the first region is lower than the density of the second region (see FIG. 5), it is possible to determine that the sign of the tilt angle θ is negative. Also, when the density of the first region is higher than the density of the second region (see FIG. 6), it is possible to determine that the sign of the tilt angle θ is positive. Also, it is possible to identify the tilt angle θ based on the density of the first region, the density of the second region, or the ratio between the density of the first region and the density of the second region.

[0062] For example, the acquisition processing unit 67 detects the density of the first region based on the reading result by the reading processing unit 66. The acquisition processing unit 67 also detects the density of the second region based on the reading result by the reading processing unit 66. The acquisition processing unit 67 then acquires the tilt angle θ based on the detected densities of the first region and the second region. For example, the acquisition processing unit 67 acquires the tilt angle θ using table data that indicates the correspondence between the ratio of the density of the first region to the density of the second region and the tilt angle θ. The table data may be stored in advance in the ROM 62 of the control unit 7.

[0063] The acquisition processing unit 67 may acquire the tilt angle θ based on the width of the first line image IM1 and the width of the second line image IM2 detected based on the reading result by the reading processing unit 66. In this case, the first formation processing unit 64 only needs to form at least one first line image IM1. Also, the second formation processing unit 65 only needs to form at least one second line image IM2. Also, the reading resolution of the image reading unit 5 does not need to be lower than the printing resolution of the image forming unit 3.

[0064] [Tilt angle acquisition process] 7, an example of the procedure for obtaining an inclination angle executed by the control unit 7 in the image forming apparatus 100, as well as the image forming method and the attitude adjustment method of the present invention will be described. Here, steps S11, S12, etc. represent the numbers of the processing procedures (steps) executed by the control unit 7.

[0065] For example, the tilt angle acquisition process is executed when an instruction to execute the tilt angle acquisition process is input on the operation display unit 6. For example, the tilt angle acquisition process is executed for any one of the recording heads 30 specified by the user.

[0066] <Step S11> First, in step S11, the control unit 7 forms a first line image IM1 on a sheet conveyed by the sheet conveying unit 2. The processing of step S11 is an example of a first forming step of the present invention, and is executed by the first forming processing unit 64 of the control unit 7.

[0067] Specifically, the control unit 7 uses all the nozzles 30A included in the first nozzle row L11 (see Figure 4) and all the nozzles 30A included in the second nozzle row L12 (see Figure 4) to form the first region including a first line image IM1 arranged at equal intervals along the width direction D12.

[0068] <Step S12> In step S12, the control unit 7 forms a second line image IM2 on the sheet on which the first line image IM1 has been formed by the processing of step S11. The processing of step S12 is an example of a second forming step of the present invention, and is executed by the second forming processing unit 65 of the control unit 7.

[0069] Specifically, the control unit 7 uses all the nozzles 30A included in the first nozzle row L11 (see Figure 4) and all the nozzles 30A included in the third nozzle row L13 (see Figure 4) to form the second region including the second line image IM2 arranged at equal intervals along the width direction D12.

[0070] <Step S13> In step S13, the control unit 7 reads the first line image IM1 formed on the sheet by the processing of step S11 and the second line image IM2 formed on the sheet by the processing of step S12. The processing of step S13 is executed by the reading processing unit 66 of the control unit 7.

[0071] Specifically, the control unit 7 uses the image reading unit 5 to read the first area and the second area formed on the sheet.

[0072] <Step S14> In step S14, the control unit 7 acquires the tilt angle θ (see FIG. 5) of the recording head 30 with respect to the width direction D12 based on the reading result from the processing in step S13. The processing in step S14 is executed by the acquisition processing unit 67 of the control unit 7. The processing in steps S13 and S14 is an example of an acquisition step of the present invention.

[0073] Specifically, the control unit 7 detects the density of the first region and the density of the second region based on the reading result of the process in step S13. Then, the control unit 7 obtains the tilt angle θ using the detected densities of the first region and the second region and the table data.

[0074] <Step S15> In step S15, the control unit 7 outputs the tilt angle θ acquired by the process in step S14.

[0075] For example, the control unit 7 displays the tilt angle θ acquired by the process of step S14 on the operation display unit 6. This allows the worker adjusting the attitude of the recording head 30 to recognize the tilt angle θ. Therefore, the worker can adjust the attitude of the recording head 30 based on the tilt angle θ acquired by the process of step S14. The process of adjusting the attitude of the recording head 30 performed by the worker is an example of an adjustment step of the present invention.

[0076] In this way, the image forming apparatus 100 can output images (first line image IM1 and second line image IM2) that make it easy to recognize the degree of inclination of the recording head 30.

[0077] Furthermore, in the image forming apparatus 100, first line images IM1 arranged at equal intervals along the width direction D12 and second line images IM2 arranged at equal intervals along the width direction D12 are formed on the sheet. As a result, the degree of tilt of the recording head 30 is expressed by the ratio between the density of the first region and the density of the second region. Therefore, the degree of tilt of the recording head 30 can be more easily recognized.

[0078] The adjustment step of the present invention may be executed by the control unit 7. In this case, the image forming apparatus 100 may be provided with an adjustment mechanism capable of adjusting the attitude of the recording head 30. The control unit 7 may adjust the attitude of the recording head 30 using the adjustment mechanism.

[0079] The acquisition step of the present invention may be performed by a person (the operator). In this case, the image forming apparatus 100 does not need to include the image reading unit 5, the reading processing unit 66, and the acquisition processing unit 67.

[0080] The second nozzles may be nozzles 30A included in the third nozzle row L13. In this case, the third nozzles are nozzles 30A included in the second nozzle row L12.

[0081] The first nozzle may be a nozzle 30A included in the second nozzle row L12. In this case, the nozzle 30A included in the first nozzle row L11 is either the second nozzle or the third nozzle.

[0082] The number of nozzle rows L10 included in the recording head 30 may be at least two or more.

[0083] [Notes on the Invention] The following is a summary of the invention extracted from the above-described embodiment. Note that the configurations and processing functions described in the following supplementary notes can be selected and combined as desired.

[0084] <Appendix 1> An image forming device comprising: an ejection unit having a plurality of nozzles arranged along a width direction perpendicular to a transport direction of a recording medium, and ejecting ink from each of the nozzles toward the recording medium; a first formation processing unit that alternately ejects the ink from a first nozzle located on one side of the transport direction of two adjacent nozzles adjacent to each other in the width direction among the plurality of nozzles and a second nozzle of either of the two adjacent nozzles, thereby forming a first line image along the transport direction on the recording medium; and a second formation processing unit that alternately ejects the ink from the first nozzle and a third nozzle different from the second nozzle among the two adjacent nozzles, thereby forming a second line image along the transport direction on the recording medium.

[0085] <Appendix 2> An image forming apparatus as described in Appendix 1, wherein the first forming processing unit forms the first line images arranged at equal intervals along the width direction, and the second forming processing unit forms the second line images arranged at equal intervals along the width direction.

[0086] <Appendix 3> An image forming apparatus as described in Appendix 1 or 2, comprising: a reading processing unit that reads the first line image and the second line image formed on the recording medium; and an acquisition processing unit that acquires the inclination angle of the ejection unit with respect to the width direction based on the reading result by the reading processing unit.

[0087] <Appendix 4> An attitude adjustment method performed using the image forming apparatus described in Appendix 1 or 2, comprising: an acquisition step of acquiring the inclination angle of the ejection section with respect to the width direction based on the first line image and the second line image formed on the recording medium; and an adjustment step of adjusting the attitude of the ejection section based on the acquisition results obtained by the acquisition step.

[0088] <Appendix 5> An image forming method carried out by an image forming device having a plurality of nozzles arranged along a width direction perpendicular to the transport direction of a recording medium and an ejection unit that ejects ink from each of the nozzles toward the recording medium, the image forming method including: a first forming step in which the ink is alternately ejected from a first nozzle located on one side of the transport direction of two adjacent nozzles adjacent to each other in the width direction among the plurality of nozzles and a second nozzle of either of the two adjacent nozzles to form a first line image along the transport direction on the recording medium; and a second forming step in which the ink is alternately ejected from the first nozzle and a third nozzle, different from the second nozzle among the two adjacent nozzles, to form a second line image along the transport direction on the recording medium. [Explanation of symbols]

[0089] 1 chassis 2 Sheet transport section 3 Image forming unit 4 Transport unit 5 Image reading unit 6 Operation display section 7 Control Unit 11 Paper cassette 12 Output tray 21 Pickup roller 22 Transport roller 30 Recording head 30A nozzle 31 Line Head 32 Line Head 33 Line Head 34 Line Head 35 Head Frame 41 Conveyor belt 42 First tension roller 43 Second tension roller 44 Third tension roller 45 Transport frame 51 Line Sensor 52 AFE circuit 61 CPU 62 ROM 63 RAM 64 First formation processing section 65 Second formation processing section 66 Reading processing section 67 Acquisition processing unit 100 Image forming device

Claims

1. an ejection unit having a plurality of nozzles arranged along a width direction perpendicular to a conveyance direction of the recording medium, and ejecting ink from each of the nozzles toward the recording medium; a first forming processing unit that alternately ejects the ink from a first nozzle located on one side of two adjacent nozzles in the width direction among the plurality of nozzles and a second nozzle of either one of the two adjacent nozzles, thereby forming a first line image along the transport direction on the recording medium; a second forming processing unit that alternately ejects the ink from the first nozzle and a third nozzle, which is one of the two adjacent nozzles and is different from the second nozzle, to form a second line image along the transport direction on the recording medium; An image forming apparatus comprising:

2. the first forming processing unit forms the first line images arranged at equal intervals along the width direction, the second forming processing unit forms the second line images arranged at equal intervals along the width direction. The image forming apparatus according to claim 1 .

3. a reading processing unit that reads the first line image and the second line image formed on the recording medium; an acquisition processing unit that acquires an inclination angle of the ejection unit with respect to the width direction based on a reading result by the reading processing unit; The image forming apparatus according to claim 1 or 2, comprising:

4. 3. A posture adjustment method performed using the image forming apparatus according to claim 1, comprising: an acquisition step of acquiring an inclination angle of the ejection portion with respect to the width direction based on the first line image and the second line image formed on the recording medium; an adjusting step of adjusting the attitude of the discharge part based on the result of the acquisition step; A posture adjustment method including:

5. An image forming method carried out by an image forming apparatus having a plurality of nozzles arranged along a width direction perpendicular to a conveyance direction of a recording medium, the image forming apparatus including an ejection unit that ejects ink from each of the nozzles toward the recording medium, the method comprising: a first forming step of alternately ejecting the ink from a first nozzle located on one side of two adjacent nozzles in the width direction among the plurality of nozzles and a second nozzle of either one of the two adjacent nozzles to form a first line image along the transport direction on the recording medium; a second forming step of alternately ejecting the ink from the first nozzle and a third nozzle, which is one of the two adjacent nozzles and is different from the second nozzle, to form a second line image along the transport direction on the recording medium; An image forming method comprising:

Images