Inkjet recording apparatus and inkjet recording method

Abstract

To provide an inkjet recording device for performing recording by a multi-pass method which suppresses an influence of air flow misdirection at a central part while suppressing end twisting at both ends of a nozzle array, and enables recording of a high quality image.SOLUTION: A mask pattern B applied to recording data by a nozzle array unit has a first region in which a distribution of recording rates applied to first nozzle groups including ends of nozzle arrays is defined, and a second region in which a distribution of recording rates applied to second nozzle groups existing between the first nozzle groups is defined, wherein a plurality of different recording rates is set to the first region, a recording rate at the end of the nozzle array is a minimum recording rate in the mask pattern B, a maximum recording rate is set to the mask pattern B, and the recording rate set to the second region is larger than the minimum recording rate and is smaller than the maximum recording rate.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present disclosure relates to an inkjet printing apparatus and an inkjet printing method, and more particularly to a technique for suppressing deflection of ink droplets ejected from a print head by controlling the printing rate using a mask pattern. [Background technology]

[0002] As an example of this type of technology, Patent Document 1 discloses a mask pattern that can accommodate two types of deflection of ejected ink droplets. One of the phenomena that causes the ejection direction of ink droplets to be deflected is what is known as airflow deviation, in which an air flow is generated as the ejected ink moves, and this air flow hits the recording medium and rises, forming a vortex. This vortex then acts on ink droplets ejected from a nozzle row adjacent to the nozzle row that created the vortex, deflecting the ejection direction of the ink droplets and resulting in a deviation in the landing position of the ink droplets.

[0003] This phenomenon becomes more pronounced the higher the recording rate of the mask pattern, i.e., the higher the density of the ejection data obtained by mask processing. The second is what is known as edge deviation, in which ink droplets ejected from nozzles in the edge regions of the nozzle array are deflected toward the center of the nozzle array by the action of air currents generated as the print head scans, causing the landing position to shift. Like air current deviation, this phenomenon becomes more pronounced the higher the recording rate of the mask pattern.

[0004] In Patent Document 1, to address the above-mentioned two ejection direction deflection phenomena, two mask patterns with different printing rates at the center and the edges are used, so-called gradation masks, in which the printing rate corresponding to each ejection port of a nozzle array is high in the center of the nozzle array and gradually decreases toward the edges. Then, in a so-called multi-pass printing method, the two mask patterns are used depending on the printing duty between adjacent nozzle arrays. This applies a mask pattern corresponding to which of the two above-mentioned deflection phenomena becomes more pronounced depending on the printing duty to each adjacent nozzle array, thereby suppressing the two ejection direction deflection phenomena as a whole. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-233699 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the configuration of Patent Document 1 may be insufficient, particularly in low-pass multi-pass printing, because the print duty per scan is high. That is, regardless of which of the two mask patterns is applied, the original print duty is relatively high, so the print duty in the center of the nozzle array cannot be sufficiently reduced by mask processing. As a result, it may not be possible to simultaneously suppress the deflection phenomenon of the two ejected ink droplets.

[0007] The object of the present disclosure is to enable an inkjet printing device that performs printing using a multi-pass method to print high-quality images by suppressing end distortion at both ends of a nozzle row while also suppressing the effects of air flow distortion in the center. [Means for solving the problem]

[0008] The inkjet recording apparatus disclosed herein is an inkjet recording apparatus that performs multi-pass recording on a recording medium using a recording head equipped with a plurality of nozzle arrays, each of which has a plurality of nozzles capable of ejecting ink, and is equipped with: a mask processing means that performs mask processing on recording data for each nozzle array using a mask pattern in which a recording rate distribution for the nozzle array is set; and a recording control means that causes ink to be ejected from the nozzle arrays based on the recording data that has been masked by the mask processing means, the mask pattern having a first region that defines a recording rate distribution to be applied to a first nozzle group that includes an end of the nozzle array, and a second region that defines a recording rate distribution to be applied to a second nozzle group that exists between the first nozzle groups, and a plurality of different recording rates are set in the first region, the recording rate at the end of the nozzle array being the minimum recording rate in the mask pattern and the maximum recording rate in the mask pattern, and the recording rate set in the second region is greater than the minimum recording rate and less than the maximum recording rate. The recording head has at least two types of nozzle arrays including a first array in which nozzles of a first diameter are arranged and a second array in which nozzles of a second diameter larger than the first diameter are arranged, and the mask processing means applies the mask pattern to the second array. It is characterized by: [Effects of the Invention]

[0009] According to the present disclosure, in an inkjet printing device that performs printing using a multi-pass method, it is possible to print high-quality images by suppressing end distortion at both ends of the nozzle row while also suppressing the effects of air flow distortion in the center. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram illustrating a schematic configuration of an inkjet recording apparatus. [Figure 2] FIG. 2 is a diagram showing the configuration of a nozzle array of a print head. [Figure 3] 3A and 3B are diagrams showing the correspondence between nozzle rows and drive sections of a print head, drive signals applied to each nozzle, and flying ink droplets ejected from each nozzle. [Figure 4] FIG. 2 is a diagram illustrating the configuration of a control system of the inkjet printing apparatus. [Figure 5]FIG. 10 is a diagram illustrating a data processing process according to an embodiment. [Figure 6] 10A and 10B are diagrams illustrating the relationship between image data converted by resolution conversion processing. [Figure 7] 10A and 10B are diagrams illustrating a process of generating print data in a multi-pass printing method. [Figure 8] 3A and 3B are schematic diagrams showing the relationship between the conveyance of a recording medium during image formation and nozzles used for recording. [Figure 9] 10A and 10B are diagrams showing examples of three-pass mask patterns B and B-1 used in the first embodiment and a conventional mask pattern A. [Figure 10] 10A and 10B are diagrams illustrating deviations in landing positions of satellites of small ink droplets ejected from small nozzle arrays. [Figure 11] FIG. 10 is a diagram showing the distribution of printing rates set for 4-pass and 5-pass mask patterns in the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, preferred embodiments of the present disclosure will be specifically and in detail described with reference to the accompanying drawings.

[0012] In this specification, "recording" (sometimes called "printing") broadly refers to the formation of an image, design, pattern, etc. on a recording medium, or the processing of the medium. It does not only refer to the formation of meaningful information such as characters or figures, but also to both meaningful and insignificant information, and to whether it is visible to humans or not.

[0013] Furthermore, "recording medium" refers not only to paper used in general recording devices, but also to a wide range of materials that can accept ink, such as vinyl, cloth, plastic film, metal plates, glass, ceramics, wood, and leather.

[0014] Furthermore, the term "ink" (sometimes referred to as "liquid") should be interpreted broadly and refers to a liquid that can be applied to a recording medium to form an image, design, pattern, etc., or to process the recording medium, or to process the ink.

[0015] Furthermore, unless otherwise specified, the term "nozzle" (sometimes called "recording element") refers collectively to the ejection port, the liquid path connected to it, and the element that generates the energy used to eject ink.

[0016] First Embodiment First, the configuration of an inkjet recording apparatus (hereinafter, referred to as a recording apparatus 100) that is a representative embodiment of the present disclosure will be described.

[0017] Fig. 1(a) is a perspective view showing a schematic configuration of a recording apparatus 100, and Fig. 1(b) is a YZ cross-sectional view of a recording head 102 shown in Fig. 1(a). As shown in Fig. 1, the recording apparatus 100 includes an ink cartridge 101, a recording head 102, a conveying roller 103, an auxiliary roller 104, a paper feed roller 105, a carriage 106, a platen 107, a carriage belt 108, and a carriage shaft 109.

[0018] The ink cartridge 101 has a plurality of liquid chambers, each containing cyan (Cy), magenta (Mg), yellow (Ye), and black (Bk) ink.

[0019] The recording head 102 ejects ink droplets onto an opposing recording medium P. The recording head 102 is detachably mounted on a carriage 106 that is movable in the main scanning direction indicated by X.

[0020] The carriage 106 supports the ink cartridge 101 and the print head 102. The carriage 106 is guided by a carriage shaft 109 and the like so as to be freely movable in the main scanning direction, and is moved back and forth in the main scanning direction by a movement mechanism as printing, i.e., as ink is ejected from the print head 102. The movement mechanism is made up of a carriage motor 411 (FIG. 4), a carriage belt 108, and the like. When not printing or when a recovery operation for the print head 102 is being performed, the carriage 106 waits at a home position h, indicated by a dotted line in the figure.

[0021] The platen 107 serves to stably support the recording medium P at the recording position. The recording medium P is conveyed in a sub-scanning direction (Y direction) that intersects (orthogonal in this example) the main scanning direction (X direction) by a pair of conveying rollers 103 and auxiliary rollers 104. The conveying rollers 103 and auxiliary rollers 104 work together to rotate while holding down the recording medium P, thereby conveying the recording medium P in the +Y direction as needed. The conveying rollers 103 are driven by a conveying motor 412 (FIG. 4).

[0022] The paper feed roller 105 is driven by a paper feed motor 413 (FIG. 4) to feed the recording medium P, and also plays a role of pressing down the recording medium P, similar to the transport roller 103 and the auxiliary roller 104.

[0023] The recording device 100 forms an image on the recording medium P using a serial scan method in which carriage scanning in the ±X directions and conveyance of the recording medium P in the +Y direction are alternately repeated.

[0024] 2 is a diagram showing the configuration of the print head 102. Fig. 2(a) is a plan view of the print head 102 when viewed in the Z direction, Fig. 2(b) is an enlarged view of the area around the ejection ports of the Bk (black) column or the Ye (yellow) column, and Fig. 2(c) is an enlarged view of the area around the ejection ports of the Cy (cyan) column or the Mg (magenta) column.

[0025] As shown in Figure 2(a), the print head 102 used in this embodiment is arranged with, from left to right, a Bk column, a Cy_1 column, an Mg_1 column, a Ye column, an Mg_2 column, and a Cy_2 column. Black ink is ejected from the Bk column, yellow ink from the Ye column, cyan ink from the Cy_1 and Cy_2 columns, and magenta ink from the Mg_1 and Mg_2 columns. The Bk column and the Ye column have the same nozzle column configuration. Here, an enlarged view of the Ye column is shown in Figure 2(b) as a representative example.

[0026] As shown in FIG. 2(b), the Ye column has multiple nozzles 201 that eject 5 pl of ink, and the ink ejected from these nozzles 201 forms dots approximately 50 μm in diameter when it hits the paper. The nozzles 201 are arranged at 600 dpi intervals in the column direction (Y direction in the figure). The Ye column has two 5 pl nozzle columns, which are shifted from each other by 1200 dpi in the Y direction. Hereinafter, the left side of the Ye column in the X direction will be referred to as the L_Ev column, and the right side will be referred to as the L_Od column.

[0027] Next, we will explain the Cy and Mg columns. Each of the Cy_1, Mg_1, Cy_2, and Mg_2 columns has two nozzle rows. Each of these two columns has one large nozzle row with large-diameter nozzles and one small nozzle row with small-diameter nozzles. Here, enlarged views of the Cy_1 and Cy_2 columns are shown in Figure 2(c).

[0028] As shown in Figure 2(c), the Cy_1 and Cy_2 columns each have a large nozzle row with multiple nozzles 201 that eject 5 [pl] of ink, and a small nozzle row with multiple nozzles 202 that eject 2 [pl] of ink.

[0029] An ink volume of 5 pl ejected from nozzle 201 forms a dot approximately 50 μm in diameter when it lands on the paper. An ink volume of 2 pl ejected from nozzle 202 forms a dot approximately 35 μm in diameter when it lands on the paper.

[0030] In the in-row direction (Y direction), the large nozzle row has nozzles 201 arranged at intervals of 600 dpi. Similarly, the small nozzle row has nozzles 202 arranged at intervals of 600 dpi. The small nozzle row in the Cy_1 row and the small nozzle row in the Cy_2 row are shifted from each other by 1200 dpi in the in-row direction (Y direction).

[0031] In each of the Cy_1 and Cy_2 columns, the large nozzle array and the small nozzle array are arranged in the +Y direction relative to each other. The Y coordinate of the large nozzle array of Cy_1 is the same as the left column (L_Ev) of the Ye column in Figure 2(b). The Y coordinate of the small nozzle array is shifted 2400 dpi in the -Y direction relative to the adjacent large nozzle array. The large nozzle array of Cy_1 is called L_Ev and the small nozzle array is called M_Ev, while the large nozzle array of Cy_2 is called L_Od and the small nozzle array is called M_Od.

[0032] The two nozzle rows for black (Bk) and yellow (Ye) are both large nozzle rows that eject large ink droplets. Meanwhile, the two nozzle rows for cyan (Cy) and magenta (Mg) each include a large nozzle row and a small nozzle row that eject large ink droplets and small ink droplets, respectively. These nozzle rows are arranged symmetrically with the yellow (Ye) nozzle row at the center.

[0033] A heater (not shown) is installed directly below (in the +Z direction) each of the nozzles 201, 202 of the print head 102, and when the heater is heated, the ink directly above it bubbles, causing ink to be ejected from the nozzles 201, 202. Note that although Figures 2(b) and 2(c) show three nozzles in each row in the row direction (Y direction), in reality, for example, 256 nozzles are arranged in each row.

[0034] In a printing apparatus 100 using a print head with a large number of nozzles arranged in this manner, a large-capacity power supply is required to simultaneously drive all of the nozzles and eject ink at the same timing. For this reason, a time-division drive method is employed in which a predetermined number of heaters arranged in the print head 102 are driven sequentially within a drive cycle. Specifically, all heaters (all nozzles) in the print head 102 are divided into 16 groups, and printing is performed by slightly shifting the drive timing for each group. By using time-division drive in this manner, the number of heaters driven simultaneously is reduced, thereby reducing the power supply capacity required for the printing apparatus.

[0035] 3A and 3B are diagrams illustrating the time-division driving method, in which Fig. 3A shows a nozzle array 300 of the print head 102, Fig. 3B shows a drive signal 301 applied to each nozzle, and Fig. 3C is a diagram schematically illustrating flying ink droplets 302 ejected from each nozzle.

[0036] 3(a), the nozzle array 300 of the print head 102 consists of 256 nozzles, which are divided into 16 sections (groups) of 16 consecutive nozzles starting from the top of the figure, from section 1 to section 16. Furthermore, each of the 16 nozzles in each section belongs to one of 16 drive blocks, and during printing, the nozzles are driven sequentially in a time-divided manner by block.

[0037] In time-division driving, nozzles belonging to the same block are driven simultaneously. In the illustrated example, the 16 nozzles of nozzle row 300, nozzle numbers 1, 17, ..., 241, form the first drive block (drive block No. 1), and the 16 nozzles, nozzle numbers 5, 21, ..., 245, form the second drive block (drive block No. 2). Similarly, the 16 nozzles, nozzle numbers 16, 32, ..., 256, form the 16th drive block (drive block No. 16), and so on, with the nozzles in each section being cyclically assigned to each drive block.

[0038] In the case of time-division driving, in which drive blocks No. 1, 5, 9, 13, 2, 6, 10, 14, 3, 7, 11, 15, 4, 8, 12, and 16 are driven in this order, each heater is driven sequentially by a pulsed drive signal 301 shown in Fig. 3(b). In addition, ink droplets 302 are ejected from each nozzle in response to the drive signal, as shown in Fig. 3(c).

[0039] Next, the control system of the recording apparatus 100 will be described. 4 is a block diagram showing the configuration of a control system of the printing apparatus 100. The printing apparatus 100 includes a CPU 401, a ROM 402, a RAM 403, an I / F 404, motor drivers 406, 407, and 408, a print head driver 409, a carriage motor 411, a transport motor 412, a paper feed motor 413, and a print head 102.

[0040] The CPU 401 controls the overall operation of the recording device 100, including the recording operation, in accordance with input signals (including image data) from an external host device 414 connected via an interface (I / F) 404. The processing programs executed by the CPU 401 are stored in a ROM 402. A RAM 403 is used as a work area for temporarily storing image data being processed, etc.

[0041] The print head 102 is driven by a print head driver 409. A carriage motor 411 for moving the carriage 106 is driven by a motor driver 406. A motor driver 407 drives a conveyance motor 412 for operating the conveyance rollers 103, and a motor driver 408 drives a paper feed motor 413 for operating the paper feed rollers 105 that feed the printing medium P.

[0042] 4, a CPU 401 controls a printhead driver 409 based on an image signal input from a host device 414 to eject ink from the nozzles of a printhead 102. At the same time, the CPU 401 controls a carriage motor driver 406 to drive a carriage motor 411, which moves the carriage 106 together with the printhead 102 in the main scanning direction (X direction).

[0043] In this way, by ejecting ink from the print head 102 while moving the print head 102, an image for one print scan is printed on the print medium P. By alternately performing one print scan like this and conveying the print medium P a predetermined distance by the driving force of the convey motor 413, images are printed sequentially on the print medium P.

[0044] Next, the flow of data processing from input of image data to ejection of ink (image recording) in the recording device 100 will be described with reference to FIG.

[0045] The printing device 100 includes a data input unit 501, a color processing unit A 502, a color processing unit B 503, a tone correction processing unit 504, a quantization processing unit 505, a resolution conversion processing unit 506, a distribution processing unit 507, a mask processing unit 508, and a print data transmission unit 509.

[0046] The data input unit 501 inputs (acquires) original image data. The original image data is data of 256 gradations (0 to 255) for each of RGB obtained from an image input device such as a digital camera or scanner, or from the host device 414, and is input at a resolution of, for example, 600 dpi.

[0047] The color processing unit A502 performs a color gamut conversion process called gamut mapping. The color processing unit A502 performs color correction on the original RGB image data input by the data input unit 501 to match the characteristics of the image to be output, and converts the image data into different data (R'G'B' data).

[0048] The color processing unit B503 performs color separation processing. The color processing unit B503 converts the R'G'B' data into signals corresponding to the ink colors used by the printing device 100. In this embodiment, it is assumed that four colors of ink are used: Cy (cyan), Mg (magenta), Ye (yellow), and Bk (black). Therefore, the converted signals are converted into data C1, M1, Y1, and K1 corresponding to each ink color. Each of the data C1, M1, Y1, and K1 has 256 gradations (0 to 255) and a resolution of 300 dpi.

[0049] Specifically, the color conversion process is performed using a three-dimensional lookup table (not shown) that shows the relationship between R, G, and B input values ​​and C, M, and Y output values. For input values ​​that deviate from the table grid point values, the output value can be obtained by interpolation from the output values ​​of the surrounding table grid points. The following explanation will be given using data C1 as a representative of data C1, M1, Y1, and K1.

[0050] The tone correction processing unit 504 performs tone correction (gamma correction) on the data C1 using a tone correction table, and obtains tone-corrected data C2.

[0051] The quantization processing unit 505 performs quantization processing on the data C2 using an error diffusion method, thereby converting the data C2, which is a multi-value signal, into a binary signal with the number of gradations required for the recording device 100 to perform a recording operation, i.e., a binary signal per bit. This processing results in data C3 with two gradations (gradation levels 0 and 1) and a resolution of 300 [dpi] x 300 [dpi]. In this embodiment, the data C3 is also referred to as gradation data. The method is not limited to the error diffusion method, and a dithering method or the like may also be used.

[0052] The resolution conversion processing unit 506 obtains data C4 from the gradation data C3 through the resolution conversion process shown in FIG. 6. In this embodiment, the data C4 is also referred to as image data. The image data C4 is expanded into two gradations, "0" and "1," based on a dot arrangement pattern that determines the number and positions of dots to be arranged. In detail, the image data C4 is composed of one of two 1-bit information values, "0" and "1," at a resolution of 600 [dpi] x 600 [dpi]. As described above, the gradation data C3 has a resolution of 300 [dpi] x 300 [dpi], so the resolution of the image data C4 is higher than that of the gradation data C3.

[0053] The distribution processing unit 507 performs distribution processing on the above-mentioned binary image data C4 using a mask pattern, the details of which will be described later in Figure 9 and other figures. The distribution processing unit 507 generates binary print data C5 that determines whether or not to eject cyan ink for each pixel area in each scan (pass) in the multi-pass method. In the distribution processing, a mask pattern according to the number of passes is used, and by masking the image data C4 corresponding to the image area for one scan, print data C5 for the number of passes is generated.

[0054] The mask pattern is data in which a printing rate is determined corresponding to each ejection port of the nozzle array, and is stored in the ROM 402, RAM 403, etc. The mask processing unit 508 determines which mask pattern to apply to which nozzle array, and performs mask processing on the image data for each nozzle array using the determined mask pattern. Note that it may be determined in advance which mask pattern to apply to which nozzle array.

[0055] Similarly, print data M5 for magenta ink, print data Y5 for yellow ink, and print data K5 for black ink are also generated. This print data C5, M5, Y5, and K5 become the data for realizing the printing operation in the printing device 100.

[0056] Here, the process of generating print data after mask processing using image data and a mask pattern will be described with reference to Fig. 7. Fig. 7(a) is a diagram showing a schematic diagram of pixels 700 to 708 in a certain image area. For simplicity, the description will be given using a unit area consisting of a pixel area equivalent to nine pixels. Fig. 7(b) is a diagram showing image data corresponding to the unit area. In the example of image data shown in Fig. 7(b), all pixels are "1", so the image data is image data in which ink is ejected from all pixels.

[0057] Figures 7(c-1), (c-2), and (c-3) show mask patterns applied to the image data shown in Figure 7(b) and used in three-pass multi-pass printing. Figures 7(c-1), (c-2), and (c-3) are mask patterns corresponding to the first scan, second scan, and third scan, respectively. That is, by applying (logical AND operation) the mask pattern shown in Figure 7(c-1) to the image data shown in Figure 7(b), the print data (Figure 7(d-1)) used in the first scan is generated.

[0058] Similarly, by applying the mask pattern shown in FIG. 7(c-2) to the image data shown in FIG. 7(b), the print data (FIG. 7(d-2)) used in the second scan is generated. Also, by applying the mask pattern shown in FIG. 7(c-3) to the image data shown in FIG. 7(b), the print data (FIG. 7(d-3)) used in the third scan is generated. Here, one bit of information, either "0" or "1", is assigned to each pixel in the mask patterns shown in FIGS. 7(c-1), (c-2), and (c-3).

[0059] Figures 7(d-1), (d-2), and (d-3) are diagrams showing print data after mask processing, which is generated by applying the mask patterns shown in Figures 7(c-1), (c-2), and (c-3) to the image data shown in Figure 7(b). For example, for pixel 700 in the print data corresponding to the first scan shown in Figure 7(d-1), the pixel value of the image data is "1" and the code value of the mask pattern is "1", so a value of "1" is set, which indicates ink ejection.

[0060] Ink is ejected onto a certain image area in three scans according to the print data generated in this way and shown in Figures 7(d-1), (d-2), and (d-3). That is, in the first scan, ink is ejected onto pixels 700, 704, and 708 within the image area in accordance with the print data of Figure 7(d-1) for the 3-pixel x 3-pixel unit area shown in the figure. In the second scan, ink is ejected onto pixels 701, 705, and 706 within the image area in accordance with the print data of Figure 7(d-2). In the third scan, ink is ejected onto pixels 702, 703, and 707 within the unit area in accordance with the print data of Figure 7(d-3), completing the printing of that area.

[0061] By ejecting ink in accordance with the print data, an image corresponding to the image data shown in Figure 7(b) is formed on the print medium P. Figure 7(e) shows the logical sum of the print data in Figures 7(d-1), (d-2), and (d-3). The logical sum of the print data after mask processing matches the image data in Figure 7(b).

[0062] Returning to the explanation of Figure 5. The print data transmission unit 509 transmits the masked print data C5, M5, Y5, and K5 to the print head driver 409. The print head driver 409 converts the masked print data C5, M5, Y5, and K5 into electrical signals for driving each nozzle so that ink is ejected in accordance with the masked print data. The electrical signals generated by the print head driver 409 are transferred to each nozzle of the print head 102 at a predetermined timing. This causes each nozzle to eject ink in accordance with the electrical signals.

[0063] In this way, the print head 102 ejects ink based on print data after mask processing for each scan (each pass) in a multi-pass method in which a unit print area on the print medium P is scanned multiple times.

[0064] Figure 8 is a schematic diagram showing the relationship between the recording medium transport and the nozzles used when forming an image using the multi-pass method. Here, we will explain the nozzle row for one color, but the nozzle rows for other colors have the same relationship. Note that Figure 8 shows the case of three passes.

[0065] The nozzle groups arranged in the nozzle row 800 are divided into three in the row direction. Of the divided nozzle groups, the nozzle group including one end is referred to as a first nozzle group 801, the nozzle group in the center as a second nozzle group 802, and the nozzle group including the other end as a third nozzle group 803.

[0066] In the first scan, the first nozzle group 801 of the nozzle row 800 is used to scan the carriage 106 in the main scanning direction (X direction) over unit area a to perform printing. After this scan, the print medium P is transported in the sub-scanning direction (+Y direction) by the distance of the first nozzle group 801. For convenience, FIG. 7 shows the relative positional relationship between the nozzles and the print medium P by depicting the nozzles as moving in the -Y direction. As a result of this transport, the second nozzle group 802 comes to correspond to unit area a.

[0067] In the second scan, the first nozzle group 801 and the second nozzle group 802 of the nozzle row 800 are used, and the corresponding nozzle groups 802, 801 are used for unit areas a and b, respectively, to scan the carriage 106 in the X direction to perform printing. After this scan, the print medium P is transported in the +Y direction by the distance of the nozzle group 802, and the third nozzle group 803 is assigned to unit area a. In the third scan, all the nozzle groups 801, 802, and 803 are used to scan the carriage 106 in the X direction to perform printing on the corresponding unit areas c, b, and a. The image in unit area a is completed by these three scans.

[0068] After the third scan, the recording medium P is transported in the +Y direction by the distance of the first nozzle group 801. In the fourth scan, as in the third scan, all nozzle groups 801, 802, and 803 are used, and printing is performed by scanning the carriage 106 in the X direction for each corresponding unit area. The image in unit area b is completed by three scans, from the second to the fourth. After the fourth scan, the print medium P is transported in the +Y direction by the distance of the third nozzle group 803. In the fifth scan, the second nozzle group 802 and the third nozzle group 803 of the nozzle row 800 are used, and printing is performed by scanning the carriage 106 in the X direction. The image in unit area c is completed by three scans, from the third to the fifth.

[0069] After the fifth scan, the recording medium P is transported in the +Y direction by the distance of the second nozzle group 802. For the sixth scan, the third nozzle group 803 of the nozzle row 800 is used, and the carriage 106 is scanned in the main scanning direction (X direction) to perform printing. An image of unit area d is completed by three scans, from the fourth to the sixth. After this scan, the recording medium P is transported in the +Y direction by the distance of the third nozzle group 801. Thereafter, the recording medium P is ejected and printing is completed.

[0070] The above operation records unit areas a, b, c, and d corresponding to image data C4. No dots are placed in pixels of image data "0" as shown in the right diagram of Figure 6(a), and dots are placed in pixels of image data "1" as shown in the right diagram of Figure 6(b).

[0071] Through the above processing, it is possible to generate 1-bit print data to be used in each of a plurality of scans based on the image data and mask pattern.

[0072] Next, the mask pattern will be described. 9A and 9B are diagrams showing examples of mask patterns for three-pass multi-pass printing. Mask pattern A shown in Fig. 9A is a mask pattern according to a comparative example, in which the printing rate at the ends of the nozzle array is set lower than the printing rate at the center as a measure against end distortion.

[0073] Specifically, this mask pattern A divides the 256 nozzles in the nozzle row into approximately thirds, and the printing rates are determined corresponding to the 0th to 85th nozzles (first nozzle group 901), the 86th to 170th nozzles (second nozzle group 901), and the 171st to 255th nozzles (third nozzle group 903). Hereinafter, the mask regions corresponding to the first nozzle group 901, the second nozzle group 901, and the third nozzle group 903, respectively, will be referred to as the first region, the second region, and the first region.

[0074] In the comparative example mask pattern A shown in Figure 9(a), the printing rate in the first region is set so that it decreases from 44% at the boundary with the second region towards the ends of the nozzle row, to 12% at the ends (corresponding to nozzles 0 and 255). In the second region, the printing rate is set to a flat 44%.

[0075] Here, in this specification, the recording rate refers to the ratio of the number of printable dots determined by the mask pattern. In other words, it refers to the ratio of the number of dots that can be printed (number of printable dots) to the total number of dots corresponding to the mask pattern area. For example, in Figures 7(c-1), (c-2), and (c-3), 3 dots are allowed to be printed out of 9 dots, so the recording rate is (3 / 9) x 100 = approximately 33%. Furthermore, the relationship between the number of nozzles and the recording rate may be 1:1 or multiple:1.

[0076] 9(b) shows a mask pattern B according to the first embodiment of the present disclosure. Mask pattern B is a mask pattern that can deal with distortion due to airflow in the central portion where the recording rate is high, in addition to countering distortion at the end portions.

[0077] In mask pattern B, the printing rate set in the second area is set to be greater than the minimum printing rate in mask pattern B (corresponding to nozzles 0 and 255) and less than the maximum printing rate in mask pattern B (corresponding to nozzles 85 and 171).

[0078] In the example shown in Figure 9(b), the minimum printing rate is 12%, the maximum printing rate is approximately 50%, and the printing rate of the second region is 38%. Note that the printing rate values ​​are merely examples and are not limited to this example. In this way, the shape of the mask pattern B according to the embodiment of the present disclosure due to the printing rate is roughly a peak-valley-peak shape in the order of the first region → second region → first region.

[0079] Here, to compare mask patterns A and B, we will first explain the deviation in ink landing position in the main scanning direction (X direction) of each nozzle in a nozzle array when mask pattern A is used for all nozzle arrays of the print head 102. As printing conditions, we will use the print head 102 shown in Figure 2, and perform three-pass multi-pass printing with a print duty of 50% per scan for the Ye array (two large nozzle arrays) and a print duty of 25% for the Cy small nozzle array. The following explanation focuses on the Ye array and Cy array.

[0080] The print duty per scan of the second nozzle group 902 located at the center of the Ye column in the in-column direction (Y direction) is 50% (print duty) × 44% (printing rate of mask pattern A) = 22% after masking with mask pattern A. On the other hand, the print duty of the small nozzle columns of Cy_1 and Cy_2 is 25% for the two columns, so the print duty per scan of the center of each small nozzle column is (25% ÷ 2) × 44% = 5.5% after masking with mask pattern A.

[0081] 9(a) is used for each of the nozzle arrays Ye, Cy_1, and Cy_2, the printing rate at the ends of the nozzle arrays is set low, so the effects of end distortion can be suppressed. However, as mentioned above, the printing rate at the center of the nozzle array is high, which increases the effects of airflow on the nozzle arrays adjacent to those nozzle arrays, especially the small nozzle arrays.

[0082] Figure 10 is a graph showing the impact position deviation of satellites of small ink droplets ejected from the small nozzle array (M_Ev array) of Cy_1 array, obtained by actually printing using back-and-forth scanning under the above printing conditions. (a) shows printing in the forward direction, and (b) shows printing in the backward direction. Note that the small nozzle array (M_Ev array) of Cy_1 array is a nozzle array located a specific distance in the X(+) direction from the Ye array, which has two large nozzle arrays.

[0083] A satellite is a small ink droplet that is ejected after the main ink droplet and lands on the recording medium P after the main ink droplet. The satellite has a slow ejection speed and a small mass, making it susceptible to the influence of air currents. A satellite of a small ink droplet ejected from a small nozzle has an even smaller mass and is therefore more susceptible to the influence of air currents.

[0084] The vertical axis of the graph in Figure 10 represents the nozzle row, with nozzle number 0 (the extreme end) being in the negative Y direction (the conveyance direction of the recording medium P). The horizontal axis of the graph represents the amount of deviation in the landing position of satellite droplets ejected from each nozzle, with the negative X direction (main scanning direction) being positive. The amount of deviation is measured based on the landing position of the satellite droplet ejected from the nozzle with nozzle number 0.

[0085] As shown in Figure 10(a), during forward printing, the amount of deviation in impact position increases in the positive direction of the graph at the center of the nozzle array. This shows that the center of the nozzle array is significantly affected by the airflow. Furthermore, during backward printing in Figure 10(b), although there is some deviation in impact position, the amount of deviation is smaller than during forward printing. This shows that backward printing is less susceptible to the effects of airflow compared to forward printing. From these results, it can be seen that in the center of the nozzle array, the small nozzle array (M_Ev array) located ahead of the Ye array in the direction of travel is more susceptible to the effects of airflow.

[0086] To reduce the influence of this airflow, it is necessary to lower the print duty in the center of the nozzle array. Therefore, in this embodiment, for example, mask pattern B shown in Figure 9(b) is applied to at least one of the nozzle arrays.

[0087] Specifically, for example, mask pattern B of this embodiment is applied to column Ye. Column Ye is made up of large nozzles with large ejection volumes, with Odd and Even columns adjacent to each other and sharing a liquid chamber. Therefore, it is believed that airflows are likely to affect the centers of the other nozzle columns, particularly the center of the small nozzle column in column Cy. Therefore, mask pattern B of this embodiment is applied to column Ye.

[0088] As described above, in mask pattern B, the printing rate at the end of the nozzle row is set to the minimum value in this mask pattern B. This is to improve the effect of white streaks caused by end distortion. In addition, the printing rate at the end of the first region on the second region side is set to the maximum value in this mask pattern B. By setting the maximum printing rate in the first region, it is possible to keep the printing rate of the second region lower than the maximum value of the first region. The printing rate of the second region is set higher than the above minimum value.

[0089] Therefore, by applying mask pattern B, the printing rate of the second area can be kept lower compared to the conventional mask pattern A.

[0090] 9(c) is a diagram comparing a conventional mask pattern A (dotted line) and a mask pattern B (solid line) of this embodiment, superimposed on each other. As a countermeasure against end warping, mask pattern B keeps the recording rate at the ends of mask pattern B as low as mask pattern A, while making the change (slope) in recording rate in the first region larger than that of mask pattern A. Also, by giving mask pattern B a maximum and minimum recording rate across the entire first region, the recording rate in the center (second region) is made lower than that of mask pattern A.

[0091] In the example of Figure 9(b), the printing rate set in the first region of mask pattern B in this embodiment is a pattern that continuously increases from the ends of the nozzle row (nozzle numbers 0 and 255) towards the end of the second region. In other words, in the first region, the printing rate is set so that it gradually decreases from a printing rate of approximately 50% at the boundary with the second region towards the end of the nozzle row, and the printing rate at the ends (corresponding to nozzles numbered 0 and 255) is 12%. In the second region, the printing rate is set to a flat 38%.

[0092] For example, like mask pattern B-1 shown in Figure 9(d), the printing rate set in the first region may increase in stages (step-like) from the end of the nozzle row to the end of the second region. In other words, in mask pattern B-1, the printing rate in the first region is set so that it decreases in stages (step-like) from a printing rate of approximately 50% at the boundary with the second region to the end of the nozzle row, with the printing rate at the end (corresponding to nozzles 0 and 255) being 12%. The printing rate in the second region is set to a flat 38%.

[0093] Furthermore, in this embodiment, the number of multi-passes is set to three, but the number of corresponding passes is not limited to a three-pass mask, and a mask pattern corresponding to three or more passes may also be used.

[0094] Here, we will explain the impact position deviation of satellite droplets from the small nozzle array (M_Ev array) of Cy_1 array when mask pattern B of Figure 9(b) is used for two Ye arrays (L_Ev array and L_Od array) with large ejection volumes that can cause airflow. Note that mask pattern A of Figure 9(a) is used for the small nozzle array (M_Ev array) of Cy_1 array.

[0095] Figures 10(c) and (d) are graphs showing the impact position deviation of satellites from the small nozzle array (M_Ev array) of Cy_1 array, which is located a specific distance away from the Ye array to which mask pattern B is applied. (c) shows forward printing, and (d) shows backward printing. Note that the printing conditions, such as the printing duty, are the same as those in Figures 10(a) and (b).

[0096] In the forward printing shown in Fig. 10(c), the deviation of the landing position in the center is improved compared to Fig. 10(a). Specifically, when mask pattern A was applied to the Ye column, the deviation of the landing position was 40 [μm], but when mask pattern B was applied, the deviation of the landing position was about 20 [μm].

[0097] Therefore, the misalignment of the landing positions of the satellites of the ink droplets ejected from the small nozzle array (M_Ev array) of the Cy_1 array is improved. As a result, by lowering the printing rate in the center of the large nozzle array (second region), which was the cause of the airflow, below the maximum value in the first region, it is possible to improve the impact on the image caused by the airflow in the center, which was an issue with conventional mask pattern A.

[0098] It should be noted that the printing rate in the first region of mask pattern B is locally high (i.e., reaches a maximum value) at the boundary with the second region, but the influence of the air flow is not considered to be large.

[0099] 10, the impact position of satellites from the small nozzle array (M_Ev array) of the Cy_1 array is shifted. This is due to the positional relationship and distance between the Ye array, which uses mask pattern B, and the small nozzle array (M_Ev array) of the Cy_1 array. In other words, the inventors' simulations and experiments with an actual device revealed that the small nozzle array is effective in reducing the influence of airflow when it is positioned ahead of the large nozzle array (Ye array) that uses mask pattern B in the traveling direction. As a specific example, the ahead of the traveling direction relative to the Ye array is the forward direction for the Cy_1 array, and the backward direction for the Cy_2 array.

[0100] Furthermore, the inventors conducted simulations and experiments and found that nozzle rows (in one print head, small nozzle rows of Cy rows (M_Ev row, M_Od row)) located at a distance similar to that between the large nozzle row to which mask pattern B is applied and the print medium P are more susceptible to the effects of airflow. Therefore, it is desirable to determine the nozzle rows to which mask pattern B of the present disclosure is applied based on the positional relationship between the nozzle rows in the print head, the direction of movement of the print head, or the distance between the nozzle rows.

[0101] As described above, the inkjet recording apparatus of this embodiment can suppress the occurrence of end distortion while also suppressing the effects of airflow distortion in the center of the nozzle row. That is, by applying mask pattern B of this embodiment, it is possible to suppress the recording rate at both ends of the nozzle row, thereby preventing the occurrence of white stripes in the recorded image due to end distortion. At the same time, it is possible to suppress the recording rate in the center of the nozzle row, thereby suppressing the effects of airflow on nozzle rows adjacent in the main scanning direction.

[0102] In particular, when performing low-pass printing where the printing duty per scan is large, the use of mask pattern B of this embodiment makes it possible to suitably suppress the effects of air currents. Note that, in this case, low-pass refers to the number of passes adopted in the printing mode with the fewer passes when there are multiple printing modes with different numbers of passes, such as "clean mode" and "standard mode." For example, when printing with 7 to 8 passes in "clean mode," a number of passes less than that is considered a low-pass.

[0103] Furthermore, when using a print head with two nozzle arrays with different nozzle diameters to increase the resolution of printed images, the landing positions of small ink droplets ejected from the small-diameter nozzles, and in particular the landing positions of their satellites, are easily affected by the air currents described above. In the example of this embodiment, in a print head with two nozzle arrays, large and small, mask pattern B of this embodiment is applied to the large nozzle array. This makes it possible to minimize the landing position deviation of small ink droplets ejected from the small nozzle array, especially the center, and the landing position deviation of their satellites.

[0104] As a result, it is possible to perform high-quality printing even in low-pass printing where the printing duty per scan is high, using a print head that ejects a small amount of ink droplets from nozzles with a high integration density.

[0105] Note that the print heads and printing conditions shown in the above-described embodiments are merely examples, and the present disclosure is not limited to these examples. For example, the arrangement of the nozzle arrays and the nozzle diameters in the print head are merely examples, and other arrangements and nozzle diameters may be used. Furthermore, while an example has been shown in which the nozzle diameters are of two sizes, large and small, a print head with one type of nozzle diameter, or a print head with three or more types of nozzle diameters, may also be used. Furthermore, the distribution of the printing rate set in mask pattern B is merely an example, and mask patterns with other distributions may also be used as long as they do not deviate from the spirit of the present disclosure.

[0106] Furthermore, in the above example, an example was shown in which mask pattern B was applied to the Ye row as an example of a nozzle row having two large nozzle rows that share a liquid chamber and are adjacent to a small nozzle row, but the nozzle row to which mask pattern B is applied is not limited to this. In a print head having multiple nozzle rows with different diameters, it is desirable to apply mask pattern B to one of the large nozzle rows.

[0107] <Second embodiment> In the first embodiment, an example of three passes was described, but other numbers of passes can also be used in the same way. In the second embodiment, a four-pass mask pattern B-2 and a five-pass mask pattern B-3 will be described as examples.

[0108] FIG. 11(a) is a diagram showing the distribution of printing rates using a 4-pass mask pattern B-2, and FIG. 11(b) is a diagram showing the distribution of printing rates using a 5-pass mask pattern B-3.

[0109] 11(a), the 256 nozzles in the nozzle row are divided into approximately four equal parts, with printing rates determined for the 0th to 63rd nozzles (first nozzle group 1101), the 64th to 127th nozzles (second nozzle group 1102), the 128th to 191st nozzles (third nozzle group 1103), and the 192nd to 255th nozzles (fourth nozzle group 1104). The mask regions corresponding to the first nozzle group 1101, the second nozzle group 1102, the third nozzle group 1103, and the fourth nozzle group 1104, respectively, are referred to as the first region, the second region, the second region, and the first region.

[0110] In mask pattern B-2, the printing rate set in the second area is set to be greater than the minimum printing rate in mask pattern B-2 (corresponding to nozzles 0 and 255) and less than the maximum printing rate in mask pattern B (corresponding to nozzles 63 and 192).

[0111] 11(a), the minimum printing rate is 12%, the maximum printing rate is approximately 35%, and the printing rate of the second region is approximately 25%. Note that the printing rate values ​​are merely examples and are not limited to this example. It is sufficient that the shape resulting from the printing rates of mask pattern B-2 according to the second embodiment of the present disclosure is roughly a peak-valley-peak shape in the order of first region → second region → first region.

[0112] Furthermore, in mask pattern B-2, the printing rate at the end of the nozzle row is set to the minimum value for this mask pattern B-2. This is to improve the effect of white streaks caused by end distortion. Also, the printing rate at the end of the first region on the second region side is set to the maximum value for this mask pattern B-2. By setting the maximum printing rate within the first region, it is possible to keep the printing rate of the second region lower than the maximum value for the first region. The printing rate of the second region is set higher than the above minimum value. Therefore, by applying mask pattern B-2, it is possible to keep the printing rate of the second region lower compared to conventional mask pattern A.

[0113] 11(b), the 256 nozzles in the nozzle row are divided into approximately five equal parts, with printing rates determined for the 0th to 50th nozzles (first nozzle group 1111), the 51st to 101st nozzles (second nozzle group 1112), the 102nd to 153rd nozzles (third nozzle group 1113), the 154th to 204th nozzles (fourth nozzle group 1114), and the 205th to 255th nozzles (fifth nozzle group 1115). The mask regions corresponding to the first nozzle group 1111, the second nozzle group 1112, the third nozzle group 1113, the fourth nozzle group 1114, and the fifth nozzle group 1115, respectively, are referred to as the first region, the second region, the second region, the second region, and the first region.

[0114] In mask pattern B-3, the printing rate set in the second area is set to be greater than the minimum printing rate in mask pattern B-3 (corresponding to nozzles 0 and 255) and less than the maximum printing rate in mask pattern B (corresponding to nozzles 50 and 205).

[0115] 11(b), the minimum printing rate is 12%, the maximum printing rate is approximately 28%, and the printing rate of the second region is approximately 20%. Note that the printing rate values ​​are merely examples and are not limited to this example. It is sufficient that the shape resulting from the printing rates of mask pattern B-3 according to the second embodiment of the present disclosure is roughly a peak-valley-peak shape in the order of first region → second region → first region.

[0116] Furthermore, in mask pattern B-2, the printing rate at the end of the nozzle array is set to the minimum value in this mask pattern B-3. This is to improve the effect of white streaks caused by end distortion. Also, the printing rate at the end of the first region on the second region side is set to the maximum value in this mask pattern B-3. By setting the maximum printing rate within the first region, it is possible to keep the printing rate of the second region lower than the maximum value of the first region. Also, the printing rate of the second region is set higher than the above minimum value. Therefore, by applying mask pattern B-3, it is possible to keep the printing rate of the second region lower compared to conventional mask pattern A.

[0117] In the example shown in Fig. 11, the printing rates set in the first regions of mask patterns B-2 and B-3 are patterned so that they increase continuously from the ends of the nozzle row (corresponding to nozzles no. 0 and 255) towards the ends of the second region. In other words, in the first region, the printing rate gradually decreases from the boundary with the second region towards the ends of the nozzle row, and the printing rate at the ends (corresponding to nozzles no. 0 and 255) is set to 12%. In the second region, the printing rate is set to be flat.

[0118] Furthermore, mask patterns B-2 and B-3 may be a pattern in which the printing rate set in the first region increases in stages (step-like) from the end of the nozzle row toward the end of the second region, as in mask pattern B-1 shown in Figure 9(d) of the first embodiment. In other words, in the first region, the printing rate decreases in stages (step-like) from the boundary with the second region toward the end of the nozzle row, and the printing rate is set so that the printing rate at the end (corresponding to nozzles 0 and 255) is 12%. In the second region, the printing rate is set to be flat.

[0119] When using a print head in which nozzle rows with different nozzle diameters (large nozzle row, small nozzle row) are arranged, such as print head 102 shown in Figure 2, it is preferable to apply mask patterns B-2 and B-3 to the large nozzle row that is in a specific positional relationship with the small nozzle row.

[0120] As described above, according to the second embodiment, it is possible to apply the mask pattern according to the present disclosure even when printing is performed with a pass count other than 3. This makes it possible to suppress the edge distortion that occurs in printing with a low pass count, while at the same time suppressing the effects of airflow distortion in the center of the nozzle array.

[0121] While preferred embodiments of the present disclosure have been described above with reference to the accompanying drawings, the present disclosure is not limited to such examples. It is clear that those skilled in the art can conceive of various modifications or alterations within the scope of the technical ideas disclosed herein, and it is understood that such modifications also fall within the technical scope of the present disclosure.

[0122] The disclosure of the above-described embodiment includes the following configurations. (Configuration 1) An inkjet recording apparatus that performs recording on a recording medium by a multi-pass method using a recording head having a plurality of nozzle arrays in which a plurality of nozzles capable of ejecting ink are arranged, a mask processing means for performing mask processing on print data for each nozzle array using a mask pattern in which a distribution of print rates in the nozzle array is set; a print control unit that ejects ink from the nozzle array based on the print data that has been masked by the mask processing unit, The mask pattern is a first region that defines a distribution of recording rates to be applied to a first nozzle group that includes an end of the nozzle row, and a second region that defines a distribution of recording rates to be applied to a second nozzle group that exists between the first nozzle groups, a plurality of different printing rates are set in the first area, and the printing rate at the end of the nozzle array is set to be the minimum printing rate in the mask pattern and the maximum printing rate in the mask pattern; The recording rate set in the second area is greater than the minimum recording rate and less than the maximum recording rate. An inkjet recording apparatus characterized by:

[0123] (Configuration 2) 2. The inkjet recording apparatus according to configuration 1, wherein the maximum recording rate is set at an end of the first area on the side of the second area.

[0124] (Configuration 3) In the mask pattern, 3. The inkjet recording apparatus according to claim 1, wherein the recording rate set in the first region increases continuously from the end of the nozzle row toward the end of the second region.

[0125] (Configuration 4) In the mask pattern, 3. The inkjet recording apparatus according to claim 1, wherein the recording rate set in the first region increases stepwise from the end of the nozzle row toward the end of the second region.

[0126] (Configuration 5) the recording head has at least two types of nozzle rows, including a first row in which nozzles having a first diameter are arranged, and a second row in which nozzles having a second diameter larger than the first diameter are arranged; The mask processing means 5. The inkjet recording apparatus according to any one of configurations 1 to 4, wherein the mask pattern is applied to the second row.

[0127] (Configuration 6) Furthermore, in the inkjet recording apparatus according to configuration 5, when a plurality of the second rows sharing a common liquid chamber are arranged in series, the mask pattern is applied to the second rows.

[0128] (Configuration 7) The inkjet recording apparatus according to configuration 5, wherein the first nozzle row to which the mask pattern is applied is located ahead of the first nozzle row in the direction of travel of the recording head.

[0129] (Configuration 8) The inkjet recording apparatus according to configuration 5, characterized in that when the first row is present at a position approximately the same distance as the second row and the recording medium, the mask pattern is applied to the second row.

[0130] (Configuration 9) An inkjet recording method for recording on a recording medium by a multi-pass method using a recording head having a plurality of nozzle arrays in which a plurality of nozzles capable of ejecting ink are arranged, comprising: a step of performing mask processing on print data for each nozzle array using a mask pattern in which a distribution of print rates in the nozzle array is set; and ejecting ink from the nozzle array based on the masked print data, The mask pattern is a first region that defines a distribution of recording rates to be applied to a first nozzle group that includes an end of the nozzle row, and a second region that defines a distribution of recording rates to be applied to a second nozzle group that exists between the first nozzle groups, a plurality of different printing rates are set in the first area, and the printing rate at the end of the nozzle array is set to be the minimum printing rate in the mask pattern and the maximum printing rate in the mask pattern; The recording rate set in the second area is greater than the minimum recording rate and less than the maximum recording rate. An inkjet recording method comprising:

Claims

1. An inkjet recording apparatus that performs recording on a recording medium by a multi-pass method using a recording head having a plurality of nozzle arrays in which a plurality of nozzles capable of ejecting ink are arranged, a mask processing means for performing mask processing on print data for each nozzle array using a mask pattern in which a distribution of print rates in the nozzle array is set; a print control unit that ejects ink from the nozzle array based on the print data that has been masked by the mask processing unit, The mask pattern is a first region that defines a distribution of recording rates to be applied to a first nozzle group that includes an end of the nozzle row, and a second region that defines a distribution of recording rates to be applied to a second nozzle group that exists between the first nozzle groups, a plurality of different printing rates are set in the first area, and the printing rate at the end of the nozzle array is set to be the minimum printing rate in the mask pattern and the maximum printing rate in the mask pattern; the recording rate set in the second area is greater than the minimum recording rate and less than the maximum recording rate; the recording head has at least two types of nozzle arrays, including a first array in which nozzles of a first diameter are arrayed, and a second array in which nozzles of a second diameter larger than the first diameter are arrayed; The mask processing means Applying the mask pattern to the second row An inkjet recording apparatus characterized by:

2. 2. The inkjet printing apparatus according to claim 1, wherein the maximum printing rate is set at an end of the first area on the side of the second area.

3. In the mask pattern, 3. The inkjet recording apparatus according to claim 2, wherein the recording rate set in the first region increases continuously from the end of the nozzle row toward the end of the second region.

4. In the mask pattern, 3. The inkjet recording apparatus according to claim 2, wherein the recording rate set in the first region increases stepwise from an end of the nozzle row toward an end of the second region.

5. 5. The inkjet recording apparatus according to claim 1, further comprising: a mask pattern that is applied to a plurality of second rows that share a common liquid chamber and are arranged in series.

6. 5. The inkjet recording apparatus according to claim 1, wherein the first nozzle row to which the mask pattern is applied is positioned ahead of the first nozzle row in the direction of travel of the recording head.

7. 5. An inkjet recording apparatus according to claim 1, wherein the mask pattern is applied to the second row when the first row is located at a position approximately the same distance as the second row and the recording medium.

8. An inkjet recording method for recording on a recording medium by a multi-pass method using a recording head having a plurality of nozzle arrays in which a plurality of nozzles capable of ejecting ink are arranged, comprising: a step of performing mask processing on print data for each nozzle array using a mask pattern in which a distribution of print rates in the nozzle array is set; and ejecting ink from the nozzle array based on the masked print data, The mask pattern is a first region that defines a distribution of recording rates to be applied to a first nozzle group that includes an end of the nozzle row, and a second region that defines a distribution of recording rates to be applied to a second nozzle group that exists between the first nozzle groups, a plurality of different printing rates are set in the first area, and the printing rate at the end of the nozzle array is set to be the minimum printing rate in the mask pattern and the maximum printing rate in the mask pattern; the recording rate set in the second area is greater than the minimum recording rate and less than the maximum recording rate; the recording head has at least two types of nozzle arrays, including a first array in which nozzles of a first diameter are arrayed, and a second array in which nozzles of a second diameter larger than the first diameter are arrayed; The mask pattern is applied to the second column. An inkjet recording method comprising:

Images