Inkjet recording apparatus and inkjet recording method

Abstract

An inkjet recording device 1 comprises a control unit 40 that controls the ejection of ink by recording heads 21Y, 21M, 21C, 21K and the ejection of a reaction liquid by a recording head 21Pr. The control unit 40 controls the ejection of ink and the ejection of the reaction liquid so that the printing progress rate of the reaction liquid in each of a series of operations becomes higher than the printing progress rate of ink in a printing area where at least the ejection of ink is performed multiple times by performing a series of operations multiple times in which the recording heads 21Pr, 21Y, 21M, 21C, 21K and a recording medium P are made to move relative to each other in a secondary scanning direction orthogonal to a main scanning direction after causing the recording heads 21Y, 21M, 21C, 21K, the recording head 21Pr, and the recording medium P to move relative to each other in the main scanning direction while causing ink and / or the reaction liquid to be ejected onto the recording medium P.

Description

[Technical Field]

[0001] The present invention relates to an inkjet recording apparatus and an inkjet recording method. [Background technology]

[0002] Conventionally, in the field of inkjet recording devices, a method has been known in which a reactive liquid (primer ink) is ejected before ejecting color ink, and the color ink is fixed on the recording medium immediately after printing, thereby preventing color bleeding, liquid concentration, etc. For example, Patent Document 1 discloses an inkjet printing device in which, with the aim of ensuring a reaction between a printability improving liquid (reactive liquid) and the ink colorant, after ejecting a printability improving liquid from a liquid ejection unit, ink is ejected from an ink ejection unit a certain time later, for example, within 500 ms. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 8-281931 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the inkjet printing device disclosed in Patent Document 1 does not anticipate cases where an image is divided and printed using a multi-pass printing method, and depending on the method for dividing the image, there is a risk of generating areas where the reaction liquid is printed after the color ink, which can result in problems such as color bleeding and liquid shifting, which can degrade image quality.

[0005] The present invention has been made in view of the above-mentioned problems, and has an object to suppress deterioration of image quality in an area that is printed multiple times using a multi-pass printing method. [Means for solving the problem]

[0006] In order to solve the above problem, the invention described in claim 1 is: an inkjet recording device that forms an image in which ink is fixed on a recording medium by repeating a series of operations in which a first recording head having an ink ejection unit that ejects ink onto a recording medium, a second recording head having a reaction liquid ejection unit that ejects reaction liquid to fix the ink ejected onto the recording medium, and the recording medium are moved relatively in a first direction to eject ink and / or reaction liquid onto the recording medium, and then the first and second recording heads and the recording medium are moved relatively in a second direction perpendicular to the first direction, a control unit that controls the ejection of ink by the first recording head and the ejection of reaction liquid by the second recording head; The control unit controls the ejection of ink by the first recording head and the ejection of reaction liquid by the second recording head so that a printing progress rate of the reaction liquid by the second recording head for each of the series of operations is higher than a printing progress rate of ink by the first recording head in a printing region where ink has been ejected a plurality of times by at least the first recording head by performing the series of operations a plurality of times. death, the printing area is an area that becomes a joint between the ends in the second direction of an image forming area where an image is formed by one of the series of operations, The number of times of the series of actions is set to be greater in the region that becomes the joint than in other regions. It is characterized by:

[0007] The invention described in claim 2 is the inkjet recording apparatus described in claim 1, the control unit controls the ejection of ink by the first recording head and the ejection of reaction liquid by the second recording head so that the ejection of reaction liquid by the second recording head is performed before the ejection of ink by the first recording head in a printing region where the ejection of ink by the first recording head is performed multiple times. It is characterized by:

[0008] The invention described in claim 3 is the inkjet recording apparatus described in claim 1 or 2, the printing area is an area where the reaction liquid is ejected multiple times by the second recording head by performing the series of operations multiple times; It is characterized by:

[0009] The invention described in claim 4 is the inkjet recording apparatus described in any one of claims 1 to 3, the first recording head and the second recording head are each disposed such that the ink ejection unit and the reaction liquid ejection unit are parallel to each other in the first direction; the control unit controls the ejection of ink by the first recording head and the ejection of reaction liquid by the second recording head so that at least a part of the reaction liquid and the ink can be ejected onto the same printing area by at least one of the series of operations. It is characterized by:

[0011] Claim 5 The invention described in claims 1 to 4 In the inkjet recording apparatus according to any one of the above items, the control unit changes a nozzle usage rate of the ink ejection unit in accordance with a position of the area in the second direction when the ink is ejected a plurality of times in the area where the first recording head ejects the ink a plurality of times. It is characterized by:

[0012] Claim 6 The invention described in claims 1 to 5 In the inkjet recording apparatus according to any one of the above items, the reaction liquid and the ink are each adjusted so that the surface tension of the reaction liquid ejected from the reaction liquid ejection unit is lower than the surface tension of the ink ejected from the ink ejection unit; It is characterized by:

[0013] Claim 7 The invention described in claims 1 to 6 In the inkjet recording apparatus according to any one of the above items, the control unit controls the ejection of the reaction liquid by the second recording head so that a maximum ejection amount per unit area of ​​the reaction liquid ejected from the reaction liquid ejection unit increases when the recording medium is an absorbent substrate compared to when the recording medium is a non-absorbent substrate. It is characterized by:

[0014] In order to solve the above problem, the following claims are provided: 8 The invention described in an inkjet recording device that forms an image in which ink is fixed on a recording medium by repeating a series of operations in which a first recording head having an ink ejection unit that ejects ink onto a recording medium, a second recording head having a reaction liquid ejection unit that ejects reaction liquid to fix the ink ejected onto the recording medium, and the recording medium are moved relatively in a first direction to eject ink and / or reaction liquid onto the recording medium, and then the first and second recording heads and the recording medium are moved relatively in a second direction perpendicular to the first direction, a control unit that controls the ejection of ink by the first recording head and the ejection of reaction liquid by the second recording head; The control unit controls the ejection of ink by the first recording head and the ejection of reaction liquid by the second recording head so that a printing progress rate of the reaction liquid by the second recording head for each of the series of operations is higher than a printing progress rate of ink by the first recording head in a printing region where ink has been ejected a plurality of times by at least the first recording head by performing the series of operations a plurality of times. death, the printing area is an area that becomes a joint between the ends in the second direction of an image forming area where an image is formed by one of the series of operations, The number of times of the series of actions is set to be greater in the region that becomes the joint than in other regions. It is characterized by: [Effects of the Invention]

[0015] According to the present invention, it is possible to suppress deterioration of image quality in an area that is printed multiple times using a multi-pass printing method. [Brief explanation of the drawings]

[0016] [Figure 1]1 is a schematic diagram illustrating a schematic configuration of an inkjet recording apparatus according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram showing the ink ejection surface side of a head unit attached to a carriage. [Figure 3] FIG. 2 is a block diagram showing the main functional configuration of the inkjet printing apparatus. [Figure 4A] FIG. 10 is a diagram showing an example of a print result when an image is recorded without performing seam correction. [Figure 4B] FIG. 10 is a diagram showing an example of a print result when an image is recorded without performing seam correction. [Figure 5] 10A and 10B are diagrams illustrating an example of a print result when an image is printed after seam correction is performed. [Figure 6] 10 is a graph showing the nozzle usage rate corresponding to each recording element when printing is performed at a seam. [Figure 7] 10A and 10B are diagrams showing examples of print results when the image allocation at the joint portion is made different between the reaction liquid and the ink. [Figure 8] FIG. 10 is a diagram showing an example of a print result when the image allocation at the joint portion is the same for reaction liquid and ink. [Figure 9] 10A and 10B are diagrams illustrating an example of a print result when image allocation according to the present embodiment is adopted in a seam portion. [Figure 10] FIG. 10 is a diagram showing an example of a printing state in which the image allocation when printing the letter "B" at the joint portion is the same for both the reaction liquid and the ink. [Figure 11] FIG. 10 is a diagram showing an example of a printing state when the image allocation when printing the letter "B" at the joint portion is made different between the reaction liquid and the ink. [Figure 12] FIG. 10 is a diagram showing an example of a printing mode in the present embodiment when printing a letter image of "B" at a seam portion. [Figure 13A] 10 is a graph showing the nozzle usage rate corresponding to each recording element when main scanning operations are performed each time (1st to 3rd times) at a joint. [Figure 13B]10 is a graph showing the nozzle usage rate corresponding to each recording element when main scanning operations are performed each time (1st to 3rd times) at a joint. [Figure 13C] 10 is a graph showing the nozzle usage rate corresponding to each recording element when main scanning operations are performed each time (1st to 3rd times) at a joint. [Figure 14] FIG. 10 is a diagram showing an example of a printing mode in which color ink is used in an area other than a seam. [Figure 15] FIG. 10 is a diagram showing an example of a printing mode for a reaction liquid in an area other than a seam. [Figure 16] FIG. 10 is a diagram showing an example of a printing pattern in which the same pixel line is printed multiple times not only with color ink but also with reaction liquid. [Figure 17] FIG. 10 is a diagram showing an example of a printing pattern in which the same pixel line is printed multiple times not only with color ink but also with reaction liquid. [Figure 18] FIG. 10 is a diagram showing an example of a printing mode in this embodiment when printing a character image of "B" in an area other than the seam. [Figure 19] FIG. 2 is a diagram illustrating an example of the arrangement of a head unit. BEST MODE FOR CARRYING OUT THE INVENTION

[0017] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0018] FIG. 1 is a schematic diagram showing the general configuration of an inkjet recording apparatus 1 according to an embodiment of the present invention. The inkjet recording device 1 includes a transport unit 10 that transports the recording medium P in a sub-scanning direction (Y direction (second direction) in Figure 1), a carriage 200 on which head units 20Pr, 20Y, 20M, 20C, and 20K (also simply referred to as head units 20) are mounted, each having a plurality of recording heads 21Pr, 21Y, 21M, 21C, and 21K (see Figure 2) (also simply referred to as recording heads 21) that eject ink, a main scanning unit 30 that scans the carriage 200 in a main scanning direction (X direction (first direction) in Figure 1) that intersects (orthogonal in this example) the sub-scanning direction, a control unit 40 (Figure 3) that controls the overall operation of each unit of the inkjet recording device 1, an image processing unit 50, an ink receiving unit 60, and the like. Here, the recording head 21Pr (second recording head) is a recording head that ejects a reaction liquid that fixes the ink (color ink) ejected by the recording heads 21Y, 21M, 21C, and 21K (first recording heads) onto the recording medium P.

[0019] The transport unit 10 includes a drive roller 11a, a driven roller 11b, a drive motor 12, and a transport belt 13. The drive roller 11a and the driven roller 11b rotate about a rotation axis extending in the main scanning direction, causing the transport belt 13 to move around the drive roller 11a and the driven roller 11b. The drive roller 11a rotates by an angle proportional to the rotation amount of the drive motor 12 attached to one end of the drive roller 11a. The transport belt 13, with the recording medium P placed on its upper surface, moves around the drive roller 11a and the driven roller 11b, thereby transporting the recording medium P in the sub-scanning direction. The drive motor 12 rotates the drive roller 11a under the control of the control unit 40 so that the recording medium P is transported a predetermined transport distance in the sub-scanning direction at a predetermined timing. The transport unit 10 also includes a rotary encoder (not shown) that detects the rotation angle of the drive roller 11 a and transmits the detection result to the control unit 40 . As the recording medium P, various media can be used, such as paper, fabric, or sheet-like resin, on whose surface the ejected ink (color material) can be fixed.

[0020] FIG. 2 is a schematic diagram showing the ink ejection surface side of the head unit 20 attached to the carriage 200. As shown in FIG. Five head units 20 are attached to the carriage 200. The head units 20 eject ink onto a recording medium P placed on the conveyor belt 13 to record an image. In this embodiment, five head units 20Pr, 20Y, 20M, 20C, and 20K corresponding to the reaction liquid and the four colors of ink (colorant inks), yellow (Y), magenta (M), cyan (C), and black (K), respectively, are attached to the carriage 200 and arranged at predetermined intervals in this order from the +X direction side. The head unit 20Y corresponding to yellow ink has a recording head 21Y attached to a mounting member, a drive circuit (not shown) provided in the recording head 21Y that supplies a drive voltage waveform to the recording head 21Y, and a drive control circuit (not shown) that controls the operation of the drive circuit. The drive control circuit supplies pixel data included in image data relating to the image to be recorded to the drive circuit, causing the drive circuit to output a drive voltage waveform corresponding to the pixel data. The head unit 20Pr corresponding to the reaction liquid and the head units 20M, 20C, and 20K corresponding to magenta, cyan, and black inks similarly have recording heads 21Pr, 21M, 21C, and 21K, drive circuits, and drive control circuits, respectively. The drive control circuits and drive circuits provided in each head unit 20 constitute a drive unit 25 (see FIG. 3).

[0021] The recording head 21 has a plurality of recording elements 22. Each recording element 22 includes a pressure chamber that stores ink, a piezoelectric element provided on the wall of the pressure chamber, and a nozzle. When a drive voltage waveform is supplied from the drive circuit of the recording head 21 to the piezoelectric element, the pressure in the pressure chamber changes in accordance with the drive voltage waveform, and ink is ejected from a nozzle communicating with the pressure chamber. The drive control circuit of the drive unit 25 causes the drive circuit to output a drive voltage waveform to the recording elements 22, causing the nozzle of the recording element 22 to perform an ejection operation in which an amount of ink is ejected according to pixel data from the nozzle, or a non-ejection operation in which ink is not ejected according to the pixel data. The nozzles of the recording elements 22 have openings provided on the ink ejection surface of the head unit 20 that faces the conveyor belt 13. Fig. 2 is a schematic diagram showing the ink ejection surface side of the head unit 20 attached to the carriage 200, and some of the openings of the nozzles included in the recording elements 22 are drawn in a circular shape.

[0022] In each head unit 20, a plurality of recording elements 22 of the recording head 21 are arranged in the sub-scanning direction to form a long head unit 20. These recording heads 21 are arranged in parallel in the main scanning direction. This makes it possible to print the reaction liquid and four colors of ink (color inks), yellow (Y), magenta (M), cyan (C), and black (K), in the same printing area with a single scan of the carriage 200 in the main scanning direction. Note that in this embodiment, each head unit 20 is provided with a corresponding recording head, but it is also possible to provide recording heads 21 for the reaction liquid and four colors of ink (color inks), yellow (Y), magenta (M), cyan (C), and black (K), in one head unit.

[0023] Here, it is preferable to adjust the reaction liquid and the four color inks so that the surface tension of the reaction liquid ejected from the nozzles of the recording element 22 is lower than the surface tension of the four color inks. For example, the surface tension of the reaction liquid is set to 20 mN / m, and the surface tension of the four color inks is set to 30 mN / m. This makes it possible to wet and spread the reaction liquid over the entire recording medium P with an ejection volume smaller than that of the four color inks. For example, when the recording medium P is a non-absorbent substrate, the maximum ejection volume of the reaction liquid per unit area is 1.4 ml / m. 2 The maximum ejection volume of the four colors of ink per unit area is 9.0 ml / m 2If this is the case, ejecting a maximum of approximately 15% of the reaction liquid relative to the four color inks will allow the reaction liquid to sufficiently wet and spread over the recording medium P. On the other hand, if the recording medium P is an absorbent substrate such as paper, the reaction liquid is more likely to be absorbed by the recording medium P than if it were a non-absorbent substrate, so it is necessary to increase the maximum ejection amount of the reaction liquid per unit area. For example, if the recording medium P is an absorbent substrate, the maximum ejection amount of the reaction liquid per unit area is 3.6 ml / m 2 The maximum ejection volume of the four colors of ink per unit area is 12.0 ml / m 2 In this case, if a maximum of about 30% of the reaction liquid is ejected relative to the four color inks, the reaction liquid can be sufficiently wetted and spread over the recording medium P.

[0024] The main scanning unit 30 includes a pair of carriage rails 31 that extend in the main scanning direction and are arranged so as to straddle the conveyor belt 13. A carriage 200 is attached to the pair of carriage rails 31 so as to be able to move back and forth along the main scanning direction. More specifically, support parts 201 extending from both ends of the carriage 200 in the sub-scanning direction are mounted on the carriage rails 31, and the support parts 201 of the carriage 200 are configured to slide on the carriage rails 31 in the main scanning direction by a linear motor (not shown). The main scanning unit 30 also includes a linear encoder (not shown) that detects the position of the carriage 200 in the main scanning direction and transmits the detection result to the control unit 40 .

[0025] The ink receiving section 60 is a tray that receives ink that is not used to record an image on the recording medium P and that is ejected from the recording elements 22 of the head unit 20 located above the ink receiving section 60. In the inkjet recording device 1, in order to prevent problems such as a decrease in image quality or ejection failure due to an increase in ink viscosity in the nozzles of the recording elements 22 that have a low ink ejection frequency, a discharge operation is performed in which ink is ejected from the recording elements 22 of the head unit 20 into the ink receiving section 60 at a predetermined timing during the image recording process or during a period when the image recording process is not being performed. Note that a wiping section that wipes the ink ejection surface of the head unit 20 located above the ink receiving section 60 with cleaning liquid may also be provided.

[0026] FIG. 3 is a block diagram showing the main functional configuration of the inkjet recording apparatus 1. As shown in FIG. The inkjet recording apparatus 1 includes a control unit 40 having a CPU (Central Processing Unit) 41, RAM (Random Access Memory) 42, ROM (Read Only Memory) 43, and storage unit 44, an image processing unit 50, an interface 101, the above-mentioned conveyance unit 10, the drive unit 25 of the head unit 20, and the main scanning unit 30. The CPU 41 is connected to the RAM 42, ROM 43, storage unit 44, conveyance unit 10, drive unit 25, main scanning unit 30, image processing unit 50, and interface 101 via a bus 102.

[0027] The CPU 41 performs various arithmetic processing and also performs overall control of the overall operation of the inkjet recording apparatus 1. For example, the CPU 41 outputs a control signal to the main scanning unit 30, causing the main scanning unit 30 to move the carriage 200 in the main scanning direction at a predetermined timing and speed. The CPU 41 also performs main scanning control by outputting a control signal and part of image data to a drive control circuit of the drive unit 25 while moving the carriage 200 in the main scanning direction, causing the drive control circuit to output a drive waveform signal corresponding to the image data from the drive circuit to the recording elements 22, thereby causing the recording elements 22 to eject ink and reaction liquid. The CPU 41 also performs sub-scanning control by outputting a control signal at a predetermined timing to the drive motor 12 of the transport unit 10, causing the transport unit 10 to transport the recording medium P a predetermined distance in the sub-scanning direction.

[0028] The RAM 42 provides a working memory space for the CPU 41 and stores temporary data. The RAM 42 may include a non-volatile memory.

[0029] The ROM 43 stores various control programs and setting data executed by the CPU 41. The setting data includes mask pattern data, etc. Note that the ROM 43 may be replaced by a rewritable nonvolatile memory such as an EEPROM (Electrically Erasable Programmable Read Only Memory) or a flash memory.

[0030] The storage unit 44 is configured with a DRAM (Dynamic Random Access Memory) or the like, and stores job information including image data input from the external device 2 to the control unit 40 via the interface 101. Note that this image data and the like may also be stored in the RAM 42.

[0031] The image processing unit 50 performs rasterization, color conversion, tone correction, halftone processing, etc. on the image data stored in the storage unit 44 as needed, and stores the processed data in the storage unit 44 .

[0032] The interface 101 is a means for transmitting and receiving data to and from the external device 2, and is configured from any one of various serial interfaces, various parallel interfaces, or a combination of these.

[0033] The external device 2 is, for example, a personal computer, and supplies image data of an image to be recorded by the inkjet recording apparatus 1 to the control unit 40 via an interface 101.

[0034] Next, an image recording operation for recording an image on the recording medium P by the inkjet recording apparatus 1 will be described. In this image recording operation, when an image is recorded on the recording medium P, a main scanning operation in which ink is ejected from a group of recording elements (plurality of recording elements 22) onto the recording medium P while moving the head unit 20 in the main scanning direction, and a sub-scanning operation in which the recording medium P is transported in the sub-scanning direction are alternately performed to record the image. Furthermore, in each main scanning operation, in order to suppress dot spreading, liquid misalignment, color bleeding, and the like that occur when the color ink is printed before the reactive liquid in the area that forms the joint in the sub-scanning direction at the edge of the image formation area where the image is formed by each main scanning operation, the printing progress rate of the reactive liquid for each main scanning operation is higher than the printing progress rate of the ink (color ink), as described below. Here, the printing progress rate refers to the progress rate until printing is completed (until the final image is formed) in an area where ink (including reactive liquid) is printed multiple times. More specifically, the printing progress rate is the ratio of printed pixels to the total number of pixels to be printed.

[0035] In the following description, the main scanning operation of ejecting ink (including reaction liquid) from the recording element group onto the recording medium P while moving the head unit 20 in the main scanning direction may be referred to as a "pass," but the "pass" referred to here refers only to the outgoing path of movement in the main scanning direction. That is, in this embodiment, on the outgoing path of movement in the main scanning direction, reaction liquid is ejected and ink is also ejected, and on the return path of movement in the main scanning direction, the head unit 20 is simply returned without ejecting reaction liquid or ink.

[0036] Before describing the details of the image recording operation, an example of a print result obtained when images are recorded without overlapping in the seam area, i.e., without seam correction, will be described with reference to FIG. 4. FIG. 4A shows an example of a print result obtained when the feed accuracy of the recording medium P in the sub-scanning direction is insufficient, and FIG. 4B shows an example of a print result obtained when there is uneven ejection from each nozzle in the head unit 20. Here, the seam refers to the seam between adjacent print areas (bands) aligned in the sub-scanning direction (see FIG. 4). In a case where this print area (band) is formed through multiple passes (e.g., four passes) (see FIG. 18), the seam refers to the seam between the area printed in the fourth pass (last pass) of one print area and the area printed in the first pass (first pass) of another print area adjacent to the one print area. Note that FIG. 4 uses the head unit 20K corresponding to black (K) ink as an example.

[0037] As shown in Result Example 1 of FIG. 4A, if the feeding accuracy of the recording medium P in the sub-scanning direction is insufficient, for example, if the recording medium P is transported at a feed amount less than the preset feed amount, a part of the image of the first pass and a part of the image of the second pass will overlap, resulting in a high image density at the joint between the images of the first and second passes. On the other hand, as shown in Result Example 2 of FIG. 4A, if the feeding accuracy of the recording medium P in the sub-scanning direction is insufficient, for example, if the recording medium P is transported at a feed amount greater than the preset feed amount, a gap will appear between the images of the first and second passes, resulting in a low image density at the joint between the images of the first and second passes. Furthermore, as shown in FIG. 4B, if there is uneven ejection from each nozzle in the head unit 20K, a difference in density will occur at the joint between the images of the first and second passes. It should be noted that the image allocation for the first pass and the image allocation for the second pass when images are printed without performing seam correction as described above are assumed to be the same.

[0038] Next, an example of a print result when seam correction is performed to eliminate problems that occur when an image is recorded without seam correction will be described with reference to Fig. 5. Fig. 5 is a diagram showing an example of a print result when seam correction is performed. Note that Fig. 5 uses head unit 20K corresponding to black (K) ink as an example.

[0039] As shown in Figure 5, in the overlapping areas of the first and second pass images, i.e., the areas subject to seam correction, printing is performed with the print target pixels thinned out. Specifically, in the first pass printing, the thinning rate of the print target pixels increases from downstream to upstream in the sub-scanning direction in the seam area, while in the second pass printing, the thinning rate of the print target pixels increases from upstream to downstream in the sub-scanning direction in the seam area. This makes it possible to prevent the image density from becoming too dark or too light in the seam area, making the seam less noticeable.

[0040] 6, in the first pass of printing, the nozzle usage rate of each nozzle arranged between the downstream end (left) of head unit 20K in the sub-scanning direction and the position where it approaches the seam is set to 100%. Also, in the first pass of printing, the nozzle usage rate of each nozzle arranged between the position where it approaches the seam and the upstream end (right) of head unit 20K in the sub-scanning direction is gradually reduced from the position where it approaches the seam toward the upstream end so that the nozzle usage rate of the nozzles arranged at the upstream end is 0%. On the other hand, in second-pass printing, the nozzle usage rate of each nozzle arranged between the upstream end (right) of head unit 20K in the sub-scanning direction and the position where it approaches the seam is set to 100%. Also, in second-pass printing, the nozzle usage rate of each nozzle arranged between the position where it approaches the seam and the downstream end (left) of head unit 20K in the sub-scanning direction is gradually reduced from the position where it approaches the seam toward the downstream end so that the nozzle usage rate of the nozzles arranged at the downstream end is 0%. Here, the nozzle usage rate refers to the percentage of pixels that are printed without being thinned out for a given nozzle during a single printing operation. In other words, the nozzle usage rate can be expressed by the following formula: <Nozzle usage rate> = 100% - <Pixel thinning rate in the main scanning direction (scanning direction) for a certain target nozzle>

[0041] Next, examples of print results when seam correction is performed taking into account the printing of reaction liquid will be described with reference to Figures 7 to 9. Note that Figures 7 to 9 will be described using as examples the head unit 20Pr corresponding to the reaction liquid and the head unit 20K corresponding to black (K) ink.

[0042] FIG. 7 is a diagram showing an example of a print result when the image allocation at the joint portion is made different between the reaction liquid and the ink. 7, if the image allocation at the seam area is different for the reaction liquid and the ink, in the first pass printing there will be areas (pixels) where the reaction liquid and the ink do not overlap, which could result in dot spreading, liquid shifting, color bleeding, etc. In addition, in the second pass printing, just like the first pass, there will be areas (pixels) where the reaction liquid and the ink do not overlap, so if seam correction is performed by the second pass printing, dot spreading, liquid shifting, color bleeding, etc. will be even more likely to occur in the seam area, resulting in a deterioration in image quality.

[0043] FIG. 8 is a diagram showing an example of a print result when the image allocation at the joint portion is the same for the reaction liquid and the ink. As described above, if the image allocation at the joint portion is made different between the reaction liquid and the ink, the image quality at the joint portion will deteriorate, so it is possible to make the image allocation at the joint portion the same for the reaction liquid and the ink. However, as shown in Figure 8, even if the image allocation at the joint portion is made the same for the reaction liquid and the ink, if there is a landing deviation between the reaction liquid and the ink, the image quality at the joint portion will deteriorate, just as in the case where the image allocation is made different.

[0044] Therefore, in this embodiment, in order to prevent deterioration of image quality at the seams, the image allocation of the reaction liquid at the seams is devised. Figure 9 shows an example of a print result when the image allocation of this embodiment is adopted at the seams.

[0045] As shown in FIG. 9, the first pass of printing the reaction liquid is performed so that the reaction liquid is spread over the entire pixel to be printed. As a result, even if the ink impact deviation occurs during the first and second passes of printing, there are no areas (pixels) where the reaction liquid and the ink do not overlap, thereby preventing the above-mentioned dot spreading, liquid misalignment, color bleeding, and the like. Note that the first pass of printing the reaction liquid is sufficient as long as the reaction liquid is spread over the entire pixel to be printed. For example, if the surface tension of the reaction liquid ejected from the nozzles of the recording elements 22 is adjusted to be lower than the surface tension of the four color inks, as described above, it is not necessary to eject the reaction liquid corresponding to all pixels to be printed. This is because in such a case, the reaction liquid can be spread over the entire pixel to be printed with a smaller ejection volume than the four color inks.

[0046] Next, the manner in which the character image of "B" is printed in the region that will become the joint (hereinafter simply referred to as the joint) will be described with reference to FIGS.

[0047] FIG. 10 is a diagram showing an example of a printing state in which the image allocation when printing the letter "B" at the joint portion is the same for both the reaction liquid and the ink.

[0048] As shown in Fig. 10, for example, when the nozzle resolution is 360 dpi and the print resolution is 720 dpi, three (three passes) of main scanning operation (printing) are performed at the seams, and two (two passes) of main scanning operation (printing) are performed in other areas to record the character image of "B." Note that in the example of Fig. 10, the recording heads 21 associated with four colors of ink are collectively represented as a recording head 21 associated with color inks (color).

[0049] Specifically, a first (first pass) main scanning operation is performed with the recording elements 22 provided at the upstream end of each recording head 21 in the sub-scanning direction and the upstream end of the seam in the sub-scanning direction positioned on the same pixel line. During this first main scanning operation, reaction liquid is printed in a predetermined image allocation such that the printing progress rate of the seam is 25%, the printing progress rate of the area upstream of the seam in the sub-scanning direction is 0%, and the printing progress rate of the area downstream of the seam in the sub-scanning direction is 50%. Next, color ink (colorant ink) is printed in the same image allocation as the above-mentioned image allocation for the reaction liquid (primer).

[0050] Next, after the recording medium P has been transported to a predetermined position, a second (second pass) main scanning operation is performed. In this second main scanning operation, first, reaction liquid is printed in a predetermined image allocation such that the printing progress rate of the seam is 75%, the printing progress rate of the area upstream of the seam in the sub-scanning direction adjacent to the seam in the sub-scanning direction is 50%, and the printing progress rate of the area downstream of the seam in the sub-scanning direction adjacent to the seam in the sub-scanning direction is 100%. Next, color ink (coloring ink) is printed in the same image allocation as the above image allocation for the reaction liquid.

[0051] Next, the recording medium P is transported to a predetermined position, and the recording elements 22 provided at the downstream end of each recording head 21 in the sub-scanning direction and the downstream end of the seam in the sub-scanning direction are positioned on the same pixel line. Then, a third (third pass) main scanning operation is performed. During this third main scanning operation, reaction liquid is first printed at the seam where the printing progress rate has not yet reached 100%, and at the upstream area adjacent to the seam in the sub-scanning direction, in a predetermined image allocation that will bring the printing progress rate to 100%. Next, color ink (coloring ink) is printed in the same image allocation as the reaction liquid. This completes the printing of the letter "B" at the seam. Note that in the printing mode shown in FIG. 10, as described in FIG. 8, there is a risk of image quality degradation if there is a landing misalignment between the reaction liquid and the ink.

[0052] FIG. 11 is a diagram showing an example of a printing state when the image allocation when printing the letter "B" at the joint portion is made different between the reaction liquid and the ink.

[0053] As shown in Fig. 11, for example, when the nozzle resolution is 360 dpi and the print resolution is 720 dpi, three (three passes) of main scanning operation (printing) is performed at the seams, and two (two passes) of main scanning operation (printing) is performed in other areas to record the character image of "B." Note that in the example of Fig. 11, similar to Fig. 10, the recording heads 21 associated with four colors of ink are collectively represented as a recording head 21 associated with color inks (color).

[0054] Specifically, a first main scanning operation (first pass) is performed with the recording elements 22 provided at the upstream end of each recording head 21 in the sub-scanning direction and the upstream end of the seam in the sub-scanning direction positioned on the same pixel line. During this first main scanning operation, reaction liquid is printed in a predetermined image allocation such that the printing progress rate of the seam is 25%, the printing progress rate of the area upstream of the seam in the sub-scanning direction is 0%, and the printing progress rate of the area downstream of the seam in the sub-scanning direction is 50%. Next, color ink (colorant ink) is printed in a predetermined image allocation different from the image allocation for the reaction liquid, such that the printing progress rate of the seam is 25%, the printing progress rate of the area upstream of the seam in the sub-scanning direction is 0%, and the printing progress rate of the area downstream of the seam in the sub-scanning direction is 50%.

[0055] Next, after the recording medium P has been transported to a predetermined position, a second (second pass) main scanning operation is performed. During this second main scanning operation, first, reaction liquid is printed in a predetermined image allocation such that the printing progress rate of the seam is 75%, the printing progress rate of the area upstream of the seam in the sub-scanning direction is 50%, and the printing progress rate of the area downstream of the seam in the sub-scanning direction is 100%. Next, color ink (coloring ink) is printed in a predetermined image allocation different from the image allocation for the reaction liquid described above, such that the printing progress rate of the seam is 75%, the printing progress rate of the area upstream of the seam in the sub-scanning direction is 50%, and the printing progress rate of the area downstream of the seam in the sub-scanning direction is 100%.

[0056] Next, the recording medium P is transported to a predetermined position, and a third (third pass) main scanning operation is performed in a state where the recording elements 22 provided at the downstream end of each recording head 21 in the sub-scanning direction and the downstream end of the seam in the sub-scanning direction are positioned on the same pixel line. During this third main scanning operation, reaction liquid is first printed in a predetermined image allocation such that the printing progress rate of the seam where the printing progress rate has not yet reached 100% and the area upstream in the sub-scanning direction adjacent to the seam becomes 100%. Next, color ink (coloring ink) is printed in a predetermined image allocation different from the image allocation for the reaction liquid, such that the printing progress rate of the seam where the printing progress rate has not yet reached 100% and the area upstream in the sub-scanning direction adjacent to the seam becomes 100%. This completes printing of the character image "B" at the seam. In the printing mode shown in Figure 11, as explained in Figure 7, if the image allocation at the joint part is different between the reaction liquid and the ink, there will be parts (pixels) where the reaction liquid and the ink do not overlap in each main scanning operation of the first and second passes, and in those parts where only the ink is printed, dots will spread, the liquid will move, color will bleed, etc., resulting in a deterioration in image quality.

[0057] Fig. 12 shows an example of a printing mode in this embodiment when printing a letter image of "B" at a seam. Figs. 13A to 13C are graphs showing the nozzle usage rates corresponding to each recording element 22 when main scanning operations are performed each time (1st to 3rd) at the seam.

[0058] As shown in Fig. 12, for example, when the nozzle resolution is 360 dpi and the print resolution is 720 dpi, three (three passes) of main scanning operation (printing) are performed at the seams, and two (two passes) of main scanning operation (printing) are performed in other areas to record the character image of "B." Note that in the example of Fig. 12, similar to Figs. 10 and 11, the recording heads 21 associated with four colors of ink are collectively represented as a recording head 21 associated with color inks (color).

[0059] Specifically, a first main scanning operation (first pass) is performed with the recording elements 22 provided at the upstream end of each recording head 21 in the sub-scanning direction and the upstream end of the seam in the sub-scanning direction positioned on the same pixel line. During this first main scanning operation, reaction liquid is printed in a predetermined image allocation such that the printing progress rate of the seam is 50%, the printing progress rate of the area upstream of the seam in the sub-scanning direction is 0%, and the printing progress rate of the area downstream of the seam in the sub-scanning direction is 50%. Next, color ink (colorant ink) is printed in a predetermined image allocation such that the printing progress rate of the seam is 25%, the printing progress rate of the area upstream of the seam in the sub-scanning direction is 0%, and the printing progress rate of the area downstream of the seam in the sub-scanning direction is 50%. 13A, in this first main scanning operation, the nozzle usage rate of each recording element 22 of the recording head 21Pr for the reaction liquid is adjusted to 100%. On the other hand, the nozzle usage rate of each recording element 22 of the recording heads 21 (21Y, 21M, 21C, 21K) for the color inks is adjusted to decrease from the downstream side to the upstream side of the joint in the sub-scanning direction.

[0060] Next, after the recording medium P has been transported to a predetermined position, a second (second pass) main scanning operation is performed. During this second main scanning operation, first, reaction liquid is printed in a predetermined image allocation such that the printing progress rate of the seam is 100%, the printing progress rate of the area adjacent to the seam on the upstream side in the sub-scanning direction is 50%, and the printing progress rate of the area adjacent to the seam on the downstream side in the sub-scanning direction is 100%. Next, color ink (colorant ink) is printed in a predetermined image allocation such that the printing progress rate of the seam is 75%, the printing progress rate of the area adjacent to the seam on the upstream side in the sub-scanning direction is 50%, and the printing progress rate of the area adjacent to the seam on the downstream side in the sub-scanning direction is 100%. In this second main scanning operation, as shown in Figure 13B, the nozzle usage rate of each recording element 22 of the recording head 21Pr for the reaction liquid and the recording heads 21 (21Y, 21M, 21C, 21K) for the color inks is adjusted to be 100%.

[0061] Next, the recording medium P is transported to a predetermined position, and a third (third pass) main scanning operation is performed in a state where the recording elements 22 provided at the downstream end of each recording head 21 in the sub-scanning direction and the downstream end of the seam in the sub-scanning direction are positioned on the same pixel line. In this third main scanning operation, first, reaction liquid is printed in a predetermined image allocation such that the printing progress rate of the upstream area in the sub-scanning direction adjacent to the seam, where the printing progress rate has not yet reached 100%, becomes 100%. Next, color ink (coloring ink) is printed in a predetermined image allocation such that the printing progress rate of the seam, where the printing progress rate has not yet reached 100%, and the upstream area in the sub-scanning direction adjacent to the seam, where the printing progress rate has not yet reached 100%, both become 100%. This completes printing of the character image of "B" at the seam. 13C, the nozzle usage rates of the recording elements 22 of the recording heads 21Pr for the color inks (21Y, 21M, 21C, 21K) are adjusted so that they increase from the downstream side to the upstream side of the seam in the sub-scanning direction. Note that, because printing of the reaction liquid at the seam is completed in the second main scanning operation, the nozzle usage rates of the recording elements 22 of the recording head 21Pr for the reaction liquid at the seam are not displayed in FIG.

[0062] Next, the printing mode in the area other than the seam in this embodiment will be described with reference to FIGS.

[0063] 14 is a diagram showing an example of a printing mode for color inks in areas other than seams. This printing mode for color inks is characterized by printing the same pixel line multiple times (for example, twice (two passes)).

[0064] As shown in FIG. 14, in the first printing pass, pixel lines L1, L5, and L9 of all pixel lines L1 to L12 in the figure are targeted, and half of the pixels on each pixel line L1, L5, and L9 are printed so that the printing progress rate is 12.5%. Next, in the second printing pass, pixel lines L2, L6, and L10 are targeted, and half of the pixels on each pixel line L2, L6, and L10 are printed so that the printing progress rate is 25%. Next, in the third printing pass, pixel lines L3, L7, and L11 are targeted, and half of the pixels on each pixel line L3, L7, and L11 are printed so that the printing progress rate is 37.5%. Next, in the fourth printing pass, pixel lines L4, L8, and L12 are targeted, and half of the pixels on each pixel line L4, L8, and L12 are printed so that the printing progress rate is 50%. Next, in the fifth printing pass, pixel lines L1, L5, and L9 are targeted and the remaining half of the pixels on each pixel line L1, L5, and L9 are printed so that the printing progress rate is 62.5%. Next, in the sixth printing pass, pixel lines L2, L6, and L10 are targeted and the remaining half of the pixels on each pixel line L2, L6, and L10 are printed so that the printing progress rate is 75%. Next, in the seventh printing pass, pixel lines L3, L7, and L11 are targeted and the remaining half of the pixels on each pixel line L3, L7, and L11 are printed so that the printing progress rate is 87.5%. Next, in the eighth printing pass, pixel lines L4, L8, and L12 are targeted and the remaining half of the pixels on each pixel line L4, L8, and L12 are printed so that the printing progress rate is 100%.

[0065] 15 is a diagram showing an example of a printing mode for the reaction liquid in the region other than the seam. This printing mode for the reaction liquid is characterized by printing the same pixel line in one go.

[0066] As shown in FIG. 15, in the first printing pass, pixel lines L1, L5, and L9 of all pixel lines L1 to L12 in the figure are printed in one pass so that the printing progress rate is 25%. Next, in the second printing pass, pixel lines L2, L6, and L10 are printed in one pass so that the printing progress rate is 50%. Next, in the third printing pass, pixel lines L3, L7, and L11 are printed in one pass so that the printing progress rate is 75%. Next, in the fourth printing pass, pixel lines L4, L8, and L12 are printed in one pass so that the printing progress rate is 100%. Note that in the fifth to eighth printing passes, only color ink printing is performed, as shown in FIG. 14.

[0067] FIG. 16 shows an example of a printing pattern in which the same pixel line is printed multiple times not only with color ink but also with reaction liquid. In this example, the image allocation of color ink and reaction liquid in each printing is the same. In this example, the letter "B" is recorded by performing four main scanning operations (printing passes). The nozzle resolution is 360 dpi, and the printing resolution is 720 dpi.

[0068] As shown in FIG. 16, first, when the first printing (first pass) is performed, the reaction liquid is printed in a predetermined image allocation such that the printing progress rate is 25%. Next, color ink is printed in the same image allocation as the above-mentioned image allocation for the reaction liquid. Next, after the recording medium P is transported to a predetermined position, the second printing (second pass) is performed. In this second printing, the reaction liquid is first printed in a predetermined image allocation such that the printing progress rate is 50%. Next, color ink is printed in the same image allocation as the above-mentioned image allocation for the reaction liquid. Next, after the recording medium P is transported to a predetermined position, the third printing (third pass) is performed. In this third printing, the reaction liquid is first printed in a predetermined image allocation such that the printing progress rate is 75%. Next, color ink is printed in the same image allocation as the above-mentioned image allocation for the reaction liquid. Next, after the recording medium P is transported to a predetermined position, the fourth printing (fourth pass) is performed. In this fourth printing, first, the reaction liquid is printed in a predetermined image allocation that results in a printing progress rate of 100%. Next, color ink is printed in the same image allocation as the image allocation for the reaction liquid. This completes the printing of the letter "B" image. Note that in the printing mode shown in FIG. 16, as explained in FIG. 8, if there is a landing misalignment between the reaction liquid and the ink, the image quality may deteriorate.

[0069] FIG. 17 shows an example of a printing pattern in which the same pixel line is printed multiple times using not only color ink but also reaction liquid. In this example, the image allocation of color ink and reaction liquid is different for each printing. In this example, four (four passes) of printing (main scanning operations) are performed to record the character image of "B." The nozzle resolution is 360 dpi, and the printing resolution is 720 dpi.

[0070] As shown in FIG. 17, first, when the first printing (first pass) is performed, reaction liquid is printed in a predetermined image allocation such that the printing progress rate is 25%. Next, color ink is printed in a predetermined image allocation such that the printing progress rate is 25%, but in an image allocation different from the image allocation for the reaction liquid described above. Next, after the recording medium P is transported to a predetermined position, a second printing (second pass) is performed. In this second printing, reaction liquid is first printed in a predetermined image allocation such that the printing progress rate is 50%. Next, color ink is printed in a predetermined image allocation such that the printing progress rate is 50%, but in an image allocation different from the image allocation for the reaction liquid described above. Next, after the recording medium P is transported to a predetermined position, a third printing (third pass) is performed. In this third printing, reaction liquid is first printed in a predetermined image allocation such that the printing progress rate is 75%. Next, color ink is printed in a predetermined image allocation such that the printing progress rate is 75%, but in an image allocation different from the image allocation for the reaction liquid described above. Next, after the recording medium P is transported to a predetermined position, the fourth printing (fourth pass) is performed. In this fourth printing, first, the reaction liquid is printed in a predetermined image allocation that results in a 100% printing progress rate. Next, color ink is printed in a predetermined image allocation that results in a 100% printing progress rate, but in an image allocation that is different from the image allocation for the reaction liquid. This completes the printing of the letter "B" image. Note that in the printing mode shown in FIG. 17, if the image allocation for the reaction liquid and the ink is different as described in FIG. 7, there will be areas (pixels) in each printing where the reaction liquid and the ink do not overlap, and in those areas where only the ink is printed, the dots will spread, the liquid will move, color bleeding will occur, and the image quality will deteriorate.

[0071] FIG. 18 shows an example of a printing mode in this embodiment when printing the letter "B" image in an area other than the seam. In this example, the letter "B" image is recorded by performing four (four passes) main scanning operations (printing). The nozzle resolution is 360 dpi, and the printing resolution is 720 dpi in the main scanning direction and 720 dpi in the sub-scanning direction. Printing of the reaction liquid is completed in the first and second main scanning operations.

[0072] As shown in Figure 18, when the first printing (first pass) is performed, the reaction liquid is printed on half of the pixel lines in the printing target area so that the printing progress rate is 50%. Next, color ink is printed in a predetermined image allocation so that the printing progress rate is 25%. Here, the color ink is printed on the pixel lines on which the reaction liquid was printed in the first printing.

[0073] Next, when the second printing (second pass) is performed, the reaction liquid is printed on the remaining half of the pixel lines of the printing target area so that the printing progress rate is 100%. Next, color ink (coloring ink) is printed in a predetermined image allocation so that the printing progress rate is 50%.

[0074] Next, when the third printing (third pass) is performed, color ink (coloring ink) is printed in a predetermined image allocation so that the printing progress rate is 75%. Note that, as the printing progress rate for the reaction liquid has reached 100% in the second printing, the printing of the reaction liquid is not performed in the third and fourth main scanning operations.

[0075] Next, when the fourth printing (fourth pass) is performed, color inks (colorant inks) are printed in a predetermined image allocation such that the print progress rate is 100%. This completes printing of the letter "B" image. Although not shown, just as when an image is recorded at a seam (see FIGS. 4 and 5), when an image is recorded outside a seam, the nozzle usage rate of each recording element 22 of the recording head 21 (21Y, 21M, 21C, 21K) for color inks can be changed depending on the position of each recording element 22.

[0076] As described above, the inkjet recording apparatus 1 of this embodiment ejects ink and / or reaction liquid onto the recording medium P while moving the recording heads 21Y, 21M, 21C, and 21K having ink ejection units that eject ink onto the recording medium P and the recording head 21Pr having reaction liquid ejection units that eject reaction liquid to fix the ink ejected onto the recording medium P relative to the recording medium P in the main scanning direction, and then moves the recording heads 21Pr, 21Y, 21M, 21C, and 21K relative to the recording medium P in the sub-scanning direction perpendicular to the main scanning direction. This series of operations is repeated to form an image in which the ink is fixed on the recording medium P. The printer is provided with a control unit 40 that controls the ejection of ink by the recording heads 21Y, 21M, 21C, and 21K and the ejection of reaction liquid by the recording head 21Pr, and the control unit 40 controls the ejection of ink by the recording heads 21Y, 21M, 21C, and 21K and the ejection of reaction liquid by the recording head 21Pr so that the printing progress rate of the reaction liquid by the recording head 21Pr for each of the above series of operations is higher than the printing progress rate of the ink by the recording heads 21Y, 21M, 21C, and 21K in a printing area where ink has been ejected multiple times by at least the recording heads 21Y, 21M, 21C, and 21K by performing the above series of operations multiple times. With this configuration, in a printing area where ink is ejected multiple times, it is possible to suppress dot spreading, liquid shifting, color bleeding, and the like that occur when the ink is ejected before the reaction liquid is ejected, thereby suppressing deterioration of image quality in the printing area where ink is ejected multiple times.

[0077] In addition, in a printing area where ink is ejected multiple times by the recording heads 21Y, 21M, 21C, and 21K, the control unit 40 controls the ejection of ink by the recording heads 21Y, 21M, 21C, and 21K and the ejection of reaction liquid by the recording head 21Pr so that the ejection of reaction liquid by the recording heads 21Y, 21M, 21C, and 21K is performed before the ejection of ink by the recording heads 21Y, 21M, 21C, and 21K. With this configuration, in a printing area where ink is ejected multiple times, it is possible to more effectively suppress dot spreading, liquid shifting, color bleeding, etc., which occur due to the ink being ejected before the reaction liquid is ejected.

[0078] Furthermore, the printing area is an area where the reaction liquid is ejected multiple times by the recording head 21Pr by performing the above series of operations multiple times, so that the ejected ink can be reliably fixed on the recording medium P.

[0079] Furthermore, each of the recording heads 21Pr, 21Y, 21M, 21C, and 21K is arranged so that the recording element groups (plurality of recording elements 22) are parallel to one another in the main scanning direction, and the control unit 40 controls the ink ejection by the recording heads 21Y, 21M, 21C, and 21K and the reaction liquid ejection by the recording head 21Pr so that the reaction liquid and ink can be ejected onto the same printing area by performing at least one of the above series of operations. This allows the carriage 200 to be made compact, thereby preventing the device from becoming larger. Furthermore, the ejection of the reaction liquid and the ejection of the ink can be performed efficiently.

[0080] The printing area is a region that forms a seam in the sub-scanning direction at the end of the image forming area where an image is formed by one of the above series of operations, and the number of times the series of operations is performed is set to be greater in the seam region than in other regions, which allows for optimal correction of color unevenness, streaks, etc. that tend to occur in the seam region.

[0081] In addition, when ink is ejected multiple times in an area where the recording heads 21Y, 21M, 21C, and 21K eject the ink multiple times, the control unit 40 changes the nozzle usage rate of the ink ejection unit (multiple recording elements 22) depending on the position of the area in the sub-scanning direction, thereby more effectively performing correction processing for the above-mentioned color unevenness, streaks, etc.

[0082] The present invention is not limited to the above-described embodiment, and various modifications are possible. For example, in the above embodiment, an example has been described in which the head unit 20 is caused to scan in the main scanning operation and the recording medium P is transported in the sub-scanning operation, but this is not intended to be limiting. For example, in the main scanning operation, the head unit 20 may be fixed and the recording medium P may be transported in the main scanning direction. Also, in the sub-scanning operation, the recording medium P may be fixed and the head unit 20 may be moved in the sub-scanning direction.

[0083] Furthermore, in the above embodiment, an example has been described in which the head unit 20 is moved in the +X direction shown in FIG. 1 during each main scanning operation, but this is not intended to be limiting. Instead, the movement direction of the head unit 20 may be switched between the +X direction and the -X direction for each main scanning operation. Alternatively, the head unit 20 may move back and forth in the +X direction and the -X direction during one main scanning operation. In these embodiments, head units 20Pr corresponding to the reaction liquid are disposed on both sides of the carriage 200, i.e., on the right side of the head unit 20Y corresponding to yellow (Y) ink and on the left side of the head unit 20K corresponding to black (K) ink, as shown in FIG. 1.

[0084] In the above embodiment, the plurality of recording elements 22 of the recording heads 21 for the reaction liquid and the four color inks are arranged in a single row in the sub-scanning direction to form a long head unit 20, but the number of nozzle rows in each recording head 21 is not limited to one row and may be multiple rows. Also, each recording head 21 may be provided with multiple head chips (long head chips in which the recording elements 22 are arranged in a single row in the sub-scanning direction).

[0085] 19, the recording heads 21 for the reaction liquid may be configured so that some of the recording elements 22 of the recording head 21 for the reaction liquid are parallel to the recording elements 22 of the recording heads 21 for the four color inks in the main scanning direction by shifting the recording head 21 for the reaction liquid in the sub-scanning direction relative to the other recording heads 21, i.e., the recording heads 21 for the four color inks. In such a case, in the portion where the recording elements 22 of the recording head 21 for the reaction liquid and the recording elements 22 of the recording heads 21 for the four color inks are parallel to each other in the main scanning direction, the reaction liquid and the four color inks (color inks), yellow (Y), magenta (M), cyan (C), and black (K), can be printed in the same printing area by a single scan of the carriage 200 in the main scanning direction.

[0086] Although the embodiments of the present invention have been described, the scope of the present invention is not limited to the above-described embodiments, but includes the scope of the invention described in the claims and its equivalents. [Industrial Applicability]

[0087] The present invention can be used in an inkjet recording apparatus and an inkjet recording method. [Explanation of symbols]

[0088] 1. Inkjet recording device 2 External device 10 Conveying section 11a Drive roller 11b driven roller 12 Drive motor 13 Conveyor belt 200 carriages 201 Support part 20, 20Pr, 20Y, 20M, 20C, 20K head unit 21, 21Pr, 21Y, 21M, 21C, 21K recording head 22 Recording element 25 Drive unit 30 Main scanning section 31 Carriage rail 40 Control Unit 41 CPU 42 RAM 43 ROM 44 Storage section 50 Image processing section 60 Ink receiving section 101 Interface 102 Bus P Recording medium

Claims

1. an inkjet recording device that forms an image in which ink is fixed on a recording medium by repeating a series of operations of ejecting ink and / or a reaction liquid onto the recording medium while moving a first recording head having an ink ejection unit that ejects ink onto a recording medium and a second recording head having a reaction liquid ejection unit that ejects a reaction liquid to fix the ink ejected onto the recording medium, and then moving the first and second recording heads and the recording medium relatively in a second direction perpendicular to the first direction, a control unit that controls the ejection of ink by the first recording head and the ejection of reaction liquid by the second recording head; the control unit controls the ejection of ink by the first recording head and the ejection of reaction liquid by the second recording head so that a printing progress rate of the reaction liquid by the second recording head for each of the series of operations is higher than a printing progress rate of the ink by the first recording head in a printing region where ink has been ejected at least a plurality of times by the first recording head by performing the series of operations a plurality of times; the printing area is an area that becomes a joint between the ends in the second direction of an image forming area where an image is formed by one of the series of operations, The number of times of the series of actions is set to be greater in the region that becomes the joint than in other regions. An inkjet recording apparatus characterized by:

2. the control unit controls the ejection of ink by the first recording head and the ejection of the reaction liquid by the second recording head so that the ejection of the reaction liquid by the second recording head is performed before the ejection of ink by the first recording head in a printing region where the ejection of ink by the first recording head is performed a plurality of times.

2. The inkjet recording apparatus according to claim 1, wherein the inkjet recording apparatus is a recording medium.

3. the printing area is an area where the reaction liquid is ejected by the second recording head multiple times by performing the series of operations multiple times; 3. The inkjet recording apparatus according to claim 1, wherein the inkjet recording head is a recording head.

4. the first recording head and the second recording head are each disposed such that the ink ejection unit and the reaction liquid ejection unit are parallel to each other in the first direction; the control unit controls the ejection of ink by the first recording head and the ejection of reaction liquid by the second recording head so that at least a part of the reaction liquid and the ink can be ejected onto the same printing area by at least one of the series of operations.

4. The inkjet recording apparatus according to claim 1, wherein the inkjet recording apparatus is a recording medium.

5. the control unit changes a nozzle usage rate of the ink ejection unit in accordance with a position of the area in the second direction when the ink is ejected a plurality of times in the area where the first recording head ejects the ink a plurality of times.

5. The inkjet recording apparatus according to claim 1, wherein the inkjet recording apparatus is a recording medium.

6. the reaction liquid and the ink are each adjusted so that the surface tension of the reaction liquid ejected from the reaction liquid ejection unit is lower than the surface tension of the ink ejected from the ink ejection unit; 6. The inkjet recording apparatus according to claim 1, wherein the inkjet recording apparatus is a recording medium.

7. the control unit controls the ejection of the reaction liquid by the second recording head so that a maximum ejection amount per unit area of ​​the reaction liquid ejected from the reaction liquid ejection unit increases when the recording medium is an absorbent substrate compared to when the recording medium is a non-absorbent substrate.

7. The inkjet recording apparatus according to claim 1, wherein the inkjet recording apparatus is a recording medium.

8. an inkjet recording method using an inkjet recording apparatus, the method comprising: ejecting ink and / or a reaction liquid onto the recording medium while moving a first recording head having an ink ejection unit that ejects ink onto the recording medium and a second recording head having a reaction liquid ejection unit that ejects a reaction liquid to fix the ink ejected onto the recording medium, and then relatively moving the first and second recording heads and the recording medium in a second direction perpendicular to the first direction, thereby repeating a series of operations to form an image in which the ink is fixed on the recording medium, a control step of controlling the ejection of ink by the first recording head and the ejection of reaction liquid by the second recording head, In the control step, the ejection of ink by the first recording head and the ejection of reaction liquid by the second recording head are controlled so that a printing progress rate of the reaction liquid by the second recording head for each of the series of operations is higher than a printing progress rate of the ink by the first recording head in a printing region where ink has been ejected a plurality of times by at least the first recording head by performing the series of operations a plurality of times; the printing area is an area that becomes a joint between the ends in the second direction of an image forming area where an image is formed by one of the series of operations, The number of times of the series of actions is set to be greater in the region that becomes the joint than in other regions. An inkjet recording method comprising:

Images