Inkjet recording apparatus for textile printing

Abstract

SOLUTION: An inkjet recording device includes a conveyance part, a carriage, one or a plurality of ink head rows, and a processing head. The treatment head includes a pretreatment head disposed upstream of the one or more ink head rows in the conveyance direction and configured to eject a non-color developing pretreatment liquid. In a case where the head disposed on the most one end side in the main scanning direction is a one end side head, the head disposed on the most other end side is a other end side head, and a distance in the main scanning direction from the one end side head to the other end side head is Lc, a distance in the main scanning direction from the one end side head to the pre-processing head is B1, a relationship of (B1-Lc / 2) / Lc ≤ 1 / 4 is satisfied.EFFECT: It is possible to reduce the variation in the time from the landing of the pretreatment liquid to the landing of the ink. As a result, by sequentially landing the pretreatment liquid and the ink on the recording medium, variation in image quality is less likely to occur on the recording medium.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to an inkjet recording apparatus having an ink head mounted on a carriage that moves in a main scanning direction. [Background technology]

[0002] Inkjet recording devices such as inkjet printers are equipped with ink heads that eject ink for forming an image onto a recording medium. For example, when the recording medium is a fiber sheet such as a woven or knitted fabric, or a plastic sheet, it may be necessary to apply a pretreatment liquid and a posttreatment liquid to the recording medium before and after ejecting the ink onto the recording medium (see, for example, Patent Document 1). The pretreatment liquid is, for example, a treatment liquid that improves the fixation of the ink to the recording medium and the coagulation of the ink pigment. The posttreatment liquid is, for example, a treatment liquid that improves the robustness of the printed image. In this case, the inkjet recording device is equipped with, in addition to the ink heads, a treatment head that ejects the pretreatment liquid and the posttreatment liquid.

[0003] When the recording medium is wide, the ink head and each processing head are mounted on a carriage that moves back and forth in the main scanning direction. During recording processing, the recording medium is intermittently fed in a predetermined transport direction (sub-scanning direction), and the carriage moves back and forth in the main scanning direction while the recording medium is stopped. As the carriage moves, ink and processing liquid are ejected from the ink head and each processing head, respectively. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-147307 Summary of the Invention

[0005] An inkjet recording apparatus according to one aspect of the present disclosure includes a transport unit, a carriage, one or more ink head rows, and a treatment head. The transport unit transports a recording medium in a predetermined transport direction. The carriage reciprocates in a main scanning direction that intersects with the transport direction. The one or more ink head rows are mounted on the carriage at predetermined positions in the transport direction. The treatment head is mounted on the carriage and ejects a non-color-forming treatment liquid. Each of the one or more ink head rows includes a plurality of ink heads that are arranged in line in the main scanning direction and each ejects ink for image formation. The treatment head includes a pretreatment head that is arranged upstream of the one or more ink head rows in the transport direction and ejects a pretreatment liquid that is the treatment liquid. Of the plurality of ink heads and processing heads, the head located closest to one end in the main scanning direction is referred to as the one-end head, and the head located closest to the other end is referred to as the other-end head, and the distance in the main scanning direction from the one-end head to the other-end head is referred to as LC, and the distance in the main scanning direction from the one-end head to the pre-processing head is referred to as B1. The pre-processing heads are arranged to satisfy the relationship in Equation 1: |(B1-LC / 2)| / LC≦1 / 4 (Equation 1)

[0006] An inkjet recording apparatus according to another aspect of the present disclosure includes a transport unit, a carriage, one or more ink head rows, and a treatment head. The transport unit transports a recording medium in a predetermined transport direction. The carriage reciprocates in a main scanning direction that intersects with the transport direction. The one or more ink head rows are mounted on the carriage at predetermined positions in the transport direction. The treatment head is mounted on the carriage and ejects a non-color-forming treatment liquid. Each of the one or more ink head rows includes a plurality of ink heads that are arranged in line in the main scanning direction and each ejects ink for image formation. The treatment head includes a post-treatment head that is arranged downstream of the one or more ink head rows in the transport direction and ejects a post-treatment liquid that is the treatment liquid. Of the plurality of ink heads and processing heads, the head located closest to one end in the main scanning direction is referred to as the one-end head, and the head located closest to the other end is referred to as the other-end head, and the distance in the main scanning direction from the one-end head to the other-end head is referred to as LC, and the distance in the main scanning direction from the one-end head to the post-processing head is referred to as B2. The post-processing head is disposed so as to satisfy the relationship in Equation 2: |(B2-LC / 2)| / LC≦1 / 4 (Equation 2). [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a perspective view showing the overall configuration of an inkjet printer according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a schematic cross-sectional view taken along line II-II in FIG. [Figure 3] FIG. 3 is an enlarged perspective view of the carriage shown in FIG. [Figure 4] FIG. 4 is a schematic diagram showing the serial printing method employed in this embodiment. [Figure 5A] FIG. 5A is a schematic diagram showing the printing status during the forward and backward travel of the carriage. [Figure 5B] FIG. 5B is a schematic diagram showing the printing status during the forward and backward travel of the carriage. [Figure 6] FIG. 6 is a plan view showing the arrangement of the ink heads and the processing heads in the carriage shown in FIG. 3, and schematically showing the head arrangement according to the first embodiment. [Figure 7] FIG. 7 is a schematic diagram for explaining the landing times of the pre-treatment liquid, ink, and post-treatment liquid at point P on the recording medium. [Figure 8] FIG. 8 is a plan view of a carriage showing a head arrangement according to the second embodiment. [Figure 9] FIG. 9 is a plan view of a carriage showing a head arrangement according to the third embodiment. [Figure 10] FIG. 10 is a plan view of a carriage showing a head arrangement according to the fourth embodiment. [Figure 11] FIG. 11 is a plan view of a carriage showing a head arrangement according to the fifth embodiment. [Figure 12] FIG. 12 is a plan view of a carriage showing a head arrangement according to the sixth embodiment. [Figure 13] FIG. 13 is a plan view of a carriage showing a head arrangement according to the seventh embodiment. [Figure 14] FIG. 14 is a plan view of a carriage showing a head arrangement according to the eighth embodiment. [Figure 15] FIG. 15 is a plan view of a carriage showing the head arrangement and the sub-tank arrangement according to the ninth embodiment. [Figure 16] FIG. 16 is a plan view of a carriage showing a head arrangement according to a tenth embodiment. [Figure 17] FIG. 17 is a plan view of a carriage showing a head arrangement according to an eleventh embodiment. [Figure 18] FIG. 18 is a plan view of a carriage showing a head arrangement according to Comparative Example 1 to be compared with the present disclosure. [Figure 19] FIG. 19 is a plan view of a carriage showing a head arrangement according to Comparative Example 2 to be compared with the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0008] An embodiment of the present disclosure will be described below with reference to the drawings. In this embodiment, an inkjet printer equipped with an ink head that ejects ink for forming an image onto a wide, long recording medium will be exemplified as a specific example of an inkjet recording apparatus. The inkjet printer of this embodiment is suitable for digital textile printing, which uses an inkjet method to print images such as letters and patterns onto a recording medium made of fabric such as woven or knitted fabric. Of course, the inkjet recording apparatus according to the present disclosure can also be used to print various inkjet images on recording media such as paper sheets and resin sheets.

[0009] [Overall configuration of inkjet printer] Fig. 1 is a perspective view showing the overall configuration of an inkjet printer 1 according to an embodiment of the present disclosure, and Fig. 2 is a schematic cross-sectional view taken along line II-II in Fig. 1. The inkjet printer 1 is a printer that prints images on a wide and long workpiece W (recording medium) using an inkjet method, and includes a device frame 10, and a workpiece transport unit 20 (transport unit) and carriage 3 that are incorporated into this device frame 10. In this embodiment, the left-right direction is the main scanning direction when printing on the workpiece W, and the direction from rear to front is the sub-scanning direction (direction F for transporting the workpiece W).

[0010] The device frame 10 forms a framework for mounting various components of the inkjet printer 1. The work transport unit 20 is a mechanism that intermittently feeds the work W so that the work W progresses in a transport direction F from rear to front in the printing area where the inkjet printing process is performed. The carriage 3 is equipped with an ink head 4, a pre-processing head 5, a post-processing head 6, and a sub-tank 7, and moves back and forth in the left and right directions during the inkjet printing process.

[0011] The device frame 10 includes a central frame 111, a right frame 112, and a left frame 113. The central frame 111 forms a framework for mounting various components of the inkjet printer 1, and has a left-to-right width corresponding to the work transport section 20. The right frame 112 and the left frame 113 are erected to the right and left of the central frame 111, respectively. Between the right frame 112 and the left frame 113 is the printing area 12 where printing processing is performed on the work W.

[0012] The right frame 112 forms the maintenance area 13. The maintenance area 13 is an area where the carriage 3 is retracted when the printing process is not being performed. In the maintenance area 13, cleaning and purging processes are performed on the nozzles (ejection holes) of the ink head 4, pre-processing head 5, and post-processing head 6, and caps are fitted. The left frame 113 forms the return area 14 for the carriage 3. The return area 14 is an area where the carriage 3 temporarily enters when it performs a main scan in the opposite direction after performing a main scan in the opposite direction from right to left across the printing area 12 during the printing process.

[0013] A carriage guide 15 for moving the carriage 3 back and forth in the left-right direction is attached to the upper side of the device frame 10. The carriage guide 15 is a flat plate-shaped member that is long in the left-right direction, and is disposed above the work transport unit 20. A timing belt 16 (moving member) is attached to the carriage guide 15 so as to be able to move in a circular motion in the left-right direction (main scanning direction). The timing belt 16 is an endless belt that is driven by a drive source (not shown) to move in a circular motion in the left or right direction.

[0014] The carriage guide 15 is equipped with a pair of upper and lower guide rails 17, which are holding members that hold the carriage 3, extending parallel to the left and right. The carriage 3 is engaged with the guide rails 17. The carriage 3 is also fixed to a timing belt 16. As the timing belt 16 moves leftward or rightward, the carriage 3 moves leftward or rightward along the carriage guide 15 while being guided by the guide rails 17.

[0015] Referring primarily to FIG. 2, the work transport section 20 includes a feed roller 21 that pays out the work W before printing, and a take-up roller 22 that takes up the work W after printing. The feed roller 21 is located at the rear lower part of the device frame 10, and is a take-up shaft for the feed roll WA, which is a wound body of the work W before printing. The take-up roller 22 is located at the front lower part of the device frame 10, and is a take-up shaft for the take-up roll WB, which is a wound body of the work W after the printing process. A first motor M1 is attached to the take-up roller 22, which drives the take-up roller 22 to rotate about its axis and performs the operation of winding up the work W.

[0016] The path between the delivery roller 21 and the take-up roller 22 and passing through the printing area 12 is the transport path for the workpiece W. Arranged on this transport path, in order from upstream, are a first tension roller 23, a work guide 24, a transport roller 25 and a pinch roller 26, a turn-back roller 27, and a second tension roller 28. The first tension roller 23 applies a predetermined tension to the workpiece W on the upstream side of the transport roller 25. The work guide 24 changes the transport direction of the workpiece W from upward to forward, allowing the workpiece W to enter the printing area 12.

[0017] The transport roller 25 is a roller that generates a transport force that intermittently feeds the workpiece W in the printing area 12. The transport roller 25 is driven to rotate around its axis by the second motor M2, and intermittently transports the workpiece W forward (predetermined transport direction F) so that the workpiece W passes through the printing area 12 (image forming position) facing the carriage 3. The pinch roller 26 is disposed so as to face the transport roller 25 from above, and forms a transport nip portion with the transport roller 25.

[0018] The turn-back roller 27 changes the transport direction of the workpiece W that has passed through the printing area 12 from forward to downward, and guides the workpiece W after printing to the take-up roller 22. The second tension roller 28 applies a predetermined tension to the workpiece W downstream of the transport roller 25. A platen 29 is disposed below the transport path of the workpiece W in the printing area 12.

[0019] The carriage 3 is supported at one end by a guide rail 17 and moves back and forth in a main scanning direction (left and right in this embodiment) that intersects (orthogonal in this embodiment) with the transport direction F. The carriage 3 comprises a carriage frame 30, and an ink head 4, a pre-processing head 5, a post-processing head 6, and a sub-tank 7 that are mounted on the carriage frame 30. The carriage frame 30 includes a head support frame 31 and a back frame 32 (engagement portion).

[0020] The head support frame 31 is a horizontal plate that holds the heads 4 to 6 described above. The back frame 32 is a vertical plate that extends upward from the rear end edge of the head support frame 31. As described above, the timing belt 16 is fixed to the back frame 32. The guide rail 17 is engaged with the back frame 32. That is, in this embodiment, the back frame 32 is an engagement portion that is held in a cantilevered state by the guide rail 17. The head support frame 31 is a horizontal plate whose rear end side is supported in a cantilevered state by the engagement portion.

[0021] The cantilevered state refers to a state in which the engagement portion (back frame 32) of the carriage 3 is located only on one side, either upstream or downstream from the center of the carriage 3 in the transport direction F, and no other engagement portion is located on the opposite side of the side where the engagement portion is located. The engagement portion is a portion that is held by the guide rail 17, which is a holding member. The engagement portion may also be located outside the range in which the ink head 4 and processing head are located in the transport direction F. In other words, the engagement portion may be located only on the upstream side or only on the downstream side of the range in which the ink head 4 and processing head are located in the transport direction F.

[0022] [Carriage Details] The carriage 3 will now be described in further detail. Fig. 3 is an enlarged perspective view of the carriage 3 shown in Fig. 1. Fig. 3 shows the transport direction F (sub-scanning direction) of the workpiece W and the main scanning direction S, which is the direction of movement of the carriage 3. Fig. 3 shows an example in which the carriage 3 is equipped with a plurality of ink heads 4 that eject ink for image formation onto the workpiece W, a pre-treatment head 5 and a post-treatment head 6 that eject non-color-forming treatment liquid, and a plurality of sub-tanks 7 that supply the ink and treatment liquid to these heads 4 to 6.

[0023] Each ink head 4 includes a number of nozzles (ink ejection holes) that eject ink droplets using an ejection method such as a piezoelectric method using a piezoelectric element or a thermal method using a heating element, and ink passages that guide the ink to the nozzles. For example, a water-based pigment ink containing a water-based solvent, pigment, and binder resin can be used as the ink. In this embodiment, the ink heads 4 include first to sixth ink heads 4A to 4F, each of which ejects six different colors of ink. For example, the first ink head 4A ejects orange (second color), the second ink head 4B ejects green (second color), the third ink head 4C ejects yellow (first color), the fourth ink head 4D ejects red (first color), the fifth ink head 4E ejects blue (first color), and the sixth ink head 4F ejects black ink (second color).

[0024] The ink heads 4A to 4F of each color are mounted on the head support frame 31 of the carriage 3 so as to be aligned in the main scanning direction S. Each of the ink heads 4A to 4F of each color has two heads. For example, the first ink head 4A is composed of an upstream head 4A1 located upstream in the transport direction F and a downstream head 4A2 located downstream of the upstream head 4A1 and shifted to the left in the main scanning direction S. The ink heads 4B to 4F of the other colors are similar. Each upstream head of these ink heads 4B to 4F is aligned in the main scanning direction S at the same position as the upstream head 4A1 in the transport direction F, and each downstream head is aligned in the main scanning direction S at the same position as the downstream head 4A2 in the transport direction F.

[0025] By arranging them in this manner, the ink heads 4 that eject one color are arranged together in the main scanning direction S. Specifically, all of the ink heads 4 that eject one color and are mounted on the carriage 3 are arranged so that no ink heads 4 that eject other colors are sandwiched between them in the main scanning direction S. Furthermore, all of the ink heads 4 that eject one color and are mounted on the carriage 3 may be arranged within a predetermined range in the main scanning direction S, and no ink heads 4 that eject other colors may be arranged within that range.

[0026] If there is a difference in the printing condition, such as the landing position or ejection amount, between two ink heads 4, the difference is more likely to be noticeable when the two ink heads 4 eject the same color than when the two ink heads 4 eject different colors. If ink heads 4 that eject the same color are arranged together in the main scanning direction S, even if there is a difference in the printing condition between the ink heads 4, it is possible to prevent a decrease in the print image quality.

[0027] The pre-treatment head 5 and post-treatment head 6 are each a type of treatment head that ejects a non-color-forming treatment liquid, which will be described later. The pre-treatment head 5 and post-treatment head 6 are disposed at different positions in the transport direction F from the ink heads 4. The pre-treatment head 5 is disposed upstream of the ink heads 4 in the transport direction F. FIG. 3 shows an example in which one pre-treatment head 5 is disposed near the center of the array of ink heads 4. Similarly, the post-treatment head 6 is disposed downstream of the ink heads 4 in the transport direction F. FIG. 3 shows an example in which two post-treatment heads 6A and 6B (multiple treatment heads) are disposed near the center of the array of ink heads 4, aligned in the main scanning direction S. Various arrangement patterns of the ink heads 4, pre-treatment heads 5, and post-treatment heads 6 on the carriage 3 will be described in detail in Examples 1 to 17, which will be described later.

[0028] As used in the above explanation, a series of heads along the main scanning direction S, which is made up of ink heads 4 and post-treatment heads 6, is referred to as a head row, or simply as a row. A head row may also include a pre-treatment head 5. Furthermore, a series of heads along the transport direction F, which is made up of ink heads 4, pre-treatment heads 5, and post-treatment heads 6, is referred to as a head row, or simply as a row.

[0029] The pretreatment head 5 is a type of treatment head, and ejects a pretreatment liquid to perform a predetermined pretreatment on the workpiece W. The pretreatment liquid is ejected from the ink head 4 onto a position on the workpiece W to which ink has not yet been ejected from the ink head 4. The pretreatment liquid is a non-color-forming treatment liquid that does not develop color even when it adheres to the workpiece W, and is a treatment liquid that exhibits functions such as increasing the fixation of ink to the workpiece W or the coagulation of ink pigments. Examples of such pretreatment liquids that can be used include a treatment liquid in which a binder resin is blended into a solvent, or a treatment liquid in which a positively charged cationic resin is blended into a solvent.

[0030] The post-treatment head 6 is a type of treatment head, and ejects a post-treatment liquid to perform a predetermined post-treatment on the workpiece W to which ink has adhered. The post-treatment liquid is ejected from the post-treatment head 6 onto a position on the workpiece W after the ink has been ejected from the ink head 4. The post-treatment liquid is also a non-color-forming treatment liquid that does not develop color even when it adheres to the workpiece W, and is a treatment liquid that exhibits the function of improving the fixation and robustness (resistance to rubbing and scraping) of the ink image printed on the workpiece W by the ink head 4. A silicone-based treatment liquid or the like can be used as such a post-treatment liquid. Note that the post-treatment liquid and the pre-treatment liquid are different treatment liquids. Specifically, the post-treatment liquid and the pre-treatment liquid contain different components.

[0031] Here, a non-color-forming treatment liquid refers to a treatment liquid that, when printed alone on a recording medium, is not perceived as having a color by the naked eye. Colors here include colors with a saturation of zero, such as black, white, and gray. A non-color-forming treatment liquid is essentially a transparent liquid; however, when viewed in its liquid form, for example, 1 liter of treatment liquid may not be completely transparent, but may appear slightly white. Such colors are so faint that, when printed alone on a recording medium, they are not perceived as having a color by the naked eye. Note that, depending on the type of treatment liquid, when printed alone on a recording medium, changes such as gloss may appear on the recording medium, but such a state is not considered color-forming.

[0032] In this embodiment, the pre-treatment liquid and the post-treatment liquid may be ejected onto almost the entire surface of the workpiece W, or the pre-treatment liquid and the post-treatment liquid may be ejected selectively in accordance with the image to be printed, similar to ink.

[0033] Next, a case where the pretreatment liquid and the posttreatment liquid are selectively ejected will be described. As described above, the pretreatment liquid, ink, and posttreatment liquid are ejected in this order onto the workpiece W in the area where a color is to be printed in accordance with the image. In this case, the ink may be of one color or multiple colors. In areas where no color is to be printed, i.e., areas where no ink is ejected, the pretreatment liquid and the posttreatment liquid are basically not ejected either. Note that, in order to adjust the image quality of the image to be printed and the texture of the workpiece W, the selection of ejection of the pretreatment liquid and the posttreatment liquid may be made to differ from the ejection of the ink.

[0034] Openings 31H are provided at the locations where the heads are arranged in the head support frame 31. The ink heads 4A to 4F, pre-processing head 5, and post-processing head 6 are assembled to the head support frame 31 so as to fit into the respective openings 31H. Nozzles arranged on the lower end surface of each of the heads 4, 5, and 6 are exposed from each opening 31H.

[0035] The sub-tanks 7 are supported by the carriage 3 above the heads 4, 5, and 6 via a holding frame (not shown). A sub-tank 7 is provided corresponding to each of the heads 4, 5, and 6. Each sub-tank 7 is supplied with ink or treatment liquid from a cartridge (not shown) or a main tank that contains the ink and treatment liquid. Each sub-tank 7 supplies the ink or treatment liquid to each of the heads 4, 5, and 6. Each sub-tank 7 and the heads 4, 5, and 6 are connected by pipes (not shown in FIG. 3) (P1, P2, and P3 shown in FIG. 15).

[0036] As described above, the inkjet printer 1 according to this embodiment is an all-in-one printer in which three types of heads - the ink head 4, pre-treatment head 5, and post-treatment head 6 - are mounted on a single carriage 3. With this inkjet printer 1, for example, in the printing process of inkjet printing onto fabric in digital textile printing, the process of ejecting the pre-treatment liquid and the process of ejecting the post-treatment liquid can be carried out in an integrated manner. This makes it possible to simplify the textile printing process and make the textile printing device more compact.

[0037] [Print method] Next, the printing method performed by the inkjet printer 1 according to this embodiment will be described. The inkjet printer 1 performs printing processing on the workpiece W using a serial printing method. Figure 4 is a schematic diagram showing the serial printing method. In Figure 4, the carriage 3 is depicted in a simplified manner, with the pre-processing head 5 and post-processing head 6 omitted.

[0038] If the workpiece W is wide, it is not possible to print while continuously feeding the workpiece W. The serial printing method is a printing method in which a carriage 3 carrying ink heads 4 of each color moves back and forth in the main scanning direction S, and the workpiece W is intermittently fed in the transport direction F, repeatedly. Here, the ink heads 4 have a predetermined printing width Pw in the transport direction F. The printing width Pw is approximately equal to the range in which the ink ejection nozzles of the ink heads 4 are arranged.

[0039] 4 and the following Figures 5A and 5B, the width of each head in the transport direction F is depicted as being approximately equal to the printing width Pw. In reality, the width of each head in the transport direction F is greater than the printing width Pw and the arrangement range of the ejection nozzles.

[0040] FIG. 4 shows the state in which the carriage 3 moves in the forward direction SA in the main scanning direction S and has completed printing of a strip-shaped image G1 with a printing width Pw. During this main scanning in the forward direction SA, the feeding of the workpiece W is stopped. After printing the strip-shaped image G1, the workpiece W is sent out in the transport direction F by a pitch corresponding to the printing width Pw. At this time, the carriage 3 waits in the return area 14 on the left end side. After sending out the workpiece W, the carriage 3 returns in the return direction SB as the timing belt 16 moves in the reverse direction. The workpiece W is in a stationary state. Then, as shown in FIG. 4, the carriage 3 moves in the return direction SB and prints a strip-shaped image G2 with a printing width Pw upstream of the strip-shaped image G1. Similar operations are repeated thereafter.

[0041] 5A and 5B are schematic diagrams showing the printing status of the carriage 3 on its forward and return passes. The ink head 4, pre-treatment head 5, and post-treatment head 6 mounted on the carriage 3 are shown in simplified form. The ink head 4 includes first, second, third, and fourth ink heads 4A, 4B, 4C, and 4D for ejecting ink of different colors (first, second, third, and fourth), respectively. These first to fourth ink heads 4A to 4D are aligned in a line in the main scanning direction S. The pre-treatment head 5 is located upstream of the ink head 4 in the transport direction F, and the post-treatment head 6 is located downstream. As with the case described in FIG. 4, the workpiece W is sent in the transport direction F between the printing on the forward pass and the printing on the return pass. The distance traveled in the transport direction F is the spacing pitch (head pitch) between adjacent heads in the transport direction F. This distance also corresponds to the printing width of each head 4, 5, and 6.

[0042] 5A shows a state in which the carriage 3 is performing a printing operation (outgoing main scanning) while moving in the outgoing direction SA in the main scanning direction S. Area A4 on the workpiece W is an area that faces the pretreatment head 5 mounted on the most upstream side of the carriage 3. During this outgoing main scanning, a pretreatment layer Lpre is formed on area A4 by the pretreatment liquid ejected from the pretreatment head 5.

[0043] Region A3 is one head pitch downstream of region A4 and faces the ink head 4. A pre-treatment layer Lpre has already been formed on region A3 over the entire length in the main scanning direction by the previous backward main scanning. During this forward main scanning, first, second, third, and fourth ink layers LCA, LCB, LCC, and LCD are formed on the pre-treatment layer Lpre in region A3 by the first to fourth color inks ejected sequentially in the aligned order of the first to fourth ink heads 4A to 4D. Note that, for ease of understanding, FIG. 5A illustrates the fourth to first ink layers LCD to LCA as if they were stacked sequentially, but they are not actually stacked. Note that the pre-treatment layer Lpre described above and the post-treatment layer Lpos described below are not formed on the workpiece W either.

[0044] Region A2 is one head pitch downstream of region A3 and faces the post-processing head 6 mounted on the most downstream side of the carriage 3. A pre-processing layer Lpre formed by the previous outgoing main scan and first to fourth ink layers LCA to LCD formed by the previous homeward main scan have already been formed in region A2 over the entire length in the main scanning direction. During this outgoing main scan, a post-processing layer Lpos is formed on the first to fourth ink layers LCA to LCD in region A2 by the post-processing liquid ejected from the post-processing head 6.

[0045] Region A1 is one head pitch downstream of region A2, and is an area where the carriage 3 has passed and printing has been completed. That is, in region A1, a pre-treatment layer Lpre, first to fourth ink layers LCA to LCD, and a post-treatment layer Lpos are formed over the entire length in the main scanning direction.

[0046] 5B shows the state in which, after completing the outward main scan in FIG. 5A, the carriage 3 turns around and moves in the return direction SB while performing the return main scan. Before the return movement, the workpiece W is sent out one head pitch in the transport direction F. Area A5 on the workpiece W is one head pitch upstream of area A4, and is the area that the pretreatment head 5 faces during this return main scan. A pretreatment layer Lpre is formed on area A5 by the pretreatment liquid ejected from the pretreatment head 5.

[0047] In region A4 and region A3, the first to fourth ink layers LCA to LCD and the post-treatment layer Lpos are respectively formed on existing layers. Specifically, in region A4, the first to fourth ink layers LCA to LCD are formed on the pre-treatment layer Lpre. In region A3, the post-treatment layer Lpos is formed on the first to fourth ink layers LCA to LCD. Region A2 is the region where printing processing has been completed following region A1.

[0048] The reason why printing is possible in both the forward main scan and the backward main scan as described above is because the pre-treatment head 5 and the post-treatment head 6 are shifted in the transport direction F relative to the ink head 4. If the pre-treatment head 5, ink head 4, and post-treatment head 6 were aligned in this order in the main scan direction S on the carriage 3, printing that ejects the pre-treatment liquid and the post-treatment liquid in the desired landing order could only be achieved in either the forward or backward main scan. To enable bidirectional printing, the pair of pre-treatment head 5 and post-treatment head 6 would have to be arranged on both sides of the ink head 4 array. In this case, the width of the carriage 3 in the main scan direction S would increase. This arrangement is unnecessary in this embodiment, so the width of the carriage 3 in the main scan direction S can be reduced.

[0049] If there are multiple rows of ink heads 4, it is possible to increase the amount of ink that lands on the workpiece W. For example, if there are two rows of ink heads 4, printing can be performed as follows. After the first row of ink heads 4 forms the first to fourth ink layers LCA to LCD as described above, the workpiece W is transported in the transport direction F by one head pitch, and the second row of ink heads 4 forms the first to fourth ink layers LCA to LCD. In this way, two layers of each color of ink can be printed on the workpiece W.

[0050] [Various head arrangements] Various examples of the arrangement of the ink head 4, pre-processing head 5, and post-processing head 6 on the carriage 3 are illustrated below as Examples 1 to 11. Note that the above-mentioned Figures 1 to 5A and 5B are intended to explain the basic functions of the pre-processing head 5 and post-processing head 6, and the detailed arrangement of the pre-processing head 5 and post-processing head 6 according to this embodiment will be explained in the following Figure 6 and subsequent Figures.

[0051] Example 1 FIG. 6 is a plan view schematically illustrating a head arrangement according to the first embodiment. FIG. 6 also illustrates the arrangement of the ink heads 4, pre-processing head 5, and post-processing head 6 (multiple processing heads) on the carriage 3 shown in FIG. 3. The carriage 3 is supported in a cantilevered manner by the guide rails 17 at the back frame 32 (engagement portion). The back frame 32 is arranged upstream of the head support frame 31 in the transport direction F. In the transport direction F, the side of the head support frame 31 on which the back frame 32 is arranged is referred to as the base end side 311, and the side of the head support frame 31 opposite the base end side 311 is referred to as the tip end side 312. As described above, the head support frame 31 of the carriage 3 is equipped with first to sixth ink heads 4A to 4F, which eject six different colors of ink, the pre-processing head 5, and the post-processing head 6. Each of the ink heads 4A to 4F of each color has two unit heads (12 in total). There is one pre-processing head 5, but two post-processing heads 6.

[0052] The group of first to sixth ink heads 4A to 4F that make up the ink head 4 are arranged side by side in the main scanning direction S in the central region of the head support frame 31 in the transport direction F. The pre-processing head 5 is arranged at approximately the center of the carriage 3 in the main scanning direction S, upstream of the ink heads 4 in the transport direction F, on the base end side 311 of the head support frame 31. Meanwhile, the post-processing head 6 is arranged at approximately the center of the carriage 3 in the main scanning direction S, downstream of the ink heads 4 in the transport direction F, on the tip end side 312 of the head support frame 31. Both the pre-processing head 5 and the post-processing head 6 are arranged near the center of the head support frame 31 in the main scanning direction S.

[0053] The first ink head 4A includes an upstream head 4A1 and a downstream head 4A2 disposed downstream of the upstream head 4A1. That is, the upstream head 4A1 and the downstream head 4A2 are arranged in the transport direction F. The upstream head 4A1 is disposed closer to the base end 311 in the central region of the head support frame 31. The downstream head 4A2 is disposed closer to the tip end 312 in the central region of the head support frame 31. The downstream head 4A2 is disposed shifted to one side (left side) in the main scanning direction S relative to the upstream head 4A1, and is disposed in a position that partially overlaps with the transport direction F. Of course, the upstream head 4A1 and the downstream head 4A2 may also be arranged in the same position in the main scanning direction S (positions aligned linearly in the transport direction F). However, the arrangement in this embodiment allows for a smaller size of the carriage 3 in the transport direction F.

[0054] The second to sixth ink heads 4B to 4F also include upstream heads 4B1, 4C1, 4D1, 4E1, and 4F1 and downstream heads 4B2, 4C2, 4D2, 4E2, and 4F2, similar to the upstream head 4A1 and downstream head 4A2 described above. The upstream heads 4A1 to 4F1 of the first to sixth ink heads 4A to 4F are aligned in a row at the same position in the transport direction F and at a predetermined interval in the main scanning direction S. The downstream heads 4A2 to 4F2 are also aligned in a row at the same position in the transport direction F and at a predetermined interval in the main scanning direction S. As a result, a staggered arrangement is formed in which a portion of the downstream heads 4A2 to 4F2 is inserted between each of the arrangement pitches of the upstream heads 4A1 to 4F1.

[0055] In other words, the ink head 4 has multiple ink head rows mounted on the carriage 3 and aligned in the transport direction F. Each of the multiple ink head rows includes multiple ink heads aligned in the main scanning direction S, each ejecting ink for image formation. In the example shown in FIG. 6, the multiple ink head rows include a first ink head row 41 and a second ink head row 42. The ink heads included in the first ink head row 41 are upstream heads 4A1, 4B1, 4C1, 4D1, 4E1, and 4F1. The ink heads included in the second ink head row 42 are downstream heads 4A2, 4B2, 4C2, 4D2, 4E2, and 4F2.

[0056] The pre-treatment head 5 is disposed so that a portion of it is sandwiched between a pair of adjacent ink heads in the main scanning direction S. Specifically, the positional relationship is such that the downstream portion of the pre-treatment head 5 is sandwiched between the upstream head 4C1 of the third ink head 4C and the upstream head 4D1 of the fourth ink head 4D.

[0057] The post-processing head 6 includes a first post-processing head 6A and a second post-processing head 6B arranged side by side in the main scanning direction S. FIG. 6 shows an example in which the first and second post-processing heads 6A and 6B are arranged at the same position in the transport direction F and at a predetermined interval in the main scanning direction S. The first post-processing head 6A is arranged between the downstream head 4C2 of the third ink head 4C and the downstream head 4D2 of the fourth ink head 4D, with its upstream portion intervening. The second post-processing head 6B is arranged between the downstream head 4D2 and the downstream head 4E2, with its upstream portion intervening, and is arranged at the same position in the main scanning direction S as the upstream head 4D1. This arrangement results in an overlapping area fa between the first and second post-processing heads 6A and 6B and the downstream heads 4C2, 4D2, and 4E2 in the transport direction F.

[0058] The width of each head is greater than the printing width Pw and the arrangement range of the ejection nozzles in the transport direction F. For this reason, the heads are arranged to have an overlapping area fa so that there is no space between the printing range Pw of each row of heads and the printing range Pw of the heads in the adjacent row.

[0059] Unless otherwise specified, in each of the figures including Figure 6, the distance between adjacent heads in the main scanning direction S (the distance between the centers of the heads) is the same. Similarly, the distance between adjacent heads in the transport direction F (the distance between the centers of the heads) is the same.

[0060] As a result of the head arrangement described above, the pre-treatment head 5 and post-treatment head 6 are arranged within an arrangement width H of the ink heads 4 in the main scanning direction S. The ink heads 4 have an arrangement width H in the main scanning direction S, extending from the downstream head 4A2 of the first ink head 4A to the upstream head 4F1 of the sixth ink head 4F. The pre-treatment head 5 is arranged within the arrangement width H on the upstream side of the ink heads 4, and the post-treatment head 6 is arranged within the arrangement width H on the downstream side of the ink heads 4. In particular, in Example 1, the pre-treatment head 5 and post-treatment head 6 are located approximately in the center of the array of all heads in the main scanning direction S.

[0061] The head arrangement according to the first embodiment described above allows for a compact carriage 3 while increasing the required ink and treatment liquid ejection volume. That is, the pre-treatment head 5 and post-treatment head 6 are arranged at different positions in the transport direction F from the ink head 4. This configuration allows for the ink heads 4A-4F, which can eject a large amount of ink, to be arranged in the main scanning direction S, and enables printing in both forward and backward main scanning, while also reducing the main scanning width of the carriage required to mount the heads 4-6. Furthermore, the post-treatment head 6 is comprised of a plurality of first and second post-treatment heads 6A and 6B, which are arranged side by side in the main scanning direction S. Therefore, even if a single head does not eject enough post-treatment liquid, the arrangement of multiple post-treatment heads 6A and 6B allows for the ejection of the required amount of post-treatment liquid.

[0062] The first to sixth ink heads 4A to 4F each include upstream heads 4A1 to 4F1 (first ink head row 41) and downstream heads 4A2 to 4F2 (second ink head row 42) arranged in the transport direction F (a direction intersecting the arrangement direction of the multiple processing heads). Therefore, even if the number of ink heads 4 is increased to increase the amount of ink ejected for each color or to achieve multi-color printing, it is difficult to increase the width of the carriage 3 in the main scanning direction.

[0063] The pre-processing head 5 and post-processing head 6 are arranged within the range of the arrangement width H of the first to sixth ink heads 4A to 4F in the main scanning direction S. Therefore, even when the pre-processing head 5 and post-processing head 6 are mounted on the carriage 3 in addition to the ink heads 4, there is no need to increase the width of the carriage 3 in the main scanning direction. In other words, it is possible to prevent the width of the carriage 3 in the main scanning direction from becoming too large.

[0064] The pre-processing head 5 and post-processing head 6 are arranged so that some of them fit between the arrangement pitches of the first to sixth ink heads 4A to 4F. Looking at the first post-processing head 6A, a portion of the first post-processing head 6A fits between the pair of downstream heads 4C2 and 4D2. This staggered arrangement allows the ink heads 4 and processing heads 5 and 6, which are arranged at different positions in the transport direction F, to be arranged at high density in the transport direction F. This allows the width of the carriage 3 in the transport direction F to be reduced.

[0065] In the head arrangement of Example 1, one pre-treatment head 5 is arranged upstream of the ink head 4 in the transport direction F, and two post-treatment heads 6A and 6B are arranged downstream. In other words, it is possible to provide an all-in-one inkjet printer 1 in which three types of heads, namely heads for ejecting pre-treatment liquid, ink, and post-treatment liquid, are mounted on a single carriage 3. Furthermore, because the pre-treatment head 5, ink head 4, and post-treatment head 6 are arranged sequentially in the transport direction F, the pre-treatment liquid, ink, and post-treatment liquid can be ejected in a desired landing order in both the forward main scan and the backward main scan.

[0066] The carriage 3 also has a back frame 32 (engagement portion) that is held in a cantilevered state by a guide rail 17 (holding member) (Fig. 1). By supporting the carriage 3 in a cantilevered manner on the timing belt 16, the structure can be simplified. Furthermore, by supporting the carriage 3 in a cantilevered manner, the downstream side of the carriage 3 can be easily opened, making it easier to perform maintenance on the ink head 4 and the processing heads 5 and 6.

[0067] In the carriage 3 supported in a cantilevered manner in this manner, the pre-processing head 5 is disposed on the base end side 311 (the side closer to the engagement portion) of the head support frame 31, and the post-processing head 6 is disposed on the tip end side 312 (the side farther from the engagement portion). Unlike the base end side 311, which is close to the back frame 32 fixed to the timing belt 16, it is expected that the positional accuracy will decrease on the tip end side 312, which is the free end. However, the tip end side 312 is equipped with the post-processing head 6, which does not require a relatively high level of ejection accuracy. Because the post-processing liquid coats the ink image printed on the workpiece W, even if a misalignment in the landing position occurs, the relative impact on image quality can be smaller than if a similar misalignment in the landing position occurs with the pre-processing liquid. Therefore, even when a cantilevered carriage 3 is used, degradation of image quality is less likely to occur.

[0068] <Challenges in head placement> As described above, in addition to the ink head 4, a pre-treatment head 5 that ejects a pre-treatment liquid and a post-treatment head 6 that ejects a post-treatment liquid are each mounted on the carriage 3, and when the pre-treatment liquid, ink, and post-treatment liquid are ejected sequentially onto the workpiece W as the carriage 3 moves back and forth in the main scanning direction, depending on the image position in the main scanning direction S, variations occur in the time from when the pre-treatment liquid lands to when the ink lands and the time from when the ink lands to when the post-treatment liquid lands, resulting in a problem in which variations in image quality are likely to occur on the workpiece W.

[0069] For example, when a pretreatment liquid that enhances the cohesion of ink pigments is used, the longer the time between the pretreatment liquid landing and the ink landing, the deeper the color. Furthermore, when a posttreatment liquid that enhances fastness is used, the longer the time between the ink landing and the posttreatment liquid landing, the deeper the color. When printing using these liquids, the longer the time between the pretreatment liquid landing and the posttreatment liquid landing, the deeper the color. When ink of the same color lands multiple times, the time between the pretreatment liquid landing and the first ink landing after that landing has a relatively large effect on the color density for the pretreatment liquid. For the posttreatment liquid, the time between the posttreatment liquid landing and the last ink landing before that landing has a relatively large effect on the color density.

[0070] In order to solve the above-mentioned problems, the present inventors have newly discovered that by appropriately setting the arrangement of the pre-treatment head 5 and the post-treatment head 6 on the carriage 3, it is possible to reduce the variation in the time from the impact of the pre-treatment liquid to the impact of the ink, and the variation in the time from the impact of the ink to the impact of the post-treatment liquid, even between different image positions in the main scanning direction S. The concept of head arrangement based on this new perspective and examples of such arrangements (embodiments) will be described below.

[0071] <Head placement concept> FIG. 7 is a schematic diagram for explaining the landing times of the pre-treatment liquid, ink, and post-treatment liquid at point P on the workpiece W. In FIG. 7, a printing area 12 is located in the center, with a maintenance area 13 and a turn-around area 14 located on either side of the printing area 12. As described above, the carriage 3 moves between the maintenance area 13 and the turn-around area 14 in the main scanning direction S, causing the ink, pre-treatment liquid, and post-treatment liquid to be ejected from the ink head 4, pre-treatment head 5, and post-treatment head 6 onto the workpiece W. Note that, for the sake of explanation, FIG. 7 illustrates the carriage 3 in both the maintenance area 13 and the turn-around area 14. The following description will be given taking as an example a case where the ink head 4 has multiple ink head rows, and printing is performed while the workpiece W is intermittently fed at one head pitch (the pitch between adjacent heads in the transport direction F).

[0072] 7, of the ink heads and processing heads (pre-processing head 5 and post-processing head 6) included in the ink head rows 41, 42, the head located closest to one end in the main scanning direction S is referred to as the first end head, and the head located closest to the other end is referred to as the other end head. The distance in the main scanning direction S from the first end head to the other end head is defined as LC, the distance in the main scanning direction S from the first end head to the pre-processing head 5 is defined as B1, the distance in the main scanning direction S from the first end head to a predetermined ink head (in FIG. 7, head 4D1 upstream of fourth ink head 4D) is defined as K, and the distance in the main scanning direction S from the first end head to post-processing head 6 is defined as B2. In the example shown in FIG. 7, the first end head is head 4A2 downstream of first ink head 4A, and the other end head is head 4F1 upstream of sixth ink head 4F. The distances LC, K, B1, and B2 may be set based on a portion of each head, but the following description will be given assuming that the distances are set based on the center of each head in the main scanning direction S. The heads on one end and the heads on the other end may be reversed.

[0073] The center of the head in the main scanning direction S basically refers to the position of an imaginary line in the main scanning direction S that bisects the area of ​​the planar shape of the head when viewed from above and intersects with the main scanning direction S. In some cases, it is also possible to consider an imaginary line that bisects the area of ​​the smallest convex polygon that includes all of the head's ejection nozzles when viewed from above and intersects with the main scanning direction S and intersects with the main scanning direction S, and the position of that imaginary line in the main scanning direction S may be the center of the head in the main scanning direction S.

[0074] First, we will explain the timing at which each liquid lands at point P on the workpiece W within the printing area 12. Note that because the movement speed of the carriage 3 is constant, the following explanation will use distance. The actual timing (time) can be calculated by dividing each distance by the movement speed of the carriage 3. Note that we will assume that point P is located at a distance A from the end of the printing area 12 on the maintenance area 13 side.

[0075] Also, here, it is assumed that the liquid is ejected from the center of the head in the main scanning direction S. If the nozzles of each head are actually distributed over a wide area in the main scanning direction S, that distribution also affects the timing of impact. However, the difference in the position of nozzles in one head in the main scanning direction S is often smaller than the difference in the position of nozzles in a different head in the main scanning direction S, so it is possible to estimate the impact of head arrangement by assuming that the liquid is ejected from the center of the head in the main scanning direction S.

[0076] For ease of understanding, the explanation is given as if the timing of ejection and the timing of impact are simultaneous. In reality, ejection is performed earlier than the timing of impact by the amount of flight time it takes for the liquid to fly from the head to the workpiece W so that the liquid impacts at a predetermined position at a predetermined timing.

[0077] The one-way movement distance of the carriage 3 (the distance traveled from the maintenance area 13 to the turning area 14) is set to the minimum distance LP+LC required for printing, and the carriage 3 is assumed to be initially positioned in the maintenance area 13. In this case, during the first movement operation (movement to the left) in which the carriage 3 moves from the maintenance area 13 to the turning area 14, the timing T1 at which the pretreatment liquid ejected from the pretreatment head 5 lands on point P can be expressed in distance terms by the following equation A.

[0078] T1=A+B1 (Formula A)

[0079] After the pretreatment liquid lands at point P, during a second movement operation (movement to the right) in which the carriage 3 moves from the turning area 14 to the maintenance area 13, ink is ejected from each ink head of the first ink head row 41 to point P. Furthermore, during a third movement operation (movement to the left) in which the carriage 3 further moves from the maintenance area 13 to the turning area 14, ink is ejected from each ink head of the second ink head row 42 to point P.

[0080] In the above, the timing T2 at which red ink (also referred to as the first ink or initial ink) from the upstream head 4D1 of the fourth ink head 4D lands on point P can be expressed by the following equation B.

[0081] T2=(LP+LC)+(LP-A)+(LC-K) (Formula B)

[0082] The first bracket in the above equation B corresponds to the time it takes for the carriage 3 to move from the maintenance area 13 to the turnaround area 14 in the first movement operation, the second bracket corresponds to the time it takes for the tip of the carriage 3 to reach point P in the second movement operation, and the third bracket corresponds to the time it takes for the carriage 3 to move further and for the specified ink head to reach point P.

[0083] From the above formulas A and B, the time ΔT from the landing of the pretreatment liquid at point P to the landing of the first ink can be expressed by the following formula C.

[0084] ΔT=T2-T1=LP-2A+LC-(B1+K)+LP+LC (Formula C)

[0085] On the other hand, the carriage 3 may first move from the turn-back area 14, that is, move to the right as the first movement operation, during printing on the workpiece W. In this case, similar to the above, the time ΔT from when the pretreatment liquid lands at point P to when the first (initial) red ink lands can be expressed by the following equation D.

[0086] ΔT=2A-LP-(LC-(B1+K))+(LP+LC) (Formula D)

[0087] Here, to consider all points on the workpiece W in the printing area 12, the distance A can be considered to vary from 0 to LP, and therefore the range of ΔT from the above equations C and D can be expressed by the following equations E, F, and G.

[0088] ΔTmin1≦ΔT≦ΔTmax1 (Formula E) ΔTmin1=-LP-|LC-(B1+K)|+(LP+LC) (Formula F) ΔTmax1=LP+|LC-(B1+K)|+(LP+LC) (Formula G)

[0089] Next, using the same concept as above, we will explain the time ΔT from when the red ink (also called the second ink or the final ink) ejected by the downstream head 4D2 of the fourth ink head 4D lands at point P until the post-treatment liquid lands. When the first movement operation is movement to the left from the maintenance area 13 to the turning area 14, the time ΔT from when the red ink of the downstream head 4D2 lands at point P until the post-treatment liquid lands can be expressed by the following formula H.

[0090] ΔT=LP-2A+(LC-(K+B2))+(LP+LC) (Formula H) If the ink head 4 has an even number of rows of ink heads along the transport direction F, the second ink droplet will land after the first ink droplet, as expressed by formula C. On the other hand, if the ink head 4 has an odd number of rows of ink heads along the transport direction F, the second ink droplet will land after the first ink droplet, as expressed by formula D.

[0091] Similarly, when the first movement operation is a movement to the right from the turning area 14 to the maintenance area 13, the time ΔT from when the red ink of the downstream head 4D2 lands at point P to when the post-treatment liquid lands can be expressed by the following equation I.

[0092] ΔT=2A-LP-(LC-(K+B2))+(LP+LC) (Formula I) In this case, if the ink head 4 has an even number of ink head rows along the transport direction F, the second ink droplet will land after the first ink droplet, as expressed by formula D. On the other hand, if the ink head 4 has an odd number of ink head rows along the transport direction F, the second ink droplet will land after the first ink droplet, as expressed by formula C.

[0093] Similarly, to consider all points on the workpiece W in the printing area 12, the distance A can be considered to vary from 0 to LP, and therefore the range of ΔT from the above equations H and I can be expressed by the following equations J, K, and L.

[0094] ΔTmin2≦ΔT≦ΔTmax2 (Formula J) ΔTmin2=-LP-|LC-(K+B2)|+(LP+LC) (Formula K) ΔTmax2=LP+|LC-(K+B2)|+(LP+LC) (Formula L)

[0095] In Equations E to G and Equations J to L, to include all ink head arrangements, K must be in the range of 0 to LC, and therefore, when the absolute values ​​of LC-(B1+K) and LC-(K+B2) are small, it is possible to prevent the occurrence of colors with large time variations in ΔT. In other words, the closer B1 and B2 are to LC / 2, the more it is possible to prevent the occurrence of colors with large time variations. Considering only this landing timing, it is most desirable for both B1 and B2 to be LC / 2.

[0096] As a result of extensive experiments and studies, the present inventors have discovered that when the following formula 1 is satisfied, it is possible to form a stable image while reducing the variation in the time from when the pretreatment liquid lands on the workpiece W to when the ink lands, regardless of the direction of movement of the carriage 3. |(B1-LC / 2)| / LC ≦ 1 / 4 (Formula 1)

[0097] Similarly, it has been found that when the following formula 2 is satisfied, it is possible to form a stable image while reducing the variation in the time from when the ink lands on the workpiece W to when the post-treatment liquid lands. |(B2-LC / 2)| / LC ≦ 1 / 4 (Formula 2)

[0098] When multiple pretreatment heads 5 are arranged, it is desirable that at least one pretreatment head 5 is arranged so as to satisfy Formula 1. In this way, by arranging at least one pretreatment head 5 so as to satisfy Formula 1, it is possible to reduce the variation in the time from the impact of the pretreatment liquid to the impact of the ink, and in addition, since more pretreatment liquid can be ejected from the other pretreatment heads 5, it is possible to increase the amount of pretreatment liquid that can be ejected.

[0099] It is more desirable that all of the above-mentioned multiple pretreatment heads 5 are arranged so as to satisfy formula 1. In this case, it is possible to further reduce the variation in the time from the impact of the pretreatment liquid to the impact of the ink, and to increase the amount of treatment liquid that can be ejected.

[0100] Similarly, when multiple post-processing heads 6 are arranged, it is desirable that at least one post-processing head 6 is arranged so as to satisfy formula 2. In this way, by arranging at least one post-processing head 6 so as to satisfy formula 2, it is possible to reduce the variation in the time from ink impact to post-processing liquid impact, and since post-processing liquid can be further ejected from other post-processing heads 6, it is possible to increase the amount of post-processing liquid that can be ejected.

[0101] It is more desirable that all of the above-mentioned multiple post-treatment heads 6 are arranged so as to satisfy formula 2. In this case, it is possible to further reduce the variation in the time from ink impact to post-treatment liquid impact, and to increase the amount of post-treatment liquid that can be ejected.

[0102] In the first embodiment, both the pre-treatment head 5 and the post-treatment head 6 are mounted on the carriage 3, but the carriage 3 may be mounted with only the pre-treatment head 5 or only the post-treatment head 6. If Formula 1 is satisfied in a carriage 3 equipped with an ink head 4 and only the pre-treatment head 5 as the processing head, the variation in the time from the impact of the pre-treatment liquid to the impact of the ink can be reduced. If Formula 2 is satisfied in a carriage 3 equipped with an ink head 4 and only the post-treatment head 6 as the processing head, the variation in the time from the impact of the ink to the impact of the pre-treatment liquid can be reduced.

[0103] Next, we will explain a more desirable arrangement of the pre-treatment head 5 and post-treatment head 6 defined by the above equations 1 and 2. Considering equations E to G, the range of ΔT differs among the first to sixth ink heads 4A to 4F. That is, the range of ΔT differs depending on the value of K. In the example shown in FIG. 7, when B1>LC / 2, the larger the value of K, the greater the range of variation in ΔT. In other words, the time variation is greatest for the black ink of the sixth ink head 4F among the ink heads 4. Furthermore, when the first movement operation is movement leftward from the maintenance area 13 to the turning area 14, the variation time of ΔT is smallest at the position A=LP. When the first movement operation is movement rightward from the turning area 14 to the maintenance area 13, the variation time of ΔT is largest at the position A=LP.

[0104] In the above example, because there is a large variation in the time between the landing of the pre-treatment liquid and the landing of the first black ink, if the variation in the time between the landing of the second black ink and the landing of the post-treatment liquid also becomes large, the variation in image quality of the black image becomes more noticeable compared to images of other colors, and the image becomes more likely to be visually affected. For this reason, it is desirable to reduce the variation in the time between the landing of the second black ink and the landing of the post-treatment liquid for the sixth ink head 4F, which ejects black ink with a large K value. Specifically, it is desirable to position the post-treatment head 6 so that B2 is small.

[0105] The present inventors have conducted similar studies to those described above for each ink head 4, and as a result have found that when a carriage 3 is equipped with multiple ink head rows including ink heads that eject ink of the same color, and the ink heads 4 are arranged in groups in the main scanning direction by color, there is a large variation in the time from when the pre-treatment liquid lands to when the first ink lands for a given color of ink, and in order to prevent further large variation in the time from when the second ink lands to when the post-treatment liquid lands, it is effective to set the absolute value of (B1+B2-LC) / LC to be small, and it is desirable that the following formula 3 be satisfied, and it is even more desirable that formula 4 be satisfied.

[0106] |(B1+B2-LC) / LC| ≦ 1 / 2 (Formula 3) |(B1+B2-LC) / LC| ≦ 1 / 3 (Formula 4)

[0107] Based on the above-described concept, in the head arrangement having two ink head arrays shown in Example 1 of FIG. 6 , the distance in the main scanning direction S from the downstream head 4A2 of the first ink head 4A to the upstream head 4F1 of the sixth ink head 4F is LC=11, the distance in the main scanning direction S from the downstream head 4A2 to the pre-treatment head 5 is B1=6, and the distance in the main scanning direction S from the downstream head 4A2 to each post-treatment head 6 is B2=5 or 7. In this case, |(B1-LC / 2)| / LC=0.045, which satisfies the above formula 1. Also, |(B2-LC / 2)| / LC=0.045 or 0.136, which both satisfy the above formula 2. Therefore, it is possible to reduce the variation in the time from the impact of the pre-treatment liquid to the impact of the ink ejected by the first ink head array 41 and the variation in the time from the impact of the ink ejected by the second ink head array 42 to the impact of the post-treatment liquid. As a result, it is possible to stably and sequentially land the pretreatment liquid, ink, and posttreatment liquid on the workpiece W, reducing the likelihood of variations in image quality on the workpiece W. Furthermore, |(B1+B2-LC) / LC| = 0 or 0.18, both of which satisfy the above-mentioned formulas 3 and 4. Therefore, when a plurality of ink head rows including ink heads that eject ink of the same color are mounted on the carriage 3, it is possible to prevent not only large variations in the time from when the pretreatment liquid lands until the first ink lands for a given color of ink, but also large variations in the time from when the second ink lands until the posttreatment liquid lands.

[0108] As mentioned above, one of the first post-processing head 6A and the second post-processing head 6B may be positioned in a position that does not satisfy the above formulas 1 to 4, but it is most desirable that both post-processing heads 6 satisfy the above formulas 1 to 4, as shown in Figure 6.

[0109] <Example 2> FIG. 8 is a plan view of a carriage 3A showing the head arrangement according to Example 2. In Example 2, the ink heads 4 also include a first ink head row 41 and a second ink head row 42, and the pre-treatment head 5 and post-treatment head 6 are positioned approximately at the center of the entire head array in the main scanning direction S. In this head arrangement, LC = 11, B1 = 6, and B2 = 5. In this case, |(B1 - LC / 2)| / LC = 0.045, which satisfies the above formula 1. Furthermore, |(B2 - LC / 2)| / LC = 0.045, which satisfies the above formula 2. Therefore, it is possible to reduce the time variance between the landing of the pre-treatment liquid and the landing of the ink ejected by the first ink head row 41, and the time variance between the landing of the ink ejected by the second ink head row 42 and the landing of the post-treatment liquid. Furthermore, |(B1 + B2 - LC) / LC| = 0, which satisfies the above formulas 3 and 4. Therefore, when a carriage 3 is equipped with multiple ink head rows including ink heads that eject ink of the same color, it is possible to prevent a large variation in the time from the landing of the pre-treatment liquid to the landing of the first ink for a given color of ink, as well as a large variation in the time from the landing of the second ink to the landing of the post-treatment liquid.

[0110] Example 3 Furthermore, FIG. 9 is a plan view of a carriage 3B showing the head arrangement according to Example 3. In Example 3, the ink head row is a single row. Also in Example 3, the pre-processing head 5 and post-processing head 6 are positioned approximately in the center of the array of all heads in the main scanning direction S. In the head arrangement in FIG. 9, LC = 6, B1 = 3, and B2 = 3. In this case, |(B1 - LC / 2)| / LC = 0, which satisfies the above formula 1. Also, |(B2 - LC / 2)| / LC = 0, which satisfies the above formula 2. Also, |(B1 + B2 - LC) / LC| = 0, which satisfies the above formulas 3 and 4. Therefore, the same effects as in Examples 1 and 2 can be achieved.

[0111] Desirable head arrangements will be further explained below based on other embodiments.

[0112] Example 4 FIG. 10 is a plan view schematically illustrating a carriage 3D equipped with a head arrangement according to Example 4. Example 4 differs from Example 1 in that the number of unit heads is increased. That is, the ink head 4 is the same as Example 1 in that it includes first to sixth ink heads 4A to 4F, each of which ejects six different colors of ink. However, each of the ink heads 4A to 4F for each color includes three unit heads (18 in total). In other words, the ink head 4 has three ink head rows (odd-numbered rows), including a first ink head row 41, a second ink head row 42, and a third ink head row 43. The pre-treatment head 5, which is located upstream of the ink head 4 in the transport direction F, includes two unit heads, and the post-treatment head 6, which is located downstream, includes three unit heads. Note that, like Example 1, the pre-treatment head 5 and the post-treatment head 6 are each arranged within the arrangement width of the ink head 4 in the main scanning direction S.

[0113] The first ink head 4A includes an upstream head 4AA, a central head 4AB, and a downstream head 4AC as the unit heads. The upstream head 4AA is arranged at the most upstream side of the first ink heads 4A in the transport direction F of the carriage 3A. The downstream head 4AC is arranged downstream of the upstream head 4AA at the same position in the main scanning direction S as the upstream head 4AA. The central head 4AB is shifted to the right in the main scanning direction S relative to the upstream head 4AA and downstream head 4AC, and is arranged downstream of the upstream head 4AA and upstream of the downstream head 4AC in the transport direction F. The central head 4AB is arranged in a position that partially overlaps with the upstream head 4AA and downstream head 4AC in the transport direction F.

[0114] The second to sixth ink heads 4B to 4F also include upstream heads 4BA, 4CA, 4DA, 4EA, and 4FA, central heads 4BB, 4CB, 4DB, 4EB, and 4FB, and downstream heads 4BC, 4CC, 4DC, 4EC, and 4FC, similar to the upstream head 4AA, central head 4AB, and downstream head 4AC described above. The upstream heads 4AA to 4FA, central heads 4BB to 4FB, and downstream heads 4BC to 4FC of the first to sixth ink heads 4A to 4F are aligned in a row at the same position in the transport direction F and at a predetermined interval in the main scanning direction S. The ink heads 4 are also arranged in groups in the main scanning direction by color.

[0115] The pre-processing heads 5 include a first pre-processing head 5A and a second pre-processing head 5B that are arranged side by side at an interval in the main scanning direction S and at the same position in the transport direction F. The first pre-processing head 5A is arranged between the head 4CA upstream of the third ink head 4C and the head 4DA upstream of the fourth ink head 4D, with a portion of its downstream side extending therebetween. The second pre-processing head 5B is arranged between the head 4DA upstream of the fourth ink head 4D and the head 4EA upstream of the fifth ink head 4E, with a portion of its downstream side extending therebetween.

[0116] The post-processing heads 6 include a first post-processing head 6A, a second post-processing head 6B, and a third post-processing head 6C, which are aligned at the same position in the transport direction F and spaced apart in the main scanning direction S. The first post-processing head 6A is positioned between the downstream head 4BC of the second ink head 4B and the downstream head 4CC of the third ink head 4C, with a portion of its upstream side extending therebetween. The second post-processing head 6B is positioned between the downstream head 4CC of the third ink head 4C and the downstream head 4DC of the fourth ink head 4D, with a portion of its upstream side extending therebetween. The third post-processing head 6C is positioned between the downstream head 4DC of the fourth ink head 4D and the downstream head 4EC of the fifth ink head 4E, with a portion of its upstream side extending therebetween.

[0117] In the head arrangement shown in FIG. 10, the upstream head 4AA or the downstream head 4AC of the first ink head 4A is the head at one end, and LC=11, B1=5, 7, and B2=3, 5, 7. In this case, |(B1-LC / 2)| / LC=0.045, 0.136, both of which satisfy the above formula 1. Also, |(B2-LC / 2)| / LC=0.227, 0.045, 0.136, both of which satisfy the above formula 2. Furthermore, when B1=5, |(B1+B2-LC) / LC|=0.273, 0.091, 0.091 for each value of B2, both of which satisfy the above formulas 3 and 4. Furthermore, when B1=7, |(B1+B2-LC) / LC|=0.091, 0.091, 0.272 for each value of B2, both of which satisfy the above formulas 3 and 4. Therefore, the same effects as those of the first and second embodiments can be achieved.

[0118] Furthermore, the head arrangement according to the fourth embodiment can provide the same advantages as those of the first embodiment. That is, the required ink and treatment liquid ejection amounts can be increased while miniaturizing the carriage 3D. In particular, in the fourth embodiment, since both the pre-treatment head 5 and the post-treatment head 6 are configured to include a plurality of unit heads, the ejection amounts of the pre-treatment liquid and the post-treatment liquid can be sufficiently increased. The first to sixth ink heads 4A to 4F also include unit heads arranged in three rows, so the ejection amounts of the ink can also be sufficiently increased.

[0119] <Example 5> 11 is a plan view that schematically shows a carriage 3E equipped with a head arrangement according to Example 5. In Example 5, similar to Example 1 (FIG. 6), an example is shown in which the pre-processing head 5 and the post-processing head 6 are arranged in the central region HC of the arrangement width H. However, Example 5 differs from Example 1 in the arrangement of the ink heads 4, as will be described later.

[0120] The head support frame 31 of the carriage 3E is equipped with first to sixth ink heads 4A to 4F, each of which ejects six different colors of ink, a pre-processing head 5, and a post-processing head 6. The first to sixth ink heads 4A to 4F are equipped with unit heads arranged in two rows, similar to Example 1. However, the shift direction of the downstream heads of each of the ink heads 4A to 4F is opposite to Example 1, with the downstream head 4A2 of the first ink head 4A being positioned to the right of the upstream head 4A1. There is one pre-processing head 5, and two post-processing heads 6, first and second post-processing heads 6A and 6B.

[0121] The pre-treatment head 5 and post-treatment head 6 are arranged in a central region HC of the arrangement width H in the main scanning direction S of the first to sixth ink heads 4A to 4F. As with the above-mentioned Example 1, the pre-treatment head 5 is arranged on the upstream side of the arrangement of the first to sixth ink heads 4A to 4F in the transport direction F, and the post-treatment head 6 is arranged on the downstream side. The pre-treatment head 5 is arranged at the same position in the main scanning direction S as the downstream head 4C2 of the third ink head 4C, and on the upstream side in the transport direction F. The pre-treatment head 5 is arranged between the upstream heads 4C1 and 4D1 of the third and fourth ink heads 4C and 4D, with a portion of its downstream side sandwiched between them.

[0122] The first and second post-processing heads 6A and 6B are aligned at the same position in the transport direction F and spaced a predetermined distance apart in the main scanning direction S. The first post-processing head 6A is positioned such that its upstream portion is between the downstream head 4B2 of the second ink head 4B and the downstream head 4C2 of the third ink head 4C. The second post-processing head 6B is positioned such that its upstream portion is between the downstream head 4C2 and the downstream head 4D2 of the fourth ink head 4D.

[0123] In this head arrangement in Example 5, the distance in the main scanning direction S from the upstream head 4A1 of the first ink head 4A to the downstream head of the sixth ink head 4F is LC=11, the distance in the main scanning direction S from the upstream head 4A1 to the pre-treatment head 5 is B1=5, and the distance in the main scanning direction S from the upstream head 4A1 to each post-treatment head 6 is B2=4 or 6. In this case, |(B1-LC / 2)| / LC=0.045, which satisfies the above formula 1. Also, |(B2-LC / 2)| / LC=0.136 or 0.045, which both satisfy the above formula 2. Therefore, it is possible to reduce the variation in the time from the landing of the pre-treatment liquid to the landing of the ink ejected by the first ink head row 41 and the variation in the time from the landing of the ink ejected by the second ink head row 42 to the landing of the post-treatment liquid. As a result, it is possible to stably and sequentially land the pretreatment liquid, ink, and posttreatment liquid on the workpiece W, reducing the likelihood of variations in image quality on the workpiece W. Furthermore, |(B1+B2-LC) / LC| = 0.18 or 0, both of which satisfy the above formulas 3 and 4. Therefore, when multiple ink head rows including ink heads that eject ink of the same color are mounted on the carriage 3, it is possible to prevent not only the large variation in the time from when the pretreatment liquid lands to when the first ink lands for a given color of ink, but also the large variation in the time from when the second ink lands to when the posttreatment liquid lands.

[0124] Furthermore, the pre-processing head 5 and post-processing head 6 are not only arranged in the central region HC of the arrangement width H, but are also arranged so that the arrangement center of the pre-processing head 5 coincides with the arrangement center of the first and second post-processing heads 6A and 6B in the main scanning direction S. In this embodiment, there is only one pre-processing head 5, so the center of the pre-processing head 5 in the main scanning direction S is the arrangement center C1. For the post-processing head 6, the midpoint between the first post-processing head 6A and the second post-processing head 6B is the arrangement center C2. The pre-processing head 5 and post-processing head 6 are arranged on the head support frame 31 so that the arrangement center C1 and the arrangement center C2 are in the same position in the main scanning direction S.

[0125] 4, in this embodiment, the carriage 3 repeats forward main scanning and backward main scanning to sequentially deposit pre-treatment liquid, ink, and post-treatment liquid on the workpiece W. When such bidirectional main scanning is employed, by employing the head arrangement of Example 5, it is possible to particularly reduce the variation in the time from when the pre-treatment liquid lands on the workpiece W until the ink lands, and the variation in the time from when the ink lands on the workpiece W, at each main scanning position.

[0126] In this case, the central region HC is preferably a region located in the center of the range of the arrangement width H, with a width that is half the arrangement width H, and more preferably one-third of the arrangement width H. "Processing heads are arranged in the central region HC" means that the centers of the arrangement of the processing heads are arranged in the central region HC, and that more than half of the arrangement centers of the processing heads are arranged in the central region HC. Furthermore, all of the arrangement centers of the processing heads may be arranged in the central region HC.

[0127] Example 6 In Example 6 and the following Example 7, head arrangements are exemplified in which measures are taken to prevent heat generation in the treatment heads 5 and 6. Generally, heads that eject liquid using a jet method generate heat because they use electricity to pressurize the liquid. The ink head 4 performs an ejection operation only when forming the required color dots. In contrast, the pre-treatment head 5 and post-treatment head 6 are required to eject pre-treatment liquid and post-treatment liquid corresponding to dots of all colors. Therefore, the pre-treatment head 5 and post-treatment head 6 are more likely to become hotter than the ink head 4. For this reason, it is desirable to perform a head arrangement that takes into account the possibility of the pre-treatment head 5 and post-treatment head 6 becoming hotter.

[0128] FIG. 12 is a plan view schematically showing a carriage 3F equipped with a head arrangement according to Example 6. The carriage 3F is supported by a back frame 32 (engagement portion) in a cantilevered state on a guide rail 17 (supporting member) (FIG. 1). The head support frame 31 is equipped with an ink head 4 equipped with first to sixth ink heads 4A to 4F, one pre-processing head 5, and a post-processing head 6 equipped with first and second post-processing heads 6A and 6B. The head arrangement is the same as that of Example 1 shown in FIG. 6, so a description thereof will be omitted here.

[0129] In this head arrangement in Example 6, LC=11, B1=6, and B2=5, 7. In this case, |(B1-LC / 2)| / LC=0.045, which satisfies the above formula 1. Also, |(B2-LC / 2)| / LC=0.045 or 0.136, which both satisfy the above formula 2. Also, |(B1+B2-LC) / LC|=0 or 0.18, which both satisfy the above formulas 3 and 4.

[0130] In this embodiment, the pre-processing head 5 is made up of one unit head, and the post-processing head 6 is made up of two unit heads (first and second post-processing heads 6A and 6B). Of these pre-processing heads 5 and post-processing heads 6, the pre-processing head 5 having the fewest number of unit heads is arranged on the base end side 311 of the head support frame 31. The post-processing head 6 having the most number of unit heads is arranged on the tip end side 312. In other words, the upstream edge of the head support frame 31 in the transport direction F is the side that is held by the guide rail 17.

[0131] As described above, the processing heads 5 and 6 generate heat during the ejection operation. As shown schematically in FIG. 12, the pre-processing head 5, which has reached a high temperature, dissipates heat ha. The same is true for the first and second post-processing heads 6A and 6B. This heat ha warms the head support frame 31 of the carriage 3F, which can cause thermal deformation of the head support frame 31 and its supporting structure, the back frame 32, and the metal fittings connecting the back frame 32 to the timing belt 16. This thermal deformation can affect the landing accuracy of ink ejected from the ink head 4 on the carriage 3F, which is supported in a cantilevered manner.

[0132] However, in the carriage 3F of Example 6, the pre-processing head 5, which has a smaller number of unit heads, is arranged on the base end side 311, which is the side that is cantilevered by the head support frame 31. This makes it possible to reduce the effects of thermal deformation (deterioration of landing accuracy). If the post-processing head 6, which has a larger number of unit heads, were arranged on the base end side 311, the back frame 32 would receive heat ha from the two unit heads, become even hotter, and be more susceptible to thermal deformation.

[0133] Furthermore, in the carriage 3F of Example 6, the pre-processing head 5 is arranged at a position excluding the end in the main scanning direction S of the head array HA (head arrangement area) of the ink head 4 and processing heads 5 and 6. Of the heads 4, 5, and 6 mounted on the carriage 3F, the pre-processing head 5, which is the processing head, is the head arranged closest to the back frame 32 (engagement portion). Such a pre-processing head 5 is arranged at a position excluding the arrangement end 313, which is the end of the head array HA.

[0134] Because the carriage 3F cannot be made unnecessarily large, if a head were placed at the arrangement edge 313 of the head array in the main scanning direction S, that head would be closest to the corner of the carriage 3F (head support frame 31) in the main scanning direction S. Because the area near the arrangement edge 313 is also close to the cantilevered back frame 32, thermal deformation in that area can induce distortion or misalignment of the head support frame 31 in the vertical and horizontal directions. This reduces the landing position accuracy of the heads 4, 5, and 6 mounted on the carriage 3F. Therefore, by not placing the processing heads (pre-processing head 5 and post-processing head 6), which become hot, in the area of ​​the arrangement edge 313, the above-mentioned thermal deformation problem can be made less likely to occur.

[0135] In this embodiment, of the two rows of ink heads 4 (first ink head row 41, second ink head row 42), the row of heads 4 located on the engagement portion side is arranged in a staggered position shifted to the right in Figure 12. Furthermore, a pre-treatment head 5, which is a processing head with a smaller number of heads, is arranged on the engagement portion side, and the pre-treatment head 5 is arranged in the center of the staggered arrangement. By arranging the heads in this manner, it is possible to arrange the heads so that the processing heads are not arranged at the arrangement edge 313.

[0136] A preferred ink head arrangement example will be further described with reference to the head arrangement of the carriage 3F shown in Figure 12. On the carriage 3F, the pre-treatment head 5, which becomes hot, is arranged so that a portion thereof is adjacent to the ink head 4. Specifically, the pre-treatment head 5 is adjacent to the upstream heads 4C1 and 4D1 of the third and fourth ink heads 4C and 4D in the main scanning direction S, and adjacent to the downstream head 4D2 of the fourth ink head 4D in the transport direction F. Furthermore, the first post-treatment head 6A is adjacent to the downstream heads 4C2 and 4D2 of the third and fourth ink heads 4C and 4D in the main scanning direction S, and adjacent to the upstream head 4C1 in the transport direction F. The second post-treatment head 6B is adjacent to the downstream heads 4D2 and 4E2 of the fourth and fifth ink heads 4D and 4E in the main scanning direction S, and adjacent to the upstream head 4D1 in the transport direction F. On the other hand, the pre-treatment head 5 and the post-treatment head 6 are not adjacent to the first, second and sixth ink heads 4A, 4B and 4F.

[0137] In the above head arrangement, for example, the third, fourth, and fifth ink heads 4C, 4D, and 4E (first ink heads that eject ink of the first color), which eject yellow, red, and blue ink, respectively, have a greater number of unit heads adjacent to the pre-treatment head 5 and post-treatment head 6 than the first, second, and sixth ink heads 4A, 4B, and 4F (second ink heads that eject ink of the second color), which eject orange, green, and black ink, respectively. In other words, the third, fourth, and fifth ink heads 4C, 4D, and 4E are ink heads that are more likely to reach high temperatures than the other ink heads 4A, 4B, and 4F.

[0138] When the viscosity of ink changes significantly with temperature, the ink ejection characteristics (e.g., ejection volume) from the ink heads also change. Temperature-dependent viscosity change characteristics differ depending on the type of ink. Therefore, in this embodiment, the ink ejected from the third, fourth, and fifth ink heads 4C, 4D, and 4E, which are prone to high temperatures, has a smaller viscosity change with temperature than the ink ejected from the first, second, and sixth ink heads 4A, 4B, and 4F. This minimizes temperature-dependent changes in the ejection volume and ejection speed of the ink ejected from the third, fourth, and fifth ink heads 4C, 4D, and 4E, even if they are heated by the pre-processing head 5 and post-processing head 6.

[0139] In this case, the number of unit heads of processing heads adjacent to an ink head 4 for each ink may be evaluated based on the maximum number of unit heads of adjacent processing heads among the ink heads 4 that eject a certain ink. For the first, second, and sixth ink heads 4A, 4B, and 4F, the maximum number of unit heads of adjacent processing heads is 0. For the third ink head 4C, the maximum number of unit heads of adjacent processing heads is 2, and for the fourth ink head 4D, the maximum number of unit heads of adjacent processing heads is 3. For the fifth ink head 4E, the maximum number of unit heads of adjacent processing heads is 1.

[0140] Furthermore, the number of unit heads of processing heads adjacent to an ink head 4 for each ink may be evaluated as the average number of unit heads of adjacent processing heads among the ink heads 4 that eject a certain ink. For the first, second, and sixth ink heads 4A, 4B, and 4F, the average number of unit heads of adjacent processing heads is 0. For the third ink head 4C, the average number of unit heads of adjacent processing heads is 1.5, and for the fourth ink head 4D, the average number of unit heads of adjacent processing heads is 2.5. For the fifth ink head 4E, the average number of unit heads of adjacent processing heads is 0.

[0141] As an evaluation combining these, for example, evaluation may first be made based on the maximum number of unit heads of adjacent processing heads, and for inks for which there is no difference in the evaluation, evaluation may be made based on the average number of unit heads of adjacent processing heads.

[0142] Alternatively, the ink heads 4 ejecting each ink may be evaluated in order of how easily they can be heated, and inks with less change in viscosity with temperature may be ejected in order of how easily they can be heated.

[0143] Example 7 Example 7 shows an example in which measures to prevent high temperatures of the pre-treatment head 5 and post-treatment head 6 between multiple ink heads of the same color that eject ink of the same color are taken into consideration. In the above-mentioned examples, the first to sixth ink heads 4A to 4F of each color each include two or three unit heads. If there is a large difference in the number of unit heads adjacent to the pre-treatment head 5 or post-treatment head 6 between these unit heads, a problem occurs in which the ink ejection characteristics differ greatly between the unit heads. In this example, an example of a head arrangement that reduces the difference in the number of adjacent heads is shown.

[0144] 13 is a plan view showing a carriage 3G having a head arrangement according to Example 7. The carriage 3G has a head arrangement in which, when the number of two unit heads (same-color ink heads) included in each of the first to sixth ink heads 4A to 4F that are adjacent to the pre-processing head 5 or the post-processing head 6 in the main scanning direction S and the transport direction F is counted, the difference between the maximum and minimum counts is 1 or less.

[0145] The head arrangement of the ink heads 4 on carriage 3G is the same as that of carriage 3F shown in Figure 12. On the other hand, the pre-processing head 5 includes first and second pre-processing heads 5A and 5B arranged side by side in the main scanning direction S, with the upstream head 4C1 of the third ink head 4C in between. The post-processing head 6 includes first and second post-processing heads 6A and 6B arranged side by side in the main scanning direction S, with the downstream head 4C2 in between.

[0146] In the head arrangement of Example 7, the head downstream of the first ink head 4A is considered as the end-side head, and the aforementioned LC=11, B1=4, 6, and B2=3, 5 are satisfied. In this case, |(B1-LC / 2)| / LC=0.136, 0.045, which satisfies the above-mentioned formula 1. Also, |(B2-LC / 2)| / LC=0.227 or 0.045, which satisfies the above-mentioned formula 2. Therefore, it is possible to reduce the time variability between the impact of the pretreatment liquid and the impact of the ink ejected from the first ink head row 41, and the time variability between the impact of the ink ejected from the second ink head row 42 and the impact of the posttreatment liquid. As a result, it is possible to stably and sequentially impact the pretreatment liquid, ink, and posttreatment liquid on the workpiece W, reducing the occurrence of variations in image quality on the workpiece W. Note that when B1=4, |(B1+B2-LC) / LC|=0.364 or 0.181, and one of them does not satisfy the above formula 3 or 4, but the other does. Also, when B1=6, |(B1+B2-LC) / LC|=0.181 or 0, and both satisfy the above formula 3 and 4. Therefore, when a plurality of ink head rows including ink heads that eject ink of the same color are mounted on the carriage 3, it is possible to prevent not only a large variation in the time from the landing of the pre-treatment liquid to the landing of the first ink for a given color of ink, but also a large variation in the time from the landing of the second ink to the landing of the post-treatment liquid.

[0147] For the second ink head 4B of the carriage 3G, the counts of the processing heads 5 and 6 adjacent to the upstream head 4B1 and downstream head 4B2 in the main scanning direction S and transport direction F are 2 and 1, respectively, with a difference of 1. For the third ink head 4C, the counts of the upstream head 4C1 and downstream head 4C2 are both 3, with a difference of 0. For the fourth ink head 4D, the count of the upstream head 4D1 is 1, and the count of the downstream head 4D2 is 2, with a difference of 1. The remaining ink heads 4A, 4E, and 4F all have a count of 0. Therefore, the difference between the maximum and minimum values ​​for all of the first through sixth ink heads 4A through 4F is 1 or less, satisfying the above requirement.

[0148] As described above, in Example 7, the difference between the maximum and minimum counts of the upstream heads 4A1 to 4F1 and the downstream heads 4A2 to 4F2 of the first to sixth ink heads 4A to 4F adjacent to the processing heads 5 and 6 is set to 1 or less. This prevents large differences in ink ejection volume between multiple ink heads of the same color.

[0149] Example 8 14 is a plan view that schematically shows a carriage 3H that includes a head arrangement according to Example 8. Example 8 shows an example in which the pre-treatment head 5 and the post-treatment head 6 are arranged in a massed manner as much as possible, rather than being arranged in a dispersed manner on the head support frame 31, thereby reducing contact between the pre-treatment liquid and the post-treatment liquid and the ink.

[0150] In Example 8, a head arrangement that satisfies the following requirements (A) to (C) is exemplified. (A) When the number of unit heads of the pre-processing heads 5 and the post-processing heads 6, whichever is larger, is m and whichever is smaller, is n, the requirement m = n + odd number is satisfied; (B) the center of arrangement or alignment of one or more pre-treatment heads 5 and the center of arrangement or alignment of one or more post-treatment heads 6 in the main scanning direction S coincide with each other in the main scanning direction S, and (C) The center of arrangement or alignment of the pre-treatment head 5 and the post-treatment head 6 and the position of one of the ink heads 4 coincide with each other in the main scanning direction S.

[0151] The carriage 3H shown in FIG. 8 is equipped with an ink head 4, one pre-processing head 5, and a post-processing head 6 having first and second post-processing heads 6A and 6B. The head arrangement is the same as in FIG. 12 and other figures. Therefore, the head arrangement in Example 8 also satisfies the relationships of Equations 1 to 4 described above and can achieve similar effects. In this example, there are m=2 post-processing heads 6 and n=1 pre-processing head 5. Therefore, the m=n+odd number requirement (A) is met. The centers of the pre-processing head 5 and the post-processing head 6 are both center C in the figure, which also satisfies requirement (B). Furthermore, center C coincides with the position of the head 4D2 downstream of the fourth ink head 4D, which also satisfies requirement (C).

[0152] According to the head arrangement of Example 8, the pre-treatment head 5 and the post-treatment head 6 can be mounted on the carriage 3H in a relatively compact state. This makes it possible to reduce the number of ink heads, out of the first to sixth ink heads 4A to 4F, that are arranged in positions close to the pre-treatment head 5 or the post-treatment head 6. This reduces the possibility of contact between the pre-treatment liquid and the post-treatment liquid and the ink on the carriage.

[0153] Example 9 In Example 9, a preferred arrangement relationship between the heads 4, 5, and 6 on the carriage and the sub-tanks that supply ink or treatment liquid to them is illustrated. FIG. 15 is a plan view showing a carriage 3I equipped with a head arrangement according to Example 9 and the sub-tank arrangement. The carriage 3I is equipped with an ink head 4 having first to sixth ink heads 4A to 4F, one pre-treatment head 5, and a post-treatment head 6 having first and second post-treatment heads 6A and 6B. The arrangement of these heads is the same as in FIG. 12 and others. Therefore, the head arrangement in Example 9 also satisfies the relationships of the above-mentioned formulas 1 to 4, and can achieve similar effects.

[0154] The carriage 3I is also equipped with subtanks 7. The subtanks 7 include ink subtanks 7A to 7F, a pre-treatment liquid subtank 71, and a post-treatment liquid subtank 72 (all of which are treatment liquid subtanks). These subtanks 7 are supplied with ink, pre-treatment liquid, and post-treatment liquid, respectively, from a main tank (not shown). The ink subtanks 7A to 7F supply the ink to the first to sixth ink heads 4A to 4F, respectively. For example, the first color ink is supplied to the upstream head 4A1 of the first ink head 4A from the first tank 7A1 of the ink subtank 7A, and the downstream head 4A2 is supplied with ink from the second tank 7A2 via a pipe P1. The second to sixth colors of ink are similarly supplied to the second to sixth ink heads 4B to 4F, respectively.

[0155] The arrangement order of the ink subtanks 7 in the main scanning direction S is the same as the arrangement order in the main scanning direction S of the ink heads 4 to which each ink subtank 7 supplies ink. Note that ink may be supplied from a single ink subtank 7 to multiple ink heads 4 that eject ink of the same color. In that case, the ink heads 4 that share the same ink subtank 7 may be arranged in a grouped position in the main scanning direction S. Furthermore, it is preferable to arrange the ink heads 4 that eject the same ink together in the main scanning direction S, and the arrangement order of the ink subtanks 7 of each color in the main scanning direction S may be the same as the arrangement order of the ink heads 4 of each color.

[0156] The pre-processing liquid sub-tank 71 supplies the pre-processing liquid to the pre-processing head 5 via a pipe P2. The post-processing liquid sub-tank 72 includes a first tank 72A and a second tank 72B. The first and second tanks 72A and 72B supply the post-processing liquid to the first and second post-processing heads 6A and 6B, respectively, via a pipe P3.

[0157] The ink subtanks 7A to 7F are mounted on the carriage 3I so as to be aligned in the main scanning direction S. The treatment liquid subtanks 71 and 72 are disposed at positions different from the ink subtanks 7A to 7F in the transport direction F. The treatment liquid subtanks 71 and 72 are also disposed aligned in the main scanning direction S. Specifically, the pre-treatment liquid subtank 71 and the first and second tanks 72A and 72B of the post-treatment liquid subtank 72 are aligned in a row in the main scanning direction S, downstream of the ink subtanks 7A to 7F in the transport direction F. It is also possible to arrange only the pre-treatment liquid subtank 71 upstream of the ink subtanks 7A to 7F.

[0158] The liquid in the sub-tank 7, which is mounted on the carriage 3I that moves back and forth in the main scanning direction S, is subjected to acceleration in that main scanning direction S. The sub-tank 7 and each of the heads 4, 5, and 6 are connected by conduits P1, P2, and P3, but if the sub-tanks 7 are widely distributed on the carriage 3I, the arrangement range of the conduits P1 to P3 in the main scanning direction S also becomes large. Because these conduits P1 to P3 are also filled with ink or treatment liquid, the influence of the acceleration can cause meniscus destruction in the ejection portions of the heads 4, 5, and 6.

[0159] However, according to the configuration of the ninth embodiment, the ink sub-tanks 7A to 7F are mounted on the carriage 3I so as to be aligned in the main scanning direction S, similar to the first to sixth ink heads 4A to 4F. This makes it possible to arrange the ink sub-tanks 7A to 7F in a relatively narrow area on the head support frame 31 of the carriage 3I. Similarly, the pre-treatment liquid sub-tank 71 and the post-treatment liquid sub-tank 72 can also be arranged in a relatively narrow area on the head support frame 31 of the carriage 3I.

[0160] Furthermore, because the pre-treatment liquid sub-tank 71 and the post-treatment liquid sub-tank 72 are disposed at positions separate from the ink sub-tanks 7A to 7F in the transport direction F, the difference in position in the main scanning direction S between the pre-treatment liquid sub-tank 71 and the post-treatment liquid sub-tank 72 and the processing heads to which the pre-treatment liquid sub-tank 71 and the post-treatment liquid sub-tank 72 supply processing liquid can be reduced. This reduces the distribution range in the main scanning direction S of the pre-treatment liquid that is connected to the pre-treatment liquid sub-tank 71, the conduit P, and the pre-processing head 5, making it less susceptible to the effects of the acceleration. Similarly, the distribution range in the main scanning direction S of the connected post-processing liquid can be reduced, making it less susceptible to the effects of the acceleration.

[0161] Similarly, the ink subtanks 7A to 7F and the ink heads 4 to which the ink subtanks 7A to 7F supply ink can be positioned with little difference in position in the main scanning direction S. This reduces the distribution range of connected ink in the main scanning direction S, making it less susceptible to the effects of the acceleration.

[0162] Example 10 Furthermore, Figure 16 is a plan view of a carriage 3J showing the head arrangement according to Example 10. In Example 10, the ink heads 4 also have a first ink head row 41 and a second ink head row 42. In this example, the post-treatment head 6 is located approximately in the center of the array of all heads in the main scanning direction S, while the pre-treatment head 5 is located at one end of the array (the left end in Figure 16). In this case, the head downstream of the first ink head 4A and the pre-treatment head 5 correspond to the heads on the one end side.

[0163] In this head arrangement, LC=11, B1=0, and B2=5. In this case, |(B1-LC / 2)| / LC=0.5, which does not satisfy the above formula 1. On the other hand, |(B2-LC / 2)| / LC=0.045, which satisfies the above formula 2. This head arrangement is suitable when, in terms of the function of the pre-treatment liquid, there is a tolerance for the required variation in the time from the impact of the pre-treatment liquid to the impact of the ink ejected from the first ink head row 41, while the variation in the time from the impact of the ink ejected from the second ink head row 42 to the impact of the post-treatment liquid must be minimized.

[0164] Example 11 Furthermore, Figure 17 is a plan view of a carriage 3K showing the head arrangement according to Example 11. In Example 11, the ink heads 4 also have a first ink head row 41 and a second ink head row 42. In this example, the post-treatment head 6 is located approximately in the center of the array of all heads in the main scanning direction S, while the pre-treatment head 5 is located at the other end of the array (the right end in Figure 17). In this case, the head downstream of the first ink head 4A corresponds to the one-end head.

[0165] In this head arrangement, LC=11, B1=10, and B2=5. In this case, |(B1-LC / 2)| / LC=0.409, which does not satisfy the above formula 1. On the other hand, |(B2-LC / 2)| / LC=0.045, which satisfies the above formula 2. As with Example 10, this head arrangement is also suitable when, due to the function of the pretreatment liquid, there is a tolerance in the required variation in the time from the impact of the pretreatment liquid to the impact of the ink ejected from the first ink head row 41, but when the variation in the time from the impact of the ink ejected from the second ink head row 42 to the impact of the posttreatment liquid must be minimized.

[0166] Contrary to the above-described Examples 10 and 11, the arrangement of the pre-treatment head 5 may satisfy formula 1, while the arrangement of the post-treatment head 6 may not satisfy formula 2. In this case, due to the function of the post-treatment liquid, there is a tolerance in the required variation in the time from the impact of the ink ejected by the second ink head row 42 to the impact of the post-treatment liquid, but this is suitable for cases where the variation in the time from the impact of the pre-treatment liquid to the impact of the ink ejected by the first ink head row 41 must be reduced.

[0167] <Inkjet recording method> As described above, the inkjet printer 1 described in each embodiment has one ink head row mounted on the carriage 3 at a predetermined position in the transport direction F, or multiple ink head rows mounted on the carriage 3 so as to be aligned in the transport direction F, a pre-treatment head, and a post-treatment head. Each of the one or more ink head rows includes multiple ink heads that are aligned in the main scanning direction S and each ejects ink for image formation. The pre-treatment head 5 is positioned upstream of the one or more ink head rows in the transport direction F, and ejects a non-color-forming pre-treatment liquid. The post-treatment head 6 is positioned downstream of the one or more ink head rows in the transport direction F, and ejects a non-color-forming post-treatment liquid.

[0168] One inkjet recording method for the inkjet printer 1 described above includes the steps of: arranging the pre-processing head 5 so as to satisfy the relationship |(B1-LC / 2)| / LC≦1 / 4 (Equation 1), where, of the multiple ink heads 4 and processing heads (pre-processing head 5 and post-processing head 6), the head located closest to one end in the main scanning direction S is referred to as the one-end head, and the head located closest to the other end is referred to as the other-end head; the distance in the main scanning direction S from the one-end head to the other-end head is referred to as LC; and the distance in the main scanning direction S from the one-end head to the pre-processing head 5 is referred to as B1; ejecting pre-processing liquid from the pre-processing head 5 onto a predetermined recording area on the workpiece W while moving the carriage 3 in the main scanning direction S; and feeding the workpiece W in the transport direction F at a predetermined feed pitch, and ejecting ink from the ink head 4 onto the recording area that has received the ejected pre-processing liquid while moving the carriage 3 in the main scanning direction S.

[0169] According to this method, an image can be efficiently formed on the workpiece W using an inkjet printer 1 in which heads for ejecting the pretreatment liquid and ink are mounted on a single carriage 3. Furthermore, because the pretreatment head 5 and ink head 4 are sequentially arranged in the transport direction F, the pretreatment liquid and ink can be ejected in a desired landing order on the recording medium. Furthermore, by appropriately positioning the pretreatment head 5 to satisfy formula 1, it is possible to reduce the variation in the time from when the pretreatment liquid lands until when the ink lands. As a result, variation in image quality on the workpiece W is less likely to occur.

[0170] In the above-described method, the processing head mounted on the carriage 3 may be only the pre-processing head 5. In addition, in the above-described method, recording may be completed without applying the post-processing liquid, or the post-processing liquid may be applied after printing by the carriage 3 is completed. In the latter case, the post-processing liquid is applied to substantially the entire surface of the workpiece W, for example, by spraying, transferring with a roller, or immersing in the post-processing liquid.

[0171] Furthermore, another inkjet recording method for the inkjet printer 1 described above includes positioning a post-processing head 6 so as to satisfy the relationship |(B2-LC / 2)| / LC≦1 / 4 (Equation 2), ejecting ink from an ink head 4 onto a predetermined recording area of ​​the workpiece W while moving a carriage 3 in a main scanning direction S, and feeding the workpiece W in a transport direction F at the feed pitch, and ejecting post-processing liquid from the post-processing head 6 onto the recording area that has received the ejected ink while moving the carriage 3 in the main scanning direction S.

[0172] Even with this method, an image can be efficiently formed on the workpiece W using an inkjet printer 1 in which heads for ejecting ink and post-treatment liquid are mounted on a single carriage. Furthermore, because the ink head 4 and post-treatment head 6 are sequentially arranged in the transport direction, the ink and post-treatment liquid can be ejected in a desired landing order on the workpiece W. Furthermore, by appropriately positioning the post-treatment head 6 to satisfy formula 2, it is possible to reduce the variation in the time between the landing of the ink and the landing of the post-treatment liquid. As a result, variations in image quality on the workpiece W are less likely to occur.

[0173] In the above-described method, the processing head mounted on the carriage 3 may be only the post-processing head 6. In the above-described method, recording may be completed without applying the pre-processing liquid, or the pre-processing liquid may be applied before printing by the carriage 3. In the latter case, the pre-processing liquid is applied to substantially the entire surface of the workpiece W, for example, by spraying, transferring with a roller, or immersing in the pre-processing liquid.

[0174] Furthermore, another inkjet recording method for the inkjet printer 1 described above includes arranging a pretreatment head 5 and a posttreatment head 6 on a carriage 3 so as to satisfy Equations 1 and 2; ejecting a pretreatment liquid from the pretreatment head 5 onto a predetermined recording area on the workpiece W while moving the carriage 3 in the main scanning direction S; feeding the workpiece W in a transport direction F at a predetermined feed pitch, and ejecting ink from the ink head 4 onto the recording area that has received the ejection of the pretreatment liquid while moving the carriage 3 in the main scanning direction S; ejecting ink from the ink head 4 onto the recording area that has received the ejection of the pretreatment liquid; further feeding the workpiece W in the transport direction F at the feed pitch, and ejecting posttreatment liquid from the posttreatment head 6 onto the recording area that has received the ejection of the ink while moving the carriage 3 in the main scanning direction S.

[0175] According to this method, an all-in-one inkjet printer 1 having three types of heads mounted on a single carriage 3, namely, heads for ejecting pretreatment liquid, ink, and posttreatment liquid, can efficiently form an image on the workpiece W. Furthermore, because the pretreatment head 5, ink head 4, and posttreatment head 6 are sequentially arranged in the transport direction F, the pretreatment liquid, ink, and posttreatment liquid can be ejected in a desired landing order on the recording medium. Furthermore, by appropriately arranging the pretreatment head 5 and posttreatment head 6 to satisfy Equations 1 and 2, it is possible to reduce variations in the time from the landing of the pretreatment liquid to the landing of the ink, and the time from the landing of the ink to the landing of the posttreatment liquid. As a result, variations in image quality on the workpiece W are less likely to occur.

[0176] <Comparative Example> 18 is a plan view of a carriage 3Z1 showing a head arrangement according to Comparative Example 1, which is compared with the present disclosure. In this head arrangement according to Comparative Example 1, LC=13, B1=0, and B2=13. In this case, |(B1-LC / 2)| / LC=0.409, which does not satisfy the above formula 1. Also, |(B2-LC / 2)| / LC=0.682, which does not satisfy the above formula 2.

[0177] 19 is a plan view of carriage 3Z2 showing a head arrangement according to Comparative Example 2, which is compared with the present disclosure. In this head arrangement according to Comparative Example 2, LC=7, B1=0, and B2=7. In this case, |(B1-LC / 2)| / LC=0.5, which does not satisfy Equation 1 above. Also, |(B2-LC / 2)| / LC=0.5, which does not satisfy Equation 2 above.

[0178] In head arrangements such as those in Comparative Examples 1 and 2, there is a large variation in the time from the impact of the pre-treatment liquid to the impact of the ink ejected by the first ink head row 41, and there is also a large variation in the time from the impact of the ink ejected by the second ink head row 42 to the impact of the post-treatment liquid, which makes it more likely that the image formed on the workpiece W will also vary.

[0179] Summary of this disclosure An inkjet recording apparatus according to one aspect of the present disclosure includes a transport unit, a carriage, one or more ink head rows, and a treatment head. The transport unit transports a recording medium in a predetermined transport direction. The carriage reciprocates in a main scanning direction that intersects with the transport direction. The one or more ink head rows are mounted on the carriage at predetermined positions in the transport direction. The treatment head is mounted on the carriage and ejects a non-color-forming treatment liquid. Each of the one or more ink head rows includes a plurality of ink heads that are arranged in line in the main scanning direction and each ejects ink for image formation. The treatment head includes a pretreatment head that is arranged upstream of the one or more ink head rows in the transport direction and ejects a pretreatment liquid that is the treatment liquid. Of the plurality of ink heads and processing heads, the head located closest to one end in the main scanning direction is referred to as the one-end head, and the head located closest to the other end is referred to as the other-end head, and the distance in the main scanning direction from the one-end head to the other-end head is referred to as LC, and the distance in the main scanning direction from the one-end head to the pre-processing head is referred to as B1. The pre-processing heads are arranged to satisfy the relationship in Equation 1: |(B1-LC / 2)| / LC≦1 / 4 (Equation 1)

[0180] This configuration makes it possible to provide an inkjet recording device in which heads for ejecting pretreatment liquid and ink are mounted on a single carriage. Furthermore, because the pretreatment head and ink head are sequentially arranged in the transport direction, the pretreatment liquid and ink can be ejected in a desired landing order on the recording medium. Furthermore, by appropriately arranging the pretreatment head to satisfy formula 1, it is possible to reduce the variation in the time from the landing of the pretreatment liquid to the landing of the ink, regardless of the direction of carriage movement. As a result, by sequentially landing the pretreatment liquid and ink on the recording medium, variation in image quality on the recording medium is less likely to occur.

[0181] In the above configuration, a plurality of the pre-processing heads may be arranged side by side in the main scanning direction, and at least one of the plurality of pre-processing heads may be arranged so as to satisfy the relationship of Equation 1 above.

[0182] According to this configuration, even when multiple pretreatment heads are arranged, it is possible to reduce the variation in the time from the impact of the pretreatment liquid to the impact of the ink by arranging at least one of the pretreatment heads so as to satisfy Formula 1. Furthermore, because the other pretreatment heads can eject more pretreatment liquid, it is possible to increase the amount of treatment liquid that can be ejected.

[0183] In the above configuration, all of the plurality of pre-treatment heads may be arranged so as to satisfy the relationship of formula 1 above.

[0184] According to this configuration, multiple pretreatment heads are arranged so that all of them satisfy formula 1, which further reduces the variation in the time from when the pretreatment liquid lands to when the ink lands, and increases the amount of treatment liquid that can be ejected.

[0185] In the above configuration, the processing head may further include a post-processing head that is arranged downstream of the one or more ink head rows in the transport direction and that ejects a post-ejection liquid, which is the processing liquid, wherein a plurality of the ink head rows are arranged side by side in the transport direction, one of the plurality of ink head rows has one ink head that ejects ink of a predetermined color, and another of the plurality of ink head rows has another ink head that is arranged adjacent to the one ink head and ejects ink of the predetermined color, and where B2 is the distance in the main scanning direction from the one end head to the post-processing head, the pre-processing head and the post-processing head may be arranged to satisfy the following relationship: |(B1+B2-LC) / LC|≦1 / 2

[0186] This configuration makes it possible to provide an all-in-one inkjet recording device in which three types of heads, namely, heads for ejecting pretreatment liquid, ink, and posttreatment liquid, are mounted on a single carriage. Furthermore, because the pretreatment head, ink head, and posttreatment head are sequentially arranged in the transport direction, the pretreatment liquid, ink, and posttreatment liquid can be ejected in a desired landing order on the recording medium. Furthermore, in a configuration in which ink of the same color is ejected from ink heads in multiple ink head rows onto a predetermined ejection target area, it is possible to reduce the variation in the time between the landing of the pretreatment liquid and the landing of the ink ejected by the ink head located upstream in the transport direction, and the variation in the time between the landing of the ink ejected by the ink head located downstream in the transport direction and the landing of the posttreatment liquid.

[0187] an inkjet recording apparatus according to another aspect of the present disclosure, the inkjet recording apparatus comprising: a transport unit that transports a recording medium in a predetermined transport direction; a carriage that reciprocates in a main scanning direction that intersects with the transport direction; one or more ink head rows that are mounted on the carriage at a predetermined position in the transport direction; and a processing head that is mounted on the carriage and ejects a non-color-forming treatment liquid, wherein each of the one or more ink head rows includes a plurality of ink heads that are arranged to be aligned in the main scanning direction and eject inks for image formation, and the processing head comprises a post-treatment head that is arranged downstream of the one or more ink head rows in the transport direction and ejects a post-treatment liquid that is the treatment liquid, wherein a head of the plurality of ink heads and the processing head that is arranged closest to one end in the main scanning direction is referred to as a one-end head, and a head that is arranged closest to the other end is referred to as an other-end head, and the inkjet recording apparatus comprises: |(B2-LC / 2)| / LC≦1 / 4···(Formula 2)

[0188] This configuration makes it possible to provide an inkjet recording device in which heads for ejecting ink and post-treatment liquid are mounted on a single carriage. Furthermore, because the ink head and post-treatment head are arranged sequentially in the transport direction, the ink and post-treatment liquid can be ejected in a desired landing order on the recording medium. Furthermore, by appropriately arranging the post-treatment head to satisfy Equation 2, it is possible to reduce the variation in the time between the ink landing and the post-treatment liquid landing, regardless of the carriage movement direction. As a result, variation in image quality on the recording medium is less likely to occur.

[0189] In the above configuration, a plurality of the post-processing heads may be arranged side by side in the main scanning direction, and at least one of the plurality of post-processing heads may be arranged so as to satisfy the relationship of formula 2 above.

[0190] According to this configuration, even when multiple post-processing heads are arranged, it is possible to reduce the variation in the time from ink impact to post-processing liquid impact by arranging at least one of the post-processing heads so that it satisfies formula 2. Furthermore, because post-processing liquid can be further ejected from other post-processing heads, it is possible to increase the amount of processing liquid that can be ejected.

[0191] In the above configuration, all of the plurality of post-processing heads may be arranged so as to satisfy the relationship of formula 2 above.

[0192] According to this configuration, multiple post-processing heads are arranged so that all of them satisfy Equation 2, which further reduces the variation in the time from when the ink lands to when the post-processing liquid lands, and increases the amount of processing liquid that can be ejected.

[0193] In the above configuration, the processing head may further include a pre-processing head that is arranged upstream of the one or more ink head rows in the transport direction and that ejects a pre-ejection liquid that is the processing liquid, the ink head rows being arranged in a line in the transport direction, one of the ink head rows having one ink head that ejects ink of a predetermined color, and another of the ink head rows having another ink head that is arranged adjacent to the one ink head and that ejects ink of the predetermined color, and the pre-processing head and the post-processing head may be arranged to satisfy the following relationship, where B1 is the distance in the main scanning direction from the one end head to the pre-processing head.

[0194] According to this configuration, in a configuration in which ink of the same color is ejected onto a predetermined ejection target area from ink heads in multiple ink head rows, it is possible to prevent the variation in the time from the impact of the pre-treatment liquid to the impact of the ink ejected by the ink head upstream in the transport direction, and the variation in the time from the impact of the ink ejected by the ink head downstream in the transport direction to the impact of the post-treatment liquid from increasing.

[0195] In the above configuration, the processing head may further include a pre-processing head that is disposed upstream of the one or more ink head rows in the transport direction and that ejects a pre-ejection liquid, which is the processing liquid, and where the distance in the main scanning direction from the one end side head to the pre-processing head is B1, the pre-processing head may be disposed so as to satisfy the following relationship: |(B1-LC / 2)| / LC≦1 / 4

[0196] According to this configuration, by appropriately arranging the pretreatment head so as to satisfy the above formula, it is possible to further reduce the variation in the time from when the pretreatment liquid lands until when the ink lands.

[0197] In the above configuration, the ink head rows may be arranged in a line in the transport direction, one of the ink head rows has one ink head that ejects ink of a predetermined color, and another of the ink head rows has another ink head that is arranged adjacent to the one ink head and ejects ink of the predetermined color, and the pre-treatment head and the post-treatment head may be arranged to satisfy the relationship of the following formula: |(B1+B2-LC) / LC|≦1 / 3

[0198] According to this configuration, in a configuration in which ink of the same color is ejected onto a predetermined ejection target area from ink heads in multiple ink head rows, it is possible to prevent the variation in the time from the impact of the pre-treatment liquid to the impact of the ink ejected by the ink head upstream in the transport direction, and the variation in the time from the impact of the ink ejected by the ink head downstream in the transport direction to the impact of the post-treatment liquid from increasing.

[0199] In the above configuration, the processing head may be arranged within a range of an arrangement width of the plurality of ink heads in the main scanning direction.

[0200] According to this inkjet recording apparatus, even when the processing head is mounted on a carriage, there is no need to increase the width of the carriage in the main scanning direction, and therefore the width of the carriage in the main scanning direction can be reduced.

[0201] In the above configuration, the processing head may be arranged so that a portion of the processing head is located between a pair of ink heads adjacent to each other in the main scanning direction among the plurality of ink heads included in one of the ink head rows.

[0202] This inkjet recording device allows the ink heads and processing heads, which are arranged at different positions in the transport direction (sub-scanning direction), to be densely arranged in the transport direction, thereby reducing the width of the carriage in the transport direction.

[0203] In the above configuration, the processing head is arranged so that a portion of it is adjacent to the ink head in the main scanning direction and the transport direction, the multiple ink heads include multiple same-color ink heads that eject ink of the same color, and when the number of adjacent processing heads in the main scanning direction and the transport direction is counted for each of the same-color ink heads, the difference between the maximum and minimum counts may be 1 or less.

[0204] Generally, heads that eject liquid using a jet method generate heat because they use electricity to pressurize the liquid. In particular, unlike ink heads that only perform ejection operations when forming required color dots, processing heads that must perform ejection operations for all color dots are more likely to become hot. Ink heads adjacent to such processing heads are also more likely to become hot, which could result in differences in ink ejection volume compared to ink heads not adjacent to the processing head. As described above, by setting the difference between the maximum and minimum counts of ink heads of the same color adjacent to the processing head to 1 or less, significant differences in ink ejection volume are less likely to occur between multiple ink heads of the same color.

[0205] In the above configuration, the processing head is arranged so that a portion thereof is adjacent to the ink head in the main scanning direction and the transport direction, and the plurality of ink heads include a first ink head that ejects at least a first color of ink and a second ink head that ejects a second color of ink, and when the number of adjacent processing heads of the first ink head is greater than the number of adjacent processing heads of the second ink head, the first color of ink may be ejected as ink having a smaller change in viscosity with temperature than the second color of ink.

[0206] In this inkjet recording device, the first ink head, which has a larger number of adjacent processing heads, ejects ink with a small change in viscosity due to temperature. Therefore, even if the first ink head is heated by the processing head, the temperature change in the ejection volume and ejection speed of the first color ink can be small.

[0207] In the above configuration, the processing head may be arranged in a central region of the arrangement width of the ink head row in the main scanning direction.

[0208] Alternatively, the processing head may include a pre-processing head that is arranged upstream of the one or more ink head rows in the transport direction and ejects a pre-processing liquid, which is the processing liquid, and a post-processing head that is arranged downstream of the one or more ink head rows in the transport direction and ejects a post-processing liquid, which is the processing liquid, and the pre-processing head and the post-processing head may be arranged such that the center of arrangement or alignment of the one or more pre-processing heads in the main scanning direction coincides with the center of arrangement or alignment of the one or more post-processing heads in the main scanning direction.

[0209] These inkjet recording devices can particularly reduce the variation in the time from when the pre-treatment liquid lands on the recording medium until the ink lands, and the variation in the time from when the ink lands on the recording medium until the post-treatment liquid lands, at each main scanning position.

[0210] In the inkjet recording device described above, when the number of the pre-processing heads and the post-processing heads, whichever is greater, is m and the number of the post-processing heads, whichever is less, is n, the requirement m=n+odd number is satisfied, and the center of arrangement or alignment of the pre-processing heads and the post-processing heads may coincide with the arrangement position of one of the plurality of ink heads in the main scanning direction.

[0211] According to this inkjet recording device, the pre-treatment head and the post-treatment head can be mounted on the carriage in a relatively compact state. This makes it possible to reduce the number of ink heads located close to the treatment head among the multiple ink heads. This reduces the possibility of contact between the pre-treatment liquid and the post-treatment liquid and the ink on the carriage.

[0212] In the inkjet recording device described above, the processing heads may include a pre-processing head that is arranged upstream of the one or more ink head rows in the transport direction and ejects a pre-processing liquid that is the processing liquid, and a post-processing head that is arranged downstream of the one or more ink head rows in the transport direction and ejects a post-processing liquid that is the processing liquid, and the inkjet recording device may further include a holding member that holds the carriage in a state that allows it to move back and forth in the main scanning direction, the carriage including an engagement portion that is held by the holding member in a cantilevered state, and the pre-processing head may be arranged on the side of the engagement portion relative to the post-processing head in the transport direction.

[0213] According to this inkjet recording device, the carriage can be supported with a simple structure by cantilevering it on a holding member. Furthermore, cantilevering makes it easy to open one side of the carriage, facilitating maintenance of the ink head and processing head. When the carriage is cantilevered, it is expected that the height accuracy will decrease on the side of the carriage farther from the engagement portion. However, since the post-processing head, which has a relatively high tolerance for ejection accuracy, is mounted on the side farther from the engagement portion, this is unlikely to have a significant impact on image quality.

[0214] In the inkjet recording device described above, the processing heads may include a pre-processing head that ejects a pre-processing liquid, which is the processing liquid, and is arranged upstream of the one or more rows of ink heads in the transport direction, and a post-processing head that ejects a post-processing liquid, which is the processing liquid, and is arranged downstream of the one or more rows of ink heads in the transport direction, and the inkjet recording device may further include a holding member that holds the carriage in a state that allows it to move back and forth in the main scanning direction, the carriage including an engagement portion that is held in a cantilevered state by the engagement portion on the holding member, and the pre-processing head or the post-processing head having the fewer heads may be arranged on the engagement portion side of the carriage.

[0215] As described above, the processing head generates heat during the ejection operation. This heats up the carriage carrying the processing head, potentially causing thermal deformation of the carriage and its supporting structure. In a configuration in which the carriage is supported by a cantilever, this thermal deformation can affect the accuracy of ink droplet placement. The above configuration reduces the number of processing heads arranged on the base end side, thereby minimizing the impact of thermal deformation.

[0216] The inkjet recording device may further include a holding member that holds the carriage in a state that allows it to move back and forth in the main scanning direction, the carriage including an engagement portion that is held in a cantilevered state on the holding member by the engagement portion, and in a head array of the ink head and the processing head, the head that is arranged on the side closest to the engagement portion of the carriage is the processing head, and the processing head may be arranged at a position on the head array excluding the end in the main scanning direction.

[0217] According to this inkjet recording device, the head arranged closest to the engaging portion in the head array (head arrangement area) is the processing head, and this processing head is not arranged at the end of the head array in the main scanning direction. Generally, the end in the main scanning direction is closest to the end (corner) of the carriage. If thermal deformation occurs at the end of the carriage near the base end, the positional accuracy of the head mounted on the carriage will decrease. The above configuration makes it less likely that such problems will occur.

[0218] The inkjet recording device may further include a plurality of ink sub-tanks that supply the ink to each of the plurality of ink heads, and a processing liquid sub-tank that supplies the processing liquid to the processing head, wherein the plurality of ink sub-tanks are mounted on the carriage so as to be aligned in the main scanning direction, and the processing liquid sub-tank is mounted on the carriage at a position different from the plurality of ink sub-tanks in the transport direction.

[0219] According to the above configuration, the ink subtank and the processing head subtank are positioned at different positions in the transport direction, allowing the subtanks to be positioned within a relatively narrow area on the carriage. Furthermore, acceleration in the main scanning direction acts on the liquid in the subtank mounted on the carriage, which moves back and forth in the main scanning direction. The subtank and the head are connected by a predetermined conduit. However, if the subtanks are widely distributed on the carriage, the conduit arrangement range in the main scanning direction also becomes large, increasing the effect of the acceleration, which may cause meniscus destruction at the ejection portion of the head. According to the above configuration, the conduit arrangement range in the main scanning direction can be relatively narrowed.

[0220] Also, an inkjet recording method according to another aspect of the present disclosure is an inkjet recording method for an inkjet recording apparatus including: a transport unit that transports a recording medium in a predetermined transport direction; a carriage that reciprocates in a main scanning direction that intersects with the transport direction; one or more ink head rows that are mounted on the carriage at a predetermined position in the transport direction; and a treatment head that is mounted on the carriage and ejects a non-color-forming treatment liquid, wherein each of the one or more ink head rows includes a plurality of ink heads that are arranged to be aligned in the main scanning direction and each eject an ink for forming an image, and the treatment head includes a pretreatment head that is arranged upstream of the one or more ink head rows in the transport direction and ejects a pretreatment liquid that is the treatment liquid, Among the processing heads, the head located closest to one end in the main scanning direction is referred to as the one-end head, and the head located closest to the other end is referred to as the other-end head, and the distance in the main scanning direction from the one-end head to the other-end head is referred to as LC, and the distance in the main scanning direction from the one-end head to the pre-processing head is referred to as B1. The pre-processing head is disposed to satisfy the relationship |(B1-LC / 2)| / LC≦1 / 4 (Formula 1); the pre-processing liquid is ejected from the pre-processing head onto a predetermined recording area on the recording medium while moving the carriage in the main scanning direction; and the recording medium is fed in the transport direction, and the ink is ejected from the ink head onto the recording area that has received the ejection of the pre-processing liquid while moving the carriage in the main scanning direction.

[0221] According to this method, an inkjet recording device in which heads for ejecting pretreatment liquid and ink are mounted on a single carriage can efficiently form images on a recording medium. In particular, because the pretreatment head and ink head are sequentially arranged in the transport direction, the pretreatment liquid and ink can be ejected in a desired landing order on the recording medium. Furthermore, by appropriately arranging the pretreatment head to satisfy formula 1, it is possible to reduce the variation in the time from the landing of the pretreatment liquid to the landing of the ink, regardless of the direction of carriage movement. As a result, variation in image quality on the recording medium is less likely to occur.

[0222] Furthermore, an inkjet recording method according to another aspect of the present disclosure is an inkjet recording method for an inkjet recording apparatus including: a transport unit that transports a recording medium in a predetermined transport direction; a carriage that moves back and forth in a main scanning direction that intersects with the transport direction; one or more ink head rows that are mounted on the carriage at a predetermined position in the transport direction; and a treatment head that is mounted on the carriage and ejects a non-color-forming treatment liquid, wherein each of the one or more ink head rows includes a plurality of ink heads that are arranged to be aligned in the main scanning direction and each eject an ink for forming an image, and the treatment head includes a post-treatment head that is arranged downstream of the one or more ink head rows in the transport direction and ejects a post-treatment liquid that is the treatment liquid, the head of the processing heads arranged at the furthest one end in the main scanning direction is referred to as a one-end head, and the head arranged at the furthest other end is referred to as an other-end head, and the distance in the main scanning direction from the one-end head to the other-end head is referred to as LC, and the distance in the main scanning direction from the one-end head to the post-processing head is referred to as B2, the post-processing head is arranged to satisfy the relationship |(B2-LC / 2)| / LC≦1 / 4 (Formula 2); the ink is ejected from the ink head onto a predetermined recording area on the recording medium while moving the carriage in the main scanning direction; and the recording medium is further fed in the transport direction, and the post-processing liquid is ejected from the post-processing head onto the recording area that has received the ejection of the ink while moving the carriage in the main scanning direction.

[0223] According to this method, an inkjet recording device in which ink and post-treatment liquid ejection heads are mounted on a single carriage can efficiently form images on a recording medium. In particular, because the ink heads and post-treatment heads are sequentially arranged in the transport direction, the ink and post-treatment liquid can be ejected in a desired landing order on the recording medium. Furthermore, by appropriately arranging the post-treatment head to satisfy Equation 2, it is possible to reduce the variation in the time from ink landing to post-treatment liquid landing, regardless of the carriage movement direction. As a result, variation in image quality on the recording medium is less likely to occur.

[0224] According to the present disclosure, it is possible to provide an inkjet recording apparatus and an inkjet recording method that include a carriage that is mounted with an ink head and a processing head and moves in the main scanning direction, and that can reduce the time variance between the landing of ink and the landing of processing liquid. [Explanation of symbols]

[0225] 1. Inkjet printer (ink head recording device) 16 Timing belt (moving part) 17 Guide rail (holding member) 20 Work transport unit (transport unit) 3, 3A~3J carriage 31 Head support frame 32 Back frame (engagement part) 4 ink heads 41 First ink head row (ink head row) 42 Second ink head row (ink head row) 43 Third ink head row (ink head row) 4A~4F 1st~6th ink heads 4A1~4F1 Upstream head 4A2~4F2 Downstream head 5 Pre-processing head (processing head) 6 Post-processing head (processing head) 7 Subtank 7A~7F Ink subtank 71 Sub-tank for pre-treatment liquid 72 Sub-tank for post-processing liquid F Conveying direction S Main scanning direction W work (recording media)

Claims

1. a conveying unit that conveys the recording medium in a predetermined conveying direction; a carriage that moves back and forth in a main scanning direction that intersects with the transport direction; one or more ink head rows mounted on the carriage at predetermined positions in the transport direction; a processing head mounted on the carriage and configured to eject a non-color-forming processing liquid; Equipped with each of the one or more ink head rows includes a plurality of ink heads arranged in the main scanning direction, each of which ejects ink for forming an image; the treatment head includes a pretreatment head that is disposed upstream of the one or more ink head rows in the transport direction and that ejects a pretreatment liquid, which is the treatment liquid; an inkjet recording device in which, when the head of the plurality of ink heads and the processing head that is located at the furthest end in the main scanning direction is referred to as the one-end head, and the head that is located at the furthest end in the main scanning direction is referred to as the other-end head, and the distance in the main scanning direction from the one-end head to the other-end head is referred to as LC, and the distance in the main scanning direction from the one-end head to the pre-processing head is referred to as B1, the pre-processing head is arranged to satisfy the relationship of Equation 1. |(B1-LC / 2)| / LC≦1 / 4...(Formula 1)

2. 2. The inkjet recording apparatus according to claim 1, an inkjet recording apparatus in which a plurality of the pre-processing heads are arranged side by side in the main scanning direction, and at least one of the plurality of pre-processing heads is arranged so as to satisfy the relationship of formula 1.

3. 3. The inkjet recording apparatus according to claim 2, an inkjet recording apparatus, wherein all of the plurality of pretreatment heads are arranged so as to satisfy the relationship of formula 1 above.

4. 4. The inkjet recording apparatus according to claim 1, the processing head further includes a post-processing head that is disposed downstream of the one or more ink head rows in the transport direction and that ejects a post-ejection liquid that is the processing liquid, a plurality of ink head rows are arranged in the transport direction; one of the ink head rows has one ink head that ejects ink of a predetermined color, another ink head row of the plurality of ink head rows has another ink head disposed adjacent to the one ink head and ejecting the ink of the predetermined color; an inkjet recording apparatus, wherein the pre-treatment head and the post-treatment head are arranged so as to satisfy the following relationship, where B2 is the distance in the main scanning direction from the one end side head to the post-treatment head; |(B1+B2-LC) / LC|≦1 / 2

5. a conveying unit that conveys the recording medium in a predetermined conveying direction; a carriage that moves back and forth in a main scanning direction that intersects with the transport direction; one or more ink head rows mounted on the carriage at predetermined positions in the transport direction; a processing head mounted on the carriage and configured to eject a non-color-forming processing liquid; Equipped with each of the one or more ink head rows includes a plurality of ink heads arranged in the main scanning direction, each of which ejects ink for forming an image; the treatment head includes a post-treatment head that is disposed downstream of the one or more ink head rows in the transport direction and that ejects a post-treatment liquid that is the treatment liquid, an inkjet recording device in which, when the head of the plurality of ink heads and the processing heads that is located at the furthest one end in the main scanning direction is referred to as the one-end head, and the head that is located at the furthest other end is referred to as the other-end head, and when the distance in the main scanning direction from the one-end head to the other-end head is referred to as LC, and the distance in the main scanning direction from the one-end head to the post-processing head is referred to as B2, the post-processing head is arranged to satisfy the relationship of Equation 2. |(B2-LC / 2)| / LC≦1 / 4...(Formula 2)

6. 6. The inkjet recording apparatus according to claim 5, an inkjet recording apparatus in which a plurality of the post-processing heads are arranged side by side in the main scanning direction, and at least one of the plurality of post-processing heads is arranged so as to satisfy the relationship of formula 2.

7. 7. The inkjet recording apparatus according to claim 5, the processing head further includes a pre-processing head that is disposed upstream of the one or more ink head rows in the transport direction and that ejects a pre-ejection liquid that is the processing liquid, a plurality of ink head rows are arranged in the transport direction; one of the ink head rows has one ink head that ejects ink of a predetermined color, another ink head row of the plurality of ink head rows has another ink head disposed adjacent to the one ink head and ejecting the ink of the predetermined color; an inkjet recording apparatus, wherein when a distance in the main scanning direction from the one end side head to the pre-treatment head is B1, the pre-treatment head and the post-treatment head are arranged so as to satisfy the relationship of the following formula: |(B1+B2-LC) / LC|≦1 / 2

8. 7. The inkjet recording apparatus according to claim 5, the processing head further includes a pre-processing head that is disposed upstream of the one or more ink head rows in the transport direction and that ejects a pre-ejection liquid that is the processing liquid, an inkjet recording apparatus, wherein the pretreatment head is disposed so as to satisfy the following relationship, where B1 is the distance in the main scanning direction from the one end side head to the pretreatment head; |(B1-LC / 2)| / LC≦1 / 4

9. 9. The inkjet recording apparatus according to claim 8, a plurality of ink head rows are arranged in the transport direction; one of the ink head rows has one ink head that ejects ink of a predetermined color, another ink head row of the plurality of ink head rows has another ink head disposed adjacent to the one ink head and ejecting the ink of the predetermined color; an inkjet recording apparatus, wherein the pre-treatment head and the post-treatment head are arranged so as to satisfy the relationship of the following formula: |(B1+B2-LC) / LC|≦1 / 3

10. 10. The inkjet recording apparatus according to claim 1, The inkjet recording apparatus, wherein the processing head is arranged within a range of an arrangement width of the plurality of ink heads in the main scanning direction.

11. 11. The inkjet recording apparatus according to claim 1, an inkjet recording apparatus, wherein the processing head is arranged so that a portion of the processing head is interposed between a pair of ink heads adjacent to each other in the main scanning direction among the plurality of ink heads included in one of the ink head rows;

12. 12. The inkjet recording apparatus according to claim 1, the processing head is disposed so that a portion of the processing head is adjacent to the ink head in the main scanning direction and the transport direction; the plurality of ink heads include a plurality of same-color ink heads that eject ink of the same color, an inkjet recording device, wherein, when the number of adjacent processing heads among the processing heads in the main scanning direction and the transport direction is counted for each of the same-color ink heads, the difference between the maximum and minimum counts is 1 or less.

13. 13. The inkjet recording apparatus according to claim 1, the processing head is disposed so that a portion of the processing head is adjacent to the ink head in the main scanning direction and the transport direction; the plurality of ink heads include at least a first ink head that ejects ink of a first color and a second ink head that ejects ink of a second color; An inkjet recording device that, when the first ink head has a greater number of adjacent processing heads than the second ink head, ejects, as the first color ink, an ink that has a smaller change in viscosity with temperature than the second color ink.

14. 14. The inkjet recording apparatus according to claim 1, The inkjet recording apparatus, wherein the processing head is arranged in a central region of the arrangement width of the ink head row in the main scanning direction.

15. 15. The inkjet recording apparatus according to claim 1, The processing head includes: a pretreatment head that is disposed upstream of the one or more ink head rows in the transport direction and that ejects a pretreatment liquid that is the treatment liquid; a post-treatment head that is disposed downstream of the one or more ink head rows in the transport direction and that ejects a post-treatment liquid that is the treatment liquid; Equipped with An inkjet recording device in which the pre-processing heads and the post-processing heads are arranged so that the center of arrangement or alignment of one or more of the pre-processing heads in the main scanning direction and the center of arrangement or alignment of one or more of the post-processing heads coincide in the main scanning direction.

16. 16. The inkjet recording apparatus according to claim 15, When the number of the pre-processing heads and the post-processing heads, whichever is larger, is m and the number of the post-processing heads, whichever is smaller, is n, the requirement m = n + odd number is satisfied; an inkjet recording apparatus, wherein the center of arrangement or alignment of the pre-treatment head and the post-treatment head coincides with the arrangement position of one of the plurality of ink heads in the main scanning direction;

17. 17. The inkjet recording apparatus according to claim 1, The processing head includes: a pretreatment head that is disposed upstream of the one or more ink head rows in the transport direction and that ejects a pretreatment liquid that is the treatment liquid; a post-treatment head that is disposed downstream of the one or more ink head rows in the transport direction and that ejects a post-treatment liquid that is the treatment liquid; Equipped with a holding member that holds the carriage in a state that allows it to move back and forth in the main scanning direction; the carriage includes an engagement portion and is held by the engagement portion in a cantilevered state on the holding member; In the inkjet recording apparatus, the pre-treatment head is disposed closer to the engaging portion than the post-treatment head in the transport direction.

18. 18. The inkjet recording apparatus according to claim 1, The processing head includes: a pretreatment head that is disposed upstream of the one or more ink head rows in the transport direction and that ejects a pretreatment liquid that is the treatment liquid; a post-treatment head that is disposed downstream of the one or more ink head rows in the transport direction and that ejects a post-treatment liquid that is the treatment liquid; Equipped with a holding member that holds the carriage in a state that allows it to move back and forth in the main scanning direction; the carriage includes an engagement portion and is held by the engagement portion in a cantilevered state on the holding member; an inkjet recording apparatus, wherein one of the pre-treatment heads and the post-treatment heads, which has a smaller number of heads, is arranged on the engagement portion side of the carriage;

19. 19. The inkjet recording apparatus according to claim 1, a holding member that holds the carriage in a state that allows it to move back and forth in the main scanning direction; the carriage includes an engagement portion and is held by the engagement portion in a cantilevered state on the holding member; In an inkjet recording device, in a head array of the ink head and the processing head, the head arranged closest to the engagement portion of the carriage is the processing head, and the processing head is arranged at a position excluding the end of the head array in the main scanning direction.

20. 20. The inkjet recording apparatus according to claim 1, The ink supply system further includes a plurality of ink sub-tanks for supplying the ink to each of the plurality of ink heads, and a treatment liquid sub-tank for supplying the treatment liquid to the treatment head, an ink jet recording device, wherein the plurality of ink sub-tanks are mounted on the carriage so as to be aligned in the main scanning direction, and the treatment liquid sub-tank is mounted on the carriage at a position different from the plurality of ink sub-tanks in the transport direction.

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