Printing unit and recording device

Abstract

This printing unit comprises a carriage which reciprocates in a main scanning direction, and a plurality of ink heads for ejecting ink. The plurality of ink heads each extend in the main scanning direction, and are mounted in the carriage so as to form a plurality of ink head rows disposed side by side in a sub-scanning direction intersecting the main scanning direction. The plurality of ink heads include a plurality of same-color ink head groups each configured from a plurality of same-color ink heads that eject ink of the same color. In at least one same-color ink head group among the plurality of same-color ink head groups, the plurality of same-color ink heads are disposed in one ink head row among the plurality of ink head rows and are not disposed in another ink head row.

Description

Technical Field

[0001] The present disclosure relates to a printing unit and a recording apparatus including an ink head mounted on a carriage that moves in a main scanning direction.

Background Art

[0002] As an inkjet recording apparatus such as an inkjet printer, an apparatus including a printing unit that performs printing on a recording medium is known. The printing unit has an ink head that discharges ink for image formation toward the recording medium. When the recording medium is wide, the above ink head is mounted on a carriage that reciprocates in the main scanning direction. At the time of printing, the recording medium is intermittently fed in a predetermined direction (sub-scanning direction), and ink is discharged from the ink head while the carriage reciprocates in the main scanning direction during the stop of the recording medium.

[0003] Patent Document 1 discloses a technique in which a plurality of ink heads are arranged in a line along the main scanning direction. Further, the plurality of ink heads include same-color ink heads that discharge the same color of ink.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

[0005] A printing unit according to one aspect of the present disclosure comprises a carriage that reciprocates in a main scanning direction and a plurality of ink heads that eject ink. The plurality of ink heads are mounted on the carriage such that each of them extends along the main scanning direction and is arranged in a sub-scanning direction intersecting the main scanning direction, forming a plurality of ink head rows. The plurality of ink heads include a plurality of same-color ink head sets, each consisting of a plurality of same-color ink heads that eject ink of the same color. In at least one of the plurality of same-color ink head sets, the plurality of same-color ink heads are located in one of the plurality of ink head rows but not in any other ink head rows.

[0006] Furthermore, a recording device relating to another aspect of this disclosure comprises the printing unit described above and a transport unit that transports the recording medium along a transport direction parallel to the sub-scanning direction. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is a perspective view showing the overall configuration of an inkjet recording apparatus according to one embodiment of the present disclosure. [Figure 2] Figure 2 is a schematic cross-sectional view along line II-II in Figure 1. [Figure 3] Figure 3 is an enlarged perspective view of the carriage shown in Figure 1. [Figure 4] Figure 4 is a schematic diagram showing a serial printing method employed in one embodiment of the present disclosure. [Figure 5A] Figure 5A is a schematic diagram showing the printing status of the carriage during its outbound and return journeys. [Figure 5B] Figure 5B is a schematic diagram showing the printing status of the carriage during its outbound and return journeys. [Figure 6] Figure 6 is a schematic plan view showing the arrangement of the ink head and processing head on the carriage shown in Figure 3. [Figure 7] Figure 7 is a schematic plan view showing the arrangement of the ink head and processing head on the carriage according to the first modified embodiment of the present disclosure. [Figure 8] Figure 8 is a schematic plan view showing the arrangement of the ink head and processing head on the carriage according to a second modified embodiment of the present disclosure. [Figure 9] Figure 9 is a schematic plan view showing the arrangement of the ink head and processing head on the carriage according to the third modified embodiment of the present disclosure. [Modes for carrying out the invention]

[0008] The printing units according to each embodiment of this disclosure will be described below with reference to the drawings. In these embodiments, as a specific example of a device equipped with a printing unit, an inkjet printer (recording device) equipped with an ink head that ejects image-forming ink onto a wide and long recording medium will be exemplified. Inkjet printers are suitable for digital textile printing, which prints images such as characters and patterns onto recording media made of fabrics such as woven or knitted materials using an inkjet method. Of course, the printing units according to this disclosure can also be used for printing various images onto recording media such as paper sheets and resin sheets.

[0009] [Overall configuration of an inkjet printer] Figure 1 is a perspective view showing the overall configuration of an inkjet printer 1 according to the first embodiment of this disclosure, and Figure 2 is a schematic cross-sectional view taken along line II-II in Figure 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, a workpiece transport unit 20 (transport unit) and a carriage 3 incorporated into the device frame 10. In this embodiment, the left-right direction is the main scanning direction S (Figure 3) when printing on the workpiece W, and the direction from rear to front is the sub-scanning direction (the transport direction F of the workpiece W, which intersects the main scanning direction S).

[0010] The device frame 10 forms a framework for mounting various components of the inkjet printer 1. The workpiece transport unit 20 is a mechanism that intermittently feeds (transports) the workpiece W so that it moves in a transport direction F from rear to front within 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 reciprocates in the main scanning direction S (left-right direction) which intersects the transport direction F of the workpiece W during the inkjet printing process. This movable unit constitutes the printing unit of this disclosure.

[0011] The apparatus frame 10 includes a central frame 111, a right frame 112, and a left frame 113. The central frame 111 forms the framework for mounting various components of the inkjet printer 1 and has a left-right width corresponding to the workpiece 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. The space between the right frame 112 and the left frame 113 is the printing area 12 where the printing process is performed on the workpiece W.

[0012] The right frame 112 forms a 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 a folding area 14 for the carriage 3. The folding area 14 is an area where the carriage 3, which has primarily scanned the printing area 12 from right to left during the printing process, temporarily enters when it performs a primary scan in the reverse direction.

[0013] A carriage guide 15 is assembled on the upper side of the device frame 10 to allow the carriage 3 to move back and forth in the left-right direction. The carriage guide 15 is a long, flat plate-shaped member and is positioned above the workpiece transport section 20. A timing belt 16 is mounted on the carriage guide 15 so as to be able to move around in the left-right direction (main scanning direction). The timing belt 16 is an endless belt and is driven to move around in the left or right direction.

[0014] The carriage guide 15 is equipped with a pair of upper and lower guide rails 17 that extend parallel to each other in the left-right direction, holding the carriage 3 in a state where it can reciprocate in the main scanning direction S. The carriage 3 is engaged with the guide rails 17. The carriage 3 is also fixed to the timing belt 16. As the timing belt 16 rotates to the left or right, the carriage 3 moves along the carriage guide 15 to the left or right, guided by the guide rails 17.

[0015] Referring mainly to Figure 2, the workpiece transport unit 20 includes a feed roller 21 for feeding out the workpiece W before printing and a take-up roller 22 for winding up the workpiece W after printing. The feed roller 21 is located at the lower rear of the device frame 10 and is the winding shaft of the feed roll WA, which is the winding body of the workpiece W before printing. The take-up roller 22 is located at the lower front of the device frame 10 and is the winding shaft of the take-up roll WB, which is the winding body of the workpiece W after printing. The take-up roller 22 is equipped with a first motor M1 that rotates the take-up roller 22 around its axis and performs the winding operation of the workpiece W.

[0016] A path between the delivery roller 21 and the take-up roller 22 and passing through the printing area 12 serves as the conveyance path for the workpiece W. In this conveyance path, a first tension roller 23, a workpiece guide 24, a conveyance roller 25, a pinch roller 26, a folding roller 27, and a second tension roller 28 are arranged in order from the upstream side. The first tension roller 23 applies a predetermined tension to the workpiece W upstream of the conveyance roller 25. The workpiece guide 24 changes the conveyance direction of the workpiece W from upward to forward and carries the workpiece W into the printing area 12.

[0017] The conveyance roller 25 is a roller that generates a conveyance force for intermittently feeding the workpiece W in the printing area 12. The conveyance roller 25 is rotationally driven about its axis by a second motor M2 and intermittently conveys the workpiece W in the forward direction (a predetermined conveyance 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 arranged to face the conveyance roller 25 from above and forms a conveyance nip portion with the conveyance roller 25.

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

[0019] The carriage 3 is supported in a cantilevered manner on the guide rail 17 and reciprocates in the main scanning direction S (in the left-right direction in this embodiment) that intersects (orthogonal in this embodiment) the conveyance direction F. The carriage 3 includes a carriage frame 30, an ink head 4, a pre-treatment head 5, a post-treatment head 6, and a sub-tank 7 mounted on the carriage frame 30. The carriage frame 30 includes a head support frame 31 and a back frame 32.

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

[0021] Note that the cantilever state means that in the carriage 3, the engaging portion (back frame 32), which is the portion held by the guide rail 17 that is a holding member, exists only on one side, either the upstream side or the downstream side, from the center of the carriage 3 in the conveyance direction F, and there is no other engaging portion on the opposite side of the side where the engaging portion exists. The engaging portion may be further arranged outside the range where the ink head 4 and the processing head are arranged in the conveyance direction F. That is, the engaging portion may be arranged only on the upstream side or only on the downstream side with respect to the range where the ink head 4 and the processing head are arranged in the conveyance direction F.

[0022] [Details of the carriage] A further description of the carriage 3 will be added. FIG. 3 is an enlarged perspective view of the carriage 3 shown in FIG. 1. FIG. 3 shows the conveyance direction F (sub-scanning direction) of the work W and the main scanning direction S, which is the moving direction of the carriage 3. In FIG. 3, an example is shown in which a plurality of ink heads 4 that eject ink for image formation onto the work W, a pre-processing head 5 and a post-processing head 6 that eject a non-coloring processing liquid, and a plurality of sub-tanks 7 that supply the ink and the processing liquid to these heads 4 to 6 are mounted on the carriage 3.

[0023] Each of the ink heads 4 is equipped with numerous 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 an ink passage that guides the ink to these nozzles. As the ink, for example, an aqueous pigment ink containing an aqueous solvent, pigment, and binder resin can be used. The multiple ink heads 4 in this embodiment are each capable of ejecting eight colors of ink. The ink heads 4 are mounted on the head support frame 31 of the carriage 3 so as to be arranged in two rows in the main scanning direction S. Each ink head 4 of each color has two heads. The detailed arrangement of the ink heads 4 will be described in detail later.

[0024] The pre-processing head 5 and post-processing head 6 are positioned differently from the ink head 4 in the transport direction F. The pre-processing head 5 is positioned upstream of the ink head 4 in the transport direction F. Figure 3 shows an example where one pre-processing head 5 is positioned near the left end of the ink head 4 array. Similarly, the post-processing head 6 is positioned downstream of the ink head 4 in the transport direction F. Figure 3 shows an example where one post-processing head 6 is positioned at the right end of the ink head 4 array. In other embodiments, multiple pre-processing heads 5 or multiple post-processing heads 6 may be provided. That is, the carriage 3 is equipped with at least one pre-processing head 5 and at least one post-processing head 6. In other embodiments, the pre-processing head 5 and post-processing head 6 may not be provided.

[0025] Furthermore, a sequence of heads along the main scanning direction S, consisting of the ink head 4, pre-processing head 5, and post-processing head 6, is referred to as a row of heads, or simply a row. Similarly, a sequence of heads along the transport direction F, consisting of the ink head 4, pre-processing head 5, and post-processing head 6, is referred to as a line of heads, or simply a line.

[0026] The pretreatment head 5 discharges a pretreatment solution to perform a predetermined pretreatment on the workpiece W. The pretreatment solution is discharged from the pretreatment head 5 to a position on the workpiece W where ink has not yet been discharged from the inkhead 4. The pretreatment solution is a non-coloring solution that does not develop color even when it adheres to the workpiece W, and is a solution that exhibits functions such as improving the ink's fixation to the workpiece W and the aggregation of the ink pigment. As such a pretreatment solution, a solution containing a binder resin in the solvent, or a solution containing a positively charged cationic resin in the solvent can be used.

[0027] The post-processing head 6 discharges a post-processing solution to perform a predetermined post-processing on the workpiece W to which ink has adhered. The post-processing solution is discharged from the post-processing head 6 to the position on the workpiece W after the ink has been discharged from the ink head 4. The post-processing solution is a non-coloring solution that does not develop color even when it adheres to the workpiece W, and it is a solution that enhances the fixation and robustness (resistance to rubbing and abrasion) of the ink image printed on the workpiece W by the ink head 4. Silicone-based solutions can be used as such post-processing solutions. Note that the post-processing solution and the pre-processing solution are different solutions. Specifically, the components contained in the post-processing solution and the pre-processing solution are different.

[0028] Here, a non-coloring processing solution refers to a solution that, when printed on a recording medium alone, is not perceived as color by the naked eye. Here, "color" includes colors with zero saturation, such as black, white, and gray. A non-coloring processing solution is basically a transparent liquid; however, for example, a liter of the solution may not be completely transparent when viewed in liquid form, and may appear slightly white. Such colors are very faint, and therefore, when printed on a recording medium alone, they are not perceived as color by the naked eye. Note that depending on the type of processing solution, when printed on a recording medium alone, changes such as glossiness may occur on the recording medium; however, such a state is not considered color development.

[0029] In this embodiment, the pre-treatment liquid and post-treatment liquid may be dispensed over substantially the entire surface of the workpiece W, or they may be dispensed selectively according to the image to be printed, similar to ink.

[0030] Next, we will explain the case where pre-treatment and post-treatment solutions are selectively dispensed. As mentioned above, the pre-treatment solution, ink, and post-treatment solution are dispensed in the order of the workpiece W where the color is printed according to the image. In this case, the ink may be one color or multiple colors. In general, the pre-treatment solution and post-treatment solution are not dispensed in the areas where no color is printed, i.e., in the areas where ink is not dispensed. In addition, the selection of the dispensing of the pre-treatment solution and post-treatment solution may be made different from the dispensing of the ink in order to adjust the image quality to be printed or the texture of the workpiece W.

[0031] As shown in Figure 3, an opening 31H is provided in the head support frame 31 where the print head is positioned. The ink head 4, pre-processing head 5, and post-processing head 6 are assembled to the head support frame 31 so that they fit into their respective openings 31H. The nozzles located on the lower end faces of each of the print heads 4, 5, and 6 are exposed through each opening 31H.

[0032] The sub-tanks 7 are supported by the carriage 3 above the heads 4, 5, and 6 via a retaining frame (not shown). Each sub-tank 7 is provided corresponding to each of the heads 4, 5, and 6. Each sub-tank 7 is supplied with ink or processing fluid from a cartridge or main tank (not shown) containing ink and processing fluid, and these are supplied to each of the heads 4, 5, and 6. Each sub-tank 7 and the heads 4, 5, and 6 are connected by piping (not shown in Figure 3).

[0033] As described above, the inkjet printer 1 according to this embodiment is an all-in-one type printer in which three types of heads, an ink head 4, a pre-treatment head 5, and a post-treatment head 6, are mounted on a single carriage 3. With this inkjet printer 1, for example, in the printing process of performing inkjet printing on fabric in digital textile printing, the pre-treatment liquid discharge process and the post-treatment liquid discharge process can be performed integrally. Therefore, the printing process can be simplified and the printing equipment can be made more compact.

[0034] [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 on the workpiece W using a serial printing method. Figure 4 is a schematic diagram showing the serial printing method. In Figure 4, the pre-processing head 5 and post-processing head 6 are omitted, and the carriage 3 is depicted in a simplified manner.

[0035] If the workpiece W has a wide size, it is not possible to print while continuously feeding the workpiece W. The serial printing method is a printing method that repeats the reciprocal movement of the carriage 3 equipped with each color ink head 4 in the main scanning direction S and the intermittent feeding of the workpiece W in the transport direction F. Here, it is assumed that the ink head 4 has a predetermined printing width Pw in the transport direction F. The printing width Pw is approximately equal to the length of the transport direction F of the area where the ink ejection nozzles of the ink head 4 are located. Note that in Figure 4 and Figures 5A and 5B described below, the length of the transport direction F of each head and the printing width Pw are depicted as approximately equal, but in reality, the length of the transport direction F of each head is greater than the printing width Pw and the length of the transport direction F of the area where the ejection nozzles are located.

[0036] Figure 4 shows the state where carriage 3 has moved in the forward direction SA in the main scanning direction S, and printing of a strip image G1 with a print width Pw has been completed. During this main scanning in the forward direction SA, the feed of the workpiece W is stopped. After printing the strip image G1, the workpiece W is fed out in the transport direction F by a pitch corresponding to the print width Pw. At this time, carriage 3 waits in the turnaround area 14 on the left end. After the workpiece W has been fed out, carriage 3 turns back in the return direction SB as the timing belt 16 reverses direction. The workpiece W is in a stopped state. Then, as shown in Figure 4, carriage 3 moves in the return direction SB and prints a strip image G2 with a print width Pw upstream of the strip image G1. The same operation is repeated thereafter.

[0037] Figures 5A and 5B are schematic diagrams showing the printing process on the forward and return journeys of carriage 3. Here, the ink head 4, pre-processing head 5, and post-processing head 6 mounted on carriage 3 are shown in a simplified manner. Ink head 4 is equipped with first, second, third, and fourth ink heads 4A, 4B, 4C, and 4D for ejecting different first, second, third, and fourth color inks, respectively. These first to fourth ink heads 4A to 4D are arranged in a line in the main scanning direction S. The pre-processing head 5 is located upstream of the ink head 4 in the transport direction F, and the post-processing head 6 is located downstream. Also, as explained in Figure 4, the workpiece W is sent in the transport direction F between the forward and return printing journeys. The travel distance in the transport direction F is the distance pitch (head pitch) between adjacent heads in the transport direction F. This travel distance is also the printing width Pw of each head 4, 5, and 6.

[0038] Figure 5A shows the state in which the carriage 3 is performing a printing operation while moving in the forward path SA in the main scanning direction S (forward main scan). Region A4 on the workpiece W is the region in which the pre-processing head 5, mounted on the uppermost side of the carriage 3, faces. In this forward main scan, a pre-processing layer Lpre is formed on region A4 by the pre-processing liquid ejected from the pre-processing head 5.

[0039] Region A3 is located one head pitch downstream of region A4 and is the region where the ink heads 4 face each other. On region A3, the pre-processing layer Lpre has already been formed along the entire length in the main scanning direction by the previous return main scan. In this forward main scan, the first, second, third, and fourth ink layers LCA, LCB, LCC, and LCD are formed on the pre-processing layer Lpre in region A3 by the first to fourth color inks ejected sequentially in the order of the first to fourth ink heads 4A to 4D. Note that in Figure 5A, the fourth to first ink layers LCD to LCA are shown as being stacked sequentially for ease of understanding, but they are not actually stacked. Also, the aforementioned pre-processing layer Lpre and the post-processing layer Lpos described later are not formed on the workpiece W.

[0040] Region A2 is located one head pitch downstream of region A3 and is the region where the post-processing head 6, mounted at the downstream end of carriage 3, faces. On region A2, the pre-processing layer Lpre from the previous forward main scan and the first to fourth ink layers LCA to LCD from the previous return main scan have already been formed along the entire length in the main scan direction. In the current forward 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 discharged from the post-processing head 6.

[0041] Region A1 is the region located one head pitch downstream of region A2, through which carriage 3 has passed and where the printing process is completed. Specifically, in region A1, the pre-processing layer Lpre, the first to fourth ink layers LCA to LCD, and the post-processing layer Lpos are formed along the entire length in the main scanning direction.

[0042] Figure 5B shows the state after the forward main scan in Figure 5A has been completed, with the carriage 3 turning around and moving in the return direction SB while performing the return main scan. Before the aforementioned turning around movement, the workpiece W has been fed forward by one head pitch in the transport direction F. Region A5 on the workpiece W is one head pitch upstream of region A4, and in this return main scan, it is the region where the pre-processing head 5 faces. A pre-processing layer Lpre is formed on region A5 by the pre-processing liquid discharged from the pre-processing head 5.

[0043] In areas A4 and A3, the first to fourth ink layers LCA to LCD and the post-processing layer Lpos are formed on top of the existing layers, respectively. Specifically, in area A4, the first to fourth ink layers LCA to LCD are formed on top of the pre-processing layer Lpre. In area A3, the post-processing layer Lpos is formed on top of the first to fourth ink layers LCA to LCD. Area A2 is the area where the printing process is completed, following area A1.

[0044] The reason why printing is possible in both the forward and return main scans, as described above, is that the pre-processing head 5 and post-processing head 6 are positioned shifted in the transport direction F relative to the ink head 4. If, for example, the pre-processing head 5, ink head 4, and post-processing head 6 were arranged in a line in the main scan direction S in this order on the carriage 3, then printing that allows the pre-processing liquid and post-processing liquid to land in the desired order could only be achieved in either the forward or return main scan. To enable bidirectional printing, the pre-processing head 5 and post-processing head 6 pair would have to be positioned on both sides of the ink head 4 array. In this case, the length of the carriage 3 in the main scan direction S would increase. Since such an arrangement is unnecessary in this embodiment, the length of the carriage 3 in the main scan direction S can be reduced.

[0045] Furthermore, by using multiple rows of ink heads 4, the amount of ink deposited on the workpiece W can be increased. For example, if there are two rows of ink heads 4, printing can be performed as follows: The first row of ink heads 4 forms the first to fourth ink layers LCA to LCD as described above. Then, 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' worth of ink can be printed on the workpiece W.

[0046] [Head placement] Figure 6 is a schematic plan view showing the arrangement of the ink heads 4 and processing heads 5 and 6 on the carriage 3 shown in Figure 3. As mentioned above, the carriage 3 is cantilevered by the guide rails 17 on the back frame 32 (Figure 3). The back frame 32 is located 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 where the back frame 32 is located is considered the base end, and the side of the head support frame 31 opposite the base end is considered the front end. As previously described, the head support frame 31 of the carriage 3 is equipped with multiple ink heads 4 that eject eight colors of ink, a pre-processing head 5, and a post-processing head 6. Each ink head 4 of each color has two unit heads. Two ink heads 4 that eject the same color of ink are called same-color ink heads, and a set of these two same-color ink heads is called a same-color ink head set.

[0047] In Figure 6, each of the 16 ink heads 4 is labeled with an alphabet letter corresponding to the color of ink it ejects. Specifically, K stands for black, Y for yellow, M for magenta, C for cyan, B for blue, V for violet, O for orange, and G for green. The pre-processing head 5 is labeled "pre," and the post-processing head 6 is labeled "post."

[0048] As shown in Figure 6, in the transport direction F, the pre-processing head 5 is positioned upstream of the multiple ink heads 4, and the post-processing head 6 is positioned downstream of the multiple ink heads 4. Furthermore, the pre-processing head 5 is positioned at the left end of the arrangement range in the main scanning direction S where the multiple ink heads 4 are positioned. On the other hand, the post-processing head 6 is positioned at the right end of the arrangement range where the multiple ink heads 4 are positioned, opposite to the pre-processing head 5 in the main scanning direction S. As a result of the above head arrangement, the pre-processing head 5 and the post-processing head 6 are positioned within the arrangement width range of the ink heads 4 in the main scanning direction S.

[0049] Multiple ink heads 4 are mounted on the carriage 3 so that each extends along the main scanning direction S and is arranged in a sub-scanning direction (transport direction F) that intersects the main scanning direction S, forming two (or more) rows of ink heads. As a result, it is possible to accommodate many ink heads 4 while reducing the width of the carriage 3 in the main scanning direction S. The first row of ink heads 4 on the side closer to the pre-processing head 5, i.e., the upstream side in the transport direction F, contains the M, Y, B, and V color ink heads 4. A pair of M color ink heads 4 are positioned on the outermost side in the main scanning direction S, and similarly, a pair of Y color ink heads 4, a pair of B color ink heads 4, and a pair of V color ink heads 4 are positioned sequentially towards the inside of the main scanning direction S. In other words, the above four color ink heads 4 are arranged symmetrically in the main scanning direction S.

[0050] On the side closer to the post-processing head 6, i.e., the second row of ink heads 4 downstream in the transport direction F, are arranged the K, C, O, and G color ink heads 4. A pair of K color ink heads 4 are positioned on the outermost side in the main scanning direction S, and similarly, a pair of C color ink heads 4, a pair of O color ink heads 4, and a pair of G color ink heads 4 are positioned sequentially towards the inside of the main scanning direction S. In other words, the above four color ink heads 4 are also arranged symmetrically in the main scanning direction S.

[0051] Furthermore, as shown in Figure 6, the ink heads 4 in the first row and the ink heads 4 in the second row are offset from each other in the main scanning direction S, and the ink heads 4 are positioned between adjacent ink heads 4, resulting in an overall staggered arrangement. A pre-processing head 5 is positioned behind the left-hand K-color ink head 4 in the second row, and a post-processing head 6 is positioned in front of the right-hand M-color ink head 4 in the first row.

[0052] Unless otherwise specified, in all figures, including Figure 6, the distance between adjacent heads (the distance between the centers of each head) is the same in the main scanning direction S. Similarly, the distance between adjacent heads (the distance between the centers of each head) is the same in the transport direction F.

[0053] Furthermore, in this embodiment, two ink heads 4 that eject ink of the same color (same-color ink heads) are arranged in the same row. In other words, each color ink head 4 is located in one of the two ink head rows and not in the other. As a result, when the carriage 3 moves back and forth in the main scanning direction, ink can be ejected from the two ink heads 4 to a predetermined pixel during scanning in the same direction. Therefore, compared to the case where the two ink heads 4 are arranged in different rows, it is possible to shorten the difference in ink impact time to the pixel and form a stable image.

[0054] To elaborate on the above, if two K-color ink heads 4 are arranged one in the first row and one in the second row, a difference will occur in the time interval between the ink ejected from the two ink heads 4 landing on the same pixel when scanning to the right and then moving back and forth, and when scanning to the left and then moving back and forth. In particular, if this time interval becomes large, the ink may become too dark. In this embodiment, this problem can be solved by consolidating the ink heads 4 of the same color into a single row.

[0055] Furthermore, as shown in Figure 6, for each color, two ink heads 4 that eject the same color ink are arranged symmetrically in the main scanning direction S, or more specifically, symmetrically left and right with respect to a center line extending in the transport direction F at the center of the main scanning direction S. Therefore, regardless of whether the carriage 3 scans to the right or left, it is possible to ensure that the landing order of each color ink is the same and to reduce the difference in landing times for each color, thereby preventing the occurrence of partial color differences on the workpiece W. However, if the 16 ink heads 4 were arranged symmetrically in a single line as described above, the distribution of differences in landing times for each color (variation between colors) would become large.

[0056] Furthermore, in this embodiment, the two ink heads 4 (black ink head set) that eject black ink are positioned at both ends in the main scanning direction S. This allows for a higher density of black on the workpiece W. Compared to the colors of the fabric that makes up the workpiece W, black is more difficult to represent. Since black does not reflect light, if some reflection of the fabric color remains, it becomes more difficult to represent a pure black color. In this embodiment, by positioning the black ink heads 4 at both ends, the contact time from the two ink heads 4 to a given pixel can be increased, thereby increasing the density. As a result, the print quality can be improved. Note that if the ink is pigment-based, it is difficult to completely cover the fabric with pigment, so it is preferable to increase the density by utilizing such a difference in contact time.

[0057] In particular, in this embodiment, the black ink head 4 is positioned in the downstream (farthest downstream) row in the transport direction F. Therefore, the black ink lands relatively later, allowing for an even higher density. If the ink heads 4 are arranged in three or more rows, it is desirable for the black ink head 4 to be positioned further downstream in the transport direction F, and even more desirable for it to be positioned at the furthest downstream.

[0058] Furthermore, in this embodiment, as shown in Figure 6, the black, cyan, magenta, and yellow ink heads 4 (basic color ink heads) are positioned outside the main scanning direction S compared to the ink heads 4 of other colors (non-basic color ink heads). Therefore, by positioning the ink heads 4 of basic colors, which are important for color reproduction, on both sides of the main scanning direction S, as well as black, and increasing the time difference between ink droplets, the color reproduction of the basic colors can be improved.

[0059] Furthermore, these basic color ink heads 4 are used relatively frequently. Therefore, by positioning these ink heads 4 in locations on the carriage 3 where they are not too densely packed and have good heat dissipation, such as at both ends in the main scanning direction S, the temperature rise of each ink head 4 can be suppressed. In addition, by distributing these heat-generating ink heads 4 to two locations on both sides in the main scanning direction S, the amount of heat generated can also be distributed.

[0060] Furthermore, in this embodiment, as shown in Figure 6, the black ink head 4 and the yellow ink head 4 are arranged in different rows. If black and yellow inks mix in a near-liquid state before they penetrate and fix into the workpiece W, it may be difficult to obtain good image quality. Therefore, by arranging black and yellow inks in different rows, mixing as described above can be suppressed, making it possible to obtain stable image quality. This configuration can also be achieved by arranging the ink heads 4 in multiple rows, as in this embodiment.

[0061] Furthermore, in this embodiment, the yellow ink head 4 and the ink heads 4 for inks with similar hues (green, orange) are arranged in different rows. As a result, as described above, mixing of these inks with similar hues can be suppressed.

[0062] This disclosure is not limited to the embodiments described above, and can take the following forms.

[0063] (1) The ink heads 4 are not limited to being arranged in two rows on the carriage 3. The ink heads 4 may be arranged in three or more rows.

[0064] (2) In the example shown in Figure 6, the two ink heads 4 are arranged in the same row for all colors. However, for inks whose color development is less affected by the time interval between impacts, the two ink heads 4 may be arranged in separate rows.

[0065] (3) Figure 7 is a schematic plan view showing the arrangement of ink heads and processing heads on a carriage according to the first modified embodiment of the present disclosure. The indication of ink colors is the same as in Figure 6 (and the same applies to other figures described later). In this modified embodiment, the plurality of ink heads 4 include a plurality of basic color ink heads that each eject ink of a basic color (K, C, M, Y) which is one of the basic colors (black, cyan, magenta, and yellow), and a plurality of non-basic color ink heads that each eject ink of a color other than the basic color (B, V, O, G). The basic color ink heads are arranged in the row of the plurality of ink heads 4 on the downstream side in the transport direction F.

[0066] With this arrangement, the inks of each color ejected from the basic color ink head 4 land relatively later, thus improving the color development of the basic color. Furthermore, as in the previous embodiment, positioning the black ink head 4 at both ends of the main scanning direction S further increases the density of the black ink. Additionally, placing yellow, which tends to have poor color when mixed with black, as far away from black as possible further improves color development.

[0067] (4) Figure 8 is a schematic plan view showing the arrangement of ink heads and processing heads on a carriage according to a second modified embodiment of the present disclosure. In this modified embodiment, the ink head 4 that ejects the ink of the color closest to cyan in hue among the plurality of ink heads 4 is arranged in the downstream row in the transport direction F of the plurality of ink head rows. Specifically, the two cyan ink heads 4 are arranged in the second row. It is also desirable that the second and subsequent colors that are closest to cyan in hue among the plurality of ink heads 4 be similarly arranged in the second row (the downstream row in the transport direction F). In Figure 8, blue corresponds to the color second closest to cyan.

[0068] Furthermore, if the ink colors ejected by multiple ink heads 4 are arranged in order of their hue from closest to cyan, and half of the inks closest to cyan are designated as cyan-based inks and the other half as non-cyan-based inks, it is desirable that more than half of the inks located in the downstream row of the multiple ink head rows in the transport direction are set to the cyan-based inks. In Figure 8, cyan, blue, and green correspond to cyan-based inks, and represent more than half of the inks in the second row of ink heads 4.

[0069] With this configuration, by applying cyan-based ink, which tends to produce a relatively darker color even with the same amount of ink, later, the color development of the cyan-based ink can be improved.

[0070] In the above, the inks were classified based on cyan, but in other embodiments, red may be used as the basis. In this case, it is desirable that the ink head 4 that ejects the ink of the color closest to red in hue among the multiple ink heads 4 be located in the upstream row in the transport direction F of the multiple ink head rows. Specifically, in Figure 8, the two magenta ink heads 4 are located in the first row. Similarly, it is desirable that the second and subsequent colors with hues close to red among the multiple ink heads 4 be located in the first row (the upstream row in the transport direction F). In Figure 8, violet corresponds to the color second closest to red.

[0071] Furthermore, if the ink colors ejected by each of the multiple ink heads 4 are arranged in order of their hue from closest to red, with half of the inks closest to red being designated as red-based inks and the other half as non-red-based inks, it is desirable that more than half of the inks located in the upstream column of the transport direction F among the multiple ink head rows be set to the red-based inks. In Figure 8, magenta, orange, and violet correspond to red-based inks, and represent more than half of the inks in the first column of ink heads 4.

[0072] With this configuration, the red inks land first, and by relatively suppressing their color development, the overall color development, including that of the cyan inks, can be improved.

[0073] (5) Figure 9 is a schematic plan view showing the arrangement of ink heads and processing heads on a carriage according to a third modified embodiment of the present disclosure. In this modified embodiment, the LM (light magenta, second ink) ink head 4 (second ink head) is located at the innermost (center) part of the second row of ink heads 4 in the main scanning direction S. On the other hand, the first row has an ink head 4 (first ink head) that ejects magenta ink (first ink). Light magenta has a hue similar to magenta and is relatively brighter. Including such light-colored inks can broaden the range of color expression (color space).

[0074] In this case, if light magenta ink, which has a lighter color than magenta, lands on the workpiece W, and then other inks land on the same pixel, the light magenta color is easily affected and its color reproduction is impaired. Therefore, in this modified embodiment, by placing the light magenta in the second row, it is possible to make it less susceptible to the effects of subsequent ink landings.

[0075] Furthermore, as shown in Figure 9, the ink head 4 that ejects light magenta ink is positioned on the inside (center) of the main scanning direction S. As a result, by reducing the contact time between the inks ejected from the two ink heads 4, it becomes possible to produce a lighter shade of light magenta ink, thereby expanding the color gamut on the workpiece W.

[0076] It should be noted that the light-colored inks are not limited to the light magenta described above. In other embodiments, inks such as light cyan and light yellow may be used, or gray ink may be used as the light-colored black ink. In this case as well, the color development of the light-colored inks can be maintained by placing the relatively light-colored inks in the second row (downstream in the transport direction F). Here, black and gray are considered to be approximate hues in the sense that they do not exhibit a specific hue.

[0077] (6) In addition, while the appropriate arrangement of the ink heads 4 has been described in each of the above embodiments with respect to the ink color, this disclosure is not limited thereto. When a plurality of ink heads 4 include a first ink head that ejects a first ink and a second ink head that ejects a second ink having a higher pigment content than the first ink, it is desirable that in the plurality of ink head rows, the second ink head is arranged in a row downstream of the first ink head in the transport direction F.

[0078] Generally, inks with poor color development tend to contain a relatively large amount of pigment to compensate for this. However, there are limits to the pigment content due to other properties required of the ink. Therefore, by positioning the ink head 4 that ejects such ink downstream in the transport direction F where color development is higher, the poor color development can be compensated for.

[0079] Similarly, if the plurality of ink heads 4 include a first ink head that ejects a first ink and a second ink head that ejects a second ink having a higher binder content than the first ink, it is desirable that in the plurality of ink head rows, the second ink head is arranged in a row downstream of the first ink head in the transport direction F.

[0080] Inks with poor color development tend to contain a relatively large amount of binder to compensate for this. However, due to other required properties of the ink, there is a limit to the amount of binder that can be contained. Therefore, by positioning the ink head 4 that ejects such ink downstream in the transport direction F where color development is higher, the color development can be further improved.

[0081] Furthermore, in a carriage 3 having a pre-processing head 5 and a post-processing head 6 as in the previous embodiment, the ink heads 4 can also be arranged as follows. Specifically, if the plurality of ink heads 4 include a first ink head that ejects a first ink and a second ink head that ejects a second ink having a higher pigment content than the first ink, the second ink head may be arranged in the row upstream of the first ink head in the transport direction F in the plurality of ink head rows.

[0082] With this arrangement, after the pretreatment solution lands on a predetermined pixel on the workpiece W, the second ink can be deposited on the same pixel relatively quickly. Therefore, the time required to fix the second ink before the posttreatment solution lands on the pixel and penetrates the workpiece W can be extended. As a result, the fixation of the pigment-rich ink (second ink) to the workpiece W can be improved, and the durability of the printed material can be enhanced.

[0083] Similarly, if the plurality of ink heads 4 include a first ink head that ejects a first ink and a second ink head that ejects a second ink having a higher binder content than the first ink, the second ink head may be arranged in the row upstream of the first ink head in the transport direction F.

[0084] Even with this head configuration, for the same reasons as above, the adhesion of the binder-rich ink (second ink) to the workpiece W can be improved, thereby enhancing the durability of the printed material. [Explanation of Symbols]

[0085] 1. Inkjet printer (recording device) 3 carriages 4 Ink Heads 5 Pre-processing head 6. Post-processing head 7 Sub-tank 10. Device frame 12 Print Area 13 Maintenance Area 14 Turning Point Area 20 Workpiece transport section H Head placement area Double job

Claims

1. A carriage that moves back and forth in the main scanning direction, Multiple ink heads that eject ink, Equipped with, The plurality of ink heads are mounted on the carriage such that each of them forms a plurality of ink head rows, each extending along the main scanning direction and arranged in a sub-scanning direction intersecting the main scanning direction, and ejects ink onto a recording medium being transported along a transport direction parallel to the sub-scanning direction. The aforementioned plurality of ink heads include a plurality of sets of same-color ink heads, each consisting of a plurality of same-color ink heads that eject ink of the same color. In at least one of the plurality of identical color ink head sets, the plurality of identical color ink heads are arranged in one of the plurality of ink head rows and not in any other ink head row. The aforementioned set of multiple ink heads of the same color includes a set of black ink heads that ejects black ink. The aforementioned black ink head set is located in the downstream ink head row in the transport direction among the plurality of ink head rows, and is not located in the upstream ink head row in the transport direction. The plurality of identical ink heads of the black ink head set are arranged at both ends of the ink head row on the downstream side in the transport direction in the main scanning direction. The plurality of ink heads include a plurality of basic color ink heads that each eject ink of one of the basic colors of black, cyan, magenta, and yellow, and a plurality of non-basic color ink heads that each eject ink of a color other than the basic colors. A printing unit in which the primary color ink head is positioned outside the primary scanning direction of the non-primary color ink head.

2. A carriage that moves back and forth in the main scanning direction, Multiple ink heads that eject ink, Equipped with, The plurality of ink heads are mounted on the carriage such that each of them extends along the main scanning direction and is arranged in a sub-scanning direction intersecting the main scanning direction, forming a plurality of ink head rows. The aforementioned plurality of ink heads include a plurality of sets of same-color ink heads, each consisting of a plurality of same-color ink heads that eject ink of the same color. In at least one of the plurality of identical color ink head sets, the plurality of identical color ink heads are arranged in one of the plurality of ink head rows and not in any other ink head row. The plurality of ink heads include a black ink head that ejects black ink and a yellow ink head that ejects yellow ink. The black ink head and the yellow ink head are located in different rows within the plurality of ink head rows and are not located in the same row. The plurality of ink heads include a plurality of basic color ink heads that each eject ink of one of the basic colors of black, cyan, magenta, and yellow, and a plurality of non-basic color ink heads that each eject ink of a color other than the basic colors. A printing unit in which the primary color ink head is positioned outside the primary scanning direction of the non-primary color ink head.

3. A carriage that moves back and forth in the main scanning direction, Multiple ink heads that eject ink, Equipped with, The plurality of ink heads are mounted on the carriage such that each of them extends along the main scanning direction and is arranged in a sub-scanning direction intersecting the main scanning direction, forming a plurality of ink head rows. The aforementioned plurality of ink heads include a plurality of sets of same-color ink heads, each consisting of a plurality of same-color ink heads that eject ink of the same color. In at least one of the plurality of identical color ink head sets, the plurality of identical color ink heads are arranged in one of the plurality of ink head rows and not in any other ink head row. The plurality of ink heads eject ink onto a recording medium that is transported along a transport direction parallel to the sub-scanning direction. Of the plurality of ink heads, the ink head that ejects the ink of the color closest to cyan in terms of hue is located in the downstream row of the plurality of ink head rows in the transport direction. The plurality of ink heads include a plurality of basic color ink heads that each eject ink of one of the basic colors of black, cyan, magenta, and yellow, and a plurality of non-basic color ink heads that each eject ink of a color other than the basic colors. A printing unit in which the primary color ink head is positioned outside the primary scanning direction of the non-primary color ink head.

4. A carriage that moves back and forth in the main scanning direction, Multiple ink heads that eject ink, Equipped with, The plurality of ink heads are mounted on the carriage such that each of them extends along the main scanning direction and is arranged in a sub-scanning direction intersecting the main scanning direction, forming a plurality of ink head rows. The aforementioned plurality of ink heads include a plurality of sets of same-color ink heads, each consisting of a plurality of same-color ink heads that eject ink of the same color. In at least one of the plurality of identical color ink head sets, the plurality of identical color ink heads are arranged in one of the plurality of ink head rows and not in any other ink head row. The plurality of ink heads eject ink onto a recording medium that is transported along a transport direction parallel to the sub-scanning direction. If the ink colors ejected by each of the aforementioned ink heads are arranged in order of their hue from closest to red, and half of the inks closest to red are designated as red-based inks and the remaining half as non-red-based inks, then more than half of the inks arranged in the upstream row of the aforementioned ink head rows in the transport direction are set to red-based inks. The plurality of ink heads include a plurality of basic color ink heads that each eject ink of one of the basic colors of black, cyan, magenta, and yellow, and a plurality of non-basic color ink heads that each eject ink of a color other than the basic colors. A printing unit in which the primary color ink head is positioned outside the primary scanning direction of the non-primary color ink head.

5. A carriage that moves back and forth in the main scanning direction, Multiple ink heads that eject ink, Equipped with, The plurality of ink heads are mounted on the carriage such that each of them forms a plurality of ink head rows, each extending along the main scanning direction and arranged in a sub-scanning direction intersecting the main scanning direction, and ejects ink onto a recording medium being transported along a transport direction parallel to the sub-scanning direction. The aforementioned plurality of ink heads include a plurality of sets of same-color ink heads, each consisting of a plurality of same-color ink heads that eject ink of the same color. In at least one of the plurality of identical color ink head sets, the plurality of identical color ink heads are arranged in one of the plurality of ink head rows and not in any other ink head row. The aforementioned set of multiple ink heads of the same color includes a set of black ink heads that ejects black ink. The aforementioned black ink head set is located in the downstream ink head row in the transport direction among the plurality of ink head rows, and is not located in the upstream ink head row in the transport direction. The plurality of identical ink heads of the black ink head set are arranged at both ends of the ink head row on the downstream side in the transport direction in the main scanning direction. The plurality of ink heads eject ink onto a recording medium that is transported along a transport direction parallel to the sub-scanning direction. The plurality of ink heads include a first ink head that ejects a first ink and a second ink head that ejects a second ink that has a hue similar to the first ink and a higher brightness. A printing unit in which, among the plurality of ink head rows, the second ink head is located in a row downstream of the first ink head in the transport direction.

6. A carriage that moves back and forth in the main scanning direction, Multiple ink heads that eject ink, Equipped with, The plurality of ink heads are mounted on the carriage such that each of them extends along the main scanning direction and is arranged in a sub-scanning direction intersecting the main scanning direction, forming a plurality of ink head rows. The aforementioned plurality of ink heads include a plurality of sets of same-color ink heads, each consisting of a plurality of same-color ink heads that eject ink of the same color. In at least one of the plurality of identical color ink head sets, the plurality of identical color ink heads are arranged in one of the plurality of ink head rows and not in any other ink head row. The plurality of ink heads include a black ink head that ejects black ink and a yellow ink head that ejects yellow ink. The black ink head and the yellow ink head are located in different rows within the plurality of ink head rows and are not located in the same row. The plurality of ink heads eject ink onto a recording medium that is transported along a transport direction parallel to the sub-scanning direction. The plurality of ink heads include a first ink head that ejects a first ink and a second ink head that ejects a second ink that has a hue similar to the first ink and a higher brightness. A printing unit in which, among the plurality of ink head rows, the second ink head is located in a row downstream of the first ink head in the transport direction.

7. A carriage that moves back and forth in the main scanning direction, Multiple ink heads that eject ink, Equipped with, The plurality of ink heads are mounted on the carriage such that each of them extends along the main scanning direction and is arranged in a sub-scanning direction intersecting the main scanning direction, forming a plurality of ink head rows. The aforementioned plurality of ink heads include a plurality of sets of same-color ink heads, each consisting of a plurality of same-color ink heads that eject ink of the same color. In at least one of the plurality of identical color ink head sets, the plurality of identical color ink heads are arranged in one of the plurality of ink head rows and not in any other ink head row. The plurality of ink heads eject ink onto a recording medium that is transported along a transport direction parallel to the sub-scanning direction. Of the plurality of ink heads, the ink head that ejects the ink of the color closest to cyan in terms of hue is located in the downstream row of the plurality of ink head rows in the transport direction. The plurality of ink heads eject ink onto a recording medium that is transported along a transport direction parallel to the sub-scanning direction. The plurality of ink heads include a first ink head that ejects a first ink and a second ink head that ejects a second ink that has a hue similar to the first ink and a higher brightness. A printing unit in which, among the plurality of ink head rows, the second ink head is located in a row downstream of the first ink head in the transport direction.

8. A carriage that moves back and forth in the main scanning direction, Multiple ink heads that eject ink, Equipped with, The plurality of ink heads are mounted on the carriage such that each of them extends along the main scanning direction and is arranged in a sub-scanning direction intersecting the main scanning direction, forming a plurality of ink head rows. The aforementioned plurality of ink heads include a plurality of sets of same-color ink heads, each consisting of a plurality of same-color ink heads that eject ink of the same color. In at least one of the plurality of identical color ink head sets, the plurality of identical color ink heads are arranged in one of the plurality of ink head rows and not in any other ink head row. The plurality of ink heads eject ink onto a recording medium that is transported along a transport direction parallel to the sub-scanning direction. If the ink colors ejected by each of the aforementioned ink heads are arranged in order of their hue from closest to red, and half of the inks closest to red are designated as red-based inks and the remaining half as non-red-based inks, then more than half of the inks arranged in the upstream row of the aforementioned ink head rows in the transport direction are set to red-based inks. The plurality of ink heads eject ink onto a recording medium that is transported along a transport direction parallel to the sub-scanning direction. The plurality of ink heads include a first ink head that ejects a first ink and a second ink head that ejects a second ink that has a hue similar to the first ink and a higher brightness. A printing unit in which, among the plurality of ink head rows, the second ink head is located in a row downstream of the first ink head in the transport direction.

9. A carriage that moves back and forth in the main scanning direction, Multiple ink heads that eject ink, Equipped with, The plurality of ink heads are mounted on the carriage such that each of them forms a plurality of ink head rows, each extending along the main scanning direction and arranged in a sub-scanning direction intersecting the main scanning direction, and ejects ink onto a recording medium being transported along a transport direction parallel to the sub-scanning direction. The aforementioned plurality of ink heads include a plurality of sets of same-color ink heads, each consisting of a plurality of same-color ink heads that eject ink of the same color. In at least one of the plurality of identical color ink head sets, the plurality of identical color ink heads are arranged in one of the plurality of ink head rows and not in any other ink head row. The aforementioned set of multiple ink heads of the same color includes a set of black ink heads that ejects black ink. The aforementioned black ink head set is located in the downstream ink head row in the transport direction among the plurality of ink head rows, and is not located in the upstream ink head row in the transport direction. The plurality of identical ink heads of the black ink head set are arranged at both ends of the ink head row on the downstream side in the transport direction in the main scanning direction. The plurality of ink heads eject ink onto a recording medium that is transported along a transport direction parallel to the sub-scanning direction. A pre-treatment head is positioned upstream of the aforementioned multiple ink head rows in the transport direction and discharges a pre-treatment liquid, A post-processing head is positioned downstream of the aforementioned multiple ink head rows in the transport direction and discharges a post-processing liquid, Furthermore, The plurality of ink heads include a first ink head that ejects a first ink and a second ink head that ejects a second ink having a higher pigment content than the first ink. A printing unit in which, among the plurality of ink head rows, the second ink head is located in a row upstream of the first ink head in the transport direction.

10. A carriage that moves back and forth in the main scanning direction, Multiple ink heads that eject ink, Equipped with, The plurality of ink heads are mounted on the carriage such that each of them extends along the main scanning direction and is arranged in a sub-scanning direction intersecting the main scanning direction, forming a plurality of ink head rows. The aforementioned plurality of ink heads include a plurality of sets of same-color ink heads, each consisting of a plurality of same-color ink heads that eject ink of the same color. In at least one of the plurality of identical color ink head sets, the plurality of identical color ink heads are arranged in one of the plurality of ink head rows and not in any other ink head row. The plurality of ink heads include a black ink head that ejects black ink and a yellow ink head that ejects yellow ink. The black ink head and the yellow ink head are located in different rows within the plurality of ink head rows and are not located in the same row. The plurality of ink heads eject ink onto a recording medium that is transported along a transport direction parallel to the sub-scanning direction. A pre-treatment head is positioned upstream of the aforementioned multiple ink head rows in the transport direction and discharges a pre-treatment liquid, A post-processing head is positioned downstream of the aforementioned multiple ink head rows in the transport direction and discharges a post-processing liquid, Furthermore, The plurality of ink heads include a first ink head that ejects a first ink and a second ink head that ejects a second ink having a higher pigment content than the first ink. A printing unit in which, among the plurality of ink head rows, the second ink head is located in a row upstream of the first ink head in the transport direction.

11. A carriage that moves back and forth in the main scanning direction, Multiple ink heads that eject ink, Equipped with, The plurality of ink heads are mounted on the carriage such that each of them extends along the main scanning direction and is arranged in a sub-scanning direction intersecting the main scanning direction, forming a plurality of ink head rows. The aforementioned plurality of ink heads include a plurality of sets of same-color ink heads, each consisting of a plurality of same-color ink heads that eject ink of the same color. In at least one of the plurality of identical color ink head sets, the plurality of identical color ink heads are arranged in one of the plurality of ink head rows and not in any other ink head row. The plurality of ink heads eject ink onto a recording medium that is transported along a transport direction parallel to the sub-scanning direction. Of the plurality of ink heads, the ink head that ejects the ink of the color closest to cyan in terms of hue is located in the downstream row of the plurality of ink head rows in the transport direction. The plurality of ink heads eject ink onto a recording medium that is transported along a transport direction parallel to the sub-scanning direction. A pre-treatment head is positioned upstream of the aforementioned multiple ink head rows in the transport direction and discharges a pre-treatment liquid, A post-processing head is positioned downstream of the aforementioned multiple ink head rows in the transport direction and discharges a post-processing liquid, Furthermore, The plurality of ink heads include a first ink head that ejects a first ink and a second ink head that ejects a second ink having a higher pigment content than the first ink. A printing unit in which, among the plurality of ink head rows, the second ink head is located in a row upstream of the first ink head in the transport direction.

12. A carriage that moves back and forth in the main scanning direction, Multiple ink heads that eject ink, Equipped with, The plurality of ink heads are mounted on the carriage such that each of them extends along the main scanning direction and is arranged in a sub-scanning direction intersecting the main scanning direction, forming a plurality of ink head rows. The aforementioned plurality of ink heads include a plurality of sets of same-color ink heads, each consisting of a plurality of same-color ink heads that eject ink of the same color. In at least one of the plurality of identical color ink head sets, the plurality of identical color ink heads are arranged in one of the plurality of ink head rows and not in any other ink head row. The plurality of ink heads eject ink onto a recording medium that is transported along a transport direction parallel to the sub-scanning direction. If the ink colors ejected by each of the aforementioned ink heads are arranged in order of their hue from closest to red, and half of the inks closest to red are designated as red-based inks and the remaining half as non-red-based inks, then more than half of the inks arranged in the upstream row of the aforementioned ink head rows in the transport direction are set to red-based inks. The plurality of ink heads eject ink onto a recording medium that is transported along a transport direction parallel to the sub-scanning direction. A pre-treatment head is positioned upstream of the aforementioned multiple ink head rows in the transport direction and discharges a pre-treatment liquid, A post-processing head is positioned downstream of the aforementioned multiple ink head rows in the transport direction and discharges a post-processing liquid, Furthermore, The plurality of ink heads include a first ink head that ejects a first ink and a second ink head that ejects a second ink having a higher pigment content than the first ink. A printing unit in which, among the plurality of ink head rows, the second ink head is located in a row upstream of the first ink head in the transport direction.

13. A carriage that moves back and forth in the main scanning direction, Multiple ink heads that eject ink, Equipped with, The plurality of ink heads are mounted on the carriage such that each of them forms a plurality of ink head rows, each extending along the main scanning direction and arranged in a sub-scanning direction intersecting the main scanning direction, and ejects ink onto a recording medium being transported along a transport direction parallel to the sub-scanning direction. The aforementioned plurality of ink heads include a plurality of sets of same-color ink heads, each consisting of a plurality of same-color ink heads that eject ink of the same color. In at least one of the plurality of identical color ink head sets, the plurality of identical color ink heads are arranged in one of the plurality of ink head rows and not in any other ink head row. The aforementioned set of multiple ink heads of the same color includes a set of black ink heads that ejects black ink. The aforementioned black ink head set is located in the downstream ink head row in the transport direction among the plurality of ink head rows, and is not located in the upstream ink head row in the transport direction. The plurality of identical ink heads of the black ink head set are arranged at both ends of the ink head row on the downstream side in the transport direction in the main scanning direction. The plurality of ink heads eject ink onto a recording medium that is transported along a transport direction parallel to the sub-scanning direction. A pre-treatment head is positioned upstream of the aforementioned multiple ink head rows in the transport direction and discharges a pre-treatment liquid, A post-processing head is positioned downstream of the aforementioned multiple ink head rows in the transport direction and discharges a post-processing liquid, Furthermore, The plurality of ink heads include a first ink head that ejects a first ink and a second ink head that ejects a second ink having a higher binder content than the first ink. A printing unit in which, among the plurality of ink head rows, the second ink head is located in a row upstream of the first ink head in the transport direction.

14. A carriage that moves back and forth in the main scanning direction, Multiple ink heads that eject ink, Equipped with, The plurality of ink heads are mounted on the carriage such that each of them extends along the main scanning direction and is arranged in a sub-scanning direction intersecting the main scanning direction, forming a plurality of ink head rows. The aforementioned plurality of ink heads include a plurality of sets of same-color ink heads, each consisting of a plurality of same-color ink heads that eject ink of the same color. In at least one of the plurality of identical color ink head sets, the plurality of identical color ink heads are arranged in one of the plurality of ink head rows and not in any other ink head row. The plurality of ink heads include a black ink head that ejects black ink and a yellow ink head that ejects yellow ink. The black ink head and the yellow ink head are located in different rows within the plurality of ink head rows and are not located in the same row. The plurality of ink heads eject ink onto a recording medium that is transported along a transport direction parallel to the sub-scanning direction. A pre-treatment head is positioned upstream of the aforementioned multiple ink head rows in the transport direction and discharges a pre-treatment liquid, A post-processing head is positioned downstream of the aforementioned multiple ink head rows in the transport direction and discharges a post-processing liquid, Furthermore, The plurality of ink heads include a first ink head that ejects a first ink and a second ink head that ejects a second ink having a higher binder content than the first ink. A printing unit in which, among the plurality of ink head rows, the second ink head is located in a row upstream of the first ink head in the transport direction.

15. A carriage that moves back and forth in the main scanning direction, Multiple ink heads that eject ink, Equipped with, The plurality of ink heads are mounted on the carriage such that each of them extends along the main scanning direction and is arranged in a sub-scanning direction intersecting the main scanning direction, forming a plurality of ink head rows. The aforementioned plurality of ink heads include a plurality of sets of same-color ink heads, each consisting of a plurality of same-color ink heads that eject ink of the same color. In at least one of the plurality of identical color ink head sets, the plurality of identical color ink heads are arranged in one of the plurality of ink head rows and not in any other ink head row. The plurality of ink heads eject ink onto a recording medium that is transported along a transport direction parallel to the sub-scanning direction. Of the plurality of ink heads, the ink head that ejects the ink of the color closest to cyan in terms of hue is located in the downstream row of the plurality of ink head rows in the transport direction. The plurality of ink heads eject ink onto a recording medium that is transported along a transport direction parallel to the sub-scanning direction. A pre-treatment head is positioned upstream of the aforementioned multiple ink head rows in the transport direction and discharges a pre-treatment liquid, A post-processing head is positioned downstream of the aforementioned multiple ink head rows in the transport direction and discharges a post-processing liquid, Furthermore, The plurality of ink heads include a first ink head that ejects a first ink and a second ink head that ejects a second ink having a higher binder content than the first ink. A printing unit in which, among the plurality of ink head rows, the second ink head is located in a row upstream of the first ink head in the transport direction.

16. A carriage that moves back and forth in the main scanning direction, Multiple ink heads that eject ink, Equipped with, The plurality of ink heads are mounted on the carriage such that each of them extends along the main scanning direction and is arranged in a sub-scanning direction intersecting the main scanning direction, forming a plurality of ink head rows. The aforementioned plurality of ink heads include a plurality of sets of same-color ink heads, each consisting of a plurality of same-color ink heads that eject ink of the same color. In at least one of the plurality of identical color ink head sets, the plurality of identical color ink heads are arranged in one of the plurality of ink head rows and not in any other ink head row. The plurality of ink heads eject ink onto a recording medium that is transported along a transport direction parallel to the sub-scanning direction. If the ink colors ejected by each of the aforementioned ink heads are arranged in order of their hue from closest to red, and half of the inks closest to red are designated as red-based inks and the remaining half as non-red-based inks, then more than half of the inks arranged in the upstream row of the aforementioned ink head rows in the transport direction are set to red-based inks. The plurality of ink heads eject ink onto a recording medium that is transported along a transport direction parallel to the sub-scanning direction. A pre-treatment head is positioned upstream of the aforementioned multiple ink head rows in the transport direction and discharges a pre-treatment liquid, A post-processing head is positioned downstream of the aforementioned multiple ink head rows in the transport direction and discharges a post-processing liquid, Furthermore, The plurality of ink heads include a first ink head that ejects a first ink and a second ink head that ejects a second ink having a higher binder content than the first ink. A printing unit in which, among the plurality of ink head rows, the second ink head is located in a row upstream of the first ink head in the transport direction.

17. A carriage that moves back and forth in the main scanning direction, Multiple ink heads that eject ink, Equipped with, The plurality of ink heads are mounted on the carriage such that each of them forms a plurality of ink head rows, each extending along the main scanning direction and arranged in a sub-scanning direction intersecting the main scanning direction, and ejects ink onto a recording medium being transported along a transport direction parallel to the sub-scanning direction. The aforementioned plurality of ink heads include a plurality of sets of same-color ink heads, each consisting of a plurality of same-color ink heads that eject ink of the same color. In at least one of the plurality of identical color ink head sets, the plurality of identical color ink heads are arranged in one of the plurality of ink head rows and not in any other ink head row. The aforementioned set of multiple ink heads of the same color includes a set of black ink heads that ejects black ink. The aforementioned black ink head set is located in the downstream ink head row in the transport direction among the plurality of ink head rows, and is not located in the upstream ink head row in the transport direction. The plurality of identical ink heads of the black ink head set are arranged at both ends of the ink head row on the downstream side in the transport direction in the main scanning direction. The plurality of ink heads eject ink onto a recording medium that is transported along a transport direction parallel to the sub-scanning direction. The plurality of ink heads include a plurality of basic color ink heads that each eject ink of one of the basic colors of black, cyan, magenta, and yellow, and a plurality of non-basic color ink heads that each eject ink of a color other than the basic colors. A printing unit in which the basic color ink head is located in the downstream row in the transport direction among the plurality of ink head rows.

18. A carriage that moves back and forth in the main scanning direction, Multiple ink heads that eject ink, Equipped with, The plurality of ink heads are mounted on the carriage such that each of them extends along the main scanning direction and is arranged in a sub-scanning direction intersecting the main scanning direction, forming a plurality of ink head rows. The aforementioned plurality of ink heads include a plurality of sets of same-color ink heads, each consisting of a plurality of same-color ink heads that eject ink of the same color. In at least one of the plurality of identical color ink head sets, the plurality of identical color ink heads are arranged in one of the plurality of ink head rows and not in any other ink head row. The plurality of ink heads include a black ink head that ejects black ink and a yellow ink head that ejects yellow ink. The black ink head and the yellow ink head are located in different rows within the plurality of ink head rows and are not located in the same row. The plurality of ink heads eject ink onto a recording medium that is transported along a transport direction parallel to the sub-scanning direction. The plurality of ink heads include a plurality of basic color ink heads that each eject ink of one of the basic colors of black, cyan, magenta, and yellow, and a plurality of non-basic color ink heads that each eject ink of a color other than the basic colors. A printing unit in which the basic color ink head is located in the downstream row in the transport direction among the plurality of ink head rows.

19. A carriage that moves back and forth in the main scanning direction, Multiple ink heads that eject ink, Equipped with, The plurality of ink heads are mounted on the carriage such that each of them extends along the main scanning direction and is arranged in a sub-scanning direction intersecting the main scanning direction, forming a plurality of ink head rows. The aforementioned plurality of ink heads include a plurality of sets of same-color ink heads, each consisting of a plurality of same-color ink heads that eject ink of the same color. In at least one of the plurality of identical color ink head sets, the plurality of identical color ink heads are arranged in one of the plurality of ink head rows and not in any other ink head row. The plurality of ink heads eject ink onto a recording medium that is transported along a transport direction parallel to the sub-scanning direction. Of the plurality of ink heads, the ink head that ejects the ink of the color closest to cyan in terms of hue is located in the downstream row of the plurality of ink head rows in the transport direction. The plurality of ink heads eject ink onto a recording medium that is transported along a transport direction parallel to the sub-scanning direction. The plurality of ink heads include a plurality of basic color ink heads that each eject ink of one of the basic colors of black, cyan, magenta, and yellow, and a plurality of non-basic color ink heads that each eject ink of a color other than the basic colors. A printing unit in which the basic color ink head is located in the downstream row in the transport direction among the plurality of ink head rows.

20. A carriage that moves back and forth in the main scanning direction, Multiple ink heads that eject ink, Equipped with, The plurality of ink heads are mounted on the carriage such that each of them extends along the main scanning direction and is arranged in a sub-scanning direction intersecting the main scanning direction, forming a plurality of ink head rows. The aforementioned plurality of ink heads include a plurality of sets of same-color ink heads, each consisting of a plurality of same-color ink heads that eject ink of the same color. In at least one of the plurality of identical color ink head sets, the plurality of identical color ink heads are arranged in one of the plurality of ink head rows and not in any other ink head row. The plurality of ink heads eject ink onto a recording medium that is transported along a transport direction parallel to the sub-scanning direction. If the ink colors ejected by each of the aforementioned ink heads are arranged in order of their hue from closest to red, and half of the inks closest to red are designated as red-based inks and the remaining half as non-red-based inks, then more than half of the inks arranged in the upstream row of the aforementioned ink head rows in the transport direction are set to red-based inks. The plurality of ink heads eject ink onto a recording medium that is transported along a transport direction parallel to the sub-scanning direction. The plurality of ink heads include a plurality of basic color ink heads that each eject ink of one of the basic colors of black, cyan, magenta, and yellow, and a plurality of non-basic color ink heads that each eject ink of a color other than the basic colors. A printing unit in which the basic color ink head is located in the downstream row in the transport direction among the plurality of ink head rows.

21. A carriage that moves back and forth in the main scanning direction, Multiple ink heads that eject ink, Equipped with, The plurality of ink heads are mounted on the carriage such that each of them extends along the main scanning direction and is arranged in a sub-scanning direction intersecting the main scanning direction, forming a plurality of ink head rows. The aforementioned plurality of ink heads include a plurality of sets of same-color ink heads, each consisting of a plurality of same-color ink heads that eject ink of the same color. In at least one of the plurality of identical color ink head sets, the plurality of identical color ink heads are arranged in one of the plurality of ink head rows and not in any other ink head row. The plurality of ink heads eject ink onto a recording medium that is transported along a transport direction parallel to the sub-scanning direction. A printing unit in which, when the ink colors ejected by the multiple ink heads are arranged in order of their hue from closest to cyan, and half of the inks closest to cyan are designated as cyan-based inks and the other half as non-cyan-based inks, more than half of the inks located in the downstream row of the multiple ink head rows in the transport direction are set to cyan-based inks.

22. A printing unit according to any one of claims 1 to 21, A printing unit in which, in all of the aforementioned sets of identical color ink heads, the respective sets of identical color ink heads are arranged in one of the aforementioned rows of ink heads but not in any of the other rows.

23. A printing unit according to any one of claims 1 to 21, The plurality of ink heads eject ink onto a recording medium that is transported along a transport direction parallel to the sub-scanning direction. A printing unit in which, among the plurality of ink heads, the ink head that ejects the ink of the color closest to red in terms of hue is located in the upstream row of the plurality of ink head rows in the transport direction.

24. A printing unit according to any one of claims 5 to 8, The second ink head is located in the printing unit, with the plurality of ink heads positioned on the inside in the main scanning direction.

25. A printing unit according to any one of claims 1 to 8 or 13 to 21, The plurality of ink heads eject ink onto a recording medium that is transported along a transport direction parallel to the sub-scanning direction. The plurality of ink heads include a first ink head that ejects a first ink and a second ink head that ejects a second ink having a higher pigment content than the first ink. A printing unit in which, among the plurality of ink head rows, the second ink head is located in a row downstream of the first ink head in the transport direction.

26. A printing unit according to any one of claims 1 to 12 or 17 to 21, The plurality of ink heads eject ink onto a recording medium that is transported along a transport direction parallel to the sub-scanning direction. The plurality of ink heads include a first ink head that ejects a first ink and a second ink head that ejects a second ink having a higher binder content than the first ink. A printing unit in which, among the plurality of ink head rows, the second ink head is located in a row downstream of the first ink head in the transport direction.

27. A printing unit according to any one of claims 1 to 21, A printing unit in which the aforementioned multiple sets of identical ink heads are mounted on the carriage such that the colors of the ink ejected by each set are symmetrical in the main scanning direction.

28. A printing unit according to any one of claims 1 to 21, A transport unit that transports the recording medium along a transport direction parallel to the sub-scanning direction, A recording device equipped with the following features.

29. The printing unit according to claim 21, The plurality of ink heads eject ink onto a recording medium that is transported along a transport direction parallel to the sub-scanning direction. The aforementioned set of multiple ink heads of the same color includes a set of black ink heads that ejects black ink. The aforementioned black ink head set is located in the downstream ink head row in the transport direction among the plurality of ink head rows, and is not located in the upstream ink head row in the transport direction. A printing unit in which the plurality of identical ink heads of the black ink head set are arranged at both ends of the ink head row on the downstream side in the transport direction in the main scanning direction.

30. The printing unit according to claim 21, The plurality of ink heads include a black ink head that ejects black ink and a yellow ink head that ejects yellow ink. A printing unit in which the black ink head and the yellow ink head are located in different rows within the plurality of ink head rows and are not located in the same row.

31. The printing unit according to claim 21, The plurality of ink heads eject ink onto a recording medium that is transported along a transport direction parallel to the sub-scanning direction. A printing unit in which, among the plurality of ink heads, the ink head that ejects the ink of the color closest to cyan in terms of hue is located in the downstream row of the plurality of ink head rows in the transport direction.

32. The printing unit according to claim 21, The plurality of ink heads eject ink onto a recording medium that is transported along a transport direction parallel to the sub-scanning direction. A printing unit in which, when the ink colors ejected by the multiple ink heads are arranged in order of their hue from closest to red, and half of the inks closest to red are designated as red inks and the other half as non-red inks, more than half of the inks located in the upstream row in the transport direction of the multiple ink head rows are set to the red inks.

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