Inkjet recording device and inkjet recording method

Abstract

Depending on the print head configuration, the post-treatment solution may directly affect the pre-treatment solution, potentially resulting in a lighter ink color density. [Solution] The inkjet recording device comprises a transport unit, a carriage, one or more ink heads, a processing head, a pre-processing head, and a post-processing head. The transport unit transports the recording medium in a predetermined transport direction. The carriage moves back and forth in a main scanning direction intersecting the transport direction. The plurality of ink heads are mounted on the carriage and each ejects ink. The pre-processing head is positioned upstream of the plurality of ink heads in the transport direction and ejects a non-coloring pre-processing liquid. The post-processing head is positioned downstream of the plurality of ink heads in the transport direction and ejects a non-coloring post-processing liquid. The plurality of ink heads include a plurality of same-color ink heads arranged side by side in the transport direction and ejecting ink of the same color from each other.

Description

Technical Field

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

Background Art

[0002] An inkjet recording apparatus such as an inkjet printer includes an ink head that discharges ink for image formation toward a recording medium. For example, when the recording medium is a fibrous sheet such as a fabric or a knitted fabric or a plastic sheet, it may be necessary to apply a pretreatment liquid and a post-treatment liquid to the recording medium before and after discharging the ink toward the recording medium (for example, Patent Document 1). The pretreatment liquid is, for example, a treatment liquid for improving the fixability of the ink to the recording medium and the aggregability of the ink pigment. The post-treatment liquid is, for example, a treatment liquid for enhancing the fastness of the printed image. In this case, the inkjet recording apparatus is provided with a treatment head that discharges the pretreatment liquid and the post-treatment liquid in addition to the ink head.

[0003] When the recording medium is wide, the above-described ink head and each treatment head are mounted on a carriage that reciprocates in the main scanning direction. In the recording process, the recording medium is intermittently fed in a predetermined conveyance direction (sub-scanning direction), and the carriage is reciprocated in the main scanning direction while the recording medium is stopped. When the carriage moves, ink and treatment liquid are discharged from the ink head and each treatment head, respectively.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

[0005] An inkjet recording apparatus according to one aspect of the present disclosure comprises a transport unit, a carriage, one or more ink heads, a processing head, at least one pre-processing head, and at least one post-processing head. The transport unit transports a recording medium in a predetermined transport direction. The carriage moves back and forth in a main scanning direction intersecting the transport direction. The plurality of ink heads are mounted on the carriage and each ejects ink. The at least one pre-processing head is positioned upstream of the plurality of ink heads in the transport direction and ejects a non-coloring pre-processing liquid. The at least one post-processing head is positioned downstream of the plurality of ink heads in the transport direction and ejects a non-coloring post-processing liquid. The plurality of ink heads include a plurality of same-color ink heads arranged side by side in the transport direction and ejecting ink of the same color from each other. [Brief explanation of the drawing]

[0006] [Figure 1] Figure 1 is a perspective view showing the overall configuration of an inkjet recording apparatus according to the first embodiment of this 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 the serial printing method employed in the first embodiment of this 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 relative positions of the nozzles of the ink head and processing head shown in Figure 6. [Figure 8]Figure 8 is a block diagram of an inkjet recording apparatus according to the first embodiment of this disclosure. [Figure 9] Figure 9 is a schematic plan view showing the upstream and downstream ink heads in an inkjet recording apparatus according to the first embodiment of this disclosure. [Figure 10] Figure 10 is a schematic diagram illustrating the placement of ink and processing liquids on image dots near the head boundary in an inkjet recording apparatus according to the first embodiment of this disclosure. [Figure 11] Figure 11 is a schematic diagram illustrating the placement of ink and processing liquids on image dots near the head boundary in an inkjet recording apparatus according to the first embodiment of this disclosure. [Figure 12] Figure 12 is a schematic plan view showing the upstream and downstream ink heads in an inkjet recording apparatus according to a second embodiment of the present disclosure. [Figure 13] Figure 13 is a schematic plan view showing the arrangement of the ink head and processing head on the carriage in an inkjet recording apparatus according to the third embodiment of this disclosure. [Figure 14] Figure 14 is a schematic plan view showing the arrangement of the ink head and processing head on the carriage in an inkjet recording apparatus according to the fourth embodiment of this disclosure. [Figure 15] Figure 15 is a schematic plan view showing the arrangement of the ink head and processing head on the carriage in an inkjet recording apparatus according to the fifth embodiment of this disclosure. [Figure 16] Figure 16 is a schematic plan view showing the arrangement of the ink head and processing head on the carriage in an inkjet recording apparatus according to the sixth embodiment of this disclosure. [Figure 17] Figure 17 is a schematic plan view showing the arrangement of the ink head, processing head, and sub-tank on the carriage in an inkjet recording apparatus according to the sixth embodiment of the present disclosure. [Figure 18]Figure 18 is a schematic plan view showing the arrangement of ink heads and processing heads on a carriage in other inkjet recording devices compared to the embodiments of this disclosure. [Figure 19] Figure 19 is a schematic diagram illustrating the placement of ink and processing solutions on image dots near the head boundary in the inkjet recording device shown in Figure 18. [Figure 20] Figure 20 is a schematic diagram illustrating the placement of ink and processing solutions on image dots near the head boundary in the inkjet recording apparatus shown in Figure 18. [Figure 21] Figure 21 is a schematic plan view showing the arrangement of ink heads and processing heads on a carriage in other inkjet recording devices compared to the embodiments of this disclosure. [Modes for carrying out the invention]

[0007] Hereinafter, with reference to the drawings, inkjet recording devices according to each embodiment of the present disclosure will be described. In these embodiments, as a specific example of an inkjet recording device, an inkjet printer equipped with an ink head that ejects image-forming ink onto a wide and long recording medium is 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 inkjet recording device according to the present disclosure can also be used for printing various inkjet images onto recording media such as paper sheets and resin sheets.

[0008] [Overall configuration of an inkjet printer] FIG. 1 is a perspective view showing the overall configuration of an inkjet printer 1 according to the first embodiment of the present disclosure, and FIG. 2 is a schematic cross-sectional view taken along line II-II of FIG. 1. The inkjet printer 1 is a printer that prints an image on a wide and long workpiece W (recording medium) by an inkjet method, and includes a device frame 10, a workpiece conveyance unit 20 (conveyance unit) incorporated in the device frame 10, and a carriage 3. In the present embodiment, the left-right direction is the main scanning direction S (FIG. 3) during printing with respect to the workpiece W, and the direction from the rear to the front is the sub-scanning direction (the conveyance direction F of the workpiece W).

[0009] The device frame 10 forms a framework for mounting various component members of the inkjet printer 1. The workpiece conveyance unit 20 is a mechanism that intermittently feeds (conveys) the workpiece W so that the workpiece W advances in the conveyance direction F from the rear to the front in the printing area where the inkjet printing process is performed. The carriage 3 mounts 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) that intersects the conveyance direction F of the workpiece W during the inkjet printing process.

[0010] 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 component members of the inkjet printer 1 and has a left-right width corresponding to the workpiece conveyance unit 20. The right frame 112 and the left frame 113 are erected adjacent to the right and left of the central frame 111, respectively. The area between the right frame 112 and the left frame 113 is a printing area 12 where printing processing is performed on the workpiece W.

[0011] 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 executed. In the maintenance area 13, cleaning processes, purge processes, etc. of the nozzles (discharge holes) of the ink head 4, the pre-treatment head 5, and the post-treatment head 6 are performed, and a cap is fitted. The left frame 113 forms a turning area 14 of the carriage 3. The turning area 14 is an area where the carriage 3 that has mainly scanned the printing area 12 from right to left in the printing process temporarily enters when performing a reverse main scan.

[0012] Above the device frame 10, a carriage guide 15 for causing the carriage 3 to reciprocate in the left - right direction is assembled. The carriage guide 15 is a flat plate - shaped member that is long in the left - right direction and is disposed above the work conveyance unit 20. A timing belt 16 (moving member) is assembled to the carriage guide 15 so as to be able to rotate in the left - right direction (main scanning direction). The timing belt 16 is an endless belt and is driven by a carriage drive unit 3S described later to rotate in the left direction or the right direction.

[0013] The carriage guide 15 is equipped with a pair of upper and lower guide rails 17 (holding members) that hold the carriage 3 in a state where it can reciprocate in the main scanning direction S and extend parallel to each other in the left - right direction. The carriage 3 is engaged with the guide rails 17. Also, the carriage 3 is fixed to the timing belt 16. The carriage 3 moves in the left direction or the right direction along the carriage guide 15 while being guided by the guide rails 17 as the timing belt 16 rotates in the left direction or the right direction.

[0014] 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.

[0015] The path between the feed roller 21 and the take-up roller 22, passing through the printing area 12, serves as the transport path for the workpiece W. Along this transport path, the first tension roller 23, workpiece guide 24, transport roller 25 and pinch roller 26, return roller 27, and second tension roller 28 are arranged in order from upstream. The first tension roller 23 applies a predetermined tension to the workpiece W upstream of the transport roller 25. The workpiece guide 24 changes the transport direction of the workpiece W from upward to forward, bringing the workpiece W into the printing area 12.

[0016] The transport roller 25 is a roller that generates a transport force to intermittently feed the workpiece W in the printing area 12. The transport roller 25 is rotationally driven around its axis by the second motor M2 and intermittently transports the workpiece W forward (in a predetermined transport direction F) so that the workpiece W passes through the printing area 12 (image formation position) facing the carriage 3. The pinch roller 26 is positioned to face the transport roller 25 from above and forms a transport nip section with the transport roller 25.

[0017] The folding roller 27 changes the transport direction of the workpiece W that has passed through the printing area 12 from forward to downward, guiding the printed workpiece W to the winding 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 positioned below the transport path of the workpiece W in the printing area 12.

[0018] The carriage 3 is cantilevered on the guide rail 17 and moves back and forth in the main scanning direction S (left-right in this embodiment) which 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 mounted on the carriage frame 30. The carriage frame 30 includes a head support frame 31 and a back frame 32 (engaging portion).

[0019] The head support frame 31 is a horizontal plate that holds the heads 4 to 6 shown 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 also engaged with the back frame 32. In other words, in this embodiment, the back frame 32 is an engaging portion that holds the guide rail 17 in a cantilevered manner. The head support frame 31 is a horizontal plate whose rear end is cantilevered to the guide rail 17 by the engaging portion.

[0020] The cantilever configuration refers to a state in the carriage 3 where the engaging portion (back frame 32) is located on only one side of the carriage 3 in the transport direction F, either upstream or downstream from the center, and no other engaging portion is present on the opposite side of the engaging portion. The engaging portion is the part held by the guide rail 17, which is a holding member. The engaging portion may also be located outside the area where the ink head 4 and the processing head are located in the transport direction F. That is, the engaging portion may be located only upstream or only downstream of the area where the ink head 4 and the processing head are located in the transport direction F.

[0021] [Carriage Details] Further explanation of carriage 3 is provided. Figure 3 is an enlarged perspective view of carriage 3 shown in Figure 1. Figure 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 carriage 3. Figure 3 shows an example in which multiple ink heads 4 that eject image-forming ink onto the workpiece W, pre-processing heads 5 and post-processing heads 6 that eject non-coloring processing liquid, and multiple sub-tanks 7 that supply the ink and processing liquid to these heads 4 to 6 are mounted on carriage 3.

[0022] Each of the ink heads 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 an ink passage that guides the ink to these nozzles. As the ink, for example, an aqueous pigment ink containing an aqueous solvent, a pigment, and a binder resin can be used. The plurality of ink heads 4 in this embodiment include first to sixth ink heads 4A to 4F, each ejecting six different colors of ink. For example, the first ink head 4A ejects orange ink, the second ink head 4B ejects green ink, the third ink head 4C ejects yellow ink, the fourth ink head 4D ejects red ink, the fifth ink head 4E ejects blue ink, and the sixth ink head 4F ejects black ink.

[0023] Each ink head 4A to 4F of a different color is mounted on the head support frame 31 of the carriage 3 so as to be aligned in the main scanning direction S. Each ink head 4A to 4F of a different color has two heads. For example, the first ink head 4A consists of an upstream ink head 4A1 positioned upstream in the transport direction F, and a downstream ink head 4A2 positioned downstream of the upstream ink head 4A1 and shifted to the left in the main scanning direction S. The same applies to the ink heads 4B to 4F of the other colors. Each of the upstream ink heads 4B to 4F of these ink heads 4B to 4F is aligned in a line in the main scanning direction S at the same position in the transport direction F as the upstream ink head 4A1, and each downstream ink head is aligned in a line in the main scanning direction S at the same position in the transport direction F as the downstream ink head 4A2. In this embodiment, each line of ink heads 4 contains one of each color's ink head 4A to 4F, but there may be two or more ink heads 4 of the same color in a line.

[0024] In the following explanation, two ink heads arranged side-by-side in the transport direction for each color (ink heads 4A-4F) may be referred to as "same-color ink heads." Furthermore, each set of ink heads 4A-4F may be referred to as a single pair of same-color ink heads, while the ink heads 4A-4F as a whole may be referred to as multiple sets of same-color ink heads. These multiple sets of same-color ink heads are arranged side-by-side in the main scanning direction S and each ejects ink of a different color.

[0025] 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 right 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 provided with at least one pre-processing head 5 and at least one post-processing head 6.

[0026] As used in the above explanation, a sequence of heads along the main scanning direction S, consisting of the ink head 4 and the 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, the pre-processing head 5, and the post-processing head 6, is referred to as a line of heads, or simply a line.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] An opening 31H (Figure 3) is provided in the head support frame 31 where the print heads are positioned. The ink heads 4A to 4F, the pre-processing head 5, and the 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.

[0033] 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 containing ink and processing fluid (not shown). Each sub-tank 7 supplies the ink or processing fluid to each of the heads 4, 5, and 6. Each sub-tank 7 and the heads 4, 5, and 6 are connected by conduits (not shown in Figure 3) (P1, P2, P3 shown in Figure 17).

[0034] 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.

[0035] [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.

[0036] 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 for each head and the printing width Pw are depicted as approximately equal. In reality, the length of the transport direction F for 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] Figure 6 is a schematic plan view showing the head arrangement on the carriage 3 according to this embodiment, and also shows the arrangement of the ink head 4, pre-processing head 5, and post-processing head 6 (multiple processing heads) on the carriage 3 shown in Figure 3. As mentioned above, the carriage 3 is cantilevered by the guide rail 17 at the back frame 32 (engaging part). 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 on which the back frame 32 is located is called the base end side 311, and the side of the head support frame 31 opposite the base end side 311 is called the tip end side 312. As previously described, the head support frame 31 of the carriage 3 is equipped with the first to sixth ink heads 4A to 4F, a pre-processing head 5, and a post-processing head 6, each ejecting six different colored inks. Each of the ink heads 4A to 4F of each color has two unit heads (12 in total). The system is equipped with one pre-processing head 5 and one post-processing head 6.

[0048] The group of first to sixth ink heads 4A to 4F that constitute the ink head 4 are arranged in the central region of the head support frame 31 in the transport direction F so as to be aligned in the main scanning direction S. The pre-processing head 5 is located near the right end of the carriage 3 in the main scanning direction S, upstream of the ink head 4 in the transport direction F, and at the base end side 311 of the head support frame 31. On the other hand, the post-processing head 6 is located at the right end of the carriage 3 in the main scanning direction S, downstream of the ink head 4 in the transport direction F, and at the tip side 312 of the head support frame 31.

[0049] The first ink head 4A includes an upstream ink head 4A1 and a downstream ink head 4A2 positioned downstream of the upstream ink head 4A1. In other words, the upstream ink head 4A1 and the downstream ink head 4A2 are arranged in the transport direction F. The upstream ink head 4A1 is positioned near the base end 311 in the central region of the head support frame 31. The downstream ink head 4A2 is positioned near the tip end 312 in the central region of the head support frame 31. The downstream ink head 4A2 is positioned at a different location from the upstream ink head 4A1, shifted to one side (left) of the main scanning direction S, and partially overlapping in the transport direction F. That is, in this embodiment, multiple ink heads of the same color are positioned at different locations in the main scanning direction S, and partially overlapping in the transport direction F. If three or more ink heads of the same color are arranged in the transport direction F, two ink heads of the same color arranged adjacent to each other in the transport direction F are arranged as described above. Of course, the upstream ink head 4A1 and the downstream ink head 4A2 may also be arranged at 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.

[0050] Furthermore, by arranging them in this way, the ink heads 4 that eject a single color are grouped together in the main scanning direction S. Specifically, all the ink heads 4 that eject a single color mounted on the carriage 3 are arranged so that no ink heads 4 that eject other colors are placed between them in the main scanning direction S. In addition, all the ink heads 4 that eject a single color mounted on the carriage 3 may be placed within a predetermined range, and no ink heads 4 that eject other colors may be placed within that range.

[0051] If there are differences in printing conditions, such as the point of impact or the amount of ink ejected, between two ink heads 4, these differences are more likely to be noticeable when the two ink heads 4 are ejecting the same color than when they are ejecting different colors. If ink heads 4 that eject the same color are arranged together in the main scanning direction S, even if there are differences in printing conditions between the ink heads 4, the image quality of the print can be less likely to deteriorate.

[0052] The second to sixth ink heads 4B to 4F are also equipped with upstream ink heads 4B1, 4C1, 4D1, 4E1, and 4F1, and downstream ink heads 4B2, 4C2, 4D2, 4E2, and 4F2, similar to the upstream ink head 4A1 and downstream ink head 4A2 described above. The upstream ink heads 4A1 to 4F1 of the first to sixth ink heads 4A to 4F1 are arranged in a line at the same position in the transport direction F, with predetermined intervals in the main scanning direction S. Similarly, the downstream ink heads 4A2 to 4F2 are also arranged in a line at the same position in the transport direction F, with predetermined intervals in the main scanning direction S. As a result, a staggered arrangement is formed, with some of the downstream ink heads 4A2 to 4F2 fitting between each arrangement pitch of the upstream ink heads 4A1 to 4F1.

[0053] The pre-processing head 5 is positioned such that a portion of it is located between a pair of adjacent ink heads in the main scanning direction S. Specifically, the downstream portion of the pre-processing head 5 is located between the upstream ink head 4E1 of the fifth ink head 4E and the upstream ink head 4F1 of the sixth ink head 4F. Furthermore, the pre-processing head 5 is located at the same position as the downstream ink head 4F2 of the sixth ink head 4F in the main scanning direction S.

[0054] The post-processing head 6 is positioned such that its upstream portion fits into the right side of the downstream ink head 4F2 of the sixth ink head 4F, and is positioned at the same location as the upstream ink head 4F1 in the main scanning direction S. With this arrangement, the post-processing head 6 has an overlapping region fa with the downstream ink head 4F2 in the transport direction F. In the transport direction F, the width of each head is greater than the print width Pw and the width of the nozzle placement area. For this reason, each head is positioned to have an overlapping region fa so that there is no gap between the print range Pw of the head in each row and the print range Pw of the head in the adjacent row.

[0055] 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.

[0056] As a result of the above-described head arrangement, the pre-processing head 5 and the post-processing head 6 are positioned within the arrangement width H of the ink head 4 in the main scanning direction S. The ink head 4 has an arrangement width H in the main scanning direction S, between the downstream ink head 4A2 of the first ink head 4A and the upstream ink head 4F1 of the sixth ink head 4F. The pre-processing head 5 is positioned within the arrangement width H on the upstream side of the ink head 4, and the post-processing head 6 is positioned within the arrangement width H on the downstream side of the ink head 4.

[0057] Figure 7 is a schematic plan view showing the positional relationship of the nozzles of the ink head and processing head shown in Figure 6. In Figure 7, the area where the nozzles that discharge liquid during printing are located on the underside of each head is schematically illustrated inside the external shape of each head. The downstream ink heads (4A2 to 4F2) of the first ink head 4A to the sixth ink head 4F are positioned closest to the post-processing head 6 in the transport direction F among the ink heads of each color. On the other hand, the upstream ink heads (4A1 to 4F1) of the first ink head 4A to the sixth ink head 4F are positioned between the pre-processing head 5 and the downstream ink heads (4A2 to 4F2) in the transport direction F.

[0058] Furthermore, the upstream and downstream ends of the nozzle arrangement area of ​​the upstream ink heads (4A1 to 4F1) of the first to sixth ink heads 4A to 4F are positioned at the same location in the transport direction F. Similarly, the upstream and downstream ends of the nozzle arrangement area of ​​the downstream ink heads (4A2 to 4F2) of the first to sixth ink heads 4A to 4F are positioned at the same location in the transport direction F. In addition, the upstream end of the nozzle arrangement area of ​​the upstream ink heads (4A1 to 4F1) is positioned continuously with respect to the downstream end of the nozzle arrangement area of ​​the pre-processing head 5 in the transport direction F (they are touching, adjacent). Also, the upstream end of the nozzle arrangement area of ​​the downstream ink heads (4A2 to 4F2) is positioned continuously with respect to the downstream end of the nozzle arrangement area of ​​the upstream ink heads (4A1 to 4F1) in the transport direction F. Furthermore, the upstream end of the nozzle arrangement area of ​​the post-processing head 6 in the transport direction F is continuously arranged in the transport direction F with respect to the downstream end of the nozzle arrangement area of ​​the downstream ink heads (4A2~4F2) in the transport direction F.

[0059] Thus, the nozzles for dispensing ink and each processing liquid are arranged so that the ink and each processing liquid land adjacent to each other in units of resolution. Therefore, the landing area of ​​the pre-processing liquid and the landing area of ​​the ink from the upstream ink heads (4A1~4F1) are continuous (adjacent) at the pre-processing / ink head boundary line L1, the landing area of ​​the ink from the upstream ink heads (4A1~4F1) and the landing area of ​​the ink from the downstream ink heads (4A2~4F2) are continuous at the ink head boundary line L2, and the landing area of ​​the ink from the downstream ink heads (4A2~4F2) and the landing area of ​​the post-processing liquid are continuous at the ink / post-processing head boundary line L3. The same applies to the subsequent embodiments.

[0060] Figure 8 is a block diagram of the inkjet printer 1 according to this embodiment. The inkjet printer 1 further comprises a control unit 90 that comprehensively controls the operation of each part of the inkjet printer 1, a carriage drive unit 3S, an I / F 91, and an image memory 92. The control unit 90 consists of a CPU (Central Processing Unit), a ROM (Read Only Memory) that stores the control program, a RAM (Random Access Memory) used as the CPU's work area, etc. In addition to the aforementioned first motor M1 and second motor M2, ink head 4, pre-processing head 5 and post-processing head 6, the control unit 90 is electrically connected to the carriage drive unit 3S, I / F 91, image memory 92, etc. The carriage drive unit 3S includes a motor (not shown) that rotates a timing belt 16 to move the carriage 3 back and forth along the main scanning direction S.

[0061] The image memory 92 temporarily stores print image data provided by an external device, such as a personal computer.

[0062] I / F91 is an interface circuit for enabling data communication with external devices. For example, it creates communication signals according to the communication protocol of a network connecting the inkjet printer 1 and the external device, and converts the communication signals from the network into data in a format that the inkjet printer 1 can process. Print instruction signals transmitted from a personal computer or the like are provided to the control unit 90 via I / F91, and image data is stored in the image memory 92 via I / F91.

[0063] The control unit 90 functions by having the CPU execute a control program stored in ROM, thereby comprising a drive control unit 901, a discharge control unit 902, a discharge pattern designation unit 903 (discharge head designation unit), and a storage unit 904.

[0064] The drive control unit 901 controls the transport operation of the workpiece W by controlling the first motor M1 and the second motor M2 of the workpiece transport unit 20. The drive control unit 901 also controls the reciprocating movement of the carriage 3 along the main scanning direction S by controlling the carriage drive unit 3S.

[0065] The ejection control unit 902 inputs predetermined command signals to the ink head 4, pre-treatment head 5, and post-treatment head 6, and controls the ejection timing of each color of ink, pre-treatment liquid, and post-treatment liquid.

[0066] The discharge pattern specification unit 903 specifies the heads 4, 5, and 6 to be discharged according to the image information received from the I / F 91 or the image memory 92. More specifically, when there are multiple discharge patterns (ratios of discharge amounts of each liquid) from the heads 4, 5, and 6 that can record an image corresponding to the image information (for example, multiple are stored in the storage unit 904), the unit specifies the discharge pattern to be used for recording from among them. Specifically, the discharge pattern is information that specifies how much liquid should be discharged from each head 4, 5, and 6 when there are multiple heads 4, 5, and 6 that discharge the same liquid. Discharge pattern information is called discharge pattern information.

[0067] Next, we will explain the case in which the ejection pattern specification unit 903 specifies the ink ejection pattern. In order to land the ink at a predetermined position on the workpiece W, the ejection ink head is selected from among a plurality of ink heads of the same color, which is the ink head that ejects the ink. More specifically, the ejection pattern specification unit 903 specifies the ratio of ejection amount (ejection pattern) of the upstream ink heads (4A1~4F1) and downstream ink heads (4A2~4F2) among the ink heads 4 of each color, and inputs a signal corresponding to that ratio to the ejection control unit 902. Figure 9 is a schematic plan view showing the upstream ink heads (4A1~4F1) and downstream ink heads (4A2~4F2) in the inkjet printer 1 according to this embodiment. Figure 9 is an enlarged plan view of the area around the upstream ink head 4F1 and downstream ink head 4F2 of the sixth ink head 4F, which ejects black ink, among the ink heads 4 capable of ejecting multiple colors of ink. In the following explanation, as shown in Figure 9, the upstream ink head may be referred to as H1 and the downstream ink head as H2, regardless of the ink color.

[0068] Furthermore, regarding the upstream ink head H1 and the downstream ink head H2, the upstream ink head H1 is an ink head whose nozzle arrangement area, when viewed along the main scanning direction S, is neither connected to nor overlapping with the nozzle arrangement area of ​​the post-processing head 6. On the other hand, the downstream ink head H2 is an ink head whose nozzle arrangement area, when viewed along the main scanning direction S, is connected to or overlapping with the nozzle arrangement area of ​​the post-processing head 6. As described later, multiple upstream ink heads H1 may be arranged side by side in the transport direction F. That is, each color ink head 4 may have three or more ink heads of the same color along the transport direction F.

[0069] The storage unit 904 pre-stores various thresholds, parameters, etc., that are referenced by the drive control unit 901, the ejection control unit 902, and the ejection pattern specification unit 903. The storage unit 904 also stores information (ejection pattern information) that combines the number of ink heads capable of printing a predetermined pixel in an image formed on the workpiece W at a specified density with the ink ejection amount of each ink head. The storage unit 904 has multiple ejection pattern information stored, each corresponding to at least one density. If there are multiple printable pixel densities, there may be densities for which no corresponding ejection pattern information is stored.

[0070] The multiple ejection pattern information stored in advance for each density includes, for example, ejection pattern information for ejection from 2 (n) ink heads and ejection pattern information for ejection from 1 (n-1) or fewer ink heads. In other words, the storage unit 904 stores in advance the information for ejecting ink from different numbers of ink heads when forming an image of a predetermined pixel at a predetermined density. In this embodiment, since two ink heads 4 are arranged for each ink color, two types of ejection patterns are stored as the information: an ink ejection pattern by the upstream ink head H1 and the downstream ink head H2 (first ejection pattern, first ejection pattern information), and an ink ejection pattern by the upstream ink head H1 only (second ejection pattern, second ejection pattern information). These pattern information are selectively referenced by the ejection pattern designation unit 903.

[0071] As the first ejection pattern, multiple ejection patterns may be stored in which the ratio of the ink volume from the upstream ink head H1 to the ink volume from the downstream ink head H2 is different. Also, as drive signals that drive the ejection elements of heads 4, 5, and 6, there may be multiple different drive signals that eject the same amount of liquid. If information on the type of drive signal is also stored as part of the ejection pattern, multiple ejection patterns may be stored as both the first and second ejection patterns.

[0072] Furthermore, the aforementioned information may include the ink ejection pattern (third ejection pattern, third ejection pattern information) produced only by the downstream ink head H2. As described below, using the first or second ejection pattern instead of the third ejection pattern can make it less likely to cause a degradation in image quality.

[0073] <Challenges in head placement> Figure 18 is a schematic plan view showing the arrangement of ink heads and processing heads on a carriage in other inkjet recording devices compared to the embodiments of this disclosure. In this inkjet recording device, the first ink heads 4A to the sixth ink heads 4F, which eject ink of each color, are arranged in a line along the main scanning direction S. The pre-processing head 5 is adjacent to the sixth ink head 4F in the main scanning direction S and is located upstream of the sixth ink head 4F in the transport direction. Furthermore, the post-processing head 6 is adjacent to the sixth ink head 4F in the main scanning direction S and is located downstream of the sixth ink head 4F in the transport direction. The pre-processing head 5 and the post-processing head 6 are located in the same position in the main scanning direction S. In these ink heads and processing heads as well, the nozzles are arranged continuously in the transport direction F, similar to Figure 7. As shown in Figure 18, when the ink head 4 and the post-processing head 6 are positioned next to each other in the transport direction F, printing occurs as the carriage 3 moves in a specific direction in the main scanning direction S (i.e., always in the case of bidirectional printing). At the boundary between the heads in the transport direction F, the post-processing solution may directly affect the pre-processing solution, potentially resulting in a reduction in ink density. This phenomenon is described in detail below.

[0074] Figures 19 and 20 are schematic diagrams illustrating the impact of ink and processing solutions on image dots near the head boundary in the inkjet recording apparatus shown in Figure 18. In Figures 19 and 20, △ represents pre-processing solution 5M ejected from pre-processing head 5, ○ represents ink 4M ejected from ink head 4, and ◇ represents post-processing solution 6M ejected from post-processing head 6. Note that the solutions (4M, 5M, and 6M) depicted overlapping in each figure actually impact the same location, and are drawn slightly offset in the main scanning direction S for illustrative purposes.

[0075] Part A of Figure 19 (and part A of Figure 20) shows how a predetermined pixel boundary line L on the workpiece W is located at the boundary LA between the pre-processing head 5 and the ink head 4 in Figure 18. Downstream of the pixel boundary line L in the transport direction F, the ink 4M lands on top of the pre-processing liquid 5M that has already landed. On the other hand, upstream of the pixel boundary line L in the transport direction F, the pre-processing liquid 5M lands as the carriage 3 moves in the main scanning direction S, just as the ink 4M lands downstream. In other words, this pixel boundary line L is the boundary of the main scan, which is the boundary of pixels in the main scan where the timing of the landing of each liquid is different.

[0076] As the workpiece W is intermittently transported in the transport direction F from the state shown in part A of Figure 19, the aforementioned pixel boundary line L is positioned at the boundary line LB between the ink head 4 and the post-processing head 6 in Figure 18. Here, as the carriage 3 moves in the return direction SB (Figure 18), ink 4M and post-processing liquid 6M are ejected and land. As shown in Figure 18, the post-processing head 6 is positioned on the leading edge side of the return direction SB relative to the ink head 4. Therefore, as shown in part B of Figure 19, the post-processing liquid 6M first lands downstream of the pixel boundary line L in the transport direction F. At this time, as indicated by the arrows, some of the post-processing liquid 6M may flow upstream of the pixel boundary line L in the transport direction F due to misalignment or bleeding of the landing. Subsequently, as the carriage 3 moves in the same return direction SB, ink 4M lands upstream of the pixel boundary line L in the transport direction F (part C of Figure 19). At this time, as described above, the color density of ink 4M decreases due to the influence of the post-treatment solution 6M that flows in (Phenomenon 1: 4MA in section C of Figure 19).

[0077] This decrease in color intensity is presumed to occur as follows: Normally, when pretreatment solution 5M and ink 4M are mixed, the aggregation of pigments in ink 4M occurs in a very short time. However, it takes some time for the pigments to adhere to the fibers of the workpiece W. Therefore, if the flow of liquid penetrating into the fibers of the workpiece W increases during the time between the impact of ink 4M and its adhesion, the proportion of pigment drawn deeper into the workpiece W increases, and the amount of pigment remaining near the surface of the workpiece W decreases, resulting in a lighter color. Note that the impact of pretreatment solution 5M occurs during the scan before the impact of ink 4M. Also, the penetration of pretreatment solution 5M is strongest immediately after impact, so it is usually somewhat weakened by the time of ink 4M impact. However, if the flow of penetration increases due to shifting or bleeding of posttreatment solution 6M that has impacted adjacent to ink 4M in the same scan, the color is likely to become lighter as described above.

[0078] To explain this phenomenon using Figure 19, when the post-treatment solution 6M bleeds or misaligns in impact as described above, and the post-treatment solution 6M acts on the impacted area of ​​the adjacent pre-treatment solution 5M, a mixture of pre-treatment solution 5M and post-treatment solution 6M is created, which then penetrates deep into the workpiece W (cloth, paper). In particular, because the time interval between the transition from part B in Figure 19 to part C in Figure 19 within the same scan is short, the ink 4M in part C of Figure 19 lands before this mixture flow subsides. Consequently, the proportion of pigment that penetrates deep into the workpiece W increases within the impacted ink 4M, resulting in a lighter color on the workpiece W. Furthermore, the post-treatment solution 6M lowers the concentration of the pre-treatment solution 5M, preventing sufficient aggregation of the pigment in the subsequently impacted ink 4M, similarly resulting in a lighter color. This phenomenon is more pronounced when the ink contains pigments, but it can also occur when it contains dyes. Therefore, here, the concept including both pigments and dyes is expressed as "pigment."

[0079] Furthermore, in section C of Figure 19, if some of the ink 4M (4MA) that landed upstream of the pixel boundary line L in the transport direction F flows downstream of the pixel boundary line L in the transport direction F as indicated by the arrow, it may act on the already landed post-processing solution 6M, causing a slight change in image density (Phenomenon 2).

[0080] On the other hand, after part A in Figure 20 (the same as part A in Figure 19), when ink 4M and post-processing liquid 6M are ejected and land as the carriage 3 moves in the forward direction SA (Figure 18), as shown in Figure 18, the ink head 4 is positioned on the leading edge side of the forward direction SA relative to the post-processing head 6. Therefore, as shown in part B in Figure 20, the ink 4M first lands upstream of the pixel boundary line L in the transport direction F (note that the ink 4M downstream of the pixel boundary line L in the transport direction F within part B of Figure 20 was landed in the previous scan (part A in Figure 20)). At this time, as indicated by the arrow in part B of Figure 20, some of the ink 4M may flow downstream of the pixel boundary line L in the transport direction F due to misalignment or bleeding of the ink (Phenomenon 3).

[0081] Subsequently, during the movement of carriage 3 in the same forward direction SA, as shown in section C of Figure 20, if the post-processing solution 6M lands downstream of the pixel boundary line L in the transport direction F, some of it may flow upstream of the pixel boundary line L in the transport direction F due to misalignment or blurring of the post-processing solution 6M (Phenomenon 4). In phenomena 2, 3, and 4 described above, the post-processing solution 6M does not directly act on the pre-processing solution 5M as in phenomenon 1, so the problem of image density change is smaller compared to phenomenon 1.

[0082] To solve the problems arising from the phenomena described above, in this embodiment, the ink head 4, pre-processing head 5, and post-processing head 6 are suitably arranged on the carriage 3, and the control unit 90 suitably controls the ink ejection pattern from the ink head 4.

[0083] In other words, in this embodiment, as shown in Figures 6 and 7, multiple rows of ink heads 4 are arranged in the transport direction F, and ink of the same color can be ejected during scanning of different carriages 3. In particular, the nozzle arrangement area of ​​the upstream ink head 4 is spaced apart in the transport direction F from the nozzle arrangement area of ​​the post-processing head 6, so that ink 4M can be ejected onto the workpiece W in a scan prior to the scan in which the post-processing liquid 6M is ejected from the post-processing head 6. Therefore, as shown in part B of Figure 19, when ink 4M does not land immediately upstream of the pixel boundary line L, the post-processing liquid 6M does not land immediately downstream of the pixel boundary line L, making it less likely for a decrease in image density (4MA) to occur in part C of Figure 19. Note that the ink heads 4 are not limited to two rows, but may be arranged in three or more rows.

[0084] Figure 10 is a schematic diagram illustrating the placement of ink and processing liquids on image dots (pixels) near the head boundary in the inkjet printer 1 according to this embodiment. In this embodiment, when recording dense pixels on the workpiece W, the ejection pattern specification unit 903 (Figure 8) selects a pattern from the ejection patterns stored in the storage unit 904 in which ink 4M is ejected by both the first and second row ink heads 4 (upstream ink head H1, downstream ink head H2), and inputs this information to the ejection control unit 902.

[0085] As a result, in the situation corresponding to part B in Figure 19, as shown in part A in Figure 10, ink 4M has already landed in the upstream portion of the transport direction F from the pixel boundary line L in the previous scan. Therefore, it becomes less likely that the post-processing solution 6M will directly affect the pre-processing solution 5M, and the possibility of the aforementioned decrease in image density can be reduced. In this way, by arranging the ink heads 4 in two rows, the influence of the post-processing solution 6M can be reduced even if there are high-density pixels that require printing by two ink heads.

[0086] Furthermore, when recording pixels with a lower density than the aforementioned high-density pixels on the workpiece W, the ejection pattern specification unit 903 selects from the ejection patterns stored in the storage unit 904 either a pattern in which ink 4M is ejected by both the first and second row ink heads 4 (first ejection pattern), or a pattern in which ink 4M is ejected by only the first row ink head 4 (second ejection pattern), and inputs this information to the ejection control unit 902.

[0087] In any ejection pattern, the total amount of ink ejected to lighter pixels is less than the total amount of ink ejected to darker pixels. For example, if the density of a lighter pixel is half that of a darker pixel, the total amount of ink ejected to the lighter pixels will be approximately half the total amount of ink ejected to the darker pixels. In this case, if the first ejection pattern is used, the amount of ink ejected from each of the two ink heads 4 will be approximately halved. If the second ejection pattern is used, the amount of ink ejected from each of the ink heads 4 will be approximately the same, and the total amount of ink will be approximately halved by halving the number of ink heads 4 that eject.

[0088] When ink 4M is ejected by both the first and second row ink heads 4, the possibility of image density degradation can be reduced, similar to the high density case described above (part A in Figure 10). Also, when ink 4M is ejected by only the first row ink head 4, as shown in part B of Figure 10, ink 4M has already landed in the upstream portion of the transport direction F from the pixel boundary line L in the previous scan. Therefore, it is less likely that the post-processing solution 6M will directly act on the pre-processing solution 5M, and similarly, the possibility of image density degradation can be reduced.

[0089] The above describes examples of dark and light pixels, but one or both of these may be used. If ink 4M is ejected only by the second row of ink heads 4, as shown in section C of Figure 10, the misaligned or smeared post-treatment liquid 6M may directly affect the pre-treatment liquid 5M. Therefore, it is desirable to use the ejection pattern described above for both.

[0090] Furthermore, when ink 4M is ejected by both the first and second row ink heads 4, drying of the nozzles of the second row ink head 4 is less likely to occur compared to when ink 4M is ejected by only the first row ink head 4. In this case as well, although the amount of ink 4M ejected from each ink head 4 is halved, as shown in part A of Figure 10, by allowing the post-treatment liquid 6M to flow in after at least some ink 4M has landed on the pre-treatment liquid 5M, direct interaction between the pre-treatment liquid 5M and the post-treatment liquid 6M is less likely to occur.

[0091] As described above, in this embodiment, the ejection pattern designation unit 903 appropriately designates the ejection pattern of the two rows of ink heads 4 according to the difference in density (gradation expression) formed on the workpiece W. This prevents a decrease in image density around the pixel boundary line L and enables stable gradation expression.

[0092] Furthermore, if there are n (n is an integer of 2 or more) ink heads of the same color arranged at different positions in the transport direction F, and the ejection pattern designation unit 903 ejects ink from n-1 or fewer ink heads of the same color based on predetermined image information, then the ejection ink head can be designated so that ink is ejected from the upstream ink head H1 and not from the downstream ink head H2 among the n ink heads of the same color. In this case as well, a decrease in density near the pixel boundary line L can be made less likely.

[0093] In this case, it is desirable that the storage unit 904 pre-stores a plurality of discharge pattern information relating to the number of discharge ink heads and the amount of ink discharged from each discharge ink head, which is information referenced by the discharge pattern designation unit 903 in order to form an image on the workpiece W at a predetermined density. In particular, it is more desirable that the discharge pattern information includes at least discharge pattern information (first pattern information) for discharging ink from n same-color ink heads and discharge pattern information (second pattern information) for discharging ink from n-1 or fewer same-color ink heads. In this case, when the discharge pattern designation unit 903 designates the discharge ink heads based on the latter discharge pattern information, it is sufficient to designate the discharge ink heads such that ink is discharged from the upstream ink head H1 and not from the downstream ink head H2. As a result, if it is not necessary to discharge ink from all same-color ink heads, the discharge of ink from the downstream ink head H2 can be preferentially blocked, making it less likely for density reduction to occur near the pixel boundary line L.

[0094] In the inkjet printer 1 according to this embodiment, printing may be performed using only ink, only the pre-treatment solution and ink, or only the ink and post-treatment solution. In such cases, the aforementioned density reduction does not occur, so the ink ejection pattern using only the downstream ink head H2 (third ejection pattern) may be used. Furthermore, the degree to which the aforementioned density reduction is affected may vary depending on the combination of pre-treatment solution, ink, post-treatment solution and workpiece W type, as well as environmental factors such as temperature and humidity. If the aforementioned density reduction has little effect, the third ejection pattern may be used, prioritizing improvements to other factors affecting image quality. Moreover, depending on the degree of the aforementioned density reduction, the third ejection pattern may be used for certain densities, while patterns other than the third ejection pattern may be used for other densities.

[0095] The ejection pattern specification unit 903 uses to print a specific ink at a specific density. This ejection pattern may be user-configurable, or it may be a user-selectable pattern from those stored in the storage unit 904. By using a mode in which either a pattern in which ink is ejected from the upstream ink head H1 and the downstream ink head H2 respectively (first ejection pattern), or a pattern in which ink is ejected from the upstream ink head H1 but not from the downstream ink head H2 (second ejection pattern) is set, printing can be performed without a third ejection pattern.

[0096] Furthermore, the control unit 90 may be able to set an ejection mode in which ejection patterns corresponding to multiple densities used for printing are grouped together into a specific ejection pattern. In addition, it may have an ejection mode in which an ejection pattern is set for all densities used for printing that does not include the third ejection pattern described above.

[0097] Figure 11 is a schematic diagram illustrating the placement of ink and processing solutions on image dots near the head boundary in the inkjet recording apparatus according to this embodiment. As mentioned above, among phenomena 1 to 4 explained using Figures 18 to 20, phenomena 2, 3 and 4 are less likely to lead to a large change in image density compared to phenomenon 1, but phenomenon 4, indicated by the arrow in section C of Figure 20, may cause a slight decrease in image density, although less than in phenomenon 1.

[0098] In the inkjet printer 1 according to this embodiment, the decrease in image density due to such phenomenon 4 can also be reduced. As mentioned above, in the state shown in parts B and C of Figure 20, during a predetermined scan of the carriage 3, the ink 4M may land first, and the landing of the adjacent post-processing liquid 6M may be misaligned or smudged. Therefore, compared to the case where the post-processing liquid 6M lands in the next scan as intended, the time from the landing of the ink 4M to the influence of the post-processing liquid 6M is significantly shorter. As a result, the aggregated pigment may not bind well to the fibers of the workpiece W and may be carried deep into the fibers along with the post-processing liquid 6M, potentially resulting in a lower density.

[0099] On the other hand, in this embodiment, for example, when printing high-density pixels, as shown in part A of Figure 11, the ink 4M from the upstream inkhead H1 lands more than one scan length before the post-treatment liquid 6M lands. Since a predetermined amount of time has elapsed after the ink 4M1 from the upstream inkhead H1 has mixed with the pre-treatment liquid 5M, even if the post-treatment liquid 6M shifts or bleeds at an early timing after the ink 4M2 from the downstream inkhead H2 lands, the effect is small.

[0100] Furthermore, referring to section B in Figure 11, in this embodiment, when printing pixels with low density, ink 4M is ejected from at least the upstream ink head H1. By the time the post-treatment liquid 6M lands, sufficient time has elapsed since the ink 4M mixed with the pre-treatment liquid 5M. Therefore, even if the post-treatment liquid 6M shifts or bleeds, the effect will be small.

[0101] Thus, in this embodiment, the decrease in image density based on phenomenon 4 is less likely to occur. Note that phenomenon 3, indicated by the arrow in part B of Figure 20, involves new ink 4M flowing into the ink 4M that has already landed, and therefore, compared to the phenomenon in which the post-treatment solution 6M acts on the pre-treatment solution 5M as described above, it is less likely to lead to a large change in density.

[0102] Furthermore, according to the head arrangement of this embodiment, it is possible to increase the amount of ink and processing fluid discharged while miniaturizing the carriage 3. Specifically, by arranging the pre-processing head 5 and post-processing head 6 at different positions from the ink head 4 in the transport direction F, it is possible to arrange the ink heads 4A to 4F, which can discharge the required amount of ink, in the main scanning direction S, and enable printing processing in both the forward and return main scanning directions, while shortening the length of the carriage in the main scanning direction required to mount the heads 4 to 6.

[0103] In particular, the first to sixth ink heads 4A to 4F each include an upstream ink head H1 (4A1 to 4F1) and a downstream ink head H2 (4A2 to 4F2) 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 enable multi-color operation, it is difficult to increase the length of the carriage 3 in the main scanning direction.

[0104] Furthermore, the pre-processing head 5 and post-processing head 6 are positioned within the arrangement width H of the first to sixth ink heads 4A to 4F in the main scanning direction S (Figure 6). 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, it is not necessary to extend the length of the carriage 3 in the main scanning direction. In other words, it is difficult to increase the length of the carriage 3 in the main scanning direction.

[0105] Furthermore, the pre-processing head 5 and post-processing head 6 are positioned so that a portion of them fits between the arrangement pitches of the first to sixth ink heads 4A to 4F. This staggered arrangement allows the ink heads 4 and processing heads 5 and 6, which are located at different positions in the transport direction F, to be densely arranged in the transport direction F. Consequently, the length of the carriage 3 in the transport direction F can be reduced.

[0106] Furthermore, in the head arrangement of this embodiment, one pre-treatment head 5 is positioned upstream of the ink head 4 in the transport direction F, and one post-treatment head 6 is positioned downstream. In other words, an all-in-one inkjet printer 1 can be provided that has three types of heads—a head for ejecting pre-treatment liquid, ink, and post-treatment liquid—mounted on a single carriage 3. Also, since the pre-treatment head 5, ink head 4, and post-treatment head 6 are positioned sequentially in the transport direction F, the pre-treatment liquid, ink, and post-treatment liquid can be ejected in a desired landing order during both the forward and return main scans.

[0107] Furthermore, in this embodiment, the post-processing head 6 is positioned outside the arrangement range HB in the main scanning direction S where the downstream ink heads H2 (4A2 to 4F2) of each color are positioned (Figure 6). This arrangement reduces the number of downstream ink heads H2 close to the post-processing head 6 in the main scanning direction S. It also reduces the average distance between the post-processing head 6 and the downstream ink heads H2 of each color in the main scanning direction S. As a result, the occurrence of the phenomena described in Figures 18 to 20 can be reduced. When multiple post-processing heads 6 are arranged, it is desirable that all post-processing heads 6 be positioned outside the arrangement range as described below, but at least some of the post-processing heads 6 may be positioned outside the arrangement range.

[0108] Furthermore, in this embodiment, the post-processing head 6 is positioned such that a portion of it overlaps with the transport direction F with respect to the multiple downstream ink heads 2H included in the multiple sets of same-color ink heads, and is positioned in the same location in the main scanning direction S as one of the multiple upstream ink heads (4F1 in Figure 9) included in the multiple sets of same-color ink heads. With this configuration, the size of the carriage 3 on which the ink heads 4, pre-processing head 5, and post-processing head 6 are mounted can be made compact in the main scanning direction S and the transport direction F.

[0109] Furthermore, in this embodiment, the carriage 3 has a back frame 32 (engaging portion) that is cantilevered by a guide rail 17 (holding member). By cantilevering the carriage 3 to the timing belt 16, the structure can be simplified. In addition, by cantilevering, the downstream side of the carriage 3 can be easily opened, making it easier to perform maintenance on the ink head 4 and processing heads 5 and 6.

[0110] In this cantilevered carriage 3, the pre-processing head 5 is positioned at the base end 311 (the side closer to the engagement portion) of the head support frame 31, and the post-processing head 6 is positioned at the tip end 312 (the side further from the engagement portion). Unlike the base end 311, which is close to the back frame 32 fixed to the timing belt 16, the tip end 312, which is a free end, is expected to have reduced positional accuracy. However, the tip end 312 is equipped with a post-processing head 6, which does not require a high degree of precision in ejection accuracy. Since the post-processing solution coats the ink image printed on the workpiece W, even if there is a misalignment in the impact position, the relative impact on image quality can be reduced compared to if a similar misalignment occurs in the pre-processing solution. Therefore, even when using a cantilevered carriage 3, it is less likely to cause a decrease in image quality. Furthermore, even if there is a misalignment in the impact position of such a post-processing solution, as mentioned above, it is possible to stably reduce the decrease in image density near the pixel boundary line L.

[0111] In addition, in the head arrangements shown in Figures 6, 7, and 9, the downstream ink head H2 of the second row for each color may not be arranged. In other words, in this case, there may be only one row of ink heads 4. However, in this case, it is desirable that the post-processing head 6 in the transport direction F be arranged with a gap downstream of the upstream ink head H1 of the first row, as shown in the figures above. That is, it is desirable that the nozzle arrangement area from which ink 4M is discharged from the ink head 4 be located upstream of the nozzle arrangement area from which post-processing liquid 6M is discharged from the post-processing head 6, in the transport direction F. In addition, assuming such a positional relationship, multiple rows of upstream ink heads H1 may be arranged. With such a head arrangement, the landing positions of the post-processing liquid 6M will not be adjacent to the landing positions of the ink 4M in the transport direction F, as shown in part B of Figure 19.

[0112] In this case, the inkjet printer 1 includes a workpiece transport unit 20 that transports the workpiece W in a predetermined transport direction F, a carriage 3 that reciprocates in a main scanning direction S intersecting the transport direction F, ink heads 4 mounted on the carriage 3 that eject ink, at least one pre-treatment head 5 positioned upstream of the ink heads 4 in the transport direction F and ejecting a non-coloring pre-treatment liquid, and at least one post-treatment head 6 positioned downstream of the plurality of ink heads 4 in the transport direction F and ejecting a non-coloring post-treatment liquid. The nozzle arrangement area of ​​the ink head 4 is spaced apart in the transport direction F from the nozzle arrangement area of ​​the post-treatment head 6 located downstream of it.

[0113] Next, the head arrangement in the carriage 3 of the inkjet printer 1 according to another embodiment of this disclosure will be described. In the following embodiments, the differences from the first embodiment will be described in particular, and the common points will be omitted.

[0114] Figure 12 is a schematic plan view showing the upstream ink head H1 and the downstream ink head H2 on the carriage 3A of an inkjet printer 1 (inkjet recording device) according to the second embodiment of this disclosure. In the first embodiment described above, as shown in Figure 9, each color ink head 4 was provided with one upstream ink head H1 and one downstream ink head H2. In this embodiment, as shown in Figure 12, the upstream ink head H1 is provided with two rows of heads (4F1, 4F2) arranged at different positions in the transport direction F, and the downstream ink head H2 is provided with one row of heads (4F3), similar to the first embodiment. Although only the sixth black ink head 4F is shown in Figure 12, the same applies to the ink heads of other colors. In this embodiment as well, each head is arranged in a staggered pattern.

[0115] In this embodiment, the nozzle arrangement area of ​​the downstream ink head H2 (4F3) is continuous (connected, adjacent) with the nozzle arrangement area of ​​the post-processing head 6 along the transport direction F. On the other hand, the nozzle arrangement areas of the upstream ink heads H1 (4F1, 4F2) are spaced apart from the nozzle arrangement area of ​​the post-processing head 6 in the transport direction F. Therefore, in this embodiment as well, by ejecting ink from at least the upstream ink head H1 to a predetermined pixel, it is possible to make it less likely for the image density to decrease near the pixel boundary line L.

[0116] In this case, the ejection pattern designation unit 903 adopts a pattern in which ink is dispersed and ejected from three heads, the upstream ink head H1 and the downstream ink head H2, for the image density required for the predetermined pixel. As with parts A and B of Figure 10, when the post-processing liquid 6M ejected from the post-processing head 6 lands at the predetermined pixel position, ink 4M has already landed on the pre-processing liquid 5M. Therefore, it becomes less likely that the post-processing liquid 6M will directly act on the pre-processing liquid 5M.

[0117] Furthermore, when ink is dispersed and ejected from two heads in accordance with the image density required for a predetermined pixel, the ejection pattern designation unit 903 may eject ink from the two heads of the upstream ink head H1. Moreover, for each color ink head, n (n is an integer of 3 or more) ink heads of the same color are arranged at different positions in the transport direction F, and the ejection pattern designation unit 903 ejects ink from n-2 or fewer ink heads of the same color based on predetermined image information, then the ejection ink heads should be designated preferentially from the ink heads of the same color located upstream in the transport direction F among the multiple upstream ink heads H1. With this configuration, since ink is ejected from the ink heads further upstream, the post-treatment liquid 6M lands after the pre-treatment liquid 5M and ink 4M have had sufficient time to act. As a result, it becomes even less likely that the post-treatment liquid 6M will directly act on the pre-treatment liquid 5M.

[0118] Furthermore, in this embodiment as well, the storage unit 904 may store one or more discharge pattern information relating to a combination of the number of discharge ink heads and the amount of ink discharged from each discharge ink head, which is referenced by the discharge pattern designation unit 903 in order to form an image on the workpiece W at a predetermined density. If the discharge pattern information includes a plurality of discharge pattern information (specific discharge pattern information) that are stored in correspondence to at least one density and have different numbers of discharge ink heads, the discharge pattern designation unit 903 may select the discharge pattern information with the smallest number of discharge ink heads and designate the discharge ink heads when recording an image at the density for which the plurality of specific discharge pattern information are stored in correspondence. In this case as well, by preferentially discharging ink from the ink heads located upstream in the transport direction F with the fewest possible number of ink heads, it becomes even less likely that the post-treatment liquid 6M will directly act on the pre-treatment liquid 5M.

[0119] Figure 13 is a schematic plan view showing the arrangement of the ink head and processing head on the carriage 3B in an inkjet printer 1 according to the third embodiment of this disclosure. In the first embodiment described above, the pre-processing head 5 and post-processing head 6 were arranged at the right end of the ink head 4, but as shown in Figure 13, the pre-processing head 5 and post-processing head 6 may also be arranged at the left end of the ink head 4. In this case as well, since ink is ejected from at least the upstream ink head (for example, 4A1) of the ink head 4, it becomes less likely that the post-processing liquid 6M will directly act on the pre-processing liquid 5M near the pixel boundary line L.

[0120] Figure 14 is a schematic plan view showing the arrangement of ink heads and processing heads on the carriage 3C in an inkjet printer 1 according to the fourth embodiment of this disclosure. In the first embodiment described above, the upstream ink head H1 was arranged to the right of the downstream ink head H2 for each color ink head, but as shown in Figure 14, the upstream ink head may be arranged to the left of the downstream ink head. In this case as well, the head arrangement area on the carriage 3 can be made compact by arranging the ink heads 4, pre-processing head 5 and post-processing head 6 in a staggered pattern. In both the embodiments of Figure 13 and Figure 14, as in the first embodiment above, each head is arranged in a staggered pattern, and the pre-processing head 5 and post-processing head 6 are arranged within the arrangement range of the ink head 4 in the main scanning direction S, so the size of the carriage 3 in the main scanning direction S and the transport direction F can be made even more compact.

[0121] Figure 15 is a schematic plan view showing the arrangement of ink heads and processing heads on the carriage 3D in an inkjet printer 1 according to the fifth embodiment of this disclosure. In the first embodiment described above, a configuration was described in which one pre-processing head 5 and one post-processing head 6 were arranged. However, as shown in Figure 15, a configuration may be provided in which two post-processing heads 6A and 6B are arranged at different positions in the main scanning direction S. In this case, the post-processing heads 6A and 6B are arranged side by side in the main scanning direction S, outside the arrangement range HB in which the downstream ink heads H2 of each color are arranged in the main scanning direction S. With such an arrangement, the number of downstream ink heads H2 close to the post-processing heads 6A and 6B in the main scanning direction S can be reduced. In addition, the average distance between the post-processing heads 6A and 6B and the downstream ink heads H2 of each color in the main scanning direction S can also be reduced. As a result, the occurrence of the phenomena described in Figures 18 to 20 can be reduced. Furthermore, as in this embodiment, since the post-treatment head 6 is composed of multiple post-treatment heads 6A and 6B, even if the discharge volume of post-treatment liquid is insufficient with a single head, the required amount can be discharged by arranging multiple post-treatment heads 6A and 6B. Note that the number of post-treatment heads in Figure 15 may be three or more.

[0122] Figure 16 is a schematic plan view showing the arrangement of the ink head and processing head on the carriage 3E in the inkjet printer 1 according to the sixth embodiment of this disclosure.

[0123] In this embodiment as well, the carriage 3E is held in a cantilevered state by the guide rail 17 (holding member) (Figures 1 and 2), with the back frame 32 (engaging portion) being held in place by this guide rail. The head support frame 31 is equipped with an ink head 4 having first to sixth ink heads 4A to 4F, a pre-processing head 5, and a post-processing head 6 having two post-processing heads 6A and 6B. In this embodiment as well, by ejecting ink from at least the ink head 4 upstream in the transport direction F to the predetermined pixel, the post-processing liquid 6M directly acts on the pre-processing liquid 5M near the pixel boundary line L, making it less likely for a decrease in image density to occur.

[0124] Furthermore, in this embodiment as well, post-processing heads 6A and 6B are provided, which are positioned at different locations in the main scanning direction S. Here, as shown in Figure 16, the post-processing head 6B is positioned outside the main scanning direction S relative to the arrangement range HB of the multiple downstream ink heads H2 included in the multiple sets of same-color ink heads (first post-processing head). On the other hand, the post-processing head 6A is positioned such that a portion of it fits between a pair of adjacent downstream ink heads H2 in the main scanning direction S, and is positioned alongside the post-processing head 6B in the main scanning direction S (second post-processing head). Even with this arrangement, the number of ink heads close to the multiple post-processing heads 6A and 6B in the main scanning direction S can be reduced. In addition, the average distance between the post-processing heads 6A and 6B and the downstream ink heads of each color in the main scanning direction S can be reduced. Furthermore, while achieving these effects, the size of the carriage 3 in the main scanning direction S can be made more compact.

[0125] In this embodiment, the pre-processing head 5 is composed of one unit head, and the post-processing head 6 is composed of two unit heads (post-processing heads 6A and 6B). Of these pre-processing head 5 and post-processing head 6, the pre-processing head 5, which has fewer unit heads, is positioned at the base end 311 of the head support frame 31. The post-processing head 6, which has more unit heads, is positioned at the tip end 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.

[0126] As described above, the processing heads 5 and 6 generate heat during the ejection operation. As schematically shown in Figure 16, the high-temperature pre-processing head 5 dissipates heat ha. The same applies to the post-processing heads 6A and 6B. This heat ha heats the head support frame 31 of the carriage 3E, which can cause thermal deformation of the head support frame 31, its holding structure the back frame 32, and the fixing fittings between the back frame 32 and the timing belt 16. In the carriage 3E, which is held in a cantilevered state, this thermal deformation can affect the accuracy of the ink ejected from the ink head 4.

[0127] However, in the carriage 3E according to this embodiment, a pre-processing head 5 with a small number of unit heads is placed on the base end side 311, which is the cantilevered side of the head support frame 31. This reduces the effects of thermal deformation (reduction in impact accuracy). If a post-processing head 6 with a large number of unit heads were placed on the base end side 311, the back frame 32 would receive heat dissipation from the two unit heads, becoming hotter and more susceptible to thermal deformation.

[0128] Furthermore, in carriage 3E, the pre-processing head 5, which is located on the side closest to the back frame 32 of carriage 3E, is positioned in a location that excludes the end in the main scanning direction S of the arrangement HA of the ink heads 4 and processing heads 5 and 6. Of the heads 4, 5, and 6 mounted on carriage 3E, the pre-processing head 5 is the head located on the side closest to the back frame 32 (engagement portion). Such a pre-processing head 5 is positioned in a location that excludes the arrangement end 313, which is the end of the head arrangement HA.

[0129] Since the carriage 3E cannot be unnecessarily enlarged, if a head is placed at the placement end 313 of the head array in the main scanning direction S, that head will be the closest head to the corner of the carriage 3E (head support frame 31) in the main scanning direction S. Because the placement end 313 is also near the cantilevered back frame 32, thermal deformation in that area can induce distortion and displacement of the head support frame 31 in the height and horizontal directions. This reduces the impact position accuracy of the heads 4, 5, and 6 mounted on the carriage 3E. Therefore, by not placing the high-temperature pre-processing head 5 in the area of ​​the placement end 313, the above-mentioned thermal deformation problem can be made less likely to occur.

[0130] In this embodiment as well, among the two rows of ink heads 4, the row of heads 4 located on the engagement side (upstream ink head H1) is in a staggered arrangement, shifted to the right in Figure 16. Furthermore, a pre-processing head 5, which is a processing head with fewer heads, is placed on the engagement side, and the pre-processing head 5 is positioned as far to the right as possible in the staggered arrangement. By arranging the heads in this way, it is possible to arrange the heads so that no processing heads are placed at the arrangement end 313.

[0131] Furthermore, in this embodiment, compared to the arrangement in Figure 15, which is similar in that multiple post-processing heads 6 are arranged, the post-processing heads 6A and 6B are arranged within the arrangement range of the ink head 4 in the main scanning direction S, so the size of the carriage 3E can be made more compact.

[0132] Figure 17 is a schematic plan view showing the arrangement of the ink head, processing head, and sub-tank on the carriage 3E in the inkjet printer 1 according to this embodiment. Below, a preferred arrangement relationship between the heads 4, 5, and 6 on the carriage 3E and the sub-tank that supplies ink or processing liquid to them will be illustrated.

[0133] The carriage 3E is also equipped with sub-tanks 7. Sub-tanks 7 include ink sub-tanks 7A to 7F, a pre-treatment liquid sub-tank 71, and a post-treatment liquid sub-tank 72. These sub-tanks 7 are supplied with ink, pre-treatment liquid, and post-treatment liquid, respectively, from the main tank (not shown). The ink sub-tanks 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 ink head 4A1 of the first ink head 4A from the first tank 7A1 of the ink sub-tanks 7A via pipeline P1, and to the downstream ink head 4A2 from the second tank 7A2. The second to sixth ink heads 4B to 4F are similarly supplied with the second to sixth colors of ink, respectively. The arrangement order of the ink sub-tanks 7 in the main scanning direction S is the same as the arrangement order of the ink heads 4 to which each ink sub-tank 7 supplies ink in the main scanning direction S.

[0134] Furthermore, ink may be supplied from a single ink sub-tank 7 to multiple ink heads 4 that eject ink of the same color. In this case, the ink heads 4 that share the ink sub-tank 7 may be arranged in a grouped position in the main scanning direction S. Moreover, it is preferable to arrange the ink heads 4 that eject the same ink together in the main scanning direction S, and the order in which the ink sub-tanks 7 for each color are arranged may be the same as the order in which the ink heads 4 for each color are arranged in the main scanning direction S.

[0135] The pre-treatment liquid sub-tank 71 supplies the pre-treatment liquid to the pre-treatment head 5 via pipeline P2. The post-treatment 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-treatment liquid to the post-treatment heads 6A and 6B, respectively, via pipeline P3.

[0136] The ink sub-tanks 7A to 7F are mounted on the carriage 3E so as to be aligned in the main scanning direction S. The processing liquid sub-tanks 71 and 72 are positioned in the transport direction F at a different location from the ink sub-tanks 7A to 7F, and are aligned in the main scanning direction S. Specifically, the pre-processing liquid sub-tank 71 and the first and second tanks 72A and 72B of the post-processing liquid sub-tank 72 are aligned in a line in the main scanning direction S downstream of the ink sub-tanks 7A to 7F in the transport direction F. Alternatively, the pre-processing liquid sub-tank 71 may be positioned upstream of the ink sub-tanks 7A to 7F.

[0137] The liquid in the sub-tank 7, mounted on the carriage 3E which moves back and forth in the main scanning direction S, is subjected to the acceleration in that direction. The sub-tank 7 and each head 4, 5, and 6 are connected by conduits P1, P2, and P3. If the sub-tank 7 is widely distributed on the carriage 3J, the range of arrangement of conduits P1 to P3 in the main scanning direction S will also be large. Since these conduits P1 to P3 are also filled with ink or processing liquid, the acceleration may cause meniscus damage at the discharge portion of the heads 4, 5, and 6.

[0138] However, according to the configuration of this embodiment, the ink sub-tanks 7A to 7F are mounted on the carriage 3E so as to be aligned in the main scanning direction S, similar to the first to sixth ink heads 4A to 4F. Therefore, it is possible to arrange the ink sub-tanks 7A to 7F in a relatively narrow area on the head support frame 31 of the carriage 3J. 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 3E.

[0139] Furthermore, since the pre-treatment liquid sub-tank 71 and the post-treatment liquid sub-tank 72 are positioned separately from the ink sub-tanks 7A to 7F in the transport direction F, the difference in position between the pre-treatment liquid sub-tank 71 and the post-treatment liquid sub-tank 72 and the processing head to which each of them supplies the processing liquid in the main scanning direction S can be minimized. As a result, the distribution range of the pre-treatment liquid connected to the pre-treatment liquid sub-tank 71, the pipeline P, and the pre-treatment head 5 in the main scanning direction S can be reduced, making it less susceptible to the effects of acceleration. Similarly, the distribution range of the connected post-treatment liquid in the main scanning direction S can be reduced, making it less susceptible to the effects of acceleration.

[0140] Similarly, the difference in position between the ink sub-tanks 7A-7F and the ink head 4 that supplies ink from each of the ink sub-tanks 7A-7F in the main scanning direction S can be minimized. This reduces the distribution range of connected inks in the main scanning direction S, making them less susceptible to the effects of acceleration.

[0141] Next, the head arrangement on the carriage of other inkjet recording devices that are comparable to the inkjet printer 1 according to each embodiment of this disclosure will be described. Figure 21 is a schematic plan view showing the arrangement of the ink head and processing head on the carriage of the above-mentioned other inkjet recording device.

[0142] As described above, the problems based on the phenomena explained in Figures 18 to 20 become particularly noticeable when the pre-treatment liquid 5M, ink 4M, and post-treatment liquid 6M are applied to a predetermined pixel on the workpiece W by separate scans (movement of the carriage 3). The head arrangements according to each of the above embodiments can suitably solve these problems.

[0143] On the other hand, in the example shown in Figure 21, two pre-treatment heads 5A and 5B are positioned on either side of the main scanning direction S of multiple ink heads 4 (4A to 4F), and a post-treatment head 6 is positioned downstream of these heads in the transport direction F. In this case, within the scanning of the carriage 3 in a predetermined direction, pre-treatment liquid 5M can be ejected and landed from the pre-treatment head 5A or 5B, and ink 4M can be ejected and landed from each ink head 4. Then, in the next scan of the carriage 3, post-treatment liquid 6M can be ejected and landed from the post-treatment head 6. In this case, since the ink 4M lands while the pre-treatment liquid 5M is penetrating into the fibers of the workpiece W, even if misalignment or bleeding occurs when the post-treatment liquid 6M lands afterward, the effect of the ink 4M's pigment penetrating deep into the fibers is less likely to occur compared to when the ink 4M lands after the penetration of the pre-treatment liquid 5M has stopped. However, even in the example shown in Figure 21, when performing bidirectional printing, the time interval between the impact of ink 4M and the impact of post-treatment liquid 6M is short at the end of the main scanning direction S where the movement direction of carriage 3 switches, so there is concern about the aforementioned decrease in image density. However, as described above, since ink 4M and pre-treatment liquid 5M are already impacted within the same scan at an even shorter time interval, a decrease in image density due to direct interaction between pre-treatment liquid 5M and post-treatment liquid 6M is unlikely to occur. In other words, in the arrangement shown in Figure 21, the problem of decreased pixel density, as explained using Figure 19, does not substantially occur. [Explanation of Symbols]

[0144] 1. Inkjet printer (inkhead type recording device) 16 Timing belt (movable component) 17 Guide rail (holding member) 20 Workpiece transport section (transport section) 3, 3A~3E Carriage 31 Head support frame 32 Backframe 4 Ink Heads 4A~4F Inkheads 1st~6th 5. Pre-processing head (processing head) 6. Post-processing head (processing head) 7 Sub-tank 71 Sub-tank for pre-treatment liquid 72 Sub-tank for post-treatment fluid Sub-tank for 7A~7F ink 90 Control Unit 901 Drive Control Unit 902 Discharge Control Unit 903 Discharge pattern specification unit (discharge head specification unit) 904 Storage section F Conveying direction H1 Upstream Ink Head H2 Downstream Ink Head S Main scanning direction W Work (Recording medium)

Claims

1. A transport unit that transports the recording medium in a predetermined transport direction, A carriage that moves back and forth in the main scanning direction intersecting the transport direction, The carriage is equipped with multiple ink heads, each ejecting ink, Equipped with, The plurality of ink heads include a plurality of same-color ink heads arranged in line in the transport direction and ejecting ink of the same color from each other. An inkjet recording device in which, when viewed along the main scanning direction, one end of one of the plurality of same-color ink heads on the transport direction side overlaps with the other end of another of the plurality of same-color ink heads on the transport direction side.

2. In the inkjet recording apparatus according to claim 1, The system further comprises at least one processing head that discharges a non-coloring processing solution, The entirety of one of the at least one processing heads is positioned so as to overlap the one same-color ink head when viewed along the transport direction. An inkjet recording device in which the end of one processing head is positioned to overlap with other ink heads of the same color among the plurality of ink heads of the same color when viewed along the main scanning direction.

3. In the inkjet recording apparatus according to claim 2, The plurality of ink heads, when the plurality of same-color ink heads are considered as a set of same-color ink heads, have a plurality of sets of same-color ink heads arranged in the main scanning direction and each ejecting ink of a different color. The aforementioned multiple sets of ink heads of the same color are A one-sided ink head, which is positioned closest to one side in the transport direction, In the aforementioned transport direction, at least one other ink head is positioned on the other side of the transport direction from the one ink head, Each of these includes, An inkjet recording device wherein the at least one processing head is positioned outside the main scanning direction with respect to the arrangement range of the plurality of one-sided ink heads included in the plurality of sets of same-color ink heads.

4. In the inkjet recording apparatus according to claim 3, The at least one processing head includes a plurality of processing heads arranged at different positions in the main scanning direction, An inkjet recording device in which the plurality of processing heads are arranged outward in the main scanning direction with respect to the arrangement range of the plurality of one-sided ink heads.

5. In the inkjet recording apparatus according to claim 2, The plurality of ink heads, when the plurality of same-color ink heads are considered as a set of same-color ink heads, have a plurality of sets of same-color ink heads arranged in the main scanning direction and each ejecting ink of a different color. The aforementioned multiple sets of ink heads of the same color are A one-sided ink head, which is positioned closest to one side in the transport direction, In the aforementioned transport direction, at least one other ink head is positioned on the other side of the transport direction from the one ink head, Each of these includes, The at least one processing head includes a plurality of processing heads arranged at different positions in the main scanning direction, The aforementioned plurality of processing heads A first processing head is positioned outside the main scanning direction with respect to the arrangement range of the multiple one-sided ink heads included in the multiple sets of same-color ink heads, A second processing head is positioned such that a portion of the plurality of one-sided ink heads is inserted between a pair of adjacent one-sided ink heads in the main scanning direction, and is positioned alongside the first processing head in the main scanning direction, Inkjet recording device, including

6. In the inkjet recording apparatus according to claim 2, The carriage is further provided with a holding member that holds it in a state that allows it to reciprocate in the main scanning direction, The carriage includes an engaging portion, which is cantilevered to the retaining member by the engaging portion. In the aforementioned transport direction, the processing head is positioned on the opposite side of the engagement portion from the plurality of ink heads in an inkjet recording apparatus.

7. In the inkjet recording apparatus according to any one of claims 3 to 6, Each of the multiple identical ink heads contained within a set of identical ink heads has n identical ink heads (where n is an integer of 2 or more) that are arranged at different positions in the transport direction. The system further includes a discharge head designation unit that designates a discharge ink head, which is an ink head that discharges the ink, from among the n ink heads of the same color in order to land the ink at a predetermined position on the recording medium based on predetermined image information. The ejection head designation unit, when ejecting ink from n-1 or fewer ink heads of the same color based on the image information, designates the ejection ink head so that ink is ejected from the other ink head among the n ink heads of the same color and not from the one ink head.

8. In the inkjet recording apparatus according to claim 7, The above n is an integer greater than or equal to 3, The ejection head designation unit, when ejecting ink from n-2 or fewer ink heads of the same color based on the image information, preferentially designates the ejection ink head from the other ink heads of the same color located on the other side in the transport direction.

9. In the inkjet recording apparatus according to claim 8, The storage unit further stores information referenced by the ejection head designation unit for forming an image at a predetermined density on the recording medium, which includes one or more ejection pattern pieces relating to a combination of the number of ejection ink heads and the amount of ink ejected from each ejection ink head. The ejection pattern information includes a plurality of specific ejection pattern information, each with a different number of ejection ink heads, which are stored in correspondence with at least one density. The ejection head designation unit is an inkjet recording device that, when recording an image at the density corresponding to the plurality of specific ejection pattern information stored, selects the specific ejection pattern information with the smallest number of ejection ink heads from among the plurality of specific ejection pattern information and designates the ejection ink head.

10. In the inkjet recording apparatus according to claim 8, The storage unit further stores a plurality of ejection pattern information relating to a combination of the number of ejection ink heads and the amount of ink ejected from each ejection ink head, which is referenced by the ejection head designation unit in order to form an image at a predetermined density on the recording medium, The ejection pattern information includes at least a first pattern information for ejecting the ink from n ink heads of the same color, and a second pattern information for ejecting the ink from n-1 or fewer ink heads of the same color. The ejection head designation unit, when designating the ejection ink head based on the second pattern information, designates the ejection ink head such that it ejects ink from the other ink head and does not eject ink from the one ink head, in an inkjet recording device.

11. In the inkjet recording apparatus according to any one of claims 3 to 5, An inkjet recording apparatus in which all ejection that causes the ink of the same color to land at a predetermined position on the recording medium based on predetermined image information is either an ejection in which the ink is ejected from the other ink head and not from the one ink head, or an ejection in which the ink is ejected from both the other ink head and the one ink head, respectively.

12. Transporting a recording medium in a predetermined transport direction, The carriage is moved back and forth in the main scanning direction intersecting the transport direction, The plurality of ink heads, including the plurality of ink heads of the same color, are arranged on the carriage such that the plurality of ink heads of the same color are aligned in the transport direction. To deposit ink of the same color onto the recording medium from the aforementioned plurality of ink heads of the same color, Equipped with, An inkjet recording method comprising arranging the plurality of ink heads on the carriage such that, when viewed along the main scanning direction, one end of one of the plurality of same-color ink heads on the transport direction overlaps with the other end of another of the plurality of same-color ink heads on the transport direction.

13. In the inkjet recording method according to claim 12, At least one processing head is positioned on the carriage, The process involves depositing a non-color-developing pretreatment solution onto the recording medium from at least one of the processing heads, Furthermore, An inkjet recording method comprising arranging the at least one processing head in the carriage such that one of the at least one processing heads overlaps with one of the same-color ink heads when viewed along the transport direction, and the end of the one processing head overlaps with another of the plurality of same-color ink heads when viewed along the main scanning direction.

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