Liquid discharge device

Abstract

To provide a serial type liquid discharge device which can continuously perform coating of a pretreatment liquid, primer formation by white ink, and printing by color ink, by an integral device.SOLUTION: A liquid discharge device includes a plurality of heads 10, a plurality of carriages 20, and conveyance means for intermittently conveying a medium 50 in a sub-scanning direction in accordance with scanning of the head 10, wherein the head 10 has a first head 11 for discharging a pretreatment liquid 31, a second head 32 for discharging white ink 32 and a third head 33 for discharging color ink 33, the pretreatment liquid 31, the white ink 32 and the color ink 33 are arranged in this order in a dischargeable manner, when nozzle resolutions of the first head to the third head are represented by N1 to N3, they satisfy relations of 1≥N2≥N3, and N1 / N3=m, N2 / N3=n and m≥n (m and n are integers of 1 or more), and when a line feed amount is represented by W, and arrangement intervals of each of the heads are represented by L1 and L2, they satisfy relations of L1=W×p, and L2=W×q (p and q are integers of 0 or more).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a liquid ejection device. [Background technology]

[0002] As a liquid ejection device, a direct to garment (DTG) printer that uses an inkjet system to print directly onto clothing such as T-shirts is known. Some DTG printers achieve vivid color development by forming a base with white ink on a non-white medium and then printing in color.

[0003] In inkjet printing, a process of applying a pretreatment liquid to a medium and drying it may be necessary to form an image with less bleeding and excellent robustness. For example, when forming an image on a polyester fabric as a medium using a pigment ink, there is a problem that the ink does not adhere sufficiently to the polyester, and the image easily peels off after washing or the like. Therefore, in order to increase the adhesion of the image, a pretreatment liquid is applied to the polyester fabric in advance, and a process is performed in which the ink is aggregated and fixed on the surface of the polyester fiber by a crosslinking reaction.

[0004] For media other than fabrics (e.g., non-paper materials such as plain paper, coated paper, and film), a pretreatment liquid is applied to the print medium to prevent ink bleeding and improve ink fixation. The pretreatment liquid can be applied by a sprayer (compressor) or a coater (roller), or can be ejected using an inkjet head.

[0005] Since fabric is a material with a higher porosity than other media such as paper and film, the applied pretreatment liquid is likely to escape to the back side without remaining on the surface. Therefore, when applying a pretreatment liquid to fabric, it is necessary to increase the viscosity of the pretreatment liquid or apply a large amount of the pretreatment liquid to wet the fabric. However, there are problems in that a high viscosity of the pretreatment liquid affects the ejection properties of the inkjet head, and applying a large amount of the pretreatment liquid leads to an increase in the size of the apparatus due to the need to add an application system, etc.

[0006] Conventionally, pre-processing of media has often been performed offline. In contrast, in recent years, configurations have been proposed that allow pre-processing, undercoating, and color printing to be performed consecutively within the same device. However, in a configuration in which a series of operations from pretreatment to printing are performed using the same device, if ink is ejected outside the area where the pretreatment liquid has been applied or the base area, there is a problem in that the image formed will be degraded.

[0007] In response to this, an image forming apparatus has been disclosed that ejects a pretreatment liquid so that the application area of ​​the pretreatment liquid is larger than the printing area (area where the ink is ejected), thereby achieving high image quality (see, for example, Patent Document 1). In the apparatus of Patent Document 1, the resolution of the pretreatment liquid is higher than the resolution of the color inks. Summary of the Invention [Problem to be solved by the invention]

[0008] The device of Patent Document 1 is a line-type system, and it is possible to control the ejection of the pretreatment liquid and the ejection of the ink separately in accordance with the transport speed of the medium. On the other hand, it is difficult to perform similar control on a serial DTG printer that performs multi-pass printing.

[0009] In serial DTG printers, if the pre-processing, which was previously performed offline, could be performed continuously in an integrated device along with base formation using white ink and image formation using color inks, it would be possible to reduce equipment costs and operating costs.

[0010] In particular, if sequential printing can be performed using the same device even when the configurations and nozzle resolutions of the heads that eject the pretreatment liquid, the white ink, and the color inks are different, the productivity can be significantly improved. Furthermore, if the color inks can be ejected without straying from the application area of ​​the pretreatment liquid and the base area, the robustness and image quality of the image on the medium can be improved.

[0011] SUMMARY OF THE PRESENTLY PREFERRED EMBODIMENTS An object of the present invention is to provide a serial type liquid ejection apparatus that is capable of continuously carrying out application of a pretreatment liquid, base formation with white ink, and printing with color inks in an integrated apparatus. [Means for solving the problem]

[0012] In order to solve the above problems, a liquid ejecting device of the present invention includes a plurality of heads that eject liquid onto a medium, a plurality of carriages that mount the heads and move back and forth in a main scanning direction, and a transport means that intermittently transports the medium in a sub-scanning direction in response to scanning of the heads, the heads having a first head that ejects a pretreatment liquid from a nozzle, a second head that ejects a white ink from a nozzle, and a third head that ejects a colored ink other than white from a nozzle, and are arranged so as to be able to eject the pretreatment liquid, the white ink, and the colored ink in this order onto the medium, and the nozzle resolution of the first head is When N1 is the nozzle resolution of the second head, N2 is the nozzle resolution of the third head, and N3 is the nozzle resolution of the third head, the relationships N1≧N2≧N3 and N1 / N3=m, N2 / N3=n, m≧n (m and n are integers of 1 or more) are satisfied, and when the amount of line feed per time that the transport means moves the medium in the sub-scanning direction in response to the scan of the third head is W, the arrangement distance between the first head and the second head in the sub-scanning direction is L1, and the arrangement distance between the second head and the third head in the sub-scanning direction is L2, the relationships L1=W×p, L2=W×q (p and q are integers of 0 or more) are satisfied. Effect of the Invention

[0013] According to the present invention, it is possible to provide a serial type liquid ejection device that can continuously perform application of a pretreatment liquid, base formation with white ink, and printing with color inks in an integrated device. [Brief description of the drawings]

[0014] [Figure 1] FIG. 2 is an explanatory diagram illustrating a schematic configuration of a main part of a DTP printer. [Diagram 2] FIG. 2 is an explanatory diagram showing an example of the configuration of a head mounted on a carriage. [Diagram 3] FIG. 4 is an explanatory diagram of the printing order and nozzle resolution of each head. [Figure 4] FIG. 4 is an explanatory diagram of the printing order and nozzle resolution of each head. [Diagram 5] 1A to 1C are diagrams illustrating a process in which a discharged liquid permeates a medium. [Figure 6] 1A to 1C are diagrams illustrating a process in which a discharged liquid permeates a medium. [Figure 7] 1A and 1B are diagrams illustrating a line feed operation and a line feed amount in a printing process. [Figure 8] 11A and 11B are diagrams illustrating the concept of matching the amount of line feed when printing using heads with different nozzle resolutions. [Figure 9] 11 is a diagram showing the relationship between the amount of line feed and the arrangement interval of each head (each carriage). [Figure 10] FIG. 4 is a diagram illustrating an example of the configuration of a carriage. [Figure 11] 1A and 1B are a perspective view and a top view showing an example of the overall configuration of a liquid ejection device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The liquid ejection device according to the present invention will be described below with reference to the drawings. Note that the present invention is not limited to the following embodiments, and may be modified, added, modified, deleted, or otherwise altered within the scope of what a person skilled in the art can conceive, and any embodiment is within the scope of the present invention as long as it achieves the functions and effects of the present invention. In addition, in the present application, the terms image formation, recording, printing, printing, etc. are all synonymous.

[0016] <Example of the overall configuration of a liquid ejection device> The liquid ejection apparatus of this embodiment is a serial type inkjet printer, for example, a DTG printer that forms an image on clothing (fabric) such as a T-shirt. Hereinafter, the liquid ejection apparatus of this embodiment will also be referred to as a "DTG printer."

[0017] FIG. 11 shows an example of the overall configuration of a liquid ejection device of this embodiment, where FIG. 11(A) is a perspective view and FIG. 11(B) is a front view. In FIG. 11, X indicates the main scanning direction, Y indicates the sub-scanning direction perpendicular to the main scanning direction X, and Z indicates the up-down direction (also the vertical direction or height direction) perpendicular to the main scanning direction X and the sub-scanning direction Y.

[0018] The DTG printer comprises a number of heads 10 that eject liquid onto a medium, a number of carriages 20 that carry the heads 10 and move back and forth in the main scanning direction X, and a transport means 61 (hereinafter referred to as the "platen") that intermittently transports the medium in the sub-scanning direction Y in response to the scanning of the heads 10. Note that, in Figure 11 (A), an example of an embodiment having multiple carriages 20 is shown in which two carriages (20a, 20b) are provided, but the number of carriages is not limited to this and can be three or more.

[0019] The platen 61 is mounted on a lifting mechanism 62, and is configured so that its height in the vertical direction Z can be adjusted. This makes it possible to accommodate a variety of media thicknesses. The lifting mechanism 62 for the platen 61 is mounted on a slider 63. The slider 63 is movably mounted on a slide rail 64 that extends in the main scanning direction X and the sub-scanning direction Y.

[0020] The guide rods (main guide rod 21 and sub guide rod 22) support the carriage 20 so as to be capable of reciprocating in the main scanning direction X. In addition, Figure 11 (A) shows an example in which the carriage 20 is held by a main guide rod 21 and a secondary guide rod 22, but the configuration of the guide rods is not limited to this, and the carriage 20 may be held by a single guide rod.

[0021] The carriage 20 is connected to a timing belt 27 that is wound around a drive pulley rotated by a main scanning motor that can rotate in forward and reverse directions, and the pulley 16. By driving the main scanning motor, the carriage 20 moves back and forth in the main scanning direction X.

[0022] The encoder sheet 25 is disposed along the main scanning direction X. Periodic slits are provided in the encoder sheet 25, and a reading sensor is provided in the carriage 20 to read the slits in the encoder sheet 25. From the reading result of the sensor, the position of the carriage 20 in the main scanning direction X can be detected.

[0023] The controller board 7 is a means for processing and controlling the operation (output) of motors, solenoids, etc., and input signals from sensors, etc., and controls the ejection of liquid. The controller board 7 also performs, for example, print control of print data sent from a PC, and print control processing by reading print data recorded in a USB memory.

[0024] A plurality of heads 10 are mounted on the carriage 20. Each head 10 has a nozzle row aligned in the sub-scanning direction (see FIGS. 3 and 4). The carriage 20 also has a head tank mounted thereon for temporarily storing ink as the liquid to be supplied to the head 10. The head tank is connected to the ink cartridge 8 via a supply tube and a supply pump.

[0025] The DTG printer is equipped with a detection means 67 that detects unevenness of the surface of the medium (fabric) on the platen 61. The detection means 67 is, for example, a position sensor that detects the height position of the medium in the up-down direction Z. If the position sensor detects that the surface of the medium is at a height that makes contact with the nozzle face of the head 10, it is determined that an error has occurred and the operation of the platen 61 is controlled to stop.

[0026] A maintenance unit 27 that maintains and recovers the head 10 is disposed on one end side in the main scanning direction X. The maintenance unit 27 includes a moisture retention cap 18a and a suction cap 18b for protecting the head 10 from drying out when the DTG printer is not operating (when images are not being formed). A suction pump is connected to the suction cap 18b. The maintenance unit 27 also includes a wiper 19 for cleaning excess ink remaining on the nozzle surface of the head 10 and restoring the nozzle condition. Furthermore, at the other end side in the main scanning direction X, a discharge receiver 26 is disposed.

[0027] When image formation starts, the DTG printer moves the platen 61 to the image formation start position. Then, the carriage 20 moves once in the main scanning direction X while ejecting liquid from the head 10. When this single movement is completed, the DTG printer moves the platen 61 a predetermined amount in the Y direction to form the next image. The platen 61, which serves as a transport means, transports the medium intermittently in the sub-scanning direction Y in response to the scanning of the head 10.

[0028] In the following description, the operation of the platen 61 to transport the medium in the sub-scanning direction Y in response to the scanning of the head 10 is referred to as the "line feed operation." Additionally, the distance the medium moves in the sub-scanning direction Y in one line feed operation (movement distance per operation) is referred to as the "line feed amount."

[0029] <Configuration example of DTG printer> FIG. 1 is an explanatory diagram schematically showing the main components of the DTG printer according to the present embodiment. As shown in FIG. 11, the DTG printer of the present embodiment includes a plurality of heads 10 that discharge liquid onto a medium 50, a plurality of carriages 20 that mount the heads 10 and reciprocate in the main scanning direction X, and a conveying means 61 that intermittently conveys the medium in the sub-scanning direction in accordance with the scanning of the heads 10. The carriage 20 is held by a guide rod 21. In the following description, when a plurality of heads are collectively referred to, they are denoted as "head 10", when a plurality of carriages are collectively referred to, they are denoted as "carriage 20", and when a plurality of guide rods are collectively referred to, they are denoted as "guide rod 21".

[0030] The DTG printer of the present embodiment is an all-in-one type device that can continuously perform pre-treatment and printing with ink on the medium 50 in an integrated device. Hereinafter, an example in which the medium 50 is a black or dark-colored fabric will be described, but the medium 50 is not limited thereto.

[0031] The head 10 has a first head 11 that discharges a pretreatment liquid 31 from a nozzle, a second head 12 that discharges white ink 32 from a nozzle, and a third head 13 that discharges a colored ink other than white (hereinafter referred to as "color ink") 33 from a nozzle, and is arranged so as to be able to discharge the pretreatment liquid 31, white ink 32, and color ink 33 onto the medium 50 in this order. The notation "color ink 33" means any combination of colored inks other than white. The number of heads 10 is not limited to the example shown in FIG. 1 and can be any number. Also, the types of the third head 13 can be three colors or less, or five colors or more. Also, a configuration in which a plurality of heads discharge the same color ink may be adopted. The head 10 also includes an integrated type head unit mode in which the color of the liquid discharged for each nozzle row is different.

[0032] The first head 11 includes multiple nozzles and ejects a pretreatment liquid 31 from the nozzles onto the medium. The second head 12 includes multiple nozzles and ejects white ink 32 from the nozzles onto the medium 50. This forms a base region on the medium 50. The third head 13 includes multiple nozzles and ejects color inks 33 from the nozzles onto the region where the base has been formed. This forms an image. By forming an image on the base region formed by ejecting the white ink 32, it is possible to suppress deterioration in image quality.

[0033] 1, the multiple carriages include a first carriage 20a carrying a first head 11, a second carriage 20b carrying a second head 12, and a third carriage 20c carrying a third head 13. These are arranged in the following order from the upstream side in the transport direction of the medium 50: the first carriage 20a, the second carriage 20c, and the third carriage 20b.

[0034] The first carriage 20a is supported by a guide rod 21a, the second carriage 20b by a guide rod 21b, and the third carriage 20c by a guide rod 21c so as to be reciprocatable in the main scanning direction X, respectively. As the carriage 20 moves, the head 10 mounted thereon moves integrally in the main scanning direction X.

[0035] FIG. 2 is an explanatory diagram showing an example of the configuration of a plurality of heads 10 mounted on a carriage 20. As shown in FIG. "Configuration A" in Fig. 2(A) shows an example of a carriage 20 equipped with heads 13 that eject color inks 33. This is a combination of heads that eject the inks required for color printing, and specifically, a C (cyan) head 13a, an M (magenta) head 13b, a Y (yellow) head 13c, and a K (black) head 13d are mounted. The arrangement of the heads is not limited to this.

[0036] 2B shows an example of a carriage 20 equipped with a head 13 that ejects color ink 33. In addition to the combination of configuration A, special color heads 13e and 13f that eject special color inks (e.g., red, green, etc.) are also mounted. The special color inks are not particularly limited, and examples thereof include red, green, and additional color inks used in commercial printing, such as blue and orange, and low color density inks used in photo printing, such as light magenta, light cyan, and gray. The arrangement of the heads is not limited to this.

[0037] "Configuration C" in FIG. 2C shows an example of a carriage 20 equipped with a head 13 that ejects color ink 33. This is an example in which the combination of heads in configuration A is arranged symmetrically in the main scanning direction X. With this configuration, ejection can be performed without changing the order in which colors are overlaid in bidirectional printing in which ejection is performed on both the forward and return passes. Note that the arrangement order of the heads is not limited to this, as long as it is symmetrical in the main scanning direction X.

[0038] 2D shows an example of a carriage 20 on which a head 12 that ejects white ink 32 and a head 13 that ejects color ink 33 are mounted. In recent years, the miniaturization of heads and the increase in nozzle density have made it possible to integrate heads for base formation and image formation on the same carriage. In this case, the head 12 that ejects the white ink 32 needs to be disposed in the center of the carriage 20 so that the white ink 32 can be ejected onto the medium 50 before the color inks 33. The arrangement order of the heads 13 that eject the color inks 33 is not limited to this.

[0039] "Configuration E" in Fig. 2(E) shows an example of a carriage 20 on which a head 12 ejecting white ink 32 and a head 13 ejecting color inks 33 are mounted and arranged symmetrically in the main scanning direction X. In bidirectional printing, the head 12 ejecting white ink 32 needs to be arranged in the center of the carriage 20 so that the white ink 32 can be ejected before the color inks 33 onto the medium 50. The arrangement order of the heads 13 ejecting color inks 33 is not limited to this, as long as they are symmetrical in the main scanning direction X.

[0040] 2(F) shows an example of a carriage 20 equipped with a head 11 that ejects the pretreatment liquid 31 and a head 12 that ejects the white ink 32. In this case, the head 11 that ejects the pretreatment liquid 31 needs to be disposed in the center of the carriage 20 so that the pretreatment liquid 31 can be ejected onto the medium 50 before the white ink 32. Configuration F is selected when forming an image using multiple types of color inks including spot color inks. By adopting a carriage of configuration F, it becomes possible to mount multiple heads 13 on one or more other carriages 20.

[0041] Because the pre-treatment liquid 31 and the white ink 32 are reactive liquids, there is a risk of problems such as the liquid adhering to the nozzle surface reacting with and solidifying. For this reason, it is considered rare for the head 11 and head 12 to be mounted on the same carriage 20 as in configuration F. However, by using the maintenance unit 27 (see Figure 11) to scrape off dirt adhering to the nozzle surface with a wiper blade and to wipe the nozzle surface with a web impregnated with cleaning liquid, the nozzle condition can be restored and problems such as poor ejection can be prevented.

[0042] The carriage configuration of the DTP printer of this embodiment may be exemplified as follows, some of which are shown in FIG. (1) When there are two carriages One carriage is in configuration F, and the other carriage is in configuration A, configuration B, or configuration C (see FIG. 10(D)). One carriage is configured to carry only the head 11, and the other carriage is configured as configuration D or configuration F (see FIG. 10(B) and FIG. 10(C)). (2) Three carriages The first carriage is configured to carry only the head 11, the second carriage is configured to carry only the head 12, and the third carriage is configured to carry only the head 13 (see FIG. 10(A)). The first carriage is of configuration F, and the second carriage and the third carriage are of a configuration in which only the head 13 is mounted. The first carriage is configured to carry only the head 11, the second carriage is configured as configuration E or configuration F, and the third carriage is configured to carry only the head 13.

[0043] 3 and 4 are explanatory diagrams of the printing order and nozzle resolution of each head. "Nozzle resolution" is the distance between adjacent nozzles (nozzle pitch), and when forming an image in one pass, the nozzle resolution is the same as the nozzle pitch. The unit of resolution is dpi. The nozzle pitch is a unique value determined at the time of manufacture. The nozzle resolution is a value that can be changed by changing the head arrangement. The liquids are ejected onto the medium in the order of the pretreatment liquid, the white ink, and the color inks. That is, printing is performed by the head 11, printing by the head 12, and printing by the head 13. The head 11 has nozzles 41 for ejecting a pretreatment liquid, the head 12 has nozzles 42 for ejecting white ink, and the head 13 has nozzles 43 for ejecting color inks.

[0044] 3 shows an example of printing using heads with the same nozzle pitch. The pitch of the nozzles 41 of head 11, the pitch of the nozzles 42 of head 12, and the pitch of the nozzles 43 of head 13 are all the same before assembly. In response to this, the mounting positions of the heads 11 and 12 are shifted to increase the nozzle resolution of the heads 11 and 12.

[0045] On the other hand, FIG. 4 shows an example in which printing is performed using head 11, head 12, and head 13, which have different nozzle pitches. Since the pretreatment liquid, white ink, and color inks have different physical properties (viscosity, dispersibility of components, contact with head members, etc.), a head suitable for ejecting each liquid may be selected. In this case, if there is a difference in size between the heads as shown in Figure 4, it is preferable to provide an unused area as shown in Figure 4.

[0046] By making the nozzle resolution of the head arranged upstream in the direction in which the medium 50 is transported (sub-scanning direction Y) higher than the nozzle resolution of the head arranged downstream, it is possible to make the droplets ejected later land within the area printed earlier. It is also possible to prevent "missing" of droplets ejected later from landing on the desired position due to factors such as deflection of the jet or fluctuation in droplet volume.

[0047] As shown in Figures 3 and 4, when the nozzle resolution of the head 11 (first head) that ejects the pretreatment liquid is N1, the nozzle resolution of the head 12 (second head) that ejects the white ink is N2, and the nozzle resolution of the head 13 (third head) that ejects the color inks is N3, the DTP printer of this embodiment satisfies the relationship N1 ≧ N2 ≧ N3 and further satisfies the relationships N1 / N3 = m, N2 / N3 = n, m ≧ n (m and n are integers greater than or equal to 1).

[0048] Using the nozzle resolution N3 of the head 13 that ejects color inks (forms images) as a reference, the nozzle resolution N1 of the head 11 that ejects the pre-treatment liquid arranged upstream, and the nozzle resolution N2 of the head 12 that ejects the white ink that serves as the base, are each set to an integer multiple of N3, making it possible to create droplet ejection data by a simple enlargement process (such as simply copying the same data). On the other hand, if the nozzle resolutions N1 and N2 are not integer multiples of N3, different image magnification / image processing will be required for each of the pretreatment liquid, white ink, and color inks, which may increase the computational load and reduce productivity.

[0049] 5 and 6 are diagrams that diagrammatically show the process by which the ejected liquid permeates into the medium. As shown in Fig. 5(A), the fabric, which is the medium 50, has gaps 52 between tangled fibers 51. Therefore, as shown in Fig. 5(B), the discharged pre-treatment liquid 31 does not spread on the surface of the medium 50, but penetrates into the inside.

[0050] The subsequently discharged white ink 32 reacts with the previously discharged pretreatment liquid 31 and solidifies. However, if the head 12 has a defective nozzle and the discharge is deflected, the white ink 32 may not be discharged into the area where the pretreatment liquid 31 is applied, as shown in Fig. 5(C). If the white ink 32 that is not in the area where the pretreatment liquid 31 is applied does not solidify near the surface and permeates into the medium 50 (reference numeral 32a in Fig. 5(C)), a gap will occur in the base area.

[0051] In contrast, in the DTP printer of this embodiment, the nozzle resolution N1 of the head 11 (first head) that ejects the pretreatment liquid is made higher than the nozzle resolution N2 of the head 12 (second head) that ejects the white ink, so that the area to which the pretreatment liquid 31 is applied can be made wider, as shown in Figures 5 (D) and 5 (E), and it is possible to prevent the ejection of the white ink 32 from straying from that area.

[0052] On the other hand, when color ink 33 is discharged onto medium 50 in the state shown in Fig. 5(E), if there is a defective discharge nozzle in head 13 causing deflection of discharge, the color ink 33 may not be discharged into the base region formed by white ink 32, as shown in Fig. 6(A). Color ink 33 discharged outside the base region permeates into the medium 50, resulting in poor color development and poor fixability of the image. Furthermore, if the white color of the base region where color ink 33 was not discharged is exposed, it may cause noise in the image, leading to a deterioration in image quality.

[0053] In contrast to this, in the DTP printer of this embodiment, the nozzle resolution N1 of the head 11 (first head) that ejects the pretreatment liquid 31, the nozzle resolution N2 of the head 12 (second head) that ejects the white ink 32, and the nozzle resolution N3 of the head 13 (third head) that ejects the color inks 33 are set so as to satisfy at least the relationship N1≧N2≧N3, so that a base region of the white ink 32 is formed in the region where the pretreatment liquid 31 has been applied, and it is possible to prevent the ejection of the color inks 33 from straying from the base region, as shown in Figures 6(B), 6(C), and 6(D).

[0054] FIG. 7 is a diagram for explaining the line feed operation and the line feed amount in the printing process. It is believed that by arranging each head 10 so that the pretreatment liquid 31, white ink 32, and color ink 33 are ejected onto the medium 50 in that order, pretreatment liquid printing, white ink printing, and color ink printing can be performed sequentially in accordance with the transport of the medium 50. For example, in a line-type printer such as that described in Patent Document 1, even if the printing resolution of each head 10 is different, high-resolution printing can be achieved by controlling the print start timing and ejection frequency to match the transport speed of the medium 50.

[0055] On the other hand, when performing high-resolution printing with the serial-type DTP printer of this embodiment, multi-pass printing (multi-pass recording) is required, in which multiple main scanning operations are performed for each position on the medium 50. The amount of line feed per scan of the carriage 20 varies depending on the nozzle pitch and number of nozzles of each head 10 and the contents of the multi-pass printing sequence. For this reason, it is difficult to achieve sequential printing in accordance with the transport of the medium 50 simply by arranging each head 10 so that the pretreatment liquid 31, white ink 32, and color ink 33 are ejected in this order.

[0056] For example, if the line feed amount w is different for each head 10 (each carriage 20) (w1>w2>w3) as shown in Figure 7(A), overlapping printed areas will occur with head 11 (carriage 20a) with line feed amount w1, and unprinted areas will occur with head 13 (carriage 20c) with line feed amount w3.

[0057] Conventionally, this has been addressed by performing pretreatment liquid printing on the entire surface of the medium 50, reloading (pulling back) the medium 50, performing white ink printing, and then reloading the medium 50 again to perform color ink printing. However, this type of printing method requires a long time until printing is completed, and there is an issue that it is difficult to improve productivity.

[0058] In contrast, the DTG printer of this embodiment makes it possible to perform pre-processing, base formation, and color printing in one go in succession without reloading by matching the line feed amount w for each head 10 (each carriage 20) (setting w1 = w2 = w3) as shown in Figure 7 (B).

[0059] 8 is a diagram for explaining the idea of ​​matching the line feed amounts in a multi-pass printing sequence using heads with different nozzle resolutions, showing the case of printing at 600 dpi x 600 dpi as an example.

[0060] To perform high-resolution printing, a large number of scans (number of passes in the main scanning direction × number of interlaces in the sub-scanning direction) is required. In a mode in which the nozzle resolutions of the heads 10 are different, in order to match the line feed amounts, it is preferable that the nozzle resolutions of the heads 10 are in an integer multiple relationship. That is, the nozzle resolution N1 of the head 11 (first head) that ejects the pretreatment liquid 31, the nozzle resolution N2 of the head 12 (second head) that ejects the white ink 32, and the nozzle resolution N3 of the head 13 (third head) that ejects the color ink 33 are N1 / N3=m, N2 / N3=n, m≧n (m and n are integers equal to or greater than 1) It is preferable that the following relationship is satisfied. In other words, it is preferable that the nozzle resolution of the head on the most downstream side (head 13) and the nozzle resolution of the heads on the upstream side (head 11, head 12) have a common multiple relationship.

[0061] As a result, by multiplying the number of main scanning passes by h (h is an integer), it is possible to adjust the line feed amount to 1 / h. In the example of Fig. 8, by multiplying the number of main scanning passes of the head 11 ejecting the pretreatment liquid by four and doubling the number of main scanning passes of the head 12 ejecting the white ink, it is possible to match the line feed amount with that of the head 13 ejecting the color inks. If there are a fractional number of nozzles, these can be dealt with by setting them as unused nozzles (see FIG. 4).

[0062] By matching the total number of scans, the printing operations can be matched even when heads 10 with different nozzle resolutions are mounted on the same carriage 20.

[0063] When printing at a very high resolution, if the nozzle resolution of each head 10 is not an integer multiple, it is possible to approximate the line feed amount by adjusting the number of nozzles used, the number of passes in the main scanning direction, and the number of interlaces in the sub-scanning direction. However, if the line feed amount does not match perfectly, an error of one pitch (for example, 21 μm at a nozzle resolution of 1200 dpi) may occur. This error may cause white streaks (missing streaks) or black streaks (dark streaks caused by overlapping droplets) to form in the main scanning direction, degrading image quality.

[0064] 9 is a diagram showing the relationship between the line feed amount W and the arrangement interval L of each head 10 (each carriage 20). The arrangement interval is the distance between the centers of each head 10 (each carriage 20) in the sub-scanning direction Y. In order to perform pre-treatment, base formation, and color printing successively at high resolution, in addition to the above requirements, it is necessary to adjust the arrangement intervals of the heads 10 (carriages 20).

[0065] FIG. 9A shows an example in which the heads 10 (carriages 20) are arranged such that the arrangement interval L is an integer multiple of the line feed amount W of the head 13 that ejects the color ink 33. On the other hand, FIG. 9B shows an example in which the arrangement interval L of the heads 10 (carriages 20) is not an integer multiple of the line feed amount W of the head 13 that ejects the color ink 33.

[0066] 9A, the arrangement interval between head 11 (carriage 20a) and head 12 (carriage 20b), and the arrangement interval between head 12 (carriage 20b) and head 13 (carriage 20c) are in the relationship L = 2W. Because the arrangement interval L is an integer multiple of W (they have a common multiple relationship), the print position and the position of the head (carriage) match even if line feed operations are repeated.

[0067] 9B, the spacing between head 11 (carriage 20a) and head 12 (carriage 20b) and the spacing between head 12 (carriage 20b) and head 13 (carriage 20c) are L=2.5W and L=1.5W, respectively. Because the spacing L is not an integer multiple of W, repeated line feed operations cause the print position and the head (carriage) position to not match, resulting in the generation of unprinted areas. 9B, although the two arrangement intervals L are not an integer multiple of W, the difference between them is 1 / 2 of W, so it is possible to perform perfect printing by performing multi-pass recording with the line feed amount set to 1 / 2. However, if the arrangement intervals L are not a multiple of W, it is difficult to perform perfect image formation.

[0068] As in the example of FIG. 9A, by setting the arrangement interval L of each head 10 (each carriage 20) to an integer multiple of the line feed amount W, it is also possible to support higher-level print modes (high-image-quality modes). Generally, printing in high-quality mode has twice the resolution of printing in standard mode. To double the resolution in the transport direction, the number of interlaces must be doubled and the line feed amount must be halved, but if the arrangement interval of each head 10 (each carriage 20) is an integer multiple of the line feed amount, it becomes possible to perform pre-processing, base formation, and color printing in one go.

[0069] In addition, when the head 12 that ejects white ink and the head 13 that ejects color inks are mounted on the same carriage 20 as in the configuration D of Fig. 2(D) and the configuration E of Fig. 2(E) as the configuration of the multiple heads 10 mounted on the carriage 20, the arrangement distance L between the heads 12 and 13 can be considered to be 0. In addition, when the head 11 that ejects the pretreatment ink and the head 12 that ejects white ink are mounted on the same carriage 20 as in the configuration F of Fig. 2(F), the arrangement distance L between the heads 11 and 12 can be considered to be 0. In these embodiments, by controlling the head disposed in the center of the carriage to always eject first, it is possible to maintain the ejection order (the order of pretreatment liquid, white ink, and color ink) onto the medium 50. Specifically, in bidirectional printing, the ejection order can be adjusted by controlling the head that ejects between the forward scan and the return scan to be switched.

[0070] As described above, the DTG printer of this embodiment, which is a serial-type liquid ejection device capable of continuously performing pretreatment, base formation, and color printing in an integrated device, has the first head 11 that ejects the pretreatment liquid 31 from its nozzles, the second head 12 that ejects the white ink 32 from its nozzles, and the third head 13 that ejects colored inks other than white (color inks) 33 from its nozzles, and is arranged so that the pretreatment liquid 31, the white ink 32, and the color inks 33 can be ejected in this order onto the medium 50. When the nozzle resolution of the first head 11 is N1, the nozzle resolution of the second head 12 is N2, and the nozzle resolution of the third head 13 is N3, N1 ≥ N2 ≥ N3, and N1 / N3=m, N2 / N3=n, m≧n (m and n are integers equal to or greater than 1) It satisfies the relationship.

[0071] In the DTG printer of this embodiment, when the distance by which the platen 61 moves the medium 50 in the sub-scanning direction Y in response to scanning by the third head 13 is W, the arrangement interval between the first head 11 and the second head 12 in the sub-scanning direction Y is L1, and the arrangement interval between the second head 12 and the third head 13 in the sub-scanning direction Y is L2, L1 = W × p, L2 = W × q (p and q are integers equal to or greater than 0) It satisfies the relationship.

[0072] In the first aspect of this embodiment (Figure 10(A)) in which the DTG printer has three carriages, the three carriages consist of a first carriage 20a carrying the first head 11, a second carriage 20b carrying the second head 12, and a third carriage 20c carrying the third head 13, and are arranged in the order of the first carriage 20a, the second carriage 20b, and the third carriage 20c from the upstream side in the transport direction of the medium 50. Then, when the arrangement interval between the first carriage 20a and the second carriage 20b in the sub-scanning direction Y is L3, and the arrangement interval between the second carriage 20b and the third carriage 20c in the sub-scanning direction Y is L4, L3 = W × r, L4 = W × s (r and s are integers greater than or equal to 1) It fulfills the relationship.

[0073] In addition, in a second aspect of this embodiment in which the DTG printer has three carriages, the three carriages consist of a first carriage 20a carrying only the first head 11, a second carriage 20b carrying the second head 12 and the third head 13, and a third carriage 20c carrying only the third head 13, and are arranged in the order of the first carriage 20a, the second carriage 20b, and the third carriage 20c from the upstream side in the transport direction of the medium 50. Then, when the arrangement interval between the first carriage 20a and the second carriage 20b in the sub-scanning direction is L3, and the arrangement interval between the second carriage 20b and the third carriage 20c in the sub-scanning direction is L4, L3 = W × r, L4 = W × s (r and s are integers greater than or equal to 1) It fulfills the relationship. With this configuration, it is possible to mount heads for many different color inks.

[0074] In addition, in a third aspect of this embodiment in which the DTG printer has three carriages, the three carriages consist of a first carriage 20a carrying the first head 11 and the second head 12, and a second carriage 20b and a third carriage 20c carrying only the third head 13, and are arranged in the order of the first carriage 20a, the second carriage 20b, and the third carriage 20c from the upstream side in the transport direction of the medium 50. Then, when the arrangement interval between the first carriage 20a and the second carriage 20b in the sub-scanning direction is L3, and the arrangement interval between the second carriage 20b and the third carriage 20c in the sub-scanning direction is L4, L3 = W × r, L4 = W × s (r and s are integers greater than or equal to 1) It fulfills the relationship. With this configuration, it is possible to mount heads for many different types of color ink.

[0075] In a fourth aspect (FIGS. 10B and 10C) of the present embodiment in which the DTG printer has two carriages, the printer has a first carriage 20a carrying only the first head 11, and a second carriage 20b carrying the second head 12 and the third head 13. These carriages are arranged in the order of the first carriage 20a and the second carriage 20b from the upstream side in the transport direction of the medium 50. When the arrangement distance between the first carriage 20a and the second carriage 20b in the sub-scanning direction Y is L5, L5 = W × t (t is an integer equal to or greater than 1) It fulfills the relationship. By using two carriages, the length of the device in the sub-scanning direction Y can be shortened, making it possible to realize a compact and space-saving device.

[0076] In a fifth aspect (FIG. 10(D)) of this embodiment in which the DTG printer has two carriages, the printer has a first carriage 20a carrying the first head 11 and the second head 12, and a second carriage 20b carrying the third head 13. These carriages are arranged in the order of the first carriage 20a and the second carriage 20b from the upstream side in the transport direction of the medium 50. When the arrangement distance between the first carriage 20a and the second carriage 20b in the sub-scanning direction Y is L5, L5 = W × t (t is an integer equal to or greater than 1) It satisfies the relationship. By using two carriages, the length of the device in the sub-scanning direction Y can be shortened, making it possible to realize a compact and space-saving device.

[0077] According to the DTG printer of this embodiment, pretreatment, base formation, and color printing can be performed continuously in one go with an integrated device. Furthermore, image robustness and image quality can be improved.

[0078] Although the DTG printer has been described as an example of an embodiment of the present invention, the liquid ejection device according to the present invention is not limited to this. In addition, the medium is not limited to fabric such as clothing, and other materials can be selected as long as the liquid can be attached to the medium.

[0079] For example, aspects of the present invention are as follows. <1> A plurality of heads that eject liquid onto a medium; a plurality of carriages each carrying the head and reciprocating in a main scanning direction; a transport means for transporting the medium intermittently in a sub-scanning direction in response to scanning of the head, the heads include a first head that ejects a pretreatment liquid from a nozzle, a second head that ejects a white ink from a nozzle, and a third head that ejects a colored ink other than white from a nozzle, and are arranged so as to be capable of ejecting the pretreatment liquid, the white ink, and the colored ink in this order onto the medium; When the nozzle resolution of the first head is N1, the nozzle resolution of the second head is N2, and the nozzle resolution of the third head is N3, N1 ≥ N2 ≥ N3, and N1 / N3=m, N2 / N3=n, m≧n (m and n are integers equal to or greater than 1) Fulfilling the relationship, When the amount of line feed per one movement of the medium in the sub-scanning direction by the transport means in response to scanning by the third head is W, the arrangement interval between the first head and the second head in the sub-scanning direction is L1, and the arrangement interval between the second head and the third head in the sub-scanning direction is L2, L1 = W × p, L2 = W × q (p and q are integers equal to or greater than 0) The liquid ejection apparatus is characterized in that the following relationship is satisfied. <2> the plurality of carriages include a first carriage mounting the first head, a second carriage mounting the second head, and a third carriage mounting the third head, and are arranged in this order from the upstream side in a transport direction of the medium, in the order of the first carriage, the second carriage, and the third carriage; When the arrangement interval between the first carriage and the second carriage in the sub-scanning direction is L3, and the arrangement interval between the second carriage and the third carriage in the sub-scanning direction is L4, L3 = W × r, L4 = W × s (r and s are integers greater than or equal to 1) The above-mentioned embodiment satisfies the relationship: <1> The liquid ejection apparatus according to claim 1, <3> the plurality of carriages include a first carriage mounting only the first head, a second carriage mounting the second head and the third head, and a third carriage mounting the third head, and are arranged in this order from the upstream side in a transport direction of the medium in the order of the first carriage, the second carriage, and the third carriage; When the arrangement interval between the first carriage and the second carriage in the sub-scanning direction is L3, and the arrangement interval between the second carriage and the third carriage in the sub-scanning direction is L4, L3 = W × r, L4 = W × s (r and s are integers greater than or equal to 1) The above-mentioned embodiment satisfies the relationship: <1> The liquid ejection apparatus according to claim 1, <4> the plurality of carriages include a first carriage mounting the first head and the second head, and a second carriage and a third carriage mounting the third head, and are arranged in the order of the first carriage, the second carriage, and the third carriage from an upstream side in a transport direction of the medium, When the arrangement interval between the first carriage and the second carriage in the sub-scanning direction is L3, and the arrangement interval between the second carriage and the third carriage in the sub-scanning direction is L4, L3 = W × r, L4 = W × s (r and s are integers greater than or equal to 1) The above-mentioned embodiment satisfies the relationship: <1> The liquid ejection apparatus according to claim 1, <5> the plurality of carriages include a first carriage carrying the first head and a second carriage carrying the second head and the third head, and are arranged in the order of the first carriage and the second carriage from an upstream side in a transport direction of the medium; When the arrangement distance between the first carriage and the second carriage in the sub-scanning direction is L5, L5 = W × t (t is an integer equal to or greater than 1) The above-mentioned embodiment satisfies the relationship: <1> The liquid ejection apparatus according to claim 1, <6> the plurality of carriages include a first carriage carrying the first head and the second head, and a second carriage carrying the third head, and are arranged in the order of the first carriage and the second carriage from an upstream side in a transport direction of the medium; When the arrangement distance between the first carriage and the second carriage in the sub-scanning direction is L5, L5 = W × t (t is an integer equal to or greater than 1) The above-mentioned embodiment satisfies the relationship: <1> The liquid ejection apparatus according to claim 1, [Explanation of symbols]

[0080] 10 Head 11 First head (head that ejects pretreatment liquid) 12 Second head (head that ejects white ink) 13 3rd head (head that ejects color ink) 20 Carriage 21 Guide rod 31 Pretreatment solution 32 White Ink 33 Color Ink 50 Medium (fabric) [Prior art documents] [Patent documents]

[0081] [Patent Document 1] JP 2015-223721 A

Claims

1. A plurality of heads that eject liquid onto a medium; a plurality of carriages each carrying the head and reciprocating in a main scanning direction; a transport means for transporting the medium intermittently in a sub-scanning direction in response to scanning of the head, the heads include a first head that ejects a pretreatment liquid from a nozzle, a second head that ejects a white ink from a nozzle, and a third head that ejects a colored ink other than white from a nozzle, and are arranged so as to be capable of ejecting the pretreatment liquid, the white ink, and the colored ink in this order onto the medium; When the nozzle resolution of the first head is N1, the nozzle resolution of the second head is N2, and the nozzle resolution of the third head is N3, N1 ≧ N2 ≧ N3, and N1 / N3=m, N2 / N3=n, m≧n (m and n are integers of 1 or more) Fulfilling the relationship, When the amount of line feed per one movement of the medium in the sub-scanning direction by the transport means in response to scanning by the third head is W, the arrangement interval between the first head and the second head in the sub-scanning direction is L1, and the arrangement interval between the second head and the third head in the sub-scanning direction is L2, L1 = W × p, L2 = W × q (p and q are integers equal to or greater than 0) A liquid ejection apparatus which satisfies the relationship:

2. the plurality of carriages include a first carriage mounting the first head, a second carriage mounting the second head, and a third carriage mounting the third head, and are arranged in this order from the upstream side in a transport direction of the medium, in the order of the first carriage, the second carriage, and the third carriage; When the arrangement interval between the first carriage and the second carriage in the sub-scanning direction is L3, and the arrangement interval between the second carriage and the third carriage in the sub-scanning direction is L4, L3 = W × r, L4 = W × s (r and s are integers of 1 or more) 2. The liquid ejection apparatus according to claim 1, wherein the following relationship is satisfied:

3. the plurality of carriages include a first carriage mounting only the first head, a second carriage mounting the second head and the third head, and a third carriage mounting the third head, and are arranged in this order from the upstream side in a transport direction of the medium in the order of the first carriage, the second carriage, and the third carriage; When the arrangement interval between the first carriage and the second carriage in the sub-scanning direction is L3, and the arrangement interval between the second carriage and the third carriage in the sub-scanning direction is L4, L3 = W × r, L4 = W × s (r and s are integers of 1 or more) 2. The liquid ejection apparatus according to claim 1, wherein the following relationship is satisfied:

4. the plurality of carriages include a first carriage carrying the first head and the second head, and a second carriage and a third carriage carrying the third head, and are arranged in the order of the first carriage, the second carriage, and the third carriage from an upstream side in a transport direction of the medium, When the arrangement interval between the first carriage and the second carriage in the sub-scanning direction is L3, and the arrangement interval between the second carriage and the third carriage in the sub-scanning direction is L4, L3 = W × r, L4 = W × s (r and s are integers of 1 or more) 2. The liquid ejection apparatus according to claim 1, wherein the following relationship is satisfied:

5. the plurality of carriages include a first carriage mounting the first head and a second carriage mounting the second head and the third head, and are arranged in the order of the first carriage and the second carriage from an upstream side in a transport direction of the medium; When the arrangement distance between the first carriage and the second carriage in the sub-scanning direction is L5, L5 = W × t (t is an integer of 1 or more) 2. The liquid ejection apparatus according to claim 1, wherein the following relationship is satisfied:

6. the plurality of carriages include a first carriage carrying the first head and the second head, and a second carriage carrying the third head, and are arranged in the order of the first carriage and the second carriage from an upstream side in a transport direction of the medium, When the arrangement distance between the first carriage and the second carriage in the sub-scanning direction is L5, L5 = W × t (t is an integer of 1 or more) 2. The liquid ejection apparatus according to claim 1, wherein the following relationship is satisfied:

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