Inkjet printing device and inkjet head maintenance method

Abstract

To provide an inkjet printing device and an inkjet head maintenance method that facilitate maintenance.SOLUTION: [1] An inkjet printing device 100 includes: a conveyance cylinder 10 that conveys a printing medium P; and a plurality of inkjet heads 31 that discharge ink to the printing medium P. The plurality of inkjet heads 31 each include inkjet head angle fixation means 50 that fixes an installation angle, and further includes inkjet head movement means 70, 170 that independently move the plurality of inkjet heads 31 from the upper of the conveyance cylinder 10 to the upper outer of the conveyance cylinder 10. [2] An inkjet head maintenance method in which the plurality of inkjet heads 31 are moved to the upper outer of the conveyance cylinder 10, and a surface of the inkjet head 31 that has been moved to the upper outer of the conveyance cylinder 10, facing the printing medium P at the time of ink discharge becomes horizontal.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Inkjet printing is a method of directly ejecting ink from minute nozzles and depositing it on a printing medium to produce printed matter with characters and images. This method has many advantages, including being easy to produce full color, being inexpensive, and not contacting the printing medium, so in recent years it has been applied not only to consumer printing but also to commercial and industrial printing fields. In the fields of commercial printing and industrial printing, in order to increase productivity, high-speed inkjet printing is being considered, in which a linear fixed print head capable of printing across the entire width of the print medium is provided and a so-called single-pass method is used to continuously print on a roll of print medium. Inkjet printing is also widely used on flexible packaging films for packaging foods, etc. Specifically, printing is performed to display the name of the packaged product, etc., on flexible packaging films, which are thin, flexible resin printing media made of synthetic resins, etc. In recent years, in the field of printing, inkjet printing devices that use water-based inks containing pigments have been considered from the viewpoints of weather resistance, water resistance, and reducing the environmental impact of printed matter.

[0003] As inkjet printing continues, fine nozzles become clogged, requiring maintenance to unclog them. Since easy maintenance improves the productivity of printed materials, various studies are being conducted to improve the ease of maintenance during inkjet printing. For example, Patent Document 1 discloses a water-based ink for inkjet printing that is easy to maintain and contains polymer particles containing a pigment dispersed in a polymer dispersant (A), polymer particles containing a wax dispersed in a polymer dispersant (B), and an organic solvent, in which the acid value of the polymer constituting the wax-containing polymer particles is within a specific range and the melting point of the wax is equal to or higher than a specific temperature. Furthermore, Patent Document 2 discloses an image recording device with the aim of providing a technology that enables efficient switching between a maintenance state and other states with a simple configuration, in which, when the maintenance unit is in the maintenance position, it is capable of facing the print head that is in the maintenance position and performing the first maintenance on the print head, and when the maintenance unit is in the retracted position, there is space between the print head that is in the maintenance position and the maintenance unit, allowing manual second maintenance to be performed on the print head. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2023-6772 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-121800 Summary of the Invention [Problem to be solved by the invention]

[0005] Attempts to improve the maintainability of inkjet printing have been made by improving the ink used in inkjet printing devices, as in the invention described in Patent Document 1, or by improving the inkjet printing device, as in the invention described in Patent Document 2. An object of the present invention is to provide an inkjet printing apparatus and an inkjet head maintenance method that allow for easy maintenance through further improvements to the inkjet printing apparatus. [Means for solving the problem]

[0006] The present inventors have found that an inkjet printing device capable of easily performing maintenance can be provided by including inkjet head angle fixing means for fixing the installation angle of each of the plurality of inkjet heads and further including inkjet head moving means for individually moving each of the plurality of inkjet heads from on to off the transport drum. They have also found that an inkjet head maintenance method capable of easily performing maintenance can be provided by individually moving each of the plurality of inkjet heads from on to off the transport drum so that the surface of the inkjet head that has been moved off the transport drum that faces the printing medium is horizontal when ejecting ink can be provided. That is, the present invention provides the following [1] and [2]. [1] An inkjet printing device comprising: a base that serves as an installation reference; a transport drum that is installed on the base and transports a printing medium made of a long sheet of resin; and a plurality of inkjet heads that are arranged on the transport drum and eject ink toward the printing medium transported by the transport drum, wherein each of the plurality of inkjet heads is equipped with an inkjet head angle fixing means that fixes the installation angle, and further comprises inkjet head moving means that individually moves each of the plurality of inkjet heads from on the transport drum to off the transport drum. [2] An inkjet head maintenance method for maintaining the inkjet heads of an inkjet printing device that includes a transport drum that transports a printing medium made of a long sheet of resin, and a plurality of inkjet heads that are arranged on the transport drum and eject ink toward the printing medium transported by the transport drum, wherein the inkjet heads are individually moved onto and off the transport drum, and the surface of the inkjet head that has been moved onto and off the transport drum that faces the printing medium when ejecting ink is horizontal. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide an inkjet printing apparatus and an inkjet head maintenance method that allow maintenance to be performed easily. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic front view illustrating an example of the configuration of an inkjet printing apparatus according to a first embodiment. [Figure 2] 1A and 1B are schematic side views illustrating an example of operation of an inkjet printing device according to a first embodiment, in which sub-view (a) is a schematic side view illustrating a state in which an inkjet head is arranged on a transport drum, and sub-view (b) is a schematic side view illustrating a state in which the inkjet head has moved outside the transport drum. [Figure 3] FIG. 10 is a front view illustrating an inkjet head moving unit according to a second embodiment. [Figure 4] FIG. 10 is a side view illustrating an inkjet head moving unit according to a second embodiment. [Figure 5] FIG. 10 is a top view illustrating an inkjet head moving unit according to a second embodiment. [Figure 6] FIG. 10 is a top perspective view illustrating an inkjet head moving unit according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Preferred embodiments for carrying out the present invention will be described below with reference to the drawings. Note that the following embodiments do not limit the inventions according to the claims, and not all of the combinations of features described in the embodiments are essential to the solution of the invention.

[0010] First, a configuration example of an inkjet printing apparatus 100 according to a first embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a front view schematic diagram illustrating the configuration example of the inkjet printing apparatus according to the first embodiment. FIG. 2 is a side view schematic diagram illustrating an operation example of the inkjet printing apparatus according to the first embodiment. In the figure, sub-division (a) is a side view schematic diagram illustrating a state in which the inkjet head is disposed on the transport drum, and sub-division (b) is a side view schematic diagram illustrating a state in which the inkjet head has moved off the transport drum. For ease of explanation, the up-down direction and the front and back directions are defined based on the normal installation orientation of the inkjet printing apparatus 100 (200). Specifically, the downward direction is the base B side, i.e., the downward direction on the paper surfaces of FIGS. 1 to 3, and the upward direction is the upward direction. The front side of the paper surfaces of FIGS. 1 and 2 is the front, and the back side of the paper surfaces is the back.

[0011] [Inkjet printing apparatus 100 according to the first embodiment] As shown in Figures 1 and 2, the inkjet printing device 100 according to the first embodiment comprises a base B serving as an installation base, a transport drum 10 that is installed on the base B and transports a printing medium P made of a long sheet of resin, and a plurality of inkjet heads 31 that are arranged on the transport drum 10 and eject ink toward the printing medium P transported by the transport drum 10. Each of the plurality of inkjet heads 31 is equipped with an inkjet head angle fixing means 50 that fixes the installation angle, and further comprises an inkjet head moving means 70 that moves each of the plurality of inkjet heads 31 individually from on the transport drum 10 to outside the transport drum 10.

[0012] 1, the base B is a portion having a flat surface that serves as a reference for installing the conveying drum 10, etc. The base B may be a floor or a member having a flat surface, as long as it has a flat surface that serves as a reference for installing the conveying drum 10, etc.

[0013] Examples of printing media P made of long sheets of resin include transparent synthetic resin film sheets, such as polyester film sheets, vinyl chloride film sheets, polypropylene film sheets, polyethylene film sheets, and nylon film sheets. These film sheets may be biaxially oriented film sheets, uniaxially oriented film sheets, or unoriented film sheets. Among these, the printing medium P can be a polyester film sheet, an oriented polypropylene film sheet, a polyester film sheet such as a polyethylene terephthalate film sheet that has been surface-treated by corona discharge treatment, or a biaxially oriented polypropylene film sheet, or a film for flexible packaging of food, etc. The thickness and width of the printing medium P can be changed as appropriate depending on the intended use of the printed matter.

[0014] Commercially available transparent synthetic resin film sheets can be used, and examples of commercially available products include Lumirror T60 (manufactured by Toray Industries, Inc., polyethylene terephthalate), Taiko FE2001 (manufactured by Futamura Chemical Co., Ltd., corona-treated polyethylene terephthalate), E5100, E5102 (manufactured by Toyobo Co., Ltd., corona-treated polyethylene terephthalate), PVC80B P (manufactured by Lintec Corporation, polyvinyl chloride), KYNAS KEE70CA (manufactured by Lintec Corporation, polyethylene), YUPO SG90 PAT1 (manufactured by Lintec Corporation, polypropylene), FOR, FOR-AQ, FOS, FOS-AQ (manufactured by Futamura Chemical Co., Ltd., corona-treated polypropylene), P2161, P2111, DP053 (manufactured by Toyobo Co., Ltd., corona-treated polypropylene), U1 (manufactured by Tocello Co., Ltd., corona-treated polypropylene), and Bonyl RX (manufactured by Kohjin Film & Chemicals Co., Ltd., nylon).

[0015] The transport drum 10 is a member that is installed on the base B and that transports the print medium P. As the print medium P is transported by the transport drum 10, the print medium P is transported while remaining in close contact with the transport drum 10, enabling transport with high precision. As a result, the high impact precision required when forming high-resolution images using the inkjet printing method can be achieved. Although not particularly limited, the conveying drum 10 according to this embodiment is configured with a shaft 11 at its rotation center. The conveying drum 10 according to this embodiment is installed perpendicular to the base B and rotatably supported by a conveying drum rotation support part 13 that rotatably supports the shaft 11 of the conveying drum 10. Although not particularly limited, the conveying drum rotation support part 13 according to this embodiment is configured with a rectangular rotation support hole 13a at a position corresponding to the shaft 11 of the conveying drum 10, and the shaft 11 of the conveying drum 10 is inserted into the rotation support hole 13a and rotatably supported. Note that in this embodiment, a conveying drum rotation support part (not shown) is arranged on the back side of the conveying drum 10, similar to the front side, and both ends of the shaft 11 of the conveying drum 10 are rotatably supported by the conveying drum rotation support part 13. However, one end of the shaft 11 of the conveying drum 10 may be rotatably supported by the conveying drum rotation support part 13. Furthermore, the means for rotatably supporting the conveying drum 10 is not limited to these.

[0016] The diameter of the transport drum 10 is not particularly limited, and can be small from the viewpoint of achieving a compact inkjet printing apparatus 100. The width of the transport drum 10 is also not particularly limited, and can be small from the viewpoint of achieving a compact inkjet printing apparatus 100, and can be large from the viewpoint of being able to handle various printing media.

[0017] Although not particularly limited, the inkjet printing apparatus 100 according to this embodiment is configured with guide rollers 21 that guide the print medium P from a print medium supply unit (not shown) that supplies the print medium P to the transport drum 10. The print medium P printed by the printing unit 30 (described later) is collected in a print medium collection unit (not shown) that collects the print medium P. The print medium supply unit (not shown) is not particularly limited as long as it can supply the print medium P. The print medium collection unit (not shown) is also not particularly limited as long as it can collect the print medium P. The position and number of guide rollers 21 can be changed as appropriate. In this embodiment, the print medium P is supplied from the lower left of the page in FIG. 1 and collected toward the lower left of the page in FIG. 1, but these positions can also be changed as appropriate. Note that the means for guiding the print medium P from the print medium supply unit (not shown) to the transport drum 10 is not limited to the guide rollers 21. The print medium P may also be supplied from the print medium supply unit (not shown) to the transport drum 10 without being guided by a means for guiding the print medium P. Furthermore, a means for guiding the printing medium P from the transport drum 10 to a printing medium recovery section (not shown) may be provided, or the printing medium P may be recovered in a printing medium recovery section (not shown) without being guided by the above means.

[0018] The inkjet head 31 ejects ink toward the print medium P being transported by the transport drum 10. There are no particular limitations on the shape of the inkjet head 31, but it can be configured so that the surface that ejects ink tends to face downward due to the action of gravity (the center of gravity of the inkjet head 31 is located on the side of the surface that ejects ink, i.e., the lower side). With this configuration, the inkjet printing apparatus 100 according to this embodiment makes it easier to perform maintenance on the inkjet head 31, as will be described later.

[0019] The inkjet head 31 may be of a piezoelectric or thermal type, among others, and may be of a piezoelectric type in view of its applicability to a wide range of inks. The color of ink ejected from the inkjet head 31 is appropriately selected depending on the color of the printed matter. The ink color may be, for example, cyan, magenta, yellow, red, blue, orange, green, violet, black, or white.

[0020] For convenience of explanation, the inkjet printing apparatus 100 according to this embodiment is configured to include four inkjet heads 31 (31a, 31b, 31c, 31d), but is not limited to this. Furthermore, the arrangement positions and intervals of the inkjet heads 31 (31a, 31b, 31c, 31d) are not limited.

[0021] The inkjet heads 31 according to this embodiment can be arranged such that the angle between the base B and the extension line E, which extends perpendicularly from the surface of the inkjet head 31 facing the print medium P toward the center of the transport drum 10, is 0° or greater and 90° or less. This angle is defined as 0° when the extension line E extends perpendicularly from the surface of the inkjet head 31 facing the print medium P toward the center of rotation of the transport drum 10 and the base B. By arranging the inkjet heads 31 so that the angle between the base B and the extension line E, which extends perpendicularly from the surface of the inkjet head 31 facing the print medium P toward the center of rotation of the transport drum 10, is 0° or greater and 90° or less. This arrangement allows ink ejection from the inkjet head 31 to the print medium P to be more stable. The angle between the extension line E and the base B is an acute angle, except when the extension line E is parallel to the plane of the base B.

[0022] Furthermore, the multiple inkjet heads 31 according to this embodiment can be configured so that the angle between the base B and an extension line E, which is perpendicularly extended from the surface facing the print medium P toward the center of rotation of the transport drum 10, is different for each of them. With this configuration, for example, when two or more inkjet heads 31 with different ink colors are provided, it is easier to prevent ink mixture depending on the color and type of ink used, the type of print medium P, etc.

[0023] 1, an extension line E extending perpendicularly from the surface of inkjet head 31a facing the printing medium P toward the center of rotation of transport drum 10 is a parallel line PL that is parallel to base B (E=PL), and therefore the angle between extension line E extending perpendicularly from the surface of inkjet head 31a facing the printing medium P toward the center of rotation of transport drum 10 and base B is 0°. An extension line E (31b) extending perpendicularly from the surface of inkjet head 31b facing the printing medium P toward the center of rotation of transport drum 10 intersects with base B at the bottom right of the page in FIG. 1, and angle A (31b) in FIG. 1 is the angle between extension line E (31b) extending perpendicularly from the surface of inkjet head 31b facing the printing medium P toward the center of rotation of transport drum 10 and base B. An extension line E (31c) extending perpendicularly from the surface of inkjet head 31c facing the printing medium P toward the center of rotation of transport drum 10 intersects with base B perpendicularly, so the angle between base B and extension line E, extending perpendicularly from the surface of inkjet head 31c facing the printing medium P toward the center of rotation of transport drum 10, is 90°. Similar to inkjet head 31a, extension line E, extending perpendicularly from the surface of inkjet head 31d facing the printing medium P toward the center of rotation of transport drum 10, is parallel line PL that is parallel to base B (E=PL), so the angle between base B and extension line E, extending perpendicularly from the surface of inkjet head 31d facing the printing medium P toward the center of rotation of transport drum 10, is 0°.

[0024] Although not particularly limited, the inkjet head 31 according to this embodiment is configured with a connecting portion 33 on the opposite side (upstream side) of the transport direction of the printing medium P for connecting to an inkjet head moving unit 70 (described later). With this configuration, when a drying mechanism for drying ink ejected from the inkjet head 31 onto the printing medium P is installed, the distance from the inkjet head 31 can be determined arbitrarily, enabling precise control of the drying state of the ink ejected onto the printing medium P. More specifically, by shortening the distance between the inkjet head 31 and the drying mechanism, ink ejected onto the printing medium P can be quickly dried to prevent bleeding. Furthermore, for example, when two or more inkjet heads 31 each having different ink colors are installed, shortening the distance between the first inkjet head 31 and the drying mechanism allows ink of a different color to be ejected from another inkjet head 31 after the ink ejected onto the printing medium P from the first inkjet head 31 has sufficiently dried, making it easier to suppress ink mixing. It is also possible to increase the distance between the inkjet head 31 and the drying mechanism. Furthermore, with the above configuration, the inkjet head moving means 70 is less likely to become soiled with ink, and even if a drying mechanism for drying the ink ejected from the inkjet head 31 onto the printing medium P is disposed downstream of the inkjet head 31, the inkjet head moving means 70 is less likely to be affected by heat, etc., from the drying mechanism.

[0025] There are no particular limitations on the position or shape of the connecting part 33, as long as it can connect the inkjet head 31 and the inkjet head moving means 70. As will be described later, as long as the inkjet head 31 can be made horizontal after being moved from on the transport drum 10 to outside the transport drum 10, the inkjet head 31 may be directly installed and fixed to the inkjet head moving means 70, which will be described later, without providing the connecting part 33.

[0026] Although not particularly limited, the connecting portion 33 according to this embodiment is configured to include an inkjet head angle fixing means 50 for fixing the installation angle of the inkjet head 31. In this embodiment, the inkjet head angle fixing means 50 is installed above the connecting portion 33 of the inkjet head 31, but the installation position is not particularly limited as long as it can fix the installation angle of the inkjet head 31. Furthermore, as will be described later, as long as the inkjet head 31 can be made horizontal after moving from on the conveying drum 10 to off the conveying drum 10, the inkjet head angle fixing means 50 may be installed directly on the inkjet head 31, and the connecting portion 33 may not be provided.

[0027] The inkjet head angle fixing means 50 is not particularly limited as long as it can fix and release the inkjet head 31. More specifically, the inkjet head angle fixing means 50 is used to change and fix the angle of the surface of the inkjet head 31 that faces the base B or the transport cylinder 10 (the surface that ejects ink). By providing the inkjet head angle fixing means 50, the distance and angle between the ink ejecting surface of the inkjet head 31 and the base B or the transport cylinder 10 can be adjusted and fixed, making it easier to obtain better printed matter.

[0028] The inkjet head angle fixing means 50 according to this embodiment is not particularly limited, but is configured as a pin 51 that can fix the installation angle of the inkjet head 31 by inserting it into a hole (not shown) formed in at least the connecting portion 33. The pin 51 serving as the inkjet head angle fixing means 50 is configured so that the fixed installation angle of the inkjet head 31 can be released by removing it from the hole (not shown) formed in at least the connecting portion 33. Note that the hole for inserting the pin 51 serving as the inkjet head angle fixing means 50 may be formed so as to reach the inkjet head 31 in addition to the connecting portion 33.

[0029] The inkjet head moving means 70 is not particularly limited as long as it can move the inkjet head 31 from on the transport drum 10 to outside the transport drum 10. As shown in FIGS. 1 and 2 , the inkjet head moving means 70 according to this embodiment is configured to include, but is not limited to, a fixed inkjet head moving means 71 having a rectangular shape and a movable inkjet head moving means 73 having the same rectangular shape as the fixed inkjet head moving means 71. The fixed inkjet head moving means 71 is disposed on the opposite side (upstream side) of the movable inkjet head moving means 73 in the transport direction of the printing medium P. In other words, the movable inkjet head moving means 73 is disposed on the side (downstream side) of the fixed inkjet head moving means 71 in the transport direction of the printing medium P. As shown in FIG. 1 , although not particularly limited, the inkjet head 31 is attached to the movable inkjet head moving means 73 via a connecting portion 33.

[0030] As shown in FIG. 2 , the inkjet head moving means 70 according to this embodiment includes, but is not limited to, a slide mechanism 75 that is slidable in a direction perpendicular to the transport direction of the transport drum 10. The slide mechanism 75 according to this embodiment includes, but is not limited to, a slide guide member 77 that is disposed on the fixed inkjet head moving means 71 and extends in a direction perpendicular to the transport direction of the transport drum 10, and a recess (not shown) that is disposed on the fixed inkjet head moving means 71 side (upstream side) of the movable inkjet head moving means 73 and has a shape corresponding to the slide guide member 77. In this embodiment, the movable inkjet head moving means 73 slides along the slide guide member 77 disposed on the fixed inkjet head moving means 71, thereby allowing the inkjet head 31, which is attached to the movable inkjet head moving means 73 via the connecting member 33, to move from above the transport drum 10 to outside the transport drum 10. This configuration allows the inkjet printing apparatus 100 according to this embodiment to more easily perform maintenance on the inkjet head 31.

[0031] The slide mechanism 75 of the inkjet head moving means 70 is not limited to the one described above. For example, the fixed inkjet head moving means 71 may be larger than the movable inkjet head moving means 73 and may have a recess corresponding to the shape of the movable inkjet head moving means 73. The movable inkjet head moving means 73 may then be slidable along the recess of the fixed inkjet head moving means 71. Alternatively, the movable inkjet head moving means 73 may be larger than the fixed inkjet head moving means 71 and may have a recess corresponding to the shape of the fixed inkjet head moving means 71, so that the movable inkjet head moving means 73 is slidable along the fixed inkjet head moving means 71. Furthermore, the fixed inkjet head moving means 71 and the movable inkjet head moving means 73 may be connected via a slidable member such as a slide rail, so that the movable inkjet head moving means 73 is slidable. In other words, the fixed inkjet head moving means 71 and the movable inkjet head moving means 73 may be joined by a slidable member such as a slide rail.

[0032] The inkjet head moving means 70 according to this embodiment includes, but is not limited to, a slide mechanism fixing means 79 for fixing the slide mechanism. The slide mechanism fixing means 79 is not limited to any particular means as long as it can fix and unlock the slide mechanism 75. As shown in FIG. 1 , the slide mechanism fixing means 79 according to this embodiment includes, but is not limited to, a hole (not shown) formed from the upstream side of the fixed inkjet head moving means 71 to the fixed inkjet head moving means 71 and the movable inkjet head moving means 73, and a pin 81. In this embodiment, the movable inkjet head moving means 73, which slides along a slide guide member 77 arranged on the fixed inkjet head moving means 71, can be fixed or unlocked by inserting or removing the pin 81 into or from the hole (not shown). This configuration enables the inkjet printing apparatus 100 according to this embodiment to more reliably prevent unintended movement of the inkjet head 31. The holes (not shown) formed in the fixed-side inkjet head moving means 71 and the movable-side inkjet head moving means 73 may be through holes that pass through the fixed-side inkjet head moving means 71 and the movable-side inkjet head moving means 73, or may be holes that are drilled from the fixed-side inkjet head moving means 71 to partway along the movable-side inkjet head moving means 73.

[0033] More specifically, in this embodiment, when the tip of the inserted pin 81 reaches the hole formed in the movable inkjet head moving means 73, the movement of the movable inkjet head moving means 73 is restricted, and the movable inkjet head moving means 73 can be fixed. On the other hand, when the tip of the pin 81 does not reach the hole formed in the movable inkjet head moving means 73 but reaches the hole formed in the fixed inkjet head moving means 71, or when the pin 81 is completely removed from the movable inkjet head moving means 73 through the hole formed continuously in the fixed inkjet head moving means 71 and the movable inkjet head moving means 73, the fixed state of the movable inkjet head moving means 73 is released, and the movable inkjet head moving means 73 can be moved from above the transport drum 10 to outside the transport drum 10. In this embodiment, as the movable inkjet head moving means 73 moves, the inkjet head 31 connected to the movable inkjet head moving means 73 via the connecting portion 33 moves from above the transport drum 10 to outside the transport drum 10.

[0034] Then, the inkjet head 31 that has been moved onto and off the transport drum 10 as described above is released from fixation by the inkjet head angle fixing means 50, so that the surface that faces the print medium P when ink is ejected (the surface from which ink is ejected) becomes horizontal. More specifically, in this embodiment, although not particularly limited, when the pin 51 serving as the inkjet head angle fixing means 50 of the inkjet head 31 that has been moved onto and off the transport drum 10 is removed from at least a hole (not shown) formed in the connecting portion 33 to release the fixation of the installation angle of the inkjet head 31, the inkjet head 31 according to this embodiment is configured so that the surface that ejects ink toward the print medium P tends to face downward (the center of gravity of the inkjet head 31 is located on the ink ejection surface side, i.e., the lower side), and therefore, the surface that faces the print medium P when ink is ejected from the inkjet head 31 becomes horizontal due to gravity or the like, without any operation other than releasing the fixation by the inkjet head angle fixing means 50. In other words, in this embodiment, the surface of the inkjet head 31 that faces the print medium P when ejecting ink is made horizontal simply by releasing the inkjet head angle fixing means 50, without having to perform any operation to level the inkjet head 31. This makes it easier to perform maintenance on the inkjet head 31, especially on the ink ejection portion.

[0035] Specifically, as shown in FIG. 1 , inkjet head 31c is disposed so that its ink-ejecting surface is horizontal with respect to base B, but the other inkjet heads 31a, 31b, and 31d are disposed so that their ink-ejecting surfaces are not horizontal with respect to base B. When inkjet head 31c moves from on transport drum 10 to the outside of transport drum 10, the ink-ejecting surface of inkjet head 31c becomes horizontal. On the other hand, after the other inkjet heads 31a, 31b, and 31d move from on transport drum 10 to the outside of transport drum 10, they are released by inkjet head angle fixing unit 50, so that their ink-ejecting surfaces become horizontal. Therefore, according to the inkjet printing apparatus 100 of this embodiment, it is easy to suppress ink color mixing, which results in better printed matter and simplifies maintenance of inkjet heads 31.

[0036] As described above, the inkjet printing apparatus 100 according to this embodiment can be provided with a drying mechanism downstream of the multiple inkjet heads 31 for drying the printing medium P onto which ink has been ejected from the inkjet heads 31. A drying mechanism may be disposed downstream of each inkjet head 31, a drying mechanism may be disposed downstream of one inkjet head 31, a drying mechanism may be disposed downstream of two inkjet heads 31, or a drying mechanism may be disposed downstream of three inkjet heads 31, and this can be changed as appropriate depending on the color and type of ink used, the type of printing medium P, etc.

[0037] An example of the configuration of the inkjet printing apparatus 100 according to the first embodiment has been described above. Next, an inkjet head moving unit 170 according to a second embodiment will be described with reference to FIGS. 3 to 6. FIG. 3 is a front view illustrating the inkjet head moving unit, and FIG. 4 is a side view illustrating the inkjet head moving unit according to the second embodiment. FIG. 5 is a top view illustrating the inkjet head moving unit according to the second embodiment, and FIG. 6 is a top perspective view illustrating the inkjet head moving unit according to the second embodiment. For ease of description, the up / down direction and the front and rear directions are defined based on the normal installation direction of the inkjet printing apparatus 100. Specifically, the base B side, i.e., the downward direction on the paper surfaces of FIGS. 3, 4, and 6 and the rear direction on the paper surface of FIG. 5, are defined as the downward direction; the upward direction on the paper surfaces of FIGS. 3, 4, and 6 and the front direction on the paper surface of FIG. 5 are defined as the upward direction; the front side on the paper surfaces of FIGS. 3 and 6 and the left side on the paper surfaces of FIGS. 4 and 5 are defined as the front; and the rear side on the paper surfaces of FIGS. 3 and 6 and the right side on the paper surfaces of FIGS. 4 and 5 are defined as the rear direction. Furthermore, the same or similar components as those in the above-described embodiment may be denoted by the same reference numerals and descriptions thereof may be omitted.

[0038] [Inkjet head moving means 170 according to the second embodiment] As shown in FIGS. 3, 5 and 6, the inkjet head moving means 170 according to the second embodiment is configured to be connected to the inkjet head 31 via a connecting portion 33, although this is not particularly limited.

[0039] The inkjet head moving means 170 according to this embodiment is not particularly limited, but the connecting portion 33 and the inkjet heads 31 can be disposed at a position on the transport direction side (downstream side) of the print medium P. With this configuration, when a drying mechanism for drying ink ejected from the inkjet heads 31 onto the print medium P is installed, as described above, the distance from the inkjet heads 31 can be determined arbitrarily, enabling precise control of the drying state of the ink ejected onto the print medium P. More specifically, by shortening the distance between the inkjet heads 31 and the drying mechanism, the ink ejected onto the print medium P can be quickly dried to prevent bleeding. Furthermore, for example, when two or more inkjet heads 31 each having different ink colors are provided, shortening the distance between the first inkjet head 31 and the drying mechanism allows the ink ejected onto the print medium P from the first inkjet head 31 to be sufficiently dried before another inkjet head 31 ejects a different color ink, making it easier to suppress ink mixing. It is also possible to increase the distance between the inkjet heads 31 and the drying mechanism. Furthermore, with the above configuration, the inkjet head moving means 170 is less likely to become soiled with ink, and even if a drying mechanism for drying the ink ejected from the inkjet head 31 onto the printing medium P is disposed downstream of the inkjet head 31, the inkjet head moving means 170 is less susceptible to the effects of heat, etc., from the drying mechanism.

[0040] As shown in Figures 3 and 6, the connecting part 33 according to this embodiment is not particularly limited, but is configured to include a rotating connecting part 39 having an axis 37 that serves as a rotation axis when changing the angle of the inkjet head 31 and that rotates together with the inkjet head 31 around the axis 37, and a non-rotating connecting part 41 that is installed on the inkjet head moving means 170 and does not rotate together with the inkjet head 31.

[0041] Although not particularly limited, the rotary connector 39 according to this embodiment is disposed on the underside of the inkjet head 31 and is attached to a nozzle plate 35 having nozzles for ejecting ink. More specifically, although not particularly limited, the rotary connector 39 is disposed on an end of the nozzle plate 35 of the inkjet head 31, at a position opposite (upstream) the inkjet head 31 in the transport direction of the print medium P. An inkjet head angle fixing unit 50 for fixing the installation angle of the inkjet head 31 is disposed on the rotary connector 39. Note that if the inkjet head 31 does not include a nozzle plate 35, the rotary connector 39 may be disposed, for example, on the surface of the inkjet head 31 opposite (upstream) the transport direction of the print medium P. Furthermore, although the inkjet head 31 according to this embodiment is configured to have a rectangular prism shape, the shape and the like are not particularly limited.

[0042] 5 and 6, the inkjet head angle fixing means 50 according to this embodiment is configured as a clamp lever 53 that is inserted into a hole (not shown), but as described above, the inkjet head angle fixing means 50 is not particularly limited as long as it can fix and release the inkjet head 31. In this embodiment, the clamp lever 53 serving as the inkjet head angle fixing means 50 is disposed at the upper end of the rotary connecting portion 39, but the position where it is disposed is not particularly limited.

[0043] In this embodiment, when the gripping portion 55 of the clamp lever 53 serving as the inkjet head angle fixing means 50 is turned, the screw in the clamp lever 53 is fastened or released, and the rotary coupling 39 on which the clamp lever 53 is disposed and the inkjet head 31 connected to the rotary coupling 39 rotate about the axis 37, thereby adjusting the angle of the ink ejection surface of the inkjet head 31 relative to the base B or the transport drum 10. When the gripping portion 55 of the clamp lever 53 serving as the inkjet head angle fixing means 50 is turned and the screw in the clamp lever 53 is fastened, the inkjet head 31 and the rotary coupling 39 connected to the inkjet head 31 are fixed at the desired angle. This configuration makes it easier to adjust the distance and angle between the printing medium P and the ink ejection surface of the inkjet head 31, thereby facilitating the production of better printed matter. The order in which the screw in the clamp lever 53 is fastened and released is not limited to the above.

[0044] Although not particularly limited, the non-rotating coupling 41 according to this embodiment is configured to include a non-rotating member 43 through which the shaft 37 serving as the rotation axis of the rotating coupling 39 and the inkjet head 31 passes, and which does not rotate together with the rotating coupling 39 and the inkjet head 31. In this embodiment, coupling the rotating coupling 39 and the inkjet head moving means 170 via the shaft 37 and the non-rotating member 43 makes the rotation of the inkjet head 31 and the rotating coupling 39 smoother and makes it difficult for the energy caused by the rotation of the inkjet head 31 and the rotating coupling 39 to be transmitted to the inkjet head moving means 170, thereby extending the life of the device.

[0045] As shown in Figures 3, 5 and 6, the inkjet head moving means 170 according to this embodiment is configured to include, but is not limited to, a slide mechanism 175 that can slide in a direction perpendicular to the conveying direction of the conveying drum 10, and a slide mechanism fixing means 179 that fixes the slide mechanism 175.

[0046] As shown in Figures 5 and 6, the slide mechanism 175 of this embodiment is not particularly limited to, but is configured to include a slide guide member 177 extending in a direction perpendicular to the conveying direction of the conveying drum 10, a slide member 83 having a shape corresponding to the slide guide member 177 and capable of sliding relative to the slide guide member 177, and a slide plate 85 supported by the slide member 83.

[0047] 5, slide guide member 177 extends in a direction perpendicular to the conveying direction of conveying drum 10 and is a member for guiding slide member 83. Slide guide member 177 according to this embodiment is configured to have, on its upper surface, a recess 177a extending in a direction perpendicular to the conveying direction of conveying drum 10, although this is not particularly limited.

[0048] The shape of the slide member 83 is not particularly limited as long as it has a shape corresponding to the slide guide member 177 and is slidable relative to the slide guide member 177. As shown in FIG. 6, the slide member 83 according to this embodiment has, although not particularly limited to, a convex portion 83a corresponding to the concave portion 177a of the slide guide member 177 and has a substantially rectangular shape. Furthermore, in this embodiment, although not particularly limited, two slide members 83, 83 are configured to be slidable relative to the slide guide member 177. By arranging two or more slide members 83, the slide plate 85, the connecting portion 33 and the inkjet head 31 mounted on the slide plate 85 can be more stably supported.

[0049] The slide plate 85 is a plate-like member supported by the slide member 83. As shown in Figures 3, 5, and 6, the slide plate 85 according to this embodiment is, although not limited to, installed on the surface of the two slide members 83, 83 that faces in the transport direction of the print medium P (downstream side). The non-rotating connecting portion 41 of the connecting portion 33 is installed on the surface of the slide plate 85 that faces in the transport direction of the print medium P (downstream side).

[0050] That is, although not particularly limited, in this embodiment, the rotary connecting portion 39 and non-rotary connecting portion 41 that constitute the connecting portion 33 are disposed on the opposite side (upstream side) of the inkjet head 31 from the transport direction of the print medium P. Furthermore, the slide plate 85 of the inkjet head moving means 170 is fixedly installed on the non-rotary connecting portion 41 on the opposite side (upstream side) of the inkjet head 31 from the transport direction of the print medium P. Furthermore, the surface of the slide member 83 that faces the transport direction of the print medium P (downstream side) is fixedly installed on the opposite side (upstream side) of the slide plate 85 from the transport direction of the print medium P. Furthermore, the convex portion 83a of the slide member 83 engages with the concave portion 177a of the slide guide member 177, so that the slide member 83 is slidable relative to the slide guide member 177. Therefore, although not particularly limited, in this embodiment, of the inkjet head moving means 170, only the slide guide member 177 is fixedly installed and does not move in a direction perpendicular to the transport direction, while the slide member 83 and the slide plate 85 are configured to move in a direction perpendicular to the transport direction. The slide guide member 177 can be fixed to the wall surface of the device or the like.

[0051] The inkjet head moving means 170 of this embodiment makes it easier to adjust the distance and angle between the printing medium P and the surface of the inkjet head 31 from which the ink is ejected, making it easier to obtain better printed matter and extending the life of the device.

[0052] While the preferred embodiments of the present invention have been described above, the technical scope of the present invention is not limited to the scope described in the above embodiments. Various modifications and improvements can be made to the above embodiments. For example, in the above-described embodiment, a long sheet made of resin is used as the printing medium P, but it is also possible to use paper, a laminate of paper and resin, or the like as the printing medium P. Furthermore, the inkjet printing device 100 may be configured so that the ink ejection surface faces downward due to the action of gravity (the center of gravity of the inkjet head 31 is located on the ink ejection surface side, i.e., on the lower side), and may be provided with a corona treatment device. The corona treatment device may be disposed, for example, between the printing medium P being supplied from a printing medium supply unit (not shown) to the guide roller 21. Furthermore, for example, in the above-described embodiment, the inkjet head moving means 70, 170 is arranged on the opposite side (upstream side) of the inkjet head 31 from the transport direction of the printing medium P, but it may also be arranged on the transport direction side (downstream side) of the printing medium P. Alternatively, for example, the inkjet head 31 may be configured so that the surface that ejects ink tends to face downward due to the effect of gravity (the center of gravity of the inkjet head 31 is located on the side of the surface that ejects ink, i.e., the lower side), and the inkjet printing device 100 may not include the inkjet head angle fixing means 50, and may be configured so that when the inkjet head 31 is moved from above the transport drum 10 to outside the transport drum 10 by the inkjet head moving means 70, 170, the surface that faces the print medium P when the ink is ejected from the inkjet head 31 becomes horizontal. In this case, simply by moving the inkjet head 31 from above the transport drum 10 to outside the transport drum 10, the surface that faces the print medium P when the ink is ejected from the inkjet head 31 becomes horizontal, making maintenance of the inkjet head 31 easier.

[0053] Next, the inkjet printing method of the present invention will be described. Components that are the same as or similar to those in the above-described embodiment will be given the same reference numerals, and descriptions thereof may be omitted.

[0054] [Inkjet head maintenance method] The inkjet head maintenance method of the present invention is a method for maintaining the inkjet heads of an inkjet printing device 100 that includes a transport drum 10 that transports a printing medium P made of a long sheet of resin, and a plurality of inkjet heads 31 that are arranged on the transport drum 10 and eject ink toward the printing medium P transported by the transport drum 10, in which the plurality of inkjet heads 31 are individually moved onto and off the transport drum 10 so that the surface of the inkjet head 31 that has been moved onto and off the transport drum 10 is horizontal when ejecting ink. Note that the inkjet head maintenance method of the present invention may use the inkjet printing device 100 described above, or other inkjet printing devices.

[0055] As described above, examples of the printing medium P include transparent synthetic resin film sheets, such as polyester film sheets, vinyl chloride film sheets, polypropylene film sheets, polyethylene film sheets, and nylon film sheets. These film sheets may be biaxially oriented film sheets, uniaxially oriented film sheets, or unoriented film sheets. Among these, the printing medium P may be a polyester film sheet or an oriented polypropylene film sheet, or a polyester film sheet such as a polyethylene terephthalate film sheet that has been surface-treated by corona discharge treatment or the like, or a biaxially oriented polypropylene film sheet, or a film for soft packaging of food, etc.

[0056] The step of moving each of the inkjet heads 31 individually onto and off the transport drum 10 can be performed using, for example, the slide mechanisms 75, 175, as described above. The step of ensuring that the surface of the inkjet head 31 that faces the print medium P when ejecting ink is horizontal after being moved onto and off the transport drum 10 can be performed using, for example, the inkjet head angle fixing means 50, as described above. Alternatively, the inkjet heads 31 may be configured so that the surface that ejects ink tends to face downward due to the action of gravity (the center of gravity of the inkjet head 31 is located on the ink ejecting surface side, i.e., the lower side), as described above, and the inkjet printing apparatus 100 may not include the inkjet head angle fixing means 50, and may be configured so that the inkjet heads 31 become horizontal when they are moved onto and off the transport drum 10.

[0057] The inkjet head maintenance method according to this embodiment makes it easy to perform maintenance of the inkjet head 31, particularly the ink ejection surface, by making the surface facing the printing medium P horizontal when the inkjet head 31 is moved outside onto the transport drum 10 and ejects ink. [Explanation of symbols]

[0058] 100: Inkjet printing device, 10: conveying drum, 11: shaft, 13: conveying drum rotation support part, 13a: rotation support hole, 21: Guide roller, 31: inkjet head, 33: connecting portion, 35: nozzle plate, 37: rotating shaft, 39: rotating connecting portion, 41: non-rotating connecting portion, 43: non-rotating member, 50: Inkjet head angle fixing means, 51: Pin, 53: Clamp lever, 55: Grip portion, 70, 170: inkjet head moving means, 71: fixed side inkjet head moving means, 73: movable side inkjet head moving means, 75, 175: slide mechanism, 77, 177: slide guide member, 177a: recessed portion (of slide guide member), 79, 179: slide mechanism fixing means, 81: pin, 83: slide member, 83a: protruding portion (of slide member), 85: slide plate, B: Base, E: Extension line, P: Printing medium, PL: Parallel line

Claims

1. A base that serves as the installation standard, a transport cylinder that is placed on the base and transports a printing medium made of a long sheet of resin; a plurality of inkjet heads disposed on the transport cylinder and configured to eject ink toward the print medium transported by the transport cylinder; An inkjet printing apparatus comprising: Each of the inkjet heads includes an inkjet head angle fixing unit that fixes the installation angle, and an inkjet head moving means for individually moving each of the inkjet heads from on the conveying drum to on the conveying drum; Inkjet printing device.

2. 2. The inkjet printing apparatus according to claim 1, wherein the inkjet head that has been moved onto the transport cylinder and out of position is released from the inkjet head angle fixing means, so that the surface of the inkjet head that faces the printing medium when ejecting ink becomes horizontal.

3. 3. The inkjet printing apparatus according to claim 1, wherein the inkjet head moving means comprises a slide mechanism that is slidable in a direction perpendicular to the transport direction of the transport cylinder.

4. 4. The inkjet printing apparatus according to claim 3, wherein the slide mechanism comprises a slide guide member extending in a direction perpendicular to the transport direction of the transport drum, a slide member having a shape corresponding to the slide guide member and slidable relative to the slide guide member, and a slide plate supported by the slide member.

5. The inkjet printing apparatus according to claim 4 , further comprising a slide mechanism fixing means for fixing the slide mechanism.

6. 3. The inkjet printing device according to claim 1, wherein when the angle between the base and an extension line extending perpendicularly from a surface of the inkjet head facing the printing medium toward the center of rotation of the transport drum when the ink is ejected from the inkjet head is defined as 0°, the angle between the base and an extension line extending perpendicularly from a surface of the inkjet head facing the printing medium toward the center of rotation of the transport drum when the ink is ejected from the inkjet head is between 0° and 90°.

7. 7. The inkjet printing device according to claim 6, wherein the angles between the base and an extension line extending perpendicularly from a surface of the inkjet heads facing the printing medium toward the center of rotation of the transport drum when the ink is ejected from each of the inkjet heads are different.

8. 3. The inkjet printing apparatus according to claim 1, wherein the printing medium is a flexible packaging film.

9. a conveying drum for conveying a printing medium made of a long sheet of resin; a plurality of inkjet heads disposed on the transport cylinder and configured to eject ink toward the print medium transported by the transport cylinder; 1. An inkjet head maintenance method for maintaining an inkjet head of an inkjet printing device comprising: The inkjet heads are individually moved onto and out of the conveying drum, a surface of the inkjet head that has been moved onto the outside of the transport cylinder and that faces the printing medium becomes horizontal when the ink is ejected from the inkjet head; Inkjet head maintenance method.

10. The inkjet head maintenance method according to claim 9 , wherein the direction in which the inkjet heads are individually moved onto and out of the transport cylinder is a direction perpendicular to the transport direction of the transport cylinder.

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