Liquid ejection head, liquid ejection unit, and liquid ejection device

Abstract

To provide a liquid discharge head capable of reducing an affection of an air current caused by media transport or head scanning.SOLUTION: There is provided a liquid discharge head comprising a nozzle plate on which, a plurality of nozzles is formed on a plane which is formed of a first direction and a second direction which is orthogonal to the first direction. The second direction is defined as a direction where the plurality of nozzles is arranged at equal intervals at a prescribed pitch corresponding to recording resolution, then, the plurality of nozzle rows formed of the nozzles are formed on the nozzle plate in an inclined state to the first direction. In the plurality of nozzle rows, when a virtual line connecting one end parts of the plurality of adjacent nozzle rows and having the same number of the nozzles, is defined as a first virtual line, on one end part of the nozzle plate in the second direction, a beginning position of the nozzle row is arranged closer to the other end part side of the nozzle row which is separated from the first virtual line.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present invention relates to a liquid ejection head, a liquid ejection unit, and a liquid ejection apparatus. [Background technology]

[0002] Patent Document 1 discloses a droplet ejection head configured by connecting together a plurality of head modules, each of which has a plurality of nozzles for ejecting liquid.

[0003] Patent Document 2 discloses an inkjet head configured by arranging a plurality of actuator units each having a parallelogram-shaped external shape. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-173264 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-160566 Summary of the Invention [Problem to be solved by the invention]

[0005] In a configuration such as that disclosed in Patent Document 1, it is difficult to provide a large space between the joints of multiple head modules and the nozzle region where the nozzles are formed, which poses a problem of low head robustness.

[0006] In a configuration such as that described in Patent Document 2, it is difficult to provide a large space between the joints of multiple actuator units and the nozzle region where nozzles are formed within the actuator unit, which poses a problem of low head robustness.

[0007] It should be noted that Patent Documents 1 and 2 do not suggest the influence of air currents generated by paper transport and head scanning on the liquid ejected from the head. [Means for solving the problem]

[0008] The present invention provides a liquid ejection head including a nozzle plate in which a plurality of nozzles are formed on a plane formed by a first direction and a second direction orthogonal to the first direction, wherein when the second direction is defined as a direction in which the plurality of nozzles are aligned at equal intervals at a predetermined pitch corresponding to a recording resolution, a plurality of nozzle arrays constituted by the plurality of nozzles are formed in the nozzle plate at an angle with respect to the first direction, and when a virtual line connecting one end of a plurality of adjacent nozzle arrays having the same number of nozzles is defined as a first virtual line, at one end of the nozzle plate in the second direction, a leading position of the nozzle array has a first portion located on the other end side of the nozzle array, away from the first virtual line. and when a virtual line connecting the other ends of adjacent nozzle rows having the same number of nozzles is defined as a second virtual line, the nozzle plate has a second portion at the other end in the second direction where a rear position of the nozzle row is positioned outside and beyond the second virtual line. It is a liquid ejection head. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a liquid ejection head that can reduce the influence of air currents caused by medium transport or head scanning. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram illustrating an example of a liquid ejection device. [Figure 2] FIG. 2 is an explanatory diagram showing an example of a head unit. [Figure 3] FIG. 2 is a schematic exploded view showing an example of a head. [Figure 4] FIG. 3 is an explanatory diagram showing an example of a flow path portion of a head. [Figure 5] FIG. 3 is a cross-sectional perspective view showing an example of a flow path portion of a head. [Figure 6] FIG. 10 is an explanatory diagram showing a head of a comparative example. [Figure 7] FIG. 10 is an explanatory diagram showing a state in which a plurality of heads according to a comparative example are arranged side by side. [Figure 8] FIG. 10 is an explanatory diagram illustrating the bending of ejected droplets. [Figure 9] FIG. 1 is an explanatory view of a head according to a first embodiment of the present invention. [Figure 10] FIG. 4 is an explanatory diagram showing the transition of the number of nozzles in a nozzle row in the longitudinal direction of a nozzle plate in the first embodiment. [Figure 11] FIG. 3 is an explanatory diagram showing a state in which a plurality of heads are arranged in the first embodiment. [Figure 12] FIG. 3 is an explanatory diagram showing a head connecting portion of the first embodiment. [Figure 13] FIG. 6 is an explanatory view of a head according to a second embodiment of the present invention. [Figure 14] FIG. 10 is an explanatory diagram showing the transition of the number of nozzles in a nozzle row in the longitudinal direction of a nozzle plate in the second embodiment. [Figure 15] FIG. 10 is an explanatory diagram showing a state in which a plurality of heads are arranged in a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the description of the drawings, the same elements are given the same reference numerals, and duplicated explanations will be omitted.

[0012] <Outline of liquid ejection device> First, an overview of a liquid ejection device will be explained using Fig. 1. Fig. 1 is a schematic diagram showing an example of a liquid ejection device. The illustrated liquid ejection device is a printing device that ejects ink onto paper using an inkjet method to form an image on the paper.

[0013] The printing device 500 includes a paper feed unit 501, a transport unit 503, a printing unit 505, a drying unit 507, and a paper discharge unit 509. The paper feed unit 501 includes a holding roller 511 that holds a roll of paper 510, and supplies the long, continuous paper 510 to the printing unit 505. The transport unit 503 performs, for example, tension control and meandering correction on the paper 510 supplied from the paper feed unit 501, adjusting the tension and transport position of the paper 510, and transports the paper 510 to the printing unit 505.

[0014] The printing unit 505 includes an inkjet recording unit 550 equipped with a head unit 555, and a transport guide member 559 facing the inkjet recording unit 550. The printing unit 505 forms an image on the paper 510 by ejecting ink from the head unit 555 onto the paper 510 moving on the transport guide member 559.

[0015] The number of head units 555 mounted in the inkjet recording section 550 may be increased or decreased as appropriate depending on the number and types of ink colors used in the printing device 500. The liquid used in the head units 555 is not limited to ink, and may include a treatment liquid for modifying the surface of the paper 510, or a coating agent for protecting the image formed on the paper 510.

[0016] The drying unit 507 heats the paper 510 carrying the image, and dries the paper 510 and the image formed on the paper 510. The paper discharge unit 509 includes a winding roller 591 that winds up the paper 510, and winds up the paper 510 sent out from the drying unit 507.

[0017] The following description will be based on the configuration of the printing apparatus 500 described above, but the liquid ejection apparatus according to the present invention is not limited to printing apparatuses. For example, the present invention can be applied to a three-dimensional modeling apparatus (three-dimensional modeling apparatus) that ejects a modeling liquid onto a powder layer formed by forming a layer of powder in order to form a three-dimensional object (a three-dimensional object). The present invention can also be applied to an electronic element production apparatus that ejects a resist pattern forming liquid to form a resist pattern for an electronic circuit.

[0018] Furthermore, the medium is not limited to paper 510. In addition to paper, various materials can be used, such as fiber, fabric, leather, metal, plastic, glass, wood, and ceramics. The form of the medium is also not limited to a long object, and may be a medium cut to a predetermined size.

[0019] Furthermore, the printing device 500 has been exemplified as a so-called line-type device configuration in which the paper 510 is moved relative to the inkjet recording unit 550 at a fixed position and an image is formed on the paper 510, but the configuration is not limited to the line-type. Any configuration is possible as long as the inkjet recording unit 550 and the paper 510 are moved relative to each other. Therefore, for example, a so-called serial-type device configuration may be used in which the inkjet recording unit is moved in a direction perpendicular to the paper feed direction relative to the paper that is fed intermittently and an image is formed on the paper 510. Alternatively, a so-called flatbed-type device configuration may be used in which the inkjet recording unit is moved in the X and Y directions relative to the paper held on a paper loading table and an image is formed on the paper 510.

[0020] Examples of materials used in liquid ejection devices include solutions, suspensions, emulsions, and the like containing solvents such as water or organic solvents, colorants such as dyes or pigments, polymerizable compounds, resins, surfactants, and other functional materials, biocompatible materials such as DNA, amino acids, proteins, and calcium, and edible materials such as natural dyes. Liquids may also contain fine powders such as metal powders. These can be used in applications such as inkjet inks, coating materials, surface treatment solutions, liquids for forming components of electronic elements and light-emitting elements, and electronic circuit resist patterns, and liquid materials for three-dimensional modeling.

[0021] <Head unit configuration> Next, the configuration of the head unit will be described using Fig. 2. Fig. 2 is an explanatory diagram showing an example of a head unit, and is a diagram of one of the eight head units 555 shown in the inkjet recording section 550 in Fig. 1, viewed from the transport guide member 559 side.

[0022] The head unit 555 includes a plurality of heads 1a, 1b, 1c, and 1d that are arranged adjacent to each other in a direction perpendicular to the medium feed direction. Hereinafter, these heads 1a to 1d will be collectively referred to as "head 1." In this embodiment, the "direction perpendicular to the medium feed direction" roughly coincides with the "second direction" (the direction in which multiple nozzles are arranged at equal intervals at a predetermined pitch corresponding to the recording resolution) described below. Furthermore, the "medium feed direction" roughly coincides with the "first direction" (the direction perpendicular to the second direction) described below.

[0023] Heads 1a to 1d include liquid ejection units 101a to 101d, nozzle plate holding members 102a to 102d, and mount members 103a to 103d. Hereinafter, the liquid ejection units 101a to 101d will be collectively referred to as "liquid ejection unit 101," the nozzle plate holding members 102a to 102d will be collectively referred to as "nozzle plate holding member 102," and the mount members 103a to 103d will be collectively referred to as "mount member 103."

[0024] The liquid ejection unit 101 of the head 1 includes a nozzle plate 10 having an outline shaped like a parallelogram, and the nozzle plate 10 has a nozzle surface 12 in which nozzles 11 for ejecting liquid are formed. Note that while some of the nozzles 11 are not shown in Figure 2, in reality, nozzles 11 are also formed in blank areas of the nozzle surface 12. The nozzle plate 10 is held by a nozzle plate holding member 102. The nozzle plate holding member 102 includes a mount member 103 on a part thereof, and by attaching the mount member 103 to a support member 550a provided on the inkjet recording unit 550, the head unit 555 is fixed to the inkjet recording unit 550.

[0025] <Head configuration> Next, the configuration of the head will be described with reference to Figures 3 to 5. Figure 3 is a schematic exploded view showing an example of a head, and is a view showing only the liquid ejection unit 101 that constitutes the head 1 of Figure 2. Figure 4 is an explanatory view showing an example of a flow path portion of the head, and Figure 5 is a cross-sectional perspective view showing an example of a flow path portion of the head. Note that the nozzle plate 10 has an outline shape that is roughly a parallelogram as shown in Figure 2, but will be described here using a simplified view that shows it as a rectangle.

[0026] The liquid ejection section 101 of the head 1 includes a nozzle plate 10, a flow path plate (individual flow path member) 20, a vibration plate member 30, a common flow path member 50, a damper member 60, a frame member 80, and a substrate (flexible wiring substrate) 105 on which a drive circuit 104 is mounted.

[0027] The nozzle plate 10 has a plurality of nozzles 11 that eject liquid (ink in this embodiment), and the plurality of nozzles 11 are arranged two-dimensionally in the short direction of the nozzle plate 10 (short direction of the nozzle plate) and in the longitudinal direction of the nozzle plate that is perpendicular to this.

[0028] The individual flow path member 20 forms a plurality of pressure chambers (individual liquid chambers) 21 each communicating with a plurality of nozzles 11, a plurality of individual supply flow paths 22 each communicating with the plurality of pressure chambers 21, and a plurality of individual recovery flow paths 23 each communicating with the plurality of pressure chambers 21. Note that one pressure chamber 21 and the individual supply flow path 22 and individual recovery flow path 23 each communicating with it are collectively referred to as an individual flow path 25.

[0029] The vibration plate member 30 forms a vibration plate 31 which is a deformable wall surface of the pressure chamber 21, and a piezoelectric element 40 is integrally provided on the vibration plate 31. The vibration plate member 30 also has a supply side opening 32 which communicates with the individual supply flow path 22 and a recovery side opening 33 which communicates with the individual recovery flow path 23 formed therein.

[0030] The piezoelectric element 40 is a pressure generating means that deforms the vibration plate 31 to pressurize the liquid in the pressure chamber 21 .

[0031] The individual flow path member 20 and the diaphragm member 30 are not limited to being separate members. For example, it is also possible to use an SOI (Silicon on Insulator) substrate to integrally form the individual flow path member 20 and the diaphragm member 30 from the same member. That is, an SOI substrate having a silicon oxide film, a silicon layer, and a silicon oxide film formed in this order on a silicon substrate can be used, with the silicon substrate serving as the individual flow path member 20 and the diaphragm 31 being formed from the silicon oxide film, the silicon layer, and the silicon oxide film. In this configuration, the layer structure of the silicon oxide film, the silicon layer, and the silicon oxide film of the SOI substrate becomes the diaphragm member 30. In this way, the diaphragm member 30 includes one made of a material formed on the surface of the individual flow path member 20.

[0032] The common flow path member 50 forms a plurality of common supply flow path tributaries 52 that communicate with two or more individual supply flow paths 22 and a plurality of common recovery flow path tributaries 53 that communicate with two or more individual recovery flow paths 23, alternately adjacent to each other in a direction perpendicular to the medium feeding direction. The common flow path member 50 is formed with through holes that serve as supply ports 54 that communicate between the supply-side openings 32 of the individual supply flow paths 22 and the common supply flow path tributaries 52, and through holes that serve as recovery ports 55 that communicate between the recovery-side openings 33 of the individual recovery flow paths 23 and the common recovery flow path tributaries 53. The common flow path member 50 also forms one or more common supply flow path main channels 56 that communicate with the multiple common supply flow path tributaries 52, and one or more common recovery flow path main channels 57 that communicate with the multiple common recovery flow path tributaries 53.

[0033] The damper member 60 has a supply-side damper 62 facing (opposite) the supply port 54 of the common supply flow path tributary 52, and a recovery-side damper 63 facing (opposite) the recovery port 55 of the common recovery flow path tributary 53. Here, the common supply flow path tributary 52 and the common recovery flow path tributary 53 are formed by sealing grooves arranged alternately in the common flow path member 50, which is the same member, with the supply-side damper 62 or the recovery-side damper 63 of the damper member 60. Note that the damper material of the damper member 60 is preferably a metal thin film or an inorganic thin film that is resistant to organic solvents. The thickness of the supply-side damper 62 and the recovery-side damper 63 of the damper member 60 is preferably 10 μm or less.

[0034] A protective film (also called a liquid-contact film) is formed on the inner wall surfaces of the common supply channel tributary 52 and the common recovery channel tributary 53, and on the inner wall surfaces of the common supply channel main stream 56 and the common recovery channel main stream 57, to protect the inner wall surfaces from the liquid flowing through the channels. For example, a silicon oxide film is formed on the surfaces of the common supply channel tributary 52 and the common recovery channel tributary 53, and on the inner wall surfaces of the common supply channel main stream 56 and the common recovery channel main stream 57, by heat treating the Si substrate. A tantalum silicon oxide film is formed on the silicon oxide film to protect the surface of the Si substrate from ink.

[0035] The frame member 80 has a supply port 81 and a discharge port 82 at its upper portion. The supply port 81 supplies liquid to the common supply channel main flow 56, and the discharge port 82 discharges liquid discharged from the common return channel main flow 57.

[0036] <Comparative Example> Next, the configuration of a comparative example will be described with reference to Figures 6 and 7. Figure 6 is an explanatory diagram showing a head of the comparative example, and Figure 7 is an explanatory diagram showing a state in which a plurality of heads of the comparative example are arranged side by side.

[0037] The head 1R shown as a comparative example has an outer shape (ridgeline) inclined at an angle θ with respect to the short-side direction of the nozzle plate, and the liquid ejection unit 101R and nozzle plate 10R of the head 1R are also formed in a shape that follows this ridgeline. In other words, the liquid ejection unit 101R has a nozzle plate 10R with an outer shape shaped like a parallelogram, and multiple nozzles 11R are regularly arranged in a two-dimensional pattern on the nozzle plate 10R. The nozzles 11R are arranged in a nozzle row 11N, for example, consisting of N nozzles 11R, and multiple nozzle rows 11N are arranged in parallel to the ridgeline and in the long-side direction of the nozzle plate, which is perpendicular to the short-side direction of the nozzle plate.

[0038] The head 1R configured as described above can have multiple heads 1Ra and 1Rb arranged in a row in the longitudinal direction of the nozzle plate, as shown in Fig. 7. However, in the comparative example, the nozzle row 11N is configured with a uniform number of N nozzles 11R. Therefore, when arranging the heads 1R so that the nozzle rows 11N are spaced equally apart in the left-right direction (longitudinal direction of the nozzle plate), it is difficult to leave a sufficient gap between the connecting portions of the heads 1Ra and 1Rb.

[0039] In other words, the distance between the nozzle row located at the right end of head 1Ra and the nozzle row located at the left end of head 1Rb must be the same as the distance between the other nozzle rows in terms of recording resolution in the longitudinal direction of the nozzle plate. Therefore, the nozzle row located closest to the head joint is located a short distance from the edge of the head. As a result, the distance from the nozzle row at the longitudinal end of the nozzle plate to the ridge (edge) of nozzle plate 10R is inevitably small, which poses a robustness issue: external impacts can easily damage the nozzles, pressure chambers, and flow channels connected to the nozzles.

[0040] Here, the short-side direction of the nozzle plate is an example of a "first direction," and the long-side direction of the nozzle plate is an example of a "second direction." Note that the short-side direction of the nozzle plate does not refer to the direction of the short side of the parallelogram nozzle plate 10R. It is assumed that the nozzle plate is rectangular, and in this case the direction of the short side of the rectangle is defined as the short-side direction of the nozzle plate. Similarly, the long-side direction of the nozzle plate does not refer to the direction of the long side of the parallelogram nozzle plate 10R. It is assumed that the nozzle plate is rectangular, and in this case the direction of the long side of the rectangle is defined as the long-side direction of the nozzle plate. It is to be noted that this definition also applies to each embodiment of the present invention described below.

[0041] <Other issues> FIG. 8 is an explanatory diagram illustrating another issue (curvature of ejected droplets) other than the above-mentioned robustness.

[0042] Figure 8 shows the nozzle arrangement when three heads are arranged adjacent to each other in the longitudinal direction of the nozzle plate. The square (◇) indicates the nozzles of the first head, the black circle (●) indicates the nozzles of the second head, and the horizontal line (-) indicates the nozzles of the third head. When liquid is ejected from the nozzles using this nozzle arrangement, the ejected liquid (ejected droplets) are prone to bending, especially from nozzles located on the upwind side or at the end, which may prevent the droplets from landing at the target location. For example, as shown in Figure 8, droplets ejected from areas A1 and A2 located on the upwind side of the head connection are prone to bending. Note that the wind (air current) here is thought to be generated by the air current generated by the liquid ejection operation from the nozzles or the air current generated by a medium such as paper passing below the head.

[0043] In this embodiment, in the case of the printing device 500 shown in Fig. 1, the upstream side in the medium (paper) feed direction is the windward side. Another method is the so-called serial method, in which an inkjet recording unit (head) is moved (head scanning) in a direction perpendicular to the paper feed direction relative to intermittently fed paper to form an image on the paper. In the serial method, the downstream side in the movement direction of the inkjet recording unit is exposed to the wind (the wind blows more strongly).

[0044] Therefore, the present invention focuses on the fact that liquid ejected from nozzles located on the downwind side is less likely to curve than liquid ejected from nozzles located on the upwind side, and arranges the nozzles in areas A1 and A2 in areas A1' and A2' that are on the downwind side of the adjacent head. This reduces the effect of airflow on ejected droplets, and reduces deterioration in image quality caused by ejected droplets curving. Specific embodiments are described below.

[0045] First Embodiment A first embodiment of the present invention will be described with reference to FIGS. 9 to 12. FIG. 9 is an explanatory diagram of a head according to the first embodiment of the present invention, and FIG. 10 is an explanatory diagram showing the transition of the number of nozzles in a nozzle row in the longitudinal direction of a nozzle plate in the same embodiment. Also, FIG. 11 is an explanatory diagram showing a state in which multiple heads are arranged in the same embodiment, and FIG. 12 is an explanatory diagram showing a head joint portion in the same embodiment. Note that the basic configuration of head 1 is as described in FIG. 2, so the same elements are given the same reference numerals and their description will be omitted here.

[0046] 9, head 1 has a parallelogram-shaped outer shape consisting of two parallel ridgelines inclined at an angle θ1 with respect to the short-side direction of the nozzle plate (first direction) and two ridgelines parallel to the long-side direction of the nozzle plate (second direction). Nozzle plate 10 provided in head 1 also has a parallelogram-shaped outer shape consisting of two parallel ridgelines (nozzle plate short side e1) inclined at an angle θ1 with respect to the short-side direction of the nozzle plate and two ridgelines (nozzle plate long side f1) parallel to the long-side direction of the nozzle plate.

[0047] The nozzle plate 10 has a nozzle surface 12 on which a plurality of nozzles 11 that eject liquid are arranged. The plurality of nozzles 11 are arranged in a direction (on a straight line L1) that is inclined at an angle θ2 with respect to the short side direction of the nozzle plate to form a nozzle row 11N. By arranging a plurality of such nozzle rows 11N in the longitudinal direction of the nozzle plate (second direction), the nozzle plate 10 forms a nozzle surface 12 on which a plurality of nozzles 11 are regularly arranged two-dimensionally.

[0048] Furthermore, the line connecting the leading nozzles of each of the multiple nozzle rows 11N that form the nozzle surface 12 is defined as an imaginary line La. In other words, the imaginary line La connects one end of adjacent nozzle rows 11N that have the same number of nozzles (in this example, each nozzle row has eight nozzles). Note that the imaginary line La is inclined at an angle θ3 with respect to the longitudinal direction of the nozzle plate, as shown in the figure.

[0049] When the imaginary straight line La is drawn as described above, a region C1 is provided at one end of the nozzle plate in the longitudinal direction (the left end in FIG. 9) where the leading position of the nozzle row 11N is located on the other end side of the nozzle row away from the imaginary straight line La. In other words, near the region C1, the number of nozzles 11 constituting the nozzle row 11N decreases from 8 to 6 to 5 to 3 to 2 to 1 as you move from the center to the end.

[0050] Furthermore, the line connecting the rearmost nozzles of each of the multiple nozzle rows 11N that form the nozzle surface 12 is defined as a virtual line Lb. That is, the virtual line Lb connects the other ends of adjacent nozzle rows 11N that have the same number of nozzles (in this example, each nozzle row has eight nozzles). The virtual line Lb is parallel to the virtual line La and, like the virtual line La, is inclined at an angle θ3 with respect to the longitudinal direction of the nozzle plate.

[0051] When the imaginary straight line Lb is drawn as described above, a region C2 is provided at the other longitudinal end of the nozzle plate (the right end in FIG. 9) where the rear position of the nozzle row 11N is positioned outside the imaginary line Lb. In other words, near region C2, the number of nozzles 11 constituting the nozzle row 11N changes from 8 to 9 to 9 to 8 to 7 to 6 to 4 to 3 to 1 as you move from the center to the end, increasing to 9 before decreasing. FIG. 10 is a graph showing the change in the number of nozzles in the nozzle row described above.

[0052] Here, the imaginary line La is an example of a “first imaginary line,” and the imaginary line Lb is an example of a “second imaginary line.” Also, the portion C1 is an example of a “first portion,” and the portion C2 is an example of a “second portion.”

[0053] As described above, the first embodiment is a head 1 including a nozzle plate 10 in which a plurality of nozzles 11 are formed on a plane formed by the nozzle plate's short-side direction (first direction) and the nozzle plate's long-side direction (second direction) perpendicular to the short-side direction, and when the nozzle plate's long-side direction is defined as the direction in which the plurality of nozzles 11 are aligned at equal intervals at a predetermined pitch corresponding to the recording resolution, a plurality of nozzle arrays 11N each made up of a plurality of nozzles 11 are formed in the nozzle plate 10 at an angle with respect to the nozzle plate's short-side direction. Furthermore, when the imaginary line La is defined as a line connecting one end of adjacent nozzle arrays each having the same number of nozzles, the nozzle plate 10 has, at one end in the nozzle plate's long-side direction, a region C1 where the leading position of the nozzle array 11N is located on the other end side of the nozzle array, away from the imaginary line La.

[0054] Furthermore, as described above, when the virtual line Lb connecting the other ends of adjacent nozzle rows 11N that have the same number of nozzles is defined as the virtual line Lb, the nozzle plate 10 has a portion C2 at the other end in the longitudinal direction of the nozzle plate where the rear position of the nozzle row 11N is positioned outside beyond the virtual line Lb.

[0055] This prevents the nozzles 11 from being located in areas susceptible to the effects of air currents, thereby reducing deterioration in image quality caused by ejected droplets being deflected by air currents.

[0056] The head 1 having the above configuration can also be configured in an array of any length by arranging multiple heads adjacent to each other in the longitudinal direction of the nozzle plate, as shown in Fig. 11. Of the components that make up the head 1, the nozzle plate holding member 102 and the mounting member 103 are not shown in Fig. 11. The joints between the heads in this case (broken line portion C3) will be explained using Fig. 12.

[0057] 12 shows an example of the joint between heads 1a and 1b. At one end of head 1a, the number of nozzles 11 constituting nozzle row 11N is 8 in nozzle row 11N-47, 9 in nozzle rows 11N-48 and 11N-49, 8 in nozzle row 11N-50, 7 in nozzle row 11N-51, 6 in nozzle row 11N-52, 4 in nozzle row 11N-53, 3 in nozzle row 11N-54, and 1 in nozzle row 11N-55. As you move from nozzle row 11N-47 located in the center toward nozzle row 11N-55 at the end, the number of nozzles 11 initially increases to 9 and then decreases.

[0058] On the other hand, at the other end of head 1b, the number of nozzles 11 constituting nozzle row 11N is 8 in nozzle rows 11N-7 and 11N-6, 6 in nozzle row 11N-5, 5 in nozzle row 11N-4, 3 in nozzle row 11N-3, 2 in nozzle row 11N-2, and 1 in nozzle row 11N-1, decreasing from nozzle row 11N-7 located in the center to nozzle row 11N-1 at the end.

[0059] In this embodiment, the arrangement of the nozzles 11 is set so that when head 1a and head 1b are aligned in the longitudinal direction of the nozzle plate, the endmost nozzle row 11N-55 of head 1a is located between the extensions of nozzle row 11N-4 and nozzle row 11N-5 of head 1b.

[0060] In the above configuration, when liquid is ejected by driving eight nozzles 11 at a time, for example, up to nozzle row 11N-47, liquid is ejected using eight nozzles 11 arranged in a row. In the next nozzle row 11N-48, liquid is ejected using the top eight nozzles 11 of the nine nozzles 11 in the drawing. The ninth nozzle 11 in nozzle row 11N-48 operates together with the top seven nozzles 11 in the next nozzle row 11N-49.

[0061] In the same manner, the nozzles 11 are fed in order in groups of eight. In other words, the feeding is performed in order starting with the nozzle whose intersection point is located in front when a perpendicular line is drawn from the center of each nozzle 11 to a horizontal line in the longitudinal direction of the nozzle plate. The seventh and eighth nozzles 11 (the bottom two in the figure) of nozzle row 11N-50 operate together with one nozzle 11 that makes up nozzle row 11N-1 of the adjacent head 1b and five nozzles 11 that make up nozzle row 11N-51 of head 1a.

[0062] After that, the nozzles 11 are fed in order in the same manner up to nozzle row 11N-5 of head 1b, and the missing nozzles are supplemented with nozzles from the next nozzle row. From nozzle row 11N-6 of head 1b onwards, liquid is ejected using eight nozzles 11 lined up in a row, and the above-mentioned feeding is repeated again at the end of head 1b (nozzle row 11N-48).

[0063] While the present embodiment has been described based on a configuration in which liquid ejection is performed in units of eight nozzles, the drive unit is not limited to this and may be less than eight or more than eight. Furthermore, the numerical values ​​used in the description regarding the transition in the number of nozzles in a nozzle array in the longitudinal direction of the nozzle plate are merely examples and are not limited to these. They may be changed as appropriate depending on specifications such as recording resolution. Furthermore, in the present embodiment, nozzle array 11N-55 of head 1a is positioned between nozzle arrays 11N-4 and 11N-5 of head 1b, but the arrangement of nozzles 11 is not limited to this. In this way, by connecting multiple heads and modularizing them into a head unit, the desired recording resolution can be ensured while preventing the effects of airflow.

[0064] The first embodiment is particularly effective for devices such as line-type inkjet devices, which do not have a head scanning mechanism and do not change the transport direction (the direction of the airflow does not change), and it is effective to mount the head so that part C1 is located upstream in the transport direction.

[0065] <Second embodiment> Next, a second embodiment of the present invention will be described with reference to Figures 13 to 15. Figure 13 is an explanatory diagram of a head according to the second embodiment of the present invention, Figure 14 is an explanatory diagram showing the transition of the number of nozzles in a nozzle row in the longitudinal direction of a nozzle plate in the same embodiment, and Figure 15 is an explanatory diagram showing a state in which multiple heads are arranged in the same embodiment. The basic configuration of the head 1 is the same as in the first embodiment, so the same elements are given the same reference numerals and their explanation will be omitted.

[0066] The second embodiment differs from the first embodiment in the transition of the number of nozzles at the longitudinal end of the nozzle plate 10. That is, in the second embodiment, at one longitudinal end of the nozzle plate (the right end in FIG. 13), the number of nozzles 11 constituting the nozzle row 11N transitions from 8 to 9 to 8 to 7 to 5 to 4 to 2 to 1 as one moves from the center to the end, increasing once to 9 before decreasing.

[0067] Furthermore, at the other end in the longitudinal direction of the nozzle plate (the left end in FIG. 13), the number of nozzles 11 constituting nozzle row 11N similarly changes from 8 to 9 to 8 to 7 to 5 to 4 to 2 to 1 as you move from the center to the end, increasing to 9 before decreasing. FIG. 14 is a graph showing the change in the number of nozzles in the nozzle row described above.

[0068] 14, when the number of nozzles changes symmetrically between one end and the other end in the longitudinal direction of the nozzle plate, the portion where the number of nozzles increases and then decreases (increase / decrease portion) may be located diagonally on the nozzle plate 10. In other words, as shown in Fig. 13, the portion where the number of nozzles increases / decreases is located roughly on the diagonal line L2 of the nozzle plate 10. In this case, the increase / decrease portion is located away from the corners of the nozzle plate 10, or in a position where it is less susceptible to the influence of airflow.

[0069] Furthermore, when the nozzle number increasing / decreasing sections are arranged diagonally on the nozzle plate 10, the nozzles 11 may be arranged in rotational symmetry. Figure 13 shows an example of a configuration in which the nozzles 11 are arranged so that the positions of the nozzles 11 overlap when rotated 180 degrees, i.e., so-called 2-fold symmetry is established.

[0070] As described above, in this embodiment, a portion corresponding to the portion C2 in the first embodiment is provided at a diagonal corner of the nozzle plate 10 (approximately on the diagonal line L2).

[0071] As described above, the nozzles 11 are formed in the nozzle plate 10 in an arrangement that establishes dyad symmetry.

[0072] This makes it possible to reduce the difference in liquid ejection quality between the forward and backward passes, even when the liquid ejection operation is performed while the head and the medium are moved back and forth relative to each other, as in bidirectional printing, for example.

[0073] In the head 1 of the second embodiment, multiple heads can also be arranged adjacent to each other in the longitudinal direction of the nozzle plate, forming an array of any length, as shown in Fig. 15. Of the components that make up the head 1, the head holding member 102 and the mounting member 103 are not shown in Fig. 15. Liquid ejection at the joints between heads is performed by sequentially feeding the nozzles based on the same concept as in the first embodiment (Fig. 12).

[0074] Adjacent heads 1a, 1b, and 1c are arranged so that the portion of one head where the number of nozzles is reduced overlaps (faces) the portion of the other head where the number of nozzles is reduced in the first direction, thereby maintaining the printing resolution even at the joints between the heads.

[0075] In the second embodiment, in the case of a device that performs head scanning, such as a serial inkjet device, by making the nozzle arrangement a symmetrical structure, it is possible to obtain an effect even when the direction of the airflow changes.

[0076] <Application example> <<Application Example 1>> The liquid ejection head of the present invention is also capable of ejecting liquids used to form three-dimensional objects. Examples of liquids used to form three-dimensional objects include hydrogel-forming materials for forming three-dimensional structures used in training for medical procedures. The hydrogel-forming material contains water and a polymerizable monomer, and preferably contains minerals and an organic solvent, and further contains a polymerization initiator and other components as needed. The polymerizable monomer is a compound having one or more unsaturated carbon-carbon bonds, and is preferably a polymerizable monomer that polymerizes when exposed to active energy rays such as ultraviolet rays or electron beams.

[0077] Examples of polymerizable monomers include monofunctional monomers and polyfunctional monomers. These may be used alone or in combination of two or more. Examples of polyfunctional monomers include bifunctional monomers, trifunctional monomers, and tetrafunctional or higher functional monomers.

[0078] There are no particular restrictions on the mineral, and it can be selected appropriately depending on the purpose, but since hydrogels are mainly composed of water, clay minerals are preferred, and layered clay minerals that can be uniformly dispersed in water at the primary crystal level are more preferred, with water-swellable layered clay minerals being even more preferred.

[0079] Examples of organic solvents include water-soluble organic solvents. The water-solubility of a water-soluble organic solvent means that the organic solvent can dissolve in water at a rate of 30% by mass or more. The water-soluble organic solvent is not particularly limited and can be appropriately selected depending on the purpose. Examples of water-soluble organic solvents include alkyl alcohols having 1 to 4 carbon atoms, such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, and tert-butyl alcohol; amides, such as dimethylformamide and dimethylacetamide; ketones or ketone alcohols, such as acetone, methyl ethyl ketone, and diacetone alcohol; ethers, such as tetrahydrofuran and dioxane; ethylene glycol, propylene glycol, 1,2-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, and diol. Examples include polyhydric alcohols such as ethylene glycol, triethylene glycol, 1,2,6-hexanetriol, thioglycol, hexylene glycol, and glycerin; polyalkylene glycols such as polyethylene glycol and polypropylene glycol; lower alcohol ethers of polyhydric alcohols such as ethylene glycol monomethyl (or ethyl) ether, diethylene glycol methyl (or ethyl) ether, and triethylene glycol monomethyl (or ethyl) ether; alkanolamines such as monoethanolamine, diethanolamine, and triethanolamine; and N-methyl-2-pyrrolidone, 2-pyrrolidone, and 1,3-dimethyl-2-imidazolidinone.

[0080] These may be used alone or in combination of two or more. Among these, polyhydric alcohols, glycerin, and propylene glycol are preferred from the viewpoint of moisturizing properties, and glycerin and propylene glycol are more preferred.

[0081] The polymerization initiator is not particularly limited and can be appropriately selected depending on the purpose. Examples include photopolymerization initiators and thermal polymerization initiators. As the photopolymerization initiator, any substance that generates radicals when irradiated with light (particularly ultraviolet light with a wavelength of 220 nm to 400 nm) can be used. When three-dimensional modeling is performed using a hydrogel-forming material, a UV (Ultra Violet) irradiation mechanism is provided, and the discharged hydrogel-forming material is irradiated with UV light to harden and form the product.

[0082] (Specific examples of hydrogel-forming materials) While stirring 120.0 parts by mass of ion-exchanged water that had been degassed under reduced pressure for 30 minutes, 12.0 parts by mass of synthetic hectorite (Laponite XLG, manufactured by RockWood) having the composition [MgLiSiO(OH)Na-0.66] as a layered clay mineral was gradually added and stirred. 0.6 parts by mass of etidronic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) was then added and stirred to prepare a dispersion. To the resulting dispersion, 44.0 parts by mass of acryloylmorpholine (manufactured by KJ Chemicals Co., Ltd.) and 0.4 parts by mass of methylenebisacrylamide (manufactured by Tokyo Chemical Industry Co., Ltd.), which had been passed through an activated alumina column to remove the polymerization inhibitor, were added as polymerizable monomers. Furthermore, 20.0 parts by mass of glycerin (manufactured by Sakamoto Pharmaceutical Industry Co., Ltd.) and 0.8 parts by mass of N,N,N',N'-tetramethylethylenediamine (manufactured by Tokyo Chemical Industry Co., Ltd.) were mixed to obtain a hydrogel-forming material.

[0083] <<Application Example 2>> The liquid ejection head of the present invention can also be used in an inkjet method for arbitrarily arranging cells to artificially form tissues composed of cells, and is capable of ejecting a cell suspension (cell ink). The cell suspension (cell ink) contains at least cells and a cell drying inhibitor. The cell suspension (cell ink) further contains a dispersion medium for dispersing the cells, and may contain other additives such as a dispersant and a pH adjuster as necessary.

[0084] The type of cells is not particularly limited and can be selected appropriately depending on the purpose, and all cells can be used regardless of taxonomic classification, such as eukaryotic cells, prokaryotic cells, multicellular organism cells, and unicellular organism cells. These may be used alone or in combination of two or more types.

[0085] Examples of eukaryotic cells include animal cells, insect cells, plant cells, and fungi. These may be used alone or in combination of two or more. Among these, animal cells are preferred, and when cells form cell aggregates, adhesive cells that adhere to each other and have such cell adhesiveness that they cannot be isolated without physicochemical treatment are more preferred.

[0086] The cell drying inhibitor is a substance that covers the surface of cells and acts to inhibit the cells from drying out, and examples thereof include polyhydric alcohols, gel-like polysaccharides, and proteins selected from extracellular matrices.

[0087] As the dispersion medium, a cell culture medium or buffer solution is preferred. A medium is a solution that contains components necessary for the formation and maintenance of cell tissues, prevents drying, and regulates the external environment, such as osmotic pressure. Any known medium can be appropriately selected and used. If it is not necessary to constantly immerse the cells in the medium, the medium can be appropriately removed from the cell suspension. A buffer solution is used to adjust the pH according to the cells and purpose, and any known buffer solution can be appropriately selected and used.

[0088] (Example of cell suspension (cell ink)) Green fluorescent dye (trade name: Cell Tracker Green, Life Technologies) was dissolved in dimethyl sulfoxide (DMSO) at a concentration of 10 mmol / L (mM) and mixed with serum-free Dulbecco's modified Eagle's medium (Life Technologies) to prepare a serum-free medium containing the green fluorescent dye at a concentration of 10 μmol / L (μM). Next, 5 mL of serum-free medium containing the green fluorescent dye was added to a dish containing cultured NIH / 3T3 cells (Clone 5611, JCRB Cell Bank) and cultured for 30 minutes in an incubator (KM-CC17RU2, Panasonic Corporation, 37°C, 5% CO2). The supernatant was then removed using an aspirator. 5 mL of phosphate-buffered saline (Life Technologies, hereafter also referred to as PBS(-)) was added to the dish, and the PBS(-) was aspirated and removed to wash the surface. After washing with PBS(-) twice, 2 mL of a 0.05% by mass trypsin-0.05% by mass EDTA solution (manufactured by Life Technologies) was added to each dish.

[0089] The dish was then heated in an incubator for 5 minutes to detach the cells from the dish, after which 4 mL of D-MEM containing 10% fetal bovine serum (hereinafter also referred to as "FBS") and 1% antibiotic (Antibiotic-Antimycotic Mixed Stock Solution (100x), manufactured by Nacalai Tesque, Inc.) was added. Next, the trypsin-inactivated cell suspension was transferred to a 50 mL centrifuge tube and centrifuged (product name: H-19FM, manufactured by KOKUSAN, 1,200 rpm, 5 minutes, 5°C), and the supernatant was removed using an aspirator.

[0090] After removal, 2 mL of D-MEM containing 10% FBS and 1% antibiotics was added to the centrifuge tube and gently pipetted to disperse the cells, obtaining a cell suspension. 10 μL of this cell suspension was transferred to an Eppendorf tube, 70 μL of medium was added, and 10 μL was transferred to another Eppendorf tube. 10 μL of 0.4% trypan blue staining solution was added and pipetted. 10 μL of the stained cell suspension was then transferred to a PMMA plastic slide.

[0091] The cell count was measured using a Countess Automated Cell Counter (Invitrogen) to obtain a cell suspension containing counted cells. PBS(-) was used as the dispersion medium. Glycerin (molecular biology grade, manufactured by Wako Pure Chemical Industries, Ltd.) was dissolved in PBS(-) as a cell drying inhibitor at a mass ratio of 0.5%. The NIH / 3T3 cell suspension was dispersed in the dispersion medium at a concentration of 6 x 106 cells / mL to obtain a cell ink.

[0092] The above-described embodiments of the present invention may be modified, added, or deleted as appropriate within the scope of the spirit of the present invention. The present invention is not limited to the above-described embodiments, and many modifications may be made by a person skilled in the art within the technical concept of the present invention. (Aspect 1) A liquid ejection head including a nozzle plate on which a plurality of nozzles are formed on a plane defined by a first direction and a second direction perpendicular to the first direction, when the second direction is defined as a direction in which the plurality of nozzles are arranged at equal intervals at a predetermined pitch corresponding to a recording resolution, a plurality of nozzle rows constituted by the plurality of nozzles are formed in the nozzle plate at an angle with respect to the first direction, When a virtual line connecting one end of adjacent nozzle rows, each having the same number of nozzles, is defined as a first virtual line, the liquid ejection head has a first portion at one end of the nozzle plate in the second direction, where the leading position of the nozzle row is located on the other end side of the nozzle row, away from the first virtual line. (Aspect 2) In aspect 1, when a virtual line connecting the other ends of adjacent nozzle rows having the same number of nozzles is defined as a second virtual line, the liquid ejection head has a second portion at the other end of the nozzle plate in the second direction, where the rear position of the nozzle row is positioned outside and beyond the second virtual line. (Aspect 3) In the liquid ejection head according to aspect 2, the second portion is provided at a diagonal corner of the nozzle plate. (Aspect 4) In any one of aspects 1 to 3, the liquid ejection head is configured such that the plurality of nozzles are formed in the nozzle plate in an arrangement that establishes two-fold symmetry. (Aspect 5) A liquid ejection head including a nozzle plate on which a plurality of nozzles are formed on a plane defined by a first direction and a second direction perpendicular to the first direction, when the second direction is defined as a direction in which the plurality of nozzles are arranged at equal intervals at a predetermined pitch corresponding to a recording resolution, a plurality of nozzle rows constituted by the plurality of nozzles are formed in the nozzle plate at an angle with respect to the first direction, The nozzle plate has A liquid ejection head in which the nozzles are arranged so that, at least at one of the two ends in the second direction, the number of nozzles constituting the nozzle row increases once from the center in the second direction to the one end and then decreases. (Aspect 6) In aspect 5, the nozzles of the nozzle plate are arranged in a liquid ejection head such that, at the other end in the second direction, the number of nozzles constituting the nozzle row decreases from the center in the second direction to the other end. (Aspect 7) In aspect 5, the nozzles of the nozzle plate are arranged so that at the other end in the second direction, the number of nozzles forming the nozzle row increases once and then decreases from the center in the second direction to the other end. (Aspect 8) In aspect 7, the liquid ejection head has a portion where the number of nozzles increases and then decreases, the portion being disposed diagonally across from the nozzle plate. (Aspect 9) A liquid ejection unit comprising a plurality of liquid ejection heads according to any one of aspects 1 to 8 arranged adjacent to each other in the second direction. (Aspect 10) In aspect 9, the adjacent liquid ejection heads are arranged in a liquid ejection unit such that the portion where the number of nozzles in one liquid ejection head is reduced overlaps with the portion where the number of nozzles in the other liquid ejection head is reduced in the first direction. (Aspect 11) A liquid ejection device comprising the liquid ejection head according to any one of the first to eighth aspects or the liquid ejection unit according to the ninth or tenth aspect. [Explanation of symbols]

[0093] 1 (1a, 1b, 1c, 1d) Head (an example of a liquid ejection head) 101(101a,101b,101c,101d) Liquid discharge part 102 (102a, 102b, 102c, 102d) head holding member 103 (103a, 103b, 103c, 103d) Mounting member 10 nozzle plate 11 nozzles 11N nozzle row 12 Nozzle surface 555 head unit La virtual line (an example of the first virtual line) Lb virtual line (an example of a second virtual line) C1 region (an example of the first region) C2 region (an example of the second region)

Claims

1. A liquid ejection head including a nozzle plate on which a plurality of nozzles are formed on a plane defined by a first direction and a second direction perpendicular to the first direction, when the second direction is defined as a direction in which the plurality of nozzles are arranged at equal intervals at a predetermined pitch corresponding to a recording resolution, a plurality of nozzle arrays constituted by the plurality of nozzles are formed in the nozzle plate at an angle with respect to the first direction, When a virtual line connecting one end of a plurality of adjacent nozzle rows, each having the same number of nozzles, is defined as a first virtual line, a leading position of the nozzle row has a first portion at one end of the nozzle plate in the second direction, the leading position of the nozzle row being located on the other end side of the nozzle row away from the first virtual line, and When a virtual line connecting the other ends of adjacent nozzle rows having the same number of nozzles is defined as a second virtual line, the liquid ejection head has a second portion at the other end of the nozzle plate in the second direction, where the rear position of the nozzle row is positioned outside and beyond the second virtual line.

2. 2. The liquid ejection head according to claim 1, wherein the second portions are provided at diagonal corners of the nozzle plate.

3. 3. The liquid ejection head according to claim 1, wherein the plurality of nozzles are formed in the nozzle plate in an arrangement that establishes two-fold symmetry.

4. A liquid ejection unit comprising a plurality of liquid ejection heads according to claim 1 arranged adjacent to each other in the second direction.

5. 5. A liquid ejection unit according to claim 4, wherein the adjacent liquid ejection heads are arranged so that a portion of one liquid ejection head where the number of nozzles is reduced overlaps a portion of the other liquid ejection head where the number of nozzles is reduced in the first direction.

6. A liquid ejection apparatus comprising the liquid ejection head according to any one of claims 1 to 3 or the liquid ejection unit according to claim 4 or 5.

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