Manufacturing method of plate with printing layer and printing device

Abstract

To provide a manufacturing method of a plate with a printing layer that enables efficient formation of a printing layer in a plate having a bent part by an inkjet method.SOLUTION: In a manufacturing method of a plate with a printing layer, a printing layer is formed in a main surface of a plate having a bent part bent in a plate thickness direction, by an inkjet method. When the printing layer is formed in the main surface by using a plurality of print heads each having at least one nozzle and discharging ink from the nozzles of the plurality of print heads while the plurality of print heads and the plate are moved relatively to each other, the plurality of print heads and the plate are moved relatively to each other such that a distance from the nozzle discharging the ink to the main surface is equal to or less than 20 mm.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a method for producing a plate with a printed layer, and a printing device. [Background technology]

[0002] An in-vehicle information device such as a car navigation system or an audio device, or a mobile communication device, is provided with a display device. A protective cover, which is a plate-shaped transparent plate, is provided on the front surface of the display in the display device via an adhesive layer. For example, a light-shielding printed layer is provided in a frame shape on the display side surface of the protective cover. The printed layer has a function of concealing wiring on the display side to maintain an aesthetic appearance, or a function of concealing illumination light from a backlight to prevent the illumination light from leaking from around the display. In recent years, there has been a demand for large, complex shapes with curved sections as cover glass shapes for in-vehicle display devices. As a method for forming a print layer on a curved surface, for example, the inkjet method described in Patent Document 1 is known. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-197850 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the method described in Patent Document 1 uses a single inkjet print head, so when the object to be printed is large, the print head must be moved back and forth multiple times to print, resulting in low production efficiency.

[0005] The present invention provides a method for producing a plate with a printed layer, which can efficiently form a printed layer on a plate having a bent portion using an inkjet method, and a printing apparatus. [Means for solving the problem]

[0006] One embodiment of the present invention relates to a method for manufacturing a plate with a printed layer, the method comprising the steps of: forming a printed layer using an inkjet method on the main surface of a plate having a bent portion that bends in the plate thickness direction; using a plurality of print heads, each having at least one nozzle, the plurality of print heads and the plate are moved relative to each other while ejecting ink from the nozzles of the plurality of print heads to form a printed layer on the main surface; and moving the plurality of print heads and the plate relative to each other so that the distance from the nozzles ejecting the ink to the main surface is 20 mm or less.

[0007] One embodiment of the printing device of the present invention is a printing device that manufactures a plate with a printed layer by using an inkjet method to form a printed layer on the main surface of a plate having a bent portion that bends in the plate thickness direction, and is equipped with a plurality of print heads, each having at least one nozzle, an ejection control unit that forms the printed layer on the main surface by ejecting ink from the nozzles of the plurality of print heads, and a relative movement unit that moves the plurality of print heads and the plate relatively so that the distance from the nozzles that eject the ink to the main surface is 20 mm or less. Effect of the Invention

[0008] According to the present invention, it is possible to provide a method for manufacturing a plate with a printed layer, which can efficiently form a printed layer on a plate having a bent portion using an inkjet method, and a printing device. [Brief description of the drawings]

[0009] [Figure 1] FIG. 2 is a schematic diagram of a printed layer-attached plate according to one embodiment of the present invention, in which (A) is a plan view and (B) is a cross-sectional view taken along line IB-IB of (A). [Diagram 2] FIG. 2 is a side view showing a schematic configuration of the printing device according to the embodiment. [Diagram 3] FIG. 2 is a plan view showing a schematic configuration of the printing device according to the embodiment. [Figure 4] FIG. 2 is a schematic diagram showing an arrangement of nozzles in an ink head according to the embodiment. [Diagram 5] Schematic diagram showing the positional relationship between the ink head and the plate when forming a printing layer in one embodiment, where (A) shows the positional relationship when a printing layer is formed on the horizontal surface of the plate, and (B) shows the positional relationship when a printing layer is formed on the first inclined surface of the plate. [Figure 6] FIG. 2 is a block diagram showing a schematic configuration of a control device according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] [Embodiment] A preferred embodiment of the present invention will be described below. Note that the present invention is not limited to this embodiment, and when there are multiple embodiments, the present invention also includes a combination of the embodiments. Numerical values ​​include the range of rounding.

[0011] (Plate with printed layer) First, the configuration of the printed layer-attached plate of this embodiment will be described. FIG. 1 is a schematic diagram of a plate with a printed layer, where (A) is a plan view and (B) is a cross-sectional view taken along line IB-IB of (A). The printed layer-attached plate GP shown in FIGS. 1(A) and (B) is a laminate that includes a plate G and a printed layer P formed on the plate G, and has a rectangular shape in a plan view. The use of the plate with the printed layer GP may be arbitrary, but it is preferably used as a cover glass for a display, and more preferably as a cover glass for an in-vehicle display. That is, in this embodiment, it is preferable to manufacture a display device, preferably an in-vehicle display device, by providing the plate with the printed layer GP on the display surface side of a display (not shown). It is preferable that the display is bonded to the side of the printed layer P of the plate with the printed layer GP. In the following description, the longitudinal direction of the printed layer plate GP is the X-axis direction, the lateral direction is the Y-axis direction, and the thickness direction is the Z-axis direction. The rightward direction in Figures 1(A) and (B) along the X-axis direction is the X1 direction, and the leftward direction is the X2 direction. The upward direction in Figure 1(A) along the Y-axis direction is the Y1 direction, and the downward direction is the Y2 direction. The upward direction in Figure 1(B) along the Z-axis direction is the Z1 direction, and the downward direction is the Z2 direction.

[0012] (board) The plate G has a first main surface G1 on which the printing layer P is formed, and a second main surface G2 located on the opposite side of the first main surface G1. The plate G has a first flat portion GA1, a first bent portion GB1, an inclined portion GC, a second bent portion GB2, and a second flat portion GA2. In this embodiment, the first and second flat portions GA1 and GA2 and the inclined portion GC are flat surfaces with a radius of curvature of 10,000 mm or more, but are not limited to this and may be curved surfaces. In this application, a surface with a radius of curvature of 10,000 mm or more is defined as a flat surface, and a surface with a radius of curvature of less than 10,000 mm is defined as a curved surface. The radius of curvature of the first and second bent portions GB1 and GB2 is smaller than the radius of curvature of the first and second flat portions GA1 and GA2 and the inclined portion GC. The radius of curvature of the first and second bend portions GB1, GB2 is less than 10,000 mm, for example, 1,000 mm or less, 500 mm or less, or 300 mm or less. The radius of curvature of the first and second bend portions GB1, GB2 is preferably 10 mm or more, and more preferably 50 mm or more.

[0013] The first flat portion GA1 constitutes a portion of the plate G on the X2 direction side. The first bent portion GB1 is adjacent to the first flat portion GA1 on the X1 direction side, and is bent so that the first principal surface G1 has a concave shape and the second principal surface G2 has a convex shape. The first bent portion GB1 is bent about a bending axis parallel to the Y-axis direction. The bending axis can be said to be the central axis of the circle of curvature of the portion of the second principal surface G2 that constitutes the first bent portion GB1. The inclined portion GC is adjacent to the X1 direction side of the first bent portion GB1 and is inclined at an inclination angle θ1 with respect to the first flat portion GA1. When the first flat portion GA1 is parallel to the XY plane, i.e., the horizontal plane M, the inclined portion GC is inclined at an inclination angle θ1 with respect to the horizontal plane M. The second bent portion GB2 is adjacent to the inclined portion GC on the X1 direction side, and is bent so that the first main surface G1 has a convex shape and the second main surface G2 has a concave shape. The second bent portion GB2 is bent around a bending axis parallel to the Y-axis direction, like the first bent portion GB1. The bending axis can be said to be the central axis of the circle of curvature of the portion of the first main surface G1 that constitutes the second bent portion GB2. The second flat portion GA2 is adjacent to the X1 direction side of the second bent portion GB2, and constitutes a portion of the plate G on the X1 direction side. The second flat portion GA2 is parallel to the first flat portion GA1.

[0014] The plate G is not limited to the above-mentioned shape, and may have any shape as long as it has at least one bent portion, but a shape having a curved surface that is concave on the first main surface G1 side is preferable. Examples of such shapes include a curved shape in which the entire first main surface G1 is a curved surface, an S-shape having at least one bent portion that is concave or convex on the first main surface G1 side, a shape that does not have the first flat portion GA1 and the first bent portion GB1, and a shape that does not have the second bent portion GB2 and the second flat portion GA2. Examples of the S-shape include a shape having the first flat portion GA1, the first bent portion GB1, the inclined portion GC, the second bent portion GB2, and the second flat portion GA2 as described above, and further a shape in which the first flat portion GA1, the inclined portion GC, and the second flat portion GA2 are replaced with curved surfaces. In addition, a shape having three or more bent portions may be used. With such a shape, it is difficult to form a printed layer by other means such as screen printing, and the printing method according to this embodiment is particularly effective. The second flat portion GA2 may be inclined with respect to the first flat portion GA1. The radius of curvature of the second bent portion GB2 may be the same as or different from the radius of curvature of the first bent portion GB1. The plate G may further include a bent portion and a flat portion at the end portion on the X1 direction side or the X2 direction side. The bending axis does not have to be parallel to the Y-axis direction. Moreover, the plate G has a rectangular shape in a plan view, but may have any other shape, such as a polygon, a circle, an ellipse, or the like.

[0015] It is preferable that the plate G does not have a plurality of bending axes in different directions at one bent portion, that is, that there is only a bending axis in one direction. When plate G has a plurality of bent portions, it is preferable that the bending axes of the bent portions are parallel to each other as shown in Figs. 1(A) and (B), but they do not have to be parallel to each other.

[0016] For example, when the plate G is glass, the thickness of the plate G is not particularly limited, but in order to effectively perform the chemical strengthening treatment, it is usually preferably 5 mm or less, more preferably 3 mm or less. In addition, when used as a cover glass for an in-vehicle display device such as a car navigation system, the thickness of the glass is preferably 0.2 mm or more, more preferably 0.8 mm or more, and even more preferably 1 mm or more from the viewpoint of strength. That is, when the plate G is glass, the thickness is preferably 0.2 mm or more and 5 mm or less, more preferably 0.8 mm or more and 3 mm or less, and even more preferably 1 mm or more and 3 mm or less.

[0017] The length of the plate G in a direction parallel to the bending axis of the first and second bent portions GB1, GB2, i.e., the width of the plate G, is preferably 100 mm or more and 300 mm or less. The width here refers to the length along the first main surface G1 from one end of the plate G to the other end in a direction parallel to the bending axis of the first and second bent portions GB1, GB2. The length of the plate G in the direction perpendicular to the bending axis of the first and second bent portions GB1, GB2 is preferably 350 mm or more and 1000 mm or less. The length here refers to the length along the first main surface G1 from one end of the plate G to the other end in the direction perpendicular to the bending axis of the first and second bent portions GB1, GB2. Plate G, whose width and length in the direction perpendicular to the bending axis of the first and second bending portions GB1, GB2 are within the preferred ranges described above, is suitable for use as a cover glass for an in-vehicle display device, and the printing method in this embodiment is useful.

[0018] The material of the plate G may be any material, such as glass, ceramics, resin, wood, metal, etc., but glass is preferable. When the plate G is made of glass, the plate G is preferably tempered glass, more preferably chemically tempered glass. When the plate G is chemically tempered glass, the DOL, i.e., the thickness of the compressive stress layer of the plate G, is preferably, for example, 5 μm or more, more preferably 10 μm or more, and even more preferably 15 μm or more. Moreover, the DOL is, for example, preferably 180 μm or less, more preferably 50 μm or less.

[0019] CS, that is, the surface compressive stress in the compressive stress layer, is preferably 500 MPa or more, more preferably 650 MPa or more, and even more preferably 750 MPa or more. There is no particular upper limit to CS, but for example, CS is preferably 1200 MPa or less. A known method may be used to obtain chemically strengthened glass by subjecting glass to chemical strengthening treatment. Examples of molten salts used in chemical strengthening treatment include alkali nitrates such as potassium nitrate, sodium nitrate, potassium sulfate, and sodium sulfate, alkali sulfate, and alkali chloride salts. These molten salts are not limited to being used alone, and may be used in combination with a plurality of types, and other salts may be mixed to adjust the chemical strengthening properties. As a result, in the surface layer of the plate G, alkali ions such as Li ions or Na ions are ion-exchanged with other alkali ions in the molten salt having a large ionic radius, such as Na ions or K ions, and then cooled to near room temperature. This ion exchange forms a layer in which compressive stress is generated by densification, that is, a compressive stress layer, in the surface layer of the plate G. In this way, the plate G can be strengthened. Processing conditions such as the temperature of the molten salt and the immersion time may be set so that CS and DOL are desired values.

[0020] The plate G that has been subjected to the chemical strengthening treatment may further be subjected to an acid treatment and an alkali treatment. The acid treatment is a process in which the chemically strengthened plate G is immersed in an acid solution. As a result, at least one of Na and K on the surface of the chemically strengthened plate G is replaced with H. That is, the surface layer of the compressive stress layer in the chemically strengthened plate G is altered to become a low-density layer. The alkali treatment is a treatment in which the plate G that has been subjected to the acid treatment is immersed in a basic solution. This removes part or all of the low-density layer formed by the acid treatment. In this way, cracks and latent scratches present on the surface of the plate G can be removed together with the low-density layer.

[0021] The material of the plate G is arbitrary, but examples thereof include aluminosilicate glass such as SiO2-Al2O3-Na2O glass or SiO2-Al2O3-Li2O-Na2O glass, or soda-lime glass, etc. Among these, aluminosilicate glass is preferable from the viewpoint of strength. The material of the plate G may be, for example, a glass material containing, in mole percentage on an oxide basis, SiO2 from 50% to 80%, Al2O3 from 1% to 20%, Na2O from 6% to 20%, K2O from 0% to 11%, MgO from 0% to 15%, CaO from 0% to 6%, and ZrO2 from 0% to 5%, or a glass material containing, in mole percentage on an oxide basis, SiO2 from 50% to 80%, Al2O3 from 1% to 20%, Na2O from 6% to 20%, K2O from 0% to 11%, MgO from 0% to 15%, CaO from 0% to 6%, and ZrO2 from 0% to 5%. Examples of glass materials containing 0% or less, Al2O3 at 2% or more and 25% or less, Li2O at 0.1% or more and 20% or less, Na2O at 0.1% or more and 18% or less, K2O at 0% or more and 10% or less, MgO at 0% or more and 15% or less, CaO at 0% or more and 5% or less, P2O5 at 0% or more and 5% or less, B2O3 at 0% or more and 5% or less, Y2O3 at 0% or more and 5% or less, and ZrO2 at 0% or more and 5% or less. As the material for the plate G, a chemically strengthened glass based on aluminosilicate glass, for example, "Dragontrail (registered trademark)" manufactured by AGC, is also suitably used.

[0022] (Printing layer) The printing layer P is formed on the first main surface G1 of the plate G. The printing layer P may be any layer made of a material different from that of the plate G, and may be, for example, a light-shielding layer that blocks at least one of visible light and infrared light. The printed layer P includes a first printed layer P1, a pair of second printed layers P2, a third printed layer P3, a pair of fourth printed layers P4, and a fifth printed layer P5. The first printed layer P1 is formed on the end portion of the first flat portion GA1 on the X2 direction side. The first printed layer P1 is formed in a rectangular shape that spans the entire width direction of the printed-layer-attached plate GP. A pair of second printed layers P2 are formed in a rectangular shape extending in the X1 direction from each end of the first printed layer P1 on the Y1 and Y2 directions to a portion near the boundary between the first flat portion GA1 and the first bent portion GB1. The third printed layer P3 is formed from the end of the pair of second printed layers P2 on the X1 direction side to a portion near the boundary between the second bent portion GB2 and the second flat portion GA2. The third printed layer P3 is formed in a rectangular shape across the entire width of the printed-layer plate GP. A pair of fourth printed layers P4 are formed in a rectangular shape extending in the X1 direction from each end of the third printed layer P3 on the Y1 direction side and the Y2 direction side to a portion near the edge of the second flat portion GA2 on the X1 direction side. The fifth printed layer P5 is formed in a rectangular shape along the edge of the second flat portion GA2 in the X1 direction so as to connect the edges of the pair of fourth printed layers P4 in the X1 direction to each other.

[0023] The area of ​​the plate with printed layer GP where the printed layer P is formed constitutes the printed area GQ. The area of ​​the plate with printed layer GP where the printed layer P is not formed constitutes the non-printed area GR. The non-printed area GR comprises a first non-printed area GR1 surrounded by a first printed layer P1 and a pair of a second printed layer P2 and a third printed layer P3, and a second non-printed area GR2 surrounded by the third printed layer P3 and a pair of a fourth printed layer P4 and a fifth printed layer P5. When the display is turned on, an image is displayed in the non-printed area GR. When the printed layer P is a light-shielding layer, the printed area GQ functions as a light-shielding area, and the non-printed area GR functions as a light-transmitting area that transmits light. The printed area GQ plays a role in improving the appearance of the display device by concealing wiring and the like. The printing layer P may be a single layer, or a plurality of layers may be laminated.

[0024] The thickness of the printing layer P is preferably 3.0 μm or more and 10.0 μm or less, more preferably 3.5 μm or more and 5.0 μm or less, and even more preferably 4.0 μm or more and 5.0 μm or less. By setting the thickness of the printing layer P within this range, light leakage from the printing layer P can be suppressed.

[0025] The first boundary B1 between the first non-printing region GR1 and the first printing layer P1, the second boundary B2 between the first non-printing region GR1 and the third printing layer P3, the third boundary B3 between the second non-printing region GR2 and the third printing layer P3, and the fourth boundary B4 between the second non-printing region GR2 and the fifth printing layer P5 are formed as straight lines parallel to the Y-axis direction. The pair of fifth boundaries B5 between the first non-printing region GR1 and the pair of second printing layers P2, and the pair of sixth boundaries B6 between the second non-printing region GR2 and the pair of fourth printing layers P4 are formed as straight lines parallel to the X-axis direction.

[0026] Note that at least one of the first to fourth boundaries B1 to B4 may be inclined with respect to the Y-axis direction, and at least one of the fifth and sixth boundaries B5 and B6 may be inclined with respect to the X-axis direction. At least one of the first to sixth boundaries B1 to B6 may have a curved portion, or may have an acute-angled or obtuse-angled corner portion. In addition, the printing layer P is not limited to the shape shown in FIG. 1(A). For example, it may not be formed on a part of the outer periphery of the plate G, or may be formed so that one or three or more non-printing regions GR are provided. The printing layer P may be formed at a position away from the edge of the plate G, or may be formed on the entire first main surface G1.

[0027] (Configuration of the printing device) Next, a printing device for manufacturing a plate GP with a printing layer by forming the printing layer P on the plate G using an inkjet method will be described. FIG. 2 is a side view showing a schematic configuration of the printing device. FIG. 3 is a plan view showing a schematic configuration of the printing device. FIG. 4 is a schematic diagram showing the arrangement of nozzles in the ink head. FIG. 5 is a schematic diagram showing the positional relationship between the ink head and the plate when forming a printing layer, (A) showing the positional relationship when a printing layer is formed on the horizontal surface of the plate, and (B) showing the positional relationship when a printing layer is formed on the first inclined surface of the plate. FIG. 6 is a block diagram showing the schematic configuration of the control device. FIG. 3 is a view of the printing device as seen from the Z1 direction side of FIG. 2, FIG. 4 is a view of the ink head as seen from the Z1 direction side of FIG. 2, and FIGS. 5(A), (B), and (C) are views of the ink head and the plate as seen from the Y2 direction side of FIG. 2.

[0028] 2 and 3 includes a printing unit 2, a head pressure maintaining unit 3, a relative movement mechanism 4, and a control device 5 described below. In the following description, the X1 direction is referred to as the printing progress direction, the X2 direction is referred to as the opposite printing progress direction, and the X1 and X2 directions may be collectively referred to as the X-axis direction as the printing progress direction and the Y-axis direction as the printing width direction.

[0029] The printing unit 2 ejects the ink N based on the control of the control device 5 by an ink jet method. The printing unit 2 includes a plurality of print heads 21 and an ink supply unit 22 . Each of the print heads 21 includes a rectangular parallelepiped head body 211. A nozzle plate 211A is provided on the surface of the head body 211 on the Z2 direction side. The print heads 21 are installed on the Z1 direction side, i.e., above the plate G held by the relative movement mechanism 4. The print heads 21 are arranged so that the longitudinal direction of the surface of the head body 211 on the Z2 direction side is parallel to the printing width direction, and are arranged to form two rows parallel to the printing width direction. The print heads 21 are arranged in a state where they are shifted from each other in the printing width direction and are alternately shifted toward the printing progress direction and the opposite printing progress direction. In other words, the print heads 21 are arranged in a so-called staggered pattern. The print heads 21 are arranged so that, when viewed from the printing progress direction side, the Y2 direction side portion of the print head 21 on the Y1 direction side of the adjacent print heads 21 overlaps with the Y1 direction side portion of the print head 21 on the Y2 direction side. It is desirable that the length W21 of the head body 211 of each print head 21 in the printing direction be 5 mm or more. It is desirable that the length V21 of the nozzle plate 211A of each print head 21 in the printing direction be 5 mm or more.

[0030] In the following description, the row of printheads 21 on the printing progress side will be referred to as the first printhead row 21A, and the row of printheads 21 on the opposite printing progress side will be referred to as the second printhead row 21B. In this embodiment, as shown in Fig. 3, six print heads 21 are provided in the printing device 1, but two to five print heads 21, or seven or more print heads 21 may be provided. The print heads 21 may be arranged to form one or three or more rows parallel to the printing width direction, and when three or more rows are formed, they may or may not be arranged in a staggered pattern. The print heads 21 may be arranged in a row in a direction inclined with respect to the X-axis direction on the XY plane.

[0031] Each print head 21 further includes a plurality of nozzles 212 provided in a head body 211, and a piezoelectric element 213 shown in FIG. The piezoelectric elements 213 are provided in the same number as the nozzles 212. The piezoelectric elements 213 are driven under the control of the control device 5 to eject the ink N supplied from the ink supply unit 22 to the nozzles 212 as droplets. Also, the piezoelectric elements 213 impart vibrations to the meniscus of each nozzle 212 under the control of the control device 5. The multiple nozzles 212 are arranged inside the head main body 211 such that openings for ejecting the ink N are exposed from the planar lower surface of the nozzle plate 211A. As shown in FIGS. 3 and 4, the multiple nozzles 212 are arranged to form multiple rows in the printing width direction.

[0032] In the following description, as shown in Figures 4 and 5, the rows of nozzles 212 in each print head 21 are referred to as the first nozzle row 215A, the second nozzle row 215B, the third nozzle row 215C, and the fourth nozzle row 215D, in order from the row in the print progress direction. The first nozzle row 215A and the second nozzle row 215B constitute a first nozzle row group 216A. The third nozzle row 215C and the fourth nozzle row 215D constitute a second nozzle row group 216B. Note that the number of rows of nozzles 212 in each print head 21 may be one, two, three, or five or more rows.

[0033] The nozzles 212 of the first nozzle row 215A and the nozzles 212 of the second nozzle row 215B are arranged in a state where they are shifted from each other in the printing width direction, and are alternately shifted in the printing progress direction and the opposite printing progress direction. In other words, the nozzles 212 constituting the first nozzle row group 216A are arranged in a so-called staggered pattern. Similarly, the nozzles 212 constituting the second nozzle row group 216B are also arranged in a staggered pattern. The nozzles 212 constituting the first nozzle row group 216A and the nozzles 212 constituting the second nozzle row group 216B are arranged so that their positions in the printing width direction are different from each other. As shown in FIG. 4, it is preferable that the distance R21 from the nozzles 212 of the first nozzle row 215A to the end of the nozzle plate 211A in the direction of printing, and the distance R21 from the nozzles 212 of the fourth nozzle row 215D to the end of the nozzle plate 211A in the opposite direction to printing, are greater than or equal to 0 mm and less than or equal to 20 mm.

[0034] 4, among the nozzles 212 constituting the first nozzle row group 216A of the first print head row 21A, the two nozzles 212 at the end in the Y1 direction may be referred to as first end nozzles 212A, and the two nozzles at the end in the Y2 direction may be referred to as second end nozzles 212B. Among the nozzles 212 constituting the second nozzle row group 216B of the first print head row 21A, the two nozzles 212 at the end in the Y1 direction may be referred to as third end nozzles 212C, and the two nozzles at the end in the Y2 direction may be referred to as fourth end nozzles 212D. Of the nozzles constituting the first nozzle row group 216A of the second print head row 21B, the two nozzles at the end in the Y1 direction may be referred to as fifth end nozzles 212E, and the two nozzles at the end in the Y2 direction may be referred to as sixth end nozzles 212F. Of the nozzles 212 constituting the second nozzle row group 216B of the second print head row 21B, the two nozzles 212 at the end in the Y1 direction may be referred to as seventh end nozzles 212G, and the two nozzles at the end in the Y2 direction may be referred to as eighth end nozzles 212H.

[0035] In each print head 21, the multiple nozzles 212 are arranged so that the distance D in the printing width direction between the pair of nozzles 212 having the shortest distance in the printing width direction is 5 mm or less, preferably 1 mm or less, and more preferably 0.5 mm or less. For example, the pair of nozzles 212 having the shortest distance in the printing width direction is the nozzle 212 located furthest in the Y1 direction of the first nozzle row 215A and the nozzle 212 located furthest in the Y1 direction of the third nozzle row 215C. In addition, each print head 21 is arranged so that, when viewed from the printing progression direction, the first end nozzle 212A and the sixth end nozzle 212F of adjacent print heads 21 are positioned the same in the printing width direction, the second end nozzle 212B and the fifth end nozzle 212E are positioned the same in the printing width direction, the third end nozzle 212C and the eighth end nozzle 212H are positioned the same in the printing width direction, and the fourth end nozzle 212D and the seventh end nozzle 212G are positioned the same in the printing width direction.

[0036] 3, each print head 21 is disposed so that the width WH from the nozzle 212 located furthest on the Y1 side to the nozzle 212 located furthest on the Y2 side, i.e., the effective printing width WH, is greater than the width WG of the plate G. With this configuration, a printing layer P of a desired shape can be formed on the plate G by simply moving each print head 21 once in the printing progression direction.

[0037] The number of nozzles 212 provided in the print head 21 may be one. Furthermore, the multiple nozzles 212 may be arranged to form one, two, three, or five or more nozzle rows parallel to the printing width direction. When the multiple nozzles 212 form multiple nozzle rows, the multiple nozzles 212 may or may not be arranged in a staggered manner. Furthermore, the multiple nozzles 212 may be arranged to form one row parallel to the X-axis direction.

[0038] As shown in FIG. 2 and FIGS. 5(A) and (B), the ink supply unit 22 includes a first ink tank 221, a second ink tank 222, and an ink pressure adjustment unit 223 shown in FIG. The first ink tank 221 contains the ink N to be supplied to each printhead 21 in the first printhead row 21A. A supply pipe 224 that supplies the ink N in the first ink tank 221 to each nozzle 212 of each printhead 21, and a return pipe 225 that returns the ink N in each printhead 21 to the first ink tank 221 are connected to each printhead 21 and the first ink tank 221 that constitute the first printhead row 21A. The second ink tank 222 contains the ink N to be supplied to each printhead 21 in the second printhead row 21B. A supply pipe 226 and a return pipe 227 having the same functions as the supply pipe 224 and the return pipe 225 are also connected to each printhead 21 and the second ink tank 222 constituting the second printhead row 21B. The ink pressure adjustment unit 223, under the control of the control device 5, adjusts the pressure of the meniscus of the nozzles 212 of each print head 21 to a predetermined pressure setting value that is lower than atmospheric pressure. The ink supply unit 22 does not necessarily have to include the return pipes 225 and 227. Also, for example, the first ink tank 221 may include tanks in the same number as the print heads 21 constituting the first print head row 21A, and ink N may be supplied from each tank to each print head 21, respectively.

[0039] The water head pressure maintaining unit 3 includes a first printing unit holding member 31 and a second printing unit holding member 32. The first printing unit holding member 31 holds each printhead 21 in the first printhead row 21A and a first ink tank 221. The second printing unit holding member 32 holds each printhead 21 in the second printhead row 21B and a second ink tank 222. Each print head 21 of the first and second print head rows 21A, 21B held by the first and second printing unit holding members 31, 32 and the first and second ink tanks 221, 222 are raised and lowered the same distance by driving the relative movement mechanism 4. Therefore, fluctuations in the head pressure of the ink N accompanying the raising and lowering of each print head 21 are suppressed, and the absolute value of the pressure fluctuation with respect to the pressure setting value of the meniscus of the nozzle 212 when forming the printing layer P can be maintained at 0.2 kPa or less.

[0040] The relative movement mechanism 4 moves the printing unit 2 having a plurality of print heads 21 and the plate G relatively in the X-axis direction. The relative movement mechanism 4 includes a plate holding unit 41 and a print head moving unit .

[0041] The plate holding part 41 holds the plate G, for example by suction, in a state where it does not move from the second main surface G2 side and so that the first and second flat parts GA1, GA2 are parallel to the horizontal plane M. It is preferable to use plate holding parts 41 that are different from each other depending on the three-dimensional shape of the plate G.

[0042] The print head moving unit 42, under the control of the control device 5, moves the first and second printing unit holding members 31 and 32 in the X-axis direction while maintaining the parallel state between the lower surfaces of the head bodies 211 of each print head 21 held by the first and second printing unit holding members 31 and 32 and the horizontal plane M. In other words, the print head moving unit 42 moves the first and second printing unit holding members 31 and 32 in the X-axis direction while maintaining the parallel state between the opening surface of the nozzle 212 and the horizontal plane M.

[0043] Further, under the control of the control device 5, the print head moving unit 42 raises and lowers the first and second printing unit holding members 31, 32 individually in the Z axis direction in accordance with the shape of the first main surface G1 of the plate G. 5(A), when forming a printing layer P on a plate horizontal surface portion GH parallel to a horizontal plane M, the print head moving unit 42 moves the first and second printing unit holding members 31, 32 in the Z-axis direction so that the distance L1 from the opening planes of the nozzles 212 of all print heads 21 constituting the first and second print head rows 21A, 21B to the plate horizontal surface portion GH is 20 mm or less, preferably 10 mm or less. In the plate G shown in FIGS. 1(A) and 1(B), the first and second flat portions GA1, GA2 correspond to the plate horizontal surface portion GH.

[0044] As shown in Fig. 5B, when forming a printing layer P on the first plate inclined surface portion GK1 inclined with respect to the horizontal plane M so that the X1 direction side is higher than the X2 direction side, the print head moving unit 42 moves the first and second printing unit holding members 31 and 32 in the Z axis direction so that the distance L2 from the opening surface of the nozzles 212 of the first nozzle row group 216A located on the X1 direction side among the first and second nozzle row groups 216A and 216B of the print head 21 constituting the first and second print head rows 21A and 21B to the first plate inclined surface portion GK1 is 20 mm or less, preferably 10 mm or less. In the plate G shown in Figs. 1A and 1B, the inclined portion GC and the first and second bent portions GB1 and GB2 correspond to the first plate inclined surface portion GK1.

[0045] Although not shown in the figure, when forming a printing layer P on a second plate inclined surface portion that is inclined with respect to horizontal plane M so that the X2 side is higher than the X1 side, the print head moving unit 42 moves the first and second printing unit holding members 31, 32 in the Z axis direction so that the distance from the opening surface of the nozzles 212 of the second nozzle array group 216B located on the X2 side of the first and second nozzle array groups 216A, 216B of the print head 21 that constitute the first and second print head arrays 21A, 21B to the second plate inclined surface portion is 20 mm or less, and preferably 10 mm or less.

[0046] The print head moving unit 42 can be a combination of a slider mechanism that moves the first and second printing unit holding members 31, 32 in the X-axis direction and a piston mechanism that raises and lowers them in the Z-axis direction, or a mechanism that moves the first and second printing unit holding members 31, 32 as described above, such as a six-axis robot.

[0047] The control device 5 controls the printing unit 2 and the relative movement mechanism 4. As shown in Fig. 6, the control device 5 includes a print head position detection unit 51, an input unit 52, a display unit 53, a storage unit 54, and a control unit 55. The control unit 55 is electrically connected to the piezoelectric element 213, the ink pressure adjustment unit 223, the print head movement unit 42, the print head position detection unit 51, the input unit 52, the display unit 53, and the storage unit 54.

[0048] The print head position detection unit 51 detects the position of each print head 21 in the X-axis direction and the Z-axis direction, and outputs a signal corresponding to the detected position to the control unit 55.

[0049] The input unit 52 is configured, for example, by a touch panel, a physical button, or a two-dimensional code reader. The input unit 52 is used to input various information, and outputs a signal corresponding to the input to the control unit 55. An example of the information input by the input unit 52 is shape specifying information that specifies the three-dimensional shapes of the plate G and the printing layer P.

[0050] The display unit 53 displays various types of information under the control of the control unit 55 .

[0051] The storage unit 54 is configured with a well-known storage device such as an HDD (Hard Disk Drive). The storage unit 54 stores a print control program, candidate nozzle information, and various information necessary for the operation of the printing device 1. The candidate nozzle information includes first candidate information, second candidate information, and third candidate information.

[0052] The first candidate information represents a nozzle 212 that is a candidate for use when forming a printing layer P on a first plate inclined surface portion GK1 in which the X1 direction side is higher than the X2 direction side, as shown in FIG. 5(B). In the following description, the nozzles 212 that are candidates for use will be referred to as the candidate nozzles 212 for use. The first candidate information indicates that, of the nozzles 212 constituting the first and second print head rows 21A and 21B, only the nozzles 212 in the first nozzle row group 216A are set as the candidate nozzles 212 to be used. In other words, the first candidate information indicates that only the nozzles 212 that are closer to the first plate inclined surface portion GK1 than the second nozzle row group 216B and that can keep the distance L2 to the first plate inclined surface portion GK1 to 20 mm or less, preferably 10 mm or less, are set as the candidate nozzles 212 to be used.

[0053] Of the nozzles 212 set as the candidate nozzles 212 to be used based on the first candidate information, the first end nozzle 212A and the sixth end nozzle 212F are in the same position in the printing width direction, and the second end nozzle 212B and the fifth end nozzle 212E are in the same position in the printing width direction, but the positions in the printing width direction of the other nozzles 212 are different from each other. Therefore, if the ejection frequency of ink N from the first, second, fifth and sixth end nozzles 212A, 212B, 212E and 212F is set to 0.5 times the ejection frequency of the other nozzles 212 while moving the first and second print head rows 21A and 21B at a constant speed, the number of landing droplets of ink N per unit area will be equal. Since two candidate nozzles 212 to be used are lined up in the printing progress direction at a predetermined position in the printing width direction, the number of landing droplets of ink N per unit area will be equal if the ejection frequency of the candidate nozzles 212 to be used that are in the same position in the printing width direction is set to 0.5, i.e. 1 / 2, the ejection frequency of the other candidate nozzles 212 to be used. When F candidate nozzles 212 to be used (F is an integer of 3 or more) are lined up in the printing progress direction at a predetermined position in the printing width direction, the number of landing droplets of ink N per unit area will be equal if the ejection frequency of the candidate nozzles 212 to be used that are in the same position in the printing width direction is set to 1 / F times the ejection frequency of the other candidate nozzles 212 to be used.

[0054] In addition, when the distance L2 from the opening surface of the nozzle 212 of the first nozzle array group 216A to the first plate inclined surface portion GK1 is 20 mm or less, preferably 10 mm or less, and when the distance L3 from the opening surface of the nozzle 212 of the second nozzle array group 216B to the first plate inclined surface portion GK1 is also 20 mm or less, preferably 10 mm or less, as shown in Figure 5 (B), all of the nozzles 212 constituting the first and second nozzle array groups 216A and 216B may be set as candidate nozzles 212 to be used.

[0055] The second candidate information represents a nozzle 212 to be used as a candidate for forming the printing layer P on the second plate inclined surface portion whose X1 direction side is lower than whose X2 direction side. The second candidate information indicates that, of the nozzles 212 constituting the first and second print head rows 21A and 21B, only the nozzles 212 in the second nozzle row group 216B are set as the candidate nozzles 212 to be used. In other words, the second candidate information indicates that only the nozzles 212 that are closer to the second inclined plate surface portion than the first nozzle row group 216A and whose distance to the second inclined plate surface portion can be 20 mm or less, preferably 10 mm or less, are set as the candidate nozzles 212 to be used.

[0056] Of the nozzles 212 set as the candidate nozzles 212 to be used based on the second candidate information, the third end nozzle 212C and the eighth end nozzle 212H are in the same position in the printing width direction, and the fourth end nozzle 212D and the seventh end nozzle 212G are in the same position in the printing width direction, but the positions in the printing width direction of the other nozzles 212 are different from one another. For this reason, if the ejection frequency of the third, fourth, seventh, and eighth end nozzles 212C, 212D, 212G, and 212H is set to 0.5 times the ejection frequency of the other nozzles 212 while moving the first and second print head rows 21A and 21B at a constant speed, the number of landing droplets of ink N per unit area will be equal.

[0057] In addition, when the distance from the opening surface of the nozzle 212 of the second nozzle array group 216B to the second plate inclined surface portion is 20 mm or less, preferably 10 mm or less, and the distance L3 from the opening surface of the nozzle 212 of the first nozzle array group 216A to the second plate inclined surface portion is also 20 mm or less, preferably 10 mm or less, all of the nozzles 212 constituting the first and second nozzle array groups 216A, 216B may be set as candidate nozzles 212 to be used.

[0058] The third candidate information indicates a candidate nozzle 212 to be used when forming the printing layer P on the plate horizontal surface portion GH shown in FIG. 5(A). The third candidate information has the same information as the first candidate information or the second candidate information. If the ejection frequency of the candidate nozzles 212 to be used that are in the same position in the printing width direction is set to 0.5 times the ejection frequency of the other candidate nozzles 212 to be used, the number of landing droplets of ink N per unit area will be the same. When forming the printing layer P on the plate horizontal surface portion GH, the distance L1 from all the nozzles 212 constituting the first and second print head rows 21A and 21B to the plate horizontal surface portion GH can be set to 20 mm or less, preferably 10 mm or less. Therefore, the third candidate information may represent that all the nozzles 212 constituting the first and second print head rows 21A and 21B are set as the candidate nozzles 212 to be used.

[0059] Since the ink N ejected from the nozzles 212 has wettability, even if the landing positions of the ink N ejected from adjacent nozzles 212 are far apart, the ink N wets and spreads to the area between these landing positions, forming a solid printed layer P as shown in Fig. 1. For this reason, depending on the shape of the printed layer P, for example, when ink N is ejected only from the candidate nozzles 212 to be used of the first nozzle array group 216A constituting the first print head array 21A, a printed layer P is formed on the first main surface G1 that is slightly wider than the distance from the candidate nozzle 212 to be used that is furthest from the candidate nozzle 212 to be used that is furthest from the candidate nozzle 212 to be used that is furthest from the candidate nozzle 212 to be used that is furthest from the candidate nozzle 212 to be used.

[0060] The control unit 55 includes, for example, a CPU (Central Processing Unit). The control unit 55 functions as a shape specifying unit 551, a discharge control unit 552, and a print head movement control unit 553 by the CPU executing a print control program stored in the storage unit 54.

[0061] The shape specifying unit 551 acquires the shape specifying information input from the input unit 52, and specifies the three-dimensional shapes of the board G and the printing layer P based on the shape specifying information. For example, when table-structured data in which the model of the printed-layer-attached board GP and the three-dimensional shapes of the board G and the printing layer P that constitute the printed-layer-attached board GP are associated with each other is stored in the storage unit 54, the shape specifying unit 551 specifies the three-dimensional shapes of the board G and the printing layer P based on the shape specifying information representing the model of the printed-layer-attached board GP and the table-structured data.

[0062] The ejection control unit 552 acquires information corresponding to each portion of the board G from the candidate nozzle information based on the three-dimensional shape of the printing layer P identified by the shape identification unit 551. Then, the ejection control unit 552 controls the piezoelectric element 213 based on the acquired information and the three-dimensional shape of the printing layer P to control the ejection state of the ink N from the nozzle 212.

[0063] The print head movement control unit 553 controls the print head moving unit 42 based on the three-dimensional shape of the board G specified by the shape specifying unit 551 to move the first and second print head rows 21A and 21B. The print head movement control unit 553 and the relative movement mechanism 4 constitute a relative movement unit.

[0064] (Method of manufacturing a plate with a printed layer) Next, a method for producing the printed layer-attached plate GP using the printing device 1 will be described. A method for producing the printed layer-attached plate GP shown in FIGS. 1(A) and (B) will be described below, but printed layer-attached plates can also be produced in a similar manner for plates having other three-dimensional shapes.

[0065] First, the worker inputs shape specifying information using, for example, the input unit 52. The shape specifying unit 551 of the control unit 55 specifies the three-dimensional shapes of the board G and the printing layer P based on the input shape specifying information. Note that the shape specifying unit 551 may obtain shape specifying information based on a detection result by a sensor or an imaging result by a camera, and specify the three-dimensional shapes of the board G and the printing layer P. Next, an operator or a board transport device (not shown) sets the board G on the board holding unit 41, as shown in Fig. 2. The board holding unit 41 holds the board G that has been set therein. Alternatively, after the board G is set in the board holding unit 41, the worker may input the shape specifying information.

[0066] When the three-dimensional shape of the printing layer P is identified by the shape identification unit 551, the discharge control unit 552 selects information representing the use candidate nozzles 212 at each portion in the X-axis direction of the plate G from the use candidate nozzle information. The discharge control unit 552 selects the third candidate information as information representing the use candidate nozzles 212 at the first and second flat portions GA1 and GA2. The discharge control unit 552 selects the first candidate information as information representing the use candidate nozzles 212 at the inclined portion GC and the first and second bent portions GB1 and GB2.

[0067] The discharge control unit 552 sets the nozzles 212 to be actually used as the nozzles 212 to be used from among the candidate nozzles 212 in each part of the plate G in the X-axis direction in accordance with the planar shape of the printing layer P. In other words, the discharge control unit 552 selects the candidate nozzles 212 to be used that are positioned vertically above the printing region GQ as the nozzles 212 to be used, and does not select the candidate nozzles 212 to be used that are positioned vertically above the non-printing region GR as the nozzles 212 to be used.

[0068] The ejection control unit 552 sets the ejection frequency of two nozzles 212 in the same position in the printing width direction to 0.5 times the ejection frequency of the other nozzles 212 in use, so that the number of landing droplets of ink N per unit area in the printing region GQ is equal according to the thickness of the printing layer P. For example, when the nozzles 212 including the first, second, fifth, and sixth end nozzles 212A, 212B, 212E, and 212F are selected as the nozzles 212 to be used based on the first candidate information, the ejection frequency of the first, second, fifth, and sixth end nozzles 212A, 212B, 212E, and 212F is set to 0.5 times the ejection frequency of the other nozzles 212 to be used. The ejection frequency can be adjusted by the driving state of the piezoelectric element 213. The ejection control unit 552 controls the ink pressure adjustment unit 223 to adjust the pressure of the ink N supplied to each print head 21 to a pressure setting value. The ejection control unit 552 controls the piezoelectric element 213 to impart vibration to the meniscus of the ink N in each nozzle 212 during standby for printing.

[0069] When the three-dimensional shape of the plate G is identified by the shape identification unit 551, the print head movement control unit 553 sets the movement trajectories of the first and second print head rows 21A, 21B so that the distances L1, L2 from the nozzle 212 in use to the first main surface G1 at each portion of the plate G in the X-axis direction are 20 mm or less, preferably 10 mm or less. When the first and second print head rows 21A, 21B move vertically above the first and second flat portions GA1, GA2, the print head movement control unit 553 sets the movement trajectories of the first and second print head rows 21A, 21B so that, as shown in FIG. 5(A), the undersides of all print heads 21 constituting the first and second print head rows 21A, 21B are positioned on the same plane, and the distance L1 from the opening surfaces of all nozzles 212 including the utilized nozzle 212 to the plate horizontal surface portion GH is 20 mm or less, preferably 10 mm or less. When the first and second printhead rows 21A and 21B move vertically above the first and second bend portions GB1, GB2 or inclined portion GC, the printhead movement control unit 553 sets the movement trajectories of the first and second printhead rows 21A and 21B so that, as shown in FIG. 5(B), the lower surfaces of the printheads 21 constituting the first printhead row 21A are positioned higher than the lower surfaces of the printheads 21 constituting the second printhead row 21B, and the distance L2 from the opening plane of the utilized nozzles 212 included in the first nozzle row group 216A of the first and second printhead rows 21A and 21B to the first and second bend portions GB1, GB2 or inclined portion GC is 20 mm or less, preferably 10 mm or less.

[0070] Thereafter, the print head movement control unit 553 controls the print head movement unit 42 based on the detection results of the positions of each print head 21 in the X-axis direction and the Z-axis direction by the print head position detection unit 51 to move the first and second print head rows 21A, 21B in the X-axis direction and the Z-axis direction along the set movement trajectory. At this time, the print head movement control unit 553 moves the first and second print head rows 21A, 21B in the X-axis direction at a uniform speed.

[0071] On the other hand, the ejection control unit 552 controls the piezoelectric element 213 to stop applying vibration to the meniscus of the ink N. The discharge control unit 552 controls the piezoelectric element 213 according to the positions of the first and second print head rows 21A and 21B to discharge ink N from each of the active nozzles 212 at a set discharge frequency. At this time, the discharge control unit 552 controls the piezoelectric element 213 according to the shapes of the first to fourth boundaries B1 to B4 between the print area GQ and the non-print area GR that intersect with respect to the print progress direction to control the discharge timing of ink N from the active nozzles 212. For example, the discharge control unit 552 makes the timing of stopping discharge of ink N from the active nozzles 212 of the first print head row 21A earlier than the timing of stopping discharge of ink N from the active nozzles 212 of the second print head row 21B according to the shapes of the first and third boundaries B1 and B3. The ejection control unit 552 makes the ejection start timing of ink N from the used nozzles 212 of the first print head row 21A earlier than the ejection start timing of ink N from the used nozzles 212 of the second print head row 21B, depending on the shapes of the second and fourth boundaries B2, B4.

[0072] Based on the above-described control of the control unit 55, in the printing unit 2 that moves in the printing direction only once, a printed layer P is formed over the entire printing width direction in the printing area GQ by ink N ejected only from the used nozzles 212 whose distances L1, L2 to the first main surface G1 are 20 mm or less, preferably 10 mm or less, as shown in Figures 1(A) and (B). In addition, the first print head row 21A and the first ink tank 221 simultaneously move up and down the same distance, and the second print head row 21B and the second ink tank 222 simultaneously move up and down the same distance, so that the printed layer P is formed in a state in which the absolute value of the pressure fluctuation with respect to the pressure setting value of the meniscus of the used nozzles 212 is maintained at 0.2 kPa or less.

[0073] (Effects of the embodiment) When the printing device 1 manufactures a plate GP with a printed layer by forming a printed layer P on a first main surface G1 of a plate G having first and second bend portions GB1, GB2, it moves multiple print heads 21, which are positioned differently in the printing width direction, relative to the plate G so that the distances L1, L2 from the nozzle 212 in use to the first main surface G1 are 20 mm or less. Therefore, compared to when a single print head 21 is used, the effective printing width WH can be made larger, and the printed layer P can be formed efficiently even if the plate G is large. Also, since the printed layer P is formed while maintaining the distances L1, L2 from the nozzles 212 in use to the first main surface G1 at 20 mm or less, the ink N ejected from the nozzles 212 in use can be prevented from becoming mist-like, and deterioration in the quality of the printed layer P can be suppressed. In particular, by moving the multiple print heads 21 and the plate G relative to one another so that the distances L1, L2 from the nozzle 212 in use to the first main surface G1 are 10 mm or less, the ink N can be further prevented from becoming mist-like, and deterioration in the quality of the printing layer P can be further prevented.

[0074] When manufacturing the plate GP with a printed layer, the printing device 1 moves the multiple print heads 21 in the printing direction while raising or lowering them according to the shape of the first main surface G1, without moving the plate G. In this manner, by adopting a configuration in which the print head 21, which is smaller than the plate G, is moved, it is possible to miniaturize the mechanism for moving the plate G and the print head 21 relative to each other.

[0075] Each print head 21 includes a first nozzle row group 216A and a second nozzle row group 216B having nozzles 212 positioned at different positions in the printing direction. When forming a printed layer P on the first and second bent portions GB1, GB2 or inclined portion GC, the printing device 1 ejects ink N from the used nozzles 212 constituting the first nozzle row group 216A while moving each print head 21 in the printing direction so that the opening surfaces of the nozzles 212 are kept parallel to the horizontal plane M and the distances L1, L2 from the first nozzle row group 216A of each print head 21 to the first main surface G1 are 20 mm or less. Therefore, the printing layer P can be formed by raising or lowering the multiple print heads 21 without rotating them in accordance with the shape of the first and second bend portions GB1, GB2 or the inclined portion GC, thereby simplifying the configuration of the print head moving unit 42 and preventing the control of the print head moving unit 42 from becoming complicated.

[0076] The multiple print heads 21 are arranged such that, when viewed from the printing progress direction, the Y2-direction side portions of adjacent print heads 21 on the Y1-direction side overlap with the Y1-direction side portions of adjacent print heads 21 on the Y2-direction side. Therefore, the seams between the printed layers P formed by the print heads 21 can be made invisible.

[0077] The multiple print heads 21 are arranged so as to be shifted from one another in the printing width direction, and so as to be shifted alternately on the printing advance direction side and the opposite printing advance direction side. Therefore, the length of a print head group made up of a plurality of print heads 21 in the printing progress direction can be shortened.

[0078] The printing device 1 controls the ejection state of the ink N from the active nozzles 212 in the first and second print head rows 21A and 21B so that the number of landing droplets of the ink N per unit area in the printing region GQ of the first main surface G1 is equal. As a result, the thickness of the printed layer P in the printing area GQ can be made uniform, improving the quality of the printed layer P.

[0079] The printer 1 controls the ejection timing of the ink N from the nozzles in use 212 in accordance with the shapes of the first to fourth boundaries B1 to B4 that intersect with the printing progress direction. Therefore, the first to sixth boundaries B1 to B6 of the printed layer P can be formed in the desired shapes, and the quality of the printed layer P is improved.

[0080] The multiple print heads 21 are arranged so that the effective printing width WH is greater than the width WG of the plate G, and are configured so that a printing layer P can be formed across the entire printing width direction in the printing area GQ with a single movement in the printing progress direction. This improves the productivity of the printed layer plate GP.

[0081] The printing apparatus 1 forms the printing layer P in a state in which the absolute value of the pressure fluctuation with respect to the pressure setting value of the meniscus of the used nozzle 212 is maintained at 0.2 kPa or less. Therefore, the ink N can be ejected from each of the utilized nozzles 212 in a stable state, and deterioration in the quality of the printed layer P can be suppressed. In particular, for example, by simply applying a simple configuration in which the first print head row 21A and the first ink tank 221 are held by the first printing unit holding member 31, deterioration in the quality of the printed layer P can be suppressed.

[0082] [Variations] Although an embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and various improvements and design changes that do not deviate from the gist of the present invention are also included in the present invention.

[0083] For example, a plurality of print heads 21, each having a plurality of nozzles 212 aligned in the printing width direction, may be arranged to form a single row along the printing progress direction and without being misaligned with each other in the printing width direction. With this configuration, a thicker printed layer P can be formed, and a printed layer P having a desired thickness can be formed efficiently, compared to when a single print head 21 is used. In addition, by forming the printed layer P while maintaining the distances L1, L2 from the nozzle 212 in use to the first main surface G1 at 20 mm or less, deterioration in the quality of the printed layer P can be suppressed.

[0084] By moving each print head 21 in the X-axis direction and the Z-axis direction while keeping the underside of the head body 211 positioned on the same plane, and rotating it around an axis of rotation parallel to the Y-axis direction, the distances L1, L2 from the nozzle 212 in use to the first main surface G1 can be set to 20 mm or less. Each print head 21 may be fixed so that the underside of the head body 211 is parallel to the horizontal plane M, and the plate G may be moved in the X-axis and Z-axis directions, for example by a robot arm, and rotated around a rotation axis parallel to the Y-axis direction, so that the distances L1, L2 from the nozzle 212 in use to the first main surface G1 may be set to 20 mm or less. At least one of the printing unit 2 and the plate G may be moved in the X-axis direction and the Z-axis direction and rotated around a rotation axis parallel to the Y-axis direction, so that the distances L1, L2 from the nozzle 212 to the first main surface G1 are set to 20 mm or less.

[0085] The following method may be applied as a method for controlling the ejection state of the ink N from the nozzles 212 in use so that the number of landing droplets of the ink N per unit area in the print region GQ is equal. For example, among the nozzles 212 constituting the first nozzle row group 216A of the first and second print head rows 21A and 21B, only one nozzle 212 each having a different position in the printing width direction is set as the candidate nozzle 212 to be used when forming the printing layer P on the first plate inclined surface portion GK1. To this end, among the first end nozzle 212A and the sixth end nozzle 212F having the same position in the printing width direction, only the first end nozzle 212A is set as the candidate nozzle 212 to be used, and among the second end nozzle 212B and the fifth end nozzle 212E having the same position in the printing width direction, only the second end nozzle 212B is set as the candidate nozzle 212 to be used. Then, the first and second print head rows 21A, 21B may be moved at a constant speed while ejecting ink N at the same ejection frequency from each of the active nozzles 212 located at different positions in the printing width direction, thereby making the number of droplets of ink N that land per unit area in the printing region GQ equal.

[0086] Although the ejection timing of the ink N from the utilized nozzles 212 is controlled in accordance with the shapes of the first to fourth boundaries B1 to B4 that intersect with the print progress direction, such control does not have to be performed.

[0087] A printing layer P can be formed over the entire printing width direction in the printing area GQ by arranging multiple print heads 21 so that the effective printing width WH is smaller than the width WG of the plate G, and moving the print heads 21 multiple times only in the printing progress direction with different positions in the printing width direction, or by moving them back and forth at least once.

[0088] For example, the first and second printing unit holding members 31, 32 are used as the head pressure maintaining unit 3 that suppresses fluctuations in the head pressure of the ink N associated with the rise and fall of each print head 21 in the first and second print head rows 21A, 21B. However, it is also possible to have the ink pressure adjusting unit 223 function as the head pressure maintaining unit 3 instead of the first and second printing unit holding members 31, 32, and fix the first and second ink tanks 221, 222 to adjust the pressure of the ink N by the ink pressure adjusting unit 223 so as to suppress fluctuations in the head pressure of the ink N associated with the rise and fall of each print head 21 in the first and second print head rows 21A, 21B. Furthermore, the water head pressure maintaining unit 3 does not have to be provided in the printing device 1. For example, the first and second ink tanks 221, 222 may be fixed and the print heads 21 of the first and second print head rows 21A, 21B may be raised and lowered.

[0089] The plate G may have a shape in which a single bent portion has multiple bending axes with different directions. In this case, the print head moving unit 42 is configured to generate a height difference between the print heads 21 adjacent to each other in the printing width direction of each print head row 21A, 21B, and the ink supply unit 22 is configured to supply ink N from separate tanks to each print head 21. Then, the print heads 21 adjacent to each other in the printing width direction may be moved in the printing progress direction while being raised or lowered by different heights according to the shape of the first main surface G1 so that the distances L1, L2 from the nozzles in use 212 to the first main surface G1 are 20 mm or less. EXAMPLES

[0090] Next, examples of the present invention will be described. Examples 2 to 6 are examples, and Examples 1 and 7 are comparative examples. However, the present invention is not limited to the examples.

[0091] (Method of manufacturing a plate with a printed layer and manufacturing results) <Example 1> As the plate of Example 1, "Doragontrail (registered trademark)" manufactured by AGC was used, and the first and second flat parts GA1 and GA2, the first and second bent parts GB1 and GB2, and the inclined part GC were formed by hot forming in the same manner as the plate G shown in Figures 1 (A) and (B). The length LG of the plate of Example 1 was 700 mm, and the width WG was 180 mm. The inclination angle θ1 of the inclined part GC with respect to the horizontal plane M was 10°. In addition, a device having the same configuration as the printing device 1 of the above embodiment was prepared as the printing device of Example 1. The printing device of Example 1 was equipped with one print head. The length L21 of the print head of Example 1 in the printing width direction shown in FIG. 4 was 150 mm. The print head of Example 1 had first and second nozzle row groups similar to the first and second nozzle row groups 216A and 216B of the print head 21 of the above embodiment. The first and second nozzle row groups were configured so that the effective print width WH shown in FIG. 3 was 50 mm. The first and second nozzle row groups were configured so that the number of print pixels in the print width direction, which is the Y-axis direction, i.e., the number of ink droplets landing, was 600 dpi. The distance R21 shown in FIG. 4 from the nozzles of the first nozzle row constituting the first nozzle row group to the end of the print head on the side in the print advance direction, and the distance R21 shown in FIG. 4 from the nozzles of the fourth nozzle row to the end of the print head on the side opposite to the print advance direction, were 6 mm.

[0092] Using the printing apparatus of Example 1 having the above-mentioned configuration, a printed layer was formed on the entire first main surface of the plate of Example 1, thereby producing the plate of Example 1 with a printed layer. When forming all the printing layers, all the nozzles constituting the first and second nozzle row groups were used as the nozzles to be used. That is, the nozzle row groups of the print head to be used in the inclined portion GC were set to the first nozzle row group located on the printing progress side and the second nozzle row group located on the opposite side to the printing progress side. With such settings, the number of print pixels in the printing progress direction when forming the printing layer was 600 dpi. While maintaining the nozzle opening surface parallel to the horizontal plane, the print head was moved in the printing progress direction and raised and lowered at a printing speed of 100 mm / sec so that the maximum distance from the opening surface of the nozzle to the plate, that is, the maximum value of the distances L1 and L2 shown in Figures 5(A) and (B), was 1.6 mm. In addition, ink was ejected from the nozzle to be used at an ejection frequency such that the number of print pixels in the printing progress direction, that is, the number of ink landings, was 600 dpi. In other words, ink was ejected from the nozzle to be used under conditions such that the number of print pixels in the printing width direction and the printing progress direction was 600 dpi. Since the effective printing width WH was approximately 27% of the width WG of the plate in Example 1, the print head was made to travel back and forth twice, and a printing layer was formed over the entire first main surface by changing the position in the printing width direction when moving in the printing progress direction or the opposite printing progress direction. In other words, the number of printing passes was four passes. The printing time was 28 seconds. Note that the printing time includes only the time when ink is being ejected, and does not include the time when ink is not being ejected, such as the time when the print head is moving. When the surface of the printed layer of the plate with the printed layer of Example 1 was observed with an optical microscope to evaluate the print quality, a high-quality printed layer was formed without any missing or uneven printing and without ink adhesion to any area other than the intended ink ejection position. In the following explanation, such a high-quality printed layer will be referred to as a printed layer with print quality "A".

[0093] <Example 2> As the plate of Example 2, a plate having the same shape as the plate of Example 1 was prepared. In addition, a printing device of Example 2 having the same configuration as the printing device of Example 1 was prepared. The printing device of Example 2 was equipped with three print heads of Example 2. The print head of Example 2 was equipped with first and second nozzle row groups, like the print head of Example 1. The print head of Example 2 had the same configuration as the print head of Example 1, except that the distance R21 from the nozzles of the first nozzle row to the end of the print head in the print progression direction was 18 mm. The three printheads of Example 2 were arranged in a staggered pattern along the print width direction so that the effective print width WH was 150 mm and the number of print pixels in the print width direction was 600 dpi across the entire effective print width WH. The first printhead row of Example 2 was composed of one printhead, and the second printhead row was composed of two printheads. As with the printing device 1 of the above embodiment, the printheads of Example 2 were arranged so that the position in the print width direction of the nozzles located at the end of the print width direction in the first printhead row was the same as the position in the print width direction of the nozzles located at the end of the print width direction in the second printhead row.

[0094] Using the printing apparatus of Example 2 having the above-mentioned configuration, a printed layer was formed on the entire first main surface of the plate of Example 2, thereby producing the plate of Example 2 with a printed layer. When forming all the printing layers, the nozzle row groups of each print head used in the inclined portion GC were set to the first and second nozzle row groups, as in Example 1. Except that each print head was moved so that the maximum distance from the opening surface of the nozzle used to the plate was 3.7 mm, each print head was moved under the same conditions as in Example 1, and ink was ejected from the nozzle used under conditions where the number of print pixels in the printing width direction and the printing progress direction was 600 dpi. Since the effective printing width WH was about 83% of the width WG of the plate in Example 2, the print head was made to go back and forth once, and the position in the printing width direction when moving in the printing progress direction or the opposite printing progress direction was changed, thereby forming a printing layer over the entire first main surface. In other words, the number of printing passes was 2 passes. In addition, the printing time was 14 seconds. As in Example 1, the printing quality of the printed layer plate of Example 2 was evaluated, and a printing layer with a printing quality of "A" was formed.

[0095] <Example 3> As the plate of Example 3, a plate having the same shape as the plate of Example 1 was prepared. In addition, a printing apparatus having the same configuration as the printing apparatus of Example 2 was prepared as the printing apparatus of Example 3. The printing apparatus of Example 3 was equipped with six print heads of Example 3. The print heads of Example 3 had the same configuration as the print heads of Example 2. The six printheads of Example 3 were arranged in a staggered pattern along the print width direction so that the effective print width WH was 300 mm and the number of print pixels in the print width direction was 600 dpi across the entire effective print width WH. The first and second printhead rows of Example 3 were each composed of three printheads, similar to the printing device 1 of the above embodiment. The printheads of Example 3 were arranged, similar to the printheads of Example 2, so that the positions in the print width direction of the nozzles located at the ends in the print width direction in the first printhead row were the same as the positions in the print width direction of the nozzles located at the ends in the print width direction in the second printhead row.

[0096] Using the printing apparatus of Example 3 having the above-mentioned configuration, a printing layer was formed on the entire first main surface of the plate of Example 3, thereby producing the plate of Example 3 with a printing layer. When forming all the printing layers, the nozzle row groups of each print head 21 used in the inclined portion GC were set to the first and second nozzle row groups, as in Examples 1 and 2. In addition, each print head was moved under the same conditions as in Example 2, and ink was ejected from the nozzles used under conditions that the number of printing pixels in the printing width direction and printing progress direction was 600 dpi. Then, since the effective printing width WH was larger than the width WG of the plate in Example 3, the print head was moved once in the printing progress direction to form a printing layer over the entire first main surface. In other words, the number of printing passes was one pass. Also, the printing time was 7 seconds. As in Example 1, the printing quality of the printed layer plate of Example 3 was evaluated, and a printed layer with a print quality of "A" was formed.

[0097] <Example 4> As the plate of Example 4, a plate having the same configuration as the plate of Example 1 was prepared, except that the inclination angle θ1 of the inclined portion GC with respect to the horizontal plane M was 32°. In addition, a printing apparatus having the same configuration as the printing apparatus of Example 3 was prepared as a printing apparatus of Example 4. The printing apparatus of Example 4 was equipped with six print heads of Example 4. The print heads of Example 4 had the same configuration as the print heads of Example 1. The six Example 4 printheads were arranged in a staggered pattern similar to Example 3.

[0098] Using the printing apparatus of Example 4 having the above-mentioned configuration, a printed layer was formed on the entire first main surface of the plate of Example 4, thereby producing the plate of Example 4 with a printed layer. When forming all the printing layers, the nozzles constituting only the first nozzle row group of each print head were used as the nozzles to be used. That is, the nozzle row group of each print head to be used in the inclined portion GC was set to only the first nozzle row group located on the printing progress direction side. With such a setting, the number of print pixels in the printing progress direction during the formation of the printing layer was 300 dpi. Each print head was moved under the same conditions as in Examples 1 to 3, except that each print head was moved so that the maximum distance from the opening surface of the nozzle to be used to the plate was 4.2 mm, and ink was ejected from the nozzle to be used at an ejection frequency such that the number of print pixels in the printing progress direction was 1200 dpi. That is, ink was ejected from the nozzle to be used under conditions such that the number of print pixels in the printing width direction and the printing progress direction were 300 dpi and 1200 dpi, respectively. As in Example 3, the number of printing passes was 1 pass, and the printing time was 7 seconds. As in Example 1, the printing quality of the printed layer plate of Example 4 was evaluated, and a printed layer with a print quality of "A" was formed. Furthermore, if the nozzle row group of each print head used in the inclined portion GC and the first and second bend portions GB1, GB2 are set to only the first nozzle row group, and the nozzle row groups of each print head used in the first and second flat portions GA1, GA2 are set to the first nozzle row group and the second nozzle row group, a print layer with print quality "A" can be formed in a shorter time than in Example 4 above.

[0099] <Example 5> As the plate of Example 5, a plate having the same shape as the plate of Example 4 was prepared. As the printing apparatus of Example 5, the printing apparatus of Example 3 was prepared. Using the printing apparatus of Example 5, a printing layer was formed on the entire first main surface of the plate of Example 5, thereby producing the plate with a printing layer of Example 5. When forming all the printing layers, the nozzle row groups of each print head used in the inclined portion GC were set to the first and second nozzle row groups, as in Examples 1 to 3. Each print head was moved under the same conditions as in Examples 1 to 4, except that each print head was moved so that the maximum distance from the opening surface of the nozzle used to the plate was 11.7 mm, and ink was ejected from the nozzle used under conditions such that the number of print pixels in the printing width direction and printing progress direction was 600 dpi. As in Examples 3 and 4, the number of printing passes was 1 pass, and the printing time was 7 seconds. Although a printing layer was formed on a plate of the same shape in Example 4 and Example 5, the maximum distance from the opening surface of the used nozzles to the plate in Example 5 is greater than that in Example 4. This is because, when the print head is moved at the inclined portion so as not to come into contact with the plate, the distance from the opening surface of the used nozzles of the second nozzle row group to the plate becomes longer than the distance from the opening surface of the used nozzles of the first nozzle row group to the plate. As in Example 1, the printing quality of the printed layer plate of Example 5 was evaluated, and it was found that although there was some unevenness in the printing, the printing layer was formed at a level that was acceptable for the product. In the following explanation, the printing layer with some unevenness in the printing but at a level that was acceptable for the product will be referred to as a printing layer with a printing quality of "B".

[0100] <Example 6> As the plate of Example 6, a plate having the same configuration as the plate of Example 1 was prepared, except that the inclination angle θ1 of the inclined portion GC with respect to the horizontal plane M was 60°. As the printing apparatus of Example 6, the printing apparatus of Example 4 was prepared. Using the printing apparatus of Example 6, a printing layer was formed on the entire first main surface of the plate of Example 6, thereby producing the plate with the printing layer of Example 6. When forming all the printing layers, the nozzle row group of each print head used in the inclined portion GC was set to the first nozzle row group, as in Example 4. Each print head was moved under the same conditions as in Examples 1 to 5, except that each print head was moved so that the maximum distance from the opening surface of the nozzle used to the plate was 10.9 mm, and ink was ejected from the nozzle used under conditions such that the number of print pixels in the printing width direction and printing progress direction were 300 dpi and 1200 dpi, respectively. As in Examples 3 to 5, the number of printing passes was 1 pass, and the printing time was 7 seconds. Although only the first nozzle row group was used in Examples 4 and 6, the maximum distance from the opening surface of the used nozzles to the plate in Example 6 is greater than that in Example 4. This is because the inclination angle of the inclined portion in Example 6 is greater than that in Example 4, and therefore when the print head is moved so as not to come into contact with the plate, the distance from the opening surface of the used nozzles of the sixth first nozzle row group to the plate is longer than that in Example 4. As in Example 1, the printing quality of the printed layer-formed plate of Example 6 was evaluated, and a printed layer with a printing quality of "B" was formed.

[0101] <Example 7> As the plate of Example 7, a plate having the same shape as the plate of Example 6 was prepared. As the printing apparatus of Example 7, the printing apparatus of Example 5 was prepared. Using the printing apparatus of Example 7, a printing layer was formed on the entire first main surface of the plate of Example 7, thereby producing the plate with the printing layer of Example 7. When forming all the printing layers, the nozzle row groups of each print head used in the inclined portion GC were set to the first and second nozzle row groups, as in Examples 1 to 3 and 5. Each print head was moved under the same conditions as in Examples 1 to 6, except that each print head was moved so that the maximum distance from the opening surface of the nozzle used to the plate was 31.7 mm, and ink was ejected from the nozzle used under conditions such that the number of print pixels in the printing width direction and printing progress direction was 600 dpi. As in Examples 3 to 6, the number of printing passes was 1 pass, and the printing time was 7 seconds. Although printing layers were formed on plates of the same shape in Examples 6 and 7, the maximum distance from the opening surface of the nozzle used to the plate in Example 7 is greater than that in Example 6 for the same reason that the maximum distance from the opening surface of the nozzle used to the plate in Example 4 is greater than that in Example 5. As in Example 1, when the printing quality of the plate with the printed layer of Example 7 was evaluated, there was a lot of printing unevenness, and there were areas where the ink did not land in the specified position, and a printed layer was formed that was problematic as a product. In the following explanation, such a printed layer that is problematic as a product will be referred to as a printed layer with a print quality of "C".

[0102] (Consideration) The methods for producing the printed layer-attached plates of the above-mentioned Examples 1 to 7 and the production results are shown in Table 1 below.

[0103] [Table 1]

[0104] <Number of print heads> When manufacturing a plate with a printed layer using a plate of the same shape, the number of printing passes was four when using the printing device of Example 1 with one print head, whereas the number of printing passes was two or less when using the printing devices of Examples 2 to 7 with multiple print heads. This confirms that by using multiple print heads positioned at different positions in the printing width direction, a printed layer can be formed more efficiently than when a single print head is used.

[0105] <Maximum distance from the nozzle opening to the plate> The print quality of the printed layer plate of Example 7, where the maximum distance from the opening surface of the nozzle used to the plate exceeded 20 mm, was rated "C", the print quality of the printed layer plates of Examples 5 and 6, where the maximum distance from the opening surface of the nozzle used to the plate exceeded 10 mm and was less than 20 mm, was rated "B", and the print quality of the printed layer plates of Examples 1 to 4, where the maximum distance was less than 10 mm, was rated "A". In this way, the print quality decreases as the maximum distance from the opening surface of the nozzle in use to the plate increases. This is thought to be because the farther the nozzle in use is from the plate, the more likely the ink is to become mist-like before it hits the plate. From this, it was confirmed that by forming the printing layer when the maximum distance from the opening surface of the nozzle to the plate is 20 mm or less, the deterioration of the printing quality of the printing layer can be suppressed, and that by forming the printing layer when the distance is 10 mm or less, a high-quality printing layer can be formed. [Explanation of symbols]

[0106] 1...printing device, 21...print head, 212...nozzle, 3...head pressure maintaining section, 4...relative movement mechanism (relative movement section), 552...ejection control section, 553...print head movement control section (relative movement section), B1, B2, B3, B4...first, second, third, fourth boundaries, G...plate, G1...first main surface, GA1, GA2...first and second flat sections, GB1, GB2...first and second bent sections, GC...inclined section, GP...plate with printed layer, GQ...printed area, GR...non-printed area, M...horizontal surface, N...ink, P...printed layer.

Claims

1. A method for producing a plate with a printed layer, comprising forming a printed layer by an inkjet method on a main surface of a plate having a bent portion bent in a plate thickness direction, Using a plurality of print heads each having at least one nozzle, A method for manufacturing a plate with a printed layer, comprising the steps of: ejecting ink from the nozzles of the multiple print heads while moving the multiple print heads and the plate relative to one another to form a printed layer on the main surface; moving the multiple print heads and the plate relative to one another such that the distance from the nozzles ejecting the ink to the main surface is 20 mm or less.

2. The method for producing a printed layer-attached plate according to claim 1, A method for manufacturing a plate with a printed layer, in which the process of moving the multiple print heads and the plate relative to each other involves moving the multiple print heads in the printing progress direction while raising or lowering them according to the shape of the curved portion of the main surface without moving the plate.

3. The method for producing a printed layer-attached plate according to claim 2, each of the plurality of print heads includes a plurality of nozzles that are positioned differently in the printing progress direction; A method for manufacturing a plate with a printed layer, comprising: moving the multiple print heads while maintaining the opening faces of the multiple nozzles parallel to a horizontal plane; and ejecting the ink only from the multiple nozzles that have different positions in the printing direction and are located 20 mm or less away from the main surface in the printing direction or the nozzles on the opposite side to the printing direction in accordance with the inclination of the main surface.

4. The method for producing a printed layer-attached plate according to claim 3, A method for manufacturing a plate with a printed layer, comprising ejecting the ink from the nozzle, the distance to the main surface being 10 mm or less.

5. The method for producing a printed layer-attached plate according to claim 2, the plurality of print heads are composed of two or more print heads positioned at different positions in the printing progression direction, and are provided with a plurality of the nozzles arranged to line up in a printing width direction perpendicular to the printing progression direction, and are arranged such that, when viewed from the printing progression direction side, a portion of one end side of the printing width direction of one of the adjacent print heads overlaps with a portion of the other end side of the printing width direction of the other print head.

6. The method for producing a printed layer-attached plate according to claim 5, The method for manufacturing a plate with a printed layer, wherein the multiple print heads are composed of three or more print heads arranged offset from each other in the printing width direction.

7. The method for producing a printed layer-attached plate according to claim 5 or 6, the nozzles are disposed in the adjacent print heads at positions that overlap when viewed from the printing progress direction, A method for manufacturing a plate with a printed layer, comprising controlling the state of ejection of the ink from the nozzles so that the number of landing droplets of the ink per unit area in the printing region of the main surface is equal.

8. The method for producing a printed layer-attached plate according to claim 5 or 6, The plate with the printing layer includes a printing area where the printing layer is formed and a non-printing area where the printing layer is not formed, the nozzles are disposed in the adjacent print heads at positions that overlap when viewed from the printing progress direction, A method for manufacturing a plate with a printed layer, the method controlling the timing of ink ejection from the nozzle depending on the shape of the boundary between the printed area and the non-printed area that intersects with the printing progression direction.

9. The method for producing a printed layer-attached plate according to any one of claims 1 to 6, A method for manufacturing a plate with a printed layer, wherein the multiple print heads are arranged so that the printed layer can be formed across the entire printing width direction in the printing area of ​​the main surface with a single movement in the printing progress direction.

10. The method for producing a printed layer-attached plate according to any one of claims 2 to 6, A method for manufacturing a plate with a printed layer, comprising ejecting the ink while maintaining an absolute value of pressure fluctuation relative to a pressure setting value of the meniscus of the nozzle during formation of the printed layer at 0.2 kPa or less.

11. The method for producing a printed layer-attached plate according to any one of claims 1 to 6, A method for manufacturing a plate with a printed layer, wherein the bent portion is bent around one bending axis.

12. The method for producing a printed layer-attached plate according to claim 11, A method for manufacturing a plate with a printed layer, wherein the radius of curvature of the bent portion is 10 mm or more and less than 10,000 mm.

13. A printing apparatus for manufacturing a plate having a printed layer by forming a printed layer on a main surface of a plate having a bent portion bent in a plate thickness direction by an inkjet method, a plurality of printheads each having at least one nozzle; an ejection control unit for ejecting ink from the nozzles of the plurality of print heads to form the printing layer on the main surface; a relative movement unit that moves the plurality of print heads and the plate relative to each other so that the distance from the nozzles that eject the ink to the main surface is 20 mm or less.

14. 14. The printing device according to claim 13, The relative movement unit is A plate holding portion that holds the plate in a stationary state; a print head moving unit that moves the plurality of print heads; a print head movement control unit that controls the print head movement unit so as to move the multiple print heads in a printing progress direction while raising or lowering them in accordance with a shape of the bent portion of the main surface.

15. 15. The printing device according to claim 14, each of the plurality of print heads includes a plurality of nozzles that are positioned differently in the printing progress direction; the print head movement control unit controls the print head movement unit to move the plurality of print heads while maintaining a state in which opening faces of the plurality of nozzles are parallel to a horizontal plane; The ejection control unit ejects the ink from a nozzle that is located at a distance to the main surface of 20 mm or less among the plurality of nozzles that are positioned differently in the printing progress direction in accordance with an inclination of the main surface.

16. 15. The printing device according to claim 14, the plurality of print heads are provided with a plurality of nozzles arranged in a line in a printing width direction perpendicular to the printing progression direction, and are arranged such that, when viewed from the printing progression direction side, a portion of one end side of the printing width direction of one of the adjacent print heads overlaps with a portion of the other end side of the printing width direction of the other print head.

17. 17. The printing device according to claim 16, A printing device, wherein the plurality of print heads are composed of three or more print heads arranged in a shifted state relative to one another in the printing width direction.

18. 18. The printing device according to claim 16 or 17, the nozzles are disposed in the adjacent print heads at positions that overlap when viewed from the printing progress direction, The ejection control unit controls the ejection state of the ink from the nozzles so that the number of landing droplets of the ink per unit area in a printing region of the main surface is equal.

19. 18. The printing device according to claim 16 or 17, The plate with the printing layer includes a printing area where the printing layer is formed and a non-printing area where the printing layer is not formed, the nozzles are disposed in the adjacent print heads at positions that overlap when viewed from the printing progress direction, The ejection control unit controls the timing of ejection of the ink from the nozzles in accordance with a shape of a boundary between the printing area and the non-printing area that intersects with the printing progress direction.

20. 18. The printing device according to claim 14, A printing device, wherein the multiple print heads are positioned so that the printing layer can be formed over the entire printing width direction in the printing area of ​​the main surface by a single movement in the printing progress direction.

21. 18. The printing device according to claim 14, A printing apparatus comprising a head pressure maintaining unit that maintains an absolute value of pressure fluctuation with respect to a pressure setting value of the meniscus of the nozzle during formation of the printing layer at 0.2 kPa or less.

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