JP2011110818A - Inkjet printer and printing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem wherein mixing of color ink etc., and white ink etc., cannot be prevented sufficiently, and thus, appropriately inexpensively perform multi-layer printing. <P>SOLUTION: This inkjet printer 10 includes: heads 14 for color printing; a head 16 for white layer formation which is a head for multi-layer formation; and a scanning control part 12. The scanning control part 12 includes a nozzle selection part 106, a main scanning control part 102 and an auxiliary scanning control part 104. The nozzle selection part 106 sets a color nozzle selection region 202 and a clearance region 206 in part of a nozzle row of the heads 14 for color printing, and sets a white layer nozzle selection region 204 in a portion where the position of the auxiliary scanning direction is not superposed on the color nozzle selection region 202 and the clearance region 206 in a nozzle row of the head 16 for white layer formation. The main scanning control part 102 discharges ink droplets from nozzles within the color nozzle selection region 202 and nozzles within the white layer nozzle selection region 204, in the main scanning operation. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an inkjet printer and a printing method.

  Due to the widespread use of inkjet printers, in recent years, for example, it has been required to form an ink layer formed of white ink, clear ink, or the like on a color printing layer printed with color printing ink such as YMCK ink. May be. In this case, if white ink or clear ink is simply printed simultaneously in the same place as the color printing ink, problems such as color mixing occur, and therefore printing cannot be performed appropriately. Therefore, conventionally, when using white ink or the like in this way, for example, after forming one layer, the relative position between the medium and the inkjet head is returned to the original position, and then the next layer is formed. To do. Therefore, when performing such printing, for example, a flat bed type ink jet printer capable of returning the relative position between the medium and the ink jet head with high accuracy is used.

Special table 2008-530619 gazette

  Multi-layer printing in which a plurality of ink layers are stacked is not limited to a flat bed type ink jet printer, and may be performed by a vertical ink jet printer or the like. In this case, for example, a registration mark such as a registration mark is formed at the time of printing the lower layer, and then the next layer is printed by rewinding the medium and correcting the position. Also, when using a medium that does not have a medium pull-back mechanism, for example, a dedicated inkjet head such as white ink is placed at a position that is later in time or earlier than the inkjet head for color printing ink. Using the provided structure, printing of a white ink layer or the like is performed after the end of color printing or before color printing.

  However, these methods require the addition of a registration mark detection mechanism, a dedicated ink jet head such as white ink provided at a special position, and a mechanism for driving the same, which raises the cost. Further, in the case where another inkjet head is provided at a position that is later in time or earlier than an ink jet head for color printing ink, the order of the layers that can be formed is limited by the positional relationship between the two inkjet heads. Therefore, it becomes difficult to perform various multilayer printing. Therefore, it is desired to perform multilayer printing by a more appropriate method.

  In addition, as a result of investigating prior art relating to the present invention, Patent Document 1 that performs multi-layer digital UV inkjet printing was discovered. However, the method disclosed in Patent Document 1 cannot sufficiently prevent mixing of color ink and white ink and the like, and it may be difficult to perform appropriate multilayer printing. Accordingly, an object of the present invention is to provide an ink jet printer and a printing method that can solve the above-described problems.

In order to solve the above problems, the present invention has the following configuration.
(Configuration 1) Main scanning operation for moving the inkjet head relative to the medium in a preset main scanning direction, and moving the inkjet head relative to the medium in a sub-scanning direction orthogonal to the main scanning direction An ink jet printer that performs printing on each position of the medium by performing a sub-scanning operation, and ejects ink droplets that form a color print layer on which color printing has been performed, and is parallel to the sub-scanning direction A plurality of nozzles arranged in the direction of the nozzle row, and when the main scanning operation is performed, by ejecting ink droplets from the plurality of nozzles while moving in the main scanning direction, for each main scanning operation A color printing head forming a portion corresponding to the main scanning operation in the color printing layer, and an ink layer printed on or under the color printing layer An inkjet head that ejects ink droplets that form a multilayer print layer, having a nozzle row in which a plurality of nozzles are arranged in the nozzle row direction, aligning the position in the sub-scanning direction with the color printing head, and in the main scanning direction When the main scanning operation is performed, ink droplets are ejected from a plurality of nozzles while moving in the main scanning direction, so that the main scanning is performed in the multilayer printing layer for each main scanning operation. A multi-layer forming head that forms a portion corresponding to the operation, and a scan control unit that controls a main scanning operation and a sub-scanning operation of the color printing head and the multi-layer forming head. A nozzle selection unit that selects a nozzle to eject ink droplets from a color printing head and a multilayer formation head, and a color printing head and multilayer formation. A main scanning control unit that causes the head to perform a main scanning operation; and a sub-scanning control unit that causes the color printing head and the multi-layer forming head to perform a sub-scanning operation. A part of the column is an area of a nozzle selection width whose length in the nozzle column direction is set in advance, and includes a color nozzle selection region including a plurality of nozzles continuously arranged in the nozzle column direction, and color in the nozzle column This is a gap area set adjacent to the nozzle selection area, and a gap area including one or more nozzles is set, and the nozzles in the color nozzle selection area are set in the color printing head during the main scanning operation. A nozzle is selected as a nozzle to eject ink droplets, and a position in the sub-scanning direction of the nozzle row of the multi-layer formation head is not located in a portion where it does not overlap with the color nozzle selection area and the gap area. The length in the nozzle row direction is the same nozzle selection width as the color printing head, and a multi-layer nozzle selection region including a plurality of nozzles continuously arranged in the nozzle row direction is set. The nozzle is selected as a nozzle that should eject ink droplets during the main scanning operation in the multi-layer forming head, and the main scanning control unit selects the nozzles in the color nozzle selection area in the color printing head and the multi-layer in the main scanning operation. While ejecting ink droplets from the nozzles in the multi-layer nozzle selection area of the forming head, the color printing head and multi-layer forming head are moved in the main scanning direction relative to the medium, and the sub-scanning control unit In the sub-scanning operation, the color printing head is set relatively to the medium by a distance set corresponding to the nozzle selection width per sub-scanning operation. And moving the layer forming head in the sub-scanning direction. The ink jet printer, for example, repeats the main scanning operation and the sub scanning operation, so that the color printing head and the color printing head in the sub scanning direction are relatively relative to the medium by the length of the printing area of the medium in the sub scanning direction. While the multi-layer forming head moves once, the color print layer and the multi-layer print layer are formed on the printing area.

  With this configuration, for example, multilayer printing in which a plurality of ink layers are formed in an overlapping manner can be appropriately performed without performing a step of returning the medium position in the sub-scanning direction. The step of returning the position of the medium in the sub-scanning direction is, for example, that the relative position of the inkjet head to the medium in the sub-scanning direction is changed to one layer after printing one layer and before printing the next layer. This is the step of returning to the position before the start of printing.

  In this case, since there is no need to return the medium position in the sub-scanning direction, it is not necessary to provide a registration mark detection mechanism. In addition, the multi-layer forming head is provided at a position adjacent to the color printing head in the main scanning direction, for example, in the same manner as the position where the ink jet head for white ink or clear ink is provided in a conventional general ink jet printer. be able to. Therefore, for example, it is not necessary to provide the multilayer formation head at a special position. As a result, it is not necessary to add a special mechanism or the like for driving it. Therefore, if constituted in this way, multilayer printing can be performed at low cost, for example. In addition, for example, multilayer printing can be performed more appropriately with the same configuration as a conventional vertical ink jet printer.

  Furthermore, in the case of such a configuration, by setting the gap region, for example, it is possible to appropriately prevent the ink of the layer printed later from being mixed with the ink of the layer printed earlier. Therefore, if comprised in this way, multilayer printing can be performed more appropriately, for example.

  The nozzle selection width is set in accordance with, for example, the number of layers formed in an overlapping manner. For the multi-layer forming head, the color printing head and the position in the sub-scanning direction are provided to be the same, for example, that the nozzle row of each inkjet head is provided in the same position in the sub-scanning direction. The fact that the positions of the nozzle rows in the sub-scanning direction are provided in a uniform manner means that the positions of the top and the bottom of the nozzle rows are provided with a precision within a range allowed according to the printing resolution. . In the sub-scanning operation, the distance set corresponding to the nozzle selection width is, for example, a distance obtained by dividing the nozzle selection width by the number of printing scans (pass number) N.

  The ink jet printer includes, for example, a plurality of color printing heads corresponding to the respective color inks for color printing. In this case, each color printing head, for example, discharges ink droplets of each color of YMCK ink. The plurality of color printing heads are provided, for example, in the main scanning direction with the positions in the sub scanning direction aligned.

  The multilayer printing head ejects ink droplets such as white ink and clear ink. The multilayer printing head may eject ink that is opaque and cannot be used at the same time as color printing ink, for example, ink droplets of opaque black ink, or ink droplets of special colors such as metallic colors. Further, as the multi-layer forming head, it is conceivable to use a part or all of a plurality of color printing heads. In this case, the multilayer print layer may also be a color printed layer.

  (Configuration 2) The color printing head and the multi-layer forming head each discharge ink droplets of ultraviolet curable ink, which is ink that is cured by ultraviolet irradiation, and the inkjet printer irradiates ultraviolet rays toward the medium. And an ultraviolet irradiation unit provided at a position behind the movement of the color printing head and the multi-layer forming head in the main scanning direction during the main scanning operation. In this case, while irradiating the ultraviolet irradiation unit with ultraviolet rays to the ink ejected from the color printing head and the multilayer formation head and landing on the medium, the color printing head, the multilayer formation head, and the ultraviolet irradiation unit are applied to the medium. On the other hand, it is moved in the main scanning direction.

  According to this configuration, for example, at each position on the medium, before the ink ejected from one of the color printing head and the multilayer forming head landed, the ultraviolet rays before the ink ejected from the other landed. Can be irradiated appropriately. Thereby, for example, a plurality of ink layers can be appropriately formed.

  The ink jet printer may include a plurality of ultraviolet irradiation units. The plurality of ultraviolet irradiation units are provided, for example, at positions sandwiching the color printing head and the multilayer forming head from both sides in the main scanning direction. With this configuration, for example, printing can be appropriately performed in both the forward path and the backward path of movement in the main scanning direction.

  (Configuration 3) The length of the gap region in the nozzle row direction is larger than the maximum variation in the sub-scanning direction of the landing positions of the ink droplets ejected from the color printing head and the multilayer formation head. The maximum variation in the sub-scanning direction of the ink droplet landing position is, for example, the maximum variation allowed in design for a normal nozzle. If comprised in this way, it can prevent more appropriately that the ink of the layer printed later, for example is mixed with the ink of the layer printed previously.

  (Configuration 4) The sub-scanning control unit is a color printing head relative to the medium by a distance of 1 / N (N is an integer of 2 or more) of the nozzle selection width per sub-scanning operation. And the multi-layer forming head is moved in the sub-scanning direction, and the ink jet printer performs printing at each position on the medium for each of the color print layer and the multi-layer print layer with a sub-scan operation between each time N The length of the gap region in the nozzle row direction is equal to the distance by which the color printing head and the multilayer forming head are moved in the sub-scanning direction in one sub-scanning operation.

  When configured in this way, the ink jet printer sets the number of scans (passes) for printing for each position of the medium to N times, and each of the color print layer and the multilayer print layer is N times for each position on the medium. It is formed by N scan printing (N pass printing) for performing the main scanning operation. Therefore, if constituted in this way, high-definition printing can be performed appropriately.

  In this case, the length of the gap region in the sub-scanning direction is equal to the pass feed width that is one movement distance in the sub-scanning operation. Therefore, in order to consider the influence of the gap area in the data for controlling the printing operation of the ink jet printer, the main scanning corresponding to each position of the medium is performed using the data for forming the color print layer and the data for forming the multilayer print layer. It is only necessary to shift the data by an amount corresponding to the pass feed width. Therefore, with this configuration, for example, for each of the color print layer and the multilayer print layer, the correspondence between each position of the medium and the main scanning operation can be easily considered. Thereby, for example, the operation of the ink jet printer can be controlled more easily.

  (Configuration 5) The length of the gap region in the nozzle row direction is smaller than the distance for moving the color printing head and the multilayer forming head in the sub-scanning direction in one sub-scanning operation.

  If comprised in this way, the influence on the printing speed by providing a clearance gap area can be reduced, for example. This also makes it possible to perform printing at a higher speed, for example. The gap region may be a region including 1 to 3 nozzles arranged in the nozzle row direction, for example. Further, the length of the gap region in the nozzle row direction may be, for example, the minimum width allowed for mechanical accuracy in controlling the inkjet head.

  (Configuration 6) The nozzle selection unit includes a plurality of color nozzle selection areas, the lengths of the two gap areas in the nozzle array direction between the adjacent color nozzle selection areas, and the nozzle array of the multi-layer nozzle selection area A plurality of gaps that are set adjacent to the side where the other color nozzle selection area is set with respect to each color nozzle selection area, with a width equal to or greater than the sum of the direction lengths being set at least. Set the area and set the multi-layer nozzle selection area in the nozzle row of the multi-layer formation head at the part where the position in the sub-scanning direction overlaps the area sandwiched between multiple gap areas in the color printing head To do.

  If constituted in this way, multilayer printing including a plurality of color printing layers can be performed appropriately, for example. In addition, for example, it is possible to appropriately perform more various multilayer printing.

  For example, when a translucent medium that allows an image printed on the printing surface of the medium to be viewed from the back side is used, the first color printing layer and at least one multi-layer are formed on the printing surface on one side of the medium. By overlapping the print layer and the second color print layer, printing can be performed so that images can be observed from both sides of the medium. This also makes it possible to perform pseudo double-sided printing by printing only on one side of the medium.

  The lengths of the color nozzle selection regions in the nozzle row direction are preferably the same nozzle selection width. The nozzle selection unit may set three or more color nozzle selection regions corresponding to three or more color print layers. In addition, for example, an inkjet printer forms at least one multi-layer print layer between a plurality of color print layers. The inkjet printer may form a plurality of multi-layer printing layers between a plurality of color printing layers. In this case, any of the plurality of multi-layer print layers is formed of, for example, a light-shielding ink. This light-shielding ink may be, for example, metallic ink or opaque black ink.

  (Configuration 7) The nozzle selection unit sets a plurality of multi-layer nozzle selection areas on which multi-layer print layers formed corresponding to the respective multi-layer nozzle selection areas are printed.

  If comprised in this way, the multilayer printing containing a some multilayer printing layer can be performed appropriately, for example. In addition, for example, it is possible to appropriately perform more various multilayer printing.

  The length of each multi-layer nozzle selection region in the nozzle row direction is preferably the same nozzle selection width. For example, the nozzle selection unit forms a plurality of multi-layer nozzle selection regions, for example, with a width corresponding to the gap region in the nozzle row direction. The ink jet printer, for example, prints a plurality of multi-layer print layers corresponding to each multi-layer nozzle selection region in an overlapping manner. In this case, for example, the inkjet printer may form a plurality of multilayer printing layers between the plurality of color printing layers.

  (Configuration 8) A main scanning operation for moving the inkjet head relative to the medium in a preset main scanning direction, and a movement of the inkjet head relative to the medium in a sub-scanning direction orthogonal to the main scanning direction A sub-scanning operation for printing on each position of the medium by an ink-jet method, and an ink-jet head that ejects ink droplets that form a color-printed color print layer. A plurality of nozzles arranged in a nozzle row direction parallel to the direction, and each main scan is performed by ejecting ink droplets from the plurality of nozzles while moving in the main scan direction when the main scan operation is performed. For each operation, a color printing head for forming a portion corresponding to the main scanning operation in the color printing layer and an ink printed on or under the color printing layer are printed. An inkjet head that ejects ink droplets that form a multi-layer print layer, and has a nozzle row in which a plurality of nozzles are arranged in the nozzle row direction, and is aligned with the color printing head in the sub-scanning direction, and By shifting the position in the main scanning direction and ejecting ink droplets from a plurality of nozzles while moving in the main scanning direction when the main scanning operation is performed, the multi-layer printing layer Scan control for controlling the main scanning operation and the sub-scanning operation of the color printing head and the multilayer forming head is performed on the multi-layer forming head that forms a portion corresponding to the main scanning operation. In the operation, a nozzle selection stage for selecting a nozzle to eject ink droplets from each of the color printing head and the multilayer forming head, and a color printing head. And a main scanning control stage for causing the multi-layer forming head to perform a main scanning operation and a sub-scanning control stage for causing the color printing head and the multi-layer forming head to perform a sub-scanning operation. The nozzle selection stage is for color printing. A nozzle selection region for a color including a plurality of nozzles continuously arranged in the nozzle row direction, which is a region of a nozzle selection width in which the length in the nozzle row direction is preset in a part of the nozzle row of the head, and the nozzle row Is a gap area set adjacent to the color nozzle selection area and includes a gap area including one or more nozzles, and the nozzles in the color nozzle selection area are mainly used in the color printing head. In the scanning operation, the ink droplets are selected as the nozzles to be ejected, and the position in the sub-scanning direction is the color nozzle selection area and the gap area in the nozzle row of the multilayer formation head. In the non-overlapping part, set the multi-layer nozzle selection area that includes a plurality of nozzles that are continuously arranged in the nozzle row direction, and that has the same nozzle selection width as the color print head in the nozzle row direction. The nozzles in the nozzle selection area are selected as nozzles that should eject ink droplets during the main scanning operation in the multi-layer forming head, and the main scanning control step is performed in the color nozzle selection area in the color printing head in the main scanning operation. The nozzles in the multi-layer formation head and the nozzles in the multi-layer nozzle selection area of the multi-layer formation head are ejected ink droplets, while moving the color printing head and the multi-layer formation head in the main scanning direction relative to the medium, In the sub-scanning control step, the sub-scanning operation is performed with respect to the medium by a distance set corresponding to the nozzle selection width per sub-scanning operation. To move the color printing head and layer forming head in the sub-scanning direction. In this way, for example, the same effect as that of Configuration 1 can be obtained.

  According to the present invention, for example, multilayer printing can be appropriately performed at low cost.

1 is a diagram illustrating an example of an inkjet printer 10 according to an embodiment of the present invention. FIG. 1A shows an example of the configuration of the inkjet printer 10. FIG. 1B shows an example of the configuration of the color printing head 14 and the white layer forming head 16 in the inkjet printer 10. It is a figure which shows an example of the color printing layer and white ink layer which are formed in each main scanning operation | movement. It is a figure which shows the example in the case of performing multilayer printing of 3 layers. It is a figure which shows an example of the multilayer printing containing more layers. FIG. 4A is a diagram illustrating an example of how to select a nozzle. FIG. 4B shows an example of the layer configuration in the printing result. It is a figure which shows the specific example of each layer shown in FIG.4 (b). FIG. 5A shows an example of the first color print layer 602. FIG. 5B shows an example of the first light reflecting layer 604. FIG. 5C shows an example of the light shielding layer 606. It is a figure which shows the specific example of each layer shown in FIG.4 (b). FIG. 6A shows an example of the second light reflecting layer 608. FIG. 6B shows an example of the second color print layer 610.

  Hereinafter, embodiments according to the present invention will be described with reference to the drawings. FIG. 1 shows an example of an inkjet printer 10 according to an embodiment of the present invention. FIG. 1A shows an example of the configuration of the inkjet printer 10. FIG. 1B shows an example of the configuration of the color printing head 14 and the white layer forming head 16 in the inkjet printer 10. In this example, the ink jet printer 10 is a vertical ink jet printer, and includes a scanning control unit 12, a plurality of color printing heads 14, a white layer forming head 16, and a plurality of ultraviolet irradiation units 18.

  The ink jet printer 10 performs printing at each position of the medium 50 by performing, for example, a main scanning operation and a sub scanning operation. The main scanning operation is, for example, a method in which the color printing head 14 and the white layer forming head 16 are set in advance while ejecting ink droplets to the color printing head 14 and the white layer forming head 16 which are inkjet heads. This is an operation of moving relative to the medium 50 in the scanning direction. Further, the sub-scanning operation refers to, for example, moving the color printing head 14 and the white layer forming head 16 relative to the medium 50 in the sub-scanning direction orthogonal to the main scanning direction between main scanning operations. It is an action to make. The vertical ink jet printer is, for example, an ink jet printer that moves the medium 50 side in the sub-scanning operation.

  Although not shown, the inkjet printer 10 is configured to perform printing operations such as a roller that transports the medium 50, a color printing head 14, a white layer forming head 16, and a driving device that drives the ultraviolet irradiation unit 18. It is further provided with various configurations necessary for the above. In this example, the ink jet printer 10 performs the main scanning operation by fixing the position of the medium 50 in the main scanning direction and moving the color printing head 14 and the white layer forming head 16 side. Further, the positions of the color printing head 14 and the white layer forming head 16 in the sub-scanning direction are fixed, and the sub-scanning operation is performed by moving the medium 50 side by conveyance. The ink jet printer 10 may be a flat bed type ink jet printer. In this case, in the sub-scanning operation, the inkjet printer 10 moves the color printing head 14 and the white layer forming head 16 side.

  The scanning control unit 12 is a control unit that controls the main scanning operation and the sub scanning operation of the color printing head 14 and the white layer forming head 16, and includes a main scanning control unit 102, a sub scanning control unit 104, and a nozzle selection unit. 106. The main scanning control unit 102 causes the color printing head 14 and the white layer forming head 16 to perform a main scanning operation. In this example. The main scanning control unit 102 causes the color printing head 14 and the white layer forming head 16 to eject ink droplets in both the forward path and the backward path of movement in the main scanning direction. Further, the sub-scanning control unit 104 causes the color printing head 14 and the white layer forming head 16 to perform a sub-scanning operation by transporting the medium 50 by, for example, a roller and moving the medium 50 side.

  The nozzle selection unit 106 selects a nozzle that should eject ink droplets in the main scanning operation from a plurality of nozzles in each of the color printing head 14 and the white layer forming head 16. The nozzle that should eject ink droplets in the main scanning operation is, for example, a nozzle that should eject ink droplets as necessary according to the image to be printed. Details of the nozzle selection will be described in more detail later.

  The color printing head 14 is an inkjet head that ejects ink droplets that form a color printing layer on which color printing has been performed. Each of the plurality of color printing heads 14 ejects ink droplets of each color of YMCK ink, for example. Further, in this example, the color printing head 14 ejects ink droplets of ultraviolet curable ink, which is ink cured by irradiation of ultraviolet rays, as ink droplets of each color of YMCK ink.

  Each color printing head 14 has, for example, a nozzle row 302 in which a plurality of nozzles 304 are arranged in a nozzle row direction parallel to the sub-scanning direction, and moves in the main scanning direction when the main scanning operation is performed. Meanwhile, ink droplets are ejected from the plurality of nozzles 304 selected by the nozzle selection unit 106. Thus, the color printing head 14 forms a portion corresponding to the main scanning operation in the color printing layer for each main scanning operation. In this example, the plurality of color printing heads 14 are provided, for example, in the main scanning direction with the positions in the sub scanning direction aligned.

  The white layer forming head 16 is an ink jet as an example of a multi-layer forming head, and forms a white ink layer as an example of a multi-layer printing layer by ejecting ink droplets of white ink. The multilayer formation head is, for example, an inkjet head that ejects ink droplets that form a multilayer print layer. The multi-layer print layer is, for example, a layer of ink that is printed over or under the color print layer. In this example, the white layer forming head 16 ejects ink droplets of ultraviolet curable ink as white ink. The white layer forming head 16 is provided so as to be aligned with the color printing head 14 in the sub-scanning direction and shifted in the main scanning direction.

  The white layer forming head 16 has a nozzle row 302 in which a plurality of nozzles 304 are arranged in the nozzle row direction, and is selected by the nozzle selection unit 106 while moving in the main scanning direction when the main scanning operation is performed. Ink droplets are ejected from the plurality of nozzles 304. Accordingly, the white layer forming head 16 forms a portion corresponding to the main scanning operation in the white ink layer for each main scanning operation.

  Here, the inkjet printer 10 may include an inkjet head that ejects ink of a color other than white as the multi-layer formation head. For example, the multi-layer printing head may eject ink droplets such as clear ink. Further, the multi-layer printing head may eject ink droplets such as opaque ink that cannot be used at the same time as color printing ink, such as opaque black ink or special color ink such as metallic color.

  Furthermore, the inkjet printer 10 may include a plurality of types of multi-layer forming heads. Further, as the multi-layer forming head, a part or all of the plurality of color printing heads 14 may also be used. In this case, the multilayer print layer may also be a color printed layer.

  The ultraviolet irradiation unit 18 is a light source unit that irradiates the medium 50 with ultraviolet rays for curing the ink. For example, the ultraviolet irradiation unit 18 is provided at a position on the rear side of the movement of the color printing head 14 and the white layer forming head 16 in the main scanning direction during the main scanning operation. As the ultraviolet irradiation unit 18, for example, a metal halide lamp, a high-pressure mercury lamp, a xenon lamp, a black light, a mercury lamp, or a UVLED can be used.

  In this example, the ink jet printer 10 includes a plurality of ultraviolet irradiation units 18. The plurality of ultraviolet irradiation units 18 are provided at positions sandwiching the color printing head 14 and the white layer forming head 16 from both sides in the main scanning direction. Further, during the main scanning operation, the main scanning control unit 102 moves the plurality of ultraviolet irradiation units 18 together with the color printing head 14 and the white layer forming head 16 in the main scanning direction. Thereby, the main scanning control unit 102 irradiates the ink ejected from the color printing head 14 and the white layer forming head 16 and landed on the medium 50 in both the forward and backward movements in the main scanning direction. The unit 18 is irradiated with ultraviolet rays.

  Here, the selection of the nozzle by the nozzle selection unit 106 will be described in more detail. The following description is an example of nozzle selection in the case where one color print layer and one white ink layer are formed to overlap each other.

  In this example, each of the plurality of color printing heads 14 and the white layer forming heads 16 has a nozzle row 302 having an effective length L. The nozzle selection unit 106 sets a color nozzle selection area 202 and a gap area 206 in a part of the nozzle row 302 of the color printing head 14. The color nozzle selection area 202 is an area in which nozzles to be selected as nozzles used for color printing are arranged, and includes a plurality of nozzles 304 that are continuously arranged in the nozzle row direction. In this example, the color nozzle selection area 202 is an area having a nozzle selection width in which the length in the nozzle row direction is set in advance as indicated by an arrow L1 in the drawing.

  The gap area 206 is an area that serves as a space for preventing the ink of the layer to be printed later from being mixed with the ink of the previously printed layer when performing multi-layer printing by the method of this example. In this example, the gap region 206 is a gap region set adjacent to the color nozzle selection region 202 in the nozzle row 302, as indicated by an arrow B1 in the drawing, and includes one or more nozzles 304. including.

  The nozzle selection unit 106 sets the color nozzle selection region 202 and the gap region 206 having the same width by aligning the positions in the sub-scanning direction for each of the plurality of color printing heads 14. As a result, the nozzle selection unit 106 sets the nozzles 304 in the color nozzle selection area 202 in each color printing head 14 as the nozzles 304 that should eject ink droplets during the main scanning operation in each color printing head 14. select.

  Further, the nozzle selection unit 106 applies the white layer nozzle selection region 204 to a portion of the nozzle row 302 of the white layer forming head 16 where the position in the sub-scanning direction does not overlap the color nozzle selection region 202 and the gap region 206. Set. The white layer nozzle selection area 204 is an area where the nozzles 304 to be selected as the nozzles 304 used for printing with white ink are arranged, and includes a plurality of nozzles 304 arranged continuously in the nozzle row direction. In this example, the white layer nozzle selection area 204 is an area having the same nozzle selection width as the color nozzle selection area 202 in the nozzle row direction, as indicated by an arrow L2 in the drawing. The white layer nozzle selection area 204 is an example of a multi-layer nozzle selection area. Accordingly, the nozzle selection unit 106 selects the nozzle 304 in the white layer nozzle selection area 204 as the nozzle 304 that should eject ink droplets during the main scanning operation in the white layer forming head 16. In this example, the nozzle selection unit 106 also includes the color printing head 14 in a portion of the nozzle row 302 of the white layer forming head 16 where the gap region 206 of the color printing head 14 and the position in the sub-scanning direction overlap. A gap area 206 having the same length as the gap area 206 is set.

  Here, as in this example, when a single color printing layer and a single white ink layer are formed to overlap, the nozzle selection unit 106 sequentially adjoins the positions in the sub-scanning direction, thereby selecting the color nozzle selection region. 202, a gap area 206, and a white layer nozzle selection area 204 are set. In the main scanning operation, the main scanning control unit 102 also includes a nozzle 304 in the color nozzle selection area 202 in each color printing head 14 and a nozzle in the white layer nozzle selection area 204 in the white layer forming head 16. While ejecting ink droplets from 304, the color printing head 14 and the white layer forming head 16 are moved in the main scanning direction. Thus, for each main scanning operation, the color printing head 14 forms a color printing layer with a nozzle selection width that is the width of the color nozzle selection region 202. In the same main scanning operation, the white layer forming head 16 is located at a position where the distance corresponding to the length of the gap region 206 is spaced in the sub scanning direction with respect to the color printing layer formed by the color printing head 14. The white ink layer is formed with a nozzle selection width that is the width of the white layer nozzle selection area 204.

  Further, between each main scanning operation, the sub scanning control unit 104 moves the color printing head 14 and the white layer forming head 16 relative to the medium 50 by the conveyance of the medium 50 in the sub scanning direction. Move to. Further, the sub-scanning control unit 104 sets the pass feed width per sub-scanning operation to a distance set corresponding to the nozzle selection width. Accordingly, the main scanning control unit 102 performs color printing on the color printing head 14 and the white layer forming head 16 to a position where the position in the sub-scanning direction is different from that in the previous main scanning operation in the next main scanning operation. And a white ink layer is formed.

  The distance set corresponding to the nozzle selection width is, for example, the medium 50 determined according to the nozzle selection width which is the width of the color print layer and white ink layer formed by one main scanning operation. Is the feed amount. The distance set corresponding to the nozzle selection width may be, for example, a distance obtained by dividing the nozzle selection width by the number of printing scans (number of passes) N.

  FIG. 2 is a diagram illustrating an example of a color print layer and a white ink layer formed in each main scanning operation. The position of the area (pass) printed in each main scanning operation on the medium 50 is printed. According to the process, it is shown in time series. In the figure, reference signs T1 to T9 indicate timings arranged in time series in the printing process.

  Here, the example described below is an example in the case of performing two-scan printing (two-pass printing) in which the number of scans (pass number) of printing for each position of the medium 50 is two. In this case, the sub-scanning control unit 104 sets the pass feed width to a distance that is ½ of the nozzle selection width. Accordingly, the ink jet printer 10 forms each of the color printing layer and the white ink layer by performing the main scanning operation twice for each portion on the medium 50.

  More specifically, for example, in the main scanning operation, for each color print layer, the first scan of the color print layer is divided into areas L11 and L12 obtained by dividing the color nozzle selection area 202 of the color print head 14 into two as shown in the figure. And the second scan is printed. In addition, the first and second scans are printed on the white ink layer 404 by the areas L21 and L22 obtained by dividing the white layer nozzle selection area 204 of the white layer forming head 16 into two. In the sub-scanning operation, a sub-scanning operation is performed with a pass feed width corresponding to the length of the regions L11, L12, L21, and L22.

  In this example, the nozzle selection unit 106 sets the length of the gap region 206 in the nozzle row direction to a distance that is ½ of the nozzle selection width. As a result, the nozzle selection unit 106 sets the length of the gap region 206 equal to the movement distance of the color printing head 14 and the white layer forming head 16 during the sub-scanning operation in the sub-scanning direction.

  In the drawing, for convenience of illustration, a plurality of color printing heads 14 and white layer forming heads 16 are collectively shown as one ink jet head. Of the inkjet heads in the figure, the color nozzle selection area 202 indicates the color nozzle selection area 202 in each color printing head 14. The white layer nozzle selection area 204 indicates the white layer nozzle selection area 204 in the white layer forming head 16. A gap area 206 indicates the gap area 206 in each of the color printing head 14 and the white layer forming head 16.

  In this example, the nozzle selection unit 106 selects the white layer nozzle on the side far from the color nozzle selection area 202 in addition to the same gap area 206 as the gap area 206 indicated by the arrow B1 in FIG. A gap region 206 indicated by an arrow B2 is further set at a position adjacent to the region 204. With this configuration, for example, the gap region 206 corresponding to each of the color nozzle selection region 202 and the white layer nozzle selection region 204 is provided, and it becomes easier to control the sub-scanning operation.

  Hereinafter, the state for each timing T1 to T9 will be described. Timing T1 indicates a state in which the medium 50 is in the initial position before printing is started. In this state, the nozzle rows of the color printing head 14 and the white layer forming head 16 are, for example, outside the printing area of the medium 50. Subsequent timings T2 to T8 are timings in a state where one sub-scanning state is performed after the previous timing. Timing T9 is a timing when all printing is completed.

  In the main scanning operation performed at the following timings, the ultraviolet irradiation unit 18 (see FIG. 1) moves in the main scanning direction together with the color printing head 14 and the white layer forming head 16 while irradiating ultraviolet rays. For example, the main scanning control unit 102 causes the ultraviolet irradiation unit 18 on the back side of the movement of the color printing head 14 and the white layer forming head 16 in the main scanning direction to perform ultraviolet irradiation. Thereby, the ultraviolet irradiation unit 18 cures the color print layer and the white ink layer formed by each main scanning operation before the next main scanning operation is performed.

  At timing T <b> 2, the color printing head 14 and the white layer forming head 16 are positioned so that the area L <b> 11 for performing the first scan printing on the color printing head 14 overlaps the leading main scanning area 502 a on the medium 50. . By performing the main scanning operation in this state, the color printing head 14 forms the first color printing layer 402a in the main scanning region 502a of the medium 50 with the width of the region L11.

  At timing T3, the color printing head 14 and the white layer forming head 16 are in positions where the area L11 of the color printing head 14 overlaps the next main scanning area 502b. In this state, the area L12 for printing the second scan in the color printing head 14 overlaps the main scanning area 502a. By performing the main scanning operation in this state, the color printing head 14 forms the color printing layer 402a for the first scan in the main scanning region 502b. In addition, the color print layer 402b for the second scan is formed in the main scan region 502a with the same width L12 as the width of the region L11.

  At timing T4, the color printing head 14 and the white layer forming head 16 are in positions where the area L11 of the color printing head 14 overlaps the next main scanning area 502c. In this state, the area L12 of the color printing head 14 overlaps the main scanning area 502b. By performing the main scanning operation in this state, the color printing head 14 forms the color printing layer 402a for the first scan in the main scanning region 502c. In addition, a color print layer 402b for the second scan is formed in the main scan region 502b.

  Further, at this timing T4, the main scanning area 502a overlaps the gap area 206 between the color printing head 14 and the white layer forming head 16. Therefore, at timing T4, neither the color printing head 14 nor the white layer forming head 16 performs printing on the main scanning region 502a.

  At timing T5, the color printing head 14 and the white layer forming head 16 are in positions where the area L11 of the color printing head 14 overlaps the next main scanning area 502d. In this state, the area L12 of the color printing head 14 overlaps the main scanning area 502c. Further, the region L21 for printing the first scan in the white layer forming head 16 overlaps the main scanning region 502a.

  By performing the main scanning operation in this state, the color printing head 14 forms the color print layer 402a for the first scan in the main scan region 502d and the color print layer 402b for the second scan in the main scan region 502c. Form. The white layer forming head 16 forms the white ink layer 404a for the first scan in the main scanning region 502a with the same width L21 as the width of the region L11.

  At timing T6, the color printing head 14 and the white layer forming head 16 are in positions where the area L11 of the color printing head 14 overlaps the next main scanning area 502e. In this state, the area L12 of the color printing head 14 overlaps the main scanning area 502d. Further, the region L21 of the white layer forming head 16 overlaps the main scanning region 502b. In addition, the region L22 for printing the second scan in the white layer forming head 16 overlaps the main scanning region 502a.

  By performing the main scanning operation in this state, the color printing head 14 forms the color print layer 402a for the first scan in the main scan area 502e and the color print layer 402b for the second scan in the main scan area 502d. Form. The white layer forming head 16 forms the white ink layer 404a for the first scan in the main scanning region 502b. Further, the white layer forming head 16 forms the white ink layer 404b of the second scan in the main scanning region 502a with the same width L22 as the width of the region L11.

  Thereafter, by repeating the same operation at timings T7 and T8, the color printing head 14 moves to the area where printing is not performed on the medium 50 in the color nozzle selection area 202 in each main scanning operation. Color printing layers 402a and 402b, which are the first layers of multilayer printing, are formed with YMCK ink using only the nozzles. Further, the white layer forming head 16 performs multilayer printing with white ink using only the nozzles of the white layer nozzle selection area 204 on the color print layers 402a and 402b formed by the previous main scanning operation. The white ink layers 404a and 404b are formed as the second layer. As a result, the inkjet printer 10 uses the color printing head 14 and the white layer forming head 16 to form the color printing layers 402a and 402b and the white ink layer serving as the backing layer on the medium 50 as in the state of timing T9. Two-layer printing in which 404a and 404b are overlapped is performed.

  According to this example, for example, multilayer printing can be appropriately performed without performing a step of returning the position of the medium 50 in the sub-scanning direction (rewinding of the medium 50). This also eliminates the need to provide various configurations that are necessary when performing such a process, for example. Therefore, according to this example, for example, multilayer printing can be performed at low cost.

  In the inkjet printer 10 of this example, for example, when multi-layer printing is not performed and normal one-layer color printing is to be performed, color printing is performed without setting the gap region 206 and the white layer nozzle selection region 204. Printing can also be performed using the entire nozzle row (total nozzle width) in the printing head 14. Therefore, according to this example, when multi-layer printing is not performed, high-speed printing similar to that of a normal inkjet printer can be appropriately performed.

  Even in the case of performing multi-layer printing, the area to be printed in one main scanning operation for each of the color printing layer and the white ink layer is smaller than the entire nozzle width, but the medium 50 needs to be rewound. Therefore, for example, printing can be performed at a speed equal to or higher than that in the case where the medium 50 is rewound and multilayer printing is performed in a time division manner. Therefore, according to this example, for example, multi-layer printing can be performed at low cost and at an appropriate speed.

  Furthermore, in this example, by setting a gap area 206 between the color nozzle selection area 202 and the white layer nozzle selection area 204 in the sub-scanning direction, the color print layer and the white ink layer are set to each other. Ink color mixing can be prevented appropriately. Therefore, according to this example, multilayer printing can be performed more appropriately.

  In this example, the length of the gap region 206 in the sub-scanning direction is equal to the pass feed width in the sub-scanning operation. In this case, for example, the correspondence between each position of the medium 50 and the main scanning operation can be easily considered for each of the color print layer and the multilayer print layer. Thereby, for example, the operation of the inkjet printer 10 can be controlled more easily.

  The inkjet printer 10 may more generally set the number of scans (number of passes) for each position of the medium 50 to N times (N is an integer of 2 or more). In this case, for example, the sub-scanning control unit 104 sets the pass feed width in the sub-scanning operation to a distance 1 / N of the nozzle selection width. The ink jet printer 10 forms the printing on each position on the medium 50 for each of the color print layer and the white ink layer by N main scanning operations that are performed with a sub-scanning operation interposed between each time. The nozzle selection unit 106 sets the length of the gap region 206 in the nozzle row direction to a distance 1 / N of the nozzle selection width. With this configuration, for example, the number of scans can be further increased, and for example, 4-scan printing (4-pass printing), 8-scan printing (8-pass printing), and the like can be appropriately performed in the same manner.

  Here, the length of the gap region 206 in the nozzle row direction may be smaller than the pass feed width in the sub-scanning operation, for example. With this configuration, for example, the influence on the printing speed due to the provision of the gap region 206 can be reduced. This also makes it possible to perform printing at a higher speed, for example.

  In this case, for example, the inkjet printer 10 sets an image to be printed in each main scanning operation, for example, by adjusting according to the difference between the pass feed amount and the gap area 206. The length of the gap region 206 in the sub-scanning direction is preferably an integral multiple of the dot pitch, and may be 1 mm or less, for example. The gap area 206 may be an area including 1 to 3 nozzles arranged in the nozzle row direction, for example. Further, the length of the gap region 206 in the nozzle row direction may be, for example, the minimum width allowed for mechanical accuracy in controlling the inkjet head.

  In addition, the length of the gap region 206 in the nozzle row direction is preferably larger than, for example, the maximum variation in the sub-scanning direction of the ink droplet landing position. The maximum variation in the ink droplet landing position in the sub-scanning direction is, for example, the accuracy of the landing position of the ink droplets ejected from the inkjet heads such as the color printing head 14 and the white layer forming head 16. This is the maximum allowable variation in design for the nozzle.

  Further, as described above, in the modified example of the present invention, instead of the white layer forming head 16, for example, an ink jet head for ink other than white ink may be used as the multi-layer forming head. As such an ink, for example, a clear ink or an ink that is opaque and cannot be used at the same time as a color printing ink (an opaque black ink or a special color ink such as a metallic color) can be appropriately used.

  Next, a case where multilayer printing including more layers is performed by the inkjet printer 10 of this example will be described. FIG. 3 is a diagram illustrating an example of a case where three layers of multi-layer printing are performed, and illustrates an example of a state in which a white ink layer is formed between two color print layers in time series.

  In this example, the nozzle selection unit 106 sets a plurality of color nozzle selection regions 202 as indicated by arrows L1 and L3 in the drawing for the color printing head 14. Further, in this case, the nozzle selection unit 106 provides a distance of two gap regions 206 and one white layer nozzle selection region 204 between the two color nozzle selection regions 202. A plurality of gap areas 206 as indicated by arrows B 1 and B 2 are set between the two color nozzle selection areas 202 so that the gap areas 206 are adjacent to the color nozzle selection areas 202. To do. Further, the nozzle selection unit 106 sets a white layer nozzle selection region 204 as indicated by an arrow L <b> 2 between the two gap regions 206.

  In the figure, timing T1 indicates a state in which the medium 50 is in the initial position before printing is started. Timings T2 to T10 are timings in a state where one sub-scanning state is performed after the previous timing. Timing T11 is timing when all printing is completed.

  Except as described below, the configuration and operation of the inkjet printer 10 in FIG. 3 are the same as or similar to those in FIG. For example, also in this example, the length of the gap region 206 is set to be equal to the pass feed width, for example. Further, the color printing head 14 and the white layer forming head 16 have previously overlapped with the medium 50 until the timing T7 which is a state before the color nozzle selection area 202 indicated by the arrow L3 overlaps with the medium 50. In the same manner as shown in FIG. 2, color printing is performed on the main scanning regions 502 a to 502 f of the medium 50 according to the operation at each timing by the nozzle selection region 202 for white and the nozzle selection region 204 for white layer. Layers 402a and 402b and white ink layers 404a and 404b are formed.

  Further, at timing T8, the color printing head 14 and the white layer forming head 16 are in positions where the area L11 of the color printing head 14 overlaps the next main scanning area 502g. In this state, the area L12 of the color printing head 14 overlaps the main scanning area 502f. A region L21 of the white layer forming head 16 overlaps the main scanning region 502d. Further, the region L22 of the white layer forming head 16 overlaps the main scanning region 502c. Further, a region L31 for printing the first scan on the white ink layers 404a and 404b in the color printing head 14 overlaps with the main scanning region 502a.

  By performing the main scanning operation in this state, the color printing head 14 forms the color print layer 402a for the first scan in the main scan region 502g and the color print layer 402b for the second scan in the main scan region 502f. Form. The white layer forming head 16 forms the white ink layer 404a for the first scan in the main scanning region 502d, and forms the white ink layer 404b for the second scan in the main scanning region 502c. Further, the color printing head 14 applies the color printing layer 406a for the first scan on the previously formed white ink layers 404a and 404b with the same width L31 as the width of the region L11 in the main scanning region 502a. Form.

  Further, at timing T9, the color printing head 14 and the white layer forming head 16 are in positions where the area L11 of the color printing head 14 overlaps the next main scanning area 502h. In this state, the area L12 of the color printing head 14 overlaps the main scanning area 502g. The region L21 of the white layer forming head 16 overlaps the main scanning region 502e. A region L22 of the white layer forming head 16 overlaps the main scanning region 502d. Further, the area L31 of the color printing head 14 overlaps the main scanning area 502b. In the white layer forming head 16, a region L32 for printing the second scan on the white ink layers 404a and 404b overlaps with the main scanning region 502a.

  By performing the main scanning operation in this state, the color printing head 14 forms the color print layer 402a for the first scan in the main scan area 502h, and the color print layer 402b for the second scan in the main scan area 502g. Form. Further, the white layer forming head 16 forms a white ink layer 404a for the first scan in the main scanning region 502e, and forms a white ink layer 404b for the second scan in the main scanning region 502d. Further, the color printing head 14 forms a color printing layer 406a for the first scan on the white ink layers 404a and 404b in the main scanning region 502b. In the main scanning region 502a, the color print layer 406b for the second scan is formed on the white ink layers 404a and 404b with the same width L32 as the width of the region L11.

  Then, the same operation is repeated after the timing T10, and multilayer printing is performed in which the white ink layer is sandwiched between the two color printing layers as in the state of the timing T11. Also in this example, for example, multilayer printing can be appropriately performed without performing the step of returning the position of the medium 50 in the sub-scanning direction. Also, for example, by setting the gap region 206 between the color nozzle selection region 202 and the white layer nozzle selection region 204, ink color mixing occurs between the color print layer and the white ink layer. Can be prevented appropriately.

  Also in this example, the length of the gap region 206 may be set smaller than, for example, the pass feed width. If constituted in this way, printing speed can be raised, for example. In a further modification of the present invention, the nozzle selection unit 106 may set three or more color nozzle selection regions 202 in the color printing head 14. In this case, the nozzle selection unit 106, for example, between the adjacent color nozzle selection regions 202, the length of the two gap regions 206 in the nozzle row direction and the length of the white layer nozzle selection region 204 in the nozzle row direction. Set at least a width greater than the sum of In addition, a plurality of gap areas 206 provided adjacent to the side where the other color nozzle selection area 202 is set are set for each color nozzle selection area 202. Then, the white layer nozzle selection region 204 is set in a portion of the nozzle row of the white layer forming head 16 where the region sandwiched between the plurality of gap regions 206 overlaps the position in the sub-scanning direction.

  The inkjet printer 10 may include an inkjet head for ink other than white, instead of the white layer forming head 16, as the multi-layer forming head. The ink jet printer 10 may include a plurality of types of multi-layer forming heads. In this case, for example, the nozzle selection unit 106 shifts the position in the sub-scanning direction of the multi-layer nozzle selection area similar to the white-layer nozzle selection area 204 described above with respect to one or a plurality of multi-layer formation heads. You may set more than one. In this case, the multi-layer print layers formed corresponding to the respective multi-layer nozzle selection areas are overprinted according to the positions in the sub-scanning direction where the respective multi-layer nozzle selection areas are set.

  Also in these cases, for example, in multilayer printing of N layers, the width K corresponding to the gap region 206 is considered with respect to the total nozzle width A of the color printing head 14 and the multilayer forming head, and each layer is (A / N−K). ), It is possible to appropriately perform multi-layer printing. Further, when only normal one-layer color printing is performed, high-speed printing can be appropriately performed by performing printing using the entire nozzle width, for example.

  FIG. 4 is a diagram illustrating an example of multilayer printing including more layers. FIG. 4A is a diagram illustrating an example of how to select a nozzle. In this example, the ink jet printer 10 further includes a light shielding layer head, which is an ink jet head that ejects ink droplets for light shielding layer formation, in addition to the color printing head 14 and the white layer forming head 16. The light shielding layer head is an example of a multilayer forming head. Except for the points described below, the ink jet printer 10 of this example is the same as or similar to the ink jet printer 10 described with reference to FIG.

  As the ink for forming the light shielding layer used in the head for the light shielding layer, for example, a metallic ink having a high light absorption coefficient or reflectance, an opaque black ink, or the like can be used. The ink for forming the light shielding layer may be a light shielding ink using nano-sized metal powder that does not transmit light as a pigment. Further, for example, gray or blue ink may be used as the ink for forming the light shielding layer. In this example, the light shielding layer forming ink is, for example, an ultraviolet curable ink. For example, in the inkjet printer 10 having the same configuration as that shown in FIG. 1A, the light shielding layer head includes a plurality of color printing heads 14 and white layer forming heads 16 aligned in the sub-scanning direction. Provided between the ultraviolet irradiation units 18.

  Further, in this example, the nozzle selection unit 106 applies each of the nozzle rows of the color printing head 14, the white layer forming head 16, and the light shielding layer head, as shown in FIG. The color nozzle selection area 202, the white layer nozzle selection area 204, the light shielding layer nozzle selection area 208, the white layer nozzle selection area 204, and the color nozzle selection area 202 with the gap area 206 interposed therebetween. Set in order.

  The nozzle selection unit 106 sets each of these areas with respect to the nozzle row of the inkjet head that ejects ink droplets corresponding to the areas, as described in FIGS. 2 and 3. For example, the nozzle selection unit 106 sets the light shielding layer nozzle selection region 208 for the nozzle row of the light shielding layer head. In addition, the nozzle selection unit 106 sets the length of the gap region 206 equal to the pass feed width. The nozzle selection unit 106 may set the length of the gap region 206 to be smaller than the pass feed width. Then, the inkjet printer 10 forms a layer corresponding to each set region on the medium 50 by the same operation as described in FIGS.

  FIG. 4B shows an example of the layer configuration in the printing result. In this example, the inkjet printer 10 performs printing on a translucent medium 50 in which an image printed on a printing surface can be viewed from the back side. The translucent medium 50 is, for example, a transparent medium 50. Further, the color nozzle selection area 202, the white layer nozzle selection area 204, the light shielding layer nozzle selection area 208, and the white layer nozzle selection area set as shown in FIG. 204, and the color nozzle selection area 202, each layer is formed to form a first color print layer 602, a first light reflection layer 604, a light shielding layer 606, a second light reflection layer 608, and a second color print. Layers 610 are overlaid.

  When configured in this way, the image printed on the first color print layer 602 is an image observed from the back side of the medium 50 through the medium 50. Further, the image printed on the second color print layer 610 is an image observed from the surface side of the medium 50. Therefore, according to this example, for example, by performing printing on only one surface of the medium 50, it is possible to perform pseudo duplex printing.

  The light shielding layer 606 is provided, for example, so as to make an image printed on the first color print layer 602 invisible from the front side for observation from the back side. Therefore, as long as the function can be exhibited, the color and thickness are not limited. The light transmittance in the light shielding layer 606 is preferably less than 25%.

  The first light reflection layer 604 is a layer that reflects light when the image in the first color print layer 602 is observed from the back side of the medium 50. The first light reflecting layer 604 further functions to reduce the influence on the color due to light absorption by the light shielding layer 606 formed thereon. The second light reflection layer 608 is a layer that reflects light when an image in the second color print layer 610 formed thereon is observed from the surface side of the medium 50. Further, the second light reflecting layer 608 further functions to reduce the influence of light absorption by the light shielding layer 606 on the color.

  The first light reflection layer 604 and the second light reflection layer 608 are preferably formed with a thickness of at least a reflectance exceeding 50%. In addition, the first light reflection layer 604 and the second light reflection layer 608 can be formed with light inks of other colors instead of the white ink. In this case, the ink jet printer 10 includes an ink jet head for light-color ink as a multi-layer forming head that replaces the white layer forming head 16.

  5 and 6 show specific examples of each layer shown in FIG. FIG. 5A shows an example of the first color print layer 602. FIG. 5B shows an example of the first light reflecting layer 604. FIG. 5C shows an example of the light shielding layer 606. FIG. 6A shows an example of the second light reflecting layer 608. FIG. 6B shows an example of the second color print layer 610.

  5 and 6 show a state in which each layer is exposed for convenience of explanation. In the actual printing operation, as described with reference to FIG. 4, for example, the inkjet printer 10 prints each layer in an overlapping manner in each main scanning operation. Further, by using the ultraviolet curable ink and performing the main scanning operation while irradiating the ultraviolet rays from the ultraviolet irradiation unit 18, each layer to be formed is cured and fixed to the medium 50 in each main scanning operation. .

  In this example, the inkjet printer 10 forms the first color printing layer 602 on one side of the transparent medium 50 by the color printing head 14. Further, in the first color print layer 602, a mirror image that is a mirror image of an image that should be viewed by an observer is printed as a print image. Accordingly, the inkjet printer 10 prints an image that becomes a normal image when observed from the back side of the medium 50 on the first color print layer 602.

  In addition, the inkjet printer 10 forms the first light reflection layer 604 at a position covering the mirror image on the first color print layer 602 by the white layer forming head 16. In this example, the inkjet printer 10 forms the first light reflection layer 604 in an area including at least an area where an image is printed in the first color printing layer 602 and the second color printing layer 610, for example. In the inkjet printer 10, for example, the first light reflection layer 604 may be formed on the entire surface of the medium 50.

  Moreover, the inkjet printer 10 forms the light shielding layer 606 on the 1st light reflection layer 604 with the head for light shielding layers. In this example, the inkjet printer 10 forms the light shielding layer 606 at least in a region including both regions where images are printed in the first color printing layer 602 and the second color printing layer 610. In the inkjet printer 10, for example, the light shielding layer 606 may be formed on the entire surface of the medium 50.

  Further, the inkjet printer 10 forms the second light reflection layer 608 on the light shielding layer 606 by the white layer forming head 16. In this example, the inkjet printer 10 forms the second light reflection layer 608 at least in a region including both regions where an image is printed in the first color print layer 602 and the second color print layer 610. In the inkjet printer 10, for example, the second light reflection layer 608 may be formed on the entire surface of the medium 50.

  Further, the inkjet printer 10 forms the second color printing layer 610 on the second light reflecting layer 608 by the color printing head 14. Further, in the second color print layer 610, a normal image showing the image that should be visually recognized by the observer is printed as the print image.

  When printing is performed as described above, by performing printing only from one side (front surface) of the medium 50, images observed from both the front side and the back side of the medium 50 can be appropriately printed. In addition, when the image printed on the first color printing layer 602 is a mirror image, a normal image can always be observed when viewed from either the front side or the back side of the medium 50. Therefore, according to this example, for example, by performing printing only on one side of the medium 50, it is possible to obtain a printing result similar to double-sided printing. Thereby, for example, a pseudo double-sided printing function can be provided to the inkjet printer 10. In addition, the inkjet printer 10 can create a very effective display object.

  Furthermore, in this example, it is possible to appropriately print a plurality of layers without performing a step of returning the position of the medium 50 in the sub-scanning direction. Therefore, according to this example, for example, pseudo double-sided printing can be appropriately performed at low cost.

  The formation of each of the above layers can also be performed as follows, for example. For example, the first light reflection layer 604, the light shielding layer 606, and the second light reflection layer 608 are formed so as to overlap all of the portions where the image is printed in the first color print layer 602 and the second color print layer 610. Instead, it is also conceivable to extract a necessary part in advance and form all or a part of these intermediate layers only in a region including the part. In this case, as a portion that needs to form an intermediate layer, for example, a portion of a region such as a region including characters or the like that becomes difficult to recognize properly when mirror image inversion is considered.

  In this case, as the image in the first color print layer 602, for example, an image obtained by mirror-inverting only a part of the image printed in the second color print layer 610 may be printed. In this case, for example, mirror image reversal is performed for a region that is difficult to recognize properly when mirror image reversal is performed, and it is necessary to distinguish and print a mirror image and a normal image. For the other regions, the same normal image as the second color print layer 610 is printed even in the image in the first color print layer 602. In this case, in the first color print layer 602, the same image is overlapped with the second color print layer 610 in the portion where the normal image is printed. For this reason, for example, it may be considered that the light shielding layer 606 is eliminated and only the first light reflecting layer 604 or the second light reflecting layer 608 is formed.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above embodiment. It is apparent from the description of the scope of claims that embodiments with such changes or improvements can be included in the technical scope of the present invention.

  The present invention can be suitably used for an inkjet printer, for example.

DESCRIPTION OF SYMBOLS 10 ... Inkjet printer, 12 ... Scan control part, 14 ... Color printing head, 16 ... White layer formation head, 18 ... Ultraviolet irradiation part, 102 ... Main scanning control part 104 ... Sub-scanning control unit, 106 ... Nozzle selection unit, 202 ... Color nozzle selection region, 204 ... White layer nozzle selection region, 206 ... Gap region, 208 ... Nozzle selection area for light shielding layer, 302... Nozzle row, 304... Nozzle, 402 a, 402 b... Color printing layer, 404 a and 404 b... White ink layer, 406 a and 406 b. 502a to 502i ... main scanning region, 602 ... first color printing layer, 604 ... first light reflecting layer, 606 ... light shielding layer, 608 ... second light reflecting layer, 610.・ Second color mark Layer

Claims (8)

A main scanning operation for moving the inkjet head relative to the medium in a preset main scanning direction, and a movement of the inkjet head relative to the medium in a sub-scanning direction orthogonal to the main scanning direction. An inkjet printer that performs sub-scanning operation and performs printing on each position of the medium,
An inkjet head that ejects ink droplets that form a color print layer on which color printing has been performed. The inkjet head has a nozzle row in which a plurality of nozzles are arranged in a nozzle row direction parallel to the sub-scanning direction, and the main scanning operation is performed. In this case, by discharging ink droplets from the plurality of nozzles while moving in the main scanning direction, color printing for forming a portion corresponding to the main scanning operation in the color printing layer for each main scanning operation For head,
An inkjet head that ejects ink droplets that form a multi-layer print layer that is a layer of ink printed on or under the color print layer, and has a nozzle row in which a plurality of nozzles are arranged in the nozzle row direction. The color printing head is aligned with the position in the sub-scanning direction and the position in the main scanning direction is shifted, and when the main scanning operation is performed, the plurality of the color printing heads are moved while moving in the main scanning direction. A multi-layer forming head for forming a portion corresponding to the main scanning operation in the multi-layer printing layer for each main scanning operation by ejecting ink droplets from each nozzle;
A scanning control unit for controlling the main scanning operation and the sub-scanning operation of the color printing head and the multi-layer formation head;
The scanning control unit
A nozzle selection unit that selects the nozzles that should eject ink droplets in the main scanning operation from each of the color printing head and the multilayer formation head;
A main scanning control unit for causing the color printing head and the multilayer forming head to perform the main scanning operation;
A sub-scanning control unit for causing the color printing head and the multilayer forming head to perform the sub-scanning operation;
The nozzle selector
A color including a plurality of the nozzles that are regions of a nozzle selection width in which the length in the nozzle row direction is set in advance in a part of the nozzle row of the color printing head and are continuously arranged in the nozzle row direction A color nozzle selection area and a gap area that is set adjacent to the color nozzle selection area in the nozzle row and includes one or more nozzles. The nozzle in the color printing head is selected as the nozzle to eject ink droplets during the main scanning operation in the color printing head,
And,
The length in the nozzle row direction is the same as that of the color printing head in a portion where the position in the sub-scanning direction of the nozzle row of the multi-layer formation head does not overlap the color nozzle selection region and the gap region. A multi-layer nozzle selection region that is a region of the nozzle selection width and includes a plurality of the nozzles continuously arranged in the nozzle row direction is set, and the nozzle in the multi-layer nozzle selection region is set as the multi-layer formation head. In the main scanning operation, select the nozzle that should eject ink droplets,
In the main scanning operation, the main scanning control unit is configured to drop ink droplets from the nozzles in the color nozzle selection area in the color printing head and from the nozzles in the multilayer nozzle selection area in the multilayer formation head. Moving the color printing head and the multilayer forming head in the main scanning direction relative to the medium,
In the sub-scanning operation, the sub-scanning control unit moves the color printing head relative to the medium by a distance set corresponding to the nozzle selection width per sub-scanning operation. And an ink jet printer, wherein the multi-layer forming head is moved in the sub-scanning direction. The color printing head and the multi-layer forming head each eject ink droplets of ultraviolet curable ink which is ink that is cured by irradiation of ultraviolet rays,
The inkjet printer is an ultraviolet irradiation unit that irradiates ultraviolet rays toward the medium, and is located behind the movement of the color printing head and the multilayer forming head in the main scanning direction during the main scanning operation. Further provided with an ultraviolet irradiation unit provided in
In the main scanning operation, the main scanning control unit irradiates the ultraviolet irradiation unit with ultraviolet rays to the ink ejected from the color printing head and the multilayer forming head and landed on the medium, and performs the color printing. 2. The ink jet printer according to claim 1, wherein the head for forming and the multi-layer forming head and the ultraviolet irradiation section are moved in the main scanning direction relative to the medium.   The length of the gap region in the nozzle row direction is larger than the maximum variation in the sub-scanning direction of the landing positions of the ink droplets ejected from the color printing head and the multilayer forming head. An ink jet printer according to claim 1 or 2. The sub-scanning controller is configured to perform the color printing relative to the medium by a distance of 1 / N (N is an integer of 2 or more) of the nozzle selection width per sub-scanning operation. Moving the head and the multi-layer forming head in the sub-scanning direction;
The ink jet printer is formed by performing N times of the main scanning operations in which each of the color printing layer and the multilayer printing layer is printed at each position on the medium with the sub scanning operation being sandwiched between each time. And
The length of the gap region in the nozzle row direction is equal to a distance for moving the color printing head and the multilayer forming head in the sub-scanning direction in the single sub-scanning operation. The inkjet printer according to any one of 1 to 3.   The length of the gap region in the nozzle row direction is smaller than a distance for moving the color printing head and the multilayer forming head in the sub-scanning direction in one sub-scanning operation. Item 4. The inkjet printer according to any one of Items 1 to 3. The nozzle selector
A plurality of the color nozzle selection regions, between the adjacent color nozzle selection regions, the length of two gap regions in the nozzle row direction, and the length of the multi-layer nozzle selection region in the nozzle row direction And a plurality of the gaps respectively provided adjacent to the side where the other color nozzle selection area is set with respect to each of the color nozzle selection areas. Set the area
And,
The multi-layer nozzle selection region is set in a portion of the nozzle row of the multi-layer formation head where a region between the plurality of gap regions and a position in the sub-scanning direction overlap in the color printing head. The inkjet printer according to claim 1, wherein the inkjet printer is a printer. The nozzle selector
7. The plurality of multi-layer nozzle selection areas on which the multi-layer print layers formed corresponding to the multi-layer nozzle selection areas are printed in an overlapping manner are set. The inkjet printer as described. A main scanning operation for moving the inkjet head relative to the medium in a preset main scanning direction, and a movement of the inkjet head relative to the medium in a sub-scanning direction orthogonal to the main scanning direction. A printing method that performs sub-scanning operation and performs printing on each position of the medium by an inkjet method,
An inkjet head that ejects ink droplets that form a color print layer on which color printing has been performed. The inkjet head has a nozzle row in which a plurality of nozzles are arranged in a nozzle row direction parallel to the sub-scanning direction, and the main scanning operation is performed. In this case, by discharging ink droplets from the plurality of nozzles while moving in the main scanning direction, color printing for forming a portion corresponding to the main scanning operation in the color printing layer for each main scanning operation For head,
An inkjet head that ejects ink droplets that form a multi-layer print layer that is a layer of ink printed on or under the color print layer, and has a nozzle row in which a plurality of nozzles are arranged in the nozzle row direction. The color printing head is aligned with the position in the sub-scanning direction and the position in the main scanning direction is shifted, and when the main scanning operation is performed, the plurality of the color printing heads are moved while moving in the main scanning direction. The color printing head and the multi-layer forming head for forming a portion corresponding to the main scanning operation in the multi-layer printing layer for each main scanning operation by ejecting ink droplets from each nozzle Performing scanning control for controlling the main scanning operation and the sub-scanning operation of the multi-layer formation head;
In the scanning control,
A nozzle selection step of selecting the nozzles that should eject ink droplets in the main scanning operation from each of the color printing head and the multilayer forming head;
A main scanning control step for causing the color printing head and the multi-layer forming head to perform the main scanning operation;
Performing a sub-scanning control step of causing the color printing head and the multi-layer forming head to perform the sub-scanning operation;
The nozzle selection step includes
A color including a plurality of the nozzles that are regions of a nozzle selection width in which the length in the nozzle row direction is set in advance in a part of the nozzle row of the color printing head and are continuously arranged in the nozzle row direction A color nozzle selection area and a gap area that is set adjacent to the color nozzle selection area in the nozzle row and includes one or more nozzles. The nozzle in the color printing head is selected as the nozzle to eject ink droplets during the main scanning operation in the color printing head,
And,
The length in the nozzle row direction is the same as that of the color printing head in a portion where the position in the sub-scanning direction of the nozzle row of the multi-layer formation head does not overlap the color nozzle selection region and the gap region. A multi-layer nozzle selection region that is a region of the nozzle selection width and includes a plurality of the nozzles continuously arranged in the nozzle row direction is set, and the nozzle in the multi-layer nozzle selection region is set as the multi-layer formation head. In the main scanning operation, select the nozzle that should eject ink droplets,
In the main scanning operation, in the main scanning operation, ink droplets from the nozzles in the color nozzle selection area in the color printing head and from the nozzles in the multilayer nozzle selection area in the multilayer formation head. Moving the color printing head and the multilayer forming head in the main scanning direction relative to the medium,
In the sub-scanning control step, in the sub-scanning operation, the color printing head is relative to the medium by a distance set corresponding to the nozzle selection width per sub-scanning operation. And a method of printing, wherein the multi-layer forming head is moved in the sub-scanning direction.