Printing method, and printer

Abstract

To suppress bleeding of a transfer image.SOLUTION: A printing method includes an image formation step of discharging color ink from a first inkjet head, and thereby forming an image onto a transfer medium, and a substrate formation step of discharging substrate ink to the transfer medium from a second inkjet head, and thereby superposing the substrate ink on the image, wherein when a region where an adhesive is supplied to the transfer medium at the same timing in an adhesive imparting step is set as a treatment unit region, the treatment unit region includes a first region, and a second region where the substrate ink is superposed on the image after the first region, and in the substrate formation step, a discharge amount of the substrate ink to the second region per unit area is made smaller than the discharge amount of the substrate ink to the first region per unit area.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a printing method for performing printing on a transfer medium and a printing apparatus.

Background Art

[0002] As disclosed in Patent Document 1, a printing method for fabric using a transfer sheet as a transfer medium is known. This printing method includes a step of printing first image data on a transfer sheet using black toner and color toner, a step of producing second image data by processing all colors in the printing range of the first image data into black, a step of printing the second image data on the transfer sheet on which the first image data has been printed using white toner instead of black toner, a step of applying an adhesive to the uppermost layer of the printed transfer sheet, a step of pressing the transfer sheet to which the adhesive has been applied against the fabric while heating, and a step of peeling the base material of the transfer sheet.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When forming an image to be transferred onto a fabric as a transfer medium using an inkjet printer, it is conceivable to attach a powdered hot melt adhesive to the image formed by the ink landing on the transfer sheet and transfer the image to the fabric. For example, an image of colored ink is formed on a transfer sheet, white ink is overlaid on the image, a powdered hot melt adhesive is attached to the white ink, and the heated hot melt adhesive is attached to the fabric, whereby the image on the transfer sheet can be transferred to the fabric. When the white ink lands on the image on the transfer sheet, it gradually dries. In the printed area on the transfer sheet, the later the white ink lands, the less the degree of drying of the white ink. For this reason, when the transfer sheet is tilted for applying a powdery hot melt adhesive or the like, the white ink with a low degree of drying may drip downward. When the white ink drips downward, bleeding occurs in the transferred image.

Means for Solving the Problem

[0005] The printing method of the present invention is a printing method for performing printing on the transfer medium, including an adhesive application step of attaching an adhesive to an undercoat ink overlaid on an image formed on the transfer medium, and a transfer step of transferring the image to the transfer medium by attaching the adhesive to the transfer medium, an image forming step of forming the image on the transfer medium by ejecting a colored ink from a first inkjet head, and an undercoat forming step of overlaying the undercoat ink on the image by ejecting the undercoat ink from a second inkjet head onto the transfer medium, taking, as a processing unit area, an area where the adhesive is supplied at the same timing in the adhesive application step with respect to the transfer medium, the processing unit area including a first area and a second area where the undercoat ink is overlaid on the image after the first area, In the undercoat forming step, the ejection amount of the undercoat ink per unit area for the second area is made less than the ejection amount of the undercoat ink per unit area for the first area.

[0006] Further, the printing apparatus of the present invention is a printing apparatus for performing printing on the transfer medium, including an adhesive application step of attaching an adhesive to an undercoat ink overlaid on an image formed on the transfer medium, and a transfer step of transferring the image to the transfer medium by attaching the adhesive to the transfer medium, a first inkjet head for ejecting a colored ink, A second inkjet head that discharges the undercoat ink; A drive unit that relatively moves the second inkjet head in a first direction with respect to the transfer medium; A control unit that controls the discharge of the colored ink from the first inkjet head, the discharge of the undercoat ink from the second inkjet head, and the drive unit, and includes: The control unit performs control to form the image on the transfer medium with the colored ink discharged from the first inkjet head and to overlay the undercoat ink discharged from the second inkjet head on the image; Taking, as a processing unit area, an area where the adhesive is supplied at the same timing in the adhesive application step with respect to the transfer medium, the processing unit area includes a first area and a second area where the undercoat ink is overlaid on the image after the first area; The control unit has an aspect in which the discharge amount of the undercoat ink per unit area for the second area is made less than the discharge amount of the undercoat ink per unit area for the first area.

Brief Description of the Drawings

[0007]

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[0008] Hereinafter, embodiments of the present invention will be described. Of course, the following embodiments are merely illustrative of the present invention, and not all of the features shown in the embodiments are necessarily essential to the solution means of the invention.

[0009] (1) Outline of Aspects Included in the Present Invention: First, the outline of the aspects included in the present invention will be described with reference to the examples shown in FIGS. 1 to 15. Note that the figures in the present application are diagrams schematically showing examples, and the scales of each part may be different from the actual ones in order to make each part recognizable, the magnification ratios in each direction shown in these figures may be different, and the figures may not be consistent. Of course, each element of this aspect is not limited to the specific examples indicated by reference numerals. In the "outline of the aspects included in the present invention", the content in parentheses means a supplementary explanation of the immediately preceding term. Also, in the present application, the numerical range "Min~Max" means not less than the minimum value Min and not more than the maximum value Max.

[0010] [Aspect 1] As illustrated in FIGS. 1, 5, etc., a printing method according to one aspect is a printing method for performing printing on the transfer medium M1, which includes an adhesive application step ST3 of attaching an adhesive 111 to an undercoat ink 36b overlapped on an image IM1 formed on the transfer medium M1, and a transfer step ST5 of transferring the image IM1 to the transfer medium M2 by attaching the adhesive 111 to the transfer medium M2. This printing method includes the following steps. (a1) An image forming step ST1 of forming the image IM1 on the transfer medium M1 by discharging a colored ink 36a from a first inkjet head (for example, the colored ink head 31). (a2) A base forming step ST2 of relatively moving a second inkjet head (for example, the undercoat ink head 32) in a first direction D1 with respect to the transfer medium M1, and overlapping the undercoat ink 36b on the image IM1 by discharging the undercoat ink 36b from the second inkjet head (32). Here, as illustrated in FIGS. 2, 6, etc., a region where the adhesive 111 is supplied at the same timing in the adhesive application step ST3 with respect to the transfer medium M1 is defined as a processing unit region A0. The processing unit region A0 includes a first region A1 and a second region A2 where the undercoat ink 36b is overlapped on the image IM1 after the first region A1. In this printing method, in the base forming step ST2, the discharge amount of the undercoat ink 36b per unit area for the second region A2 is made smaller than the discharge amount of the undercoat ink 36b per unit area for the first region A1.

[0011] In the above processing unit region A0, since the discharge amount of the undercoat ink for the second region A2 where the undercoat ink 36b is overlapped on the image IM1 after the first region A1 is small, the flow of the undercoat ink 36b due to the inclination of the transfer medium M1 in the adhesive application step ST3 is suppressed. By suppressing the flow of the undercoat ink 36b, bleeding of the transferred image (the image IM1 to be transferred) due to the undercoat ink 36b dripping downward or the like is suppressed. Therefore, the above aspect can provide a printing method capable of suppressing bleeding of the transferred image.

[0012] Various examples can be considered in the above-described aspect. For the second inkjet head (32) to move relative to the transfer medium M1 in the first direction D1, the second inkjet head (32) may move in the first direction D1 while the transfer medium M1 does not move, the transfer medium M1 may move in a direction opposite to the first direction D1 while the second inkjet head (32) does not move, and both the transfer medium M1 and the second inkjet head (32) may move along the first direction D1. Further, the second inkjet head (32) may also move relative to the transfer medium M1 in a second direction D2 intersecting the first direction D1. The first inkjet head (31) may move relative to the transfer medium M1 together with the second inkjet head (32), or may move relative to the transfer medium M1 separately from the second inkjet head (32).

[0013] The processing unit region A0 includes the following regions. (Region b1) A region corresponding to one single sheet of transfer medium when the transfer medium is a single sheet (see, for example, FIG. 8). (Region b2) A region corresponding to one conveyance amount when a transfer medium that is continuous paper on which lateral printing is performed is intermittently conveyed (see, for example, FIG. 7). (Region b3) A region corresponding to one conveyance amount for one sub-scan when a sub-scan is performed on a transfer medium on which serial printing is performed (see, for example, FIG. 9). (Region b4) A region corresponding to one cut transfer medium when a transfer medium on which line printing is performed is cut (see, for example, FIG. 10). Printing on single-sheet paper may be performed in any of the lateral method, serial method, and line method. The lateral method is a printing method in which an inkjet head is scanned in the main scanning direction and the sub-scanning direction intersecting the main scanning direction with respect to the processing unit area of the transfer medium, and ink is ejected from the inkjet head. The lateral method for continuous paper is a printing method in which ink is ejected from an inkjet head while scanning the inkjet head in the transport direction and a direction intersecting the transport direction with respect to the above-mentioned area b2 of the transfer medium during transport stop, and the continuous paper is intermittently transported in the transport direction in units corresponding to the above-mentioned area b2. The serial method is a printing method in which an inkjet head is reciprocated in the main scanning direction and ink is ejected from the inkjet head, and sub-scanning is performed between the main scans. The line method is a printing method in which ink is ejected from an inkjet head having a length equal to or greater than the width of the continuous paper onto the continuous paper being transported. The materials of the single-sheet paper and the continuous paper are not limited to strict paper, and may be resin, metal, etc.

[0014] In the base formation step ST2, the base ink 36b may be ejected from the second inkjet head (32) that is relatively moving in the first direction D1, or the base ink 36b may be ejected from the second inkjet head (32) that is relatively moving in the second direction D2 while the relative position in the first direction D1 remains unchanged. The processing unit area A0 may include a third area A3 where the base ink 36b is overlaid on the image IM1 after the first area A1 and before the second area A2. In this case, in the base formation step ST2, the ejection amount of the base ink 36b per unit area for the third area A3 may be made larger than the ejection amount of the base ink 36b per unit area for the second area A2 and smaller than the ejection amount of the base ink 36b per unit area for the first area A1. In the present application, "first", "second",... are terms for identifying each component included in a plurality of components having similarities, and do not mean order. Of course, the above remarks also apply in the following aspects.

[0015] [Aspect 2] As illustrated in FIG. 6 and the like, the first region A1 may include a portion where the base ink 36b is first overlapped with the image IM1 in the processing unit region A0. The second region A2 may include a portion where the base ink 36b is last overlapped with the image IM1 in the processing unit region A0. In the processing unit region A0, since the amount of the base ink discharged in the portion where the base ink 36b is last overlapped with the image IM1 is smaller than that in the portion where the base ink 36b is first overlapped with the image IM1, the flow of the base ink 36b due to the inclination of the transfer medium M1 in the adhesive application step ST3 is further suppressed. Therefore, the above aspect can further suppress the bleeding of the transferred image.

[0016] [Aspect 3] As illustrated in FIG. 13, at least one of the first region A1 and the second region A2 may include a first continuous region A11 that is connected together as the image IM1 in the region, and a second continuous region A12 that is separated from the first continuous region A11 and is connected together. Here, it is assumed that the area of the second continuous region A12 is larger than that of the first continuous region A11. In the base formation step ST2, the printing method may reduce the discharge amount of the base ink 36b per unit area for the second continuous region A12 compared to the discharge amount of the base ink 36b per unit area for the first continuous region A11. The larger the continuous region is, the more likely the flow of the base ink 36b due to the inclination of the transfer medium M1 occurs in the adhesive application step ST3. Since the discharge amount of the base ink for the second continuous region A12 having a large area in the first region A1 or the second region A2 is small, the flow of the base ink 36b due to the inclination of the transfer medium M1 in the adhesive application step ST3 is further suppressed. Therefore, the above aspect can further suppress the bleeding of the transferred image.

[0017] [Aspect 4] As illustrated in FIG. 6 and the like, in the base formation step ST2, in this printing method, main scanning is performed to eject the base ink 36b while relatively moving the second inkjet head (32) along a second direction D2 intersecting the first direction D1 with respect to the transfer medium M1. In the sub-scanning between the main scans, the position where the base ink 36b is overlaid on the image IM1 may be changed in the first direction D1 by relatively moving the second inkjet head (32) with respect to the transfer medium M1 in the first direction D1. The second region A2 may be a region where the base ink 36b is overlaid on the image IM1 in a main scan after the main scan in which the base ink 36b is overlaid on the image IM1 in the first region A1. In printing that performs main scanning and sub-scanning, such as the lateral method or the serial method, the difference in the landing time of the base ink 36b is greater in the sub-scanning direction than in the main scanning direction. For this reason, it is preferable to change the ejection amount of the base ink 36b in the sub-scanning direction rather than in the main scanning direction. Therefore, the above aspect can suitably suppress bleeding of the transferred image when printing that performs main scanning and sub-scanning is performed.

[0018] Here, the printing of Aspect 4 may be one-pass or multi-pass (two or more passes). The number of passes means the number of main scans accompanied by ejection of the base ink performed at the same location. The above remarks are also applicable to the following aspects.

[0019] [Aspect 5] As illustrated in FIG. 9, in this printing method, in the base formation step ST2, main scanning may be performed to eject the base ink 36b while relatively moving the second inkjet head (32) in the first direction D1 with respect to the transfer medium M1. The second region A2 may be a region where the base ink 36b is overlaid on the image IM1 after the first region A1 in the main scan in which the base ink 36b is overlaid on the image IM1 in the first region A1. Even during one main scan, there are differences in the landing time of the undercoat ink 36b, and the longer the distance of the main scan, the greater the difference in the landing time of the undercoat ink 36b. Since the discharge amount of the undercoat ink 36b for the second region A2 where the undercoat ink 36b is overlaid on the image IM1 is smaller than that for the first region A1 during one main scan, the flow of the undercoat ink 36b due to the inclination of the transfer medium M1 in the adhesive application step ST3 is suppressed. Therefore, the above aspect can preferably suppress the bleeding of the transfer image due to the difference in the landing time of the undercoat ink during the main scan. Of course, after setting the first region A1 and the second region A2 by fitting the sub-scanning direction to the first direction D1 as in the fourth aspect and changing the discharge amount of the undercoat ink 36b, and setting the first region A1 and the second region A2 by fitting the main-scanning direction to the first direction D1 as in the fifth aspect, the discharge amount of the undercoat ink 36b may be changed.

[0020] [Aspect 6] As illustrated in FIG. 11, in the present printing method, in the undercoat formation step ST2, the provisional discharge amount PD of the undercoat ink 36b is determined regardless of the position in the first direction D1 in the processing unit region A0, and the coefficient αi corresponding to the position in the first direction D1 is multiplied by the provisional discharge amount PD to determine the discharge amount DT of the undercoat ink 36b for the first region A1 and the second region A2. Note that the discharge amount DT of the undercoat ink 36b is also referred to as the undercoat ink discharge amount DT. In the above case, the undercoat ink discharge amount DT can be easily changed between the first region A1 and the second region A2. Further, by receiving the input of the coefficient αi from the user, the undercoat ink discharge amount DT can be adjusted according to the user's desire.

[0021] Whether the image transferred onto the transfer medium achieves the intended image quality is affected not only by the amount and composition of the base ink, but also by the amount and composition of the colored ink for the image, the amount and composition of the adhesive adhering to the base ink, and so on. Therefore, strictly speaking, the coefficient needs to be determined in consideration of the enormous number of assumed combinations of the amount and composition of the ink, the type of transfer medium, the amount and type of the adhesive, the type of the transfer medium, and so on. By accepting the input of the coefficient from the user, it is not necessary to prepare the coefficient for all the enormous number of assumed combinations, which can contribute to the reduction of the memory.

[0022] [Aspect 7] The base ink 36b may be an ink containing a component that blocks the transmission of light. In this case, since the color of the transfer medium M2 cannot be seen through the image portion, the image quality of the transferred image can be improved. Here, the ink containing a component that blocks the transmission of light includes an ink containing a component that diffusely reflects light, such as white ink, an ink containing a component that absorbs light, such as black ink, an ink containing a component that diffusely reflects light and a component that absorbs light, such as gray ink, and so on. This addendum is also applicable in the following aspects.

[0023] [Aspect 8] As illustrated in FIG. 6, assume that printing is performed by performing main scanning and sub-scanning. As illustrated in FIG. 15, the processing unit region A0 may include a first discharge amount region AD1 where the discharge amount per unit area of the base ink 36b overlaid on the image IM1 is a first discharge amount (for example, 40% in FIG. 15), and a second discharge amount region AD2 where the discharge amount per unit area of the base ink 36b overlaid on the image IM1 is greater than the first discharge amount (for example, 80% in FIG. 15). Here, the second discharge amount region AD2 is located at a position different from the first discharge amount region AD1 in the first direction D1, and the number of passes of the main scanning accompanied by the discharge of the base ink performed at the same location on the transfer medium M1 is defined as the number of passes NP. In this printing method, in the base forming step ST2, the number of passes NP in the second discharge amount region AD2 may be made larger than the number of passes NP in the first discharge amount region AD1. In the region where the discharge amount of the base ink is large, since the drying of the base ink 36b proceeds due to an increase in the number of passes NP, the flow of the base ink 36b due to the inclination of the transfer medium M1 in the adhesive application step ST3 is further suppressed. Therefore, the above aspect can further suppress bleeding of the transferred image.

[0024] [Aspect 9] Incidentally, as illustrated in FIGS. 1 and 5, the printing apparatus 1 according to one aspect is a printing apparatus 1 that performs printing on the transfer medium M1. The printing apparatus 1 includes an adhesive application step ST3 of attaching an adhesive 111 to an undercoat ink 36b superposed on an image IM1 formed on the transfer medium M1, and a transfer step ST5 of transferring the image IM1 to the transfer medium M2 by attaching the adhesive 111 to the transfer medium M2. As illustrated in FIGS. 2 to 4, the present printing apparatus 1 includes a first inkjet head (31) that discharges a colored ink 36a, a second inkjet head (32) that discharges the undercoat ink 36b, a drive unit 50, and a control unit 10. The drive unit 50 relatively moves the second inkjet head (32) in a first direction D1 with respect to the transfer medium M1. The control unit 10 controls the discharge of the colored ink 36a from the first inkjet head (31), the discharge of the undercoat ink 36b from the second inkjet head (32), and the drive unit 50. As illustrated in FIG. 5, the control unit 10 forms the image IM1 on the transfer medium M1 with the colored ink 36a discharged from the first inkjet head (31), and controls to superpose the undercoat ink 36b discharged from the second inkjet head (32) on the image IM1. Here, a processing unit region A0 is defined as a region where the adhesive 111 is supplied at the same timing in the adhesive application step ST3 with respect to the transfer medium M1. The processing unit region A0 includes a first region A1 and a second region A2 where the undercoat ink 36b is superposed on the image IM1 after the first region A1. The control unit 10 causes the discharge amount of the undercoat ink 36b per unit area for the second region A2 to be less than the discharge amount of the undercoat ink 36b per unit area for the first region A1.

[0025] The above aspect can provide a printing apparatus capable of suppressing bleeding of a transferred image.

[0026] Furthermore, the above-described aspects are applicable to a printing system including the above-described printing apparatus, a control method of the above-described printing apparatus, a control method of the above-described printing system, a control program of the above-described printing apparatus, a control program of the above-described printing system, a computer-readable recording medium recording any of the above-described control programs, and the like. Also, the above-described printing apparatus may be composed of a plurality of distributed parts.

[0027] (2) Specific examples of printing apparatuses: FIG. 1 schematically illustrates the configuration of a printing system that forms an image IM1 on a transfer medium M1 and transfers the image IM1 to a transfer target medium M2. The printing system shown in FIG. 1 includes a printing apparatus 1, an adhesive application apparatus 100, and a thermal transfer apparatus 200. The printing apparatus 1 may be a single printer 2, or may be composed of a printer 2 and a host apparatus HO1 as shown in FIG. 1. The host apparatus HO1 shown in FIG. 1 can generate image data DA1 corresponding to the image IM1 to be transferred, and can transmit the image data DA1 to the printer 2. Hereinafter, the image IM1 to be transferred is also referred to as the transfer image IM1. The printer 2 includes a printing unit 20 that ejects ink onto the transfer medium M1, and forms an image IM1 corresponding to the image data DA1 on the transfer medium M1. The adhesive application apparatus 100 includes an adhesive tank 110 that attaches an adhesive 111 to the ink on the transfer medium M1, and a heating unit 120 that heats the transfer medium M1 after the adhesive is applied. The thermal transfer apparatus 200 transfers the image IM1 from the transfer medium M1 to the transfer target medium M2.

[0028] For the transfer medium M1, a transfer film or the like capable of transferring an image by the DTF (Direct to Film) method can be used. For such a transfer film, a resin film such as a PET (polyethylene terephthalate) film can be preferably used. Of course, the material of the transfer medium M1 may include paper, metal, etc. in addition to resin, and the transfer medium M1 may be a metal film or the like. As the adhesive 111, a powdery adhesive such as a powdery hot melt adhesive can be used. The hot melt adhesive is a thermoplastic resin powder, which melts when heated above the melting point and solidifies when cooled. As the hot melt adhesive, an adhesive containing one or more thermoplastic resins selected from polyurethane resins, polyolefin resins, polyamide resins, polyester resins, etc. can be used. For the medium M2 to be transferred, fabrics such as knitted or woven fabrics, non-woven fabrics, etc. can be used, and fabrics processed like T-shirts, etc. may also be used.

[0029] Although details will be described later, in the printing apparatus 1, an image forming step ST1 and a base forming step ST2 are performed. In the adhesive applying apparatus 100, an adhesive applying step ST3 and a heating step ST4 are performed. In the thermal transfer apparatus 200, a transfer step ST5 is performed.

[0030] FIG. 2 is a plan view schematically illustrating the configuration of a printer 2 including an inkjet head 30. The processing unit region A0 shown in FIG. 2 is a rectangle with a length L0 and a width W0. FIG. 3 is a bottom view schematically illustrating the nozzle surface 30a of the inkjet head 30. FIG. 4 is a block diagram schematically illustrating the configuration of the printing apparatus 1. FIG. 5 schematically illustrates a printing method on the medium M2 to be transferred. FIG. 6 schematically illustrates the division of the processing unit region A0. Printer 2 is an inkjet printer that ejects liquid ink droplets 37. Printer 2 includes a control unit 10, a printing unit 20, a RAM (Random Access Memory) 21 which is a semiconductor memory, a communication I / F (Interface) 22, a storage unit 23, an operation panel 24, and the like. The control unit 10, the RAM 21, the communication I / F 22, the storage unit 23, and the operation panel 24 are connected to a bus and can input and output information to and from each other. The printing unit 20 includes an inkjet head 30 and a driving unit 50.

[0031] The control unit 10 includes a CPU (Central Processing Unit) 11 which is a processor, a color conversion unit 12, a halftone processing unit 13, a rasterization processing unit 14, a drive signal transmission unit 15, and the like. The control unit 10 can be constituted by an SoC (System on a Chip) or the like. Based on the image data DA1 acquired from any one of a host device HO1, an external memory (not shown), and the like, the control unit 10 controls the inkjet head 30 and the driving unit 50 so that an image IM1 of colored ink 36a and a layer of undercoat ink 36b are formed on the transfer medium M1. The image data DA1 can be applied with, for example, RGB data having integer values of, for example, 2 gradations of R (red), G (green), and B (blue) for each pixel. 8 tone integer values can be applied.

[0032] The CPU 11 is a device that mainly performs information processing and control in the printer 2. The color conversion unit 12 has, for example, a color conversion LUT (look-up table) in which the correspondence between the gradation values of R, G, and B and the gradation values of C (cyan), M (magenta), Y (yellow), K (black), and W (white) is defined. In the color conversion LUT, the gradation value of W is, for example, the value at which the undercoat ink 36b is used when at least one of the colored inks 36a of C, M, Y, and K is used. For example, when the gradation values of C, M, Y, and K are 0 indicating no use of colored ink, the gradation value of W may be 0 indicating no use of undercoat ink, and in the remaining cases, the gradation value of W may be 128 indicating 50% use of undercoat ink. Thereby, the undercoat ink 36b is overlaid on the position of the image IM1. Of course, the discharge amount of the undercoat ink 36b overlaid on the image IM1 may be less than 50% or more than 50% within the range where a transfer image IM1 with good image quality can be obtained. The color conversion unit 12 refers to the color conversion LUT and converts the RGB data into ink amount data having, for example, 2 8 integer gradation values of C, M, Y, and K for each pixel. The ink amount data represents the usage amount of the inks 36 of C, M, Y, K, and W in units of pixels. Note that the inks 36 shown in FIG. 4 include the colored inks 36a of C, M, Y, and K and the undercoat ink 36b. Also, when the resolution of the RGB data is different from the printing resolution, the color conversion unit 12 converts the resolution of the RGB data into the printing resolution first, or converts the resolution of the ink amount data into the printing resolution.

[0033] The halftone processing unit 13 performs halftone processing on the ink amount data by any one of the dither method, error diffusion method, etc., to generate dot data with the number of gradations reduced to, for example, 2 or 4. The dot data is generated for each of C, M, Y, K, and W. The dot data represents the dot formation state of the ink 36 in units of pixels. The rasterization processing unit 14 generates raster data by performing rasterization processing to rearrange the dot data in the order in which dots are formed by the driving unit 50.

[0034] The drive signal transmission unit 15 generates a drive signal SG1 corresponding to the voltage signal applied to the drive element 42 of the inkjet head 30 from the raster data and outputs it to the drive circuit 41 of the inkjet head 30. The RAM 21 stores the image data DA1 and the like received from the host device HO1 and the like. The communication I / F 22 inputs and outputs information to and from the host device HO1 and the like. Examples of the host device HO1 include computers such as personal computers and tablet terminals, mobile phones such as smartphones, and the like. The storage unit 23 may be a non-volatile semiconductor memory such as a flash memory, or a magnetic storage device such as a hard disk. The operation panel 24 includes an output unit 25 such as a liquid crystal panel for displaying information, an input unit 26 such as a touch panel for receiving operations on the display screen, and the like.

[0035] The drive circuit 41 applies a voltage signal to the drive element 42 according to the drive signal SG1 input from the drive signal transmission unit 15. The drive element 42 may be a piezoelectric element that applies pressure to the ink 36 in the pressure chamber communicating with the nozzle 34, or a drive element that generates bubbles in the pressure chamber by heat to eject ink droplets 37 from the nozzle 34. The ink 36 is supplied from the ink cartridge 35 to the pressure chamber of the inkjet head 30. The ink 36 in the pressure chamber is ejected as ink droplets 37 from the nozzle 34 toward the transfer medium M1 by the drive element 42. When the ink droplets 37 land on the transfer medium M1, dots are formed on the transfer medium M1. When dots of the colored ink 36a are formed on the transfer medium M1, an image IM1 represented by the dot pattern is formed on the transfer medium M1.

[0036] The inkjet head 30 shown in FIG. 3 includes a color ink head 31 that discharges color ink 36a and an undercoat ink head 32 that discharges undercoat ink 36b. The color ink head 31 is an example of a first inkjet head, and the undercoat ink head 32 is an example of a second inkjet head. The color ink 36a is an ink that contains a coloring material such as a pigment as a dispersed substance or solute in a liquid (e.g., water) as a dispersion medium or solvent. The color ink 36a includes, for example, chromatic inks of C, M, and Y, and an ink of K that is achromatic. The color ink head 31 includes a C ink head 31C that discharges C ink, an M ink head 31M that discharges M ink, a Y ink head 31Y that discharges Y ink, and a K ink head 31K that discharges K ink. The undercoat ink 36b is an ink that contains a component that blocks the transmission of light, and is, for example, a W ink that contains a component that diffusely reflects light. The W ink is an ink that contains a white pigment such as titanium oxide or zinc oxide as a dispersed substance in a liquid such as water as a dispersion medium. By the undercoat ink 36b blocking the transmission of light, the color of the transfer medium M2 that becomes the background of the image IM1 is not affected by the color of the image IM1, and a transfer medium M2 having an image IM1 with good image quality can be obtained. Each ink head (31C, 31M, 31Y, 31K, 32) has a nozzle array direction that intersects the second direction D2 as the scanning direction, for example, a nozzle row in which a plurality of nozzles 34 are arranged in the first direction D1. The plurality of nozzles 34 of each ink head may be arranged in a staggered pattern in the nozzle array direction, in other words, arranged in two rows in the nozzle array direction. The nozzle array direction may be offset from the first direction D1 within a range of less than 90°. Each nozzle 34 of the color ink head 31 discharges the color ink 36a as ink droplets 37, and each nozzle 34 of the undercoat ink head 32 discharges the undercoat ink 36b as ink droplets 37. The inkjet head 30 shown in FIGS. 2 to 4 is mounted on a carriage 33. When the printer 2 performs lateral printing, the carriage 33 is movable along the second direction D2 as the main scanning direction and the first direction D1 as the sub-scanning direction.

[0037] The driving unit 50 as a lateral system includes a main scanning driving unit 51, a sub-scanning driving unit 52, and a conveying unit 55. The main scanning driving unit 51 shown in FIG. 2 performs main scanning to eject ink 36 from the inkjet head 30 in at least one of the forward direction D11 and the reverse direction D12 while moving the inkjet head 30 along the second direction D2 as the main scanning direction. Focusing on the undercoat ink head 32, it can be said that the main scanning driving unit 51 performs main scanning to eject the undercoat ink 36b while relatively moving the undercoat ink head 32 along the second direction D2 with respect to the transfer medium M1. The sub-scanning driving unit 52 shown in FIG. 2 performs sub-scanning to move the inkjet head 30 along the first direction D1 as the sub-scanning direction during the main scanning intervals. That is, during sub-scanning, the inkjet head 30 moves intermittently along the first direction D1. Focusing on the undercoat ink head 32, it can be said that the sub-scanning driving unit 52 relatively moves the undercoat ink head 32 in the first direction D1 with respect to the transfer medium M1 during the sub-scanning between the main scans. The conveying unit 55 shown in FIGS. 2 and 4 conveys the transfer medium M1, which is continuous paper, along the first direction D1 as the conveying direction during the printing intervals of the processing unit area A0. That is, when not printing, the transfer medium M1 moves intermittently along the first direction D1. The conveying unit 55 shown in FIGS. 2 and 4 sends the transfer medium M1 in the first direction D1 along the conveying path 59. The platen 58 is located below the conveying path 59 and supports the transfer medium M1 by contacting the transfer medium M1 in the conveying path 59. The inkjet head 30 controlled by the control unit 10 adheres the ink 36 to the transfer medium M1 by ejecting ink droplets 37 toward the transfer medium M1 supported by the platen 58. The control unit 10 controls the ejection of the colored ink 36a from the colored ink head 31, the ejection of the undercoat ink 36b from the undercoat ink head 32, and the driving unit 50.

[0038] As long as the undercoat ink head 32 can overlay the undercoat ink 36b on the image IM1 formed by the colored ink 36a, various arrangements are conceivable. For example, the undercoat ink head 32 may be located at a position going in the forward direction D11 from the C ink head 31C shown in FIG. 3, or may be located at a position going in a direction opposite to the sub-scanning direction from the colored ink head 31.

[0039] Next, with reference to FIGS. 5, 6, etc., a printing method onto the transfer medium M2 will be described. The printing method shown in FIG. 5 includes the following steps. (c1) An image forming step ST1 of forming an image IM1 on the transfer medium M1 by discharging the colored ink 36a from the colored ink head 31. (c2) An undercoat forming step ST2 of relatively moving the undercoat ink head 32 in the first direction D1 with respect to the transfer medium M1 and overlaying the undercoat ink 36b on the image IM1 by discharging the undercoat ink 36b from the undercoat ink head 32. (c3) An adhesive applying step ST3 of attaching an adhesive 111 to the undercoat ink 36b overlaid on the image IM1 formed on the transfer medium M1. (c4) A heating step ST4 of heating the transfer medium M1 to which the adhesive 111 has been applied. (c5) A transfer step ST5 of transferring the image IM1 to the transfer medium M2 by attaching the adhesive 111 to the transfer medium M2.

[0040] For example, as shown in FIG. 6, assume a scenario where ink 36 is ejected from the inkjet head 30 in units of bands B1 to B6 with respect to the processing unit area A0. For example, when, for each band, a second main scan in which the base ink 36b lands is performed after the first main scan in which the colored ink 36a lands, the image forming step ST1 is performed in the first main scan, and the base forming step ST2 is performed in the second main scan. When the first main scan is a main scan in the forward direction D11, the second main scan may be a main scan in the reverse direction D12 like bidirectional printing, or may be a main scan in the forward direction D11 like unidirectional printing. As long as the base ink 36b does not mix with but overlaps the image IM1 formed by the colored ink 36a, the image forming step ST1 and the base forming step ST2 may be performed by one main scan in the forward direction D11 by the inkjet head 30 shown in FIG. 3. For each band, the image IM1 may be formed in one pass, the base ink 36b may be overlaid on the image IM1 in one pass, the image IM1 may be formed in multiple passes, or the base ink 36b may be overlaid on the image IM1 in multiple passes.

[0041] In the example shown in FIG. 1, the transfer medium M1 with the undercoat ink 36b laminated thereon is intermittently conveyed from the printer 2 to the adhesive applying device 100 and enters the adhesive tank 110 while being tilted. When the powdery adhesive 111 is contained in the adhesive tank 110, the adhesive 111 adheres to the still-un-dried undercoat ink 36b. FIG. 5 shows a state in which the image IM1, the undercoat ink 36b, and the powdery adhesive 111 are laminated in this order on the transfer medium M1 in the adhesive applying step ST3. In this way, the adhesive applying step ST3 is carried out. In the example shown in FIG. 1, the transfer medium M1 with the thermoplastic adhesive 111 applied thereto is intermittently conveyed from the adhesive tank 110 to the heating unit 120. During this period, excess adhesive 111 is shaken off due to the transfer medium M1 tilting again or the like. The heating unit 120 heats the transfer medium M1 to which the adhesive 111 has been applied. When the transfer medium M1 is heated to a temperature equal to or higher than the melting temperature of the adhesive 111, the adhesive 111 melts. FIG. 5 shows a state in which the image IM1, the dried undercoat ink 36b, and the melted adhesive 111 are laminated in this order on the transfer medium M1 in the heating step ST4. When the thermal transfer device 200 can heat the transfer medium M1, the heating unit 120 may perform preliminary heating on the transfer medium M1 to a temperature lower than the melting temperature of the adhesive 111. In this way, the heating step ST4 is carried out. In the example shown in FIG. 1, the heated transfer medium M1 is intermittently discharged from the heating unit 120. The discharged transfer medium M1 is cut as necessary, overlapped with the transfer medium M2 with the surface to which the adhesive 111 has been applied facing the transfer medium M2, and carried into the thermal transfer device 200.

[0042] The thermal transfer device 200 presses the transfer medium M1 and the medium to be transferred M2 in a state where the adhesive 111 applied to the transfer medium M1 is in contact with the medium to be transferred M2. When the thermal transfer device 200 includes a heating mechanism, the thermal transfer device 200 heats the transfer medium M1 and the medium to be transferred M2 to a temperature equal to or higher than the melting temperature of the adhesive 111. FIG. 5 shows a state in which the melted adhesive 111, the dried base ink 36b, the image IM1, and the transfer medium M1 are laminated in this order on the medium to be transferred M2. By pressing the transfer medium M1 and the medium to be transferred M2, the image IM1 adheres to the medium to be transferred M2 via the base ink 36b and the adhesive 111. In this way, the transfer step ST5 of transferring the image IM1 to the medium to be transferred M2 is performed. When the transfer medium M1 is peeled off from the medium to be transferred M2, the image IM1 remains on the medium to be transferred M2, and the medium to be transferred M2 with the image IM1 transferred as shown in FIG. 1 is obtained. Since there is a layer of the base ink 36b between the transferred image IM1 and the medium to be transferred M2, the color of the medium to be transferred M2 is suppressed from affecting the image IM1, and the image quality of the image IM1 is good.

[0043] Although the transfer medium M1 described above is continuous paper, the transfer medium M1 may be single-sheet paper. In this case, the user may put the printed single-sheet paper into the adhesive tank 110 to attach the powdery adhesive 111 to the base ink 36b. In this operation, the transfer medium M1 tilts.

[0044] When the base ink 36b lands on the image IM1 on the transfer medium M1, it gradually dries. In the processing unit area A0 where the adhesive 111 is supplied at the same timing in the adhesive application step ST3 with respect to the transfer medium M1, the lower the landing of the base ink 36b, the lower the degree of dryness of the base ink 36b. For this reason, when the transfer medium M1 tilts to apply the adhesive 111 or the like, the base ink 36b with a low degree of dryness may drip downward. When the base ink 36b drips downward, bleeding occurs in the transferred image IM1, and the image quality of the transferred image IM1 deteriorates. However, if the implementation of the adhesive application step ST3 is delayed to increase the drying time of the base ink 36b, the throughput after the adhesive application step ST3 decreases.

[0045] The printing apparatus 1 of this specific example solves the above-described problems by relatively reducing the discharge amount of the undercoat ink 36b per unit area for the second region A2 where the undercoat ink 36b is overlaid on the image IM1 relatively slowly in the processing unit region A0 described above. First, with reference to FIG. 6, an example of dividing the processing unit region A0 and the discharge amount of the undercoat ink per unit area of each region will be described.

[0046] The processing unit region A0 includes the regions b1 to b4 described above. FIG. 6 shows an example in which main scanning and sub-scanning are performed in units of bands B1 to B6 with respect to the region b1 for one single sheet of paper or the region b2 during lateral printing. The control unit 10 performs control to perform main scanning for discharging the ink 36 while relatively moving the inkjet head 30 along the second direction D2 with respect to the transfer medium M1. The control unit 10 performs control to change the position in the first direction D1 for forming the image IM1 on the transfer medium M1 by relatively moving the colored ink head 31 in the first direction D1 with respect to the transfer medium M1 during sub-scanning between main scans. Further, the control unit 10 performs control to change the position in the first direction D1 for overlaying the undercoat ink 36b on the image IM1 by relatively moving the undercoat ink head 32 in the first direction D1 with respect to the transfer medium M1 during sub-scanning. The image IM1 is formed on the transfer medium M1 in units of bands B1 to B6 in the order of the first direction D1, and the undercoat ink 36b is overlaid on the image IM1 in units of bands B1 to B6 in the order of the first direction D1. The processing unit region A0 shown in FIG. 6 includes a first region A1 and a second region A2 where the undercoat ink 36b is overlaid on the image IM1 after the first region A1. The second region A2 is a region where the undercoat ink 36b is overlaid on the image IM1 in the main scan after the main scan in which the undercoat ink 36b is overlaid on the image IM1 in the first region A1. FIG. 6 shows various examples C1 to C4 of dividing the bands B1 to B6 into regions.

[0047] In Example C1, bands B1 and B2 are assigned to the first region A1, bands B3 and B4 are assigned to the third region A3, and bands B5 and B6 are assigned to the second region A2. The first region A1 includes band B1 where the base ink 36b is first overlaid on the image IM1 in the processing unit region A0. The third region A3 is where the base ink 36b is overlaid on the image IM1 after the first region A1 and before the second region A2. The second region A2 includes band B6 where the base ink 36b is last overlaid on the image IM1 in the processing unit region A0. The control unit 10 controls the discharge amount of the base ink 36b per unit area for the first region A1 to the discharge amount DT1, controls the discharge amount of the base ink 36b per unit area for the third region A3 to the discharge amount DT3, and controls the discharge amount of the base ink 36b per unit area for the second region A2 to the discharge amount DT2. The discharge amount DT3 is less than the discharge amount DT1, and the discharge amount DT2 is less than the discharge amount DT3. The discharge amounts DT2 and DT3 may be set within a range where the influence on the image quality of the transferred image IM1 due to the change in the base ink discharge amount DT is small. Note that the discharge amount of the base ink 36b per unit area (referred to as DT) means the ratio (including percentage) of the number of dots formed by the ink droplets 37 for a predetermined number of pixels, and when dots of different sizes are formed, it means the ratio when converted to the largest dot (for example, a large dot). A pixel is the smallest element that constitutes an image and can have a color independently assigned. For example, when Nd large dots are formed for 100 pixels, the discharge amount DT is Nd%.

[0048] In the processing unit region A0, since the discharge amount DT2 for the second region A2 where the base ink 36b is overlaid on the image IM1 after the first region A1 is small, the flow of the base ink 36b due to the inclination of the transfer medium M1 in the adhesive application step ST3 is suppressed. By suppressing the flow of the base ink 36b, bleeding of the transferred image IM1 due to the base ink 36b dripping downward or the like is suppressed, and the image quality of the transferred image IM1 is improved. In addition, since a third region A3 with a discharge amount DT3 that is less than the discharge amount DT1 and greater than the discharge amount DT2 is present between the first region A1 and the second region A2, the change in the base ink discharge amount DT due to the change in the region is reduced. As a result, the influence on the image quality of the transfer image IM1 due to the change in the base ink discharge amount DT is reduced, and the image quality of the transfer image IM1 is improved.

[0049] In Example C2, there is no third region A3 in the processing unit region A0, bands B1 to B4 are assigned to the first region A1, and bands B5 and B6 are assigned to the second region A2. Even without the third region A3, since the discharge amount DT2 for the second region A2 is small, the flow of the base ink 36b due to the inclination of the transfer medium M1 in the adhesive application step ST3 is suppressed, and bleeding of the transfer image IM1 is suppressed. In Example C3, only the last band B6 is assigned to the second region A2, and bands B1 to B5 are assigned to the first region A1. Among the processing unit regions A0, the base ink 36b is most likely to flow in the last band B6. Therefore, also in Example C3, the flow of the base ink 36b due to the inclination of the transfer medium M1 in the adhesive application step ST3 is effectively suppressed, and bleeding of the transfer image IM1 is effectively suppressed.

[0050] In Example C4, the base ink discharge amounts DT of the respective bands B1 to B6 are set so that the base ink discharge amount DT gradually decreases from band B1 to band B6. In this case, for example, bands B1 to B5 can be fitted to the first region A1, and band B6 can be fitted to the second region A2. In Example C4, the influence on the image quality of the transfer image IM1 due to the change in the base ink discharge amount DT is reduced, and the image quality of the transfer image IM1 is improved.

[0051] FIG. 7 schematically illustrates the lateral intermittent conveyance for the continuous paper M11 as the transfer medium M1. The lateral method for the continuous paper M11 is a printing method in which the inkjet head 30 discharges ink 36 while scanning vertically and horizontally with respect to the processing unit area A0 of the continuous paper M11 during conveyance stop, and the continuous paper M11 is fed in the conveyance direction by the conveyance amount L1 corresponding to the processing unit area A0. In the example shown in FIG. 6, the second direction D2 is the main scanning direction, and the first direction D1 is the sub-scanning direction and also the conveyance direction. For the continuous paper M11, the adhesive 111 is supplied at the same timing in the adhesive application step ST3 in units of the conveyance amount L1. Therefore, the processing unit area A0 becomes the area b2 corresponding to one conveyance amount L1 when the continuous paper M11 is intermittently conveyed.

[0052] The state SA1 shown in FIG. 7 is a state in which the conveyance of the continuous paper M11 as the transfer medium M1 has stopped, and printing is being performed on the processing unit area A01 as the processing unit area A0. When the image IM1 is formed on the processing unit area A01 and the undercoat ink 36b is overlaid on the image IM1, the conveyance unit 55 feeds the continuous paper M11 by a predetermined conveyance amount L1 in the first direction D1. The conveyance amount L1 is a distance obtained by adding a predetermined margin to the length of the processing unit area A0 in the first direction D1. The next state SA2 is a state in which the conveyance of the continuous paper M11 has stopped, and printing is being performed on the processing unit area A02 as the processing unit area A0. When the image IM1 is formed on the processing unit area A02 and the undercoat ink 36b is overlaid on the image IM1, the conveyance unit 55 feeds the continuous paper M11 by the conveyance amount L1 in the first direction D1. The next state SA3 is a state in which the conveyance of the continuous paper M11 has stopped, and printing is being performed on the processing unit area A03 as the processing unit area A0. As described above, the printer 2 forms the image IM1 on the processing unit area A0 of the continuous paper M11 during conveyance stop, overlays the undercoat ink 36b on the image IM1, and intermittently conveys the continuous paper M11 in the first direction D1 by the conveyance amount L1.

[0053] FIG. 8 schematically illustrates the processing unit area A0 in the single-sheet paper M12. The printing on the single-sheet paper M12 may be any of the lateral method, the serial method, and the line method, but FIG. 8 shows an example of performing the lateral method or the serial method of printing on the single-sheet paper M12. When the transfer medium M1 is a single sheet of paper M12, the adhesive 111 is supplied at the same timing in the adhesive application step ST3 for one sheet of the single sheet of paper M12. Therefore, the processing unit area A0 becomes the area b1 corresponding to one sheet of the single sheet of paper.

[0054] In addition, in printing that performs main scanning and sub-scanning, the difference in the landing time of the undercoat ink 36b is greater in the sub-scanning direction than in the main scanning direction. For this reason, by changing the discharge amount of the undercoat ink 36b in the sub-scanning direction rather than in the main scanning direction, bleeding of the transfer image IM1 is preferably suppressed.

[0055] FIG. 9 schematically illustrates the division of the processing unit area A0 corresponding to the conveyance amount for one sub-scan. When serial printing is performed, the transfer medium M1 is conveyed in the conveyance direction by the conveyance amount L2 for one sub-scan at a time. There is a difference in the landing time of the undercoat ink 36b even during one main scan, and the difference in the landing time of the undercoat ink 36b increases as the distance of the main scan becomes longer. Therefore, it is conceivable to divide the area corresponding to one conveyance amount L2 in the transfer medium M1 into the processing unit area A0 and divide the processing unit area A0 in the main scanning direction. In the example shown in FIG. 9, the main scanning direction is an example of the first direction D1, and the sub-scanning direction is an example of the second direction D2. The conveyance direction of the transfer medium M1 is the direction opposite to the second direction D2. The drive unit 50 for realizing serial printing only needs to have a main scanning drive unit 51 and a conveyance unit 55. The main scanning drive unit 51 performs main scanning to discharge the ink 36 while moving the inkjet head 30 along the first direction D1, and the conveyance unit 55 performs sub-scanning to send the transfer medium M1 in the direction opposite to the second direction D2. In other words, the main scanning drive unit 51 changes the position in the first direction D1 where the undercoat ink 36b is overlaid on the image IM1 by performing main scanning to discharge the undercoat ink 36b while relatively moving the undercoat ink head 32 with respect to the transfer medium M1 along the first direction D1. The conveyance unit 55 relatively moves the undercoat ink head 32 with respect to the transfer medium M1 in the direction opposite to the second direction D2 in the sub-scanning between main scans.

[0056] The serial method for the continuous paper M11 is a printing method in which the inkjet head 30 ejects ink 36 while scanning the inkjet head 30 along the first direction D1 with respect to the processing unit area A0 of the continuous paper M11 during conveyance stop, and the continuous paper M11 is fed in the conveyance direction by the conveyance amount L2 each time. Therefore, the processing unit area A0 becomes the area b3 corresponding to the conveyance amount L2 for one sub-scan. The second area A2 divided in the main scanning direction is an area where the undercoat ink 36b is overlaid on the image IM1 in the main scanning later than the first area A1 where the undercoat ink 36b is overlaid on the image IM1 in the first area A1. In order to reduce the waste of the transfer medium M1, a plurality of separated images are often arranged on the transfer medium M1 in the main scanning direction. Therefore, a time difference occurs in the landing of the undercoat ink 36b overlaid on the image in the same main scanning. In such a case, by reducing the undercoat ink ejection amount for the second area A2 where the undercoat ink 36b is overlaid on the image IM1 later than the first area A1 where the undercoat ink 36b is overlaid on the image IM1 first in one main scanning, the flow of the undercoat ink 36b due to the inclination of the transfer medium M1 in the adhesive application step ST3 is suppressed.

[0057] FIG. 9 shows various examples C1 to C4 of dividing the processing unit region A0 corresponding to the conveyance amount L2 for one sub-scan. In example C1, the main scan start region on the left part of FIG. 9 is assigned to the first region A1, the main scan end region on the right part of FIG. 9 is assigned to the second region A2, and the third region A3 is assigned between the first region A1 and the second region A2. The ejection amount DT3 for the third region A3 is less than the ejection amount DT1 for the first region A1, and the ejection amount DT2 for the second region A2 is less than the ejection amount DT3 for the third region A3. In example C2, there is no third region A3 in the processing unit region A0, the main scan end region is assigned to the second region A2, and the rest is assigned to the first region A1. In example C3, the second region A2 is narrower and the first region A1 is wider compared to example C2. Since the undercoat ink 36b is most likely to flow at the main scan end part at the right end of FIG. 9 within the processing unit region A0, even in example C3, the flow of the undercoat ink 36b due to the inclination of the transfer medium M1 in the adhesive application step ST3 is effectively suppressed. In example C4, the undercoat ink ejection amount DT of the processing unit region A0 is set such that the undercoat ink ejection amount DT gradually decreases from the main scan start part to the main scan end part. In example C4, the influence on the image quality of the transfer image IM1 due to the change in the undercoat ink ejection amount DT is reduced. Of course, as shown in FIG. 6, after fitting the sub-scan direction to the first direction D1 for region division and changing the undercoat ink ejection amount DT, the main scan direction may be fitted to the first direction D1 for region division and the undercoat ink ejection amount DT may be changed as shown in FIG. 9.

[0058] FIG. 10 schematically illustrates the processing unit region A0 when the continuous paper M11 is cut at the cutting position P1. The printer 2 shown in FIG. 10 is assumed to perform line-by-line printing on the continuous paper M11, but the printing on the continuous paper M11 to be cut may also be in a lateral or serial manner. When line-by-line printing is performed, the continuous paper M11 continuously moves in the conveyance direction, which is the right direction in FIG. 10. The first direction D1 in which the inkjet head 30 moves relative to the continuous paper M11 is the direction opposite to the conveyance direction. When the continuous paper M11 on which the image IM1 with the undercoat ink 36b superimposed thereon is formed is cut, the adhesive 111 is supplied at the same timing in the adhesive application step ST3 to one transfer medium M13 obtained from the continuous paper M11. Therefore, the processing unit area A0 becomes the area b4 corresponding to one cut transfer medium. In the processing unit area A0, the second area A2 is located closer to the printer 2 than the first area A1. In the second area A2, the undercoat ink 36b is superimposed on the image IM1 later than in the first area A1.

[0059] (3) Specific Example of Processing of Printing Apparatus: FIG. 11 schematically illustrates a printing control process for forming the image IM1 on the transfer medium M1 and controlling the undercoat ink 36b to be superimposed on the image IM1. FIG. 11 also shows a structural example of the coefficient table T1 for calculating the undercoat ink discharge amount DT. The printer 2 holds the coefficient table T1, and the coefficient table T1 may be stored in the storage unit 23. The printing control process shown in FIG. 11 targets lateral or serial printing. When the control unit 10 shown in FIG. 4 receives a printing instruction to the transfer medium M1 from the host device HO1 or the operation panel 24, it starts the printing control process. When the printing control process starts, the control unit 10 acquires the image data DA1 representing the transfer medium M1 from the host device HO1 or the like (step S102). Hereinafter, the description of "step" may be omitted, and the step number may be indicated in parentheses.

[0060] After acquiring the image data DA1, the control unit 10 sets a target pixel for color conversion from among a plurality of pixels constituting the image data DA1 (S104). Next, the control unit 10 converts the gradation value of the target pixel into a value representing the usage amounts of the colored ink 36a and the undercoat ink 36b (S106). When the image data DA1 is RGB data and the ink amount data is CMYKW data representing the usage amounts of the inks 36 of C, M, Y, K, and W, the control unit 10 refers to a color conversion LUT and converts each pixel value of R, G, and B into each pixel value of C, M, Y, K, and W. In the color conversion LUT, it is assumed that the gradation value of W is a value at which the undercoat ink 36b is used when at least one of the colored inks 36a of C, M, Y, and K is used. Thereby, the undercoat ink 36b is overlaid on the position of the image IM1. The gradation value of W after color conversion at the target pixel represents the provisional discharge amount PD of the undercoat ink 36b that is determined regardless of the position in the first direction D1 in the processing unit area A0. Since the provisional discharge amount PD is represented by 0 to 100%, if the gradation value of W is 0 to 255, the gradation value of W represents the provisional discharge amount PD by associating the gradation values 0 to 255 with the provisional discharge amounts 0 to 100%.

[0061] Next, the control unit 10 refers to the coefficient table T1 and multiplies the coefficient αi corresponding to the area Ai included in the processing unit area A0 by the provisional discharge amount PD of the undercoat ink 36b to calculate the undercoat ink discharge amount DT (S108). Here, the area Ai is any one of the first area A1, the second area A2, and the third area A3. The coefficient αi is a coefficient corresponding to the position in the first direction D1. The process of S108 can also be said to be a process of correcting the undercoat ink data such as the W data among the CMYKW data and the ink amount data. The coefficient table T1 has a coefficient α1 associated with the first region A1, a coefficient α2 associated with the second region A2, and a coefficient α3 associated with the third region A3. In FIG. 11, it is shown that α1 = 1.2, α2 = 0.8, and α3 = 1.0. In this case, the discharge amount DT1 for the first region A1 is 1.2×PD, the discharge amount DT2 for the second region A2 is 0.8×PD, and the discharge amount DT3 for the third region A3 is 1.0×PD. Therefore, the discharge amount DT3 for the third region A3 is less than the discharge amount DT1 for the first region A1, and the discharge amount DT2 for the second region A2 is less than the discharge amount DT3 for the third region A3.

[0062] As described above, the control unit 10 determines a provisional discharge amount PD regardless of the position in the first direction D1, and multiplies the coefficient αi by the provisional discharge amount PD to determine the discharge amount DT of the undercoat ink 36b for the region Ai. By determining αi×PD as the discharge amount DT in units of the region Ai, the amount of calculation can be reduced compared to the case where the discharge amount DT is linearly changed over the entire processing unit region A0 in the first direction D1, and high-speed processing is realized. After determining the discharge amount DT, the control unit 10 determines whether the processes of S104 to S108 have been performed for all the pixels of the image data DA1 (S110). If there are remaining pixels for which the processes of S104 to S108 have not been performed, the control unit 10 returns the process to S104.

[0063] When the processes of S104 to S108 are performed for all pixels, the control unit 10 performs halftone processing to generate dot data in which the gradation number of the obtained ink amount data is reduced to, for example, 2 or 4 (S112). The dot data is generated for each of C, M, Y, K, and W. After the halftone processing, the control unit 10 performs rasterization processing to generate raster data in which the dot data is rearranged so that the main scan for overlaying the undercoat ink 36b on the image IM1 is performed after the main scan for forming the image IM1 (S114). For example, it is assumed that the printing unit 20 performs the second main scan in which the undercoat ink 36b lands after the first main scan in which the colored ink 36a lands on each band in the processing unit area A0. In this case, the control unit 10 generates raster data in which the dot data is rearranged so that the colored ink 36a is ejected in the first main scan so that the image IM1 is formed, and the undercoat ink 36b is ejected in the second main scan so that it is overlaid on the image IM1.

[0064] Finally, the control unit 10 generates a drive signal SG1 according to the raster data, transmits it to the inkjet head 30, controls the printing unit 20 so as to form the image IM1 on the transfer medium M1 and overlay the undercoat ink 36b on the image IM1 (S116). The drive unit 50 relatively moves the inkjet head 30 with respect to the transfer medium M1 so that the main scan and the sub-scan are performed according to the control by the control unit 10. The colored ink head 31 ejects the colored ink 36a so that the image IM1 is formed on the transfer medium M1 during the main scan, and the undercoat ink head 32 ejects the undercoat ink 36b so that the undercoat ink 36b is overlaid on the image IM1 during the main scan. Here, since the discharge amount DT2 for the second region A2 where the base ink 36b is overlaid on the image IM1 is less than that for the first region A1 and the third region A3, the flow of the base ink 36b due to the inclination of the transfer medium M1 in the adhesive application step ST3 is suppressed. As a result, bleeding of the transferred image IM1 due to the base ink 36b dripping downward or the like is suppressed, and the image quality of the transferred image IM1 is improved. Further, since the third region A3 having a discharge amount DT3 that is less than the discharge amount DT1 and more than the discharge amount DT2 is located between the first region A1 and the second region A2, the influence on the image quality of the transferred image IM1 due to the change in the base ink discharge amount DT is reduced, and the image quality of the transferred image IM1 is improved.

[0065] As illustrated in FIG. 12, the printing apparatus 1 can receive the setting of the coefficient αi. FIG. 12 schematically illustrates the coefficient setting process. FIG. 12 also illustrates a coefficient setting screen 500 as a user interface screen for receiving the setting of the coefficient αi. The coefficient setting process may be performed by the printer 2 or may be performed by the cooperation of the host device HO1 and the printer 2. For example, when the control unit 10 of the printer 2 receives a setting instruction for the coefficient αi from the operation panel 24, it starts the coefficient setting process. First, the control unit 10 causes the output unit 25 of the operation panel 24 to display the coefficient setting screen 500, and when the input unit 26 receives an operation on the coefficient setting screen 500, it acquires the set value corresponding to the operation from the operation panel 24 (S202). The coefficient setting screen 500 has an input field 501 for the coefficient α1, an input field 502 for the coefficient α3, an input field 503 for the coefficient α2, an OK button 504, etc. In the initial coefficient setting screen 500, the control unit 10 causes the coefficient α1 of the coefficient table T1 to be displayed in the input field 501, the coefficient α3 of the coefficient table T1 to be displayed in the input field 502, and the coefficient α2 of the coefficient table T1 to be displayed in the input field 503. The operation panel 24 receives a change in the coefficient α1 in the input field 501, receives a change in the coefficient α3 in the input field 502, and receives a change in the coefficient α2 in the input field 502. When the operation panel 24 receives an operation on the OK button 504, it transmits the coefficient α1 displayed in the input field 501, the coefficient α3 displayed in the input field 502, and the coefficient α2 displayed in the input field 503 to the control unit 10.

[0066] The control unit 10 stores the coefficients α1 to α3 received from the operation panel 24 in the coefficient table T1 (S204) and ends the coefficient setting process. Thereby, the base ink ejection amount DT is calculated according to the set coefficient αi. Also, the host device HO1 may start the coefficient setting process in response to a setting instruction for the coefficient αi. In this case, in S202, the host device HO1 acquires the coefficient αi from the printer 2, causes the coefficient setting screen 500 to be displayed on the display, and receives an operation on the coefficient setting screen 500 by an input device such as a keyboard, a pointing device, a touch panel, etc. When the host device HO1 receives an operation on the OK button 504, in S204, it transmits the coefficients αi displayed in the input fields 501 to 503 to the printer 2. The printer 2 that has received the coefficient αi may store the coefficient αi in the coefficient table T1.

[0067] By performing the coefficient setting process described above, the base ink ejection amount DT can be adjusted according to the user's requirements. Whether the transferred image IM1 has the intended image quality is affected not only by the amount and composition of the base ink 36b, but also by the amount and composition of the colored ink 36a, the amount and composition of the adhesive 111, and so on. Therefore, strictly speaking, the coefficient αi needs to be determined in consideration of a huge number of assumed combinations such as the amount and composition of the ink 36, the type of the transfer medium M1, the amount and type of the adhesive 111, the type of the medium to be transferred M2, and so on. By performing the coefficient setting process described above, it is not necessary to prepare the coefficient αi for all the huge number of assumed combinations, and the storage area for the coefficient αi can be reduced.

[0068] Note that, as illustrated in FIG. 13, the ejection amount DT1 of the base ink 36b overlaid on the image IM1 in the first region A1 is not limited to being constant, and the ejection amount DT2 of the base ink 36b overlaid on the image IM1 in the second region A2 is also not limited to being constant. FIG. 13 schematically shows an example in which the base ink ejection amount DT is changed according to the size of the continuous region of the image IM1 within the same region.

[0069] The first region A1 shown in FIG. 13 includes a first continuous region A11 that is connected as one piece as the image IM1 within the first region A1, and a second continuous region A12 that is separated from the first continuous region A11 and is connected as one piece. The area of the second continuous region A12 is larger than that of the first continuous region A11. Within the same first region A1, the larger the continuous region, the easier it is for the base ink 36b to flow due to the inclination of the transfer medium M1 in the adhesive application step ST3. Therefore, the control unit 10 may make the ejection amount DT12 of the base ink 36b per unit area for the second continuous region A12 smaller than the ejection amount DT11 of the base ink 36b per unit area for the first continuous region A11. Thereby, the flow of the base ink 36b due to the inclination of the transfer medium M1 in the adhesive application step ST3 is further suppressed.

[0070] The second region A2 shown in FIG. 13 includes, as an image IM1 within the second region A2, a first continuous region A11 that is connected together and a second continuous region A12 that is separated from the first continuous region A11 and is connected together. The area of the second continuous region A12 is larger than that of the first continuous region A11. Within the same second region A2, the larger the continuous region, the more likely it is that the base ink 36b will flow due to the inclination of the transfer medium M1 in the adhesive application step ST3. In particular, in the second region A2, since the drying time of the base ink 36b is short, the base ink 36b is more likely to flow in the relatively large second continuous region A12. Therefore, the control unit 10 may make the discharge amount DT22 of the base ink 36b per unit area for the second continuous region A12 less than the discharge amount DT21 of the base ink 36b per unit area for the first continuous region A11. Thereby, the flow of the base ink 36b due to the inclination of the transfer medium M1 in the adhesive application step ST3 is further suppressed.

[0071] Note that in the second region A2, DT21 > DT22, while in the first region A1, DT11 = DT12 may be the case, or in the first region A1, DT11 > DT12, while in the second region A2, DT21 = DT22 may be the case. Even when the third region A3 includes a first continuous region A11 with a small area and a second continuous region A12 with a large area, the discharge amount of the base ink per unit area for the second continuous region A12 may be made less than the discharge amount of the base ink per unit area for the first continuous region A11.

[0072] FIG. 14 schematically illustrates the structure of a coefficient table T1 for changing the discharge amount DT of the base ink according to the size of the continuous region of the image IM1 within the same region. The coefficient table T1 shown in FIG. 14 has a coefficient α1 associated with the first region A1, a coefficient α2 associated with the second region A2, and a coefficient α3 associated with the third region A3. Here, the coefficient αi changes according to the area of the continuous region. The coefficient αi shown in FIG. 14 is smaller for the second continuous region A12 where the area of the continuous region is equal to or greater than the threshold value THA than for the first continuous region A11 where the area of the continuous region is less than the threshold value THA. For example, in the second region A2, the coefficient αi in the first continuous region A11 is 0.8, and the coefficient αi in the second continuous region A12 is 0.7. Note that the coefficient αi within the same region may switch in three or more steps, or may change linearly.

[0073] The printing control process that refers to the coefficient table T1 shown in FIG. 14 can be performed according to the printing control process shown in FIG. 11. For example, in S102, the control unit 10 may extract the continuous regions included in the first region A1, the continuous regions included in the second region A2, and the continuous regions included in the third region A3 based on the image data DA1. Moreover, the control unit 10 may obtain the area of each continuous region by S108. The area of the continuous region can be obtained, for example, by counting the number of pixels included in the continuous region. In each region Ai, the control unit 10 determines that the continuous region is the first continuous region A11 when the area of the continuous region is less than the threshold value THA, and determines that the continuous region is the second continuous region A12 when the area of the continuous region is equal to or greater than the threshold value THA. In S108, the control unit 10 may refer to the coefficient αi corresponding to the area of the continuous region in the region Ai from the coefficient table T1, and calculate the base ink discharge amount DT by multiplying the coefficient αi by the provisional discharge amount PD of the base ink 36b. When the coefficient table T1 shown in FIG. 14 is referred to, the control unit 10 applies the coefficient αi corresponding to less than the threshold value THA in the first continuous region A11 and applies the coefficient αi corresponding to equal to or greater than the threshold value THA in the second continuous region A12. By performing the printing control process as described above, the flow of the base ink 36b due to the inclination of the transfer medium M1 in the adhesive application step ST3 is further suppressed, and the bleeding of the transferred image is further suppressed.

[0074] As illustrated in FIG. 15, the number of passes NP of the processing unit area A0 is not limited to being constant, and may vary according to the area. Here, the number of passes NP means the number of main scans accompanied by the ejection of the undercoat ink 36b performed at the same location on the transfer medium M1. FIG. 15 schematically shows an example of changing the number of passes NP according to the undercoat ink ejection amount DT per unit area. FIG. 15 also shows an example of the structure of a pass number table T2 for determining the number of passes NP according to the undercoat ink ejection amount DT. The pass number table T2 is used when main scanning and sub-scanning are performed. In the pass number table T2 shown in FIG. 15, the correspondence between the undercoat ink ejection amount DT and the number of passes NP is defined. In the pass number table T2, the number of passes NP increases step by step as the ejection amount of W as the undercoat ink ejection amount DT increases.

[0075] The processing unit area A0 shown in FIG. 15 includes a first ejection amount area AD1 where the undercoat ink ejection amount DT per unit area is 40% as the first ejection amount, and a second ejection amount area AD2 where the undercoat ink ejection amount DT per unit area is 80% as the second ejection amount. Here, the second ejection amount has a larger undercoat ink ejection amount DT than the first ejection amount, and the second ejection amount area AD2 is located at a different position from the first ejection amount area AD1 in the first direction D1. As shown in FIG. 15, the second area A2 is an example of the first ejection amount area AD1, and the first area A1 is an example of the second ejection amount area AD2. Note that when the second area A2 is fitted to the first ejection amount area AD1, the third area A3 may be fitted to the second ejection amount area AD2, or when the third area A3 is fitted to the first ejection amount area AD1, the first area A1 may be fitted to the second ejection amount area AD2. The control unit 10 makes the number of passes NP in the second ejection amount area AD2 larger than the number of passes NP in the first ejection amount area AD1.

[0076] For example, when the base ink discharge amount DT in the first discharge amount region AD1 is 40%, the control unit 10 sets the number of passes NP to 4 according to the pass number table T2. When the base ink discharge amount DT in the second discharge amount region AD2 is 80%, the control unit 10 sets the number of passes NP to 8 according to the pass number table T2. As shown in FIG. 15, the number of passes NP in the third discharge amount region where the discharge amount DT is larger than that in the first discharge amount region AD1 and smaller than that in the second discharge amount region AD2, for example, in the third region A3, may be larger than the number of passes NP in the first discharge amount region AD1 and smaller than the number of passes NP in the second discharge amount region AD2.

[0077] The printing control process that refers to the pass number table T2 can be performed according to the printing control process shown in FIG. 11. For example, in S112, the control unit 10 calculates the average value of the discharge amount of the base ink 36b of the portion overlaid on the image IM1 for each region Ai based on the W data included in the CMYKW data, and may refer to the pass number table T2 using the average value as the base ink discharge amount DT. Thereafter, the control unit 10 sets the number of passes NP corresponding to the base ink discharge amount DT for each region Ai, and may generate dot data with the gradation number of the ink amount data reduced to 2 or 4, for example. In a region where the base ink discharge amount DT is large, the drying of the base ink 36b proceeds as the number of passes NP increases, so the flow of the base ink 36b due to the inclination of the transfer medium M1 in the adhesive application step ST3 is further suppressed.

[0078] In addition, when the main scanning can be stopped in the middle of the band, it is possible to change the number of main scans within the band. When the first discharge amount region AD1 and the second discharge amount region AD2 are set within one band such that the first region A1 and the second region A2 are set within one band, the control unit 10 may control the number of main scans in the second discharge amount region AD2 to be larger than the number of main scans in the first discharge amount region AD1. In a region where the base ink discharge amount DT is large, the drying of the base ink 36b proceeds as the number of main scans increases, so the flow of the base ink 36b due to the inclination of the transfer medium M1 in the adhesive application step ST3 is further suppressed.

[0079] (4) Variation example: The present invention can have various variation examples. For example, the entity performing the above-described processing is not limited to the CPU, and may be an electronic component other than the CPU, such as an ASIC (Application Specific Integrated Circuit). Of course, a plurality of CPUs may cooperate to perform the above-described processing, or the CPU and other electronic components (for example, ASIC) may cooperate to perform the above-described processing. Part of the print control processing shown in FIG. 11 may be performed by the host device HO1. In this case, the control unit of the printing device 1 is a combination of the control unit 10 in the narrow sense and the host device HO1. The combination of the colors of the colored inks 36a is not limited to C, M, Y, and K, and may include orange, green, light cyan with a lower concentration than C, light magenta with a lower concentration than M, dark yellow with a higher concentration than Y, light black with a lower concentration than K, and the like. Of course, even when the colored ink 36a does not contain some of the inks of C, M, Y, and K, the aspects of the present application are applicable.

[0080] The undercoat ink 36b is not limited to the W ink, and may be a K ink containing a component that absorbs light, a gray ink containing a component that diffusely reflects light and a component that absorbs light, and the like. Also, a clear ink that allows light to pass through although the color of the transfer medium M2 that becomes the background of the image IM1 passes through can also be used as the undercoat ink 36b. FIGS. 13 and 14 show an example of changing the undercoat ink discharge amount DT according to the size of the continuous area of the image IM1 within the same area, but the control unit 10 may change the undercoat ink discharge amount DT according to the color of the image IM1 within the same area.

[0081] The above-described printing control process shows an example of changing the base ink ejection amount DT for each area Ai by adjusting the ink amount data for the base ink 36b. However, it is also possible to change the base ink ejection amount DT for each area Ai other than this example. For example, the control unit 10 may generate CMYK data that does not include W data from RGB data, generate colored dot data for each of C, M, Y, and K from the CMYK data, and then generate 4-value W dot data based on the colored dot data. Here, the control unit 10 may generate W dot data in which large dots of W are generated for pixels where dots of the colored ink 36a are generated for the first area A1, and generate W dot data in which medium dots of W are generated for pixels where dots of the colored ink 36a are generated for the second area A2. Thereby, the base ink ejection amount DT can be made smaller in the second area A2 than in the first area A1. Further, the control unit 10 may reduce the base ink ejection amount DT in the second area A2 compared to the first area A1 by applying a data mask that reduces the generation rate of W dots for the second area A2.

[0082] (5) Conclusion: As described above, according to the present invention, it is possible to provide a configuration or the like that can suppress bleeding of the transferred image in various aspects. Of course, even in an aspect consisting only of the constituent elements according to the independent claims, the above-described basic actions and effects can be obtained. Also, configurations in which each configuration disclosed in the above-described examples is mutually replaced or the combination is changed, known techniques, and configurations in which each configuration disclosed in the above-described examples is mutually replaced or the combination is changed, etc. are also feasible. The present invention includes these configurations and the like.

Explanation of Signs

[0083] 1…Printing device, 2…Printer, 10…Control unit, 20…Printing unit, 30…Inkjet head, 31…Colored ink head, 32…Undercoat ink head, 33…Carriage, 34…Nozzle, 36…Ink, 36a…Colored ink, 36b…Undercoat ink, 37…Ink droplet, 50…Drive unit, 51…Main scanning drive unit, 52…Sub-scanning drive unit, 55…Conveyor unit, 100…Adhesive application device, 110…Adhesive tank, 111…Adhesive, 120…Heating unit, 200…Thermal transfer device, 500…Coefficient setting screen, A0, A01, A02, A03…Processing unit area, A1…First area, A2…Second area, A3…Third area, A11…First continuous area, A12…Second continuous area, AD1…First discharge amount area, AD2…Second discharge amount area, D1…First direction, D2…Second direction, D11…Forward direction, D12…Return direction, DA1…Image data, DT…Discharge amount, IM1…Image, L1, L2…Conveyor amount, M1…Transfer medium, M2…Medium to be transferred, M11…Continuous paper, M12…Single sheet paper, NP…Number of passes, PD…Tentative discharge amount, ST1…Image forming process, ST2…Undercoat forming process, ST3…Adhesive application process, ST4…Heating process, ST5…Transfer process, T1…Coefficient table, T2…Number of passes table, αi…Coefficient.

Claims

1. An adhesive application step of applying an adhesive to an undercoat ink overlaid on an image formed on a transfer medium, and a transfer step of transferring the image to the transfer medium by attaching the adhesive to the transfer medium, a printing method for performing printing on the transfer medium, An image forming step of forming the image on the transfer medium by ejecting a colored ink from a first inkjet head, A base forming step of overlaying the undercoat ink on the image by ejecting the undercoat ink from a second inkjet head onto the transfer medium, including: Taking, as a processing unit area, an area where the adhesive is supplied at the same timing in the adhesive application step with respect to the transfer medium, the processing unit area including a first area and a second area where the undercoat ink is overlaid on the image after the first area, In the base forming step, a printing method in which the discharge amount of the undercoat ink per unit area for the second area is made smaller than the discharge amount of the undercoat ink per unit area for the first area.

2. The first area includes a portion where the undercoat ink is first overlaid on the image in the processing unit area, The printing method according to claim 1, wherein the second area includes a portion where the undercoat ink is finally overlaid on the image in the processing unit area.

3. At least one of the first area and the second area includes, as the image within the area, a first continuous area that is connected together and a second continuous area that is separated from the first continuous area and is connected together, The area of the second continuous area is larger than that of the first continuous area, The printing method according to claim 1 or claim 2, wherein in the base forming step, the discharge amount of the undercoat ink per unit area for the second continuous area is made smaller than the discharge amount of the undercoat ink per unit area for the first continuous area.

4. In the base forming step, while relatively moving the second inkjet head with respect to the transfer medium along a second direction intersecting a first direction in which the transfer medium is relatively moved with respect to the second inkjet head, main scanning for ejecting the undercoat ink is performed, and in a sub-scan between the main scans, the position where the undercoat ink is overlaid on the image is changed in the first direction by relatively moving the second inkjet head with respect to the transfer medium in the first direction. The printing method according to claim 1 or claim 2, wherein the second area is an area where the base ink is overlaid on the image in the main scan after the main scan in which the base ink is overlaid on the image in the first area.

5. In the base formation step, a main scan is performed to eject the base ink while relatively moving the second inkjet head in the first direction with respect to the transfer medium. The printing method according to claim 1 or claim 2, wherein the second area is an area where the base ink is overlaid on the image after the first area in the main scan in which the base ink is overlaid on the image in the first area.

6. In the base formation step, a tentative ejection amount of the base ink is determined regardless of the position in the first direction in the processing unit area, and a coefficient corresponding to the position in the first direction is multiplied by the tentative ejection amount to determine the ejection amount of the base ink for the first area and the second area. The printing method according to claim 1 or claim 2.

7. The printing method according to claim 1 or claim 2, wherein the base ink is an ink containing a component that blocks the transmission of light.

8. In the base formation step, a main scan is performed to eject the base ink while relatively moving the second inkjet head along a second direction intersecting the first direction with respect to the transfer medium, and in the sub-scan between the main scans, the second inkjet head is relatively moved in the first direction with respect to the transfer medium to change the position where the base ink is overlaid on the image in the first direction. The processing unit area includes a first ejection amount area where the ejection amount per unit area of the base ink overlaid on the image is the first ejection amount, and a second ejection amount area where the ejection amount per unit area of the base ink overlaid on the image is a second ejection amount that is more than the first ejection amount. The second ejection amount area is located at a position different from the first ejection amount area in the first direction. Regarding the number of times of the main scan accompanied by the ejection of the base ink performed at the same location on the transfer medium as the number of passes. The printing method according to claim 1 or claim 2, wherein in the base formation step, the number of passes in the second ejection amount area is made larger than the number of passes in the first ejection amount area.

9. A printing apparatus that performs printing on the transfer medium to carry out an adhesive application step of attaching an adhesive to a base ink overlaid on an image formed on the transfer medium, and a transfer step of transferring the image to the transfer medium by attaching the adhesive to the transfer medium. A first inkjet head that discharges a colored ink. A second inkjet head that discharges the base ink. A drive unit that relatively moves the second inkjet head in a first direction with respect to the transfer medium. It includes a control unit that controls the discharge of the colored ink from the first inkjet head, the discharge of the base ink from the second inkjet head, and the drive unit. The control unit controls to form the image on the transfer medium with the colored ink discharged from the first inkjet head and to overlay the base ink discharged from the second inkjet head on the image. Taking the region where the adhesive is supplied at the same timing in the adhesive application step with respect to the transfer medium as a processing unit region, the processing unit region includes a first region and a second region where the base ink is overlaid on the image after the first region. The control unit reduces the discharge amount of the base ink per unit area for the second region compared to the discharge amount of the base ink per unit area for the first region. A printing apparatus.

Images