JP2012131155A - Printer and printing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To print an image printed at high duty and an image printed at low duty in a superimposed manner by a simple structure.SOLUTION: The method includes executing a first printing and a second printing. In the first printing, a second image is formed on a first image by discharging, in a positional relationship such that nozzles of a first head 41A are aligned with nozzles which are located on the carrying-directional upstream side when a nozzle string of a second head 41B is halved, ink from the nozzles of the first head to form the first image on a medium, while discharging ink from nozzles on the carrying-directional downstream side of the halved nozzle string of the second head to form the second image. In the second printing, the second image is formed on the first image by discharging, in a positional relationship such that the nozzles of the first head are aligned with the nozzles on the carrying-directional downstream side of the second head, ink from the nozzles on the carrying-directional upstream side of the second head to form the first image on the medium, while discharging ink from the nozzles of the first head and the nozzles on the carrying-directional downstream side of the second head to form the second image.

Description

  The present invention relates to a printing apparatus and a printing method.

  It is known to print a background image with a background color such as white and a color image on a transparent medium (see Patent Document 1). When a color image is viewed from the printing surface side of the medium, first, the background image is printed on the medium, and the color image is printed on the background image. This printing method is called “surface printing”. Conversely, when a color image is viewed from the back side of a transparent medium, the color image is first printed on the medium, and the background image is printed on the color image. This printing method is called “back printing”.

JP 2009-113284 A

There is a demand for improving the visibility by increasing the contrast of a color image by printing the background image darkly.
However, in Patent Document 1, since the length of the nozzle row that discharges white ink is the same as the length of the nozzle row that discharges color ink, there is a limit to increasing the amount of white ink per unit area (white ink). There is a limit to printing with a high duty).

  Similar to printing a background image with a high duty, there is also a demand for printing a clear ink for forming a coating layer with a high duty when, for example, a color image is coated to increase glossiness. As described above, there is a demand not only for printing a background image using white ink but also for printing a high duty image and a low duty image in an overlapping manner.

  On the other hand, in order to increase the degree of freedom of printing, there is also a demand for changing the upper and lower order of images with different duties to be printed in a superimposed manner. For example, when the background image is printed at a high duty, it is desirable that the printing apparatus can cope with both surface printing and back printing, since the degree of freedom of printing can be increased.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a printing apparatus that can change the upper and lower order of images with different duties to be printed in a simple configuration.

  A main invention for achieving the above object includes a transport unit that transports a medium in a transport direction, a carriage that is movable in a moving direction that intersects the transport direction, and a plurality of lines that are provided in the carriage and are arranged in the transport direction. A first head having a nozzle row composed of nozzles, and a second head provided on the carriage side by side with the first head in the movement direction and having a nozzle row longer than the nozzle row of the first head; A head moving mechanism that changes a positional relationship between the first head and the second head in the transport direction, and the nozzle of the first head is upstream of the second head in the transport direction by the head moving mechanism. The ink is discharged from the nozzles of the first head and the nozzles on the upstream side in the transport direction of the second head in a positional relationship so as to be aligned with the nozzles of An operation of forming a second image on the medium by ejecting ink from a nozzle downstream of the second head in the transport direction, and an operation of transporting the medium in the transport direction. By repeating the above, the first printing for forming the second image on the first image, and the nozzles of the first head are aligned with the nozzles on the downstream side in the transport direction of the second head by the head moving mechanism. In such a positional relationship, ink is ejected from the nozzles on the upstream side in the transport direction of the second head to form the second image on the medium, and the nozzles of the first head and the second head By repeating the operation of ejecting ink from a nozzle on the downstream side in the transport direction to form the first image on the medium and the operation of transporting the medium in the transport direction, the second A viable printing apparatus and a second printing for forming the first image onto the image.

  Other features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

1 is an overall configuration block diagram of a printer. 2A is a schematic cross-sectional view of the printer 1, and FIG. 2B is a schematic top view of the printer 1. 3A and 3B are explanatory views of the lower surface of the carriage. 4A and 4B are explanatory diagrams of the positional relationship between the white nozzle row of the first head 41A and the white nozzle row of the second head 41B in the upstream arrangement. FIG. 5A to FIG. 5D are explanatory diagrams of surface printing in the upstream arrangement. 6A to 6D are explanatory diagrams of back printing in the downstream arrangement. FIG. 7A is an explanatory diagram of a first comparative example. FIG. 7B is an explanatory diagram of a second comparative example. 8A and 8B are explanatory views of the lower surface of the carriage according to the second embodiment. FIG. 8A is an explanatory diagram of the upstream arrangement, and FIG. 8B is an explanatory diagram of the downstream arrangement. 9A and 9B are explanatory diagrams of surface printing according to the second embodiment. 10A and 10B are explanatory diagrams of back printing according to the second embodiment. 11A and 11B are explanatory views of the lower surface of the carriage according to the third embodiment. FIG. 11A is an explanatory diagram of the upstream arrangement, and FIG. 11B is an explanatory diagram of the downstream arrangement. 12A and 12B are explanatory diagrams of printing with a fixing material according to the third embodiment. 13A and 13B are explanatory diagrams of glossy printing according to the third embodiment. 14A and 14B are explanatory views of the lower surface of the carriage according to the fourth embodiment. FIG. 14A is an explanatory diagram of the upstream arrangement, and FIG. 14B is an explanatory diagram of the downstream arrangement. FIG. 15A and FIG. 15B are explanatory diagrams of printing of a surface-printed glossy image according to the fourth embodiment. FIGS. 16A and 16B are explanatory diagrams of printing of another front-surface gloss image according to the fourth embodiment. FIG. 17A to FIG. 17C are explanatory diagrams of still another surface printing gloss image printing of the fourth embodiment.

  At least the following matters will become clear from the description of the present specification and the accompanying drawings.

A transport unit that transports a medium in the transport direction, a carriage that is movable in a moving direction that intersects the transport direction, and a first nozzle array that is provided on the carriage and includes a plurality of nozzles arranged in the transport direction. A head, a second head provided on the carriage side by side with the first head in the moving direction, and having a nozzle row longer than the nozzle row of the first head; and the first head and the second head A head moving mechanism that changes a positional relationship in the transport direction, and a nozzle on the upstream side in the transport direction when the nozzle of the first head divides the nozzle row of the second head into two by the head moving mechanism. Ink is discharged from the nozzles of the first head and the nozzles on the upstream side in the transport direction of the second head to form a first on the medium. Forming an image, ejecting ink from nozzles on the downstream side in the transport direction when the nozzle row of the second head is divided into two to form a second image on the medium, and transporting the medium The first printing for forming the second image on the first image by repeating the transporting operation in the direction, and the transporting direction of the second head by moving the nozzles of the first head by the head moving mechanism. The second image is formed on the medium by ejecting ink from the nozzle on the upstream side in the transport direction of the second head in a positional relationship such that it is aligned with the nozzle on the downstream side, and the nozzle of the first head The operation of ejecting ink from the nozzles on the downstream side in the transport direction of the second head to form the first image on the medium and the operation of transporting the medium in the transport direction are repeated. And the second printing and capable of executing printing apparatus will become apparent to form the first image on the second image.
According to such a printing apparatus, it is possible to change the upper and lower order of images with different Duty to be printed in a simple configuration with a simple configuration.

  It is desirable to perform either the first printing or the second printing according to the amount of ink per unit area for forming the first image and the second image. Further, when an image having a larger amount of ink per unit area is formed below, the head moving mechanism causes the nozzles of the first head to be aligned with the nozzles on the upstream side in the transport direction of the second head. In the positional relationship, when the first printing is performed and an image with a larger amount of ink per unit area is formed on the top, the nozzle of the first head is moved by the head moving mechanism to the second head. It is desirable to perform the second printing in a positional relationship that is aligned with the nozzles on the downstream side in the transport direction. This makes it possible to change the top and bottom order of images with different duties to be printed in a simple configuration.

  Preferably, the second head is fixed to the carriage, and the first head is provided so as to be movable along the transport direction by the head moving mechanism. Thereby, the enlargement of an apparatus can be avoided.

  Preferably, the first head forms an image to be painted on a medium, and the second head forms a color image on the medium with color ink. Thereby, even if the positional accuracy of the first head is low, it is allowed.

A transport unit that transports a medium in the transport direction, a carriage that is movable in a moving direction that intersects the transport direction, and a first nozzle array that is provided on the carriage and includes a plurality of nozzles arranged in the transport direction. A head, a second head provided on the carriage side by side with the first head in the moving direction, and having a nozzle row longer than the nozzle row of the first head; and the first head and the second head And a head moving mechanism that changes a positional relationship in the transport direction, wherein the nozzle of the first head divides the nozzle array of the second head into two by the head moving mechanism. The nozzles of the first head and the nozzles of the second head upstream in the transport direction are arranged so as to be aligned with the nozzles of the upstream side of the transport direction. A first image is formed on the medium by discharging ink, and a second image is formed on the medium by discharging ink from the nozzles on the downstream side in the transport direction when the nozzle row of the second head is divided into two. The first head for forming the second image on the first image by repeating the operation for transporting the medium in the transport direction, or the nozzle of the first head by the head moving mechanism. Is aligned with the nozzles on the downstream side in the transport direction of the second head, and ink is ejected from the nozzles on the upstream side in the transport direction of the second head to form the second image on the medium. And an operation of ejecting ink from the nozzles of the first head and the nozzles on the downstream side in the transport direction of the second head to form the first image on the medium; and transporting the medium By repeating the act of conveying in direction, a second printing method for printing to form the first image on the second image becomes clear.
According to such a printing method, it is possible to change the upper and lower order of images with different duties to be printed in a superimposed manner by using a printing apparatus having a simple configuration.

=== First Embodiment ===
<Overall configuration>
FIG. 1 is a block diagram of the overall configuration of the printer 1, FIG. 2A is a schematic cross-sectional view of the printer 1, and FIG. 2B is a schematic top view of the printer 1. Hereinafter, an embodiment will be described with an example of a printing system in which the printing apparatus is an inkjet printer (printer 1) and the printer 1 and the computer 90 are connected.

  The controller 10 is a control unit for controlling the printer 1. The interface unit 11 is for transmitting and receiving data between the computer 90 and the printer 1. The CPU 12 is an arithmetic processing unit for controlling the entire printer 1. The memory 13 is for securing an area for storing a program of the CPU 12, a work area, and the like. The CPU 12 controls each unit by the unit control circuit 14. The detector group 50 monitors the situation in the printer 1, and the controller 10 controls each unit based on the detection result.

  The transport unit 20 transports the medium S from the upstream side to the downstream side in a direction (transport direction) in which the medium S (roll paper or the like) continues. The roll-shaped medium S before printing is supplied to the printing area by the conveyance roller 21 driven by a motor, and then the printed medium S is wound into a roll shape by a winding mechanism. Note that the medium S can be held at a predetermined position by vacuum suction of the medium located in the print area during printing.

  The carriage unit 30 reciprocates the head in the paper width direction. The carriage unit 30 includes a carriage 31 on which the head is mounted and a carriage movement mechanism 32 for reciprocating the carriage.

  The head unit 40 has a head provided on the carriage 31. A plurality of nozzles that are ink discharge portions are provided on the lower surface of the head. In this embodiment, UV ink is ejected from the nozzle. The UV ink is an ink having a property of curing when irradiated with ultraviolet light. In the present embodiment, the head unit 40 includes a head moving mechanism 42 for changing the position of the head in the transport direction.

The irradiation unit 60 is for irradiating the UV ink discharged onto the medium with ultraviolet light. The irradiation unit 60 of the present embodiment includes a provisional curing irradiation unit 61 and a main curing irradiation unit 62.
The provisional curing irradiation unit 61 is provided on the carriage 31 and is movable together with the head. The pre-curing irradiation unit 61 irradiates the UV light with such an intensity that the surface of the UV ink is cured (temporarily cured) so that the UV inks that have landed on the medium do not spread. For example, LED (light emitting diode) etc. are employ | adopted as the irradiation part 61 for temporary hardening. The controller 10 irradiates the ultraviolet light from the temporary curing irradiation unit 61 while moving the carriage 31 to temporarily cure the UV ink on the printing region.
The main curing irradiation unit 62 is provided on the downstream side in the X direction of the printing region, and can irradiate ultraviolet light over the width of the medium. The main curing irradiation unit 62 irradiates UV light having an intensity capable of main curing (completely solidifying) the UV ink on the medium. For example, a UV lamp or the like is employed as the main curing irradiation unit 62. The controller 10 irradiates the ultraviolet light from the main curing irradiation unit 62 while conveying the medium, and cures the image formed by the UV ink.

  When performing printing, the printer 1 alternately repeats an operation (pass) for moving the carriage 31 in the moving direction and a conveying operation. In each pass, the printer 1 ejects ink from the head to form an image on the medium, and irradiates the ultraviolet light from the temporary curing irradiation unit 61 to temporarily cure the image. By repeating the pass and the conveying operation in this manner, it is possible to form an image by joining the medium.

  By repeating the pass and the conveying operation, the image formed in the printing region is gradually conveyed toward the main curing irradiation unit 62. When the image is conveyed to a position facing the main curing irradiation unit 62, ultraviolet light is irradiated from the main curing irradiation unit 62 and the image is main cured.

<Configuration of the underside of the carriage>
3A and 3B are explanatory views of the lower surface of the carriage. In the following description, focusing on the position of the first head 41A in the transport direction, the head arrangement in FIG. 3A is called “upstream arrangement”, and the head arrangement in FIG. 3B is called “downstream arrangement”. First, the configuration of the lower surface of the carriage will be described based on the upstream arrangement in FIG. 3A.

  Two heads (first head 41 </ b> A and second head 42 </ b> B) are provided on the lower surface of the carriage 31. The two heads are provided at different positions in the carriage movement direction. Further, two temporary curing irradiation sections 61 are provided on the carriage 31 so as to sandwich these two heads from the moving direction.

  The first head 41A includes a white nozzle row (W) for discharging white ink. The white nozzle row is a nozzle row for forming a background image. The white nozzle row of the first head 41A is composed of 180 nozzles. The 180 nozzles are arranged along the conveyance direction at a predetermined nozzle pitch, and are arranged at an interval of 1/180 inch in this embodiment. For this reason, the white nozzle row of the first head 41A can form dots in a printing range having a width of 1 inch (L in the drawing) each time the carriage 31 moves once in the movement direction.

  The second head includes five nozzle rows. The five nozzle rows are a black nozzle row (K) for discharging black ink, a cyan nozzle row (C) for discharging cyan ink, and a magenta nozzle row (M) for discharging magenta ink. And a yellow nozzle row (Y) for discharging yellow ink and a white nozzle row (W) for discharging white ink. The black nozzle row, cyan nozzle row, magenta nozzle row, and yellow nozzle row are nozzle rows (color nozzle row group) for forming a color image. The white nozzle row is a nozzle row for forming a background image. The white ink discharged from the white nozzle row of the second head 41B is the same as the white ink discharged from the white nozzle row of the first head 41A.

  Each nozzle row of the second head 41B is composed of 360 nozzles. That is, each nozzle row of the second head 41B is composed of the number of nozzles twice that of the white nozzle row of the first head 41A. The 360 nozzles of each nozzle row of the second head 41B are arranged along the transport direction at a predetermined nozzle pitch, and are arranged at an interval of 1/180 inch in this embodiment. For this reason, each nozzle row can form dots in a printing range having a width of 2 inches (2L in the drawing) each time the carriage 31 moves once in the movement direction.

  In the upstream arrangement, the nozzles of the first head are arranged so as to line up with the nozzles on the upstream side in the transport direction when the nozzle row of the second head is divided into two. For this reason, the print range of the first head and the print range of the second head partially overlap. Specifically, in the case of the upstream arrangement, the print range of the first head overlaps with the half range on the upstream side in the transport direction in the print range of 2 inches wide of the second head. In other words, in the case of upstream arrangement, the print range of the first head overlaps with the print range on the upstream side in the transport direction when the print range of the second head is divided into two.

  Further, in the case of upstream arrangement, the nozzle row of the second head 41B is greater than or equal to the carrying amount of the carrying operation during printing (a carrying operation performed between passes) with respect to the nozzle row of the first head 41A. The length protrudes downstream in the transport direction (projects by a length L). For this reason, in the case of the upstream arrangement, at least one time is required from when the first head 41A performs printing to when the portion of the nozzle protruding from the first head 41A of the second head 41B performs printing in the same region. Is required.

  The two pre-curing irradiation units 61 can irradiate ultraviolet light in an irradiation range having a width of 2 inches (corresponding to 2L) along the conveyance direction. In the case of the upstream arrangement, the first head 41 </ b> A is located on the upstream side in the transport direction in the irradiation range of the pre-curing irradiation unit 61. Accordingly, the pre-curing irradiation unit 61 can irradiate the ultraviolet light at least twice with respect to the ink ejected from the first head 41A arranged upstream.

Next, the configuration of the lower surface of the carriage will be described using FIG. 3B as well.
The first head 41A is movable along the transport direction. The head moving mechanism 42 moves the first head 41 </ b> A along the transport direction in response to an instruction from the controller 10. When the first head 41A moves from the upstream arrangement state (see FIG. 3A) by the distance L to the downstream side in the transport direction, the downstream arrangement state (see FIG. 3B) is obtained. The second head 41B is fixed to the lower surface of the carriage 31.

  In the downstream arrangement, the nozzles of the first head are arranged so as to line up with the nozzles on the downstream side in the transport direction when the nozzle row of the second head is divided into two. For this reason, even in the downstream arrangement, the print range of the first head and the print range of the second head partially overlap. However, in the case of downstream arrangement, the print range of the first head overlaps with the half range on the downstream side in the transport direction in the print range of 2 inches wide of the second head. In other words, in the case of downstream arrangement, the print range of the first head overlaps with the print range on the downstream side in the transport direction when the print range of the second head is divided into two.

  In the case of the downstream arrangement, the nozzle row of the second head 41B protrudes upstream in the carrying direction with a length that is equal to or longer than the carrying amount of the carrying operation during printing with respect to the nozzle row of the first head 41A. (Projected by length L). For this reason, in the case of the downstream arrangement, at least once during the period from when the nozzle of the portion protruding from the first head 41A of the second head 41B performs printing to when the first head 41A performs printing in the same region. Is required.

4A and 4B are explanatory diagrams of the positional relationship between the white nozzle row of the first head 41A and the white nozzle row of the second head 41B in the upstream arrangement.
With the positional relationship as shown in FIG. 4A, it is possible to form white ink dots on the medium with a resolution in the transport direction of 1/720 inch. That is, white ink dots can be formed at a higher resolution than the nozzle pitch. Thereby, when forming a background image, it becomes difficult to produce a space | gap between dots (In addition, a background image is an image filled with white ink.).
With the positional relationship as shown in FIG. 4B, white ink dots can be formed on the same pixel. Thereby, white can be formed deeply in each pixel.
However, since the print ranges of the two white nozzle rows overlap in any of the positional relationships in FIGS. 4A and 4B, the amount of white ink per unit area in the print range can be increased. Therefore, it is possible to print the background image darkly.

<Front-print printing (printing with upstream arrangement)>
The controller 10 causes the position of the first head 41 </ b> A to be arranged on the upstream side when performing surface printing. Surface printing is printing in which a color image is formed on a background image after the background image is formed on a medium.

  FIG. 5A to FIG. 5D are explanatory diagrams of surface printing in the upstream arrangement. In the drawing, the nozzle row for ejecting ink is shown in black, and the region of the pre-curing irradiation section that irradiates ultraviolet light is blacked out.

  First, as shown in FIG. 5A, the controller 10 moves the carriage 31 in the moving direction, and all the nozzles in the white nozzle row of the first head 41A and the upstream side in the transport direction of the white nozzle row in the second head 41B. White ink is ejected from the nozzles (upper half nozzles in FIG. 5A). As a result, a white background image having a width in the transport direction of L (1 inch) is formed on the medium. The operation of moving the carriage 31 in the movement direction may be referred to as “pass”. In addition, the first pass may be referred to as “pass 1” (that is, FIG. 5A is a diagram showing the state of pass 1).

  In pass 1, the controller 10 irradiates ultraviolet light from the pre-curing irradiation unit 61 on the upstream side in the moving direction of the carriage 31 (left side in FIG. 5A). As a result, the white ink immediately after landing on the medium is irradiated with ultraviolet light, and the surface of the ink is cured (temporarily cured). By pre-curing the white ink, bleeding between the inks is suppressed even if the color ink is subsequently applied. Since it is not necessary to irradiate the region where the background image is not formed with the ultraviolet light, the temporary curing irradiation unit 61 irradiates the ultraviolet light from the region where the position of the first head 41A in the transport direction is the same as the white nozzle row. The ultraviolet light is not irradiated from the region downstream in the transport direction (the ultraviolet light is irradiated from the upper half region of the temporary curing irradiation unit 61 on the left side of FIG. 5A).

  Next, as illustrated in FIG. 5B, the controller 10 transports the medium in the transport direction. The carry amount at this time is L (1 inch). As a result, the area where the background image is formed in FIG. 5A is located downstream in the transport direction, and the unprinted portion of the medium is supplied to the print area (background image print area) of the first head 41A in pass 2. .

  Then, as illustrated in FIG. 5C, the controller 10 causes the pass 2 to be performed. Also in pass 2, the controller 10 moves the carriage 31 in the movement direction, and all the nozzles in the white nozzle row of the first head 41A and the nozzles on the upstream side in the transport direction of the white nozzle row of the second head 41B (see FIG. White ink is ejected from the upper half nozzle in 5A). As a result, a white background image having a width in the transport direction of L (1 inch) is formed on the medium.

  Further, in pass 2, as shown in FIG. 5C, the controller 10 causes the nozzles (K, C, M, Y) in the color nozzle row group of the second head 41B to be downstream in the transport direction (FIG. 5C). The color ink is ejected from the lower half nozzle in FIG. As a result, a color image having a width L (1 inch) in the conveyance direction is formed on the medium on the background image formed in pass 1.

  Further, in pass 2, the controller 10 irradiates ultraviolet light from the pre-curing irradiation unit 61 on the upstream side in the movement direction of the carriage 31 (right side in FIG. 5C). In pass 2, the pre-curing irradiation unit 61 irradiates not only the background image but also the color image with ultraviolet light, and therefore irradiates ultraviolet light from all regions. In other words, the pre-curing irradiation unit 61 irradiates ultraviolet light from a region where the printing region in the pass 2 and the position in the transport direction are the same.

  In pass 2, the temporary curing irradiation unit 61 on the downstream side in the movement direction of the carriage 31 (left side in FIG. 5C) may irradiate ultraviolet light. In this way, the background image can be sufficiently temporarily cured before the color image is formed, and bleeding between the color ink and the white ink can be particularly suppressed.

  After pass 2, as shown in FIG. 5D, the controller 10 transports the medium in the transport direction. The carry amount at this time is L (1 inch). As a result, the area where the background image is formed in FIG. 5C is positioned in the color image print area in pass 3, and the unprinted portion of the medium is supplied to the background image print area in pass 3.

  Then, after FIG. 5D, the controller 10 alternately repeats the operation (pass) for moving the carriage 31 in the movement direction and the conveyance operation. In each pass, as shown in FIG. 5C, the controller 10 sends white ink from all the nozzles in the white nozzle row of the first head 41A and the nozzles on the upstream side in the transport direction of the white nozzle row of the second head 41B. In addition, the color ink is discharged from the nozzles on the downstream side in the transport direction of each nozzle row (K, C, M, Y) of the color nozzle row group of the second head 41B. In other words, in each pass, the controller 10 forms a background image in the upstream half area of the printing area having a width in the transport direction of 2L, and forms a color image in the downstream half area. In each pass, the controller 10 irradiates ultraviolet light from the temporary curing irradiation unit 61 on the upstream side in the moving direction of the carriage 31 to temporarily cure the background image and the color image. By repeating such a pass and the transport operation of the transport amount of L, surface printing that prints a color image on the background image can be performed.

  According to the present embodiment, a background image is formed using two white nozzle rows (a white nozzle row of the first head 41A and a nozzle on the upstream side in the transport direction of the white nozzle row of the second head 41B). Therefore, the amount of white ink per unit area can be increased (white ink can be printed at a high duty). Thereby, the background image can be printed darkly, and the contrast of the color image can be increased to improve the visibility.

<Backside printing (printing at downstream side)>
The controller 10 causes the position of the first head 41 </ b> A to be arranged downstream when performing reverse printing. Back-printing is printing in which a color image is formed on a medium and then a background image is formed on the color image. The reverse printing is mainly performed on a transparent medium, and the color image of the printed material by the reverse printing is seen through the transparent medium.

  6A to 6D are explanatory diagrams of back printing in the downstream arrangement. In the drawing, the nozzle row for ejecting ink is shown in black, and the region of the pre-curing irradiation section that irradiates ultraviolet light is blacked out. Compared with the above-described front printing (FIGS. 5A to 5D), the position of the first head 41A in the transport direction is different. In addition, the area of the nozzle that ejects the ink of the second head 41B is different from the surface printing.

  The controller 10 alternately repeats the operation (pass) for moving the carriage 31 in the movement direction and the conveying operation. In each pass, as shown in FIG. 6C, the controller 10 moves all the nozzles in the white nozzle row of the first head 41A and the downstream side in the transport direction of the white nozzle row of the second head 41B (lower side in the figure). The white ink is ejected from half of the nozzles, and the color ink is ejected from the nozzles on the upstream side in the transport direction of each nozzle row (K, C, M, Y) of the color nozzle row group of the second head 41B. In other words, in each pass, the controller 10 forms a color image in the upstream half area of the printing area having a width in the transport direction of 2L, and forms a background image in the downstream half area. In each pass, the controller 10 irradiates ultraviolet light from the temporary curing irradiation unit 61 on the upstream side in the moving direction of the carriage 31 to temporarily cure the background image and the color image. By repeating such a pass and the transport operation of the transport amount of L, it is possible to perform reverse printing that prints a background image on a color image.

  According to this embodiment, a background image is formed using two white nozzle rows (a white nozzle row of the first head 41A and a nozzle on the downstream side in the transport direction of the white nozzle row of the second head 41B). Therefore, the amount of white ink per unit area can be increased (white ink can be printed at a high duty). Thereby, the background image can be printed darkly, and the contrast of the color image can be increased to improve the visibility.

  As described above, the controller 10 places the first head 41 on the upstream side when a dark background image to be printed is formed below the color image. Conversely, when a background image to be printed dark is formed on a color image, the first head 41 is disposed downstream.

<Comparative example>
FIG. 7A is an explanatory diagram of a first comparative example. In the figure, the nozzle rows for ejecting ink are shown in black. By repeating the pass of ejecting ink from the nozzles in the blacked-out area and the transport operation of the transport amount of L, surface printing that prints a color image on the background image can also be performed.

  However, unlike the present embodiment, the first comparative example is not provided with a configuration corresponding to the first head. For this reason, when forming a background image, the amount of white ink per unit area cannot be increased as in this embodiment. For this reason, in the first comparative example, the background image cannot be printed as darkly as the present embodiment, and the contrast of the color image cannot be increased.

  FIG. 7B is an explanatory diagram of a second comparative example. Compared to the first embodiment, in the second comparative example, the length of the white nozzle row of the first head is 2L, and the first head is fixed. Also in the second comparative example, surface printing is performed in which a color image is printed on a background image by repeating a pass for ejecting ink from the nozzles in the blacked-out area and a transport operation of L transport amount. be able to. It is also possible to print the background image darkly.

  However, in the second comparative example, the number of nozzles that do not eject white ink increases compared to the first embodiment. The number of nozzles that do not eject white ink is 180 in the first embodiment, whereas it is 360 in the second comparative example. In white ink, the pigment is more likely to settle than in color ink, and the nozzles are likely to clog unless ink is ejected. For this reason, in the 2nd comparative example, the probability that a nozzle will be clogged will become high compared with a 1st embodiment.

  In the second comparative example, the white nozzle row of the first head needs to be 2 inches, which increases the cost of the head. On the other hand, in the first embodiment, since the white nozzle row of the first head is 1 inch, the cost of the head can be reduced.

  Note that, according to the present embodiment, the head moving mechanism 42 for moving the first head along the transport direction is required instead of the white nozzle row of the first head being 1 inch. However, since the background image is an image that is simply filled with white ink, the positional accuracy after the movement of the first head is acceptable even if it is low. For this reason, the head moving mechanism 42 can be configured with an inexpensive one.

=== Second Embodiment ===
8A and 8B are explanatory views of the lower surface of the carriage according to the second embodiment. FIG. 8A is an explanatory diagram of the upstream arrangement, and FIG. 8B is an explanatory diagram of the downstream arrangement.
In the second embodiment, the configuration of the first head 41A is different from that of the first embodiment. The first head 41A of the first embodiment includes only a white nozzle row, whereas the first head 41A of the second embodiment also includes a color nozzle row group.

  Next, front printing and back printing according to the second embodiment will be described. If the first embodiment is understood, the operation of the pre-curing irradiation unit 61 according to the second embodiment can also be understood, and the description thereof is omitted here.

<Front-print printing>
9A and 9B are explanatory diagrams of surface printing according to the second embodiment. In the figure, the nozzle rows for ejecting ink are shown in black. By repeating the pass of ejecting ink from the nozzles in the blacked-out area and the transport operation of the transport amount of L, it is possible to perform surface printing that prints a color image on the background image.

  When performing surface printing, the second head 41B discharges the white ink from the nozzle (upper half nozzle in the figure) on the upstream side in the transport direction of the white nozzle row in both of FIGS. 9A and 9B. Color ink is ejected from nozzles (lower half nozzles in the drawing) on the downstream side in the transport direction of each nozzle row (K, C, M, Y) of the color nozzle row group.

  On the other hand, the arrangement of the first head 41A differs depending on which of the background image and the color image is printed darkly. If ink is ejected as shown in FIG. 9A, a surface printing of a dark background image can be performed as in the first embodiment. On the other hand, if ink is ejected as shown in FIG. 9B, it is possible to perform surface printing of a dark color image. In other words, the controller 10 places the first head 41A in the upstream arrangement when performing the dark surface printing of the background image, and places the first head 41A in the downstream arrangement when performing the dark surface printing of the color image. To do.

<Backprint printing>
10A and 10B are explanatory diagrams of back printing according to the second embodiment. In the figure, the nozzle rows for ejecting ink are shown in black. By repeating the pass of ejecting ink from the nozzles in the blacked area and the transport operation of the transport amount of L, it is possible to perform reverse printing that prints the background image on the color image.

  In the case of performing reverse printing, the second head 41B is configured such that the nozzle on the upstream side in the transport direction of each nozzle row (K, C, M, Y) of the color nozzle row group in both FIG. 9A and FIG. 9B. In this case, the color ink is discharged from the upper half nozzle), and the white ink is discharged from the nozzle (lower half nozzle in the drawing) on the downstream side in the transport direction of the white nozzle row.

  Similar to the surface printing, the first head 41A has a different arrangement depending on which of the background image and the color image is printed darkly. If ink is ejected as shown in FIG. 10A, the back printing of a dark color image can be performed. On the other hand, if ink is ejected as shown in FIG. 10B, it is possible to perform reverse printing of a dark background image. In other words, the controller 10 places the first head 41A in the upstream arrangement when performing a dark back printing of a color image, and places the first head 41A in the downstream arrangement when performing a dark back printing of a background image. To do.

  As described above, the controller 10 arranges the first head 41 so that the first head 41 </ b> A can form a darker one of the background image and the color image to be printed. Further, the controller 10 places the first head 41 on the upstream side when the image to be printed darker is on the lower side. On the contrary, when the image to be printed darker is on the upper side, the first head 41 is arranged downstream.

=== Third Embodiment ===
11A and 11B are explanatory views of the lower surface of the carriage according to the third embodiment. FIG. 11A is an explanatory diagram of the upstream arrangement, and FIG. 11B is an explanatory diagram of the downstream arrangement.
Compared to the first embodiment of FIG. 3, the first head 41A and the second head 41B of the third embodiment are each provided with a clear ink nozzle row that discharges UV curable clear ink instead of the white nozzle row. ing.

The clear ink ejected by the clear ink nozzle array has a function as a fixing material for improving fixability and a function as a glossing material for improving glossiness.
When clear ink is used as a fixing material, a clear image is applied to a medium to form a transparent image on the medium, and then a color image is formed thereon. Thereby, the transparent image under the color image becomes a fixing layer, and the fixability of the color image to the medium is improved. In the following description, such printing is referred to as “printing with a fixing material”.
When clear ink is used as a glossy material, a color image is formed on a medium, and then a clear image is applied thereon to form a transparent image. Thereby, the transparent image on the color image becomes a coating layer, and the glossiness of the color image is improved. In the following description, such printing is referred to as “glossy printing”.

  Note that the transparent image is a solid image in both the case of printing with a fixing material and the case of glossy printing.

<Printing with fixing material>
12A and 12B are explanatory diagrams of printing with a fixing material according to the third embodiment. In the figure, the nozzle rows for ejecting ink are shown in black. It is possible to perform printing with a fixing material for printing a color image on a transparent image (fixing layer) by repeating a pass for ejecting ink from a nozzle in a black-painted region and a transport operation of L transport amount. it can.

  When performing printing with a fixing material, the second head 41B discharges clear ink from the nozzle (upper half nozzle in the figure) on the upstream side in the transport direction of the clear ink nozzle row in both FIGS. 12A and 12B. At the same time, the color ink is ejected from the nozzles (lower half nozzles in the drawing) on the downstream side in the transport direction of each nozzle row (K, C, M, Y) of the color nozzle row group.

  On the other hand, the arrangement of the first head 41A differs depending on which of the transparent image and the color image is printed darkly. If ink is ejected as shown in FIG. 12A, a dark transparent image (thick fixing layer) can be printed with a fixing material. On the other hand, if ink is ejected as shown in FIG. 12B, it is possible to perform printing with a fixing material for a dark color image. In other words, the controller 10 places the first head 41A in the upstream side when printing with a fixing material with a thicker fixing layer, and the first head 41A when printing with a fixing material having a dark color image. Arrange downstream.

<Glossy printing>
13A and 13B are explanatory diagrams of glossy printing according to the third embodiment. In the figure, the nozzle rows for ejecting ink are shown in black. Glossy printing for printing a transparent image (coating layer) on a color image can be performed by repeating the pass of ejecting ink from the nozzles in the blacked area and the transport operation of the transport amount of L.

  In the case of performing glossy printing, the second head 41B is configured such that the nozzle on the upstream side in the transport direction of each nozzle row (K, C, M, Y) of the color nozzle row group in both FIG. 13A and FIG. 13B. The color ink is ejected from the upper half nozzle), and the clear ink is ejected from the nozzle (lower half nozzle in the figure) on the downstream side in the transport direction of the clear ink nozzle row.

  Similar to the printing with the fixing material, the first head 41A has a different arrangement depending on which of the transparent image and the color image is printed darkly. If ink is ejected as shown in FIG. 13A, glossy printing of a dark color image can be performed. On the other hand, if ink is ejected as shown in FIG. 13B, it is possible to perform glossy printing of a dark transparent image. In other words, the controller 10 places the first head 41A in the upstream side when performing dark gloss printing of a color image, and places the first head 41A in the downstream side when performing gloss printing with a thick coating layer. To do.

  As described above, the controller 10 arranges the first head 41 so that the first head 41 </ b> A can form a darker one of the transparent image and the color image to be printed. Further, the controller 10 places the first head 41 on the upstream side when the image to be printed darker is on the lower side. On the contrary, when the image to be printed darker is on the upper side, the first head 41 is arranged downstream.

=== Fourth Embodiment ===
14A and 14B are explanatory views of the lower surface of the carriage according to the fourth embodiment. FIG. 14A is an explanatory diagram of the upstream arrangement, and FIG. 14B is an explanatory diagram of the downstream arrangement. In the present embodiment, each head includes a color nozzle row group, a white nozzle row, and a clear ink nozzle row.

  In the printing method described below, a front-surface gloss image is printed. The surface-printed glossy image is an image obtained by superimposing a background image, a color image, and a transparent image in order. In other words, the surface gloss image is an image in which a coating layer (transparent image) is formed on the surface printed image (background image and color image). In other words, it is an image in which a glossy image (color image and transparent image) is formed on the background image.

  FIG. 15A and FIG. 15B are explanatory diagrams of printing of a surface-printed glossy image according to the fourth embodiment. In the figure, the nozzle rows for ejecting ink are shown in black. By repeating the pass of ejecting ink from the nozzles in the blacked area and the transport operation of the transport amount of L / 2, it is possible to print the surface gloss image. In the embodiments described so far, the carry amount is L, but in this embodiment, the carry amount is half (L / 2).

  In both of FIGS. 15A and 15B, the second head 41B has an area (background image) having a width L / 2 from a nozzle on the upstream side of the white nozzle row in the transport direction (a nozzle on the upper quarter in the drawing). A white ink is ejected to the printing area), and an area having a width L / 2 adjacent to the background image printing area (color image printing area) in each nozzle row (K, C, M, Y) of the color nozzle row group Color ink is ejected from the nozzles. Further, clear ink is ejected from the nozzles on the downstream side in the transport direction of the clear ink nozzle row (lower half nozzles in the figure) to the region of width L. The clear ink is applied to the region of width L / 2 in two passes.

  The arrangement of the first head 41A differs depending on whether the image to be printed by front printing (background image or color image) or the transparent image is printed darkly. If ink is ejected as shown in FIG. 15A, the image to be printed on the surface can be darkened. On the other hand, if ink is ejected as shown in FIG. 15B, a transparent image can be printed thickly. In other words, the controller 10 places the first head 41A in the upstream side when printing images (background image and color image) to be printed on the front side are dark, and moves the first head 41A when printing thick images on the transparent image. Arrange downstream.

  FIGS. 16A and 16B are explanatory diagrams of printing of another front-surface gloss image according to the fourth embodiment. In the figure, the nozzle rows for ejecting ink are shown in black. By repeating the pass of ejecting ink from the nozzles in the blacked area and the transport operation of the transport amount of L / 2, it is possible to print the surface gloss image. In the above-described printing of FIGS. 15A and 15B, the clear ink is applied in two passes, but in the printing of FIGS. 16A and 16B, the white ink is applied in two passes.

  In both of FIG. 16A and FIG. 16B, the second head 41B applies white ink from the nozzle (upper half nozzle in the drawing) on the upstream side in the conveyance direction of the white nozzle row to the region of width L (background image printing region). In addition to discharging, color ink is discharged from the nozzles in the area (color image printing area) having a width L / 2 adjacent to the background image printing area in each nozzle array (K, C, M, Y) of the color nozzle array group. To do. Further, the clear ink is ejected from the 1/4 nozzle on the downstream side in the transport direction of the clear ink nozzle row (the lower 1/4 nozzle in the drawing) to the region of the width L / 2.

  The arrangement of the first head 41A differs depending on whether the background image or the glossy image (color image or transparent image) is printed darkly. If ink is ejected as shown in FIG. 16A, the background image can be darkened. On the other hand, if ink is ejected as shown in FIG. 16B, a glossy image can be printed thick. In other words, the controller 10 places the first head 41A upstream when the background image is printed dark, and places the first head 41A downstream when the thick image is printed.

FIG. 17A to FIG. 17C are explanatory diagrams of still another surface printing gloss image printing of the fourth embodiment. In the figure, the nozzle rows for ejecting ink are shown in black. By repeating the pass of ejecting ink from the nozzles in the blacked-out area and the transport operation of the transport amount of (2/3) × L, it is possible to print the surface gloss image.
In the printing of the above-described glossy surface print image, the clear ink or the white ink is applied in two passes, but here the clear ink and the white ink are applied in one pass. Further, in the printing of the above-described glossy surface print image, the carry amount is L / 2, but here the carry amount is (2/3) × L.

  In any of FIGS. 17A to 17C, the second head 41B has a width (2/3) × L from the nozzle on the upstream side 1/3 of the white nozzle row (the upper third nozzle in the drawing). White ink is ejected to the area (background image print area), and the nozzles (K, C, M, Y) of the color nozzle array group at the center 1/3 nozzle (width adjacent to the background image print area (2 / 3) Nozzle in the area of × L), discharges the color ink, and the area of width L / 2 from the 1/3 nozzle (lower 1/3 nozzle in the drawing) downstream in the transport direction of the clear ink nozzle row Discharge clear ink.

  The arrangement of the first head 41A differs depending on whether the background image, the color image, or the transparent image is printed darkly. When the ink is ejected as shown in FIG. 17A, the background image can be darkened, when the ink is ejected as shown in FIG. 17B, the color image can be printed darkly, and when the ink is ejected as shown in FIG. 17C, the transparent image becomes thicker. Can print. In other words, the controller 10 arranges the first head 41A upstream when the background image is printed dark, and arranges the first head 41A at the center as shown in FIG. 17B when printing the color image dark. When the transparent image is printed thickly, the first head 41A is disposed downstream.

  In the above description, the background image, the color image, and the transparent image are printed in order, but the present invention is not limited to this. For example, a transparent image may be formed at the bottom as a fixing layer, and a background image and a color image may be formed on the transparent image. Further, the background image and the color image may be printed on the back instead of being printed on the surface.

=== Summary ===
Each of the printers 1 described above includes the transport unit 20, the carriage 31, the first head 41 </ b> A, the second head 41 </ b> B, and the head moving mechanism 42. In the head moving mechanism 42, the first head 41A has a nozzle row with a length L, and the second head 41A has a nozzle row with a length 2L (FIGS. 3A, 3B, 8A, FIG. 8B, FIG. 11A, FIG. 11B, FIG. 14A and FIG. 14B). The head moving mechanism 42 can move the first head 41A in the transport direction so that the first head 41A can be arranged upstream or downstream.
With such a configuration, the printer 1 can perform at least two types of printing. First, the first head 41A is arranged upstream, and ink is ejected from the nozzles of the first head 41A and the nozzles upstream of the second head 41B in the transport direction to form a first image, and the second In this printing, a second image is formed on the first image by alternately repeating a pass for forming the second image by ejecting ink from the nozzles on the downstream side in the transport direction of the head 41B and a transport operation. Second, the first head 41A is disposed downstream, and ink is ejected from the nozzles upstream of the second head 41B in the transport direction to form a second image, and the nozzles of the first head 41A and the second head In this printing, the first image is formed on the second image by alternately repeating the pass for forming the first image by ejecting ink from the nozzles 41B on the downstream side in the transport direction and the transport operation.
For example, in the first embodiment, the color image is formed on the background image by forming the background image as the first image and the color image as the second image by arranging the first head 41A upstream. Surface printing is performed (see FIG. 5). In the first embodiment, the first head 41A is disposed downstream, and back printing is performed to form a background image on the color image (see FIG. 6). Thereby, in any case, the background image can be printed darkly.

  In the second embodiment, it is also possible to form a background image as the first image and a color image as the second image (see FIGS. 9A and 9B), and form a color image as the first image. It is also possible to form a background image as the second image (see FIGS. 10A and 10B). In the third embodiment, a transparent image (or color image) is formed as the first image, and a color image (or transparent image) is formed as the second image (FIGS. 12A, 12B, 13A, and 13B). . In the fourth embodiment, a front print image (background image and color image) is formed as the first image, and a transparent image is formed as the second image (FIGS. 15A and 15B). In the fourth embodiment, a background image can be formed as the first image, and a glossy image (color image and transparent image) can be formed as the second image.

  Further, the controller 10 described above performs upstream arrangement or downstream arrangement printing according to the amount of ink per unit area of an image to be printed in an overlapping manner. For example, if the lower image is printed darker (if the lower printed image has more ink per unit area than the upper printed image), the controller 10 is arranged upstream. To print. In addition, when the upper image is printed darker, the controller 10 performs printing in a downstream arrangement. For example, in the first embodiment, when the background image for front printing is printed darkly, printing is performed with the first head 41A disposed upstream. Conversely, when the background image of back printing is printed darkly, printing is performed with the first head 41A disposed downstream.

  In the above-described embodiment, the second head 41B having a long nozzle row is fixed to the carriage, and the first head 41A is provided to be movable in the transport direction by the head moving mechanism. Thereby, the size of the carriage 31 can be made as small as possible. If the first head 41A is fixed to the carriage 31 and the second head 41B is movably provided, the second head 41B is longer in the transport direction than the first head 41A, so the carriage 31 needs to be enlarged. Will occur, and the device will become larger.

  In a configuration in which the first head 41A is movable while the second head 41B is fixed, a background image, a transparent image, or the like is formed using the first head 41A, and a color image is formed using the second head 41B. It is desirable to form using. This is because an image to be filled is not conspicuous even if the dot landing position is deviated, and is acceptable even if the position accuracy of the first head 41A is low.

=== Others ===
The above embodiment is mainly described for a printer, but it goes without saying that the disclosure includes a printing apparatus, a printing method, a program, a storage medium storing the program, and the like.

  The above-described embodiments are for facilitating understanding of the present invention, and are not intended to limit the present invention. The present invention can be changed and improved without departing from the gist thereof, and it is needless to say that the present invention includes equivalents thereof. In particular, the embodiments described below are also included in the present invention.

<About nozzle>
In the above-described embodiment, ink is ejected using a piezoelectric element. However, the method for discharging the liquid is not limited to this. For example, other methods such as a method of generating bubbles in the nozzle by heat may be used.

<About ink>
In the above-described embodiment, a UV ink having a property of being cured when irradiated with ultraviolet rays has been used. However, UV ink is not necessarily used. If the ink is not UV ink, the printer 1 may not include the irradiation unit 60.

1 printer, 10 controller,
11 Interface unit, 12 CPU,
13 memory, 14 unit control circuit,
20 transport units, 21 transport rollers,
30 Carriage unit, 31 Carriage,
40 head units, 41 heads,
41A first head, 41B second head,
42 head moving mechanism,
50 detector groups, 60 irradiation units,
61 Irradiation unit for temporary curing, 62 Irradiation unit for main curing

Claims (6)

A transport unit for transporting the medium in the transport direction;
A carriage movable in a moving direction intersecting the conveying direction;
A first head having a nozzle row provided on the carriage and composed of a plurality of nozzles arranged in the transport direction;
A second head provided on the carriage side by side with the first head in the moving direction and having a nozzle row longer than the nozzle row of the first head;
A head moving mechanism that changes a positional relationship between the first head and the second head in the transport direction;
With
The nozzles of the first head and the nozzles of the first head are aligned with the nozzles on the upstream side in the transport direction when the nozzle row of the second head is divided into two by the head moving mechanism. From the nozzles on the upstream side in the transport direction of the second head, ink is ejected to form a first image on the medium, and from the nozzles on the downstream side in the transport direction when the nozzle row of the second head is divided into two First printing that forms the second image on the first image by repeating the operation of ejecting ink to form the second image on the medium and the operation of conveying the medium in the conveying direction. When,
The head moving mechanism causes the nozzles of the first head to be aligned with the nozzles on the downstream side in the transport direction of the second head, and ejects ink from the nozzles on the upstream side in the transport direction of the second head. The first image is formed on the medium, and the second image is formed on the medium by ejecting ink from the nozzles of the first head and the nozzles on the downstream side in the transport direction of the second head. And a printing apparatus capable of executing the second printing for forming the second image on the first image by repeating the operation of conveying the medium in the conveyance direction. The printing apparatus according to claim 1,
A printing apparatus that performs either the first printing or the second printing according to an ink amount per unit area for forming the first image and the second image. The printing apparatus according to claim 1 or 2,
When the first image has a larger amount of ink per unit area than the second image, the head moving mechanism causes the nozzles of the first head and the nozzles on the upstream side in the transport direction of the second head. The first printing is performed in a positional relationship such that
When the amount of ink per unit area is greater in the second image than in the first image, the head moving mechanism causes the nozzles of the first head and the nozzles on the downstream side in the transport direction of the second head. A printing apparatus, wherein the second printing is performed in a positional relationship such that they are arranged side by side. The printing apparatus according to any one of claims 1 to 3,
The second head is fixed to the carriage;
The printing apparatus according to claim 1, wherein the first head is provided to be movable along the transport direction by the head moving mechanism. The printing apparatus according to claim 4,
The first head forms an image to be filled on a medium,
The printing apparatus, wherein the second head forms a color image on the medium with color ink. A transport unit for transporting the medium in the transport direction;
A carriage movable in a moving direction intersecting the conveying direction;
A first head having a nozzle row provided on the carriage and composed of a plurality of nozzles arranged in the transport direction;
A second head provided on the carriage side by side with the first head in the moving direction and having a nozzle row longer than the nozzle row of the first head;
A head moving mechanism that changes a positional relationship between the first head and the second head in the transport direction;
A printing method for a printing apparatus comprising:
The nozzles of the first head and the nozzles of the first head are aligned with the nozzles on the upstream side in the transport direction when the nozzle row of the second head is divided into two by the head moving mechanism. From the nozzles on the upstream side in the transport direction of the second head, ink is ejected to form a first image on the medium, and from the nozzles on the downstream side in the transport direction when the nozzle row of the second head is divided into two First printing that forms the second image on the first image by repeating the operation of ejecting ink to form the second image on the medium and the operation of conveying the medium in the conveying direction. Or in a positional relationship such that the nozzles of the first head are aligned with the nozzles on the downstream side of the second head in the transport direction by the head moving mechanism. The medium is formed by ejecting ink from nozzles on the flow side to form the first image on the medium, and ejecting ink from nozzles of the first head and nozzles on the downstream side in the transport direction of the second head. A printing method for performing second printing for forming the second image on the first image by repeating the operation of forming the second image and the operation of transporting the medium in the transport direction.