JP2013091200A - Printer, printing method and printed material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress clogging of a nozzle.SOLUTION: This printer includes: a transport unit transporting a medium in a transporting direction; a head which is a head movable along a moving direction crossing to a transporting direction and includes a first nozzle array wherein nozzles for discharging inks for forming an color image are disposed in the transporting direction and a second nozzle array wherein nozzles for discharging inks for forming a background image are disposed in the transporting direction, with the first nozzle array and the second nozzle array arranged side by side in a moving direction; and a control part which performs a transporting operation for transporting the medium to the transport unit and a discharging operation for discharging the inks from the head moving in the moving direction. The control part prints a front printing image and a back printing image on the medium arranging in the moving direction when receiving both of a printing instruction of the front printing image for forming the color image on the background image and a printing instruction of the back printing image for forming the background image on the color image.

Description

  The present invention relates to a printing apparatus, a printing method, and a printed matter.

  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

A color nozzle array that ejects ink for forming a color image and a background nozzle array that ejects ink for forming a background image may be arranged side by side in the moving direction of the head. When surface printing is performed using the head in which the color nozzle row and the background nozzle row are arranged in this way, a specific nozzle becomes an unused nozzle. Similarly, when the back printing is performed using the head in which the color nozzle row and the background nozzle row are arranged in this manner, the specific nozzle becomes an unused nozzle.
For this reason, when one of the surface printing and the back printing is continuously performed for a long time, the ink components of the unused nozzles are thickened or solidified by evaporation, and the nozzles are easily clogged.

  An object of this invention is to suppress clogging of a nozzle.

  A main invention for achieving the above object is a transport unit that transports a medium in a transport direction, and a head that is movable along a moving direction that intersects the transport direction, and that includes ink for forming a color image. The color nozzle row and the background nozzle, wherein the nozzle for discharging has a color nozzle row arranged in the carrying direction, and the nozzle for discharging ink for forming a background image has a background nozzle row arranged in the carrying direction. A head in which a row is arranged in the moving direction; a control unit that performs a transport operation that transports the medium to the transport unit; and a discharge operation that ejects the ink to the head that moves in the travel direction; The control unit includes a print instruction for a front print image for forming the color image on the background image, and a front instruction on the color image. A printing apparatus that prints on the medium by arranging the front print image and the back print image in the moving direction when receiving both print instructions of the back print image forming the background image is there.

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

FIG. 1 is a block diagram of the overall configuration of the printer 1. 2A is a schematic cross-sectional view of the printer 1, and FIG. 2B is a schematic top view of the printer 1. FIG. 3 is an explanatory diagram of the lower surface of the carriage. FIG. 4A is an explanatory diagram of a front print image. FIG. 4B is an explanatory diagram of a back print image. FIG. 5A is an explanatory diagram of surface printing. FIG. 5B is an explanatory diagram of reverse printing. FIG. 6A is an explanatory diagram of allocation of a front print image and a back print image. FIG. 6B is an explanatory diagram of the nozzles used in a certain pass. FIG. 7A is an explanatory diagram of a printed matter according to the second embodiment. FIG. 7B is an explanatory diagram of nozzles used in a certain pass according to the second embodiment. FIG. 8A is an explanatory diagram of a printed matter according to a modification of the second embodiment. FIG. 8B is an explanatory diagram of a nozzle used in a certain pass according to a modification of the second embodiment. FIG. 9A is an explanatory diagram of a printed matter according to the third embodiment. FIG. 9B is an explanatory diagram of a nozzle test pattern according to the third embodiment. FIG. 10 is an explanatory diagram of normal interlaced printing. FIG. 11 is an explanatory diagram of surface printing by interlace printing. 12A and 12B are explanatory diagrams of a printing method according to the fifth 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 a transport direction, and a head that is movable along a moving direction that intersects the transport direction, and color nozzles that eject ink for forming a color image are arranged in the transport direction And a background nozzle row in which nozzles for ejecting ink for forming a background image are arranged in the carrying direction, and the color nozzle row and the background nozzle row are arranged in the moving direction. And a control unit for performing a transport operation for transporting the medium to the transport unit and a discharge operation for ejecting the ink to the head moving in the moving direction, The control unit prints a front print image for forming the color image on the background image, and prints a back print image for forming the background image on the color image. When subjected to both directions, the printing apparatus characterized by printing on the medium side by side the back surface printing image and the table surface printing image in the moving direction is apparent.
According to such a printing apparatus, nozzle clogging can be suppressed.

  The control unit forcibly continuously ejects the ink from the nozzles when the head passes between a region where the front-printed print image is formed and a region where the back-printed print image is formed. It is desirable. Thereby, even if the thickening or solidification of the ink progresses in the nozzle during one of the front printing and the back printing, the clogging of the nozzle during the other printing can be suppressed.

  The control unit forcibly continuously ejects the ink from the nozzles when the head passes between a region where the front-printed print image is formed and a region where the back-printed print image is formed. Accordingly, it is desirable to form a pattern for inspecting clogging of the nozzle. Thereby, clogging of the nozzle can be inspected.

  It is preferable that the apparatus further includes a cutter unit for cutting the medium, and the cutter unit cuts the medium so that the pattern is attached to at least one of the front-printed print image and the back-printed print image. Thereby, quality evaluation of a printed image can be performed using the pattern.

A transport unit that transports a medium in a transport direction, and a head that is movable in a moving direction that intersects the transport direction, and nozzles that eject ink for forming a color image are arranged in the transport direction. A nozzle row and a second nozzle row in which nozzles for ejecting ink for forming a background image are arranged in the transport direction, and the first nozzle row and the second nozzle row are arranged in the movement direction. And a discharge operation for discharging the ink to the head moving in the moving direction, wherein the background image is printed on the background image. When receiving both a print instruction for a front print image for forming the color image thereon and a print instruction for a back print image for forming the background image on the color image, the front print Printing wherein the printing on the medium side by side the back surface printing image and printing the image in the moving direction is apparent.
According to such a printing method, clogging of the nozzle can be suppressed.

  Moreover, the printed matter printed by such a printing method becomes clear. According to such a printed matter, since the clogging of the nozzles is suppressed and printing is performed, a high quality image is obtained.

=== First Embodiment ===
<Basic printer 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.

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.

  The cutter unit 70 is for cutting a predetermined part of the medium on which the image is formed. The cutter unit 70 includes a cutter (metal blade or laser), a moving mechanism that moves the cutter in the paper width direction, and the like.

  When performing printing, the controller 10 of the printer 1 repeatedly performs an operation (pass) in which the carriage 31 is moved in the moving direction to eject ink from the head and a transport operation in which the transport unit 20 transports the medium. 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.

  Further, the transport operation is repeated, so that the main cured image is transported toward the cutter unit 70. The cutter unit 70 cuts (cuts) the medium at a position to be cut. For example, in an embodiment described later, the cutter unit 70 cuts the medium along the transport direction so as to cut the width of the medium in half. The media after cutting may be wound up in a roll shape as shown in the figure, or when cut into sheets (for example, A plate size, B plate size, etc.) by the cutter unit 70, they are stacked. Also good.

FIG. 3 is an explanatory diagram of the lower surface of the carriage.
A head 41 is provided on the lower surface of the carriage 31. The head 41 includes five nozzle rows. These five nozzle rows are arranged side by side in the moving direction (paper width direction) of the head 41.

  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 color nozzle rows that discharge color ink for forming a color image. The white nozzle row is a background nozzle row that discharges white ink (background ink) for forming a background image.

  The white ink is a special ink used when forming a color image on a transparent medium. When a color image is formed alone on a transparent medium, the visibility of the color image is not good. Therefore, by forming a background image with white ink together with the color image, the contrast of the color image is improved, or the color image is shielded. Improving the visibility of color images. For this reason, the white ink is an ink that is completely different from the color ink.

  Each nozzle row is composed of 180 nozzles. The 180 nozzles of each nozzle row are arranged along the transport direction at a predetermined nozzle pitch, and are arranged at an interval of 1/180 inch in this embodiment (that is, L in the figure is 1 inch). ). For this reason, by intermittently ejecting ink from each nozzle row, every time the carriage 31 moves once in the movement direction (for each pass), at intervals of 1/180 inch along the conveyance direction. A dot row is formed.

  The nozzle pitch can be expressed as k × D. k is an integer, and D is the dot interval in the transport direction (the direction of the nozzle row). For example, if an image is formed with D set to 1/180 inch, k is 1. If the image is formed with D set to 1/720 inch, k is 4.

  The two pre-curing irradiation units 61 can irradiate ultraviolet light in an irradiation range having a width of 1 inch (corresponding to L) along the conveyance direction. Since the irradiation range of the pre-curing irradiation unit 61 and the ink discharge range of each nozzle row are aligned in the moving direction, one temporary curing irradiation unit immediately after the ink is discharged from the nozzle row to the medium in a certain pass Can irradiate the ink (dots) landed on the medium with ultraviolet light.

<About front printing and back printing>
FIG. 4A is an explanatory diagram of an image formed by surface printing (surface printing image). “Front-print printing” is printing in which a color image is formed on a background image after the background image is formed on a medium. In the case of surface printing, when viewed from the front side of the medium, the color image is printed on the background image, so that the color image is easy to see. (However, when viewed from the back side of the medium, since the color image is hidden under the background image, the color image is difficult to see.)
FIG. 4B is an explanatory diagram of an image (back printing image) formed by back 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. In reverse printing, when viewed from the back side of the medium, since the color image is printed on the background image, the color image is easy to see. (However, when viewed from the front side of the medium, since the color image is hidden under the background image, it is difficult to see the color image.)
FIG. 5A is an explanatory diagram of surface printing.
When performing surface printing, half nozzles (nozzles # 1 to 90) on the downstream side in the conveyance direction are used in the color nozzle row (for example, cyan nozzle row), and half nozzles (nozzles on the upstream side in the conveyance direction) are used in the white nozzle row. # 91-180) are used. In this way, a color image is formed on the background image formed with the white ink by alternately repeating the pass using the nozzle and the conveying operation. For example, in region A in the figure, a background image is formed in pass 1 and a color image is formed in subsequent pass 2, thereby forming a color image on the background image.

FIG. 5B is an explanatory diagram of reverse printing.
When reverse printing is performed, half nozzles (nozzles # 91 to 180) on the upstream side in the transport direction are used in the color nozzle row, and half nozzles (nozzles # 1 to 90) on the downstream side in the transport direction are used in the white nozzle row. Used. In this way, the background image is formed on the color image by alternately repeating the pass using the nozzle and the conveying operation. For example, in area A in the figure, a color image is formed in pass 1 and a background image is formed in subsequent pass 2, thereby forming a background image on the color image.

  As shown in FIG. 5A, when surface printing is performed, the half nozzles (nozzles # 91 to 180) on the upstream side in the transport direction of the color nozzle row and the half nozzles on the downstream side in the transport direction of the white nozzle row (Nozzles # 1 to 90) are unused nozzles. For this reason, when surface printing is performed continuously for a long time, the ink components of these unused nozzles are thickened or solidified by evaporation, and the nozzles are easily clogged. In particular, white ink tends to thicken and nozzles are likely to clog. In addition, as a means for preventing clogging of the nozzle, there is a flushing operation for forcibly and continuously ejecting ink from the nozzle outside the printing region (non-printing flushing). Not only does the amount of ink consumed increase, but the printing operation is temporarily interrupted, resulting in a longer printing time.

  Similarly, as shown in FIG. 5B, when reverse printing is performed, the half nozzles (nozzles # 1 to 90) on the downstream side in the conveyance direction of the color nozzle row and the upstream side in the conveyance direction of the white nozzle row. Half of the nozzles (nozzles # 91 to 180) are unused nozzles. For this reason, even if back printing is performed continuously for a long time, the nozzles are easily clogged. In particular, white ink tends to thicken and nozzles are likely to clog. Further, if flushing outside printing is frequently performed in order to prevent nozzle clogging, not only the ink consumption increases, but also the printing operation is temporarily interrupted, resulting in a longer printing time.

<Allocation between front printing and back printing>
For example, a printing company that owns the printer 1 may receive an order for a printed matter for surface printing from Company A and an order for a printed matter for reverse printing from Company B. In such a case, the printer 1 receives both the printing instruction (print job) for the front printing and the printing instruction for the back printing from the computer 90. However, if back printing is performed after the printer 1 has completed front surface printing, unused nozzles may be clogged during front surface printing, and subsequent back surface printing may not be performed normally.

  Therefore, in the present embodiment described below, when there are both a print instruction for front printing and a print instruction for back printing, the printer 1 causes the front printing image (see FIG. 4A) and the back printing image (see FIG. 4A). 4B) is assigned in the paper width direction (the movement direction of the head 41), and both surface printing and back printing are performed in the same pass.

  FIG. 6A is an explanatory diagram of allocation of a front print image and a back print image. The controller 10 of the printer 1 arranges an image to be printed so that the front-printed print image and the back-printed print image are aligned in the paper width direction when both the front-printed print instruction and the reverse-printed print instruction are issued. (Assign an image). When there are a plurality of images to be printed, the images to be printed are arranged so that the plurality of printed images are arranged along the transport direction. Similarly, when there are a plurality of images to be back-printed, the images to be printed are arranged so that the plurality of back-printed images are arranged along the transport direction.

  Here, a front printing area is set on the left side of the medium in the drawing, and a back printing area is set on the right half. Then, a plurality of front print images are arranged along the transport direction in the left front print region, and a plurality of back print images are arranged along the transport direction in the right back print region. Although the front printing area and the back printing area are allocated equally, the widths of the printing areas may be different depending on the sizes of the front printing image and the back printing image.

  By arranging the front print image and the back print image side by side in the paper width direction, both front print and back print are performed in the same pass as described below.

FIG. 6B is an explanatory diagram of the nozzles used in a certain pass.
In front printing, the half nozzles (nozzles # 91 to 180) on the upstream side in the transport direction of the color nozzle row and the half nozzles (nozzles # 1 to 90) on the downstream side in the transport direction of the white nozzle row are used as unused nozzles. However, these nozzles will be used in reverse printing. In reverse printing, half nozzles (nozzles # 1 to 90) on the downstream side in the conveyance direction of the color nozzle row and half nozzles (nozzles # 91 to 180) on the upstream side in the conveyance direction of the white nozzle row are not used. These nozzles are used for surface printing.

  For this reason, by performing both surface printing and back printing in the same pass, it is possible to reduce the number of nozzles that are not used continuously for a long time. As a result, the nozzle is less likely to be clogged. Further, since it is possible to reduce the number of nozzles that are not used continuously for a long time, it is possible to reduce the number of flushing operations (outside printing flushing) that forcibly and continuously eject ink from the nozzles outside the printing region. If flushing outside printing is frequently performed, not only the ink consumption increases, but the printing operation is temporarily interrupted, so the printing time becomes longer. According to this embodiment, the ink consumption is reduced. It is possible to suppress the printing time. This effect is particularly remarkable in white ink that tends to thicken.

  Note that the controller 10 causes the cutter unit to cut the medium in the margin between the front-printed print image and the back-printed print image. This cut line is a line along the transport direction (see FIG. 6A). Since a plurality of front-printed images and back-printed images are arranged side by side along the transport direction, if the medium is divided into two along the transport direction, the surface-printed medium and the back print It can be separated from the printed medium. As described above, when an order is received from A company for a printed matter for surface printing, and an order for a printed matter for back printing is received from B company, one of the media divided by the cutter unit is delivered to A company, and the other is It will be delivered to Company B.

=== Second Embodiment ===
FIG. 7A is an explanatory diagram of a printed matter according to the second embodiment. FIG. 7B is an explanatory diagram of nozzles used in a certain pass according to the second embodiment.

  Also in the second embodiment, the controller 10 of the printer 1 allows the front print image and the back print image to be aligned in the paper width direction when both the print instruction for the front print and the print instruction for the back print are provided. An image to be printed is assigned (see FIG. 7A). As a result, both surface printing and back printing are performed in the same pass (see FIG. 7B). Thereby, also in 2nd Embodiment, it becomes difficult to clog a nozzle similarly to 1st Embodiment.

  Further, in the second embodiment, the controller 10 sets a flushing area between the front printing area and the back printing area (see FIG. 7A). Then, the controller 10 forcibly and continuously ejects ink from the nozzle used for printing the next image when the nozzle passes over the flushing area in each pass (flushing operation). In the pass shown in FIG. 7B, when the nozzles pass over the flushing area, the nozzles used for reverse printing (nozzles # 91 to 180 on the upstream half of the color nozzle row in the carrying direction and downstream in the carrying direction of the white nozzle row) are used. The ink is forcibly continuously discharged from the nozzles # 1 to 90) on the side half. As a result, even when ink containing a component that easily evaporates is used and ink thickening or solidification progresses somewhat in the nozzle during surface printing, clogging of the nozzle during back printing can be suppressed.

  Note that, as shown on the left side of FIG. 7B, ink may be forcibly continuously ejected from all nozzles outside the medium immediately before surface printing is performed. Thereby, clogging of the nozzle at the time of surface printing can be suppressed. Further, as shown on the right side of FIG. 7B, immediately after the back printing is performed, the ink may be forcibly continuously ejected from all the nozzles outside the medium. Thereby, clogging of the nozzle used in the next pass can be suppressed. Note that the flushing immediately after the back printing is performed may not be performed.

  By the way, according to the second embodiment, the ink ejected by the flushing operation lands on the flushing area between the front printing area and the back printing area. As a result, an image by flushing is formed between the front print image and the back print image.

Therefore, in the second embodiment, the controller 10 causes the cutter unit to cut both sides of the flushing area so as to cut out the flushing area. In other words, in the second embodiment, the controller 10 provides a cut line in the margin between the front print image and the flushing area, and also provides a cut line in the margin between the back print image and the flushing area. Accordingly, it is possible to deliver the front-printed print image and the back-printed print image with the image removed by flushing being removed.
However, if an image by flushing is allowed even if it is attached to a front-printed print image or a back-printed print image, only one side of the two cut lines in FIG. 7B may be used.

<Modification of Second Embodiment>
In the second embodiment shown in FIGS. 7A and 7B, when the flushing is performed immediately before the surface printing is performed, the flushing is performed outside the medium. However, this flushing may be performed inside the medium. In the second embodiment shown in FIGS. 7A and 7B, even when the flushing is performed immediately after the back printing is performed, the flushing is performed outside the medium. However, this flushing may be performed inside the medium.

  FIG. 8A is an explanatory diagram of a printed matter according to a modification of the second embodiment. FIG. 8B is an explanatory diagram of a nozzle used in a certain pass according to a modification of the second embodiment.

  Also in this modified example, the controller 10 of the printer 1 performs printing so that the front print image and the back print image are aligned in the paper width direction when both the print instruction for the front print and the print instruction for the back print are provided. An image to be assigned is assigned (see FIG. 8A). As a result, both surface printing and back printing are performed in the same pass (see FIG. 8B). Thereby, also in a modification, it becomes difficult to clog a nozzle similarly to 1st Embodiment and 2nd Embodiment.

  Also in the modification, the controller 10 sets a flushing area between the front printing area and the back printing area (see FIG. 8A). As a result, even when ink containing a component that easily evaporates is used and ink thickening or solidification progresses somewhat in the nozzle during surface printing, clogging of the nozzle during back printing can be suppressed.

  In the modified example, as shown on the left side of FIG. 8B, immediately before the surface printing is performed, ink is forcibly continuously ejected from all the nozzles inside the medium. Thereby, clogging of the nozzle at the time of surface printing can be suppressed. Although not shown, when the nozzle row moves in the direction opposite to the moving direction in FIG. 8B in bidirectional printing, ink is discharged from all the nozzles inside the medium immediately before the back printing is performed. Force continuous discharge. Thereby, clogging of the nozzle at the time of back printing can be suppressed.

  By the way, according to the modification, the ink ejected by the flushing operation is landed on the flushing region between the front-printed image and the edge of the medium. As a result, an image by flushing is formed between the surface printing and the edge of the medium. Therefore, in the modification, the controller 10 may cause the cutter unit to cut the left side of the front print image. Similarly, the controller 10 may cause the cutter unit to cut the right side of the back print image.

=== Third Embodiment ===
In the second embodiment described above, an image by flushing is formed between the front print image and the back print image (see FIG. 7A). However, a useful inspection pattern may be formed between the front printing image and the back printing image.

  FIG. 9A is an explanatory diagram of a printed matter according to the third embodiment. FIG. 9B is an explanatory diagram of a nozzle test pattern according to the third embodiment.

  Also in the third embodiment, if the controller 10 of the printer 1 has both a printing instruction for front printing and a printing instruction for back printing, the front printing image and the back printing image are arranged in the paper width direction. An image to be printed is assigned (see FIG. 9A). As a result, both front-surface printing and back-surface printing are performed in the same pass, which makes it difficult for the nozzles to be clogged, as in the first and second embodiments.

  Furthermore, in the third embodiment, the controller 10 forms a nozzle test pattern between the front print image and the back print image by forming a nozzle test pattern after the front print and immediately before the back print. (See FIG. 9A). When forming the nozzle test pattern, the controller 10 ejects a predetermined number (here, 5) of ink droplets from each nozzle at a predetermined timing (FIG. 9B). Thereby, if an inspector looks at a nozzle test pattern, the inspector can inspect for the presence of a defective nozzle that cannot eject ink. For example, if the inspector confirms the nozzle test pattern of FIG. 9B, it can be specified that the nozzle # 8 is a defective nozzle.

  When forming the nozzle test pattern, the controller 10 forcibly and continuously ejects ink from the nozzles. For this reason, similarly to the above-described flushing operation, clogging of the nozzles during back printing can be suppressed even if the ink thickening or solidification slightly progresses in the nozzles during surface printing. For example, as shown in FIG. 9B, even if the ink of the nozzle # 4 is thickened or solidified during the surface printing, the ink is forcibly continuously ejected from the nozzle # 4 when the nozzle test pattern is formed. By doing so, the nozzle # 4 can be recovered before the back printing.

  The nozzle inspection pattern can fulfill the quality assurance function of front-surface printing and back-surface printing. For this reason, a nozzle inspection pattern may be attached to the back print image or the back print image. In this case, as shown in FIG. 9A, it is preferable to cut the cutter unit only on one side, not on both sides of the nozzle test pattern. Thereby, for example, the company B that has received the printed material of the back printing can check the quality of the back printing image by looking at the nozzle inspection pattern. Then, with the nozzle test pattern as shown in FIG. 9B, it can be known that the printed matter is produced with the nozzle # 8 being a defective nozzle.

=== Fourth Embodiment ===
In the surface printing shown in FIG. 5A and the back printing shown in FIG. 5B, a color image and a background image are formed at the same resolution as the nozzle pitch (1/180 inch). However, it is also possible to form a color image or a background image with a resolution finer than the nozzle pitch.

<Reference: Normal interlaced printing>
FIG. 10 is an explanatory diagram of normal interlaced printing. In the drawing, the position of the head (nozzle row) and the state of dot formation in pass 1 to pass 4 are shown.

  For convenience of explanation, only one nozzle row of a plurality of nozzle rows is shown, and the number of nozzles is also reduced (here, 12). The nozzles indicated by black circles in the figure are nozzles that can eject ink. On the other hand, nozzles indicated by white circles are nozzles that cannot eject ink. For convenience of explanation, the head (nozzle row) is depicted as moving relative to the medium, but this figure shows the relative positions of the head and the medium. The medium is transported in the transport direction. In addition, for convenience of explanation, each nozzle is shown as forming only a few dots (circles in the figure), but in reality, ink droplets are ejected intermittently from nozzles that move in the moving direction. Therefore, a large number of dots are arranged in the moving direction. This row of dots is also called a raster line. A dot indicated by a black circle is a dot formed in the last pass, and a dot indicated by a white circle is a dot formed in a previous pass.

  “Interlaced printing” means a printing method in which k is 2 or more and a raster line that is not recorded is sandwiched between raster lines that are recorded in one pass. For example, in the printing method shown in the figure, k is 4 and three raster lines are sandwiched between raster lines formed in one pass (as described above, the nozzle pitch is k × D, k is an integer, and D is the dot interval in the transport direction).

  In interlaced printing, each time a medium is transported by a certain transport amount F in the transport direction, each nozzle records a raster line immediately above the raster line recorded in the immediately preceding pass. In order to perform recording with a constant carry amount in this way, (1) the number N (integer) of nozzles that can eject ink is relatively prime to k, and (2) the carry amount F is N · The condition is that it is set to D.

  In the figure, the nozzle row has 12 nozzles arranged in the transport direction. Since the nozzle pitch (k × D) of the nozzle row is 1/180 inch and the dot interval D in the transport direction is 1/720 inch, k is 4. Therefore, 11 nozzles (nozzle # 1 to nozzle # 11) are used instead of all the nozzles in order to satisfy “N and k are relatively prime”, which is a condition for performing interlaced printing. It is done. In addition, since 11 nozzles are used, the medium is transported by a transport amount of 11 · D. As a result, using a nozzle row having a nozzle pitch of 1/180 inch (= 4 × D), dots are formed on the medium at a dot interval of 1/720 inch (= D). When interlace printing is performed using a nozzle array including 180 nozzles # 1 to # 180, a pass using 179 nozzles and a transport operation with a transport amount of 179 · D are alternately repeated. Become.

  In the case of interlace printing, k passes are required to complete a raster line having a continuous nozzle pitch width. For example, in order to complete four raster lines that are continuous at a dot interval of 720 dpi using a nozzle row having a nozzle pitch of 180 dpi, four passes are required. According to the figure, continuous raster lines are formed at dot intervals D upstream of the raster line (raster line indicated by the arrow in the figure) formed by nozzle # 3 in pass 3 in the transport direction. It has been shown.

  When interlace printing is performed for only a color image without forming a background image, the color nozzle rows (cyan nozzle row, magenta nozzle row, yellow nozzle row and black nozzle row in FIG. 3) for each color are shown in FIG. Each works like In other words, each color nozzle row ejects ink from the respective nozzles # 1 to # 11 (nozzles # 1 to # 179 when each nozzle row includes 180 nozzles).

  However, in the case of forming a color image while forming a background image, as described below, the position in the transport direction of the color nozzle that discharges color ink and the transport direction of the white nozzle that discharges white ink The position of is not overlapped.

<Front printing and back printing by interlace printing>
FIG. 11 is an explanatory diagram of surface printing by interlace printing. In the drawing, the nozzles in the color nozzle row are indicated by circles, and the nozzles in the white nozzle row are indicated by triangles.

  Also in the case of surface printing by interlace printing, half nozzles (nozzles # 1 to 6) on the downstream side in the transport direction of the color nozzle row are used, and half nozzles (nozzle # 7) on the upstream side in the transport direction of the white nozzle row. ~ 12) are used. The interlaced printing conditions already described ((1) The number of nozzles N (integer) that can eject ink is coprime to k, and (2) the carry amount F is set to ND). In order to satisfy this condition, when interlace printing is performed with six nozzles, ink is ejected from the five nozzles and the medium is transported by a transport amount of 5 · D.

  At any raster line position, white dots are formed by the nozzles in the white nozzle row (white nozzles), and then color dots are formed by the nozzles in the color nozzle row (color nozzles). For example, in the raster line at the position of the dotted line in the figure, after the white dot is formed in pass 1, color dots are formed in pass 5. For this reason, a color image can be formed on the background image.

  Although not shown, also in the case of reverse printing by interlace printing, half nozzles on the upstream side in the transport direction of the color nozzle row are used, and half nozzles on the downstream side in the transport direction of the white nozzle row are used. Then, the background image can be formed on the color image by alternately repeating the pass and the conveying operation so as to satisfy the conditions of the interlaced printing.

  By the way, when surface printing is performed by interlace printing, as in the above-described embodiment, the half nozzle on the upstream side in the transport direction of the color nozzle row and the half nozzle on the downstream side in the transport direction of the white nozzle row are It becomes an unused nozzle. Also, when back printing is performed by interlace printing, as in the above-described embodiment, the half nozzles on the downstream side in the transport direction of the color nozzle row and the half nozzles on the upstream side in the transport direction of the white nozzle row are It becomes an unused nozzle.

  Therefore, even in the case of interlaced printing, if there are both a print instruction for front-surface printing and a print instruction for back-surface printing, the printer 1 assigns the front-surface printing image and the back-surface printing image in the paper width direction and uses the same path. It is recommended to perform both surface printing and back printing. By performing both surface printing and back printing in the same pass, it is possible to reduce the number of nozzles that are not used continuously for a long time. As a result, the nozzle is less likely to be clogged.

=== Fifth Embodiment ===
In the above-described embodiment, half of the nozzles in each nozzle row are used during front surface printing or back surface printing. However, the method of using the nozzle is not limited to this.

12A and 12B are explanatory diagrams of a printing method according to the fifth embodiment.
In a certain pass, as shown in FIG. 12A, a white nozzle row is used to form a background image in the front print area, and a color nozzle row is used to form a color image in the reverse print area. . After the pass shown in FIG. 12A, the next pass is performed without performing the transport operation. In the next pass, as shown in FIG. 12B, a background image is formed using the white nozzle array in the reverse printing area, and a color image is formed using the color nozzle array in the front printing area. . Thus, after the pass shown in FIG. 12B, a color image is formed on the background image in the front print area and the front print image is printed, and the background image is printed on the color image in the back print area. A back print image is formed and printed. After the pass shown in FIG. 12B, the medium is transported in the transport direction by a transport amount corresponding to the length L of the nozzle row (see FIG. 3). After this transport operation, the above-described FIG. 12A and FIG. The pass shown is made again.

  As described above, also in the fifth embodiment, the controller 10 of the printer 1 allows the front print image and the back print image to be arranged in the paper width direction if both the print instruction for the front print and the print instruction for the back print are provided. Allocate images to be printed so that they line up. As a result, both surface printing and back printing are performed in the same pass (see FIGS. 12A and 12B). Thereby, also in 5th Embodiment, it becomes difficult to clog a nozzle.

=== 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. When UV ink is not used, the above-described irradiation unit 60 is also unnecessary.

<About white ink>
In the present specification, the term “white” is not limited to white in the strict sense that is the surface color of an object that reflects 100% of all wavelengths of visible light. It shall include a color called white. “White” means, for example, (1) Color measurement mode: Spot color measurement, Light source: D50, Backing: Black, Print medium: Measured with transparent film, using x-rite colorimeter eye-one Pro If it is colored, the label in the Lab system is on the a * b * plane within the circumference of the radius 20 and inside thereof, and L * is in the hue range represented by 70 or more, or (2) Minolta When using the colorimeter CM2022 manufactured by the company with color measurement in the measurement mode D502 ° field of view, SCF mode, and white background, the label in the Lab system is on the circumference of the radius 20 and inside it on the a * b * plane. , And L * is in the hue range represented by 70 or more, or (3) the color of the ink used as the background of the image as described in JP-A-2004-306591, as the background If it is used, it is not limited to pure white.

<About background images>
In the above-described embodiment, the background image is formed with the white ink. However, the background image is not limited to a white image formed with white ink. For example, a metallic image formed with glittering ink (metallic ink) may be used as the background image. In this case, the head 41 is preferably provided with a nozzle row that ejects glitter ink instead of the white nozzle row.

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, 32 Carriage moving mechanism,
40 head units, 41 heads,
50 detector groups, 60 irradiation units, 61 temporary curing irradiation unit, 62 main curing irradiation unit,
70 cutter units, 90 computers

Claims (6)

A transport unit for transporting the medium in the transport direction;
A head that is movable along a moving direction that intersects the transport direction, and a color nozzle row in which nozzles for ejecting ink for forming a color image are arranged in the transport direction, and an ink for forming a background image A nozzle having a background nozzle array arranged in the transport direction, and a head in which the color nozzle array and the background nozzle array are arranged in the moving direction;
A control unit that performs a transport operation of transporting the medium to the transport unit and a discharge operation of ejecting the ink to a head that moves in the moving direction;
A printing apparatus comprising:
The control unit receives both a print instruction for a front print image for forming the color image on the background image and a print instruction for a back print image for forming the background image on the color image. In this case, the printing apparatus is characterized in that the front printing image and the back printing image are arranged in the moving direction and printed on the medium. The printing apparatus according to claim 1,
The control unit forcibly continuously ejects the ink from the nozzles when the head passes between a region where the front-printed print image is formed and a region where the back-printed print image is formed. A printing apparatus characterized by that. The printing apparatus according to claim 2,
The control unit forcibly continuously ejects the ink from the nozzles when the head passes between a region where the front-printed print image is formed and a region where the back-printed print image is formed. Thus, a printing apparatus for forming a pattern for inspecting clogging of the nozzle. The printing apparatus according to claim 3,
A cutter unit for cutting the medium;
The printing apparatus, wherein the cutter unit cuts the medium so that the pattern is attached to at least one of the front printing image and the back printing image. A transport unit for transporting the medium in the transport direction;
A head that is movable along a moving direction that intersects the transport direction, and a first nozzle row in which nozzles for ejecting ink for forming a color image are arranged in the transport direction, and for forming a background image A nozzle having nozzles for ejecting ink arranged in the transport direction; and a head in which the first nozzle array and the second nozzle array are arranged in the movement direction;
Use
A printing method that performs a transport operation for transporting the medium to the transport unit and a discharge operation for ejecting the ink to a head that moves in the moving direction,
When both a print instruction for a front print image for forming the color image on the background image and a print instruction for a back print image for forming the background image on the color image are received, A printing method comprising: printing a printed image and a back printed image on the medium in the moving direction.   A printed matter printed by the printing method according to claim 5.

Images