JP5560679B2 - Fluid ejecting apparatus and fluid ejecting method - Google Patents

Description

  The present invention relates to a fluid ejecting apparatus and a fluid ejecting method.

  As one of fluid ejecting apparatuses, there is an ink jet printer including a nozzle row in which nozzles that eject ink (fluid) to a medium are arranged in a predetermined direction. Among inkjet printers, there are known printers that repeat an operation of ejecting ink from nozzles while moving a nozzle row in a moving direction intersecting a predetermined direction and an operation of transporting a medium in a predetermined direction.

  A printing apparatus that performs printing using white ink in addition to color inks such as cyan, magenta, and yellow is known (see, for example, Patent Document 1). In such a printer, by performing the background treatment with the white ink, it is possible to print a color image with good color developability without being influenced by the ground color of the medium.

JP 2002-38063 A

As the background processing using white ink, for example, a background image of white ink is printed on a medium, and then a color image is printed on the background image with color ink. By printing a color image after printing a background image and then providing a drying time, ink bleeding can be prevented. However, if variations occur in the drying time of the background image, density unevenness occurs in the image.
Therefore, an object of the present invention is to suppress image quality deterioration of an image.

The main invention for solving the above problems are aligned in the moving direction crossing the nozzle for ejecting a fluid to form a color image and a first nozzle row aligned in a predetermined direction, before Symbol first nozzle array and said predetermined direction , relative a second nozzle row in which the nozzles for ejecting a fluid to form a background image overlapping the color image arranged in the predetermined direction, and a pre-Symbol first nozzle array and the second nozzle array and the medium in the moving direction an operation for ejecting fluid from the nozzles while moving to, the first nozzle array and a control unit for repeatedly, and operation of relatively moving in the predetermined direction of the one direction a relative position of the medium body relative to the second nozzle array a is normal at the time of image formation, with the first nozzle array and the said control unit for a predetermined carry amount in one direction causes relative movement of the second predetermined direction a relative position of the medium body with respect to the nozzle row Has, the nozzles forming the upper layer of the image of said color image and the background image, than the nozzles forming the underlying image and the nozzles located in the one direction side of the predetermined direction, wherein A non-ejection nozzle, which is the nozzle from which fluid is not ejected, is positioned on the one direction side in the predetermined direction with respect to the nozzle that forms the lower layer image during image formation at the edge of the medium, and the upper layer The length in the predetermined direction of the region to which the non-ejection nozzle belongs is located in the other direction side of the predetermined direction from the nozzle forming the image, and is an integral multiple of the predetermined conveyance amount , The fluid ejecting apparatus is characterized.

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

1 is an overall configuration block diagram of a printer. 2A is a schematic perspective view of the printer, and FIG. 2B is a schematic cross-sectional view of the printer. It is a figure which shows the nozzle arrangement | sequence of the lower surface of a head. FIG. 4 is a diagram illustrating a medium feeding position and a sheet discharging position. It is a figure explaining the printing method of the comparative example in surface printing mode. It is a figure which shows the mode of the upper end printing of the surface printing mode of this embodiment. It is a figure which shows the mode of the lower end printing of the surface printing mode of this embodiment. FIG. 8A and FIG. 8B are diagrams showing the paper feed position and paper discharge position of printers with different transport units. It is a figure which shows the printing method of the comparative example which varied the number of nozzles for drying. It is a figure which shows the printing method which changed the number of nozzles for drying. It is a figure which shows the printing method which made the nozzle at the time of upper end and lower end printing and the nozzle at the time of normal printing the same.

=== Summary of disclosure ===
At least the following will become apparent from the description of the present specification and the accompanying drawings.

That is, (A) a first nozzle row in which nozzles for ejecting a first fluid are arranged in a predetermined direction, and (B) a second fluid is arranged in a moving direction that intersects the first nozzle row and the predetermined direction. A second nozzle array in which nozzles to be ejected are arranged in the predetermined direction; and (C) an operation of ejecting fluid from the nozzles while relatively moving the first nozzle array, the second nozzle array, and the medium in the movement direction. And a controller that repeatedly moves the relative positions of the first nozzle row, the second nozzle row, and the medium in one direction of the predetermined direction. A control unit that relatively moves a predetermined transport amount in the one direction of the predetermined direction with respect to a relative position between the first nozzle row and the second nozzle row and the medium; and (E) the first The second fluid on the first image by the fluid of one When the second image is formed, the nozzle that forms the second image is the nozzle that is located on the one direction side in the predetermined direction with respect to the nozzle that forms the first image. A non-ejection nozzle, which is the nozzle from which fluid is not ejected, is positioned closer to the one direction side of the predetermined direction than the nozzle that forms the first image, and the second image The length in the predetermined direction of the region to which the non-injecting nozzle belongs is located on the other side of the predetermined direction with respect to the nozzle to be formed, and is a length that is an integral multiple of the predetermined conveyance amount, (F) Is a fluid ejecting apparatus.
According to such a fluid ejecting apparatus, it is possible to make the drying time of the first image constant, and it is possible to suppress image quality deterioration.

In the fluid ejecting apparatus, during normal image formation, the other non-ejection nozzle that is the nozzle from which fluid is not ejected is positioned closer to the one direction side in the predetermined direction than the nozzle that forms the first image. In addition, the length in the predetermined direction of the region to which the other non-injection nozzle belongs is located on the other direction side of the predetermined direction with respect to the nozzle that forms the second image. The length must be an integer multiple.
According to such a fluid ejecting apparatus, it is possible to make the drying time of the first image constant, and it is possible to suppress image quality deterioration.

In the fluid ejecting apparatus, the first image is formed during normal image formation by the nozzle that forms the first image at the time of image formation of the end portion on the one direction side in the predetermined direction of the medium. The nozzle is located on the one side in the predetermined direction with respect to the nozzle, and the non-ejection nozzle is located on the one direction side in the predetermined direction with respect to the other non-ejection nozzle during normal image formation. Use the nozzle.
According to such a fluid ejecting apparatus, the position control range of the medium can be shortened.

In this fluid ejecting apparatus, the nozzle that forms the second image is formed at the end of the predetermined direction in the other direction of the medium, and the second image is formed at the time of normal image formation. The nozzle is located on the other direction side of the predetermined direction with respect to the nozzle, and the non-ejection nozzle is located on the other direction side of the predetermined direction with respect to the other non-ejection nozzle during normal image formation. Use the nozzle.
According to such a fluid ejecting apparatus, the position control range of the medium can be shortened.

In this fluid ejecting apparatus, the length in the predetermined direction of the region to which the nozzle that forms at least one of the first image and the second image belongs is an integral multiple of the predetermined transport amount. Be long.
According to such a fluid ejecting apparatus, the number of nozzles that form each image (the number of times the nozzle row moves in the movement direction) can be made constant.

In addition, the first nozzle row in which the nozzles that eject the first fluid are arranged in a predetermined direction, and the nozzle that injects the second fluid in the movement direction that intersects the first nozzle row and the predetermined direction are An operation of ejecting a fluid from the nozzle while relatively moving the second nozzle row arranged in a predetermined direction and the medium in the moving direction; and the relative relationship between the first nozzle row and the second nozzle row and the medium. A fluid ejecting method of a fluid ejecting apparatus that repeats an operation of relatively moving a position in one direction of the predetermined direction, and during normal image formation, the first nozzle array, the second nozzle array, and the medium When the relative position is moved relative to the predetermined direction in the predetermined direction by a predetermined conveyance amount, and the second image is formed by the second fluid on the first image by the first fluid. Before forming 2 images A nozzle is the nozzle positioned on the one direction side in the predetermined direction with respect to the nozzle that forms the first image, and more than the nozzle that forms the first image at the time of image formation at the edge of the medium. The nozzle located on the one direction side of the predetermined direction and located on the other direction side of the predetermined direction with respect to the nozzle forming the second image, wherein the length in the predetermined direction is the predetermined direction. A fluid ejecting method comprising: not ejecting fluid from the nozzle belonging to a region having a length that is an integral multiple of the transport amount.
According to such a fluid ejecting method, the drying time of the first image can be made constant, and image quality deterioration can be suppressed.

=== About the printing system ===
Hereinafter, an embodiment will be described by taking a fluid ejecting apparatus as an ink jet printer and taking a serial printer (hereinafter referred to as a printer) in the ink jet printer as an example.

  FIG. 1 is a block diagram of the overall configuration of the printer 1. FIG. 2A is a schematic perspective view of the printer 1, and FIG. 2B is a schematic cross-sectional view of the printer 1. The printer 1 that has received the print data from the computer 60, which is an external device, controls each unit (the conveyance unit 20, the carriage unit 30, and the head unit 40) by the controller 10 so as to display an image on the medium S (paper, film, etc.). Form. Further, the detector group 50 monitors the situation in the printer 1, and the controller 10 controls each unit based on the detection result. The computer 60 is installed with a program (printer driver) for converting image data output from the application program into print data. The printer driver is recorded on a recording medium (computer-readable recording medium) such as a flexible disk FD or a CD-ROM, or can be downloaded via the Internet.

  The controller 10 (control unit) is a control unit for controlling the printer 1. The interface unit 11 is for transmitting and receiving data between the computer 60 as an external device 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 a unit control circuit 14 according to a program stored in the memory 13.

  The transport unit 20 feeds the medium S to a printable position and transports the medium S by a predetermined transport amount in the transport direction (predetermined direction) during printing. The transport unit 20 feeds the paper feed roller 21, the transport roller 22, and the discharge roller. And a paper roller 23. The paper feed roller 21 is rotated, and the medium S to be printed is sent to the transport roller 22. The controller 10 rotates the transport roller 22 to position the medium S at the print start position.

The carriage unit 30 is for moving the head 41 in a direction crossing the transport direction (hereinafter referred to as a movement direction), and has a carriage 31.
The head unit 40 is for ejecting ink onto the medium S and has a head 41. The head 41 is moved in the movement direction by the carriage 31. A plurality of nozzles, which are ink ejecting portions, are provided on the lower surface of the head 41, and each nozzle is provided with an ink chamber (not shown) containing ink.

  FIG. 3 is a diagram showing the nozzle arrangement on the lower surface of the head 41. On the lower surface of the head 41, five nozzle rows in which 180 nozzles are arranged at a predetermined interval (nozzle pitch d) in the transport direction are formed. As shown in the figure, black nozzle row K for ejecting black ink, cyan nozzle row C for ejecting cyan ink, magenta nozzle row M for ejecting magenta ink, yellow nozzle row Y for ejecting yellow ink, and white ink are ejected. White nozzle rows W are arranged in order in the movement direction. Note that the 180 nozzles in each nozzle row are numbered sequentially from the nozzles on the downstream side in the transport direction (# 1 to # 180).

  In such a printer 1, a dot forming process (corresponding to an image forming operation) in which ink droplets are intermittently ejected from the head 41 moving in the moving direction to form dots on the medium, and the medium is applied to the head 41. On the other hand, the carrying process (corresponding to the carrying operation) for carrying in the carrying direction is repeated. By doing so, dots can be formed at positions on the medium different from the positions of the dots formed by the previous dot formation process, and a two-dimensional image can be printed on the medium. The operation in which the head 41 moves once in the movement direction while ejecting ink droplets is referred to as “pass”.

=== About print mode ===
In the printer 1 of the present embodiment, one of the printing modes can be selected from “normal color mode”, “front printing mode”, and “back printing mode”. It is assumed that the print mode is selected by the user. The normal color mode is a mode in which a color image (including a monochrome image) using four colors of black, cyan, magenta, and yellow is directly printed on a medium. That is, in the normal color mode, four color nozzle rows (YMCK) are used, and the white nozzle row W (corresponding to the first nozzle row or the second nozzle row) is not used. Hereinafter, for the sake of explanation, the four color nozzle rows (YMCK) are collectively referred to as “color nozzle row Co (corresponding to the first nozzle row or the second nozzle row)”.

  On the other hand, in the front printing mode and the back printing mode, the background image of the white ink (W) is overlaid and printed on the color image of the four color ink (YMCK). By doing so, the color developability of the color image can be improved, and when the transparent medium is used as the medium, it is possible to prevent the opposite side of the color image from being seen through. The front printing mode is a mode in which a white background image is first printed on a predetermined area on the medium, and a color image is printed on the background image. Therefore, in the front printing mode, the color image is viewed from the printing surface side. On the other hand, the reverse printing mode is a mode in which a color image is first printed on a predetermined area on the medium, and a white background image is printed on the color image. Therefore, in the reverse printing mode, the color image is viewed from the medium surface side. Therefore, the back printing mode can be selected when a transparent medium is used.

=== About the transport unit 20 ===
FIG. 4 is a diagram illustrating a paper feed position and a paper discharge position of the medium S by the transport unit 20 of the printer 1. In the printer 1 of this embodiment, it is assumed that printing is performed in a state where the medium S is sandwiched between both the transport roller 22 and the paper discharge roller 23. By doing so, the medium S can be stably conveyed. In the following description, of the two ends in the transport direction of the medium S (the end along the moving direction), the end on the upstream side in the transport direction is referred to as the “upper end”, and the end on the downstream side in the transport direction Is called the “lower end”.

  The left diagram in FIG. 4 is a diagram illustrating the position (paper feed position) of the medium S with respect to the head 41 at the start of printing. Here, a point where the upper end portion of the medium S is located downstream from the end portion of the head 41 on the downstream side in the transport direction by a length D is defined as a “paper feed position (print start position)”. At the paper feed position shown in the drawing, printing can be started with the medium S being sandwiched between the transport roller 22 and the paper discharge roller 23.

  On the other hand, the right diagram of FIG. 4 is a diagram showing the position of the medium S (paper discharge position) with respect to the head 41 at the end of printing. Here, a point where the lower end portion of the medium S is located upstream by the length D from the upstream end portion of the head 41 in the transport direction is defined as a “paper discharge position (print end position)”. At the paper discharge position shown in the drawing, printing can be completed with the medium S being sandwiched between the transport roller 22 and the paper discharge roller 23.

==== Regarding the Printing Method of the Comparative Example ===
FIG. 5 is a diagram illustrating a printing method of a comparative example in the front printing mode. For simplicity of explanation, the number of nozzles belonging to one nozzle row is reduced to 24 in the drawing. In the surface printing mode printing of the comparative example, among the nozzles belonging to the color nozzle row Co (= YMCK), the half nozzles (# 1 to # 12) on the downstream side in the transport direction are used, and the half on the upstream side in the transport direction. No. nozzles (# 13 to # 24) are not used. On the other hand, in the white nozzle row W, half nozzles (# 1 to # 12) on the downstream side in the transport direction are not used, and half nozzles (# 13 to # 24) on the upstream side in the transport direction are used. For the following explanation, the nozzles used for printing are called “used nozzles (▲, ○)”.

  The right diagram in FIG. 5 shows the positional relationship of nozzles (ejection nozzles) that eject ink in each pass. In an actual printer, the medium is transported downstream in the transport direction with respect to the head 41 (nozzles), but in the figure, the position of the head 41 is moved upstream in the transport direction with respect to the medium. Further, the used nozzles # 1 to # 12 of the color nozzle row Co and the used nozzles # 13 to # 24 of the white nozzle row W are drawn as one nozzle row.

  The right diagram in FIG. 5 shows a state from the start of printing of the medium to the end of printing. That is, the printing state from the upper end to the lower end of the medium is shown. In the upper end printing process (hereinafter referred to as upper end printing) and the lower end printing process (hereinafter referred to as lower end printing), the conveyance amount of the medium is different from the printing process other than the end part (hereinafter referred to as normal printing). In the normal printing of FIG. 5 (pass 5 to pass 13), an operation of forming an image while moving the head 41 in the moving direction, and an operation of transporting the medium 3d in length 3d in the transport direction in the nozzle pitch d. Are repeated alternately. By doing so, the predetermined area of the medium first faces the used nozzles (# 13 to # 24) of the white nozzle row W, and then faces the used nozzles (# 1 to # 12) of the color nozzle row Co. . As a result, a background image is printed in a predetermined pass on the medium, and a color image is printed on the background image in a later pass. In FIG. 5, the number of used nozzles in each of the nozzle arrays Co and W is twelve, and the amount of medium transported at one time is three times the nozzle pitch d. Therefore, the background image and the color image are printed in four passes each. The In this way, by printing an image with different nozzles over a plurality of passes for a predetermined area of the medium, it is possible to reduce the difference in nozzle characteristics.

  On the other hand, in the upper end printing and the lower end printing, the transport amount of the medium is changed (decreased) as compared with the normal printing. Here, when the upper end portion of the medium is printed and the medium transport amount before and after the pass is smaller than the medium transport amount 3d during normal printing, the pass is set as the upper end printing pass. Therefore, in the right diagram of FIG. 5, pass 1 to pass 4 correspond to the top-end printing pass. Similarly, when the lower end portion of the medium is printed and the medium transport amount before and after the pass is smaller than the medium transport amount 3d during normal printing, the pass is set as the lower end printing pass. Therefore, in the right diagram of FIG. 5, pass 14 to pass 17 correspond to the lower-end printing pass. In both upper-end printing and lower-end printing, the medium conveyance amount is the nozzle pitch d. As described above, the medium transport amount is smaller at the time of upper end printing and lower end printing than at the time of normal printing, so the number of nozzles for ejecting ink droplets (hereinafter referred to as ejection nozzles) is small at the start of printing, and the number of ejection nozzles is gradually increased On the contrary, at the end of printing, the number of ejection nozzles is gradually reduced. Therefore, for example, among the used nozzles (# 13 to # 24) of the white nozzle row W, ink droplets are ejected even if the nozzle is upstream in the transport direction from the printing start position (position of nozzle # 16 in pass 1). There are nozzles (# 19 to # 24) that do not.

  As described above, in the upper end printing and the lower end printing, the medium conveyance amount is changed as compared with the normal printing, and printing is performed by selecting a nozzle that ejects ink droplets from among the used nozzles. By doing so, the upper end portion and the lower end portion of the medium are also subjected to four passes from the ejection nozzles (◯) of the white nozzle row W in the previous pass with respect to the predetermined region, similarly to the central portion of the medium. Ink droplets are ejected, and in subsequent passes, ink droplets are ejected on the background image from the ejection nozzles (カ ラ ー) of the color nozzle row Co over four passes. That is, a color image can be printed on the background image.

  Note that the nozzles arranged in the movement direction in the right diagram of FIG. 5 correspond to nozzles that form dot rows (hereinafter referred to as raster lines) along the movement direction. For example, four white nozzles (◯) and four color nozzles (▲) are arranged in the moving direction immediately upstream of the print start position (for the nozzles within the thick frame), which is a background image and a color image. Are printed in 4 passes each. In the right diagram of FIG. 5, four white nozzles (◯) and four color nozzles (▲) are arranged in the movement direction in the entire region from the print start position to the print end position. This also shows that images are formed in the upper and lower end printing as in the normal printing.

  In summary, in the printing method in the front printing mode in the comparative example, the background image is printed with the half nozzles (# 13 to # 24) on the upstream side in the transport direction of the white nozzle row W, and the transport direction of the color nozzle row Co. A color image is printed by the half nozzles (# 1 to # 12) on the downstream side. By doing so, a background image can be printed in a first pass and a color image can be printed on the background image in a later pass with respect to a predetermined area of the medium. Although not shown in the drawing, in the printing method in the reverse printing mode in the comparative example, conversely, the background image is printed by the half nozzles (# 1 to # 12) on the downstream side in the transport direction of the white nozzle row W, and the color nozzle row A color image is printed by the half nozzles (# 13 to # 24) on the upstream side in the Co conveyance direction. In the normal color mode, all the nozzles in the color nozzle row Co may be used, or half the nozzles in the color nozzle row Co may be used as in the surface printing mode.

  As described above, in the printing method of the comparative example, when the background image and the color image are printed in an overlapping manner, the nozzle that prints the image first is the nozzle that is positioned on the upstream side in the transport direction from the nozzle that prints the image later. By doing so, it is possible to make different paths for overlapping the background image and the color image for printing. However, in the printing method of the comparative example, printing of the subsequent image (color image) is started from the pass next to the pass in which the printing of the previous image (background image in FIG. 5) is completed. In other words, in the printing method of the comparative example (during upper end / lower end printing and normal printing), the drying time of the previous image is relatively short, and only the time required for one medium transport operation is required. Therefore, when the drying property of the image to be printed first is poor (for example, when the drying property of the ink is poor or the ink absorption property of the medium is poor), the drying of the image to be printed first does not proceed. The next color image is printed, the ink is smeared, and the image quality of the printed image is degraded. Therefore, an object of the present embodiment is to prevent blurring of a print image when a background image and a color image are printed in an overlapping manner.

=== About the Printing Method of the Present Embodiment ===
FIG. 6 is a diagram illustrating a state of upper end printing in the front printing mode in the printing method of the present embodiment, and FIG. 7 is a diagram illustrating a state of lower end printing in the front printing mode in the printing method of the present embodiment. Similar to the printing method of the comparative example, in the printing method of the present embodiment, the medium conveyance amount at the time of normal printing (equivalent to the time of normal image formation) is set to three times the nozzle pitch (3d), and at the time of upper end / lower end printing. The medium transport amount d (corresponding to the time of image formation at the edge of the medium) is made smaller than the medium transport amount 3d during normal printing. 6 and 7, pass 1 to pass 8 correspond to the upper end printing pass, and pass 18 to pass 25 correspond to the lower end printing pass.

  During normal printing, as shown in the head 41 in the left diagram of FIG. 6, among the nozzles belonging to the color nozzle row Co, nine nozzles (# 1 to # 9) on the downstream side in the transport direction are used as color image nozzles. Of the nozzles belonging to the white nozzle row W, nine nozzles (# 16 to # 24) on the upstream side in the transport direction are set as background image nozzles. Then, six drying nozzles (# 10 to # 15 · x) are provided between the color image nozzle (▲) and the background image nozzle (◯). Therefore, in normal printing, a predetermined area on the medium first faces a nozzle on the upstream side in the transport direction of the white nozzle row W, and then faces a drying nozzle (corresponding to a non-injection nozzle) in the center in the transport direction. Finally, it faces the nozzle on the downstream side in the transport direction of the color nozzle row Co. Ink droplets are not ejected from the drying nozzle. Therefore, the period in which the predetermined area of the medium faces the drying nozzle can be used as the image drying time, and the drying time from the end of printing the background image to the start of printing the color image is a comparative example. The printing method (FIG. 5) can be made longer.

  Further, in the printing method of the present embodiment, unlike the printing method of the comparative example described above (FIG. 5), the nozzles used at the upper and lower end printing are not fixed nozzles. In the printing method of the comparative example, printing is performed using the same nozzles as those for normal printing at the time of printing at the upper and lower ends. That is, the nozzles that print the background image are the half nozzles (# 13 to # 24) on the upstream side in the transport direction of the white nozzle row W, and the nozzles that print the color image are the half on the downstream side in the transport direction of the color nozzle row Co. Nozzles (# 1 to # 12). Therefore, the print start position is nozzle # 16 in pass 1, and the print end position is nozzle # 9 in pass 17. When two images are printed in a superimposed manner, the nozzle of the image to be printed first is set to the nozzle on the upstream side in the transport direction with respect to the nozzle of the image to be printed later. For this reason, if the nozzles at the top and bottom printing are the same as the nozzles during normal printing as in the comparative printing method, the upstream nozzle in the transport direction is used at the start of printing, and the downstream in the transport direction at the end of printing. The side nozzle will be used.

  In this printer, as shown in FIG. 4, printing is performed in a state where the medium S is sandwiched between the transport roller 22 and the paper discharge roller 23. Therefore, in the printing method of the comparative example, the margin amount at the upper end of the medium S is relatively large as shown in FIG. Specifically, the margin amount at the upper end of the medium is the total amount of the medium protrusion amount D from the head 41 and the nozzle lengths for 15 nozzles including the used nozzles (# 1 to # 12) of the color nozzle row Co. Become. Although not shown, the margin amount at the lower end of the medium S is relatively large, and the nozzle length for 15 nozzles including the used nozzles (# 13 to # 24) of the white nozzle row W and the medium from the head 41 protrude. The total amount with the amount D.

  On the other hand, in the printing method of the present embodiment, the nozzle on the downstream side (one direction side) in the transport direction is printed from the nozzles (# 16 to # 24) for printing the background image during normal printing, and the background image is printed at the upper end printing. In addition, the nozzles on the upstream side in the transport direction (other direction side) than the nozzles (# 1 to # 9) that print color images during normal printing are used to print color images during bottom edge printing. To do.

  Specifically, as shown in FIG. 6, the nozzles # 8 to # 10 on the downstream side in the transport direction from the background image nozzles (# 16 to # 24) during normal printing are the nozzles of pass 1. Thereafter, the position of the background image nozzle is shifted upstream in the transport direction while increasing the number of background image nozzles (◯) in passes 1 to 8 of the upper end printing. Therefore, the print start position of the present embodiment is the position of nozzle # 8 in pass 1. Therefore, in the present embodiment, the margin amount at the upper end of the medium is the total amount of the medium protrusion amount D from the head 41 and the nozzle length for seven nozzles, which is larger than the margin amount of the printing method of the comparative example (FIG. 5). Get smaller.

  Similarly, as shown in FIG. 7, lower end printing is performed using nozzles on the upstream side in the transport direction with respect to the color image nozzles (# 1 to # 9) during normal printing. In the lower-end printing pass 18 to pass 25, the position of the color image nozzles is shifted upstream in the transport direction while reducing the number of color image nozzles (（). Therefore, the print end position of the present embodiment is the position of nozzle # 17 in pass 25. Therefore, the margin amount at the lower end portion of the medium according to the present embodiment is the total amount of the medium protrusion amount D from the head 41 and the nozzle length for seven nozzles, and is smaller than the margin amount of the printing method of the comparative example.

  FIG. 8A and FIG. 8B are diagrams showing the sheet feeding position and the sheet discharging position of the medium S in another printer having a different transport unit 20. So far, as shown in FIG. 4, a printer that prints with the medium S sandwiched between both the transport roller 22 and the paper discharge roller 23 has been described as an example, but the present invention is not limited thereto. As shown in FIG. 8, the printer may have a variable feed position (cue position) and discharge position. In the printing method of the comparative example (FIG. 5), the upstream nozzle in the transport direction is used at the start of printing, and the downstream nozzle in the transport direction is used at the end of printing. Therefore, the paper supply position and the paper discharge position of the medium S are the positions shown in FIG. 8A. In this case, the margin amount of the medium S becomes small, but the position control range of the medium S (the length for controlling the position of the medium S in the transport direction) becomes long. If it does so, it will become easy to produce a conveyance error. For example, when the position of the conveyance direction of the medium S is controlled by the rotation amount (conveyance amount) of the conveyance roller 22 after the sensor on the upstream side in the conveyance direction detects the upper end portion of the medium S, the range of the conveyance control is The longer the length, the easier it is for transport errors to occur. When the paper feed position and the paper discharge position are in FIG. 8A, the amount of the medium S protruding from the head 41 increases, the transport unit 20 becomes large, and the medium S is likely to be jammed. I'm sorry.

  On the other hand, in the printing method of the present embodiment (FIGS. 6 and 7), the nozzle on the downstream side in the transport direction is used at the start of printing, and the nozzle on the upstream side in the transport direction is used at the end of printing. The paper feed position and the paper discharge position are the positions shown in FIG. 8B. That is, according to the printing method of the present embodiment, the position control range of the medium S can be shortened. Therefore, it is possible to suppress the conveyance error and to reduce the amount of the medium S protruding from the head 41.

  Further, in the printing method of the present embodiment, nozzles different from those used in normal printing are used during upper end printing and lower end printing. Even if the nozzles are not used in normal printing, the viscosity increase of the ink can be suppressed by using the nozzles at the upper end printing or the lower end printing. As a result, nozzle ejection defects can be suppressed, and the number of nozzle cleanings can be reduced. Further, by using more types of nozzles as in the printing method of the present embodiment, it is possible to reduce the difference in nozzle characteristics.

At the time of upper end printing, as the background image nozzle (◯) shifts to the upstream side in the transport direction, the drying nozzle (×) and the color image nozzle (▲) are also used. For example, in pass 6-8, the color image nozzles at the time of upper end printing are located on the downstream side in the carrying direction, but the color image nozzles (# 1 to # 9) at the time of normal printing are also located on the downstream side in the carrying direction. On the other hand, the drying nozzles (# 10 to # 15) for normal printing are located at the center of the nozzle row, whereas the drying nozzles for upper end printing (for example, nozzles # 5 to # 7 in pass 4) are Located downstream of the nozzle row.
In addition, when the lower end printing is performed, the background image nozzle (◯) and the drying nozzle (×) are not used as the color image nozzle (▲) shifts upstream in the transport direction. For example, in passes 18 to 20, the background image nozzles at the time of lower end printing are positioned on the upstream side in the transport direction, but the background image nozzles (# 16 to # 24) at the time of normal printing are also positioned on the upstream side in the transport direction. On the other hand, the drying nozzles (# 10 to # 15) for normal printing are located in the center of the nozzle row, whereas the drying nozzles for lower end printing (for example, nozzles # 18 to # 20 in pass 22) are Located upstream of the nozzle row.
In other words, the drying nozzle (×) is the same as the background image nozzle (◯) at the top edge printing and the color image nozzle (▲) at the bottom edge printing (▲). The nozzles are different from # 10 to # 15).

  By the way, in the printing method of the present embodiment, the medium transport amount during normal printing is 3d, which is three times the nozzle pitch d, and the medium is transported to the nozzles (head 41) in one pass during normal printing. It is shifted by 3 nozzles downstream in the direction. For this reason, during normal printing, printing is started and completed for each area on the medium on which three raster lines (dot rows along the moving direction) are formed (for every three squares in the figure). For example, in the right diagram of FIG. 6, the uppermost stream side nozzle (◯) and the most downstream side nozzle (▲) in pass 9 of normal printing are respectively equal to the length of three raster lines in the next pass 10. It can also be seen from the fact that it is shifted to the upstream side in the transport direction (only for 3 squares). Also, as with the spray nozzles that form each image, it can be seen from the figure that the drying nozzles (×) between the spray nozzles are also shifted by three nozzles (three squares) upstream in the transport direction for each pass. .

  For this reason, during normal printing, the number of nozzles for printing the background image and the color image is set to the number of nozzles belonging to an area that is an integral multiple of the medium transport amount 3d. Here, as shown in FIG. 6, the number of nozzles for printing the background image and the color image is assumed to be the number of nozzles belonging to the region having a length (9d) three times the medium transport amount 3d, that is, nine. By doing so, the number of passes for printing each image during normal printing can be made constant at 3 times (3 nozzles). Similarly, during normal printing, the number of nozzles for drying is the number of nozzles belonging to a region having a length that is an integral multiple of the medium transport amount 3d. Here, as shown in FIG. 6, the number of nozzles for drying is set to the number of nozzles belonging to an area having a length (6d) twice the medium transport amount 3d, that is, six. By doing so, the number of passes of the medium facing the drying nozzle during normal printing can be made constant at two times. This can also be seen from the fact that three white nozzles, two drying nozzles, and three color nozzles are lined up in the movement direction, as indicated by the nozzles surrounded by a thick frame in the normal printing region.

  That is, at the time of normal printing, the background image and the color image are printed with the number of nozzles (9 nozzles) belonging to an area that is an integral multiple (3 times in the figure) of the medium conveyance amount 3d (during normal printing). The nozzles on the downstream side in the transport direction from the nozzles (# 16 to # 24) for printing the background image, and the nozzles on the upstream side in the transport direction from the nozzles (# 1 to # 9) for printing the color image. The number (six nozzles) of nozzles belonging to a region having a length that is an integral multiple of the medium transport amount 3d (twice in the figure) is defined as drying nozzles (# 10 to # 15). As a result, the background image and the color image can be printed with the same number of passes (number of nozzles) over the entire area of the image formed by normal printing. In addition, the number of passes in which the medium faces the drying nozzle during printing of the background image and the color image can be made constant.

  As described above, according to the normal printing of the present embodiment, the ink droplets are not ejected twice after the background image printing is completed until the color image printing is started (hereinafter also referred to as a drying pass). ) Can be provided. As a result, the drying time of the background image can be made longer than the printing method of the comparative example (FIG. 5), and bleeding of the image can be suppressed. Even if the drying time of the background image can be secured for a long time, if the drying time (number of drying passes) varies depending on the location of the background image, the background image and the color image have different bleeding depending on the location of the image. End up. As a result, density unevenness occurs in the image. On the other hand, in the present embodiment, the drying time (the number of drying passes) of the background image can be made constant over the entire area of the image formed by normal printing. As a result, it is possible to suppress image density unevenness due to variations in drying time.

  Further, it is preferable to perform the same printing as the normal printing (how to form dots) as much as possible even during the upper and lower end printing. That is, it is preferable to start printing for every area (every 3 squares) on the medium where the three raster lines are formed even at the top and bottom printing. However, when printing at the upper and lower ends, the dots cannot be filled unless the medium transport amount d is made smaller than the medium transport amount 3d during normal printing. Therefore, in the upper end printing, the nozzles shifted to the upstream side in the transport direction are used up to two nozzles while increasing the number of ejection nozzles for each pass. For example, in pass 1 of FIG. 6, nozzles # 8 to # 10 in the white nozzle row W are used, whereas in pass 2, nozzles # 7 to # 12 are used, and in pass 3, nozzles # 6 to ## are used. 14 is used. As a result, the medium conveyance amount at the time of upper end printing is the nozzle pitch d (for one square), but for each area on the medium on which three raster lines are formed (every three squares) as in normal printing. Printing starts and printing is completed. This can also be seen from the fact that the most upstream nozzle among the injection nozzles in each pass is shifted by 3 squares upstream in the transport direction in the right diagram of FIG. Also, as the pass progresses, the drying nozzle (×) and the color image nozzle (▲) are also used, but these nozzles are also 3 squares upstream in the transport direction for each pass, as shown in the right figure of FIG. It's off.

  On the other hand, in the lower end printing, for each pass, the number of ejection nozzles is reduced, and the most downstream nozzle among the ejection nozzles is shifted to two upstream in the transport direction. For example, in pass 23 of FIG. 7, nozzles # 11 to # 19 of the color nozzle row Co are used, whereas in pass 24, nozzles # 13 to # 18 of the color nozzle row Co are used, and in pass 25, color nozzles are used. Nozzles # 15- # 17 in row Co are used. As a result, the medium conveyance amount at the lower end printing is the nozzle pitch d (for one square), but as in the normal printing, for each area on the medium on which three raster lines are formed (every three squares). Printing starts and printing is completed. This can also be seen from the fact that in FIG. 7, the most downstream nozzle of the nozzles in each pass is shifted by 3 squares upstream in the transport direction. Further, as the pass progresses, the number of background image nozzles (◯) and the number of drying nozzles (×) also decreases. As shown in FIG. 7, these nozzles are also 3 squares upstream in the transport direction for each pass. It's off.

  As described above, in the upper-end / lower-end printing, printing is started for each area (every three squares) on the medium on which three raster lines are formed, as in normal printing, and printing is completed. That is, the number of raster lines formed for each pass during normal printing is equal to the number of raster lines formed for each pass during upper and lower end printing. For this reason, even when printing at the upper and lower ends, the number of nozzles for printing the background image and the color image may be set to the number of nozzles belonging to an area that is an integral multiple of the medium transport amount 3d (corresponding to a predetermined transport amount). . However, at the time of printing at the upper and lower ends, the number of nozzles for forming an image is gradually increased or decreased.

  Specifically, at the time of upper end printing in the present embodiment (FIG. 6), for example, the number of background image nozzles for pass 1 is 3, the number of background image nozzles for pass 2 is 6, and the background image for pass 3 is used. Nine nozzles, three color image nozzles for pass 6, six color image nozzles for pass 7, and nine color image nozzles for pass 8. That is, the number of background image nozzles and the number of color image nozzles in each pass are increased for each number of nozzles corresponding to the length of the transport amount 3d during normal printing, not the transport amount d during upper-end printing. To go. That is, in FIG. 6, 3 nozzles are increased. In addition to the nozzles that form the image, the number of drying nozzles is also increased by the number of nozzles (3 nozzles) corresponding to the length of the transport amount 3d during normal printing. For example, the number of drying nozzles in pass 4 is 3 (1 ×), while the number of drying nozzles in pass 5 is 6 (2 ×). In other words, in the upper end printing of the present embodiment, the length in the transport direction of the area to which the nozzle that forms each image belongs in each pass, and the length in the transport direction of the area to which the drying nozzle belongs in each pass are normally set. The length is an integral multiple of the medium transport amount 3d during printing.

  By doing so, as in normal printing, the number of passes for forming each image during top-end printing can be kept constant at 3 times (3 nozzles), and the number of drying passes is also 2 times (nozzle for drying). The number can be fixed to 2). This can also be seen from the fact that the nozzles arranged in the movement direction in the upper end printing region in FIG. 6 are three white nozzles, two drying nozzles, and three color nozzles.

  Similarly, at the lower end printing (FIG. 7), for example, the number of background image nozzles in pass 18 is nine, the number of background image nozzles in pass 19 is six, and the number of background image nozzles in pass 20 is three. The number of the 23 color image nozzles is nine, the number of the color image nozzles in the pass 24 is six, and the number of the color image nozzles in the pass 25 is three. That is, the number of background image nozzles and the number of color image nozzles in each pass are not the transport amount d at the lower end printing, but the number of nozzles corresponding to the length of the transport amount 3d at the normal printing (3 Reduce each nozzle). In addition, the number of drying nozzles is also decreased by the number of nozzles (3 nozzles) corresponding to the length of the transport amount 3d during normal printing. For example, the number of drying nozzles in pass 21 is six (2 times), whereas the number of drying nozzles in pass 22 is three (1 time). In other words, even during bottom-end printing, the length in the transport direction of the area to which the nozzles that form each image in each pass belong, and the length in the transport direction of the area to which the drying nozzle belongs are the media transport amount during normal printing. The length is an integral multiple of 3d. By doing so, as in normal printing, the number of passes for printing each image can be kept constant at 3 times (3 nozzles) and the number of drying passes can also be 2 times (drying). The number of nozzles for use can be constant. This can also be seen from the fact that the nozzles arranged in the movement direction in the lower end printing region in FIG. 7 are three white nozzles, two drying nozzles, and three color nozzles.

To summarize the above, in the upper and lower end printing, the nozzle on the downstream side in the transport direction from the nozzle for the background image (◯), and the nozzle on the upstream side in the transport direction from the nozzle for the color image (▲) By setting (x), a drying pass can be provided between the background image and the color image. As a result, it is possible to lengthen the drying time of the background image and suppress blurring of the image as compared with the upper end / lower end printing (FIG. 5) of the comparative example.
In upper-end / lower-end printing, the length in the conveyance direction of the region to which the nozzle that prints an image in each pass is set to an integral multiple of the medium conveyance amount 3d for normal printing. By doing so, the number of passes (number of nozzles) for printing each image in the top and bottom printing can be made constant, and the number of passes for forming each image in the top and bottom printing and each pass in normal printing. The number of passes for forming an image can be made equal, and printing control becomes easy.
In top / bottom printing, the length in the transport direction of the region to which the drying nozzle belongs is set to an integral multiple of the medium transport amount 3d for normal printing. By doing so, the number of dry passes (2 passes) can be made constant in the upper and lower end printing. That is, since the images formed in the upper and lower end printing have a constant background image drying time, the occurrence of uneven density is suppressed. Furthermore, in this embodiment, since the number of drying passes for top and bottom printing is equal to the number of drying passes for normal printing, the background image is dried over the entire area of the image formed by top and bottom printing and normal printing. Time can be kept constant. Therefore, the occurrence of uneven density can be suppressed.

  As described above, the nozzle that forms the background image and the color image and the nozzle for drying are set to the nozzles belonging to the nozzle row even if the printer driver sets the print data. It may be set when the controller 10 in the printer 1 that has received the print data from the printer driver assigns the print data to each nozzle.

  FIG. 9 is a diagram illustrating a printing method of a comparative example in which the number of drying nozzles is varied. FIG. 9 shows printing in the front printing mode, in which the number of background image nozzles (◯) during normal printing is eleven, the number of color image nozzles (▲) is eleven, and the drying nozzle (×). The number of is assumed to be two. That is, in the printing method of FIG. 9, unlike the printing method of the present embodiment, the length (2d) in the conveyance direction of the region to which the drying nozzle belongs is a non-integer multiple of the medium conveyance amount (3d) during normal printing. (2/3 times).

  The medium conveyance amount during normal printing is 3d, which is three times the nozzle pitch d, and the medium is shifted by three nozzles downstream of the nozzle (head 41) in the conveyance direction in one pass during normal printing. Become. Therefore, if the number of drying nozzles is set to a number corresponding to a non-integer multiple of the medium transport amount 3d, for example, the drying nozzle (x) is transported from pass 9 to pass 10 during normal printing in FIG. When shifted by 3 nozzles on the upstream side in the direction, a medium region that cannot face the drying nozzle is generated. As a result, in an image printed by normal printing, there are an area where a dry pass is provided and an area where no dry pass is provided, resulting in uneven density in the image.

  The medium transport amount d for upper and lower end printing is set to be shorter than the medium transport amount 3d for normal printing. However, in the upper-end / lower-end printing, printing is started for each area (every three squares) on the medium on which three raster lines are formed, as in the normal printing area, and printing is completed. Therefore, as shown in FIG. 9, at the time of printing at the upper and lower ends, the drying nozzle (x) is shifted to the upstream side in the transport direction by three nozzles (three squares) with respect to the medium for each pass. As a result, there are a medium area that faces the drying nozzle and a medium area that cannot face the drying nozzle.

  That is, in the upper-end / lower-end printing, similarly to the normal printing, if the length in the conveyance direction of the region to which the drying nozzle belongs (2d in the drawing) is set to a non-integer multiple of the medium conveyance amount 3d in the normal printing. As a result, the drying time of the background image varies, and the image has uneven density. In FIG. 9, the case where the length 2d in the transport direction of the region to which the drying nozzle belongs is smaller than the medium transport amount 3d during normal printing is described as an example, but the present invention is not limited to this. For example, if the number of drying nozzles is four and the length in the transport direction of the region to which the drying nozzle belongs (for example, 4d) is a non-integer multiple (4/3 times) greater than the medium transport amount 3d, the drying is performed. Variations will occur in time. In this case, all the medium regions face the drying nozzles, but the number of the facing drying nozzles differs depending on the location of the medium. Therefore, as in the printing method of the present embodiment described above (FIGS. 6 and 7), in top / bottom printing, the length in the transport direction of the area to which the drying nozzle belongs is an integral multiple of the medium transport amount 3d for normal printing. And

  Further, in the printing method of this comparative example, in the upper end / lower end printing and the normal printing, the length in the transport direction of the area to which the nozzle for printing each image belongs is also a non-integer multiple of the medium transport amount 3d during the normal printing. Yes. Therefore, dots are formed by four passes (four nozzles) or dots are formed by three passes (three nozzles) by the raster line. This complicates printing control. Therefore, as in the printing method of the present embodiment described above, it is preferable that the length in the transport direction of the area to which the nozzles for printing each image belong is also an integral multiple of the medium transport amount 3d for normal printing.

  In the above description, the “front printing mode” has been described as an example. However, the present invention is not limited to this. Even in the reverse printing mode in which a color image is first printed on a medium and a background image is printed thereon, it is preferable to provide a drying pass while printing each image. In the reverse printing mode, the nozzles may be reversed from the front printing mode. In the reverse printing mode, the color image nozzle (▲) in FIGS. 6 and 7 is used as the background image nozzle (◯), and the background image in FIGS. The color nozzle (◯) may be a color image nozzle (▲). However, the position of the drying nozzle (x) is the same in both the front printing mode and the back printing mode.

=== Modification ===
FIG. 10 is a diagram illustrating a printing method in the front printing mode in which the number of drying nozzles is changed. In the above-described embodiments (FIGS. 6 and 7), in the upper end / lower end printing, the length 6d in the transport direction of the area to which the drying nozzle belongs is set to twice the medium transport amount 3d for normal printing. Not limited to this. The number of drying nozzles may be changed in accordance with the drying property of the image to be printed first (background image in FIG. 10). If the image to be printed first has good drying properties, the number of drying nozzles is reduced to, for example, the number of nozzles “3” corresponding to 1 times the normal printing medium transport amount 3d as in the printing method of FIG. May be. In this case, in the entire area of the image, the number of drying passes between the printing of the background image and the color image is “one time”, and uneven density of the image can be suppressed. On the other hand, if the image to be printed first has poor drying properties, the number of drying nozzles may be increased.

  Further, not only the drying nozzle but also the length in the transport direction of the region to which the nozzle for printing each image belongs is preferably set to an integral multiple of the medium transport amount 3d for normal printing. In FIG. 10, there are 24 nozzles belonging to one nozzle row, and the number of drying nozzles is three. Therefore, the number of nozzles for printing each image may be nine, and the remaining three nozzles (shaded portions in the figure) may not be used. By doing so, the number of passes for forming each image can be made constant (three nozzles) over the entire area of the image.

  FIG. 11 is a diagram illustrating a printing method in which the nozzles for upper and lower end printing and the nozzles for normal printing are the same. In the above-described embodiment (FIGS. 6 and 7), in order to shorten the position control range of the medium (for example, to reduce the amount of blank space of the medium), in the upper end printing, the nozzle for background image of normal printing (◯) In addition, the nozzle on the downstream side in the transport direction is used from the nozzle for drying (×), and the nozzle on the upstream side in the transport direction is used for the color image nozzle (▲) and the nozzle for drying (×) for normal printing in the lower end printing. However, it is not limited to this. As shown in FIG. 11, the position of the color image nozzles (# 1 to # 9), the position of the drying nozzles (# 10 to # 15), and the position of the drying nozzles (# 10 to # 15) are the same as during normal printing at the top and bottom printing. The positions of the background image nozzles (# 16 to # 24) may be fixed.

  Even in this case, in upper end / lower end printing and normal printing, the length in the transport direction of the region to which the drying nozzle belongs is set to an integral multiple of the medium transport amount 3d during normal printing, so that the entire image area The number of drying passes can be made constant, and unevenness in image density can be suppressed. However, in contrast to the printing method of the comparative example having no drying nozzle in FIG. 5, the printing start position is more upstream in the transport direction and the print end position is more in the transport direction in FIG. Downstream side. Therefore, in the case where the drying nozzles are provided as in the above-described printing method (FIGS. 6 and 7), it is particularly effective to make the upper end printing and lower end printing nozzles variable, and the position control range of the medium can be reduced. An effect of reducing (an effect of reducing the amount of margin) is obtained.

=== Other Embodiments ===
Each of the above embodiments has been described mainly for a printing system having an ink jet printer, but includes disclosure of a method for correcting density unevenness. 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.

<Normal printing drying nozzle>
In the above-described embodiment, the length in the transport direction of the region to which the normal printing drying nozzle belongs is set to be an integral multiple of the medium transport amount during normal printing, but is not limited thereto. The drying time of the image formed by printing by making the length in the transport direction of the area to which at least one of the drying nozzles of the upper end printing and the lower end printing belongs to an integral multiple of the medium transport amount during normal printing Can be made constant. In the above-described embodiment, the length in the transport direction of the region to which the nozzles forming the background image and the color image belong is also an integral multiple of the medium transport amount during normal printing, but is not limited thereto.

<Printing multiple images>
In the above-described embodiment, the case where two images are printed is shown, but the present invention is not limited to this. Even when three or more images are printed in an overlapping manner, it is preferable that the nozzle of the image to be printed first is a nozzle on the upstream side in the transport direction with respect to the nozzle of the image to be printed later, and a drying nozzle is provided therebetween. Further, drying nozzles may be provided or the number of drying nozzles provided between them may be varied depending on the drying properties of the image.

<About background images>
In the above-described embodiment, the background image is printed with the white ink. However, the present invention is not limited to this, and the background image may be printed with a color ink other than white (for example, metallic ink). Further, the background image is not limited to printing only with the white ink, and the background image with the white color adjusted may be printed by mixing the white ink with another color ink. Further, a color image may be printed by adding white ink to four-color ink (YMCK).

<Other printers>
In the above-described embodiment, the printer that repeats the operation of forming an image while moving the head 41 in the movement direction and the operation of conveying the medium in the conveyance direction is described as an example. For example, an operation of forming an image while moving the head 41 along the conveyance direction of the continuous paper and an operation of moving the head 41 in the paper width direction intersecting the medium conveyance direction with respect to the continuous paper conveyed to the printing area And a printer that forms an image by alternately repeating, and then transports a portion of the continuous paper that has not yet been printed to the printing area.

<About nozzle arrangement>
In the above-described embodiment, as shown in FIG. 3, the four nozzle rows that respectively eject four-color inks (YMCK) are arranged in the movement direction, but the present invention is not limited to this. For example, two color nozzle rows out of four color nozzle rows may be arranged in the transport direction, and two color nozzle rows grouped in the transport direction may be arranged in the movement direction. Then, the length of the white nozzle row W is set to the length corresponding to the nozzle row of two colors. Even in such a printer, for example, in order to implement the front printing mode, the nozzle row on the upstream side of the two color nozzle rows arranged in the transport direction uses half of the nozzles on the downstream side in the transport direction, and the downstream side In this nozzle row, half of the nozzles on the upstream side in the transport direction may be used, and in the white nozzle row W, 1/4 of the nozzle on the most upstream side in the transport direction may be used. Also in this case, the number of drying nozzles corresponding to an integral multiple of the medium conveyance amount during normal printing is provided between the jet nozzles of the white nozzle row W and the four-color jet nozzles in the upper and lower end printing. And good.

<About the printing method>
In the above-described embodiment, overlap printing is taken as an example, but the present invention is not limited to this. Other printing methods (for example, a printing method in which a plurality of raster lines are formed in different passes between raster lines arranged at a nozzle pitch d as in interlaced printing) may be used.

<About fluid ejection device>
In the above-described embodiment, the ink jet printer is exemplified as the fluid ejecting apparatus, but the present invention is not limited thereto. The fluid ejecting apparatus can be applied to various industrial apparatuses instead of a printer. For example, a textile printing apparatus for applying a pattern to a fabric, a display manufacturing apparatus such as a color filter manufacturing apparatus or an organic EL display, a DNA chip manufacturing apparatus for manufacturing a DNA chip by applying a solution in which DNA is dissolved to a chip, and the like. Also, the present invention can be applied.
The fluid ejection method may be a piezo method in which fluid is ejected by applying a voltage to the drive element (piezo element) to expand and contract the ink chamber, or bubbles are generated in the nozzle using a heating element. It is also possible to use a thermal method in which liquid is ejected by the bubbles. The ink ejected from the head 41 may be ultraviolet curable ink that is cured when irradiated with ultraviolet rays, or powder may be ejected from the head.

1 printer,
10 controller, 11 interface unit, 12 CPU,
13 memory, 14 unit control circuit, 20 transport unit,
21 paper feed roller, 22 transport roller, 23 paper discharge roller,
30 Carriage unit, 31 Carriage,
40 head units, 41 heads,
50 detector groups, 60 computers

Claims (6)

A first nozzle row in which nozzles that eject a fluid forming a color image are arranged in a predetermined direction;
Arranged in the moving direction crossing the front Symbol first nozzle array and the predetermined direction, and a second nozzle row in which the nozzles for ejecting a fluid to form a background image overlapping the color image arranged in the predetermined direction,
An operation for ejecting fluid from the nozzles while relatively moving before Symbol first nozzle row and the second nozzle array and the medium and the moving direction, of the medium body with respect to the first nozzle row and the second nozzle array An operation of relatively moving the relative position in one direction of the predetermined direction,
In normal imaging, the control unit for relatively moving the predetermined conveyance amount of the relative position to the direction of the predetermined direction of the medium member relative to the first nozzle row and the second nozzle array,
Have,
Among the color image and the background image, the nozzle that forms the upper layer image is the nozzle located on the one direction side in the predetermined direction with respect to the nozzle that forms the lower layer image ,
The non-ejection nozzle, which is the nozzle to which no fluid is ejected, is positioned on the one direction side in the predetermined direction with respect to the nozzle that forms the lower layer image during the image formation of the edge of the medium, and the upper layer The length in the predetermined direction of the region to which the non-injecting nozzle belongs is located on the other side of the predetermined direction with respect to the nozzle that forms the image, and is an integral multiple of the predetermined conveyance amount,
Fluid jet apparatus characterized. The fluid ejection device according to claim 1,
During normal image formation, another non-ejection nozzle that is the nozzle from which fluid is not ejected is positioned on the one direction side in the predetermined direction with respect to the nozzle that forms the lower layer image, and the upper layer image. The length in the predetermined direction of the region to which the other non-injecting nozzle belongs is a length that is an integral multiple of the predetermined conveyance amount.
Fluid ejection device. The fluid ejecting apparatus according to claim 2,
At the time of image formation at the end portion on the one direction side in the predetermined direction of the medium,
It said nozzle to form an image of the lower layer, than the nozzle to form an image of the lower layer in the normal image forming time and the nozzles located in the one direction side of the predetermined direction,
The non-ejecting nozzle is the nozzle located on the one direction side in the predetermined direction with respect to the other non-ejecting nozzle during normal image formation.
Fluid ejection device. The fluid ejecting apparatus according to claim 2 or 3,
When forming an image of an end of the medium on the other direction side in the predetermined direction,
It said nozzle to form an image of the upper layer than the nozzle to form an image of the upper layer in the normal image forming time and the nozzle located at the other side of the predetermined direction,
The non-ejecting nozzle is the nozzle located on the other direction side in the predetermined direction with respect to the other non-ejecting nozzle during normal image formation.
Fluid ejection device. The fluid ejection device according to any one of claims 1 to 4,
The length in the predetermined direction of the area to which the nozzle forming at least one of the lower layer image and the upper layer image is an integral multiple of the predetermined transport amount,
Fluid ejection device. A first nozzle row in which nozzles that eject a fluid forming a color image are arranged in a predetermined direction, and a background image that is arranged in a moving direction that intersects the first nozzle row and the predetermined direction and overlaps the color image are formed. An operation of ejecting fluid from the nozzle while relatively moving a second nozzle row in which nozzles for ejecting fluid are arranged in the predetermined direction and a medium in the moving direction; and the first nozzle row and the second nozzle the fluid ejecting method of a fluid ejecting apparatus repeats an operation for relatively moving the relative position of the medium member in the predetermined direction of the direction for the column,
In normal imaging, and causing a relative position of the medium body with respect to the first nozzle row and the second nozzle array are relatively moved a predetermined carry amount to said one direction of said predetermined direction,
Of the color image and the background image, the nozzle that forms the upper layer image is the nozzle located on the one direction side in the predetermined direction with respect to the nozzle that forms the lower layer image, and the edge of the medium When the image is formed, it is located on the one direction side in the predetermined direction with respect to the nozzle that forms the lower layer image , and is located on the other direction side in the predetermined direction with respect to the nozzle that forms the upper layer image. The nozzle does not eject fluid from the nozzle belonging to a region whose length in the predetermined direction is an integral multiple of the predetermined transport amount;
A fluid ejection method comprising:

Images