JP2020062788A - Ink-jet printer - Google Patents

Abstract

To provide an ink-jet printer capable of suppressing a decrease in printing quality of printing media even when ink jetted from a path column jetting the ink last into an area of the printing medium divided by constant bandwidth in a sub-scanning direction can be reliably hardened while downsizing an ultraviolet-light irradiator in the sub-scanning direction in the ink-jet printer which prints on printing media by a multipath system.SOLUTION: In an ink-jet printer which prints on printing media in a multipath system, illuminance of a final irradiation part 4d of an ultraviolet irradiation part 4 irradiating ultraviolet to a division printing region PA of a printing medium 2 last is higher than illuminance of the remaining irradiation parts 4a to 4c excluding the final irradiation part 4d. Illuminance of the final irradiation part 4d is not constant in a sub-scanning direction but varies in the sub-scanning direction.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an inkjet printer that prints on a print medium by a multi-pass method.

  2. Description of the Related Art Conventionally, an inkjet printer that prints on a print medium by a multi-pass method has been known (for example, see Patent Document 1). The inkjet printer described in Patent Document 1 includes an inkjet head that ejects ultraviolet curable ink, a head drive mechanism that moves the inkjet head in the main scanning direction, and a medium feed mechanism that feeds the print medium in the sub-scanning direction. ing. The inkjet head is formed with a nozzle array including a plurality of nozzles arranged in the sub-scanning direction. In an inkjet printer, the inkjet head is generally mounted on a carriage, and the carriage moves in the main scanning direction.

  When the inkjet printer described in Patent Document 1 prints on a print medium in four passes, for example, the nozzle row is divided into four first pass rows to fourth pass rows in the sub-scanning direction. The width of the first pass row to the fourth pass row in the sub-scanning direction is a constant band width. The medium feeding mechanism feeds the print medium in the sub-scanning direction by the same amount as the bandwidth when printing the print medium.

  In the inkjet printer described in Patent Document 1, an operation in which an inkjet head ejects ink while moving in the main scanning direction and an operation in which a medium feeding mechanism feeds a print medium in the sub-scanning direction by the same amount as the bandwidth are alternately performed. Then, the ink is sequentially ejected from the first pass row, the second pass row, the third pass row, and the fourth pass row to a predetermined area of the print medium defined by the bandwidth. That is, ink is finally ejected from the fourth pass row to a predetermined area of the print medium defined by the bandwidth.

International Publication No. 2012/67064

  In an inkjet printer that prints on a print medium using an ultraviolet curable ink like the inkjet printer described in Patent Document 1, generally, ultraviolet irradiation is applied to cure ink by irradiating the ink ejected from an inkjet head with ultraviolet light. Is mounted on the carriage. In the inkjet printer described in Patent Document 1, in order to reliably cure the ink ejected from the fourth pass row, as shown in FIG. 7A, the sub-scanning of the ultraviolet irradiator 101 mounted on the carriage is performed. The width in the direction is longer than the length of the nozzle row 103 of the inkjet head 102, and after the ink is ejected from the fourth pass row 103d, the carriage of the carriage after the medium feeding mechanism feeds the print medium in the sub-scanning direction. Also during operation, it is preferable that the ultraviolet ray irradiator 101 irradiate the ink ejected from the fourth pass row 103d with ultraviolet rays.

  That is, it is preferable that the ultraviolet irradiator 101 extends to the downstream side of the nozzle row 103 in the transport direction (direction of arrow V in FIG. 7) of the print medium during printing. In FIG. 7, the nozzle row 103 is divided into a first pass row 103a, a second pass row 103b, a third pass row 103c, and a fourth pass row 103d in the sub-scanning direction. The first pass row 103a, the second pass row 103b, the third pass row 103c, and the fourth pass row 103d are arranged in this order toward the downstream side in the transport direction of the print medium during printing.

  On the other hand, as shown in FIG. 7A, when the UV irradiator 101 extends to the downstream side of the nozzle array 103 in the print medium conveyance direction, the UV irradiator 101 becomes large in the sub-scanning direction. As a result, the carriage becomes large in the sub-scanning direction. Therefore, the present inventor downsizes the ultraviolet irradiator 101 in the sub-scanning direction, and in order to surely cure the ink ejected from the fourth pass row 103d, the inventor of the present invention makes it possible to reduce the size of the ultraviolet irradiator 101 in the fourth sub-scanning direction. The illuminance of a portion arranged at the same position as the pass row 103d (hereinafter, this portion is referred to as an “ultraviolet ray irradiation unit 101a”) is higher than the illuminance of other portions of the ultraviolet ray irradiator 101 excluding the ultraviolet ray irradiation unit 101a. Also considered to be higher.

  For example, as shown in FIG. 7B, it was examined to increase the illuminance of the ultraviolet irradiation unit 101a by widening the width of the ultraviolet irradiation unit 101a in the main scanning direction. Further, according to the study by the inventors of the present application, it has been clarified that the ink ejected from the fourth pass row 103d can be reliably cured by increasing the illuminance of the ultraviolet irradiation unit 101a.

  However, if the illuminance of the ultraviolet irradiation unit 101a is simply increased until the ink ejected from the fourth pass row 103d is reliably cured, all the ink ejected from the fourth pass row 103d will not be discharged from the first pass row 103a. Since the ink ejected from the third pass column 103c cures more rapidly and at the same speed, the size of all the ink droplets ejected from the fourth pass column 103d after curing is the same as that of the first pass column 103a. ~ Ink ejected from the fourth pass row 103d in an image or the like printed on a print medium becomes a certain size smaller than the size of the ink droplets ejected from the third pass row 103c after curing. It has been clarified by the study of the inventor of the present application that the portion constituted by is easily noticeable. That is, it has been clarified by the inventors of the present application that the print quality of the print medium deteriorates if the illuminance of the ultraviolet irradiation unit 101a is simply increased until the ink ejected from the fourth pass row 103d is reliably cured. .

  Therefore, an object of the present invention is to provide an inkjet printer that performs printing on a print medium by a multi-pass method using an inkjet head in which a nozzle array having a plurality of pass arrays separated by a constant band width in the sub-scanning direction is formed. It is possible to reliably cure the ink ejected from the pass row that ejects ink last to the area of the print medium, which is divided by the band width in the sub-scanning direction, while reducing the size of the ultraviolet irradiation device in the sub-scanning direction. Even if it exists, it is providing the inkjet printer which can suppress the fall of the printing quality of a printing medium.

  In order to solve the above-mentioned problems, an inkjet printer of the present invention irradiates an inkjet head formed with a plurality of nozzles for ejecting an ultraviolet curable ink toward a print medium, and an ultraviolet ray to the ink ejected from the inkjet head. An ultraviolet irradiator that cures the ink, a carriage on which the inkjet head and the ultraviolet irradiator are mounted, a carriage drive mechanism that moves the carriage in the main scanning direction, and a vertical direction and a main scanning direction with respect to the carriage. And a feed mechanism that relatively feeds the print medium in the sub-scanning direction, and the carriage is moved in the main scanning direction and the print medium is relatively fed in the sub-scanning direction relative to the carriage alternately a plurality of times. , An inkjet printer that prints on a print medium by a multi-pass method. The nozzle array is formed with a plurality of nozzles arranged in the sub-scanning direction, and the nozzle array includes a plurality of pass arrays separated by a certain band width in the sub-scanning direction. The feeding mechanism includes a plurality of irradiation units divided in the scanning direction, and the feeding mechanism feeds the printing medium in the sub-scanning direction relative to the carriage by the same amount as the bandwidth when printing the printing medium, and printing of the printing medium is performed. The print area, which is an area, is composed of a plurality of divided print areas separated by a bandwidth in the sub-scanning direction, and the print medium is relatively sent to the carriage in the sub-scanning direction to at least a part of the divided print areas. Each time it is ejected, ink is ejected from a different pass row, and the last pass row that ejects the ink to the divided printing area among the plurality of pass rows is set as the final pass row. If the final irradiation unit is the irradiation unit that irradiates ultraviolet rays last to the divided printing area, the illuminance of the final irradiation unit is higher than the illuminance of the remaining irradiation units excluding the final irradiation unit. Is not constant in the sub-scanning direction but changes in the sub-scanning direction.

  In the inkjet printer of the present invention, the ultraviolet irradiator is provided with a plurality of irradiation units that are divided in the sub-scanning direction. Further, in the present invention, the last pass row in the plurality of pass rows for ejecting ink to the divided print areas is defined as the last pass row, and the last pass row in the plurality of irradiation units is set for the divided print areas. When the irradiation unit that irradiates ultraviolet rays is the final irradiation unit, the illuminance of the final irradiation unit is higher than the illuminance of the remaining irradiation units excluding the final irradiation unit. Therefore, in the present invention, it is possible to reliably cure the ink ejected from the final pass row by the final irradiation section. Therefore, according to the present invention, it is possible to surely cure the ink ejected from the final pass row while miniaturizing the ultraviolet irradiator in the sub-scanning direction.

  Further, in the present invention, the illuminance of the final irradiation unit is not constant in the sub scanning direction but changes in the sub scanning direction. Therefore, in the present invention, it is possible to vary the size of the ink droplets ejected from the final pass row after curing in the sub-scanning direction. Therefore, in the present invention, it is possible to make the portion formed by the ink ejected from the final pass row inconspicuous in the image or the like printed on the print medium, and as a result, the print quality of the print medium can be reduced. It is possible to suppress the decrease.

  In the present invention, the ultraviolet irradiator is provided with a plurality of light emitting elements, and for example, the number of light emitting elements that are turned on at the time of printing of the print medium in the final irradiation unit and are arranged in the main scanning direction is the final irradiation. The number of light-emitting elements that are turned on when printing the print medium in the remaining irradiation section excluding the number is larger than the number of light-emitting elements that are arranged in the main scanning direction, and the last irradiation section is turned on when printing the print medium. The number of light emitting elements arranged in the main scanning direction is not constant in the sub scanning direction but changes in the sub scanning direction.

  In this case, the number of light emitting elements arranged in the main scanning direction in the final irradiation unit is larger than the number of light emitting elements arranged in the main scanning direction in the remaining irradiation units excluding the final irradiation unit. It is preferable that the number of light emitting elements arranged in the main scanning direction in the final irradiation unit is not constant in the sub scanning direction but changes in the sub scanning direction. With this configuration, by simply causing all the light emitting elements of the ultraviolet irradiator to emit light, the illuminance of the final irradiation unit can be made higher than the illuminance of the remaining irradiation units excluding the final irradiation unit. The illuminance of the final irradiation unit can be changed in the sub-scanning direction. Therefore, the control of the ultraviolet irradiator becomes easy.

  In the present invention, the ultraviolet irradiator is provided with a plurality of light emitting elements, and the illuminance of the light emitting element that is turned on during printing of the print medium in the final irradiating unit is equal to that during printing of the print medium in the remaining irradiating unit except the final irradiating unit. The illuminance of the light emitting element is higher than that of the light emitting element to be turned on, and the illuminance of the light emitting element to be turned on during printing of the print medium in the final irradiating section is not constant in the sub-scanning direction but may be changed in the sub-scanning direction. .

  In the present invention, when the relative movement direction of the print medium, which is relatively fed in the sub-scanning direction with respect to the carriage during printing of the print medium, is the first direction, the illuminance of the final irradiation unit is the first direction side. It is preferable that the height becomes higher as it goes. With this configuration, even if the number of passes when printing on the print medium is increased (that is, the bandwidth is narrowed), the illuminance of the final irradiation unit is set to the illuminance of the remaining irradiation units excluding the final irradiation unit. It is possible to make the illuminance higher than the illuminance, and it is possible to change the illuminance of the final irradiation unit in the sub-scanning direction. Therefore, even in an ink jet printer in which the number of passes when printing on a print medium increases or decreases, it is possible to reliably cure the ink ejected from the final pass row while miniaturizing the ultraviolet irradiator in the sub-scanning direction. At the same time, it becomes possible to suppress deterioration of the print quality of the print medium.

  In the present invention, the ultraviolet irradiator preferably includes a plurality of light emitting elements and a single substrate on which all the light emitting elements of the ultraviolet irradiator are mounted. With this structure, the structure of the ultraviolet irradiator can be simplified and the cost of the ultraviolet irradiator can be reduced.

  In the present invention, the width of the substrate in the sub-scanning direction is preferably less than or equal to the width of the inkjet head in the sub-scanning direction. According to this structure, the ultraviolet irradiator can be further downsized in the sub-scanning direction.

  As described above, according to the present invention, an inkjet printer that performs printing on a print medium by a multi-pass method using an inkjet head in which a nozzle row having a plurality of pass rows separated by a constant band width in the sub-scanning direction is formed. In, while miniaturizing the ultraviolet irradiator in the sub-scanning direction, it is possible to reliably cure the ink ejected from the pass row that finally ejects the ink to the area of the print medium that is divided by the bandwidth in the sub-scanning direction. Even in this case, it is possible to suppress deterioration of the print quality of the print medium.

1 is a schematic diagram for explaining a configuration of an inkjet printer according to an embodiment of the present invention. FIG. 3 is a bottom view for explaining the configurations of the inkjet head and the ultraviolet irradiator shown in FIG. 1. FIG. 3 is a diagram for explaining an operation of the inkjet printer shown in FIG. 1 during printing. FIG. 3 is a diagram for explaining an operation of the inkjet printer shown in FIG. 1 during printing. It is a figure for demonstrating the structure of the ultraviolet irradiation device concerning other embodiment of this invention. It is a figure for demonstrating the structure of the ultraviolet irradiation device concerning other embodiment of this invention. It is a figure for demonstrating the problem of a prior art.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Structure of inkjet printer)
FIG. 1 is a schematic diagram for explaining the configuration of an inkjet printer 1 according to an embodiment of the present invention. FIG. 2 is a bottom view for explaining the configurations of the inkjet head 3 and the ultraviolet irradiator 4 shown in FIG. 3 and 4 are diagrams for explaining the operation of the inkjet printer 1 shown in FIG. 1 during printing.

  The inkjet printer 1 of the present embodiment (hereinafter, referred to as “printer 1”) is, for example, a commercial inkjet printer, and prints on the print medium 2. The print medium 2 is, for example, a print paper, a cloth or a resin film. The printer 1 includes an inkjet head 3 that ejects ink (hereinafter, referred to as “head 3”). The printer 1 according to this embodiment includes a plurality of heads 3. The head 3 ejects ultraviolet curable ink (UV ink).

  The printer 1 also includes an ultraviolet irradiator 4 that irradiates the ink ejected from the head 3 with ultraviolet rays to cure the ink, a carriage 5 on which the head 3 and the ultraviolet irradiator 4 are mounted, and a carriage 5 in the main scanning direction. A carriage driving mechanism 6 that moves the carriage 5 in the Y direction (FIG. 1 and the like), a guide rail 7 that guides the carriage 5 in the main scanning direction, a platen 8 on which the print medium 2 at the time of printing is placed, and a vertical direction (FIG. 1 and the like) and a medium feeding mechanism 9 for feeding the print medium 2 in the sub-scanning direction (X direction in FIG. 1, etc.) orthogonal to the main scanning direction. The medium feeding mechanism 9 of the present embodiment is a feeding mechanism that relatively feeds the print medium 2 in the sub-scanning direction with respect to the carriage 5.

  The printer 1 may include a guide shaft instead of the guide rail 7. Further, the printer 1 may include, in place of the platen 8 and the medium feeding mechanism 9, a table on which the print medium 2 is placed and a table feeding mechanism that feeds the table in the sub-scanning direction. The table feed mechanism in this case is a feed mechanism that relatively feeds the print medium 2 in the sub-scanning direction with respect to the carriage 5.

  The printer 1 of the present embodiment performs printing on the print medium 2 by the multi-pass method by alternately moving the carriage 5 in the main scanning direction and feeding the print medium 2 in the sub scanning direction a plurality of times. In the following description, the main scanning direction (Y direction) will be referred to as the “left and right direction” and the sub scanning direction (X direction) will be referred to as the “front and back direction”. Further, the X1 direction side in FIG. 1 or the like, which is one side in the front-rear direction, is the “front” side, and the X2 direction side in FIG. 1 or the like, which is the opposite side, is the “rear” side. In the present embodiment, when printing the print medium 2, the print medium 2 is fed in the forward direction. That is, the front direction (X1 direction) of the present embodiment is the first direction, which is the relative movement direction of the print medium 2 that is sent relative to the carriage 5 in the sub-scanning direction when the print medium 2 is printed. Has become.

  The carriage drive mechanism 6 is provided with, for example, two pulleys, a belt that is bridged over the two pulleys and partially fixed to the carriage 5, and a motor that rotates the pulleys. The carriage 5 is arranged above the platen 8. A plurality of heads 3 are mounted on the carriage 5. The plurality of heads 3 are mounted on the carriage 5 so as to be adjacent to each other in the left-right direction.

  The head 3 mounted on the carriage 5 ejects ink toward the upper surface of the print medium 2 mounted on the table 8. That is, the head 3 ejects the ink downward. A plurality of nozzles that eject ink toward the print medium 2 are formed on the lower surface of the head 3. The plurality of nozzles are arranged in the front-rear direction, and the nozzle row 12 is composed of the plurality of nozzles. That is, the head 3 is formed with a nozzle row 12 including a plurality of nozzles arranged in the sub-scanning direction.

  As described above, the printer 1 prints on the print medium 2 by the multi-pass method. The nozzle row 12 includes a plurality of pass rows 12a to 12d that are separated by a constant band width BW in the front-rear direction (sub scanning direction). For example, when the printer 1 prints on the print medium 2 in four passes, the nozzle row 12 includes four pass rows 12a to 12d. In this embodiment, the nozzle row 12 is composed of four pass rows 12a to 12d. That is, the nozzle row 12 is divided into four pass rows 12a to 12d in the front-rear direction.

  Each of the pass rows 12a to 12d is composed of a plurality of nozzles. The pass rows 12a to 12d are arranged in this order toward the front side, the pass row 12a constitutes the rear end of the nozzle row 12, and the pass row 12d constitutes the front end of the nozzle row 12. There is. The configuration of the ultraviolet irradiator 4 when the printer 1 prints on the print medium 2 in four passes will be described below.

  The ultraviolet irradiator 4 is mounted on the carriage 5 on both sides of the head 3 in the left-right direction. That is, the carriage 5 is equipped with two ultraviolet ray irradiators 4. The ultraviolet irradiator 4 includes a plurality of light emitting elements 13 and one substrate 14 on which the plurality of light emitting elements 13 are mounted. The light emitting element 13 is, for example, a UVLED chip that emits ultraviolet rays. All the light emitting elements 13 included in the ultraviolet irradiator 4 are mounted on one board 14. The number of the ultraviolet irradiators 4 mounted on the carriage 5 may be one.

  The width of the substrate 14 in the front-rear direction is less than or equal to the width of the head 3 in the front-rear direction. In this embodiment, the width of the substrate 14 in the front-rear direction is substantially equal to the width of the head 3 in the front-rear direction. In the front-back direction, the front end of the substrate 14 and the front end of the head 3 are arranged at substantially the same position. In addition, the range (width) in the front-rear direction of the portion where the plurality of light emitting elements 13 are arranged is equal to the length of the nozzle row 12. In the front-rear direction, the front end of the portion where the plurality of light emitting elements 13 are arranged and the front end of the nozzle row 12 are arranged at the same position.

  Further, the ultraviolet irradiator 4 includes a plurality of irradiation units 4a to 4d which are divided in the front-rear direction. Each of the plurality of irradiation units 4a to 4d is arranged at the same position as each of the path rows 12a to 12d in the front-back direction. That is, the ultraviolet irradiator 4 includes four irradiation units 4a to 4d that are separated by the band width BW in the front-rear direction, and the plurality of light emitting elements 13 that configure the ultraviolet irradiator 4 are four in the front-rear direction. Is divided into irradiation units 4a to 4d. The irradiation units 4a to 4d are arranged in this order toward the front side. That is, in the front-back direction, the irradiation unit 4a is arranged at the same position as the pass line 12a, the irradiation unit 4b is arranged at the same position as the pass line 12b, and the irradiation unit 4c is arranged at the same position as the pass line 12c. The irradiation unit 4d is arranged at the same position as the path line 12d.

  The medium feeding mechanism 9 includes, for example, a drive roller that contacts one surface of the print medium 2, a driven roller that is arranged to face the drive roller and that contacts the other surface of the print medium 2, and a motor that rotates the drive roller. And so on. The medium feeding mechanism 9 feeds the print medium 2 in the forward direction by the same amount as the band width BW when the print medium 2 is printed.

  The printing area, which is an area in which printing of the print medium 2 is performed, is composed of a plurality of divided printing areas PA that are separated by the band width BW in the front-rear direction. In the following, when each of the six divided print areas PA (six divided print areas PA continuous in the front-back direction) shown in FIGS. 3 and 4 is individually shown, each of the six divided areas PA is divided. The print areas PA1 to PA6 are set. The divided print areas PA1 to PA6 are arranged in this order toward the rear side.

  When the print medium 2 is printed, for example, first, the print medium 2 is fed until the divided print area PA1 is arranged at the same position as the pass row 12a in the front-back direction (see FIG. 3A). After that, while moving the carriage 5 in one of the left and right directions, ink is ejected from the pass row 12a to all or part of the divided print area PA1, and the ink ejected from the pass row 12a to the divided print area PA1 is irradiated. Ultraviolet rays are irradiated from 4a to cure the ink.

  After that, the print medium 2 is fed until the divided print area PA2 is arranged at the same position as the pass row 12a in the front-rear direction (see FIG. 3B). That is, in the front-back direction, the print medium 2 is fed in the front direction by the same amount as the band width BW until the divided print area PA1 is arranged at the same position as the pass row 12b. After that, while moving the carriage 5 in one of the left and right directions, ink is ejected from the pass row 12a to all or part of the divided print area PA2, and ink is ejected from the pass row 12b to all or part of the divided print area PA1. At the same time, the ink ejected from the pass row 12a to the divided print area PA2 is irradiated with ultraviolet rays from the irradiation section 4a to cure the ink, and the ink ejected from the pass row 12b to the divided print area PA1 is irradiated from the irradiation section 4b. Ultraviolet rays are irradiated to cure the ink.

  After that, the print medium 2 is fed until the divided print area PA3 is arranged at the same position as the pass row 12a in the front-rear direction (see FIG. 3C). That is, in the front-rear direction, the divided print area PA2 is arranged at the same position as the pass row 12b, and the divided print area PA1 is arranged at the same position as the pass row 12c by the same amount as the band width BW in the forward direction. Send 2. Then, while moving the carriage 5 in one of the left and right directions, ink is ejected from the pass row 12a to all or part of the divided print area PA3, and ink is ejected from the pass row 12b to all or part of the divided print area PA2. Then, the ink is ejected from the pass row 12c to the whole or a part of the divided print area PA1, and the ink ejected from the pass row 12a to the divided print area PA3 is irradiated with ultraviolet rays from the irradiation section 4a to cure the ink. , The ink ejected from the pass row 12b to the divided print area PA2 is irradiated with ultraviolet rays from the irradiation section 4b to cure the ink, and the ink ejected from the pass row 12c to the divided print area PA1 is irradiated with ultraviolet rays from the irradiation section 4c. Irradiate to cure the ink.

  After that, the print medium 2 is fed until the divided print area PA4 is arranged at the same position as the pass row 12a in the front-rear direction (see FIG. 4A). That is, in the front-back direction, the divided print area PA3 is arranged at the same position as the pass row 12b, the divided print area PA2 is arranged at the same position as the pass row 12c, and the divided print area PA1 is arranged at the same position as the pass row 12d. The print medium 2 is fed in the forward direction by the same amount as the bandwidth BW until the print medium 2 is reached.

  Then, while moving the carriage 5 in one of the left and right directions, ink is ejected from the pass row 12a to all or part of the divided print area PA4, and ink is ejected from the pass row 12b to all or part of the divided print area PA3. Then, ink is ejected from the pass row 12c onto all or part of the divided print area PA2, ink is ejected from the pass row 12d onto all or part of the divided print area PA1, and from the pass row 12a to the divided print area PA4. The ejected ink is irradiated with ultraviolet rays from the irradiation section 4a to cure the ink, and the ink ejected from the pass row 12b to the divided printing area PA3 is irradiated with ultraviolet rays from the irradiation section 4b to cure the ink. The ink ejected from the row 12c to the divided printing area PA2 is irradiated with ultraviolet rays from the irradiation unit 4c to cure the ink, and the pass row 12d By irradiating ultraviolet rays from the irradiation unit 4d to ink ejected et split printing area PA1 to cure the ink. When the ink is ejected from the pass row 12d to the divided print area PA1 and the ink is cured by the ultraviolet rays emitted from the irradiation unit 4d, the printing on the divided print area PA1 is completed.

  After that, the print medium 2 is fed until the divided print area PA5 is arranged at the same position as the pass row 12a in the front-rear direction (see FIG. 4B). That is, in the front-back direction, the divided print area PA4 is arranged at the same position as the pass row 12b, the divided print area PA3 is arranged at the same position as the pass row 12c, and the divided print area PA2 is arranged at the same position as the pass row 12d. The print medium 2 is fed in the forward direction by the same amount as the bandwidth BW until the print medium 2 is reached.

  Then, while moving the carriage 5 in one of the left and right directions, ink is ejected from the pass row 12a to all or part of the divided print area PA5, and ink is ejected from the pass row 12b to all or part of the divided print area PA4. Then, ink is ejected from the pass row 12c to all or part of the divided print area PA3, ink is ejected from the pass row 12d to all or part of the divided print area PA2, and at the same time from the pass row 12a to the divided print area PA5. The ejected ink is irradiated with ultraviolet rays from the irradiation section 4a to cure the ink, and the ink ejected from the pass row 12b to the divided printing area PA4 is irradiated with ultraviolet rays from the irradiation section 4b to cure the ink. The ink ejected from the row 12c to the divided print area PA3 is irradiated with ultraviolet rays from the irradiation unit 4c to cure the ink, and the pass row 12d By irradiating ultraviolet rays from the irradiation unit 4d to ink ejected et split printing area PA2 to cure the ink. When the ink is ejected from the pass array 12d to the divided print area PA2 and the ink is cured by the ultraviolet rays emitted from the irradiation unit 4d, the printing on the divided print area PA2 ends.

  Hereinafter, this operation is repeated to print the print medium 2. That is, the ink is ejected from different pass rows 12a to 12d to at least a part of each of the divided print areas PA every time the print medium 2 is fed in the same amount as the band width BW in the forward direction. When the ink is ejected from the pass row 12d to the divided print area PA and the ink is cured by the ultraviolet rays emitted from the irradiation unit 4d, the printing on the divided print area PA ends. The pass row 12d of the present embodiment is a final pass row that ejects the last ink to the divided print area PA. The irradiation unit 4d of the present embodiment is the final irradiation unit that finally irradiates the divided printing area PA with ultraviolet rays, and is arranged at the same position as the pass row 12d in the front-back direction (sub-scanning direction).

  When printing the print medium 2, the illuminance of the irradiation unit 4d, which is the final irradiation unit, is higher than the illuminance of each of the irradiation units 4a to 4c. For example, although the illuminances of the individual light emitting elements 13 of the irradiation sections 4a to 4d are equal, the light emitting elements 13 that are turned on when printing the print medium 2 in the irradiation section 4d and that are arranged in the left-right direction. Is larger than the number of light emitting elements 13 that are turned on when printing the print medium 2 in each of the irradiation units 4a to 4c and that are arranged in the left-right direction. Specifically, the number of light emitting elements 13 arranged in the left-right direction in the irradiation section 4d is larger than the number of light emitting elements 13 arranged in the left-right direction in each of the irradiation sections 4a to 4c.

  In the present embodiment, the number of light emitting elements 13 arranged in the left-right direction in the irradiation section 4a, the number of light emitting elements 13 arranged in the left-right direction in the irradiation section 4b, and the light-emitting elements arranged in the left-right direction in the irradiation section 4c. The number of 13 is the same, and when printing the print medium 2, the illuminance of the irradiation unit 4a, the illuminance of the irradiation unit 4b, and the illuminance of the irradiation unit 4c are equal. The number of light emitting elements 13 arranged in the left-right direction in each of the irradiation units 4a to 4c is constant in the front-back direction (sub-scanning direction), and the illuminance of each of the irradiation units irradiation units 4a to 4c is It is constant in the front-back direction. The irradiation parts 4a to 4c are formed in a square shape or a rectangular shape.

  On the other hand, when printing the print medium 2, the illuminance of the irradiation unit 4d is not constant in the front-rear direction (sub-scanning direction) but changes in the front-rear direction. For example, the number of the light emitting elements 13 that are turned on when printing the print medium 2 in the irradiation unit 4d and arranged in the left-right direction is not constant in the front-rear direction but changes in the front-rear direction. Specifically, the number of light emitting elements 13 arranged in the left-right direction in the irradiation unit 4d is not constant in the front-rear direction but changes in the front-rear direction. Further, in this embodiment, the illuminance of the irradiation unit 4d gradually increases toward the front side. That is, the number of the light emitting elements 13 arranged in the left-right direction in the irradiation unit 4d gradually increases toward the front side, and one end in the left-right direction of the irradiation unit 4d is stepped.

(Main effects of this embodiment)
As described above, in the present embodiment, the illuminance of the irradiation unit 4d that is arranged at the same position in the front-back direction as the path row 12d that ejects ink last to the divided printing area PA is the illuminance of the irradiation units 4a to 4c. Is higher than. Therefore, in the present embodiment, the ink ejected from the pass row 12d can be reliably cured by the irradiation unit 4d arranged at the same position in the front-rear direction as the pass row 12d. Therefore, in the present embodiment, it is possible to reliably cure the ink ejected from the pass row 12d while reducing the size of the ultraviolet irradiator 4 in the front-rear direction.

  Further, in this embodiment, the illuminance of the irradiation unit 4d is not constant in the front-rear direction but changes in the front-rear direction. Therefore, the size of the ink droplets ejected from the pass row 12d after curing varies in the front-rear direction. It becomes possible to make it. Therefore, in the present embodiment, it is possible to make the portion formed by the ink ejected from the pass row 12d in the image printed on the print medium 2 inconspicuous, and as a result, the print of the print medium 2 is performed. It is possible to suppress deterioration of quality.

  In this embodiment, the illuminance of the irradiation unit 4d gradually increases toward the front side. Therefore, in the present embodiment, even if the number of passes when the printer 1 prints on the print medium 2 increases (for example, when the printer 1 prints on the print medium 2 in 8 passes or when the printer 1 prints on the print medium 2 in 16 passes). Even when printing is performed), the illuminance of the final irradiation unit arranged at the same position in the front-back direction (sub-scanning direction) as the final pass row that ejects the last ink to the divided printing area PA is the final irradiation. It is possible to increase the illuminance of the remaining irradiating unit excluding the parts and to change the illuminance of the final irradiating unit in the sub-scanning direction. Therefore, in the present embodiment, in the printer 1, even if the number of passes for printing on the print medium 2 increases, the ultraviolet ray irradiator 4 is downsized in the front-back direction and the ink ejected from the final pass row is reliably cured. This makes it possible to prevent the print quality of the print medium 2 from deteriorating.

  In this embodiment, all the light emitting elements 13 included in the ultraviolet irradiator 4 are mounted on one substrate 14. Therefore, in this embodiment, the configuration of the ultraviolet irradiator 4 can be simplified and the cost of the ultraviolet irradiator 4 can be reduced. Further, in this embodiment, the width of the substrate 14 in the front-rear direction is less than or equal to the width of the head 3 in the front-rear direction, so that the ultraviolet irradiator 4 can be made smaller in the front-rear direction.

(Other embodiments)
The embodiment described above is an example of a preferred embodiment of the present invention, but the present invention is not limited to this, and various modifications can be made without departing from the scope of the present invention.

  In the above-described embodiment, when there is a case where the print medium 2 is printed while feeding the print medium 2 in the forward direction and a case where the print medium 2 is printed while feeding the print medium 2 in the backward direction, FIG. As shown in, in one of the two ultraviolet irradiators 4, the ultraviolet irradiators 4 may have irradiation units 4a to 4d arranged in this order toward the rear side.

  In this case, when performing printing on the print medium 2 while feeding the print medium 2 in the forward direction, the ultraviolet irradiator 4 in which the irradiation units 4a to 4d are arranged in this order toward the front side is used. When performing printing on the print medium 2 while feeding 2 in the backward direction, the ultraviolet irradiation device 4 in which the irradiation units 4a to 4d are arranged in this order toward the rear side is used. Further, in this case, when printing the print medium 2 while feeding the print medium 2 in the front direction, the front direction is the first direction, and printing the print medium 2 while feeding the print medium 2 in the rear direction. When performing, the rear direction is the first direction.

  In the above-described mode, as shown in FIG. 6A, the number of light emitting elements 13 arranged in the left-right direction in the irradiation section 4d is equal to the number of light emitting elements 13 arranged in the left-right direction in the irradiation sections 4a to 4c. It may be. Further, the number of the light emitting elements 13 arranged in the left-right direction in the irradiation unit 4d may be constant in the front-back direction. In this case, when the print medium 2 is printed, the light emitting element 13 not hatched in FIG. 6A emits light.

  That is, even in this case, the number of the light emitting elements 13 that are turned on when printing the print medium 2 in the irradiation section 4d and that are arranged in the left-right direction is printed in each of the irradiation sections 4a to 4c. The number of the light emitting elements 13 that are turned on when printing the medium 2 is larger than the number of the light emitting elements 13 that are arranged in the left-right direction, and when printing the print medium 2, the illuminance of the irradiation unit 4d is equal to that of the irradiation units 4a. 4c is higher than the respective illuminance. Even in this case, the number of light emitting elements 13 that are turned on when printing the print medium 2 in the irradiation unit 4d and that are arranged in the left-right direction is not constant in the front-rear direction but in the front-rear direction. The illuminance of the irradiation unit 4d is not constant in the front-rear direction but changes in the front-rear direction when the print medium 2 is printed.

  However, as in the above-described embodiment, the number of light emitting elements 13 arranged in the left-right direction in the irradiation section 4d is larger than the number of light emitting elements 13 arranged in the left-right direction in the irradiation sections 4a to 4c, and When the number of the light emitting elements 13 arranged in the left-right direction in the irradiation unit 4d changes in the front-rear direction, all the light emitting elements 13 of the ultraviolet irradiation device 4 are simply caused to emit light when printing the print medium 2. Thereby, the illuminance of the irradiation unit 4d can be made higher than the illuminance of each of the irradiation units 4a to 4c, and the illuminance of the irradiation unit 4d can be changed in the front-rear direction. Therefore, the control of the ultraviolet irradiator 4 becomes easy.

  In the above-described embodiment, the illuminance of the light emitting element 13 that is turned on when printing the print medium 2 in the irradiation section 4d is higher than the illuminance of the light emitting element 13 that is turned on when printing the print medium 2 in each of the irradiation sections 4a to 4c. In addition, the illuminance of the light emitting element 13 that is turned on when printing the print medium 2 in the irradiation unit 4d may not be constant in the front-rear direction but may change in the front-rear direction. However, in this case, control of the ultraviolet irradiator 4 may be complicated.

  In this case, as in the above-described embodiment, the number of light emitting elements 13 arranged in the left-right direction in the irradiation section 4d is smaller than the number of light emitting elements 13 arranged in the left-right direction in each of the irradiation sections 4a to 4c. The number of the light emitting elements 13 arranged in the left-right direction in the irradiation unit 4d may change in the front-back direction, but as shown in FIG. The number of light-emitting elements 13 arranged in the same direction is equal to the number of light-emitting elements 13 arranged in the left-right direction in each of the irradiation sections 4a to 4c, and the light-emitting elements 13 arranged in the left-right direction in the irradiation section 4d. The number of may be constant in the front-back direction.

  In the above-described embodiment, when printing the print medium 2, the illuminance of the irradiation unit 4d may gradually increase toward the rear side. For example, as shown in FIG. 6C, the number of light emitting elements 13 arranged in the left-right direction in the irradiation section 4d may be gradually increased toward the rear side. In addition, in the above-described embodiment, for example, when printing the print medium 2, the illuminance of the irradiation unit 4d may decrease once toward the front side and then increase again. For example, as shown in FIG. 6D, the number of light-emitting elements 13 arranged in the left-right direction in the irradiation unit 4d may decrease once toward the front side and then increase again.

  Even in these cases, since the size of the ink droplets ejected from the pass row 12d after curing can be varied in the front-rear direction, in the image printed on the print medium 2 or the like, It is possible to make the portion formed by the ink ejected from the pass row 12d inconspicuous. Therefore, it is possible to suppress deterioration of the print quality of the print medium 2.

  In the above-described embodiment, the printer 1 may print on the print medium 2 by multi-pass other than 4-pass. For example, the printer 1 may print on the print medium 2 in 8 passes, or may print on the print medium 2 in 16 passes. When the printer 1 prints on the print medium 2 in eight passes, the nozzle row 12 includes eight pass rows, and the ultraviolet irradiator 4 includes eight irradiation units. When the printer 1 prints on the print medium 2 in 16 passes, the nozzle row 12 includes 16 pass rows, and the ultraviolet irradiator 4 includes 16 irradiation units.

  In the above-mentioned form, the illuminance of one or two irradiation units 4a to 4c arbitrarily selected from the irradiation units 4a to 4c is different from that of the remaining irradiation units 4a to 4c that are not selected. Is also good. For example, the number of the light emitting elements 13 arranged in the left-right direction in one or two irradiation units 4a to 4c arbitrarily selected from the irradiation units 4a to 4c is the remaining irradiation units 4a to 4c which are not selected. The number may be different from the number of the light emitting elements 13 arranged in the left-right direction in 4c. Further, in the above-described embodiment, the illuminance of the irradiation units 4a to 4c may not be constant in the front-rear direction but may change in the front-rear direction. For example, the number of the light emitting elements 13 arranged in the left-right direction in the irradiation unit 4a may not be constant in the front-rear direction but may change in the front-rear direction.

  In the above-described embodiment, the width of the substrate 14 in the front-rear direction may be larger than the width of the head 3 in the front-rear direction, and the front end of the substrate 14 may be disposed in front of the front end of the head 3. In this case, the width in the front-rear direction of the portion where the plurality of light emitting elements 13 are arranged is wider than the length of the nozzle row 12, and the front end of the portion where the plurality of light emitting elements 13 is arranged is the nozzle row 12. It may be arranged in front of the front end. Further, in the above-described embodiment, each of the irradiation units 4a to 4d and each of the pass rows 12a to 12d may be displaced in the front-rear direction. That is, in the front-rear direction, the irradiation unit 4a and the pass line 12a are displaced, the irradiation unit 4b and the pass sequence 12b are displaced, the irradiation unit 4c and the pass sequence 12c are displaced, and the irradiation unit 4d and the pass sequence 12d are displaced. May be.

  In the above-mentioned form, the non-ejection region described in the above-mentioned Patent Document 1 may be formed in the head 3. Further, in the above-described embodiment, instead of the medium feeding mechanism 9, a carriage feeding mechanism for feeding the carriage 5 in the sub scanning direction may be provided. The carriage feed mechanism in this case is a feed mechanism that relatively feeds the print medium 2 in the sub-scanning direction with respect to the carriage 5. Moreover, in the above-mentioned form, the ultraviolet irradiator 4 may include two or more substrates 14.

1 Printer (inkjet printer)
2 Print media 3 Head (inkjet head)
4 UV Irradiators 4a to 4c Irradiation Unit 4d Irradiation Unit (Final Irradiation Unit)
5 Carriage 6 Carriage Drive Mechanism 9 Media Feed Mechanism (Feed Mechanism)
12 nozzle row 12a to 12c pass row 12d pass row (final pass row)
13 Light emitting element 14 Substrate BW Bandwidth PA Divided print area X Sub-scanning direction X1 First direction Y Main-scanning direction

Claims (7)

An inkjet head in which a plurality of nozzles for ejecting an ultraviolet curable ink toward a print medium are formed, an ultraviolet irradiator that irradiates the ink ejected from the inkjet head with ultraviolet rays to cure the ink, and the inkjet head And a carriage on which the ultraviolet irradiator is mounted, a carriage drive mechanism that moves the carriage in the main scanning direction, and the print medium relative to the carriage in a sub-scanning direction orthogonal to the vertical direction and the main scanning direction. And a feeding mechanism that feeds the print medium, the carriage moving in the main scanning direction and the relative feeding of the print medium in the sub-scanning direction with respect to the carriage are alternately performed a plurality of times, and the multi-pass method is used. An inkjet printer that prints on a print medium,
In the inkjet head, a nozzle row including a plurality of the nozzles arranged in the sub-scanning direction is formed,
The nozzle row includes a plurality of pass rows separated by a constant band width in the sub-scanning direction,
The ultraviolet irradiator includes a plurality of irradiation units that are separated in the sub-scanning direction,
The feeding mechanism relatively feeds the print medium in the sub-scanning direction with respect to the carriage by the same amount as the bandwidth when printing the print medium,
A printing area, which is an area where printing of the print medium is performed, is composed of a plurality of divided printing areas divided by the bandwidth in the sub-scanning direction,
Ink is ejected from the different pass rows every time the print medium is relatively sent to the carriage in the sub-scanning direction, in at least a part of the divided print area.
Of the plurality of pass rows, the pass row that ejects ink last to the divided print areas is set as the final pass row, and ultraviolet rays are finally emitted to the divided print areas of the plurality of irradiation units. When the irradiation unit for irradiating is the final irradiation unit,
The illuminance of the final irradiation unit is higher than the illuminance of the remaining irradiation unit excluding the final irradiation unit, and is not constant in the sub-scanning direction, but changes in the sub-scanning direction. Inkjet printer to do. The ultraviolet irradiator includes a plurality of light emitting elements,
The number of the light emitting elements that are turned on during printing of the print medium in the final irradiation unit and are arranged in the main scanning direction is the same as the number of the light emitting elements in the remaining irradiation unit excluding the final irradiation unit. The number of the light emitting elements that are turned on during printing is greater than the number of the light emitting elements that are arranged in the main scanning direction,
The number of the light emitting elements that are turned on when printing the print medium in the final irradiation unit and that are arranged in the main scanning direction is not constant in the sub scanning direction but changes in the sub scanning direction. The inkjet printer according to claim 1, wherein: The number of the light emitting elements arranged in the main scanning direction in the final irradiation unit is larger than the number of the light emitting elements arranged in the main scanning direction in the remaining irradiation units except the final irradiation unit. ,
The inkjet printer according to claim 2, wherein the number of the light emitting elements arranged in the main scanning direction in the final irradiation unit is not constant in the sub scanning direction but changes in the sub scanning direction. The ultraviolet irradiator includes a plurality of light emitting elements,
The illuminance of the light emitting element that is turned on when printing the print medium in the final irradiation unit is higher than the illuminance of the light emitting element that is turned on during printing of the print medium in the remaining irradiation units excluding the final irradiation unit. Is getting higher,
2. The inkjet printer according to claim 1, wherein the illuminance of the light emitting element that is turned on at the time of printing the print medium in the final irradiation unit is not constant in the sub-scanning direction but changes in the sub-scanning direction. When the relative movement direction of the print medium, which is sent relative to the carriage in the sub-scanning direction during printing of the print medium, to the carriage is a first direction,
The inkjet printer according to any one of claims 1 to 4, wherein the illuminance of the final irradiation unit gradually increases toward the first direction side.   The ultraviolet ray irradiator includes a plurality of light emitting elements, and includes a single substrate on which all the light emitting elements of the ultraviolet ray irradiator are mounted. Inkjet printer.   7. The inkjet printer according to claim 6, wherein the width of the substrate in the sub-scanning direction is less than or equal to the width of the inkjet head in the sub-scanning direction.

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