JP2009202418A - Inkjet printer, printing unit, and its printing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet printer which has improved print quality by applying UV ink not to ooze out of the surface of a print medium in smoothed state, and to provide its printing unit and printing method. <P>SOLUTION: The inkjet printer includes a vacuum table for supporting a print medium, a print head 62 mounted on a carriage 63 and discharging UV ink toward the surface of the print medium so that the UV ink adheres thereto, and a right UVLED unit 70R and a left UVLED unit 70L mounted on the carriage 63 and curing the UV ink adhering to the surface of the print medium by irradiating it with UV rays. The right UVLED unit 70R and the left UVLED unit 70L are configured by mounting a plurality of UVLEDs on the carriage 63 while arranging in front and back, and each of the plurality of UVLEDs is configured such that irradiation strength of UV rays can be controlled independently. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an inkjet printer that performs printing by ejecting ink onto a printing medium, a printing unit thereof, and a printing method thereof.

  2. Description of the Related Art Conventionally, an ink jet printer that prints on a print medium by ejecting ink from the print head while reciprocating a print head disposed opposite to the platen left and right with respect to the print medium placed on the platen It has been known. Among such ink jet printers, there is an ink jet printer that prints on a print medium by ejecting ultraviolet curable ink (hereinafter referred to as UV ink) having a property of being cured by being irradiated with ultraviolet rays from a print head. . Since this UV ink is excellent in weather resistance and water resistance, it becomes possible to use the printed material for, for example, outdoor advertising flyers and the like, and the usage of the printed material is greatly expanded as compared with the case of using the water-soluble ink. There is an advantage.

  By the way, an ink jet printer that performs printing by discharging UV ink is provided with an ultraviolet irradiation device for irradiating the UV ink attached to the printing medium with ultraviolet rays and curing it. In recent years, an ink jet printer using an ultraviolet light emitting diode (hereinafter referred to as UVLED) has been developed as a light source for emitting ultraviolet light in the ultraviolet irradiation device (see, for example, Patent Document 1). Here, the UVLED is an abbreviation for Ultra Bior Light Emitting Diode.

  As shown in FIG. 9A, the conventional printing unit 500 includes a right ultraviolet ray irradiation device 520R having UVLEDs arranged therein and capable of irradiating ultraviolet rays toward a print medium 501 positioned below. A pair of left ultraviolet irradiation devices 520L are fixedly disposed on the left and right sides of the print head 510. For convenience of explanation, the arrow direction shown in FIG. The print head 510 is, for example, a magenta print head 510M that discharges droplet-shaped magenta UV ink from a plurality of nozzles (not shown) provided on the lower surface toward the print medium 501, and similarly discharges yellow UV ink. The yellow print head 510Y, the cyan print head 510C that discharges cyan UV ink, and the black print head 510K that discharges black UV ink.

  When printing is performed on the print line 508 of the print medium 501, UV ink is ejected from each nozzle of the print head 510 while moving the print unit 500 back and forth by a predetermined number of passes above the print line 508, and desired. In this pattern, the print line 508 is attached in an overlapping manner. At this time, ultraviolet light having an irradiation intensity capable of completely curing the UV ink is emitted from the right ultraviolet irradiation device 520R and the left ultraviolet irradiation device 520L, and printing is performed by irradiating the printing line 508 with the ultraviolet light. The UV ink attached to the line 508 is cured and printed.

  9B and 9C show cross-sectional views of the state in which the UV ink ejected from the nozzles adheres to the print line 508 in the middle of printing on the print line 508 as described above. . In FIG. 9B, uncured UV ink 512 is ejected on the completely cured UV ink 511 that has adhered to the print line 508 in the previous pass and is completely cured by being irradiated with ultraviolet rays. The attached state is shown. At this time, since the fully cured UV ink 511 is completely cured, the affinity between the fully cured UV ink 511 and the uncured UV ink 512 is poor, and the uncured UV ink 512 is raised in a granular shape due to surface tension. And become attached. In addition, after the uncured UV ink 512 is adhered in the form of particles, it has a poor affinity, and therefore, it is completely cured by being irradiated with ultraviolet rays in a state where it hardly spreads before being irradiated with ultraviolet rays.

  On the other hand, the uncured UV ink 514 later in the current pass adheres to the print line 508 in the previous pass and is not cured (or hardly cured) on the previous uncured UV ink 513. FIG. 9C shows a state where the ink is discharged and adhered. At this time, the affinity between the previous uncured UV ink 513 and the subsequent uncured UV ink 514 is good, and the subsequent uncured UV ink 514 mixes with the previous uncured UV ink 513 after adhering in a granular form. It bleeds together. The previous uncured UV ink 513 and the subsequent uncured UV ink 514 are mixed to form a mixed UV ink 515, which is irradiated with ultraviolet rays and completely cured.

JP 2006-27236 A

  By the way, when printing is performed on the printing medium 501 by the printing unit 500, the respective UV inks that overlap and adhere to the surface of the printing medium 501 are cured without being mixed and spread and spread and smoothed. Thus, it is possible to obtain a print medium 501 (desired print) on which desired printing has been performed. However, as shown in FIG. 9B, when the uncured uncured UV ink 512 overlaps and adheres onto the completely cured fully cured UV ink 511, the fully cured UV ink 511 and the uncured UV ink are uncoated. While the ink 512 does not mix, the fully cured UV ink 511 repels the uncured UV ink 512, and the uncured UV ink 512 is irradiated with ultraviolet rays while being swelled in a granular shape on the surface of the fully cured UV ink 511. May be cured. As described above, when the printed matter printed with the UV ink cured in a granular form is compared with the desired printed matter, the appearance is different due to the reflection of light from the printed matter, and the print quality may be deteriorated.

  Further, as shown in FIG. 9C, when the uncured uncured UV ink 514 overlaps and adheres to the uncured previous uncured UV ink 513, the subsequent uncured UV ink 514 was mixed with the previous uncured UV ink 513 and spread, and in this state, it was sometimes cured by being irradiated with ultraviolet rays. In this way, when the printed matter that is cured and printed in a state where the UV inks are mixed and blotted is compared with the desired printed matter, the color of the mixed and blotted portion looks different, which may reduce the print quality. was there.

  In view of the above-described problems, the present invention uses an ink jet printer in which the print quality is improved by stacking and adhering UV ink on the surface of a print medium in a smoothed state so as not to bleed, and the ink jet printer. It is an object to provide a printing unit and a printing method using the inkjet printer.

  In order to solve the above problems, an ink jet printer according to the present invention is reciprocally moved in a first direction with respect to a medium support member (for example, a vacuum table 12a in the embodiment) for supporting a print medium and the print medium. And a carriage which is relatively moved in a second direction orthogonal to the first direction and is mounted opposite the medium support member, and discharges ink toward the surface of the print medium supported by the medium support member. The print head to be adhered and the medium mounted on the carriage facing the medium support member, and the surface of the print medium supported by the medium support member is irradiated with ultraviolet rays to cure the ink adhered to the surface of the print medium. For example, the right UVLED unit 70R and the left UVLED unit 70L in the embodiment. . The ultraviolet irradiation device is configured by mounting a plurality of ultraviolet light sources (for example, the UVLED 81R in the embodiment) in the second direction and mounted on the carriage, and each of the plurality of ultraviolet light sources independently The irradiation intensity is configured to be controllable.

  In the inkjet printer having the above-described configuration, the ultraviolet irradiation device has a size in the second direction longer than the size of the print head, a part of the ultraviolet light source is adjacent to the print head, and the remaining ultraviolet light source. Is preferably mounted on the carriage so as to protrude in the second direction with respect to the print head. In the ink jet printer having the above configuration, it is preferable that the ultraviolet irradiation device is disposed on both sides of the print head in the first direction on the carriage. In the ink jet printer having the above-described configuration, the plurality of ultraviolet light sources preferably use a light emitting diode. In the inkjet printer having the above configuration, the plurality of ultraviolet light sources preferably have a configuration in which the irradiation intensity of ultraviolet rays can be set in at least two stages.

  The printing unit according to the present invention discharges and adheres ink to the surface of the print medium while moving relative to the surface of the print medium, and cures the attached ink by irradiating with ultraviolet rays. A printing unit used for printing, mounted on a carriage that is relatively reciprocated in a first direction with respect to a print medium and that is relatively moved in a second direction orthogonal to the first direction. A print head that ejects and attaches ink toward the surface of the medium; and an ultraviolet irradiation device that is mounted on the carriage and that irradiates the surface of the print medium with ultraviolet light to cure the ink attached to the surface of the print medium. Have. The ultraviolet irradiation device is configured by arranging the plurality of ultraviolet light sources in the second direction and mounted on the carriage, and each of the plurality of ultraviolet light sources is configured such that the irradiation intensity of ultraviolet rays can be controlled independently. ing.

  The printing method according to the present invention is a printing method performed using the ink jet printer configured as described above, wherein the carriage is moved relative to the print medium supported by the medium support member in the first direction. Performing the desired printing by ejecting ink from the print head to the surface of the printing medium while reciprocating, and curing the ink adhering to the surface of the printing medium by irradiating ultraviolet rays from the ultraviolet irradiation device; An ultraviolet ray applied to the ink ejected from the print head and attached to the surface of the print medium, independently controlling the intensity of the emitted ultraviolet rays from the plurality of ultraviolet light sources when irradiating the ultraviolet rays from the ultraviolet irradiation device; The irradiation timing and dose are controlled.

  In the printing method, the size of the ultraviolet irradiation device in the second direction is longer than the size of the print head, a part of the ultraviolet light source is adjacent to the print head, and the remaining ultraviolet light source is An inkjet printer mounted on the carriage protruding in the second direction with respect to the print head is used to move the carriage from the print head to the surface of the print medium while relatively reciprocating in the first direction. When desired printing is performed by ejecting ink, a portion of the ultraviolet light source adjacent to the print head is used to temporarily cure the ink immediately after being ejected from the print head and attached to the surface of the print medium. The portion of the ultraviolet light source that protrudes in the second direction with respect to the print head is moved to the previous relative reciprocating movement. It is preferred that has an ultraviolet light for curing so as to present cured by irradiation of ink adhering to the surface of the print medium is discharged from the print head in.

  The inkjet printer according to the present invention is configured such that a plurality of ultraviolet light sources are arranged in a second direction and an ultraviolet irradiation device is mounted on a carriage, and each of the plurality of ultraviolet light sources is independently irradiated with ultraviolet light. Is configured to be controllable. With this configuration, the uncured UV ink adhering to the print medium is cured to a gel-like semi-cured state where the UV inks that are in contact with each other are not mixed and smeared while ensuring an affinity for spreading and smoothing. It is possible to irradiate ultraviolet rays with possible irradiation intensity. For this reason, when another UV ink is adhered and stacked on the gel-like semi-cured UV ink, the adhered UV ink spreads and is smoothed and does not cause bleeding. Therefore, it is possible to print on the surface of the print medium in a state where the UV ink is smoothed and so as not to bleed, and the print quality can be improved. Further, after the semi-cured UV inks overlapped with each other are smoothed, the UV inks are fixed to the print medium by irradiating these UV inks with ultraviolet rays having irradiation intensity that can be completely cured. As described above, it is possible to irradiate ultraviolet rays having different irradiation intensities at different timings.

  The ultraviolet irradiation device preferably has a configuration in which a part of the ultraviolet light source is adjacent to the print head and the remaining ultraviolet light source is mounted on the carriage so as to protrude in the second direction with respect to the print head. When configured in this way, the UV ink is irradiated from the ultraviolet light source adjacent to the print head to the UV ink with irradiation intensity that can be cured, for example, in a gel-like semi-cured state, and the carriage moves relative to the second direction. After that, it is possible to irradiate ultraviolet rays having an irradiation intensity capable of completely curing the semi-cured UV ink from an ultraviolet light source protruding in the second direction with respect to the print head. Therefore, even when the UV ink takes a long time to spread and smooth after it becomes a gel-like semi-cured state, for example, the UV ink is completely cured and printed after waiting for smoothing. It can be fixed to the medium.

  The ultraviolet irradiation device is preferably arranged on both sides of the print head in the first direction on the carriage. In such a configuration, it is possible to irradiate ultraviolet rays having irradiation intensity that can be cured into a gel-like semi-cured state immediately after the UV ink adheres to the print medium regardless of the reciprocating direction of the carriage. Therefore, for example, even when UV inks adhered in the same pass are in contact with each other, the UV inks can be cured into a semi-cured state before mixing and bleeding. Therefore, it is possible to suppress the occurrence of bleeding and improve the print quality.

  The plurality of ultraviolet light sources preferably have a configuration using light emitting diodes. In the light emitting diode, the current value of the supply current changes, and at the same time, the irradiation intensity of ultraviolet rays changes. Therefore, it is possible to irradiate UV ink with a desired irradiation intensity with almost no time lag with respect to irradiation intensity control. Therefore, the UV ink can be cured without unevenness, for example, in a gel-like semi-cured state and a completely cured state.

  The plurality of ultraviolet light sources preferably have a configuration capable of setting the irradiation intensity of ultraviolet rays in at least two stages. In this configuration, the irradiation intensity of the ultraviolet light source is set to, for example, an irradiation intensity at which uncured UV ink can be cured into a gel-like semi-cured state and an irradiation intensity at which semi-cured UV ink can be completely cured. Keep it. Thus, the irradiation intensity control of each of the plurality of ultraviolet light sources can be performed by a simple method of selecting one of the two irradiation intensities, and the ultraviolet irradiation intensity control becomes easy.

  The printing unit according to the present invention is configured by mounting an ultraviolet irradiation device on a carriage so that a plurality of ultraviolet light sources are arranged in the second direction, and each of the plurality of ultraviolet light sources is independently irradiated with ultraviolet rays. Is configured to be controllable. According to this printing unit, it is possible to arbitrarily change the irradiation width and the irradiation intensity in the second direction of the ultraviolet rays irradiated from the ultraviolet irradiation device. Therefore, for example, the irradiation width of ultraviolet rays in the second direction can be controlled in accordance with the discharge width in the second direction of the UV ink discharged from the print head.

  In the printing method according to the present invention, when the ultraviolet irradiation is performed from the ultraviolet irradiation apparatus, the irradiation ultraviolet intensity from the plurality of ultraviolet light sources is independently controlled, and the ultraviolet irradiation timing to the UV ink attached to the surface of the printing medium is controlled. And the dose is controlled. In this printing method, first, the UV ink adhering to the printing medium is irradiated with ultraviolet rays having irradiation intensity that can be cured, for example, in a gel-like semi-cured state. After that, the UV ink has been smoothed without bleeding by irradiating UV light with irradiation intensity capable of completely curing the semi-cured UV ink at the timing when the semi-cured UV ink spreads and is smoothed. It can be cured with and fixed to the print medium.

  The ultraviolet irradiation device is adjacent to the print head and protrudes in the second direction and is mounted on the carriage. From the portion adjacent to the print head, the ink immediately after adhering is irradiated with temporary curing ultraviolet rays to temporarily cure. There is a printing method in which the ink cured in the previous relative reciprocating movement is irradiated with ultraviolet rays for main curing (completely cured) from the portion protruding in the second direction (semi-cured into a gel). preferable. According to this printing method, the temporarily cured UV ink is irradiated with ultraviolet rays for main curing after the carriage is relatively moved in the second direction. Therefore, the temporarily cured UV ink can be spread and smoothed before the ultraviolet light for main curing is irradiated. Therefore, it is possible to fix to the printing medium by irradiating the ultraviolet ray for main curing with the UV ink smoothed.

  Hereinafter, a preferred embodiment of the present invention will be described with reference to FIGS. As an example of an ink jet printer to which the present invention is applied, a printing unit is moved with respect to a printing medium fixedly held on a table in two orthogonal directions (X-axis-Y-axis) in a horizontal plane. FIG. 1 is a perspective view of an inkjet printer 1 that performs printing of FIG. For convenience of explanation, the directions of arrows shown in the drawings will be referred to as front and rear, left and right, and top and bottom, respectively.

  The ink jet printer 1 includes a support portion 10 that forms a base portion in a lower portion, and a printing portion 50 that is disposed above the support portion 10 so as to be movable. The support unit 10 is mainly composed of a main body frame 11, a support table 12, a vacuum blower 13, and a control unit 20. The main body frame 11 horizontally supports a support table 12 mounted and fixed thereon, and serves as a mounting base for each mechanism. The support table 12 is formed in a rectangular shape in plan view, and a vacuum table 12a for mounting and holding the flat print medium 2 thereon is formed at the center. The surface of the vacuum table 12a is formed with a number of fine air holes penetrating vertically, and these air holes communicate with a decompression chamber (not shown) provided on the lower surface side of the vacuum table 12a. . Further, guide grooves 12b and 12b extending in the front-rear direction are formed on the left and right end surfaces of the support table 12, and are fitted to front and rear guides 51a and 51a formed on the left and right sides of the printing unit 50 described later.

  The vacuum blower 13 communicates with the decompression chamber and exhausts the air in the decompression chamber to set a negative pressure, or feeds air into the decompression chamber and discharges it from the air hole. The print medium 2 is placed at the origin position on the vacuum table 12a, the vacuum chamber 13 is set to a negative pressure by the vacuum blower 13, and the print medium 2 is vacuum-adsorbed on the surface of the vacuum table 12a and fixedly held. When the desired printing on the printing medium 2 is completed and the printing medium 2 is removed from the vacuum table 12a, the printing medium 2 is floated and removed easily by sending air into the decompression chamber and discharging it from the air holes. be able to.

  The control unit 20 is installed at the front end portion of the support table 12 and mainly includes an operation panel 21, a stop button 22, and a controller 23. The operation panel 21 is provided with operation buttons (not shown) for operating the ink jet printer 1 and a display panel (not shown) for displaying the operation status. The stop button 22 is a button for stopping the operation of the inkjet printer 1. The controller 23 is configured inside the control unit 20, and as shown in FIG. 6, for example, the room temperature of the working room in which the ink jet printer 1 is installed, the printing medium 2 used for printing, and the type of UV ink are input. Is done. Further, the controller 23 can output operation signals to the front and rear drive mechanisms 59, the left and right drive mechanisms 69, the UV LEDs of the right UVLED unit 70R, the UV LEDs of the left UV LED unit 70L, and the print heads of the respective colors. The operation signal is output to these, and the operation is controlled so that the ink jet printer 1 is in a desired operation state.

  In the above description, the room temperature of the work chamber is input to the controller 23 because the room temperature is related to the smoothing of the UV ink, the speed of the bleeding between the UV inks, and the like. . In general, the viscosity of a liquid such as UV ink changes with a change in the room temperature. For example, when the room temperature rises, the viscosity of the UV ink decreases. When the viscosity of the UV ink is low, the UV ink ejected from the nozzle adheres to the print medium 2 and then spreads and smoothes in a short time. At this time, the UV inks in contact with each other are mixed and spread in a short time. As described above, the room temperature of the working chamber affects the viscosity of the UV ink, and as a result, affects the smoothing and bleeding of the UV ink attached to the printing medium 2. Further, for example, a temperature in the vicinity of the print head 62 in the print unit 60 described later can be detected. By doing so, it becomes possible to detect the viscosity of the UV ink more accurately.

  The printing unit 50 is mainly composed of a base 51, a guide rail 52, and a printing unit 60. The base 51 is a substantially rectangular parallelepiped extending left and right, and front and rear guides 51a and 51a formed in the vicinity of the left and right ends are fitted with the guide grooves 12b and 12b, and slide back and forth across the upper side of the support table 12. It is supported movably. The guide rail 52 extends to the left and right and is formed on the front surface of the base 51. Further, left and right guides 65 formed on the rear surface of a carriage 63, which will be described later, are fitted to the guide rails 52, and the printing unit 60 is supported so as to be slidable in the left and right directions. Various well-known techniques can be used for the front / rear drive mechanism 59 that slides the base 51 back and forth, and the left / right drive mechanism 69 that slides the print unit 60 left and right. Is omitted.

  As shown in FIGS. 1 and 2, the printing unit 60 mainly includes a printing head 62, a carriage 63, a pair of left and right right UVLED units 70 </ b> R, and a left UVLED unit 70 </ b> L, and an outer peripheral portion is covered with a cover 61. . The print head 62 includes, for example, print heads 62M, 62Y, 62C, 62K, and 62T corresponding to magenta (M), yellow (Y), cyan (C), black (K), and transparent clear (T) colors. Has been. A plurality of nozzles (not shown) capable of ejecting the UV ink of each color downward are formed on the lower surface of the print heads 62M, 62Y, 62C, 62K, and 62T of each color on a plane extending in the front-rear and left-right directions. It is arranged. A storage tank 53 that stores UV ink of each color is disposed on the upper surface of the left end of the base 51. The storage tank 53 includes, for example, storage tanks 53M, 53Y, 53C, 53K, and 53T corresponding to colors of magenta (M), yellow (Y), cyan (C), black (K), and clear (T). Has been. A storage tank and a print head communicate with each other via a pipe line (not shown) for each color, and UV ink is appropriately sent from the storage tank to the print head.

  The carriage 63 is a mounting base for the print head 62, the right UVLED unit 70R, and the left UVLED unit 70L. A print head 62 is mounted and fixed near the front end of the carriage 63, and a pair of right UVLED unit 70 </ b> R and left UVLED unit 70 </ b> L are mounted and fixed on the left and right sides of the print head 62.

  As shown in FIGS. 2 and 3, the right UVLED unit 70 </ b> R and the left UVLED unit 70 </ b> L are covered with a flat cover 71 on the front and rear side surfaces, the left and right side surfaces, and open downward. FIG. 3 shows a side cross-sectional view of the right UVLED unit 70R. In the interior surrounded by the cover 71, UVLEDs 81R to 86R are attached in order from the front so that ultraviolet rays can be emitted downward. The UV LEDs 81R to 86R have the same specifications, and ultraviolet rays emitted from an LED chip (not shown) incorporated in the main body 88 are condensed by a condensing lens 89 and have a fixed irradiation angle. Is irradiated downward. The UV LEDs 81 </ b> R to 86 </ b> R are independently controlled by the controller 23 to emit ultraviolet rays. In addition, by operating the UVLEDs 81R to 86R, it is possible to irradiate the nozzles formed on the lower surface of the print head 62 with ultraviolet rays having a width of about twice as long.

  Further, a partition plate 72 is provided in the front and rear intermediate portions (between the UVLEDs 83R and 84R and between the UVLEDs 83L and 84L) of the right UVLED unit 70R and the left UVLED unit 70L. If comprised in this way, in step 4 mentioned later, for example, since the ultraviolet rays emitted from the UVLEDs 84R, 85R, 86R are not irradiated to the printing line 2a, the ultraviolet rays having a desired irradiation intensity are irradiated for each line. The UV ink can be cured.

  Each of the UV LEDs 81 </ b> R to 86 </ b> R has a current value of a supply current controlled by the controller 23, and can irradiate ultraviolet rays having an irradiation intensity corresponding to the current value. For example, the irradiation intensity when the current of the current value A1 is supplied is an intensity for pre-curing uncured UV ink into a gel-like semi-cured state. In addition, for example, the irradiation intensity when the current of the current value A2 is supplied is an intensity at which the UV ink in a semi-cured gel-like state is temporarily cured and is fully cured. Further, the UV ink is actually cured by receiving, for example, ultraviolet rays having an irradiation intensity for temporary curing a plurality of times, and receiving an integrated amount of ultraviolet rays necessary for the main curing. The controller 23 can also control the irradiation intensity of the ultraviolet rays from each UVLED to be zero, that is, not to irradiate the ultraviolet rays, by changing the current value.

  The left UVLED unit 70L has the same configuration as that of the right UVLED unit 70R (see FIG. 4), and the UVLEDs 81L to 86L are arranged in order from the front in the interior surrounded by the cover 71. ing. In addition, each of the UV LEDs 81L to 86L is independently controlled by the controller 23 to emit ultraviolet rays. The printing unit 60 configured in this manner is reciprocated left and right by the left and right drive mechanism 69 above the print medium 2 with the print head 62, the right UVLED unit 70R, and the left UVLED unit 70L mounted on the carriage 63. At the same time, it is slid back and forth by the front and rear drive mechanism 59.

  Up to this point, the respective constituent members of the ink jet printer 1 have been described. Hereinafter, the operation of the respective constituent members when printing is performed up to the left and right end portions of the white print medium 2 with reference to the flowchart shown in FIG. explain. Before the start of printing, the printing unit 50 is located at the rear end of the support table 12, and the printing unit 60 is positioned to the left of the left end of the printing medium 2 as shown in FIG. In the home position).

  In step 1, the printing medium 2 is placed at the origin position on the vacuum table 12a and is fixed to the vacuum table 12a by being vacuum-sucked. Then, the operator inputs the type of the printing medium 2 on which printing is performed and the type of UV ink used for printing to the controller 23 via the operation panel 21. At this time, the room temperature of the working room in which the inkjet printer 1 is installed is also detected and input to the controller 23.

  Proceeding to step 2, the controller 23 calculates the viscosity for each color of the input UV ink at the detected room temperature. Then, based on the obtained viscosity, the time required for smoothing after adhesion to the printing medium 2 for each color of the UV ink is calculated. As a result, for example, magenta takes the longest time to smooth, yellow takes the second time, cyan takes the third time, and black takes the shortest time to smooth. The following explanation will be given.

  Proceeding to step 3, the UV ink ejection pattern is determined based on the time required for smoothing obtained in step 2. For example, the number of passes is determined based on the required print quality, and the ejection pattern is determined so that the UV ink having a long time required for smoothing is ejected in order. Here, the number of passes is the number of passes through the same area of the print medium 2 while discharging UV ink from the nozzles of the print head 62. In this way, for example, printing is performed in six passes, and UV ink is ejected one by one in the order of magenta, yellow, cyan, and black in each pass, and then clear UV ink is ejected in the remaining two passes. And so on. Based on the UV ink ejection pattern determined in this way, the UV irradiation pattern of each UVLED is determined. For example, the UV irradiation timing and the UV irradiation intensity of each UVLED are determined so that after UV ink adheres to the print medium 2, UV light for pre-curing is irradiated and smoothed after being smoothed.

  Proceeding to step 4, UV ink is ejected onto the printing medium 2 and ultraviolet rays are irradiated, whereby desired printing is performed on the printing medium 2. Here, the outline of the printing procedure will be described with reference to FIG. 4 showing a plan view of the printing unit 60. The printing unit 60 is moved from the home position shown in FIG. 4A to a position to the right of the right end of the printing medium 2 shown in FIG. It is reciprocated to return to the position. At this time, UV ink whose ejection is controlled is ejected from the nozzles of the respective print heads while reciprocating left and right above the print medium 2 and adhered to the print medium 2 in a desired pattern. The UV ink adhering to the printing medium 2 is irradiated with the ultraviolet light for temporary curing as described above and temporarily cured, and spreads until it becomes smoothed over time. Thereafter, the UV light for main curing is irradiated to the smoothed UV ink, and is finally cured in a smoothed state and fixed to the print medium 2, and desired printing is performed.

  When printing is performed as described above, the controller 23 controls each component so that the UV ink ejection pattern determined in Step 3 and the ultraviolet irradiation pattern of each UVLED are obtained. An example of control of the right UVLED unit 70R, the left UVLED unit 70L, and the print head 62 by the controller 23 will be described with reference to FIG. It is assumed that the print head 62 is in a front-rear position where UV ink can be attached to, for example, the print line 2 a extending left and right on the surface of the print medium 2 by reciprocating left and right. A printed line 2b having the same front-rear width as the print line 2a is adjacent to the rear side of the print line 2a. As described later, UV ink of each color (magenta, yellow, cyan, black, and clear) is attached to the printed line 2b in a temporarily cured state. At this time, the ultraviolet rays emitted from the UVLEDs 81R, 82R, 83R (UVLEDs 81L, 82L, 83L) can be applied to the printing line 2a. Moreover, the ultraviolet rays emitted from the UVLEDs 84R, 85R, 86R (UVLEDs 84L, 85L, 86L) can irradiate the printed line 2b.

  In the first pass, the printing unit 60 is moved from the home position shown in FIG. 4A to the reverse position shown in FIG. At this time, magenta UV ink 62m whose ejection is controlled from the nozzles of the print head 62M is ejected onto the printing line 2a. Further, at this time, the UVLEDs 81L, 82L, and 83L are controlled so as to emit ultraviolet rays for temporary curing, and the other UVLEDs are controlled so as not to emit ultraviolet rays. Therefore, when the first pass is executed, the UV ink 62m attached to the printing line 2a is in a state of being temporarily cured by being irradiated with ultraviolet rays for temporary curing (see FIG. 5A). Further, while the first pass is being executed, the UV inks of the respective colors that have been preliminarily cured on the printed line 2 b and gradually spread on the surface of the print medium 2.

  In the second pass, the printing unit 60 is moved from the reverse position shown in FIG. 4B to the home position shown in FIG. At this time, the yellow UV ink 62y discharged from the nozzles of the print head 62Y adheres so as to overlap the UV ink 62m attached in the first pass, for example. The pre-cured UV ink 62m and the uncured UV ink 62y are not mixed and spread, and the UV ink 62y is not repelled by the UV ink 62m due to surface tension. Further, at this time, the UVLEDs 81R, 82R, and 83R are controlled by the controller 23 so as to emit ultraviolet rays for temporary curing, and the other UVLEDs are controlled so as not to emit ultraviolet rays. Therefore, when the second pass is executed, the UV ink 62y attached to the printing line 2a is temporarily cured by being irradiated with ultraviolet rays for temporary curing, and the UV ink attached in the first pass. 62 m is also in a temporarily cured state (see FIG. 5B). At this time, the pre-cured UV ink 62m and the pre-cured UV ink 62y have good affinity, so that they do not repel each other and gradually spread, and they do not mix and bleed. Further, while the second pass is being executed, the UV inks of the respective colors that have been preliminarily cured on the printed line 2 b and gradually spread on the surface of the printing medium 2.

  In the third pass, the printing unit 60 is moved from the home position to the reverse position, as in the first pass. At this time, the cyan UV ink 62c ejected from the nozzles of the print head 62C overlaps and adheres to the print line 2a to which the temporarily cured UV ink 62m and the temporarily cured UV ink 62y are adhered. The temporarily cured UV inks 62m and 62y and the uncured UV ink 62c do not mix and bleed, and the UV ink 62c is not repelled by the UV inks 62m and 62y due to surface tension. Further, at this time, the UVLEDs 81L, 82L, and 83L are controlled by the controller 23 so as to emit ultraviolet rays for temporary curing, and the other UVLEDs are controlled so as not to emit ultraviolet rays. Therefore, when the third pass is executed, the UV ink 62c attached to the printing line 2a is in a state of being temporarily cured by being irradiated with ultraviolet rays for temporary curing, and in the first pass and the second pass. The adhering UV ink 62m and UV ink 62y are also temporarily cured (see FIG. 5C). At this time, the UV ink 62m, the UV ink 62y, and the UV ink 62c that have been pre-cured do not repel each other because they have good affinity, and do not spread out and are not mixed and spread. Further, while the third pass is being performed, the UV inks of the respective colors that have been preliminarily cured on the printed line 2 b and gradually spread on the surface of the print medium 2.

  In the fourth pass, the printing unit 60 is moved from the reverse position to the home position, as in the second pass. At this time, the black UV ink 62k discharged from the nozzles of the print head 62K overlaps and adheres to the print line 2a to which the temporarily cured UV ink 62m, UV ink 62y, and UV ink 62c are attached. The temporarily cured UV inks 62m, 62y, 62c and the uncured UV ink 62k do not mix and bleed, and the UV ink 62k is repelled by the UV inks 62m, 62y, 62c due to surface tension. There is nothing. Further, at this time, the UVLEDs 81R, 82R, and 83R are controlled by the controller 23 so as to emit ultraviolet rays for temporary curing, and the other UVLEDs are controlled so as not to emit ultraviolet rays. Therefore, when the fourth pass is executed, the UV ink 62k attached to the printing line 2a is in a state of being temporarily cured by being irradiated with ultraviolet rays for temporary curing, and attached in the first to third passes. The UV ink 62m, the UV ink 62y, and the UV ink 62c are also temporarily cured (see FIG. 5D). At this time, the UV ink 62m, the UV ink 62y, the UV ink 62c, and the UV ink 62k that have been pre-cured do not repel each other because of their good affinity, and do not spread and mix. Further, while the fourth pass is being performed, the UV inks of the respective colors that have been preliminarily cured on the printed line 2 b and gradually spread on the surface of the print medium 2.

  In the fifth pass, the printing unit 60 is moved from the home position to the reverse position, as in the first pass. At this time, the clear UV ink 62t discharged from the nozzles of the print head 62T overlaps and adheres to the print line 2a to which the temporarily cured UV ink 62m, UV ink 62y, UV ink 62c, and UV ink 62k adhere. To do. The pre-cured UV inks 62m, 62y, 62c, and 62k and the uncured UV ink 62t do not mix and bleed, and the UV ink 62t is converted into the UV inks 62m, 62y, 62c, and so on by surface tension. It won't be played in 62k. Further, at this time, the UVLEDs 81L, 82L, and 83L are controlled by the controller 23 so as to emit ultraviolet rays for temporary curing, and the other UVLEDs are controlled so as not to emit ultraviolet rays. Therefore, when the fifth pass is executed, the UV ink 62t adhering to the printing line 2a is in a state of being temporarily cured by being irradiated with ultraviolet rays for temporary curing, and adhered in the first to fourth passes. The UV ink 62m, the UV ink 62y, the UV ink 62c, and the UV ink 62k are also temporarily cured. At this time, the UV ink 62m, the UV ink 62y, the UV ink 62c, the UV ink 62k, and the UV ink 62t that have been pre-cured gradually spread without repelling each other because of good affinity, and are mixed and blotted. There is nothing. Further, while the fifth pass is being executed, the UV inks of the respective colors that have been pre-cured on the printed line 2b spread gradually on the surface of the print medium 2, and for example, the fifth pass has been completed. It is assumed that the state is smoothed at the time.

  In the sixth pass, the printing unit 60 is moved from the reverse position to the home position, as in the second pass. At this time, the clear UV ink 62t discharged from the nozzles of the print head 62T is applied to the print line 2a to which the temporarily cured UV ink 62m, UV ink 62y, UV ink 62c, UV ink 62k, and UV ink 62t are attached. Will overlap and adhere. The transparent clear UV ink 62t ejected in the fifth pass and the sixth pass adheres to the entire surface of the printing line 2a. Here, the temporarily cured UV inks 62m, 62y, 62c, 62k, 62t and the uncured UV ink 62t do not mix and bleed, and the uncured UV ink 62t is temporarily cured by the surface tension. The UV inks 62m, 62y, 62c, 62k, and 62t are not repelled. Further, at this time, the UVLEDs 81R, 82R, 83R are controlled by the controller 23 so as to emit ultraviolet rays for temporary curing, and the UVLEDs 84R, 85R, 86R, 84L, 85L, 86L are controlled so as to emit ultraviolet rays for main curing. The UVLEDs 81L, 82L, and 83L are controlled so as not to emit ultraviolet rays.

  Therefore, when the sixth pass is executed, the UV ink 62t adhering to the printing line 2a is in a state of being temporarily cured by being irradiated with the ultraviolet light for temporary curing, and adhered in the first to fifth passes. The UV ink 62m, the UV ink 62y, the UV ink 62c, the UV ink 62k, and the UV ink 62t are also temporarily cured (see FIG. 5E). At this time, the UV ink 62m, the UV ink 62y, the UV ink 62c, the UV ink 62k, and the UV ink 62t that have been pre-cured gradually spread without repelling each other because of good affinity, and are mixed and blotted. There is nothing. Further, the UV ink of each color of the printed line 2b is irradiated with ultraviolet light for main curing in a smoothed state, and is finally cured, and fixed to the print medium 2. By doing so, a transparent clear coat layer with a smooth surface is formed to cover the upper surface of the magenta, yellow, cyan, and black UV inks, and glossy printing is possible. Become.

  When the sixth pass is completed, the printing unit 60 is slid and moved forward by the printing line 2a by the front-rear drive mechanism 59 while the printing unit 60 is stationary at the home position. Thereafter, in the same manner as in the first to sixth passes described above, UV ink is applied to the print line adjacent to the front of the print line 2a, and UV light for pre-curing is irradiated and pre-cured. At this time, the UV inks of the respective colors that have been temporarily cured by adhering to the printing line 2a are irradiated with the ultraviolet light for main curing in the sixth pass in the same manner as the above-described printed line 2b, and are then smoothed. Cured and fixed to the print medium 2. By repeatedly performing UV ink adhesion, temporary curing, and main curing until the front end of the printing medium 2 is reached, printing on the printing medium 2 is completed and this flow ends.

  Here, the main effects of the inkjet printer 1 are summarized as follows. First, irradiation of each UVLED is controlled so that the UV ink adhering to the printing medium 2 is temporarily cured by irradiating UV light for temporary curing for each pass. By doing so, the UV ink adhering to the print medium 2 is temporarily cured, and the UV ink adhering to the surface of the print medium 2 is gradually spread and smoothed because the affinity is ensured. It is possible. At this time, the UV inks are not mixed and blotted. Furthermore, the UV ink gradually spreads and smoothes over time after being temporarily cured, and maintains a smoothed state without further spreading. Therefore, the ultraviolet ray for main curing may be irradiated after the UV ink is smoothed, and the irradiation timing control of the ultraviolet ray for main curing becomes easy. By performing the main curing in this way, it is possible to fix the UV ink stacked in a smoothed state so as not to bleed on the surface of the print medium 2, and to improve the print quality.

  Second, it can be controlled to irradiate UV light for temporary curing from the UVLED adjacent to the print head 62, and to perform main curing by irradiating UV light for main curing from the UVLED protruding rearward from the print head 62. It has become. By performing such control, the UV ink can be made to have a long time from the temporary curing to the main curing, so that the UV ink can be surely smoothed during this period. The ink can be permanently cured in a smoothed state and fixed to the print medium 2.

  Third, the viscosity of the UV ink is calculated from the room temperature of the working chamber, and the calculated viscosity is reflected in the UV ink discharge pattern and the UV irradiation pattern of each UVLED. With this configuration, even when the indoor temperature changes and the viscosity of the UV ink changes, the UV ink is layered on the surface of the printing medium 2 in a smoothed state so as not to bleed and is fully cured. And the print quality can be improved.

  The configurations of the right UVLED unit 70R and the left UVLED unit 70L in the present invention are not limited to the above-described embodiments, and the configurations shown in FIGS. 8A and 8B may be employed. One UVLED unit may be configured by only the portions (UVLEDs 81R, 82R, 83R) adjacent to the left and right sides of the print head 62 as in the right UVLED unit 70R ′ of the printing unit 90 shown in FIG. 8A, for example. Is possible. By comprising in this way, the number of UVLED can be reduced and the manufacturing cost can be reduced, achieving the effect of the above-mentioned Example. Further, for example, as shown in a printing unit 95 shown in FIG. 8B, it is possible to configure only one left UVLED unit 70L. With this configuration, the left and right widths of the carriage 63 'can be shortened while achieving the effects of the above-described embodiments, and the printing unit 95 can be downsized.

  In the above-described embodiment, the front and rear lengths of the right UVLED unit 70R and the left UVLED unit 70L are not limited to two lines (print line 2a and printed line 2b). For example, the print head 62 may be configured to extend from the left and right sides to the rear by a length of three lines. Further, the number of UVLEDs arranged in the right UVLED unit 70R and the left UVLED unit 70L is not limited. Further, the plurality of UVLEDs only need to extend in the front-rear direction inside the right UVLED unit 70R and the left UVLED unit 70L, and need not necessarily be arranged in a line in the front-rear direction.

  The present invention is not limited to the method of controlling the irradiation timing and irradiation intensity of each UVLED as shown in the above-described embodiments. Each UVLED may be controlled so that the UV ink attached to the print medium 2 is cured and fixed to the print medium 2 in a smoothed state.

  In step 2 of the above-described embodiment, the present invention is not limited to the configuration in which the viscosity of the UV ink is calculated based on the room temperature detected for each printing and the time required for smoothing is calculated. For example, the relationship between the room temperature and the viscosity of the UV ink is obtained by experiment or simulation, and the relationship between the viscosity of the UV ink and the time required for smoothing is obtained, and these relationships are used as a database for the control unit 20. It is also possible to store the data in a memory (not shown) incorporated therein. If comprised in this way, the time required for the smoothing of the UV ink corresponding to the detected indoor temperature will be obtained because the controller 23 refers to the database. Further, based on the relationship between the obtained room temperature and the viscosity of the UV ink, and the relationship between the obtained viscosity of the UV ink and the time required for smoothing, the detected room temperature and the smoothing of the UV ink are required. A configuration in which the relationship with time is stored in a memory as a database may be used.

  In the above-described embodiment, the UV ink ejection pattern is ejected by one color for each pass, but is not limited to such ejection control. For example, it is possible to perform ejection control such that different colors of UV ink are ejected simultaneously in each pass. In the above-described embodiment, the discharge control is performed such that clear UV ink is discharged in the fifth pass and the sixth pass. However, the present invention is not limited to such discharge control. For example, if it is possible to adhere clear UV ink to the entire surface of the printing line 2a, it is possible to perform discharge control such that clear UV ink is discharged only in the fifth pass.

  In the above-described embodiment, the printing is performed on the flat print medium 2 fixedly held on the vacuum table 12a. However, the present invention is not limited to this configuration. By providing an additional mechanism, it is possible to print on a sheet-like print medium.

  In the above-described embodiment, the print medium 2 is fixedly held on the vacuum table 12a (so-called flat bed). However, the present invention is not limited to this structure, and the present invention uses a sheet-like print medium. The present invention can also be applied to an ink jet printer that performs printing while being conveyed on a platen.

  In the above-described embodiment, the configuration in which the UV irradiation intensity of each UVLED is controlled in two stages for temporary curing and main curing is described, but the present invention is not limited to this configuration. For example, a configuration in which the ultraviolet irradiation intensity is controlled in three or more stages may be used, or a configuration in which the ultraviolet irradiation intensity is continuously controlled may be employed.

1 is a perspective view showing an ink jet printer according to the present invention. FIG. 3 is a perspective view (partially omitted) illustrating the inside of the printing unit. It is sectional drawing which showed the III-III part in FIG. It is a top view for demonstrating the discharge control of an ink, and the irradiation control of an ultraviolet-ray. It is sectional drawing which showed the process in which UV ink was piled up for every pass by the inkjet printer which concerns on this invention. It is the figure which showed the control system of the inkjet printer which concerns on this invention. 3 is a flowchart illustrating a printing method of the inkjet printer according to the present invention. It is the top view which showed another embodiment of the printing unit which concerns on this invention. (A) is a plan view showing a conventional printing unit, (b) is a cross-sectional view showing a state in which another UV ink adheres onto a completely cured UV ink, and (c) It is sectional drawing which showed the state which another UV ink adhered on the UV ink which is not hardened | cured.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inkjet printer 2 Print medium 12a Vacuum table (medium support member)
60 Printing unit 62 Printing head 63 Carriage 70R Right UVLED unit (ultraviolet irradiation device)
70L Left UVLED unit (ultraviolet irradiation device)
81R-86R, 81L-86L UVLED (ultraviolet light source)

Claims (8)

A medium support member for supporting the print medium;
The medium support member is mounted on a carriage that is reciprocally moved relative to the print medium in a first direction and that is relatively moved in a second direction orthogonal to the first direction. A print head that discharges and adheres ink toward the surface of the print medium supported by
An ultraviolet irradiation device that is mounted on the carriage so as to face the medium support member and that irradiates the surface of the print medium supported by the medium support member with ultraviolet rays to cure the ink adhering to the surface of the print medium; In the inkjet printer
The ultraviolet irradiation device is configured by arranging a plurality of ultraviolet light sources in the second direction and mounted on the carriage,
Each of the plurality of ultraviolet light sources can independently control the irradiation intensity of ultraviolet rays.   The ultraviolet irradiation device has a dimension in the second direction longer than a dimension of the print head, a part of the ultraviolet light source is adjacent to the print head, and the remaining ultraviolet light source is The inkjet printer according to claim 1, wherein the inkjet printer is mounted on the carriage so as to protrude in a direction of 2.   3. The ink jet printer according to claim 1, wherein the ultraviolet irradiation device is disposed on both sides of the print head in the first direction on the carriage. 4.   The inkjet printer according to any one of claims 1 to 3, wherein the plurality of ultraviolet light sources are configured using light emitting diodes.   5. The inkjet printer according to claim 1, wherein the plurality of ultraviolet light sources are configured to be capable of setting an irradiation intensity of ultraviolet rays in at least two stages. It is a printing unit used to discharge and adhere ink to the surface of the print medium while moving relative to the surface of the print medium, and to cure the attached ink by irradiating it with ultraviolet rays. There,
It is mounted on a carriage that is reciprocally moved relative to the print medium in a first direction and relatively moved in a second direction orthogonal to the first direction, and ejects ink toward the surface of the print medium. A print head to be adhered;
An ultraviolet irradiation device that is mounted on the carriage and that irradiates the surface of the print medium with ultraviolet rays to cure the ink attached to the surface of the print medium;
The ultraviolet irradiation device is configured by arranging the plurality of ultraviolet light sources in the second direction and mounted on the carriage,
Each of the plurality of ultraviolet light sources is a printing unit capable of independently controlling the irradiation intensity of ultraviolet rays. A printing method using the inkjet printer according to claim 1,
While the carriage is relatively reciprocated in the first direction with respect to the print medium supported by the medium support member, ink is discharged from the print head onto the surface of the print medium to perform desired printing, and Curing the ink adhered to the surface of the printing medium by irradiating ultraviolet rays from an ultraviolet irradiation device;
When irradiating ultraviolet rays from the ultraviolet irradiating device, the irradiation ultraviolet intensity from the plurality of ultraviolet light sources is independently controlled, and the ultraviolet rays are applied to the ink ejected from the print head and attached to the surface of the print medium. A printing method characterized by controlling timing and dose. The ultraviolet irradiation device has a dimension in the second direction longer than a dimension of the print head, a part of the ultraviolet light source is adjacent to the print head, and the remaining ultraviolet light source is Projecting in the direction of 2, mounted on the carriage,
When performing desired printing by discharging ink from the print head to the surface of the print medium while relatively reciprocating the carriage in the first direction,
From the portion adjacent to the print head of the ultraviolet light source, the ink immediately after being ejected from the print head and adhering to the surface of the print medium is irradiated with ultraviolet light for temporary curing and temporarily cured,
From the portion of the ultraviolet light source that protrudes in the second direction with respect to the print head, the ink that has been ejected from the print head and adhered to the surface of the print medium in the previous reciprocal movement is used for main curing. The printing method according to claim 7, wherein the curing is performed by irradiation with ultraviolet rays.

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