JP5247895B2 - Inkjet printer - Google Patents

Description

  The present invention relates to an inkjet printer that discharges ultraviolet curable ink.

  As described in Patent Document 1, in a conventional inkjet printer, an inkjet head that ejects basic color ink, an inkjet head that ejects clear ink, and a plurality of ultraviolet rays that irradiate ultraviolet rays are ejected onto a carriage that moves in the scanning direction. An irradiation device is juxtaposed along the scanning direction. When a glossy image is formed, the surface smoothing of the transparent ink is promoted by turning on only the ultraviolet irradiation device arranged at the rearmost in the carriage movement direction.

JP 2005-199563 A

  However, in the ink jet printer described in Patent Document 1, since the clear ink is ejected and the ultraviolet light is irradiated in one movement of the carriage, the surface of the cured product generated by the clear ink is uneven. There was a problem that sufficient glossiness could not be obtained.

  SUMMARY An advantage of some aspects of the invention is that it provides an ink jet printer that can form a sufficiently glossy image.

An ink jet printer according to the present invention includes a carriage that can reciprocate in a scanning direction, an ink discharge unit that is mounted on the carriage and discharges ultraviolet curable ink onto a recording medium, and a scanning direction of the ink discharge unit that is mounted on the carriage. And an ultraviolet irradiating unit that irradiates the recording medium with ultraviolet rays disposed on at least one of the front side and the rear side, and an inkjet in which the recording medium moves relative to the ink ejection unit in a feed direction orthogonal to the scanning direction In the printer, the ultraviolet irradiation unit blocks irradiation of ultraviolet rays from a position corresponding to the front portion in the feed direction of the ink discharge unit in the scanning direction, and further forwards the feed direction in the scanning direction from the front portion. At a position corresponding to the ink ejection means than the ink ejection means. And irradiating ultraviolet light from a position corresponding to the forward.

  According to the ink jet printer of the present invention, the ultraviolet curable ink applied to the upper layer is sufficiently smoothed by blocking the irradiation of the ultraviolet rays from the position corresponding to the front portion in the feed direction of the ink discharge means ( A sufficiently glossy image can be formed.

In addition, as described above, the ultraviolet curable ink applied to the upper layer can be cured after being sufficiently smoothed by irradiating ultraviolet rays from a position corresponding to the front in the feed direction from the ink discharge means. Thus, it is possible to form an appropriately glossy image.

  In this case, it is further preferable that the ultraviolet irradiation means gradually increases the illuminance of ultraviolet light emitted from a position corresponding to the front of the ink discharge means in the scanning direction toward the feed direction. In this way, the UV curing applied to the upper layer by gradually increasing the illuminance of the ultraviolet rays emitted from the position corresponding to the front of the ink ejection means in the scanning direction toward the feed direction. The mold ink can be gradually cured. Thereby, rapid curing shrinkage of the ultraviolet curable ink can be suppressed, and generation of stripes between passes and reduction in glossiness can be suppressed.

  Moreover, it is preferable that an ultraviolet irradiation means irradiates an ultraviolet-ray from the position corresponding to the rear part in the feed direction of an ink discharge means in a scanning direction. Thus, after irradiating ultraviolet rays from a position corresponding to the rear portion in the feed direction of the ink discharge means, the ultraviolet curable ink discharged from the rear portion of the ink discharge means is cured, and then from the front portion of the ink discharge means. The discharged ultraviolet curable ink can be laminated. Thereby, it is possible to prevent the ultraviolet curable ink ejected from the rear part of the ink ejecting means from bleeding with the ultraviolet curable ink ejected from the front part of the ink ejecting means.

An ink jet printer according to the present invention includes a carriage that can reciprocate in a scanning direction, an ink discharge unit that is mounted on the carriage and discharges ultraviolet curable ink onto a recording medium, and a scanning direction of the ink discharge unit that is mounted on the carriage. And an ultraviolet irradiating unit that irradiates the recording medium with ultraviolet rays disposed on at least one of the front side and the rear side, and an inkjet in which the recording medium moves relative to the ink ejection unit in a feed direction orthogonal to the scanning direction In the printer, the ink discharge unit is divided into a first discharge region disposed at the rear in the feed direction and a second discharge region disposed at the front in the feed direction, and the ultraviolet irradiation unit is arranged in the scanning direction. Of the second irradiation area corresponding to the second discharge area, the ultraviolet ray from the front in the feed direction With blocking the morphism, irradiating ultraviolet rays from the third irradiation area corresponding to the feed direction forward of said a position corresponding to the feed forward than the front in the scanning direction second discharge region It is characterized by.

According to the ink jet printer of the present invention, the ultraviolet curable ink applied to the upper layer is sufficiently smoothed (wet) by blocking the irradiation of ultraviolet rays from the front portion in the feed direction of the second irradiation region. Therefore, a sufficiently glossy image can be formed. In addition, by irradiating ultraviolet rays from the third irradiation region in this way, the ultraviolet curable ink applied to the upper layer can be cured after being sufficiently smoothed, so that an appropriately glossy image is obtained. Can be formed.

  The ink discharge means described above preferably discharges a colored UV curable ink from the first discharge area and discharges a UV curable ink having translucency from the second discharge area. As described above, the colored ultraviolet curable ink is ejected from the first ejection area, and the translucent ultraviolet curable ink is ejected from the second ejection area. In addition to being able to apply a UV curable ink having the property, the UV curable ink having translucency can be smoothed on the upper layer of the colored UV curable ink. Thereby, the glossiness can be given to the image formed with the colored ultraviolet curable ink.

  Moreover, it is preferable that the ultraviolet irradiation means mentioned above irradiates an ultraviolet-ray from the rear part in the feed direction of a 2nd irradiation area | region. In this way, by irradiating ultraviolet rays from the rear part in the feed direction of the second irradiation region, it is possible to irradiate the ultraviolet curable ink having translucency applied directly on the colored ultraviolet curable ink with ultraviolet rays. . As a result, the bonding strength between the colored ultraviolet curable ink and the translucent ultraviolet curable ink can be improved.

  Moreover, it is preferable that the ultraviolet irradiation means mentioned above irradiates an ultraviolet-ray from the 1st irradiation area | region corresponding to a 1st discharge area | region in a scanning direction. As described above, the ultraviolet curable ink discharged from the first discharge region is cured by irradiating the ultraviolet ray from the first irradiation region, and then the ultraviolet curable ink discharged from the second discharge region is stacked. Can do. Thereby, it is possible to prevent the ultraviolet curable ink ejected from the first ejection region from bleeding with the ultraviolet curable ink ejected from the second ejection region.

  In this case, it is more preferable that the ultraviolet irradiation means described above gradually increases the illuminance of the ultraviolet rays irradiated from the third irradiation region in the feed direction. In this way, the ultraviolet curable ink applied to the upper layer can be gradually cured by gradually increasing the illuminance of the ultraviolet rays irradiated from the third irradiation region in the feed direction. Thereby, rapid curing shrinkage of the ultraviolet curable ink can be suppressed, and generation of stripes between passes and reduction in glossiness can be suppressed.

  Moreover, it is preferable that the ultraviolet irradiation means mentioned above makes the peak illumination intensity of the ultraviolet-ray irradiated from a 3rd irradiation area | region smaller than the peak illumination intensity of the ultraviolet-ray irradiated from a 1st irradiation area | region. Thus, the curing rate of the ultraviolet curable ink in the upper layer can be slowed by making the peak illuminance of the ultraviolet rays irradiated from the third irradiation region smaller than the peak illuminance of the ultraviolet rays irradiated from the first irradiation region. . Thereby, it is possible to further suppress the generation of stripes between passes and the reduction in glossiness.

  Further, the ultraviolet irradiation means described above includes an ultraviolet irradiation unit that emits ultraviolet rays toward the recording medium, and a mask member that is provided on the recording medium side of the ultraviolet emission unit and blocks passage of ultraviolet rays emitted from the ultraviolet irradiation unit. It is good also as providing. As described above, since the illuminance of ultraviolet rays irradiated to the recording medium can be adjusted by the arrangement and shape of the mask member provided in the ultraviolet irradiation unit, the illuminance distribution of ultraviolet rays emitted from the ultraviolet irradiation means is easily adjusted. be able to.

  And it is preferable that the rear end part in the feed direction of the mask is gradually narrowed in the scanning direction toward the rear in the feed direction. In this way, by gradually reducing the width of the rear end portion in the feed direction of the mask toward the rear in the feed direction, the illuminance of the ultraviolet rays irradiating the recording medium is simply lowered gradually in the feed direction. be able to.

  Moreover, it is preferable that the width in the scanning direction of the front end portion in the feed direction of the mask is gradually narrowed forward in the feed direction. In this way, by gradually reducing the width of the front end portion in the feed direction of the mask toward the front in the feed direction, the illuminance of ultraviolet rays irradiating the recording medium can be gradually increased toward the feed direction. it can.

  On the other hand, the ultraviolet irradiation means may include a plurality of UVLEDs arranged in the feed direction and a lighting control unit that performs lighting control of the plurality of UVLEDs. In this way, by arranging a plurality of UV LEDs in the feed direction, the illuminance of ultraviolet rays in the feed direction irradiated on the recording medium can be adjusted, so that the illuminance distribution of ultraviolet rays emitted from the ultraviolet irradiation means can be easily achieved. Can be adjusted.

  According to the present invention, a sufficiently glossy image can be formed.

1 is a schematic diagram illustrating an inkjet printer according to an embodiment. It is a bottom view of an ultraviolet irradiation device. It is the III-III sectional view taken on the line of FIG. It is the IV-IV sectional view taken on the line of FIG. It is the figure which showed the relationship between an ultraviolet irradiation device and an inkjet head. It is the figure which showed the illumination intensity distribution of the ultraviolet-ray irradiated to a medium. It is the figure which showed the illumination intensity distribution of the ultraviolet-ray irradiated to a medium. It is a top view which shows a mask. It is the figure which showed the photosensitive state of the photosensitive paper at the time of making an ultraviolet irradiation device light on photosensitive paper.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of an inkjet printer according to the invention will be described in detail with reference to the drawings. The inkjet printer according to the embodiment is a multi-pass inkjet printer that forms an image in a plurality of passes, and discharges ultraviolet curable ink and cures the discharged ultraviolet curable ink by irradiating ultraviolet rays. Thus, an image is formed on the medium. In the drawings, the same or corresponding parts are denoted by the same reference numerals.

  FIG. 1 is a schematic diagram illustrating an inkjet printer according to an embodiment. As shown in FIG. 1, the ink jet printer 1 according to this embodiment includes a carriage 2 that can reciprocate in a scanning direction S, a head unit 3 mounted on the carriage 2, and a head unit 3 mounted on the carriage 2. An ultraviolet irradiation device 4a disposed in front of the scanning direction S and an ultraviolet irradiation device 4b mounted on the carriage 2 and disposed behind the head unit 3 in the scanning direction S are provided. The ink jet printer 1 transports the medium in the feed direction F perpendicular to the scanning direction S by the path width, and moves the carriage 2 in the scanning direction S to eject ultraviolet curable ink from the ink jet head 6. At the same time, an image is formed on the medium by performing scanning by irradiating ultraviolet rays from the ultraviolet irradiation device 4a and the ultraviolet irradiation device 4b.

  The carriage 2 is held so as to be capable of reciprocating in the scanning direction S above a platen (not shown) through which the medium is conveyed. The carriage 2 is movably held by, for example, a guide rail (not shown) extending in the scanning direction S, and reciprocates in the scanning direction S along the guide rail by driving a drive mechanism (not shown) such as a drive motor. It can be moved.

  The head unit 3 is an ink ejection device in which a plurality of inkjet heads 6 (6a to 6d) that eject ultraviolet curable ink are incorporated. Since the head unit 3 is mounted on the carriage 2, it is possible to discharge ultraviolet curable ink when moving in the scanning direction S accompanying the movement of the carriage 2. The inkjet head 6a to the inkjet head 6d are provided along the scanning direction S, and are arranged in the order of the inkjet head 6a, the inkjet head 6b, the inkjet head 6c, and the inkjet head 6d from the front side in the scanning direction S. .

  Each inkjet head 6 is formed with a plurality of nozzles (not shown) that discharge ultraviolet curable ink as droplets. The plurality of nozzles form a nozzle row arranged so as to extend in the feed direction F, and two nozzle rows are formed in the scanning direction S in each inkjet head 6. Colored ultraviolet curable ink (hereinafter also referred to as “color ink”) is ejected from the inkjet head 6a and the inkjet head 6b disposed on the front side in the scanning direction S, and the inkjet head disposed on the rear side in the scanning direction S. 6c and the inkjet head 6d discharge ultraviolet curable ink having translucency (hereinafter also referred to as “clear ink”). More specifically, magenta (M) color ink is ejected from the nozzle row on the front side in the scanning direction S formed on the inkjet head 6a, and from the nozzle row on the rear side in the scanning direction S formed on the inkjet head 6a. In this case, cyan (C) color ink is ejected. In addition, yellow (Y) color ink is ejected from the nozzle row on the front side in the scanning direction S formed on the inkjet head 6b, and black (from the nozzle row on the rear side in the scanning direction S formed on the inkjet head 6b. K) color ink is ejected. Then, clear ink (CL) is ejected from the two nozzle rows formed in each of the inkjet head 6c and the inkjet head 6d.

  Of the nozzle rows formed in the inkjet head 6a and the inkjet head 6b, the color ink is ejected only from the nozzle rows in the first ejection region A1 arranged in the rear half in the feed direction F, and the front half in the feed direction F. No color ink is ejected from the nozzle rows arranged in the nozzle array. On the other hand, among the nozzle rows formed in the inkjet head 6c and the inkjet head 6d, the clear ink is ejected only from the nozzle row in the second ejection area A2 arranged in the front half in the feed direction F, and the rear half in the feed direction F. Clear ink is not ejected from the nozzle rows arranged in the nozzles. For this reason, when the medium is conveyed in the feed direction F, first, the color ink discharged from the first discharge area A1 of the inkjet head 6a and the inkjet head 6b is applied to the surface of the medium, and then the medium is fed in the feed direction F. Then, the clear ink ejected from the inkjet head 6c and the second ejection area A2 of the inkjet head 6d is applied to the upper layer (surface) of the color ink.

  In addition, although each inkjet head 6 demonstrated as what changes the kind of ink discharged for every nozzle row, only one kind of ink is ejected from one inkjet head 6, and only the number of desired ink types is the inkjet head. 6 may be incorporated in the head unit 3.

  The ultraviolet irradiating device 4a and the ultraviolet irradiating device 4b are configured in the same manner, and irradiate the ultraviolet curable ink applied to the medium with ultraviolet rays to cure the ultraviolet curable ink. Therefore, hereinafter, the ultraviolet irradiation device 4a and the ultraviolet irradiation device 4b will be collectively described as the ultraviolet irradiation device 4. In addition, since the ultraviolet irradiation device 4 is mounted on the carriage 2, it is possible to emit ultraviolet rays when reciprocating in the scanning direction S accompanying the movement of the carriage 2.

  2 is a bottom view of the ultraviolet irradiation device, FIG. 3 is a sectional view taken along line III-III in FIG. 2, and FIG. 4 is a sectional view taken along line IV-IV in FIG. As shown in FIGS. 2 to 4, the ultraviolet irradiation device 4 includes a UVLED unit 41, a reflection plate 42, and a mask 43 as main components.

  The UVLED unit 41 is composed of a plurality of UVLEDs (ultraviolet light emitting diodes), and each UVLED is arranged in the feed direction F. In the present embodiment, eight UVLEDs are mounted on the UVLED unit 41. The UVLED unit 41 is irradiated with ultraviolet rays with high directivity, and the illuminance in the direction inclined by 60 ° with respect to the vertical direction is about 50% with respect to the illuminance in the vertical direction.

  The reflection plate 42 reflects the ultraviolet rays emitted from the UVLED unit 41 to the media side. The reflecting plate 42 is formed in an umbrella shape that spreads from the UVLED unit 41 downward in the vertical direction with an inclination of about 60 ° so as to form a side surface of a truncated pyramid. A transparent cover 42 a is attached to the rectangular opening formed on the lower end surface of the reflecting plate 42, so that the opening of the reflecting plate 42 is blocked and ultraviolet rays can be transmitted. As described above, since the ultraviolet rays emitted from the UVLED unit 41 have high directivity, the illuminance of ultraviolet rays below the reflecting plate 42 in the vertical direction is lower than the illuminance of ultraviolet rays below the UVLED 41 in the vertical direction.

  The mask 43 is formed in a thin sheet shape and is made of a material that blocks the passage of ultraviolet rays, and blocks the portion of the ultraviolet rays emitted from the ultraviolet irradiation device 4 to illuminate the medium with ultraviolet rays. Is to adjust.

  FIG. 5 is a diagram showing the relationship between the ultraviolet irradiation device and the inkjet head. As shown in FIG. 5, the ultraviolet irradiation device 4 includes the first irradiation region M1 of the ultraviolet irradiation device 4 corresponding to the first ejection region A1 of the inkjet head 6 in the scanning direction S and the first irradiation region M1 of the inkjet head 6 in the scanning direction S. The second irradiation area M2 of the ultraviolet irradiation device 4 corresponding to the second ejection area A2 and the third irradiation area M3 of the ultraviolet irradiation apparatus 4 corresponding to the front of the second ejection area A2 of the inkjet head 6 in the scanning direction S are divided. It is done. That is, the first irradiation area M1 is a position (area) facing the first ejection area A1 when the carriage 2 moves in the scanning direction S, and the color ink ejected from the first ejection area A1 is the medium. It corresponds to a position (region) that passes above the application position applied to. The second irradiation area M2 is a position (area) facing the second ejection area A2 when the carriage 2 moves in the scanning direction S, and the clear ink ejected from the second ejection area A2 is applied to the medium. It corresponds to a position (region) that passes above the applied position. The third irradiation area M3 is a position (area) on the front side in the feed direction F of the second discharge area A2, and when the carriage 2 moves in the scanning direction S, the clear ink discharged from the second discharge area A2 is This corresponds to the position (area) on the front side in the feed direction F of the application position applied to the medium. The third irradiation region M3 is a region having a predetermined length in the feed direction F. The UVLED unit 41 has a rear end disposed about 10 mm ahead of the rear end of the inkjet head 6 in the feed direction F.

  Here, the illuminance distribution adjusted by the mask will be described with reference to FIGS. 6 and 7 are diagrams showing the illuminance distribution of ultraviolet rays irradiated on the medium. The illuminance distribution shown in FIGS. 6 and 7 is an illuminance distribution based on the illuminance of the vertical component of ultraviolet rays. By the way, in the ultraviolet rays irradiated from the ultraviolet irradiation device 4, not only the vertical direction component but also the inclination direction component inclined from the vertical direction exists. However, since the directivity of ultraviolet rays emitted from the UVLED unit 41 is high, and the distance between the ultraviolet irradiation device 4 and the medium is short, the inclination direction component of the ultraviolet rays is relative to the illuminance of the vertical component of the ultraviolet rays. It will be extremely small. For this reason, it can be considered that the illuminance distribution of the ultraviolet rays applied to the medium is substantially the same as the illuminance distribution shown in FIGS.

  As shown in FIGS. 6 and 7, the illuminance distribution of the ultraviolet rays irradiated on the medium includes the illuminance distribution corresponding to the first irradiation area M1, the illuminance distribution corresponding to the second irradiation area M2, and the third irradiation area M3. And the illuminance distribution corresponding to.

The illuminance distribution of the first irradiation region M1 is generally high in illuminance. When the ultraviolet irradiation device 4 moves in the scanning direction S, the ultraviolet curable ink in the entire first irradiation region M1 is cured. Illuminance is possible. That is, after the illuminance distribution in the feed direction F passing through the center of the scanning direction S gradually increases from the rear of the feed direction F to the front of the feed direction F, and reaches the first peak illuminance P1 with the highest illuminance, Illuminance decreases sharply near the rear edge. As for this 1st peak illumination intensity P1, the illumination intensity of a vertical direction component will be about 780 mW / cm < ² >, for example. Further, the illuminance at the rear end of the feed direction F is, for example, the illuminance of the vertical component is about 400 mW / cm ² and is lower than the first peak illuminance P1, but the ultraviolet curable ink can still be cured. Illuminance.

The illuminance distribution of the second irradiation region M2 has an illuminance that is at least the path width on the rear side in the feed direction F, and the ultraviolet curable ink is cured when the ultraviolet irradiation device 4 moves in the scanning direction S. Illuminance that can be. Further, the illuminance distribution of the second irradiation area M2 is such that the illuminance on the front side in the feed direction F is low, and the ultraviolet curable ink cannot be cured when the ultraviolet irradiation device 4 moves in the scanning direction S. It has become. That is, the illuminance distribution in the feed direction F passing through the center of the scanning direction S is such that the illuminance is such that the ultraviolet curable ink is cured at least for the pass width from the rear of the feed direction F to the front of the feed direction F. After the illuminance decreases and then reaches the bottom illuminance B where the ultraviolet curable ink does not cure, the bottom illuminance B continues to the rear end. The bottom illuminance B may be any illuminance as long as the ultraviolet curable ink is not cured. For example, the illuminance of the vertical component is 0 mW / cm ² or a value close to 0 mW / cm ² .

The illuminance distribution of the third irradiation region M3 is such that the illuminance on the rear side in the feed direction F is low, and the ultraviolet curable ink cannot be cured when the ultraviolet irradiation device 4 moves in the scanning direction S. ing. The illuminance distribution of the third irradiation region M3 is such that the illuminance on the front side in the feed direction F is high, and the illuminance that can cure the ultraviolet curable ink when the ultraviolet irradiation device 4 moves in the scanning direction S. It has become. In other words, the illuminance distribution in the feed direction F passing through the center of the scanning direction S is gradually increased after the bottom illuminance B continues for a while from the rear of the feed direction F to the front of the feed direction F, and the first peak illuminance P1. After reaching a lower second peak illuminance P2, the illuminance gradually decreases. The second peak illuminance P2 is lower than the first peak illuminance P1, and for example, the illuminance of the vertical component is 180 mW / cm ² and is about ¼ of the first peak illuminance P1.

  Therefore, in order to obtain such an illuminance distribution, the mask 43 is arranged at a position corresponding to the rear part in the feed direction F of the third irradiation region M3 from the front part of the second irradiation region M2 in the feed direction F, and the ultraviolet ray. It is attached to the media side of the irradiation device 4. Note that the mask 43 can be attached to the ultraviolet irradiation device 4 by fixing it to the reflecting plate 42, the cover 42a, or the like using an adhesive tape, an adhesive, or the like.

  FIG. 8 is a plan view showing the mask. In the following description, the width of the mask 43 in the scanning direction S is simply expressed as “width”, and the length of the mask 43 in the feed direction F is simply expressed as “length”. As shown in FIG. 8, the mask 43 is formed in a line-symmetric octagon with respect to a line L that passes through the center of the scanning direction S and extends in the feed direction F, and includes a rectangular first portion 43a and a first portion. A triangular second part 43b located on the rear side in the feed direction F of the part 43a and a pentagonal third part 43c located on the front side in the feed direction F of the first part 43a.

  The first portion 43a is formed in a rectangular shape having the same size as the width in the scanning direction S of the cover 42a, and blocks the ultraviolet rays irradiated from the second irradiation region M2. When the width of the cover 42a in the scanning direction S is 36 mm, the dimensions of the first portion 43a are, for example, a width of 36 mm and a length of 15 mm.

  The second portion 43b is formed in a triangular shape whose width gradually narrows toward the rear of the feed direction F (gradually widens toward the feed direction F), and blocks the ultraviolet rays irradiated from the second irradiation region M2. Is. When the width of the cover 42a in the scanning direction S is 36 mm, the dimensions of the second portion 43b are, for example, 36 mm in width (triangle base) and 5 mm in length (triangle height).

  The third portion 43c is formed in a pentagon whose width narrows in two steps toward the front in the feed direction F, and blocks the ultraviolet rays irradiated from the second irradiation region M2 and the third irradiation region M3. . When the width of the cover 42a in the scanning direction S is 36 mm, the dimensions of the third portion 43c are, for example, 36 mm for the width (base of the pentagon), 25 mm for the length (pentagon height), The length of the inclination is 20 mm, and the length of the second-stage inclination is 5 mm.

  As shown in FIGS. 2 to 5, the mask 43 formed in this way is arranged in front of the center of the cover 42 a in the feed direction F. The rear end of the mask 43 is located behind the center of the UVLED unit 41 and ahead of the rear end of the UVLED unit 41, for example, about 5 mm behind the center of the UVLED unit 41. . In addition, the front end of the mask 43 is located in front of the front end of the UVLED unit 41. Thereby, since direct light of ultraviolet rays emitted from the UVLED unit 41 is irradiated from the first irradiation region M1, ultraviolet rays having high illuminance can be irradiated. From the third irradiation region M3, the reflection plate 42 is irradiated. Since only the reflected light reflected from is irradiated, ultraviolet rays having a lower illuminance than that of the first irradiation region M1 can be irradiated.

  FIG. 9 is a diagram illustrating a photosensitive state of the photosensitive paper when the ultraviolet irradiation device is turned on on the photosensitive paper. In FIG. 9, P1 shows the state of the photosensitive paper when the ultraviolet ray radiating device 4 is irradiated with ultraviolet rays while the carriage 2 is stationary, and P2 is a state where the carriage 2 is moved in the scanning direction S The state of the photosensitive paper when ultraviolet rays are irradiated from the ultraviolet irradiation device 4 is shown. As shown in FIG. 9, at the position corresponding to the first irradiation region M1, the entire surface of the photosensitive paper is exposed. At the position corresponding to the second irradiation area M2, only a part of the rear side in the feed direction F is exposed, and a part of the front side in the feed direction F is not exposed. At the position corresponding to the third irradiation region M3, a part on the rear side in the feed direction F is not exposed, and only a part on the front side in the feed direction F is exposed.

  As can be seen from FIG. 9, when the ultraviolet irradiation device 4 is turned on while moving the carriage 2 in the scanning direction S, the color ink discharged from the first discharge region A1 is applied to the medium at the position corresponding to the first irradiation region M1. Immediately after application, the film is cured by being irradiated with ultraviolet rays. On the other hand, in the position corresponding to the second irradiation region M2, the clear ink discharged from the second discharge region A2 is cured by being irradiated with ultraviolet rays immediately after being applied to the medium only in the lower layer, but in the upper layer. After being applied to the media, the surface is smoothed because the ultraviolet rays are not irradiated for a while. Then, at a position corresponding to the third irradiation region M3, the clear ink discharged from the second discharge region A2 is irradiated with ultraviolet rays and cured.

  In the inkjet printer 1 configured as described above, the color ink and the clear ink are ejected from the first ejection area A1 and the second ejection area A2 of the inkjet head 6 as the carriage 2 moves, and the ultraviolet irradiation device 4 Ultraviolet rays are emitted, and the media is sequentially conveyed in the feed direction F by the path width, whereby an image is formed on the media. For this reason, color ink is applied on the medium, and clear ink is applied on the upper layer of the color ink.

  Since the color ink discharged from the first discharge area A1 of the inkjet head 6 is irradiated with ultraviolet rays having an illuminance distribution in the first irradiation area M1, this color ink has an illuminance immediately after being applied to the medium. It is cured by irradiation with high ultraviolet rays.

  On the other hand, the clear ink discharged from the second discharge region A2 of the inkjet head 6 is first irradiated with ultraviolet rays having an illuminance distribution in the second irradiation region M2. For this reason, of the clear ink applied to the media, the lower clear ink is cured by being irradiated with ultraviolet rays immediately after being applied to the media, and the upper clear ink is irradiated with ultraviolet rays immediately after being applied to the media. Therefore, the surface spreads out along the media surface and the surface is smoothed. Thereafter, when the medium is conveyed in the feed direction F, the upper layer clear ink whose surface is smoothed is irradiated with ultraviolet rays having an illuminance distribution in the third irradiation region M3, and the upper layer clear ink is cured.

  As described above, according to the inkjet printer 1 according to the present embodiment, the clear ink applied to the upper layer is sufficiently smoothed by blocking the irradiation of ultraviolet rays from the front portion in the feed direction F of the second irradiation region M2. Therefore, a sufficiently glossy image can be formed.

  The color ink is ejected from the first ejection area A1 and the clear ink is ejected from the second ejection area A2, so that the clear ink can be applied to the upper layer of the color ink and the clear ink can be applied to the upper layer of the color ink. Can be smoothed. Thereby, glossiness can be given to the image formed with color ink.

  Further, as the illuminance distribution of the second irradiation region M2, the illuminance is increased by at least the path width on the rear side in the feed direction F, and ultraviolet rays are irradiated at a position corresponding to the rear portion of the second discharge region A2 in the feed direction F. The clear ink applied directly above the color ink can be irradiated with ultraviolet rays. Thereby, the joint strength between the color ink and the clear ink can be improved.

  Moreover, the color ink discharged from the first discharge area A1 is cured by setting the illuminance distribution of the first irradiation area M1 to an illuminance that can cure the ultraviolet curable ink in the entire first irradiation area M1. Later, the clear ink ejected from the second ejection area A2 can be stacked. Thereby, it is possible to prevent the color ink from bleeding with the clear ink.

  Also, as the illuminance distribution of the third irradiation region M3, the illuminance on the front side in the feed direction F can be increased so that the clear ink applied to the upper layer can be cured after being sufficiently smoothed. A feeling image can be formed.

  At this time, the clear ink applied to the upper layer can be gradually cured by gradually increasing the illuminance of the ultraviolet rays irradiated from the third irradiation region M3 in the feed direction F. Thereby, rapid hardening shrinkage | contraction of clear ink can be suppressed, and the generation | occurrence | production of the stripe between passes and the fall of a glossiness can be suppressed.

  In addition, by setting the peak illuminance in the third irradiation area M3 to be smaller than the peak illuminance in the first irradiation area M1, the curing speed of the clear ink in the upper layer can be reduced. Thereby, it is possible to further suppress the generation of stripes between passes and the reduction in glossiness.

  Furthermore, according to the present embodiment, the illuminance of ultraviolet rays irradiated to the medium can be adjusted by the arrangement and shape of the mask 43 provided in the UVLED unit 41, and therefore the illuminance distribution of ultraviolet rays emitted from the ultraviolet irradiation device 4 Can be adjusted easily.

  Then, by gradually narrowing the width of the second portion 43b of the mask 43 toward the rear in the feed direction F (gradually widening toward the feed direction F), the illuminance of ultraviolet rays applied to the medium can be simply set in the feed direction. It can be gradually lowered toward F.

  Further, by gradually narrowing the width of the third portion 43c of the mask 43 toward the front in the feed direction F, the illuminance of ultraviolet rays applied to the media can be gradually increased toward the feed direction F. .

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment. For example, in the above embodiment, the illuminance distribution in the first irradiation region M1 has been described as having high illuminance as a whole, but the illuminance distribution in the first irradiation region M1 may be any illuminance distribution. For example, the illuminance distribution in the first irradiation region M1 may be an illuminance at which the ultraviolet curable ink is not cured as a whole.

  In the above embodiment, the color ink and the clear ink are ejected from the inkjet head 6. However, only the color ink or only the clear ink may be ejected. In this case, it is preferable to discharge the color ink or the clear ink from all the nozzle rows regardless of the first discharge area A1 and the second discharge area A2 of the inkjet head 6. Even in such a case, it is only necessary to block the ultraviolet rays irradiated from the front in the feed direction F of the ultraviolet irradiation device 4, and the illuminance distribution in the first irradiation region M1 may be any illuminance distribution. For example, the illuminance distribution in the first irradiation area M1 may be the illuminance that the ultraviolet curable ink is not cured as a whole, and the illuminance distribution in the first irradiation area M1 is the illuminance at which the rear part in the feed direction F is cured by the ultraviolet curable ink. Further, the illuminance at which the front part of the feed direction F is not cured by the ultraviolet curable ink may be used.

  In the above-described embodiment, the UV LED is used as the ultraviolet irradiation device. However, any device such as a metal halide lamp may be used as long as the ultraviolet curable ink can be irradiated with ultraviolet rays.

  Moreover, although the said embodiment demonstrated as what adjusts the illumination intensity distribution of an ultraviolet-ray with the mask 43, you may adjust with other various methods, such as lighting control of each UVLED which comprises the UVLED unit 41. FIG. When UVLED lighting control is adopted, each UVLED is individually controlled to be turned off, the UVLEDs arranged in the second irradiation region M2 are turned off, and the UVLEDs arranged in the first irradiation region M1 and the third irradiation region M3 are turned off. The above illuminance distribution can be realized by adjusting the illuminance of the arranged UVLED.

  In the above embodiment, the medium and the head unit 3 (carriage 2) are moved relative to each other in the feed direction F by conveying the medium. However, the medium and the head are actually moved. Either unit 3 (carriage 2) or both of them may be moved. For example, the present invention may be applied to a flat bed type inkjet printer including a flat bed on which a medium is placed and fixed, and a mechanism for moving the head unit 3 (carriage 2). In the case of this flat bed type ink jet printer, the feed direction F of the present invention is opposite to the direction in which the head unit 3 (carriage 2) moves for printing.

Claims (13)

A carriage capable of reciprocating in the scanning direction;
An ink ejection unit that is mounted on the carriage and ejects ultraviolet curable ink onto a recording medium;
Ultraviolet irradiation means mounted on the carriage and disposed at least one of the front and rear in the scanning direction of the ink discharge means to irradiate the recording medium with ultraviolet rays,
An inkjet printer in which the recording medium moves relative to the ink ejection means in a feed direction orthogonal to the scanning direction;
The ultraviolet irradiation means includes
In the scanning direction, the irradiation of ultraviolet rays from a position corresponding to the front portion in the feed direction of the ink ejection means is blocked, and the position in the scanning direction corresponds to the front of the feed direction relative to the front portion. An inkjet printer characterized by irradiating ultraviolet rays from a position corresponding to the front in the feed direction relative to the ink discharge means . The ultraviolet irradiation means includes
The ink jet printer according to claim 1, characterized in that the illuminance of the ultraviolet rays irradiated from a position corresponding to the feed forward than the ink discharge means in the scanning direction, gradually increasing toward the feed direction. The ultraviolet irradiation means includes
3. The inkjet printer according to claim 1, wherein ultraviolet rays are irradiated from a position corresponding to a rear portion in the feed direction of the ink discharge unit in the scanning direction. A carriage capable of reciprocating in the scanning direction;
An ink ejection unit that is mounted on the carriage and ejects ultraviolet curable ink onto a recording medium;
Ultraviolet irradiation means mounted on the carriage and disposed at least one of the front and rear in the scanning direction of the ink discharge means to irradiate the recording medium with ultraviolet rays,
An inkjet printer in which the recording medium moves relative to the ink ejection means in a feed direction orthogonal to the scanning direction;
The ink ejection means includes
It is divided into a first discharge area disposed behind the feed direction and a second discharge area disposed forward of the feed direction,
The ultraviolet irradiation means includes
Of the second irradiation area corresponding to the second ejection area in the scanning direction, the irradiation of ultraviolet rays from the front part in the feed direction is blocked , and the front side in the scanning direction corresponds to the front in the feed direction. An inkjet printer characterized by irradiating ultraviolet rays from a third irradiation area corresponding to the position in the feed direction and ahead of the second ejection area . The ink ejection means includes
Discharging colored ultraviolet curable ink from the first discharge region;
The inkjet printer according to claim 4 , wherein an ultraviolet curable ink having translucency is discharged from the second discharge region. The ultraviolet irradiation means includes
The inkjet printer according to claim 4 , wherein ultraviolet rays are irradiated from a rear portion of the second irradiation region in the feed direction. The ultraviolet irradiation means includes
The inkjet printer according to claim 4 , wherein ultraviolet rays are emitted from a first irradiation region corresponding to the first ejection region in the scanning direction. The ultraviolet irradiation means includes
The inkjet printer according to any one of claims 4 to 7 , wherein the illuminance of ultraviolet rays irradiated from the third irradiation region is gradually increased toward the feed direction. The ultraviolet irradiation means includes
9. The inkjet printer according to claim 8 , wherein a peak illuminance of ultraviolet rays irradiated from the third irradiation region is made smaller than a peak illuminance of ultraviolet rays irradiated from the first irradiation region. The ultraviolet irradiation means includes
An ultraviolet irradiation unit that emits ultraviolet rays toward the recording medium;
A mask member which is provided on the recording medium side of the ultraviolet ray emitting unit and blocks passage of ultraviolet rays emitted from the ultraviolet ray irradiating unit;
The inkjet printer according to any one of claims 1 to 9 , further comprising: The inkjet printer according to claim 10 , wherein a width of the rear end portion of the mask in the feed direction is gradually narrowed toward the rear in the feed direction. The inkjet printer according to claim 10 or 11 , wherein a width of the front end portion of the mask in the feed direction is gradually narrowed forward in the feed direction. The ultraviolet irradiation means includes
A plurality of UVLEDs arranged in the feed direction;
A lighting control unit that performs lighting control of the plurality of UVLEDs;
The inkjet printer according to any one of claims 1 to 9 , further comprising:

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