JP2008188983A - Ultraviolet irradiation device, recording apparatus using the ultraviolet irradiation device, and recording method - Google Patents

Abstract

A skin in which only the surface of an ink cures an ultraviolet curable ink deposited on a recording medium during printing (for example, monocolor printing) in which the thickness of the ink deposited on the recording medium is relatively large. Provided is an ultraviolet irradiation device that can be cured well without causing a problem of tension.
Ultraviolet irradiation devices 190A and 190B are attached to a carriage 50 on which a print head 52 that ejects ultraviolet curable ink is mounted, and ultraviolet rays are applied to an ink film 196 that the print head 52 ejects onto a printing paper P. A plurality of ultraviolet light sources 192 and 193 for irradiation are provided. The ultraviolet light 193 a of the ultraviolet light source 193 that irradiates the print paper P near the print head 52 is more than the ultraviolet light 192 a of the ultraviolet light source 192 that irradiates the print paper P that is separated from the vicinity of the print head 52 in the moving direction of the carriage 50. The wavelength is long.
[Selection] Figure 2

Description

  The present invention relates to an ultraviolet irradiation apparatus including an ultraviolet light source that irradiates ultraviolet rays to ultraviolet curable ink ejected onto a recording medium by a recording head, a recording apparatus using the ultraviolet irradiation apparatus, and a recording method. .

In recent years, ultraviolet curable inks have attracted attention as inks used in inkjet printers and the like.
UV curable ink differs from normal water-based ink or oil-based ink in that it adheres to a recording medium (printing paper), etc., and then quickly cures when irradiated with an appropriate amount of ultraviolet light, thereby recording ink such as ink permeability. This is the point that stable printing quality can be maintained without being influenced by the physical properties.

  In an ink jet recording apparatus (ink jet printer) using such an ultraviolet curable ink, the ultraviolet curable ink is ejected as fine ink droplets and adhered to the recording medium around the recording head. It is necessary to equip the ink with an ultraviolet irradiating device for irradiating the ink with an ultraviolet ray, and a carriage equipped with the ultraviolet irradiating device is proposed in which a recording head is mounted and reciprocated in the width direction of the recording medium ( For example, see Patent Document 1).

Japanese Patent Laid-Open No. 2004-237603

  By the way, in general, ultraviolet rays having a long wavelength have a stronger permeability to the ink film than ultraviolet rays having a short wavelength, and ultraviolet rays having a short wavelength tend to have a larger energy of one photon than ultraviolet rays having a long wavelength. Therefore, printing that increases the ink film thickness by increasing the ink ejection amount to print on a film, such as a packaging package, or increasing the pigment concentration to obtain high color development (for example, large size When mono-color printing on a poster or the like), there is a problem that the surface peels off due to rubbing of the stacked recording media, and uncured ink oozes out from the inside and stains the surroundings.

This is because, when the ultraviolet ray irradiated to the thick ink film has a short wavelength, curing starts immediately from the surface of the ink film, and the ultraviolet ray cannot reach inside the ink film. This is because the curing of only the surface of the ink film adhering to the ink proceeds and the inside becomes a skinned state of insufficient curing.
Accordingly, an object of the present invention is to solve the above-described problems, and in the printing in which the film thickness of the ink attached to the recording medium is relatively thick, the ultraviolet curable ink attached on the recording medium is used as the ink. It is to provide an ultraviolet irradiation apparatus and a recording method that can be cured well without causing the problem of skinning in which only the surface of the film is cured. Another object of the present invention is to provide a recording apparatus using the ultraviolet irradiation apparatus.

The above object of the present invention is an ultraviolet irradiation apparatus including an ultraviolet light source that irradiates ultraviolet rays to ultraviolet curable ink jetted onto a recording medium by a recording head,
The ultraviolet light of the ultraviolet light source that irradiates the recording medium near the recording head has a longer wavelength than the ultraviolet light of the ultraviolet light source that irradiates the recording medium far from the vicinity of the recording head. This can be achieved with an irradiation device.

According to the ultraviolet irradiation apparatus having the above-described configuration, the ink film ejected onto the recording medium by ejection from the recording head is first irradiated with ultraviolet light having a long wavelength that irradiates the recording medium near the recording head. The inner part of the film is cured. Thereafter, ultraviolet light having a short wavelength for irradiating the recording medium away from the vicinity of the recording head is irradiated to the ink film, and the surface of the ink film is cured.
For this reason, for example, even in monocolor printing where the viscosity of the ink is high and the film thickness of the ink film is relatively thick, there is a problem of skinning in which only the surface of the UV curable ink attached on the recording medium is cured. And can be cured well.
The “wavelength” referred to here indicates a wavelength that is a peak of light emitted from the light source. “Monocolor printing” also includes an aspect in which the recording head ejects one or more colors of ultraviolet curable ink to make each one or more colors monochromatic printing.

  In the ultraviolet irradiation apparatus having the above-described configuration, the ultraviolet irradiation apparatus includes a plurality of ultraviolet light sources, and the plurality of ultraviolet light sources are disposed near the recording head, and the light source for long wavelengths is more than the light source for long wavelengths. And a short wavelength light source disposed away from the recording head.

According to the ultraviolet irradiation device having the above-described configuration, first, with respect to the ink film ejected onto the recording medium by ejection from the recording head, the recording in the vicinity of the recording head is performed from the long wavelength light source disposed in the vicinity of the recording head. The medium is irradiated with ultraviolet rays having a long wavelength, and the inner part of the ink film is cured. Thereafter, the ink film is irradiated with ultraviolet rays having a short wavelength that irradiates the recording medium away from the vicinity of the recording head from the short wavelength light source disposed farther from the recording head than the long wavelength light source. The film surface is cured.
Moreover, according to the ultraviolet irradiation device having such a configuration, the layout of the long wavelength light source and the short wavelength light source is easy and the configuration of the ultraviolet light source is simplified, so that the manufacturing cost can be reduced.

  In the ultraviolet irradiation apparatus having the above-described configuration, it is preferable that the plurality of ultraviolet light sources irradiate the recording medium with ultraviolet rays whose wavelengths are sequentially shortened as they are separated from the vicinity of the recording head.

  According to the ultraviolet irradiation device having such a configuration, it is possible to irradiate the ink film ejected on the recording medium with ultraviolet rays having a wavelength that gradually decreases from a long wavelength. Therefore, even if the ink film is thick, it can be cured sequentially from the inner side of the ink film, and finally the surface side can be cured, and the entire ink film can be reliably cured.

  In addition, it is desirable that the ultraviolet irradiation apparatus having the above-described configuration includes a unit that separates ultraviolet rays emitted from the ultraviolet light source into a plurality of ultraviolet rays having different wavelengths.

According to the ultraviolet irradiation apparatus having the above-described configuration, the long-wavelength ultraviolet light separated by the means for separating the plurality of ultraviolet light having different wavelengths is first applied to the ink film ejected onto the recording medium by the ejection from the recording head. Irradiation is performed on a recording medium in the vicinity of the recording head, and the inner part of the ink film is cured. Thereafter, ultraviolet light having a short wavelength separated by the means is applied to the ink film on the recording medium away from the vicinity of the recording head to cure the surface of the ink film.
According to such means, it is possible to separate the ultraviolet rays emitted from the ultraviolet light source into a plurality of ultraviolet rays having different wavelengths without installing a plurality of ultraviolet light sources.

  In the ultraviolet irradiation apparatus having the above-described configuration, it is desirable that the means is a filter that preferentially transmits a specific wavelength.

  According to the ultraviolet irradiation apparatus having such a configuration, the ultraviolet light irradiated onto the recording medium from the ultraviolet light source is reliably wavelength-separated by the filter interposed between the ultraviolet light source and the recording medium, and the ultraviolet light having a long wavelength is the wavelength. It is possible to obtain a state in which the ink on the recording medium is irradiated before the short ultraviolet rays.

  In the ultraviolet irradiation device having the above-described configuration, it is desirable that a reflection mechanism is disposed at a position facing the filter, and that the ultraviolet light emitted from the ultraviolet light source is reflected to the filter side.

According to the ultraviolet irradiation device having such a configuration, the ultraviolet light emitted from the ultraviolet light source to the side opposite to the filter side is also returned to the filter side by reflection by the reflection mechanism and used for curing the ultraviolet curable ink. Therefore, the utilization efficiency of ultraviolet rays emitted from the ultraviolet light source is improved.
Further, for example, the reflecting surface of the reflecting mechanism is a parabolic curved surface having the light emission center of the ultraviolet light source as a focal point, so that the direction of ultraviolet rays that pass through the filter is aligned, and the intensity of ultraviolet rays irradiated to the ink is made uniform. In addition, the curing performance of the ink by ultraviolet irradiation can be stabilized.

  In the ultraviolet irradiation apparatus having the above-described configuration, it is desirable that the means separates the ultraviolet rays so that the wavelength to be transmitted becomes shorter as the distance from the vicinity of the recording head increases.

  According to the ultraviolet irradiation device having such a configuration, it is possible to irradiate the ink film ejected on the recording medium with ultraviolet rays having a wavelength that gradually decreases from a long wavelength. Therefore, even if the ink film is thick, it can be cured sequentially from the inner side of the ink film, and finally the surface side can be cured, and the entire ink film can be reliably cured.

Furthermore, in the ultraviolet irradiation device having the above configuration, the recording head is a line-type head provided over the width direction of the recording medium,
The ultraviolet light of the ultraviolet light source that irradiates the recording medium in the vicinity of the recording head is more than the ultraviolet light of the ultraviolet light source that irradiates the recording medium away from the vicinity of the recording head along the feeding direction of the recording medium. A long wavelength is desirable.

  According to the ultraviolet irradiation apparatus having such a configuration, the wavelength at which the ink film ejected onto the recording medium by the ejection from the line type head is first irradiated onto the recording medium near the line type head on the paper discharge side. Is irradiated with UV light, and the inner part of the ink film is cured. Thereafter, ultraviolet rays having a short wavelength for irradiating the recording medium away from the vicinity of the recording head are irradiated to the ink film, and the surface of the ink film can be cured.

Further, in the ultraviolet irradiation device having the above configuration, the recording head is a head mounted on a carriage,
The ultraviolet light of the ultraviolet light source that irradiates the recording medium in the vicinity of the recording head has a wavelength greater than the ultraviolet light of the ultraviolet light source that irradiates the recording medium that is separated from the vicinity of the recording head along the moving direction of the carriage. It is desirable that is long.

  According to the ultraviolet irradiation device having such a configuration, the ink film ejected on the recording medium by the ejection from the recording head is first irradiated with ultraviolet light having a long wavelength that irradiates the recording medium near the recording head. The inner part of the ink film is cured. Thereafter, while moving the carriage, the ink film is irradiated with ultraviolet rays having a short wavelength that irradiates the recording medium away from the vicinity of the recording head along the moving direction of the carriage, and the surface of the ink film can be cured. .

  In the ultraviolet irradiation device having the above-described configuration, it is preferable that the ultraviolet irradiation device is provided on both side ends along the moving direction of the carriage.

  According to the ultraviolet irradiation device having such a configuration, ink is ejected from the recording head onto the recording medium while reciprocating the carriage, and the ultraviolet irradiation device located on the rear side in the head scanning direction irradiates the ultraviolet rays. The ink film can be quickly cured regardless of the carriage head scanning direction, and the printing speed can be improved.

In the ultraviolet irradiation device having the above-described configuration, it is desirable that the ultraviolet light source is at least one selected from an LED, an LD, a mercury lamp, a metal halide lamp, a xenon lamp, or an excimer lamp.
In particular, when the ultraviolet irradiation device is configured to have a plurality of ultraviolet light sources, by using either an LED or an LD as the ultraviolet light source, ultraviolet light having a short wavelength and a long wavelength can be used alone without using a filter or the like. Each light source can be prepared. Therefore, for example, compared with the case where a mercury lamp, a metal halide lamp, or other lamps are used as the ultraviolet light source, it is possible to avoid an increase in the size of the ultraviolet irradiation device due to the installation of a filter or the like. The ultraviolet ray curable ink can be efficiently cured without lowering the ultraviolet ray intensity.
On the other hand, when the ultraviolet light emitted from the ultraviolet light source is separated into ultraviolet light having different wavelengths by the filter, the wavelength of the ultraviolet light can be adjusted by the filter, so that the degree of freedom in selecting the ultraviolet light source is high. Therefore, for example, when the wavelength range of ultraviolet rays absorbed by the coloring material (pigment or dye) contained in the ultraviolet curable color ink, the curing temperature, etc. are different, the wavelength suitable for the physical properties of the ink By selecting an ultraviolet light source having a region and a heat generation temperature, it is possible to realize the ink curing process by irradiation with ultraviolet light more efficiently.

  Also, the above object of the present invention is achieved by a recording apparatus provided with the above ultraviolet irradiation device.

  According to the recording apparatus having such a configuration, for example, the ultraviolet curable ink adhered onto the recording medium even during recording (for example, monocolor printing) where the viscosity of the ink is high and the ink film is relatively thick. Recording can be performed satisfactorily without incurring the problem of skinning in which only the surface of the film is cured.

The above-mentioned object of the present invention is a recording method for monocolor printing on a recording medium using an ultraviolet curable ink,
When the ultraviolet curable ink ejected from the recording head onto the recording medium is cured, the ultraviolet rays of the ultraviolet light source that irradiates the recording medium near the recording head are separated from the vicinity of the recording head. This is achieved by a recording method characterized in that the ultraviolet curable ink is cured by irradiating ultraviolet rays having a wavelength longer than that of the ultraviolet light source that irradiates the ultraviolet light.

  According to the recording method having such a configuration, only the surface of the ultraviolet curable ink adhered on the recording medium is obtained even in monocolor printing where the viscosity of the ink is high and the ink film is relatively thick. It can be cured satisfactorily without incurring the problem of hardening skin.

Hereinafter, an example of an embodiment of an ultraviolet irradiation apparatus, a recording apparatus using the ultraviolet irradiation apparatus, and an ultraviolet irradiation method according to the present invention will be described in detail with reference to the drawings.
FIG. 1 is a perspective view of an ink jet recording apparatus equipped with an ultraviolet irradiation apparatus according to the first embodiment of the present invention.

  An ink jet printer (ink jet recording apparatus) 20 shown in FIG. 1 has a paper feed motor 30 that feeds printing paper P as a recording medium in the sub-scanning direction SS, a platen 40, and ultraviolet curable ink with a small particle size. A print head 52 as a recording head that is ejected from the head nozzle and adheres to the print paper P, a carriage 50 on which the print head 52 is mounted, a carriage motor 60 that moves the carriage 50 in the main scanning direction MS, and the print head 52 Are provided with a pair of ultraviolet irradiation devices 90A and 90B for irradiating the ink adhering surface on the printing paper P to which the ultraviolet curable ink is adhered.

The carriage 50 is pulled by a pulling belt 62 driven by a carriage motor 60 and moves along a guide rail 64.
The print head 52 shown in the first embodiment is a so-called serial head for full-color printing that ejects ink of three or more colors, and is provided with a large number of head nozzles for each color. In addition to the print head 52 described above, the carriage 50 on which the print head 52 is mounted is supplied to the print head 52 and a black cartridge 54 as a black ink container containing black ink to be supplied to the print head 52. And a color ink cartridge 56 as a color ink container containing the color ink.
The ink stored in each cartridge 54, 56 is a so-called ultraviolet curable ink.

  A capping device 80 for sealing the nozzle surface of the print head 52 when stopped is provided at the home position of the carriage 50 (the position on the right side in FIG. 1). When the print job ends and the carriage 50 reaches above the capping device 80, the capping device 80 is automatically raised by a mechanism (not shown) to seal the nozzle surface of the print head 52. This capping prevents the ink in the nozzles from drying out. The positioning control of the carriage 50 is performed to accurately position the carriage 50 at the position of the capping device 80, for example.

2 is a front view of the ultraviolet irradiation device 90A (corresponding to 190A in FIG. 2) and 90B (corresponding to 190B in FIG. 2) shown in FIG. 1, and FIG. 3 is a view taken along the line AA in FIG.
As shown in FIGS. 1 to 3, the ultraviolet irradiation devices 190 </ b> A and 190 </ b> B are respectively attached to both side ends facing the moving direction of the carriage 50.
As shown in FIG. 2, the ultraviolet irradiation device 190A mounted on the left side of the print head 52 discharges onto the printing paper P during the right scanning when the carriage 50 moves in the right direction (the direction of arrow B in FIG. 2). The applied ink film 196 is irradiated with ultraviolet rays. On the other hand, the ultraviolet irradiation device 190B attached to the right side of the print head 52 has an ink film 196 discharged onto the printing paper P during left scanning when the carriage 50 moves leftward (in the direction of arrow C in FIG. 2). Is irradiated with ultraviolet rays.
Each of the ultraviolet irradiation devices 190A and 190B is attached to the carriage 50 and has a housing 194 in which a plurality of two types of ultraviolet light sources 192 and 193 having different wavelengths of emitted ultraviolet light are aligned and supported, and each ultraviolet light source 192 and 193. And a light source control circuit (not shown) that controls light emission and extinction of the light source.

The ultraviolet light source 192 provided in each of the ultraviolet irradiation devices 190A and 190B is a short wavelength light source that emits ultraviolet light having a short wavelength of about 360 nm, and the ultraviolet light source 193 has an ultraviolet wavelength of about 390 nm that is longer than the ultraviolet light source 192. Is a long wavelength light source.
In the case of the first embodiment, two of these two kinds of ultraviolet light sources 192 and 193 are arranged in each of the ultraviolet irradiation devices 190A and 190B.

  Further, as shown in FIGS. 2 and 3, these two types of ultraviolet light sources 192 and 193 are arranged such that the ultraviolet light source 193 having a long wavelength of emitted ultraviolet light is closer to the print head 52 than the ultraviolet light source 192 having a short wavelength. As shown, the plurality of ultraviolet light sources 192 and 193 are separated from the print head 52 along the moving direction of the carriage 50 (the direction of arrow B or arrow C in FIG. 2) L11, L12 (where L11 <L12 ) At a plurality of attachment positions S11 and S12.

  Further, a light source control circuit (not shown) that controls the light emission and extinction of each ultraviolet light source 192, 193 is such that the ultraviolet light 193a emitted from the ultraviolet light source 193 is longer than the ultraviolet light 192a emitted from the ultraviolet light source 192. Further, the light emission timings of the ultraviolet light sources 192 and 193 are controlled so that the ink film 196 attached on the printing paper P is irradiated.

  In the case of the first embodiment, either an LED or an LD is used for each of the ultraviolet light sources 192 and 193. Therefore, it is possible to prepare short-wavelength and long-wavelength ultraviolet light sources with a single light source without using a filter or the like. Therefore, for example, compared with the case where a mercury lamp, a metal halide lamp, or other lamps are used as the ultraviolet light source, it is possible to avoid an increase in the size of the ultraviolet irradiation device due to the installation of a filter or the like. The ultraviolet ray curable ink can be efficiently cured without lowering the ultraviolet ray intensity.

The selection of the ultraviolet light source mounted on the housing 194 is performed in consideration of the allowable dimensions that can be mounted on the housing 194, the allowable temperature around the print head 52, and the like. An ultraviolet light source appropriately selected from metal halide lamps, xenon lamps and excimer lamps can also be used.
That is, when the wavelength range of ultraviolet rays absorbed by the coloring material (pigment or dye) contained in the ultraviolet curable color ink, the curing temperature, etc. are different, the wavelength range suitable for the physical properties of the ink By selecting an ultraviolet light source having an exothermic temperature, it is possible to realize the ink curing process by ultraviolet irradiation more efficiently.

  According to the ultraviolet irradiation devices 190A and 190B described above, first, as shown in FIG. 2, printing is performed on the ink film 196 ejected from the print head 52 onto the printing paper P as a recording medium. The ultraviolet light source 193 that irradiates the print paper P near the head 52 is irradiated with ultraviolet light 193a having a long wavelength, and the inner part of the ink film 196 is cured. Thereafter, while moving the carriage 50, the ultraviolet light source 192 that irradiates the print paper P away from the vicinity of the print head 52 along the moving direction of the carriage 50 irradiates the ink film 196 with ultraviolet light 192a having a short wavelength, The surface of the ink film 196 is cured.

  Therefore, as in the present embodiment, even when printing is performed with a high ink viscosity and a relatively thick ink film 196, the ultraviolet irradiation devices 190A and 190B apply the ultraviolet curable ink attached on the printing paper P to the surface. It can be cured satisfactorily without incurring the problem of skinning that only cures.

The configuration of the ultraviolet irradiation apparatus according to the present invention is not limited to the configuration of the recording head, carriage, ultraviolet light source, and the like in the above-described embodiment, and various forms can be taken based on the spirit of the present invention. Needless to say.
For example, in the above embodiment, the two ultraviolet light sources 192 and 193 are provided as the ultraviolet light sources having different wavelengths of the emitted ultraviolet rays. However, three or more kinds of ultraviolet light sources having different wavelengths of the emitted ultraviolet rays may be used. good. In that case, it is preferable to arrange each ultraviolet light source so that the wavelength of the emitted ultraviolet light becomes shorter as the distance from the print head 52 becomes longer.

  In such a case, it is possible to irradiate the ink film 196 ejected on the printing paper P with ultraviolet light whose wavelength gradually decreases in order from a long wavelength. Therefore, even if the film thickness of the ink film 196 is large, the ink film 196 can be sequentially cured from the inner side and finally the surface side can be cured, and the entire ink film 196 can be reliably cured.

  In the above-described embodiment, the ultraviolet light source 193 that emits the ultraviolet light 193a having a long wavelength is disposed closer to the print head 52 than the ultraviolet light source 192 that emits the ultraviolet light 192a having a short wavelength. The ultraviolet light of the ultraviolet light source that irradiates the printing paper P is configured to have a longer wavelength than the ultraviolet light of the ultraviolet light source that irradiates the printing paper P away from the vicinity of the print head 52 along the moving direction of the carriage 50. However, it is also possible to arrange the ultraviolet light source 192 and the ultraviolet light source 193 at an equal distance from the print head 52, or arrange the ultraviolet light source 192 closer to the print head 52 than the ultraviolet light source 193. That is, the ultraviolet light sources 192 and 193 so that the ultraviolet light 193a of the ultraviolet light source 193 irradiates the printing paper P near the print head 52 and the ultraviolet light 192a of the ultraviolet light source 192 irradiates the printing paper P away from the printing head 52. If the irradiation directions are respectively set, the attachment positions of the ultraviolet light sources 192 and 193 can be changed as appropriate.

In the above embodiment, the serial type head is used as the print head 52 that ejects the ultraviolet curable ink onto the recording medium. However, the recording head of the present invention is not limited to this.
Next, an ink jet recording apparatus equipped with the ultraviolet irradiation device according to the second embodiment of the present invention will be described.
An ink jet printer (ink jet recording apparatus) 1 according to the second embodiment of the present invention shown in FIG. 4 includes a paper feed roller 2 for feeding a printing paper P as a recording medium from a paper tray (not shown), and printing. A transport roller 3 for transporting the paper P, a driven roller 4 provided to face the transport roller 3, a platen 5 for supporting the print paper P, and a recording head provided to face the platen 5 And an ultraviolet irradiation device 7 for irradiating the ink adhering surface on the printing paper P on which the ultraviolet curable ink is adhered by the print head 6 with ultraviolet rays.

As shown in FIG. 5, the print head 6 is a line type head including a plurality of head modules 10 </ b> A to 10 </ b> D on the side corresponding to the platen 5. Each of the head modules 10A to 10D includes a nozzle 11 formed so as to form a four-row line arrangement along the paper width direction (X-axis direction), a liquid chamber communicating with each of the nozzles 11, and the liquid And a piezoelectric element (not shown) for generating pressure in the chamber.
Then, the head modules 10A to 10D perform full color printing by ejecting black, cyan, magenta, and yellow inks supplied from an ink supply means (not shown) from the nozzles 11 for each line array. ing.

In FIG. 5, the ultraviolet irradiation device 17 (corresponding to the ultraviolet irradiation device 7 shown in FIG. 4) is attached to the print head 6 so as to be positioned on the paper discharge side, as shown in FIGS. .
The ultraviolet irradiation device 17 is attached to the print head 6, and controls a housing 34 that aligns and supports two types of ultraviolet light sources 18 and 19 having different wavelengths of emitted ultraviolet light, and controls light emission and extinction of the ultraviolet light sources 18 and 19. And a light source control circuit (not shown).

The ultraviolet light source 18 provided in the ultraviolet irradiation device 17 is a short wavelength light source that emits ultraviolet light having a short wavelength of about 360 nm, and the ultraviolet light source 19 emits ultraviolet light having a wavelength of about 390 nm longer than the ultraviolet light source 18. It is a long wavelength light source.
As shown in FIGS. 5 and 6, these two types of ultraviolet light sources 18 and 19 are arranged such that the ultraviolet light source 19 having a long wavelength of emitted ultraviolet light is closer to the print head 6 than the ultraviolet light source 18 having a short wavelength. As described above, the two ultraviolet light sources 18 and 19 set the separation distances L11 and L12 (where L11 <L12) from the center of the print head 6 along the conveyance direction of the printing paper P (the direction of arrow D in FIG. 6). It is equipped with a plurality of mounting positions S11 and S12.

  Furthermore, the light source control circuit (not shown) that controls the light emission and extinction of the respective ultraviolet light sources 18 and 19 is such that the ultraviolet light having a long wavelength emitted from the ultraviolet light source 19 precedes the ultraviolet light having a short wavelength emitted from the ultraviolet light source 18. The light emission timings of the ultraviolet light sources 18 and 19 are controlled so that the ink film 196 attached on the printing paper P is irradiated.

  In the case of the second embodiment, a mercury lamp, a metal halide lamp, or other lamps that are long in the paper width direction are used for the ultraviolet light sources 18 and 19, and the ink film 296 attached on the printing paper P is applied to the ultraviolet light sources 18 and 19. It is cured uniformly along the paper width direction.

The selection of the ultraviolet light source to be mounted on the casing 34 is performed in consideration of the allowable dimensions that can be mounted on the casing 34, the allowable temperature around the print head 6, and the like. Therefore, a mercury lamp, a metal halide lamp, and other lamps are used. Not limited to this, an ultraviolet light source such as LED or LD can also be used.
That is, when the wavelength range of ultraviolet rays absorbed by the coloring material (pigment or dye) contained in the ultraviolet curable color ink, the curing temperature, etc. are different, the wavelength range suitable for the physical properties of the ink By selecting an ultraviolet light source having an exothermic temperature, it is possible to realize the ink curing process by ultraviolet irradiation more efficiently.

  According to the ultraviolet irradiation device 17 described above, as shown in FIG. 6, the ink film 196 ejected on the printing paper P, which is a recording medium, is ejected from the plurality of head modules 10 </ b> A to 10 </ b> D of the print head 6. On the other hand, first, the ultraviolet light source 19 that irradiates the print paper P in the vicinity of the print head 6 is irradiated with ultraviolet light 19 a having a long wavelength to cure the inner part of the ink film 196. Thereafter, while feeding the printing paper P, the ultraviolet light source 18 that irradiates the printing paper P away from the vicinity of the printing head 6 along the feeding direction (Y-axis direction) of the printing paper P causes the ultraviolet light 18 a having a short wavelength to be applied to the ink film 196. The surface of the ink film 196 is cured.

  Therefore, the ultraviolet irradiation device 17 cures only the surface of the ultraviolet curable ink deposited on the printing paper P even during printing with a high ink viscosity and a relatively thick ink film as in the present embodiment. It can be cured well without causing the problem of skinning.

Next, an ink jet recording apparatus equipped with the ultraviolet irradiation device according to the third embodiment of the present invention will be described.
The third embodiment is the same as the first embodiment described above except that the ultraviolet irradiation devices 290A and 290B shown in FIG. 7 are mounted as the ultraviolet irradiation devices 90A and 90B in FIG. 1 described above. .
As shown in FIG. 7, each of the ultraviolet irradiation devices 290A and 290B is attached to a carriage 50 and supports the ultraviolet light source 291 at a predetermined distance from the print head 52 by being attached to a carriage 50. A housing 293, two filters F1 and F2 for separating the ultraviolet light UVsl in the wide wavelength range emitted from the ultraviolet light source 291 into the ultraviolet light UVl having a long wavelength and the ultraviolet light UVs having a short wavelength, and the ultraviolet light source 291. In addition, a reflection mechanism 294 that reflects the ultraviolet light UVsl in a wide wavelength range toward the two filters F1 and F2 and a light source control circuit (not shown) that controls light emission and extinction of the ultraviolet light source 291 are provided.

  As the ultraviolet light source 291, it is preferable to use at least one selected from a mercury lamp, a metal halide lamp, a xenon lamp, an excimer lamp, and the like having a wide wavelength range of emitted ultraviolet light.

  Of the two filters F1 and F2, which are filters that preferentially transmit a specific wavelength, one filter F1 is a length that transmits only ultraviolet light having a long wavelength of about 390 nm when irradiated with ultraviolet light UVsl in a wide wavelength region. It is a wavelength filter. The other filter F2 is a short wavelength filter that transmits only ultraviolet rays having a short wavelength of 300 nm or less when irradiated with ultraviolet rays UVsl in a wide wavelength range.

  In the present embodiment, the two filters F1 and F2 as means for separating the ultraviolet rays into a plurality of ultraviolet rays having different wavelengths are arranged between the ultraviolet light source 291 and the printing paper P, but the print head 52 is used. A filter F1 is provided on the vicinity side, and a filter F2 is provided on the side away from the vicinity of the print head 52 along the moving direction of the carriage 50. That is, as shown in FIG. 7, the filters F1 and F2 include two filters F1 such that the filter F1 that is a long wavelength filter is disposed closer to the print head 6 than the filter F2 that is a short wavelength filter. , F2 have a plurality of attachment positions S21, S22 having separation distances L21, L22 (where L21 <L22) from the center of the print head 6 along the scanning direction of the carriage 50 (the direction of the arrow MS1 or MS2 in FIG. 7). Equipped with.

  Therefore, the ultraviolet light UVsl in a wide wavelength range irradiated on the printing paper P from the ultraviolet light source 291 is reliably wavelength-separated by the filters F1 and F2 interposed between the ultraviolet light source 291 and the printing paper P, and has a long wavelength. It is possible to obtain a state in which the ultraviolet ray UVl is applied to the ink on the printing paper P before the ultraviolet ray UVs having a short wavelength.

The reflection mechanism 294 is disposed at a position facing the filters F1 and F2, and reflects the ultraviolet rays emitted from the ultraviolet light source 291 toward the filters F1 and F2.
The reflection surface 294a of the reflection mechanism 294 is formed in, for example, a parabolic curved surface that focuses on the light emission center of the ultraviolet light source 291 and reflects the ultraviolet light incident from the ultraviolet light source 291 in parallel to the axis of the parabolic curved surface. The light is incident on the filters F1 and F2.

  With the above configuration, a near region where the separation distance from the print head 52 is less than a predetermined distance on the printing paper P is irradiated with the long wavelength ultraviolet light UVl separated by the filter F1, and the separation distance from the print head 52 is predetermined. The far region as described above can be irradiated with ultraviolet rays UVs having a short wavelength separated by the filter F2.

  In the ultraviolet irradiation devices 290A and 290B according to this embodiment, first, ultraviolet light UVl having a long wavelength separated by the filter F1 is printed on the ink film 296 ejected on the printing paper P by ejection from the print head 52. Irradiation is applied to the printing paper P in the vicinity of the head 52 and the inner part of the ink film 296 is cured. Thereafter, while moving the carriage 50, the ultraviolet rays UVs having a short wavelength separated by the filter F2 are applied to the ink film 296 on the printing paper P away from the vicinity of the print head 52, and the surface of the ink film 296 is cured. .

  Therefore, for example, even when printing is performed with a high ink viscosity and a relatively thick ink film, the surface of the ultraviolet curable ink attached on the recording medium is not cured, and it does not incur the problem of skinning. Can be cured.

Furthermore, in the ultraviolet irradiation devices 290A and 290B of the above-described embodiment, the reflection mechanism 294 is disposed at a position facing the filters F1 and F2 with the ultraviolet light source 291 in between, and the ultraviolet light source 291 is opposite to the filters F1 and F2 side. The ultraviolet rays emitted to the side are reflected by the reflection surface 294a of the reflection mechanism 294 toward the filters F1 and F2.
Therefore, the ultraviolet light emitted from the ultraviolet light source 291 to the side opposite to the filters F1 and F2 is also returned to the filters F1 and F2 by reflection by the reflection mechanism 294, and is used for curing the ultraviolet curable ink. Therefore, the utilization efficiency of ultraviolet rays emitted from the ultraviolet light source 291 is improved.

  Further, as in the present embodiment, the reflecting surface 294a of the reflecting mechanism 294 is a parabolic curved surface having the light emission center of the ultraviolet light source 291 as a focal point, so that the ultraviolet directions that pass through the filters F1 and F2 are aligned. The intensity of ultraviolet rays irradiated to the ink can be made uniform, and the curing performance of the ink by ultraviolet irradiation can be stabilized.

  Furthermore, in the ultraviolet irradiation devices 290A and 290B of the above embodiment, the ultraviolet light source 291 may be at least one selected from a mercury lamp, a metal halide lamp, a xenon lamp, or an excimer lamp, and the degree of freedom in selecting the ultraviolet light source 291 is high. For example, when the wavelength range of ultraviolet rays absorbed by the coloring material (pigment or dye) contained in the UV curable color ink, or when the curing temperature is different, the wavelength range suitable for the physical properties of the ink, By selecting the ultraviolet light source 291 having an exothermic temperature, the ink curing process can be realized more efficiently by the irradiation of ultraviolet rays.

  In addition, regardless of which ultraviolet light source 291 is used, the ultraviolet light UVsl emitted from the ultraviolet light source 291 is separated into the long-wavelength ultraviolet light UVl and the short-wavelength ultraviolet light UVs by the filters F1 and F2. When the ink is irradiated with ultraviolet rays UV1 having a long wavelength first, only the surface of the ultraviolet curable ink adhered on the recording medium is cured even during printing with a relatively thick ink film. The ink can be cured satisfactorily without incurring ink.

The configuration of the ultraviolet irradiation apparatus according to the present invention is not limited to the configuration of the recording head, carriage, ultraviolet light source, and the like in the above-described embodiment, and various forms can be taken based on the spirit of the present invention. Needless to say.
For example, in the above embodiment, the ultraviolet light emitted from the ultraviolet light source 291 is separated into two types of long and short ultraviolet rays using the two types of filters F1 and F2 of the long wavelength filter and the short wavelength filter. Depending on the characteristics, three or more types of filters may be used to separate into three or more types of ultraviolet rays having different wavelengths, and the ink on the printing paper P may be irradiated in order from the longer wavelength.

  In such a case, it is possible to irradiate the ink film 296 ejected on the printing paper P with ultraviolet light whose wavelength is gradually reduced from a long wavelength. Therefore, even if the film thickness of the ink film 296 is large, the ink film 296 can be sequentially cured from the inner side and finally the surface side can be cured, and the entire ink film 296 can be cured reliably.

In the above embodiment, a so-called serial head is used as the print head 52 that ejects the ultraviolet curable ink onto the recording medium. However, the recording head of the present invention is not limited to this.
Hereinafter, an ink jet printer (ink jet recording apparatus) according to a fourth embodiment of the present invention will be described.
The fourth embodiment is the same as the second embodiment described above except that in FIG. 4 described above, the ultraviolet irradiation device 27 is the ultraviolet irradiation device 27 shown in FIG.

  In the present embodiment, the ultraviolet irradiation device 27 (corresponding to the ultraviolet irradiation device 7 in FIG. 4) is attached so as to be positioned on the paper discharge side with respect to the print head 6, as shown in FIGS. . The ultraviolet irradiation device 27 of the present embodiment has a basic configuration substantially the same as that of the ultraviolet irradiation device 290A of the third embodiment, but is configured to be long in the paper width direction, and the ink adhered on the printing paper P. The film 296 can be uniformly cured along the paper width direction.

  That is, the ultraviolet irradiation device 27 supports the ultraviolet light source 291 having a wide wavelength range of emitted ultraviolet light and the ultraviolet light source 291 that is attached to the print head 6 and that is long in the paper width direction from the print head 6 at a predetermined distance. The housing 44, the two filters F1 and F2 for separating the ultraviolet light UVsl having a wide wavelength range emitted from the ultraviolet light source 291 into the ultraviolet light UVl having a long wavelength and the ultraviolet light UVs having a short wavelength, and the ultraviolet light source 291 The configuration includes a reflection mechanism 294 that reflects the ultraviolet light UVsl in a wide wavelength range toward the two filters F1 and F2, and a light source control circuit (not shown) that controls light emission and extinction of the ultraviolet light source 291.

  As shown in FIG. 9, these filters F1 and F2, which are means for separating the ultraviolet rays into a plurality of ultraviolet rays having different wavelengths, are such that the filter F1 as a long wavelength filter is closer to the print head 6 than the filter F2 as a short wavelength filter. The two filters F1 and F2 are spaced apart from the center of the print head 6 along the conveyance direction of the printing paper P (the direction of arrow D in FIG. 9) L21, L22 (where L21 <L22 ) At a plurality of attachment positions S21 and S22.

  According to the ultraviolet irradiation device 27 according to the present embodiment described above, as shown in FIG. 9, the print head 6 is adhered onto the printing paper P which is a recording medium by jetting from the plurality of head modules 10 </ b> A to 10 </ b> D. First, ultraviolet light UVl having a long wavelength separated by the filter F1 is irradiated onto the printing paper P in the vicinity of the printing head 6 to cure the ink film 296, and the inner part of the ink film 296 is cured. Thereafter, while feeding the printing paper P, the ultraviolet rays UVs having a short wavelength separated by the filter F2 are applied to the ink film 296 on the printing paper P away from the vicinity of the print head 6 to cure the surface of the ink film 296. .

  Therefore, even when printing is performed with a high ink viscosity and a relatively thick ink film as in the present embodiment, the ultraviolet irradiation device 27 cures only the surface of the ultraviolet curable ink deposited on the printing paper P. It can be cured well without causing the problem of skinning.

  The equipment equipped with the ultraviolet irradiation device of the present invention is not limited to the ink jet printer shown in the above embodiment. It can be mounted on various devices that apply ultraviolet curable ink. Various materials such as paper, film, cloth, and thin metal plate can be considered as the material of the recording medium irradiated with ultraviolet rays by the ultraviolet irradiation apparatus of the present invention.

  Hereinafter, the present invention will be described in detail with specific examples, but the present invention is not limited to such specific examples.

  The following various ultraviolet curable ink compositions were prepared (the numerical values in Table 1 indicate% by weight).

[Preparation of each ink composition]
(Preparation of pigment dispersion)
As a coloring material, C.I. I. Pigment Black 7 (carbon black) 15% by weight and allyl glycol (manufactured by Nippon Emulsifier Co., Ltd.) as a monomer were added to make 100% by weight, and the mixture was stirred to obtain a mixture. This mixture was subjected to a dispersion treatment for 6 hours together with zirconia beads (diameter 1.5 mm) using a sand mill (manufactured by Yaskawa Seisakusho).
Thereafter, zirconia beads were separated by a separator to obtain a black pigment dispersion.

  In the same manner, a pigment dispersion corresponding to each color, that is, cyan pigment dispersion 4 (CI Pigment Blue 15: 3), magenta pigment dispersion (CI Pigment Violet-19), yellow pigment dispersion A liquid (CI Pigment Yellow 213) was prepared.

  After various additives were mixed and completely dissolved in the composition (% by weight) shown in Table 1, the pigment dispersion (Pigment Black-7, Pigment Blue-15: 3, Pigment Violet-19, Pigment Yellow- 213) was added dropwise with stirring (see Table 1 for the amount added). After completion of the dropwise addition, the mixture was stirred at room temperature for 1 hour and further filtered through a 5 μm membrane filter to obtain each ink composition.

In addition, the additive used in the table | surface is as follows.
Allyl glycol (monomer: manufactured by Nippon Emulsifier Co., Ltd.)
U-15HA
(Urethane oligomer: Shin-Nakamura Chemical Co., Ltd.)
Irgacure 819
(Photopolymerization initiator: Ciba Specialty Chemicals)
Irgacure 127
(Photopolymerization initiator: Ciba Specialty Chemicals)
BYK-UV3570
(Surfactant: manufactured by Big Chemie Japan Co., Ltd.)
Irgastab UV10
(Thermal radical polymerization inhibitor: Ciba Specialty Chemicals)

  The above UV curable ink is filled into each nozzle row using an ink jet printer PX-G5000 manufactured by Seiko Epson Corporation, and the printed dot size of the ink dot is large on the PET film at room temperature and normal pressure. A monochromatic character pattern having a thickness of 20 μm was printed for each ink. Moreover, the printed material was subjected to a curing treatment under the following irradiation conditions. The UV LEDs in the ultraviolet irradiation device mounted on the side of the carriage were arranged as follows.

<Irradiation conditions>
(Condition 1)
An ultraviolet ray with a wavelength of 395 nm is arranged near the recording head, and an ultraviolet ray with a wavelength of 365 nm is arranged outside the recording head so that the irradiation intensity is 60 mW / cm ² .
(Condition 2)
An ultraviolet ray having a wavelength of 365 nm is arranged in the vicinity of the recording head, and an ultraviolet ray having a wavelength of 395 nm is arranged outside the recording head so that the irradiation intensity is 60 mW / cm ² .

<Curing state evaluation>
The index of the cured state is as follows.
A: Completely cured B: Skinning occurs and the interior is uncured

In both Experimental Example 1 and Experimental Example 2, all four ink compositions shown in Table 1 were in this state, and there was no difference in curability between colors.
According to the present invention, even in monocolor printing where the viscosity of the ink is high and the film thickness of the ink film is relatively large, skinning occurs and the inside is not uncured and can be completely cured. .

1 is a perspective view of an ink jet recording apparatus equipped with an ultraviolet irradiation device according to a first embodiment and a third embodiment of the present invention. It is an ultraviolet irradiation device shown in Drawing 1, and is a front view of an ultraviolet irradiation device concerning a 1st embodiment of the present invention. It is an AA arrow line view of FIG. FIG. 6 is a perspective view of an ink jet recording apparatus equipped with an ultraviolet irradiation device according to a second embodiment and a fourth embodiment of the present invention. FIG. 5 is a plan view of the ultraviolet irradiation device and the recording head shown in FIG. 4 and the ultraviolet irradiation device and the recording head according to a second embodiment of the present invention. It is an ultraviolet irradiation device shown in Drawing 5, and is a front view of an ultraviolet irradiation device concerning a 2nd embodiment of the present invention. FIG. 4 is a schematic cross-sectional view of the ultraviolet irradiation apparatus and the recording head shown in FIG. 1 and the ultraviolet irradiation apparatus and the recording head according to a third embodiment of the present invention. It is an ultraviolet irradiation device and a recording head shown in Drawing 4, Comprising: It is a top view of an ultraviolet irradiation device and a recording head concerning a 4th embodiment of the present invention. It is an ultraviolet irradiation device shown in Drawing 4, and is a front view of the ultraviolet irradiation device concerning a 4th embodiment of the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 20 ... Inkjet printer (inkjet recording device), 30 ... Paper feed motor, 40 ... Platen, 50 ... Carriage, 52 ... Print head (recording head), 54 ... Black cartridge, 56 ... Color ink cartridge, 60 ... Carriage motor, 62 ... traction belt, 64 ... guide rail, 80 ... capping device, 90A (190A, 290A), 90B (190B, 290B) ... ultraviolet irradiation device, 192, 193, 291 ... ultraviolet light source, 194, 293 ... housing, 196 296 ... ink film (ink), P ... printing paper (recording medium), 294 ... reflection mechanism, F1 ... filter, F2 ... filter

Claims (13)

An ultraviolet irradiation device including an ultraviolet light source that irradiates ultraviolet rays to an ultraviolet curable ink jetted onto a recording medium by a recording head,
The ultraviolet light of the ultraviolet light source that irradiates the recording medium in the vicinity of the recording head has a longer wavelength than the ultraviolet light of the ultraviolet light source that irradiates the recording medium away from the vicinity of the recording head. Irradiation device.   The ultraviolet irradiation device is an ultraviolet irradiation device including a plurality of ultraviolet light sources, wherein the plurality of ultraviolet light sources are arranged in the vicinity of the recording head, and the recording head is longer than the long wavelength light source. The ultraviolet irradiation device according to claim 1, further comprising: a light source for short wavelength disposed away from the light source.   3. The ultraviolet irradiation apparatus according to claim 1, wherein the plurality of ultraviolet light sources irradiate the recording medium with ultraviolet rays whose wavelengths are sequentially shortened as the distance from the vicinity of the recording head is increased.   2. The ultraviolet irradiation device according to claim 1, wherein the ultraviolet irradiation device comprises means for separating the ultraviolet rays emitted from the ultraviolet light source into a plurality of ultraviolet rays having different wavelengths.   The ultraviolet irradiation apparatus according to claim 4, wherein the means is a filter that preferentially transmits a specific wavelength.   The ultraviolet irradiation device according to claim 5, wherein a reflection mechanism is disposed at a position facing the filter, and reflects ultraviolet rays emitted from the ultraviolet light source toward the filter.   7. The ultraviolet irradiation apparatus according to claim 4, wherein the means separates the ultraviolet rays so that the wavelength to be transmitted becomes shorter as the distance from the vicinity of the recording head increases. The recording head is a line-type head provided across the width direction of the recording medium;
The ultraviolet light of the ultraviolet light source that irradiates the recording medium in the vicinity of the recording head is more than the ultraviolet light of the ultraviolet light source that irradiates the recording medium away from the vicinity of the recording head along the feeding direction of the recording medium. The ultraviolet irradiation device according to claim 1, wherein the wavelength is long. The recording head is a head mounted on a carriage;
The ultraviolet light of the ultraviolet light source that irradiates the recording medium in the vicinity of the recording head has a wavelength greater than the ultraviolet light of the ultraviolet light source that irradiates the recording medium that is separated from the vicinity of the recording head along the moving direction of the carriage. The ultraviolet irradiation device according to claim 1, wherein the ultraviolet irradiation device is long.   The ultraviolet irradiation device according to claim 9, wherein the ultraviolet irradiation device is provided at both side ends along the moving direction of the carriage.   11. The ultraviolet irradiation device according to claim 1, wherein the ultraviolet light source is at least one selected from an LED, an LD, a mercury lamp lamp, a metal halide lamp, a xenon lamp, or an excimer lamp.   A recording apparatus comprising the ultraviolet irradiation device according to claim 1. A recording method for monocolor printing on a recording medium using ultraviolet curable ink,
When the ultraviolet curable ink ejected from the recording head onto the recording medium is cured, the ultraviolet rays of the ultraviolet light source that irradiates the recording medium near the recording head are separated from the vicinity of the recording head. A recording method, wherein the ultraviolet curable ink is cured by irradiating an ultraviolet ray having a wavelength longer than that of the ultraviolet light source that irradiates the ultraviolet ray.

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