JP2006142613A - Inkjet recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To certainly heat an uncured ink impacting on a recording medium. <P>SOLUTION: This inkjet recording device 1 comprises recording heads 3a to 3d, each having a discharging surface 30, on which at least, a single array 31 of nozzles for discharging an ultraviolet-curable ink to the recording medium K, is installed, at least, a single flashlight source 51 which irradiates the ink impacting on the surface of the recording medium K with a flash light, and a control device 6 which controls the flashlight source 51. The control device 6 controls the flashlight source 51 in the way that the ink discharged from a plurality of the nozzles 32 of each nozzle array 31, is irradiated with the flash light at least once. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an inkjet recording apparatus that records an image on a recording medium.

  Conventionally, as an apparatus for recording an image even on a recording medium having poor ink absorbability, a photo-curing inkjet recording apparatus has been used. A photo-curing ink jet recording apparatus is a photo-curing ink jet recording apparatus in which a photo-curable ink is ejected from a recording head and landed on the surface of a recording medium, and then light is irradiated from an always-on light source that is constantly lit to the surface of the recording medium. The ink is fixed (see, for example, Patent Documents 1 and 2).

  Here, as the photocurable ink, a radical polymerization type ink and a cationic polymerization type ink are known. Among these inks, the cationic polymerization type ink has the advantage of being cured with light having a lower illuminance than the radical polymerization type ink by accumulating the energy of the irradiated light. Application is under consideration.

By the way, the above-mentioned cationic polymerization type ink has a property of being cured by light with lower illuminance when heated. For this reason, in an ink jet recording apparatus using this ink, from the viewpoint of reducing the load of the ordinary light source, a flash light source for irradiating the flash is disposed between the recording head and the ordinary light source to flush the ink on the recording medium. It is conceivable that the material is heated by irradiation with a light source and then cured by irradiation with an ordinary light source.
JP 2001-310454 A JP 2004-106525 A

  However, when the ink is heated by a flash light source, if the flash does not hit the ink, the ink is not sufficiently heated, and there is a possibility that the ink is not completely cured even by irradiation from an ordinary light source.

  An object of the present invention is to provide an ink jet recording apparatus capable of reliably heating uncured ink landed on a recording medium.

The invention according to claim 1 is an inkjet recording apparatus,
A recording head having an ejection surface provided with at least one nozzle row for ejecting photocurable ink toward the recording medium;
At least one flash light source for irradiating the ink landed on the surface of the recording medium with a flash;
A control device for controlling the flash light source,
The control device controls the flash light source to irradiate a flash at least once with respect to the ink ejected from the nozzles in each nozzle row.

  According to the first aspect of the present invention, since the flash light source irradiates the ink at least once with respect to the ink ejected from the nozzles in each nozzle row, the flash is not irradiated to the uncured ink on the recording medium. The case disappears. Therefore, the uncured ink on the recording medium can be reliably heated.

The invention described in claim 2 is the ink jet recording apparatus according to claim 1,
A moving device that relatively moves the recording head, the flash light source, and a recording medium in a predetermined direction intersecting the nozzle row during image recording;
The control device lights the flash light source at a lighting frequency f satisfying the following expression (1).
f ≧ (1-α) · v ₁ / L ₁ (1)
(However,
α: ratio of effective irradiation time to lighting cycle (1 / f) (0 ≦ α ≦ 1),
v ₁ : relative moving speed of the recording head and the flash light source and the recording medium by the moving device,
L ₁ : irradiation width of the flash light source on the recording medium in the predetermined direction)

Here, the effective irradiation time is a time during which light having an illuminance equal to or higher than the heating lower limit illuminance of the ink is irradiated in the lighting time of the flash light source in one lighting cycle.
A time t ₁ from when a certain point on the recording medium enters the irradiation width of the flash light source until it exits the irradiation width is represented by L ₁ / v ₁ , and is an ineffective irradiation time within one lighting cycle, That is, the time t _{2 when the} illuminance is less than the heating lower limit illuminance is represented by (1-α) / f.

According to the second aspect of the invention, the operating frequency f of the flash light source satisfies the above equation (1), that is since the time t _1, t ₂ satisfy t ₁ ≧ t _2, the non-effective irradiation time t in ₂ In addition, the uncured ink that has entered the irradiation width of the flash light source does not come out of the irradiation width without receiving light having an illuminance higher than the heating lower limit illuminance. In other words, within a time t ₁ from when the uncured ink on the recording medium enters the irradiation width of the flash light source to when it exits the irradiation width, light with an illuminance equal to or higher than the heating lower limit illuminance is applied to the uncured ink once. Irradiated as described above. Therefore, the uncured ink on the recording medium can be heated more reliably.

The invention described in claim 3 is the ink jet recording apparatus according to claim 1 or 2,
A moving device that relatively moves the recording head, the flash light source, and a recording medium in a predetermined direction intersecting the nozzle row during image recording;
The controller is
The flash light source is turned on after a time T that satisfies the following expression (2) after the recording head ejects ink.
_{T ≦ (L 2 + L 1} /2) / v 1 + h / v 2 ... (2)
(However,
L ₁ : irradiation width of the flash light source on the recording medium in the predetermined direction,
L ₂ : distance between an irradiation area of the recording medium by the flash light source and a landable area of ink ejected from the nozzles in the nozzle row closest to the flash light source,
v ₁ : relative moving speed of the recording head and the flash light source and the recording medium by the moving device,
h: distance between the ejection surface and the recording medium,
v ₂ : average speed of ink ejected from the recording head)

Here, the time t ₃ from when the ink is ejected from the recording head to when the ink hits the recording medium is represented by t ₃ = h / v ₂ . The time t ₄ from when the ink ejected from the nozzle in the nozzle row closest to the flash light source lands on the recording medium until it is positioned on the center line of the irradiation area by the flash light source is t ₄ = ( represented by _{L 2 + L 1/2)} / v 1. Therefore, the time t ₅ from when the ink is ejected from the nozzle in the nozzle row closest to the flash light source to when the ink is positioned on the center line of the irradiation area of the flash light source is expressed by the following equation (3): It is represented by
t ₅ = t ₃ + t _{4
= H / v 2 + (L} 2 + L 1/2) / v 1 ... (3)

According to the third aspect of the present invention, the flash light source is turned on after time T after the recording head ejects ink, and this time T satisfies T ≦ t _5. The flash is irradiated before the uncured ink ejected from the nozzle in the center is positioned on the center line of the irradiation area by the flash light source. Accordingly, the uncured ink is reliably irradiated with flash once or more. In addition, the ink is reliably irradiated at least once with respect to the ink ejected in the same cycle from the nozzles in the nozzle row farther from the flash light source than the nozzle row. Therefore, the uncured ink on the recording medium can be heated more reliably.
Further, since the flash light source is not turned on until the time T elapses from the ejection of ink, the power consumption can be reduced accordingly.

According to a fourth aspect of the present invention, in the ink jet recording apparatus according to the third aspect,
A plurality of the recording heads;
The controller is
As the distance L ₂ in the formula (2),
A distance between an irradiation area of the recording medium by the flash light source and a landable area of ink ejected from a nozzle in the nozzle array closest to the flash light source among the nozzle arrays of the plurality of recording heads. It is characterized by using.

  According to the fourth aspect of the invention, even when a plurality of recording heads are provided, the same effect as that of the third aspect of the invention can be obtained.

Invention of Claim 5 is an inkjet recording device as described in any one of Claims 1-4,
It comprises an ordinary light source that irradiates light onto ink landed on the surface of a recording medium by continuously turning on during image recording.

  According to the fifth aspect of the invention, since the ordinary light source is provided, the ink heated by the flash light source can be reliably cured by the ordinary light source.

Invention of Claim 6 is an inkjet recording device as described in any one of Claims 1-5,
The recording head ejects ink containing an infrared absorbing material,
The flash light source irradiates a flash having a wavelength of at least an infrared region.

  According to the invention described in claim 6, the same effect as that of the invention described in any one of claims 1 to 5 can be obtained.

The invention according to claim 7 is the ink jet recording apparatus according to any one of claims 1 to 6,
The flash light source is a xenon light source.

  According to the invention of the seventh aspect, the same effect as that of the invention according to any one of the first to sixth aspects can be obtained.

Invention of Claim 8 is an inkjet recording device as described in any one of Claims 1-7,
The recording head discharges cationic polymerization ink.

  According to the invention described in claim 8, it is possible to obtain the same effect as the invention described in any one of claims 1-7.

According to invention of Claims 1-3, uncured ink can be heated reliably.
According to the fourth aspect of the invention, even when a plurality of recording heads are provided, the same effect as that of the third aspect of the invention can be obtained.

  According to the fifth aspect of the present invention, it is possible to obtain the same effect as that of any one of the first to fourth aspects. Can be reliably cured.

  According to the invention described in claims 6 to 8, the same effect as that of the invention described in any one of claims 1 to 5 can be obtained.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a plan view showing a schematic configuration of an ink jet recording apparatus 1 according to the present invention.
As shown in this figure, the ink jet recording apparatus 1 includes a platen 11 between rotatable rollers 10 and 10.

The rollers 10 and 10 are configured to transport the recording medium K in the transport direction X by intermittently rotating by driving of the transport motor 10a (see FIG. 4).
The upper surface of the platen 11 is substantially flat, and supports the recording medium K conveyed between the rollers 10 and 10 from the back surface side.

Above the platen 11, a guide member 12 extending along a scanning direction Y as a predetermined direction in the present invention is disposed. In the present embodiment, the scanning direction Y is substantially orthogonal to the transport direction X.
A carriage 2 as a moving device in the present invention is supported on the guide member 12, and a driving device 2a (see FIG. 4) is connected to the carriage 2.

  The carriage 2 can be reciprocated in the scanning direction Y on the recording medium K by driving of the driving device 2 a, and this movement is guided by the guide member 12. Four recording heads 3 a to 3 d are mounted on the carriage 2 along the scanning direction Y.

  As shown in FIG. 2, the recording heads 3 a to 3 d are provided with a photocurable ink, which is an ultraviolet curable ink in the present embodiment, from a plurality of nozzles 32,. To be discharged. The nozzles 32,... Are configured to individually eject ink as droplets by the operation of a piezo element or a heating element, for example, and are arranged in the transport direction X to form a nozzle row 31.

  In this embodiment, the recording head 3a ejects black (K), the recording head 3b cyan (C), the recording head 3c ejects magenta (M), and the recording head 3d ejects yellow (Y) ink. It has become. Each of the recording heads 3a to 3d is supplied with ink of a corresponding color from an ink tank (not shown). In FIG. 2, the carriage 2 and a main irradiation device 4 described later are not shown.

As shown in FIG. 1, main irradiation devices 4 and 4 are arranged on both sides of the recording heads 3 a to 3 d in the scanning direction Y, and move in the scanning direction Y together with the carriage 2.
The main irradiation device 4 includes an ordinary light source (not shown) inside a concave cover member (not shown) that opens downward.

  The ordinary light source is always turned on during image recording, and in the present embodiment, ultraviolet light is irradiated radially. As this ordinary light source, for example, a high pressure mercury lamp, a low pressure mercury lamp, a metal halide lamp, black light, a hot cathode tube, a cold cathode tube, an LED (Light Emitting Diode), an electrodeless lamp, an excimer lamp, or the like can be used.

A sub-irradiation device 5 is disposed between the recording heads 3 a to 3 d and the main irradiation devices 4 and 4.
As shown in FIG. 2, the sub-irradiation device 5 includes a flash light source 51 inside a concave cover member 50 opened downward.

  The flash light source 51 emits a flash having a wavelength of at least the infrared region during image recording. In the present embodiment, a xenon light source is used as the flash light source 51, and this xenon light source has a spectral distribution as shown in FIG. 3 and ultraviolet (100 to 400 nm wavelength region) and infrared (700 to 1000 nm wavelength). )) Flash.

  As shown in FIG. 4, a control device 6 is connected to the transport motor 10a, the drive device 2a, the recording heads 3a to 3d, the main irradiation device 4, and the sub irradiation device 5.

  The control device 6 includes a ROM (Read Only Memory) 6a, a RAM (Random Access Memory) 6b, and a CPU (Central Processing Unit) 6c. The ROM 6a stores various control programs relating to operations of the transport motor 10a, the driving device 2a, the recording heads 3a to 3d, the main irradiation device 4, and the sub irradiation device 5. The RAM 6b is provided with a work area for the CPU 6c. The CPU 6c develops a program designated from various programs stored in the ROM 6a in a work area in the RAM 6b and executes it.

  The control device 6 controls the transport motor 10a, the drive device 2a, the recording heads 3a to 3d, the main irradiation device 4, and the sub irradiation device 5 by the operation of the CPU 6c.

  Specifically, the control device 6 is configured to intermittently convey the recording medium K by controlling the conveyance motor 10a. Further, the control device 6 controls the drive device 2a to move the carriage 2 in the scanning direction Y together with the recording heads 3a to 3d, the sub irradiation devices 5 and 5, and the main irradiation devices 4 and 4. . The control device 6 controls the recording heads 3a to 3d to eject ink toward the recording medium K. The control device 6 controls the main irradiation device 4 to irradiate the recording medium K with ultraviolet rays.

Further, the control device 6 controls the sub-irradiation device 5 so that the ink ejected from the nozzles 32 in each nozzle row 31 is irradiated with a flash at least once. Specifically, as shown in the upper graph of FIG. 5, the flash light source 51 is turned on at a lighting frequency f that satisfies the following expression (1).
f ≧ (1-α) · v ₁ / L ₁ (1)

However, as shown in FIG. 2 or FIG. 5, in the formula (1), α is a ratio (0 ≦ α ≦ 1) of the effective irradiation time to the lighting cycle (1 / f). Further, v ₁ is the relative moving speed of the recording heads 3a to 3d, the main irradiating devices 4 and 4, the sub-irradiating devices 5 and 5, and the recording medium K, and is the moving speed of the carriage 2 in this embodiment. L ₁ is the irradiation width of the flash light source 51 on the recording medium K in the scanning direction Y. The effective irradiation time is a time during which light having an illuminance equal to or higher than the heating lower limit illuminance of the ink is irradiated in the lighting time of the flash light source 51 in one lighting cycle. Further, in the present embodiment, the irradiation width of the flash light source 51 is the width of a region where light having an illuminance of 50% hits the illuminance at the center line C of the irradiation region of the flash light source.

Here, as shown in the upper and lower graphs of FIG. 5, a time t ₁ (= L ₁ / v ₁ ) at which a certain point on the recording medium K passes the irradiation width of the flash light source 51 and one lighting. Using the ineffective irradiation time in the cycle, that is, the time t ₂ (= (1−α) / f) in which the illuminance is less than the heating lower limit illuminance, the above equation (1) becomes t ₁ ≧ t ₂ . It is synonymous. Further, the upper part of FIG. 5, as shown in the middle graph, the first width of the recording medium K which light effective irradiance strikes the irradiation of the lighting period _{L a (= L 1 + αv} 1 / f), 1 lighting cycle ( When the movement distance L _b (= v ₁ / f) of the carriage 2 within ₁ / f) is used, the above equation (1) is synonymous with L _a ≧ L _b .

Further, the control device 6 controls the sub-irradiation device 5 so that the flash is irradiated after a time T satisfying the following expression (2) after the recording heads 3a to 3d eject ink. .
_{T ≦ (L 2 + L 1} /2) / v 1 + h / v 2 ... (2)

However, as shown in FIG. 2, in the formula (2), L ₂ is relative to the flash light source 51 among the irradiation region of the recording medium K by the flash light source 51 and the nozzle rows 31 of the recording heads 3a to 3d. This is the distance from the landable area of the ink ejected from the nozzle 32 in the nearest nozzle row 31. Further, h is the distance between the ejection surface 30 of the recording head 3 a to 3 d and the recording medium K, v ₂ is the average velocity of ink ejected from the recording head 3 a to 3 d.

Here, the time t ₃ (= h / v ₂ ) from the time when ink is ejected from the recording heads _{3 a to 3} d until the ink reaches the recording medium K, and the nozzles in the nozzle row 31 closest to the flash light source 51. 32, until the ink ejected from ... is located on the center line C of the irradiation region by the flash light source 51 after landing on the recording medium K time _{t 4 (= (L 2 +} L 1/2) / v 1) When ink is ejected from the nozzles 32 in the nozzle row 31 closest to the flash light source 51, the ink is positioned on the center line C of the irradiation area of the flash light source 51. The time t ₅ is expressed by the following equation (3).

t ₅ = t ₃ + t _{4
= H / v 2 + (L} 2 + L 1/2) / v 1 ... (3)
Therefore, the above equation (2) is synonymous with T ≦ t ₅ .

Here, the ink used in this embodiment will be described.
As the ink used in the present embodiment, in particular, “photocuring technology (selection of resin / initiator and blending conditions and measurement / evaluation of curing degree (technical association information)” described in “photocuring system (No. 4)) “Curing system using photoacid / base generator (Section 1)”, “Photo-induced alternating copolymerization (Section 2)”, etc. are applicable. It may be cured by radical polymerization.

  Specifically, the ink used in the present embodiment is an ultraviolet curable ink having a property of being cured by irradiation with ultraviolet rays as light, and has at least a polymerizable compound (a known polymerizable compound as a main component). ), A photoinitiator, and a coloring material (dye or pigment). However, as the ink used in the present embodiment, the photoinitiator may be excluded when an ink that conforms to the above-mentioned “light-induced alternating copolymerization (section 2)” is used.

  The ultraviolet curable ink is roughly classified into a radical curable ink containing a radical polymerizable compound and a cation curable ink containing a cationic polymerizable compound as a polymerizable compound. It can be applied as an ink to be used, and a hybrid ink in which a radical curable ink and a cationic curable ink are combined may be applied as an ink used in this embodiment.

  However, since a cationic curable ink that has little or no inhibition of polymerization reaction by oxygen is superior in functionality and versatility, a cationic curable ink is particularly used in the present embodiment. The cation curable ink used in the present embodiment is specifically a mixture containing at least a cation polymerizable compound such as an oxetane compound, an epoxy compound, and a vinyl ether compound, a photo cation initiator, and a coloring material. As described above, it has a property of being cured by irradiation with ultraviolet rays.

  Furthermore, the ink used in the present embodiment preferably contains a compound that absorbs infrared rays and generates heat. In the present invention, the compound that absorbs infrared rays and generates heat (infrared absorbing agent) is a dye or pigment that effectively absorbs near infrared rays, and preferably a dye or pigment that effectively absorbs infrared rays having a wavelength of 760 nm to 1500 nm. It is a pigment, more preferably a dye or pigment that effectively absorbs infrared rays of 760 nm to 1200 nm. These infrared absorbers preferably have an absorption maximum in the near infrared region, more preferably have an absorption maximum from a wavelength of 760 nm to 1500 nm, and still more preferably have an absorption maximum from a wavelength of 760 nm to 1200 nm.

  In addition, these infrared absorbers have substantially the required transparency and color reproducibility in the visible light region in applications where transparency in the visible light region and color reproducibility are required. It is preferable to add within the range which does not affect. In actual use of the ink containing the polymerizable composition of the present invention, an infrared absorber is added to the ink of the present invention after examining various performance evaluations necessary for exhibiting the performance desired by the user. The amount can be determined. In particular, in applications that require color reproducibility such as ink, it is preferable to add in a range that does not substantially affect the color reproduction. Specifically, it is preferably 0.0001 to 10% by weight, preferably 0.0001 to 5% by weight, more preferably 0.001 to 1% by weight, based on the total weight of the ink.

  Here, as dyes, commercially available dyes and known dyes described in documents such as “Dye Handbook” (edited by the Society for Synthetic Organic Chemistry, published in 1970), etc. have maximum absorption in the near infrared region. Is available. Specifically, azo dyes, metal complex azo dyes, pyrazolone azo dyes, naphthoquinone dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinoneimine dyes, methine dyes, cyanine dyes (including merocyanine dyes), squarylium dyes, pyrylium salts, metals Among dyes such as thiolate complexes, those having maximum absorption in the near infrared region can be mentioned. Among these, phthalocyanine dyes, quinoneimine dyes, cyanine dyes (including merocyanine dyes), and squarylium dyes are particularly preferred, which have maximum absorption in the near infrared region.

  On the other hand, as pigments used in the present invention, commercially available pigments and color index (CI) manual, “Latest Pigment Handbook” (edited by Japan Pigment Technical Association, published in 1977), “Latest Pigment Application Technology” (CMC) (Published, published in 1986) and “printing ink technology”, published by CMC (published in 1984), pigments having maximum absorption in the near infrared region can be used. Examples of the pigment include black pigments, yellow pigments, orange pigments, brown pigments, red pigments, purple pigments, blue pigments, green pigments, fluorescent pigments, metal powder pigments, and other polymer-bonded dyes. Specifically, insoluble azo pigments, azo lake pigments, condensed azo pigments, chelate azo pigments, phthalocyanine pigments, anthraquinone pigments, perylene and perinone pigments, thioindigo pigments, quinacridone pigments, dioxazine pigments, isoindolinone pigments , Quinophthalone pigments, dyed lake pigments, azine pigments, nitroso pigments, nitro pigments, natural pigments, fluorescent pigments, inorganic tin oxides, indium compounds, inorganic pigments, pigments with maximum absorption in the near infrared region can be used .

Next, the “recording medium K” used in the present embodiment will be described.
The recording medium K used in the present embodiment is made of various papers such as plain paper, recycled paper, glossy paper, etc., various fabrics, various non-woven fabrics, resin, metal, glass and the like applied to a normal ink jet recording apparatus. A recording medium is applicable. As the form of the recording medium K, a roll shape, a cut sheet shape, a plate shape, or the like is applicable. In this embodiment, as the recording medium K, a long resin film wound in a roll shape is used.

  In particular, as the recording medium K used in the present embodiment, a transparent or opaque non-absorbent resin film used for so-called soft packaging can be applied. Specific resin types of resin film include polyethylene terephthalate, polyester, polyolefin, polyamide, polyesteramide, polyether, polyimide, polyamideimide, polystyrene, polycarbonate, poly-ρ-phenylene sulfide, polyether ester, polyvinyl chloride , Poly (meth) acrylic acid ester, polyethylene, polypropylene, nylon and the like are applicable, and further, copolymers of these resins, mixtures of these resins, and those obtained by crosslinking these resins are also applicable. Above all, as the type of resin of the resin film, one of stretched polyethylene terephthalate, polystyrene, polypropylene, and nylon is selected because of the transparency, dimensional stability, rigidity, environmental load, cost, etc. of the resin film. It is preferable to use a resin film having a thickness of 2 to 100 μm (preferably 6 to 50 μm). Moreover, you may perform surface treatments, such as a corona discharge process and an easily bonding process, on the surface of the support body of resin films.

  Further, as the recording medium K used in the present embodiment, known opaque recording media such as various papers whose surfaces are coated with a resin, a film containing a pigment, and a foamed film are also applicable.

Next, the operation of the inkjet recording apparatus 1 during image recording will be described.
First, the carriage 2 scans immediately above the recording medium K to one side in the scanning direction Y in a state where the conveyance of the recording medium K by the rollers 10 is stopped. As a result, the recording heads 3a to 3d, the sub-irradiating devices 5 and 5, and the main irradiating devices 4 and 4 scan following the carriage 2 and record an image during this scanning.

Specifically, first, each of the recording heads 3a to 3d ejects ink from the nozzles 32,.
Next, the sub-irradiation device 5 on the rear side of the recording heads 3a to 3d, that is, on the other side, flashes the uncured ink ejected from the nozzles 32 in each nozzle row 31 and landed on the recording medium K. Irradiation heats the uncured ink and renders it curable.

Here, the lighting frequency f of the flash light source 51 satisfies the above equation (1), that is, the times t ₁ and t ₂ satisfy t ₁ ≧ t ₂ . Therefore, as shown in the lower graph of FIG. 5, the uncured ink that has entered the irradiation width of the flash light source 51 within the ineffective irradiation time t ₂ does not receive light having an illuminance exceeding the heating lower limit illuminance. In other words, in the time t ₁ when the uncured ink on the recording medium K passes through the irradiation width of the flash light source 51, the light having an illuminance equal to or higher than the heating lower limit illuminance is 1 for the uncured ink. Irradiated more than once.
This is a result of operating frequency f satisfies the equation (1), as shown in the middle graph of Figure 5, the width L _a and the moving distance L _b satisfies L _a ≧ L _b, each lighting period It can also be seen from the fact that at least one point overlaps the area where light of effective illuminance hits by irradiation.

At this time, the time T from the recording head 3a~3d are ejecting ink until irradiating flash satisfies the above (2), that is, the time T, t ₅ satisfies T ≦ t _5. Therefore, the flash is irradiated before the uncured ink ejected from the nozzles 32 in the nozzle row 31 closest to the flash light source 51 is positioned on the center line C of the irradiation region by the flash light source 51. The number of flash irradiations with respect to the uncured ink is surely one or more. In addition, the number of times of flash irradiation with respect to the ink ejected in the same cycle from the nozzles 32 in the nozzle row 31 that is further away from the flash light source 51 than the nozzle row 31 is reliably one or more.

  Next, the normal light source of the main irradiation device 4 behind the recording heads 3a to 3d irradiates the ink on the surface of the recording medium K with ultraviolet rays. Thereby, the uncured ink on the recording medium K is cured by the ultraviolet rays and fixed on the surface of the recording medium K.

When the scanning of the carriage 2 is completed, the rollers 10 and 10 convey the recording medium K along the conveyance direction X.
Next, in a state in which the conveyance of the recording medium K by the rollers 10 and 10 is stopped, the carriage 2 scans the recording medium K immediately above the recording medium K in the scanning direction, and during this scanning, the recording heads 3a to 3d sub-irradiation devices 5, 5 and main irradiation devices 4 and 4 record images.
Next, the rollers 10 and 10 convey the recording medium K along the conveyance direction X.

  Thereafter, the inkjet recording apparatus 1 repeats the above operations, and a desired image composed of a plurality of dots of each process color is sequentially recorded on the surface of the recording medium K.

  According to the inkjet recording apparatus 1 described above, there is no case where the flash that is higher than the heating lower limit illuminance is not irradiated to the uncured ink on the recording medium K, and the uncured ink is reliably heated with the flash that is higher than the lower heating illuminance. be able to. Therefore, even if the light from the main irradiation devices 4 and 4 has a low illuminance, the uncured ink on the recording medium K can be reliably cured.

  Further, since the flash light source 51 is not turned on until the time T elapses after ink ejection, the power consumption can be reduced accordingly.

In the above embodiment, the inkjet recording apparatus 1 has been described as a serial head type apparatus, but may be a line head type apparatus. In this case, a transport device for the recording medium K is used as the moving device in the present invention. Further, the predetermined direction in the present invention is the transport direction X, and the relative moving speed v ₁ between the recording heads 3a to 3d, the main irradiating devices 4 and 4, the sub-irradiating devices 5 and 5, and the recording medium K is the transport of the recording medium K. It becomes speed.

  In addition, the inkjet recording apparatus 1 has been described as including the normal light source of the main irradiation device 4 and the flash light source 51 of the sub-irradiation device 5 as light sources. However, the irradiation energy necessary for ink curing is obtained only by the flash light source 51. If it is possible, the normal light source may not be provided.

  Further, although the flash light source 51 has been described as being a xenon light source, it may be a light source such as an LED.

  Moreover, although ultraviolet curable ink was used as ink, you may use what hardens | cures by irradiation of light other than an ultraviolet-ray. Here, “light” is light in a broad sense and includes electromagnetic waves such as ultraviolet rays, X-rays, and visible rays. In the case of using a photocurable ink that is cured by light other than ultraviolet rays, the normal light source of the main irradiation device 4 that emits light that can cure the ink is applied.

1 is a plan view showing a schematic configuration of an ink jet recording apparatus according to the present invention. It is a figure for demonstrating operation | movement of a recording head and a sub irradiation apparatus. It is a figure which shows the spectrum distribution of a flash light source. 1 is a block diagram showing a schematic configuration of an ink jet recording apparatus according to the present invention. The upper graph shows the illuminance change of the flash light source, the middle graph shows the position of the sub-irradiation device in the scanning direction, and the lower graph shows the uncured ink on the recording medium and the center line of the irradiation area It is a figure which shows the distance.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inkjet recording device 2a Moving device 3a-3d Recording head 6 Control apparatus 30 Ejection surface 31 Nozzle row 32 Nozzle 51 Flash light source K Recording medium Y Scanning direction (predetermined direction)

Claims (8)

A recording head having an ejection surface provided with at least one nozzle row for ejecting photocurable ink toward the recording medium;
At least one flash light source for irradiating the ink landed on the surface of the recording medium with a flash;
A control device for controlling the flash light source,
The control apparatus controls the flash light source to irradiate a flash at least once with respect to ink ejected from nozzles in each nozzle row. The inkjet recording apparatus according to claim 1, wherein
A moving device that relatively moves the recording head, the flash light source, and a recording medium in a predetermined direction intersecting the nozzle row during image recording;
The said control apparatus makes the said flash light source light with the lighting frequency f which satisfy | fills the following (1) Formula, The inkjet recording device characterized by the above-mentioned.
f ≧ (1-α) · v ₁ / L ₁ (1)
(However,
α: ratio of effective irradiation time to lighting cycle (1 / f) (0 ≦ α ≦ 1),
v ₁ : relative moving speed of the recording head and the flash light source and the recording medium by the moving device,
L ₁ : irradiation width of the flash light source on the recording medium in the predetermined direction) The inkjet recording apparatus according to claim 1 or 2,
A moving device that relatively moves the recording head, the flash light source, and a recording medium in a predetermined direction intersecting the nozzle row during image recording;
The controller is
An ink jet recording apparatus, wherein the flash light source is turned on after a time T satisfying the following expression (2) after the recording head ejects ink.
_{T ≦ (L 2 + L 1} /2) / v 1 + h / v 2 ... (2)
(However,
L ₁ : irradiation width of the flash light source on the recording medium in the predetermined direction,
L ₂ : distance between an irradiation area of the recording medium by the flash light source and a landable area of ink ejected from the nozzles in the nozzle row closest to the flash light source,
v ₁ : relative moving speed of the recording head and the flash light source and the recording medium by the moving device,
h: distance between the ejection surface and the recording medium,
v ₂ : average speed of ink ejected from the recording head) The inkjet recording apparatus according to claim 3.
A plurality of the recording heads;
The controller is
As the distance L ₂ in the formula (2),
A distance between an irradiation area of the recording medium by the flash light source and a landable area of ink ejected from a nozzle in the nozzle array closest to the flash light source among the nozzle arrays of the plurality of recording heads. An ink jet recording apparatus using the ink jet recording apparatus. In the ink jet recording apparatus according to any one of claims 1 to 4,
An ink jet recording apparatus comprising an ordinary light source that irradiates light to ink landed on a surface of a recording medium by being continuously turned on during image recording. In the ink jet recording apparatus according to any one of claims 1 to 5,
The recording head ejects ink containing an infrared absorbing material,
The ink jet recording apparatus, wherein the flash light source emits a flash having a wavelength of at least an infrared region. In the ink jet recording apparatus according to any one of claims 1 to 6,
The inkjet recording apparatus, wherein the flash light source is a xenon light source. In the ink jet recording apparatus according to any one of claims 1 to 7,
An ink jet recording apparatus, wherein the recording head discharges cationic polymerization ink.

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