JP2007090642A - Inkjet recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recorder which can uniformly match a granular touch of images by keeping the uniformity of a dot diameter of ink cured on a recording medium even when an irradiation timing after hitting of the ink ejected from a nozzle of a recording head onto the recording medium before receiving of light irradiation by a light irradiating device becomes varied. <P>SOLUTION: The inkjet recorder 1 is equipped with the recording head 9 with the nozzle 8 which ejects a photo-curing type ink 16, the light irradiating device 11 which cures the photo-curing type ink 16 hit on the recording medium S by irradiating the ink with light, and a controlling device 12 which controls an amount of ejection of the photo-curing type ink 16 ejected from the nozzle 8 on the basis of the irradiation timing t after hitting of the photo-curing type ink 16 ejected from the nozzle 8 of the recording head 9 onto the recording medium S before receiving of light irradiation by the light irradiating device 11 so that the dot diameter D of the photo-curing type ink 16 cured on the recording medium becomes equal. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ink jet recording apparatus, and more particularly, to an ink jet recording apparatus in which photocurable ink is irradiated with light to be cured and fixed on a recording medium.

  Nozzle provided on one end surface of a recording head as an image recording apparatus capable of recording an image not only on a normal recording medium such as paper and cloth but also on a recording medium having poor ink absorbability such as a resin film Inkjet recording apparatuses for ejecting ink from ink and landing on recording media have been developed, and the technology is currently applied in various technical fields. Among them, a photo-curing type ink jet recording apparatus that cures and fixes an ink that has landed on a recording medium by irradiating it with light such as ultraviolet rays is actively used as a recording apparatus that can easily obtain a high-definition image. Development is underway.

  In such a photocurable ink jet recording apparatus, generally, a photocurable ink containing a photoinitiator having sensitivity to light such as ultraviolet rays is used. The photo-curable ink spreads on the recording medium until it reaches the recording medium and is cured by light irradiation, the dot diameter is enlarged, bleeding occurs between the dots, or the ink penetrates the recording medium. As a result, the image quality changes.

  In order to avoid such an influence on the image quality such as an increase in the dot diameter of the ink, the time from the ink ejection to the recording medium until the light irradiation, that is, the irradiation timing is usually made as short as possible. For example, in a line head type ink jet recording apparatus, a light irradiation device is provided on the downstream side in the recording medium conveyance direction in the vicinity of the recording head, and in a serial head type ink jet recording apparatus, the light irradiation device is attached to a carriage on which the recording head is mounted (for example, , See Patent Documents 1 and 2).

  On the other hand, as an improvement of such an ink jet recording apparatus, for example, in a line head type ink jet recording apparatus, if a defect occurs in a part of a recording head having a length corresponding to the entire width of the recording medium, the entire recording head is removed. An ink jet recording apparatus is proposed in which a plurality of recording heads having a shorter length are arranged in a staggered manner in the width direction of the recording medium so as to cover the entire width of the recording medium because the yield has to be changed and the yield deteriorates. (See Patent Document 3). Similarly, in a serial head type inkjet recording apparatus, for example, it has been proposed to mount a plurality of recording heads in a staggered manner along the sub-scanning direction on a carriage, for example (see Patent Document 4).

In such an ink jet recording apparatus, as in the case of the line head system illustrated in FIG. 10A, in order to make the dot diameter of the ink on the recording medium uniform in each recording head, each recording head Ha. , there are cases where Hb, Hc, ... light irradiation device at a distance equal distance a ₀ from the nozzle of the corresponding recording heads to La, Lb, Lc, is plurality of ... in a staggered manner. The same applies to a serial head type ink jet recording apparatus.

  However, when an ink jet recording apparatus in which a plurality of recording heads are arranged in a staggered manner as described above, for example, when inks Ia, Ib, Ic,... As shown in the enlarged view of FIG. 10B, due to the mounting error of Ha, Hb, Hc,... There has been a problem that white streaks or the like as indicated by dotted lines appear and the image quality is deteriorated.

  Therefore, in order to avoid the occurrence of such white streaks, as shown in FIG. 11 (A), the number provided on each longitudinal end side of each adjacent recording head is a non-light irradiation type. There has been proposed an ink jet recording apparatus configured such that the positions of the individual nozzles coincide with each other in the transport direction Z of the recording medium with respect to the recording head Ha (see Patent Document 5). In FIG. 11A, the nozzle region whose position matches in the transport direction Z is shown as the overlapping region R.

  Further, from the nozzles in the overlapping region R, for example, the inks Ia and Ib are alternately ejected between the adjacent recording heads Ha and Hb. By adopting such an ink ejection method, as shown in the enlarged view of FIG. 11B, the boundary portion can be blurred in the portion Q on the image corresponding to the overlapping region R of the nozzles. As shown in FIG. 10 (B), it is possible to avoid the appearance of white streaks clearly.

By applying such a recording head nozzle overlap configuration and ink ejection method to the photo-curable ink jet recording apparatus of FIG. 10A, the light irradiation type ink jet recording apparatus has white stripes on the solid image. It was expected that the problem that would occur was resolved.
JP-A-60-132767 JP 2004-203025 A JP 2004-284307 A JP 2005-103844 A JP 2002-225265 A

  Applying the above-described nozzle overlapping configuration of the recording head and the ink ejection method to the light irradiation type inkjet recording apparatus avoids the appearance of white streaks on the solid image as in the case of the non-photocuring type. Can do. However, in the light irradiation type ink jet recording apparatus, when such a configuration and a discharge method are adopted, there is a problem in that dark stripes appear in the portion Q on the solid image corresponding to the overlapping region R of the nozzle. Arise.

  That is, in the photocurable ink jet recording apparatus shown in FIG. 12A to which the above configuration is applied, the recording heads Ha, Hb, and Hc are attached so that white streaks as shown in FIG. 10B do not occur. Even if the error or the like is adjusted and the ink discharge amount from each nozzle of each recording head is appropriately adjusted so as to be equal, the overlapping region R as shown in the enlarged view of FIG. In the portion Q on the image corresponding to, ink having a larger dot diameter appears in the surrounding ink having a uniform dot diameter, and this is recognized as a dark streak.

As shown in FIG. 12A, the light irradiation device Lb cures the ink ejected from the nozzles in the overlapping region R of the recording head Hc onto the recording medium, and the nozzle and light of the recording head Hc. since the direction of the distance a ₁ between the irradiation device Lb becomes longer than the distance a ₀ of the nozzle and the light irradiation device Lb of the recording head Hb, each of the recording heads adjacent in the overlap region R Hb, ink alternate between Hc Ib , Ic is ejected in the corresponding portion Q on the image until the ink Ic ejected from the nozzle of the recording head Hc onto the recording medium travels a distance (A ₁ -A ₀ ). It takes more time and spreads more.

  That is, the irradiation timing from the landing of the ink Ic discharged from the nozzle in the overlapping region R of the recording head Hc to the recording medium until the light irradiation by the light irradiation device Lb is the ink Ib discharged from the nozzle of the recording head Hb. This is longer than the irradiation timing until the light irradiation by the light irradiation device Lb after landing on the recording medium, so that the dot diameter of the ink greatly increases.

  As described above, the longer the distance between the nozzle of the recording head and the light irradiation device, that is, the longer the irradiation timing, the larger the dot diameter of the ink that has landed on the recording medium due to leveling. It becomes difficult to keep the dot diameter of the cured ink uniform. This problem occurs not only in the line head type ink jet recording apparatus as shown in FIG. 12A but also in a serial head type ink jet recording apparatus in which the recording head and the light irradiation device are similarly arranged.

  Further, as shown in FIG. 13A, a line head type or serial head type ink jet recording apparatus in which recording heads Hk, Hc, Hm, Hy and a light irradiation device L are arranged, for example, one of each recording head. When an equal amount of ink is ejected from each nozzle so as to form a line, as shown in FIG. 13 (B), the distance between the nozzles of the recording heads Hk, Hc, Hm, and Hy and the light irradiation device L is set. Depending on the irradiation timing, the ink Ik, Ic, Im, and Iy cured on the recording medium change in dot diameter, the ink dot diameter uniformity is lost, and the graininess of the image is made uniform. I can't.

  Accordingly, the present invention provides an ink dot cured on a recording medium even when the irradiation timing from the landing of the ink ejected from the nozzle of the recording head to the recording medium until the light irradiation by the light irradiation device is different. An object of the present invention is to provide an ink jet recording apparatus capable of maintaining uniform uniformity in diameter and uniforming the graininess of an image.

In order to solve the above problem, the ink jet recording apparatus according to claim 1,
A recording head having a nozzle for discharging photocurable ink to the recording medium;
A light irradiation device for irradiating and curing light curable ink landed on a recording medium; and
From the landing of the photocurable ink ejected from the nozzle of the recording head to the recording medium, for each nozzle of the recording head, so that the dot diameter of the photocurable ink cured on the recording medium becomes equal. And a control device that controls the discharge amount of the photocurable ink discharged from the nozzles based on the irradiation timing until the light irradiation by the light irradiation device is received.

  According to the first aspect of the invention, the control device of the ink jet recording apparatus is based on the irradiation timing from the landing of the ink ejected from the nozzle of the recording head to the recording medium until the light irradiation by the light irradiation device is received. Ink is ejected from the nozzles of the recording head to the recording medium, and the ink that has landed on the recording medium is cured by light irradiation by the light irradiation device, fixed on the recording medium, and recorded on the recording medium The dot diameters of the ink constituting the image are made equal.

  According to a second aspect of the present invention, in the ink jet recording apparatus according to the first aspect, the control device controls the discharge amount of the photocurable ink discharged from the nozzles to be smaller as the irradiation timing is longer. It is characterized by that.

  According to the second aspect of the present invention, the control device of the ink jet recording apparatus according to the first aspect controls the discharge amount of the photocurable ink discharged from the nozzle having a long irradiation timing.

  According to a third aspect of the present invention, in the ink jet recording apparatus according to the first or second aspect, the control device determines an appropriate amount of liquid per droplet of the photocurable ink ejected from the nozzle of the recording head. The discharge amount of the photocurable ink is controlled by changing.

  According to the third aspect of the present invention, the control device of the ink jet recording apparatus adjusts and controls the ink ejection amount by changing the droplet amount per ink ejected from the nozzle of the recording head.

  According to a fourth aspect of the present invention, in the ink jet recording apparatus according to the first or second aspect, the recording head is a multi-drop type recording head, and the control device is ejected from a nozzle of the recording head. The discharge amount of the photocurable ink is controlled by changing the number of drops of the photocurable ink.

  According to the fourth aspect of the invention, the control device of the ink jet recording apparatus adjusts and controls the ink ejection amount by changing the number of ink drops ejected from the nozzles of the multi-drop type recording head.

  The invention according to claim 5 is the ink jet recording apparatus according to any one of claims 1 to 4, wherein the photocurable ink is a cationic polymerization type photocurable ink. To do.

  According to the fifth aspect of the present invention, the control device of the ink jet recording apparatus controls the discharge amount of the cationic polymerization type photocurable ink discharged from the nozzle of the print head based on the irradiation timing. Ink dots constituting an image recorded on the recording medium by ejecting ink from each nozzle to the recording medium, curing the ink landed on the recording medium by light irradiation by a light irradiation device, fixing the ink to the recording medium Make the diameters equal.

  According to the first aspect of the present invention, the irradiation timing from the landing of the ink ejected from the nozzle of the recording head to the recording medium until the light irradiation by the light irradiation device is received is relative to the recording head and the recording medium. It is determined by the target moving speed and the distance between the nozzle of the recording head and the light irradiation device. Then, the dot diameter of the ink that has landed on the recording medium during the irradiation timing is increased by leveling. Therefore, the control device of the ink jet recording apparatus is configured to control the ejection amount of the photocurable ink ejected from the nozzles of the recording head based on the irradiation timing, so that a pre-adjusted amount of ink is recorded on the recording medium. It is possible to align the dot diameters of the inks between the nozzles when they are discharged and cured by the light irradiation of the light irradiation device.

  As described above, according to the first aspect of the present invention, even when ink is ejected from the nozzles of the recording head having different irradiation timing due to a difference in distance from the light irradiation device, the ink discharge amount is adjusted in advance. Thus, the uniformity of the dot diameter of the ink cured on the recording medium can be maintained, and the graininess of the image can be made uniform.

  According to the second aspect of the present invention, the control device of the ink jet recording apparatus according to the first aspect controls the discharge amount of the photocurable ink discharged from the nozzle having a long irradiation timing. For this reason, the dot diameter of the ink to be cured is controlled by ejecting a smaller amount of ink in advance from the nozzle that the dot diameter of the ink ejected with a long irradiation timing becomes larger until it receives light irradiation. It becomes easy to achieve uniformization, and the effect of the invention according to claim 1 can be exhibited accurately.

  According to the invention described in claim 3, the control device of the ink jet recording apparatus, for example, applies a driving voltage to the piezoelectric element to change its deformation degree, or applies a driving voltage to the heating element to heat it. The ink discharge amount is adjusted and controlled by changing the droplet amount per ink droplet discharged from the nozzle of the recording head. Therefore, it becomes possible to adjust and control the ink ejection amount more accurately, and the effects of the invention described in the above claims can be more effectively exhibited.

  According to the fourth aspect of the invention, the control device of the ink jet recording apparatus adjusts and controls the ink ejection amount by changing the number of ink drops ejected from the nozzles of the multi-drop type recording head. Therefore, it becomes possible to adjust and control the ink ejection amount more accurately, and the effects of the invention described in the above claims can be more effectively exhibited.

  According to the fifth aspect of the present invention, if a cationic polymerization type photocurable ink having a property that there is almost no inhibition of the polymerization reaction by oxygen is used, it is said that it is in the air as in the ink jet recording apparatus of the present invention. In an ink jet recording apparatus that records an image in a recording environment, it is possible to cause a polymerization reaction without being affected by oxygen in the air and to cure the ink. Can be demonstrated.

  Embodiments of an ink jet recording apparatus according to the present invention will be described below with reference to the drawings.

  In the following embodiments, a line head type ink jet recording apparatus is described, but the description also applies to a serial head type ink jet recording apparatus in which the relative arrangement of the recording head and the light irradiation device is the same. In the following embodiment, as shown in FIG. 1 described later, a case where recording is performed on a long recording medium S that is wound around a winding roller 5 by an inkjet recording apparatus 1 will be described. It is not limited.

[First Embodiment]
As shown in FIG. 1, a flat platen 2 that supports the recording medium S from the back side of the recording surface is disposed substantially horizontally in the recording unit of the ink jet recording apparatus 1 according to the first embodiment of the present invention. ing. A plurality of driven rollers 3a and 3b for guiding the recording medium S are provided on the upstream side and the downstream side in the recording medium conveyance direction indicated by the arrow Z in the drawing of the platen 2, and the driven roller 3a is provided with the recording medium S. Are horizontally supported at substantially the same height as the platen 2, and the driven roller 3 b guides the recording medium S downward and applies a certain tension to the recording medium S.

  On the most upstream side in the recording medium conveyance direction Z, an original winding roller 4 around which a long recording medium S having a predetermined width is wound is rotatably arranged, and is most downstream in the recording medium conveyance direction Z. On the side, a winding roller 5 for winding the recording medium S unwound from the original winding roller 4 and conveyed on the platen is disposed. The winding roller 5 is a driving source such as a motor (not shown). The recording medium S is transported in the transport direction Z by being driven to rotate and being wound up.

  For example, an endless conveyance belt (not shown) is stretched between the upstream and downstream driven rollers 3 a and 3 a adjacent to the platen 2, and the recording medium S is placed on the conveyance belt on the upper surface side of the platen 2. It is also possible to configure so that

  Above the platen 2, an image recording unit 6 is disposed for ejecting ink to the recording medium S and recording an image on the recording medium. In the present embodiment, as shown in FIG. 2, the image recording unit 6 includes a photo-curing type for each color of yellow (Y), magenta (M), cyan (C), and black (K) with respect to the recording medium S. The recording head groups 7y, 7m, 7c, and 7k that eject ink direct their longitudinal directions in the direction perpendicular to the recording medium transport direction Z, that is, the width direction of the recording head S, and the nozzles 8 face the recording medium S. It is arranged like this.

  The configuration of each recording head group 7y, 7m, 7c, 7k is the same as that of the photo-curable ink jet recording apparatus shown in FIG. 12A, and hereinafter, the black (K) light is representatively represented as a whole. The recording head group 7k that discharges curable ink will be described. FIG. 2 shows the image recording unit 6 in which one recording head group is composed of three recording heads and three light irradiation devices are provided corresponding to the recording head group. The number of recording heads constituting the head group, the number of light irradiation devices, and the arrangement thereof are appropriately determined according to the overall width of the recording medium S and the like. FIG. 2 shows a case where four recording head groups are provided in accordance with each color of YMCK used in the present embodiment. However, the number and arrangement order of the recording head groups are appropriately determined depending on the type of colors used. It is done.

  In one recording head group, the width of the recording medium S is such that a plurality of recording heads 9 a, 9 b, 9 c having nozzles 8 that discharge photocurable ink to the recording medium S cover the entire width of the recording medium S. The recording heads 9a, 9b, and 9c are arranged in a staggered manner in the direction such that the positions of several nozzles 8 provided on the end side of adjacent recording heads coincide with each other in the recording medium conveyance direction Z. It is configured. As in the conventional example described above, in FIG. 2, the region of the nozzle 8 whose position matches in the transport direction Z is shown as the overlapping region R.

  The recording head 9a and the like are provided with piezoelectric elements (not shown) corresponding to the respective nozzles 8. The piezoelectric elements are deformed by an electrostrictive effect according to the driving voltage applied to the piezoelectric elements, and the ink chamber of the nozzles 8 is added. The ink is ejected from each nozzle 8 by pressing. The piezoelectric element used in the present embodiment can adjust the degree of deformation in accordance with the applied drive voltage. The amount of ink ejected from the nozzles 8 by changing the applied drive voltage, That is, the appropriate amount of liquid per drop of ink can be changed.

  For example, it is possible to use a heating element instead of the piezoelectric element. In this case, by changing the drive voltage applied to the heating element, the growth of bubbles that are generated and grow in the ink by heating the heating element. The amount of ink discharged from the nozzle can be changed by changing the degree. It is also possible to use a so-called multi-drop type recording head as the recording head, and to change the amount of ink ejected from the nozzles by changing the number of ink drops ejected from the nozzles. is there.

On the downstream side of the recording heads 9a, 9b, and 9c in the transport direction, there are light irradiation devices 11a, 11b, and 11c including a light source 10 for irradiating and curing the light-curable ink landed on the recording medium S. corresponding recording heads 9a, 9b, are arranged in a staggered manner to a position separated by an equal distance a ₀ from 9c.

  Although not shown, an ink tank for storing the color ink to be ejected is connected to the recording head of each recording head group via a supply pipe.

  Here, as described above, the ink used in the present embodiment is a photo-curing ink that is cured and fixed on a recording medium when irradiated with light, and in particular, an ultraviolet-curing type that is cured by irradiation with ultraviolet light. Ink is preferably used.

  As the ultraviolet curable ink, a radical polymerization ink containing a radical polymerizable compound, a cation polymerization ink containing a cation polymerizable compound, or a radical polymerization ink and a cation polymerization ink are combined as a polymerizable compound. Hybrid ink or the like is preferably used. In particular, it is preferable to use a cationic polymerization ink that has almost no inhibitory action on the polymerization reaction due to oxygen and is excellent in functionality and versatility.

  As the light source 10 of the light irradiation devices 11a, 11b, and 11c, a light source suitable for curing the photocurable ink used is employed. When ultraviolet curable ink is used, as the light source 10, for example, a high pressure mercury lamp, a metal halide lamp, a black light, a hot cathode tube, a cold cathode tube, an LED (Light Emitting Diode), or the like can be employed.

  As shown in FIG. 1, a control device 12 for controlling them is connected to the recording head and the light irradiation device of each recording head group. In this embodiment, the control device 12 is a CPU or ROM (not shown). A RAM, an input / output interface, and the like are configured by a computer connected to a bus.

  As shown in FIG. 3, an input device 13 such as a keyboard and various disk drives is connected to the control device 12, and the distance between the recording head and the platen, the type and thickness of the recording medium are connected via the input device 13. The type of ink used for each recording head of the recording head group, the reference drive voltage applied to the piezoelectric element of each recording head, the head temperature indicating the temperature of the ink in each recording head, and the inkjet recording apparatus 1 is a line head system If so, recording conditions such as the conveyance speed of the recording medium, the carriage speed if the serial head method is used, and the number of passes for designating the number of passes for image recording corresponding to the head width are input. It is also possible to connect an external computer 14 to the control device 12 so as to be communicable, and to take in image data to be recorded on the recording medium S therefrom.

  Further, the light irradiation device 11 is connected to the control device 12, and the control device 12 is configured to control turning on and off of the light source 10, adjusting the light amount, and the like via the light irradiation device 11.

Further, the control device 12 is connected to the recording head 9 and a plurality of piezoelectric elements 15 corresponding to the nozzles 8, and the control device 12 controls the head temperature of the recording head 9 based on the input recording conditions. The reference drive voltage V ₀ to be applied to the input piezoelectric element 15 and the nozzles 8 of the recording head 9 and the light irradiation device 11 are adjusted so that the dot diameter of the ink cured on the recording medium becomes equal. The amount of ink discharged from the nozzles 8 is controlled by adjusting the value of the drive voltage to be applied to each piezoelectric element 15 corresponding to each nozzle 8 of the recording head 9 based on the irradiation timing based on the distance of the ink. It is configured.

Specifically, in this embodiment, the control unit 12, the light irradiation device 11a as shown in FIG. 2, 11b, the recording head 9a the distance between 11c is kept equidistant _{A 0,} 9b, 9c of Since the irradiation timings are all the same, the input reference drive voltage V ₀ is applied to the piezoelectric elements 15 corresponding to the nozzles 8 as they are or with fine adjustment so that the dot diameters of the inks are equal between the print heads. It has become.

Further, the control unit 12, the distance between the light irradiation device 11b the distance A ₁ and by the recording head 9a the irradiation timing is different from the nozzle 8 of the equidistant A _0, a piezoelectric corresponding to the nozzle 8k of 9c overlapping regions R holds the table driving voltages V ₁ to be applied to the element 15 in the storage unit, the discharge amount of ink discharged from the nozzle 8k by applying a driving voltages V ₁ read from the table to the piezoelectric element 15 Is to control.

  Here, the principle of controlling the amount of ink discharged from the nozzles of the recording head will be described.

  The ink 16 ejected from the nozzles 8 of the recording head 9 and landed on the recording surface of the recording medium S has its dot diameter D enlarged by leveling according to the irradiation timing from landing to light irradiation, as shown in FIG. Go. That is, the dot diameter D of the ink cured on the recording medium changes according to the irradiation timing t from when the ink has landed on the recording medium until it is cured by being irradiated with light.

  If the conveyance speed v of the recording medium S is constant, the irradiation timing t is the distance X between the nozzle 8 of the recording head 9 and the light irradiation device 11 shown in FIG. 5, more precisely, from the nozzle 8 of the recording head 9. The nozzle 8 of the recording head 9 and the light irradiation device 11 are proportional to the distance X between the landing position of the ejected ink 16 on the recording medium S and the irradiation position of the light irradiation device 11 from the light source 10 to the recording medium S. As the distance X becomes longer and the irradiation timing t becomes longer, the dot diameter D of the cured ink 16 increases.

  Although the dot diameter enlargement ratio of the ink 16 varies depending on the viscosity and surface tension of the ink, generally, as shown in the graph of FIG. 6, the irradiation timing t from the landing of the ink 16 to the light irradiation, that is, this In this case, as the distance X between the nozzle 8 of the recording head 9 and the light irradiation device 11 increases, the dot diameter D of the ink expands relatively quickly after landing, and the degree of expansion decreases as the irradiation timing t increases. Show the trend.

Therefore, in the present embodiment, the control device 12 is ejected from the nozzles of the recording head having a long distance X with respect to the light irradiation device and a long irradiation timing so that all the dot diameters of the ink cured by the light irradiation device are equal. Control is performed to reduce the amount of ink discharged. That is, the control device 12 causes the piezoelectric element 15 to apply the reference drive voltage V ₀ to the nozzle 8k in the overlapping region R of the recording heads 9a and 9c whose distance from the light irradiation device 11b is farther than the nozzle 8 of the recording head 9b. It is configured to eject fewer ink by applying a low driving voltage V _1.

Driving voltages V ₁ to be applied to the piezoelectric element 15 corresponding to the nozzle 8k can be determined by calculation. Specifically, the irradiation timing obtained from the conveyance speed v of the recording medium S and the distance between the nozzle of the recording head and the light irradiation device, the correlation between the applied drive voltage and the ink ejection amount, the ink viscosity and the surface tension. based on the equal first calculates the dot diameter D ₀ of the ink being cured by light irradiation device 11b that are separated by a distance a ₀ ejected from the nozzles 8 of the recording head 9b by application of the reference drive voltage V _0, followed by , the recording head 9a, the piezoelectric element 15 corresponding to the nozzle 8k so that the dot diameter of the ink being cured by light irradiation device 11b that are separated by a distance a ₁ is ejected from the nozzle 8k of 9c becomes equal to the dot diameter D ₀ the value of to be applied driving voltages V ₁ may be determined by calculating the.

Such drive voltage V ₁ and the nozzle to be applied to the piezoelectric element 15 corresponding to the calculated nozzle 8k and - relationship between the distance X between the light irradiation device is expressed as the graph shown in FIG. 7, the theoretical As a result, as the distance between the nozzle 8 of the recording head 9 and the light irradiation device 11 becomes longer, that is, as the irradiation timing becomes longer, a smaller amount of ink should be ejected.

However, in the present embodiment, in consideration of individual differences among the print heads, the dot diameter D _{0 of the} ink ejected from the print head 9b with the reference drive voltage V ₀ applied and cured by the light irradiation device 11b is applied. actually measuring the recording head 9a, the driving voltages V ₁ the dot diameter of the ink cured while varying the drive voltage V ₁ applied to the piezoelectric element is equal to the dot diameter D ₀ corresponding to the nozzle 8k of 9c experimental Is required.

The storage unit of the control device 12 stores a table of the driving voltage V ₁ obtained corresponding to each value of the reference driving voltage V ₀ and the conveyance speed v of the recording medium S, and the table is used. It is prepared for each type of ink. The controller 12 is configured to control the amount of ink ejected from applying reads driving voltages V ₁ to be applied to the piezoelectric element 15 nozzles 8k corresponding to the nozzle 8k from the table.

In addition, since the recording head groups 7y, 7m, 7c, and 7k use different types of ink and have different viscosities and surface tensions, in the present embodiment, the control device 12 includes the recording head groups 7y, 7m, 7c, 7k nozzles for each 8y, 8m, 8c, the table driving voltages _{V 1} to be applied to the piezoelectric element corresponding to each of the 8k are prepared.

  If a heating element is used instead of the piezoelectric element, the driving voltages to be applied to the heating elements corresponding to the nozzles 8y, 8m, 8c, and 8k are determined in the same manner, and a multi-drop as a recording head is determined. When a recording head of the type is used, the number of ink drops to be ejected from the nozzles 8y, 8m, 8c, and 8k is determined in the same manner.

When the ink jet recording apparatus is a serial head system, the ink 16 ejected from the nozzles 8 of the recording head 9 has an air resistance as compared with the line head system ink jet recording apparatus 1 of the present embodiment shown in FIG. In response, the ink lands on a position slightly shifted to the light irradiation device 11 side from a position immediately below the nozzle on the recording medium. Therefore, when calculating the driving voltage V ₁ to be applied to the piezoelectric element 15 corresponding to the nozzle 8 k by calculation, instead of using the distance X between the nozzle 8 of the recording head 9 and the light irradiation device 11, the recording head 9. Of calculating the irradiation timing using the distance X between the landing position of the ink 16 ejected from the nozzle 8 on the recording medium S and the irradiation position of the light source 10 from the light source 10 onto the recording medium S There can be calculated driving voltages V ₁ more accurately. Such a consideration is not required when experimentally obtaining the drive voltage V _1.

  In addition to this, as shown in FIG. 3, the control device 12 is connected to a drive source of the take-up roller 5, and the control device 12 rotates the rotation speed of the motor based on the input conveyance speed of the recording medium S. It is comprised so that adjustment etc. may be performed. In addition to this, various devices (not shown) of the ink jet recording apparatus 1 are connected to the control device 12 so as to control the normal operation or maintenance operation of the ink jet recording apparatus 1 and the operating environment.

  Next, the operation of the ink jet recording apparatus 1 according to this embodiment will be described.

  When image data is input to the control device 12 of the ink jet recording apparatus 1 and a recording start signal is transmitted, the control device 12 transmits a signal to the light irradiation device 11 to turn on the light source 10 and the winding roller. 5 is rotated to start conveyance of the recording medium S in the conveyance direction Z.

  Then, a drive voltage is applied to the piezoelectric element 15 corresponding to the nozzle 8 to which the photocurable ink is to be ejected based on the image data, and the ink is landed at a predetermined position on the recording medium S. Then, the landed ink is conveyed below the light irradiation device 11 while expanding the dot diameter by leveling on the recording medium, is cured by being irradiated with light, and is fixed to the recording medium S.

At that time, the control device 12 applies the reference drive voltage V _{0 as it} is or finely adjusted to the piezoelectric element 15 corresponding to the nozzle 8 that is not in the overlapping region R of the recording head 9 to eject ink from the nozzle 8. . The ink ejected from the nozzle 8 is cured by light irradiation, and a dot having a dot diameter D ₀ is formed on the recording medium S.

Further, the control device 12 applies the input ink type, the reference drive voltage V _0, and the recording medium S to the piezoelectric elements 15 corresponding to the nozzles 8y, 8m, 8c, and 8k in the overlapping region R of the recording head 9. conveying speed v is applied reads the driving voltages V ₁ to be applied from each of the corresponding table, or to be applied to calculate the driving voltages V ₁ applied, the nozzle 8y, 8m, 8c, less the 8k An amount of ink is ejected. Nozzle 8y, 8m, 8c, ink ejected from the 8k is cured by light irradiation spread by leveling, the dot of the dot diameter D ₀ is formed on the recording medium S.

Thus, the nozzle 8 and the nozzle 8y, 8m, 8c, ink ejected from the 8k become dot having the same diameter all over the recording medium dot diameter D _0, in the case of the conventional example shown in FIG. 12 (B) Such dark streaks do not appear.

  As described above, according to the ink jet recording apparatus 1 according to the present embodiment, the irradiation timing from when the ink ejected from the nozzle 8 of the recording head 9 hits the recording medium to when the light irradiation apparatus 11 receives light irradiation is used. Based on this, the discharge amount of the photo-curable ink discharged from the nozzle 8 and the nozzles 8y, 8m, 8c, and 8k is controlled, and in particular, since the distance from the light irradiation device 11 is farther than the nozzle 8, the irradiation timing becomes longer and leveling is performed. By making the ink discharge amount from the nozzles 8y, 8m, 8c, and 8k whose dot diameter further expands by less than the ink discharge amount from the nozzle 8, the ink dots cured on the recording medium by being irradiated with light. It becomes possible to make the diameter the same as the dot diameter of the ink ejected from the nozzle 8 and cured.

  Therefore, even when ink is ejected from the nozzles of recording heads with different irradiation timings, the uniformity of the dot diameter of the photocurable ink cured on the recording medium can be maintained, and the graininess of the image can be made uniform. It becomes possible.

[Second Embodiment]
The ink jet recording apparatus according to the second embodiment of the present invention is the same as the ink jet recording apparatus 1 according to the first embodiment shown in FIG. 1 and FIG. The configuration of the recording unit is different.

  As shown in FIG. 8, the image recording unit 20 of the ink jet recording apparatus according to this embodiment includes each color of yellow (Y), magenta (M), cyan (C), and black (K) with respect to the recording medium S. The recording heads 21y, 21m, 21c, and 21k that discharge the photo-curable ink are oriented in the direction perpendicular to the recording medium conveyance direction Z, and the nozzles 22y, 22m, 22c, and 22k are directed to the recording medium S. It arrange | positions so that it may oppose.

  Each recording head uses a recording head that can eject ink from a nozzle by applying a driving voltage to a piezoelectric element and change the ejection amount per ink droplet by changing the driving voltage. Similarly to the case of the first embodiment, it is possible to employ a recording head using a heating element or a multi-drop type recording head.

  On the downstream side of the recording heads 21y, 21m, 21c, and 21k in the transport direction, a light irradiation device 24 having a light source 23 for irradiating and curing the light curable ink landed on the recording medium S is recorded in each recording. It is arranged in parallel with the head 21y and the like.

  In FIG. 8, one recording head and one light irradiation device each having a length that covers the entire width of the recording medium S are described. However, as in the case of the first embodiment, It is also possible to arrange a plurality of short recording heads and light irradiation devices in a staggered manner in the width direction of the recording medium S.

In the present embodiment, the distances B ₀ , B ₁ , B ₂ , and B ₃ between the nozzles 22y, 22m, 22c, and 22k of the recording heads 21y, 21m, 21c, and 21k and the light irradiation device 24 are different, and the irradiation timings are respectively different. Is different. Thus, for example, when the driving voltage applied to the piezoelectric element corresponding to the nozzle 22y of the recording head 21y and reference driving voltage V _0, on the recording medium by applying a reference driving voltage V ₀ to the piezoelectric element corresponding to the nozzle 22y The ink is ejected and leveling occurs while the landed ink moves the distance B _0, and the dot diameter D ₀ of the ink on the image formed by the light irradiation from the light irradiation device 24 is set in the first embodiment. It is obtained by calculation or experiment in the same way as the form.

The ink ejected from the nozzles 22m, 22c, and 22k of the recording heads 21m, 21c, and 21k is formed by moving the distances B ₁ , B ₂ , and B ₃ and receiving light from the light irradiation device 24, respectively. as the dot diameter of the ink on the image is equal to the dot diameter _{D 0} respectively, the nozzles 22m, 22c, the driving voltages _V 1 to be applied respectively to the piezoelectric elements corresponding to _22k, V 2, _{V 3} calculations or experiments, respectively Determined by

In the present embodiment, as in the first embodiment, the storage means of the control device includes the reference drive voltage V ₀ and the conveyance speed v of the recording medium S for each of the recording heads 21m, 21c, and 21k. Tables of drive voltages V ₁ , V ₂ , and V ₃ obtained corresponding to the values are stored, and a table is prepared for each type of ink used in each of the recording heads 21m, 21c, and 21k. ing.

The control device reads out and applies drive voltages V ₁ , V ₂ , and V ₃ to be applied to the piezoelectric elements corresponding to the nozzles 22 m, 22 c, and 22 k from these tables, and discharges them from the nozzles 22 m, 22 c, and 22 k. Control is performed so that the amount of ink discharged is less than the amount of ink discharged from the nozzles 22y.

The recording head to be applied to the reference driving voltage V ₀ is not limited to the recording head 21y, also meet the condition dot diameter of the cured ink are the same size, the recording head 21y, 21m, 21c, It is also possible to apply a drive voltage other than the reference drive voltage V _{0 to} all 21k.

If ink is ejected from the nozzles 22y, 22m, 22c, and 22k of the recording heads 21y, 21m, 21c, and 21k of the image recording unit 20 having such a configuration and cured by the light irradiation device 24, the nozzles 22y, 22m, 22c, ink ejected from 22k is a dot having the same diameter all over the recording medium dot diameter D _0.

  As described above, in the ink jet recording apparatus according to the second embodiment, the same effect as that of the ink jet recording apparatus 1 according to the first embodiment can be obtained. Even when the ink is discharged, the uniformity of the dot diameter of the photocurable ink cured on the recording medium can be maintained, and the graininess of the image can be made uniform.

[Third Embodiment]
The ink jet recording apparatus according to the third embodiment of the present invention is similar to the second embodiment in that the entire structure and the structure of the control device are the ink jet recording apparatus according to the first embodiment shown in FIGS. 1 and 3, respectively. 1, but the configuration of the image recording unit is different.

  In the first and second embodiments, the adjustment of the ink dot diameter based on the irradiation timing based on the difference between the nozzle-light irradiation device distances between the plurality of recording heads is shown. It can also occur in a book recording head. In the present embodiment, as an example in which a difference in irradiation timing occurs in one recording head, an ink jet recording apparatus in which the recording head and the light irradiation apparatus are provided in non-parallel will be described as an example.

In the image recording unit 40 of the ink jet recording apparatus according to the present embodiment, as shown in FIG. 9, a recording head 41 that discharges, for example, black (K) photocurable ink to the recording medium S has a longitudinal direction. The nozzles 42 _{0 to} 42 _n-1 are arranged so as to have an angle of 45 degrees with respect to the recording medium conveyance direction Z, and so as to face the recording medium S.

  Each recording head uses a recording head that can eject ink from a nozzle by applying a driving voltage to a piezoelectric element and change the ejection amount per ink droplet by changing the driving voltage. As in the first and second embodiments, it is also possible to employ a recording head using a heating element or a multi-drop recording head.

  On the downstream side of the recording head 41 in the transport direction, a light irradiation device 44 including a light source 43 for irradiating and curing the light curable ink landed on the recording medium S is perpendicular to the transport direction Z. It is arranged so as to face.

  In the image recording unit 40 of the present embodiment, a plurality of recording heads 41 are provided depending on the type of ink used, or a plurality of shorter recording heads in which the recording heads 41 and the light irradiation devices 44 are arranged in a staggered manner. It is also possible to configure with a light irradiation device.

In the present embodiment, the distances C _{0 to} C _n-1 between the nozzles 42 _{0 to} 42 _n-1 of the recording head 41 and the light irradiation device 44 are different, and the irradiation timings are different. Thus, for example, when the driving voltage applied to the piezoelectric element corresponding to the nozzle 42 ₀ as a reference driving voltage V _0, the ink on the recording medium by applying a reference driving voltage V ₀ to the piezoelectric element corresponding to the nozzle 42 ₀ Leveling occurs while the ejected and landed ink moves the distance C _0, and the dot diameter D ₀ of the ink on the image formed by receiving the light irradiation from the light irradiation device 44 is set to the first and second inks. Similar to the embodiment, it is obtained by calculation or experiment.

The ink ejected from the nozzles 42 _{1 to} 42 _n−1 moves on the image formed at the irradiation timing until the ink moves through the distances C _{1 to} C _n−1 and receives the light irradiation from the light irradiation device 44. as the dot diameter of the ink is equal to the dot diameter _{D 0} respectively, determined by calculation or experiment, respectively the drive voltage _{V 1 ~V n-1} to be applied respectively to the piezoelectric elements corresponding to the nozzles _{42 1 ~42 n-1} To do.

Note that, for example, a predetermined number of nozzles are selected from the nozzles 42 _{0 to} 42 _{n−1 and} a driving voltage is determined by the above calculation or experiment, and driving voltages for other nozzles are selected before and after the nozzles. It is also possible to approximate and determine from the change rate of the drive voltage determined for the selected nozzle.

In the present embodiment, as in the first and second embodiments, the storage unit of the control device includes the reference drive voltage V ₀ and the recording medium for the nozzles 42 _{1 to} 42 _n−1 of the recording head 41. A table of drive voltages V _{1 to} V _n−1 obtained corresponding to each value of the transport speed v of S is stored, and is used when there are a plurality of types of ink used for the recording head 41. A table is prepared for each ink.

The control device reads out and applies drive voltages V _{1 to} V _n−1 to be applied to the piezoelectric elements corresponding to the nozzles 42 _{1 to} 42 _n−1 from those tables, and applies them from the nozzles 42 _{1 to} 42 _n−1. and it is configured so that the discharge amount of ink ejected performs control for less than the amount of ink ejected from the nozzles 42 _0.

The nozzle to be applied to the reference driving voltage V ₀ is not limited to the nozzle 42 ₀ the closest to the light irradiation device 44, also meet the condition dot diameter of the cured ink are the same size, the recording head It is also possible to apply a drive voltage other than the reference drive voltage V _{0 to} all of 42 _{0 to} 42 _n−1 .

If ink is ejected from the nozzles 42 _{0 to} 42 _n−1 of the recording head 41 of the image recording unit 40 having such a configuration and cured by the light irradiation device 44, the ink is ejected from the nozzles 42 _{0 to} 42 _n−1 . the ink is the dot having the same diameter all over the recording medium dot diameter D _0.

  As described above, also in the ink jet recording apparatus according to the third embodiment, the same effects as those of the ink jet recording apparatuses according to the first and second embodiments can be obtained, and the distance from the light irradiation apparatus is different. Even when ink is ejected from nozzles of recording heads with different irradiation timings, the uniformity of the dot diameter of the photocurable ink cured on the recording medium can be maintained, and the graininess of the image can be made uniform. It becomes possible.

  In the first to third embodiments, when the amount of ink discharged from the nozzle is reduced and the density of the dots on the image is reduced, the ink is discharged from the nozzle that reduces the amount of ink discharged. It is also possible to increase the ink density in advance. For this reason, when the viscosity or surface tension of the ink changes, the driving voltage to be applied is calculated in consideration thereof.

It is a figure which shows the structure of the inkjet recording device which concerns on 1st Embodiment. It is a figure which shows the structure of the image recording part of the inkjet recording device of FIG. It is a block diagram which shows the control structure of the inkjet recording device of FIG. 1 containing a control apparatus. It is a figure which shows the ink on the recording medium which a dot diameter expands by the increase in irradiation timing. It is a figure explaining the distance of a recording head and a light irradiation apparatus. 6 is a graph showing a relationship between a dot diameter of ink and a distance between a recording head and a light irradiation device. It is a graph which shows the relationship between the drive voltage which should be applied to a piezoelectric element, and the distance between a recording head and light irradiation apparatus. It is a figure which shows the structure of the image recording part of the inkjet recording device which concerns on 2nd Embodiment. It is a figure which shows the structure of the image recording part of the inkjet recording device which concerns on 3rd Embodiment. (A) The block diagram of the conventional photocurable inkjet recording device, (B) It is an enlarged view which shows the white stripe which appears on an image. 2A is a configuration diagram of a conventional inkjet recording apparatus in which an overlapping region is provided between adjacent recording heads, and FIG. 2B is an enlarged view showing a state in which white streaks are blurred on an image. 2A is a configuration diagram of a conventional photo-curable ink jet recording apparatus in which an overlapping region is provided between adjacent recording heads, and FIG. 2B is an enlarged view showing dark streaks appearing on an image. (A) The block diagram of the conventional inkjet recording device in which the several recording head and the light irradiation apparatus are arrange | positioned in parallel, (B) The enlarged view which shows the dot from which the diameter which appears on an image differs.

Explanation of symbols

1 inkjet recording apparatus _{8,8y~8k, 22y~22k, 42 0 ~42 n} -1 nozzle 9,9a~9c, 21y~21k, 41 recording heads 11,11a~11c, 24,44 light irradiation device 12 control device 16 Ink A ₀ , A ₁ , B _{0 to} B ₃ , C _{0 to} C _n−1 , X Distance between nozzle and light irradiation device D, D ₀ dot diameter S Recording medium t Irradiation timing

Claims (5)

A recording head having a nozzle for discharging photocurable ink to the recording medium;
A light irradiation device for irradiating and curing light curable ink landed on a recording medium; and
From the landing of the photocurable ink ejected from the nozzle of the recording head to the recording medium, for each nozzle of the recording head, so that the dot diameter of the photocurable ink cured on the recording medium becomes equal. An ink jet recording apparatus comprising: a control device that controls a discharge amount of photocurable ink discharged from a nozzle based on an irradiation timing until light irradiation by the light irradiation device is received.   The ink jet recording apparatus according to claim 1, wherein the control device controls the discharge amount of the photocurable ink discharged from the nozzle to be decreased as the irradiation timing is longer.   2. The control device according to claim 1, wherein the controller controls the discharge amount of the photocurable ink by changing an appropriate amount of liquid per droplet of the photocurable ink discharged from the nozzle of the recording head. The ink jet recording apparatus according to claim 2. The recording head is a multi-drop recording head,
3. The control device according to claim 1, wherein the controller controls the ejection amount of the photocurable ink by changing the number of drops of the photocurable ink ejected from the nozzles of the recording head. The ink jet recording apparatus described.   The inkjet recording apparatus according to claim 1, wherein the photocurable ink is a cationic polymerization type photocurable ink.

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