JP2004284141A - Ultraviolet curing inkjet recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultraviolet curing inkjet recoding device which is applicable to various recording mediums, and carries out continuous recording over a long period of time with high reliability. <P>SOLUTION: According to the structure of the ink jet recording device, an inkjet recording head 30 for ejecting ultraviolet curing ink and ultraviolet emitting means are arranged adjacently to each other, and an interval between the same is determined based on an interval between a recording medium holding surface of a recording medium holding means 70, and each ultraviolet emitting means, an interval between the recording medium holding means and the ink jet recording head, and an incidence angle of ultraviolet rays at a location that is closest to the inkjet recording head in an irradiation range of the ultraviolet emitting means with respect to the recording medium holding surface. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an ultraviolet-curable inkjet recording apparatus that forms an image by attaching an ultraviolet-curable ink that is cured by ultraviolet irradiation to a recording medium.
[0002]
[Prior art]
Ink jet recording apparatuses are currently used in various fields because of their light weight, small size, and low vibration and noise during recording, and recording media to be printed are also diversified. . Conventionally, paper has been mostly used as a recording medium, but in recent years, application to recording media other than paper has been attempted. As a recording method therefor, an ink jet recording method using an ultraviolet curable ink has been proposed.
[0003]
Due to the property that the ultraviolet curable ink is cured by irradiating ultraviolet rays, by irradiating the ink ejected from the ink jet recording head and the ink attached to the surface of the recording medium with ultraviolet rays, the ink penetrates into the recording medium or is exposed on the recording medium. It is possible to quickly cure the ink before bleeding occurs. Therefore, high quality can be achieved on not only ink-absorbing recording media such as paper, fabric, wood, etc. but also non-ink-absorbing recording media such as leather, glass, metal, ceramics and films without forming an ink receiving layer. Can be formed.
[0004]
As a method of curing the ink ejected from the ink jet recording head by irradiating ultraviolet rays, for example, methods such as Patent Documents 1 and 2 have been proposed. Patent Literature 1 describes that an ultraviolet ray irradiating unit is provided in the vicinity of an ejection nozzle to cure ink ejected on the surface of a sheet by ultraviolet irradiation. Further, Patent Document 2 describes that print heads are arranged in a sub-scanning direction on a carriage movable in a main scanning direction, and ultraviolet lamps are arranged on the left and right sides of the print head.
[0005]
When the ultraviolet irradiation means is arranged in this way, it is better to install the ultraviolet irradiation means at a position as close as possible to the ink jet recording head in order to cure the ink adhering to the recording medium as quickly as possible and form a high-quality image with little bleeding. However, since the ultraviolet light emitted from the ultraviolet light irradiating means is reflected and reflected by a reflector in the ultraviolet lamp in addition to the direct irradiation from the ultraviolet lamp, the light is irradiated in various directions on the surface of the recording medium facing the recording medium or the surface holding the recording medium. And the reflected ultraviolet light reaches the discharge port of the inkjet recording head. Therefore, if the ultraviolet irradiation means is too close to the ink jet recording head, the amount of the ultraviolet light reaching the ejection port of the ink jet recording head will be increased, and as a result, the ink of the ejection port will be hardened and clogged. I will.
[0006]
FIG. 11 is a diagram showing a positional relationship between the inkjet recording head 30 and the ultraviolet irradiation units 60a and 60b when an ultraviolet irradiation unit according to the related art is provided.
[0007]
Ultraviolet light irradiating means 60a, 60b sandwiching the inkjet recording head 30 in the main scanning direction so that the ultraviolet curable ink ejected from the inkjet recording head 30 to the recording medium is quickly irradiated with ultraviolet rays in both the forward path and the backward path. Is installed. The irradiated ultraviolet light is reflected by a holding surface such as a recording medium or a platen facing the ultraviolet irradiation means as shown in FIG. 12, and reaches the surface of the adjacent inkjet recording head. Irradiation at all times may cause irrecoverable clogging.
[0008]
Therefore, Patent Document 3 describes that a nozzle plate of an ink jet recording head has a light-shielding property and a water-repellent eutectoid plating layer is formed, thereby drawing ink into the back and preventing nozzle clogging due to ultraviolet rays. Have been. However, if the recording operation is continuously performed for a long time, the ink will remain on the nozzle plate surface, and the ink will eventually be cured by the reflected ultraviolet light, and the nozzles may be clogged.
[0009]
[Patent Document 1]
JP-A-2-283452
[Patent Document 2]
JP-A-2002-292907
[Patent Document 3]
JP-A-11-10874
[0010]
[Problems to be solved by the invention]
Thus, the present invention is to solve the above problems and provide an ultraviolet-curable inkjet recording apparatus that can be applied to various recording media and has high reliability even for long-time continuous recording. is there.
[0011]
[Means for Solving the Problems]
An ultraviolet curable ink jet recording apparatus according to the present invention includes an ink jet recording head that discharges ultraviolet curable ink toward a recording medium from a plurality of ink ejection ports, and an ultraviolet irradiation unit that irradiates the ink adhered to the recording medium with ultraviolet light. Drive control means for driving and controlling the ink jet recording head so as to selectively discharge ink from the ink discharge port in accordance with an image signal; holding means for holding the recording medium at a recording position; In an inkjet recording apparatus comprising a head and a movement control unit for relatively moving the recording medium, the ultraviolet irradiation unit is adjacent to the inkjet recording head at a distance L that satisfies (Equation 1). It is characterized by being arranged.
L ≧ (d ₁ + D ₂ ) Tan θ (Equation 1)
However,
d ₁ : Distance between the surface of the ultraviolet irradiation unit facing the holding unit and the recording medium holding surface of the holding unit
d ₂ : Distance between the surface facing the holding means of the ink jet recording head and the recording medium holding surface
θ: the angle of incidence of ultraviolet light at the position closest to the ink jet recording head in the irradiation range of the ultraviolet light irradiation means on the recording medium holding surface
[0012]
Further, at least one of the ultraviolet irradiation means and the ink jet recording head is arranged so as to be inclined away from the other opposing surface. Further, the interval L and the interval d ₁ And the distance d ₂ And a distance adjusting means for adjusting at least one of the distances. Further, the interval d ₁ , D ₂ Is d ₁ ≧ d ₂ And the distance d ₁ Is 1 to 20 mm. Further, the movement control means controls the reciprocating movement of the ultraviolet irradiation means and the ink jet recording head integrally in the scanning direction, and the ultraviolet irradiation means moves forward and rear in the scanning direction with respect to the ink jet recording head. It is characterized by being arranged on at least one. Further, the movement control means controls the movement of the recording medium in a direction orthogonal to the arrangement direction of the ejection ports in the ink jet recording head in which a plurality of ink ejection ports are arranged in a line, and the ultraviolet irradiation means includes: It is characterized in that the ink jet recording head is arranged on the downstream side in the moving direction of the recording medium.
[0013]
With the above configuration, the distance between the ink jet recording head and the ultraviolet irradiation means is defined by the distance from the recording medium holding surface of the holding means as shown in (Equation 1). The effect of the ultraviolet light reflected on the recording medium can be suppressed even when recording is performed on the recording medium. That is, since the surface of the recording medium is located at a position closer to the ultraviolet irradiation means than the recording medium holding surface, the ultraviolet light reflected on the recording medium surface is more ultraviolet irradiation means than the ultraviolet light reflected on the recording medium holding surface. If the ultraviolet rays reflected on the recording medium holding surface do not affect the ink jet recording head, the influence can be suppressed even for recording media having various thicknesses. Further, when a plurality of recording media are held on the recording medium holding surface, the recording medium holding surface is exposed from between the recording media, and the ultraviolet light is reflected, or the inkjet recording head is moved to a position separated from both ends of the recording medium. In this case, even when ultraviolet rays are reflected on the recording medium holding surface, the influence can be suppressed.
[0014]
Also, by defining the interval between the inkjet recording head and the ultraviolet irradiation means based on the incident angle of the ultraviolet light at the position closest to the inkjet recording head in the irradiation range of the ultraviolet irradiation means with respect to the recording medium holding surface, the recording medium holding surface It is possible to reliably suppress the influence of the ultraviolet ray which most affects the ink jet recording head among the ultraviolet rays reflected by the light source.
[0015]
As described above, the influence of ultraviolet rays reflected on the surface of the recording medium can be suppressed, so that even if continuous recording is performed for a long time, the discharge ports of the inkjet recording head are not clogged by the ultraviolet rays.
[0016]
Further, since at least one of the ultraviolet irradiation unit and the ink jet recording head is arranged so as to be inclined away from the other opposing surface, the entire distance between the ultraviolet irradiation unit and the ink jet recording head is not increased (formula (1)). The interval L defined in 1) can be set, and the device can be made compact. Further, if the ultraviolet irradiating means is disposed at an angle, the incident angle θ in (Equation 1) can be reduced, and accordingly, the ultraviolet irradiating means can be disposed at a position close to the ink jet recording head. Further, the interval L and the interval d ₁ And the distance d ₂ By providing at least one interval adjusting means for adjusting the intervals, it is possible to adjust the intervals appropriately for various recording media and suppress the influence of ultraviolet rays reflected on the recording medium surface.
[0017]
Also, the interval d ₁ , D ₂ For d ₁ ≧ d ₂ It is preferable that d ₁ <D ₂ In the case of, the interval between the recording medium and the ultraviolet irradiation means must be set with priority to prevent collision, and as a result, the interval between the inkjet recording head and the recording medium must be increased, and The quality will be inferior. And the interval d ₁ Is preferably in the range of 1 to 20 mm. When the distance exceeds 20 mm, the irradiation area of the ultraviolet light reflected on the opposed recording medium increases, and the distance between the inkjet recording head and the ultraviolet light irradiation means has to be increased. As a result, the ink can be effectively cured. This is because it will not be possible. Also, if the thickness is less than 1 mm, the danger of the ultraviolet irradiation means and the ink jet recording head colliding with the recording medium increases.
[0018]
Further, when the ultraviolet irradiation unit and the inkjet recording head are reciprocally moved in the scanning direction as a unit, the ultraviolet irradiation unit is disposed at least one of the front and the rear in the scanning direction with respect to the inkjet recording head, so that the recording medium can be printed. The attached ink can be quickly cured. Further, when the recording medium is moved in a direction orthogonal to the arrangement direction of the ejection ports in the ink jet recording head in which the plurality of ink ejection ports are arranged in a line, the ultraviolet irradiation means is used to move the recording medium with respect to the ink jet recording head. By arranging it on the downstream side in the direction, the ink attached to the recording medium can be quickly cured in the same manner.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described. Note that the embodiments described below are preferred specific examples for carrying out the present invention, and therefore, various technical limitations are made. However, the present invention is particularly limited in the following description. It is not limited to these forms unless otherwise specified.
[0020]
FIG. 1 is an overall perspective view of an ultraviolet-curable inkjet recording apparatus according to a first embodiment of the present invention. The recording medium holding unit 70 is formed of an edgeless belt that supports the recording medium 8, and is driven to rotate by the transport roll 71. The recording medium 8 is transported in the sub-scanning direction Y by the transport rolls 71, and an ultraviolet curable ink is attached to the transported recording medium 8 by the inkjet recording head 30. Then, the ultraviolet curable ink adhered to the recording medium 8 is cured by being irradiated with ultraviolet rays by the ultraviolet irradiation means 60a and 60b.
[0021]
The ink jet recording head 30 is positioned and fixed on a carriage 40 supported by a guide rail 43. The carriage 40 is driven by a carriage motor 41 on the recording medium 8 via a timing belt 42 in a main scanning direction (crossing direction X1). , X2). In response to the image signal, the carriage 40 is moved in the main scanning directions X1 and X2, and a drive signal is input from an external drive control unit (not shown) to the inkjet recording head 30 via the flexible cable 5 so that the ultraviolet curable ink is discharged. The ink is discharged toward the surface of the recording medium 8. Ultraviolet rays are applied to the ink adhered to the surface of the recording medium 8 by the ultraviolet irradiation means 60a and 60b, and the movement is controlled so that the recording medium 8 is transported in the sub-scanning direction Y for each scanning line. By sequentially repeating the above operations, an image can be formed on the recording medium 8. Since the ultraviolet irradiation means 60a and 60b may move to a position outside the recording area where no recording medium exists, it is necessary that the ultraviolet irradiation means 60a and 60b are not affected by ultraviolet rays reflected from the recording medium holding surface.
[0022]
The ultraviolet light irradiating means 60a and 60b perform ink jet recording so that the ultraviolet curable ink ejected from the ink jet recording head 30 is immediately irradiated on the recording medium 8 immediately after the ultraviolet curable ink is ejected from the ink jet recording head 30 in both the forward path X1 and the backward path X2. The head 30 is fixed on the carriage 40 so as to sandwich the head 30 in the main scanning direction. The ultraviolet curable ink ejected from the ink jet recording head 30 is quickly cured by ultraviolet irradiation by the ultraviolet irradiation means 60a in the forward path X1, and is rapidly cured by ultraviolet irradiation by the ultraviolet irradiation means 60b in the return path X2. Formed on top.
[0023]
FIG. 2 is a diagram of the ultraviolet irradiation units 60a and 60b and the inkjet recording head 30 installed on the carriage 40 as viewed from the sub-scanning direction Y. As shown in FIG. 2, the ultraviolet irradiation means 60a and 60b are provided inside a box-shaped irradiation unit housing 64 having an irradiation opening 63 in which quartz glass is disposed, and an ultraviolet lamp 61, a cold for transmitting heat rays and reflecting ultraviolet rays. A reflecting mirror 62 composed of a mirror and an intake port 65 for taking in cooling air from outside are provided inside the irradiation unit housing 64. Cooling air from the intake port 65 is sent into the irradiation unit housing 64 by a blower fan (not shown), and is exhausted to the outside of the irradiation unit housing 64 from an exhaust port (not shown). The direction of the airflow discharged from the exhaust port is set to a direction in which the inkjet recording head is not installed so as not to adversely affect the ejection of the inkjet recording head.
[0024]
In this configuration example, the irradiation unit housing itself is mounted on the carriage like the ink jet recording head, but an optical fiber cable may be used as the ultraviolet light guide path. If ultraviolet rays can be guided to the vicinity of the inkjet recording head 30 via a flexible and flexible optical fiber cable, it is not necessary to install the ultraviolet irradiation unit itself on the carriage 40, and the carriage 40 can be reduced in size and weight. Examples of the light source used for the ultraviolet lamp 61 include a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a xenon flash lamp, a carbon arc lamp, a metal halide lamp, a deep UV lamp, and a UV laser. If so, it can be used arbitrarily. However, the irradiation range of the ultraviolet rays by the ultraviolet irradiation means needs to have a width larger than the recording area of the inkjet recording head 30 in at least one scan.
[0025]
FIG. 3 is a diagram showing a positional relationship between the inkjet recording head 30 and the ultraviolet irradiation units 60a and 60b.
[0026]
The interval L between the ultraviolet irradiation means 60a and 60b and the adjacent inkjet recording head 30 is L ≧ (d ₁ + D ₂ ) It is necessary to set so as to satisfy the condition of tan θ.
here,
d ₁ : The distance between the recording medium holding surface of the recording medium holding means 70 and the surface facing the irradiation opening of the ultraviolet irradiation means 60a, 60b;
d ₂ : The distance between the recording medium holding surface of the recording medium holding means 70 and the opposing surface of the inkjet recording head 30;
θ: the angle of incidence of ultraviolet light at the position closest to the inkjet recording head in the irradiation range of the ultraviolet irradiation means on the recording medium holding surface
It is.
[0027]
Specifically, the inkjet recording head is irradiated with a perpendicular drawn down from the inner peripheral surface of the irradiation opening of the ultraviolet irradiation unit 60 adjacent to the inkjet recording head 30 to the recording medium holding surface and the irradiation range of the ultraviolet irradiation unit on the recording medium holding surface. The distance between the closest position and the closest position is W1, and the ultraviolet light reflected on the closest position and the recording medium holding surface is d from the recording medium holding means. ₂ Assuming that the distance from the arrival point to the distant position to the perpendicular drawn down to the recording medium holding surface is W2, the ultraviolet light at the incident angle θ at the closest position is W1 = from the inner peripheral surface of the irradiation opening of the ultraviolet irradiation means. d ₁ After reaching the position where tan θ, the light is reflected at the reflection angle θ, so that W2 = d ₂ The position will reach tan θ.
[0028]
That is, in order to prevent the ultraviolet light reflected on the recording medium holding surface from reaching the surface of the inkjet recording head, the distance L between the inkjet recording head 30 and the ultraviolet irradiation means 60a, 60b is set to
W1 + W2 = d ₁ tanθ + d ₂ tan θ = (d ₁ + D ₂ ) Tanθ
It is necessary to set above. Under such conditions, even if the recording medium surface is a metal having a mirror surface, the ultraviolet light reflected from the recording medium surface does not reach the surface of the head plate 10 of the ink jet recording head 30, and the It is possible to suppress the occurrence of ejection failure due to ink thickening and ink curing in the ejection port and its peripheral portion, and it is possible to obtain high continuous ejection stability. The same applies to the case where the ultraviolet irradiation means 60a and 60b move to a position where no recording medium exists and the ultraviolet light is reflected on the recording medium holding surface.
[0029]
At this time, d ₁ And d ₂ Is d ₁ ≧ d ₂ It is preferred that In order to form a clear image on a recording medium, it is desirable that the distance between the recording medium and the inkjet recording head be as small as possible. ₁ <D ₂ In the case of, the interval between the recording medium and the ultraviolet irradiation means must be set with priority to prevent collision, and as a result, the interval between the inkjet recording head and the recording medium must be increased, and The quality will be inferior. Further, the interval d ₁ Is preferably in the range of 1 to 20 mm. When the distance exceeds 20 mm, the irradiation area of the ultraviolet light reflected on the opposed recording medium increases, and the distance between the inkjet recording head and the ultraviolet light irradiation means has to be increased. As a result, the ink can be effectively cured. This is because it will not be possible. Also, if the thickness is less than 1 mm, the danger of the ultraviolet irradiation means and the ink jet recording head colliding with the recording medium increases.
[0030]
Also, the interval L is preferably in the range of 5 to 150 mm, more preferably in the range of 10 to 60 mm. If it is less than 5 mm, the ink jet recording head is liable to be affected by ultraviolet light irregularly reflected by the ultraviolet irradiation means. In other words, when the interval L is large, the influence of the irregularly reflected ultraviolet light is negligible and the ink jet recording head is not clogged. The effect comes out. On the other hand, if the thickness exceeds 150 mm, it takes a long time from when the ink adheres to the recording medium to when the curing is performed by ultraviolet rays, and when a cloth or the like is used as the recording medium, the bleeding of the ink increases.
[0031]
When adjusting the interval L, for example, the ultraviolet irradiation unit is installed on a support carriage (not shown) movable on a guide rail installed in parallel with the scanning direction of the carriage 40. The support carriage is provided with a female screw portion integrated therewith, and a lead screw arranged parallel to the scanning direction of the carriage 40 is screwed into the female screw portion. By controlling the rotation direction and the amount of rotation of this lead screw connected to the output shaft of the motor via the joint part, the support carriage supporting the ultraviolet irradiation means can be slid in the main scanning direction by the amount of screw feed of the lead screw. It becomes possible. As a result, the distance L between the inkjet recording head and the ultraviolet irradiation means is controlled.
[0032]
Interval d ₁ And d ₂ In the case of adjusting the distance, for example, the carriage 40 supporting the inkjet recording head and the ultraviolet irradiation means may be movable in the vertical direction with respect to the recording medium holding surface, and the guide rail described above is installed perpendicular to the scanning direction. What is necessary is just to adjust the whole carriage 40 up and down by a lead screw. Thereby, d can be changed.
[0033]
Note that the above example of the interval adjusting mechanism is merely an example, and the present invention is not limited to this example.
[0034]
FIG. 4 shows a modification of FIG. 2, in which parts having the same functions as those in FIG. 2 are indicated by the same reference numerals, and description of overlapping parts will be omitted. The difference from FIG. 2 is that the ultraviolet irradiation units 60a and 60b are installed to be inclined forward or backward in the main scanning direction. The central axis of the ink jet recording head 30 is inclined parallel to the perpendicular to the recording medium holding means, and the central axes of the ultraviolet irradiation means 60a and 60b are inclined away from the ink jet recording head 30 with respect to the perpendicular to the recording medium holding means. It is installed on the carriage 40. The carriage 40 is provided with a shaft support corresponding to each ultraviolet irradiation means. If each ultraviolet irradiation means is fixed to the shaft support with a screw or the like, the ultraviolet irradiation means can be fixed at a predetermined inclination angle. And the inclination angle can be easily adjusted. Also, the interval d ₁ , D ₂ In addition, if a means for moving the entire carriage 40 in the direction perpendicular to the recording medium holding surface and adjusting means is provided, and a means for finely adjusting the ultraviolet irradiation means and the ink jet recording head individually to vertically move the recording medium, It can be adjusted appropriately according to.
[0035]
In this case, the inclination angles of the ultraviolet irradiation means 60a and 60b are preferably set so that the central axis is in a range of 1 to 30 degrees with respect to a perpendicular to the recording medium holding means. According to this configuration, as compared with the case where the central axis of the ultraviolet irradiation unit is parallel to the perpendicular to the recording medium holding unit, the ultraviolet incident angle θ on the recording medium holding surface is reduced, and the above-described interval L is shortened. (See FIG. 5). Therefore, it is possible to further reduce the size of the apparatus by reducing the distance L between the inkjet recording head 30 and the ultraviolet irradiation means 60a and 60b. Then, the time until the ultraviolet curable ink ejected from the ink jet recording head 30 and adhered onto the recording medium 8 is irradiated with ultraviolet rays can be shortened, and the occurrence of bleeding of the ultraviolet curable ink can be suppressed.
[0036]
FIG. 6 shows a configuration in which the inkjet recording head 30 and the ultraviolet irradiation units 60a and 60b are mounted on the carriage 40 such that the central axes of the inkjet recording head 30 and the ultraviolet irradiation units 60a and 60b are inclined in the main scanning direction with respect to the perpendicular to the recording medium holding surface. For example, the two ink jet recording heads 30 and 31 are arranged so that the ink arrangement is symmetrical in the left and right directions. In the forward path X1, image formation by the ink jet recording head 31 and ultraviolet irradiation by the ultraviolet irradiation means 60a are performed. Performs image formation by the inkjet recording head 30 and ultraviolet irradiation by the ultraviolet irradiation means 60b. If the ink jet recording heads of the same arrangement are set to be driven in order in the forward path and the return path, the color inks can always be applied in the same order, so that the occurrence of horizontal stripes due to the different order can be prevented.
[0037]
Further, since the inkjet recording heads 30 and 31 perform unidirectional recording in either of the forward path and the backward path, the ultraviolet curable ink ejected from each inkjet recording head is more mainstream than the direction perpendicular to the recording medium 8. It is mounted so that its central axis is inclined with respect to the perpendicular to the recording medium holding means so as to be discharged on the upstream side in the scanning directions X1 and X2, respectively.
[0038]
In this case, the inclination angles of the inkjet recording heads 30 and 31 and the ultraviolet irradiation means 60a and 60b should be set in the range of 1 to 30 degrees with respect to the perpendicular to the recording medium holding means, as in FIG. preferable.
[0039]
Further, when the inclination angle of the ink jet recording head is set according to the moving speed of the carriage 40, the ultraviolet curable ink ejected from the ink jet recording head apparently reaches the recording medium 8 perpendicularly, and the main dot is formed on the recording medium 8 with the main dot. It is possible to form a sharp image without image deterioration due to a flying speed difference from a satellite.
[0040]
Then, the reciprocating speed of the carriage 40 in the main scanning direction can be set to be high, and the productivity can be improved.
[0041]
FIG. 7 shows a configuration in which the inkjet recording heads 30 and 31 are attached so as to sandwich one ultraviolet irradiation unit 60a in the main scanning direction. In this configuration, the ink is ejected from the ink jet recording head in the forward path X1 and cured by irradiating the ultraviolet rays with the ultraviolet irradiating means 60a. Irradiates and cures. In any case, the ultraviolet curable ink discharged from the ink jet recording heads 30 and 31 onto the recording medium 8 can be quickly irradiated with ultraviolet rays, so that the apparatus can be made compact and the number of parts can be reduced to reduce costs. Can be expected.
[0042]
FIG. 8 is an overall perspective view of an ultraviolet curable inkjet recording apparatus according to the second embodiment. Portions indicating the same functions as those of the first embodiment described above are denoted by the same reference numerals, and description of overlapping portions will be omitted.
[0043]
In this example, the ink jet recording head 32 is a line head (full line type ink jet recording head) in which a plurality of ink ejection ports are formed over the entire width of an image forming area that intersects the conveyance direction Y of the recording medium 8. The recording apparatus includes a head plate 12 having a plurality of ink ejection ports capable of ejecting curable ink to the recording medium 8 and an ink tank 22 connected to the head plate and having an independent ink storage unit for each color. It is exchangeably attached to a head fixing portion (not shown) so as to be arranged at a predetermined interval in the medium transport direction.
[0044]
The ultraviolet irradiating means 60c is provided on the downstream side in the transport direction Y of the recording medium 8 so that the ultraviolet curable ink ejected from the ink jet recording head 32 can be irradiated immediately after the ultraviolet curable ink adheres onto the recording medium 8. . The ultraviolet irradiation range of the ultraviolet irradiation means 60c is set to be longer from both ends of the recording area in the arrangement direction of the ejection ports of the ink jet recording head 32, and the length of the ultraviolet irradiation range in the transport direction is determined according to the transport speed. It is set so that the ink adhered on the surface 8 is sufficiently cured while passing through the ultraviolet irradiation range.
[0045]
The recording medium 8 is continuously conveyed in the conveying direction Y, the ink jet recording head 32 is driven and controlled in response to an image signal to discharge ink, and the surface of the recording medium 8 is irradiated with ultraviolet rays by the ultraviolet irradiation means 60c to perform recording. An image is formed on the medium 8.
[0046]
FIG. 9 is a diagram showing the arrangement of the ultraviolet irradiation means 60c and the inkjet recording head 32 as viewed from the direction in which the ejection ports are arranged. The inkjet recording head 32 is arranged so that the central axis of the inkjet recording head 32 is inclined upstream in the recording medium transport direction and the central axis of the ultraviolet irradiation means 60c is inclined downstream in the recording medium transport direction with respect to the perpendicular to the recording medium holding surface. In order to arrange the ultraviolet irradiating means 60c and the inkjet recording head 32 in an inclined manner, for example, a shaft support is provided corresponding to each of the apparatus main bodies and fixed to the shaft support with a screw or the like. Can be fixed, and the inclination angle can be easily adjusted.
[0047]
FIG. 10 is a diagram showing a positional relationship between the inkjet recording head 32 of FIG. 9 and the ultraviolet irradiation means 60c. In the present configuration, since the central axis of the inkjet recording head 32 is arranged so as to be inclined with respect to the perpendicular to the recording medium holding surface, the ink ejected from the inkjet recording head 32 is moved in a direction perpendicular to the recording medium 8. Is discharged to the upstream side in the recording medium transport direction, and it is possible to form a sharp image on the recording medium 8 without image deterioration due to a flying speed difference between the main dot and the satellite. In this case, it is preferable to set the inclination angle according to the continuous conveyance speed of the recording medium 8. Thereby, the continuous conveyance speed of the recording medium 8 can be increased, and the productivity can be improved. Further, it is possible to reduce the time required for the ink ejected from the ink jet recording head 32 and irradiating the ink adhered on the recording medium 8 with the ultraviolet rays, so that the bleeding of the ink adhering to the recording medium 8 is suppressed. be able to. The inclination angle of the inkjet recording head 32 and the ultraviolet irradiation means 60c is preferably in the range of 1 to 30 degrees with respect to the perpendicular to the recording medium holding surface, as in the first embodiment.
[0048]
Examples of the recording medium that can be used in the present invention include ink-absorbing recording media such as paper, cloth, and wood without an ink-receiving layer formed thereon, and ink-absorbing materials such as leather, glass, metal, ceramics, and films. It can also be used for a recording medium without any. Also, a medium having a fluffy surface or a medium having irregularities can be recorded by increasing the distance between the head and the medium.
[0049]
Using the inkjet recording apparatus shown in FIG. 1, L = 50 mm, d ₁ = 10 mm, d ₂ = 6 mm, and a color image was recorded on a fabric (thickness: 2.5 mm) woven with a yarn made of polyester fiber. A continuous recording operation was performed for 240 hours, but no clogging was caused in the inkjet recording head due to ultraviolet curing.
[0050]
【The invention's effect】
With the above configuration, the distance between the inkjet recording head and the ultraviolet irradiation means is defined by the distance from the recording medium holding surface of the holding means as shown in (Equation 1), so that the recording medium having various thicknesses can be recorded. Even so, the effect of ultraviolet rays reflected on the recording medium can be suppressed. That is, since the surface of the recording medium is located at a position closer to the ultraviolet irradiation means than the recording medium holding surface, the ultraviolet light reflected on the recording medium surface is more ultraviolet irradiation means than the ultraviolet light reflected on the recording medium holding surface. If the ultraviolet rays reflected on the recording medium holding surface do not affect the ink jet recording head, the influence can be suppressed even for recording media having various thicknesses. Further, when a plurality of recording media are held on the recording medium holding surface, the recording medium holding surface is exposed from between the recording media, and the ultraviolet light is reflected, or the inkjet recording head is moved to a position separated from both ends of the recording medium. In this case, even when ultraviolet rays are reflected on the recording medium holding surface, the influence can be suppressed.
[0051]
Also, by defining the interval between the inkjet recording head and the ultraviolet irradiation means based on the incident angle of the ultraviolet light at the position closest to the inkjet recording head in the irradiation range of the ultraviolet irradiation means with respect to the recording medium holding surface, the recording medium holding surface It is possible to reliably suppress the influence of the ultraviolet ray which most affects the ink jet recording head among the ultraviolet rays reflected by the light source.
[0052]
As described above, the influence of ultraviolet rays reflected on the surface of the recording medium can be suppressed, so that even if continuous recording is performed for a long time, the discharge ports of the inkjet recording head are not clogged by the ultraviolet rays.
[0053]
Further, since at least one of the ultraviolet irradiation unit and the ink jet recording head is arranged so as to be inclined away from the other opposing surface, the entire distance between the ultraviolet irradiation unit and the ink jet recording head is not increased (formula (1)). The interval L defined in 1) can be set, and the device can be made compact. Further, if the ultraviolet irradiating means is disposed at an angle, the incident angle θ in (Equation 1) can be reduced, and accordingly, the ultraviolet irradiating means can be disposed at a position close to the ink jet recording head. Further, the interval L and the interval d ₁ And the distance d ₂ By providing at least one interval adjusting means for adjusting the intervals, it is possible to adjust the intervals appropriately for various recording media and suppress the influence of ultraviolet rays reflected on the recording medium surface.
[0054]
Also, the interval d ₁ , D ₂ For d ₁ ≧ d ₂ It is preferable that d ₁ <D ₂ In the case of, the interval between the recording medium and the ultraviolet irradiation means must be set with priority to prevent collision, and as a result, the interval between the inkjet recording head and the recording medium must be increased, and The quality will be inferior. And the interval d ₁ Is preferably in the range of 1 to 20 mm. When the distance exceeds 20 mm, the irradiation area of the ultraviolet light reflected on the opposed recording medium increases, and the distance between the inkjet recording head and the ultraviolet light irradiation means has to be increased. As a result, the ink can be effectively cured. This is because it will not be possible. Also, if the thickness is less than 1 mm, the danger of the ultraviolet irradiation means and the ink jet recording head colliding with the recording medium increases.
[0055]
Further, when the ultraviolet irradiation unit and the inkjet recording head are reciprocally moved in the scanning direction as a unit, the ultraviolet irradiation unit is disposed at least one of the front and the rear in the scanning direction with respect to the inkjet recording head, so that the recording medium can be printed. The attached ink can be quickly cured. Further, when the recording medium is moved in a direction orthogonal to the arrangement direction of the ejection ports in the ink jet recording head in which the plurality of ink ejection ports are arranged in a line, the ultraviolet irradiation means is used to move the recording medium with respect to the ink jet recording head. By arranging it on the downstream side in the direction, the ink attached to the recording medium can be quickly cured in the same manner.
[Brief description of the drawings]
FIG. 1 is a schematic perspective view relating to a first embodiment of the present invention.
FIG. 2 is a diagram illustrating a configuration example of an ultraviolet irradiation unit and an inkjet recording head as viewed from a sub-scanning direction.
FIG. 3 is an explanatory diagram relating to a distance between an ultraviolet irradiation unit and an inkjet recording head in FIG. 2;
FIG. 4 is a diagram illustrating another configuration example of the ultraviolet irradiation unit and the inkjet recording head as viewed from a sub-scanning direction.
FIG. 5 is an explanatory diagram relating to a distance between an ultraviolet irradiation unit and an ink jet recording head in FIG. 4;
FIG. 6 is a diagram illustrating another configuration example of the ultraviolet irradiation unit and the inkjet recording head as viewed from a sub-scanning direction.
FIG. 7 is a diagram illustrating another configuration example of the ultraviolet irradiation unit and the inkjet recording head as viewed from a sub-scanning direction.
FIG. 8 is a schematic perspective view relating to a second embodiment of the present invention.
FIG. 9 is a diagram illustrating a configuration example of an ultraviolet irradiation unit and an ink jet recording head as viewed from a recording medium conveyance direction.
FIG. 10 is an explanatory diagram relating to a distance between an ultraviolet irradiation unit and an inkjet recording head in FIG. 9;
FIG. 11 is a diagram illustrating a configuration example of a conventional ultraviolet irradiation unit and an ink jet recording head as viewed from a sub-scanning direction.
FIG. 12 is a diagram illustrating a recording operation of a conventional ultraviolet irradiation unit and an ink jet recording head.
[Explanation of symbols]
10 Head plate
11 Head plate
12 Head plate
20 ink tank
21 Ink tank
22 Ink tank
30 inkjet recording head
31 inkjet recording head
32 inkjet recording head
40 carriage
41 Carriage motor
42 Timing Belt
5 Flat cable
60a UV irradiation means
60b UV irradiation means
70 Recording medium holding means
71 Transport Roll
8 Recording media

Claims (6)

An ink jet recording head that discharges an ultraviolet curable ink toward a recording medium from a plurality of ink discharge ports, an ultraviolet irradiation unit that irradiates the ink adhered to the recording medium with ultraviolet light, and the ink discharge ports according to an image signal. Drive control means for driving and controlling the ink jet recording head so as to selectively eject ink, holding means for holding the recording medium at a recording position, and movement for relatively moving the ink jet recording head and the recording medium In the ink jet recording apparatus having a control means,
The ultraviolet curing type ink jet recording apparatus, wherein the ultraviolet irradiation means is disposed adjacent to the ink jet recording head at a distance L so as to satisfy (Equation 1).
L ≧ (d ₁ + d ₂ ) tan θ (Equation 1)
However,
d ₁ : distance between the surface facing the holding means of the ultraviolet irradiation means and the recording medium holding surface of the holding means d ₂ : distance θ between the surface facing the holding means of the inkjet recording head and the recording medium holding surface θ: holding the recording medium Angle of incidence of ultraviolet light at the position closest to the inkjet recording head in the irradiation range of the ultraviolet irradiation means on the surface 2. The ultraviolet curable ink jet recording apparatus according to claim 1, wherein at least one of said ultraviolet irradiation means and said ink jet recording head is arranged so as to be inclined away from said other opposing surface. The ultraviolet curable ink jet recording apparatus according to claim 1, further comprising an interval adjusting unit for adjusting at least one of the interval L, the interval d _1, and the interval d _2. . Distance _d 1, there _{d 2} is the relation of _{d 1} ≧ _{d 2,} and distance _{d 1} is the ultraviolet ray curable inkjet recording apparatus according to any one of claims 1 to 3, characterized in that the 1 to 20 mm. The movement control unit controls the reciprocating movement of the ultraviolet irradiation unit and the inkjet recording head integrally in the scanning direction, and the ultraviolet irradiation unit is at least one of a front and a rear in the scanning direction with respect to the inkjet recording head. The ultraviolet curable ink jet recording apparatus according to any one of claims 1 to 4, wherein the ultraviolet curable ink jet recording apparatus is arranged at a position (1). The movement control means controls the movement of the recording medium in a direction orthogonal to the arrangement direction of the ejection ports in the ink jet recording head in which a plurality of ink ejection ports are arranged in a line. The ultraviolet curable ink jet recording apparatus according to any one of claims 1 to 4, wherein the ultraviolet curable ink jet recording apparatus is arranged downstream of a head in a moving direction of the recording medium.

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