JP6036091B2 - UV irradiator - Google Patents

Description

  The present invention relates to an ultraviolet irradiator.

  2. Description of the Related Art Conventionally, in a printing machine that prints on a sheet with ultraviolet curable UV ink, an ultraviolet irradiator that irradiates and cures ultraviolet rays on a sheet after UV ink application is provided facing the sheet conveyance path. (For example, refer to Patent Document 1).

JP 2006-297690 A

However, in the conventional printing press, there is a problem that the ultraviolet rays emitted from the ultraviolet irradiator leak from the sheet conveyance path, illuminate the sheet or ink head before printing, and change the quality.
In general, a high-output light source is used in an ultraviolet irradiator of a printing press. For this reason, simply providing a light-shielding plate that blocks leaked light will cause the light-shielding plate to be thermally deformed by the radiant heat of the light source, resulting in a change in the light-shielding range. Also affects.

  This invention is made | formed in view of the situation mentioned above, and aims at providing the ultraviolet irradiation device which can suppress the influence of the leakage light of an ultraviolet-ray.

In order to achieve the above object, the present invention comprises an irradiator main body containing a linear ultraviolet light source, and ultraviolet rays emitted from the ultraviolet light source are emitted from an irradiation opening of the irradiator main body onto a sheet coated with UV ink. The ultraviolet irradiator for irradiating comprises a light shielding means for shielding a part of the ultraviolet light emitted from the irradiation opening , the light shielding means extending in the extending direction of the ultraviolet light source, and the irradiation opening of the irradiator main body. And a light shielding plate that shields ultraviolet rays that illuminate the sheet or ink head before or during application of the ink, and that is hidden by the light shielding plate when viewed from the ultraviolet light source. And a support frame that extends along the light shielding plate and supports the light shielding plate.

  Further, the present invention is characterized in that, in the ultraviolet irradiator, the light shielding plate is a high thermal conductive material that suppresses a temperature difference between the surface of the ultraviolet light source exposed to ultraviolet rays and the back surface thereof. To do.

  In the ultraviolet irradiator, the light shielding plate may be a reflective material that reflects radiant heat of the ultraviolet light source.

  Further, the present invention is characterized in that, in the ultraviolet irradiator, a plurality of holes for pinning the light shielding plate to the support frame are elongated holes extending in a direction allowing deformation of the light shielding plate. To do.

  According to the present invention, in the ultraviolet irradiator, a heat shut-off unit that cuts off heat transfer from the light-shielding plate to the support frame is provided between the light-shielding plate and the support frame.

According to the ultraviolet irradiator of the present invention, since the light shielding plate for shielding the leakage light of the irradiated ultraviolet light is provided, it is possible to prevent the members and parts that should avoid the ultraviolet irradiation from being exposed to the leakage light.
In addition, since the support frame that supports the light shielding plate is arranged at a location hidden behind the light shielding plate when viewed from the ultraviolet light source, the support frame is not exposed to the ultraviolet rays or radiant heat of the ultraviolet light source. For this reason, even when the output of the ultraviolet light source is large, thermal deformation of the support frame due to ultraviolet light or radiant heat can be suppressed. Thereby, since the deformation | transformation and displacement of the light-shielding plate accompanying the thermal deformation of the support frame are suppressed, it is possible to prevent the irradiation range from changing due to such deformation or displacement.

It is a figure which shows a part of structure of the printing machine which has an ultraviolet irradiation device concerning embodiment of this invention. FIG. 2 is an enlarged view of part A including the vicinity of the light shielding unit in FIG. 1. It is a side view which shows the structure of an ultraviolet irradiation device. It is a bottom view of an ultraviolet irradiator. It is a top view of a light-shielding unit. It is VI-VI arrow sectional drawing of FIG. It is VII-VII arrow sectional drawing of FIG. It is an exploded view of a light-shielding unit.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram showing a part of the configuration of a printing press 1 having an ultraviolet irradiator 10 according to the present embodiment.
The printing machine 1 performs printing by discharging an ultraviolet curable UV ink from an ink head (not shown) and applying it to the sheet 4, and irradiating the sheet with ultraviolet U to cure the UV ink. That is, as shown in FIG. 1, the printing machine 1 includes a conveyance unit 5 that conveys a sheet 4 coated with UV ink by an ink head along a conveyance path 5 a, and a UV ink by irradiating the sheet 4 with ultraviolet rays U. And a nitrogen purge box 6 for performing ultraviolet irradiation on the sheet 4 in a nitrogen atmosphere.
In addition to the members shown in FIG. 1, the printing machine 1 includes members included in a normal printing machine such as a storage sheet unit that stocks unprinted sheets 4 before UV ink application. In this figure, although a sheet is shown as the sheet 4, continuous paper such as roll paper may be used.

The conveyance path 5a of the sheet 4 introduces the sheet 4 coated with UV ink into the nitrogen purge box 6, is set in each of the pair of ultraviolet irradiators 10, and each irradiates the sheet 4 with ultraviolet U. It is provided to discharge from the nitrogen purge box 6 via the position P.
The conveyance means 5 conveys the sheet 4 along the conveyance path 5a, and includes a conveyance belt 5b extending along the conveyance path 5a and a plurality of sprockets 8a to 8c that convey the conveyance belt 5b. Have.

  The nitrogen purge box 6 is provided with an introduction opening 6a through which the conveyance path 5a passes and an ultraviolet ray U for irradiating the conveyance path 5a. Further, the inside of the nitrogen purge box 6 is configured such that the periphery of the conveyance path 5a to which the ultraviolet ray U is irradiated is a nitrogen atmosphere, and the ultraviolet irradiation to the sheet 4 is performed in the nitrogen atmosphere. As a result, the UV ink is irradiated with ultraviolet rays in a nitrogen atmosphere, and the curing of the UV ink is promoted and the fixing (drying) of the UV ink is performed more quickly than when ultraviolet rays are irradiated in an atmosphere containing oxygen.

FIG. 2 is an enlarged view of a portion A in FIG. 1, and FIG. 3 is a side view showing the configuration of the ultraviolet irradiator 10. FIG. 4 is a bottom view of the ultraviolet irradiator 10.
The pair of ultraviolet irradiators 10 are configured substantially the same, and include an irradiator body 11 and a light shielding device 20.
As shown in FIG. 3, the irradiator body 11 includes a substantially box-shaped casing 13 that extends long in the sheet width direction E (direction orthogonal to the conveyance direction D) of the sheet 4. A lamp unit 12 that radiates U is provided inside.
The lamp unit 12 includes an ultraviolet discharge lamp 14 that is a linear ultraviolet light source, and a reflecting mirror 16. The ultraviolet discharge lamp 14 is a lamp that constitutes one or a plurality of straight tube-type linear light sources arranged in a straight line, and extends in the sheet width direction E over the entire length of the sheet 4. . The reflecting mirror 16 is an elliptic reflecting mirror that extends along the ultraviolet discharge lamp 14 and surrounds the ultraviolet discharge lamp 14.

  As shown in FIG. 2, the ultraviolet discharge lamp 14 has its tube axis disposed at the first focal point F <b> 1 of the reflecting mirror 16, so that the emitted light of the ultraviolet discharge lamp 14 is condensed at the second focal point F <b> 2 of the reflecting mirror 16. To do. The second focal point F2 is set to be located inside the housing 13 and above the irradiation opening 13a provided on the bottom surface 13t, and the condensed light of the second focal point F2 spreads from the irradiation opening 13a. Irradiated as ultraviolet light U.

In order to suppress a loss when the ultraviolet ray U is incident on the nitrogen purge box 6 from the irradiator main body 11, the irradiator main body 11 has an irradiation opening 13a and an introduction opening 6a of the nitrogen purge box 6 as shown in FIG. And facing each other so that the gap α becomes narrow.
Thereby, the ultraviolet rays U irradiated from the irradiator main body 11 are efficiently guided to the nitrogen purge box 6, and are irradiated over the entire conveyance path 5 a in the sheet width direction E and along the conveyance direction D over a wide range.

The ultraviolet discharge lamp 14 of the ultraviolet irradiator 10 uses a high output type lamp (for example, a mercury lamp) in order to increase the curing rate of UV ink and improve the printing throughput. The irradiator body 11 is provided with an air cooling mechanism for air-cooling the high-power ultraviolet discharge lamp 14 to stably light it.
Specifically, as shown in FIG. 2, the casing 13 of the irradiator body 11 is configured to be airtight by closing the irradiation opening 13 a with a glass plate 17, and on the top surface of the casing 13. A blower duct 15a and an exhaust duct 15b are connected. A blower fan (not shown) is connected to the blower duct 15a, and cooling air is sent from the outside into the housing 13 by the blower operation of the blower fan. Cooling air cools the ultraviolet discharge lamp 14 and the reflecting mirror 16 while circulating inside the housing 13, and is discharged from the exhaust duct 15b.

  The light shielding device 20 shields the leakage light Ua of the ultraviolet light U irradiated by the irradiator body 11 and is provided so as to cover the irradiation opening 13 a from the outside of the housing 13. Leakage light Ua is a light component that deviates from a predetermined irradiation range, and in this printing press 1, a portion that is outside the irradiation range set in advance at the irradiation position P of ultraviolet U and where ultraviolet irradiation should be avoided is disposed. The light traveling toward S (FIG. 2) becomes leakage light Ua. As a member which should avoid ultraviolet irradiation, the sheet | seat 4 before printing or the middle, an ink head (not shown), etc. are mentioned, for example. That is, when the leakage light Ua is applied to the sheet 4 before or during printing, the sheet 4 deteriorates or the print quality deteriorates, and when the leakage light Ua is applied to the ink head, the UV ink is cured and the ink Clogging may occur.

In particular, in this printing machine 1, since the ultraviolet light U is spread over a wide range at the irradiation position P, the leakage light Ua is likely to be generated, and since the output of the ultraviolet light U is high, the influence of the leakage light Ua is large.
Therefore, in the printing machine 1, as described above, the light blocking device 20 is provided in the irradiation opening 13a of the irradiator main body 11, thereby blocking the leakage light Ua. However, depending on the configuration of the printing press, the layout of the irradiator main body 11, and the output of the ultraviolet rays U, there is a case where measures against leakage light are unnecessary. Therefore, the light shielding device 20 is attached to the outside of the irradiator body 11 by retrofitting so that the light shielding device 20 can be appropriately installed according to the necessity of countermeasures against leakage light.

That is, as shown in FIGS. 2 to 4, the light shielding device 20 includes an apparatus housing 21 and a light shielding unit 23 provided in the device housing 21. As shown in FIG. 2, the device housing 21 is a box that has an upper surface opened and is fitted and fixed to the bottom surface 13 t of the housing 13 of the irradiator body 11. On the bottom surface 21t of the apparatus housing 21, as shown in FIG. 4, an ultraviolet light passage window 21a that is an opening having a size including the irradiation opening 13a is formed at a position corresponding to the irradiation opening 13a of the irradiator body 11. The ultraviolet ray U irradiated from the irradiation opening 13a is irradiated to the irradiation position P of the printing press 1 through the ultraviolet ray through window 21a.
The height of the apparatus housing 21 is limited to a height that can be accommodated in the gap α between the irradiator body 11 and the nitrogen purge box 6, and the irradiator body 11 can be changed without changing the arrangement of the irradiator body 11. Can be retrofitted.

The light shielding unit 23 is a light shielding means that is disposed between the irradiation opening 13a and the ultraviolet ray passage window 21a and shields part of the ultraviolet light U radiated from the irradiation opening 13a, that is, leakage light Ua. In this printing machine 1, as shown in FIG. 2, the ultraviolet light U which goes out of the irradiation position P and goes upstream along the transport direction D becomes leakage light Ua.
The light shielding unit 23 spans from one end 24a to the other end 24b in the longitudinal direction (sheet width direction E, that is, the extending direction of the ultraviolet discharge lamp 14) of the ultraviolet light passing window 21a so as to shield the leaked light Ua. 35. The light leakage plate Ua shields the leakage light Ua.

Here, as shown in FIG. 2, since the light shielding device 20 is arranged at a position closer to the irradiation position P from the irradiation opening 13 a of the irradiator body 11, a slight positional deviation occurs in the light shielding plate 35. As a result, the ultraviolet irradiation at the irradiation position P is greatly affected.
In particular, in this printing machine 1, since the ultraviolet discharge lamp 14 having a high output enough to require internal air cooling is used as the ultraviolet light source, the light-shielding unit 23 uses the ultraviolet light (leakage light Ua) and radiant heat (far away) of the ultraviolet discharge lamp 14. There is a risk of thermal deformation due to infrared rays or the like. In addition, since the light shielding unit 23 is long in the sheet width direction E as shown in FIG. 3, the light shielding device 20 is subjected to a large load on the central portion C in the longitudinal direction and is coupled downward with the influence of heat. Deformation is likely to occur.
Therefore, in the present embodiment, the light shielding unit 23 is configured so that the ultraviolet irradiation at the irradiation position P is hardly affected even if the ultraviolet discharge lamp 14 is affected by heat, and the configuration will be described in detail below. .

5 is a plan view of the light shielding unit 23, FIG. 6 is a sectional view taken along the arrow VI-VI in FIG. 5, FIG. 7 is a sectional view taken along the arrow VII-VII in FIG. .
The light shielding unit 23 includes a support frame 25 and a spacer 30 in addition to the light shielding plate 35. The support frame 25 is a support material for supporting the light shielding plate 35 along the longitudinal direction of the ultraviolet light passing window 21a. In this embodiment, a single columnar member having no joint is used. The spacers 30 are fixed to the support frame 25 at predetermined intervals along the longitudinal direction, and support the light shielding plate 35 at a position separated from the support frame 25.

As described above, the light shielding plate 35 is a plate member having a rectangular shape in a plan view extending from one end 24a to the other end 24b of the ultraviolet light passage window 21a of the light shielding device 20.
As shown in FIG. 5, the light-shielding plate 35 is configured by connecting a plurality of rectangular plate pieces 36 and 37 in the longitudinal direction, as shown in FIG. The plate pieces 36 and 37 have a reflection characteristic of reflecting the radiant heat (far infrared rays or the like) of the ultraviolet discharge lamp 14 and are made of a material such as aluminum having high thermal conductivity. Since the plate pieces 36 and 37 reflect the radiant heat, the ultraviolet discharge lamp 14 is prevented from being heated by the radiant heat.
Moreover, since it has high thermal conductivity, the temperature of the surface of the plate pieces 36 and 37 on the side exposed to the leaked light Ua and radiant heat rises, and it is difficult for a temperature difference to occur between the back and back surfaces. Deformation such as warpage due to the temperature difference is prevented.

  However, when ultraviolet irradiation is performed for a long time, heat due to leakage light Ua or radiant heat is accumulated on the plate pieces 36 and 37 of the light shielding plate 35 and may be thermally deformed. In this case, if the thermal deformation of the light shielding plate 35 is the longitudinal direction of the ultraviolet light passing window 21a (that is, the direction in which the light shielding plate 35 is bridged), the light shielding range of the light shielding plate 35 in the ultraviolet light passing window 21a does not change. Thermal deformation of the light shielding plate 35 to the outside is allowable. Therefore, the light shielding unit 23 is configured such that the thermal deformation of the light shielding plate 35 is limited only in the longitudinal direction (that is, the sheet width direction E).

Specifically, as shown in FIG. 5, the light shielding plate 35 is configured such that the plate pieces 36 are arranged at regular intervals, and the end portions of the plate pieces 36 are covered with the plate pieces 37 from above and overlapped. The pins 41 are connected to each other by passing through the pins 41 and pinning. In the plate pieces 36 and 37, the holes through which the pins 41 pass are formed as long holes 38 that are long in the sheet width direction E, which is the longitudinal direction.
The spacers 30 are disposed under the respective long holes 38, and the pins 41 penetrating the long holes 38 cannot be moved relative to the round holes 31 of the spacers 30 by the retaining rings 42 as shown in FIGS. Fixed to.
With this configuration, the thermal deformation of the plate pieces 36 and 37 is limited to the direction along the long hole 38 with the pin 41 as a fixing point, that is, the longitudinal direction of the light shielding plate 35.

In addition to this, as shown in FIGS. 6 to 8, the plate pieces 36 and 37 are formed in a substantially U-shaped cross section by including side pieces 36 a and 37 b whose both edges are bent in an L shape. . As a result, the rigidity in the cross section perpendicular to the longitudinal direction, that is, the rigidity in the transport direction D and the vertical direction is increased, and the deformation in the direction other than the longitudinal direction is less likely to occur.
Further, as described above, each of the plate pieces 36 and 37 is made of a high thermal conductivity material, so that deformation such as warpage due to a temperature difference between the front and back surfaces is less likely to occur. This deformation is more reliably limited only to the longitudinal direction.

  6 to 8, reference numeral 43 denotes a washer, and the plate pieces 36 and 37 are pinned to the support frame 25 (more precisely, the spacer 30) by the washer 43, the pin 41 and the retaining ring 42. A fixing means 40 for fastening and fixing is configured. Further, the bent pieces 45 provided at the ends of the side pieces 36a and 37b of the plate pieces 36 and 37 contribute to the extension of the light shielding range.

By the way, if the support frame 25 supporting the light shielding plate 35 is distorted due to thermal deformation, the light shielding plate 35 is also distorted by this distortion, and the ultraviolet irradiation at the irradiation position P is affected.
Therefore, in this light shielding unit 23, as shown in FIG. 7 and FIG. 8, it is hidden by the light shielding plate 35 as viewed from the ultraviolet discharge lamp 14 as shown in FIG. The support frame 25 is arranged at the location.
Thereby, since the support frame 25 is not directly exposed to the ultraviolet rays U, leakage light Ua, and radiant heat, heating of the support frame 25 by these is suppressed, and thermal deformation is suppressed.

However, when heat is stored in the light shielding plate 35 supported by the support frame 25, the support frame 25 is heated by heat transfer from the light shielding plate 35 because heat is stored, and eventually thermal deformation occurs. It tends to occur.
Therefore, in the light shielding unit 23, the spacer 30 is interposed between the support frame 25 and the light shielding plate 35, and heat transmission from the light shielding plate 35 to the support frame 25 is blocked by the spacer 30.

As shown in FIGS. 6 to 8, the spacer 30 is a metal fitting formed by bending a rectangular plate material into a U-shaped cross section and providing side pieces 32 on both sides. As shown in FIG. 8, the spacer 30 is sandwiched between a pair of side pieces 32 from above, and these side pieces 32 are fastened to the support frame 25 with bolts 34 and nuts 33 and fixed. The light shielding plate 35 is placed on the upper surface 30 </ b> A from above the spacer 30 and fixed by the fixing means 40.
At this time, as the contact area between the upper surface 30A and the light shielding plate 35 increases, the heat conduction from the light shielding plate 35 to the spacer 30 increases, so that the spacer 30 extends in the longitudinal direction of the support frame 25 as shown in FIG. It does not extend, but is scattered in positions corresponding to the connecting portions of the plate pieces 36 and 37.

As shown in FIGS. 6 and 7, the spacer 30 is attached to the support frame 25 with a gap β between the upper surface 30 </ b> A and the support frame 25. Due to the gap β, an air layer is formed between the upper surface 30A of the spacer 30 and the support frame 25 to inhibit heat transfer from the light shielding plate 35 placed on the upper surface 30A to the support frame 25.
The spacer 30 is formed of a low thermal conductivity material such as SUS, which has a lower thermal conductivity than the light shielding plate 35, and prevents heat from being transmitted from the light shielding plate 35 to the support frame 25 through the spacer 30. doing.
As described above, since the thermal coupling between the support frame 25 and the light shielding plate 35 is blocked by the spacer 30, the support frame 25 is prevented from being thermally deformed due to the thermal influence of the light shielding plate 35.

Further, as described above, the support frame 25 is configured by using one columnar member manufactured by extrusion molding or the like, and since there is no joint in the longitudinal direction, the joint hangs down by its own weight. Such deformation is prevented.
In addition to this, as shown in FIGS. 6 to 8, the support frame 25 has a cross-sectional structure in which an outer frame piece 28 is supported by an arm 27 around each of the pair of columnar bases 26 and hangs down by its own weight. It is rigid to the extent that does not occur.
As a result, even when the ultraviolet light source has a high output and even when the sheet width direction E is long, the support frame 25 can be prevented from being deformed by the heat and by its own weight. Then, by supporting the light shielding plate 35 on the support frame 25 having no deformation as described above, the deformation of the light shielding plate 35 due to the deformation of the support frame 25 can be suppressed. The desired leakage light Ua can be reliably shielded without any influence.

As described above, according to the present embodiment, the following effects can be obtained.
That is, according to the ultraviolet irradiator 10 of the present embodiment, the light shielding device 20 having the light shielding unit 23 is provided, and the light shielding unit 23 shields the leakage light Ua of the ultraviolet light U irradiated from the irradiator body 11. Since it was set as the structure provided with 35, irradiation of the leak light Ua to the location S which should avoid ultraviolet irradiation can be prevented.
In addition, in the present embodiment, the light shielding unit 23 includes a support frame 25 that supports the light shielding plate 35, and the support frame 25 is disposed at a location hidden by the light shielding plate 35 when viewed from the ultraviolet discharge lamp 14.
With this configuration, since the support frame 25 is not directly exposed to the ultraviolet ray U (leakage light Ua) or radiant heat of the ultraviolet discharge lamp 14, even when the output of the ultraviolet discharge lamp 14 is large enough to require air cooling, Thermal deformation of the support frame 25 due to ultraviolet rays U and radiant heat is suppressed. Thereby, the deformation of the light shielding plate 35 due to the thermal deformation of the support frame 25 is suppressed, and the desired leakage light Ua can be reliably shielded without affecting the ultraviolet irradiation at the irradiation position P.

Further, according to the present embodiment, the light shielding plate 35 is made of a highly thermally conductive material that suppresses a temperature difference between the surface of the ultraviolet discharge lamp 14 on the side exposed to the ultraviolet rays U (leakage light Ua) and the back surface thereof. Configured.
Thereby, deformations such as warpage due to the temperature difference between the front and back surfaces of the light shielding plate 35 are suppressed.

  Furthermore, according to this embodiment, since the light shielding plate 35 is made of a reflective material that reflects the radiant heat of the ultraviolet discharge lamp 14, heat accumulation on the light shielding plate 35 due to this radiant heat is reduced, and thermal deformation is unlikely to occur. .

Further, according to the present embodiment, the plurality of holes for pinning the light shielding plate 35 to the support frame 25 extend in a direction allowing deformation of the light shielding plate 35 (the sheet width direction E in the present embodiment). A long hole 38 is used.
Thereby, even if thermal deformation occurs in the light shielding plate 35, the deformation can be limited to a direction allowed in advance, that is, a direction that does not affect the ultraviolet irradiation at the irradiation position P.

In addition, according to the present embodiment, the spacer 30 is provided between the light shielding plate 35 and the support frame 25 as a heat shielding unit that blocks heat transfer from the light shielding plate 35 to the support frame 25.
Thereby, since the support frame 25 is not heated through the light shielding plate 35, it is possible to prevent thermal deformation of the support frame 25 and to prevent deformation of the light shielding plate 35 due to deformation of the support frame 25.

  The above-described embodiment is merely an example of one aspect of the present invention, and can be arbitrarily modified and applied without departing from the spirit of the present invention.

For example, in the above-described embodiment, the light shielding plate 35 is exemplified by the configuration extending from the one end 24a to the other end 24b of the ultraviolet light passage window 21a, but is not limited thereto.
That is, the light shielding plate 35 is formed in a shape and a size corresponding to the leaked light Ua to be shielded, and is disposed in the ultraviolet light passing window 21a so that the leaked light Ua can be shielded. At this time, the light shielding plate 35 is spanned so as to cross the ultraviolet light passing window 21 a, and the spanned direction is a direction allowing deformation of the light shielding plate 35.

Further, for example, a reflective film may be formed on the surface of the light shielding plate 35 to provide a reflection characteristic for reflecting radiant heat.
Further, for example, the ultraviolet irradiator 10 has been described as being incorporated in the printing machine 1 that cures the UV ink printed on the sheet 4, but of course the present invention may be incorporated in a device that irradiates ultraviolet rays for other purposes. Is applicable.

DESCRIPTION OF SYMBOLS 10 Ultraviolet irradiation device 11 Irradiator main body 12 Lamp unit 13a Irradiation opening 14 Ultraviolet discharge lamp (ultraviolet light source)
16 Reflector 20 Light-shielding device 21a Ultraviolet light passage 23 Light-shielding unit (light-shielding means)
25 Support frame 30 Spacer (heat blocking means)
35 Light-shielding plate 38 Long hole D Conveying direction E Sheet width direction P Irradiation position U Ultraviolet light Ua Leakage light

Claims (5)

In an ultraviolet irradiator that includes an irradiator main body containing a linear ultraviolet light source, and that irradiates the ultraviolet rays emitted from the ultraviolet light source from an irradiation opening of the irradiator main body on a sheet coated with UV ink .
A light shielding means for shielding a part of the ultraviolet rays irradiated from the irradiation opening ,
The shading means is
A light-shielding plate that extends in the extending direction of the ultraviolet light source, radiates from an irradiation opening of the irradiator main body, deviates from a predetermined irradiation range, and shields the ultraviolet rays that illuminate the sheet or ink head before or during application of the ink When,
An ultraviolet irradiator , comprising: a support frame that is disposed at a location hidden from the light shielding plate when viewed from the ultraviolet light source, extends along the light shielding plate, and supports the light shielding plate.   2. The ultraviolet irradiator according to claim 1, wherein the light shielding plate is made of a highly thermally conductive material that suppresses a temperature difference between a surface of the ultraviolet light source exposed to ultraviolet rays and a back surface thereof.   The ultraviolet irradiator according to claim 1 or 2, wherein the light shielding plate is made of a reflective material that reflects radiant heat of the ultraviolet light source.   The plurality of holes for pinning the light shielding plate to the support frame are elongated holes extending in a direction allowing deformation of the light shielding plate. UV irradiator.   5. The ultraviolet irradiator according to claim 1, further comprising a heat blocking unit that blocks heat transfer from the light blocking plate to the support frame between the light blocking plate and the support frame.

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