Light irradiation apparatus and inkjet printer

Light irradiator and inkjet printer

The present invention relates to a light irradiator and an inkjet printer, and in particular to a light irradiator that forms a linear elongated light irradiation area on a light-irradiated object and irradiates the light, and is equipped with the light irradiator to cure the light-curing ink An inkjet printer that spit out the recording medium to record the image on the recording medium.

Nowadays, for example, the inkjet recording method is used in various printing fields such as photographs, various printings, markings, special printings of color filters, etc. because of the simple and inexpensive image formation by the gravure printing method.

In the inkjet printer using this inkjet recording method, by appropriately combining the recording head that discharges and controls fine dots, the color reproduction area, durability, and discharge accuracy of the ink are improved; the ink is greatly improved Special paper with absorbency, color development, surface gloss, etc., can form high-quality images.

Inkjet printers can generally be classified according to the type of ink used. For example, a photocurable inkjet method that uses a curable ink that is cured by irradiating light such as ultraviolet rays is well known (see, for example, patents). Documents 1 to 3, Non-Patent Document 1).

The light-curing inkjet method has low odor. In addition to special paper, it can also be used for quick-drying and non-ink-absorbent recording media.

This type of inkjet printer using the photocurable inkjet method, as shown in FIG. 13, has a head 70, which mounts a recording head 71 and two light irradiators 80A, 80B on a carriage 72. The recording head 71 is provided with nozzles (not shown) that make fine droplets of, for example, ultraviolet curable ink and discharge them onto the recording medium R. Two light irradiators 80A and 80B are installed in the recording medium. For example, the positions on both sides of the head 71 irradiate the ink sprayed on the recording medium R with ultraviolet rays to harden it.

The head 70 is supported by a rod-shaped guide rail 75, and can reciprocate along the guide rail 75 to a position above the recording medium R by a drive mechanism not shown. The guide rail 75 is provided to extend along the recording medium R.

As the ultraviolet curable ink used, for example, a radical polymerization ink containing a radical polymerizable compound as a polymerizable compound, a cationic polymerization ink containing a cation polymerizable compound as a polymerizable compound, etc. can be mentioned. Among these inks, radical polymerization inks are the mainstream.

The respective light irradiators 80A and 80B are composed of a box-shaped cover member 81 having a light emission outlet 81A that opens in the direction in which the recording medium R is located (the downward direction in FIG. 13). Inside the cover member 81, the long-arc discharge lamp 82 forming a linear light source is arranged in a direction orthogonal to the moving direction of the head 70, extends parallel to the recording medium R, and is positioned at the light-emitting outlet 81A. At a position on the rear side of the discharge lamp 82, a trough-shaped reflector 83 having an elliptical reflecting surface 83A that reflects the light emitted by the discharge lamp 82 is installed at a position where the discharge lamp 82 is located at its first focal point Fr1 It extends along the discharge lamp 82 in the state.

As the discharge lamp 82, for example, a high-pressure mercury lamp or a metal halide lamp is used, and the length of the light-emitting part is made such that the size (width dimension) of the recording medium R in the moving direction of the head 70 is large.

In the above-mentioned inkjet printer, the head 70 is arranged such that the recording medium R is located at or near the second focal point Fr2 of the convex portion 83 of the light irradiators 80A, 80B, and is caused by, for example, the discharge lamp 82 is lit. The head 70 is moved above the recording medium R, so that the light from the discharge lamp 82 irradiates the recording medium R located at the second focal point Fr2 of the reflector 83 in a linear state, thereby causing the light to be ejected. The ultraviolet curable ink attached to the recording medium R is cured.

When specifically describing the curing treatment of the ultraviolet curable ink (the ultraviolet radiation treatment performed on the ultraviolet curable ink), in FIG. 13, when the head 70 moves to the right direction while printing on the recording medium R, it is already The ultraviolet curable ink sprayed on the recording medium R is cured by the irradiated light from the light irradiator 80A located on the rear side of the head 70 in the moving direction, and when the head 70 is in the same FIG. 13 When printing on the recording medium R while moving to the left, the ultraviolet curable ink that has been sprayed onto the recording medium R is received from the other light irradiator 80B located behind the head 70 in the moving direction Hardened by irradiating light.

[Patent Document 1] Japanese Patent Application Publication No. 2005-246955 [Patent Document 2] Japanese Patent Application Publication No. 2005-103852 [Patent Document 3] Japanese Patent Application Publication No. 2005-305742

[Non-Patent Document 1] Noguchi Hiromichi, Orikasa Teruo, "Trends in UV Inkjet Printing", Journal of the Graphic Society of Japan, 2003, Vol. 40, No. 3 p.32-46

In recent years, with the desire for higher image quality of inkjet printers using the above-mentioned photocurable inkjet recording method, it is required to perform ink curing treatment more quickly. The reason is as follows.

That is, as shown in Non-Patent Document 1, for example, radical polymerization inks have the property of being exposed to oxygen to reduce the concentration of free radicals. Therefore, the longer the ink is exposed to the atmosphere, the faster the curing speed becomes. Slow, it takes a long time to harden the ink. In addition, the ink used in inkjet printers must have a certain degree of low viscosity in order to be smoothly discharged from the nozzles of the recording head. Therefore, after the ink has been sprayed on the recording medium, the ink is not In the case of immediate curing (photopolymerization), the dot shape of the ink after ejection is likely to change, making it impossible to obtain high-quality images.

In response to this expectation, it may be considered that the polymerization reaction can proceed rapidly by increasing the peak illuminance of light irradiated by a light irradiator, for example.

For example, in the aforementioned Non-Patent Document 1, it is shown that the use of a high-illuminance lamp can reduce the degree of decrease in ink curing speed caused by oxygen, that is, by rapidly curing the ink, it is possible to prevent painting. The quality is reduced, and it is shown that it is possible to form a light irradiation area of the same size as that of, for example, a long arc type discharge lamp, and the effectiveness of a microwave UV lamp with higher illuminance than that of a long arc type discharge lamp can be obtained. The peak illuminance of the microwave UV lamp shown in Non-Patent Document 1 is, for example, 1000 to 1200 mW/cm²about.

In addition, in Patent Document 2 mentioned above, it is shown that a cylindrical lens is arranged between the light source lamp and the recording medium, and the light from the light source lamp is condensed and irradiated to the recording medium to improve the exposure to the medium. The technique of peak illuminance of the irradiated light.

However, even in the case of using optical elements such as lenses or reflectors to condense and illuminate the light from the light source lamp, if the brightness of the light source lamp itself cannot be improved, the peak illuminance obtained will be affected. limited.

In addition, even in the case of using microwave UV lamps, similarly, in order to obtain a sufficiently high illuminance that can meet the aforementioned expectations, it is necessary to increase the brightness of the microwave UV lamp itself, but in fact, it is necessary to further increase the long arc of the light-emitting part. The brightness of type lamps or microwave UV lamps is technically very difficult.

In addition, the inkjet printer as described above further has the following problems. That is, for example, in a conventional inkjet printer having the structure shown in FIG. 13, the structure is such that the light emission outlets 81A of the light irradiators 80A and 80B and the light emission outlets 83A of the reflector 83 are opposed to each other and open in the same way. The direction, that is, the light from the discharge lamp 82, which includes light from the visible region to the infrared region, which is unnecessary when curing the ultraviolet curable ink, directly irradiates the recording medium R, and is accompanied by the discharge lamp 82 lighting The radiant heat is also injected into the recording medium R, so it is affected by light and radiant heat from the visible region to the infrared region, so that the recording medium R is heated and becomes a high temperature.

As the recording medium R, since paper, resin, film, etc., which are susceptible to deformation due to heat are used in most cases, there is a problem in that, in order to perform the curing treatment of ultraviolet curable ink with high efficiency , And when a discharge lamp that can obtain a high peak illuminance is used, the degree of thermal influence of unnecessary light from the visible region to the infrared region or the radiant heat of the discharge lamp on the recording medium R becomes greater, and the temperature of the recording medium R becomes The higher the state, as a result, it becomes easy to produce deformation, etc., and it is difficult to form a high-quality image.

For such a problem, it can be considered that a vapor-deposited mirror (or a mirror) formed between the discharge lamp and the recording medium that reflects only light of a wavelength necessary for ink curing and transmits light other than that wavelength Called cold mirror), only the light reflected by this mirror is irradiated to the recording medium, thereby reducing the influence of heat on the recording medium.

However, in the case of disposing such a reflector, the length of the optical path from the discharge lamp to the recording medium becomes longer. Therefore, in the case of a long arc discharge lamp, for example, it cannot condense the light in the long direction of the discharge lamp, so the light is irradiated The area (light-irradiated area) becomes larger, resulting in lower light utilization efficiency, and it becomes impossible to obtain a sufficient height of illuminance on the light-irradiated surface.

As described above, in fact, in an inkjet printer using a photocurable inkjet method, the peak illuminance of the irradiated surface can be increased by using the light source lamp itself with high brightness, and it is impossible to improve the ink curing process.

The present invention was developed in view of the above circumstances, and its purpose is to provide an inkjet printer that can efficiently harden the ink, so that it can reliably form high-quality images and heat An inkjet printer with a small degree of influence on the recording medium.

<p>The inventors carefully reviewed the results of the research and found that the above-mentioned problems were solved by creating the following structure, and completed the present invention. That is, as the light source lamp, a short arc type with a longer arc type discharge lamp with higher brightness is used A discharge lamp is provided with an optical system of a specific reflecting member that condenses the light from the discharge lamp into a linear shape and then irradiates it.</p><p>That is, the light irradiator of the present invention is characterized by comprising: a short-arc discharge lamp in which a pair of electrodes are arranged opposite to each other in a discharge vessel; and a reflecting member for reflecting light from the discharge lamp. The reflecting member condenses the light from the aforementioned discharge lamp to extend into a linear shape to form a light-irradiated area.</p><p>In the light irradiator of the present invention, the light from the discharge lamp can be condensed into a linear shape and irradiated by forming any of the structures (a) or (b) shown below.</p><p>(a) A reflector configured to surround the discharge lamp and reflect the light from the discharge lamp is used to constitute a reflecting member, which is used as a reflector; when setting the three-dimensional rectangular coordinate system with its optical axis as the X axis, The reflecting surface of the cross section of the XY plane is elliptical, and the reflecting surface of the cross section of the XZ plane is parabolic.</p><p>(b) By configuring a reflector that surrounds the discharge lamp and reflects the light from the discharge lamp: and a reflector that has a cylindrical reflecting surface that reflects the light reflected by the reflector and focuses only on one axis, Construct a reflective member.</p><p>As a specific example of such a structure, the following structures can be cited: (1) A reflecting surface having a rotating parabolic surface centered on its optical axis is used as a reflector, and a reflecting surface having a parabolic cross-section is used as a reflector. As a reflector; (2) Use a reflector with a rotating elliptical surface centered on its optical axis as a reflector, and use a reflector with an elliptical cross-section as a reflector.</p><p>In addition, the light irradiator of the present invention is provided with a plurality of light source units composed of short arc type discharge lamps and reflectors. The light source unit is arranged to surround the discharge lamp and reflect the light from the discharge lamp, and the light source unit is arranged so that at least a part of the light source irradiation area of the light source units adjacent to each other overlaps on the light irradiation surface.</p><p>The inkjet printer of the present invention is provided with a head. The head has a recording head for ejecting photocurable ink to a recording medium and a light for irradiating the ink to harden the ejected ink attached to the recording medium. The light irradiator, by moving the head relative to the recording medium, ejects ink from the recording head to the recording medium, and irradiates the ink sprayed on the recording medium with light. An inkjet printer that hardens the ink and records an image is characterized by using the above-mentioned light irradiator as the light irradiator.</p>

<p>According to the light irradiator of the present invention, by using a short-arc discharge lamp as the light source lamp, an optical system of a specific reflective member is formed, and it is possible to suppress the spread of the light irradiation area of the light irradiation surface with the optical path length. The light from the short-arc discharge lamp forming the point light source is condensed to extend linearly in any direction of the light irradiation surface, so the light from the discharge lamp can be effectively used, and because the brightness of the discharge lamp itself is high, Therefore, a high peak illuminance can be obtained on the illuminated surface.</p><p>In addition, by forming a structure in which the light from the light source lamp is reflected and emitted with a reflective member, for example, when the light in the ultraviolet region is emitted, the light emitted from the discharge lamp is included in the light from the visible region to the infrared region and the accompanying The radiant heat of the lighting of the discharge lamp will not directly enter the light irradiated object, and the degree of heat influence on the light irradiated object can be minimized.</p><p>According to an inkjet printer equipped with the above-mentioned light irradiator, the light from the discharge lamp irradiates the photo-curable ink that has been sprayed onto the recording medium with high illuminance, so it can be efficiently removed The ink sprayed on the recording medium is cured (photopolymerized), and the time required for curing can be shortened. As a result, the dot shape can be prevented from changing, and therefore, a high-quality image can be reliably formed. In addition, especially in the case of using ultraviolet curable ink, the recording medium is irradiated by reflecting the light from the discharge lamp, so that the light from the visible region to the infrared region and the accompanying light are included in the light emitted by the discharge lamp. The radiant heat from the lighting of the discharge lamp does not directly enter the light-irradiated object, so the degree of influence of heat on the light-irradiated object can be minimized, and the deformation of the recording medium can be prevented.</p><p>In addition, according to the present invention, the light irradiator (lamp) can be made smaller and lighter than a long-arc discharge lamp. Therefore, the weight of the entire inkjet printer can be reduced, and It is possible to increase the printing speed due to the increase in the efficiency of the hardening treatment of the ink.</p>

&lt;First Embodiment&gt;

The light irradiator according to the first embodiment of the present invention is provided with: at least one light source unit composed of a short-arc discharge lamp and a reflector that reflects light from the discharge lamp; and the reflection is irradiated by the light source unit The reflecting mirror that emits the light from the discharge lamp uses a specific reflecting member composed of a reflector and a reflecting mirror to condense the light from the discharge lamp into a linearly extending light irradiation area on the irradiated surface. Irradiated.

Fig. 1 is a cross-sectional view schematically showing a partial structure of an example of a light irradiator according to the first embodiment of the present invention.

This light irradiator 10 is provided with an exterior cover 11, the entire exterior cover 11 is, for example, substantially box-shaped, and has a light emission outlet 11A opening on one side (downward in FIG. 1), and is arranged in the exterior cover 11 There is a light source unit 15 provided with a short-arc discharge lamp 12 and a reflector 13 arranged to surround the discharge lamp 12 and reflect the light from the discharge lamp 12, and is arranged to reflect the light from the light source unit 15 and then pass the light The exit 11A is projected to the outside mirror 17.

The reflector 13 constituting the light source unit 15 is constituted by a dish-shaped mirror having a reflecting surface 13A of a parabola of revolution centered on the optical axis C, and is arranged in a posture in which the optical axis C and the light irradiation surface W extend in parallel. The light irradiating port 13B of the reflector 13 is opened in a direction different from the light irradiating port 11A of the light irradiator 10, for example, in the right direction in FIG. 1.

The discharge lamp 12 constituting the light source unit 15 is composed of an ultra-high pressure mercury lamp that can effectively emit ultraviolet light with a wavelength of, for example, 300 to 450 nm. In the discharge vessel, a pair of electrodes is in a state where the distance between the electrodes is, for example, 0.5 to 2 mm. They are arranged in opposite directions, and the mercury of the luminescent material, the rare gas of the buffer gas for starting assist, and the halogen are respectively enclosed in a predetermined amount. Here, the enclosed amount of mercury is, for example, 0.08~0.30mg/mm³。

This discharge lamp 12 is arranged so that a straight line connecting a pair of electrodes extends along the optical axis C of the reflector 13 in a state where the light-emitting portion (for example, the bright spot of the arc) is located at the focal point Fr of the reflector 13.

The reflecting mirror 17 has a parabolic reflecting surface with only one axis, that is, the plane containing the optical axis C of the reflector 13 and the optical axis D of the reflecting mirror 17, which is the cross-section of the plane along the light emission direction. 17A is composed of a parabolic trough-shaped cylindrical dish mirror, and the reflecting surface 17A is arranged to face the light irradiation port 13B of the light source unit 15 and the light exit 11A of the light irradiator 10, and is located on the light irradiation surface W at the focal point Fm It extends along the light irradiation surface W (in FIG. 1, along the direction perpendicular to the paper surface) in the state in the region facing the light exit 11A.

Here, the light irradiator 10 reflects the light radiated from the discharge lamp 12 with a reflecting surface 13A having a paraboloid shape to form parallel light along the optical axis C, and irradiates the light toward the reflector 17 through the light irradiating port 13B , And then the parallel light that has entered the mirror 17 is reflected by the reflective surface 17A of the parabolic cylindrical cross-section of the mirror 17, so that the parallel light will not be condensed on the length of the mirror 17 in the state of parallel light. Direction (in FIG. 1, along the direction perpendicular to the paper surface), while focusing on the optical axis direction of the reflector 13 (in the left and right direction in FIG. 1), the light is emitted through the light exit 11A, thereby , The light from the discharge lamp 12 is irradiated so that the light irradiation area W located at the focal point Fm of the reflector 17 forms a light irradiation area IA extending linearly in the longitudinal direction of the reflector 17.

If the light irradiator 10 according to the above-mentioned structure is adopted, the short-arc discharge lamp 12 is used as the discharge lamp, and the reflector 13 and the reflector having reflecting surfaces 13A and 17A of specific shapes are combined. The optical system of the specific reflecting member formed by 17 makes it possible to suppress the diffusion of the light irradiation area IA formed on the light irradiation surface W as the optical path length increases, while reducing the point light source from the discharge lamp 12 The light is condensed so as to extend linearly on the light irradiation surface W in a direction orthogonal to the optical axis of the reflector 13, so the light from the discharge lamp 12 can be effectively used, and the brightness of the discharge lamp 12 itself is high, so The light-irradiated area IA formed on the light-irradiated surface W can be a linear shape having an effective area having a high peak illuminance in a predetermined size.

&lt;Second Embodiment&gt;

The light irradiator according to the second embodiment of the present invention is provided with at least one light source section, which is composed of a short-arc discharge lamp and a reflector that reflects light from the discharge lamp, and is constituted by at least the reflector The specific reflecting member is used to condense the light from the discharge lamp into a light irradiated area that extends linearly on the surface to be irradiated and irradiates it.

Fig. 2 is a cross-sectional view schematically showing a partial structure of an example of a light irradiator according to a second embodiment of the present invention. Fig. 3 is a partial cross-sectional view showing a cross section of the plane extending parallel to the light irradiation surface of the light irradiator shown in Fig. 2, that is, the AA section.

The basic structure of this light irradiator 20 is the same as that of the light irradiator 10 of the above-mentioned first embodiment. In an exterior cover 11 having a light exit 11A opening on one side (downward in FIG. 2), there is arranged A light source section 21 provided with a short arc discharge lamp 12 and a reflector 22 arranged to surround the discharge lamp 12 and reflect the light from the discharge lamp 12, and is provided with a light emitting outlet for reflecting the light from the light source section 21 11A is formed by reflecting mirror 26 to the outside.

The reflector 22 constituting the light source unit 21 uses a composite reflective surface, which is when the optical axis C is set as the three-dimensional rectangular coordinate system of the X axis, the reflective surface 22A of the cross-section of the XY plane is elliptical. Cylindrical reflecting surface (refer to FIG. 2); a cylindrical reflecting surface (refer to FIG. 3) that is parabolic in cross-section with the reflecting surface 22B in the XZ plane. FIG. 4 is a view of the light source unit 21 viewed from the front direction (the opening direction of the reflector 22). As described above, the reflector 22 has two types of reflecting surfaces: cylindrical ellipse and cylindrical paraboloid, and the curvature of the Y direction and the Z direction are different, so a boundary line can be generated at the junction of the two reflecting surfaces.

The reflector 22 is arranged in a posture with the optical axis C extending parallel to the light irradiation surface W, and the light irradiation opening 22C is opened in a direction different from the light exit 11A of the light irradiator 20, for example, in the right direction in FIG. 2 (X direction).

The reflector 22 is located on the optical axis C in a state where the first focal point Fr1 of the elliptical reflecting surface 22A and the focal point Fr0 of the parabolic reflecting surface 22B coincide with each other.

The discharge lamp 12 constituting the light source unit 21 has the same structure as that of the discharge lamp of the first embodiment, and is arranged so that the light-emitting part (for example, the bright spot of the arc) is located at the first focal point Fr1 of the elliptical reflecting surface 22A of the reflector 22 In this state, the straight line connecting the pair of electrodes extends along the optical axis C of the reflector 13.

The reflecting mirror 26 is composed of a flat mirror, and is arranged such that its reflecting surface 26A faces the light emitting port 22C of the light source unit 21 and the light emitting port 11A of the light irradiator 20, and is on the elliptical reflecting surface 22A of the reflector 22 described later The second focal point Fr2 (the mirror image of the second focal point of the reflector 26) is located in the area of the light irradiation surface W facing the light exit 11A, along the light irradiation surface W (in FIG. 2 it is perpendicular to the paper surface).of direction, Z direction) extend.

Here, the light irradiator 20 utilizes the light emitted by the discharge lamp 12 to be reflected by the reflector 22 to make the light reflected by the parabolic reflecting surface 22B of the reflector 22 into parallel light along the optical axis C. And the light reflected by the elliptical reflecting surface 22A of the reflector 22 is irradiated to the reflecting mirror 26 through the light irradiating port 22C to condense the light at the second focal point Fr2 of the reflecting surface 22A, and then the reflecting mirror 26 faces the light The irradiation surface is turned back in the W direction.

As a result, in the Z-axis direction in the figure, the parallel light is focused only in the X-axis direction, and the light-irradiated surface W forms a light-irradiated area linearly extending in the direction Z-direction orthogonal to the optical axis C of the reflector In the IA method, light from the discharge lamp 12 is irradiated.

In the light irradiator 20 of the second embodiment, the reflector 26 is provided for the user to return only the optical path of the reflector 22 to the light irradiation surface W side. The reflector 22 is arranged such that its optical axis C is aligned with When the Y axis is parallel, so that the reflected light of the reflector 22 is directly emitted from the light exit 11A, the reflector 26 is not required.

According to the light irradiator 20 of the above structure, by adopting the following structure, the short arc type discharge lamp 12 is used as the discharge lamp to form a specific reflecting member optical system with a reflector 22 (the reflector 22 includes The structure of the composite reflective surface of the reflective surface 22A with a specific shape makes it possible to suppress the diffusion of the light irradiated area IA formed on the light irradiated surface W as the length of the optical path becomes larger, while reducing the point light source from the discharge lamp The light of 12 is condensed to extend linearly on the light irradiation surface W in the direction orthogonal to the optical axis of the reflector 22, so the light from the discharge lamp 12 can be effectively used, and the brightness of the discharge lamp 12 itself is high. Therefore, the light-irradiated area IA formed on the light-irradiated surface W can be a linear shape having an effective area having a high peak illuminance in a predetermined size.

&lt;The third embodiment&gt;

The light irradiator according to the third embodiment of the present invention includes at least one light source unit and a reflector. The light source unit is composed of a short-arc discharge lamp and a reflector that reflects light from the discharge lamp. The reflector A mirror reflects the light irradiated by the light source and emits it. A specific reflecting member composed of a reflector and a reflector condenses the light from the discharge lamp to form a linear extension on the illuminated surface. The light irradiates the area and irradiates the person.

Fig. 5 is a cross-sectional view schematically showing a partial structure of an example of a light irradiator according to a third embodiment of the present invention.

The basic structure of this light irradiator 30 is the same as that of the light irradiator 10 of the above-mentioned first embodiment. In an exterior cover 11 having a light exit 11A opening on one side (lower in FIG. 2), a short The arc-type discharge lamp 12 and the light source portion 31 of the reflector 32 arranged to surround the discharge lamp 12 and reflect the light from the discharge lamp 12 are arranged to reflect the light from the light source portion 31 and then emit it through the light exit 11A It is formed by a mirror 36 to the outside.

The reflector 32 constituting the light source unit 31 is an elliptical condenser having a reflecting surface 32A having a rotating elliptical surface centered on the optical axis C, and is arranged in a posture in which the optical axis C and the light irradiation surface W extend parallel to the reflector 32 The light irradiating port 32B is opened in a direction different from the light irradiating port 11A of the light irradiator 30, such as the right direction in FIG. 5.

The discharge lamp 12 constituting the light source unit 31 has the same structure as the discharge lamp of the first embodiment, and is arranged so that the light-emitting part (for example, the bright spot of the arc) is located on the first of the rotatory ellipsoidal reflecting surface 32A of the reflector 32 In the state of the focal point Fr1, the straight line connecting the pair of electrodes extends along the optical axis C of the reflector 32.

The reflecting mirror 36 is a reflecting surface having a parabolic shape in only one axis, that is, the plane including the optical axis C of the reflector 32 and the optical axis D of the reflecting mirror 36, which is a cross-section of the plane along the light emission direction. 36A is composed of a parabolic trough-shaped cylindrical dish mirror. The reflecting surface 36A is arranged to face the light irradiation port 32B of the light source unit 31 and the light exit 11A of the light irradiator 30, at the first focal point Fm1 and the reflector In the state where the second focus Fr2 of the reflecting surface 32A of 32 coincides and the second focus Fr2 is located in the region of the light irradiation surface W facing the light exit 11A, it is along the light irradiation surface W (in FIG. 5, it is along the In the direction perpendicular to the surface of the paper).

In this way, by aligning the second focal point Fr2 of the reflector 32 with the first focal point Fr1 of the reflector 36, the high-brightness light from the discharge lamp 12 can be linearly focused on the second focal point Fr2 of the reflector 36 .

Here, the light irradiator 30 reflects the light emitted by the discharge lamp 12 with a reflector 32 having a reflecting surface 32A in the shape of a rotating ellipse, and irradiates it to the reflector 36 through the light irradiation port 32B to condense the light on the reflector. The second focal point Fr2 of the ellipse-shaped reflective surface 32A of 32 is once condensed at the second focal point Fr2 of the reflective surface 32A of the reflector 32, and then enters the mirror 36 while spreading again.

The light incident to the mirror 36 is reflected by the cylindrical reflective surface 36A whose cross-section of the mirror 36 is elliptical, so that the light is not condensed in the longitudinal direction of the mirror 36 (in FIG. 5, the direction perpendicular to the paper surface) , But only condensed in the optical axis direction of the reflector 32 (the left and right direction in FIG. 5) while exiting through the light exit 11A, whereby the light from the discharge lamp 12 is irradiated so that the light is located on the reflector 36 The light irradiation surface W of the second focal point Fr2 of Fr2 forms a light irradiation area IA extending linearly in a direction orthogonal to the optical axis C of the reflector 32.

If the light irradiator 30 according to the above-mentioned structure is adopted, the short arc type discharge lamp 12 is used as the discharge lamp, and the reflector 32 and the reflector 36 having the reflecting surfaces 32A and 36A of specific shapes are combined. The formed optical system of the specific reflecting member makes it possible to condense the light on the light irradiation surface W while suppressing the spread of the light irradiation area IA formed on the light irradiation surface W as the optical path length increases, and reflect it toward and away from the light irradiation surface W. The optical axis of the lamp 13 extends linearly in the direction orthogonal to the optical axis, so the light from the discharge lamp 12 can be effectively used, and the brightness of the discharge lamp 12 itself is high, so the light irradiation area IA formed on the light irradiation surface W It is possible to make the effective area with high peak illuminance into a linear shape of a predetermined size.

In addition, by creating the following structure (optical system), a combination of a reflector 32 composed of an elliptical condenser lens having a revolving elliptical reflecting surface 32A; and a reflector composed of a cylindrical surface having an elliptical reflecting surface 36A. The structure in which the mirror 36 condenses and irradiates the light from the discharge lamp 12 can further obtain the following effects.

Since the diffusion angle of the light once collected at the second focal point Fr2 of the reflector 32 can be set according to the curvature of the reflector 32, the condensing position of the light reflected by the reflector 36 (the size of the focal length ) Can be set according to the curvature of the reflector 36, so by adjusting the curvature of the reflector 32 and the curvature of the reflector 36, the length of the first focal point Fr1 formed linearly extending can be appropriately adjusted according to the purpose.

In the foregoing, for any of the light irradiators of the first to third embodiments, the light source device is described as having a single structure, but since a light irradiation area of an appropriate size corresponding to the size of the light irradiation object can be obtained, it is actually It is better to have a structure with a plurality of light source parts. In the following, a light irradiator of the first embodiment provided with, for example, two light source units will be described as an example.

Fig. 6 is a cross-sectional view schematically showing a partial structure of an example of a light irradiator according to another embodiment of the present invention. Fig. 7 is a plan view of the light irradiator shown in Fig. 6 when viewed from above.

This light irradiator 40 is provided with an exterior cover 11 having a light emission outlet 11A opening on one side (downward in FIG. 6). In the exterior cover 11, a short arc type is arranged. The discharge lamp 12 and the two light source parts 151 and 152 of the reflector 13 arranged to surround the discharge lamp 12 and reflect the light from the discharge lamp 12 are arranged to reflect the light from the light source parts 151 and 152 and pass the light The ejection port 11A is formed by a reflecting mirror 17 that ejects to the outside.

The structure of one of the light source unit 151 is the same as that shown in FIG. The discharge lamp 12 of the same form and structure is arranged so that the light-emitting part (for example, the bright spot of the arc) is located at the focal point Fr of the reflecting surface 13A of the paraboloid of the reflector 13, and the line connecting the pair of electrodes is along the line of the reflector 13 The optical axis C1 extends. In addition, the other light source unit 152 also has the same structure.

The respective light source units 151 and 152 are in a posture extending in a direction that crosses the reflective surface 17A of the mirror 17 and are arranged so that they are at the same horizontal position on the light irradiation surface W. One of the light source units 151 The optical axis C1 and the optical axis C2 of the other light source unit 152 both extend parallel to the light irradiation surface W, and overlap at the peripheral portion so as not to interrupt the light irradiation area of the respective light source units 151 and 152.

The reflecting mirror 17 has the same structure as that shown in FIG. 1, and is constituted by a trough-shaped cylindrical dish mirror having a reflecting surface 17A having a parabolic shape in only one axis.

Here, the light irradiator 40 uses the reflector 13 to reflect the light emitted by the discharge lamps 12 of the respective light source units 151 and 152 to create parallel lights along the respective optical axes C1 and C2, and then pass through the light irradiating port 13B The light is irradiated toward the reflector 17, and the parallel light incident on the reflector 17 by the respective light source parts 151 and 152 is reflected by the cylindrical reflecting surface 17A whose cross-section of the reflector 17 is parabolic, so that the light is not condensed on the reflector 17 In the longitudinal direction (in the vertical direction in FIG. 7), the light is condensed in the direction orthogonal to the longitudinal direction of the reflector 17 (in the horizontal direction in FIG. 7), and emitted through the light exit 11A, thereby , The light from the discharge lamp 12 is irradiated so that the light irradiation surface W located at the focal point Fm of the reflector 17 forms the light irradiation areas IA1 of the respective light source portions 151, 152 linearly extending in the longitudinal direction of the reflector 17 IA2 overlaps each other.

According to the light irradiator 40 of the above-mentioned structure, by forming the respective light irradiation regions IA1 and IA2 extending linearly on the light irradiation surface W, the peripheral regions with lower illuminance than the central region overlap each other, so that the total The illuminance has the same illuminance as the central area. In the light irradiation area, a large effective area with sufficient high illuminance can be set, and a light irradiation area of a size suitable for the purpose can be obtained reliably. The following shows examples of experiments performed to confirm such effects.

&lt;Experimental example&gt;

According to the structure shown in FIG. 6 and FIG. 7, the light irradiator (40) of the present invention is manufactured.

The discharge lamp (12) of each light source (151, 152) is an ultra-high pressure mercury lamp with a distance between electrodes of 1.2mm and a rated power of 210W. The reflector (13) is used as a mirror. The effective field size of the light irradiation port (13B) is approximately It is a dish mirror of 44mm×48mm and a focal distance of 6mm.

The reflecting mirror (17) uses a cylindrical dish mirror with a focal distance of 60mm.

The light irradiation area of the respective light source units (151, 152) is, for example, 50 mm. When a part of the peripheral area is overlapped with each other, the effective area length of the entire light irradiation area is sufficiently high to be 65 mm. The light source units (151, 152) are arranged so as to be inclined in a direction intersecting the reflecting surface (17A) of the reflecting mirror (17). The distance from the light exit (11A) to the light irradiation surface (W) is 22mm.

&lt;Specific form of comparative light irradiator&gt;

Prepare a lamp "UVH-150M/XJ1" (manufactured by Ushio Electric Co., Ltd.) (refer to the light irradiator shown in Figure 13, which has a metal halide lamp with a rated power of 1500W and a luminous length of 125mm as the light source. At the position behind the metal halide lamp in the direction, an elliptical cold mirror with a focal distance of about 120mm is arranged.

For these respective light irradiators, when measuring the ultraviolet radiation intensity (illuminance) in the direction orthogonal to the longitudinal direction of the linear light irradiation area formed on the light irradiation surface, it was confirmed that, as shown in Fig. 8, if according to In the light irradiator of the present invention, even if the power input to the discharge lamp is less than 1/3 of the power of the light source lamp of the light irradiator for comparison, the peak intensity value is about 600mW/ cm²The peak illuminance (2900 mW/cm²) (Refer to curve (I)).

Above, the light irradiator of the first embodiment has been described as an example. However, the light irradiator of the second embodiment and the light irradiator of the third embodiment can be constructed with a plurality of light source units. With such a structure, the same effects as described above can be obtained.

Especially in the light irradiator of the third embodiment, by setting the curvature of the reflector and the curvature of the mirror appropriately according to the purpose, the length of the light irradiation area of the adjacent light source unit is adjusted, and the overlapping area is adjusted. For example, the size of the illuminance can make the illuminance of the peripheral portion lower than that of the central portion complementary, so it is easy to distribute all the covers in the long direction of the light irradiation area into an even state, and even if the two light source portions are not used to make them separate The optical axis of the reflector is arranged obliquely, and the peripheral parts of the light irradiation area of the adjacent light source parts can also be overlapped with each other, so the installation structure design becomes simple.

In addition, the light irradiators in the first to third embodiments described above have been described with a structure in which the light source unit is arranged in a posture in which the optical axis of the reflector extends parallel to the light irradiation surface, but it may be as shown in the figure. As shown in Fig. 9, the light source unit 31 is arranged in a posture in which the optical axis C of the reflector 32 extends in the direction perpendicular to the light irradiation surface W. With this structure, it is also possible to obtain the same structure as the first embodiment to the first embodiment described above. The light irradiators 10, 20, and 30 of the third embodiment have the same effect, and since the dischargeable lamp 12 is installed in the vertical direction, the lateral width of the light irradiator (lamp) can be reduced and compact. The structure of the light irradiator 50 is to condense the light from the discharge lamp 12 into a light irradiation area IA extending linearly on the light irradiation surface W by a specific reflecting member composed of a reflector 32 and a reflector. And irradiate it, which belongs to the third embodiment described above.

A specific description of the structure of the light irradiator 50 is as follows, that is, it is provided with an exterior cover 11, which is box-shaped as a whole, has a light emission outlet 11A that opens on one side (downward in FIG. 9), and is attached to the exterior cover In 11, a light source unit 31 having a short-arc discharge lamp 12 and a reflector 32 arranged to surround the discharge lamp 12 and reflect the light from the discharge lamp 12 is arranged, and is arranged to reflect the light from the light source unit 31 It is formed by two reflecting mirrors that are emitted to the outside through the light emission outlet 11A.

The reflector 32 constituting the light source unit 31 uses a reflecting surface 32A having a rotating elliptical surface centered on the optical axis C, and is arranged as a reflector with the optical axis C extending perpendicularly to the light irradiation surface W The light irradiation port 32B of 32 opens in the same direction as the light irradiation port 11A of the light irradiator 50, for example.

The discharge lamp 12 constituting the light source unit 31 has the same structure as the discharge lamp of the first embodiment described above, and is arranged so that the light-emitting portion (for example, the bright spot of the arc) is located on the rotating ellipsoidal reflecting surface 32A of the reflector 32 In the state of the first focal point Fr1, the straight line connecting the pair of electrodes extends along the optical axis C of the reflector 32.

The two reflecting mirrors are composed of a first reflecting mirror 52 of a plane mirror and a second reflecting mirror 53 of a trough-shaped cylindrical elliptical mirror whose reflecting surface 53A in only one axis direction is an ellipse.

The first reflecting mirror 52 is arranged such that the light irradiation direction of the light source unit 31 is positioned on the front side relative to the second focal point Fr2 of the reflecting surface 32A of the reflector 32, and the reflecting surface 52A faces the reflector 32 obliquely upward. In a state where the optical axis C is inclined, it extends along the light irradiation surface W (in the direction perpendicular to the paper surface in FIG. 9).

Here, the light irradiator 50 reflects the light emitted by the discharge lamp 12 with a reflector 32 having a reflecting surface 32A in the shape of a rotating ellipse, and irradiates the light to the reflector 52 through the light irradiation port 32B to condense the light on the rotating ellipse. The second focal point Fr2 of the planar reflecting surface 32A is reflected by the first connecting portion 35 before the second focal point Fr2 is condensed, and once it is at the position of the mirror image of the first mirror 52 (the second mirror 53 After the first focal point Fm1) of the reflecting surface 53A of the light is collected, it is incident on the second reflecting mirror 53 while being diffused again.

The light incident on the second mirror 53 is reflected by the cylindrical reflective surface 53A whose cross-section is elliptical, so that it does not condense the light and diffuses in the longitudinal direction of the second mirror 53 (in FIG. 9 as The direction perpendicular to the surface of the paper), but only the direction perpendicular to the longitudinal direction of the second mirror 53 (the left-right direction in FIG. 9) is collected, and the light is emitted through the light exit 11A, whereby the light is emitted from The light of the discharge lamp 12 forms a light irradiation area IA extending linearly in the longitudinal direction of the second mirror 53 on the light irradiation surface W located at the second focal point Fr2 of the second mirror 53.

In addition, for the light irradiator of this structure, the following structure can also be made, that is, as shown in FIG. A part of the light irradiation areas IA1 and IA2 of the light source units 31 in the longitudinal direction of the mirror 53 overlaps. By making this structure, the same effect as that shown in FIGS. 6 and 7 can be obtained, that is, when the light is irradiated The surface W forms the light irradiation areas IA1 and IA2 extending linearly. By overlapping the peripheral areas with lower illuminance than the central area, it becomes possible to have the same illuminance as the central area. The irradiated area has a sufficiently high illuminance, and the effective area IA0 having an even illuminance distribution in the longitudinal direction can be set to be large, and a light irradiated area of a size suitable for the purpose can be obtained reliably. In addition, in FIG. 10, only the reflection position of the 1st mirror 52 and the 2nd mirror 53 which comprise a reflection member reflects the light from arbitrary directions from a light source device is shown.

The light irradiator of the present invention has been described above, but the light irradiator of the present invention is not limited to the above-mentioned embodiment, and various modifications can be made.

For example, in the first embodiment, it is possible to use a trough-shaped cylindrical mirror having an arc-shaped reflection surface in only one axis direction as the reflection mirror. In the case of using this kind of mirror, the condensing performance is slightly lower than that of the parabolic reflecting surface due to the influence of the spherical aberration, but in practice, it can also obtain a sufficient effect.

In addition, in the light irradiator of the present invention, it is possible to use vapor deposition of a multilayer film (cold) that has the function of transmitting light from the visible region to the infrared region and radiant heat from the lamp, and reflecting only the light in the ultraviolet region. mirror). In the case of this structure, when the light irradiator of the present invention is applied to an inkjet printer using photocurable ink described later, it can be more reliably prevented from being included in the light emitted by the discharge lamp. The light from the visible region to the infrared region or the radiant heat generated by the lighting of the discharge lamp is irradiated to the recording medium. Therefore, it is possible to prevent the recording medium from heating (higher temperature of the recording medium). Therefore, it is susceptible to heat and deformation during use. The paper, resin or film is extremely useful as a recording medium.

In addition, the short-arc discharge lamp is not limited to an ultra-high pressure mercury lamp. For example, a metal halide type short-arc discharge lamp may be used. In particular, if a halogen compound such as iron (Fe) is enclosed, it may be in the range of 350 to 450 nm. The luminous efficiency of light in the nearby wavelength range becomes higher, so the total radiation beam of the light irradiation surface (light irradiation object) increases. Therefore, the treatment efficiency of the curing treatment of, for example, the photocuring ink can be improved.

As described above, according to the light irradiator of the present invention, it is possible to condense the light from the short-arc discharge lamp forming a point light source while suppressing the spread of the light irradiation area of the light irradiation surface with the length of the optical path. It extends linearly in any direction of the light irradiated surface, so the light from the discharge lamp can be effectively used, and because the brightness of the discharge lamp itself is high, a high peak illuminance can be obtained on the irradiated surface. The light-irradiated area formed by the irradiated surface has uniform illuminance distribution in the longitudinal direction, and the effective area with high peak illuminance is made into a line of a predetermined size. Therefore, the light irradiator of the present invention is suitable for use as a light source for light-curing ink sprayed onto a recording medium such as a light-curing inkjet printer (hereinafter simply referred to as "inkjet printer") Very useful at times.

Fig. 11 is a perspective view schematically showing a partial structure of an example of the inkjet printer of the present invention. Fig. 12 is a cross-sectional view of the inkjet printer shown in Fig. 11;

This inkjet printer is equipped with a head 60, the head 60 is composed of a recording head 61 and two light irradiators 62A, 62B mounted on the carriage 63, the recording head 61 is provided with, for example, ultraviolet curing The type ink is made into tiny droplets and ejected onto the recording medium R. Nozzles (not shown). The two light irradiators 62A and 62B are installed on the recording head 61, for example, on both sides of the recording head. The ink of medium R is irradiated with ultraviolet rays to harden it.

The head 60 is supported by a rod-shaped guide rail 65 provided to extend along the recording medium R, and is reciprocally movable along the guide rail 65 to a position above the recording medium R by a driving mechanism not shown.

As the ultraviolet curable ink used, for example, a radical polymerization ink containing a radical polymerizable compound as a polymerizable compound, a cationic polymerization ink containing a cation polymerizable compound as a polymerizable compound, and the like can be cited.

As the recording medium R, for example, paper, resin, film, etc. can be used.

One of the light irradiators 62A is constructed by having the same structure as the light irradiator 40 (refer to FIGS. 6 and 7) of the first embodiment in which two light source units are arranged side by side. That is, the light source units 151 and 152 are in a mutual horizontal position with respect to the recording medium R, and the optical axes C1 and C2 of the reflector 13 extend parallel to the recording medium R, and face the reflecting surface 17A of the counter mirror 17. Postures extending in directions orthogonal to each other, arranged side by side.

One of the light source unit 151 is a reflector 13 composed of a dish-shaped mirror having a rotating parabolic reflecting surface 13A centered on the optical axis C1, and the discharge lamp 12 is arranged in its light-emitting part (for example, a bright spot of an arc) The focal point Fr of the reflective surface 13A in the parabolic shape of the reflector 13 extends along the optical axis C1 of the reflector 13 and is formed. The other light source unit 152 also has the same structure.

The reflecting mirror 17 is constituted by a trough-shaped cylindrical dish mirror having a reflecting surface 17A having a parabolic shape in only one axis.

In addition, for the other light irradiator 62B, except that the arrangement positions of the two light source units 151, 152 and the reflecting mirror 17 are symmetrical to the arrangement position of one of the light irradiators 62A, the rest is irradiated with the light of either one The structure of the device 62A is the same.

In this inkjet printer, for example, in a state where the discharge lamp 12 is lit, the head 60 arranged so that the recording medium R is located at or near the focal point Fm of the reflector 17 of the light irradiators 62A and 62B is moved to The upper position of the recording medium R is such that the light from the discharge lamp 12 is condensed linearly, and the recording medium R located at the second focal point Fm of the reflector 17, for example, is perpendicular to the moving direction of the head 60 In this way, the ultraviolet curable ink that has just been sprayed onto the recording medium R is cured.

The curing process of the ultraviolet curable ink is specifically described as follows. That is, in FIG. 12, when the head 60 is also moved to the right while printing on the recording medium R, the ultraviolet curable ink sprayed on the recording medium R is It is hardened by the irradiated light from one of the light irradiators 62A located on the rear side of the head 60 in the moving direction, and when in FIG. 12, when the head 60 moves to the left while printing on the recording medium R, The ultraviolet curable ink sprayed on the recording medium R is cured by the irradiation light from the other light irradiator 62B located on the rear side of the head 60 in the moving direction.

In this way, according to the inkjet printer with the above structure, the light from the discharge lamp 12 irradiates the ultraviolet curable ink that has been sprayed on the recording medium R with high illuminance. Therefore, it is possible to achieve high efficiency The ultraviolet curable ink just sprayed on the recording medium R is cured (photopolymerized), which can shorten the time required for curing. As a result, the dot shape can be prevented from changing, so high-quality images can be formed reliably .

In addition, by adopting the following structure, the light irradiators 62A and 62B reflect the light from the discharge lamp 12 and irradiate the recording medium R, so that the light emitted by the discharge lamp 12 is included in the visible region to the infrared region. The light and the radiant heat accompanying the lighting of the discharge lamp 12 will not directly enter the recording medium R, so the influence of heat on the recording medium R can be minimized, even in the case of the use of a recording medium that is prone to thermal deformation. The recording medium is reliably prevented from being deformed, and therefore, the limitation of the recording medium R that can be used can be eliminated.

In addition, according to the present invention, the light irradiator (lamp) can be made smaller and lighter than those equipped with a long-arc discharge lamp. Therefore, it is possible to reduce the weight of the entire inkjet printer and to achieve the same The increase in the efficiency of the hardening of the ink results in an increase in the printing speed.

In addition, in the inkjet printer of the present invention, not only the light irradiator of the first embodiment described above, but also the light irradiator of the second embodiment and the third embodiment can be applied. In the case of using the structure of the light irradiator of the second embodiment and the third embodiment, the same effects as described above can also be obtained.

Furthermore, in the above-mentioned inkjet printer, the structure of recording images by moving the head against the recording medium has been described. However, the light irradiator of the present invention can also be applied to Location, such as the structure where the recording medium is intermittently transported to record the image.

In addition, the light irradiator of the present invention is not only a light source used to harden photo-curing ink that has been sprayed onto a recording medium, such as a photo-curing inkjet printer, but can also be applied to the coating on 2 A panel bonding device in which the linear light-curable adhesive material between the light-transmitting substrates is irradiated with light to bond the two light-transmitting substrates. In such a panel bonding device, the length of the light-irradiated area formed by the light irradiator can be designed in accordance with the length of the light-curable adhesive applied in a linear shape.

<p>10. . . Light irradiator</p><p>11A. . . Light exit</p><p>11. . . Exterior cover</p><p>12. . . Discharge lamp</p><p>13. . . reflector</p><p>13A. . . Reflective surface</p><p>13B. . . Light irradiation port</p><p>15. . . Light source</p><p>17. . . Reflector</p><p>17A. . . Reflective surface</p><p>C. . . Optical axis</p><p>W. . . Light-irradiated surface</p><p>Fr. . . Focal point of reflector</p><p>Fm. . . Focus of the mirror</p><p>IA. . . Light irradiation area</p><p>20. . . Light irradiator</p><p>twenty one. . . Light source</p><p>twenty two. . . reflector</p><p>22A. . . Reflective surface</p><p>22B. . . Reflective surface</p><p>22C. . . Light irradiation port</p><p>Fr0. . . Focus of parabolic reflecting surface</p><p>Fr1. . . The first focus of the elliptical reflecting surface</p><p>Fr2. . . The second focus of the elliptical reflecting surface</p><p>26. . . Reflector</p><p>26A. . . Reflective surface</p><p>30. . . Light irradiator</p><p>31. . . Light source</p><p>32. . . reflector</p><p>32A. . . Reflective surface</p><p>32B. . . Light irradiation port B</p><p>36. . . Reflector</p><p>36A. . . Reflective surface</p><p>Fm1. . . The first focus of the mirror</p><p>Fm2. . . The second focus of the mirror</p><p>40. . . Light irradiator</p><p>151,152. . . Light source</p><p>C1, C2. . . Optical axis</p><p>IA1, IA2. . . Light irradiation area</p><p>IA0. . . Effective area</p><p>50. . . Light irradiator</p><p>52. . . 1st mirror</p><p>52A. . . Reflective surface</p><p>53. . . 2nd mirror</p><p>53A. . . Reflective surface</p><p>60. . . head</p><p>61. . . Record head</p><p>62A, 62B. . . Light irradiator</p><p>63. . . bracket</p><p>65. . . guide</p><p>70. . . head</p><p>71. . . Record head</p><p>72. . . bracket</p><p>75. . . guide</p><p>R. . . Recording medium</p><p>80A, 80B. . . Light irradiator</p><p>81. . . Cover member</p><p>81A. . . Light exit</p><p>82. . . Discharge lamp</p><p>83. . . reflector</p><p>83A. . . Reflective surface</p><p>83B. . . Light irradiation port</p>

Fig. 1 is a cross-sectional view schematically showing a partial structure of an example of a light irradiator according to the first embodiment of the present invention.

Fig. 2 is a cross-sectional view schematically showing a partial structure of an example of a light irradiator according to a second embodiment of the present invention.

Fig. 3 is a partial cross-sectional view showing a cross section of the plane extending parallel to the light irradiation surface of the light irradiator shown in Fig. 2, that is, the AA section.

Fig. 4 is a view of the light source unit viewed from the front direction (the opening direction of the reflector).

Fig. 5 is a cross-sectional view schematically showing a partial structure of an example of a light irradiator according to a third embodiment of the present invention.

Fig. 6 is a cross-sectional view schematically showing a partial structure of an example of a light irradiator according to another embodiment of the present invention.

Fig. 7 is a plan view of the light irradiator shown in Fig. 6 when viewed from above.

FIG. 8 is a diagram showing together the ultraviolet radiation intensity distribution (illuminance distribution) of the light irradiation area formed by the light irradiator of the present invention in the direction orthogonal to its longitudinal direction, and a comparison light irradiator equipped with a long arc discharge lamp Distribution chart.

Fig. 9 is a cross-sectional view schematically showing a partial structure of another example of the light irradiator according to the third embodiment of the present invention.

Fig. 10 is a cross-sectional view schematically showing a partial structure of another example of the light irradiator according to the third embodiment of the present invention.

Fig. 11 is a perspective view schematically showing a partial structure of an example of the inkjet printer of the present invention.

Fig. 12 is a cross-sectional view of the inkjet printer shown in Fig. 11;

Fig. 13 is a perspective view schematically showing a partial structure of an example of a conventional inkjet printer using a photocurable inkjet method.