JP2009098381A - Ultraviolet irradiation apparatus and recording apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultraviolet irradiation head 330 furnished with an oval reflection mirror 334. <P>SOLUTION: The ultraviolet irradiation head has: the oval reflection mirror 334 which has a pair of end parts on a line extending in a short axis direction passing through one focal point f2 and an oval arc cross section including the other focal point f2; a discharge tube 332 disposed at the other focal point f1; and a condenser lens 336 having an incident side focal point f3 at the one focal point f2. It is possible that the discharge tube 332 has a linear light emission part and the oval reflection mirror 334 is extended in the direction perpendicular to the cross section, having the one focal point f1 at the position of the light emitting part at each position in the longitudinal direction of the discharge tube 332. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an ultraviolet irradiation apparatus and a recording apparatus. More specifically, in an apparatus or facility for curing an ultraviolet curable resin, such as a recording apparatus using an ultraviolet curable ink, an ultraviolet irradiation apparatus that generates ultraviolet rays to irradiate the ultraviolet curable resin, and a recording provided therewith Relating to the device.

  The ultraviolet curable resin contains a photopolymerization initiator, and radicals generated by the irradiated ultraviolet rays form a polymerizable double bond to cure. Ultraviolet curable resins are often used as base materials for paints, inks, etc., as well as optical modeling materials and adhesives. As a method for attaching the ultraviolet curable ink to the recording medium, there are coating, printing, and the like, but the use of an ink jet method capable of accurately forming an arbitrary image or pattern without a printing plate is expected.

  The ultraviolet curable ink has a preferable characteristic as a printing ink, in which the curing is very slow until it is irradiated with ultraviolet rays, and it is rapidly cured when irradiated with ultraviolet rays. In addition, since the solvent is not volatilized or released during the curing process, there is an advantage that the environmental load is small.

Patent Document 1 listed below describes an ultraviolet irradiation device that includes a straight tube ultraviolet lamp and a cold mirror having an elliptical arc cross section and can irradiate ultraviolet rays with high efficiency. Patent Document 2 listed below describes an ink jet printer including an ultraviolet curing irradiation device that collects light with a reflecting mirror.
JP 2003-052111 A JP 2006-035648 A

  The curing rate of the ultraviolet curable resin changes depending on the intensity of the irradiated ultraviolet light. For this reason, the ultraviolet irradiation device used for the purpose of curing the ultraviolet curable resin is always required to improve the intensity of the irradiated ultraviolet rays.

  However, since many ultraviolet light sources generate heat together with ultraviolet rays, it is impossible to increase the input energy. In addition, since energy generated inevitably is dissipated or energy is separately supplied to cool the equipment, the energy efficiency of the high-power ultraviolet irradiation device tends to decrease.

  Therefore, in order to solve the above problem, as a first embodiment of the present invention, an elliptical arc having a pair of ends on a line passing through one focal point and extending in the minor axis direction and containing the other focal point is provided. There is provided an ultraviolet irradiation apparatus including an elliptical reflecting mirror having a cross-sectional shape, an ultraviolet light source disposed at the other focal point, and a condenser lens having an incident side focal point at one focal point. Thereby, it is possible to irradiate high-intensity ultraviolet rays without increasing the input energy. Moreover, since energy efficiency is improved, the calorific value is also reduced.

  In the ultraviolet irradiation device, the ultraviolet light source is a discharge tube having a linear light emitting portion, and the elliptical reflecting mirror has one focal point at the position of the light emitting portion at each position in the longitudinal direction of the discharge tube. , It may extend in a direction perpendicular to the cross section. Thereby, a discharge tube widely used as an ultraviolet light source can be used with high efficiency. Moreover, high intensity ultraviolet rays can be irradiated over a wide irradiation range.

  Further, in the ultraviolet irradiation device, the condenser lens may have a reflection layer on the incident surface that reflects light having a wavelength exceeding 400 nm. Thereby, while not contributing to the curing of the ultraviolet curable resin, it is possible to suppress long-wavelength light that heats the irradiation target.

  Furthermore, in the ultraviolet irradiation device, the condenser lens may include three or more optical glass lenses. Thereby, a high-performance condenser lens can be formed using optical glass having high resistance to ultraviolet rays and excellent optical characteristics. In addition, a condenser lens having the required characteristics can be formed without using an expensive material such as lithium fluoride or calcium fluoride crystal (fluorite), which contributes to cost reduction.

  Furthermore, in the above ultraviolet irradiation device, the elliptical reflecting mirror may be a cold mirror that reflects light in the ultraviolet band and transmits light in another band. Thereby, the long wavelength light which does not contribute to hardening of ultraviolet curable resin is dissipated outside through a cold mirror, and the temperature rise of an ultraviolet irradiation device can be suppressed.

  Still further, in the ultraviolet irradiation device, the condenser lens may have an incident side end surface that forms a concave surface having a focal point arranged at one focal point with respect to incident ultraviolet rays. Thereby, the ultraviolet rays emitted from the reflecting mirror and diffused can be converged with high efficiency.

  Furthermore, in the ultraviolet irradiation apparatus, the condenser lens may have a transmittance of 96% or more with respect to ultraviolet rays having a wavelength of 365 nm. Thereby, the ultraviolet-ray of the zone | band which contributes to hardening of ultraviolet curable resin can be irradiated with high efficiency.

  Still further, in the ultraviolet irradiation device, the condenser lens has three optical glass lenses, and among the three optical glass lenses, an optical glass lens to which ultraviolet light is incident and an optical glass lens that emits ultraviolet light are: , Having an index of refraction of 1.65 or more and 1.67 or less with respect to ultraviolet light having a wavelength of 365 nm, an Abbe number of 35.98 or more and 36.02 or less, and another one sheet The optical glass lens may have a refractive index of 1.60 or more and 1.62 or less with respect to ultraviolet light having a wavelength of 365 nm, and may have an Abbe number of 60.0 or more and 62.0 or less. Thereby, a highly efficient ultraviolet irradiation device can be formed using an easily available optical glass lens.

  Further, as a second embodiment of the present invention, a recording head that discharges ultraviolet curable ink while moving in a reciprocating movement direction that intersects the conveyance direction of the recording medium, and extends in the minor axis direction through one focal point. An elliptical reflector having an elliptical arc cross-sectional shape having a pair of ends on an existing line and including the other focal point, an ultraviolet light source disposed at the other focal point, and an incident-side focal point at one focal point There is provided a recording apparatus including an ultraviolet irradiation unit that irradiates ultraviolet rays to ultraviolet curable ink that is discharged from a recording head and attached to a recording medium. Thereby, the above-described effect can be enjoyed also in the liquid ejecting apparatus.

  It should be noted that the above summary of the invention does not enumerate all the necessary features of the present invention. Further, a sub-combination of these feature groups can be an invention.

  Hereinafter, the present invention will be described through embodiments of the invention, but the following embodiments do not limit the invention according to the claims. In addition, not all the combinations of features described in the embodiments are essential for the solving means of the invention.

  FIG. 1 is a perspective view showing an appearance of an ink jet recording apparatus 100 according to an embodiment. The ink jet recording apparatus 100 performs recording by ejecting ink onto a large single sheet such as a JIS standard A0 size or a JIS standard B0 size, or roll paper having the same paper width as the single sheet. In addition to paper, a resin film or the like can be used as the recording medium.

  As shown in the figure, the ink jet recording apparatus 100 includes a casing 110 including an upper casing 112 and a lower casing 114 that are stacked on each other, and a small casing 116 that is suspended below the lower casing 114. Have The housing 110 is lifted and supported by the legs 120 from below. As a result, a space for discharging the recorded recording paper 150 is formed below the housing 110.

  The upper casing 112 is provided with an operation panel 130 that is used when the ink jet recording apparatus 100 is operated in a stand-alone manner. The operation panel 130 may be provided with a display panel, a display lamp, and the like that indicate the operation state of the ink jet recording apparatus 100. On the other hand, the lower housing 114 is provided with a cartridge holder 140 into which an ink cartridge 240 containing ink is loaded.

  In the ink jet recording apparatus 100, the recording paper 150 on which an image is recorded is sent forward from between the upper housing 112 and the lower housing 114. The fed recording sheet 150 hangs downward due to its own weight. Therefore, a smooth guide surface 252 that smoothly guides the recording paper 150 is formed at the front end of the suction platen 250 that can be seen in the gap between the upper housing 112 and the lower housing 114.

  FIG. 2 is a perspective view showing the ink jet recording apparatus 100 as seen from the back. As shown in the figure, on the rear surface of the ink jet recording apparatus 100, a spindle 160 that is horizontally stretched and a roll 152 that is horizontally supported by being inserted through the spindle 160 are disposed at the rear of the lower housing 114. Installed. The roll 152 is formed by winding a long recording sheet 150. The recording paper 150 shown in FIG. 1 corresponds to the front end of the recording paper 150 pulled out from the roll 152 and passing through the inside of the housing 110 and then pulled out to the front.

  FIG. 3 is a perspective view schematically showing the internal mechanism 200 of the ink jet recording apparatus 100. As shown in the figure, the internal mechanism 200 includes a guide shaft 270, a recording head assembly 230, and a suction platen 250.

  The guide shaft 270 extends horizontally along the longitudinal direction of the ink jet recording apparatus 100. The recording head assembly 230 is supported by the guide shaft 270 and reciprocates in the reciprocating movement direction M along the guide shaft 270.

  The recording head assembly 230 includes a recording head 310 and a pair of ultraviolet irradiation heads 320 and 330 that sandwich the recording head 310 in the extending direction of the guide shaft 270. The recording head 310 and the ultraviolet irradiation heads 320 and 330 move integrally along the guide shaft 270.

  In addition, a timing belt 220 that is hung on a pair of pulleys 260 is disposed behind the guide shaft 270. One of the pulleys 260 is rotationally driven by a carriage motor 222. As a result, the timing belt 220 travels parallel to the guide shaft 270 between the pulleys 260.

  A portion of the timing belt 220 is coupled to the recording head assembly 230. Thereby, the recording head assembly 230 can be moved in accordance with the drive signal supplied to the carriage motor 222. Further, a linear scale 214 is arranged in parallel with the reciprocating movement direction M.

  The linear scale 214 has a transparent main body and a light shielding band formed at a constant period along the reciprocating movement direction M. On the other hand, the recording head assembly 230 includes a detection unit that detects and counts light shielding bands. Thereby, the movement amount of the recording head assembly 230 can be accurately detected. Note that the guide shaft 270, the recording head assembly 230, the timing belt 220, and the linear scale 214 are accommodated in the upper housing 112 of the ink jet recording apparatus 100.

  Below the moving range of the recording head assembly 230, along the conveyance direction S of the recording paper 150, a conveyance unit including the conveyance drive roller 212 and the suction platen 250 are arranged in this order. The transport driving roller 212 and the suction platen 250 are accommodated in the lower housing 114.

  The conveyance driving roller 212 is rotated by a conveyance motor, and rotates while the recording paper 150 is pressed by a conveyance driven roller (not shown). As a result, the recording paper 150 is pulled out from the roll 152 and sent out onto the suction platen 250.

  The suction platen 250 supports the recording paper 150 fed from the transport unit from below on a flat surface. The suction platen 250 has a large number of suction holes on the surface thereof that communicate with a decompression source such as a suction fan, and sucks the supported recording paper 150. As a result, the suction platen 250 holds the recording paper 150 with curl or the like flat below the recording head 310.

  On the other hand, a flushing portion 290 and a cap 280 are sequentially disposed outside the suction platen 250 in the reciprocating direction M of the recording head assembly 230. The flushing unit 290 absorbs the ejected ink when the flushing for ejecting a large amount of ink from the recording head 310 is executed. By such flushing, the thickened ink can be removed from the recording head 310. In addition, the cap 280 hermetically seals the lower surface of the recording head 310 during a period when the ink jet recording apparatus 100 is at rest, and prevents the ink from being thickened or solidified in the recording head 310.

  The ink jet recording apparatus 100 having the above structure executes a recording operation as follows. First, the conveyance drive roller 212 feeds the recording paper 150 onto the suction platen 250, and the suction platen 250 holds the conveyed recording paper 150 flat. The recording head 310 ejects ink toward the surface of the recording paper 150 while moving in the reciprocating movement direction M on the recording paper 150 supported on the suction platen 250. Hereinafter, the operation of transporting the recording paper 150 in the transport direction S by the transport unit 210 and the reciprocating movement of the recording head 310 in the reciprocating movement direction M on the recording paper 150 are alternately repeated, and an arbitrary surface of the recording paper 150 is detected. An image is formed by attaching ink to the region.

  FIG. 4 is a partially enlarged view showing the recording head assembly 230 extracted from the ink jet recording apparatus 100. As shown in the figure, the recording head assembly 230 includes a recording head 310 and a pair of ultraviolet irradiation heads 320 and 330 disposed with the recording head 310 sandwiched in the reciprocating movement direction M. A large number of nozzles that eject ultraviolet curable ink are provided on the lower surface of the recording head 310.

  Each of the ultraviolet irradiation heads 320 and 330 collects a discharge tube 332 as an ultraviolet light source, an elliptical reflecting mirror 334 that guides light emitted from the discharge tube 332 downward, and ultraviolet rays emitted from the elliptical reflecting mirror 334. A condenser lens 336. As the discharge tube 322, an ultraviolet lamp such as a metal halide lamp, a xenon lamp, a carbon arc lamp, a chemical lamp, a low pressure mercury lamp, or a high pressure mercury lamp can be used. This type of light source includes a quartz glass tube that seals a discharge atmosphere and an electrode that applies a discharge voltage therein.

  The reflecting mirror 324 is formed by molding an aluminum plate or the like and has an elliptical arc cross-sectional shape. Thus, the ultraviolet rays emitted radially from the discharge tubes 322 and 332 are efficiently reflected and irradiated toward the recording paper 150. Further, the condenser lens 336 converges the diffusing ultraviolet rays and irradiates the recording paper 150 with the generated ultraviolet rays without waste.

  Here, the discharge tube 322 is mounted so that its longitudinal direction is parallel to the transport direction S, and is disposed in the immediate vicinity of the recording head 310. Accordingly, in the recording operation of the ink jet recording apparatus 100, ultraviolet rays are immediately applied to the ultraviolet curable ink ejected onto the recording paper 150 by the recording head 310.

  FIG. 5 is a diagram schematically showing the optical structure 300 of the ultraviolet irradiation heads 320 and 330. In FIG. 5, the reference number of one ultraviolet irradiation head 330 is used, but the other ultraviolet irradiation head 320 also has the same structure.

  In the optical structure 300 shown in FIG. 5, the elliptical reflecting mirror 334 forms an elliptical arc having a minor axis of 68 mm and an eccentricity of 0.85. A discharge tube 332 is disposed on one focal point f 1 of the elliptical reflecting mirror 334. The elliptical reflecting mirror 334 has an end of the reflecting surface on a horizontal plane including the other focal point f2 of the elliptical arc, and forms an opening having a width of 71.8 mm.

  In contrast to the elliptical reflecting mirror 334 described above, the condenser lens 336 is formed using three lenses 331, 333, and 335 each having a positive refractive power, and has a high refractive power as a whole. The focal point f3 on the incident surface side of the condenser lens 336 is disposed at the same position as the other focal point f2 of the elliptical reflecting mirror 334. The optical specifications of the condenser lens 336 are listed in Table 1 below.

[Table 1]
f. l 37.28
F. B 20.23
F 1: 0.497

r D dn ν τ
0 20.23
1 33.500 43.0 6.50 1.66635 36.01 0.965
2 24.000 43.0 0.75
3 64.000 60.0 10.50 1.61261 60.99 0.990
4 36.000 60.0 0.75
5 871.070 75.0 14.50 1.66635 36.01 0.965
6 59.524 75.0 50.00

However, in Table 1 above,
r is the mth radius from the discharge tube 332 side,
D is the diameter of the m-th lens from the discharge tube 332 side,
d is the inter-surface distance between the m-th surface and the next surface from the discharge tube 332 side,
n is the refractive index of i-line (365 nm) of the m-th lens from the discharge tube 332 side,
ν is the mth lens Abbe number from the discharge tube 332 side,
τ represents the i-line internal transmittance per 25 mm thickness of the m-th lens from the discharge tube 332 side.

  Note that the configuration of the condenser lens 336 is not limited to three. However, it is preferable to use three or more lenses 331, 333, and 335 in order to realize the characteristics as the condenser lens 336 using optical glass having resistance to ultraviolet rays.

  As shown in FIG. 5, the ultraviolet light emitted from the discharge tube 332 and reflected by the elliptical reflecting mirror 334 passes through the other focal point f <b> 2 and is emitted from the opening to the outside of the elliptical reflecting mirror 334. The emitted ultraviolet light enters the condenser lens 336 and is converged in a narrower range than the diameter of the lens 335 on the emission side. Further, the ultraviolet rays emitted from the discharge tube 332 and directly emitted from the opening without being reflected by the elliptical reflecting mirror 334 are also incident on the condenser lens 336 and converged.

  In this optical structure 300, the incident surface of the lens 331 that forms the incident surface of the condenser lens 336 forms a concave surface when viewed from the discharge tube 332 side. Thereby, the ultraviolet rays that are emitted from the opening of the elliptical reflecting mirror 334 and diffused are also efficiently captured by the condenser lens 336.

  FIG. 6 is a graph showing the result of measuring the irradiation surface intensity of ultraviolet rays by the ultraviolet irradiation head 330 as described above in the same cross section as FIG. Note that the “irradiation surface position” in the figure is indicated by the distance from the zero point where the position of the central optical axis of the irradiated ultraviolet ray on the irradiation surface is “0”. As shown in the figure, it can be seen that the ultraviolet rays emitted from the discharge tube 332 are converged around the zero point. Further, it can be seen that the illuminance is low at a position away from the zero point, and the recording paper 150 is irradiated with high efficiency.

  Thus, in the ultraviolet irradiation head 330, the ultraviolet rays emitted from the discharge tube 332 are irradiated to the recording paper 150 at a high rate. In the ultraviolet irradiation head 330 according to the present example, a plane luminous flux effective rate of 95.7% was obtained.

  FIG. 7 is a view showing the structure of an ultraviolet irradiation head 330 as a comparative example manufactured for the purpose of comparison with the optical structure 300 shown in FIG. As shown in the figure, in this optical structure 300, the elliptical reflecting mirror 334 has an elliptical arc-shaped cross section with an eccentricity of 0.80, and has an opening with a width of 60 mm at a position intersecting the minor axis. Further, the ultraviolet irradiation head 330 does not include the condenser lens 336. When the plane light flux effective rate of such an ultraviolet irradiation head 330 was measured, it was found that it was only 79.4%.

  FIG. 8 is a view showing a modification of the optical structure 300 shown in FIG. As shown in the figure, in this optical structure, a reflection layer 337 that reflects light having a wavelength longer than 400 nm is provided on the incident surface of the condenser lens 336. The reflective layer 337 reflects light in a band that does not contribute to curing of the ultraviolet curable ink, passes through the other focal point f2 of the elliptical reflecting mirror 334, and returns it to the inside of the elliptical reflecting mirror 334. Thereby, it is prevented that the irradiation target of ultraviolet rays is heated by the light having a long wavelength.

  Furthermore, according to one preferable form, it is preferable that the elliptical reflecting mirror 334 is a cold mirror that transmits light having a wavelength longer than 400 nm. As a result, light in a band that does not contribute to the curing of the ultraviolet curable ink is diffused to the outside of the elliptical reflecting mirror 334, and the temperature rise of the optical structure 300 can be suppressed.

  FIG. 9 is a diagram schematically showing the optical structure 300 of the ultraviolet irradiation head 330 having different specifications. In the optical structure 300 shown in FIG. 9, the elliptical reflecting mirror 334 forms an elliptical arc having a minor axis of 60 mm and an eccentricity of 0.80. A discharge tube 332 is disposed on one focal point f 1 of the elliptical reflecting mirror 334. The elliptical reflecting mirror 334 has an end of the reflecting surface on the horizontal plane including the other focal point f2 of the elliptical arc, and forms an opening having a width of 71.7 mm.

  For the elliptical reflecting mirror 334 as described above, a condenser lens 336 having the same specification as that shown in FIG. 5 was used. Accordingly, the condenser lens 336 has specifications as already shown in Table 1. The condenser lens 336 is also arranged such that the focal point f3 on the incident surface side of the condenser lens 336 is at the same position as the focal point f2 on the opening side of the elliptical reflecting mirror 334. When the plane light flux effective rate of the ultraviolet irradiation head 330 having such an optical structure 300 was measured, it was as high as 94.1%.

  FIG. 10 is a diagram schematically showing the optical structure 300 of the ultraviolet irradiation head 330 with different specifications. In the optical structure 300 shown in FIG. 10, the shape and dimensions of the elliptical reflecting mirror 334 are exactly the same as those shown in FIG. 5, and form an elliptical arc with a minor axis of 68 mm and an eccentricity of 0.85. A discharge tube 332 is disposed on one focal point f1 of the elliptical reflecting mirror 334. Further, the elliptical reflecting mirror 334 has an end of the reflecting surface on a horizontal plane including the other focal point f2 of the elliptical arc, and forms an opening having a width of 71.8 mm. In contrast to the elliptical reflecting mirror 334 as described above, the condenser lens 336 has specifications shown in Table 2 below.

[Table 2]
f. l 35.90
F. B 24.72
F 1: 0.855

r D dn ν τ
0 24.72
1 33.500 43.0 6.50 1.66635 36.01 0.965
2 24.000 43.0 0.75
3 64.000 42.0 5.50 1.61261 60.99 0.990
4 36.000 42.0 0.75
5 871.070 43.0 5.00 1.666635 36.01 0.965
6 59.524 43.0 50.00

However, in Table 2 above,
r is the mth radius from the discharge tube 332 side,
D is the diameter of the m-th lens from the discharge tube 332 side,
d is the inter-surface distance between the m-th surface and the next surface from the discharge tube 332 side,
n is the refractive index of i-line (365 nm) of the m-th lens from the discharge tube 332 side,
ν is the mth lens Abbe number from the discharge tube 332 side,
τ represents the i-line internal transmittance per 25 mm thickness of the m-th lens from the discharge tube 332 side.

  When the plane light flux effective rate of the ultraviolet irradiation head 330 having such an optical structure 300 was measured, it was still a high value of 88.5%.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiment. In addition, it is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

1 is a perspective view illustrating an appearance of an ink jet recording apparatus 100 as viewed from the front. 1 is a perspective view illustrating an appearance of an inkjet recording apparatus 100 as viewed from the back. 2 is a perspective view showing an internal mechanism 200 of the ink jet recording apparatus 100. FIG. FIG. 6 is a partially enlarged view of the recording head assembly 230 taken out. It is a figure which shows the optical structure 300 of the ultraviolet irradiation head 330. FIG. It is a graph which shows the irradiation surface illumination ratio by the ultraviolet irradiation head 330. FIG. It is a figure which shows the optical structure 300 of the ultraviolet irradiation head 330 which concerns on a comparative example. FIG. 6 is a diagram showing a modification of the optical structure 300. FIG. 6 is a partially enlarged view of the recording head assembly 230 taken out. FIG. 3 is a diagram illustrating a state in which the recording head assembly 230 is looked up from below.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Inkjet recording device, 110 housing | casing, 112 upper housing | casing, 114 lower housing | casing, 116 small housing | casing, 120 leg part, 130 operation panel, 140 cartridge holder, 150 recording paper, 152 roll, 160 spindle, 200 internal mechanism , 210 transport unit, 212 transport drive roller, 220 timing belt, 222 carriage motor, 230 recording head assembly, 240 ink cartridge, 250 suction platen, 252 guide surface, 260 pulley, 270 guide shaft, 280 cap, 290 flushing unit, 310 recording head, 312 nozzle plate, 320, 330 UV irradiation head, 322, 332 discharge tube, 331, 333, 335 lens, 334 elliptical reflector, 336 condenser lens, 337 reflection layer

Claims (9)

An elliptical reflector having a pair of ends on a line passing through one focal point in the minor axis direction and having an elliptical arc cross-sectional shape containing the other focal point;
An ultraviolet light source disposed at the other focal point;
An ultraviolet irradiation device comprising: a condenser lens having a focal point on the incident side at the one focal point. The ultraviolet light source is a discharge tube having a linear light emitting part,
2. The ultraviolet irradiation device according to claim 1, wherein the elliptical reflecting mirror has the one focal point at the position of the light emitting portion at each position in the longitudinal direction of the discharge tube and extends in a direction perpendicular to the cross section. .   2. The ultraviolet irradiation device according to claim 1, wherein the condenser lens includes a reflection layer that reflects light having a wavelength exceeding 400 nm on an incident surface.   The ultraviolet irradiation device according to claim 1, wherein the condenser lens includes three or more optical glass lenses.   The ultraviolet irradiation device according to claim 1, wherein the elliptical reflecting mirror is a cold mirror that reflects light in the ultraviolet band and transmits light in another band.   2. The ultraviolet irradiation device according to claim 1, wherein the condenser lens has an incident-side end surface that forms a concave surface having a focal point arranged at the one focal point with respect to incident ultraviolet rays.   The ultraviolet irradiation device according to claim 1, wherein the elliptical reflecting mirror has an eccentricity of 0.75 or more and 0.85 or less. The condenser lens has three optical glass lenses,
Among the three optical glass lenses, the optical glass lens to which ultraviolet rays are incident and the optical glass lens that emits ultraviolet rays have a refractive index of 1.65 or more and 1.67 or less with respect to ultraviolet rays having a wavelength of 365 nm. And the Abbe number is 35.98 or more and 36.02 or less,
The other optical glass lens has a refractive index of 1.60 or more and 1.62 or less with respect to ultraviolet rays having a wavelength of 365 nm, and an Abbe number of 60.0 or more and 62.0 or less. Item 2. The ultraviolet irradiation device according to Item 1. A recording head that discharges ultraviolet curable ink while moving in a reciprocating direction that intersects the conveyance direction of the recording medium; and
An elliptical reflector having a cross-sectional shape of an elliptical arc having a pair of ends on a line passing through one focal point and extending in the minor axis direction and including the other focal point, and an ultraviolet light source disposed at the other focal point And an ultraviolet irradiation unit that irradiates ultraviolet rays to the ultraviolet curable ink ejected from the recording head and attached to the recording medium, the condenser lens having an incident-side focal point at the one focal point. A recording apparatus comprising:

Images