Light irradiation unit, printing device, and printing system

Abstract

To provide a technology which uses a light irradiation unit having a light convergent lens and can suppress a turbulence of air current by the light convergent lens between a light irradiation unit and a printing medium.SOLUTION: A light irradiation unit 30 has a housing 31, a light source 32, a light convergent lens 33, and a light transmissive member 34. On a lower surface 311 of the housing 31, an opening 312 is formed. The light source 32 and the light convergent lens 33 are arranged inside the housing 31. The light transmissive member 34 is arranged at the opening 312 of the housing 31. The light convergent lens 33 converges light emitted by the light source 32. The light transmissive member 34 transmits light converged by the light convergent lens 33. The light transmissive member 34 has a flat lower surface. Thus, occurrence of a turbulence of an air current by the light convergent lens 33 between the light irradiation unit 30 and the printing medium 9 can be suppressed.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a light irradiation unit, a printing device, and a printing system. [Background technology]

[0002] Conventionally, there has been known a printing system that prints on the surface of a strip-shaped print medium by ejecting ink onto the print medium from multiple ejection heads while the print medium is being transported. This type of printing system may use photocurable ink that hardens when exposed to light such as ultraviolet light. In this case, after the ink is ejected onto the print medium from the ejection heads, the ink is irradiated with light. This hardens the ink and fixes it to the print medium.

[0003] Conventional printing systems using photocurable inks are described in, for example, Patent Documents 1 and 2. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-020481 [Patent Document 2] Patent Publication No. 2021-049655 Summary of the Invention [Problem to be solved by the invention]

[0005] In such printing systems, there is a demand for faster printing processes. To speed up printing processes, it is necessary to transport the print medium at high speed. In this case, it is also necessary to increase the amount of light per unit area irradiated onto the print medium in order to cure the ink. For example, it is conceivable to converge the light emitted from a light source using a light converging lens and irradiate the upper surface of the print medium.

[0006] However, as the print medium moves, an air current flows downstream in the transport direction near the top surface of the print medium, and this air current contains a fine mist of ink that is generated as the ink is ejected from the ejection head.

[0007] If a converging lens is placed opposite the top surface of the print medium, the convex surface of the converging lens will disrupt the airflow, causing the ink mist contained in the airflow to adhere to the underside of the ejection head. If the adhered mist accumulates and grows into relatively large droplets, there is a risk that they will drip onto the top surface of the print medium.

[0008] The present invention has been developed in consideration of these circumstances, and aims to provide a technology that uses a light irradiation unit having a light converging lens and can suppress the occurrence of air flow disturbances caused by the light converging lens between the light irradiation unit and the printing medium. [Means for solving the problem]

[0009] The first invention of the present application is a light irradiation unit that irradiates light onto photocurable ink supplied to a printing medium, the light irradiation unit comprising: a housing having an opening formed on its bottom surface; a light source disposed within the housing; a light converging lens disposed within the housing for converging the light emitted from the light source; and a light-transmitting member disposed in the opening of the housing for transmitting the light converged by the light converging lens, the light-transmitting member having a flat bottom surface. The light emitted from the light source and transmitted through the light converging lens and the light-transmitting member forms a spot of a predetermined area on the surface of the printing medium, and the height positions of the light source and the light converging lens are higher than the height positions of the light source and the light converging lens when the spot of the predetermined area is formed on the printing medium in the absence of the light-transmitting member. .

[0011] The first part of this application 2 The invention First Invention In the light irradiation unit, the lower surface of the light-transmitting member and the lower surface of the housing are located on the same or substantially the same plane.

[0012] The first part of this application 3 The invention is the first invention or the second invention In the light irradiation unit, the light converging lens is a rod lens that extends parallel to the bottom surface of the housing.

[0013] The first part of this application4 The invention is a printing system, comprising: a transport mechanism that transports a print medium along a predetermined transport path; an ejection head that ejects photocurable ink from a plurality of ink ejection ports onto the print medium transported by the transport mechanism; a first base portion that supports the ejection head; and 3 The present invention comprises a light irradiation unit according to any one of the preceding inventions and a second base portion supporting the light irradiation unit, wherein the light irradiation unit irradiates light onto the printing medium downstream of the ejection head on the transport path, and the lower surface of the light-transmitting member and the lower surface of the second base portion are located on the same or approximately the same plane.

[0014] The first part of this application 5 The invention is 4 In the printing system of the invention, the lower surface of the ejection head, the lower surface of the first base portion, the lower surface of the optically transparent member, and the lower surface of the second base portion are positioned on the same or approximately the same plane.

[0015] The first part of this application 6 The invention is a printing device comprising: a transport mechanism that transports a printing medium along a predetermined transport path; an ejection head that ejects photocurable ink from a plurality of ink ejection ports onto the printing medium transported by the transport mechanism; a first base portion that supports the ejection head; and a second base portion that can support a light irradiation unit that irradiates the ink supplied to the printing medium with light via a light converging lens, wherein the second base portion has a base plate with an opening and a light-transmitting member arranged in the opening, and the light-transmitting member has a flat lower surface.

[0016] The first part of this application 7 The invention is 6 A printing device of the invention, wherein when the light irradiation unit is supported on the second base portion, the lower surface of the ejection head, the lower surface of the first base portion, the lower surface of the light-transmitting member, and the lower surface of the second base portion are positioned on the same or approximately the same plane.

[0017] The first part of this application 8 The invention is6 Invention or 7 In the printing device of the invention, the second base portion is located upstream and downstream of the opening in the transport direction of the print medium and has a straightening surface extending in a direction toward the lower surface of the light-transmitting member.

[0018] The first part of this application 9 The invention is a light irradiation unit that irradiates light onto photocurable ink supplied to a printing medium, and includes a light source that emits light, a light converging lens that converges the light emitted from the light source, and rectifying surfaces that are located upstream and downstream of the light converging lens in the conveyance direction of the printing medium and extend in a direction toward the vicinity of the lower end of the light converging lens. The rectifying surface includes a first rectifying surface located upstream of the light converging lens in the transport direction of the print medium and inclined so as to gradually increase in height toward the vicinity of the lower end of the light converging lens, and a second rectifying surface located downstream of the light converging lens in the transport direction of the print medium and inclined so as to gradually increase in height toward the vicinity of the lower end of the light converging lens. .

[0020] The first part of this application 10 The invention is a printing system including a transport mechanism that transports a print medium along a predetermined transport path, an ejection head that ejects photocurable ink from a plurality of ink ejection ports onto the print medium transported by the transport mechanism, a first base portion that supports the ejection head, and a second base portion that supports the ejection head. 9 The device comprises a light irradiation unit of the invention and a second base portion supporting the light irradiation unit, wherein the light irradiation unit irradiates light onto the printing medium downstream of the transport path from the ejection head, and the airflow above the printing medium is guided by the underside of the second base portion and the straightening surface.

[0021] The first part of this application 11 The invention is 10 In the printing system of the invention, the airflow above the printing medium is guided by the lower surface of the ejection head, the lower surface of the first base portion, the lower surface of the second base portion, and the rectifying surface.

[0022] The first part of this application 12The invention is a printing device comprising: a transport mechanism that transports a printing medium along a predetermined transport path; an ejection head that ejects photocurable ink from a plurality of ink ejection ports onto the printing medium transported by the transport mechanism; a first base portion that supports the ejection head; and a second base portion that can support a light irradiation unit that irradiates the ink supplied to the printing medium with light via a light converging lens, wherein the second base portion, when the light irradiation unit is supported, is located upstream and downstream of the light converging lens in the transport direction of the printing medium and has a straightening surface that extends in a direction toward the lower end of the light converging lens. [Effects of the Invention]

[0023] The first to third inventions of this application 5 According to the present invention, a light-transmitting member with a flat underside is placed on the underside of the housing of the light irradiation unit, which makes it possible to prevent the occurrence of turbulence in the air flow between the light irradiation unit and the printing medium due to the light converging lens.

[0024] In particular, 2 Invention ~ 5 According to the present invention, it is possible to further prevent turbulence of the air flow between the light irradiation unit and the printing medium.

[0025] The first part of this application 6 Invention ~ 8 According to the invention, a light-transmitting member with a flat underside is placed in the opening of the second base portion that supports the light irradiation unit, thereby preventing the airflow between the light irradiation unit and the printing medium from being disturbed by the light converging lens.

[0026] In particular, 7 Invention ~ 8 According to the present invention, it is possible to further prevent turbulence of the air flow between the light irradiation unit and the printing medium.

[0027] The first part of this application 9 Invention ~ 11According to the present invention, the rectifying surfaces are provided on the upstream and downstream sides of the light converging lens, which makes it possible to prevent the light converging lens from causing turbulence in the air flow between the light irradiation unit and the printing medium.

[0028] In particular, 10 Invention ~ 11 According to the present invention, it is possible to further prevent turbulence of the air flow between the light irradiation unit and the printing medium.

[0029] The first part of this application 12 According to the present invention, the rectifying surfaces are provided on the upstream and downstream sides of the light converging lens, which makes it possible to prevent the light converging lens from causing turbulence in the air flow between the light irradiation unit and the printing medium. [Brief explanation of the drawings]

[0030] [Figure 1] FIG. 1 illustrates a configuration of a printing system. [Figure 2] FIG. 2 is a control block diagram of the printing system. [Figure 3] 3A and 3B are diagrams illustrating the configuration of a light irradiation unit and a second base portion according to the first embodiment. [Figure 4] FIG. 10 is a diagram showing the arrangement of a light source and a light converging lens in (a) a case where there is no light-transmitting member (comparative example) and (b) a case where there is a light-transmitting member (example). [Figure 5] 10A and 10B are diagrams illustrating the configuration of a light irradiation unit and a second base portion according to a second embodiment. [Figure 6] 10A and 10B are diagrams illustrating the configuration of a light irradiation unit and a second base portion according to a third embodiment. [Figure 7] 10A and 10B are diagrams illustrating the configuration of a light irradiation unit and a second base portion according to a fourth embodiment. [Figure 8] 10A and 10B are diagrams illustrating the configuration of a light irradiation unit and a second base portion according to a fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0031] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0032] <1. Printing system configuration> 1 is a diagram showing the configuration of a printing system 1 according to one embodiment of the present invention. This printing system 1 is an apparatus that prints an image on the surface of a long strip-shaped printing medium 9 by ejecting ink droplets from a plurality of ejection heads 20 toward the printing medium 9 while transporting the printing medium 9. The printing medium 9 may be printing paper or a resin film.

[0033] 1, the printing system 1 includes a transport mechanism 10, five ejection heads 20, two light irradiation units 30, a base unit 40, a fixing unit 50, and a control unit 60. All components except the control unit 60 are housed inside a box-shaped housing 70. Note that, within the printing system 1, the device configured from the transport mechanism 10, the multiple ejection heads 20, and the base unit 40 is an example of the "printing device" of the present invention.

[0034] The transport mechanism 10 transports the print medium 9 in a transport direction that follows its longitudinal direction. The transport mechanism 10 of this embodiment has an unwinding section 11, multiple transport rollers 12, and a winding section 13. The print medium 9 is unwound from the unwinding section 11 and transported along a transport path formed by the multiple transport rollers 12. Each transport roller 12 rotates around an axis that extends perpendicular and horizontal to the transport direction, guiding the print medium 9 downstream along the transport path. The print medium 9 is stretched across the multiple transport rollers 12 under tension. This prevents the print medium 9 from sagging or wrinkling during transport. After transport, the print medium 9 is collected in the winding section 13.

[0035] The five ejection heads 20 are units that eject ink droplets onto the print medium 9 transported by the transport mechanism 10. The five ejection heads 20 are arranged at intervals along the transport direction of the print medium 9. The print medium 9 is transported below the five ejection heads 20 with its printing surface facing upward. A large number of ink ejection orifices are formed on the underside of each ejection head 20. The five ejection heads 20 eject ink of each color - W (white), C (cyan), M (magenta), Y (yellow), and K (black) - from the ink ejection orifices toward the upper surface of the print medium 9. This forms a multicolor image on the upper surface of the print medium 9.

[0036] The ink ejected from the ejection head 20 is photocurable ink. Photocurable ink is ink that is cured by irradiation with light such as ultraviolet light. In the printing system 1 of this embodiment, after the ink is ejected from the ejection head 20 onto the print medium 9, the light irradiation unit 30 and the fixing unit 50 irradiate the ink on the print medium 9 with light to cure it.

[0037] The two light irradiation units 30 are units for irradiating light onto the ink ejected from the ejection head 20 onto the upper surface of the printing medium 9 to semi-cure the ink. In this embodiment, the light irradiation units 30 are arranged downstream of the ejection head 20 that ejects W (white) ink and downstream of the ejection head 20 that ejects K (black) ink.

[0038] Each light irradiation unit 30 irradiates the upper surface of the printing medium 9 being transported by the transport mechanism 10 with light. This causes the light to be irradiated onto the ink adhering to the upper surface of the printing medium 9. The light irradiated from the light irradiation unit 30 contains ultraviolet light in a wavelength range effective for curing the ink. Therefore, when the ink on the printing medium 9 is irradiated with this light, the viscosity of the ink increases.

[0039] However, the amount of light emitted from the light irradiation unit 30 is smaller than the amount of light emitted by the fixing unit 50, which will be described later. As a result, the ink on the print medium 9 is not completely cured. In other words, the light emitted from the light irradiation unit 30 causes the ink of each color on the print medium 9 to become semi-cured, with reduced fluidity. When the ink is semi-cured, the spread of the ink on the print medium 9 is suppressed. Therefore, a decrease in print quality due to ink spreading is less likely to occur in the transport path downstream of the light irradiation unit 30.

[0040] The detailed structure of the light irradiation unit 30 will be described later.

[0041] The base unit 40 is a frame for supporting the five ejection heads 20 and the two light irradiation units 30. The base unit 40 is fixed to the housing 70 of the printing system 1. The base unit 40 has five first base portions 41 and two second base portions 42. The five first base portions 41 and the two second base portions 42 are arranged along the transport direction of the print medium 9.

[0042] The five ejection heads 20 are each attached to a first base portion 41. This supports the five ejection heads 20 and fixes the position of each ejection head 20. The first base portion 41 has a rectangular opening 411 in the center. The ejection heads 20 are fixed to the first base portion 41 with their lower ends fitted into the openings 411. Therefore, the lower surfaces of the ejection heads 20 attached to the first base portion 41 face the printing surface of the print medium 9 without being obstructed by the first base portion 41.

[0043] The two light irradiation units 30 are each attached to the second base portion 42. This supports the two light irradiation units 30 and fixes the positions of the light irradiation units 30. The detailed structure of the second base portion 42 will be described later.

[0044] The fixing unit 50 is a unit that irradiates light onto the semi-cured ink on the print medium 9 to fully cure the ink. The fixing unit 50 is disposed downstream of the five ejection heads 20 and the two light irradiation units 30 on the transport path. The fixing unit 50 has a metal halide lamp 51 and a reflector 52. The light emitted from the metal halide lamp 51 is irradiated onto the ink on the print medium 9 either directly or after being reflected by the reflector 52.

[0045] The light emitted from the metal halide lamp 51 contains ultraviolet rays in a wavelength band effective for curing ink. The light emitted from the metal halide lamp 51 also has a sufficient amount of light to completely cure the ink. Therefore, when light is irradiated from the metal halide lamp 51 onto the ink on the printing medium 9, the ink is sufficiently cured and fixed to the printing medium 9.

[0046] Thereafter, the print medium 9 that has passed through the fixing unit 50 passes through a plurality of transport rollers 12 and is collected into a winding section 13.

[0047] The control unit 60 is a unit for controlling the operation of each part of the printing system 1. Fig. 2 is a control block diagram of the printing system 1. The control unit 60 is composed of a computer having a processor 61 such as a CPU, a memory 62 such as RAM, and a storage unit 63 such as a hard disk drive. A computer program P for controlling the operation of the printing system 1 is stored in the storage unit 63.

[0048] The control unit 60 is also electrically connected to the above-mentioned transport mechanism 10, five ejection heads 20, two light irradiation units 30, and fixing unit 50. The control unit 60 temporarily reads out a computer program P stored in a storage unit 63 into a memory 62, and the processor 61 performs arithmetic processing based on the computer program P, thereby controlling the operation of each of the above-mentioned units. In this way, the printing process in the printing system 1 progresses.

[0049] The control unit 60 is also electrically connected to a server 2 installed outside the printing system 1. Image data D to be printed is stored in the server 2. During printing processing, the print medium 9 is transported by the transport mechanism 10, and the control unit 60 reads out the specified image data D from the server 2 and ejects ink of each color from each ejection head 20 based on the image data D. As a result, an image corresponding to the image data D is recorded on the printing surface of the print medium 9.

[0050] 2. Configuration of the Light Irradiation Unit and the Second Base Portion Next, the detailed structures of the above-mentioned light irradiation unit 30 and second base portion 42 will be described.

[0051] <2-1. First embodiment> Fig. 3 is a diagram showing the configuration of the light irradiation unit 30 and the second base part 42 according to the first embodiment. In Fig. 3, the light irradiation unit 30 attached to the second base part 42 is shown by a solid line, and the light irradiation unit 30 detached from the second base part 42 is shown by a virtual line (two-dot chain line). As shown in Fig. 3, the light irradiation unit 30 has a housing 31, a light source 32, a light converging lens 33, and a light-transmitting member 34.

[0052] The housing 31 is a casing that houses the light source 32 and the light converging lens 33. The housing 31 has a flat bottom surface 311. The bottom surface 311 of the housing 31 is disposed approximately parallel to the top surface of the print medium 9 transported by the transport mechanism 10. An opening 312 is formed in the bottom surface 311 of the housing 31. The opening 312 is a through-hole that passes through the bottom surface 311 of the housing 31 in the vertical direction.

[0053] The light source 32 is disposed inside the housing 31. The light source 32 is fixed to the housing 31. For example, a plurality of LEDs (Light Emitting Diodes) are used as the light source 32. The plurality of LEDs are arranged along the width direction of the print medium 9. When a current is supplied to the light source 32 from the control unit 60, the light source 32 emits light. Then, light is emitted downward from the light source 32. The light emitted from the light source 32 contains ultraviolet light for curing the ink.

[0054] The converging lens 33 is a lens for converging the light emitted from the light source 32. The converging lens 33 is disposed below the light source 32 inside the housing 31. The converging lens 33 is fixed to the housing 31. A rod-shaped lens is used for the converging lens 33. The converging lens 33 is disposed horizontally along the width direction of the print medium 9. In other words, the converging lens 33 is disposed in a position parallel to the bottom surface 311 of the housing 31. As shown in FIG. 3, the bottom surface of the converging lens 33 is a convex surface that protrudes downward.

[0055] The light-transmitting member 34 is a transparent plate placed in the opening 312 of the housing 31. The light-transmitting member 34 is fixed to the housing 31. The light-transmitting member 34 has a flat upper surface and a flat lower surface. Light emitted from the light source 32 and converged by the light converging lens 33 passes through the light-transmitting member 34 and is irradiated onto the upper surface of the print medium 9.

[0056] 4A and 4B are diagrams showing the arrangement of the light source 32 and the light converging lens 33 in the case where the light-transmitting member 34 is not present (comparative example) and the case where the light-transmitting member 34 is present (example). In order to properly cure the ink, it is necessary to properly manage the amount of light per unit area irradiated onto the upper surface of the printing medium 9. To do this, it is necessary to keep the area S of the spot formed on the upper surface of the printing medium 9 by the light emitted from the light source 32 and converged by the light converging lens 33 constant.

[0057] If the light-transmitting member 34 is added without changing the height positions of the light source 32 and the light-converging lens 33, as shown in FIG. 4(a), the area S' of the spot formed on the upper surface of the print medium 9 will be larger than the normal area S, as shown by the imaginary line (two-dot chain line) in FIG. 4(a). For this reason, when the light-transmitting member 34 is provided, the height positions of the light source 32 and the light-converging lens 33 are made higher than the height positions in FIG. 4(a), as shown in FIG. 4(b). This makes it possible to form a spot of appropriate area S on the upper surface of the print medium 9. This allows the ink on the print medium 9 to be cured satisfactorily.

[0058] Returning to FIG. 3 , the second base portion 42 has a base plate 43 and a wall portion 44. The base plate 43 extends parallel to the upper surface of the printing medium 9. The base plate 43 has a rectangular opening 431 in its center. The opening 431 is a through-hole that passes through the base plate 43 in the vertical direction. The wall portion 44 extends upward from the edge of the opening 431 of the base plate 43. The light irradiation unit 30 is inserted inside the wall portion 44. Then, with the lower end of the housing 31 fitted into the opening 431, the housing 31 is fixed to the second base portion 42. As a result, the lower surface of the light irradiation unit 30 and the upper surface of the printing medium 9 face each other in the vertical direction with a gap between them.

[0059] When printing is performed in the printing system 1, the printing medium 9 is transported downstream in the transport direction. As the printing medium 9 moves, an airflow F (viscous flow) is generated in the space between the light irradiation unit 30 and the printing medium 9, flowing downstream in the transport direction. When ink droplets are ejected from the ejection openings of the ejection head 20, mist smaller than the droplets is generated. The airflow F contains such fine mist of ink. Therefore, if the airflow F becomes turbulent, the ink mist contained in the airflow F will adhere to the bottom surface of the ejection head 20, the bottom surface of the light irradiation unit 30, the bottom surface of the base unit 40, and the like. If the adhering mist accumulates and becomes relatively large droplets, there is a risk that they will drip onto the top surface of the printing medium 9.

[0060] In this regard, in the light irradiation unit 30 of this embodiment, a light-transmitting member 34 is disposed on the lower surface 311 of the housing 31. The lower surface of the light-transmitting member 34 is a flat surface parallel to the upper surface of the print medium 9. In this way, the light converging lens 33 is not exposed on the lower surface of the light irradiation unit 30, and therefore, the convex shape of the light converging lens 33 can be prevented from causing turbulence in the airflow F between the light irradiation unit 30 and the print medium 9. This makes it possible to prevent ink mist from adhering to the lower surface of the ejection head 20, the lower surface of the light irradiation unit 30, the lower surface of the base unit 40, and the like due to turbulence in the airflow F.

[0061] In particular, in this embodiment, the lower surface of the light-transmitting member 34 and the lower surface 311 of the housing 31 are arranged on the same plane. In this way, no step is created at the boundary between the lower surface of the light-transmitting member 34 and the lower surface 311 of the housing 31. Therefore, it is possible to prevent turbulence of the airflow F due to a step between the light irradiation unit 30 and the print medium 9. Note that the lower surface of the light-transmitting member 34 and the lower surface 311 of the housing 31 may be arranged on approximately the same plane. In other words, there may be a very slight step (for example, equal to or less than the thickness of the light-transmitting member 34) at the boundary between the lower surface of the light-transmitting member 34 and the lower surface 311 of the housing 31.

[0062] Furthermore, in this embodiment, the lower surface of the light-transmitting member 34, the lower surface 311 of the housing 31, and the lower surface of the second base portion 42 are arranged on the same plane. In this way, no step is created at the boundary between the lower surface of the light-transmitting member 34 and the lower surface 311 of the housing 31, nor at the boundary between the lower surface 311 of the housing 31 and the lower surface of the second base portion 42. Therefore, it is possible to further prevent turbulence of the airflow F caused by a step between the light irradiation unit 30 and the printing medium 9.

[0063] The lower surface of the light-transmitting member 34, the lower surface 311 of the housing 31, and the lower surface of the second base portion 42 may be disposed on approximately the same plane. That is, a slight step (for example, equal to or smaller than the thickness of the light-transmitting member 34) may exist at the boundary between the lower surface of the light-transmitting member 34 and the lower surface 311 of the housing 31, or at the boundary between the lower surface of the housing 31 and the lower surface of the second base portion 42.

[0064] Furthermore, it is more desirable that the underside of the ejection head 20, the underside of the first base portion 41, the underside of the light-transmitting member 34, the underside 311 of the housing 31, and the underside of the second base portion 42 are all disposed on the same plane. In this way, no steps are created at the boundary between the underside of the ejection head 20 and the underside of the first base portion 41, or at the boundary between the underside of the first base portion 41 and the underside of the second base portion 42. Therefore, it is possible to further prevent turbulence of the airflow F due to steps between the ejection head 20 and the light irradiation unit 30 and the print medium 9.

[0065] Furthermore, the first base portion 41 on which the ejection head 20 that ejects at least K (black) ink is attached and the second base portion 42 on which the light irradiation unit 30 is attached immediately downstream thereof may be formed as an integrated member or as separate members. Furthermore, the first base portion 41 on which the application head 20 that ejects W (white) ink is attached and the second base portion 42 on which the light irradiation unit 30 is attached immediately downstream thereof may be formed as an integrated member or as separate members. Furthermore, the first base portion 41 on which the application heads 20 of all colors are attached and the second base portion 42 on which all light irradiation units 30 are attached may be formed as an integrated member or as separate members.

[0066] The lower surface of the ejection head 20, the lower surface of the first base portion 41, the lower surface of the light-transmitting member 34, the lower surface 311 of the housing 31, and the lower surface of the second base portion 42 may be arranged on approximately the same plane. In other words, there may be a very slight step (for example, equal to or smaller than the thickness of the light-transmitting member 34) at the boundary between these portions.

[0067] <2-2. Second embodiment> Next, a second embodiment will be described. Fig. 5 is a diagram showing the configuration of a light irradiation unit 30 and a second base part 42 according to the second embodiment. In Fig. 5, the light irradiation unit 30 attached to the second base part 42 is shown by a solid line, and the light irradiation unit 30 detached from the second base part 42 is shown by a virtual line (two-dot chain line).

[0068] 5, the light irradiation unit 30 of this embodiment includes a housing 31, a light source 32, and a light converging lens 33. The light irradiation unit 30 irradiates light emitted from the light source 32 downward via the light converging lens 33. However, while the light irradiation unit 30 of the first embodiment includes the light-transmitting member 34, the light irradiation unit 30 of this second embodiment does not include the light-transmitting member 34. Therefore, the convex lower surface of the light converging lens 33 is exposed to the lower surface of the light irradiation unit 30.

[0069] On the other hand, the second base portion 42 of this embodiment has a base plate 43, a wall portion 44, and a light-transmitting member 45. The base plate 43 extends parallel to the upper surface of the print medium 9. The base plate 43 has a rectangular opening 431 in the center. The opening 431 is a through-hole that passes through the base plate 43 in the vertical direction. The wall portion 44 extends upward from the base plate 43. The light-transmitting member 45 is a transparent plate that is placed in the opening 431 of the base plate 43. The light-transmitting member 45 is fixed to the base plate 43. The light-transmitting member 45 has a flat upper surface and a flat lower surface.

[0070] The light irradiation unit 30 is fixed to the wall portion 44 with the lower end of the housing 31 inserted inside the wall portion 44. This results in the light converging lens 33 being disposed above and spaced apart from the light-transmitting member 45. Light emitted from the light source 32 and converged by the light converging lens 33 passes through the light-transmitting member 34 and is irradiated onto the upper surface of the print medium 9.

[0071] In the configuration of this embodiment, the light-transmitting member 45 is also disposed so as to face the upper surface of the print medium 9. The lower surface of the light-transmitting member 45 is a flat surface parallel to the upper surface of the print medium 9. The light-converging lens 33 is not exposed to the space where the airflow F is formed. Therefore, the convex shape of the light-converging lens 33 can prevent turbulence of the airflow F from occurring between the light irradiation unit 30 and the print medium 9.

[0072] In the example of FIG. 5, there is a slight step at the boundary between the lower surface of the light-transmitting member 45 and the lower surface of the second base portion 42, but the height of the step is smaller than the thickness of the light-transmitting member 45. In this way, it is desirable that the lower surface of the light-transmitting member 45 and the lower surface of the second base portion 42 are arranged on approximately the same plane. This makes it possible to suppress turbulence of the airflow F due to the step. Note that the light-transmitting member 45 may be fitted into the opening 431 of the second base portion 42 so that the lower surface of the light-transmitting member 45 and the lower surface of the second base portion 42 are arranged on the same plane. In this way, it is possible to further suppress turbulence of the airflow F due to the step.

[0073] It is also more desirable that the lower surface of the ejection head 20, the lower surface of the first base portion 41, the lower surface of the light-transmitting member 45, and the lower surface of the second base portion 42 are arranged on the same or substantially the same plane. This can reduce steps at the boundaries between the above-mentioned portions. Therefore, it is possible to further reduce turbulence of the airflow F due to steps.

[0074] <2-3. Third embodiment> Next, a third embodiment will be described. Fig. 6 is a diagram showing the configuration of a light irradiation unit 30 and a second base part 42 according to the third embodiment. In Fig. 6, the light irradiation unit 30 attached to the second base part 42 is shown by a solid line, and the light irradiation unit 30 detached from the second base part 42 is shown by a virtual line (two-dot chain line).

[0075] The light irradiation unit 30 in Figure 6 is equivalent to the light irradiation unit 30 in Figure 5. The second base part 42 in Figure 6 differs from the second base part 42 in Figure 5 only in that it has a first rectifying surface 461 and a second rectifying surface 462.

[0076] The first rectifying surface 461 is provided on the upstream side of the opening 431 of the base plate 43. The first rectifying surface 461 extends in a direction from the lower surface of the second base portion 42 toward the lower surface of the light-transmitting member 45 exposed in the opening 431. The first rectifying surface 461 is inclined so that its height gradually increases toward the downstream side in the transport direction of the print medium 9.

[0077] The second rectifying surface 462 is provided on the downstream side of the opening 431 of the base plate 43. The second rectifying surface 462 extends in a direction from the lower surface of the second base portion 42 toward the lower surface of the light-transmitting member 45 exposed in the opening 431. The second rectifying surface 462 is inclined so that its height gradually increases toward the upstream side in the transport direction of the print medium 9.

[0078] By providing such a first rectifying surface 461 and a second rectifying surface 462, the step at the boundary between the lower surface of the light-transmitting member 45 and the lower surface of the second base portion 42 becomes gentler. This makes it possible to further suppress turbulence of the airflow F at the boundary between the lower surface of the light-transmitting member 45 and the lower surface of the second base portion 42. This makes it possible to further suppress adhesion of ink mist to the lower surface of the ejection head 20, the lower surface of the light irradiation unit 30, the lower surface of the base unit 40, and the like due to turbulence of the airflow F.

[0079] <2-4. Fourth embodiment> Next, a fourth embodiment will be described. Fig. 7 is a diagram showing the configuration of a light irradiation unit 30 and a second base part 42 according to the fourth embodiment. In Fig. 7, the light irradiation unit 30 attached to the second base part 42 is shown by a solid line, and the light irradiation unit 30 detached from the second base part 42 is shown by a virtual line (two-dot chain line).

[0080] 7, the light irradiation unit 30 of this embodiment has a housing 31, a light source 32, and a light converging lens 33. The light irradiation unit 30 of this embodiment does not have a light-transmitting member 34. Therefore, the convex lower surface of the light converging lens 33 is exposed at the lower surface of the light irradiation unit 30. The light irradiation unit 30 irradiates the upper surface of the print medium 9 with light emitted from the light source 32 via the light converging lens 33.

[0081] In the fourth embodiment, the light irradiation unit 30 has a first rectifying member 35 and a second rectifying member 36. The first rectifying member 35 and the second rectifying member 36 are fixed to the lower surface of the housing 31.

[0082] The first rectifying member 35 has a first rectifying surface 351. The first rectifying surface 351 is located upstream of the light converging lens 33 in the transport direction of the print medium 9. The first rectifying surface 351 extends from the lower surface of the first rectifying member 35 toward the vicinity of the lower end of the light converging lens 33. The first rectifying surface 351 is inclined so that its height gradually increases toward the vicinity of the lower end of the light converging lens 33.

[0083] The second rectifying member 36 has a second rectifying surface 361. The second rectifying surface 361 is located downstream of the light converging lens 33 in the transport direction of the print medium 9. The second rectifying surface 361 extends from the lower surface of the second rectifying member 36 toward the vicinity of the lower end of the light converging lens 33. The second rectifying surface 361 is inclined so that its height gradually increases toward the vicinity of the lower end of the light converging lens 33.

[0084] On the other hand, the second base portion 42 of this embodiment has a base plate 43 and a wall portion 44. The base plate 43 extends parallel to the upper surface of the printing medium 9. The base plate 43 has a rectangular opening 431 in the center. The opening 431 is a through-hole that passes through the base plate 43 in the up-down direction. The wall portion 44 extends upward from the edge of the opening 431 of the base plate 43. The light irradiation unit 30 is inserted inside the wall portion 44. Then, with the lower end of the housing 31 fitted into the opening 431, the housing 31 is fixed to the second base portion 42.

[0085] By providing the first rectifying surface 351 and the second rectifying surface 361 on the underside of the light irradiation unit 30 as in this embodiment, the step at the boundary between the underside of the light converging lens 33 and the underside of the second base portion 42 can be reduced. The airflow F over the print medium 9 is guided by the underside of the ejection head 20, the underside of the first base portion 41, the underside of the second base portion 42, the first rectifying surface 351, and the second rectifying surface 361. This makes it possible to suppress turbulence in the airflow F. Therefore, it is possible to suppress adhesion of ink mist to the underside of the ejection head 20, the underside of the light irradiation unit 30, the underside of the base unit 40, etc., due to turbulence in the airflow F.

[0086] 7, the first rectifying surface 351 and the second rectifying surface 361 are inclined so that their heights gradually increase toward the vicinity of the lower end of the light converging lens 33. However, when the lower end of the light converging lens 33 is located lower than the lower surface of the base plate 43, the first rectifying surface 351 and the second rectifying surface 361 may be inclined so that their heights gradually decrease toward the vicinity of the lower end of the light converging lens 33.

[0087] <2-5. Fifth embodiment> Next, a fifth embodiment will be described. Fig. 8 is a diagram showing the configuration of a light irradiation unit 30 and a second base part 42 according to the fifth embodiment. In Fig. 8, the light irradiation unit 30 attached to the second base part 42 is shown by a solid line, and the light irradiation unit 30 detached from the second base part 42 is shown by a virtual line (two-dot chain line).

[0088] 8, the light irradiation unit 30 of this embodiment has a housing 31, a light source 32, and a light converging lens 33. The light irradiation unit 30 of this embodiment does not have a light-transmitting member 34. Therefore, the convex lower surface of the light converging lens 33 is exposed at the lower surface of the light irradiation unit 30. The light irradiation unit 30 irradiates the upper surface of the print medium 9 with light emitted from the light source 32 via the light converging lens 33.

[0089] On the other hand, the second base portion 42 of the present embodiment has a base plate 43 and a wall portion 44. The base plate 43 has a rectangular opening 431 in the center. The opening 431 is a through-hole that passes through the base plate 43 in the vertical direction. The wall portion 44 extends upward from the base plate 43.

[0090] The light irradiation unit 30 is fixed to the second base portion 42 with the lower end of the housing 31 inserted inside the wall portion 44 and placed on the upper surface of the base plate 43. The light converging lens 33 is placed in the opening 431 of the base plate 43. This causes the light converging lens 33 and the upper surface of the print medium 9 to face each other in the vertical direction with a gap between them.

[0091] In the fourth embodiment, the lower surface of the base plate 43 includes a first flow rectifying surface 461 and a second flow rectifying surface 462.

[0092] The first rectifying surface 461 is provided on the upstream side of the opening 431 of the base plate 43. That is, the first rectifying surface 461 is located on the upstream side of the light converging lens 33 when the light irradiation unit 30 is supported on the second base portion 42. The first rectifying surface 461 extends in a direction from the lower surface of the second base portion 42 toward the vicinity of the lower end of the light converging lens 33 exposed in the opening 431. The first rectifying surface 461 is inclined so that its height gradually increases toward the vicinity of the lower end of the light converging lens 33.

[0093] The second rectifying surface 462 is provided on the downstream side of the opening 431 of the base plate 43. That is, the second rectifying surface 462 is located on the downstream side of the light converging lens 33 when the light irradiation unit 30 is supported on the second base part 42. The second rectifying surface 462 extends in a direction from the lower surface of the second base part 42 toward the vicinity of the lower end of the light converging lens 33 exposed in the opening 431. The second rectifying surface 462 is inclined so that its height gradually increases toward the vicinity of the lower end of the light converging lens 33.

[0094] By providing such a first rectifying surface 461 and a second rectifying surface 462, it is possible to reduce the step at the boundary between the lower surface of the light converging lens 33 and the lower surface of the second base portion 42. The airflow F over the printing medium 9 is guided by the lower surface of the ejection head 20, the lower surface of the first base portion 41, the lower surface of the second base portion 42, the first rectifying surface 461, and the second rectifying surface 462. This makes it possible to suppress turbulence in the airflow F. Therefore, it is possible to suppress adhesion of ink mist to the lower surface of the ejection head 20, the lower surface of the light irradiation unit 30, the lower surface of the base unit 40, and the like due to turbulence in the airflow F.

[0095] 8, the first rectifying surface 461 and the second rectifying surface 462 are inclined so that their heights gradually increase toward the vicinity of the lower end of the light converging lens 33. However, when the lower end of the light converging lens 33 is located at a position lower than the lower surface of the base plate 43, the first rectifying surface 461 and the second rectifying surface 462 may be inclined so that their heights gradually decrease toward the vicinity of the lower end of the light converging lens 33.

[0096] <3. Modifications> Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments.

[0097] The light irradiation unit 30 in the above embodiment semi-cures the ink supplied to the printing medium 9. However, the light irradiation unit 30 of the present invention may also fully cure the ink supplied to the printing medium 9.

[0098] Furthermore, the printing system 1 in the above embodiment includes five ejection heads 20. However, the number of ejection heads included in the printing system may be one to four, or may be six or more. For example, the printing system may include ejection heads that eject ink of a special color in addition to the colors W, C, M, Y, and K. The printing system may also include an ejection head that ejects a primer ink to improve the wettability of the printing medium. Furthermore, each ejection head may be composed of multiple heads arranged in the width direction of the printing medium.

[0099] Furthermore, the printing system 1 of the above embodiment includes two light irradiation units 30. However, the number of light irradiation units 30 included in the printing system may be one, or may be three or more. For example, a light irradiation unit 30 may be disposed only downstream of the most downstream ejection head 20. Alternatively, a light irradiation unit 30 may be disposed downstream of each of all of the ejection heads 20.

[0100] Furthermore, the printing system 1 of the above embodiment prints on a continuous, long strip of printing medium 9. However, the printing system of the present invention may also print on a plurality of printing media while transporting the printing media sequentially.

[0101] Furthermore, the detailed shapes of the light irradiation unit, the printing device, and the printing system may differ from those shown in the drawings of the present application. Furthermore, the elements appearing in the above-described embodiments and modifications may be combined as appropriate within the scope of not causing any contradiction. [Explanation of symbols]

[0102] 1 Printing System 9 Print media 10. Conveying mechanism 20 Discharge head 30 Light irradiation unit 31 Case 32 light source 33 Light converging lens 34 Light-transmitting member 35 First straightening member 36 Second straightening member 40 base units 41 First base part 42 Second base part 43 Base Plate 44 Wall 45 Light-transmitting material 50 Fuser unit 60 Control Unit 311 Underside of the housing 312 Housing opening 351 1st rectification surface 361 2nd rectifying surface 411 First base opening 431 Second base opening 461 1st rectification surface 462 2nd rectifying surface F airflow S Spot area

Claims

1. A light irradiation unit that irradiates light onto photocurable ink supplied to a printing medium, a housing having an opening formed on the bottom surface; a light source disposed within the housing; a light converging lens disposed within the housing and configured to converge the light emitted from the light source; a light-transmitting member disposed at the opening of the housing and transmitting light converged by the light converging lens; and the light-transmitting member has a flat lower surface; the light emitted from the light source and transmitted through the light converging lens and the light-transmitting member forms a spot of a predetermined area on the surface of the printing medium; A light irradiation unit in which the height positions of the light source and the light converging lens are higher than the height positions of the light source and the light converging lens when forming a spot of the specified area on the printing medium in the absence of the light-transmitting member.

2. The light irradiation unit according to claim 1 , A light irradiation unit, wherein a lower surface of the light-transmitting member and a lower surface of the housing are located on the same or substantially the same plane.

3. 3. The light irradiation unit according to claim 1 or 2, The light-illuminating unit, wherein the light-converging lens is a rod lens extending parallel to the bottom surface of the housing.

4. a transport mechanism that transports the print medium along a predetermined transport path; an ejection head that ejects photocurable ink from a plurality of ink ejection ports onto the print medium transported by the transport mechanism; a first base portion that supports the ejection head; The light irradiation unit according to any one of claims 1 to 3; a second base portion that supports the light irradiation unit; Equipped with the light irradiation unit irradiates the print medium with light downstream of the ejection head along the transport path; A printing system, wherein a lower surface of the optically transparent member and a lower surface of the second base portion are positioned on the same or substantially the same plane.

5. 5. The printing system according to claim 4, A printing system, wherein a lower surface of the ejection head, a lower surface of the first base portion, a lower surface of the optically transparent member, and a lower surface of the second base portion are positioned on the same or substantially the same plane.

6. a transport mechanism that transports the print medium along a predetermined transport path; an ejection head that ejects photocurable ink from a plurality of ink ejection ports onto the print medium transported by the transport mechanism; a first base portion that supports the ejection head; a second base portion capable of supporting a light irradiation unit that irradiates the ink supplied to the printing medium with light via a light converging lens; Equipped with The second base portion is a base plate having an opening; a light-transmitting member disposed in the opening; and The printing device, wherein the optically transparent member has a flat lower surface.

7. 7. The printing device according to claim 6, a printing device in which, when the light irradiation unit is supported on the second base portion, the lower surface of the ejection head, the lower surface of the first base portion, the lower surface of the light-transmitting member, and the lower surface of the second base portion are positioned on the same or approximately the same plane.

8. 8. The printing device according to claim 6 or claim 7, The second base portion is a straightening surface located on the upstream side and downstream side of the opening in the transport direction of the print medium and extending in a direction toward the lower surface of the light-transmitting member; A printing device comprising:

9. A light irradiation unit that irradiates light onto photocurable ink supplied to a printing medium, A light source that emits light; a light converging lens that converges the light emitted from the light source; a straightening surface located on the upstream side and downstream side of the light converging lens in the conveyance direction of the print medium, the straightening surface extending in a direction toward the vicinity of the lower end of the light converging lens; and The flow straightening surface is a first rectifying surface that is located upstream of the light converging lens in the conveyance direction of the print medium and that is inclined so that its height gradually increases toward the lower end of the light converging lens; a second rectifying surface that is located downstream of the light converging lens in the conveyance direction of the print medium and that is inclined so that its height gradually increases toward the lower end of the light converging lens; A light irradiation unit comprising:

10. a transport mechanism that transports the print medium along a predetermined transport path; an ejection head that ejects photocurable ink from a plurality of ink ejection ports onto the print medium transported by the transport mechanism; a first base portion that supports the ejection head; The light irradiation unit according to claim 9 ; a second base portion that supports the light irradiation unit; Equipped with the light irradiation unit irradiates the print medium with light downstream of the ejection head along the transport path; A printing system, wherein the airflow over the printing medium is guided by the lower surface of the second base portion and the rectifying surface.

11. 11. The printing system of claim 10, A printing system in which the airflow over the printing medium is guided by the lower surface of the ejection head, the lower surface of the first base portion, the lower surface of the second base portion, and the rectifying surface.

12. a transport mechanism that transports the print medium along a predetermined transport path; an ejection head that ejects photocurable ink from a plurality of ink ejection ports onto the print medium transported by the transport mechanism; a first base portion that supports the ejection head; a second base portion capable of supporting a light irradiation unit that irradiates the ink supplied to the printing medium with light via a light converging lens; Equipped with The second base portion is When the light irradiation unit is supported, straightening surfaces are located on the upstream and downstream sides of the light converging lens in the transport direction of the print medium, and extend in a direction toward the vicinity of the lower end of the light converging lens. A printing device comprising:

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