JP2014184666A - Image recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique capable of effectively preventing incidence of the light from an irradiation part onto the nozzle formation surface of a print head which discharges a photocurable liquid.SOLUTION: An image recording device is provided with: a print head 36 having a nozzle formation surface 362 in which a nozzle 361 for discharging a photocurable liquid to a recording medium S is provided; and an irradiation part 37 having a housing 38 regulating an opening 381 facing the recording medium S by tops 384a and 385a of the protrusions 384 and 385 protruded from an inner wall face 383a, and a light source 39 contained in the housing 38. The device has a head side protrusion 384 positioning between the nozzle formation surface 362 and an opening 381 in an arrangement direction Ds in which the print head 36 and the irradiation part 37 get lined up, and has a low reflection part onto which a light directly incident from the light source 39 to the recording medium S through the opening 381 and regularly reflected to the side of the head 36 in the arrangement direction Ds is incident, in a facing a surface 384b facing the recording medium S of the head side protrusion 384.

Description

  The present invention relates to an image recording apparatus that performs image recording by irradiating light onto a photocurable liquid ejected from a nozzle of a print head toward a recording medium, and the liquid attached to the nozzle formation surface of the print head is cured. It is related with the technique which suppresses this.

  2. Description of the Related Art Conventionally, there has been known an image recording apparatus such as an ink jet printer that performs image recording by ejecting a photocurable liquid from a nozzle of a print head toward a recording medium and irradiating and curing the liquid attached to the recording medium. It has been. In such an apparatus, a part of the liquid ejected from the nozzle may adhere to the nozzle formation surface of the print head. When the liquid adhering to the nozzle formation surface is irradiated with light, the liquid is cured on the nozzle formation surface, which may adversely affect image recording. In view of this, various techniques have been proposed for suppressing the irradiation of light onto the nozzle formation surface of the print head when image recording is performed using a photocurable liquid.

  For example, in the ink jet printers of Patent Document 1 and Patent Document 2, light is prevented from entering the nozzle forming surface by appropriately defining the interval between the print head and the irradiation unit. Specifically, among the light directly incident on the recording medium through the opening from the light source disposed in the housing having the opening, the print head is configured so that the light regularly reflected on the recording medium does not enter the nozzle forming surface. And the distance between the irradiating part is defined.

Japanese Patent No. 4259098 Japanese Patent No. 4309688

  By the way, among the light emitted from the light source, the direct incident light that directly enters the recording medium through the opening and the casing that passes through the opening and is incident on the recording medium after being reflected by the inner wall surface of the casing. There is internal reflection light. Therefore, in order to suppress the hardening of the liquid adhering to the nozzle formation surface, it is important to suppress the incidence on the nozzle formation surface with respect to both the direct incident light and the reflected light in the housing. On the other hand, Patent Documents 1 and 2 do not particularly take into account the reflected light in the housing, and there is a limit to the effect of suppressing the curing of light attached to the nozzle formation surface. In Patent Documents 1 and 2, it is necessary to increase the distance between the print head and the irradiation unit by a predetermined distance or more, and it is difficult to reduce the size of the apparatus.

  This invention is made in view of the said subject, and provides the technique which can suppress effectively that the light from an irradiation part injects into the nozzle formation surface of the print head which discharges a photocurable liquid. With the goal.

  In order to achieve the above object, an image recording apparatus according to the present invention includes a print head having a nozzle forming surface provided with a nozzle for discharging a photocurable liquid toward a recording medium, and a protrusion protruding from an inner wall surface. And a light source that emits light that is contained in the housing and that cures the liquid, and the protrusion includes a print head and a light irradiation unit. The head side protruding portion is located between the nozzle formation surface and the opening in the arrangement direction in which the head side protruding portion is arranged, and the head side protruding portion faces the recording medium directly from the light source through the opening to the recording medium. It is characterized by having a low reflection portion into which light incident and regularly reflected on the print head side in the arrangement direction is incident.

  In the present invention (image recording apparatus), the irradiating unit has a housing provided with an opening facing the recording medium, and a light source accommodated in the housing on the opposite side of the recording medium with respect to the opening. Therefore, the light emitted from the light source is irradiated onto the recording medium through the opening. And in order to suppress incidence to a nozzle formation surface with respect to both the above-mentioned direct incident light and reflected light in a housing | casing, the protrusion part which has a low reflection part is provided. That is, the low reflection part is arranged between the nozzle formation surface and the opening in the arrangement direction in which the print head and the irradiation part are arranged, and the arrangement direction of the direct incident light directly incident on the recording medium from the light source through the opening. The specularly reflected light is incident on the print head side. For this reason, the direct incident light is attenuated by being regularly reflected by the recording medium and then incident on the low reflection portion, and the direct incident light can be prevented from entering the nozzle forming surface. Further, the projecting portion is provided so as to project from the inner wall surface of the housing and define the opening. Therefore, after reflecting off the inner wall surface of the casing, most of the reflected light in the casing heading to the recording medium is blocked by the protrusion before reaching the recording medium, so that the reflected light in the casing enters the nozzle forming surface. Can be suppressed. As described above, in the present invention, by having the projecting portion having the low reflection portion, it is possible to suppress both the direct incident light and the reflected light in the housing from entering the nozzle forming surface, and the light from the irradiation portion forms the nozzle. Incidence on the surface can be effectively suppressed. Further, since it is possible to block both the direct incident light and the reflected light in the casing regardless of the distance between the print head and the irradiation unit, the irradiation unit can be disposed close to the head.

  Incidentally, the reflected light from the recording medium is incident on the facing surface of the head-side protruding portion located between the nozzle forming surface and the opening and facing the recording medium, and then the light is repeatedly reflected and incident on the nozzle forming surface. Cases can also be envisaged. However, in the present invention, since the low reflection portion is provided on the facing surface of the head-side protruding portion, the light traveling toward the facing surface enters the low reflection portion and attenuates. For this reason, it can suppress more reliably that the light reflected on the opposing surface of the head side protrusion part injects into a nozzle formation surface, and is suitable.

  At this time, it is more preferable that the low reflection portion is formed in the entire region of the facing surface. By doing so, the light traveling toward the opposing surface is surely incident on the low reflection portion and attenuated. Therefore, it is possible to more reliably suppress the incidence of light reflected by the facing surface of the head-side protruding portion on the nozzle forming surface.

  Further, the opposing surface may be configured to be an inclined surface extending from the inner wall surface toward the light source side or the recording medium side. When the opposing surface is an inclined surface extending from the inner wall surface toward the light source side, the light incident on the opposing surface after being reflected by the recording medium is easily reflected to the opening side in the arrangement direction. For this reason, the incidence of light on the nozzle forming surface can be suppressed. Further, when the facing surface is an inclined surface extending from the inner wall surface toward the recording medium, the reflected light in the housing is easily reflected toward the inside of the housing. For this reason, the incidence of light on the nozzle forming surface can be suppressed.

  By the way, considering the light that is regularly reflected to the print head side by the recording medium out of the direct incident light, the larger the incident angle to the recording medium, the more the reflected light that is directed toward the nozzle formation surface after being reflected is blocked by the protrusion. It becomes difficult. Therefore, among the light that is directly incident on the recording medium from the light source through the aperture and then specularly reflected on the print head side, the specularly reflected light having the maximum incident angle when entering the recording medium is incident on the opposite surface. It is preferable to be configured as follows. According to such a configuration, the regular reflection light of other light having a smaller incident angle than the light having the maximum incident angle to the recording medium among the directly incident light is reliably incident on the facing surface where the low reflection portion is formed. Can be made. As a result, light incident on the nozzle forming surface can be further suppressed.

More specifically, as will be described in detail later, when a support member having a flat support surface for supporting the recording medium is further provided, it is farthest from the nozzle formation surface in the arrangement direction. The distance in the arrangement direction between the target light source that is the light source and the tip of the head side protrusion is L1, the distance in the arrangement direction between the tip of the head side protrusion and the inner wall surface is L2, and the distance between the target light source and the recording medium The distance is D1, the distance between the tip of the head side protrusion and the recording medium is D2, the distance between the base end of the head side protrusion and the recording medium is D3, and the target light source and the tip of the head side protrusion are What is necessary is just to comprise so that the following (Formula 1) and (Formula 2) may be satisfy | filled, when the incident angle to the recording medium of the light which makes a locus | trajectory the locus | trajectory is set to (theta).
L1 ≦ tan θ · (D1-D2) (Formula 1)
L2 ≧ tan θ · (D2 + D3) (Formula 2)

  In addition, it is preferable to further include a drive mechanism that moves the irradiation unit in the exit / retreat direction with respect to the recording medium. By providing such a driving mechanism, even when various recording media having different thicknesses are used, the distance between the irradiation unit and the recording medium can be reduced by moving the irradiation unit in the retracting direction by the driving mechanism. It can be adjusted appropriately.

  In addition, the print head can be configured to eject liquid that is cured by ultraviolet rays from the nozzle, the light source emits ultraviolet rays as light, and the low reflection portion absorbs ultraviolet rays. According to this configuration, even when a liquid curable by ultraviolet rays is used for image recording, it is possible to suppress the incidence of ultraviolet rays on the nozzle forming surface.

  In addition, it is preferable that a transmissive member that covers the opening and transmits light emitted from the light source is further provided, and the transmissive member is supported by protrusions provided on both sides in the arrangement direction with respect to the opening. Part of the liquid ejected from the print head may become mist, and this mist-like liquid may adhere to each part of the apparatus and contaminate each part. Therefore, by providing the transmission member as described above, it is possible to suppress the mist-like liquid from entering the housing through the opening and to prevent the liquid from adhering to the light source. In addition, since the transmission member is supported by the protruding portion of the housing, a separate member for supporting the transmission member is not required, and the number of parts can be reduced.

1 is a front view schematically showing a configuration of an image recording apparatus to which the present invention can be applied. The schematic diagram which shows an example of embodiment of an irradiation part. The figure for demonstrating the suitable structure in the irradiation part of FIG. The figure for demonstrating the suitable structure in other embodiment of an irradiation part.

  Embodiments of an image recording apparatus according to the present invention will be described below with reference to the drawings. FIG. 1 is a front view schematically showing a configuration of an image recording apparatus to which the present invention can be applied. In FIG. 1 and the following drawings, a three-dimensional coordinate system corresponding to the left-right direction X, the front-rear direction Y, and the vertical direction Z of the image recording apparatus 1 in order to clarify the arrangement relationship of each part of the apparatus as necessary. Is adopted.

  As shown in FIG. 1, in the image recording apparatus 1, the feeding unit 2, the process unit 3, and the winding unit 4 are arranged in the left-right direction. The feeding unit 2 and the winding unit 4 have a feeding shaft 20 and a winding shaft 40, respectively. Then, both ends of the sheet S (web) are wound around the feeding unit 2 and the winding unit 4 in a roll shape, and are stretched between them. The sheet S is transported from the feeding shaft 20 to the process unit 3 along the transport path Pc thus stretched and subjected to image recording processing by the head unit 3U, and then transported to the winding shaft 40. The type of the sheet S is roughly classified into a paper type and a film type. Specific examples include high-quality paper, cast paper, art paper, coated paper, and the like for paper, and synthetic paper, PET (Polyethylene terephthalate), PP (polypropylene), and the like for film. In the following description, of both surfaces of the sheet S, the surface on which an image is recorded is referred to as the front surface, and the opposite surface is referred to as the back surface.

  The feeding unit 2 includes a feeding shaft 20 around which the end of the sheet S is wound, and a driven roller 21 around which the sheet S drawn from the feeding shaft 20 is wound. The feeding shaft 20 supports the end of the sheet S by winding the end thereof with the surface of the sheet S facing outward. Then, when the feeding shaft 20 rotates clockwise on the paper surface of FIG. 1, the sheet S wound around the feeding shaft 20 is fed to the process unit 3 via the driven roller 21.

  The process unit 3 appropriately performs processing by the head unit 3U disposed along the surface of the platen 30 while supporting the sheet S fed from the feeding unit 2 by a flat platen 30 having a flat shape. The image recording is performed on the sheet S. In the process unit 3, a front drive roller 31 and a rear drive roller 32 are provided on both sides of the platen 30, and the sheet S conveyed from the front drive roller 31 to the rear drive roller 32 is supported by the platen 30. Receive image printing.

  The front drive roller 31 has a plurality of minute protrusions formed by thermal spraying on the outer peripheral surface, and winds the sheet S fed from the feeding unit 2 from the surface side. Then, the front drive roller 31 rotates counterclockwise on the paper surface of FIG. 1 to convey the sheet S fed from the feeding unit 2 to the downstream side of the conveyance path Pc. A nip roller 31n is provided for the front drive roller 31. The nip roller 31n is in contact with the back surface of the sheet S while being biased toward the front drive roller 31 and sandwiches the sheet S between the front drive roller 31 and the nip roller 31n. Thereby, the frictional force between the front drive roller 31 and the sheet S is ensured, and the sheet S can be reliably conveyed by the front drive roller 31.

  The flat platen 30 is supported by a support mechanism (not shown) so that the support surface (upper surface) for supporting the sheet S is horizontal. Driven rollers 33, 34 are provided on the left and right sides of the platen 30, and the driven rollers 33, 34 wind the sheet S conveyed from the front drive roller 31 to the rear drive roller 32 from the back side. The upper end positions of the driven rollers 33 and 34 are arranged so as to be flush with or slightly below the surface of the platen 30, and the sheet S conveyed from the front driving roller 31 to the rear driving roller 32 contacts the platen 30. It is comprised so that the state which carried out can be maintained.

  The rear drive roller 32 has a plurality of minute protrusions formed by thermal spraying on the outer peripheral surface, and winds the sheet S conveyed from the platen 30 via the driven roller 34 from the front side. Then, the rear drive roller 32 conveys the sheet S to the winding unit 4 by rotating counterclockwise on the paper surface of FIG. A nip roller 32n is provided for the rear drive roller 32. The nip roller 32 n is in contact with the back surface of the sheet S while being biased toward the rear drive roller 32, and sandwiches the sheet S between the rear drive roller 32. Accordingly, a frictional force between the rear drive roller 32 and the sheet S is ensured, and the sheet S can be reliably conveyed by the rear drive roller 32.

  Thus, the sheet S conveyed from the front drive roller 31 to the rear drive roller 32 is conveyed in the conveyance direction Ds on the platen 30 while being supported by the platen 30. In the process unit 3, a head unit 3 </ b> U is provided to print a color image on the surface of the sheet S supported by the platen 30. Specifically, the head unit 3U includes four print heads 36a to 36d arranged from the upstream side to the downstream side along the transport direction Ds. The print heads 36a to 36d correspond to yellow, cyan, magenta, and black, respectively. Each of the print heads 36a to 36d is opposed to the surface of the sheet S supported by the platen 30 with a slight clearance, and ejects the corresponding color ink by an ink jet method. Then, each of the print heads 36a to 36d ejects ink onto the sheet S conveyed along the conveyance direction Ds, so that a color image is formed on the surface of the sheet S.

  Incidentally, as the ink (recording liquid), UV (ultraviolet) ink (photocurable ink) that is cured by irradiating with ultraviolet rays (light) is used. Therefore, the head unit 3U includes irradiation units 37a and 37b in order to cure the ink and fix the ink on the sheet S. The ink curing is performed in two stages, temporary curing and main curing. Between the print heads 36a to 36d, an irradiation portion 37a for temporary curing is disposed. That is, the irradiation unit 37a irradiates the ultraviolet ray with a small integrated light amount, thereby curing (temporarily curing) the ink to such an extent that the shape of the ink does not collapse, and does not completely cure the ink. On the other hand, an irradiation section 37b for main curing is provided on the downstream side in the transport direction Ds with respect to the print heads 36a to 36d. That is, the irradiation unit 37b completely cures (mainly cures) the ink by irradiating a larger amount of ultraviolet light than the irradiation unit 37a. By executing the temporary curing and the main curing in this manner, the color image formed by the print heads 36a to 36d can be fixed on the surface of the sheet S.

  Furthermore, the head unit 3U has a print head 36e on the downstream side in the transport direction Ds with respect to the irradiation unit 37b. The print head 36e is opposed to the surface of the sheet S supported by the platen 30 with a slight clearance, and discharges transparent UV ink onto the surface of the sheet S by an ink jet method. That is, the transparent ink is further ejected with respect to the color image formed by the print heads 36a to 36d for four colors. In addition to the head unit 3U, an irradiation unit 37c is provided downstream of the print head 36e in the transport direction Ds. The irradiating unit 37c irradiates strong ultraviolet rays to completely cure (mainly cure) the transparent ink ejected by the print head 36e. Thereby, the transparent ink can be fixed on the surface of the sheet S.

  As described above, in the process unit 3, ink discharge and curing are appropriately performed on the sheet S supported by the platen 30 to form a color image coated with the transparent ink. Then, the sheet S on which the color image is formed is conveyed to the winding unit 4 by the rear drive roller 32.

  The winding unit 4 includes a winding shaft 40 that winds the end of the sheet S, and a driven roller 41 that winds the sheet S conveyed to the winding shaft 40. The winding shaft 40 winds and supports the end of the sheet S with the surface of the sheet S facing outward. And the sheet | seat S is wound around the winding shaft 40 via the driven roller 41 by the winding shaft 40 rotating clockwise on the paper surface of FIG.

  Next, details of the irradiation units 37a to 37c will be described. FIG. 2 is a schematic diagram illustrating an example of an embodiment of an irradiation unit. Here, the print heads 36a to 36e have the same configuration, and the irradiation units 37a to 37c have the same configuration. Therefore, in the following, any one of the print heads 36a to 36e is referred to as the print head 36 without distinguishing the print heads 36a to 36e, and is provided adjacent to the downstream side in the transport direction Ds with respect to the print head 36. Any one of the irradiated irradiation units 37a to 37c will be described as the irradiation unit 37.

  The irradiation unit 37 is provided on the downstream side of the print head 36 in the transport direction Ds of the sheet S. The UV ink is first ejected from the nozzles 361 formed on the nozzle formation surface 362 of the print head 36 on the sheet S being conveyed in the conveyance direction Ds, and then irradiated with ultraviolet rays from the irradiation unit 37. . Thus, the UV ink attached to the surface of the sheet S is cured by the ultraviolet rays. In this embodiment, the arrangement direction Da in which the print head 36 and the irradiation unit 37 are arranged is along the transport direction Ds of the sheet S and coincides with the left-right direction (X direction).

  The irradiation unit 37 includes a housing 38 provided with an opening 381 facing the sheet S, a light source 39 accommodated in the housing 38 on the opposite side of the sheet S with respect to the opening 381, and a glass member that covers the opening 381. 40. Incidentally, the irradiation unit 37 is configured to be movable in the exit / retreat direction Db that moves out (proximity and separation) with respect to the sheet S. That is, an elevating mechanism 50 that moves the irradiation unit 37 in the retracting direction Db is provided, and when the elevating mechanism 50 is driven, the irradiation unit 37 moves in the retracting direction Db. In this embodiment, the exit / retreat direction Db is a direction substantially orthogonal to the arrangement direction Da and coincides with the vertical direction (Z direction).

  In the cross section in the XZ plane, the casing 38 includes a ceiling portion 382, two wall portions 383 extending downward (−Z direction) from the left and right ends of the ceiling portion 382 toward the sheet S, and each wall portion 383. And bottom portions 384 and 385 projecting from the lower end toward the opening 381. That is, the bottom portions 384 and 385 are provided in a state of protruding from the lower end of the inner wall surface 383 a of each wall portion 383, and the opening 381 is defined by the tips 384 a and 385 a of the bottom portions 384 and 385. In this embodiment, the opposing surfaces 384 b and 385 b of the bottom portions 384 and 385 facing the sheet S are substantially parallel to the sheet S supported by the planar support surface 30 a of the platen 30.

  The light source 39 is provided on the ceiling portion 382 of the housing 38 and emits ultraviolet rays for curing the UV ink. For example, a light-emitting diode (LED) can be used as the light source 39, but other light sources can be used. Then, the ultraviolet light emitted from the light source 39 passes through the opening 381 and enters the sheet S, whereby the UV ink attached to the surface of the sheet S is cured. In this embodiment, a plurality of light sources 39 are linearly provided in the front-rear direction (Y direction) to form a light source row, and two light source rows are provided in the left-right direction (X direction). With this configuration, it is possible to irradiate ultraviolet rays over the entire width of the sheet S (dimension in the Y direction). However, the number and arrangement of the light sources 39 are not limited to this configuration, and can be changed as appropriate.

  The glass member 40 covers the opening 381 while being supported by the bottom portions 384 and 385 provided on the left and right sides of the opening 381, and transmits the ultraviolet rays emitted from the light source 39. Here, a part of the UV ink ejected from the print head 36 may become mist, and this mist-like UV ink may adhere to each part of the apparatus and contaminate each part. However, by providing the glass member 40 that covers the opening 381, the mist-like UV ink is prevented from entering the housing 38 through the opening 381, and the UV ink is prevented from adhering to the light source 39. Can do. For this reason, the light source 39 can be appropriately protected and maintained in a good state. In addition, since the glass member 40 is supported by the bottom portions 384 and 385 of the casing 38, a separate member for supporting the glass member 40 becomes unnecessary, and the number of parts can be reduced.

  Incidentally, in the image recording apparatus 1 configured as described above, a part of the UV ink ejected from the nozzle 361 of the print head 36 may adhere to the nozzle formation surface 362 of the print head 36. When the UV ink attached to the nozzle formation surface 362 is irradiated with ultraviolet rays from the irradiation unit 37, the UV ink is cured on the nozzle formation surface 362. As a result, the cured UV ink accumulates on the nozzle forming surface 362, and the phenomenon that this deposit bends the ejection trajectory of the UV ink ejected from the nozzle 361 (so-called “flight bending”) occurs. The image recording could be adversely affected. Hereinafter, a configuration for suppressing UV ink from entering the nozzle forming surface 362 will be described.

  Among the ultraviolet rays emitted from the light source 39, the ultraviolet rays that pass through the opening 381 and are directly incident on the sheet S (hereinafter referred to as “direct incident light”) are reflected by the inner wall surface 383 a of the housing 38. There is ultraviolet light (hereinafter referred to as “in-casing reflected light”) that enters the sheet S through the opening 381. In this embodiment, among the bottom portions 384 and 385 of the housing 38, the entire region of the facing surface 384b of the bottom portion 384 between the nozzle forming surface 362 and the opening 381 particularly in the arrangement direction Da is applied to ultraviolet rays. By setting it as the site | part (henceforth a "low reflection part") which has a low reflectance, it can be made to suppress incidence to a nozzle formation surface with respect to both directly incident light and reflected light in a housing | casing.

  Various methods are conceivable for making the facing surface 384b of the bottom portion 384 a low-reflection portion. For example, the bottom portion 384 itself may be formed of a low-reflectance member, or a predetermined process may be performed on the facing surface 384b. Or a low reflectivity material may be applied. As the low reflectance member or material, for example, a material having a high absorption rate for ultraviolet rays can be selected. In this embodiment, the low reflection part is formed by sticking white art paper (reflectance with respect to ultraviolet rays: about 65% or less) to the entire region of the facing surface 384b. However, in addition to this, the bottom 384 can also be formed of a roughened iron plate (same as above: about 50 to 60%) or a galvanized iron plate (same as about 30% to 40%). . Furthermore, colored alumite treatment (same: about 5-50%), dark color coating (same: about 15-40%), matte coating (same: about 0.5-30%), flocking treatment (same: about: 0.1-10%), or low reflection surface treatment such as black, tough black, black cobalt alloy plating, black electroless nickel plating, black chrome plating, radiant treatment (same: about 0.5-50%) ) Etc. can be applied to the opposing surface 384b to form a low reflection portion.

  As described above, the bottom portion 384 on which the low reflection portion is formed is provided between the nozzle formation surface 362 and the opening 381 in the arrangement direction Da. Then, on the facing surface 384b of the bottom 384, for example, as indicated by a broken line in FIG. 2, the light that is regularly reflected toward the print head 36 in the arrangement direction Da out of the reflected light of the directly incident light on the sheet S is received. Incident. For this reason, since direct incident light is specularly reflected by the sheet S and then incident on the opposing surface 384b and attenuated, direct incident light can be prevented from entering the nozzle forming surface 362.

  Furthermore, the bottom portion 384 is provided so as to protrude from the inner wall surface 383a of the housing 38 and to define the opening 381 at the tip 384a. Therefore, for example, as indicated by a one-dot chain line in FIG. 2, the reflected light in the housing that is reflected by the inner wall surface 383 a of the housing 38 and then travels toward the sheet S is blocked before reaching the sheet S, so that the reflected light in the housing is It can suppress entering into the nozzle formation surface 362. FIG.

  As described above, in the present embodiment, by including the bottom portion 384 configured also as the low reflection portion, it is possible to suppress the incidence on the nozzle forming surface 362 with respect to both the directly incident light and the reflected light in the casing, and the irradiation portion 37. It is possible to effectively prevent the ultraviolet rays from the incident to the nozzle forming surface 362.

  Moreover, in this embodiment, since the entire area of the facing surface 384b of the bottom 384 is configured as a low reflection portion, the light traveling toward the facing surface 384b is surely incident on the facing surface 384b as the low reflection portion and attenuated. To do. Therefore, the incidence of the light reflected by the facing surface 384b of the bottom portion 384 on the nozzle forming surface 362 can be more reliably suppressed.

  In this embodiment, not only the facing surface 384b of the bottom portion 384 but also the facing surface 385b of the bottom portion 385 on the opposite side of the bottom portion 384 with respect to the opening 381 is pasted with white art paper on the entire area. A reflection part is formed. As described above, when both the bottom portions 384 and 385 provided on the left and right sides of the opening 381 are low reflection portions, the print heads 36 are provided on both sides of the one irradiation portion 37 as shown in FIG. In addition, it is possible to prevent ultraviolet rays from entering the nozzle formation surfaces 362 of the print heads 36 on both sides.

  Subsequently, the irradiation unit 37 will be described in more detail. FIG. 3 is a view for explaining a preferred configuration in the irradiation section of FIG. 2, but the illustration of the glass member 40 is omitted. Considering the ultraviolet rays that are specularly reflected by the sheet S toward the print head 36 out of the directly incident light, the light having a larger incident angle θ on the sheet S is more difficult to block the reflected light toward the nozzle forming surface 362 at the bottom 384. Become. Therefore, in the present embodiment, the regular reflected light UVr of the ultraviolet ray (hereinafter referred to as “maximum incident angle light UVi”) having the maximum incident angle θ among the directly incident light is incident on the facing surface 384 b of the bottom 384. It is configured. FIG. 3 shows a case where the locus of the regular reflection light UVr coincides with a straight line connecting the incident position of the maximum incident angle light UVi on the sheet S and the base end 384c of the bottom portion 384.

  The trajectory of the maximum incident angle light UVi coincides with a straight line connecting the target light source 39T farthest from the nozzle forming surface 362 in the arrangement direction Da among the plurality of light sources 39 and the tip 384a of the bottom 384. When the light source 39 has a non-negligible spread in the arrangement direction Da, the position of the target light source 39T that is the most distant from the nozzle formation surface 362 in the arrangement direction Da is particularly the position of the target light source 39T. Can be considered.

Here, when the facing surface 384b of the bottom 384 can be regarded as parallel to the sheet S,
L1: Distance in arrangement direction Da between target light source 39T and tip 384a of bottom 384 L2: Length in arrangement direction Da of bottom 384 D1: Distance between target light source 39T and sheet S D2: Tip of bottom 384 The distance between 384a and the sheet S is defined as the incident angle of the maximum incident angle light UVi on the sheet S.
L1 = tan θ · (D1-D2)
L2 = 2 tan θ · D2
This relationship is established in FIG.

When the distance L1 becomes larger or the length L2 becomes shorter than the state shown in FIG. 3, the incident angle θ of the maximum incident angle light UVi increases, and the regular reflection light UVr of the maximum incident angle light UVi forms the nozzle. There is a risk of being incident on the surface 362. Therefore, by making the distance L1 smaller and the length L2 longer than in the state shown in FIG. 3, the specularly reflected light UVr can be reliably incident on the facing surface 384b of the bottom 384. In other words, by configuring the irradiation unit 37 so as to satisfy the following (Expression 1) and (Expression 2), the regular reflection light of other ultraviolet rays having an incident angle θ on the sheet S smaller than the maximum incident angle light UVi. Can be reliably incident on the facing surface 384b on which the low reflection portion is formed. As a result, the specularly reflected light is attenuated by the facing surface 384b, and ultraviolet rays incident on the nozzle forming surface 362 can be reliably suppressed.
L1 ≦ tan θ · (D1-D2) (Formula 1)
L2 ≧ 2 tan θ · D2 (Formula 2)

  In this embodiment, as described above, the elevating mechanism 50 that moves the sheet S in the retracting direction Db is provided. Therefore, even when the thickness of the sheet S is variously changed, the distances D <b> 1 and D <b> 2 are adjusted by moving the irradiation unit 37 with respect to the sheet S by the elevating mechanism 50, so that the thickness of the sheet S is affected. (Equation 1) and (Equation 2) can be satisfied.

  As described above, in this embodiment, the sheet S is disposed between the nozzle forming surface 362 and the opening 381 in the arrangement direction Da in which the print head 36 and the irradiation unit 37 are arranged, and from the light source 39 through the opening 381. A low reflection portion (opposing surface 384b) is provided for the light that is regularly reflected on the print head 36 side in the arrangement direction Da out of the directly incident light directly incident on the light. For this reason, the direct incident light is attenuated by being regularly reflected by the sheet S and then entering the low reflection portion 384 b, and the direct incident light can be prevented from entering the nozzle forming surface 362. Further, projecting portions (bottom portions 384 and 385) that project from the inner wall surface 383 a of the housing 38 and define the opening 381 are provided. Therefore, the reflected light in the housing that is reflected by the inner wall surface 383 a of the housing 38 and then travels toward the sheet S is blocked by the protrusions 384 and 385 before reaching the sheet S, and the reflected light in the housing enters the nozzle forming surface 362. Can be suppressed. As described above, by having the protruding portions 384 and 385 having the low reflection portion 384b, it is possible to suppress both the direct incident light and the reflected light in the casing from entering the nozzle forming surface 362, and the ultraviolet rays from the irradiation portion 37. Is effectively prevented from entering the nozzle forming surface 362.

  In the case where the protruding portion 384 (head-side protruding portion) is provided between the nozzle forming surface 362 and the opening 381 in the arrangement direction Da, the head-side protruding portion 384 faces the sheet S on the facing surface 384b facing the sheet S. It is also assumed that the reflected light enters the nozzle formation surface 362 after repeated reflection. Therefore, in this embodiment, the low reflection portion is formed on the facing surface 384b facing the sheet S of the head-side protruding portion 384 located between the nozzle forming surface 362 and the opening 381 in the arrangement direction Da. Thus, by forming the low reflection portion on the facing surface 384b of the head-side protruding portion 384, the light traveling toward the facing surface 384b enters the low reflection portion and is attenuated. For this reason, it is possible to suppress the light reflected by the facing surface 384 b of the head-side protruding portion 384 from entering the nozzle forming surface 362.

  Further, by providing the bottom portion 384 functioning as a low reflection portion and a protruding portion in this way, it is possible to suppress the ultraviolet rays from the irradiation portion 37 from entering the nozzle forming surface 362, and therefore printing in the arrangement direction Da. The distance between the head 36 and the irradiation unit 37 can be set more freely. For this reason, for example, the UV ink discharged from the print head 36 can be quickly cured by the irradiation unit 37 by arranging the print head 36 and the irradiation unit 37 so as to reduce the interval.

  As described above, in this embodiment, UV ink corresponds to “liquid” in the present invention, ultraviolet light corresponds to “light” in the present invention, and sheet S corresponds to “recording medium” in the present invention. 384 and 385 correspond to the “protruding portion” of the present invention, the bottom portion 384 corresponds to the “head side protruding portion” of the present invention, and the opposing surfaces 384b and 385b correspond to the “low reflection portion” of the present invention. The member 40 corresponds to the “transmission member” of the present invention, and the lifting mechanism 50 corresponds to the “drive mechanism” of the present invention.

[Other embodiments]
Another embodiment of the present invention will be described with reference to FIG. FIG. 4 is a diagram for explaining a preferred configuration in another embodiment of the irradiation unit. Note that this embodiment is different from the above-described embodiment in that the bottom portions 384 and 385 are protruded obliquely upward from the inner wall surface 383a. However, the configuration is common to the other embodiments described above. Will not be described. It goes without saying that the same effect can be achieved by providing the configuration common to the above-described embodiment. In the present embodiment, the bottom portions 384 and 385 are projected obliquely upward from the inner wall surface 383a, but may be projected obliquely downward. In this case, the reflected light in the casing can be easily reflected toward the inside of the casing 38, and the incidence of light on the nozzle forming surface 362 can be suppressed.

  In this embodiment, the bottom surface 384 protrudes obliquely upward from the inner wall surface 383a toward the opening 381, so that the facing surface 384b of the bottom portion 384 is an inclined surface. The distance of the facing surface 384b from the sheet S increases from the print head 36 side (base end 384c side) toward the opening 381 side (front end 384a side) in the arrangement direction Da. As described above, the opposing surface 384b is an inclined surface extending from the inner wall surface 383a toward the inside of the housing 38, so that the light incident on the opposing surface 384b after being reflected by the sheet S is arranged in the arrangement direction Da. It becomes easy to reflect in the opening 381 side. Therefore, the light incident on the facing surface 384b can be prevented from being reflected toward the print head 36, and the reflected light from the facing surface 384b can be prevented from entering the nozzle forming surface 362.

  In this embodiment, not only the facing surface 384b of the bottom portion 384 but also the facing surface 385b of the bottom portion 385 on the opposite side of the bottom portion 384 with respect to the opening 381 has an inclined surface similar to the facing surface 384b. For this reason, as shown in FIG. 1, when the print heads 36 are provided on both sides of the one irradiation unit 37, it is possible to suppress the ultraviolet rays from entering the nozzle formation surfaces 362 of the print heads 36 on both sides. In addition, in order to acquire the effect similar to the opposing surfaces 384b and 385b comprised in this way, it is good also considering the opposing surfaces 384b and 385b as a curved surface which is convex upwards.

  Here, as in the above-described embodiment, regarding the case where the facing surface 384b of the bottom portion 384 is an inclined surface, the conditions for causing the regular reflection light UVr of the maximum incident angle light UVi to enter the facing surface 384b of the bottom portion 384 are as follows. consider. Similar to FIG. 3, FIG. 4 is a straight line where the locus of the regular reflection light UVr of the maximum incident angle light UVi connects the incident position of the maximum incident angle light UVi to the sheet S and the base end 384 c of the bottom 384. Is shown.

Here, when the facing surface 384b of the bottom 384 is an inclined surface whose distance from the sheet S increases from the print head 36 side toward the opening 381 side in the arrangement direction Da,
L1: Distance in the arrangement direction Da between the target light source 39T and the tip 384a of the bottom 384 L2: Distance in the arrangement direction Da between the tip 384a of the bottom 384 and the inner wall surface 383a D1: Between the target light source 39T and the sheet S Distance D2: Distance between the tip 384a of the bottom 384 and the sheet S D3: Distance between the base 384c of the bottom 384 and the sheet S θ: Maximum incident angle When defined as the incident angle of the light UVi on the sheet S,
L1 = tan θ · (D1-D2)
L2 = tan θ · (D2 + D3)
This relationship is established in FIG.

When the distance L1 becomes larger or the length L2 becomes shorter than the state shown in FIG. 4, the incident angle θ of the maximum incident angle light UVi increases, and the regular reflection light UVr of the maximum incident angle light UVi forms the nozzle. There is a risk of being incident on the surface 362. Therefore, by making the distance L1 smaller and the length L2 longer than in the state shown in FIG. 4, the regular reflected light UVr can be reliably incident on the facing surface 384b of the bottom 384. In other words, by configuring the irradiation unit 37 so as to satisfy the following (Expression 3) and (Expression 4), the regular reflected light of other ultraviolet rays having an incident angle θ to the sheet S smaller than the maximum incident angle light UVi. Can be reliably incident on the facing surface 384b on which the low reflection portion is formed. As a result, the specularly reflected light is attenuated by the facing surface 384b, and ultraviolet rays incident on the nozzle forming surface 362 can be reliably suppressed.
L1 ≦ tan θ · (D1-D2) (Formula 3)
L2 ≧ tan θ · (D2 + D3) (Formula 4)

[Modification]
In addition, this invention is not limited to the said embodiment, Unless it deviates from the meaning, it is possible to combine the element of the said embodiment suitably, or to add a various change. For example, in the above embodiment, the bottom portion 384 between the nozzle forming surface 362 and the opening 381 in the arrangement direction Da has a function as a low reflection portion. However, the low reflection portion can be provided as a member (low reflection member) completely different from the bottom portion 384. In this case, for example, the low reflection member can be disposed between the bottom 384 and the sheet S, or can be disposed at an appropriate position between the print head 36 and the irradiation unit 37 in the arrangement direction Da.

  Further, in the above embodiment, the bottom portions 384 and 385 as the protruding portions of the present invention are provided on both sides of the opening 381 in the arrangement direction Da, but at least in the arrangement direction Da, the nozzle formation surface 362 and the opening 381 are provided. It is only necessary that a bottom portion 384 is provided between them, and providing the bottom portion 385 is not an essential requirement for the present invention.

  Moreover, in the said embodiment, although the low reflection part was formed in the whole area | region of each opposing surface 384b and 385b of the bottom parts 384 and 385, even if it forms a low reflection part only in a partial area | region of the opposing surfaces 384b and 385b. Good. Furthermore, the low reflection portion may not be formed at all on the facing surface 385b on the opposite side of the nozzle forming surface 362 with respect to the opening 381.

  Moreover, in the said embodiment, although the bottom parts 384 and 385 as a protrusion part of this invention shall protrude from the lower end of the inner wall surface 383a, it is not necessary to protrude from the lower end of the inner wall surface 38a. That is, the bottom portions 384 and 385 may protrude from an appropriate position between the upper end and the lower end of the inner wall surface 38a.

  In the above-described embodiment, the arrangement direction Da in which the print head 36 and the irradiation unit 37 are arranged is along the conveyance direction Ds of the sheet S. However, the arrangement direction Da may be different from the transport direction Ds.

  In the above embodiment, the opening 381 is covered by the glass member 40 to protect the light source 39. However, the opening 381 may be formed by another member as long as it is a member that can transmit light emitted from the light source 39. It may be covered. Furthermore, it is possible not to provide a member that covers the opening 381.

  In the above embodiment, the sheet S is supported by the flat support surface 30a of the platen 30, but the sheet S can be supported by a rotating drum having an arcuate support surface, for example. In this case, the above relational expressions (Formula 1), (Formula 2), (Formula 3), and (Formula 4) are appropriately modified or used, or when designing the irradiation unit 37, in relation to the rotating drum, You may obtain | require the positional relationship that the light reflected by the support surface of the rotating drum injects into the bottom part 384 using drawing apparatuses, such as CAD.

  Further, it is possible to discharge liquid other than UV ink from the print head 36, and the light emitted from the light source of the irradiation unit 37 can be changed as appropriate according to the type of liquid discharged from the print head 36. .

  DESCRIPTION OF SYMBOLS 1 ... Image recording device, 30 ... Platen (support member), 30a ... Support surface, 36 ... Print head, 361 ... Nozzle, 362 ... Nozzle formation surface, 37 ... Irradiation part, 38 ... Housing | casing, 381 ... Opening, 384 ... Bottom part (head side projecting part), 385 ... Bottom part (projecting part), 384a, 385a ... Tip, 384b ... Opposing surface (low reflection part), 384c ... Base end, 39 ... Light source, 40 ... Glass member (transmission member), 50 ... Elevating mechanism (drive mechanism), S ... Sheet (recording medium), Da ... Arrangement direction

Claims (8)

A print head having a nozzle forming surface provided with a nozzle for discharging a photo-curable liquid toward a recording medium;
An irradiating unit including a housing that defines an opening facing the recording medium at a tip of a projecting portion projecting from an inner wall surface, and a light source that emits light that is contained in the housing and cures the liquid;
With
The protrusion has a head-side protrusion located between the nozzle forming surface and the opening in the arrangement direction in which the print head and the irradiation portion are arranged.
The light that is directly incident on the recording medium from the light source through the opening and is regularly reflected on the print head side in the arrangement direction is incident on the facing surface of the head-side protruding portion that faces the recording medium. An image recording apparatus having a low reflection portion.   The image recording apparatus according to claim 1, wherein the low reflection portion is formed in the entire region of the facing surface.   The image recording apparatus according to claim 1, wherein the facing surface is an inclined surface extending from the inner wall surface toward the light source side or the recording medium side.   Of the light that is directly incident on the recording medium after being directly incident on the recording medium from the light source through the opening, the specularly reflected light of the light having the maximum incident angle when incident on the recording medium is the light. The image recording apparatus according to claim 1, wherein the image recording apparatus is incident on the facing surface. A support member having a flat support surface for supporting the recording medium;
The distance in the arrangement direction between the target light source that is the light source farthest from the nozzle formation surface in the arrangement direction and the tip of the head side protrusion is L1, and the tip of the head side protrusion is The distance between the inner wall surface in the arrangement direction is L2, the distance between the target light source and the recording medium is D1, the distance between the tip of the head side protruding portion and the recording medium is D2, and the head The distance between the base end of the side protrusion and the recording medium is D3, and the incident angle of light on the recording medium with the locus connecting the target light source and the tip of the head side protrusion is θ. 5. The image recording apparatus according to claim 1, wherein the following (Formula 1) and (Formula 2) are satisfied.
L1 ≦ tan θ · (D1-D2) (Formula 1)
L2 ≧ tan θ · (D2 + D3) (Formula 2)   6. The image recording apparatus according to claim 1, further comprising a drive mechanism that moves the irradiation unit in a retracting direction with respect to the recording medium.   The said printing head discharges the said liquid hardened | cured with an ultraviolet-ray from the said nozzle, the said light source inject | emits the said ultraviolet-ray as the said light, The said low reflection part absorbs the said ultraviolet-ray in any one of Claim 1 thru | or 6 The image recording apparatus described. And further comprising a transmission member that covers the opening and transmits the light emitted from the light source,
The image recording apparatus according to claim 1, wherein the transmission member is supported by the protrusions provided on both sides in the arrangement direction with respect to the opening.

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