Patent Application
20080204536
1. Field of the Invention
The present invention relates to an ink jet recording apparatus which performs recording by using a recording liquid which is cured by irradiation with an active ray.
2. Related Background Art
In recent years, there is known an ink jet recording apparatus in which ultraviolet curable ink (hereinafter, referred to as UV ink) to be cured by an ultraviolet ray is used as ink ejected by an ink jet head, the UV ink is ejected and adhered to a recording medium such as a PVC sheet, glass, a foamed board, or a plate, and after that, an ultraviolet ray is applied to cure and fix the UV ink on the recording medium.
According to Japanese Patent Application Laid-open No. Sho 60-132767 and Japanese Patent Application Laid-open No. 2004-338264 and the like, there are proposed recording apparatuses of a type, in which an ink jet head moves in a direction orthogonal to a conveying direction of a recording medium (hereinafter, referred to as main scanning direction), that is, a so-called serial type, and which has an ultraviolet ray irradiation lamp provided to at least one of both side portions in the main scanning direction of the ink jet head and moving together with the head. Further, Japanese Patent Application Laid-open No. Sho 60-132767 also proposes an apparatus of a so-called line type, in which an ink jet head is stationary and has a length larger than a width of a recording medium in the main scanning direction and an ultraviolet ray irradiation lamp for irradiating an overall width of the recording medium is disposed on a recording medium delivery side of the head.
On the other hand, Japanese Patent Application Laid-open No. 2004-338264 discloses an invention for solving a problem in that, when an ultraviolet ray irradiation lamp moves to the outside of a region of a platen (home position or head moving direction changing position) for supporting a recording medium in an ink ejection forward side of an ink jet head, an ultraviolet ray applied from the ultraviolet ray irradiation lamp is reflected on a casing wall portion of the apparatus to enter a nozzle portion of the ink jet head, thereby causing the ink in the nozzle portion to be cured. As means for solving the problem, a plate material for preventing the reflection of the ultraviolet ray is set, in the home position or the head moving direction changing position, to substantially the same height as the platen.
However, the invention disclosed in Japanese Patent Application Laid-open No. 2004-338264 is perhaps effective in a case where printing is performed on thin recording media such as roll paper, but in a case where the recording medium is thicker, a step height between a recording surface of the recording medium and the platen for supporting the recording medium cannot be ignored for solving the above-mentioned problem. That is, in flatbed printers, hybrid printers, or the like, in a case where printing is performed on a rigid medium having a plate thickness, such as aplastic board or a glass plate, when an ultraviolet ray irradiation device is situated above the rigid medium, an ultraviolet ray does not enter the nozzle portion, but at a moment when the ultraviolet ray irradiation device retained at a constant height with respect to a recording surface of the rigid medium moves to the outside of an end side in a width direction of the rigid medium, the height thereof becomes larger. That is, an irradiation direction space of the ultraviolet ray irradiation device increases. As a result, due to reflection, scatter, diffraction, or the like of the ultraviolet ray from the ultraviolet ray irradiation device to the ink jet head side, leak light increases, thereby causing the ink curing in the nozzle portion.
An occurrence state of this problem is described in detail with reference to
The problem described above can be solved by providing the ultraviolet ray irradiation device with a shutter mechanism capable of shielding the ultraviolet ray. However, in order to achieve this, at a timing immediately before the ultraviolet ray irradiation device 3 positioned on a back side of the ink jet head 2 moving in the main scanning direction reaches the end side in the width direction of the rigid medium (stage shown in
In view of the above-mentioned related-art problem, it is therefore an object of the present invention to prevent, in an ink jet recording apparatus for performing printing with active ray curing type ink, ink curing in the nozzle portion at a time of printing on a thick rigid medium on the platen and to enable the no-margin printing on the rigid medium.
An ink jet recording apparatus according to the present invention includes: an ink jet head for performing recording by discharging droplets of active ray curing type ink onto a recording medium; and an active ray irradiation device disposed adjacently to the ink jet head, for curing the active ray curing type ink discharged onto a recording surface of the recording medium.
Further, there is provided a plate which can be disposed in a vicinity of an end portion of the recording medium and is movable, whereby the above-mentioned problem is solved.
That is, in the present invention, when the active ray irradiation device is positioned outside a recording region of the thick recording medium called rigid medium while remaining in an active ray irradiation state, here, a plate which can be disposed in an arbitrary position between a surface substantially flush with the recording surface and the ink discharge surface of the ink jet head exists, so the irradiation direction space of the active ray irradiation device is not enlarged. Accordingly, the active ray from the active ray irradiation device does not enter the nozzle portion of the ink jet head, thereby preventing the curing of the ink in the nozzle portion. Further, owing to this, no-margin printing on the thick recording medium, which cannot be performed in the related art is enabled.
In the ink jet recording apparatus, there is preferably provided a plate position adjusting mechanism for making the plate movable in a thickness direction of the recording medium so that a surface on a side of the ink jet head and on a side of the active ray irradiation device of the plate vertically moves in parallel with respect to the recording surface.
Further, there is preferably provided a head position adjusting mechanism for making the ink jet head movable in a thickness direction of the recording medium so that a distance from the recording surface to an ink discharge surface of the ink jet head can be changed.
In this case, it is preferable that, when the head position adjusting mechanism adjusts a position of the ink jet head, the plate position adjusting mechanism move the plate in association therewith. With this structure, by adjusting the position of the ink discharge surface of the ink jet head correspondingly to the thickness of the recording medium to be conveyed, the surface on the ink jet head side and the active ray irradiation device side of the plate is automatically adjusted to a predetermined position between the surface substantially flush with the recording surface and the ink discharge surface of the ink jet head.
In order to achieve this, it is necessary that a distance from the recording surface to the surface on the side of the ink jet head and on the side of the active ray irradiation device of the plate and the distance from the recording surface to the ink discharge surface of the ink jet head be each adjusted to a given distance in advance.
Further, in the above-mentioned ink jet recording apparatus, there is desirably provided a slide mechanism for enabling the plate to slide so as to be in contact with an end of the recording medium in accordance with an outer configuration of the recording medium. As a result, even when an outer configuration of the recording medium to be conveyed is changed, a flat surface adjacent to the recording surface of the recording medium can be structured.
The slide mechanism includes a rail member disposed in a direction orthogonal to a conveying direction of the recording medium so as to guide the plate in a freely slidable manner.
In a case of an ink jet recording apparatus of a serial type, it is conceived that the rail member is disposed along a rail for guiding the ink jet head in the direction crossing the conveying direction of the recording medium.
Further, it is preferable that a surface on a side of the ink jet head and on a side of the active ray irradiation device of the plate be subjected to treatment for preventing reflection, scatter, or the like of an active ray.
Further, it is preferable that the plate be disposed on at least one of both sides in a direction crossing a conveying direction of the recording medium.
The above-mentioned plate disposed on one of both sides in the direction crossing the conveying direction of the recording medium may have the following structure. That is, in an ink jet recording apparatus of a serial type, in a home position of the ink jet head, a maintenance mechanism for maintaining and recovering discharge of the head is provided in some cases. The recording apparatus of the present invention uses active ray curing type ink. Accordingly, the maintenance mechanism includes a shutter mechanism for preventing incidence of the active ray and a plate-like member provided therearound. In this case, by making the shutter mechanism and the plate-like member movable in a thickness direction of the recording medium, the same function as that of the plate can be achieved.
Further, in the ink jet recording apparatus as described above, between the ink jet head and the active ray irradiation device, a light shielding plate is desirably provided, for shielding the active ray from the active ray irradiation device to the ink discharge surface of the ink jet head. In this case, there is desirably provided a light shielding plate position adjusting mechanism, by which, even when positions of the ink jet head and the active ray irradiating device are adjusted with respect to the recording surface, a gap between the plate and the light shielding plate are maintained constant.
Further, there is preferably provided friction reducing means between an end portion of the plate and the recording medium, the friction reducing means being provided to the end portion on a side of the recording medium of the plate and being brought into contact with the recording medium.
Further, there is preferably provided an ink removing layer provided on a part or an entire surface which is brought into contact with the recording medium of the plate, for facilitating removal of the active ray curing type ink in a case where the active ray curing type ink is adhered thereto.
Note that the term “active ray” in the scope of claims and in this specification, includes ones having property of diffraction, reflection, or the like, such as light, an electron ray, and a radiation ray. Further, as the active ray used for curing the active ray curing type ink, an ultraviolet ray, a near-infrared ray, an electron ray, or the like are preferable.
According to the present invention described above, when the ink jet recording is performed on the thick rigid medium with the active ray curing type ink, ink curing in the nozzle portion by the active ray can be prevented and the no-margin printing on the rigid medium is enabled.
Hereinafter, description will be made of an embodiment of the present invention with reference to the drawings. Note that, herein, the same components as those of the related-art apparatus structure illustrated in
In those figures, the ink jet recording apparatus according to this embodiment includes an ink jet head 2 for discharging UV ink of six colors (cyan C, magenta M, yellow Y, light cyan Lc, light magenta Lm, black K), ultraviolet ray irradiation devices 3 for irradiating an ultraviolet ray for curing the UV ink, and a carriage 7 for mounting those. The carriage 7 engages with a carriage rail 15 extending in the main scanning direction and can reciprocatingly move along the carriage rail 15 by drive means including a motor and an endless belt. Further, the ultraviolet ray irradiation devices 3 on the carriage 7 are disposed on both sides in the main scanning direction of the ink jet head 2 for six colors. In the recording apparatus, each of an ink discharge surface of the ink jet head 2 and ultraviolet ray irradiation holes of the ultraviolet ray irradiation devices 3 is oriented in a substantially gravitational direction. Between the ultraviolet ray irradiation device 3 and the ink jet head 2 adjacent thereto, a plurality of shielding plates 5 are provided, thereby reducing leakage of the ultraviolet ray from the ultraviolet ray irradiation device 3, reflected, scattered, etc. on the rigid medium 1 to the ink jet head 2 side.
The rigid medium 1 onto which the UV ink is discharged from the ink jet head 2 is supported by an upper surface of the platen 4 such that the recording surface thereof is maintained flat, and the rigid medium 1 is conveyed and supported by a conveying means 10. The platen 4 has a sufficient width in the main scanning direction, for supporting the rigid medium 1 of a maximum size on which the printing can be performed by this recording apparatus. On the other hand, various conveying mechanisms using a roller, a belt, or the like can be applied to the conveying means 10. As an example thereof, there is conceived a structure in which, as shown in
Further, in the present invention, a plate 8 forming a flat surface is provided to an outside of a region of the rigid medium 1 to be conveyed. The plate 8 can be disposed at any height position between substantially the same height as a recording surface 1a of the rigid medium 1 and the ink discharge surface of the ink jet head 2, and can be disposed so as to be adjacent to an end surface of the rigid medium 1.
In order to achieve this, the plate 8 is slidably suspended on two rail members 9a and 9b arranged in substantially parallel to each other in the main scanning direction. One rail member 9a of the two rail members 9 is disposed below the carriage rail 15 and along the carriage rail 15. The other rail member 9b is disposed at an interval from the rail member 9a in the conveying direction of the rigid medium, the interval being larger than an outside dimension of the carriage 7, the ink jet head 2, and the like. The rail members 9a and 9b are arranged at a position sufficiently higher than a flat surface portion of the plate 8 when the plate 8 is installed at substantially the same height as the recording surface 1a of the rigid medium 1. Accordingly, both ends of the flat surface portion of the plate 8 are folded to be engaged with the rail members 9a and 9b. With the above-mentioned structure, the rail members 9a and 9b do not interfere with conveyance of the rigid medium 1, and the plate 8 is enabled to slide in the main scanning direction to be positioned in the end surface position of the rigid medium 1 of various size widths. Note that a slide operation of the plate 9 may be performed by using drive means such as a linear actuator or a ball screw. Further, in a case of a compatible device in which recording with the rigid medium can be changed to recording with a roll medium, in order to ensure a space for easily replacing the conveying means 10 including the platen 4, it is preferable that the rail members 9a and 9b be extended to be longer than the carriage rail 15 and a retraction area for the plate 8 be provided.
Further, as shown in
The rail members 9a and 9b for suspending the plate 8 can be vertically moved individually. However, vertical movement mechanisms of the rail members 9a and 9b are also associated with a vertical movement mechanism of the carriage rail 15. Specifically, when, in accordance with the thickness of the rigid medium 1 to be conveyed, a distance from the recording surface 1a of the rigid medium 1 to the ink discharge surface of the ink jet head 2 is made variable by the vertical movement mechanism of the carriage rail 15, the rail members 9a and 9b and the plate 8 suspended on the rail members 9a and 9b move in association therewith, thereby changing the height position of the upper surface of the plate 8.
At this time, it is preferable that the vertical movement mechanisms of the carriage rail 15 and the rail members 9a and 9b be used to set the distance from the recording surface 1a of the rigid medium 1 to the ink discharge surface of the ink jet head 2 to the above-mentioned given distance X, and at the same time, a distance from the recording surface 1a thereof to the upper surface of the plate 8 be set to a predetermined distance in advance. A reason for this is because, when, since the height of the recording surface 1a of the rigid medium 1 changes, the distance from the recording surface 1a of the rigid medium 1 to the ink discharge surface of the ink jet head 2 is set again to the above-mentioned distance X by the vertical movement mechanism of the carriage rail 15, the height (distance) of the upper surface of the plate 8 with respect to the recording surface 1a automatically becomes the predetermined distance which is set in advance. That is, the height adjustments of the ink jet head 2 and the plate 8 are associated with each other, so, even when the height of the ink discharge surface of the ink jet head 2 is changed in accordance with the height position of the recording surface 1a of the rigid medium 1, the distance between the recording surface and the upper surface of the plate 8 is continuously retained to be the predetermined distance.
With the above-mentioned structure, when the plate 8 whose height is adjusted to a predetermined height position between the recording surface 1a of the rigid medium 1 and the ink discharge surface of the ink jet head 2 is slid according to the width of the rigid medium 1 to be made adjacent to the end surface of the rigid medium 1, the step height corresponding to the thickness of the rigid medium 1 is reduced. After the setting as described above, the carriage 7 is moved from a left end to a right end of
Further, with the recording apparatus according to this embodiment, regardless of the thickness of the recording medium, the height of the ink discharge surface of the ink jet head 2 and the height of the plate 8 can be made variable independently of each another. Thus, the height of the plate 8 can be made as close as possible to the height of the ink discharge surface of the ink jet head 2. When the plate 8 is made closer to the ink discharge surface of the ink jet head 2, leakage of the ultraviolet ray from the ultraviolet ray irradiation device 3 to the ink jet head 2 is reduced by a corresponding amount. That is, the irradiation direction space of the ultraviolet ray irradiation device 3 is made narrower, so the ultraviolet ray reaching the head is reduced by a corresponding amount, thereby making it possible to prevent curing of the ink in the nozzle portion.
Note that the ultraviolet ray from the ultraviolet ray irradiation device 3 is applied onto the plate 8 to be reflected, scattered, etc., so the surface of the plate 8 is subjected to anti-reflection treatment with an ultraviolet ray absorber or the like or black light absorbing treatment such as black alumite treatment.
In this figure, the surface on the ink jet head 2 side of the plate 8 is subjected to an anti-reflection layer 23. The anti-reflection layer 23 is subjected to the anti-reflection treatment with the ultraviolet ray absorber or the like, or the black light absorbing treatment such as the black alumite treatment. Thus, reflectance of the ultraviolet ray in a case where the anti-reflection layer 23 exists is made smaller than in a case where the anti-reflection layer does not exist, thereby reducing reflection of the ultraviolet ray. Further, on the surface of the plate 8 including the anti-reflection layer 23, there is provided an ink removing layer 24. The ink removing layer 24 is made of a fluororesin which is a liquid-resistant material, and a surface of the ink removing layer 24 is a layer having smaller irregularities than those of the anti-reflection layer 23 or the surface of the plate 8, thereby increasing smoothness. Accordingly, in a case where ink is adhered and fixed, the ink can be more easily removed when the ink removing layer 24 is provided. Further, the ink removing layer 24 also serves to facilitate removal of the ink adhered due to misting or splash of the ink. Accordingly, while in
Further, a roller 25 is disposed on the end portion on the rigid medium 1 side of the plate 8. The roller 25 is brought into contact with a side surface of the rigid medium 1 at a contact surface 28. Further, the roller 25 is arranged so as to slightly protrude from a side surface of the plate 8, whereby an opposed surface 27 of the plate 8 with respect to the rigid medium 1 is not brought into contact therewith and a space exists therebetween. The roller 25 abuts on the side surface of the rigid medium 1, thereby reducing resistance due to contact. As a result, the rigid medium 1 can be smoothly conveyed. If there is not the roller 25, the rigid medium 1 is rubbed against the plate 8 while being conveyed. Accordingly, there is such a risk that the rigid medium 1 cannot be normally conveyed by an amount desired to be conveyed.
Similarly to the plate 8, on a surface of the roller 25, an ink removing layer 26 is provided, thereby making it possible to easily remove ink when the ink is adhered and fixed thereto. Further, although not shown, it is preferable that, on a lower layer of the ink removing layer 26, an anti-reflection layer like that of the plate 8 be provided. The roller 25 is friction reducing means for reducing friction due to contact between the plate 8 and the rigid medium 1. Other than the roller 25, a circular arc guide for reducing a contact area between the plate 8 and the rigid medium 1 may be used.
The plate 8 can be vertically moved by the vertical movement mechanisms of the rail members 9a and 9b. A first distance 22 is a distance between the upper surface of the plate 8 and the ink discharge surface of the ink jet head 2 in the case where the upper surface of the plate 8 exists at substantially the same height as the recording surface 1a of the rigid medium 1. A second distance 21 is a distance between the upper surface of the plate 8 and the ink discharge surface of the ink jet head 2 in the case where the plate 8 exists in a position closer to the ink jet head 2 than to the recording surface 1a of the rigid medium 1. A third distance 20 is a distance from the recording surface 1a of the rigid medium 1 to a surface on the ink jet head 2 side of the plate 8. The smaller the first distance 21 is, the less the ultraviolet ray applied to the ink jet head 2 becomes. A preferable case is that the third distance 20 is a positive value, that is, the surface on the ink jet head 2 side of the plate 8 is closer to the ink jet head 2 than to the recording surface 1a of the rigid medium 1. In this case, the irradiation direction space from the upper side of the rigid medium 1 to the ultraviolet ray irradiation device 3 becomes narrower, so the ultraviolet ray reaching the head is reduced by the corresponding amount, thereby making it possible to prevent curing of the ink in the nozzle portion. On the other hand, in a case where the first distance 22 becomes larger, and the surface on the ink jet head 2 side of the plate 8 is farther from the ink jet head 2 than the recording surface 1a of the rigid medium 1, the irradiation direction space from the upper side of the rigid medium 1 to the ultraviolet ray irradiation device 3 becomes wider, so the ultraviolet ray reaching the head increases by the corresponding amount. However, when compared to the case where the plate 8 does not exist, the irradiation of the head with the ultraviolet ray is reduced, thereby making it possible to obtain an effect of preventing curing of the ink in the nozzle portion.
Further, in the ink jet recording apparatus, the carriage 7 is allowed to reciprocatingly scan on the recording medium 1 to perform high-speed printing in some cases. In this case, it is desirable that, not only the plate 8 can be provided to one side in the main scanning direction of the rigid medium 1 as shown in
As shown in
Further, in the embodiment of the present invention, the rigid medium 1 is used as the recording medium, also in a case where the recording medium is not limited to the rigid medium and another recording medium is used as another mode, the effect of the present invention is exerted when a space in an irradiation direction of an active ray irradiation device is made narrower. The larger the distance from the platen 4 to the recording surface of the recording medium is, the larger an irradiation direction space for an active ray applied from an irradiation device. Accordingly, for example, the present invention can be used in a case where the rigid medium or a resin sheet is used and for a printer having a structure in which a width of the recording medium and a width of the platen are the same and a space exists outside and below the recording medium, or the like.
Further, of the recording medium, there are ones having warpage or irregular shapes, so, in a case where printing is performed of the medium of those kinds, there is a need for a larger head-medium distance than that at the time of normal printing. In this case, when the heights of the ink jet head 2 and the ultraviolet ray irradiation device 3 are adjusted by raising the carriage rail 15 in the normal printing state of
In the above embodiment, the ink jet recording apparatus of a so-called serial type is illustrated. However, the present invention is not limited to the ink jet recording apparatus of the serial type, and the plate 8 according to the present invention, and a slide mechanism and height adjusting mechanism thereof can be applied to a recording apparatus of a line type regarding. That is, in the recording apparatus of a line type, in order to enable the no-margin printing, an ink jet head unit having a length equal to or larger than a maximum width of the recording medium to be conveyed is fixed in the main scanning direction, and on a medium delivery side with respect to the head unit, an ultraviolet ray irradiation lamp for irradiating a region having a width equal to or larger than the maximum width of the recording medium to be conveyed is disposed. Accordingly, in a case where the recording medium to be conveyed is the thick rigid medium, the space below the ultraviolet ray irradiation lamp positioned outside the region of the rigid medium becomes wider by at least the thickness of the rigid medium than the UV irradiation space on the rigid medium. As a result, there is such a risk that the UV light from the ultraviolet ray irradiation lamp positioned outside the region of the rigid medium enters the nozzle portion of the ink jet head adjacent thereto. Thus, the plate 8 according to the present invention, and the slide mechanism and height adjusting mechanism are effective for the ink jet recording apparatus of the line type.
Note, a recording liquid such as ink discharged by the ink jet head of the present invention is not limited to the UV ink and may be recording liquid having possibility of being cured by being irradiated with an active ray such as a near-infrared ray and an electron ray.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2007-038276 | Feb 2007 | JP | national |
