JP2006076062A - Image recording apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording apparatus which can reduce the amount of incidence of reflected light into a recording head. <P>SOLUTION: Characteristically, in a carriage 4, light shielding members 11 and 31 for absorbing/reflecting ultraviolet reflected light, which are provided between a recording head 5 and an infrared irradiation device 8, have a length equal in dimension to/greater in dimension than the recording width of the recording head 5; and brush parts 13 and 33, which are composed of an elastic material, are provided outside an area corresponding to the recording width of the recording head 5, in such a manner as to come into direct contact with a recording medium P. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image recording apparatus, and more particularly to an image recording apparatus using an ultraviolet curable ink that can be cured by being irradiated with ultraviolet rays.

  In an image recording apparatus recording apparatus that records an image by ejecting and landing droplets of ink on a recording medium arranged to face the recording head from the recording head, the ink absorbs poor ink When an image is recorded on a recording medium, problems such as dragging and bleeding due to uncured / unfixed ink are caused.

  In order to solve such a problem, a suitable image can be obtained by irradiating ultraviolet rays to ink landed on a recording medium by an ultraviolet irradiation device using an ultraviolet curable ink containing a photoinitiator sensitive to ultraviolet rays. There is known a method for recording / fixing (see, for example, Patent Document 1).

  In addition, when ultraviolet curable ink is used, in addition to the ultraviolet irradiation device, a heating member such as a heat plate is disposed in the ink jet printer, and the ink landed on the recording medium is heated by the heat from the heating member. Can be irradiated with ultraviolet rays to sufficiently cure the ink to record a high-definition image (see Patent Document 2).

  Further, in the case of a serial head type image recording apparatus, an ultraviolet irradiation device that is longer than the recording width of the recording head is provided on the side of the recording head, and the printing area and the previous scanning are performed by one scanning of the recording head. By irradiating both the printing area and the ultraviolet ray with ultraviolet rays, the ink can be irradiated with ultraviolet rays a plurality of times without lowering the printing efficiency, and the ink can be sufficiently cured to record a high-definition image (see Patent Document 3). ).

  Here, when curing and fixing the ink, the factors that greatly influence the image quality are the sensitivity of the ultraviolet curable ink, the timing of ultraviolet irradiation and the wavelength and intensity of the light, and the dot diameter, as time passes from the ink landing, Problems such as bleeding become prominent. If the time from when the ink lands on the recording medium to when it is irradiated with ultraviolet rays is long, the dot diameter of the ink that has landed on the recording medium increases, causing blurring or color mixing, and so on, thereby degrading the image quality.

Therefore, in order to shorten the time from when the ink lands on the recording medium to when the ultraviolet rays are irradiated, in the conventional inkjet recording apparatus, the ultraviolet irradiation device 51 is placed close to the recording head 52 as shown in FIG. Provided. In this ink jet recording apparatus, ultraviolet rays emitted from the light source 53 are incident on the recording head 52 side to prevent the ink adhering to the nozzle forming surface 54 and the ink in the nozzles from being cured. The irradiation device 51 includes a cover member 55 that covers the light source 53.
JP 2003-145725 A JP 2002-137375 A JP 2004-1326 A

However, in the conventional image recording apparatus, since the ultraviolet irradiation device 51 is arranged close to the recording head 52, the ultraviolet light irradiated from the light source 53 is applied to the inner surface of the cover member 55 of the ultraviolet irradiation device 51 and the recording medium. Or the like, and may pass between the cover member 55 and the recording medium and enter the recording head 52 side (see FIG. 11). When the reflected light is incident in this way, the ink attached to the nozzle forming surface 54 of the recording head 52 or the ink in the nozzle reacts and thickens or hardens, which tends to cause ink ejection failure. There's a problem.

  An object of the present invention is to reduce the amount of reflected light incident on the nozzle forming surface of a recording head while ensuring a sufficient amount of incident ultraviolet light to cure ink landed on the recording medium. An object of the present invention is to provide an image recording apparatus capable of stably discharging ink over a long period of time.

In order to solve the above problem, the invention according to claim 1 is:
A recording head formed with a nozzle for discharging ultraviolet curable ink onto a recording medium;
An ultraviolet irradiation device comprising an ultraviolet light source that irradiates ultraviolet rays after the ink has landed on the recording medium to cure the ink;
In an image recording apparatus comprising: a light shielding member that is provided between the recording head and the ultraviolet irradiation device and blocks ultraviolet rays from entering the recording head.
The light shielding member is formed longer than the recording width of the recording head, and an area other than the recording width includes a proximity portion that is closer to the recording medium to an area corresponding to the recording width. To do.

  According to the first aspect of the present invention, the light shielding member includes the proximity portion closer to the recording medium in the region other than the recording width of the recording head, so that the reflected light is incident on the recording head side. Therefore, the amount of reflected light incident on the nozzle forming surface of the recording head can be reduced while securing a sufficient amount of incident ultraviolet light to cure the ink that has landed on the recording medium.

The invention according to claim 2 is the image recording apparatus according to claim 1,
A serial recording head;
The proximity portion is provided in a region other than the region corresponding to the recording width of the recording head, further provided with a predetermined gap further downstream from the region in the conveyance direction of the recording medium.

  According to the second aspect of the present invention, the proximity portion is provided in a region other than the region corresponding to the recording width of the recording head and further downstream from the region in the recording medium conveyance direction with a predetermined gap. When the recording medium and the recording head move relative to each other, the light shielding member can be prevented from coming into contact with uncured ink on the recording medium on the downstream side in the transport direction from the recording head.

  A third aspect of the present invention is the image recording apparatus according to the first or second aspect, wherein the light shielding member is provided in parallel to the recording head.

  According to the third aspect of the invention, since the light shielding member is installed in parallel to the recording head, the light shielding member can be attached close to the recording head.

  A fourth aspect of the present invention is the image recording apparatus according to any one of the first to third aspects, wherein the proximity portion is a brush portion made of an elastic material.

  According to the fourth aspect of the present invention, since the proximity portion of the light shielding member is a brush portion made of an elastic material, the light shielding member can be deformed, and the light shielding member and the recording medium can be changed due to a change in the thickness of the recording medium or a jam. Even if the distance changes, it can be dealt with only by deformation of the brush portion.

  The invention described in claim 5 is the invention described in claim 4, wherein the brush portion is provided so as to contact the recording medium.

  According to the invention described in claim 5, since the brush portion is attached so as to be in direct contact with the recording medium, the light shielding member is in contact with the recording medium and is electrically grounded to the recording apparatus main body. It can be energized.

  A sixth aspect of the present invention is the image recording apparatus according to any one of the first to fifth aspects, wherein the ink is a cationic polymerization type ink.

  According to the sixth aspect of the present invention, the amount of reflected light incident on the recording head can be reduced even when a cationically curable ink having high sensitivity to ultraviolet rays is used, so that the stability of the ink from the recording head can be reduced. Discharging can be performed over a long period of time.

  According to the first aspect of the present invention, since the amount of reflected light incident on the nozzle formation surface of the recording head can be reduced by the light shielding member, the viscosity of the ink can be increased by the reaction between the ink and the ultraviolet rays on the nozzle formation surface. Curing can be suppressed and stable ejection of ink from the recording head can be performed over a long period of time.

  According to the second aspect of the present invention, the proximity portion is provided in a region other than the region corresponding to the recording width of the recording head and further downstream from the region in the recording medium conveyance direction with a predetermined gap. The amount of reflected light incident on the nozzle forming surface of the recording head can be reduced without disturbing the uncured dot shape on the recording medium.

  According to the third aspect of the present invention, since the light shielding member can be attached close to the recording head, the amount of reflected light incident on the nozzle forming surface of the recording head can be further reduced.

  According to the fourth aspect of the present invention, since the proximity portion of the light shielding member is freely deformable, the light shielding member can be installed without strictly defining the distance from the recording medium, and the reflected light is incident on the nozzle forming surface of the recording head. The amount can be reduced.

  According to the fifth aspect of the present invention, since the light shielding member has electric conductivity, even if static electricity is generated on the recording medium, it can be effectively neutralized by contact discharge, and the recording head The amount of reflected light incident on the nozzle forming surface can be reduced.

  According to the sixth aspect of the present invention, even when cationically curable ink is used, the amount of reflected light incident on the recording head can be reduced, so that the ink is stably ejected from the recording head over a long period of time. be able to.

  Embodiments of the present invention will be described below with reference to the drawings. However, the scope of the invention is not limited to the illustrated examples.

(First embodiment)
FIG. 1 shows an ink jet recording apparatus according to this embodiment. As shown in FIG. 1, the ink jet recording apparatus according to this embodiment is a serial head type ink jet recording apparatus, and includes a recording apparatus main body 1 and a support base 2 that supports the recording apparatus main body 1.

  A rod-shaped guide rail 3 is provided inside the recording apparatus main body 1, and a carriage 4 is supported on the guide rail 3. The carriage 4 is reciprocated in the main scanning direction A, which is the width direction of the recording medium P, along the guide rail 3 by a carriage driving device (not shown).

  As shown in FIGS. 2 to 4, the carriage 4 is equipped with a recording head 5 that ejects ink of each color of yellow (Y), magenta (M), cyan (C), and black (K).

  A nozzle forming surface 6 is provided on the surface of each recording head 5 facing the recording medium P, and a plurality of nozzles 7 for ejecting ink of each color onto the recording medium P are provided on each nozzle forming surface 6 in the transport direction. It is provided along B.

  Here, the ink used in this embodiment will be described. When the ink is cured, the polymerizable compound contained in the ink undergoes a polymerization reaction, but in this embodiment, the ink contains an activated energy ray curable compound as the polymerizable compound, and activation that initiates the polymerization reaction is performed. It is an ultraviolet curable ink using ultraviolet rays as energy.

  The ultraviolet curable ink containing a polymerizable compound is roughly classified into a radical curable ink containing a radical polymerizable compound and a cation curable ink containing a cationic polymerizable compound, and both inks are inks used in this embodiment. As applicable. However, since the cation curable ink is less or less susceptible to polymerization inhibition by oxygen, the sensitivity to ultraviolet rays is high, and the active species acid has the property of accumulating light energy. Excellent functionality and versatility.

  Further, on both sides of the recording head 5 of the carriage 4 in the main scanning direction A, there are provided ultraviolet irradiation devices 8 for irradiating the ink ejected from the nozzles 7 to the recording medium P and curing the ink. The length in the transport direction B is longer than the recording width of the recording head 5.

  The ultraviolet irradiation device 8 includes a box-shaped cover member 9 that opens toward the recording medium P, and an ultraviolet light source 10 that radiates ultraviolet rays radially is provided inside the cover member 9. Yes.

  A light shielding member 11 is installed between the ultraviolet irradiation device 8 of the carriage 4 and the recording head 5 so as to be substantially perpendicular to the recording medium P. The light shielding member 11 is substantially the same as the ultraviolet irradiation device 8. Has the same length dimension. A portion of the light shielding member 11 corresponding to the recording width of the recording head 5 is formed so as to have a predetermined interval with respect to the recording medium P, and a portion of the light shielding member 11 other than the recording width of the recording head 5 is recorded. A proximity portion that is closer to the recording medium than the portion corresponding to the width is provided. Here, in the present embodiment, as the proximity portion of the light shielding member 11, the brush portion 13 whose tip is in contact with the recording medium P is used.

  The light shielding member 11 is made of a material having ultraviolet absorptivity, and at least the brush portion 13 is made of a material having elasticity, and is freely deformable.

Here, the material having ultraviolet absorptivity is a material that absorbs ultraviolet rays. Specifically, carbon black is used as an inorganic substance, and titanium oxide / zinc oxide / iron oxide (α-Fe ₂ O that has been made into ultrafine particles). ₃ , Fe ₃ O ₄ ) and the like, and organic substances include benzotriazole compounds and materials containing aromatic compounds. In addition to the above-described materials, the light shielding member 11 may be coated with various ultraviolet absorbers such as alumite treatment and other metal oxide treatment methods, plating treatment, vapor deposition, and sputtering treatment. The ones that have been given are also included.

  The light shielding member 11 described above also has electrical conductivity, and is connected to the recording apparatus main body 1 in which electrical continuity is ensured by a conductive member or the like (not shown) and is in contact with the recording medium P via the brush portion 13. Therefore, the recording apparatus main body 1 is electrically grounded, and static electricity generated on the recording medium P can be eliminated by contact discharge.

  One area in which the carriage 4 is movable is a recording area for recording on the recording medium P, and the recording area P is formed of a flat plate member below the carriage 4 and covers the recording medium P. A platen 14 that supports the recording surface is provided.

  An ink tank 15 that supplies ink to an intermediate tank (not shown) of the recording head 5 is provided at the outer end of the recording area, which is the movement range of the carriage 4.

  A maintenance unit 16 for cleaning the recording head 5 is provided at the other end outside the recording area, which is the moving range of the carriage 4.

  On the other hand, the main body 1 of the ink jet recording apparatus is provided with a transport mechanism (not shown) for transporting the recording medium P in the transport direction B. The transport mechanism is provided with, for example, a transport motor and a transport roller (not shown), and transports the recording medium P in the transport direction B by rotating the transport roller by driving the transport motor. Further, the transport mechanism repeats transport and stop of the recording medium P in accordance with the operation of the carriage 4 during image recording, and transports the recording medium P intermittently.

  Next, the operation of this embodiment will be described.

  When predetermined image information is sent to the ink jet recording apparatus, the upper part of the platen 14 is intermittently conveyed in the conveyance direction B while the recording medium P is supported by the platen 14 on the recording surface.

  Each time the conveyance mechanism of the recording medium P is stopped, the carriage 4 is operated to reciprocate in the main scanning direction A immediately above the recording medium P. Along with this, the recording head 5 mounted on the carriage 4, the ultraviolet irradiation device 8 and the light shielding member 11 are moved back and forth immediately above the recording medium P by following the movement of the carriage 4, and the nozzle 7 provided on the recording head 5 The ink of a required color is ejected onto the recording medium P, and the landed ink is irradiated with ultraviolet rays from the ultraviolet light source 10 of the ultraviolet irradiation device 8. As a result, the ink is cured and an image is formed.

  At this time, the ultraviolet rays irradiated radially from the ultraviolet light source 10 irradiate the ink on the recording medium P, and are reflected by the inner surface of the cover member 9 and the opposing recording medium P. Of this reflected light, a part of the reflected light reflected to the recording head 5 side and passing between the cover member 9 and the recording medium P is made by the light shielding member 11 before entering the nozzle forming surface 6 of the recording head 5. Can be blocked. Specifically, as shown in FIG. 5, in a region corresponding to the recording width of the recording head 5, a part of the reflected light toward the recording head 5 can be blocked by the light shielding member 11. On the other hand, in a region other than the recording width of the recording head 5, the reflected light toward the recording head 5 can be completely blocked by the light shielding member 11 and the brush portion 13. Therefore, the amount of reflected light incident on the nozzle forming surface 6 of the recording head 5 can be greatly reduced.

  Further, since the brush portion 13 of the light shielding member 11 is made of an elastic material and can be freely deformed, even if a change in the thickness of the recording medium P or a jam occurs, the distance between the carriage 4 and the recording medium P changes. The brush portion 13 is deformed and the distance from the recording medium P can be adjusted.

  Furthermore, since the light-shielding member 11 that has ultraviolet absorbency and conductivity is in direct contact with the recording medium P, the static electricity generated on the recording medium P can be eliminated by contact discharge.

  As described above, according to the present embodiment, the light shielding member 11 can block the reflected light irradiated from the ultraviolet light source 10 from being incident on the nozzle forming surface 6 of the recording head 5, and thus land on the recording medium P. It is possible to reduce the amount of reflected light incident on the nozzle forming surface 6 of the recording head 5 while ensuring a sufficient amount of ultraviolet light for curing the ink that has been cured, and stable ink ejection from the recording head 5 for a long period of time. Can be done over.

(Second embodiment)
Next, a second embodiment of the ink jet recording apparatus according to the present invention will be described with reference to FIG. Here, the same reference numerals are assigned to substantially the same configurations as those in the first embodiment.

  In the ink jet recording apparatus of the present embodiment, a light shielding member 31 is mounted on the carriage 4, and the light shielding member 31 is in a region other than the region corresponding to the recording width of the recording head 5 and further in the transport direction than that region. A brush portion 33 is provided on the downstream side of B with a predetermined gap therebetween. In the present embodiment, except for the above-described points of the light shielding member 31, the configuration is substantially the same as that of the ink jet recording apparatus of the first embodiment, and image recording can be performed in the same manner as in the first embodiment.

  In the present embodiment, even when an area containing uncured ink on the recording medium P is conveyed downstream in the conveying direction B from the recording width of the recording head 5 during image recording, the light shielding member 31 has the brush portion 33. Since the recording head 5 is provided with a predetermined gap other than the recording width of the recording head 5 and further downstream of the recording head 5 in the transport direction B, the uncured ink of the recording medium P is applied to the brush portion 33 of the light shielding member 31. There is no contact.

  This embodiment can also be applied to an ink jet recording apparatus that records an image by so-called interleaving. In the image recording by interleaving, image recording in the same area of the recording medium P is completed by scanning a plurality of times. Therefore, the recording head 5 and the area containing the uncured ink on the recording medium P are moved relative to each other by a minute amount. Are sequentially transported downstream in the transport direction B from the area of the recording medium P that has been completely finished. For this reason, the recording head 5 and the region containing the uncured ink on the recording medium P are relatively moved before the ink is completely cured. As described above, the uncured ink on the recording medium P is removed from the brush of the light shielding member 31. There is no contact with the portion 33. Therefore, since uncured ink does not contact the light shielding member 31, good image recording can be performed without disturbing the dot shape.

  As described above, in the present embodiment, even in the ink jet recording apparatus that records an image by interleaving as described above, the recording head 5 is secured while securing a sufficient amount of ultraviolet light for curing the ink that has landed on the recording medium P. This makes it possible to reduce the amount of reflected light incident on the nozzle forming surface 6 and to stably discharge ink from the recording head 5 over a long period of time.

(Third embodiment)
Next, a third embodiment of the ink jet recording apparatus according to the present invention will be described with reference to FIGS. Hereinafter, the same reference numerals are assigned to the configurations substantially the same as those of the first embodiment.

  The present embodiment shows a case of a line head type ink jet recording apparatus. In the line head type ink jet recording apparatus, the recording head 5, the ultraviolet irradiation device 8, and the light shielding member 11 are elongated substantially the same as the width of the recording medium P, and each is substantially parallel to the width direction of the recording medium P. It is prepared to become. The recording medium P is conveyed immediately below the recording head 5, the ultraviolet irradiation device 8, and the light shielding member 11, so that an image is recorded.

  7 and 8 show line head type ink jet recording apparatuses in which only one ultraviolet irradiation device 8 is provided on the downstream side in the transport direction B from each recording head 5. In this case, the light shielding member 11 is installed only at one location between the recording head 5 and the ultraviolet irradiation device 8.

  In the ink jet recording apparatus of FIGS. 7 and 8, the length of the recording head 5, the ultraviolet irradiation device 8, and the light shielding member 11 is used, and the three members are substantially parallel to the width direction of the recording medium P. The configuration is substantially the same as that of the ink jet recording apparatus of the first embodiment except for the points arranged in FIG.

  With the above configuration, a part of the ultraviolet reflected light that is irradiated from the ultraviolet light source 10 and is reflected by the cover member 9 or the recording medium P and incident on the recording head 5 side is recorded in the recording head 5 and the ultraviolet irradiation device 8. Are shielded by the light shielding member 11 provided between the two. Therefore, even in a line head type ink jet recording apparatus, the amount of reflected light incident on the nozzle forming surface 6 of the recording head 5 can be reduced and ink can be stably ejected from the recording head 5 over a long period of time.

  FIG. 9 shows a line head type ink jet recording apparatus in which an ultraviolet irradiation device 8 is provided between the recording heads 5. In this case, the light shielding member 11 is disposed between the recording head 5 and the ultraviolet irradiation device 8.

  The ink jet recording apparatus described above has substantially the same configuration as the ink jet recording apparatus of the above-described embodiment shown in FIGS. 7 and 8 except for the positional relationship of the recording head 5, the ultraviolet irradiation device 8, and the light shielding member 11.

  With the above configuration, the reflected light that is irradiated from each ultraviolet light source 10 and is incident on each recording head 5 side is applied to each light shielding member 11 disposed between the recording head 5 and the ultraviolet irradiation device 8. Blocked. Therefore, even if a plurality of ultraviolet irradiation devices 8 are provided in the line head type ink jet recording apparatus, the amount of reflected light incident on the nozzle forming surface 6 of each recording head 5 is reduced, and Ink can be stably ejected over a long period of time.

1 is a perspective view showing an embodiment of an image recording apparatus according to the present invention. It is a bottom view of the carriage in a first embodiment. It is the sectional view on the AA line in FIG. It is a side view of the carriage in a first embodiment. It is explanatory drawing which shows the reflective state of the ultraviolet-ray in 1st embodiment. It is a side view of the carriage in a second embodiment. It is a side view of the image recording device in a third embodiment. It is a front view of the image recording device in a third embodiment. It is a side view of the image recording device in a third embodiment. It is a front view of the carriage in the conventional inkjet recording device. It is explanatory drawing which shows the reflective state of the ultraviolet-ray in the conventional inkjet recording device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Recording apparatus main body 4 Carriage 5 Recording head 7 Nozzle 8 Ultraviolet irradiation apparatus 9 Cover member 10 Ultraviolet light source 11, 31 Light-shielding member 13, 33 Brush part A Main scanning direction B Conveying direction P Recording medium

Claims (6)

A recording head formed with a nozzle for discharging ultraviolet curable ink onto a recording medium;
An ultraviolet irradiation device comprising an ultraviolet light source that irradiates ultraviolet rays after the ink has landed on the recording medium to cure the ink;
In an image recording apparatus comprising: a light shielding member that is provided between the recording head and the ultraviolet irradiation device and blocks ultraviolet rays from entering the recording head.
The light shielding member is formed longer than the recording width of the recording head, and an area other than the recording width includes a proximity portion that is closer to the recording medium to an area corresponding to the recording width. Image recording device. A serial recording head;
2. The proximity portion is provided in a region other than a region corresponding to a recording width of the recording head, and further provided with a predetermined gap further downstream from the region in the conveyance direction of the recording medium. The image recording apparatus described.   The image recording apparatus according to claim 1, wherein the light shielding member is provided in parallel to the recording head.   The image recording apparatus according to claim 1, wherein the proximity portion is a brush portion made of an elastic material.   The image recording apparatus according to claim 4, wherein the brush portion is provided so as to contact the recording medium.   The image recording apparatus according to claim 1, wherein the ink is a cationic polymerization ink.

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