JP2005279942A - Image recording apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To carry out stable discharging of ink for a long term by reducing ultraviolet rays which leak to a recording head surface while suitable ultraviolet irradiation is secured for ink struck on a recording medium. <P>SOLUTION: A protecting member formed by combining a plurality of plate-like members in a lattice shape is set at an irradiation face of an ultraviolet irradiation device. An ultraviolet reflectance of a face opposed to the recording head side of the protecting member is made lower than an ultraviolet reflectance of the other face. <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 general, in an image recording apparatus that records an image by ejecting and landing a small droplet of ink on a recording medium arranged to face the recording head from the recording head, recording with poor ink absorption When an image is recorded on a medium, problems such as bleeding due to uncured / unfixed inks occur.

  In order to solve such a problem, for example, in Patent Document 1, ultraviolet light is irradiated to ink landed on a recording medium by an ultraviolet irradiation device using an ultraviolet curable ink containing a photoinitiator sensitive to ultraviolet light. Thus, there is provided a method for curing and fixing a suitable ink by controlling the dot diameter, the bleeding between dots, and the penetration of the ink into the recording medium.

  In general, in an image recording apparatus of the UV inkjet recording system as described above, an ink containing a photoinitiator having a predetermined sensitivity to ultraviolet rays is used, and the ink landed on the recording medium is irradiated with ultraviolet rays. As a result, the ink is cured and fixed to the recording medium. In this case, if it takes a long time from the landing of the ink to the recording medium to the irradiation of the ultraviolet rays, problems such as an increase in the dot diameter of the ink that has landed on the recording medium, bleeding of the dots, and penetration of the ink into the recording medium become significant. Therefore, it is desirable to shorten the time from ink ejection to ultraviolet irradiation as much as possible.

Therefore, in the general ink jet recording apparatus disclosed in Patent Document 1, an ultraviolet irradiation apparatus is provided in the vicinity of the recording head in order to immediately irradiate the ink landed on the recording medium with ultraviolet light.
JP-A-60-132767

  However, in the case of Patent Document 1, when a light source for irradiating ultraviolet light is arranged close to the recording head, the ultraviolet light emitted from the light source is placed inside the housing of the ultraviolet irradiation device on which the light source is mounted or the surface of the recording medium. There is a risk of reflection and incidence on the ejection surface of the recording head. When ultraviolet rays enter in this way, there is a problem in that ink adhering to the ejection surface of the recording head reacts with the ultraviolet rays to thicken or harden, and ink ejection defects are likely to occur.

  Furthermore, inks can be roughly classified into radical polymerization inks and cationic polymerization inks. Unlike radical polymerization inks, cationic polymerization inks are not susceptible to polymerization by oxygen and are highly sensitive to ultraviolet rays. Certain acids have the property of storing light energy. For this reason, the cationic polymerization ink has a problem that it is more susceptible to ultraviolet rays at the discharge port on the surface of the recording head than the radical polymerization ink.

  An object of the present invention is to reduce the amount of ultraviolet light incident on the surface of the recording head, thereby ensuring a sufficient and suitable amount of ultraviolet light incident on the recording surface on the recording medium, and stable ink ejection from the recording head over a long period of time. An object of the present invention is to provide an image recording apparatus that can be used.

  The invention described in claim 1 includes a recording head that discharges ink that is cured by irradiating ultraviolet rays, and an ultraviolet irradiation device that cures the ink and emits light, and discharges the ultraviolet curable ink to a recording medium. In the image recording apparatus for recording an image by irradiating with ultraviolet rays after that, a protective member formed by combining a plurality of plate-like members in a lattice shape is provided on the irradiation surface of the ultraviolet irradiating device, and the recording member side of the protective member The ultraviolet reflectance of the first surface opposite to the first surface is lower than the ultraviolet reflectance of the side opposite to the first surface and the second surface.

  According to the first aspect of the present invention, the protective member formed by combining a plurality of plate-like members in a lattice shape is provided on the irradiation surface of the ultraviolet irradiation device, and the first surface of the protective member facing the recording head side is provided. Since the ultraviolet reflectance is lower than the ultraviolet reflectance of the second surface opposite to the first surface, the ultraviolet light from the ultraviolet irradiation device is applied to the surface of the protective member facing the recording head. When irradiated, the amount of ultraviolet rays reflected to the recording head can be reduced, and as a result, the incidence of ultraviolet rays on the ejection surface of the recording head can be reduced.

  In addition, when a jam occurs between the ultraviolet irradiation device and the recording medium due to a clogging of the recording medium or a conveyance failure, the recording medium in which the protective member is bent due to the jam makes contact with or enters the ultraviolet irradiation device. It can be prevented.

  According to a second aspect of the present invention, in the image recording apparatus according to the first aspect, the surface of the protective member facing the recording head is coated with an ultraviolet absorber.

  According to the second aspect of the present invention, since the ultraviolet absorber is coated on the first surface of the protective member that faces the recording head, the first surface of the protective member that faces the recording head is used. When the surface 1 is irradiated with ultraviolet rays, the ultraviolet absorber can absorb the ultraviolet rays, and the amount of ultraviolet rays reflected to the recording head side can be reduced. It can reduce the incidence of ultraviolet rays.

  According to a third aspect of the present invention, in the image recording apparatus according to the first or second aspect, the protective member is made of aluminum.

  According to the invention described in claim 3, since the protective member is made of aluminum having an ultraviolet reflectance of 80% or more, the surface other than the first surface facing the recording head side of the protective member is irradiated. The reflected ultraviolet rays can be efficiently reflected, and the ink discharged onto the recording medium can be efficiently irradiated with the ultraviolet rays. In addition, since the protective member is made of aluminum, durability against heat can be improved, and deformation of the member can be reduced.

  Even when a jam occurs in the recording medium, the protective member is made of aluminum, so that a sufficient strength against contact by the jam can be ensured.

  According to a fourth aspect of the present invention, in the image recording apparatus according to any one of the first to third aspects, the pitch between the plate-like members becomes narrower as the protective member approaches the recording head. It is characterized by being arranged like this.

  According to the fourth aspect of the present invention, since the protective member is arranged so that the pitch between the plate-like members becomes narrower as it approaches the recording head, the ultraviolet rays irradiated to the vicinity of the recording head. This prevents a part of the light from being reflected on the recording head side, thereby reducing the amount of incident light on the ejection surface of the recording head.

  According to a fifth aspect of the present invention, in the image recording apparatus according to the first to fourth aspects, the light source housed in the ultraviolet irradiation device is a cold cathode sterilization lamp, a hot cathode sterilization lamp, a low pressure mercury lamp, or an electrodeless lamp. , An excimer lamp, a high-pressure mercury lamp, a metal halide lamp, a xenon lamp, or an LED.

  According to the invention described in claim 5, the ultraviolet irradiation device is any one of a cold cathode sterilization lamp, a hot cathode sterilization lamp, a low pressure mercury lamp, an electrodeless lamp, an excimer lamp, a high pressure mercury lamp, a metal halide lamp, a xenon lamp, or an LED. Even when one of them is used, the first surface of the protective member facing the recording head and the second surface opposite to the first surface absorb and reflect ultraviolet rays, respectively, so that the recording head discharge surface Can be reduced.

  According to a sixth aspect of the present invention, in the image recording apparatus according to the first to sixth aspects, the ink ejected from the recording head is a cationic curable ink.

  According to the sixth aspect of the present invention, the ink used in the image recording apparatus has a cationic curable property. That is, the cationic curable ink has higher sensitivity to ultraviolet rays than the radical curable ink and has the property of accumulating the light energy of the active species acid, so that the ink is cured by irradiation with ultraviolet rays. Even when such ink is used, the first surface of the protective member facing the recording head and the second surface opposite to the first surface are incident on the recording head. By absorbing or reflecting each ultraviolet ray to be emitted, it is possible to reduce the incidence on the recording head ejection surface.

  According to a seventh aspect of the present invention, in the image recording apparatus, a recording medium mounting unit that supports a recording medium, a recording head that discharges ink that is cured by irradiating light to the recording medium, and the recording medium An ultraviolet irradiation device having a light source for irradiating light for curing the ink on the recording medium, and a partition wall portion and the partition wall portion are formed between the recording medium mounting means and the ultraviolet irradiation device. A protective member having a plurality of slit portions, and the ultraviolet reflectance of the first surface of the partition wall facing the recording head is that of the second surface opposite to the first surface. It is characterized by being lower than the ultraviolet reflectance.

  According to the seventh aspect of the present invention, a protective member having a partition wall and a plurality of slits formed by the partition wall is provided between the recording medium mounting means and the ultraviolet irradiation device to protect the recording medium. Since the ultraviolet reflectance of the first surface facing the recording head side of the member is lower than the ultraviolet reflectance of the second surface opposite to the first surface, the ultraviolet light from the ultraviolet irradiation device However, when the first surface of the protective member facing the recording head side is irradiated, the amount of ultraviolet rays reflected to the recording head side can be reduced, and as a result, the ultraviolet rays are incident on the ejection surface of the recording head. Can be reduced.

  According to an eighth aspect of the present invention, in the image recording apparatus, a recording medium mounting unit that supports a recording medium, a recording head that discharges ink that is cured by irradiating light onto the recording medium, and the recording head An ultraviolet irradiation device having a light source for irradiating light for curing the ink on the recording medium, and a partition wall portion and the partition wall portion are formed between the recording medium mounting means and the ultraviolet irradiation device. A protective member having a plurality of slit portions, and the ultraviolet reflectance of the first surface of the partition wall portion facing the recording head is 50% or less.

  According to the invention described in claim 8, a protective member having a partition wall portion and a plurality of slit portions formed by the partition wall portion is provided between the recording medium mounting means and the ultraviolet irradiation device, By setting the ultraviolet reflectance of the first surface facing the recording head in the previous period to 50% or less, the ultraviolet light from the ultraviolet irradiation device was irradiated to the first surface of the protective member facing the recording head. In this case, the amount of ultraviolet light reflected toward the recording head can be reduced to less than half, and as a result, the incidence of ultraviolet light on the ejection surface of the recording head can be reduced.

  According to a ninth aspect of the present invention, in the image recording apparatus, a recording medium mounting unit that supports a recording medium, a recording head that discharges ink that is cured by irradiating light to the recording medium, and the recording head An ultraviolet irradiation device having a light source for irradiating light for curing the ink on the recording medium, and a partition wall portion and the partition wall portion are formed between the recording medium mounting means and the ultraviolet irradiation device. A protective member having a plurality of slit portions, and the ultraviolet reflectance of the second surface opposite to the first surface of the partition wall facing the recording head is 60% or more. Features.

  According to the invention of claim 9, a protective member having a partition wall and a plurality of slits formed by the partition wall is provided between the recording medium mounting unit and the ultraviolet irradiation device, By setting the ultraviolet reflectance of the second surface opposite to the first surface opposite to the recording head of the partition wall to be 60% or more, the ultraviolet light from the ultraviolet irradiation device is changed to the second surface. It is possible to secure 60% or more of ultraviolet rays irradiated onto the recording medium when the surface is irradiated, and as a result, it is possible to irradiate with sufficient ultraviolet rays to cure the ink landed on the recording medium.

  According to a tenth aspect of the present invention, in the image recording apparatus according to any one of the seventh to ninth aspects, the protection member is configured in a lattice shape.

  According to a tenth aspect of the present invention, in the image recording apparatus according to any one of the seventh to ninth aspects, the protective member is configured in a lattice shape so that the entire protective member is resistant to an external impact. When a jam occurs due to clogging of the recording medium or poor conveyance between the ultraviolet irradiation device and the recording medium, the recording medium bent by the jam is not damaged. It can prevent contacting or entering the irradiation device.

  The invention according to claim 11 is the image recording apparatus according to any one of claims 7 to 9, wherein the image recording apparatus moves the recording medium and the ultraviolet irradiation device relatively. It is characterized by having.

  According to an eleventh aspect of the present invention, in the image recording apparatus according to any one of the seventh to ninth aspects, the image recording apparatus includes a moving unit that relatively moves the recording medium and the ultraviolet irradiation apparatus. Even so, the first surface of the partition wall facing the recording head absorbs ultraviolet light, and the second surface opposite to the first surface reflects ultraviolet light. UV light that is sufficient to cure the ink ejected onto the recording medium can be applied while reducing the incidence of ultraviolet light on the ejection surface.

  According to a twelfth aspect of the present invention, in the invention of the eleventh aspect, with respect to the distance between the recording medium placing means and the protective member, one end of the protective member in the relative movement direction of the ultraviolet irradiation device in the previous period and the recording The image recording apparatus according to claim 11, wherein a first distance between the recording medium mounting unit and the medium mounting unit is greater than a second distance between a portion other than the one end and the recording medium mounting unit.

  According to the twelfth aspect of the present invention, the distance between the recording medium placing unit and the protective member is between the one end in the relative movement direction of the ultraviolet irradiation device and the recording medium placing unit. The first distance is larger than the second distance between the portion other than the one end and the recording medium placing means, so that the recording medium placing means can move with the recording medium placing means when moving in the relative direction. Even when the recording medium is clogged or bent due to a conveyance failure between the ultraviolet irradiation devices, the first distance larger than the second distance guides the deflection to prevent sham. .

  According to a thirteenth aspect of the present invention, in the image recording apparatus according to any one of the seventh to ninth aspects, the protective member is attached to the ultraviolet irradiation device.

  According to the thirteenth aspect of the invention, since the protective member is attached to the ultraviolet irradiation device, the position of the ultraviolet irradiation device with respect to the recording head is always kept constant. The reflection of ultraviolet rays can always be kept constant, and the ultraviolet irradiation device can be reliably protected.

  The invention described in claim 14 is characterized in that, in the invention described in claim 13, the protection member is detachable from the ultraviolet irradiation device.

  According to the fourteenth aspect of the present invention, since the protective member is detachable, the protective member is damaged by a jam generated between the recording medium placing unit and the ultraviolet irradiation device. Even if it exists, only a protection member can be replaced | exchanged, without replacing | exchanging the whole ultraviolet irradiation device.

  According to a fifteenth aspect of the present invention, in the image recording apparatus according to any one of the seventh to ninth aspects, the integrated illuminance measured via the protective member on the recording medium placing unit is integrated illuminance. A. When the integrated illuminance B measured on the recording medium placing means without the protective member is defined as integrated illuminance B, 0.7 ≦ A / B <1.0. And

  According to a fifteenth aspect of the present invention, in the image recording apparatus according to any one of the seventh to ninth aspects, between the ultraviolet irradiation device and a recording medium supported by the recording medium mounting means. When the protective member is provided, the light density and the irradiation spectrum are changed, and the maximum illuminance of ultraviolet rays irradiated on the recording medium in the previous period is reduced as compared with the case where the protective member is not provided. When the integrated illuminance A measured through the protective member and the integrated illuminance measured without the protective member are B, the relationship between the two is 0.7 ≦ A / B <1.0. In addition, it is possible to irradiate ultraviolet rays sufficient to cure the ink ejected on the recording medium.

  According to a sixteenth aspect of the present invention, in the image recording apparatus according to any one of the seventh to ninth aspects, the ultraviolet irradiation device includes a housing and quartz glass.

  According to a sixteenth aspect of the present invention, in the image recording apparatus according to any one of the seventh to ninth aspects, since the ultraviolet irradiation device includes a housing and quartz glass, the light source requires a cooling fan. Even in a high-pressure mercury lamp or the like, the air flow generated by the cooling fan does not leak from the ultraviolet irradiation device to the recording head side and does not hinder the landing of ink mist. Also in such an ultraviolet irradiation device, the first surface of the partition wall facing the recording head absorbs ultraviolet light from a light source to reduce incidence on the ejection surface of the recording head, and the first surface The second surface on the opposite side can irradiate with sufficient ultraviolet rays to cure the ink landed on the recording medium.

  According to the first aspect of the present invention, the ultraviolet reflectance of the first surface of the protective member facing the recording head is lower than the ultraviolet reflectance of the second surface opposite to the first surface. By doing so, when the ultraviolet light from the ultraviolet irradiation device is irradiated on the surface of the protective member facing the recording head side, the amount of ultraviolet light reflected on the recording head side can be reduced. The incidence of ultraviolet rays on the ejection surface of the recording head can be reduced, and as a result, ink curing and fixing on the ejection surface of the recording head can be prevented. In addition, stable ink ejection can be achieved, and sufficient ultraviolet irradiation to the ink landed on the recording medium and protection of the irradiated surface can be performed.

  According to the second aspect of the invention, the first surface of the protective member is irradiated with ultraviolet rays by coating the first surface of the protective member facing the recording head side with the ultraviolet absorber. In this case, since the ultraviolet ray can be absorbed by the ultraviolet absorber, the amount of ultraviolet ray reflected to the recording head side can be reduced, and as a result, the incidence of the ultraviolet ray on the ejection surface of the recording head is reduced, Curing and fixing of the ink on the ejection surface of the recording head can be prevented, and clogging of the ejection port can be prevented and long-term stable ejection can be achieved.

  According to the third aspect of the present invention, the protective member is made of aluminum so that the ultraviolet rays applied to the surface other than the surface facing the recording head of the protective member can be efficiently reflected. In addition, it is possible to efficiently irradiate the ink ejected onto the recording medium with ultraviolet rays. Moreover, durability against heat can be improved, deformation of the member can be reduced, and sufficient strength against contact due to jam of the recording medium can be ensured.

  According to the fourth aspect of the present invention, the recording head is arranged such that the pitch between the plate-like members becomes narrower as the recording head is approached, and a part of ultraviolet rays irradiated in the vicinity of the recording head is blocked. As a result, the amount of incident light on the ejection surface of the recording head can be reduced, and ink curing and fixing on the ejection surface of the recording head can be prevented. it can.

  According to the invention described in claim 5, the light source is any one of a cold cathode sterilization lamp, a hot cathode sterilization lamp, a low pressure mercury lamp, an electrodeless lamp, an excimer lamp, a high pressure mercury lamp, a metal halide lamp, a xenon lamp or an LED. Even so, it is possible to reliably reduce the amount of the ultraviolet rays irradiated from the ultraviolet irradiation lamp to the recording head surface.

  According to the sixth aspect of the present invention, even if the ink is a cation curable ink, it is possible to reliably reduce the incident amount of ultraviolet rays irradiated from the ultraviolet irradiation device onto the surface of the recording head.

  According to the seventh aspect of the present invention, the ultraviolet reflectance of the first surface facing the recording head side of the protective member is lower than the ultraviolet reflectance of the second surface opposite to the first surface. Therefore, when the ultraviolet light from the ultraviolet irradiation device is irradiated on the first surface of the protective member facing the recording head, the amount of ultraviolet light reflected on the recording head can be reduced. As a result, it is possible to reduce the incidence of ultraviolet rays on the ejection surface of the recording head, prevent clogging due to ink curing and fixing on the ejection surface of the recording head, and perform suitable image recording over a long period of time. It becomes.

  According to the eighth aspect of the present invention, the ultraviolet reflectance of the first surface of the partition wall facing the recording head is 50% or less, so that the protective member faces the recording head. When the first surface is irradiated with ultraviolet rays, the amount of ultraviolet rays reflected to the recording head can be reduced to less than half, and as a result, the incidence of ultraviolet rays on the ejection surface of the recording head can be reduced. In addition, it is possible to prevent clogging due to ink curing and fixing on the ejection surface of the recording head, and to perform suitable image recording over a long period of time.

  According to the ninth aspect of the present invention, since the ultraviolet reflectance of the second surface opposite to the first surface facing the recording head of the partition wall portion is 60% or more, the recording medium It is possible to irradiate with sufficient ultraviolet light to cure the ink that has landed on it, and it is possible to record high-quality and high-quality images.

  According to the tenth aspect of the present invention, since the protective member is configured in a lattice shape, durability against external impacts is increased. Therefore, a recording medium is provided between the ultraviolet irradiation device and the recording medium. Even when a jam occurs due to clogging or poor conveyance, the recording medium is durable against the jam and has an effect of preventing the recording medium from contacting or entering the ultraviolet irradiation device. Furthermore, there is an effect that ultraviolet rays sufficient for curing can be continuously irradiated toward the ink discharged onto the recording medium.

  According to the eleventh aspect of the present invention, even if the moving means relatively moves the recording medium and the ultraviolet irradiation device, the first surface of the partition wall facing the recording head is Absorbs ultraviolet rays, reduces incidence on the recording head side, prevents ink curing and fixing on the ejection surface of the recording head, and the second surface opposite to the first surface is on the recording medium. Since the ultraviolet rays sufficient for curing the ink that has landed are reflected, the same effects as those of the image recording apparatus according to any one of claims 7 to 9 can be obtained.

  According to the twelfth aspect of the present invention, the first distance between the one end portion in the relative movement direction of the ultraviolet irradiation apparatus and the recording medium placing means is a portion other than the one end portion and the recording. Since the distance is larger than the second distance between the medium placing unit and the moving medium in the relative direction, the recording medium is deflected between the recording medium placing unit and the ultraviolet irradiation device due to clogging or conveyance failure. Even if this occurs, the first distance larger than the second distance in the previous period can guide the deflection to prevent jamming, prevent damage to the ultraviolet irradiation device and the like, and maintain the image recording apparatus. There is an effect that makes possible.

  According to the invention of claim 13, since the position of the ultraviolet irradiation device with respect to the recording head is always kept constant, the reflection of the ultraviolet rays emitted from the ultraviolet irradiation lamp can be kept constant, and Since the ultraviolet irradiation device can be reliably protected, there is an effect that high-quality and high-quality image recording is possible over a long period of time.

  According to the fourteenth aspect of the present invention, when the protective member is damaged due to a jam or the like, or when the ink adheres to the protective member and the reflectance of ultraviolet rays is reduced, the entire ultraviolet irradiation device is not replaced. Only the protective member can be exchanged, and there is an effect that it is excellent in maintainability and economy.

  According to the invention described in claim 15, when the integrated illuminance A measured through the protective member and the integrated illuminance measured without the protective member are B, the relationship between the two is 0.7 ≦ By setting A / B <1.0, there is an effect that the irradiation of ultraviolet rays sufficient to cure the ink ejected onto the recording medium is ensured and high-quality and high-quality image recording is possible.

  In the invention described in claim 16, since the ultraviolet irradiation device has a housing and quartz glass, even if the light source is a high-pressure mercury lamp that requires a cooling fan, the air flow generated by the cooling fan generates the ultraviolet light. There is no leakage from the irradiation device to the recording head side, and there is an effect that enables high-quality and high-quality image recording without impairing the landing of the ink mist.

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

  FIG. 1 is a perspective view showing a main configuration of an embodiment when the image recording apparatus according to the present invention is applied to an ink jet printer. The ink jet printer 1 according to the present embodiment is a serial head type ink jet printer, and includes a printer main body 1A and a support base 1B that supports the printer main body 1A.

  Inside the printer main body 1A, a rod-shaped guide rail 3 is provided, and a carriage 5 is supported on the guide rail 3. The carriage 5 reciprocates along the guide rail 3 in the main scanning direction X, which is the width direction of the recording medium P, by a carriage driving device (not shown).

The carriage 5 is mounted with a recording head 4 that discharges yellow (Y), magenta (M), cyan (C), and black (K) inks on the recording medium P.
In the recording head 4, a plurality of nozzles (not shown) that eject ink are arranged along the sub-scanning direction Y.

  Here, the ink used in the present embodiment will be described. When the ink is cured, the polymerizable compound contained in the ink undergoes a polymerization reaction. In the present embodiment, the ink contains an activation energy ray-curable compound as the polymerizable compound, and the activation energy for starting the polymerization reaction is included. It is an ultraviolet curable ink using ultraviolet rays.

  The ultraviolet curable ink is roughly classified into a radical curable ink containing a radical polymerizable compound and a cation curable ink containing a cationic polymerizable compound as a polysynthetic compound. Both inks are used in this embodiment. A hybrid ink in which a radical curable ink and a cationic curable ink are combined may be applied as an ink used in the main form.

  However, in the present embodiment, in particular, the cationic curable ink with little or no inhibition of the polymerization reaction by oxygen is superior in functionality and versatility. Cationic heavy synthetic ink is used. The cation curable ink used in the present embodiment is specifically a mixture containing at least a cation polymerizable compound such as an oxetane compound, an epoxy compound, and a vinyl ether compound, a photo cation initiator, and a color material, It has the property of being cured by irradiation with ultraviolet rays.

  Further, at both ends of the recording head 4 of the carriage 5 in the main scanning direction X, there are provided ultraviolet irradiation devices 2 for irradiating the ink ejected from the nozzles onto the recording medium P and curing the ink. Yes.

  Next, the ultraviolet irradiation device 2 will be described in detail with reference to FIGS. This ultraviolet irradiation device 2 shows an example in which a high-pressure mercury lamp is used as a light source. The ultraviolet irradiation device 2 has a box-shaped housing 12 having an open lower surface facing the recording medium P, and a light source 10 is arranged inside the housing.

Around the light source 10, there is provided a reflection plate 18 that reflects the ultraviolet rays emitted from the light source 10 toward the recording medium. A fan 7 is accommodated in the upper part of the housing 12, and the inside of the housing 12 can be cooled by driving the fan 7. A quartz glass 9 capable of transmitting ultraviolet rays is provided on the surface of the housing 12 that faces the recording medium P. A protection member 11 is attached to the ultraviolet irradiation device 2 so as to cover the quartz glass 9.
In the present embodiment, the ultraviolet irradiation device 2 has the housing 12, and the protective member 11 is provided on the surface of the housing 12 facing the recording medium P. However, the present invention is not limited to this. Instead, the light source 10 or the ultraviolet irradiation device is not shielded between the recording medium P supported by the recording medium mounting means and the light source 10 or the ultraviolet irradiation device 2 so as to prevent the ink from being cured. 2 may be provided with a protective member that functions to prevent physical contact and / or adhesion of ink.

  The protection member 11 is configured by combining a plurality of plate-like members 25 having a long shape in a lattice shape, and the protection member 11 is configured by a material having a high ultraviolet reflectance such as aluminum whose surface is mirror-finished. Yes. By using aluminum having a high ultraviolet reflectance, the protective member itself can sufficiently irradiate the ink landed on the recording medium without reducing the ultraviolet rays irradiated from the light source. At the same time, especially when a high-pressure mercury lamp or the like is used as the light source, deformation of the protective member 7 can be prevented as a heat countermeasure.

Here, FIG. 4 is a perspective view showing another embodiment of the protective member 11 in the ultraviolet irradiation device 2. As shown in FIG. 4, the protection member 11 may have a partition wall portion 15 formed of a plate-like member and a plurality of slit portions 16 formed of the partition wall portion.
That is, with respect to the protective member 11, in the present embodiment, an example of a grid-like partition wall is shown. However, the light source 10 or the ultraviolet irradiation device 2 is not shielded without blocking ultraviolet rays that prevent ink from being cured. As long as it functions to prevent physical contact and / or ink adhesion, the shape is not limited to a lattice shape, and may be a honeycomb structure, a slit shape, a concentric circle, or the like.
When these structures are arranged with respect to the ultraviolet irradiation device 2, they have air permeability and do not trap heat generated from the ultraviolet irradiation device 2.
In addition, when ink or the like adheres to the protective member 11 and there is a risk of reducing the irradiation of ultraviolet rays, the protective member 11 can be attached to and detached from the ultraviolet irradiation device 20 so that the protective member 11 can be replaced. Preferably it is attached.

  The protective member 11 is made of a metal such as aluminum as long as it has a high ultraviolet reflectivity and can secure a sufficient irradiation amount for curing and fixing the ink that has been applied to the recording medium by the ultraviolet light from the light source 10. It is not limited. For example, a cold mirror in which a thin film of a metal compound mainly containing aluminum is deposited on the glass surface may be used. Furthermore, a method of plating, vapor deposition, and sputtering of a reflective material having a high ultraviolet reflectance on another metal or resin may be used.

  The surface of the plate-like member 13 facing the recording head 10 is coated with an ultraviolet absorber so that the ultraviolet reflectance is lower than that of the surface facing the recording head.

  In addition, as an ultraviolet absorber, if an inorganic material is carbon black, powders such as ultrafine particles of titanium oxide / zinc oxide or iron oxide, and an organic material is a member containing a benzotriazole compound or an aromatic compound, the ultraviolet absorption rate is increased. Highly preferred.

  In addition, as a method of providing the ultraviolet absorbing portion on the surface of the plate-like member facing the recording head, a method of performing various metal oxidation treatments such as a black alumite treatment, a method of plating treatment, vapor deposition or sputtering treatment, etc. There is. Furthermore, various ultraviolet absorbers can be coated.

  In addition, any one of a cold cathode sterilization lamp, a hot cathode sterilization lamp, a low pressure mercury lamp, an electrodeless lamp, an excimer lamp, a metal halide lamp, a xenon lamp, and an LED is applied as a light source for irradiating ultraviolet rays.

  One area of the movable range of the carriage 5 is a recording area for recording on the recording medium P. Below the carriage 5 in the recording area, a plate-like member is used to cover the recording medium P. A platen 8 supported from the recording surface is provided.

  In addition, a maintenance unit 7 for cleaning the nozzles of the recording head 4 is provided at the outer end of the recording area, which is a movable range of the carriage 5. Here, in the ink jet recording apparatus of the present embodiment, when the image recording is performed a predetermined number of times, the carriage 5 is moved to a predetermined position of the maintenance unit 7 to perform cleaning.

In the present embodiment, the recording head 4 is mounted on the carriage 5 and reciprocates in the main scanning direction X that is the width direction of the recording medium P. However, the present invention is not limited to this example. You may make it extend over the width direction of the medium P. FIG.
Further, in the present embodiment, the mechanism for transporting the recording medium P in the sub-scanning direction Y with respect to the recording head 4 has been exemplified, but the present invention is not limited to this, and the recording medium P and the recording head are relative to each other. It is only necessary to have a relative movement means for moving the relative movement means, and the control means controls the relative movement means.
Furthermore, in the present embodiment, an example in which the ink ejected from the recording head 4 lands directly on the recording medium P is shown, but the present invention is not limited to this, and is ejected from the recording head 4. The ink may be temporarily held by a carrier such as an intermediate transfer member and then landed by transferring the ink from the carrier to the recording medium P.

In the present embodiment, the ultraviolet irradiation device 2 is mounted on the carriage 5 and reciprocates in the main scanning direction X that is the width direction of the recording medium P. However, the present invention is not limited to this example, and the recording head is recorded. You may make it extend over the width direction of the medium P. FIG.
In the present embodiment, the mechanism for transporting the recording medium P in the sub-scanning direction Y with respect to the ultraviolet irradiation device 2 is exemplified. However, the present invention is not limited to this, and the recording medium P, the ultraviolet irradiation device 2, and the like. It is only necessary to have a relative moving means for relatively moving and to control the relative moving means by the control means.

As shown in FIG. 5, when a protective member 11 (plate member 25) is provided between the light source 10 or the ultraviolet irradiation device 2 and the recording medium P instructed by the recording medium mounting means, the light density or irradiation spectrum is obtained. Changes. More specifically, as shown in FIG. 8, a decrease in peak illuminance or the like occurs.
Therefore, the ratio between the integrated light amount when the protective member 11 is provided and the integrated light amount when the protective member 11 is not provided is:
0.7 ≦ Integrated light quantity when protective member 11 is provided / Integrated light quantity when protective member 11 is not provided <1.0
It is preferable that

Here, the integrated light quantity is obtained as follows.
[Ultraviolet irradiation equipment]
Light source High pressure mercury lamp with peak wavelength at 254 nm (catalog nominal value) Low pressure mercury lamp with peak wavelength at 254 nm (catalog nominal value) Metal halide lamp with peak wavelength at 365 nm (catalog nominal value) Peak at 365 nm (catalog nominal value) LED with wavelength

[Illuminance measurement device]
UV illuminance meter (Iwasaki Electric Co., Ltd.): UVPF-A1
Light receiver (Iwasaki Electric Co., Ltd.): PD-254 (measurement wavelength range: 240-280 nm)
PD-365 (measurement wavelength range: 300 to 390 nm)
Connect to the UV illuminance meter

〔Measuring method〕
In an inkjet printer having an ultraviolet irradiation device, when the light emission of the light source of the ultraviolet irradiation device is stabilized, for example, after 10 to 15 minutes, measurement is performed using an ultraviolet integrated illuminometer.
During normal image formation, the recording medium is placed on the recording medium placing means, and the process of ink ejection and ultraviolet irradiation is performed. Therefore, in this measurement, the light receiving surface of the light receiver is the same as the recording medium. Fix it at a flat position.
In a normal image forming mode (when there are a plurality of recording modes, such as a standard mode, a normal mode, and a default mode), the light receiver and the ultraviolet irradiation device are relatively moved, Measure the amount of emitted light as the integrated light quantity. Note that it is not necessary to eject ink when measuring the integrated light quantity.

When the inkjet printer uses a line type head as the recording head, the integrated light quantity is measured while the relative movement of an arbitrary length is performed once in the conveyance direction of the recording medium. Further, when a serial type head mounted on the carriage is used as the recording head, the integrated light quantity is measured while the recording head is moved once in the main scanning direction (X direction in this embodiment).
In any case, it is arbitrary, and it is necessary to make the relative movement at a speed slower than the sampling period of the light receiver.
The fixed position of the light receiver is arbitrary in any case.
For the relative movement between the light receiver and the ultraviolet irradiation device, refer to the description of the relative movement between the recording medium P and the ultraviolet irradiation device.
The measured integrated light quantity is represented by the product of irradiation intensity (illuminance) and irradiation time, and can be obtained, for example, in the form of 20 mJ / cm ³ .
In the above measurement, the example in which the light receiver of the illuminance measuring device is attached to the ink jet printer has been described. If this is difficult, the conditions corresponding to the measurement conditions (relative between the light receiving device in the normal recording mode and the ultraviolet irradiation device) If the speed and the distance relationship between the light source and the light receiving surface are the same), it is possible to obtain the same result by performing measurement in a state where the ultraviolet irradiation device is incorporated in another device, for example.

When a high-pressure mercury lamp having a peak wavelength at 254 nm (catalog nominal value) is used as the light source, the light source emits an ultraviolet spectrum over a wide range of 200 nm to 400 nm, so that the measurement wavelength range is 240 nm to 280 nm and Although it is possible to measure the integrated light quantity for each wavelength region using two types of 300 nm to 390 nm, the ink spectral sensitivity used in the ink jet printer falls within the measurement wavelength range. It is possible to select a light receiver or a combination in which a peak wavelength of an arbitrary light source exists in the measurement wavelength range of the light receiver.
In addition, if the light source has a single peak wavelength, it goes without saying that the measurement is performed with only one light receiver that keeps the peak wavelength within the range.
In either case, the light receiver used for illuminance measurement may be selected in such a combination that the peak wavelength of the light source exists in the measurement wavelength range.

In order to prevent the ultraviolet rays from being blocked by preventing the ink from being cured by disposing the protective member, the protective member 11 measured based on the above-described measurement method is provided. The relationship between the integrated light amount and the integrated light amount when the protective member 11 is not provided is
0.7 ≦ Integrated light quantity when protective member 11 is provided / Integrated light quantity when protective member 11 is not provided <1.0
It is preferable that

Note that the reflectance of the surface facing the head is preferably 50% or less, more preferably 20% or less, at the peak wavelength (catalog nominal value) of the light source.
The reflectance of the surface opposite to the surface facing the head is preferably 60% or more, more preferably 80% or more, so that the peak wavelength (catalog nominal value) of the light source is reflected.

[Measurement method of reflectivity]
A 60 mm integrating sphere having the wavelength of the light source of the spectrophotometer as a measurement region is attached to the light receiving part of Hitachi spectrophotometer U-3300.
First, the light intensity of a standard reflector that is a reference reflectance measurement target member is measured. The standard reflector uses a nominal reflectance 99% of Spectralon reflection standard (250-2500 nm) manufactured by Labsphere whose wavelength is the wavelength of the light source of the spectrophotometer. In addition, since the reflectance of a measurement object may change with the surface state of a standard reflecting plate, it is preferable to use a new article.
Light transmitted through the prism and controlled in wavelength is incident on the sample inside the integrating sphere. The light reflected by the standard reflecting plate is diffused inside the integrating sphere and finally reaches the light receiving unit, where it is detected as the light intensity.
Next, the standard reflector and the protection member 11 are replaced, and the same measurement is performed on the light intensity of the partition wall portion of the protection member 11.
The relative value between the light intensity obtained using the standard reflector and the light intensity obtained using the partition wall portion of the protection member 11 is defined as the reflectance of the partition wall portion measurement target surface of the protection member 11.
Reflectance = light intensity of the partition wall measurement surface of the protective member 11 / light intensity of the standard reflector × 100 [%]

Next, the operation of this embodiment will be described.
When predetermined image information is sent to the ink jet recording apparatus, the recording medium P is intermittently conveyed in the sub-scanning direction Y over the platen 8 with the recording surface supported by the platen 8.

  Each time the recording medium transport mechanism stops, the carriage 5 operates to reciprocate in the main scanning direction X directly above the recording medium P. Along with this, the recording head 4 and the ultraviolet irradiation device 2 provided on the carriage also reciprocate immediately above the recording medium so as to follow the movement of the carriage, and ink of a desired color from the nozzles of the recording head 4 with respect to the recording medium. Are discharged, and ultraviolet rays are irradiated from the ultraviolet irradiation device 2. As a result, an image is formed.

  In the present embodiment, since the protective member 11 is provided in the ultraviolet irradiation device, a jam such as a conveyance failure or clogging of the recording medium P occurs between the ultraviolet irradiation device 2 and the recording medium P. In addition, the protective member 11 can prevent the recording medium P from directly contacting or entering the ultraviolet irradiation device 2. In addition, since the protective member 11 is formed in a lattice shape, the amount of ultraviolet light emitted from the ultraviolet irradiation device 2 can be secured above a certain level, and the ink discharged onto the recording medium can be reliably cured. Is.

  Further, as shown in FIG. 4, among the plate-like members of the protective member, the surface facing the recording head is coated with an ultraviolet absorber, and the other surface is made of aluminum having a high ultraviolet reflectance. Therefore, it is possible to reduce the reflection of the ultraviolet light irradiated to the surface of the plate-like member 13 facing the recording head out of the ultraviolet light irradiated from the light source. As a result, the ultraviolet light irradiated to the ejection surface of the recording head 4 is reduced. It can be made to. On the other hand, the ultraviolet light irradiated on the other surface can be efficiently reflected on the recording medium, and even when the ultraviolet light from the light source is partially blocked by the protective member, the recording medium is efficiently irradiated with the ultraviolet light. The ink discharged onto the recording medium P can be reliably cured and fixed.

As described above, in this embodiment, when a jam occurs between the ultraviolet irradiation device and the recording medium, the protective member 11 directly contacts or enters the recording medium P to the ultraviolet irradiation device 2. Therefore, the irradiation surface portion of the ultraviolet irradiation device 2 can be reliably protected, and the ultraviolet ray sufficient for curing the ink ejected on the recording medium can be irradiated. There is an effect that a stable image formation can be performed over a long period of time.
Further, by coating the first surface of the plate-like member 25 facing the recording head with an ultraviolet absorber, the reflection of the ultraviolet rays irradiated on the surface of the protective member facing the recording head out of the ultraviolet rays irradiated from the light source. Therefore, it is possible to reduce the ultraviolet rays applied to the ejection surface of the recording head 2, prevent the ink from being cured on the ejection surface, and perform proper ejection over a long period of time. It becomes possible.

  The protective member 11 may be arranged so that the pitch between the plate-like members 25 becomes narrower as the recording head 4 is approached. By arranging the plate-like member 25 in this way, the plate-like member interferes with ultraviolet rays incident at a deep incident angle on the recording medium P, and a part of the ultraviolet rays can be blocked. It is possible to prevent the ultraviolet rays from being reflected on the recording head 4 side, and to reduce the amount of incident light on the ejection surface of the recording head 4.

  6 and 7 show another embodiment in which a low-pressure mercury lamp is used as the light source of the ultraviolet irradiation device 21, and the ultraviolet irradiation described above is performed except that the quartz glass 9 and the fan 13 are not provided. The configuration is almost the same as that of the device 2.

  Also in the present embodiment, similarly to the above-described embodiment, the surface of the housing 12 of the ultraviolet irradiation device 21 that faces the recording medium P is combined with a plurality of plate-like members 25 having a long shape in a lattice shape. A member 11 is attached.

  This protective member is also made of a material with high UV reflectivity, such as aluminum with a mirror-finished surface. However, when using a low-pressure mercury lamp as the light source, it is necessary to consider thermal measures such as a high-pressure mercury lamp. Therefore, any material may be used as long as it satisfies the conditions of ultraviolet reflectance and durability.

  Also in this embodiment, the surface of the plate-like member 25 facing the recording head 4 side is coated with an ultraviolet absorber as in the above embodiment. Thereby, the reflection of the ultraviolet ray irradiated to the first surface of the plate-like member 25 facing the recording head among the ultraviolet rays irradiated from the light source can be reduced, and as a result, the discharge surface of the recording head 4 is irradiated. UV rays can be reduced. On the other hand, the ultraviolet rays irradiated on the other surfaces can be efficiently reflected on the recording medium, and even when the ultraviolet rays from the light source are partially blocked by the protective member 11, the ultraviolet rays are efficiently irradiated onto the recording medium. Thus, the ink discharged onto the recording medium P can be reliably cured and fixed.

  Further, when a jam occurs between the ultraviolet irradiation device 21 and the recording medium P, the protective member 11 can prevent the direct contact or entry of the recording medium P into the ultraviolet irradiation device 21, and as a result. In addition, the irradiation surface portion of the ultraviolet irradiation device 21 can be reliably protected, and the ultraviolet ray sufficient for curing the ink ejected on the recording medium P can be irradiated, so that proper image formation can be performed over a long period of time. It can be carried out.

1 is a perspective view showing an embodiment of an image recording apparatus according to the present invention. It is the perspective view which showed the principal part structure of the ultraviolet irradiation device in the inkjet recording device of FIG. It is a side view which shows the principal part structure of the ultraviolet irradiation device shown in FIG. It is a perspective view which shows the principal part structure of one Example of the partition part in this embodiment and a slit. It is explanatory drawing which shows the reflective state of the ultraviolet-ray of the ultraviolet irradiation device in this embodiment. It is a perspective view which shows the principal part structure of the other Example of the ultraviolet irradiation device in the inkjet recording device of FIG. It is a side view which shows the principal part structure of the ultraviolet irradiation device shown in FIG. It is a graph which shows the measured numerical value in this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inkjet recording device 2 Ultraviolet irradiation device 3 Guide rail 4 Recording head 5 Carriage 7 Maintenance unit 8 Platen 9 Quartz glass 10 Light source 11 Protection member 12 Housing 13 Fan 14 Low-pressure mercury lamp 15 Partition 16 Slit 25 Plate-shaped member 30 Ultraviolet P Recording medium

Claims (16)

It has a recording head that ejects ink that is cured by irradiating ultraviolet rays, and an ultraviolet irradiation device that cures the ink and irradiates light, and then irradiates ultraviolet rays after ejecting ultraviolet curable ink onto a recording medium. In an image recording apparatus for recording
A protective member formed by combining a plurality of plate-like members in a lattice shape is provided on the irradiation surface of the ultraviolet irradiation device, and the ultraviolet reflectance of the first surface of the protective member facing the recording head is determined by the first surface. An image recording apparatus characterized by being lower than the ultraviolet reflectance of the second surface opposite to the surface.   The image recording apparatus according to claim 1, wherein the first surface of the protective member facing the recording head is coated with an ultraviolet absorber.   The image recording apparatus according to claim 1, wherein the protection member is made of aluminum.   4. The image recording apparatus according to claim 1, wherein the protective member is disposed such that a pitch between the plate-like members becomes narrower as the recording head is approached. 5. .   The light source stored in the ultraviolet irradiation device is any one of a cold cathode sterilization lamp, a hot cathode sterilization lamp, a low pressure mercury lamp, an electrodeless lamp, an excimer lamp, a high pressure mercury lamp, a metal halide lamp, a xenon lamp, or an LED. The image recording apparatus according to claim 1, wherein the image recording apparatus is provided.   The image recording apparatus according to claim 1, wherein the ink ejected from the recording head is a cationic curable ink.   Recording medium mounting means for supporting the recording medium, a recording head for discharging ink that is cured by irradiating light to the recording medium, and light for curing the ink on the recording medium An ultraviolet irradiation device having a light source, and a protective member having a partition wall portion and a plurality of slit portions formed by the partition wall portion between the recording medium mounting means and the ultraviolet irradiation device, An ultraviolet ray reflectivity of a first surface of the partition wall facing the recording head is lower than an ultraviolet reflectivity of a second surface opposite to the first surface. .   Recording medium mounting means for supporting the recording medium, a recording head for discharging ink that is cured by irradiating light to the recording medium, and light for curing the ink on the recording medium An ultraviolet irradiation device having a light source, and a protective member having a partition wall portion and a plurality of slit portions formed by the partition wall portion between the recording medium mounting means and the ultraviolet irradiation device, The image recording apparatus according to claim 1, wherein the first surface of the partition wall facing the recording head has an ultraviolet reflectance of 50% or less. Recording medium mounting means for supporting the recording medium, a recording head for discharging ink that is cured by irradiating light to the recording medium, and light for curing the ink on the recording medium An ultraviolet irradiation device having a light source, and a protective member having a partition wall portion and a plurality of slit portions formed by the partition wall portion between the recording medium mounting means and the ultraviolet irradiation device,
2. An image recording apparatus according to claim 1, wherein the ultraviolet reflectance of the second surface opposite to the first surface facing the recording head of the partition wall is 60% or more.   The image recording apparatus according to claim 7, wherein the protection member is configured in a lattice shape.   The image recording apparatus according to claim 7, further comprising a moving unit that relatively moves the recording medium and the ultraviolet irradiation apparatus.   Regarding the distance between the recording medium placing means and the protection member, the first distance between one end of the protection member and the recording medium placing means in the relative movement direction of the ultraviolet irradiation device is other than the one end. The image recording apparatus according to claim 11, wherein the image recording apparatus is larger than a second distance between the portion and the recording medium placing means.   The image recording apparatus according to claim 7, wherein the protection member is attached to the ultraviolet irradiation apparatus.   The image recording apparatus according to claim 13, wherein the protection member is detachable from the ultraviolet irradiation apparatus.   In the image recording apparatus, the integrated illuminance measured through the protective member on the recording medium placing means is the integrated illuminance A, and the protective member is not provided on the recording medium placing means. The image recording apparatus according to claim 7, wherein 0.7 ≦ A / B <1.0, where the measured integrated illuminance is defined as integrated illuminance B.   The image recording apparatus according to claim 7, wherein the ultraviolet irradiation device includes a housing and quartz glass.

Images