Ink jet printer

The present invention relates to an inkjet printer, and more particularly to an inkjet printer that records an image using an ultraviolet curable ink.

Generally, an inkjet printer is known as a means capable of printing on various recording media. An inkjet printer records an image on a recording medium by ejecting ink from an ejection port provided on a surface of the recording head facing the recording medium, landing on the recording medium, and fixing the ink, which requires a plate making process. There is an advantage that it is possible to print according to the demand because it does not. In particular, in recent years, an inkjet printer using a photocurable ink that is cured by light such as ultraviolet rays has been known, and according to this, the ink is cured by irradiating the ink that has landed on the recording medium with light. Since it can be fixed on a recording medium, it is possible to easily print on a recording medium that does not absorb ink, such as a transparent or translucent resin film.

Such an inkjet printer is generally provided with an ink tank that stores ink before it is sent to a recording head that ejects ink, but the amount of ink stored in the ink tank is image recording. It decreases as the operation is repeated. Therefore, in order to smoothly perform the image recording operation, it is necessary to grasp whether or not the ink in the ink tank is exhausted and to replenish the ink as appropriate when the ink is exhausted. Therefore, the ink tank is formed of a transparent or translucent material so that the content of the ink tank can be determined, and the amount of ink in the ink tank can be detected visually or by a detection means such as a sensor. Is possible. By making the ink tank transparent or translucent in this way, the type of ink in the ink tank can also be visually confirmed.

However, when ultraviolet curable ink that cures in response to ultraviolet rays or the like is used for image recording, if the ink tank is made transparent or translucent, ultraviolet rays from the outside pass through the ink tank and are stored inside. Can be cured or the quality of the ink can be degraded. Therefore, the ink tank is formed of polypropylene or the like to which an ultraviolet absorber such as salicylic acid or cyanoacrylate is added so that visible light can be transmitted and the amount of ultraviolet rays transmitted can be reduced. It is possible to detect the remaining amount of ink and the type of ink while preventing the ultraviolet rays from being irradiated (see, for example, Patent Document 1).<patcit num="1"><text>Japanese Unexamined Patent Publication No. 2001-63099</text></patcit>

<p> However, if an ultraviolet absorber is added to the material forming the ink tank to allow visible light to pass through the ink tank while the ultraviolet light can be dimmed, the production process of the ink tank becomes complicated and the production cost becomes high. There is a problem that it becomes high.</p><p> Further, in this case, since the inside of the ink tank can be visually confirmed, it is difficult to completely block light. Therefore, if the ink tank is left in a state of being exposed to external light for a long period of time, there is a problem that the ink inside the ink tank is cured and the quality is deteriorated.</p><p> Therefore, the present invention has been made to solve the above problems, and provides an inkjet printer capable of detecting the remaining amount of ink and the type of ink without affecting the ink inside the ink tank. The purpose is to do.</p>

<p> In order to solve such a problem, the inkjet printer according to claim 1 has an ink tank for storing an ultraviolet curable ink that is cured by ultraviolet rays, a recording head that ejects the ultraviolet curable ink, and the ink. An inkjet printer including an ink supply tube for supplying the ultraviolet curable ink from a tank to the recording head. The ink tank and the ink supply tube are formed of a material that does not transmit light, and the ink is supplied. It is characterized in that a transparent or translucent internal observation window formed of a material that does not easily transmit ultraviolet rays is provided in the middle of the tube and in the vicinity of the ink tank.</p><p> In the invention according to claim 1, which has such a configuration, the ink tank and the ink supply tube are formed of a material that does not transmit light so that the ink is not irradiated with light such as ultraviolet rays before image recording. The liquid level of the ink in the ink supply tube can be checked from the internal observation window provided in the ink supply tube.</p><p> The invention according to claim 2 is the inkjet printer according to claim 1, wherein the internal observation window is composed of an inner layer in contact with the ultraviolet curable ink and an outer layer formed of a material that does not easily transmit ultraviolet rays. The material forming the inner layer has a multi-layer structure, and is characterized by having corrosion resistance to the ultraviolet curable ink.</p><p> In the invention according to claim 2, which has such a configuration, since the inner layer of the internal observation window is formed of a material having corrosion resistance to the ultraviolet curable ink, the ultraviolet curable ink is used for the internal observation window. It is designed so that it does not come into direct contact with the outer layer.</p>

<p> According to the invention described in claim 1, an internal observation window is formed in the middle of the ink supply tube with a material that does not easily transmit ultraviolet rays, and the liquid level of the ink in the ink supply tube, the color of the ink, etc. Since it can be confirmed, when the ink in the ink tank is exhausted and the ink liquid level drops to the position where the internal observation window of the ink supply pipe is provided, it can be easily detected by visual inspection or the like. The type of ink can also be easily confirmed.</p><p> Further, since the remaining amount of ink can be confirmed from the internal observation window provided in the ink supply tube in this way, the ink tank and the ink supply tube can be formed of a material that does not transmit light such as ultraviolet rays and visible light at all. .. As a result, the production cost of the ink tank can be reduced as compared with the case where the ink tank is formed of a material to which an ultraviolet absorber is added, and the ink before image recording is irradiated with light such as ultraviolet rays. This can be reliably prevented, and the effect is that the ultraviolet curable ink does not cure inside the ink tank and the quality of the ink does not deteriorate.</p><p> According to the invention described in claim 2, the internal observation window is composed of an outer layer made of a material such as acrylic that does not easily transmit ultraviolet rays and an inner layer formed of a material having corrosion resistance to ultraviolet curable ink. Because of the multi-layer structure, the UV curable ink does not come into direct contact with the outer layer of the internal observation window, and even when a material that is easily corroded by the UV curable ink such as acrylic is used as the material that constitutes the internal observation window. The effect is that the internal observation window is not corroded by the ultraviolet curable ink and the liquid level of the ink can be easily confirmed through the internal observation window.</p>

Hereinafter, an embodiment of the inkjet printer according to the present invention will be described with reference to FIGS. 1 and 2.

First, as shown in FIG. 1, in the present embodiment, the inkjet printer is an inkjet printer by a serial printing method, and the inkjet printer has a platen 1 formed in a flat plate shape and supporting the recording medium P from a non-recording surface. It is provided. Transfer rollers 2 and 3 for transporting the recording medium P while maintaining the height of the platen 1 at approximately the same height as the platen 1 are rotatably provided on the upstream side and the downstream side of the platen 1, respectively, and the recording medium P is driven (not shown). By rotating the transport rollers 2 and 3 by the mechanism, the transport rollers 2 and 3 are transported along the upper surface of the platen 1 in a predetermined transport direction X.

Above the platen 1, a rod-shaped guide rail 4 extending in the main scanning direction orthogonal to the transport direction X of the recording medium P is provided. A carriage 5 is supported on the guide rail 4, and the carriage 5 reciprocates along the guide rail 4 in the main scanning direction by a drive mechanism (not shown).

The carriage 5 is equipped with four recording heads 6 corresponding to each color (yellow (Y), magenta (M), cyan (C), black (K)) used in the inkjet printer according to the present embodiment. .. A plurality of ink ejection ports (not shown) are provided on the surface of the recording head 6 facing the recording medium P, and each recording head 6 ejects ink from the ink ejection port. The ink used in the inkjet printer is not limited to this, and for example, colors such as light yellow (LY), light magenta (LM), and light cyan (LC) can be used. In this case, a recording head corresponding to each color is mounted on the carriage.

Here, the ink used in the present embodiment is an ultraviolet curable ink that is cured by irradiating with ultraviolet rays. UV-curable inks are roughly classified into radical polymerization type inks containing radical polymerization compounds and cationic polymerization type inks containing cationically polymerizable compounds as polymerizable monomers and photopolymerization initiators. It can be applied as the ink used in this embodiment. Further, a hybrid ink obtained by combining a radical polymerization ink and a cationic polymerization ink may be applied as the ink used in the present embodiment.

An ultraviolet irradiation device (not shown) that irradiates ultraviolet rays is provided on the carriage 5 so as to irradiate the ink that has landed on the recording medium P with ultraviolet rays. The ink is cured by being irradiated with ultraviolet rays from the ultraviolet irradiation device, and is fixed on the recording medium P. As an ultraviolet light source (not shown) provided in the ultraviolet irradiation device, for example, a high-pressure mercury lamp, a low-pressure mercury lamp, a metal halide lamp, a semiconductor laser, a cold cathode tube, an excimer lamp, an LED (Light Emitting Diode), or the like is applied. It is possible.

Further, in each recording head 6, an intermediate tank 7 for temporarily storing inks of each color of yellow (Y), magenta (M), cyan (C), and black (K) is provided via an ink supply pipe 8a. Are connected. Further, each intermediate tank 7 is connected to a main tank 9 which is an ink tank for storing ink of each color via an ink supply pipe 8b.

The ink supply tubes 8a and 8b are made of a flexible material such as resin, and are deformable according to the movement of the carriage. The ink supply tubes 8a and 8b are made of a dark material such as black so that the ink does not easily transmit ultraviolet rays from the outside. Further, the ultraviolet curable ink used in the present embodiment contains a monomer, and some of the monomers have a property of dissolving a resin such as acrylic. Therefore, as the material for forming the ink supply tubes 8a and 8b, for example, a material having corrosion resistance to ultraviolet curable ink such as polypropylene (PP) and polyethylene (PE) is preferably used.

Further, at one end of the ink supply pipe 8b, a supply pipe side connection portion 10 connected to the main tank 9 is provided.

An internal observation window 11 for checking the ink existing in the ink supply pipe 8b is provided in the middle of the ink supply pipe 8b and in the vicinity of the connection portion 10 on the supply pipe side. As shown in FIG. 2, the internal observation window 11 is a short tube having a multi-layer structure composed of an outer layer 12 and an inner layer 13, and by inserting both ends of the tube into the ink supply tube 8b, the inside of the ink supply tube 8b is formed. It is joined. The internal observation window 11 may be joined to the ink supply tube 8b so as not to cause ink leakage, and the joining method is not limited to the one illustrated here.

The outer layer 12 of the internal observation window is formed of, for example, an acrylic resin or the like so that visible light is transmitted and ultraviolet rays are hardly transmitted. On the other hand, the inner layer 13 is formed of a material having corrosion resistance to ultraviolet curable ink such as polypropylene (PP) and polyethylene (PE). The material constituting the inner layer 13 is lighter in color and thinner than the material constituting the ink supply tube 8b so as not to obstruct the transmission of visible light, and the thickness is, for example, t = 0.2 to 0.5. Be done. As long as it transmits visible light, it may be light in color or thickness. Acrylic resin and the like are difficult to transmit ultraviolet rays, but have the property of being easily corroded by the monomers contained in the ultraviolet curable ink. In this way, the outer layer 12 formed of acrylic resin and the like is resistant to the ultraviolet curable ink. By forming a multi-layer structure in which inner layers 13 made of a corrosive material are stacked, it is possible to check the ink inside the ink supply pipe 8b from the outside while preventing corrosion.

Next, the main tank 9 has an ink storage unit 14 capable of storing a large amount of ink, and a storage side connection unit 15 that connects the ink storage unit 14 and the ink supply pipe 8b. By connecting the supply pipe side connection portion 10 of the ink supply pipe 8b and the storage portion side connection portion 15 of the ink storage portion 14, the main tank 9 and the ink supply pipe 8b are connected, and each main tank 9 is connected. The ink stored in the ink storage unit 14 is supplied to the intermediate tank 7 via the ink supply pipe 8b, once stored in the intermediate tank 7, and then supplied to each recording head 6. .. The ink storage unit 14 is made of a flexible material such as resin, and its capacity is reduced as the ink inside is consumed. Further, the ink storage unit 14 is formed of a dark resin or the like that does not transmit ultraviolet rays at all, so that the ink stored inside is not irradiated with ultraviolet rays from the outside. The ink inside the main tank 9 may be prevented from being irradiated with the ultraviolet rays or the like by covering the main tank 9 with a cover that blocks ultraviolet rays or the like.

Further, a weight sensor (not shown) as an ink amount detecting means is provided in contact with the bottom of the main tank 9. The weight sensor can detect the amount of ink stored in the ink storage unit 14 of the main tank 9 by detecting the change in the weight of the main tank 9.

Next, the operation of this embodiment will be described.

When the power of the inkjet printer is turned on, power is supplied to each part of the inkjet printer, and the carriage 5 on which the recording head 6 is mounted moves above the platen 1.

When the carriage 5 reaches a predetermined position, the recording medium P is transported in the transport direction X by the transport rollers 2 and 3, and at the same time, the carriage 5 reciprocates along the main scanning direction. At this time, ink of a required color is ejected from the ink ejection port of the recording head 6 based on predetermined image information. At the same time, the ultraviolet light source of the ultraviolet irradiation device is turned on, and the ink ejected on the recording medium P is irradiated with ultraviolet rays, whereby the ink is cured and fixed and an image is recorded on the recording surface of the recording medium P. Will be done.

During the image recording operation, ink is supplied to the recording head 6 from each intermediate tank 7 at any time, and when the amount of ink stored in each intermediate tank 7 decreases, each main tank 9 corresponding to each at any time Ink is supplied from.

The weight change of the main tank 9 is detected by the weight sensor at any time, and the amount of ink stored in the ink storage unit 14 is grasped by this. Further, when the ink remaining amount in the ink storage unit 14 is exhausted and the ink liquid level is lowered to the position of the internal observation window 11 provided in the ink supply tube 8b, the user has no ink remaining amount in the main tank 9. This can be visually confirmed, and ink is replenished as necessary. At that time, by checking the color of the ink from the internal observation window 11, the user determines the ink that needs to be replenished, selects an appropriate ink, and replenishes the ink.

From the above, according to the present embodiment, the remaining amount of ink and the type of ink can be confirmed from the internal observation window 11 provided in the middle of the ink supply pipe 8b, so that the main tank 9 and the ink supply pipes 8a and 8b can be confirmed. The ink itself can be formed so as not to transmit ultraviolet rays, and the ink in the main tank 9 or the ink supply tubes 8a and 8b is not cured or deteriorated in quality by being irradiated with ultraviolet rays.

In addition, since the position and color of the ink liquid level can be easily and accurately confirmed from the internal observation window 11, the ink replenishment time can be appropriately grasped, and the user mistakenly checks the ink of a different color. It is possible to prevent mistakes such as replenishing ink.

In the present embodiment, the internal observation window 11 is configured by joining a transparent or translucent tube in the middle of the ink supply tube 8b so that the inside of the ink supply tube 8b can be visually recognized from this tube portion. The configuration of the internal observation window 11 is not limited to this. For example, a notch having a size that allows the inside of the ink supply tube 8b to be visually recognized is formed in a part of the ink supply tube 8b, and a member formed of acrylic resin or the like is fitted in the notch to observe the inside. The window 11 may be configured.

Further, in the present embodiment, the internal observation window 11 is provided in the middle of the ink supply pipe 8b and in the vicinity of the supply pipe side connection portion 10, but the position where the internal observation window 11 is provided is not limited to this. It suffices if it is provided in the vicinity of the main tank 9 so that it can be detected at an early stage that the remaining amount of ink in the main tank 9 has been exhausted. However, it may be formed of a material that does not transmit ultraviolet rays so that the inside can be observed from here.

Further, in the present embodiment, the internal observation window 11 has a multi-layer structure including an outer layer 12 formed of acrylic resin or the like and an inner layer 13 formed of polypropylene or the like. Not limited to this, when image recording is performed using an ink that does not have the property of corroding the resin, the internal observation window 11 may be composed only of an acrylic resin or the like that does not transmit ultraviolet rays. Further, as a material for forming the internal observation window 11, glass coated to prevent the transmission of ultraviolet rays, or a resin having corrosion resistance to ultraviolet curable inks such as polypropylene and polyethylene is coated to prevent the transmission of ultraviolet rays. You may use the one which has been given.

Further, in the present embodiment, the liquid level of the ink can be visually confirmed from the internal observation window 11, but for example, a light emitter having built-in light emitting elements that emit light such as infrared rays on both sides of the internal observation window 11. An optical sensor including a light receiver having a built-in light receiving element that senses the light emitted from the light emitter may be provided to check the liquid level of the ink. That is, when the liquid level of the ink is above the sensor installation position, the light emitted from the light emitter is blocked by the ink and is not received by the light receiver, but when the liquid level is lower than the sensor installation position, the light is emitted from the light emitter. The irradiated light is received by the light receiver. Thereby, the liquid level of the ink may be detected. The sensor provided in the internal observation window is sufficient as long as it can detect the liquid level of the ink, and is not limited to the optical sensor illustrated here.

Further, in the present embodiment, the weight sensor for detecting the amount of ink in the main tank 9 is provided so as to be in contact with the bottom surface of the main tank 9, but the position where the sensor is provided is not limited to this. Further, without providing the weight sensor, it may be determined whether or not the remaining amount of ink is sufficient by detecting the ink liquid level from the internal observation window 11.

In the present embodiment, the intermediate tank 7 is provided between the main tank 9 and the recording head 6, but instead of providing the intermediate tank 7, for example, a mechanism such as a damper is provided and the ink flows into the recording head 6. The amount of ink and the negative pressure applied to the ink may be adjusted.

Further, in the present embodiment, image recording is performed using an ink that is cured by irradiating with ultraviolet rays, but the ink is not necessarily limited to this, and for example, ultraviolet rays, electron beams, X-rays, visible rays, and the like. The ink may be cured by irradiating light other than ultraviolet rays such as electromagnetic waves such as infrared rays. In this case, a polymerizable compound that polymerizes and cures with light other than ultraviolet rays and a photoinitiator that initiates a polymerization reaction between the polymerizable compounds with light other than ultraviolet rays are applied to the ink. When a photocurable ink that is cured by light other than ultraviolet rays is used, a light source that irradiates the light is applied instead of the ultraviolet light source. According to this embodiment, a light-shielding material that does not transmit light through the main tank 9 for storing ink and the parts other than the internal observation windows 11 of the ink supply tubes 8a and 8b that guide the ink from the main tank 9 to the recording head 6. Therefore, even if an ink that is cured by various kinds of light other than ultraviolet rays or whose quality is deteriorated by being irradiated with light is used, it may affect the ink before image recording. Absent. When a photocurable ink that is cured by a specific light other than ultraviolet rays is used, the internal observation window 11 is formed of a material that does not easily transmit the specific light.

Further, in the present embodiment, the inkjet printer reciprocates the recording head 6 mounted on the carriage 5 in the main scanning direction, and ejects ink from the recording head 6 while transporting the recording medium P in the transport direction X. Although the serial head type inkjet printer that forms an image is used, the line head type inkjet printer that forms an image by ejecting ink from a recording head fixed to the printer body and transporting a recording medium may also be used. ..

The recording medium P used in the present embodiment is made of various papers such as plain paper, recycled paper, and glossy paper, various fabrics, various non-woven fabrics, resins, metals, and glass, which are applied to ordinary inkjet printers. Recording media are applicable. Further, as the form of the recording medium P, a roll shape, a cut sheet shape, a plate shape, or the like can be applied.

In addition, it goes without saying that the present invention is not limited to the above-described embodiment and can be appropriately modified.

<figref num="1">It is a side view which showed the main part structure of one Embodiment of the inkjet printer in this Embodiment.</figref><figref num="2">It is sectional drawing which showed one Embodiment of the internal observation window in this embodiment.</figref>

Code description

6 Recording head 8a, 8b Ink supply pipe 9 Main tank 11 Internal observation window 12 Outer layer 13 Inner layer 14 Ink storage