JP2003136688A - Ink jet printer and recording method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet printer in which high quality printing can be kept. SOLUTION: The ink jet printer A comprises rollers 1 and 2 for carrying a sheet-like recording medium R, a recording head 41 for printing on the print face of the recording medium R being carried by the carrying rollers 1 and 2 by ejecting UV ink curable upon irradiation with UV-rays, and cleaning brushes 31 and 32 for cleaning the print face of the recording medium R before UV-ink is ejected from the head 41. Substances causing lowering of print quality, e.g. fine dust, are removed by means of the cleaning brushes 31 and 32 and high quality printing can be sustained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inkjet printer and a method for recording on a recording medium using the inkjet printer.

[0002]

2. Description of the Related Art Today, it is common practice to form an image on a monitor by a computer or the like and print the formed image on a sheet-shaped recording medium by an ink jet printer. As a method of printing on a recording medium using an inkjet printer, there is a method of using a UV ink that cures when irradiated with ultraviolet rays (hereinafter referred to as UV). In this method, UV ink is attached to a recording medium,
After that, the recording medium to which the UV ink is attached is irradiated with UV to cure the UV ink and perform printing.

[0003]

By the way, the printing surface of the recording medium before the UV ink is attached is not particularly in a cleaned state. Therefore, such a printed surface may have minute dust on it, and when a water-repellent medium such as a film is used as the recording medium, a liquid such as water droplets due to dew condensation is used. The material may remain on the printing surface in a repelled state on the printing surface. When printing is performed in such a state, the adhesion or bleeding property of the UV ink on the recording medium is changed, or the UV ink is changed, as compared with the state where high-quality printing is performed as usual. There is a possibility that discoloration may occur, which may lead to deterioration of print quality.

Therefore, the present invention provides an ink jet printer capable of holding high quality printing and a recording method on a recording medium using the ink jet printer.

[0005]

According to a first aspect of the present invention, there is provided an ink jet printer in which ultraviolet rays are radiated onto a conveying means for conveying a sheet-shaped recording medium and a printing surface of the recording medium conveyed by the conveying means. It is characterized in that it is provided with a head for ejecting and curing the UV ink which is cured, and a cleaning means for cleaning the printing surface of the recording medium before the UV ink is ejected by the head.

The "recording medium" may be roll-shaped, cut-sheet-shaped, or other forms of paper, and the type of paper may be acidic paper, neutral paper, or any other type. Good. The “recording medium” may be made of a material other than paper, and may be, for example, a resin film.
The "recording medium" is not limited to the sheet shape, and may be a plate shape. What is "UV ink"?
Basically, UV energy causes a photochemical reaction,
The ink that cures from a liquid to a solid, and as another property, the "UV ink" has a property that it has high viscosity at room temperature and changes to low viscosity by heating. Specifically, the viscosity of UV ink is 5 at 30 ° C.
A liquid of 0 to 3000 mPa · s is preferable.
It is more preferably 50 to 1000 mPa · s, and even more preferably 100 to 500 mPa · s. Fifty
At mPa · s or less, clear printing cannot be performed because bleeding easily occurs. At 3000 mPa · s or higher, the smoothness of the image quality is lost. Furthermore, the viscosity at 60 ° C is 3 to 30 mP.
It is preferably an a · s liquid. If it is less than 3 mPa · s, a problem may occur in high-speed ejection.
If it exceeds 0 mPa · s, the ejection property may deteriorate. Further, particularly when ejected from a head composed of a piezo element, a liquid having a viscosity of 3 to 30 mPa · s is preferable.

According to the first aspect of the present invention, since the cleaning means is provided, the printing surface of the recording medium conveyed to the position where the UV ink is ejected by the head has already been cleaned by the cleaning means. Has become. On the printing surface in this state, minute dusts and the like are removed, and when a water-repellent medium such as a film is used as the recording medium, a liquid substance that causes a deterioration in print quality ( For example, water drops caused by dew condensation are also removed. Therefore, when printing is performed on the printing surface of the recording medium in such a state, the adhesion or bleeding property of the UV ink to the recording medium is higher than that in the state where high quality printing is performed as usual. And the like, and the discoloration of the UV ink does not occur. As a result, high quality printing can be retained.

According to a second aspect of the present invention, the conveying means for conveying the sheet-shaped recording medium and the printing surface of the recording medium conveyed by the conveying means are cured when ultraviolet rays are irradiated U
A method for recording on a recording medium using an inkjet printer including a head for ejecting V ink and performing printing, comprising a cleaning step for cleaning a print surface of the recording medium before the UV ink is ejected by the head. It is characterized by

According to the recording method of the second aspect, the same effect as that of the first aspect can be obtained.

According to a third aspect of the present invention, in the ink jet printer according to the first aspect, the ink adheres to the printing surface of the recording medium before the UV ink is ejected by the head and the droplets of the UV ink are ejected. A detection unit for detecting a foreign substance having a diameter larger than a diameter, and when the detection unit detects the foreign substance, the cleaning unit cleans the print surface of the recording medium before the head ejects the UV ink. Is characterized by.

According to the third aspect of the present invention, when the UV ink is ejected while the foreign matter remains on the recording medium, the UV ink droplets ejected on the surface of the foreign matter have a high viscosity on the surface of the foreign matter. However, when the foreign matter is peeled off from the surface of the recording medium after the printing is completed, at the same time, the high viscosity droplets on the surface of the foreign matter are also peeled off from the surface of the recording medium. Even if the UV ink droplets are not peeled off, the droplets ejected on the surface of the foreign matter flow to the rear surface side of the foreign matter while maintaining a low viscosity and adhere to the recording medium to be fixed. The fixability is rather weak, and the droplets thereof are easily separated from the recording medium. Therefore, as in the above configuration, the invention according to claim 3 is provided with the detection means, so that the foreign matter can be reliably detected, and the detected foreign matter can be removed by the cleaning means. As a result, it is possible to prevent the separation of the UV ink droplets from the recording medium, the deterioration of the fixing ability of the UV ink droplets, and the like, and to maintain high-quality printing.

According to a fourth aspect of the present invention, in the ink jet printer according to the first and third aspects, a UV lamp for irradiating the print surface of the recording medium with UV in order to cure the UV ink adhered to the print surface of the recording medium. The cleaning means removes a substance that inhibits the curing of the UV ink by the UV lamp.

In the "curing of UV ink", a photopolymerization initiator, which is one of the UV ink compositions, absorbs UV to generate radicals (active species), which is one of the UV ink compositions. Polymerization is initiated by reacting with the reactive groups of the monomer and the oligomer, which are two, and thus, the “substance that inhibits the curing of the UV ink by the UV lamp” means that UV that is absorbed by the UV ink is absorbed. Substances that consume radicals to initiate polymerization, such as U
It means a substance that reduces the curability of the V ink.

According to the fourth aspect of the present invention, the printed recording medium is conveyed to a position opposite to the UV lamp and is irradiated with UV by the UV lamp, and the UV ink adhered to the recording medium. Will be cured.
Further, the substance that inhibits the curing of the UV ink before the UV irradiation by the UV lamp is removed by the cleaning means. Therefore, if UV is applied to the recording medium to which the UV ink is attached in this state, the substance does not hinder the curing of the UV ink. As a result, as compared with the case where high-quality printing is performed as usual, the adhesiveness or bleeding property of the UV ink on the recording medium does not change, and the discoloration of the UV ink does not occur. Able to maintain quality print.

According to a fifth aspect of the present invention, the ink jet printer according to any one of the first to third aspects is provided with a second cleaning means for cleaning the cleaning means. .

According to the fifth aspect of the present invention, the cleaning means for cleaning the printing surface of the recording medium is further cleaned by the second cleaning means. For example, the cleaning means is used when printing is performed for a long time. If the cleaning means is dirty, printing is not performed with the cleaning means being in the dirty status. That is, the cleaning unit that has become dirty is brought into a state where it has been cleaned by the second cleaning unit, and printing is performed. Therefore, for example, even if printing is performed for a long time, the printing surface of the recording medium during this period is more reliably and stably cleaned, and thus more reliably and stably. And can maintain high quality printing.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of an ink jet printer of the present invention will be described below with reference to the drawings. In the present embodiment, an example in which the inkjet printer of the present invention is applied to an ultraviolet ray (hereinafter referred to as UV) inkjet printer will be described, but the present invention can be applied to various inkjet printers.

FIG. 1 is a sectional view of an essential part of an ink jet printer for easily understanding the printing process on a recording medium which is a sheet of paper. As shown in the figure, the inkjet printer A schematically includes conveyance rollers 1 and 2 that play a role of conveying a recording medium R such as a sheet of paper.
A cleaning unit 3 that cleans the recording medium R transported by the transport rollers 1 and 2, a printing unit 4 that prints on the recording medium R, and a UV irradiation is applied to the recording medium R to which the ink is attached in the printing unit 4. The UV irradiation unit 5 is provided. Then, a transport path in which the recording medium R is transported by the transport roller 1, passes through the cleaning unit 3, the printing unit 4, and the UV irradiation unit 5 and is further transported by the transport roller 2,
It is established along the transport direction D. In addition, in the present embodiment, an example in which a roll paper wound in a roll shape is applied as a paper supply source is shown, and this roll paper is referred to as a “recording medium R”. The recording medium R is set on the spindle 6.

As shown in FIG. 1, the conveying rollers 1 and 2 are
The printing unit 4 is arranged separately from each other at positions before and after printing is performed on the recording medium R by the printing unit 4. The transport rollers 1 and 2 are rotationally driven in the same direction as each other to transport the recording medium R in the transport direction D.
It has a function as a transporting means for sending to.

The cleaning section 3 is provided with cleaning brushes (hereinafter referred to as brushes) 31, 32. The two brushes 31 and 32 are provided on the printing surface side and the non-printing surface side of the recording medium R, respectively.
The leading end of 2 is in contact with both the printed surface and the non-printed surface of the recording medium R. The brushes 31 and 32 have a function as a cleaning unit that cleans both the printing surface and the non-printing surface of the recording medium R before the ink is ejected in the printing unit 4, and thus the print quality is not deteriorated. This is to remove the causative substance (for example, minute dust: hereinafter referred to as "quality lowering substance"). The “non-printing surface” is the surface opposite to the printing surface of the recording medium, that is, the surface on which printing is not performed.

The printing unit 4 includes an ink jet type recording head 41 and a carriage 4 including the recording head 41.
2 and a carriage rail 43 for guiding the movement of the carriage 42.

Ink such as cyan (C), magenta (M), yellow (Y), and black (B) is supplied to the recording head 41 by a tube or an ink cartridge (not shown). This ink has a high viscosity at room temperature, a low viscosity when heated, and a property of being cured when irradiated with UV. Below, this ink is called "UV
"Ink".

The carriage 42 has a recording head 41,
It is connected to the carriage rail 43 via the connecting portion 42a. The carriage rail 43 is a rail that extends substantially orthogonal to the transport direction D of the recording medium R, and is in the transport direction D.
The carriage 42 is guided in a direction substantially orthogonal to (a direction from the front side to the back side or the direction from the back side to the front side in FIG. 1). The direction in which the carriage rail 43 extends will be referred to as the "scanning direction", and the following description will be given. When printing is performed on the recording medium R, UV ink is ejected from the recording head 41 to the recording medium R while the carriage 42 is guided by the carriage rail 43 and moves in the scanning direction.

The UV irradiator 5 is equipped with a UV lamp 51. The UV lamp 51 irradiates the print surface of the recording medium R with UV in order to cure the UV ink attached to the print surface of the recording medium R.

Next, the operation of the ink jet printer A according to the present invention from the feeding of the recording medium R to the ejection of the recording medium R will be described. The paper source of the recording medium R is set on the spindle 12, and the leading end of the recording medium R is guided to the conveying roller 1 along a paper feed guide (not shown),
Align the tip. Aligned recording medium R
Are conveyed to the cleaning unit 3.

In the cleaning unit 3, the recording medium R is conveyed in the conveying direction D with the tips of the brushes 31 and 32 in contact with the printing surface and the non-printing surface of the recording medium R. In this case, since the tip of the brush 32 is in contact with the print surface of the recording medium R, the quality lowering substance (for example, minute dust or the like) is removed by the brush 32. That is, the recording head 41 of the printing unit 4 causes U
The printing surface of the recording medium R before the V ink is ejected is in a cleaned state. When a water-repellent medium such as a film is used as the recording medium R, similarly,
The quality-reducing substances (for example, water drops caused by dew condensation) will also be removed. Then, the recording medium R that has been cleaned by the cleaning unit 3 is further transported to the printing unit 4 in the transport direction D.

In the printing section 4, the recording head 21 prints. Specifically, the recording medium R has a non-printing surface supported by a platen (not shown), and the carriage 4
Printing is performed by ejecting UV ink onto the printing surface of the recording medium R while the recording head 41 moves in the scanning direction in association with the operation of 2. Recording medium R after printing is performed
Are transported to the UV irradiation unit 5.

In the UV irradiation section 5, the UV lamp 51 irradiates the recording medium R to which the UV ink is attached with UV, and the UV ink attached to the recording medium R is cured. Then, the recording medium R that has gone through the steps of the cleaning unit 3, the printing unit 4, and the UV irradiation unit 5 is discharged through a paper discharge guide (not shown).

As described above, according to the ink jet printer A of this embodiment, the printing surface of the recording medium R conveyed to the position where the UV ink is ejected by the recording head 41 is
It has already been cleaned by the brush 32. On the printing surface in this state, the quality-reducing substance (for example, fine dust) is cleaned by the brush 3 as a cleaning unit.
1, 32 have been removed. Therefore, when printing is performed on the printing surface of the recording medium R in such a state,
Compared to the state in which high-quality printing is performed as usual, the adhesion or bleeding property of the UV ink on the recording medium R does not change, and the UV ink does not discolor. As a result, the inkjet printer A having the above configuration
According to this, high-quality printing can be retained. In the above example shown in FIG. 1, the "quality-reducing substance" is UV.
A substance that inhibits the curing of the ink (hereinafter referred to as “UV curing inhibitor”) is also included, and the UV curing inhibitor can be removed by the brushes 31 and 32 as the cleaning means. In this case, even if the recording medium to which the UV ink is attached is irradiated with UV, the UV curing inhibitor does not inhibit the curing of the UV ink.

Here, modified examples in which the brushes 31 and 32 as the above-mentioned cleaning means are substituted are shown in FIGS.
Will be described with reference to. 2 and 3, the components other than the cleaning means are the same as those in the above example, and therefore, the same reference numerals as those in FIG. 1 are given to these components, and detailed description thereof will be omitted. .

As shown in FIG. 2, the carriage 42 of the printing unit 4 is provided with a small camera 7 and a cleaning brush (hereinafter referred to as a brush) 33.

The small camera 7 is provided on the carriage 42 together with the brush 33, but is arranged upstream of the brush 33 in the carrying direction D (close to the carrying roller 1).
At the same time, it is arranged upstream of the recording head 41 in the transport direction D. The small camera 7 captures an image of the printing surface of the recording medium R, and is mounted on the carriage 42, so that the small camera 7 can move in the scanning direction simultaneously with the movement of the carriage 42 in the scanning direction. In this case, the printing surface of the recording medium R is scanned so that the printing surface can be imaged at high speed.
In addition, the small camera 7 is provided with a recording head 41 for U
It has a function as a detection unit that detects foreign matter adhering to the printing surface of the recording medium R before the V ink is ejected. The "foreign matter" is a substance larger than the diameter of the droplets of the UV ink ejected by the recording head 41 (that is, the smallest nozzle diameter of the recording head 41), and has been described in the above example shown in FIG. It includes the meaning of quality-reducing substances and UV curing inhibitors. The small camera 7 as a detection means is connected to a control unit (not shown) inside the inkjet printer A, and the control unit is preliminarily subjected to UV.
The diameter of the ink droplet is stored. Then, the control unit performs control so as to detect a foreign substance larger than the diameter of the droplet of the UV ink while the small camera 7 is imaging the print surface of the recording medium R.

Although the brush 33 is provided on the carriage 42 together with the small camera 7, it is arranged on the downstream side of the small camera 7 in the conveying direction D (the side close to the conveying roller 2), and at the same time, the brush 33 is conveyed in the conveying direction. It is arranged on the upstream side of D. The brush 33 is movable so as to move up and down in a direction (hereinafter referred to as an ascending / descending direction; see FIG. 2) that is substantially orthogonal to the printing surface of the recording medium R. More specifically, the tip of the brush 33 is in contact with the printing surface of the recording medium R when the brush 33 is in the lowered state, and the tip is away from the printing surface when the brush 33 is in the raised state. In addition, the brush 33 is connected to the above-mentioned control unit, and by this control unit, the normally raised state is maintained, and the brush 33 is lowered when the foreign object is detected by the small camera 7. Is controlled to be. Further, the brush 33 is mounted on the carriage 42 as in the case of the small camera 7 described above, so that the brush 33 can move in the scanning direction simultaneously with the movement of the carriage 42 in the scanning direction. Therefore, brush 3
When 3 is lowered, that is, when the tip of the brush 33 is in contact with the printing surface of the recording medium R, when the carriage 42 moves in the scanning direction at the same time as the carriage 42 moves in the scanning direction, the recording head By 41, foreign matter adhering to the print surface of the recording medium R before the UV ink is ejected is removed, and the print surface is cleaned. That is, the brush 33 functions as a cleaning unit that cleans the printing surface of the recording medium R.

The small camera 7 as the above-mentioned detecting means,
In the operation of the inkjet printer A including the brush 33 as a cleaning unit, when the small camera 7 detects a foreign object accompanying the movement of the carriage 42 in the scanning direction, the brush 33 is in a lowered state (usually in an elevated state). Therefore, the printing surface before the printing is performed by the recording head 41 moves in the scanning direction while the tip of the brush 33 is in contact with the printing surface of the recording medium R to remove foreign matters. It is in a cleaned state. Then, the recording medium R is conveyed to a position facing the recording head 41 in the cleaned state and printing is performed. When the UV curing inhibitor is removed as “foreign matter”, the UV irradiation by the UV irradiation unit 5 causes
Curing of the V ink is not hindered.

As described above, according to the modification shown in FIG. 2, by providing the brush 33 as the cleaning means,
The same effect as the above-mentioned example shown in FIG. In particular, according to the modified example shown in FIG. 2, the small camera 7 as the detection means reliably detects the foreign matter adhering to the printing surface of the recording medium R, and further detects the detected foreign matter as the brush as the cleaning means. Since it is removed by 33, the printing surface of the recording medium R before the UV ink is ejected by the recording head 41 can be surely brought into the cleaned state in which the foreign matter is removed. In this case, the droplets of the UV ink are ejected onto the surface of the foreign matter to increase the viscosity, the droplets are not separated from the recording medium R at the same time as the foreign matter after the printing is completed, and the foreign matter is removed, so that the recording medium is removed. The fixability of the UV ink droplets on the R does not deteriorate. As a result, high quality printing can be retained.

As shown in FIG. 3, the cleaning section 3 is provided with two suction rollers 34 and 35 and two cleaning brushes (hereinafter referred to as brushes) 36 and 37.

The suction rollers 34 and 35 are arranged adjacent to each other and are in contact with each other on the printing surface and the non-printing surface side of the recording medium R, and in the conveying direction D of the recording medium R to be conveyed. The two are rotated in reverse with each other.
The surfaces of the suction rollers 34 and 35 are formed so as to be able to adsorb quality-reducing substances (for example, minute dust). Therefore, the recording medium R conveyed while being sandwiched between the two suction rollers 34 and 35 is in a state where the printing surface and the non-printing surface are cleaned by the two suction rollers 34 and 35. That is, the two suction rollers 34 and 35 have a function as a cleaning unit that cleans the printing surface and the non-printing surface of the recording medium R.

The brushes 36 and 37 are provided on the printing surface side and the non-printing surface side of the recording medium R, respectively, and at the positions facing the two suction rollers 34 and 35, respectively. More specifically, the tips of the two brushes 36 and 37 are always in contact with the surfaces of the two suction rollers 34 and 35, and the tips of the suction rollers 34 and 35 that rotate as the recording medium R is conveyed. The quality-reducing substances adsorbed on the surface are removed. That is, these two brushes 36 and 37 have a function as second cleaning means for further cleaning the suction rollers 34 and 35 as cleaning means.

As described above, according to the modified example shown in FIG. 3, since the suction rollers 34 and 35 as the cleaning means are provided, the same effect as that of the above example shown in FIG. 1 can be obtained. In particular,
According to the modification shown in FIG. 3, two suction rollers 34 and 35 for cleaning the printing surface and the non-printing surface of the recording medium R are used.
The surface of is cleaned by two brushes 36 and 37 as a second cleaning means. That is, the quality-reducing substances adsorbed on the surfaces of the suction rollers 34 and 35 are not absorbed by the brush 3 during the rotation of the suction rollers 34 and 35.
It is designed to be removed by 6, 37. In this case, printing is not performed with the surfaces of the suction rollers 34 and 35 being soiled, and even if printing is performed for a long time, the printing surface of the recording medium R during this period can be more reliably. In addition, since the cleaning is performed in a stable manner, high-quality printing can be retained more reliably and stably. In addition, U
When the V-curing inhibitor is removed, the UV irradiation in the UV irradiation unit 5 does not hinder the curing of the UV ink.

Although the brushes 31, 32, 33, 36, 37 are disclosed as cleaning means in the examples shown in FIGS. 1 to 3, the recording medium R is made of an elastic material such as rubber instead of these brushes. As the cleaning means, a blade (which may be a metal blade of a type in which an elastic body such as rubber is molded only at the tip end of the metal portion) which follows the print surface of the recording medium R as it is conveyed may be applied.

[0041]

According to the present invention, since the ink jet printer of the present invention is provided with the cleaning means, the printing surface of the recording medium conveyed to the position where the UV ink is ejected by the head is cleaned by this cleaning means. It has already been cleaned. When printing is performed on the printing surface of the recording medium in such a state, the adhesion or bleeding property of the UV ink on the recording medium may change as compared with the state in which high quality printing is performed. The UV ink does not discolor. As a result, high quality printing can be retained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of essential parts for explaining a printed portion of an inkjet printer according to an embodiment.

FIG. 2 is a sectional view of an essential part for explaining a modified example of the printed portion.

FIG. 3 is a main-portion cross-sectional view for explaining a modified example of the printed portion.

[Explanation of symbols]

A inkjet printer D conveyance direction R recording medium 1, 2 conveyance rollers (conveyance means) 3 cleaning section 4 printing section 5 UV irradiation section 7 small camera (detection means) 31, 32, 33 cleaning brush (cleaning means) 34, 35 adsorption Rollers (cleaning means) 36, 37 Cleaning brushes (second cleaning means) 41 Recording heads (heads) 51 UV lamps

Claims (5)

[Claims] 1. A transporting means for transporting a sheet-shaped recording medium, and a head for discharging and printing UV ink, which cures when irradiated with ultraviolet rays, on a printing surface of the recording medium transported by the transporting means. An inkjet printer, comprising: a cleaning unit that cleans a print surface of the recording medium before the UV ink is ejected by the head. 2. A transporting means for transporting a sheet-shaped recording medium, and a head for discharging and printing UV ink, which cures when irradiated with ultraviolet rays, on a printing surface of the recording medium transported by the transporting means. A method of recording on a recording medium using an inkjet printer provided, comprising a cleaning step of cleaning a print surface of the recording medium before the UV ink is ejected by the head. 3. The ink jet printer according to claim 1, wherein a foreign substance having a diameter larger than a droplet of the UV ink and adhering to a print surface of a recording medium before the UV ink is ejected by the head is detected. An ink jet printer, comprising: a detection unit for cleaning the print surface of the recording medium before the head ejects the UV ink by the cleaning unit when the detection unit detects the foreign matter. . 4. The inkjet printer according to claim 1, further comprising a UV lamp for irradiating the print surface of the recording medium with UV in order to cure the UV ink attached to the print surface of the recording medium. Is the U from the UV lamp
An ink jet printer characterized by removing a substance that inhibits curing of V ink. 5. The ink jet printer according to claim 1, further comprising a second cleaning unit that cleans the cleaning unit.