JP2003285426A - Inkjet printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet printer which can make an illuminating mechanism compact by making the illuminating mechanism for ultraviolet rays a relatively low illuminance and can suppress generation of ozone. <P>SOLUTION: The inkjet printer has a chamber structure 10 with a chamber 13b inside, a carriage 3 arranged inside the chamber structure 10, an inert gas supply means for supplying an inert gas to the chamber 13b, and an oxygen sensor set in the chamber 13b. A plurality of heads for discharging ink drops highly reactive to the oxygen towards a recording medium 99 are set at the carriage 3, and an UV light source is set between the heads. The inert gas is supplied into the chamber 13b and at the same time, an oxygen concentration in the chamber 13b is detected to maintain a desired inert gas ambience. The illuminating mechanism can be made compact and also the generation of ozone can be restricted accordingly. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inkjet printer.

[0002]

2. Description of the Related Art In recent years, as an image printing method capable of forming an image easily and inexpensively, many image printing methods using an ink jet printer have been adopted. An inkjet printer intermittently moves a recording medium such as paper or a resin film in the sub-scanning direction, and moves a head on the recording medium in the main-scanning direction perpendicular to the sub-scanning direction when the recording medium is stopped. . Then, while the head is moving in the main scanning direction, the inkjet printer ejects ink droplets from the head onto the recording medium by means of a piezo element or a heater. An image is printed on the recording medium by such an operation of the inkjet printer.

As an ink used in an ink jet printer, there is a photocurable ink which is cured by irradiation with light such as ultraviolet rays. The photocurable ink is, for example, a pigment, a monomer or oligomer serving as a precursor of a polymer compound, and a radical (active species) generated by light energy (mainly ultraviolet energy), and the radical crosslinks the monomer or oligomer. It is composed by including a photopolymerization initiator that advances a reaction or a polymerization reaction, and is cured by a crosslinking reaction or a polymerization reaction by irradiation of light. A printer that prints with such a photo-curable ink has a relatively low odor compared to a printer that prints with a solvent-based ink, and has recently attracted attention because it can record on a recording medium that does not absorb ink.

[0004]

By the way, ultraviolet rays are radiated in order to cure the photo-curable ink adhering to the recording medium. However, since the ultraviolet rays are radiated in the atmosphere, the ultraviolet rays having high illuminance (having large energy) are radiated. It is essential to irradiate. Therefore, the ultraviolet light source becomes large. Along with this, the power source of the light source becomes large in weight and volume, and further, a cooling mechanism for suppressing the irradiation heat of the light source is required. Therefore, it is difficult to reduce the size of the mechanism for irradiating the ultraviolet rays inside the printer body. Further, when the recording medium is irradiated with ultraviolet rays having large energy, the recording medium is easily deteriorated, and a recording medium made of a material weak against ultraviolet rays cannot be applied. Therefore, a recording medium having resistance to ultraviolet ray irradiation must be selected. I won't.

Therefore, it may be considered to irradiate ultraviolet rays having low illuminance. However, although radicals are generated in the polymerization initiation reaction of the photopolymerization initiator composing the photocurable ink, the radicals are consumed by the reaction of oxygen in the atmosphere with the radicals, and the activity of the photocurable ink is oxygen. Will be reduced by. Therefore, irradiation of ultraviolet rays having a certain illuminance is necessary for curing the photocurable ink. Further, in particular, when oxygen in the atmosphere reacts with the generated radicals, ozone is generated, and an offensive odor due to ozone generation (ozone odor) emerges as another problem.

[0006] Therefore, an object of the present invention is to provide an ink jet printer which can make the irradiation mechanism compact by using an ultraviolet light irradiation mechanism having a relatively low illuminance, and which can suppress an offensive odor caused by ozone generation. Is to provide.

[0007]

In order to solve the above-mentioned problems, an ink-jet printer according to the invention of claim 1 is a photocurable ink which is adhered to a recording medium and which is cured by irradiation of light. Irradiating means for irradiating the recording medium, shielding means for shielding the contact between the vicinity of the irradiated portion where the photo-curable ink adhered to the recording medium is irradiated with light by the irradiating means and the outside air, and the contact with the outside air by the shielding means A gas supply means for supplying an inert gas inert to the photocurable ink to the vicinity of the irradiated portion shielded from the light, a detection means for detecting an oxygen concentration in the vicinity of the irradiated portion, and the detection means. Control means for controlling the supply of the inert gas from the gas supply means so that the oxygen concentration detected by the method becomes equal to or lower than a predetermined set concentration.

According to the first aspect of the present invention, the photocurable ink attached to the recording medium is irradiated with light by the irradiation means. At this time, the photocurable ink is irradiated with light by the irradiation means. The vicinity is supplied with the inert gas by the gas supply means in a state where the contact with the outside air is substantially shielded by the shield means. Then, in the vicinity of the irradiated portion, the oxygen concentration is detected by the detection unit, and the control unit controls the oxygen concentration to be equal to or lower than the set concentration. That is, it is possible to replace the atmosphere with an inert gas and maintain the vicinity of the irradiated portion under a desired inert gas atmosphere. Therefore, the photo-curable ink attached to the recording medium is not cured by oxygen, and is reliably cured on the recording medium without increasing the ultraviolet energy.
In this case, since a light source with low illuminance (irradiation means of the present invention) can be applied to the printer body, the irradiation mechanism for irradiating light can be made compact, and recording can be performed on a recording medium that is easily deteriorated by ultraviolet rays. . Furthermore, since it is possible to irradiate with ultraviolet light of low illuminance and maintain it in a desired inert atmosphere, it is possible to improve image quality.

By the way, basically, the photocurable ink contains a photopolymerization initiator, a radical is generated by the initiation reaction of the photopolymerization initiator, and ozone is generated by reacting the radical with oxygen. However, in the invention of claim 1,
The vicinity of the irradiated portion where the photocurable ink is irradiated with the light by the irradiation means is in an inert gas atmosphere and the oxygen concentration is very low. Therefore, the reaction between radicals and oxygen is suppressed as much as possible and the generation of ozone is also suppressed. Therefore, it is possible to suppress the generation of ozone odor, which is an offensive odor.

According to a second aspect of the present invention, in the ink jet printer according to the first aspect, the control means switches between supplying and not supplying the inert gas from the gas supply means, and the inert gas is supplied. It is characterized by controlling the supply of gas.

According to the second aspect of the present invention, when the oxygen concentration detected by the detecting means is equal to or lower than the set concentration, the control means may switch so as not to supply the inert gas from the gas supply means. it can. Therefore, it is not necessary to supply the inert gas more than necessary, so that the supply amount (consumption amount) of the inert gas can be saved.

According to a third aspect of the present invention, in the ink jet printer according to the first aspect, the control means includes an adjusting means capable of adjusting a flow rate of the inert gas flowing out from the gas supply means, and the adjusting means. According to the method, the flow rate of the inert gas is adjusted to control the supply of the inert gas.

In the invention according to claim 2, when the inert gas is not supplied, oxygen in the atmosphere penetrates into the vicinity of the irradiated portion, and the detected oxygen concentration is temporarily higher than the set concentration. Could be. However, claim 3
In the invention described above, since the flow rate of the inert gas is adjusted by the adjusting means to supply the inert gas, the inert gas can be constantly supplied in the vicinity of the irradiated portion. Therefore, it is possible to reliably prevent the oxygen concentration in the vicinity of the irradiated portion from becoming higher than the set concentration, and it is possible to maintain the vicinity of the irradiated portion in an optimal inert gas atmosphere.

The invention according to a fourth aspect is the ink jet printer according to any one of the first to third aspects,
A head that ejects a photocurable ink that cures by irradiation of light, a transport unit that transports a recording medium to which the photocurable ink adheres in a predetermined direction, a discharge operation of the photocurable ink by the head, and the transport unit. When the images are sequentially recorded on the recording medium by the recording medium conveying operation including the recording medium conveying operation and the oxygen concentration detected by the detection unit exceeds the set concentration, the image being recorded is recorded. Recording operation control means for controlling the recording operation to continue until the formation of the image is completed, and to stop the recording operation after the formation of the image being recorded is completed.

If the recording operation is stopped when the detected oxygen concentration exceeds the set concentration and the recording operation is restarted when the oxygen concentration reaches the set concentration or less, the ink ejection by the head is restarted. The affected part remains as a defective part in the image to some extent. However, in the invention described in claim 4, when the oxygen concentration detected by the detection means exceeds the set concentration, the recording operation control means continues the recording operation until the formation of the image being recorded is completed. The print quality of the image does not deteriorate significantly. Therefore, there is a possibility that the final recorded matter on which the image is recorded can be treated not as a defective recorded matter but as a recorded matter on which the image is normally recorded.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Specific embodiments of the present invention will be described below with reference to the drawings. However, the scope of the invention is not limited to the illustrated example. FIG. 1 is a perspective view showing a main part of the inkjet printer 1, and FIG. 2 is a bottom view showing a carriage 3 provided in the inkjet printer 1. Further, FIG. 3 is a view showing a chamber structure 10 provided in the inkjet printer 1.
FIG. 4 is a partial cross-sectional view seen from the main scanning direction A of FIG. FIG. 4 is a block diagram schematically showing the control means 40 provided in the inkjet printer 1 and each member related to the control device 40.

The ink jet printer 1 has a droplet (hereinafter, referred to as "UV ink") of an ultraviolet curable ink (hereinafter, referred to as "UV ink") having a property of being cured by irradiation with ultraviolet rays as light.
It is called "ink droplet". ) Is discharged toward the recording medium 99, and ultraviolet rays are irradiated after the ink droplets are attached to print on the recording medium 99. In the following description, UV ink is used as the photo-curable ink, but ink having the property of being cured by irradiation with electromagnetic waves such as infrared rays, visible rays, electron beams, and X-rays may be used. Here, light is light in a broad sense. That is, the light mentioned in this specification includes not only visible light but also electromagnetic waves such as ultraviolet rays, infrared rays, electron beams, and X-rays. The material of the recording medium 99 may be resin, paper, or any other material that can be printed by the inkjet printer 1.

As shown in FIGS. 1 to 3, the ink jet printer 1 mainly comprises a conveying means 11 for conveying a sheet-shaped recording medium 99 in the sub-scanning direction B and a substantially right angle with respect to the sub-scanning direction B. A guide member 2 that extends in the main scanning direction A, a carriage 3 that is a moving body that is guided by the guide member 2 and moves in the main scanning direction A along the guide member 2, and a plurality of ejecting ink droplets of UV ink. ..., a plurality of UV light sources 5, 5, ... (illustrated in Fig. 2) for irradiating the recording medium 99 with ultraviolet rays, and a cover 9 (Fig. 2) provided for each UV light source 5. Etc.), a plurality of ink tanks 6, 6, ... Which are arranged below the carriage 3 and store UV ink, and an ink supply path 7 for supplying UV ink from the ink tank 6 to the head 4. Provided in each ink tank 6 A transformer pump 8, a chamber structure 10 for housing the carriage 3 therein and for shielding the internal space from the outside air, a platen 12 arranged in the chamber structure 10, and an inert gas inert to UV ink. A gas supply means 56 (shown in FIG. 4 or the like) for supplying into the chamber structure 10, an oxygen sensor 51 (shown in FIG. 4 or the like) provided in the chamber structure 10 for detecting the oxygen concentration in the chamber structure 10, and a gas. The control means 40 (illustrated in FIG. 4 and the like) for controlling the supply of the inert gas from the supply means 56.

As shown in FIG. 1, the ink tanks 6, 6,
... are replaceable ink cartridges, and each ink tank 6 stores one color of UV ink. That is, in one ink tank 6,
UV ink of any one of several colors is stored. Although UV inks of different colors are basically stored in each ink tank 6, UV inks of the same color may be stored in two or more ink tanks 6. As the colors of the UV ink used in the inkjet printer 1,
Basically, each process color of yellow (Y), magenta (M), cyan (C), and black (K) is used. In addition, light yellow (LY), light magenta (L)
M), light cyan (LC), light black (L
K), or features such as white (W), red (R), blue (B), and green (G).

The UV ink stored in each ink tank 6 has a pigment corresponding to a color, a monomer or an oligomer serving as a precursor of a photopolymerization resin, and a radical generated by ultraviolet energy to generate a monomer or an oligomer. A photopolymerization initiator that promotes a crosslinking reaction or a polymerization reaction, a photopolymerization accelerator that accelerates the initiation reaction of the photopolymerization initiator, and the like are included. A monomer or an oligomer undergoes a crosslinking reaction or a polymerization reaction as the photoreaction initiator irradiated with ultraviolet rays acts as a catalyst, and the UV ink has a property of being cured by such a reaction.

As shown in FIG. 3, the conveying means 11 moves the recording medium 99 in the sub-scanning direction B in accordance with the operation of the carriage 3.
It also has a function of carrying the recording medium 99 intermittently, that is, a function of intermittently carrying the recording medium 99, that is, a function of repeatedly stopping and carrying the recording medium 99. The details of the transport means 11 will be described later.

As shown in FIG. 1, the carriage 3 reciprocates in the main scanning direction A along the guide member 2 in accordance with intermittent conveyance of the recording medium 99, and specifically, the recording medium. When 99 is stopped, it moves forward, backward, or reciprocates in the main scanning direction A.

As shown in FIG. 3, the platen 12 is arranged so as to face the carriage 3, and holds the non-printing surface of the recording medium 99 conveyed below the carriage 3 by suction. Specifically, a suction chamber having a fan is provided below the platen 12, and the platen 12 has a suction port formed of a plurality of small holes communicating with the suction chamber.
It is provided on the back side of. Accordingly, by driving the fan in the suction chamber, the non-printing surface of the recording medium 99 on the platen 12 is sucked, and the recording medium 99 can be conveyed in the sub-scanning direction B in a state of being in close contact with the platen 12.

As shown in FIG. 1, the ink supply path 7 is UV
.. to the heads 4, 4, .. Supplied. That is, the color of the UV ink stored in any one of the ink tanks 6 is the same as the color of the ink droplets ejected from the head 4 communicating with that ink tank 6 via the ink supply path 7. The ink supply path 7 is formed of a flexible member so that it can follow the movement of the carriage 3.

A plurality of transformer pumps 8, 8, ... Are provided in the ink supply path 7. An ink supply path 7 in which a transformer pump 8 communicates with the head 4 from the ink tank 6.
The amount of ink supplied from the ink tank 6 to the head 4 is changed by changing the internal pressure of.

The carriage 3 will be described in detail. As shown in FIG. 2, the heads 4, 4, ... Are attached to the carriage 3, and the UV light sources 5, 5 ,.
, And the covers 9, 9 ... Are attached to the carriage 3 so as to cover the UV light sources 5. Therefore, as the carriage 3 moves, the heads 4, 4,
... scan the recording medium 99, and the UV light sources 5, 5, ... scan the recording medium 99 together with the heads 4, 4 ,.

A plurality of ejection ports (nozzles (not shown)) are formed on the lower surface of each head 4, and the plurality of ejection ports are arranged in a line in the sub-scanning direction B. Ejecting means (not shown) such as a piezo element is provided inside each head 4, and ink droplets are separately ejected from each ejection port by the operation of the ejecting means. UV ink of any one of several colors is ejected from one head 4. Although ink droplets of UV ink of different colors are basically ejected for each head 4, UV ink of the same color may be ejected from two or more heads 4.

Each UV light source 5 is composed of an ultraviolet lamp or the like which emits ultraviolet rays in a specific wavelength region (for example, wavelength 250 nm) with stable irradiation energy. The wavelength and irradiation intensity of the ultraviolet rays emitted from the UV light source 5 are determined by the recording medium 9
It is appropriately set according to the material of No. 9 or the type of UV ink. LED (light emitting d)
iode), fluorescent lamps, high pressure mercury lamps, metal halide lamps, high pressure mercury spot lamps, xenon lamps, etc. are applicable. The UV light source 5 is made of the material of the recording medium 99 or UV.
It may be possible to change the wavelength and irradiation energy of ultraviolet rays to be irradiated depending on the type of ink.

Each cover 9 covers the UV light source 5 from above. The cover 9 shields the ultraviolet rays from the UV light source 5 so that the head 4 is not exposed to the ultraviolet rays, and conversely the recording medium 99 is exposed to the ultraviolet rays from the UV light source 5. The length of the UV light source 5 in the sub-scanning direction B is
It is longer than or substantially equal to the length of the head 4 in the sub-scanning direction B.

The heads 4, 4, ... Are arranged in a line in the main scanning direction A at equal intervals. The UV light sources 5, 5, ... Are also arranged in a line in the main scanning direction A at equal intervals. Also,
One head 4 is interposed between the two UV light sources 5 and 5, and the heads 4 and the UV light sources 5 are alternately arranged in the main scanning direction A.

The heads 4, 4, ... And the UV light source 5,
In the row consisting of 5, ..., Both ends in the main scanning direction A are U
It is a V light source 5. Further, the distance between the head 4 and the UV light source 5 adjacent to the one side thereof is equal to the distance between the UV light source 5 adjacent to the other side. That is, the head 4 and the UV light source 5
Are arranged in a straight line alternately and at equal intervals. Note that, in FIG. 2, the reference numerals shown on the heads 4 mean the colors of the ejected ink droplets, but the color arrangement is not limited to that shown in FIG.

While the carriage 3 is moving forward, backward or reciprocating, ink droplets are ejected from each head 4 and adhere to the recording medium 99. At that time, when the UV light source 5 adjacent to the head 4 is located immediately above the ink droplets that have adhered as the carriage 3 moves, the adhered ink is
It is cured by being irradiated with ultraviolet rays from the V light source 5. That is, ink droplets are ejected onto the recording medium 99 above the platen 12, and ultraviolet rays are emitted onto the ink droplets that have adhered above the platen 12.

Next, the chamber structure 10 and the transfer means 1
1 will be described. As shown in FIG. 3, the chamber structure 10 has a box body 13 having an internal space and surrounding the carriage 3 and the platen 12 arranged in the internal space,
Partition plates 20, 21, 2 provided on the inner surface of the box body 13
2, 23, and. The box body 13 includes an upper surface portion 14 and a lower surface portion 15 that are oriented in a direction perpendicular to the main scanning direction A and the sub scanning direction B, two side surface portions (not shown) that are oriented in the main scanning direction A, and a sub body. It has a substantially rectangular parallelepiped shape composed of a front surface portion 16 and a rear surface portion 17 facing the scanning direction B, and these surfaces form an internal space. Through holes 16a and 17a are formed in the surface portions 16 and 17, respectively. The through hole 16a communicates with the inside and outside of the box body 13 at the front surface portion 16, and the through hole 17a is provided inside and outside the box body 13 at the rear surface portion 17. The through holes 16a and 17a face each other.

The partition plate 20 is a ridge protruding from the upper surface portion 14 into the internal space of the box body 13, and is elongated in the main scanning direction A. The partition plate 21 is a ridge protruding from the lower surface portion 15 into the internal space of the box body 13, and is elongated in the main scanning direction A. The partition plate 20 and the partition plate 21 are arranged to face each other in the vertical direction. The partition plate 22 is a ridge protruding from the upper surface portion 14 into the internal space of the box body 13,
It is elongated in the main scanning direction A. The partition plate 23 is a ridge protruding from the lower surface portion 15 into the internal space of the box body 13,
It is elongated in the main scanning direction A. The partition plate 22 and the partition plate 23 are arranged to face each other in the vertical direction.

The internal space of the box body 13 has partition plates 20, 2
It is divided into three parts by 1, 22, 23. That is, the internal space of the box body 13 includes an upstream chamber 13 a in the sub-scanning direction B, a downstream chamber 13 c in the sub-scanning direction B, and a chamber 13.
It is composed of a chamber 13b between the chamber a and the chamber 13c. The chambers 13a and 13b are partitioned by partition plates 20 and 21, and the chambers 13b and 13c are partitioned by partition plates 22 and 23.

Nip rollers 24, 24, which constitute the conveying means 11, are arranged between the partition plate 20 and the partition plate 21. The nip rollers 24, 24 are arranged facing each other and in close proximity to each other, and are rotatable about an axis in the main scanning direction A. Similarly, between the partition plate 20 and the partition plate 21, the nip rollers 25, 25 forming the transport means 11 are provided.
Are arranged. The nip rollers 25, 25 are arranged facing each other and in close proximity to each other, and are rotatable around the axis in the main scanning direction A. Nip rollers 24, 24
Are respectively close to the partition plates 20 and 21, and the nip rollers 25 and 25 are close to the partition plates 22 and 23. That is, the passage opening (the partition plate 20) communicating with the chambers 13a and 13b.
(Gap between the partition plate 21 and the partition plate 21)
The passage opening (a gap between the partition plate 22 and the partition plate 23) communicating with the chambers 13b and 13c is closed by the nip rollers 25, 25.

When viewed from the side, a contact point between one nip roller 24 and the other nip roller 24, a contact point between one nip roller 25 and the other nip roller 25, and a through hole 16
The "a" and the through hole 17a are substantially linear in the sub-scanning direction B. The recording medium 99 has a through hole 16a.
Through the partition plate 20 and the partition plate 21 to reach the chamber 13b, and between the partition plate 22 and the partition plate 23 to reach the chamber 13c. , Through the through hole 17b to the outside of the box body 13. The recording medium 99 is sandwiched by the nip rollers 24, 24 between the partition plate 20 and the partition plate 21, and is sandwiched by the nip rollers 25, 25 between the partition plate 22 and the partition plate 23. By rotating at least one of the nip rollers 24, 24, 25, 25, the recording medium 99
Are conveyed in the sub-scanning direction B.

A platen 12 and a carriage 3 are arranged in a chamber 13b inside the box 13. Therefore, the carriage 3 reciprocates in the main scanning direction A within the chamber 13b.
Since the carriage 3 is arranged in the chamber 13b, the heads 4, 4, ... And the UV light sources 5, 5, ... Are also arranged in the chamber 13b. That is, in the chamber 13b, the heads 4 and 4 are directed toward the recording medium 99 conveyed on the platen 12.
, And the UV light sources 5, 5, ... irradiate the ink droplets adhering to the recording medium 99 with ultraviolet rays. Obey,
The ink droplets attached to the recording medium 99 are UV light sources 5, 5, ...
The irradiated portion 18 irradiated by the light and its vicinity are
Located in room 13b.

The gas supply means 56 supplies an inert gas inert to the UV ink into the chamber 13b. Examples of the inert gas include helium gas, neon gas, argon gas, krypton gas, nitrogen gas and carbon dioxide gas. In addition to these gases, any gas that does not reduce the curing speed of the UV ink, that is, a gas that is inert to the radicals generated in the initiation reaction of the photopolymerization initiator can be used as an inert gas. .

As the gas supply means 56, a nitrogen gas cylinder is used, an apparatus for separating only nitrogen gas from the outside air by utilizing the difference in permeability between oxygen and nitrogen with respect to the hollow fiber membrane is used, and PSA (Pressure by activated carbon) is used. Swing Adsor
A device that supplies an inert gas by the ption) method is also used. As the supply path of the inert gas, for example, the inert gas is generated above the row of the heads 4, 4, ... And the UV light sources 5, 5 ,. There is a method of supplying it to the lower side of the carriage 3 through the same.

The oxygen sensor 51 detects the oxygen concentration in the chamber 13b, more specifically, the oxygen concentration in the vicinity of the irradiated portion 18. The oxygen sensor 51 is installed in the chamber 13b. The oxygen sensor 51 can almost certainly detect the oxygen concentration in the chamber 13b including the vicinity of the irradiated portion 18, but since the oxygen concentration in the vicinity of the irradiated portion 18 is particularly desired to be detected, the oxygen sensor 51 is provided around the irradiated portion 18. Is preferably provided. As the oxygen sensor 51, for example, a galvanic cell type oxygen sensor using a strong electrolyte aqueous solution can be applied, and any sensor that can detect the oxygen concentration at room temperature can be applied as the oxygen sensor 51. The chamber structure 10 as described above shields the contact between the chamber 13b and the outside air, and the inert gas is supplied to the chamber 13b, so that the chamber 13b becomes an inert atmosphere and the oxygen concentration in the chamber 13b decreases.

Next, the control means 40 will be described. As shown in FIG. 4, the control means 40 includes a CPU 45 and an RA.
M44, ROM46, interfaces 41 and 43
And an arithmetic processing unit having a system bus for connecting them. CPU 4 of control means 40
An oxygen sensor 51 is connected to 5 via a system bus and an interface 41, and a detection signal detected by the oxygen sensor 51 is input. Furthermore, CP
The head 4, the transport means 11, and the gas supply means 56 are connected to the U45 via the system bus, the interface 43, and the drive circuits 52, 53, and 54.

In the ROM 46, the head 4 and the transport means 1
A control program for controlling the recording medium 1 and the like to perform the recording operation on the recording medium 99 and the operation accompanying the recording operation, and the control data used in this control program are stored. Furthermore, ROM46
The gas supply means 56 is controlled to control the chamber structure 10.
It also stores a gas supply program that causes the inkjet printer 1 to perform an operation of supplying an inert gas into the chamber 13b, and data used in this gas supply program. The CPU 45 uses the RAM 44 as a work area and ROMs
The calculation is performed according to the control program, the gas supply program, and the like stored in 46. The CPU 45 can output a drive signal according to the calculation result to the head 4, the transport unit 11, the gas supply unit 56, and the like. That is, the control means 40 uses the CP
The inkjet printer 1 can be controlled by the calculation of U45, whereby the inkjet printer 1 performs the recording operation on the recording medium 99 and also supplies the inert gas.

Next, the operation of the ink jet printer 1 configured as described above will be described. During the operation of the inkjet printer 1, ultraviolet rays are emitted from the UV light source 5 and the recording medium 99 is irradiated with the ultraviolet rays. Further, while the inkjet printer 1 is operating, the oxygen sensor 51 constantly detects the oxygen concentration in the chamber 13b (the volume concentration of oxygen in the chamber 13b; the same applies below).
Inert gas is supplied inside. As a result, the chamber 13
The air in b is replaced with the inert gas, and the inside of the chamber 13b is maintained under the inert gas atmosphere.

Specifically, referring to FIG. 5, the CPU 45 of the control means 40 outputs a drive signal to the gas supply means 56 to supply the inert gas, and the gas supply means 56.
From which inert gas is supplied. As a result, the inside of the chamber 13b is purged with an inert gas (step S1), and the CPU 45 causes the oxygen sensor 51 to operate based on the detection signal of the oxygen sensor 51.
It is determined whether the oxygen concentration detected by is 10% or less (step S2).

When the oxygen concentration detected by the oxygen sensor 51, that is, the oxygen concentration in the chamber 13b becomes 10% or less, a drive signal for stopping the supply of the inert gas from the CPU 45 of the control means 40 to the gas supply means 56. Is input, and purging with an inert gas is interrupted (step S
3). Then, the CPU 45 determines whether the oxygen concentration detected by the oxygen sensor 51 is 12% or less (step S4). When the oxygen concentration becomes 12% or less, the process returns to the step S1 and the inside of the chamber 13b is restarted. Purge with inert gas. By detecting the oxygen concentration by the oxygen sensor 51 as described above, the oxygen concentration in the chamber 13b, specifically, in the vicinity of the irradiated portion 18 in the chamber 13b, is approximately 10% to 12%.
%, The inside of the chamber 13 is maintained under an inert gas atmosphere.

The oxygen concentration for maintaining the inside of the chamber 13b in a desired inert gas atmosphere is predetermined,
The determined set density (for example, 14%) is stored in the ROM 46 of the control means 40. Of course, this set concentration can be appropriately changed, and the concentration serving as a reference for purging with an inert gas or interrupting the purging (the numerical values 10%, 12 shown in steps S2 and S4 in FIG. 5).
%) Can be changed appropriately.

Then, as described above, with the inside of the chamber 13b maintained in an inert atmosphere, the nip rollers 24,
The recording medium 99 passes between the partition plate 20 and the partition plate 21 by the rotation of the recording medium 24, the recording medium 99 is carried into the chamber 13b, and the nip rollers 25, 25 are further rotated so that the recording medium 99 is recorded. It passes through between the partition plate 22 and the partition plate 23, and is discharged from the chamber 13b. At this time, the inkjet printer 1 rotates the recording medium 99 in the sub-scanning direction B by rotating the nip rollers 24, 24, 25, 25 by a predetermined angle.
Transport intermittently. Here, when the recording medium 99 is stopped, the carriage 3 moves forward, backward, or reciprocates in the main scanning direction A in the chamber 13b. Then, while the carriage 3 is moving on the recording medium 99, the heads 4, 4, ... Appropriately eject ink droplets from the respective ejection ports, and the ink droplets adhere to the recording medium 99. As the carriage 3 moves, the UV light source 5 adjacent to the head 4 that ejected the ink droplet is positioned immediately above the attached ink droplet, and therefore the ink droplet is irradiated with ultraviolet rays. Harden.

As described above, the ink jet printer 1 performs the reciprocating movement (or the forward and backward movements) of the carriage 3, the ejection of the ink droplets, and the irradiation of the adhered ink droplets, and then the conveying means 11 ( That is, the nip rollers 24, 2
4, 25, 25), the recording medium 99 is conveyed in the sub-scanning direction B by a predetermined distance. Then, when the recording medium 99 stops, the inkjet printer 1 again performs the reciprocating movement of the carriage 3, the ejection of ink droplets, and the irradiation of ink droplets.
After that, the inkjet printer 1 repeats the above-described operation to record an image on the recording medium 99.

Here, during recording of the image, the oxygen concentration detected by the oxygen sensor 51 is temporarily changed to RO of the control means 40.
When the set density (for example, 14%) stored in M46 is exceeded, ink droplet ejection operations by the heads 4, 4, ...
The control unit 40 controls the inkjet printer 1 to continue the recording operation including the operation of conveying the recording medium 99 by the No. 1 recording medium.
To control. When the recording of this image is completed, the CPU 45 of the control device 40 causes at least the heads 4, 4, ...
A drive signal for stopping the recording operation is output to the conveyance means 11 and the recording operation of the image on the recording medium 99 is interrupted. Then, in this state, from the gas supply means 56 to the chamber 13
When the inert gas is continuously supplied into the chamber b and the oxygen concentration in the chamber 13b becomes 10% or less, a new image is recorded on the recording medium 99 again.

As described above, in this embodiment, the chamber structure 10 is provided in the area where an image is actually recorded, and in particular, the ink droplets attached to the recording medium 99 emit ultraviolet rays by the UV light sources 5, 5 ,. The irradiated portion 18 to be irradiated is arranged in the chamber 13b. Regarding the chamber 13b, the gap between the partition plate 20 and the partition plate 21 is the nip rollers 24, 2
4 and the gap between the partition plate 22 and the partition plate 23 is blocked by the nip rollers 25, 25.
The gas in b is unlikely to leak to the outside of the chamber 13b.
The gas outside b is less likely to enter the chamber 13b. Therefore, the contact between the irradiated portion 18 and its vicinity and the outside air is shielded by the chamber 13b. In the present embodiment, the oxygen sensor 51 is installed in the chamber 13b of the chamber structure 10 and the inert gas is supplied to control the oxygen concentration in the chamber 13b to be equal to or lower than the set concentration. Can be maintained under an inert gas atmosphere.

Here, the radicals generated in the initiation reaction of the photopolymerization initiator have higher reactivity with oxygen than with the monomers or oligomers of the photopolymerization resin, and therefore the radicals react with oxygen. Therefore, the adhered ink droplets cause curing inhibition, but in the present embodiment,
Since the inside of the chamber 13b is controlled under a desired inert gas atmosphere, the adhered ink droplets do not hinder the curing, and the UV light source 5
The ink droplets will cure without increasing the UV energy.

Since it is not necessary to increase the ultraviolet energy of the UV light sources 5, 5, ..., The power consumption of the ink jet printer 1 can be suppressed, and the cooling mechanism for cooling the UV light sources 5, 5 ,. Need not be provided. Therefore, the area around the UV light sources 5, 5, ... Is simplified, and the mechanism for irradiating the ultraviolet light can be made compact. Further, since it is not necessary to increase the ultraviolet energy of the UV light sources 5, 5, ..., A material relatively vulnerable to ultraviolet rays can be applied as the recording medium 99.

Although ozone is generated by the reaction between radicals and oxygen, in this embodiment, the chamber 13b is maintained under a desired inert gas atmosphere, and the oxygen concentration in the chamber 13b is the same as the atmospheric oxygen concentration. Since it is lower, the reaction between radicals and oxygen is suppressed as much as possible, and the generation of ozone is also suppressed. Therefore, it is possible to suppress the generation of ozone odor, which is an offensive odor.

Further, in the present embodiment, when controlling the oxygen concentration in the chamber 13b, the inert gas is not always supplied from the gas supply means 56, but the inert gas is supplied or not supplied. Is controlled by switching. For example,
As shown in FIG. 5, the inert gas is not supplied from the gas supply means 56 during the period when the oxygen concentration is approximately 10% to 12%. As a result, unnecessary supply of the inert gas can be suppressed, and the supply amount (consumption amount) of the inert gas can be saved. However, even if the oxygen concentration detected by the oxygen sensor 51 temporarily exceeds the set concentration during the period when the inert gas is not supplied and the image is being recorded, the formation of the image ends. The recording operation continues until. Therefore,
The print quality of the image is not significantly deteriorated, and the final recorded matter on which the image is recorded may be treated not as a defective recorded matter but as a recorded matter on which the image is normally recorded.

The present invention is not limited to the above-mentioned embodiment, and within the scope of the present invention,
Various improvements and design changes may be made. For example,
In the above-described embodiment, as described with reference to FIG. 5, when controlling the oxygen concentration in the chamber 13b, the inert gas is switched between being supplied and not supplied.
The flow rate of the inert gas supplied into 3b may be adjusted and controlled. That is, as shown in FIG. 4, the adjusting means 57 is connected to the CPU 45 of the control means 40 via the system bus, the interface 43, and the drive circuit 55. Then, based on the drive signal from the CPU 45 of the control means 40 to the gas supply means 56, as shown in FIG. 6, the chamber 13b is constantly purged with an inert gas (step T).
1). At this time, based on the drive signal from the CPU 45 to the adjusting means 57, the adjusting means 57 causes the gas supply means 56 to operate.
Adjust the flow rate of the inert gas flowing out from (Step T
2) It is judged whether the oxygen concentration detected by the oxygen sensor 51 is 12% or less (step T3). If it exceeds 12%, the flow rate of the inert gas is increased to 12% or less. In some cases, the flow rate may be maintained or reduced. The “adjusting means 57” is a valve or the like provided at the outlet of the inert gas flowing out from the gas supply means 56.

When the supply of the inert gas is controlled in this way, unlike the present embodiment, the inert gas can be constantly supplied to the inside of the chamber 13b, specifically, the vicinity of the irradiated portion 18. In other words, there is no period in which the inert gas is not supplied into the chamber 13b. Therefore, it is possible to reliably prevent the oxygen concentration in the vicinity of the irradiated portion 18 from becoming higher than the set concentration, and it is possible to maintain the vicinity of the irradiated portion 18 in an optimum inert gas atmosphere.

In the above embodiment, the UV light source 5,
.. are provided on the carriage 3, but they may not be provided on the carriage 3 as long as the adhered droplets can be irradiated with ultraviolet rays. For example, from the carriage 3 in the sub-scanning direction B
A UV light source that extends over the entire width of the box body 13 in the main scanning direction A may be provided on the platen 12 on the downstream side of the. Also in this case, the UV light source is arranged in the chamber 13b of the box body 13, and when the recording medium 99 is conveyed in the sub-scanning direction B after the ejected ink droplets adhere, the ink droplets are generated. When passing under the UV light source, it is irradiated with ultraviolet rays.

In the above embodiment, the heads 4, 4, ...
Are provided on the carriage 3 and reciprocate in the main scanning direction A, but the so-called line heads that do not move are heads 4, 4 ,.
Alternatively, the carriages 3, 3, ... May be provided instead. In this case, it becomes like FIG.

That is, in the chamber 13b, the platen 1
A line head 30 is fixed above the line 2. The ejection openings 32, 32, ... Are formed in a line in the main scanning direction A on the lower surface of the line head 30, and the ejection openings 33, 3 are formed.
Line heads 30 are arranged in a line in the main scanning direction A.
Are formed on the lower surface of the line head 30, and the ejection ports 35, 35, ... Are arranged in a line in the main scanning direction A. Is formed on the lower surface of the line head 30.
, A row of discharge ports 33, 33, ..., a row of discharge ports 34, 34, ... and discharge ports 35, 35,
The rows of ... Extend over the entire width of the chamber 13b in the main scanning direction A.

UV discharged from the discharge ports 32, 32, ...
The ink colors are all the same, and similarly, the ejection ports 33, 3
The color of the UV ink ejected from 3, ... Is the same, the color of the UV ink ejected from the ejection ports 34, 34, ... Is the same, and the UV ejected from the ejection ports 35, 35 ,. All ink colors are the same. However, discharge port 3
The colors of the UV inks ejected from the nozzles 2, 33, 34, and 35 are different from each other. For example, yellow (Y) UV ink is ejected from each ejection port 32, and magenta (M) UV is ejected from each ejection port 33. Ink is ejected, and cyan (C) UV ink is ejected from each ejection port 34.
Black (K) UV ink is ejected from 5. Further, if the UV inks of other colors are to be ejected, a plurality of ejection ports arranged in a line in the main scanning direction A may be provided on the lower surface of the line head 30.

In the case of the ink jet printer as shown in FIG. 7, U extending over the entire width of the box body 13 in the main scanning direction A on the downstream side in the sub scanning direction B from the line head 30.
The V light source 31 is provided above the platen 12. The line head 30 and the light source 31 are arranged in the chamber 13b.
Then, the recording medium 99 is ejected from the line head 30.
The ink droplets adhering to the recording medium 99 are irradiated with ultraviolet rays while passing below the UV light source 31 while the recording medium 99 is being conveyed in the sub-scanning direction B. Even in the inkjet printer as shown in FIG. 7, since the gas supply unit 56 supplies the inert gas into the chamber 13b to control the oxygen concentration in the chamber 13b, the ink droplets attached to the recording medium 99 inhibit the curing. Does not happen.

By the way, in the ink jet printer as shown in FIG. 7, the chamber 13b may be further divided into two. That is, the chamber 13b may be partitioned into a chamber in which the UV light source 31 is present and a chamber in which the line head 30 is internally, but in this case, only the chamber in which the UV light source 31 is mainly inside is inert gas. It may be controlled in an atmosphere or UV
Both the chamber inside the light source 31 and the chamber inside the line head 30 may be controlled under an inert gas atmosphere. Note that FIG. 7A is a partial cross-sectional view as seen in the main scanning direction A, and FIG. 7B is a broken line D of FIG.
FIG. 8 is a cross-sectional view taken along line D in FIG. 7, and in the inkjet printer of FIG. 7, the same components as those of the inkjet printer 1 shown in FIGS. Further, the platen 12 and the recording medium 99 are not shown in FIG.

Further, the line head 30 and the UV light source 3
1 or the carriage 3 is arranged in the chamber structure 10. However, the chamber structure 10 does not necessarily have to be provided. In this case, the line head 30 and the line head 30 can be formed by a so-called air curtain using an inert gas such as nitrogen. The UV light source 31 or the carriage 3 is surrounded. In that case, the inert gas of the air curtain is supplied to the inside while the contact with the outside air is shielded by the air curtain, and the ink droplets adhering to the recording medium 99 are discharged by the UV light sources 5, 5 ,. Irradiated part 1 irradiated with ultraviolet rays
The vicinity of 8 is controlled under a desired inert gas atmosphere, and the ink droplets attached to the recording medium 99 do not inhibit curing.

That is, the line head 30 or the head 4,
When the ink droplets ejected from the recording medium 99 adhere to the recording medium 99 and are irradiated with ultraviolet rays by the UV light sources 5, 5, ... Or the UV light source 31, the contact with the outside air is blocked and the contact with the outside air is prevented. It suffices that an inert gas is supplied to the shielded space and that this space is controlled under a desired inert gas atmosphere. Therefore, it is desirable that the UV light sources 5, 5, ... Or the UV light source 31 is arranged in the chamber 13b, but it is not always necessary to be arranged in the chamber 13b. UV light source 5,
5, or the UV light source 31 is not arranged in the chamber 13b, it goes without saying that the box body 13 is made of a material that transmits ultraviolet rays.

[0066]

According to the present invention, the vicinity of the irradiated portion where the photo-curable ink attached to the recording medium is irradiated with light by the irradiation means is controlled to have an oxygen concentration lower than a predetermined set concentration. It can be maintained under a desired inert gas atmosphere. Therefore, the photo-curable ink attached to the recording medium is not cured by oxygen, and is reliably cured on the recording medium without increasing the ultraviolet energy. In this case, since a light source with low illuminance can be applied to the printer body, the irradiation mechanism for irradiating light can be made compact, and recording can be performed even on a recording medium that is easily deteriorated by ultraviolet rays. further,
The image quality can be improved because the ultraviolet irradiation with low illuminance and the desired inert atmosphere can be maintained. Further, since the vicinity of the irradiated portion is under an inert gas atmosphere and the oxygen concentration is very low, the reaction between radicals and oxygen is suppressed as much as possible, and the generation of ozone is also suppressed. Therefore, it is possible to suppress the generation of ozone odor, which is an offensive odor.

[Brief description of drawings]

FIG. 1 is a perspective view showing a main part of an inkjet printer according to an embodiment.

FIG. 2 is a bottom view schematically showing a carriage included in the inkjet printer.

FIG. 3 is a sectional view showing a chamber structure in which the carriage is housed, as viewed from a side.

FIG. 4 is a block diagram schematically showing a control means provided in the inkjet printer and each member related to the control device.

FIG. 5 is a flow chart for explaining control of inert gas supply by the control means.

FIG. 6 is a flowchart for explaining control of inert gas supply different from that in FIG.

FIG. 7 (a) is a cross-sectional view showing a chamber structure provided in an ink jet printer which is another example of the ink jet printer as viewed from the side, and (b) is a cross sectional view showing the chamber structure as seen from below. is there.

[Explanation of symbols] 1 inkjet printer 4 heads 5 UV light source (irradiation means) 10 Chamber structure (shielding means) 11 Transport means 13 boxes Room 13b 20, 21, 22, 23 Partition plate 24, 25 Nip roller (roller) 30 line head 31 UV light source (irradiation means) 40 control means (recording operation control means) 51 Oxygen sensor (detection means) 56 Gas supply means 57 Adjustment means

Claims (4)

[Claims] 1. An irradiation unit for irradiating light to a photocurable ink that is attached to a recording medium and is cured by irradiation of light, and a photocurable ink attached to a recording medium is irradiated with light by the irradiation unit. A shielding means for shielding the contact between the vicinity of the irradiated portion and the outside air, and an inert gas inert to the photocurable ink in the vicinity of the irradiated portion shielded from contact with the outside air by the shielding means. Gas supply means for supplying, detection means for detecting oxygen concentration in the vicinity of the irradiated portion, and oxygen from the gas supply means so that the oxygen concentration detected by the detection means is below a predetermined set concentration. An inkjet printer comprising: a control unit that controls the supply of an inert gas. 2. The ink jet printer according to claim 1, wherein the control unit controls the supply of the inert gas by switching between supplying and not supplying the inert gas from the gas supply unit. An inkjet printer characterized in that 3. The ink jet printer according to claim 1, wherein the control unit includes an adjusting unit capable of adjusting a flow rate of the inert gas flowing out from the gas supply unit, and the adjusting unit controls the flow rate of the inert gas. An ink jet printer characterized in that the flow rate is adjusted to control the supply of the inert gas. 4. The ink jet printer according to claim 1, wherein a head for ejecting a photocurable ink that is cured by irradiation with light and a recording medium to which the photocurable ink is attached are set in a predetermined direction. When recording an image sequentially on a recording medium by a recording operation to a recording medium including a conveying unit that conveys to the recording medium, a discharging operation of the photocurable ink by the head, and a conveying operation of the recording medium by the conveying unit, When the oxygen concentration detected by the detecting means exceeds the preset concentration, the recording operation is continued until the formation of the image being recorded is completed, and the recording operation is stopped when the formation of the image being recorded is completed. An ink jet printer, comprising: a recording operation control unit that controls to perform the above.