JPH09216352A - Liquid emitting apparatus and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To properly prevent serious emission inferiority, in an ink jet printer emitting ink and a treatment soln. insolubilizing the ink from an ink jet head to perform printing, by controlling the adhesion range of an insoluble matter contained in spring-back mists generated by allowing the ink and the treatment soln. to impinge against a printing medium in a superposed state. SOLUTION: Cover plates 8 are provided so as to cover an emitting orifice surface 5A and the adhesion range of sprung-back mists is controlled by relative air streams generated when an ink jet head 5 is scanned by the cover plates 8. That is, the flow E turned toward the rear side of the upstream side cover plate is generated by the cover plate and mists are guided to the rear side of the cover plate 8 by this flow E. With respect to the downstream side cover plate 8, the flow F going toward the constant flow D separated from the cover plate is generated and mists are guided to the upper surface of the cover plate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid ejecting apparatus and a liquid ejecting method, and more specifically, to a printability improving liquid (hereinafter simply referred to as a treating liquid) for insolubilizing or aggregating an ink and a coloring material in the ink on a print medium. (Also referred to as a liquid ejection apparatus) and a liquid ejection method for performing printing by ejecting (also referred to as).

[0002] The present invention is applicable to all devices that use paper, cloth, leather, nonwoven fabric, OHP paper, or the like, or even metal, as a medium for receiving ejected ink and a printability improving liquid (hereinafter referred to as a print medium). Applicable. Specific examples of applicable equipment include office equipment such as printers, copiers, and facsimile machines, and industrial production equipment.

[0003]

2. Description of the Related Art Many products have a printing method in which a liquid is jetted into a space by a conventionally known liquid jetting method to fly in a space and adhere to a printing medium (paper, OHP paper, processed paper, etc.). Is used for.

As a conventionally known phenomenon in such a liquid ejecting system, small droplets called ink mist other than the ejected droplets are unspecified portions of the print medium or the head. It is known that it adheres to a large area.

In order to prevent the ink mist from adhering to an unspecified portion, for example, the head itself is improved or an air flow by a fan is introduced into the print space between the head and the print medium. There is. As an effect of the former, it can be observed that the generation of ink mist is reduced. However, in the latter case, since the flight direction of the ejected droplets itself may be disturbed by the air flow, it is necessary to use a relatively weak air flow, and a satisfactory effect of preventing ink mist adhesion is not obtained. .

[0006] Further, there is also known one in which the ink mist itself is made to adhere to a predetermined area by an electric field.
When the minute ink droplets that become ink mist have a non-predetermined polarity when separated to form the droplets, or droplets that do not have polarity are generated, it is not possible to effectively control the adhesion range by the electric field. was there.

[0007]

BACKGROUND OF THE INVENTION The present inventors have examined ink mist generated in a conventional device, and most of the conventionally recognized ink mist has a relatively large volume and a relatively high moving speed. The result of the examination was obtained. In other words, this conventional ink mist moves by the kinetic energy of itself toward the direction in which the energy is applied and surely reaches the head, the print medium, or the functional portion inside the apparatus, and the above-mentioned adhesion phenomenon occurs. It happens. Therefore, in order to prevent these conventional ink mist adhesion phenomena, some means that can oppose the moving energy of the ink mist is required.

However, providing such a facing means also in the printing apparatus, as a result, almost always affects the ejected liquid droplet itself for forming an image, and also increases the cost. Therefore, it causes a big problem in practical use.

The present inventors have made a new invention by reexamining the state of generation of ink mist and earnestly studying with an unprecedented focus.

Further, in order to improve the water resistance of the ink jet printed matter, it is also known to react the inks (different colors or the same color) or a treatment liquid which reacts with the inks on the surface of the print medium. .

In these cases, in particular, the liquid droplets formed by the preceding ejection on the print medium are made to collide with the subsequent ejection droplets, so that most of the generated mist is mainly the mist due to rebound. Is coming. Also in this case, the repelling mist itself has a large kinetic energy and adheres to an unspecified place. The present invention has also been studied in this case, and has led to the present invention.

[0012]

SUMMARY OF THE INVENTION It is an object of the present invention to fundamentally improve the generation of ink mist and to provide a situation in which it is easy to control or regulate ink mist.

Further, according to the present invention, the amount of the insoluble matter adhering to the discharge port portion and its vicinity is reduced by positively controlling the deposition range of the insoluble matter due to the reaction, and the discharge state is always maintained in a good state. It is to provide a liquid ejecting apparatus and a liquid ejecting method capable of performing the above.

[0014]

According to the present invention, there is provided:
Generated by using a moving unit for moving the discharging unit provided with a discharge port for discharging the liquid with respect to the medium, and the relative movement of the discharging unit and the medium by the moving unit. And an air flow generation unit for generating an air flow in a direction away from the ejection port in a space near the ejection port surface of the ejection unit in which the ejection port is arranged.

Further, in the liquid ejecting method in which the ejecting means provided with the ejecting port for ejecting the liquid moves relative to the medium to eject the liquid from the ejecting port to the medium, the ejecting means and the medium The air flow generated by utilizing the relative movement of the liquid is generated while generating an air flow in a direction away from the ejection port in the space near the ejection port surface of the ejection unit in which the ejection port is arranged. It is characterized by discharging.

Further, in the liquid ejecting method, the ejecting means provided with an ejecting port for ejecting the liquid moves relative to the medium to eject the liquid from the ejecting port to the medium,
An airflow generated by suspending the liquid between the ejection unit and the medium and utilizing the relative movement of the ejection unit and the medium, wherein the ejection port is arranged. The liquid is ejected while generating an air flow in a direction away from the ejection port in a space near the ejection port surface of the means.

Furthermore, a droplet of 25 pl or less is ejected from the ejecting means at a momentum of 400 pl · m / sec or less, and a mist generated by collision with a medium or a liquid on the medium is generated between the ejecting means and the medium. It is characterized by having a step of floating in the space.

According to the above structure, the mist that accompanies the ejection of the liquid from the head can be moved in the direction away from the ejection port by the air flow, whereby the mist adheres to the ejection port to cause ejection failure. It can be prevented from occurring. Further, since the mist can be in a suspended state, that is, can be easily controlled by the air flow, it is possible to easily control the range in which the mist adheres.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION As described above, the present invention has the following results as a result of examining the contents and behavior of rebound mist.
It was made from a new perspective. In particular, the focus is on the behavior of the rebound mist when the ink or treatment liquid is ejected while the inkjet head (ejection means) is scanning.

1A to 1C and 2A to 2A.
(C) is a figure explaining the behavior of rebound mist.

FIGS. 1A to 1C show a rebound mist 7 when one ink droplet 4A or a treatment droplet 4A is ejected from the ink jet head 5 onto the print medium 2.
Shows the behavior of. As shown in FIG. 7C, the ink droplets or the treatment droplets that have landed on the print medium 2 generate a substantially conical rebound mist 7 having a predetermined angle.
Flies toward the inkjet head 5 at substantially the above predetermined angle.

FIGS. 2A to 2C show rebounding mist when the treatment liquid and the ink are ejected from the ink jet head 5 (each different ink jet head) with a certain time difference. In this case, the subsequent treatment droplet 4A or the ink droplet 4A is landed on the ink droplet 4B or the treatment droplet 4B that has been ejected in advance and has already landed on the print medium 2 (FIG. 2B). Also in this case, a substantially conical rebound mist is generated ((c) in the same figure).

However, since the mist 7 shown in FIG. 2 is generated by collision of the treatment liquid, which is a different liquid, with the ink, the mist contains a mixture of the treatment liquid and the ink. Become.

The inventors of the present application have found that the contents of the rebound mist are relatively different depending on the discharge order of the treatment liquid and the ink. That is, when the treatment liquid is ejected first, a large amount of agglomerates or insolubilized substances due to the reaction between the treatment liquid and the ink are contained, whereas the ink is ejected first and then the treatment liquid is applied to this ink. When it hits, the above-mentioned aggregate is hardly contained. In one embodiment of the present invention, the range of mist adhesion is controlled in consideration of such a discharge order.

The present inventors have also found that the shape of the rebound mist changes mainly due to the distance between the ink jet head and the print medium. 3 and 4 are diagrams for explaining this situation.

When the distance is a certain distance or more, a substantially conical mist 7 as shown in FIG. 3 is formed.

On the other hand, when the distance becomes short, the rebound mist shown in FIG. 3 is formed at the initial stage of continuous ejection, but when the above ejection is further continued, it is ejected continuously. The flight of the ink droplets produces an air flow as shown by A in the figure, whereby the rebound mist 7 gradually receives a force toward the center side in the figure, and finally forms a good vortex shown in FIG.

The formation of the vortex involves the relative movement of the ink jet head. That is, when continuous ejection is performed, their landing positions are continuously displaced due to the relative movement, and thus, strictly speaking, the vortices shown in FIG. 4 are not formed. However, since the rebound mist itself has a velocity component in the relative movement direction, and the discharge velocity is much higher than that component,
It is estimated that a vortex as shown in FIG. 4 is formed for a certain target ejection port.

Even if the rebound mist of any of the forms shown in FIG. 3 or FIG. 4 is formed, the mist may adhere to the ejection port 6 on the ejection port surface 5A of the ink jet head 5 or the vicinity thereof. In particular, when the mist containing a large amount of insoluble matter shown in FIG. 2 adheres to the discharge port or its vicinity, the above-mentioned serious discharge failure may occur.

On the other hand, in one embodiment of the present invention, whether the conical mist shown in FIG. 3 or the mist vortex shown in FIG. The possibility of mist adhering to the discharge port 6 and the like is reduced.

5 and 6 are diagrams for explaining such control.

In one embodiment of the present invention, the cover plate provided to prevent the mist from adhering to the ejection port surface of the ink jet head is positively used for controlling the adhering range.

As described above, the state of the rebounding mist is either scattered in a conical shape (FIG. 5) or a vortex is formed (FIG. 6) depending on the distance between the sheets. In either case, the air flow relative to the inkjet head 5 is generated by the movement of the inkjet head 5 for scanning. This air flow first produces a flow E that wraps around due to the presence of the cover plate 8 on the upstream side of the air flow. That is, the airflow flowing along the surface of the cover plate 8 causes flow separation at the angle 8j of the cover plate 8 on the upstream side and flows behind the cover plate 8 to generate the flow E, whereby the rebound mist is discharged. It is considered to be guided to a portion behind the cover plate 8, which is a position separated from the outlet 6.

On the other hand, in the cover plate on the downstream side, a constant flow D which is apart from the cover plate 8 to some extent.
Exists, and the flow around the wake side cover plate 8 has a relatively large pressure with respect to the portion having the relatively large velocity, so that the flow at that portion is indicated by the arrow F in the figure. Become. Accordingly, it is considered that the rebound mist is similarly guided to the surface side of the wake side cover plate 8 which is a position separated from the discharge port 6.

Thus, according to one embodiment of the present invention, by properly arranging the cover plate 8,
It is possible to control the attachment position of the bounce mist.

In another embodiment of the present invention, in order to control the adhesion range by the air flow shown in FIGS. 5 and 6, instead of using the above-mentioned cover plate, the ejection port surface or the space between the respective color ink ejection parts is simply used. It is also possible to use a convex portion provided at the boundary of. That is, generally, by appropriately setting the shape of the convex portion and the like, the adhesion range of the rebound mist can be made desired.

A preferable shape of the general convex portion including the above-mentioned cover plate is that, in the convex portion on the upstream side, the airflow is caught behind the convex portion.
As a shape that causes such entrainment of air flow,
For example, a method may be considered in which a flow is first generated along the shape of a convex portion, and the flow is separated from the convex portion due to a change in the shape. On the other hand, it is preferable that the convex portion on the wake side does not disturb the constant flow generated in the portion away from the convex portion.

In another embodiment of the present invention, the control of the mist adhesion range is positively utilized.

That is, as described above, the formed mist is in a floating state between the ink jet head and the print medium. That is, these mists generate kinetic energy applied when ejected from the head, especially 400 pl · m / se of droplets with an amount of 25 pl or less.
The energy when ejected with a momentum of c or less is consumed by air resistance or the like after rebounding on the print medium, and finally becomes extremely small in the state shown in FIGS. 3 and 4. As a result, the droplets of the ejected ink or the treatment liquid itself are in a floating state in combination with the fact that they are relatively fine. The mist in the floating state is easily moved by using, for example, an air flow, and in the present embodiment, this is utilized to change the attachment site according to the components mainly contained in the mist. .

As described above, when the ink and the treatment liquid for insolubilizing the ink are used, or when the inks of the same color or different colors that react with each other to insolubilize are used, the insolubilized substance adheres to the ejection port or its vicinity. Is not preferred. Therefore, by appropriately determining the position of the air flow and / or the convex portion of the cover plate or the like, the mist adhering portion is located at a position away from the ejection port.

On the other hand, when inks that do not react with each other and do not cause insolubilization are used, conversely to the above, the adhering portion is concentrated on the ejection port surface to prevent the mist from adhering to other portions. Then, the mist attached to the ejection port surface can be treated by wiping.

[0042]

Embodiments of the present invention will be described below in detail with reference to the drawings.

(Embodiment 1) FIG. 7 is a perspective view showing a schematic view of an ink jet printing apparatus according to an embodiment of the present invention.

In FIG. 7, the recording medium 106 inserted in the paper feeding position of the apparatus 100 is conveyed to the printable area by the ink jet unit 103 by the feed roller 109. A platen 108 is provided on the back surface of the print medium in the printable area.

The carriage 101 has two guide shafts 10
4 and 105, the head unit 103 can reciprocally scan the print area. Carriage 10
Each unit described later can be mounted on the unit 1. That is, an inkjet head 103 that ejects ink and a processing liquid for each of a plurality of colors, and an ink jet unit 103 that includes an ink tank for supplying the ink or the processing liquid to each inkjet head is mounted. For example, as a plurality of color inks, black (B
k), cyan (C), magenta (M), yellow (Y)
Can be used.

At the left end of the area where the carriage 101 can move, a recovery system unit 110 having a wiping mechanism and the like described below is provided below the area, and the ejection port of each ink jet head is capped when printing is not performed. Etc. become possible. This left end position is called the home position of each ink jet head.

Reference numeral 107 denotes a switch section and a display element section.
The switch unit is used for turning on / off the power of the ink jet printing apparatus, setting various print modes, and the like, and the display element unit is for displaying various states of the printing apparatus.

The treatment liquid for insolubilizing the ink dye can be obtained, for example, as follows.

That is, after mixing and dissolving the following components,
Further, after pressure filtration with a membrane filter having a pore size of 0.22 μm (trade name: Fluoropore filter, manufactured by Sumitomo Electric Industries, Ltd.), the pH may be adjusted to 4.8 with NaOH to obtain a treatment liquid Al. it can.

[Al component] Low molecular component of cationic compound Stearyl trimethyl ammonium salt 2.0 parts (trade name: Electrostripper QE, manufactured by Kao Corporation) or stearyl trimethyl ammonium chloride (trade name: Utamine 86P, Kao Corporation) Co., Ltd. Polymer of cationic compound Copolymer of diallylamine hydrochloride and sulfur dioxide 3.0 parts (average molecular weight: 5000) (Brand name: polyamine sulfone PAS-92, Nitto Boseki Co., Ltd.) Thiodi Glycol 10 parts Water balance The following may be mentioned as suitable examples of the ink that is insolubilized by mixing with the treatment liquid.

That is, the following components were mixed, and the mixture was filtered under pressure with a membrane filter (trade name: Fluoropore filter, manufactured by Sumitomo Electric Industries, Ltd.) having a pore size of 0.22 μm, and yellow, magenta, cyan and black were used. Inks Y1, M1, C1, and K1 can be obtained.

Y1 C.I. I. Direct Yellow 142 2 parts Thiodiglycol 10 parts Acetyleneol EH 0.05 parts (manufactured by Kawaken Fine Chemical Co., Ltd.) Water balance M1 I. Acid Red 289; C1 dye having the same composition as Y1 except that 2.5 parts is replaced with C.I. I. Acid Blue 9; Same composition as Y1 except that 2.5 parts were used. I. Food Black 2: Same composition as Y1 except that 3 parts are replaced. In the mixing of the above-described processing liquid (liquid composition) and ink, in the present invention, the above-described processing liquid and ink are applied on the printing material or on the printing material. As a result of mixing at the position where the ink has penetrated into the printing material, as a first step of the reaction, the low molecular weight component or the cationic oligomer contained in the treatment liquid and the anionic group used in the ink are used. The water-soluble dye has an association due to ionic interaction and instantaneously separates from the solution phase.

Next, in the second step of the reaction, the above-mentioned dye and the association product of the low molecular weight cationic substance or the cationic oligomer are adsorbed by the polymer component contained in the treatment liquid, so that the association occurs. The size of the dye agglomerates further increases, making it difficult for the dye aggregates to enter the gaps between the fibers of the print material, and as a result, only the liquid portion that has undergone solid-liquid separation will soak into the recording paper, thus improving print quality and fixability The compatibility of both is achieved. At the same time, the aggregate formed by the low molecular weight component of the cationic substance or the cationic oligomer and the anionic dye formed by the mechanism described above increases in viscosity and does not move with the movement of the liquid medium, so that a full-color image is obtained. Even when adjacent ink dots are formed of different color inks as in the case of formation, they do not mix with each other, and bleeding does not occur. Also, the agglomerates are essentially water-insoluble and the formed images have perfect water resistance.
Further, it also has an effect of improving the light fastness of an image formed by the shielding effect of the polymer.

As used herein, the term "insolubilization" or "aggregation" means the phenomenon of only the first step or the phenomenon including both the first step and the second step.

In practicing the present invention, it is not necessary to use a cationic polymer substance having a large molecular weight or a polyvalent metal salt as in the prior art, or even if it is necessary to use a high-molecular weight metal salt, the present invention may be applied. Since it is only necessary to use it supplementarily to further improve the effect, the amount of use can be minimized. As a result, there is no decrease in the coloring property of the dye, which is a problem when trying to obtain the water resistance effect by using the conventional cationic polymer substance or polyvalent metal salt. Can be listed as the effect of.

The material to be printed used in carrying out the present invention is not particularly limited, and so-called plain paper such as copy paper and bond paper which have been conventionally used can be suitably used. Of course, a coated paper specially prepared for inkjet printing and a transparent film for OHP can also be suitably used, and general high-quality paper and glossy paper can also be suitably used.

FIG. 8 is a block diagram showing the control arrangement of the ink jet printing apparatus according to this embodiment.

In FIG. 8, from the host computer,
Data of characters and images to be printed (hereinafter referred to as image data) is input to the reception buffer 401 of the printing apparatus of this example. Further, data for confirming whether data is correctly transferred and data for notifying an operation state of the printing apparatus are transferred from the printing apparatus to the host computer. The image data held in the reception buffer 401 is C
Transferred to the memory unit 403 under the management of the PU 402,
It is temporarily stored in the RAM (random access memory). The mechanical control unit 404 drives a mechanical unit 405 such as a carriage motor or a line feed motor according to a command from the CPU 402. The sensor / SW control unit 406 transfers signals from the sensor / SW unit 407 including various sensors and SWs (switches) to the CPU 402. The display element control unit 408 is the CPU 40.
The display element unit 409 including the LEDs and the liquid crystal display elements of the display panel group is controlled by the instruction from the control unit 2. The head control unit 410 controls the driving of each inkjet head 200 according to a command from the CPU 402. Further, the head control unit 410 is provided with the inkjet head 20.
Regarding the state of 0, temperature information detected by a sensor (not shown) is transmitted to the CPU 402.

FIG. 9 is a perspective view showing the head unit 102 of this embodiment, and FIG. 10 is a view showing a state in which the head unit 102 is performing a printing operation. Incidentally, in these drawings, the illustration of the head unit 102 for the Y, M and C inks is omitted.

As shown in these figures, in this embodiment, the ejection ports 206 are arranged in two rows in each ink jet head.
Rows, and the ejection port arrangement of each column is 1 / of the ejection port pitch.
It is assumed to be shifted by 2. Thereby, printing with a resolution twice as high as that which can be realized when the ejection port arrangement is one row can be performed.

The cover plate 208 covers the ejection port surface 205 excluding the peripheral portions of the two ejection port arrays. As a result, as described with reference to FIGS. 5 and 6, it is possible to control the mist adhesion range by the air flow generated by the carriage movement. In the present embodiment and the examples described with reference to FIGS. 5 and 6, the case where the printing operation is performed in only one direction has been described, but it is possible to effectively control the adhesion range even in so-called bidirectional printing. Of course.

In FIGS. 9 and 10, ink passages are provided so as to communicate with the ejection openings of the ink jet heads 200BK1, 200S, 200BK2, and electrothermal conversion elements for generating thermal energy in the ink passages. Are formed. The contact pad 210A provided on the wiring board 210 is used to make electrical contact between the inkjet head and the apparatus main body.

The cover plate 208 is made of stainless steel (S
A plate made of US) is attached to the ejection port surface with an adhesive. The inkjet head of each color is fixed by a supporting member 209. Then, to print one pixel, the heads 200BK2, 200S,
The ink is ejected in the order of 200BK1, that is, the black ink, the treatment liquid, and the black ink in this order.

In this embodiment, the cover plate 20
8 has a thickness of 0.3 mm, the opening of the cover plate 208 has a length of 2.5 mm in the x direction and a length of 18 in the y direction.
mm, and the three openings shown have the same dimensions. Also, the entire cover plate is 40 mm in the x direction in the figure, and y
The direction is 20 mm, and the plate width in the x direction between the heads is 10.2 mm. Further, it is desirable that the edge of the opening is substantially vertical.

Each ink jet head has a volume of ejected droplets of 8.5 pl, an ejection speed of 18 m / s, and one ejection port is arranged at a resolution of 300 dpi. The distance from the ejection port to the paper 106 is 1.3 mm. Furthermore, the drive frequency of each head is 10 kHz, and the print resolution is 1200 dpi.

In FIG. 10, the carriage advances in the direction of the arrow at a speed of 211.7 m / s, whereby the relative air flow between the carriage and the paper in the direction opposite to the carriage advancing direction. Flow occurs. With such a configuration, as a result of printing at 600 dpi × 1200 dpi, as a result, the rebounding mist from the paper surface adheres to the ejection opening surface of each head as shown in FIG. 11, and the amount of mist adhesion near the ejection opening is reduced. I was able to.

Further, when the ink jet head is removed from the main body of the printing apparatus and placed on a flat surface such as a desk, in the conventional case, the ejection opening portion directly contacts the flat surface portion and is damaged. There was something that happened. However, according to the present embodiment, the provision of the cover plate can prevent the ejection port portion from directly contacting the flat surface portion.

In this embodiment, a SUS plate is used as the cover plate, but the cover plate is not limited to this, and a metal such as aluminum or a resin material such as Noryl, PP or polyethylene may be used.

Further, the cover plate and the ink jet head may be integrally formed instead of being formed separately, and in this case, the same effect can be obtained.

Furthermore, in the present embodiment, three ink jet heads are supported by one supporting member, but even if one ink jet head is supported by one supporting member, a cover plate, etc. It has been clarified by examination that the same effect can be obtained if the condition of 1 is within the following range.

That is, the ink ejection amount is 5 to 25 pl, the ejection speed is 8 to 25 m / s, the distance between the head and the paper is 0.
5 to 20 mm, plate thickness 0.1 to 1.0 mm, plate opening x-direction length 1.0 to 6.0 mm, x-direction plate width 1.0 mm or more, carriage speed 50 mm
/ S or more, preferably 100 mm / s or more. Under the above conditions, preferably, the momentum when ejected from the head is about 25 pl or less for the droplet,
It is 400 pl · m / sec or less.

(Embodiment 2) This embodiment is different from Embodiment 1 only in the plate. That is,
As shown in FIG. 12, the cover plates at both ends of each head in the ejection port arrangement direction are removed.

In the ink jet head, ink droplets or the like adhere to the ejection port surface during printing due to rebound mist and other causes. Although such deposits are removed by wiping, this embodiment improves the wiping property by improving the blade passing property.

The head of this embodiment has a discharge volume of 17 pl,
The ejection speed is 15 m / s, and the ejection ports are arranged in two rows with a resolution of 300 dpi per row. The distance from the ejection port to the paper is 1.6 mm, the drive frequency of each head is 10 kHz, and the print resolution is 600 dpi.

Also in this example, as shown in FIG. 11, the amount of mist adhering to the vicinity of the discharge port could be reduced.

(Embodiment 3) Also in this embodiment, only the cover plate structure is different from the above-described Embodiment 1.
FIG. 13 is a diagram showing the cover plate of this embodiment.

As shown in the figure, the cover plate 208 is provided only around the ejection port array of the head BK1. The cover plate has a thickness of 0.25 mm, the cover plate opening has a length in the x direction of 4.0 mm, and a length in the y direction of 20 mm. Also, the entire plate is 18.5 mm in the x direction and y
The direction is 20 mm.

The ejection volume of each ink jet head was 4 pl, the ejection speed was 22 m / s, and the ejection ports were 3 in one row.
They are arranged in two columns with a resolution of 00 dpi. The distance between the ejection port and the paper is 1.0 mm. The drive frequency of each head is 15 kHz, and the print resolution is 120
0 dpi, that is, the carriage speed is 317.5 m
m / s. Also in the apparatus of this embodiment, one-way printing is performed, and ejection is performed in the order of the heads BK2, 200S, 200BK1.

When paying attention to a certain pixel in this one-way printing, the black ink is first ejected from the ink jet head 200BK2 as described above, but the content of the rebound mist at this time is only the black ink. Therefore, in this case, the mist adhering to the head 200BK2 can be relatively easily removed by wiping without providing a cover plate around the ejection opening of the head 200BK2, and there is no fear of serious ejection failure due to insoluble matter or the like.

Next, the treatment liquid is ejected from the ink jet head 200S. In this case, as described above,
Since black ink and treatment liquid are ejected in that order, and rebound mist is generated due to that, the amount of insoluble matter contained in the adhering mist is small, and the treatment liquid incorporates this insoluble matter inside. ing. Therefore, in this case as well, there is little possibility of causing a serious ejection failure as well.

Finally, the ink jet head 200BK1
In the case of 1, the black ink is ejected to the treatment liquid ejected immediately before, and in this case, a rebound mist containing a large amount of insoluble matter is generated. Therefore, the cover plate 208
And the range of mist adhesion is controlled by this.

Although the example shown in FIG. 13 is the case of unidirectional printing, in the case of bidirectional printing, as shown in FIG. 14, ink jet heads 200BK1 and 2BK are used.
A cover plate may be provided around each ejection port of 00BK2.

(Fourth Embodiment) FIG. 15 is a perspective view showing an ink jet head according to a fourth embodiment of the present invention.

The ink jet head of this embodiment is A4 size.
220mm, which is almost the same as the length of the size paper
The ejection ports are arranged in the width of. This inkjet head is of a so-called full line type and is used in a state of being fixed to the apparatus main body, and the paper is conveyed relative to this.

In this embodiment, the cover plate has a thickness of 0.4 mm, the cover plate opening has a length of 6.0 mm in the x direction and a length of 240 mm in the y direction. The overall size of the plate is 14 mm in the x direction and 26 mm in the y direction.
It is 0 mm.

The ejection volume of the ink jet head is 17 pl, the ejection speed is 24 m / s, and the ejection ports are arranged at a resolution of 600 dpi. The distance between the ejection port and the paper is 1.2 mm. Further, the driving frequency is 1 kHz and the print resolution is 600 dpi.
That is, the sheet conveyance speed is 42.3 mm / s.

In the apparatus according to the present embodiment, since the air flow generated between the ink jet head and the paper is due to the transportation of the paper, the speed thereof is relatively small, and the range of the rebound mist to be attached is reduced. Not enough to control. Therefore, as shown in FIG. 16, a fan 220 is provided in order to generate a sufficient speed of air flow between the inkjet head 200 and the paper 106.

That is, in this embodiment, the fan 220 and the motor 221 for driving the fan 220 are provided, and the flow generated by this is guided by the guide 223 to generate an air flow of about 100 mm / s. It was possible to reduce the amount of mist adhering near the discharge port by controlling the adhering range of No.

Even in the case of a head mounted in an apparatus for printing by scanning with a carriage as shown in FIG. 7, there is a case where an air flow of a sufficient speed does not occur when recording with high resolution. . For example, when printing is performed at a drive frequency of 8 kHz with a resolution of 4800 dpi to improve the density, the carriage speed is 42.3.
mm / s, which is not sufficient to generate an air flow. In that case, a flow of air can be generated by providing a fan as in this embodiment.

(Embodiment 5) FIG. 17 is a perspective view showing a head unit according to a fifth embodiment of the present invention.

As shown in the figure, in this embodiment, instead of using a cover plate for preventing the adhesion of rebounding mist and the like to control the mist adhering range, the periphery of the ejection port array region of each ink jet head is controlled. The convex portion 230 is provided on. This protrusion has a width of 1.0 mm and a height of 0.
3 mm. Even with such a configuration, the airflow as shown in FIGS. 5 and 6 is generated, and the mist adhesion range can be controlled.

In carrying out the present invention, the ink to be used is not particularly limited to the dye ink, a pigment ink in which a pigment is dispersed may be used, and the treatment liquid to be used is one that causes the pigment to aggregate. Can be used. The following can be mentioned as an example of the pigment ink which causes aggregation by mixing with the above-mentioned colorless liquid A1. That is, as described below, yellow, magenta,
Cyan and black inks Y2, M2, C2 and K2 can be obtained.

Black ink K2 anionic polymer P-1 (styrene-methacrylic acid-ethyl acrylate, acid value 400, weight average molecular weight 6,0
00, an aqueous solution having a solid content of 20%, a neutralizing agent: potassium hydroxide) as a dispersant, the following materials were charged into a batch-type vertical sand mill (manufactured by Imex), and glass beads having a diameter of 1 mm were filled as a medium. The dispersion treatment was performed for 3 hours while cooling with water. The viscosity after dispersion was 9 cps and the pH was 10.0. The dispersion was centrifuged to remove coarse particles, thereby producing a carbon black dispersion having a weight average particle diameter of 100 nm.

(Composition of carbon black dispersion) -P-1 aqueous solution (solid content 20%) 40 parts-Carbon black Mogul L (manufactured by Cablack) 24 parts-Glycerin 15 parts-Ethylene glycol monobutyl ether 0.5 parts- Isopropyl alcohol 3 parts water 135 parts Next, the dispersion obtained above was sufficiently dispersed to obtain a black ink K2 for ink jet containing a pigment. The solids content of the final preparation was about 10%.

Yellow ink Y2 anionic polymer P-2 (styrene-acrylic acid-methyl methacrylate, acid value 280, weight average molecular weight 1
1,000, an aqueous solution having a solid content of 20%, and a neutralizing agent: diethanolamine) as a dispersant, and using the materials described below, a dispersion treatment was performed in the same manner as in the preparation of the black ink K2, and the weight average particle size A 103 nm yellow dispersion was prepared.

(Composition of yellow dispersion) P-2 aqueous solution (solid content 20%) 35 parts C.I. I. Pigment Yellow 180 24 parts (Nova Palm Yellow PH-G, manufactured by Hoechst) Triethylene glycol 10 parts Diethylene glycol 10 parts Ethylene glycol monobutyl ether 1.0 part Isopropyl alcohol 0.5 part Water 135 parts Obtained above The yellow dispersion thus obtained was sufficiently diffused to obtain an inkjet yellow ink Y2 containing a pigment. The solids content of the final preparation was about 10%.

Cyan Ink C2 Using the anionic polymer P-1 used in the preparation of the black ink K2 as a dispersant, the following materials were used, and the same dispersion treatment as in the case of the carbon black dispersion described above was performed. Then, a cyan color dispersion having a weight average particle diameter of 120 nm was produced.

(Composition of cyan color dispersion) P-1 aqueous solution (solid content 20%) 30 parts C.I. I. Pigment Blue 15: 3 24 parts (Fast Genble-FGF, Dainippon Ink and Chemicals) ・ Glycerin 15 parts ・ Diethylene glycol monobutyl ether 0.5 parts ・ Isopropyl alcohol 3 parts ・ Water 135 parts Cyan color dispersion obtained above Was sufficiently stirred to obtain a cyan ink C2 for inkjet containing a pigment. The solids content of the final preparation was about 9.6%.

Magenta Ink M2 Using the anionic polymer P-1 used in the preparation of the black ink K2 as a dispersant, the following materials were used, and the same dispersion treatment as in the case of the carbon black dispersion described above was performed. Then, a magenta color dispersion having a weight average particle diameter of 115 nm was produced.

(Composition of magenta color dispersion) P-1 aqueous solution (solid content 20%) 20 parts C.I. I. Pigment Red 122 (Dainippon Ink and Chemicals) 24 parts ・ Glycerin 15 parts ・ Isopropyl alcohol 3 parts ・ Water 135 parts The magenta color dispersion obtained above is sufficiently diffused to contain a pigment-containing magenta ink for inkjet. M2
I got The solids content of the final preparation was about 9.2%.

[0101]

As is apparent from the above description, according to the present invention, the mist generated along with the liquid ejection from the head can be moved in the direction away from the ejection port by the air flow. It is possible to prevent mist from adhering to the ejection port and causing ejection failure. Further, since the mist can be in a suspended state, that is, can be easily controlled by the air flow, it is possible to easily control the range in which the mist adheres.

As a result, the amount of mist adhering to the discharge port or its vicinity can be reduced, and serious discharge defects can be prevented.

[Brief description of drawings]

FIG. 1A to FIG. 1C are diagrams illustrating generation of a rebound mist.

2A to 2C are diagrams illustrating generation of a rebound mist.

FIG. 3 is a diagram illustrating an example of the behavior of a bounce mist.

FIG. 4 is a diagram illustrating another example of the behavior of the spring return mist.

FIG. 5 is a diagram illustrating an example of the control of the range of adhesion of the bounce mist according to the present invention.

FIG. 6 is a diagram for explaining another example of the control of the attachment range of the bounce mist according to the present invention.

FIG. 7 is a perspective view showing an inkjet printing apparatus according to an embodiment of the present invention.

FIG. 8 is a block diagram showing a control configuration of the inkjet printing apparatus.

FIG. 9 is a perspective view showing the head unit according to the first embodiment of the present invention.

FIG. 10 is a top view showing a state of the head unit during a printing operation.

FIG. 11 is a diagram illustrating a control result of a mist adhesion range according to the first embodiment.

FIG. 12 is a perspective view showing a head unit according to a second embodiment of the invention.

FIG. 13 is a perspective view showing a head unit according to a third embodiment of the present invention.

FIG. 14 is a perspective view showing a head unit according to a modification of the third embodiment.

FIG. 15 is a perspective view showing a head unit according to a fourth embodiment of the present invention.

FIG. 16 is a diagram showing a configuration for forcibly generating an air flow in the fourth embodiment.

FIG. 17 is a perspective view showing a head unit according to a fifth embodiment of the present invention.

[Explanation of symbols]

2,106 Print medium (paper) 5,200,200BK, 200BK 1,200BK
2,200S, 200YMC Inkjet head 5A, 205 Discharge port surface 6,208 Discharge port 7 Bounce mist 8,208 Cover plate (covering member) 101 Carriage 110 Recovery unit 230 Convex part

Claims (19)

[Claims] 1. A moving means for moving an ejecting means provided with an ejection port for ejecting liquid relative to a medium, and a relative movement of the ejecting means and the medium by the moving means. Air flow generating means for generating an air flow in a direction away from the discharge port in a space in the vicinity of the discharge port surface of the discharge unit in which the discharge port is arranged, A liquid ejecting device. 2. The liquid ejecting apparatus according to claim 1, wherein the air flow generating means is a convex portion provided on the ejecting means alongside the ejection port along the movement direction. 3. The liquid ejecting apparatus according to claim 2, wherein the convex portion is a cover plate provided around the ejection port. 4. The height of the protrusion is 0.1 mm or more and 1.0.
The liquid ejecting apparatus according to claim 2, wherein the liquid ejecting apparatus has a diameter of not more than mm. 5. The liquid ejecting apparatus according to claim 2, wherein a cross-sectional shape of the convex portion along the moving direction is a rectangle. 6. The distance between the ejection port and the medium is 0.5.
The liquid ejecting apparatus according to claim 1, wherein the liquid ejecting apparatus has a size of not less than 2.0 mm and not more than 2.0 mm. 7. The moving speed of the moving means is 50 mm / s.
The liquid ejection device according to claim 1, wherein the liquid ejection device has a thickness of ec or more. 8. The amount of liquid discharged from the discharge port is 25 p
It is 1 or less, The liquid ejection apparatus in any one of Claims 1-7 characterized by the above-mentioned. 9. The liquid ejection apparatus according to claim 8, wherein the momentum of the liquid ejected from the ejection port is 400 pl · m / sec or less. 10. The liquid ejection apparatus according to claim 1, wherein the ejection means is provided with a plurality of the ejection ports. 11. The liquid ejection apparatus according to claim 10, wherein a plurality of the ejection ports are provided along a direction intersecting with the movement direction. 12. The ejecting means has an ink ejecting section for ejecting ink and a treatment liquid ejecting section for ejecting a treatment liquid for insolubilizing the ink.
A liquid ejection device according to claim 1. 13. The liquid ejection apparatus according to claim 1, wherein the ejection unit has an electrothermal converter as an energy generation unit that generates energy for ejecting the liquid. 14. The liquid ejecting apparatus according to claim 1, wherein the ejecting unit has a piezoelectric element as an energy generating unit that generates energy for ejecting the liquid. 15. A liquid ejecting method in which ejecting means provided with an ejecting port for ejecting liquid moves relative to a medium to eject liquid from the ejecting port onto the medium, the ejecting means and the medium. And a liquid flow that is generated by utilizing the relative movement of the liquid in the space near the discharge port surface of the discharge means in which the discharge port is arranged, in a direction away from the discharge port. A liquid ejecting method, which comprises ejecting. 16. A liquid ejecting method in which an ejecting unit provided with an ejecting port for ejecting liquid moves relative to a medium to eject liquid from the ejecting port to the medium, the ejecting unit and the medium. And the air flow generated by utilizing the relative movement of the ejection unit and the medium while suspending the liquid between the ejection port and the ejection port surface of the ejection unit in which the ejection port is arranged. A liquid ejecting method comprising ejecting a liquid while generating an air flow in a direction away from the ejection port in a nearby space. 17. A liquid ejecting apparatus for ejecting a liquid to a medium by using an ejecting means provided with an ejecting port for ejecting a liquid, wherein the ejecting means is provided with a convex portion, and the convex portion and the air flow generation A liquid ejecting apparatus, which generates an air flow in a direction away from the ejection port in a space near the ejection port surface of the ejection unit in which the ejection port is arranged by the air flow generated by the device. 18. The liquid ejecting apparatus according to claim 17, wherein the airflow generating means has a fan and generates the airflow by the fan. 19. A droplet of a volume of 25 pl or less is ejected from the ejection means at a momentum of 400 pl · m / sec or less, and a mist generated by collision with a medium or a liquid on the medium is generated between the ejection means and the medium. A method of ejecting a liquid, comprising a step of floating in a space.