Droplet ejection apparatus, method of suppressing liquid aggregation in droplet ejection apparatus, and program

Abstract

Provided is a droplet ejection apparatus that includes a droplet ejection section which ejects droplets from nozzles. The droplet ejection section includes a first head for ejecting a first liquid and a second head for ejecting a second liquid for aggregation of the first liquid. An ejection speed of the second head is lower than an ejection speed of the first head.

Description

BACKGROUND OF THE INVENTIONTechnical Field

[0001] The present invention relates to a droplet ejection apparatus, a method of suppressing liquid aggregation in a droplet ejection apparatus, and a program.Description of Related Art

[0002] Conventionally, there has been known a droplet ejection apparatus which ejects a first liquid from a nozzle provided on a nozzle face of a head. In addition, as a droplet ejection apparatus, a configuration in which a second liquid for aggregating the first liquid is ejected in-line from the head is known.

[0003] In such a droplet ejection apparatus, if mist of one of the liquids adheres to the nozzle face of the head that ejects the other liquid, an aggregate is formed on the nozzle face. In particular, when the mist of the second liquid adheres to the nozzle of the first head that ejects the first liquid and causes an ejection failure of the first liquid, there is a greater effect than an ejection failure of the second liquid.

[0004] Therefore, for example, Japanese Unexamined Patent Publication No. 2018-094757 describes a configuration in which an airflow generating section is provided between the first head and the second head that ejects the second liquid to prevent the mist of the second liquid from adhering to the nozzles of the first head.SUMMARY OF THE INVENTION

[0005] According to the configuration described in Japanese Unexamined Patent Publication No. 2018-094757, it is possible to prevent the mist of the second liquid from adhering to the nozzles of the first head. However, the above-described configuration cannot suppress generation of the mist of the second liquid. Therefore, there is still a risk that the mist of the second liquid adheres to the nozzles of the first head. In addition, in the configuration described in Patent Literature 1, since the airflow generating section is provided, the size of the apparatus and the cost are increased, and the degree of freedom of arrangement of the heads is reduced.

[0006] With respect to such a problem, the inventors have conducted intensive studies and found that it is possible to suppress generation of the mist by reducing the ejection speed of droplets to a predetermined speed. However, when the ejection speed of the droplet is reduced, the influence of the air resistance increases correspondingly. This causes another problem where the landing accuracy of the first liquid is reduced.

[0007] The present invention has been made in view of such circumstances. An object of the present invention is to provide a droplet ejection apparatus, a method of suppressing liquid aggregation in a droplet ejection apparatus, and a program which are capable of suppressing both a reduction in accuracy of landing of a first liquid and generation of mist of a second liquid.

[0008] To achieve at least one of the abovementioned objects, according to an aspect of the present invention, a droplet ejection apparatus reflecting one aspect of the present invention includes: a droplet ejection section which ejects droplets from nozzles, wherein the droplet ejection section includes a first head for ejecting a first liquid and a second head for ejecting a second liquid for aggregation of the first liquid, wherein an ejection speed of the second head is lower than an ejection speed of the first head.

[0009] According to another aspect of the present invention, provided is a method of suppressing liquid aggregation in a droplet ejection apparatus, the droplet ejection apparatus including: a droplet ejection section which ejects droplets from nozzles, wherein the droplet ejection section includes a first head for ejecting a first liquid and a second head for ejecting a second liquid for aggregation of the first liquid, wherein the method includes controlling of droplet ejection of the droplet ejection section, wherein in the controlling, an ejection speed of the second head is controlled to be lower than an ejection speed of the first head.

[0010] According to another aspect of the present invention, provided is a program for a computer of a droplet ejection apparatus, the droplet ejection apparatus including: a droplet ejection section which ejects droplets from nozzles, wherein the droplet ejection section includes a first head for ejecting a first liquid and a second head for ejecting a second liquid for aggregation of the first liquid, wherein the program causes the computer to function as a controller to control droplet ejection of the droplet ejection section, wherein the controller performs control such that an ejection speed of the second head is lower than an ejection speed of the first head. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The advantages and features provided by one or more embodiments of the invention will become more fully understood from the detailed description given hereinbelow and the appended drawings which are given by way of illustration only, and thus are not intended as a definition of the limits of the present invention, wherein: Fig. 1 is a perspective view of a droplet ejection apparatus; Fig. 2 is a block diagram of the droplet ejection apparatus; Fig. 3 is a schematic front view of a carriage; Fig. 4 is a graph summarizing the relationship between an ejection speed of droplets and an amount of mist generated; Fig. 5 is a graph summarizing the relationship between the ejection speed of droplets and an amount of landing deviation; and Fig. 6 is a side view of a drop watcher. DETAILED DESCRIPTION

[0012] Hereinafter, a droplet ejection apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings. However, the scope of the invention is not limited to the illustrated examples. In the following description, components having the same function and configurations are denoted by the same reference numerals, and the description thereof will be omitted.[Overall Configuration of Inkjet Recording Apparatus]

[0013] Fig. 1 is a perspective view of an inkjet recording apparatus 1 as an embodiment of a droplet ejection device according to the present invention. Fig. 2 is a block diagram showing a functional configuration of the inkjet recording apparatus 1. The inkjet recording apparatus 1 includes a controller 2, a conveyance section 3, and a droplet ejection section 4.

[0014] In the following, an X direction, a Y direction, and a Z direction are directions shown in Fig. 1. Further, in the description below, the X direction, the Y direction, and the Z direction correspond to a width direction, a conveyance direction, and a height direction, respectively.(Controller)

[0015] The controller 2 includes a central processing unit (CPU), a random access memory (RAM), and a read only memory (ROM). Thus, the controller 2 controls the overall operation of the inkjet recording apparatus 1.

[0016] The CPU controls each part of the inkjet recording apparatus 1. The RAM is a volatile memory that temporarily stores various kinds of information in a writable and readable manner. The ROM is a non-volatile memory in which various types of information and programs are stored in a readable manner. More specifically, the controller 2 causes the CPU to read a specified program from various programs stored in the ROM and load the program into the RAM. Then, the controller 2 executes various kinds of processing in coordination with the loaded program.(Conveyance Section)

[0017] As shown in Fig. 1, the conveyance section 3 includes two conveyance rollers 3a and 3b that rotate in the conveyance direction around rotary shafts extending in the width direction. Furthermore, the conveyance section 3 includes a ring-shaped conveyance belt 3c.

[0018] The inner side of the conveyance belt 3c is supported by the conveyance rollers 3a and 3b. A recording medium M is placed on the conveyance face of the conveyance belt 3c. The conveyance rollers 3a and 3b rotate and circulate in the conveyance direction in accordance with an operation of a conveyance motor of the roller. As a result, the conveyance belt 3c conveys the recording medium M in the conveyance direction.

[0019] In addition, it is preferable that a predetermined adhesive (base agent) is applied to the placement face of the conveyance belt 3c, which is a surface different from an inner surface that comes into contact with the conveyance rollers 3a and 3b and is an outer surface on a side on which the recording medium M is placed. When the placement face is coated with an adhesive, a reduction in image quality due to the position shift of the recording medium M can be suppressed.

[0020] The recording medium M is, for example, a piece of fabric cut to a constant size. The recording medium M is supplied onto the conveyance belt 3c by a medium supply section (not illustrated). The recording medium M on which the image is recorded by the ink ejection of the droplet ejection section 4 is discharged to a predetermined discharge section. Note that the recording medium M is not limited to textile. The recording medium M may be any recording medium on which landed ink can be fixed, and may be any of various media such as paper.(Droplet Ejection Section)

[0021] The droplet ejection section 4 forms the image by ejecting color ink onto the recording medium M conveyed by the conveyance section 3 at an appropriate timing based on image data acquired from an external device or the like. The droplet ejection section 4 includes a carriage 41 on which an ink ejection unit 42 including a plurality of inkjet heads 421 to eject ink of respective colors, for example, cyan (C), magenta (M), yellow (Y), and black (K) is mounted.{ Carriage}

[0022] Fig. 3 is a schematic front view of a cross section of the carriage 41 seen from the conveyance direction. The ink ejection unit 42 and a treatment liquid ejection unit 43 are mounted on the carriage 41. The carriage 41 includes, for example, a belt bridged between two pulleys that are rotated by a motor (not illustrated). The carriage 41 causes the ink ejection unit 42 and the treatment liquid ejection unit 43 to scan in the width direction by a rotation operation of the motor based on a drive signal output by the controller 2.

[0023] In addition, the inkjet recording apparatus 1 according to the present embodiment is a serial head type (multi-pass type) inkjet recording apparatus which forms an image by discharging color ink onto the recording medium M from the ink ejection unit 42 while scanning the carriage 41 in the width direction. The image may be formed by scanning the carriage 41 once, or the image may be formed by scanning the carriage 41 a plurality of times.

[0024] In addition, the inkjet recording apparatus 1 according to the present embodiment is of an in-line type. That is, the droplet ejection section 4 performs image formation by ink ejection of the ink ejection unit 42 continuously with pretreatment by ejection of the treatment liquid of the treatment liquid ejection unit 43.{Ink Ejection Unit}

[0025] The ink ejection unit 42 includes a plurality of inkjet heads 421 to eject color ink, which is a first liquid. The inkjet heads 421 each include a tank for a color ink, a channel, an actuator, and a plurality of nozzles. The actuator is, for example, a piezoelectric element. In order to cause the ink to be ejected from the nozzle, the actuator applies pressure fluctuation to the ink in the nozzle in response to a voltage signal of a predetermined drive waveform applied from the controller 2.

[0026] As shown in Fig. 3, the plurality of inkjet heads 421 are mounted on the carriage 41 in the width direction. The inkjet heads 421 eject the color ink onto the recording medium M by the actuator applying pressure fluctuation to the color ink supplied from the tank to the nozzle via the channel under the control of the controller 2.

[0027] As the color ink ejected by the ink ejection unit 42, pigment ink containing a pigment dispersion, resin ink containing a resin, disperse dye ink in which a dye is dispersed, or the like is used.{Treatment Liquid Ejection Unit}

[0028] The treatment liquid ejection unit 43 includes a treatment liquid ejection head 431 provided at a first end portion of the carriage 41 in the width direction. The treatment liquid ejection head 431 is provided outside the ink ejection unit 42, and similarly to the inkjet heads 421, includes a tank for the treatment liquid, a channel, an actuator, and a plurality of nozzles. The treatment liquid ejection unit 43 ejects a treatment liquid, which is a second liquid, under the control of the controller 2.

[0029] In detail, the treatment liquid ejected by the treatment liquid ejection head 431 is, for example, a transparent pretreatment ink containing a coagulant, and is mixed in a liquid state with the color ink ejected by the inkjet head 421. The pretreatment ink contains at least a coagulant. The pretreatment ink may contain components such as a solvent, a surfactant, or water in addition to the aggregation agent. The coagulant contained in the pretreatment ink is not particularly limited as long as it generates an aggregate when coming into contact with the color ink. The coagulant contained in the pretreatment ink is, for example, a polyvalent metal salt, an organic acid, an inorganic acid, or a cationic polymer.

[0030] The treatment liquid ejection head 431 ejects the treatment liquid when the carriage 41 scans to the first end side (the right side in Fig. 3) where the treatment liquid ejection unit 43 is provided. According to this configuration, the pretreatment and the image formation can be performed at the same time by one time scanning of the carriage 41, which enhances productivity.

[0031] The treatment liquid ejection head 431 may be provided at both ends of the carriage 41 in the width direction. In this configuration, by ejecting the treatment liquid from the treatment liquid ejection head 431 on the front side in the scanning direction of the carriage 41, image formation processing can be performed on both the forward and return paths of the carriage 41, which enhances productivity.

[0032] The distance from the nozzles of the treatment liquid ejection head 431 to the recording medium M is preferably 1 mm or more and 6 mm or less. As the distance from the nozzles of the treatment liquid ejection heads 431 to the recording medium M is 1 mm or more, it is possible to prevent the nozzles from contacting the recording medium M. As the distance from the nozzles of the treatment liquid ejection head 431 to the recording medium M is 6 mm or less, it is possible to suppress generation of mist due to splashing up of the treatment liquid.

[0033] Hereinafter, the inkjet heads 421 and the treatment liquid ejection head 431 will be simply referred to as "heads" when no particular distinction is made therebetween.[Ejection Control]

[0034] In such an inkjet recording apparatus 1, the controller 2 controls ejection of droplets by the droplet ejection section 4. Specifically, the controller 2 controls the ejection speed of the treatment liquid from the treatment liquid ejection head 431 to be slower than the ejection speed of the ink from the inkjet heads 421.

[0035] The ejection speed of the head can be calculated by, for example, the following sequence. First, a difference Δt between the time at which a droplet reaches a recording medium M that is 500 µm ahead of the nozzle and the time at which the droplet reaches a recording medium M that is 600 µm ahead is obtained. Then, the value obtained by dividing the flying distance Δl = 100 µm by the required time Δt, which is Δl / Δt, is the ejection speed. In order to improve the measurement accuracy, it is preferable to perform the trial 10 times and calculate the average value. In addition, the ejection speed of the head can also be measured by using jetXpert, a flying droplet observation device manufactured by imageXpert Corporation, for example.

[0036] Fig. 4 is a graph summarizing the relationship between the ejection speed of droplets and the amount of mist generated; In Fig. 4, the horizontal axis represents the ejection speed, and the vertical axis represents the amount of mist generated. Fig. 5 is a graph summarizing the relationship between the ejection speed of droplets and the amount of landing deviation. In Fig. 5, the horizontal axis represents the ejection speed and the vertical axis represents the amount of landing deviation. As shown in Fig. 4, when the ejection speed of the droplets is decreased, the amount of generated mist decreases. On the other hand, as shown in Fig. 5, when the ejection speed of droplets is decreased, the influence of the air resistance increases, and the amount of landing deviation increases.

[0037] Therefore, in the inkjet recording apparatus 1 according to the present embodiment, the controller 2 reduces only the ejection speed of the treatment liquid ejection head 431. Then, as generation of mist of the treatment liquid is suppressed, it is possible to suppress nozzle clogging due to attachment and aggregation of mist of the treatment liquid to the nozzles of the inkjet head 421. Furthermore, as described above, since the treatment liquid is colorless and transparent, the landing deviation caused by the reduction of the ejection speed of the treatment liquid ejection head 431 does not affect the quality of the image to be formed. In addition, since the ejection speed of the inkjet head 421 is as conventional, it is also possible to suppress the occurrence of image disturbance.

[0038] To be specific, the controller 2 controls the ejection speed of the treatment liquid ejection head 431 to be slower than the ejection speed of the inkjet head 421 by 0.5 m / s or more. When the ejection speed of the treatment liquid from the treatment liquid ejection head 431 is made slower than the ejection speed of the ink from the inkjet head 421 by 0.5 m / s or more, it is possible to obtain a sufficient effect of suppressing generation of mist of the treatment liquid.

[0039] On the other hand, the controller 2 controls the ejection speed of the treatment liquid ejection head 431 to be 4.0 m / s or more. This is because if the ejection speed of the treatment liquid of the treatment liquid ejection head 431 is less than 4.0 m / s, the influence of air resistance increases, and conversely, mist is more likely to be generated.

[0040] The controller 2 also controls the ejection speed of the inkjet head 421 and the treatment liquid ejection head 431 to be 10.0 m / s or less. This is because even if the ejection speed is set to 10.0 m / s or more, the effect of suppressing the landing deviation is not further increased. In addition, when the ejection speed is set to 10.0 m / s or more, the number of satellites (minute droplets) in a droplet increases. This is because the amount of mist increases when the satellites are affected by air resistance.(Ejection Speed Reduction Method)

[0041] As a method of reducing the ejection speed of the treatment liquid ejection head 431 by the controller 2, an appropriate known method can be adopted. For example, the controller 2 can reduce the ejection speed of the treatment liquid ejection head 431 by causing the voltage to be applied to the actuator of the treatment liquid ejection head 431 to be smaller than the voltage to be applied to the actuator of the inkjet head 421.

[0042] Alternatively, the controller 2 can reduce the ejection speed of the treatment liquid ejection head 431 by causing the drive waveform of the voltage signal to be applied to the actuator of the treatment liquid ejection head 431 to be different from the drive waveform of the voltage signal to be applied to the actuator of the inkjet head 421.

[0043] Alternatively, the controller 2 can reduce the ejection speed of the treatment liquid ejection head 431 by performing control such that the viscosity of the treatment liquid is higher than the viscosity of the ink. Specifically, the controller 2 can cause the viscosity of the treatment liquid to be higher than the viscosity of the ink by performing control such that the temperature of the treatment liquid is lower than the temperature of the ink. Alternatively, the controller 2 can cause the viscosity of the treatment liquid to be higher than the viscosity of the ink by making the components of the treatment liquid different from the components of the ink.

[0044] The viscosity range of the treatment liquid and the ink is preferably 2 cp or more and 10 cp or less. When the viscosities of the treatment liquid and the ink are within the above range, sufficient ejection stability from a head is obtained.[Examples]

[0045] Next, with respect to examples and comparative examples of the present invention, the results of evaluating preferred configurations by various tests will be described. Hereinafter, the present invention will be specifically described with reference to example, but the present invention is not limited thereto.[Test 1. Evaluation of Amount of Scattering Mist]

[0046] The treatment liquid ejection head 431 for ejecting a treatment liquid colored with a cation pigment and a dummy head with paper attached to a nozzle face are arranged in the conveyance direction with a gap of 3 mm therebetween. Then, the treatment liquid was continuously ejected for one minute at a predetermined ejection speed toward a cloth away from the nozzle face of the treatment liquid ejection head 431 by 1 mm, and the number of minute liquid droplets adhering to the paper on the nozzle face of the dummy head was evaluated. The test results were evaluated as "Not Good" when the number of minute droplets adhering to the paper was 100 or more, and as "Good" when the number was less than 100.[Test 2. Evaluation of Landing Position Deviation]

[0047] A thin line pattern was printed on a cloth separated from a nozzle face by 1 mm at a predetermined ejection speed by the treatment liquid ejection head 431 for ejecting a treatment liquid colored with a cation pigment, and the amount of deviation of the landing position was evaluated. When the deviation amount was less than 35 mm and was also allowable in the ink, the test result was evaluated as A, when the deviation amount was 35 mm or more and less than 75 mm and was allowable in the treatment liquid, the test result was evaluated as B, and when the deviation amount was 75 mm or more and was not allowable in the treatment liquid, the test result was evaluated as C.

[0048] The formulations of the treatment liquids used in Tests 1 and 2 were as in Table I below.[Table 1]

[0049] Table IComponentsRatio (%)Cationic Dispersed Pigment (solid content)0.5Coagulant (MPT-60)5.0Propylene Glycol20.0Glycerin10.0Water64.5

[0050] The results of Tests 1 and 2 were as in Table II.[Table 2]

[0051] Table IIEjection Speed (m / s)Test 1Test 27.0Not GoodA6.5Not GoodA6.0Not GoodA5.5GoodB5.0GoodB4.5GoodB4.0GoodB3.5Not GoodC

[0052] As shown in Table II, generation of mist is suppressed when the ejection speed is in a range of 4.0 to 5.5 m / s. In contrast, print deviation is suppressed as the ejection speed increases. Then, in the case of the treatment liquid, print deviation is allowed if it is B or more. Therefore, the ejection speed of the treatment liquid is preferably 4.0 to 5.5 m / s.[Effects of First Embodiment]

[0053] As described above, the inkjet recording apparatus 1 according to the present embodiment includes the droplet ejection section 4 that ejects droplets from nozzles, and the controller 2 that controls the droplet discharge of the droplet ejection section 4. In addition, the droplet ejection section 4 includes the inkjet head 421 which is the first head that ejects ink which is the first liquid, and the treatment liquid head 431 which is the second head that ejects the treatment liquid which is the second liquid that causes aggregation of the ink which is the first liquid. Then, the controller 2 performs control such that the ejection speed of the treatment liquid head 431 which is the second head is slower than the ejection speed of the inkjet head 421 which is the first head.

[0054] According to this configuration, generation of mist of the treatment liquid can be suppressed. Therefore, nozzle clogging due to adhesion of mist of the treatment liquid to the nozzle face of the inkjet head 421 can be suppressed. In addition, since the ejection speed of the inkjet head 421 is not reduced, the landing accuracy is not reduced. Therefore, occurrence of image disturbance can also be suppressed.[Other Configurations]

[0055] Although specific description has been given above based on the embodiment according to the present invention, the present invention is not limited to the above-described embodiment. It is a matter of course that the present invention can be subjected to various modifications within the scope of the invention described in the claims and the equivalents thereof.

[0056] For example, in the above description, the inkjet recording apparatus 1 including the droplet ejection section 4 in which the first liquid is ink and the second liquid is the treatment liquid is the droplet ejection apparatus, but the invention is not limited thereto. That is, the above-described configurations of the present invention can be arbitrarily applied as long as the droplet ejection apparatus ejects the first liquid and the second liquid for aggregation the first liquid.

[0057] In the above description, the droplet ejection section 4 is of a serial head type in which the ink ejection unit 42 and the treatment liquid ejection unit 43 are mounted on one carriage 41, but the invention is not limited thereto. That is, the configuration of the present invention is applicable to the inkjet recording apparatus 1 including the droplet ejection section 4 of the line head type (one-pass type), in which the ink ejection unit 42 and the treatment liquid ejection unit 43 are disposed consecutively in the conveyance direction.

[0058] Furthermore, as described above, the number of satellites in droplet ejected from the head greatly contributes to the amount of generated mist. Therefore, the controller 2 may control the drive waveform such that the number of satellites in droplet ejected by the treatment liquid ejection head 431 is smaller than the number of satellites in droplet ejected by the inkjet head 421. In the above-described configuration, the controller 2 functions as an acquirer that acquires the number of satellites in a droplet ejected from the head.

[0059] To be specific, for example, as shown in Fig. 6, a drop watcher including a trigger camera and a lens D1, and a strobe camera D2 is provided below the head of the conveyance section 3 such that they face each other in the width direction. In this structure, the trigger camera is focused on a droplet, and then the strobe is disposed at a position facing each head in the XY plan view. Then, at the time of ejection of a droplet, the strobe is flashed at the moment of 400 to 600 ns so that satellites of a flying droplet can be measured. Then, the controller 2 acquires the imaging results by the drop watcher a plurality of times for a plurality of nozzles and adjusts the drive waveform on the basis of the average value of the satellites of the droplets.

[0060] More specifically, the controller 2 counts the number of satellites at the time point when the tenth leading droplet of the droplets ejected ten consecutive times by the head is at a position of 500 µm from the nozzle. The controller 2 then controls the drive waveform to be applied to the inkjet heads 421 and the treatment liquid ejection head 431 such that the average value of the satellites of the treatment liquid is less than the average value of the satellites of the ink. In particular, the controller 2 preferably controls the drive waveform such that the number of satellites of the treatment liquid is less than or equal to half the number of satellites of the ink.

[0061] Further, when the controller 2 decreases only the ejection speed of the treatment liquid ejection head 431, the application amount of the treatment liquid decreases, and thus the amount of the treatment liquid applied to the recording medium M may be insufficient. Therefore, the controller 2 may suppress a decrease in the application amount of the treatment liquid by causing the ejection frequency of the treatment liquid ejection head 431 to be higher than the ejection frequency of the inkjet head 421. Alternatively, a decrease in the amount of the treatment liquid to be applied may be suppressed by making the number of the treatment liquid ejection head units 431 mounted on the carriage 41 greater than the number of the inkjet heads 421 of any one color in the ink ejection unit 42.

[0062] Furthermore, if the controller 2 decreases only the ejection speed of the treatment liquid ejection head 431, there is a risk that the landing positions of the ink and the treatment liquid will deviate at the edges of the recording medium M. Therefore, the controller 2 may align the landing positions by causing the inkjet head 421 and the treatment liquid ejection head 431 to eject the droplets at different timings. The ejection timings of the treatment liquid ejection head 431 and the inkjet head 421 can be appropriately calculated from, for example, a printing gap based on the thickness of the recording medium M.

[0063] In addition, the controller 2 may control not only the ejection speed of the heads but also the amount of droplet to be ejected. To be specific, the controller 2 preferably controls the liquid amount of a droplet ejected from the nozzles to be in a range of 4 pL to 30 pL. When the temperature is controlled to be within the above range, the droplets are less likely to be influenced by air resistance, and generation of mist can be suppressed.

[0064] In addition, in the above description, the controller 2 controls the ejection speed and the like of the inkjet head 421 and the treatment liquid ejection head 431, but the invention is not limited thereto. That is, even in a case where the ejection speed cannot be controlled (changed) by the controller 2, for example, if the ejection speed of the treatment liquid ejection head 431 is defined in advance to be slower than the ejection speed of the inkjet head 421, the configuration of the present invention can be applied.

[0065] In the above description, an example in which a hard disk, a semiconductor non-volatile memory, or the like is used as a computer-readable medium for the program according to the present invention has been disclosed, but the medium is not limited to this example. As another computer-readable medium, a portable recording medium such as a CD-ROM can be applied. Furthermore, a carrier wave is also applied as a medium for providing data of the program according to the present invention via a communication line.

[0066] Although embodiments of the present invention have been described and shown in detail, the disclosed embodiments are made for purposes of illustration and example only and not limitation. The scope of the present invention should be interpreted by terms of the appended claims.

[0067] The entire disclosure of Japanese Patent Application No. 2024-094772 filed on June 12, 2024, is incorporated herein by reference in its entirety.

Claims

1. A droplet ejection apparatus comprising: a droplet ejection section which ejects droplets from nozzles, wherein the droplet ejection section includes a first head for ejecting a first liquid and a second head for ejecting a second liquid for aggregation of the first liquid, wherein an ejection speed of the second head is lower than an ejection speed of the first head.

2. The droplet ejection apparatus according to claim 1, wherein the ejection speed of the second head is equal to or higher than 4.0 m / s and is lower than the ejection speed of the first head by 0.5 m / s or more.

3. The droplet ejection apparatus according to claim 1, wherein the ejection speed of the first head and the ejection speed of the second head are 10.0 m / s or lower.

4. The droplet ejection apparatus according to claim 1, wherein an ejection amount of a nozzle of the first head and an ejection amount of a nozzle of the second head are 4 pL or more and 30 pL or less.

5. The droplet ejection apparatus according to claim 1, wherein the first liquid contains a dispersion, wherein the second liquid contains a coagulant that causes aggregation of the dispersion.

6. The droplet ejection apparatus according to claim 1, wherein a distance between a nozzle face of the second head on which a nozzle is provided and a recording medium is 1 mm or more and 6 mm or less.

7. The droplet ejection apparatus according to claim 1, wherein a number of satellites of a droplet ejected by the second head is smaller than a number of satellites of a droplet ejected by the first head.

8. The droplet ejection apparatus according to any one of claims 1 to 7, further comprising: a controller that controls droplet ejection of the droplet ejection section.

9. The droplet ejection apparatus according to claim 8 when claim 8 cites claim 7, wherein the controller acquires information on the number of satellites in the droplet ejected from the first head and the number of satellites in the droplet ejected from the second head; wherein the controller controls a voltage to be applied to the first head and a voltage to be applied to the second head in accordance with the acquired information.

10. The droplet ejection apparatus according to claim 8, wherein the controller causes a voltage to be applied to the second head to be smaller than a voltage to be applied to the first head.

11. The droplet ejection apparatus according to claim 8, wherein the controller applies, to the second head, a voltage having a waveform different from a waveform of a voltage applied to the first head.

12. The droplet ejection apparatus according to claim 8, wherein the controller causes a viscosity of the second liquid to be higher than a viscosity of the first liquid.

13. The droplet ejection apparatus according to claim 12, wherein the controller causes a temperature of the second liquid to be lower than a temperature of the first liquid.

14. The droplet ejection apparatus according to claim 8, wherein the controller causes an ejection frequency of the second head to be higher than an ejection frequency of the first head.

15. The droplet ejection apparatus according to claim 8, wherein the droplet ejection section includes, as the first head, inkjet heads of a plurality of types for ejecting respective color inks. wherein a number of heads as the second ejection head is greater than a number of heads of any one of the plurality of the types of the inkjet heads as the first ejection head.

16. The droplet ejection apparatus according to claim 8, wherein the controller differentiates an ejection timing at which a droplet is ejected from the first head from an ejection timing at which a droplet is ejected from the second head.

17. The droplet ejection apparatus according to claim 16, wherein the controller determines the ejection timing of the first head and the ejection timing of the second head in accordance with a distance between a nozzle face of the droplet ejection section from which the liquid is ejected and the recording medium.

18. A method of suppressing liquid aggregation in a droplet ejection apparatus, the droplet ejection apparatus comprising: a droplet ejection section which ejects droplets from nozzles, wherein the droplet ejection section includes a first head for ejecting a first liquid and a second head for ejecting a second liquid for aggregation of the first liquid, wherein the method includes controlling of droplet ejection of the droplet ejection section, wherein in the controlling, an ejection speed of the second head is controlled to be lower than an ejection speed of the first head.

19. A program for a computer of a droplet ejection apparatus, the droplet ejection apparatus comprising: a droplet ejection section which ejects droplets from nozzles, wherein the droplet ejection section includes a first head for ejecting a first liquid and a second head for ejecting a second liquid for aggregation of the first liquid, wherein the program causes the computer to function as a controller to control droplet ejection of the droplet ejection section, wherein the controller performs control such that an ejection speed of the second head is lower than an ejection speed of the first head.

Images