Liquid ejection device, liquid ejection method, method for manufacturing an article, program

Abstract

To provide a desired liquid discharge device that is configured so as to suppress a solid component with a high specific gravity from precipitating on a flow path and yet suppress densities of a solid component in ink from varying.SOLUTION: A liquid discharge device is provided with a tank in which liquid can be stored, a discharge head that can discharge the liquid, a reflux passage for the liquid, through which the liquid is refluxed from the tank via the discharge head to the tank, and a control part. The reflux passage comprises a filter passage going through a filter, and a filter bypass passage provided in parallel to the filer passage. The control part controls a ratio of flow volumes of the liquid flowing into the filer passage to flow volumes of the liquid flowing into the filter bypass passage.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a liquid ejection apparatus, a liquid ejection method using the liquid ejection apparatus, and the like. [Background technology]

[0002] 2. Description of the Related Art In the field of liquid ejection devices such as so-called inkjet printers, a liquid supply system is known that includes a tank for storing ink, a filter disposed between the tank and the ejection head, and a liquid delivery means for supplying ink from the tank to the ejection head.

[0003] When using ink containing insoluble solid components having a specific gravity greater than that of the solvent component, the ink is circulated between the tank and the head in order to prevent the solid components from settling.

[0004] Patent Document 1 discloses a printing device in which a carriage filter and a circulation filter are disposed in a flow path that circulates white ink that contains a white pigment component. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2019-147270 A Summary of the Invention [Problem to be solved by the invention]

[0006] In the printing device disclosed in Patent Document 1, in order to prevent clogging of the carriage filter, which is a time-consuming task to replace, a circulation filter with finer mesh than the carriage filter is also used in combination so that more of the coagulated ink can be captured by the circulation filter. In this device, by continuously circulating the ink, it is possible to prevent the settling of solid components in the supply system tubes, etc. It is also expected that the carriage filter, which is difficult to replace, will be prevented from becoming clogged early due to coagulated ink.

[0007] However, in this device, although impurities and aggregates can be removed by the filter, a phenomenon occurs in which solid components that should be contained in the ink are captured by the carriage filter or circulation filter while the ink is circulated for a long period of time. When the concentration of solid components in the ink decreases below the normal value, there are cases in which the ink applied to the recording medium cannot perform as intended, even if a specified amount of ink is ejected from the ejection head.

[0008] Therefore, there has been a demand for a liquid ejection device that can prevent solid components with a large specific gravity from settling in the flow passages and also can prevent fluctuations in the concentration of solid components in the ink. [Means for solving the problem]

[0009] A first aspect of the present invention is a liquid ejection device comprising a tank capable of storing a liquid, an ejection head capable of ejecting the liquid, a flow path of the liquid, which is a circulation flow path that returns to the tank from the tank via the ejection head, and a control unit, wherein the circulation flow path comprises a filter flow path that passes through a filter, and a filter bypass flow path that is arranged in parallel with the filter flow path, and the control unit controls the ratio of the flow rate of the liquid flowing through the filter flow path to the flow rate of the liquid flowing through the filter bypass flow path.

[0010] In addition, a second aspect of the present invention is a liquid ejection method that uses a liquid ejection device comprising: a tank capable of storing liquid; an ejection head capable of ejecting the liquid; a flow path of the liquid, the flow path being a return flow path from the tank via the ejection head back to the tank; and a control unit, wherein the return flow path comprises a filter flow path that passes through a filter, and a filter bypass flow path provided in parallel with the filter flow path, and the control unit controls the ratio of the flow rate of the liquid flowing through the filter flow path and the flow rate of the liquid flowing through the filter bypass flow path depending on an operating mode. Effect of the Invention

[0011] According to the present invention, it is possible to provide a liquid ejection device that can prevent solid components with a large specific gravity from settling in a flow path and can also prevent fluctuations in the concentration of solid components in the ink. [Brief description of the drawings]

[0012] [Figure 1] 1 is a schematic diagram showing the overall configuration of a liquid ejection device 100 according to a first embodiment. [Diagram 2] FIG. 2 is a schematic block diagram for explaining a control unit 20. [Diagram 3] 5 is a flowchart for explaining the transition of operation modes in the liquid ejection methods according to the first to fourth embodiments. [Figure 4] 4 is a flowchart illustrating a liquid flow path control method according to the first embodiment. [Diagram 5] FIG. 11 is a schematic diagram showing the overall configuration of a liquid ejection apparatus 500 according to a second embodiment. [Figure 6] 10 is a flowchart illustrating a liquid flow path control method according to the second embodiment. [Figure 7] FIG. 11 is a schematic diagram showing the overall configuration of a liquid ejection apparatus 700 according to a third embodiment. [Figure 8] 11 is a flowchart illustrating a liquid flow path control method according to the third embodiment. [Figure 9] FIG. 11 is a schematic diagram showing the overall configuration of a liquid ejection apparatus 900 according to a fourth embodiment. [Figure 10] 10 is a flowchart illustrating a liquid flow path control method according to the fourth embodiment. [Figure 11] 6 is a flowchart for explaining the operation procedure of step S100. [Figure 12] 13 is a valve control table for explaining the control states of valves in the fourth embodiment. [Figure 13] 5 is a schematic diagram for explaining a procedure for introducing gas into a flow path and recovering ink in a filter 3 into an ink tank 2. FIG. [Figure 14] 5A to 5C are schematic diagrams for explaining a procedure for discharging introduced gas from a flow path. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] A liquid ejection device, a liquid ejection method, and the like according to embodiments of the present invention will be described with reference to the drawings. The embodiments described below are merely examples, and those skilled in the art can appropriately modify and implement the detailed configurations without departing from the spirit and scope of the present invention.

[0014] In the drawings referred to in the following description of the embodiments, elements denoted by the same reference numbers have the same functions unless otherwise specified. In addition, since the drawings may be represented diagrammatically for the convenience of illustration and explanation, the shape, size, arrangement, etc. of the elements depicted in the drawings may not strictly correspond to the actual objects.

[0015] The liquid ejection device according to the embodiment described below may be a device that ejects liquid (ink) for recording characters or images, but is not limited thereto. For example, it may be a device that applies liquid (ink) containing a functional material to form functional films or functional elements such as electrodes, antistatic films, optical filters, resist patterns for forming electronic circuits, films for three-dimensional modeling, and organic EL elements. In the following description, the ejection of liquid (ink) by the liquid ejection device to apply it to an object may be described as "recording", but the recording here is not necessarily limited to recording information such as characters or images. For example, it also includes ejecting and applying liquid containing a functional material toward an object (substrate of the object) to manufacture an object such as a functional film or a functional element.

[0016] The liquid ejection device of the embodiment exemplified below includes a circulation flow path (liquid flow path) that exits from a tank and returns to the tank. The circulation flow path includes a filter flow path that passes through a filter, and a filter bypass flow path that is provided in parallel with the filter flow path.

[0017] The liquid ejection device of the embodiment can execute a cleaning mode in which impurities are removed from the ink using a filter. In the cleaning mode, the liquid flow path can be controlled so that all or 70% or more of the circulating ink passes through the filter flow path, and zero or less than 30% passes through the filter bypass flow path. By continuously circulating the ink along the circulation flow path without stopping, the impurities in the ink can be removed by the filter, and at the same time, it is possible to suppress the sedimentation of solid components in the liquid flow path.

[0018] The liquid ejection device can execute an ejection mode in which ink is ejected from the ejection head. In the ejection mode, the fluid flow path is controlled so that ink is supplied from the tank to the ejection head via the filter bypass flow path, and ink not consumed by the ejection head is returned to the tank. In the ejection mode, by continuously circulating the ink along the return flow path, it is possible to not only supply ink to the ejection head, but also to suppress the settling of solid components in the liquid flow path. In addition, during the ejection mode, the liquid flow path can be controlled so that all or 70% or more of the ink supplied to the ejection head passes through the filter bypass flow path, and zero or less than 30% passes through the filter flow path. This makes it possible to prevent or suppress the capture of solid components that should originally be contained in the ink by the filter, and suppress a decrease in the concentration of solid components in the ink.

[0019] Furthermore, the liquid ejection device of the embodiment can continue to circulate ink in the liquid flow path to prevent solid components from settling even in modes other than those described above (for example, a standby mode in which neither cleaning nor ejection is performed). In this case, the liquid flow path can be controlled so that all or 70% or more of the circulated ink passes through the filter bypass flow path, and zero or less than 30% passes through the filter flow path. This makes it possible to prevent or reduce the capture of solid components that should originally be contained in the ink by the filter, and to suppress a decrease in the concentration of solid components in the ink.

[0020] In the liquid ejection device of the embodiment, when the tank is refilled with ink or when a replaceable tank filled with ink is attached, a cleaning mode is performed to remove impurities from the ink. When the cleaning mode is completed, the operation mode is switched to another operation mode, but the ink continues to circulate in order to suppress the settling of solid components. In the other operation mode, flow path control is performed to prevent or reduce the capture of solid components that should originally be contained in the ink by the filter. That is, the liquid flow path is controlled so that all or 70% or more of the circulated ink passes through the filter bypass flow path, and zero or less than 30% passes through the filter flow path. This makes it possible to suppress fluctuations in the concentration of solid components in the ink from which impurities have been removed, and also to suppress the settling of solid components in the liquid flow path.

[0021] Therefore, according to the liquid ejection device and the liquid ejection method of the embodiment, ink containing a predetermined concentration of solid components can be stably applied to an object, so that the applied ink can exhibit its original performance. For example, when recording characters or images, characters or images can be recorded in a desired color or shade, and when forming a functional film or functional element using a liquid containing a functional material, a functional film or functional element with desired performance can be manufactured.

[0022] [Embodiment 1] (Configuration of liquid ejection device) First, a description will be given of the overall configuration of a liquid ejection device 100 according to embodiment 1. Fig. 1 is a schematic diagram showing the configuration of the liquid ejection device 100. For ease of explanation, general components (such as a housing and a power supply) that are not directly related to the problem-solving principle of the present invention are omitted from the illustration.

[0023] The liquid ejection device 100 includes an ejection head 1 capable of ejecting ink, an ink tank 2 capable of storing ink, a filter 3, a pump 4, a flow path control valve 6, and a flow path control valve 9, which are connected by a liquid flow path. That is, the ink tank 2 and the pump 4 are connected by a flow path 11, and the pump 4 and the flow path control valve 6 are connected by a flow path 5. The pump 4 may be a pump for liquid, such as a diaphragm pump, a tubing pump, or a piston pump. It is desirable to operate the pump 4 at all times, except when performing maintenance on the liquid ejection device 100, to circulate the ink and prevent the settling of solid components.

[0024] A filter flow path 7 that passes through the filter 3 and a filter bypass flow path 8 that bypasses the filter 3 are provided in parallel between the flow path control valve 6 and the flow path control valve 9. The flow path control valve 6 and the flow path control valve 9 are three-way valves that can switch the connection of the flow paths. The flow path control valve 9 and the ejection head 1 are connected by a flow path 10, and the ejection head 1 and the ink tank 2 are connected by a flow path 12.

[0025] The ink tank 2 may be either fixed or replaceable, and ink can be replenished by injecting ink into a fixed tank or by attaching a replaceable tank filled with ink. The ink tank 2 may be provided with a pressure control mechanism (not shown). The pressure control mechanism can control the air pressure inside the tank to an appropriate pressure (e.g., negative pressure) so that ink is supplied from the ink tank 2 to the ejection head 1 under conditions suitable for ejecting the ink.

[0026] The liquid ejection device 100 includes a control unit 20 that controls the operation of each unit. Fig. 2 is a schematic block diagram for explaining the control unit 20. The control unit 20 is a computer for controlling the operation of the liquid ejection device 100, and includes a CPU, a ROM, a RAM, an I / O port, and the like. The ROM stores an operation program for the liquid ejection device 100.

[0027] The operations related to the liquid ejection method of this embodiment are executed under the control of the control unit 20, which stores a control program for controlling the operations of each unit, such as the pump 4, the flow path control valve 6, the flow path control valve 9, and the ejection head 1. The control program related to the liquid ejection method may be stored in a ROM like other operation programs, or may be loaded into a RAM from outside via a network. Alternatively, the control program may be loaded into a RAM via a computer-readable recording medium, such as a flexible disk, an optical disk, a magneto-optical disk, a magnetic tape, a USB memory, or an SSD.

[0028] The I / O port is connected to an external device or a network, and can perform input and output of data necessary for, for example, ink ejection control, between the external computer 21. The I / O port is also connected to a display device and an input device (not shown), and can display information about the operating state of the liquid ejection device 100 to an operator and can receive commands from the operator.

[0029] The control unit 20 is connected to controlled elements such as the pump 4, the flow path control valve 6, the flow path control valve 9, and the ejection head 1 in a manner capable of transmitting signals, and is capable of controlling these. The control unit 20 is also connected to various sensors provided in the ink tank 2 in a manner capable of transmitting signals, such as a liquid volume sensor 22, a pressure sensor 23, and a temperature sensor 24, and is capable of acquiring measurement information required for control. Note that while the control elements according to the present invention are shown in Fig. 2, other control elements provided in the liquid ejection device, such as control elements and sensors relating to position control of the ejection head, are not shown.

[0030] (inks and filters) The ink ejected by the liquid ejection device 100 of this embodiment may contain an insoluble solid component. For example, in this embodiment, an ink containing an acrylic monomer as a main component and TiO2 particles as an insoluble solid component is preferably used. The particle size of TiO2 has a median particle diameter of 200 nm and a particle size distribution of 100 to 700 nm. The concentration of the insoluble solid component contained in the ink is 7 wt%. However, the ink used in the liquid ejection device according to the present invention is not limited to this example, and the type, particle size, and concentration of the insoluble solid component, and the main component of the ink are not limited to this example. The particle size of the insoluble solid component is preferably 50 nm or more and 2 μm or less. The viscosity of the ink used in this embodiment is 10 mPa·s at room temperature (for example, 23° C.±2° C.), but is not limited to this example, and can be used without any problem as long as it is in the range of 1.0 mPa·s or more and 40 mPa·s or less at room temperature.

[0031] By strictly controlling the process of manufacturing the ink, it is possible to keep the impurities contained in the ink immediately after production below a certain level. However, when the ink is filled into a container after production, transported, or replenished into a liquid ejection device, there is a possibility that relatively large impurities may become mixed into the ink.

[0032] Therefore, the liquid ejection device 100 according to this embodiment is provided with a filter 3 for removing solid impurities from the refilled ink. A so-called capsule filter is preferably used as the filter 3. A capsule filter is a filter medium (filter material) stored in a capsule-shaped case, and has a relatively low pressure loss and is capable of stably filtering the ink. However, the capsule filter is only one example, and the liquid ejection device according to the present invention can also be provided with other types of filters.

[0033] The filter media (filter material) built into the case may be, for example, a porous membrane, fiber, or granules. An appropriate filter media (filter material) may be selected with reference to impurities that may be mixed into the ink and the particle size of solid components originally contained in the ink. In the explanation of this embodiment, "filter size" may be used as an index for indicating the filtering ability of a filter. Filter size refers to the smallest size of particles that the filter can remove almost entirely (e.g., 99.9% or more) when a liquid containing particles is passed through the filter once.

[0034] If the filter size is too small, not only the impurities but also the insoluble solid components that should be contained in the ink may be collected by the filter, so the filter size must be set appropriately. The filter size of the filter 3 used in this embodiment is preferably 5 to 100 times the median particle size of the insoluble solid components that should be contained in the ink, and is preferably smaller than the ejection nozzle diameter of the inkjet head. Here, the median particle size refers to the diameter of the particle with the highest content, that is, the particle size corresponding to the center of the particle size distribution. In this embodiment, since the median particle size of the TiO2 particles contained in the ink is 200 nm, a filter medium with a filter size of 5 μm (or 10 μm) was selected. A filter medium with a filter size in the range of 1 μm to 20 μm is suitable, but the filter size is set appropriately depending on the particle size of the insoluble solid components of the ink and the particle size of the impurities to be removed from the ink.

[0035] In a filter having a large surface area of ​​the filter media such as a capsule filter, even if the filter size is set as described above, there is a possibility that insoluble solid components smaller than the filter size will adhere to the surface of the filter media and be captured. In other words, if the ink continues to pass through the filter for a long period of time even after the impurities have been removed, there is a possibility that the insoluble solid components that should be contained in the ink will be captured and reduced. Therefore, in this embodiment, a filter bypass flow path 8 that bypasses the filter 3 is provided in parallel with the filter flow path 7 that passes through the filter 3, and the flow path when circulating the ink is appropriately controlled.

[0036] (Liquid discharge method) FIG. 3 is a flowchart for explaining the procedure of a liquid ejection method using the liquid ejection apparatus 100. As shown in FIG.

[0037] When the operation of the liquid ejection device 100 is started, the control unit 20 executes a cleaning mode for removing impurities from the ink stored in the ink tank 2 in step S1. Specifically, the control unit 20 drives the pump 4 and controls the flow path control valve 6 and the flow path control valve 9 to connect the flow path 5 and the flow path 10 with the filter flow path 7 and close the filter bypass flow path 8. As a result, the ink continues to circulate (return) along the arrows C1 to C3 to C4 to C5 in the figure, and impurities are removed by the filter 3. Since the ink continues to circulate during the execution of the cleaning mode, the precipitation of solid components in the liquid flow path is suppressed. The ink tank 2 stores 500 ml of ink, and the pump 4 is driven so that the flow rate is 50 ml / min, but this is an example and other conditions may be used.

[0038] In step S2, the control unit 20 judges whether or not the ink has been sufficiently cleaned, and if it is judged that the ink has not been sufficiently cleaned (step S2: NO), the process returns to step S1 and continues to execute the cleaning mode. In order to judge whether or not the ink has been sufficiently cleaned, judgment conditions can be set in advance based on the particle size of impurities that may be contained in the ink, the filter size of the filter 3, the amount of ink stored in the ink tank 2, the liquid delivery capacity of the pump 4, and the like. For example, the cleaning mode can be experimentally performed in advance, the concentration of impurities remaining in the ink can be measured over time, and the time required for sufficient cleaning can be determined and stored in the control unit 20. In this way, the control unit 20 can judge whether or not the cleaning has been sufficiently performed by measuring the execution time of the cleaning mode using a timer program or the like.

[0039] If the cleaning mode is executed for a longer period than necessary, there is a possibility that the insoluble solid components that should be contained in the ink may adhere to the filter, so it is advisable to measure the change in concentration of the insoluble solid components in the ink over time in advance and set the optimal execution time. For example, in this embodiment, the operation time of the cleaning mode is set to one hour, and it has been confirmed that while most of the impurities can be removed, the concentration of the insoluble solid components does not change within the measurement accuracy of a TGA (thermogravimetric analyzer). The operation time of the cleaning mode is preferably set so that the reduction amount is 0.2 wt% or less, preferably 0.1 wt% or less, when the concentration of the insoluble solid components of the ink stored in the ink tank 2 is examined by a TGA (thermogravimetric analyzer). Of course, the operation time of the cleaning mode is not limited to this example, and appropriate judgment conditions can be set according to the particle size of the impurities, the filter size of the filter 3, the amount of ink stored in the ink tank 2, the liquid delivery capacity of the pump 4, and the like.

[0040] If it is determined that the ink cleaning has been performed sufficiently (step S2: YES), the control unit 20 proceeds to step S4 after terminating the cleaning mode in step S3, and determines whether or not to immediately start a liquid ejection operation. Specifically, it determines whether or not a liquid ejection command has been received.

[0041] If no liquid ejection command has been received (step S4: NO), the process proceeds to step S9, where the control unit 20 executes the standby mode. Specifically, the control unit 20 continues to drive the pump 4, and controls the flow path control valve 6 and the flow path control valve 9 to connect the flow path 5 and the flow path 10 via the filter bypass flow path 8, and closes the filter flow path 7. As a result, the ink continues to circulate (return) along C1-C2-C4-C5, as indicated by the arrows in the figure.

[0042] During standby mode, ink continues to circulate, preventing the solid components in the ink from settling in the liquid flow path. Also, because the filter flow path 7 is closed, the solid components that should be contained in the ink are not captured by the filter 3, preventing changes in the concentration of the solid components. After that, the process loop from (Step S4: NO) to (Step S9) is repeated until a liquid ejection command is received, and the standby mode continues, preventing changes in the concentration of the solid components in the ink and preventing the settling of the solid components.

[0043] If a liquid ejection command is received (step S4: YES), the process proceeds to step S5, where the control unit 20 executes the liquid ejection mode. Specifically, the control unit 20 continues to drive the pump 4, and controls the flow path control valve 6 and the flow path control valve 9 to connect the flow path 5 and the flow path 10 via the filter bypass flow path 8 and close the filter flow path 7. As a result, ink is supplied to the ejection head 1 via C1 to C2 to C4, as indicated by arrows in the figure, and is ejected from the ejection head. Furthermore, the remaining ink that has not been ejected from the ejection head flows back to the ink tank 2 via the flow path 12 along the arrow C5.

[0044] Since the ink continues to circulate during the liquid ejection mode, the solid components in the ink are prevented from settling in the liquid flow path. Also, since the filter flow path 7 is closed, the solid components that should be contained in the ink are not captured by the filter 3, and fluctuations in the concentration of the solid components are suppressed.

[0045] Next, the process proceeds to step S6, where the control unit 20 determines whether to end the liquid ejection mode (whether the necessary ejection operation has been completed). If the liquid ejection mode is to be ended (step S6: YES), the process proceeds to step S9, where the standby mode is executed. Thereafter, the process loop of steps S4 to S9 is repeated and the standby mode continues until a liquid ejection command is received, but as already described, while the standby mode is being executed, fluctuations in the concentration of solid components in the ink are suppressed.

[0046] If the liquid ejection mode is not to be ended (step S6: NO), the liquid ejection mode continues, but the process proceeds to step S7, where the control unit 20 judges whether the time that has elapsed since the cleaning mode was ended in step S3 has exceeded a predetermined time. In this embodiment, after the cleaning mode is ended, the standby mode or the liquid ejection mode is executed to continue circulating the ink, so that the solid components in the ink are prevented from settling in the liquid flow path. However, if a long time has passed since cleaning, new impurities may be mixed into the ink from the outside, or the solid matter in the ink may aggregate to form a large lump that is not suitable for ejection from the ejection head 1. Therefore, in this embodiment, in step S7, it is judged whether the time that has elapsed since the cleaning mode was ended has exceeded a predetermined time, and if it has exceeded the predetermined time (step S7: YES), the process returns to step S1 and executes the cleaning mode again. The predetermined time may be appropriately set in advance by experiment, for example, and stored in the control unit 20 as a judgment criterion.

[0047] In this embodiment, the criterion is whether or not the time elapsed since the cleaning mode was ended exceeds 12 hours, but the judgment condition of step S7 is not limited to this and other conditions can be set. For example, during execution of the ejection mode, the speed of the ejected droplets and the landing position and shape of the droplets that land on the recording medium may be measured to judge whether or not the predetermined ejection performance is maintained, and if not, the process may return to step S1 and execute the cleaning mode again. In this case, in step S7, the control unit 20 may cause the ejection head 1 to record a test pattern and measure the position and shape of the landed ink droplets to make the above judgment.

[0048] If the time elapsed since the cleaning mode was ended has not exceeded the predetermined time (step S7: NO), the liquid ejection mode continues, but the control unit 20 checks the remaining ink level in the ink tank 2 using the liquid level sensor 22 in step S8. If the remaining ink level is less than the predetermined level, it is determined that ink needs to be replenished (step S8: YES), and ink is replenished into the ink tank 2 in step S10. In this embodiment, the predetermined level (determination threshold) is 50 ml, but this is not the only example and any appropriate determination threshold can be set. When ink replenishment is completed, the process proceeds to step S1, and the control unit 20 executes the cleaning mode already described. If it is determined that ink replenishment is not required (step S8: NO), the process returns to step S5, and the control unit 20 continues to execute the liquid ejection mode.

[0049] The operational procedure of the liquid ejection device 100 has been described above with reference to FIG. 3. Next, with reference to FIG. 4, an additional explanation will be given from the viewpoint of a method for controlling the liquid flow paths.

[0050] When the operation of the liquid ejection device 100 is started, in step S21, the ink tank 2 is refilled with, for example, 500 ml of ink, and in the following step S22, a circulation path (return path) is configured along C1-C3-C4-C5 shown by arrows in Fig. 1. Step S22 corresponds to the cleaning mode described in step S1 of Fig. 3, and a circulation path (return path) using the filter path 7 is configured. At that time, the pump 4 is driven so that the flow rate becomes, for example, 50 ml / min.

[0051] Until it is determined in step S23 that it is time to change the flow path, the circulation path (return flow path) using the filter flow path 7 continues to be formed, and the ink continues to circulate. Note that step S23 corresponds to step S2 in FIG.

[0052] When it is determined in step S23 that it is time to change the flow path (step S23: YES), a circulation path that is partially different from the previous path is configured in step S24. That is, in step S24, a circulation path (circulation path) is configured along C1-C2-C4-C5 shown by arrows in Fig. 1. Step S24 corresponds to either the liquid ejection mode described in step S5 of Fig. 3 or the standby mode described in step S9, and a circulation path (circulation path) using the filter bypass flow path 8 is configured.

[0053] Next, in step S25, it is determined whether the ink has been circulated through the circulation path (return path) using the filter bypass path 8 for a predetermined time. Although step S7 is described in FIG. 3 as being performed during execution of the liquid ejection mode, a similar determination may be made during execution of the standby mode. That is, step S25 in FIG. 4 may be performed in an operation mode other than the cleaning mode. The predetermined time used as the criterion for step S25 may be set appropriately by investigating in advance through experiments the relationship between the duration of ink circulation and the amount of new impurities mixed in.

[0054] If it is determined in step S25 that the predetermined time has elapsed (step S25: YES), the process returns to step S22, and the circulation path (return path) using the filter flow path 7 is reconfigured.

[0055] If it is determined that the predetermined time has not been exceeded (step S25: NO), the process proceeds to step S26, where it is determined whether or not the ink tank 2 needs to be replenished with ink. Note that step S26 corresponds to step S8 in FIG. If it is determined that ink needs to be replenished (step S26: YES), the process returns to step S21, and the ink tank 2 is replenished with ink.

[0056] If it is determined that ink replenishment is not necessary (step S26: NO), the process returns to step S24, and the circulation path (return path) using the filter bypass path 8 continues to be configured.

[0057] As described above, when the tank is refilled with ink, the liquid ejection device of this embodiment executes a cleaning mode in which ink is circulated through a filter flow path in order to remove impurities from the ink. In this embodiment, 100% of the ink circulating in the cleaning mode passes through the filter flow path. Once the removal of impurities is completed, in order to prevent solid components that should originally be contained in the ink from being captured by the filter, the ink is circulated by switching from the filter flow path to the filter bypass flow path, and the ink is controlled not to flow through the filter. In this embodiment, 100% of the ink circulating in the liquid ejection mode or standby mode passes through the filter bypass flow path. This makes it possible to suppress fluctuations in the concentration of solid components in the ink after the impurities have been removed, and also makes it possible to suppress the solid components from settling in the liquid flow path. Therefore, according to the liquid ejection device and liquid ejection method of this embodiment, ink containing solid components of a predetermined concentration can be stably applied to a recording medium, and the applied ink can exhibit its original performance. For example, when recording characters or images, they can be recorded in the desired color or shade, and when applying a liquid containing a functional material, a functional thin film or functional element with the desired performance can be produced.

[0058] [Embodiment 2] The overall configuration of a liquid ejection device 500 according to the second embodiment will be described with reference to Fig. 5. Fig. 5 is a schematic diagram showing the configuration of the liquid ejection device 500. For ease of explanation, general components (such as a housing and a power supply) that are not directly related to the problem-solving principle of the present invention are not shown. Elements common to the first embodiment are denoted by the same reference symbols, and explanations thereof will be simplified or omitted.

[0059] The liquid ejection device 500 is common to the first embodiment in that it includes an ejection head 1, an ink tank 2, a filter 3, a pump 4, and a control unit 20. The liquid ejection device 100 of the first embodiment includes a flow path control valve 6 and a flow path control valve 9 that can switch the connection of the flow paths, and is configured to alternatively select a filter flow path 7 or a filter bypass flow path 8. The control unit 20 controls the switching of the flow paths so that ink flows only through the filter flow path 7 in the cleaning mode, and so that ink flows only through the filter bypass flow path 8 in the liquid ejection mode and standby mode.

[0060] In contrast, in the liquid ejection device 500 of the second embodiment, no flow path control valves are provided at the branch point P1 and the junction P2, but a flow rate control valve 51 is provided at the filter bypass flow path 8, and a flow rate control valve 52 is provided at the filter flow path 7. The flow rate control valves 51 and 52 are valves that can control the flow rate of the flowing liquid, and their operations are controlled by the control unit 20. The control unit 20 can individually control the flow rate of C2 flowing through the filter bypass flow path 8 and the flow rate of C3 flowing through the filter flow path 7.

[0061] Like the first embodiment, the liquid ejection device 500 of the present embodiment also executes each of the cleaning mode, liquid ejection mode, and standby mode according to the flowchart shown in Fig. 3. However, the present embodiment differs from the first embodiment in the method of controlling the flow paths in each mode.

[0062] A description will be given from the viewpoint of a method for controlling a liquid flow path with reference to Fig. 6. In Fig. 6, steps S21, S23, S25, and S26 are similar to those in the first embodiment described with reference to Fig. 4, and therefore description thereof will be omitted.

[0063] In this embodiment, when circulating the ink in step S61, the control unit 20 controls the flow control valves 51 and 52 to circulate the ink such that the flow rate in the filter flow path 7 is greater than that in the filter bypass flow path 8. (C3>C2). In the cleaning mode, more than half of the circulating ink passes through the filter flow path 7 to remove impurities, while ink is also caused to flow through the filter bypass flow path 8 to prevent solid components of the ink from settling in the filter bypass flow path. The ratio of the flow rates of the filter bypass flow path 8 and the filter flow path 7 in step S61 is set according to the impurity removal ability of the filter 3 and the ease of settling of solid components of the ink.

[0064] In general, when the total flow rate of the filter bypass flow path 8 and the filter flow path 7 in the cleaning mode is taken as 100%, the flow rate of the filter flow path 7 is preferably 70% or more, and more preferably 90% or more.

[0065] In addition, in this embodiment, when circulating the ink in step S62, the control unit 20 controls the flow control valve 51 and the flow control valve 52 to circulate the ink such that the flow rate in the filter bypass flow path 8 is greater than that in the filter flow path 7. (C2>C3). In the liquid ejection mode and the standby mode, more than half of the circulating ink passes through the filter bypass flow path 8 to suppress the solid components of the ink from settling in the circulation flow path. At that time, ink is also made to flow through the filter flow path 7 to suppress the solid components of the ink from settling in the filter flow path 7, but the flow rate through the filter flow path 7 is reduced to prevent the solid components that should be included in the ink from being excessively captured by the filter 3. The ratio of the flow rates of the filter bypass flow path 8 and the filter flow path 7 in step S62 can be set according to the ease of settling of the solid components of the ink and the rate at which the solid components that should be included in the ink are captured by the filter 3.

[0066] In general, when the total flow rate of the filter bypass flow path 8 and the filter flow path 7 in the liquid ejection mode and standby mode is taken as 100%, it is preferable to set the flow rate of the filter bypass flow path 8 to 70% or more, and it is even more preferable to set it to 90% or more.

[0067] In this embodiment, flow control valves 51 and 52 are provided to precisely control the flow rate ratio between the filter bypass flow path 8 and the filter flow path 7, but as long as a predetermined flow rate ratio can be realized, a configuration in which a flow control valve is provided in only one of the flow paths may be adopted.

[0068] When the tank is refilled with ink, the liquid ejection device of this embodiment performs a cleaning mode in which the ink is circulated mainly via the filter flow path in order to remove impurities from the ink. At that time, a small amount of ink is also made to flow through the filter bypass flow path to suppress the precipitation of solid components in the filter bypass flow path. Once the removal of impurities is completed, the ink is circulated mainly via the filter bypass flow path, and the ink flowing through the filter is suppressed to reduce the capture of solid components that should originally be contained in the ink by the filter. This makes it possible to suppress the concentration of solid components in the ink after the impurities have been removed from fluctuating, and furthermore, to suppress the precipitation of the solid components in the liquid flow path and the filter case. Therefore, according to the liquid ejection device and liquid ejection method of this embodiment, ink containing a predetermined concentration of solid components can be stably applied to a recording medium, so that the applied ink can exhibit its original performance. For example, when recording characters or images, it is possible to record with the desired color and shade, and when applying a liquid containing a functional material, it is possible to manufacture a functional thin film or a functional element with the desired performance.

[0069] [Embodiment 3] The overall configuration of a liquid ejection device 700 according to the third embodiment will be described with reference to Fig. 7. Fig. 7 is a schematic diagram showing the configuration of the liquid ejection device 700. For ease of explanation, general components (such as a housing and a power supply) that are not directly related to the problem-solving principle of the present invention are not shown. Elements common to the first embodiment are denoted by the same reference symbols, and explanations thereof will be simplified or omitted.

[0070] The liquid ejection device 700 is common to the first embodiment in that it includes an ejection head 1, an ink tank 2, a filter 3, a pump 4, a flow path control valve 6, a flow path control valve 9, and a control unit 20. In the liquid ejection device 100 of the first embodiment, ink is circulated in a flow path that passes through the ejection head 1 in any of the cleaning mode, the liquid ejection mode, and the standby mode.

[0071] In contrast, the liquid ejection device 700 of the third embodiment is provided with a head flow path 71 that passes through the ejection head 1, and a head bypass flow path 72 that bypasses the ejection head 1, and is different in that the head flow path 71 and the head bypass flow path 72 are used differently depending on the mode. That is, in the cleaning mode, ink is circulated via the head bypass flow path 72, and in the liquid ejection mode and standby mode, ink is circulated via the head flow path 71.

[0072] To make this possible, in the liquid ejection device 700, a flow path control valve 61 is provided upstream of the ejection head 1, and a flow path control valve 62 is provided downstream of the ejection head 1. The flow path control valve 61 and the flow path control valve 62 are three-way valves that can switch the connection of the flow paths under the control of the control unit 20, and a head flow path 71 and a head bypass flow path 72 are provided in parallel between the two valves.

[0073] Like the first embodiment, the liquid ejection device 700 of the present embodiment also executes each of the cleaning mode, ejection mode, and standby mode according to the flowchart shown in Fig. 3. However, the present embodiment differs from the first embodiment in the method of controlling the flow paths in each mode.

[0074] A description will be given from the viewpoint of a method for controlling a liquid flow path with reference to Fig. 8. In Fig. 8, steps S21, S23, S25, and S26 are similar to those in the first embodiment described with reference to Fig. 4, and therefore descriptions thereof will be omitted.

[0075] In this embodiment, when circulating the ink in step S81, the control unit 20 controls the flow path control valve 6 and the flow path control valve 9 to connect the flow path 5 and the flow path 10 via the filter flow path 7. At the same time, the control unit 20 controls the flow path control valve 61 and the flow path control valve 62 to connect the flow path 10 and the flow path 12 via the head bypass flow path 72. According to this embodiment, in the cleaning mode, the ink continues to circulate (return) along C1 to C3 to C4 to C7 to C5 indicated by the arrows in the figure, and impurities are removed by the filter 3. Since the ink continues to circulate during the execution of the cleaning mode, the precipitation of solid components in the liquid flow path is suppressed. At that time, the ink is circulated using the head bypass flow path 72 without passing through the ejection head 1, so that the ink during the cleaning process from which impurities have not been completely removed does not come into contact with the ejection head 1. This makes it possible to prevent, for example, impurities that have not been completely removed from adhering to the ejection head 1 during the cleaning process.

[0076] In this embodiment, when circulating the ink in step S82, the control unit 20 controls the flow path control valve 6 and the flow path control valve 9 to connect the flow path 5 and the flow path 10 through the filter bypass flow path 8. At the same time, the control unit 20 controls the flow path control valve 61 and the flow path control valve 62 to connect the flow path 10 and the flow path 12 through the head flow path 71. Therefore, in step S82 in which the liquid ejection mode or the standby mode is executed, the ink continues to circulate (return) along the arrows C1 to C2 to C4 to C6 to C5 in the figure. Since the ink continues to circulate during the execution of the liquid ejection mode or the standby mode, the precipitation of solid components in the liquid flow path is suppressed. Furthermore, since the filter flow path 7 is closed, the solid components that should originally be contained in the ink are not captured by the filter 3, and the concentration of the solid components that should be contained is suppressed from changing.

[0077] As described above, when the liquid ejection device of this embodiment refills the tank with ink, it executes a cleaning mode in which ink is circulated through a filter flow path in order to remove impurities from the ink. At that time, by circulating the ink through the head bypass flow path 72 without passing through the ejection head 1, it is possible to prevent ink from which impurities have not been completely removed from contacting the ejection head 1 during the cleaning process.

[0078] Once the removal of impurities is complete, in order to prevent the solid components that should be contained in the ink from being captured by the filter, the ink is circulated by switching from the filter flow path to the filter bypass flow path, and ink is controlled not to flow through the filter. This makes it possible to suppress fluctuations in the concentration of solid components in the ink after the impurities have been removed, and also to suppress the solid components from settling in the liquid flow path. Therefore, according to the liquid ejection device and liquid ejection method of this embodiment, ink containing a predetermined concentration of solid components can be stably applied to a recording medium, so that the applied ink can exhibit its original performance. For example, when recording characters or images, they can be recorded in the desired color or shade, and when applying a liquid containing a functional material, a functional thin film or functional element with the desired performance can be manufactured.

[0079] [Embodiment 4] The overall configuration of a liquid ejection device 900 according to the fourth embodiment will be described with reference to Fig. 9. Fig. 9 is a schematic diagram showing the configuration of the liquid ejection device 900. For ease of explanation, general components (such as a housing and a power supply) that are not directly related to the problem-solving principle of the present invention are not shown. Elements common to the third embodiment are denoted by the same reference symbols, and explanations thereof will be simplified or omitted.

[0080] The liquid ejection device 900 is similar to embodiment 3 in that it is equipped with an ejection head 1, an ink tank 2, a filter 3, a pump 4, a flow path control valve 6, a flow path control valve 9, a flow path control valve 61, a flow path control valve 62, a head flow path 71, a head bypass flow path 72, and a control unit 20.

[0081] In the liquid ejection device 700 of the third embodiment, after the cleaning mode is performed, the flow path is switched from the filter flow path 7 to the filter bypass flow path 8 while ink remains in the filter 3, and the liquid ejection mode or the standby mode is performed.

[0082] In contrast, the liquid ejection device 900 of the fourth embodiment, after executing the cleaning mode, removes ink remaining in the filter 3 and the filter flow path 7. This makes it possible to prevent solid components contained in the ink from precipitating in the case of the filter 3 that stores the filter media (filter material) and in the filter flow path 7, and prevents the precipitated solid components from adversely affecting the operation of the cleaning mode again.

[0083] Furthermore, the liquid ejection device 900 of this embodiment is configured so that the ink removed from the filter 3 and the filter flow path 7 can be collected in the ink tank 2 and reused for ejection. This makes it possible to use the ink without waste, which is beneficial in terms of cost and environmental protection.

[0084] Furthermore, according to the liquid ejection device 900 of this embodiment, the ink is removed from the filter 3 and the filter flow path 7 and collected in the ink tank 2 by injecting gas into the liquid flow path, and then an exhaust (degassing) process is performed on the liquid flow path into which the gas was injected. This makes it possible to prevent the gas remaining in the flow path from dissolving into the ink and changing the physical properties of the ink when ink is reinjected into the part into which the gas was injected to remove the ink.

[0085] To achieve this, the liquid ejection device 900 includes a gas inlet section that introduces gas into the filter flow path to remove ink from the filter flow path, and an exhaust section that exhausts the gas introduced into the filter flow path. Specifically, the liquid ejection device 900 further includes a flow path opening / closing valve 89, a flow path control valve 90, a flow path 91, a pipe 92, a pipe control valve 93, a gas inlet path 94, an exhaust path 95, a gas exhaust path 96, an exhaust pump 97, an exhaust path 98, and a degassing module 99.

[0086] The flow path opening / closing valve 89 is disposed in the flow path 12 connecting the flow path control valve 62 and the ink tank 2, and is a valve that opens and closes the flow path 12 under the control of the control unit 20. The flow path control valve 90 is a three-way valve that can be switched, under the control of the control unit 20, between connecting the flow path 5 and the flow path 91, or connecting the pipe 92 and the flow path 91. The flow path 91 connects the flow path control valve 90 and the flow path control valve 6, and constitutes a part of a circulation flow path that circulates the ink.

[0087] The conduit 92 is a conduit that serves as a gas flow path when gas is supplied to the flow path 91 or when gas is exhausted from the filter 3 or the like via the flow path 91. The conduit control valve 93 is a three-way valve that can be switched, under the control of the control unit 20, between connecting the conduit 92 to a gas inlet path 94 or connecting the conduit 92 to an exhaust path 95.

[0088] The gas inlet passage 94 is a conduit for introducing gas from the outside to be used when removing ink from the filter 3. The gas used here is desirably a gas that does not react or dissolve when it comes into contact with the ink and thus does not change the physical properties of the ink, and although this depends on the type of ink, for example, dry air or dry nitrogen is used. The gas is supplied from the gas inlet passage 94 at a pressure of, for example, 0.2 atmospheres.

[0089] The exhaust path 95 is a pipe that serves as a gas flow path when gas is exhausted from the filter 3 etc., and is connected to an exhaust pump 97. Various types of vacuum pumps can be used as the exhaust pump 97, which sucks in gas and exhausts it to the gas exhaust path 96. The exhaust pump 97 is also connected to a degassing module 99 via an exhaust path 98. The degassing module 99 is a device that includes, for example, a tube with a hollow fiber membrane, and removes air bubbles and dissolved gas from the ink by passing the ink through the tube.

[0090] As in the first or third embodiment, the liquid ejection device 900 of this embodiment also executes each of the cleaning mode, ejection mode, and standby mode according to the flowchart shown in Fig. 3. However, in this embodiment, when the cleaning mode ends, ink remaining in the filter 3 and the filter flow path 7 is removed and collected in the ink tank 2, and the filter 3 and the filter flow path 7 are degassed.

[0091] With reference to Fig. 10, an explanation will be added from the viewpoint of a method for controlling a liquid flow path. In Fig. 10, the steps other than step S100 are the same as those in embodiment 3 explained with reference to Fig. 8, and therefore explanations will be omitted. In this embodiment, when the cleaning mode is completed, that is, when step S23 (S2) becomes YES, the process proceeds to step S100, and after the process of step S100 is completed, the process proceeds to step S82.

[0092] The procedure of the process performed in step S100 will be specifically described with reference to the flowchart shown in Fig. 11. When step S100 starts, in step S101, the control unit 20 stops the pump 4 to temporarily stop the circulation of ink.

[0093] Next, in step S102, the control unit 20 uses gas to discharge ink from inside the filter 3, and recovers the discharged ink in the ink tank 2. The upper part of the valve control table shown in Fig. 12 shows control commands used by the control unit 20 to control each valve in step S102. Also, in Fig. 13, the flow of gas in step S102 is shown diagrammatically by thick arrows.

[0094] 13, gas introduced from a gas introduction path 94 passes through a conduit control valve 93, a conduit 92, and a flow path control valve 90, and is introduced into a flow path 91. The gas introduced into the flow path 91 advances through the circulation flow path while pushing the remaining ink along the direction of the arrow. In other words, the ink remaining in the circulation flow path downstream of the flow path control valve 90, including the ink remaining in the filter 3, is pushed by the introduced gas and flows as shown by the arrow, and is collected in the ink tank 2 through the open flow path opening / closing valve 89.

[0095] When the remaining ink is collected in the ink tank 2, the control unit 20 operates the exhaust pump 97 in step S103 of the flow chart shown in FIG. 11, and the process proceeds to step S104. The exhaust pump 97 must start operating before step S104, but does not necessarily have to start operating after step S102. For example, the exhaust pump 97 may be started during the cleaning mode before starting step S100 and may be operated continuously. In that case, step S103 is omitted and the process proceeds to step S104. If the exhaust pump 97 is operated and the degassing module 99 is operated when circulating the ink, including the cleaning mode, it is possible to remove dissolved gas in the circulating ink. By maintaining the amount of dissolved oxygen in the ink at, for example, 3 ppm or less, the ejection from the ejection head 1 can be stabilized.

[0096] In step S104, the control unit 20 exhausts from the flow path the gas that was introduced when the ink was collected in the ink tank 2 in step S103. The control commands used by the control unit 20 to control each valve in step S104 are shown in the middle section of the valve control table shown in Fig. 12. Also, in Fig. 14, the flow of the gas exhausted in step S104 is shown typically by thick arrows.

[0097] The circulation flow path downstream of the flow path control valve 90 is connected to an exhaust pump 97 via a pipe 92, a pipe control valve 93, and an exhaust path 95, but because the flow path opening / closing valve 89 is closed, the gas that had filled the flow path is exhausted and discharged from a gas exhaust path 96.

[0098] When the gas filling the flow path is exhausted, the process proceeds to step S105, where the control unit 20 controls each valve to configure a liquid flow path for step S82, and operates the pump 4. The lower part of the valve control table shown in FIG. 12 shows control commands used by the control unit 20 to control each valve in step S105. When step S105 is completed, step S100 shown in FIG. 10 is completed, and the process proceeds to step S82. The subsequent operations are the same as those in the third embodiment.

[0099] As described above, when the liquid ejection device according to this embodiment refills the tank with ink, it executes a cleaning mode in which ink is circulated through a filter flow path in order to remove impurities from the ink. At that time, by circulating the ink using the head bypass flow path 72 without passing through the ejection head 1, it is possible to prevent ink from which impurities have not been completely removed from contacting the ejection head 1 during the cleaning process.

[0100] Furthermore, in this embodiment, after the cleaning mode is executed, ink remaining in the filter 3 and the filter flow path 7 is removed. This makes it possible to prevent solid components contained in the ink from precipitating in the case of the filter 3 that stores the filter media (filter material) or in the filter flow path 7, and prevents the precipitated solid components from having an adverse effect when the cleaning mode is executed again.

[0101] Furthermore, in this embodiment, the ink removed from the filter 3 and the filter flow path 7 can be collected in the ink tank 2 and used for ejection. This makes it possible to use the ink without waste, which is beneficial in terms of cost and environmental conservation.

[0102] In this embodiment, the ink is removed from the filter 3 and the filter flow path 7 and collected in the ink tank 2 by injecting gas into the liquid flow path, and then an exhaust (degassing) process is performed on the liquid flow path into which the gas was injected. This makes it possible to prevent the gas from dissolving in the ink and changing the physical properties of the ink when ink is reinjected into the part into which the gas was injected to remove the ink.

[0103] Once these processes are completed, in order to prevent the solid components that should be contained in the ink from being captured by the filter, the ink is circulated by switching from the filter flow path to the filter bypass flow path, and the ink is controlled not to flow through the filter. This makes it possible to suppress fluctuations in the concentration of solid components in the ink after impurities have been removed, and also to suppress the solid components from settling in the liquid flow path. Therefore, according to the liquid ejection device and liquid ejection method of this embodiment, ink containing a predetermined concentration of solid components can be stably applied to a recording medium, so that the applied ink can exhibit its original performance. For example, when recording characters or images, they can be recorded in the desired color and shade, and when applying a liquid containing a functional material, a functional thin film or functional element with the desired performance can be manufactured.

[0104] [Comparison with the reference form] As described above, in each embodiment, a filter bypass flow path is provided in parallel with the filter flow path, and in modes other than the cleaning mode, at least half (preferably 70% or more) of the circulated ink passes through the filter bypass flow path, thereby making it possible to prevent solid components that should originally be contained in the ink from being captured by the filter.

[0105] Here, as a reference embodiment, there will be mentioned a liquid ejection device that includes the ejection head 1, ink tank 2, filter 3, and pump 4 similar to the liquid ejection device 100 of the first embodiment, but does not include the flow path control valve 6, filter bypass flow path 8, and flow path control valve 9. The reference embodiment is common to each of the embodiments in that ink is circulated in any of the cleaning mode, liquid ejection mode, and standby mode, but differs from each of the embodiments in that all of the circulated ink passes through the filter in any of the modes.

[0106] The liquid ejection device according to the reference embodiment was operated for seven consecutive days according to the control flow shown in FIG. 3 after refilling the ink tank 2 with ink, and the concentration of the insoluble solid components of the ink remaining in the ink tank 2 was examined to see if there was any change. The concentration of the insoluble solid components in the ink was measured using a TGA (thermogravimetric analyzer), and a 1.0 wt% decrease was confirmed compared to when the ink was refilled. As a result of the insoluble solid components being captured by the filter, the concentration of the insoluble solid components in the ink decreased, and after the seventh day, the ink was unable to perform as it should. For this reason, when characters or images were recorded, the quality of the colors and shades decreased, and when a liquid containing a functional material was applied, the performance of the functional thin film and the functional element tended to decrease. In addition, the filter tended to become close to being clogged, and the flow rate of the circulating liquid tended to decrease.

[0107] In response to this, the liquid ejection device according to each embodiment was operated for 10 consecutive days according to the control flow shown in FIG. 3 after refilling the ink tank 2 with ink, and it was examined whether the concentration of the insoluble solid components of the ink remaining in the ink tank 2 had changed. When the concentration of the insoluble solid components in the ink was measured using a TGA (thermogravimetric analyzer), it was confirmed that there was no change within the measurement accuracy range from the time when the ink was refilled. According to each embodiment, ink containing a predetermined concentration of solid components can be stably applied to a recording medium, so that the applied ink can exhibit its original performance. In addition, the filter does not become clogged, and continuous operation for a longer period of time than the reference embodiment is possible.

[0108] [Other embodiments] The present invention is not limited to the above-described embodiment, and many modifications are possible within the scope of the technical concept of the present invention. Different embodiments described above may be combined for implementation.

[0109] For example, in the third and fourth embodiments, similar to the first embodiment, the flow path control valve 6 and the flow path control valve 9 are used to enable switching between the filter flow path 7 and the filter bypass flow path 8, but the flow rate of each flow path may be made variable as in the second embodiment.

[0110] In the third and fourth embodiments, the flow path control valve 61 and the flow path control valve 62 are used to switch between the head flow path 71 and the head bypass flow path 72, but the flow rate ratio of these flow paths may also be made variable by other configurations. For example, a flow control valve may be provided for each of the head flow path 71 and the head bypass flow path 72, so that 70% or more of the flow rate flows through the head bypass flow path 72 in the cleaning mode, and 70% or more of the flow rate flows through the head flow path 71 in the liquid ejection mode or the standby mode.

[0111] Furthermore, in addition to the circulation flow paths described in each embodiment, the ejection head 1 may be provided with a sub-tank and a sub-flow path, and the device may be configured to have a secondary circulation flow path for circulating ink within the ejection head 1 as well.

[0112] Furthermore, the liquid ejection apparatus and liquid ejection method may be capable of executing other operation modes in addition to the cleaning mode, liquid ejection mode, and standby mode.

[0113] The present invention can also be realized by supplying a program for implementing the ink ejection method according to the embodiment to a system or device via a network or a storage medium, and having a processor in a computer of the system or device read and execute the program. A control program for causing a control unit to execute a control method relating to the ink ejection method described above, and a computer-readable storage medium storing the control program are also included in the embodiments of the present invention.

[0114] The disclosure of this specification includes the following disclosure items. [Disclosure 1] A tank capable of storing liquid; an ejection head capable of ejecting the liquid; a circulation flow path for the liquid, the circulation flow path being a flow path for the liquid that runs from the tank to the discharge head and returns to the tank; A liquid ejection device comprising: The circulation flow path includes a filter flow path passing through a filter and a filter bypass flow path provided in parallel with the filter flow path, The control unit controls a ratio of a flow rate of the liquid flowing through the filter flow path to a flow rate of the liquid flowing through the filter bypass flow path. A liquid ejection device comprising: [Disclosure 2] the circulation channel includes a channel control valve capable of switching whether the liquid flows through the filter channel or the filter bypass channel, The control unit controls the flow path control valve to change a ratio of a flow rate of the liquid flowing through the filter flow path and the filter bypass flow path. The liquid ejection device according to Disclosure 1, [Disclosure 3] the circulation channel includes a flow control valve capable of controlling a flow rate of the liquid flowing through the filter channel, and / or a flow control valve capable of controlling a flow rate of the liquid flowing through the filter bypass channel; The control unit controls the flow control valve to change a ratio of a flow rate of the liquid flowing through the filter flow path and the filter bypass flow path. The liquid ejection device according to Disclosure 1, [Disclosure 4] The circulation flow path further includes a head bypass flow path provided in parallel with the ejection head, the control unit controls a ratio of a flow rate of the liquid supplied to the ejection head to a flow rate of the liquid flowing through the head bypass flow path. 4. The liquid ejection device according to any one of Disclosure Items 1 to 3. [Disclosure 5] the circulation flow path includes a flow path control valve that can switch whether the liquid flows through the ejection head or the head bypass flow path, the control unit controls the flow path control valve to change a ratio of a flow rate of the liquid flowing through the ejection head and the head bypass flow path. The liquid ejection device according to disclosure 4, [Disclosure 6] A gas inlet portion is provided for introducing a gas into the filter flow path to remove the liquid from the filter flow path. 6. The liquid ejection device according to any one of Disclosure Items 1 to 5. [Disclosure 7] The liquid removed from the filter flow path is collected in the tank. The liquid ejection device according to Disclosure 6, [Disclosure 8] An exhaust unit that exhausts the gas introduced into the filter flow path is provided. The liquid ejection device according to Disclosure 6 or 7. [Disclosure 9] The control unit is A cleaning mode in which 70% or more of the liquid circulating through the circulation flow path is caused to pass through the filter flow path, and a discharge mode in which the liquid is discharged from the discharge head while 70% or more of the liquid circulating through the circulation flow path is caused to pass through the filter bypass flow path, 9. The liquid ejection device according to any one of Disclosure Items 1 to 8. [Disclosure 10] the cleaning mode is performed so that a reduction in the concentration of insoluble solid components contained in the liquid falls within a range of 0.2 wt % or less. The liquid ejection device according to Disclosure 9, [Disclosure 11] The control unit is Furthermore, a standby mode can be executed in which the liquid is not ejected from the ejection head while 70% or more of the liquid circulating through the circulation flow path passes through the filter bypass flow path. 11. The liquid ejection device according to Disclosure 9 or 10. [Disclosure 12] The control unit is and executing the cleaning mode again when a time during which 70% or more of the liquid is circulated to the circulation flow path via the filter bypass flow path exceeds a predetermined time after the cleaning mode is executed. 12. The liquid ejection device according to any one of Disclosure Items 9 to 11. [Disclosure 13] A tank capable of storing liquid; an ejection head capable of ejecting the liquid; a circulation flow path for the liquid, the circulation flow path being a flow path for the liquid that runs from the tank to the discharge head and returns to the tank; A liquid ejection method using a liquid ejection device including a control unit, The circulation flow path includes a filter flow path passing through a filter and a filter bypass flow path provided in parallel with the filter flow path, The control unit controls a ratio of a flow rate of the liquid flowing through the filter flow path to a flow rate of the liquid flowing through the filter bypass flow path according to an operation mode. A liquid ejection method comprising: [Disclosure 14] The control unit is A cleaning mode in which 70% or more of the liquid circulating through the circulation flow path is caused to pass through the filter flow path, and a discharge mode in which 70% or more of the liquid circulating through the circulation flow path is caused to pass through the filter bypass flow path while the liquid is discharged from the discharge head, is executable. A liquid ejection method according to Disclosure 13. [Disclosure 15] the control unit executes the cleaning mode so that a reduction in concentration of an insoluble solid component contained in the liquid falls within a range of 0.2 wt % or less. A liquid ejection method according to Disclosure 14. [Disclosure 16] The control unit is After the tank is refilled with the liquid, the cleaning mode is executed and then the ejection mode is executed. 16. A liquid ejection method according to Disclosure 14 or 15. [Disclosure 17] The control unit, after executing the cleaning mode, executes a process of introducing a gas into the filter flow path to remove the liquid from the filter flow path. 17. A liquid ejection method according to any one of Disclosure Items 14 to 16. [Disclosure 18] The control unit executes a process of recovering the liquid removed from the filter flow path in the tank. A liquid ejection method according to Disclosure 17. [Disclosure 19] The control unit executes a process of exhausting the gas introduced into the filter flow path. 19. The liquid ejection method according to Disclosure 17 or 18. [Disclosure 20] The control unit is and executing the cleaning mode again when a time during which 70% or more of the liquid is circulated to the circulation flow path via the filter bypass flow path exceeds a predetermined time after the cleaning mode is executed. 20. A liquid ejection method according to any one of Disclosure Items 14 to 19. [Disclosure 21] The control unit is A standby mode is possible in which 70% or more of the liquid circulating through the circulation flow path passes through the filter bypass flow path while the liquid is not discharged from the discharge head. 21. A liquid ejection method according to any one of Disclosure Items 13 to 20. [Disclosure 22] The circulation flow path further includes a head bypass flow path provided in parallel with the ejection head, the control unit controls a ratio of a flow rate of the liquid supplied to the ejection head to a flow rate of the liquid flowing through the head bypass flow path according to an operation mode. 22. A liquid ejection method according to any one of Disclosures 13 to 21. [Disclosure 23] The liquid is discharged from the discharge head by the liquid discharge method according to any one of Disclosures 13 to 22, and applied to a substrate. A method for producing an article comprising the steps of: [Disclosure 24] A program for causing the control unit to execute the liquid ejection method described in any one of Disclosures 13 to 22. [Disclosure 25] A computer-readable recording medium having the program described in Disclosure 24 recorded thereon. [Explanation of symbols]

[0115] 1···Ejection head / 2···Ink tank / 3···Filter / 4···Pump / 5···Flow path / 6···Flow path control valve / 7···Filter flow path / 8···Filter bypass flow path / 9···Flow path control valve / 10, 11, 12···Flow path / 20···Control unit / 21···External computer / 22···Flow rate sensor / 23···Pressure sensor / 24···Temperature sensor / 51, 52···Flow rate control valve / 61, 62···Flow path control valve / 71···Head flow path / 72···Head bypass flow path / 89···Opening and closing valve / 90···Flow path control valve / 91···Flow path / 92···Pipe line / 93···Pipe line control valve / 94···Gas inlet path / 95···Exhaust path / 96···Gas exhaust path / 97···Exhaust pump / 98···Exhaust path / 99···Degassing module / 100, 500, 700, 900···Liquid discharge device

Claims

1. A tank capable of storing a liquid, A discharge head capable of discharging the liquid, A flow path for the liquid, the flow path being a circulation path that returns from the tank through the discharge head to the tank, A liquid discharge apparatus including a control unit, The circulation path includes a filter flow path passing through a filter and a filter bypass flow path provided in parallel with the filter flow path, The control unit controls a ratio of a flow rate of the liquid flowing through the filter flow path to a flow rate of the liquid flowing through the filter bypass flow path, A liquid discharge apparatus characterized by the above.

2. The circulation path includes a flow path control valve capable of switching through which of the filter flow path and the filter bypass flow path the liquid flows, The control unit controls the flow path control valve to change a ratio of a flow rate of the liquid flowing through the filter flow path to a flow rate of the liquid flowing through the filter bypass flow path, The liquid discharge apparatus according to claim 1, characterized by the above.

3. The circulation path includes a flow rate control valve capable of controlling a flow rate of the liquid flowing through the filter flow path and / or a flow rate control valve capable of controlling a flow rate of the liquid flowing through the filter bypass flow path, The control unit controls the flow rate control valve to change a ratio of a flow rate of the liquid flowing through the filter flow path to a flow rate of the liquid flowing through the filter bypass flow path, The liquid discharge apparatus according to claim 1, characterized by the above.

4. The circulation path further includes a head bypass flow path provided in parallel with the discharge head, The control unit controls a ratio of a flow rate of the liquid supplied to the discharge head to a flow rate of the liquid flowing through the head bypass flow path, The liquid discharge apparatus according to any one of claims 1 to 3, characterized by the above.

5. The circulation path includes a flow path control valve capable of switching through which of the discharge head and the head bypass flow path the liquid flows, The control unit controls the flow path control valve to change a ratio of a flow rate of the liquid flowing through the discharge head to a flow rate of the liquid flowing through the head bypass flow path, The liquid discharge apparatus according to claim 4, characterized by the above.

6. A gas introduction unit that introduces gas into the filter flow path to remove the liquid from the filter flow path, The liquid discharge apparatus according to any one of claims 1 to 3, characterized by the above.

7. The liquid removed from the filter flow path is recovered into the tank. The liquid ejection apparatus according to claim 6, characterized in that...

8. The liquid ejection apparatus according to claim 6, further comprising an exhaust unit for exhausting the gas introduced into the filter flow path. The liquid ejection apparatus according to claim 6, characterized in that...

9. The control unit... is capable of executing a cleaning mode in which 70% or more of the liquid circulating in the circulation path passes through the filter flow path, and a discharge mode in which the liquid is discharged from the discharge head while 70% or more of the liquid circulating in the circulation path passes through the filter bypass flow path. The liquid ejection apparatus according to any one of claims 1 to 3, characterized in that...

10. The cleaning mode is executed so that the decrease in the concentration of the insoluble solid component contained in the liquid is within a range of 0.2 wt% or less. The liquid ejection apparatus according to claim 9, characterized in that...

11. The control unit... is further capable of executing a standby mode in which the liquid is not discharged from the discharge head while 70% or more of the liquid circulating in the circulation path passes through the filter bypass flow path. The liquid ejection apparatus according to claim 9, characterized in that...

12. The control unit... After executing the cleaning mode, if the time during which 70% or more of the liquid is circulated through the circulation path via the filter bypass flow path exceeds a predetermined time, the cleaning mode is executed again. The liquid ejection apparatus according to claim 9, characterized in that...

13. A liquid ejection method using a liquid ejection apparatus including a tank capable of storing a liquid, a discharge head capable of discharging the liquid, a circulation path that is a flow path of the liquid and returns from the tank via the discharge head to the tank, and a control unit, wherein the circulation path includes a filter flow path passing through a filter and a filter bypass flow path provided in parallel with the filter flow path, and the control unit controls the ratio of the flow rate of the liquid flowing through the filter flow path to the flow rate of the liquid flowing through the filter bypass flow path according to an operation mode. The liquid ejection method is characterized in that...

14. The control unit... is capable of executing a cleaning mode in which 70% or more of the liquid circulating in the circulation path passes through the filter flow path, and a discharge mode in which the liquid is discharged from the discharge head while 70% or more of the liquid circulating in the circulation path passes through the filter bypass flow path. ​ ​ ​ The liquid ejection method according to claim 13, characterized in that...

15. The control unit executes the cleaning mode so that the decrease in the concentration of the insoluble solid component contained in the liquid is within a range of 0.2 wt% or less. The liquid ejection method according to claim 14, characterized in that...

16. The control unit... After the liquid is replenished in the tank, the ejection mode is executed after the cleaning mode is executed. The liquid ejection method according to claim 14 or 15, characterized in that...

17. After executing the cleaning mode, the control unit executes a process of introducing gas into the filter flow path to remove the liquid from the filter flow path. The liquid ejection method according to claim 14 or 15, characterized in that...

18. The control unit executes a process of recovering the liquid removed from the filter flow path into the tank. The liquid ejection method according to claim 17, characterized in that...

19. The control unit executes a process of exhausting the gas introduced into the filter flow path. The liquid ejection method according to claim 17, characterized in that...

20. The control unit... After executing the cleaning mode, if the time during which 70% or more of the liquid is circulated through the circulation path via the filter bypass path exceeds a predetermined time, the cleaning mode is executed again. The liquid ejection method according to claim 14 or 15, characterized in that...

21. The control unit... Is capable of executing a standby mode in which the liquid is not ejected from the ejection head while allowing 70% or more of the liquid circulating through the circulation path to pass through the filter bypass path. The liquid ejection method according to claim 13 or 14, characterized in that...

22. The circulation path further includes a head bypass flow path provided in parallel with the ejection head. The control unit controls the ratio of the flow rate of the liquid supplied to the ejection head and the flow rate of the liquid flowing through the head bypass flow path according to the operation mode. The liquid ejection method according to claim 13 or 14, characterized in that...

23. The liquid is ejected from the ejection head and applied to a substrate by the liquid ejection method according to claim 13 or 14. A method for manufacturing an article, characterized in that...

24. A program for causing the control unit to execute the liquid ejection method according to claim 13 or 14.

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