Liquid discharge apparatus and liquid discharge method

Abstract

The present application relates to a liquid ejecting apparatus and a liquid ejecting method. The liquid ejecting apparatus has a flow path member having a flow path of a pseudoplastic liquid, an actuator that imparts pressure to the liquid in the flow path to cause a liquid droplet to be ejected from the flow path member, and a flow rate setting section that sets the flow rate of the liquid in the flow path. The flow rate setting section adjusts the circulation flow rate of the liquid that circulates sequentially in a supply reservoir, a plurality of supply manifolds, a plurality of supply flow paths, a plurality of pressure chambers, a plurality of recovery flow paths, a plurality of recovery manifolds, and a recovery reservoir to a given target flow rate. The flow path has a flow path shape in which the average viscosity of the liquid in the supply flow path when the circulation flow rate is the target flow rate is half or less of the average viscosity of the liquid in the supply manifold.

Description

[0001] This application is a divisional application of the invention patent application with application number 202080098938.5, entitled "Liquid Ejection Device and Liquid Ejection Method", with an international filing date of June 16, 2020 (priority date of March 30, 2020). Technical Field

[0002] This disclosure relates to a liquid ejection device and a liquid ejection method. Background Technology

[0003] Liquid ejection devices such as inkjet printers are known. In Patent Document 1, an inkjet recording device using thixotropic ink is disclosed as the ink.

[0004] Prior art literature

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 8-216425 Summary of the Invention

[0007] The liquid ejection device disclosed herein includes a flow path component, an actuator, and a flow rate setting unit. The flow path component has a pseudoplastic liquid flow path. The actuator applies pressure to the liquid within the flow path, causing droplets to be ejected from the flow path component. The flow rate setting unit sets the flow rate of the liquid within the flow path. The flow path includes a supply reservoir, multiple supply manifolds, multiple supply flow paths, multiple pressure chambers, multiple nozzles, multiple recovery flow paths, and a recovery reservoir. The supply reservoir is supplied with the liquid. The multiple supply manifolds are connected to the supply reservoir and are supplied with the liquid from the supply reservoir. The multiple supply flow paths are arranged in groups of two or more relative to each of the multiple supply manifolds and are each connected to any one of the multiple supply manifolds from which the liquid is supplied. The multiple pressure chambers are each connected to the multiple supply flow paths and are supplied with the liquid from the multiple supply flow paths, and are pressurized by the actuator. The plurality of nozzles are connected to the plurality of pressure chambers respectively, causing the liquid from the pressure chambers to be ejected to the outside. The plurality of recovery flow paths are connected to the plurality of pressure chambers respectively, recovering the liquid from the plurality of pressure chambers. The plurality of recovery manifolds are connected to any two or more of the plurality of recovery flow paths respectively, recovering the liquid from the plurality of recovery flow paths. The recovery reservoir is connected to the plurality of recovery manifolds, recovering the liquid from the plurality of recovery manifolds. The flow setting unit adjusts the circulation flow rate of the liquid circulating in the supply reservoir, the plurality of supply manifolds, the plurality of supply flow paths, the plurality of pressure chambers, the plurality of recovery flow paths, the plurality of recovery manifolds, and the recovery reservoir to a given target flow rate. The flow path has a flow path shape in which the average viscosity of the liquid in the supply flow path is less than half of the average viscosity of the liquid in the supply manifold when the circulation flow rate is the target flow rate.

[0008] The liquid ejection method disclosed herein involves a liquid ejection method using the aforementioned liquid ejection device, employing a shear rate of 1000 s. -1 The viscosity at that time was above 0.02 Pa·s and below 0.4 Pa·s, and the shear rate was 0.01 s⁻¹. -1 The liquid is a pseudoplastic fluid with a viscosity of 0.5 Pa·s or more and 50 Pa·s or less. Attached Figure Description

[0009] Figure 1 This is a schematic diagram showing the overall structure of the liquid ejection device involved in the embodiment.

[0010] Figure 2 (a) is an exploded perspective view of the head of the liquid ejection device according to the embodiment. Figure 2(b) is a perspective view of the second flow path component included in the above-mentioned head.

[0011] Figure 3 (a) and Figure 3 (b) is a top perspective view of the head involved in the embodiment.

[0012] Figure 4 yes Figure 3 Enlarged view of region IV in (b).

[0013] Figure 5 This is a perspective view of the individual flow path of the head involved in the implementation method.

[0014] Figure 6 (a) is Figure 5 A cross-sectional view at line VIa-VIa. Figure 6 (b) is Figure 5 A cross-sectional view at line VIb-VIb.

[0015] Figure 7 This is a diagram showing the characteristics of the liquid used in the liquid ejection device according to the embodiment.

[0016] Figure 8 This is a diagram illustrating an example of the average viscosity at each part of the flow path involved in the implementation method.

[0017] Figure 9 This is a schematic cross-sectional view of a single flow path involved in the variation.

[0018] -Explanation of Figure Markers-

[0019] 1...Liquid ejection device, 3...Head, 13...Flow setting unit, 19...Flow path component, 21...Actuator, 29...Supply reservoir, 31...Recovery reservoir, 33...Supply manifold, 37...Recovery manifold, 39...Supply flow path, 41...Pressure chamber, 43...Nozzle, 45...Recovery flow path. Detailed Implementation

[0020] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. Please note that the following drawings are schematic; therefore, details are sometimes omitted. Furthermore, the size ratios may not correspond to actual size ratios. The size ratios of multiple drawings may also not be consistent with each other. Sometimes specific dimensions are larger than actual dimensions, and specific shapes are exaggerated.

[0021] In the accompanying drawings, arrows are sometimes used to indicate directions D1 to D6. These directions are parallel to the ejection surface 3a, which will be described later. Furthermore, directions D2 and D5, for example, are parallel to the long side of the head 3, which will be described later, and are, from another viewpoint, the so-called main scanning directions. Directions D3 and D6 are orthogonal to directions D2 and D5. Directions D1 and D4 are inclined relative to directions D3 and D6.

[0022] (Overall structure of the liquid ejection device)

[0023] Figure 1 This is a schematic diagram showing the main structural parts of the liquid ejection device 1 (hereinafter, sometimes referred to as "ejection device 1") according to the embodiment.

[0024] For example, like an inkjet printer, the ejection device 1 is configured to cause liquid to adhere to the surface of the object 101 by ejecting droplets from the ejection surface 3a of the head 3 toward the object 101. Furthermore, the ejection surface 3a may face any direction relative to the vertical direction, but in the following description, for convenience, the direction in which the ejection surface 3a faces will sometimes be referred to as downward, using terms such as upper surface or lower surface.

[0025] The specific type (application) of the ink ejector 1 can be set to an appropriate type (application). For example, the ink ejector 1 can be a device that prints text and graphics (records information from other perspectives) by adhering ink to a recording medium (e.g., paper) that is the object 101. That is, the ink ejector 1 can be a printer, as commonly understood. Furthermore, for example, the ink ejector 1 can also be a device that decorates the body of a car, which is the object 101, by adhering paint to it. Furthermore, for example, the ink ejector 1 can also be a device that forms wiring by adhering a liquid including conductive particles to a circuit board that is the object 101.

[0026] Furthermore, unlike the example illustrated, the spraying device 1 may not be a device for adhering liquid to the object 101. For example, the spraying device 1 may be a device for spraying liquid chemicals that react with substances inside a container into the container, or it may be a device for dispersing disinfectant into the atmosphere.

[0027] As can be understood from the examples of specific types of ejection devices 1 described above, the material, shape, and size of the object 101 can be appropriately set. Figure 1This is a schematic diagram, therefore the object 101 is represented by a cuboid. Examples of materials for the object 101 include paper, cloth, resin, metal, ceramics, and wood, as well as combinations thereof. Examples of types of the object 101 include recording media (e.g., rolls of paper or sheets of paper), circuit boards, clothing, beverage containers, storage containers, housings of electronic devices, and automobile bodies. The object 101, or the area therein with liquid adhering to it, can be narrower or wider than the ejection surface 3a from which the liquid droplets are ejected.

[0028] Furthermore, as can be understood from the examples of specific types of ejection devices 1 described above, the type of liquid can also be appropriately set. Examples of liquid types include ink, paint, liquids containing conductive particles, chemicals, and disinfectants. Ink and paint are sometimes distinguished based on the presence or absence of organic solvents and / or the presence or absence of a protective function on the surface of the object 101. However, such distinction may not be made. In the following description, paint may be appropriately replaced with ink. Conversely, paint may not be used. Paint may include pigments for coloring purposes, or it may not include pigments (e.g., only for imparting gloss and / or protecting the object 101) if it is not for coloring purposes.

[0029] The ejection device 1 includes, for example, a head 3 for ejecting droplets and a moving part 5 for moving the head 3 relative to an object 101. The head 3 has an ejection surface 3a with multiple nozzles (described later) opening for ejecting droplets. The moving part 5, for example, maintains the ejection surface 3a facing the surface of the object 101 while moving both relative to each other along the ejection surface 3a and the surface of the object 101. The direction of relative movement is, for example, the D3 direction or the D6 direction. As understood from an inkjet printer, which is a specific example of the ejection device 1, droplets are ejected from the ejection surface 3a in sync with the relative movement described above, so that the droplets adhere to an area larger than the area of ​​the multiple nozzles.

[0030] Furthermore, the dispensing device 1 includes, for example, a tank 7 for storing liquid. The head 3 has a supply port 3b for supplying liquid from the tank 7 to the head 3 and a recovery port 3c for recovering liquid from the head 3 to the tank 7. That is, the liquid circulates in the head 3 and the tank 7. By circulating the liquid in this way, the possibility of liquid remaining in the head 3 is reduced. Furthermore, the possibility of the retained liquid solidifying or the precipitation of components within the retained liquid can be reduced. In addition, in this embodiment, by circulating the liquid, as described later, the shear rate of the liquid can be adjusted, and thus the viscosity of the liquid can be adjusted.

[0031] The ejection device 1 includes: a circulation operation unit 9 that applies pressure to the liquid to circulate it; and a control unit 11 that controls each component (e.g., the head 3, the moving part 5, and the circulation operation unit 9). Furthermore, the combination of the circulation operation unit 9 and the control unit 11 can also be considered as a flow rate setting unit 13 that sets the flow rate (hereinafter referred to as the circulation flow rate) of the liquid circulating in the head 3. The circulation flow rate can, for example, be considered to be the same as the flow rate of the liquid flowing out from the recovery port 3c to the outside of the head 3.

[0032] The ejection device 1 can have only one head 3 (and canister 7), like a monochrome printer, or it can have multiple heads 3 (and multiple canisters 7) that eject different types of liquids, like a color printer. Alternatively, the ejection device 1 can have multiple heads 3 that eject the same type of liquid. Having multiple heads 3 that eject the same type of liquid can, for example, help to shorten the time it takes for the liquid to adhere to a fixed area, or to increase the ink droplet density. In the following description, for convenience, only one head 3 will be mentioned.

[0033] (Mobility Department)

[0034] The moving part 5 can, for example, move the object 101 relative to the head 3 at least in one of the D3 and D6 directions. As described above, this direction is the direction of movement when ejecting droplets, and is the so-called sub-scanning direction. The moving part 5 can also realize relative movement between the head 3 and the object 101 in directions other than the D3 and D6 directions. Examples of other directions in which relative movement can be realized include the D2 and D5 directions, which are orthogonal to the D3 and D6 directions, and the directions orthogonal to the ejection surface 3a (directions that bring the head 3 and the object 101 closer together and directions that move them away from each other). Furthermore, the moving part 5 can also realize relative rotation between the head 3 and the object 101.

[0035] The moving part 5 can move only the object 101, only the head 3, or both in the absolute coordinate system. Furthermore, the specific structure of the moving part 5 can be appropriately set according to the specific type of the ejection device 1.

[0036] For example, if the ejector device 1 is a so-called line printer, the moving part 5 may also be configured as a device for conveying the recording medium (e.g., paper) that is the object 101. This device may include, for example, multiple rollers that generate friction in contact with the recording medium and an electric motor that rotates the multiple rollers. Furthermore, for example, if the ejector device 1 is a so-called serial printer, the moving part 5 may include: a device for conveying the recording medium that is the object 101 in a given conveying direction; and a device for moving the head 3 in a direction orthogonal to the conveying direction and along the direction of the recording medium.

[0037] Furthermore, for example, the ejection device 1 may include a belt conveyor for transporting any type of object 101. Furthermore, for example, the ejection device 1 may include a movable worktable for loading any type of object 101. Furthermore, for example, the ejection device 1 may include an industrial robot for moving any type of object 101 and / or an industrial robot for moving the head 3. Examples of industrial robots include, for example, vertical articulated robots (articulated robots in the narrow sense), horizontal articulated robots, Cartesian robots, and parallel linkage robots.

[0038] (The can and the circulating mechanism)

[0039] The canister 7 and the circulation action unit 9 may be the same as, for example, the canister and circulation action unit in a known inkjet printer that circulates liquid, or the known canister and circulation action unit may be used.

[0040] For example, tank 7 can also be a structure that houses the liquid supplied to head 3 and the liquid recovered from head 3 in the same space. Alternatively, tank 7 can be a structure that houses the liquid supplied to head 3 and the liquid recovered from head 3 in different spaces, allowing the liquid to flow from the latter space to the former space. In this case, tank 7 can have two spaces by being divided into one tank by a partition, or it can have two spaces by having two tanks interconnected by a flow path. The space inside tank 7 (as described above) can be open to the atmosphere, but can be electrically sealed. In the latter case, the pressure inside tank 7 can also be adjusted to an appropriate pressure by a valve or a vacuum pump. Tank 7 can also have a main tank and a sub-tank with a smaller capacity than the main tank. The sub-tank mediates between the main tank and head 3.

[0041] In the illustrated example, the circulation unit 9 includes: a pump 15 that delivers liquid from tank 7 to head 3; a pressure sensor 17A that detects the pressure of the liquid at the supply port 3b; and a pressure sensor 17B that detects the pressure of the liquid at the recovery port 3c. The control unit 11, for example, performs feedback control on the pump 15 based on the detection values ​​of pressure sensors 17A and 17B, so that the pressure difference between the supply port 3b and the recovery port 3c converges to a given target value. Thus, the circulation flow rate is feedback-controlled to the target flow rate.

[0042] Unlike the example shown, pump 15 on the supply port 3b side can be replaced, or a pump 15 that delivers liquid from the recovery port 3c to the tank 7 can be installed. Alternatively, pump 15 that delivers liquid can be replaced, or the flow of liquid can be generated by pressure control within the tank 7 using a vacuum pump or the like. Liquid flow can also be generated by making the liquid level in the tank containing the supply liquid higher than the liquid level in the tank containing the recovered liquid.

[0043] Instead of pressure sensors 17A and 17B, or based on these, flow sensors that detect the flow rate of liquid supplied to head 3 and / or the flow rate of liquid recovered from head 3 can be installed and used for circulating flow control. Furthermore, as understood from the various ways in which the aforementioned liquid flow is generated, sensors that detect the air pressure within tank 7 can be installed instead of these sensors for circulating flow control. Alternatively, open-loop control can be performed without sensor-based feedback control. That is, sensors may not be installed at all.

[0044] The can 7 and the circulation unit 9 do not move in the absolute coordinate system, for example, via the moving part 5. Therefore, for example, in the case where the moving part 5 moves the head 3 in the absolute coordinate system, the head 3 moves relative to the can 7 and the circulation unit 9. In this case, the head 3 is connected to the can 7 and the circulation unit 9 via a flow path, for example, formed by a flexible tube. Furthermore, in the case where the moving part 5 does not move the head 3 in the absolute coordinate system, the head 3 is fixed relative to the can 7 and the circulation unit 9. In this case, the structure of the flow path connecting the head 3 to the can 7 and the circulation unit 9 is arbitrary. Contrary to the above description, all or part of the can 7 and the circulation unit 9 may also move together with the head 3.

[0045] (Control Department)

[0046] The control unit 11 is, for example, a computer. Although not specifically illustrated, a computer has a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), and external storage devices. The CPU executes programs stored in the ROM and / or external storage devices, thereby controlling the head 3, the movement unit 5, and the loop operation unit 9.

[0047] (head)

[0048] Figure 2 (a) is the exploded stereograph of the first 3.

[0049] The head 3 has: flow path component 19 (reference numeral in the figure) Figure 1 ), having a flow path for liquid flow; an actuator 21, applying pressure to the liquid within the flow path member 19; and a signal transmission member 23 (in Figure 1 (Illustrations omitted) are used to input drive signals to actuator 21. Flow path member 19 has: a first flow path member 25 having an ejection surface 3a; and a second flow path member 27 having a supply port 3b and a recovery port 3c. Sometimes the surface of the first flow path member 25 opposite to the ejection surface 3a is referred to as the pressurizing surface 25a.

[0050] The first flow path member 25 and the second flow path member 27 are each configured as a generally flat plate, and are overlapped to form a generally flat flow path member 19. Liquid supplied to the supply port 3b is supplied from the second flow path member 27 to the first flow path member 25, and then ejected from the ejection surface 3a. Liquid that is not ejected and remains flows from the first flow path member 25 to the second flow path member 27 and is recovered from the recovery port 3c.

[0051] The control unit 11 outputs a control signal based on given data such as image data. The control signal is input, for example, via a signal transmission member 23 to a driver (not shown) mounted on the signal transmission member 23. This driver generates a drive signal with a given waveform based on the input control signal. This drive signal is input to the actuator 21 via the signal transmission member 23. The actuator 21 applies pressure to the liquid within the flow path member 19 with a pressure waveform corresponding to the waveform of the drive signal. As a result, the liquid within the flow path member 19 is ejected from the ejection surface 3a. Furthermore, the division of labor between the control unit 11 and the driver can be appropriately configured; moreover, the driver can also be understood as part of the control unit 11.

[0052] (Second flow path components, supply reservoir, and recovery reservoir)

[0053] Figure 2 (b) is a perspective view of the second flow path component 27. More specifically, this view is a perspective view of the second flow path component 27 viewed from the side of the first flow path component 25. Figure 2 The upper part of the paper in (b) corresponds to Figure 1 as well as Figure 2 (a) is below the paper. Figure 3 (a) is a top perspective view of the head 3 viewed from the side opposite to the ejection surface 3a. In this figure, the shape of the second flow path component 27 and the actuator 21 are shown.

[0054] like Figure 2 As shown in (b), the second flow path member 27 has two grooves (refer to reference numerals 29 and 31) formed on the surface of the first flow path member 25. These two grooves are blocked by the first flow path member 25, constituting Figure 2 (b) and Figure 3 The image (a) shows a supply reservoir 29 and a recovery reservoir 31. The supply reservoir 29 is a flow path that communicates with the supply port 3b and supplies the liquid supplied to the supply port 3b to the flow path of the first flow path member 25. The recovery reservoir 31 is a flow path that communicates with the recovery port 3c, recovers liquid from the flow path of the first flow path member 25, and guides the recovered liquid to the recovery port 3c.

[0055] The supply reservoir 29 and the recovery reservoir 31, for example, have portions (main sections 29a and 31a) that extend in a straight line along the long side direction (D2 direction and D5 direction) of the head 3. The main sections 29a and 31a, for example, have configuration areas covering multiple nozzles (described later) (see here). Figure 3 The length of the entire length of the long side direction (D2 and D5 directions) of the arrangement area of ​​actuator 21 (a). Furthermore, the main sections 29a and 31a are located on opposite sides (D3 and D6 directions) of the short side direction of the head 3 relative to the arrangement areas of the plurality of nozzles. In the description of the embodiment, for convenience, only the main sections 29a and 31a are considered; the shape and size of the supply reservoir 29 and the recovery reservoir 31 are sometimes described.

[0056] Supply port 3b is connected, for example, to one end (the end in the D2 direction) of supply reservoir 29. The other end (the end in the D5 direction) of supply reservoir 29 is a dead end (in other words, a dead end). Liquid in supply reservoir 29 flows from one end to the other end in the D5 direction. Recovery port 3c is connected, for example, to one end (the end in the D5 direction) of recovery reservoir 31. The other end (the end in the D2 direction) of recovery reservoir 31 is a dead end (in other words, a dead end). Liquid in recovery reservoir 31 flows from the other end to the one end in the D5 direction. The direction of liquid flow in supply reservoir 29 and the direction of liquid flow in recovery reservoir 31 are the same in the illustrated example. However, they can also be opposite to each other.

[0057] The supply reservoir 29 may have only the main portion 29a, or it may have other portions. In the illustrated example, the supply reservoir 29 has a portion that extends obliquely from the main portion 29a toward the long side of the head 3 to reach the supply port 3b (reference numerals omitted). Similarly, the recovery reservoir 31 may have only the main portion 31a, or it may have other portions. In the illustrated example, the recovery reservoir 31 has a portion that extends obliquely from the main portion 31a toward the long side of the head 3 to reach the recovery port 3c (reference numerals omitted).

[0058] The shape and dimensions of the cross-sections of the supply reservoir 29 and the recovery reservoir 31 (e.g., the main portions 29a and 31a therein) can be fixed regardless of their position along the length of these flow paths, or they can vary depending on their position. In the description of the embodiments, the former is sometimes used as an example. Furthermore, the shape of the cross-section can be a suitable shape such as a rectangle. The various dimensions of the supply reservoir 29 and the recovery reservoir 31 can be appropriately set according to the specific technical field in which the ejection device 1 is applied.

[0059] In the illustrated example, the second flow path component 27, in addition to serving as two slots for the supply reservoir 29 and the recovery reservoir 31, also has a slit 27a through which the signal transmission component 23 is inserted. Figure 2 (a) and Figure 2 (b)), and the recess 27b that houses the actuator 21 ( Figure 2 (b) and Figure 3 (a)). The slit 27a, for example, extends the second flow path member 27 from the side of the first flow path member 25 to the opposite side, and also extends along the long side of the head 3. The recess 27b, for example, has a planar shape that is larger than the actuator 21, and in the illustrated example, it is a rectangle with the long side of the head 3 as its long side.

[0060] The material of the second flow path component 27 is arbitrary. For example, the second flow path component 27 may be made of metal, resin, or ceramic, or a combination thereof.

[0061] (First flow path component)

[0062] Figure 3 (b) is a top perspective view of the head 3. In this figure, the shape of the first flow path component 25 and the actuator 21 are shown. Furthermore, Figure 4 yes Figure 3 Enlarged view of region IV in (b).

[0063] The flow path of the first flow path component 25 has multiple supply manifolds 33 from which liquid is supplied from the supply reservoir 29 and multiple individual flow paths 35 from which liquid is supplied from the supply manifolds 33. Each individual flow path 35 includes a nozzle (described later) that ejects droplets from the ejection surface 3a. Furthermore, the flow path of the first flow path component 25 has multiple recovery manifolds 37 that recover liquid from the multiple individual flow paths 35 and guide the recovered liquid to the recovery reservoir 31.

[0064] Although not specifically illustrated, the first flow path component 25 may also have flow paths located in the D2 and D5 directions relative to the multiple supply manifolds 33, multiple individual flow paths 35, and multiple recovery manifolds 37, connecting the supply reservoir 29 and the recovery reservoir 31. Such flow paths, for example, help to homogenize the temperature of the first flow path component 25.

[0065] (manifold)

[0066] The supply manifold 33, for example, has a main portion 33a extending linearly along the D4 direction from the supply reservoir 29 side to the recovery reservoir 31 side (in the illustrated example, this corresponds to approximately the entire supply manifold 33). The D4 direction is inclined relative to the short side direction (D6 direction) of the head 3. Similarly, the recovery manifold 37, for example, has a main portion 37a extending linearly along the D1 direction from the recovery reservoir 31 side to the supply reservoir 29 side (in the illustrated example, this corresponds to approximately the entire recovery manifold 37). The D1 direction is inclined relative to the short side direction (D3 direction) of the head 3. In the description of the embodiment, for convenience, the shape and size of the supply manifold 33 and the recovery manifold 37 are sometimes described only with reference to the main portions 33a and 37a.

[0067] One end of the supply manifold 33 (the end in the D1 direction) overlaps with the supply reservoir 29 in a top-view perspective. This end communicates with the supply reservoir 29 via an opening 33b on the surface of the first flow path member 25 on the side of the second flow path member 27. The other end of the supply manifold 33 (the end in the D4 direction) is an end. Therefore, liquid from the supply reservoir 29 is supplied to the aforementioned end of the supply manifold 33 via the opening 33b and flows within the supply manifold 33 from the aforementioned end to the other end in the D4 direction.

[0068] One end of the recovery manifold 37 (the end in the D4 direction) overlaps with the recovery reservoir 31 in a top-view perspective. This end communicates with the recovery reservoir 31 via an opening 37b on the surface of the first flow path member 25 on the side of the second flow path member 27. The other end of the recovery manifold 37 (the end in the D1 direction) is an end. Therefore, the liquid in the recovery manifold 37 flows from the other end toward the first end in the D4 direction and is recovered into the recovery reservoir 31 via the opening 37b.

[0069] The supply manifold 33 and the recovery manifold 37 have a length extending along the short side (in the D3 and D6 directions) of the arrangement area covering the plurality of nozzles (described later) (here, the arrangement area of ​​the actuator 21). Furthermore, the end of the supply manifold 33 on the recovery reservoir 31 side (the end in the D4 direction) is, for example, located closer to the supply reservoir 29 side than the recovery reservoir 31. Similarly, the end of the recovery manifold 37 on the supply reservoir 29 side (the end in the D1 direction) is, for example, located closer to the recovery reservoir 31 side than the supply reservoir 29.

[0070] The multiple supply manifolds 33 are, for example, identical in structure and arranged at a fixed interval along the D2 direction. In other words, the multiple supply manifolds 33 extend parallel to each other with the same length. The multiple supply manifolds 33 are arranged at a fixed interval along the supply reservoir 29 at their connection points (openings 33b) relative to the supply reservoir 29.

[0071] Similarly, the multiple recovery manifolds 37 are, for example, identical in structure to each other, and are arranged at a fixed spacing along the D2 direction. In other words, the multiple recovery manifolds 37 extend parallel to each other with the same length. The connection points (openings 37b) of the multiple recovery manifolds 37 relative to the recovery reservoir 31 are arranged at a fixed spacing along the recovery reservoir 31.

[0072] Multiple supply manifolds 33 and multiple recovery manifolds 37 are arranged alternately, for example, at a fixed interval. Furthermore, the supply manifolds 33 and recovery manifolds 37 are adjacent to each other and extend parallel to each other. More specifically, most of the supply manifolds 33 (excluding the upstream side) and most of the recovery manifolds 37 (excluding the downstream side) are adjacent to each other in the area where the multiple nozzles are arranged.

[0073] The shape and size of the cross-sections of the supply manifold 33 and the recovery manifold 37 (e.g., the main portions 33a and 37a therein) can be fixed regardless of their position along the length of the flow paths, or they can vary depending on their position. In the description of the embodiments, the former is sometimes used as an example. Furthermore, the shape of the cross-section can be a suitable shape such as a rectangle. The various dimensions of the supply manifold 33 and the recovery manifold 37 can be appropriately set according to the specific technical field in which the ejection device 1 is applied.

[0074] (Separate flow path)

[0075] Individual flow paths 35 are located, for example, between and connected to adjacent supply manifolds 33 and recovery manifolds 37. Multiple individual flow paths 35 are provided for each set of manifolds (33 and 37). Multiple individual flow paths 35 connected to the same manifolds (33 and 37) are arranged, for example, at a fixed interval along the manifold (along the D1 direction), forming one flow path column. Furthermore, multiple flow path columns are arranged along the D2 direction to form a matrix configuration of multiple individual flow paths 35. Unlike the illustrated example, two or more columns of individual flow paths 35 may also be provided between adjacent supply manifolds 33 and recovery manifolds 37.

[0076] Within a flow path array, the structures of the multiple individual flow paths 35 are substantially identical. Furthermore, the structures of the multiple flow path arrays are also substantially identical to each other. For example, the orientation of the individual flow paths 35 may differ between adjacent flow path arrays (as illustrated in the example). Additionally, the shape and / or size of the multiple individual flow paths 35 within a flow path array may also differ slightly. The flow path arrays located at the ends in the D2 direction and the flow path arrays located at the ends in the D5 direction may also have so-called dummy individual flow paths that do not eject droplets.

[0077] Each flow path 35 has a nozzle 43 that opens at the ejection surface 3a and ejects droplets. A column formed by arranging multiple nozzles 43 along the D1 direction is called a nozzle column. The arrangement direction (D1 direction) of the nozzles 43 within a nozzle column is inclined relative to the direction of relative movement of the head 3 relative to the object 101 (D3 direction). Due to this inclination, the nozzles 43 belonging to the same nozzle column are positioned differently in the D2 direction. Furthermore, when viewed from the D3 direction, portions of the multiple nozzle columns overlap each other. In this overlapping portion, the nozzles 43 of one nozzle column are positioned differently in the D2 direction from the nozzles 43 of other nozzle columns. Moreover, when projecting the multiple nozzles 43 along the D3 direction, the multiple nozzles 43 are arranged at substantially a fixed interval in the D2 direction.

[0078] Therefore, multiple ink dots arranged in the D2 direction with a spacing shorter than the distance between adjacent nozzles 43 in the head 3 can be formed on the surface of the object 101. For example, 32 nozzles 43 are projected within the range of an imaginary straight line R, and the nozzles 43 are arranged at intervals of 360 dpi within the imaginary straight line R. Therefore, if the object 101 and the head 3 are moved relative to each other in a direction orthogonal to the imaginary straight line R to eject droplets, printing can be performed at a resolution of 360 dpi.

[0079] Figure 5 This is a 3D view of a single flow path 35. Furthermore, Figure 6 (a) and Figure 6 (b) is a cross-sectional view of the first flow path component 25 and the actuator 21. Figure 6 (a) and Figure 5 The corresponding line is VIa-VIa. Figure 6 (b) and Figure 5 The VIb-VIb line corresponds to this.

[0080] The separate flow path 35 includes, for example, a supply flow path 39 (first supply flow path 39A and second supply flow path 39B) connected to the supply manifold 33, a pressure chamber 41 connected to the supply flow path 39, and a nozzle 43 connected to the pressure chamber 41. As described above, the nozzle 43 is open at the ejection surface 3a and communicates with the outside of the first flow path member 25. Liquid from the supply manifold 33 is supplied to the nozzle 43 via the supply flow path 39 and the pressure chamber 41. Furthermore, by applying pressure to the pressure chamber 41 using the actuator 21, droplets are ejected from the nozzle 43. In addition, the separate flow path 35 has a recovery flow path 45 connecting the pressure chamber 41 and the recovery manifold 37. Liquid that is not ejected and remains in the pressure chamber 41 is recovered from the recovery flow path 45 to the recovery manifold 37.

[0081] Pressure chamber 41, for example, has a pressure chamber body 41a pressurized by actuator 21 and a descender 41b connecting pressure chamber body 41a and nozzle 43.

[0082] The pressure chamber body 41a has an opening, for example, in the pressurizing surface 25a of the first flow path member 25, which is blocked by the actuator 21. Furthermore, pressure is applied to the liquid within the pressure chamber body 41a by the upward and / or downward flexing deformation of the actuator 21. A descender 41b extends from the lower surface of the pressure chamber body 41a toward the ejection surface 3a. The cross-sectional area of ​​the descender 41b is smaller than the area of ​​the cross-section parallel to the pressurizing surface 25a of the pressure chamber body 41a.

[0083] The shape and dimensions of the pressure chamber body 41a can be appropriately set. In the illustrated example, the planar shape of the pressure chamber body 41a is circular. Unlike the illustrated example, the planar shape of the pressure chamber body 41a can also be, for example, an ellipse or a rhombus, other than a circle. Furthermore, the pressure chamber body 41a is formed as a thin shape with a thickness smaller than its diameter when viewed from above. In the illustrated example, the shape and dimensions of the cross-section parallel to the pressurizing surface 25a of the pressure chamber body 41a are fixed in the vertical direction. However, the shape and / or dimensions of the cross-section of the pressure chamber body 41a can also vary depending on its position in the vertical direction.

[0084] The shape and size of the descender 41b can also be appropriately set. In the illustrated example, the descender 41b is cylindrical. Furthermore, in the illustrated example, the cross-sectional shape is circular. Unlike the illustrated example, the descender 41b can be tilted relative to the vertical direction, or its diameter can vary depending on its vertical position. Additionally, the cross-sectional shape can also be other than a circle, such as an ellipse.

[0085] The connection position of the descender 41b relative to the pressure chamber body 41a when viewed from above can also be appropriately set. In the illustrated example, the descender 41b is connected adjacent to the outer edge of the circular pressure chamber body 41a. Unlike the illustrated example, if the pressure chamber body 41a is elliptical or rhomboid in shape, for example, the descender 41b can be connected to the end of the long side of the pressure chamber body 41a.

[0086] Nozzle 43 opens on a portion of the bottom surface of descender 41b. Nozzle 43 may open at the center of the bottom surface of descender 41b, or it may open at a location away from the center (as illustrated in the example). The longitudinal cross-section of nozzle 43 is a cone shape, with the diameter decreasing towards the ejection surface 3a. Part or all of nozzle 43 may also be an inverted cone shape. The cross-sectional shape of nozzle 43 may be, for example, circular.

[0087] The supply flow path 39 may have, for example, a first supply flow path 39A and a second supply flow path 39B. Unlike the illustrated example, the supply flow path 39 may also have only one of the first supply flow path 39A and the second supply flow path 39B. In the supply flow path 39, the connection position relative to the supply manifold 33, the connection position relative to the pressure chamber 41, the flow path shape, and the dimensions can be appropriately set. In the illustrated example, this is described below.

[0088] The first supply flow path 39A connects the supply manifold 33 to the pressure chamber body 41a. The first supply flow path 39A extends upward from the upper surface of the supply manifold 33, then extends in the D5 direction, then in the D4 direction, and finally extends upward again to connect with the lower surface of the pressure chamber body 41a. The shape and dimensions of the cross-section of the first supply flow path 39A are substantially fixed for most of its length (e.g., more than 60%). The cross-sectional shape for this majority of the length is rectangular.

[0089] The second supply flow path 39B connects the supply manifold 33 to the descender 41b. The second supply flow path 39B extends from the lower surface of the supply manifold 33 in the D5 direction, then extends in the D1 direction and connects to the side of the descender 41b. The shape and dimensions of the cross-section of the second supply flow path 39B are substantially fixed for most of its length (e.g., more than 60%). The cross-section covering this majority of its length is rectangular.

[0090] For example, only one recovery flow path 45 is provided in a single flow path 35. Unlike the illustrated example, more than two recovery flow paths 45 may also be provided. In the recovery flow path 45, the connection position relative to the recovery manifold 37, the connection position relative to the pressure chamber 41, the flow path shape, and the dimensions can be appropriately set. In the illustrated example, this is described below.

[0091] The recovery flow path 45 connects the recovery manifold 37 to the descender 41b. The recovery flow path 45 extends from the side of the recovery manifold 37 in the D2 direction and then in the D4 direction before connecting to the side of the descender 41b. The shape and dimensions of the cross-section of the recovery flow path 45 are substantially fixed for most of its length (e.g., more than 60%). The cross-sectional shape for this majority of the length is rectangular.

[0092] As described above, multiple individual flow paths 35 connected to the same supply manifold 33 and the same recovery manifold 37 are arranged along the manifold at fixed intervals. Therefore, the connection positions of the first supply flow path 39A and the supply manifold 33 are arranged along the supply manifold 33 at fixed intervals. The connection positions of the second supply flow path 39B and the supply manifold 33, as well as the connection positions of the recovery flow path 45 and the recovery manifold 37, are also the same.

[0093] like Figure 6 (a) and Figure 6 As shown in (b), the first flow path member 25 is formed by stacking multiple plates 47A to 47M. Various flow paths of the first flow path member 25 are formed in holes or recesses in the plates 47A to 47M. The multiple plates 47A to 47M can be formed, for example, of metal or resin. Figure 6 In the example shown in (b), baffles are provided above and below the recovery manifold 37 (reference numerals omitted).

[0094] As described above, the pressure chamber 41 opens at the pressurized surface 25a. Unlike the illustrated example, a plate may also be provided to block the pressure chamber 41. In this case, it is possible to consider the plate blocking the pressure chamber 41 as part of the first flow path member 25, or as part of the actuator 21. In the description of this disclosure, the plate described above is understood as part of the actuator 21.

[0095] (Actuator)

[0096] like Figure 2 As shown in (a), the actuator 21 is, for example, a generally flat plate-shaped component, with the pressure surface 25a of the first flow path component 25 (more specifically, in...) Figure 2 The area shown by the dashed line in (a) is joined. Then, as... Figure 6 (a) and Figure 6 As shown in (b), actuator 21 blocks the opening above pressure chamber 41. Actuator 21 extends substantially throughout the entire configuration area of ​​pressure chamber 41. Actuator 21 has a displacement element 49 in each pressure chamber 41.

[0097] The actuator 21 can have various known structures and apply well-known structures. In the illustrated example, the actuator 21 is a so-called unimorph piezoelectric actuator. Details are as follows.

[0098] The actuator 21 has a vibrating plate 51, a common electrode 53, a piezoelectric layer 55, and individual electrodes 57 stacked sequentially from the pressure chamber 41 side. The vibrating plate 51, the common electrode 53, and the piezoelectric layer 55 extend substantially throughout the entire configuration area of ​​the pressure chamber 41. The individual electrodes 57 are provided for each pressure chamber 41. The individual electrodes 57 have, for example, a shape similar to the planar shape of the pressure chamber 41 in a top view, and further overlap with the central side of the pressure chamber 41.

[0099] The portion of the piezoelectric layer 55 sandwiched between the individual electrode 57 and the common electrode 53 is polarized in the thickness direction. Therefore, when a voltage is applied to the individual electrode 57 and the common electrode 53, the piezoelectric layer 55 contracts or elongates in the direction along its surface. This contraction or elongation is limited by the vibrating plate 51, and the displacement element 49 flexes towards the pressure chamber 41 side or the opposite side, like a bimetal. This applies pressure to the liquid within the pressure chamber 41.

[0100] The materials and thicknesses of each layer of actuator 21 can be appropriately set. For example, the vibrating plate 51 and the piezoelectric layer 55 can be made of lead zirconate titanate (PZT), NaNbO3, BaTiO3, (BiNa)NbO3, or BiNaNb5O3. 15 It is made of ceramic materials such as Ag-Pd or Au. The common electrode 53 and the individual electrode 57 can be made of metallic materials such as Ag-Pd or Au.

[0101] The common electrode 53 is, for example, given a fixed potential (reference potential). The individual electrode 57 is, for example, input with the drive signal described above. The driving mode of the displacement element 49 (from another viewpoint, the waveform of the drive signal) can be suitably configured. For example, the driving mode can be configured as a so-called traction mode.

[0102] (liquid)

[0103] Figure 7 This is a graph showing the characteristics of the liquid used in the ejection device 1. In this graph, the horizontal axis represents the shear rate D (1 / s), and the vertical axis represents the viscosity η (Pa·s). EX1 and EX2 show the characteristics of a first example and a second example of the liquid used in the ejection device 1.

[0104] As shown in the figure, the liquid used by the ejection device 1 is a pseudoplastic fluid. In definitive terms, a pseudoplastic fluid can be described as a non-Newtonian fluid whose viscosity decreases with increasing shear rate. Shear rate is sometimes also called shear velocity, velocity gradient, or strain rate. Shear rate can be easily calculated, for example, by dividing the velocity difference between two mutually separated locations in a direction orthogonal to the flow direction by the distance between the two locations. Viscosity can be easily calculated, for example, by dividing the shear stress by the shear rate. Shear stress is sometimes also called shear stress. Shear stress can be easily calculated by dividing the force exerted on two parallel surfaces (of the same area) separated in a direction orthogonal to the flow direction by the area of ​​one surface.

[0105] Furthermore, a pseudoplastic fluid can be described as having a viscosity η of η = k × D p-1A power-law fluid is a fluid for which the power exponent p is less than 1 when approximated using the power law. Here, k is the viscosity coefficient, and D is the shear rate. Furthermore, the viscosity η is a function of D, and is therefore sometimes referred to as apparent viscosity.

[0106] The liquid used in the ejection device 1 can have thixotropic properties, where the viscosity decreases as the shear stress is applied for a longer period of time, or it can not have thixotropic properties.

[0107] The specific composition and / or structure of a pseudoplastic fluid can be derived from a variety of well-known components and / or compositions. For example, inks and coatings are typically pseudoplastic fluids. Figure 7 The liquids shown in the first and second examples are common coatings (in other words, commercially available coatings). The specific properties of pseudoplastic fluids can also be appropriately set. An example is given below.

[0108] For example, the liquid can be set to a shear rate of 1000 s. -1 Liquids with a viscosity of 0.02 Pa·s or higher and 0.4 Pa·s or lower. Additionally, in Figure 7 In the first example of the coatings shown, the shear rate is 1000 s. -1 The viscosity at that time was 0.3 Pa·s. In the coating involved in the second example, the shear rate was 1000 s. -1 The viscosity at that time is 0.1 Pa·s. The liquid can also be set to a shear rate of 1000 s⁻¹. -1 The viscosity at that time is above 0.1 Pa·s and below 0.3 Pa·s.

[0109] Furthermore, for example, the liquid can be set to a shear rate of 0.01 s. -1 The viscosity at that time was above 0.5 Pa·s and below 50 Pa·s. Additionally, in... Figure 7 In the first example of the coatings shown, the shear rate was 0.01 s. -1 The viscosity at that time was 5 Pa·s. In the coating involved in the second example, the shear rate was 0.01 s. -1 The viscosity at that time was 30 Pa·s. The liquid can be set to a shear rate of 0.01 s⁻¹. -1 The viscosity at that time is above 5 Pa·s and below 30 Pa·s.

[0110] Furthermore, for example, when approximating viscosity using a power law, the viscosity coefficient k of the liquid can be greater than or equal to 1.0 and less than 1.5, and the power exponent p can be greater than or equal to 0.35 and less than 0.65. In the coating involved in the first example, the viscosity coefficient k is 1.0 and the power exponent p is 0.65. In the coating involved in the second example, the viscosity coefficient k is 1.5 and the power exponent p is 0.35. The approximation formula can be determined, for example, using the least squares method.

[0111] (Average viscosity)

[0112] The concept of average viscosity is introduced below. Normally, viscosity exhibits different values ​​in each tiny region within the flow path. However, the viscosity of each tiny region may not be suitable for setting the viscosity of the liquid within the flow path component 19, and its calculation is also difficult. Therefore, the viscosity averaged across each part of the flow path of the flow path component 19 is called the average viscosity. The average viscosity is a value relative to a single part within the flow path. For example, the average viscosity referred to as the average viscosity of one supply manifold 33 is the average viscosity of the entire supply manifold 33.

[0113] The average viscosity can be calculated, for example, as follows. First, determine the relationship between the shear rate D and the viscosity η in the liquid used in the ejection device 1. This determination can be made using various known methods, or by referring to well-known literature. Next, derive an approximate expression representing the determined relationship between the shear rate D and the viscosity η. The approximate expression can be a suitable mathematical formula, such as the power law. The fitting method can also be a known method, such as the least squares method. Next, the circulation flow rate U (m³ / s) is... 3 Using the boundary condition ( / s), the fluid simulation of each part of the flow path is performed using the above approximation to obtain the differential pressure ΔP (Pa) between the upstream and downstream ends of each part. Then, the circulation flow rate U, differential pressure ΔP, and the dimensions (m) of each part are substituted into the given mathematical formula to calculate the average viscosity μ (Pa·s).

[0114] The following is an example of the mathematical formula used to calculate the average viscosity μ.

[0115] The mathematical formula for the case where the flow path shape is cylindrical with the flow direction as the axis is as follows.

[0116] U=(πr 4 ΔP) / (8μL) (1)

[0117] Here, r is the radius of the cross-section, and L is the length of the flow path.

[0118] Furthermore, the mathematical formula for the case where the flow path shape is a prism (cubic prism) with the flow direction as the axis is as follows.

[0119] U=(w 3 hΔP) / (4μL)

[0120] ×(16 / 3-1024 / π 5 ×w / h

[0121] ×∑(1 / q 5 ×tanh(qπh / 2w)) (2)

[0122] Here, q = 1, 3, 5, 7, 9, and 11, and ∑ represents the six (1 / q) values ​​when these six values ​​are substituted into q. 5 The sum of (×tanh(qπh / 2w)). w is the width of the flow path. h is the height of the flow path. L is the length of the flow path.

[0123] In the reservoirs (29 and 31) and manifolds (33 and 37), the flow rate U differs on the upstream and downstream sides. In this case, for example, any of the maximum flow rate, minimum flow rate, or average flow rate can be used. The average viscosity described below can be understood as the average viscosity calculated using any of the above-mentioned flow rates. Furthermore, when comparing the average viscosity of the reservoirs (29 and 31) and the average viscosity of the manifolds (33 and 37), the average viscosities calculated under the same conditions can be compared. For example, the average viscosity calculated using the maximum flow rate (lowest average viscosity) can be compared, the average viscosity calculated using the minimum flow rate (highest average viscosity) can be compared, or the average viscosity calculated using the average flow rate (average average viscosity) can be compared. For example, the average viscosity described below can be understood as the average viscosity calculated using the maximum flow rate (lowest average viscosity). For example, the average viscosity supplied to reservoir 29 and supply manifold 33 can be understood as being calculated using the upstream flow rate. The average viscosity of the recovery reservoir 31 and the recovery manifold 37 can be understood as the average viscosity calculated using the downstream flow rate.

[0124] In pressure chamber 41, pressure chamber body 41a, or downcomer 41b, the direction of liquid flow is not fixed. The average viscosity of these parts described below is calculated with the flow direction from top to bottom as the flow direction. For example, the average viscosity of downcomer 41b is calculated with the flow direction from pressure chamber body 41a to nozzle 43 as the flow direction.

[0125] (Average viscosity of flow path components)

[0126] Figure 8 This is a diagram illustrating an example of the relative relationships between the average viscosity μ of each part of the flow path in the flow path component 19. In this diagram, the horizontal axis corresponds to multiple parts of the flow path in the flow path component 19. The vertical axis represents the average viscosity μ of each part.

[0127] Additionally, in the figure, the average viscosity μ2 represents the average viscosity μ in one of the multiple supply manifolds 33. Similarly, the average viscosity μ in one flow path is represented for the other flow paths. The average viscosity μ3 of the supply flow path 39 can also be understood as any average viscosity in the first supply flow path 39A and the second supply flow path 39B.

[0128] The liquid ejection device 1 sets the target flow rate of the circulating flow rate controlled by the flow rate setting unit 13, and the shape and size of the flow path of the flow path member 19, so as to satisfy the average viscosity relationship shown in the figure. In other words, the flow path of the flow path member 19 has the following properties when the circulating flow rate is the target flow rate: Figure 8 The flow path shape that establishes the relationship shown. In other words, in the shape and dimensions of the flow path of flow path component 19, the circulation flow rate is set to... Figure 8 The value showing the relationship between average viscosity and the given value. For example, in the shape and size of the flow path in the flow path component 19, the circulation flow rate is set such that the average viscosity of the liquid supplied to the flow path 39 is less than half the average viscosity of the liquid supplied to the manifold 33.

[0129] When the circulating flow rate is adjusted in open-loop control, the fluctuation in circulating flow rate caused by the amount of droplets ejected from multiple nozzles 43 is large. In this case, Figure 8 The relationship shown can, for example, hold true for the circulating flow rate during periods when droplets are not ejected from all nozzles 43. In other words, in an implemented product, the circulating flow rate during periods when droplets are not ejected from all nozzles 43 can be determined as the target flow rate in that product. This idea can also be applied to feedback control with low follow-through of the circulating flow rate towards the target flow rate.

[0130] exist Figure 8 In this context, the following relationship holds for average viscosity, for example.

[0131] The average viscosity μ3 of the liquid in the supply flow path 39 (39A or 39B) can be lower than the average viscosity μ2 of the liquid in the supply manifold 33. More specifically, for example, the average viscosity μ3 can be less than 1 / 2, 1 / 3, or 1 / 5 of the average viscosity μ2.

[0132] In this case, for example, because the average viscosity μ3 of the liquid in the supply flow path 39 is low, liquid can be smoothly supplied from the supply flow path 39 to the pressure chamber 41. Furthermore, because the average viscosity μ2 in the supply manifold 33 is high, pressure waves are easily attenuated. As a result, the possibility of pressure waves leaking from the pressure chamber 41 through the supply flow path 39 to the supply manifold 33 is reduced, allowing them to propagate to other pressure chambers 41 via other supply flow paths 39. That is, so-called fluid crosstalk can be reduced.

[0133] The same relationship can also apply between the recovery flow path 45 and the recovery manifold 37. That is, the average viscosity μ5 of the liquid in the recovery flow path 45 can be lower than the average viscosity μ6 of the liquid in the recovery manifold 37. More specifically, for example, the average viscosity μ5 can be less than 1 / 2, 1 / 3, or 1 / 5 of the average viscosity μ6. In this case, the same effect as described above is achieved.

[0134] The average viscosity μ2 of the supply manifold 33 can be lower than the average viscosity μ1 of the supply reservoir 29. More specifically, for example, the average viscosity μ2 can be less than 1 / 2, 1 / 3, or 1 / 4 of the average viscosity μ1.

[0135] In this case, for example, the average viscosity μ2 of the liquid in the supply manifold 33 is low, thereby enabling the liquid to be supplied smoothly from the supply manifold 33 to the supply flow path 39. In addition, since the viscosity is high in the supply reservoir 29 and the pressure wave is easily attenuated, crosstalk caused by the propagation of pressure waves through the supply reservoir 29 can be reduced.

[0136] The same relationship described above can also apply between the recovery manifold 37 and the recovery reservoir 31. That is, the average viscosity μ6 of the liquid in the recovery manifold 37 can be lower than the average viscosity μ7 of the liquid in the recovery reservoir 31. More specifically, for example, the average viscosity μ6 can be less than 1 / 2, 1 / 3, or 1 / 5 of the average viscosity μ7. In this case, the same effect as described above is achieved.

[0137] The average viscosity μ4 of the descender 41b can be higher than the average viscosity μ5 of the recovery flow path 45. More specifically, for example, the average viscosity μ4 can be more than 1.5 times the average viscosity μ5.

[0138] In this case, for example, if the viscosity is high, the resistance to the movement of the bubbles becomes greater, and therefore the possibility of recovering the bubbles that have entered the descender 41b from the nozzle 43 from the recovery flow path 45 becomes higher.

[0139] The same relationship can also apply between the descender 41b and the supply flow path 39. That is, the average viscosity μ4 of the descender 41b can be higher than the average viscosity μ3 of the supply flow path 39. More specifically, for example, the average viscosity μ4 can be more than 1.5 times or more than 2 times the average viscosity μ3.

[0140] In this case, for example, because the average viscosity μ3 of the supply flow path 39 is low, liquid can be supplied smoothly to the descender 41b. As a result, for example, the possibility of insufficient liquid supply to the descender 41b is reduced by the continuous ejection of liquid.

[0141] The average viscosity μ2 of the supply manifold 33 can be higher than the average viscosity (μ3, μ4, and μ5) of each flow path 35 (except for the pressure chamber body 41a). More specifically, for example, the average viscosity μ2 can be more than 1.5 times higher than the average viscosity μ3, μ4, and μ5.

[0142] In this case, for example, because the average viscosity μ in the individual flow path 35 is low, liquid can be supplied smoothly to the nozzle 43. Furthermore, the average viscosity μ in the supply manifold 33 is high, resulting in a rapid decrease in pressure from the individual flow path 35 to the supply manifold 33. Therefore, fluid crosstalk is less likely to occur.

[0143] The same relationship can also apply between the recovery manifold 37 and the individual flow paths 35. That is, the average viscosity μ6 of the liquid in the recovery manifold 37 can be higher than the average viscosity (μ3, μ4, and μ5) of each flow path in the individual flow path 35. More specifically, for example, the average viscosity μ6 can be more than 1.5 times higher than the average viscosities μ3, μ4, and μ5. The same effect as described above is achieved in this case.

[0144] (An example of the value of average viscosity, etc.)

[0145] There are countless combinations of liquid characteristics, circulation flow rate, flow path shape, and size that can achieve the aforementioned relationship of average viscosity μ. Furthermore, these can be appropriately set according to the specific technical field in which the ejection device 1 is applied. The following shows the usage reference... Figure 7 This illustrates an example of the value for a typical coating.

[0146] The circulation flow rate can be set to, for example, 50 ml / min or more and 300 ml / min. The pressure in nozzle 43 when no liquid is being sprayed can be ±2 kPa relative to atmospheric pressure (approximately 100 kPa). The differential pressure between supply port 3b and recovery port 3c can be set to 40 kPa or more and 160 kPa or less.

[0147] In both the supply reservoir 29 and the recovery reservoir 31, the width w can be 4 mm or more and 20 mm or less, the height h can be 3 mm or more and 15 mm or less, and the length L can be 200 mm or more and 800 mm or less. In both the supply manifold 33 and the recovery manifold 37, the width w can be 0.2 mm or more and 2 mm or less, the height h can be 0.5 mm or more and 6 mm or less, and the length L can be 5 mm or more and 20 mm or less. In the first supply flow path 39A, the width w and the height h can each be set to 50 μm or more and 200 μm or less. In the second supply flow path 39B, the width w can be set to 50 μm or more and 200 μm or less, and the height h can be 25 μm or more and 200 μm or less. In the recovery flow path 45, the width w can be set to 70 μm or more and 200 μm or less, and the height h can be set to 80 μm or more and 200 μm or less. The length L of the supply flow path 39 and the recovery flow path 45 can be 300 μm or more and 1500 μm or less. In the descender 41b, the radius r can be 50 μm or more and 250 μm or less, and the length L can be 0.5 mm or more and 2 mm or less. In the nozzle 43, the radius r can be 5 μm or more and 50 μm or less.

[0148] The following shows an example of estimating the average viscosity μ under the conditions described above. Additionally, the average viscosity μ of the downcomer 41b is calculated using equation (1), and for the other flow paths, it is calculated using equation (2). The average viscosity μ of the supply reservoir 29 and the recovery reservoir 31 is 0.4 Pa·s or more and 2 Pa·s or less. The average viscosity μ of the supply manifold 33 and the recovery manifold 37 is 0.1 Pa·s or more and 0.4 Pa·s or less. The average viscosity μ of the supply flow path 39 and the recovery flow path 45 is 0.01 Pa·s or more and 0.1 Pa·s or less. The average viscosity μ in the downcomer 41b is 0.05 Pa·s or more and 0.2 Pa·s or less.

[0149] (Fluid resistance)

[0150] The fluid resistance (N·s / m⁵) within the flow path component 19 can be appropriately set. For example, the fluid resistance can be set such that both conditions 1 and 2 are met.

[0151] Condition 1:

[0152] (1 / 2)×R r ×U(1+1 / m) and (1 / 2)×R m The sum of ×(U / m)×(1+1 / n) is less than 2σ / r.

[0153] Condition 2:

[0154] R r<1 / 10×R m ×(1 / m)

[0155] Here, R r R is the fluid resistance supplied to the liquid in the reservoir 29. m This is the fluid resistance of the liquid in the supply manifold 33. m is the number of supply manifolds 33 connected to the supply reservoir 29. n is the number of individual flow paths 35 (nozzles 43) in each supply manifold 33. U is the flow rate (m³) of the liquid flowing into the supply reservoir 29. 3 / s). σ is the surface tension of the liquid (N / m). r is the radius of nozzle 43 (m).

[0156] Here, we ignore the supply manifold 33, which is only connected to a fictitious separate flow path that cannot eject droplets. Furthermore, we assume that the supply manifold 33 is connected to the same number of nozzles 43. Additionally, we assume that the spacing between the multiple supply manifolds 33, the distance from the upstream end of the supply reservoir 29 to the first supply manifold 33, and the distance from the last supply manifold 33 to the downstream end of the supply reservoir 29 are equal.

[0157] (1 / 2)×R in condition 1 r ×U(1+1 / m) corresponds to the pressure drop within the supply reservoir 29 (the pressure difference between the upstream and downstream sides). Specifically, the pressure drop from the upstream end of the supply reservoir 29 to the first supply manifold 33 is defined as U×R. r / m, the pressure drop from the first supply manifold 33 to the second supply manifold is calculated as (UU / m)×R r / m. Furthermore, the sum of the pressure drops from upstream to downstream, i.e., U×R r / m+(UU / m)×R r / m+...+U / m× / R r / m, thus obtaining the above (1 / 2)×R r ×U(1+1 / m).

[0158] (1 / 2)×R in condition 1 m ×(U / m)×(1+1 / n) corresponds to the pressure drop (pressure difference between upstream and downstream) within one supply manifold 33. This mathematical formula is obtained in the same way as the pressure drop within the supply reservoir 29 described above. That is, in the mathematical formula related to the supply reservoir 29, the fluid resistance Rr of the supply reservoir 29 is replaced by the fluid resistance R of the supply manifold 33. m The flow rate U flowing into the supply reservoir 29 is replaced by the flow rate U / m of the liquid flowing into the supply manifold 33, and the number m of the supply manifold 33 is replaced by the number n of the nozzles 43.

[0159] (1 / 2)×R in condition 1r ×U(1+1 / m) and (1 / 2)×R m The sum of ×(U / m)×(1+1 / n) roughly corresponds to the pressure difference between the upstreammost individual flow path 35 and the downstreammost individual flow path 35. The upstreammost individual flow path 35 is the individual flow path 35 connected to the upstream of the supply manifold 33 that connects to the upstream of the supply reservoir 29. The downstreammost individual flow path 35 is the individual flow path 35 connected to the downstream of the supply manifold 33 that connects to the downstream of the supply reservoir 29. The pressure drop in the individual flow paths 35 is approximately equal to that in the multiple individual flow paths 35, therefore the above sum corresponds to the pressure difference of all the nozzles 43 (the pressure difference between the nozzle 43 with the highest pressure and the nozzle 43 with the lowest pressure).

[0160] Furthermore, when the sum of the above is less than 2σ / r, the meniscus is easily maintained under atmospheric pressure in all nozzles 43. Also, regarding condition 1, as already explained, the supply manifold 33 connected only to a dummy separate flow path and the dummy separate flow path can be ignored. Furthermore, in the upstream or downstream supply manifold 33, sometimes the number of separate flow paths 35 connected is less than that of other supply manifolds 33. In this case, for example, the upstream or downstream supply manifold 33 can be ignored; conversely, it can be assumed that the upstream or downstream supply manifold 33 also has the same number of separate flow paths 35 as other supply manifolds 33.

[0161] Condition 2 indicates the fluid resistance R supplied to the liquid reservoir 29. r Fluid resistance R of supply manifold 33 m The magnitude relationship. Since the flow rate of the liquid flowing into the supply manifold 33 is 1 / m of the flow rate of the liquid flowing into the supply reservoir 29, the fluid resistance R... m Multiply by 1 / m to the fluid resistance R r With fluid resistance R m A comparison is made. Furthermore, condition 2 is valid if the fluid resistance R supplied to the reservoir 29 is... r In the fluid resistance R of the supply manifold 33 m The smallest in comparison.

[0162] For example, in the prior art, R r For R m Approximately 1 / 5 of ×(1 / m). On the other hand, in this embodiment, R r It can be set to R m ×(1 / m) is greater than 1 / 40 and less than 1 / 10. Of course, in this embodiment, as in the prior art, R... r It can also be set to R m It is about 1 / 5 of ×(1 / m).

[0163] By satisfying condition 2, for example, the liquid can easily flow from the supply reservoir 29 to the multiple supply manifolds 33, and the flow rate difference between the multiple supply manifolds 33 is mitigated. Consequently, liquid can be stably supplied to all the supply manifolds 33.

[0164] Based on conditions 1 and 2, fluid resistance can also be set to make condition 3 below true.

[0165] Condition 3:

[0166] R m <1 / 10×R n ×(1 / n)

[0167] Here, R n It is the fluid resistance in nozzle 43.

[0168] Condition 3 indicates the fluid resistance R of the supply manifold 33. m The relationship between the fluid resistance of the individual flow path 35 and the fluid resistance of the nozzle 43. n The fluid resistance R through nozzle 43 is much greater than the fluid resistance at other parts of the individual flow path 35. n The fluid resistance of the individual flow path 35 is approximated. Furthermore, the flow rate of the liquid flowing into the individual flow path 35 is 1 / n of the flow rate of the liquid flowing into the supply manifold 33, therefore the fluid resistance R is... n Multiply by 1 / n to reduce the fluid resistance R m With fluid resistance R n Compare them.

[0169] Condition 3 is true when the fluid resistance R of the supply manifold 33 is... m In the fluid resistance R of nozzle 43 n In comparisons, it is extremely small. For example, in the prior art, R... m For R n Approximately 1 / 6 of ×(1 / n). Furthermore, in this embodiment, as with the prior art, R... m It can also be set to R n Approximately 1 / 6 of ×(1 / n). For example, R m For R n The value is greater than 1 / 10 and less than 1 / 4 of ×(1 / n).

[0170] By satisfying condition 3, for example, the liquid can easily flow from the supply manifold 33 to the locations of the multiple individual flow paths 35, and the flow rate difference between the multiple individual flow paths 35 is mitigated. Consequently, it is possible to stably supply liquid to all the individual flow paths 35.

[0171] In addition, as an implementation Figure 8The dimensions of the average viscosity shown are one example, and the dimensions of the flow path shown are another example, which can be used as a reference for the dimensions of the flow path that satisfy conditions 1 to 3.

[0172] (Modified Example)

[0173] Figure 9 This is a schematic cross-sectional view of the individual flow path 235 involved in the variation.

[0174] The pressure chamber 241 of the separate flow path 235, like the pressure chamber 41 of the embodiment, has a pressure chamber body 241a and a descender 241b. The descender 241b has a first portion 241ba and a second portion 241bb with different cross-sectional areas.

[0175] The first part 241ba is connected to the nozzle 43. The second part 241bb is connected to the pressure chamber body 241a. In other words, the second part 241bb is located closer to the pressure chamber body 241a than the first part 241ba. Moreover, the cross-sectional area of ​​the second part 241bb is wider than that of the first part 241ba.

[0176] Because the cross-sectional areas of the first part 241ba and the second part 241bb are different, their average viscosities are also different. For example, the average viscosity of the liquid in the second part 241bb is higher than that of the liquid in the first part 241ba. In other words, the average viscosity in the descender 241b increases in stages as it approaches the pressure chamber body 41a from the nozzle 43. Furthermore, the increase in average viscosity can occur not only in one stage but also in two or more stages. In other words, the descender may have a third part, etc., in addition to the first and second parts.

[0177] In cases where the average viscosity of the second portion 241bb, located closer to the pressure chamber body 241a than the first portion 241ba, is higher than that of the first portion 241ba, for example, bubbles entering the descender 241b from the nozzle 43 are less likely to move toward the pressure chamber body 241a. Consequently, the likelihood of bubbles becoming trapped in the pressure chamber body 241a and causing a decrease in ejection characteristics becomes lower.

[0178] Furthermore, when at least one of the two flow paths whose average viscosity is being compared has a portion with a different shape, the average viscosity of the portion where the two flow paths meet can be compared with each other. For example, in the single flow path 235 involved in the modified example, when comparing the average viscosity of the recovery flow path 45 with the average viscosity of the downcomer 241b, it is possible not to compare the average viscosity of the downcomer 241b as a whole, but to use the average viscosity of the second portion 241bb that is directly connected to the recovery flow path 45 for comparison. The average viscosity of the second portion 241bb has a greater impact on the flow between the recovery flow path 45 and the downcomer 241b.

[0179] The technology disclosed herein is not limited to the above-described embodiments and variations, and can be implemented in various ways.

[0180] For example, a liquid ejection device is not limited to a piezoelectric device that applies pressure to a liquid using a piezoelectric element. A liquid ejection device can also be a thermosensitive device that generates bubbles in a liquid by heat and applies pressure to the liquid in conjunction with the generation of the bubbles to eject droplets.

[0181] The structure of the flow path can be various beyond what is shown in the diagram. For example, adjacent individual flow paths can also share a portion of each other. For example, a portion of the recovery manifold side in the recovery flow path can also be shared between adjacent individual flow paths.

[0182] The average viscosity can also be set in a manner different from the implementation method. For example, the average viscosity μ3 of the supply flow path 39, contrary to the implementation method, can be greater than or 1.5 times greater than the average viscosity μ5 of the recovery flow path 45. In this case, when the droplets are ejected, the liquid in the descender 41b is less likely to flow backward (less likely to flow in the direction opposite to the circulation direction). Furthermore, the liquid and / or bubbles are more likely to flow in the recovery flow path.

Claims

1. A liquid ejection device, comprising: A flow path component includes a flow path configured for pseudoplastic liquid flow, and the flow path has a supply reservoir, multiple supply manifolds connected to the supply reservoir, and multiple pressure chambers connected one-to-one with the multiple supply flow paths. An actuator is configured to apply pressure to the liquid in the plurality of pressure chambers to cause droplets to be ejected from a plurality of nozzles connected one-to-one with the plurality of pressure chambers. The pump is configured to cause the liquid to flow sequentially through the supply reservoir, the multiple supply manifolds, the multiple supply flow paths, and the multiple pressure chambers; as well as The controller is configured to adjust the flow rate of the liquid to a given target flow rate. The flow path has a flow path shape and flow path size such that, when the flow rate is the target flow rate, the average viscosity of the liquid in the supply flow path is less than half of the average viscosity of the liquid in the supply manifold.

2. The liquid ejection device according to claim 1, wherein, The flow path has a flow path shape in which the average viscosity of the liquid in the plurality of supply manifolds is less than half of the average viscosity of the liquid in the supply reservoir when the flow rate is the target flow rate.

3. The liquid ejection device according to claim 1, wherein, The liquid ejection device includes: Multiple recovery flow paths are connected to each of the multiple pressure chambers; and The pump is configured to circulate the liquid sequentially via the supply reservoir, the multiple supply manifolds, the multiple supply flow paths, the multiple pressure chambers, the multiple recovery flow paths, the multiple recovery manifolds, and the recovery reservoir. The plurality of pressure chambers each have: The pressure chamber body is pressurized by the actuator; and The descender connects the pressure chamber body and the nozzle. The recovery flow path is connected to the descender. The flow path has a flow path shape in which the average viscosity of the liquid in the descender is more than 1.5 times the average viscosity of the liquid in the recovery flow path when the flow rate is the target flow rate.

4. The liquid ejection device according to claim 1, wherein, The liquid ejection device includes: Multiple recovery flow paths are connected to each of the multiple pressure chambers; and The pump is configured to circulate liquid sequentially via the supply reservoir, the multiple supply manifolds, the multiple supply flow paths, the multiple pressure chambers, the multiple recovery flow paths, the multiple recovery manifolds, and the recovery reservoir. The plurality of pressure chambers each have: The pressure chamber body is pressurized by the actuator; and The descender connects the pressure chamber body and the nozzle. The recovery flow path is connected to the descender. The descender has: First part; as well as The second part is located further away from the main body of the pressure chamber than the first part. The flow path has a shape in which the average viscosity of the liquid in the second part is higher than the average viscosity of the liquid in the first part when the flow rate is the target flow rate.

5. The liquid ejection device according to claim 1, wherein, Let the fluid resistance of the liquid in the supply reservoir be R. r , Let the fluid resistance of the liquid in the supply manifold be R. m , Let m be the number of supply manifolds connected to the supply reservoir. Let the number of nozzles in each of the supply manifolds be n. Let the flow rate of the liquid flowing into the supply reservoir be U. Let the surface tension of the liquid be σ. Let the radius of the nozzle be r. Then, (1 / 2)×R r ×U(1+1 / m) and (1 / 2)×R m The sum of ×(U / m)×(1+1 / n) is less than 2σ / r, and R r <1 / 10×R m ×(1 / m)。 6. The liquid ejection device according to claim 5, wherein, The fluid resistance of the liquid in the nozzle is set to R. n hour, R m <1 / 10×R n ×(1 / n)。 7. The liquid ejection device according to claim 1, wherein, The pump is a vacuum pump.

8. The liquid ejection device according to claim 1, wherein, The target flow rate is above 50 ml / min and below 300 ml / min.

9. The liquid ejection device according to claim 1, wherein, Let S1 be the cross-sectional area of ​​the inflow surface of the nozzle orthogonal to the flow direction of the liquid, and S2 be the cross-sectional area of ​​the outflow surface of the nozzle orthogonal to the flow direction of the liquid. Then, S1>S2.

10. A liquid ejection method, using the liquid ejection device of claim 1, wherein, Using a shearing speed of 1000s -1 The viscosity at that time was above 0.02 Pa·s and below 0.4 Pa·s, and the shear rate was 0.01 s⁻¹. -1 The liquid is a pseudoplastic fluid with a viscosity of 0.5 Pa·s or more and 50 Pa·s or less.

11. A liquid ejection device, comprising: A flow path component includes a flow path configured for pseudoplastic liquid flow, and the flow path has a supply reservoir, multiple supply manifolds connected to the supply reservoir, multiple supply flow paths, multiple pressure chambers, multiple recovery flow paths, multiple recovery manifolds, and a recovery reservoir, wherein the multiple supply flow paths are arranged in a number of two or more relative to each of the multiple supply manifolds and are respectively connected to any one of the multiple supply manifolds to supply liquid from the connected supply manifolds; the multiple pressure chambers are respectively connected to the multiple supply flow paths and are pressurized by supplying liquid from the supply flow paths; the multiple recovery flow paths are respectively connected to the multiple pressure chambers and recover liquid from the multiple pressure chambers; the multiple recovery manifolds are respectively connected to any two or more of the multiple recovery flow paths and recover liquid from the multiple recovery flow paths; and the recovery reservoir is connected to the multiple recovery manifolds and recovers liquid from the multiple recovery manifolds. An actuator is configured to apply pressure to the liquid in the plurality of pressure chambers to cause droplets to be ejected from a plurality of nozzles connected one-to-one with the plurality of pressure chambers. The tank, which is part of the liquid storage, is connected to the supply reservoir and the recovery reservoir; The pump is configured to circulate the liquid sequentially through the supply reservoir, the multiple supply manifolds, the multiple supply flow paths, the multiple pressure chambers, the multiple recovery flow paths, the multiple recovery manifolds, and the recovery reservoir. The controller is configured to adjust the circulation flow rate of the liquid to a given target flow rate; and The moving part is configured to move at least one of the flow path member or the surface of the object, so that the droplets ejected from the plurality of nozzles move toward the surface of the object. The flow path shape and flow path size have such that, when the circulating flow rate is equal to the target flow rate, the average viscosity of the liquid in the plurality of supply flow paths is less than half of the average viscosity of the liquid in the plurality of supply manifolds.

12. A method for ejecting liquid, The pseudoplastic liquid is circulated via a flow path component comprising a supply reservoir, multiple supply manifolds connected to the supply reservoir, multiple supply flow paths connected to two or more of the multiple supply manifolds, multiple pressure chambers connected one-to-one to the multiple supply flow paths, multiple recovery flow paths connected one-to-one to the multiple pressure chambers, multiple recovery manifolds connected to two or more of the multiple recovery flow paths, and a recovery reservoir connected to the multiple recovery manifolds. Pressure is applied to the liquid in the plurality of pressure chambers, causing droplets to be ejected from a plurality of nozzles connected one-to-one to the plurality of pressure chambers. The circulating flow rate of the liquid is adjusted to a target flow rate where the average viscosity of the liquid in the multiple supply flow paths is less than half of the average viscosity of the liquid in the multiple supply manifolds.

13. The liquid ejection method according to claim 12, wherein, At least one of the flow path components or the surface of the object is moved such that droplets ejected from the plurality of nozzles move toward the surface of the object.

14. The liquid ejection method according to claim 12, wherein, When the circulating flow rate is the target flow rate, the average viscosity of the liquid in the multiple supply manifolds is less than half the average viscosity of the liquid in the supply reservoir.

15. The liquid ejection method according to claim 12, wherein, The plurality of pressure chambers each have: The pressure chamber body is pressurized by the actuator; and The descender connects the pressure chamber body and the corresponding nozzle. The recovery flow path is connected to the descender. When the flow rate is the target flow rate, the average viscosity of the liquid in the descender is more than 1.5 times the average viscosity of the liquid in the multiple recovery flow paths.

16. The liquid ejection method according to claim 12, wherein, The plurality of pressure chambers each have: The pressure chamber body is pressurized by the actuator; and The descender connects the pressure chamber body and the corresponding nozzle. The recovery flow path is connected to the descender. The descender has: First part; as well as The second part is located closer to the main body of the pressure chamber than the first part. When the flow rate is the target flow rate, the average viscosity of the liquid in the second part is higher than the average viscosity of the liquid in the first part.

17. The liquid ejection method according to claim 12, wherein, Let the fluid resistance of the liquid in the supply reservoir be R. r , Let the fluid resistance of the liquid in the supply manifold be R. m , Let m be the number of supply manifolds connected to the supply reservoir. Let the number of nozzles in each of the supply manifolds be n. Let the flow rate of the liquid flowing into the supply reservoir be U. Let the surface tension of the liquid be σ. Let the radius of the nozzle be r. Then, (1 / 2)×R r ×U(1+1 / m) and (1 / 2)×R m The sum of ×(U / m)×(1+1 / n) is less than 2σ / r, and R r <1 / 10×R m ×(1 / m)。 18. The liquid ejection method according to claim 17, wherein, In R n When the fluid resistance of the liquid in the nozzle is... R m <1 / 10×R n ×(1 / n)。 19. The liquid ejection method according to claim 12, wherein, Using a shearing speed of 1000s -1 The viscosity at that time was above 0.02 Pa·s and below 0.4 Pa·s, and the shear rate was 0.01 s⁻¹. -1 The liquid is a pseudoplastic fluid with a viscosity of 0.5 Pa·s or more and 50 Pa·s or less.

20. The liquid ejection method according to claim 12, wherein, The target flow rate is above 50 ml / min and below 300 ml / min.

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