Liquid dispensing device and liquid dispensing method

Abstract

To stably supply pseudoplastic liquid to a circulation supply flow path formed in a flow path member.SOLUTION: A liquid ejection apparatus has a flow path member having a flow path through which a pseudoplastic liquid flows, an actuator that applies a pressure to the liquid inside the flow path to cause a liquid droplet to be ejected from the flow path member, and a flow rate setting unit that sets a flow rate of the liquid inside the flow path. The flow rate setting unit adjusts a circulation flow rate of the liquid, which circulates through a supply reservoir, a plurality of supply manifolds, a plurality of supply flow paths, a plurality of pressure chambers, a plurality of collection flow paths, a plurality of collection manifolds, and a collection reservoir in this order, to a predetermined target flow rate. The flow path has a flow path shape with which average viscosity of the liquid in the supply flow paths becomes half or less of average viscosity of the liquid in the supply manifolds when the circulation flow rate is the target flow rate.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] The present disclosure relates to a liquid ejection device and a liquid ejection method.

Background Art

[0002] Liquid ejection devices such as inkjet printers are known. In Patent Document 1, an inkjet recording device using a thixotropic ink is disclosed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0004] A liquid discharge device according to one aspect of the present disclosure includes a flow path member, an actuator, and a flow rate setting unit. The flow path member has a flow path through which a pseudoplastic liquid flows. The actuator applies pressure to the liquid in the flow path to discharge droplets from the flow path member. The flow rate setting unit sets the flow rate of the liquid in the flow path. The flow path includes a supply reservoir, a plurality of supply manifolds, a plurality of supply flow paths, a plurality of pressure chambers, a plurality of nozzles, a plurality of recovery flow paths, and a recovery reservoir. The supply reservoir is supplied with the liquid. The plurality of supply manifolds are connected to the supply reservoir, and the liquid is supplied from the supply reservoir. The plurality of supply flow paths are provided in numbers of two or more for each of the plurality of supply manifolds, and each is connected to one of the plurality of supply manifolds, and the liquid is supplied from the connected supply manifold. The plurality of pressure chambers are separately connected to the plurality of supply flow paths, and the liquid is supplied from the plurality of supply flow paths, and pressure is applied by the actuator. The plurality of nozzles are connected separately to the plurality of pressure chambers and discharge the liquid from the pressure chambers to the outside. The plurality of recovery channels are connected separately to the plurality of pressure chambers and recover the liquid from the plurality of pressure chambers. The plurality of recovery manifolds are each connected to two or more of the plurality of recovery channels and recover the liquid from the plurality of recovery channels. The recovery reservoir is connected to the plurality of recovery manifolds and recovers the liquid from the plurality of recovery manifolds. The flow rate setting unit adjusts the circulation flow rate of the liquid circulating sequentially through the supply reservoir, the plurality of supply manifolds, the plurality of supply channels, the plurality of pressure chambers, the plurality of recovery channels, the plurality of recovery manifolds, and the recovery reservoir to a predetermined target flow rate. The channels have a channel shape such that when the circulation flow rate is the target flow rate, the average viscosity of the liquid in the supply channels is half or less of the average viscosity of the liquid in the supply manifolds.

[0005] A liquid ejection method according to one aspect of the present disclosure is a liquid ejection method using the above liquid ejection device. As the liquid, a pseudoplastic fluid having a viscosity of 0.02 Pa·s or more and 0.4 Pa·s or less when the shear rate is 1000 s -1 and a viscosity of 0.5 Pa·s or more and 50 Pa·s or less when the shear rate is 0.01 s -1 is used.

Brief Description of Drawings

[0006] [Figure 1] It is a schematic diagram showing the overall configuration of a liquid ejection device according to an embodiment. [Figure 2] FIG. 2(a) is an exploded perspective view of a head of a liquid ejection device according to an embodiment, and FIG. 2(b) is a perspective view of a second flow path member included in the above head. [Figure 3] FIGS. 3(a) and 3(b) are plan perspective views of a head according to an embodiment. [Figure 4] It is an enlarged view of region IV in FIG. 3(b). [Figure 5] It is a perspective view of an individual flow path of a head according to an embodiment. [Figure 6] FIG. 6(a) is a cross-sectional view taken along line VIa-VIa of FIG. 5, and FIG. 6(b) is a cross-sectional view taken along line VIb-VIb of FIG. 5. [Figure 7] It is a diagram showing the characteristics of a liquid used in a liquid ejection device according to an embodiment. [Figure 8] It is a diagram showing an example of the average viscosity for each part of a flow path according to an embodiment. [Figure 9] It is a schematic cross-sectional view of an individual flow path according to a modification.

Modes for Carrying Out the Invention

[0007] Embodiments of this disclosure will be described below with reference to the drawings. The following drawings are schematic; therefore, details may be omitted. Furthermore, dimensional ratios do not necessarily correspond to reality. Dimensional ratios between multiple drawings do not necessarily correspond either. Certain dimensions may be shown larger than they actually are, and certain shapes may be exaggerated.

[0008] The drawings may include arrows indicating directions D1 to D6. These directions are parallel to the ejection surface 3a, which will be described later. Directions D2 and D5 are, for example, parallel to the longitudinal direction of head 3, which will be described later, and from another perspective, are the so-called main scanning directions. Directions D3 and D6 are perpendicular to directions D2 and D5. Directions D1 and D4 are inclined relative to directions D3 and D6.

[0009] (Overall configuration of the liquid dispensing device) Figure 1 is a schematic diagram showing the main components of the liquid dispensing device 1 (hereinafter sometimes referred to as "dispensing device 1") according to this embodiment.

[0010] The ejection device 1 is configured to adhere liquid to the surface of an object 101 by ejecting droplets from the ejection surface 3a of the head 3 toward the object 101, similar to an inkjet printer. The ejection surface 3a may face any direction with respect to the vertical, but for convenience, in the following explanation, the direction toward which the ejection surface 3a faces will be considered downward, and terms such as upper surface or lower surface will be used.

[0011] The specific type (use) of the ejection device 1 may be as appropriate. For example, the ejection device 1 may be a device that prints characters and figures (or, from another perspective, records information) by applying ink to a recording medium (e.g., paper) as the object 101. In other words, the ejection device 1 may be a printer in general. Alternatively, for example, the ejection device 1 may be a device that decorates the body of an automobile by applying paint to the body as the object 101. Alternatively, for example, the ejection device 1 may be a device that forms wiring by applying a liquid containing conductive particles to a circuit board as the object 101.

[0012] Furthermore, unlike the illustrated example, the dispensing device 1 does not have to be a device that applies liquid to the object 101. For example, the dispensing device 1 may be a device that dispenses a liquid chemical that reacts with the substance in the container into the container, or it may be a device that sprays disinfectant into the atmosphere.

[0013] As can be understood from the examples of specific types of dispensing devices 1 described above, the material, shape, and dimensions of the object 101 may be appropriate. Since Figure 1 is a schematic diagram, the object 101 is shown as a rectangular parallelepiped. Examples of materials for the object 101 include paper, cloth, resin, metal, ceramic, and wood, as well as combinations thereof. Examples of types of objects 101 include recording media (e.g., roll paper or sheet paper), circuit boards, clothing, beverage containers, storage containers, electronic equipment housings, and automobile bodies. The object 101 or the area on which the liquid adheres may be narrower or wider than the dispensing surface 3a from which the droplets are dispensed.

[0014] Furthermore, as can be understood from the examples of specific types of dispensing devices 1 described above, the type of liquid may also be appropriate. For example, examples of liquid types include ink, paint, liquids containing conductive particles, chemicals, and disinfectants. Inks and paints may be distinguished by the presence or absence of organic solvents and / or the presence or absence of a protective function for the surface of the object 101. However, such distinctions are not required. In the following description, paint may be read as ink as appropriate, and vice versa. Paint may contain pigments for the purpose of coloring, or it may not contain pigments (colorless) and may not be intended for coloring (for example, only for the purpose of providing gloss and / or protecting the object 101).

[0015] The ejection device 1 includes, for example, a head 3 for ejecting droplets and a moving unit 5 for relatively moving the head 3 and the object 101. The head 3 has an ejection surface 3a from which a plurality of nozzles (described later) for ejecting droplets are open. The moving unit 5 moves the ejection surface 3a and the surface of the object 101 relatively along the ejection surface 3a and the surface of the object 101, while maintaining the ejection surface 3a and the surface of the object 101 facing each other. The direction of relative movement is, for example, the D3 direction or the D6 direction. As can be understood from an inkjet printer, which is a specific example of the ejection device 1, droplets are ejected from the ejection surface 3a in synchronization with the relative movement described above, so that droplets adhere to an area larger than the area of ​​the arrangement area of ​​the plurality of nozzles.

[0016] Furthermore, the discharge device 1 has, for example, a tank 7 that stores 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. In other words, the liquid circulates between the head 3 and the tank 7. By circulating the liquid in this way, for example, the probability of liquid accumulating in the head 3 is reduced. Consequently, the probability of the accumulating liquid solidifying or components in the accumulating liquid settling is reduced. In addition, in this embodiment, by circulating the liquid, the shear rate of the liquid can be adjusted, and consequently, the viscosity of the liquid can be adjusted, as will be described later.

[0017] The discharge device 1 includes a circulation operating unit 9 that applies pressure to the liquid so that the liquid circulates, and a control unit 11 that controls each part (for example, the head 3, the moving part 5, and the circulation operating unit 9). The combination of the circulation operating unit 9 and the control unit 11 may be considered as a flow rate setting unit 13 that sets the flow rate of the liquid circulating in the head 3 (hereinafter referred to as the circulation flow rate). The circulation flow rate may be considered to be the same as, for example, the flow rate of the liquid flowing out of the head 3 from the recovery port 3c.

[0018] The dispensing device 1 may have only one head 3 (and tank 7), like a monochrome printer, or it may have multiple heads 3 (and multiple tanks 7) dispensing different types of liquids, like a color printer. Alternatively, the dispensing device 1 may have multiple heads 3 dispensing the same type of liquid. Having multiple heads 3 dispensing the same type of liquid is advantageous, for example, in reducing the time it takes for the liquid to adhere to a certain area or improving dot density. For convenience, the following description will refer only to a single head 3.

[0019] (Moving part) The moving unit 5 can, for example, move the object 101 relative to the head 3 in at least one of the D3 and D6 directions. As previously described, this direction is the direction of movement when ejecting droplets, and is the so-called sub-scanning direction. The moving unit 5 may be capable of realizing relative movement between the head 3 and the object 101 in directions other than the D3 and D6 directions. Other directions in which relative movement may be realized include, for example, the D2 and D5 directions which are perpendicular to the D3 and D6 directions, and the direction perpendicular to the ejection surface 3a (the direction that brings the head 3 and the object 101 closer together, and the direction that moves them apart). The moving unit 5 may also be capable of realizing relative rotation between the head 3 and the object 101.

[0020] The moving unit 5 may move only the object 101, only the head 3, or both, in the absolute coordinate system. Furthermore, the specific configuration of the moving unit 5 may be appropriately set according to the specific type of discharge device 1.

[0021] For example, if the ejection device 1 is a so-called line printer, the moving unit 5 may be configured as a device for transporting the recording medium (e.g., paper) as the object 101. This device includes, for example, a plurality of rollers that contact the recording medium to generate frictional force, and an electric motor that rotates the plurality of rollers. Alternatively, if the ejection device 1 is a so-called serial printer, the moving unit 5 may include a device for transporting the recording medium as the object 101 in a predetermined transport direction, and a device for moving the head 3 in a direction perpendicular to the transport direction and along the recording medium.

[0022] Furthermore, for example, the dispensing device 1 may include a belt conveyor for transporting any type of object 101. Also, for example, the dispensing device 1 may include a movable table on which any type of object 101 is placed. Furthermore, for example, the dispensing 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 vertical articulated robots (articulated robots in the narrow sense), SCARA robots, Cartesian robots, and parallel link robots.

[0023] (Tank and circulation mechanism) The tank 7 and the circulation mechanism 9 may be similar to, for example, the tank and circulation mechanism in a known inkjet printer that circulates liquid, or they may be adaptations of such known tank and circulation mechanism.

[0024] For example, tank 7 may be configured to contain the liquid supplied to head 3 and the liquid recovered from head 3 in the same space. Alternatively, tank 7 may contain the liquid supplied to head 3 and the liquid recovered from head 3 in separate spaces, with the liquid flowing from the latter space to the former space. In this case, tank 7 may have two spaces separated by a partition wall, or it may have two spaces formed by two tanks connected to each other by a flow path. The inside of tank 7 (the above space) may be open to the atmosphere or sealed. In the latter case, the pressure inside tank 7 may be adjusted to an appropriate pressure by a valve or vacuum pump, etc. Tank 7 may have a main tank and a sub-tank with a smaller capacity than the main tank. The sub-tank acts as an intermediary between the main tank and head 3.

[0025] In the illustrated example, the circulation unit 9 includes a pump 15 that delivers liquid from the tank 7 to the head 3, a pressure sensor 17A that detects the liquid pressure on the supply port 3b side, and a pressure sensor 17B that detects the liquid pressure on the recovery port 3c side. The control unit 11, for example, uses the detected values ​​of the pressure sensors 17A and 17B to feedback control the pump 15 so that the pressure difference between the supply port 3b and the recovery port 3c converges to a predetermined target value. This feedback controls the circulation flow rate to the target flow rate.

[0026] Unlike the illustrated example, a pump 15 for sending liquid from the recovery port 3c to the tank 7 may be provided instead of, or in addition to, the pump 15 on the supply port 3b side. Alternatively, instead of, or in addition to, the liquid flow may be generated by pressure control within the tank 7 using a vacuum pump or the like. Liquid flow may also be generated by raising the liquid level in the tank containing the supply liquid higher than the liquid level in the tank containing the recovered liquid.

[0027] In place of, or in addition to, the pressure sensors 17A and 17B, a flow sensor for detecting the flow rate of the liquid supplied to the head 3 and / or a sensor for detecting the flow rate of the liquid recovered from the head 3 may be provided and used to control the circulating flow rate. Also, as can be understood from the various ways in which the above liquid flow is generated, in place of, or in addition to these sensors, a sensor for detecting the air pressure in the tank 7 may be provided and used to control the circulating flow rate. Open-loop control may be performed without sensor-based feedback control; that is, sensors may not be provided.

[0028] The tank 7 and the circulation mechanism 9 are not moved in the absolute coordinate system by the moving part 5, for example. Therefore, in an embodiment where the moving part 5 moves the head 3 in the absolute coordinate system, the head 3 moves relative to the tank 7 and the circulation mechanism 9. In this case, the head 3 and the tank 7 and the circulation mechanism 9 may be connected by a flow path made of, for example, a flexible tube. Also, in an embodiment where the moving part 5 does not move the head 3 in the absolute coordinate system, the head 3 is fixed relative to the tank 7 and the circulation mechanism 9. In this case, the configuration of the flow path connecting the head 3 and the tank 7 and the circulation mechanism 9 is arbitrary. Contrary to the above description, all or part of the tank 7 and the circulation mechanism 9 may move together with the head 3.

[0029] (Control Unit) The control unit 11 is configured, for example, by a computer. The computer, although not specifically shown, includes a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), and an external storage device. The CPU controls the head 3, the moving unit 5, and the circulating operation unit 9 by executing programs stored in the ROM and / or external storage device.

[0030] (head) Figure 2(a) is an exploded perspective view of head 3.

[0031] Head 3 includes a flow path member 19 (reference numeral 1 in Figure 1) having a flow path through which liquid flows, an actuator 21 that applies pressure to the liquid in the flow path member 19, and a signal transmission member 23 (not shown in Figure 1) for inputting a drive signal to the actuator 21. The flow path member 19 includes a first flow path member 25 having a discharge surface 3a and a second flow path member 27 having a supply port 3b and a recovery port 3c. The surface of the first flow path member 25 opposite to the discharge surface 3a is sometimes called the pressurized surface 25a.

[0032] The first flow channel member 25 and the second flow channel member 27 are each configured in a generally flat shape, and when superimposed on each other, they form a generally flat flow channel member 19. The liquid supplied to the supply port 3b is supplied from the second flow channel member 27 to the first flow channel member 25, and then discharged from the discharge surface 3a. The liquid that remains without being discharged flows from the first flow channel member 25 to the second flow channel member 27 and is recovered from the recovery port 3c.

[0033] The control unit 11 outputs a control signal based on predetermined data such as image data. The control signal is input to a driver (not shown) mounted on the signal transmission member 23, for example, via the signal transmission member 23. The driver generates a drive signal having a predetermined waveform based on the input control signal. The drive signal is input to the actuator 21 via the signal transmission member 23. The actuator 21 applies pressure to the liquid in the flow channel member 19 with a pressure waveform corresponding to the waveform of the drive signal. As a result, the liquid in the flow channel member 19 is discharged from the discharge surface 3a. The division of roles between the control unit 11 and the driver may be set as appropriate, and the driver may be considered as part of the control unit 11.

[0034] (Second flow channel member, supply reservoir, and recovery reservoir) Figure 2(b) is a perspective view of the second flow channel member 27. More specifically, this figure shows the second flow channel member 27 as seen from the first flow channel member 25 side, and the upper part of the paper in Figure 2(b) corresponds to the lower part of the paper in Figures 1 and 2(a). Figure 3(a) is a plan perspective view of the head 3 as seen from the opposite side of the discharge surface 3a. This figure shows the shape of the second flow channel member 27 and the actuator 21.

[0035] As shown in Figure 2(b), the second flow channel member 27 has two grooves (see reference numerals 29 and 31) formed on the surface facing the first flow channel member 25. These two grooves are blocked by the first flow channel member 25 to form the supply reservoir 29 and the recovery reservoir 31 shown in Figures 2(b) and 3(a). The supply reservoir 29 is connected to the supply port 3b and is a flow channel that supplies the liquid supplied to the supply port 3b into the flow channel of the first flow channel member 25. The recovery reservoir 31 is connected to the recovery port 3c and is a flow channel that recovers the liquid from the flow channel of the first flow channel member 25 and guides the recovered liquid to the recovery port 3c.

[0036] The supply reservoir 29 and the recovery reservoir 31 each have, for example, portions (main portions 29a and 31a) that extend linearly along the longitudinal direction (D2 direction and D5 direction) of the head 3. The main portions 29a and 31a have a length that extends along the longitudinal direction (D2 direction and D5 direction) of the arrangement area of ​​the multiple nozzles (described later) (refer here to the arrangement area of ​​the actuator 21 in Figure 3(a)). Furthermore, the main portions 29a and 31a are located on opposite sides (D3 direction and D6 direction) of the short direction of the head 3 with respect to the arrangement area of ​​the multiple nozzles. In describing the embodiments, for convenience, the shape and dimensions of the supply reservoir 29 and the recovery reservoir 31 may be described by focusing only on the main portions 29a and 31a.

[0037] The supply port 3b leads to, for example, one end (the end in the D2 direction) of the supply reservoir 29. The other end (the end in the D5 direction) of the supply reservoir 29 is a dead end (in other words, a cul-de-sac). The liquid in the supply reservoir 29 flows in the direction from one end to the other (in the D5 direction). The recovery port 3c leads to, for example, one end (the end in the D5 direction) of the recovery reservoir 31. The other end (the end in the D2 direction) of the recovery reservoir 31 is a dead end (in other words, a cul-de-sac). The liquid in the recovery reservoir 31 flows in the direction from the other end to the one end (in the D5 direction). In the illustrated example, the direction in which the liquid flows in the supply reservoir 29 and the direction in which the liquid flows in the recovery reservoir 31 are the same. However, they may be opposite to each other.

[0038] The supply reservoir 29 may have only a main portion 29a, or it may have other parts. In the illustrated example, the supply reservoir 29 has a portion (not shown in reference numerals) that extends diagonally from the main portion 29a in the longitudinal direction of the head 3 to the supply port 3b. Similarly, the recovery reservoir 31 may have only a main portion 31a, or it may have other parts. In the illustrated example, the recovery reservoir 31 has a portion (not shown in reference numerals) that extends diagonally from the main portion 31a in the longitudinal direction of the head 3 to the recovery port 3c.

[0039] The cross-sectional shape and dimensions of the supply reservoir 29 and the recovery reservoir 31 (for example, the main parts 29a and 31a) may be constant regardless of their position along the length of the flow path, or they may vary depending on their position. In the description of the embodiments, the former may be taken as an example. The cross-sectional shape may be any appropriate shape, such as a rectangle. The various dimensions of the supply reservoir 29 and the recovery reservoir 31 may be set appropriately according to the specific technical field to which the discharge device 1 is applied.

[0040] In the illustrated example, the second flow channel member 27 has two grooves that serve as a supply reservoir 29 and a recovery reservoir 31, as well as a slit 27a (Figures 2(a) and 2(b)) through which the signal transmission member 23 is inserted, and a recess 27b (Figures 2(b) and 3(a)) for housing the actuator 21. The slit 27a penetrates the second flow channel member 27 from the first flow channel member 25 side to the opposite side and extends along the longitudinal direction of the head 3. The recess 27b has a planar shape that is slightly larger than the actuator 21, and in the illustrated example, it is a rectangle with the longitudinal direction of the head 3 as its longitudinal direction.

[0041] The material of the second flow channel member 27 is arbitrary. For example, the second flow channel member 27 may be made of metal, resin, ceramic, or a combination thereof.

[0042] (First flow channel member) Figure 3(b) is a plan perspective view of head 3. This figure shows the shape of the first flow path member 25 and the actuator 21. Figure 4 is an enlarged view of region IV in Figure 3(b).

[0043] The flow path of the first flow path member 25 includes a plurality of supply manifolds 33 to which liquid is supplied from a supply reservoir 29, and a plurality of individual flow paths 35 to which liquid is supplied from the supply manifolds 33. Each individual flow path 35 includes a nozzle (described later) that discharges droplets from a discharge surface 3a. The flow path of the first flow path member 25 also includes a plurality of recovery manifolds 37 that recover liquid from the plurality of individual flow paths 35 and guide the recovered liquid to a recovery reservoir 31.

[0044] Although not specifically shown in the figures, the first flow path member 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 contribute, for example, to equalizing the temperature of the first flow path member 25.

[0045] (Manifold) The supply manifold 33 has a main section 33a (corresponding to substantially the entire supply manifold 33 in the illustrated example) that extends linearly along the D4 direction from the supply reservoir 29 side to the recovery reservoir 31 side. The D4 direction is inclined with respect to the short direction (D6 direction) of the head 3. Similarly, the recovery manifold 37 has a main section 37a (corresponding to substantially the entire recovery manifold 37 in the illustrated example) that extends linearly along the D1 direction from the recovery reservoir 31 side to the supply reservoir 29 side. The D1 direction is inclined with respect to the short direction (D3 direction) of the head 3. For convenience in describing the embodiments, the shape and dimensions of the supply manifold 33 and recovery manifold 37 may be described by focusing only on the main sections 33a and 37a.

[0046] One end of the supply manifold 33 (the end in the D1 direction) overlaps the supply reservoir 29 in a plan view. This end is connected to the supply reservoir 29 through an opening 33b that opens to the side of the first flow channel member 25 facing the second flow channel member 27. The other end of the supply manifold 33 (the end in the D4 direction) is a dead end. Therefore, the liquid from the supply reservoir 29 is supplied to the aforementioned end of the supply manifold 33 through the opening 33b and flows through the supply manifold 33 in the direction from the aforementioned end to the aforementioned end (D4 direction).

[0047] One end of the recovery manifold 37 (the end in the D4 direction) overlaps the recovery reservoir 31 in a plan view. This end is connected to the recovery reservoir 31 through an opening 37b that opens to the side of the first flow channel member 25 facing the second flow channel member 27. The other end of the recovery manifold 37 (the end in the D1 direction) is a dead end. Therefore, the liquid in the recovery manifold 37 flows from the other end to the one end (in the D4 direction) and is recovered into the recovery reservoir 31 through the opening 37b.

[0048] The supply manifold 33 and the recovery manifold 37 have a length that extends along the shorter side (directions D3 and D6) of the area where the multiple nozzles (described later) are located (refer here to the area where the actuator 21 is located). The end of the supply manifold 33 on the recovery reservoir 31 side (the end in the D4 direction) is located, for example, closer to the supply reservoir 29 than to 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 located, for example, closer to the recovery reservoir 31 than to the supply reservoir 29.

[0049] The multiple supply manifolds 33 are, for example, identical in configuration to one another and are arranged at a constant pitch along the D2 direction. In other words, the multiple supply manifolds 33 extend parallel to each other and have the same length. The connection points (openings 33b) of the multiple supply manifolds 33 to the supply reservoir 29 are arranged at a constant pitch along the supply reservoir 29.

[0050] Similarly, the multiple recovery manifolds 37 are, for example, identical in configuration to one another and are arranged at a constant pitch along the D2 direction. In other words, the multiple recovery manifolds 37 extend parallel to each other and have the same length. The connection points (openings 37b) of the multiple recovery manifolds 37 to the recovery reservoir 31 are arranged at a constant pitch along the recovery reservoir 31.

[0051] Multiple supply manifolds 33 and multiple recovery manifolds 37 are arranged alternately, for example, at a constant pitch. 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.

[0052] The cross-sectional shape and dimensions of the supply manifold 33 and the recovery manifold 37 (for example, the main sections 33a and 37a) may be constant regardless of their position along the length of the flow path, or they may vary depending on their position. In the description of the embodiments, the former may be taken as an example. The cross-sectional shape may be any appropriate shape, such as a rectangle. The various dimensions of the supply manifold 33 and the recovery manifold 37 may be set appropriately according to the specific technical field to which the discharge device 1 is applied.

[0053] (Individual channel) The individual flow paths 35 are, for example, located between adjacent supply manifolds 33 and recovery manifolds 37 and connected to each other. Multiple individual flow paths 35 are provided for each pair of manifolds (33 and 37). Multiple individual flow paths 35 connected to the same manifolds (33 and 37) are arranged, for example, at a constant pitch along the manifold (along the D1 direction), forming a row of flow paths. Multiple row of flow paths are then arranged in the D2 direction, resulting in a matrix arrangement of multiple individual flow paths 35. Unlike the illustrated example, two or more rows of individual flow paths 35 may be provided between adjacent supply manifolds 33 and recovery manifolds 37.

[0054] Within a single flow path array, the configurations of multiple individual flow paths 35 are basically identical. Similarly, the configurations of multiple flow path arrays are also basically the same. However, for example, the orientation of individual flow paths 35 may differ between adjacent flow path arrays (as shown in the illustration). Also, for example, the shape and / or dimensions of multiple individual flow paths 35 within a single flow path array may differ slightly. Among the multiple flow path arrays, the flow path arrays located at the D2 direction end and the flow path arrays located at the D5 direction end may have so-called dummy individual flow paths that do not discharge droplets.

[0055] Each individual flow path 35 has a nozzle 43 that opens to the discharge surface 3a and discharges droplets. A row of multiple nozzles 43 arranged in the D1 direction is called a nozzle row. The direction of arrangement of the nozzles 43 in a nozzle row (D1 direction) is inclined with respect to the direction of relative movement of the head 3 with respect to the object 101 (D3 direction). Due to the above inclination, the positions of the nozzles 43 belonging to the same nozzle row are different in the D2 direction. In addition, multiple nozzle rows partially overlap when viewed in the D3 direction. In this overlapping portion, the positions of the nozzles 43 of one nozzle row and the nozzles 43 of another nozzle row are different in the D2 direction. When multiple nozzles 43 are projected in the D3 direction, the multiple nozzles 43 are arranged at basically constant intervals in the D2 direction.

[0056] This allows multiple dots to be formed on the surface of the object 101, arranged in the D2 direction at a pitch shorter than the distance between adjacent nozzles 43 in the head 3. For example, 32 nozzles 43 are projected onto a virtual straight line R, and within the virtual straight line R, the nozzles 43 are arranged at intervals of 360 dpi. As a result, by moving the object 101 and the head 3 relative to each other in a direction perpendicular to the virtual straight line R and ejecting droplets, printing can be performed at a resolution of 360 dpi.

[0057] Figure 5 is a perspective view of the individual flow path 35. Figures 6(a) and 6(b) are cross-sectional views of the first flow path member 25 and the actuator 21. Figure 6(a) corresponds to the line VIa-VIa in Figure 5. Figure 6(b) corresponds to the line VIb-VIb in Figure 5.

[0058] The individual 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 previously described, the nozzle 43 opens to the discharge surface 3a and is connected to the outside of the first flow path member 25. The liquid from the supply manifold 33 is supplied to the nozzle 43 via the supply flow path 39 and the pressure chamber 41. Then, when pressure is applied to the pressure chamber 41 by the actuator 21, droplets are discharged from the nozzle 43. The individual flow path 35 also has a recovery flow path 45 connecting the pressure chamber 41 and the recovery manifold 37. The liquid that remains in the pressure chamber 41 without being discharged is recovered into the recovery manifold 37 from the recovery flow path 45.

[0059] The pressure chamber 41 includes, for example, a pressure chamber body 41a to which pressure is applied by an actuator 21, and a descender 41b that connects the pressure chamber body 41a to the nozzle 43.

[0060] The pressure chamber body 41a opens, for example, to the pressurizing surface 25a of the first flow path member 25 and is closed by the actuator 21. Pressure is then applied to the liquid in the pressure chamber body 41a by the upward and / or downward bending deformation of the actuator 21. The descender 41b extends from the lower surface of the pressure chamber body 41a toward the discharge surface 3a. The cross-sectional area of ​​the descender 41b is smaller than the cross-sectional area of ​​the pressure chamber body 41a parallel to the pressurizing surface 25a.

[0061] The shape and dimensions of the pressure chamber body 41a may be set as appropriate. 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 may be a shape other than a circle, such as an ellipse or a rhombus. Also, the pressure chamber body 41a is thin, with a thickness smaller than the diameter in plan view. 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 constant in the vertical direction. However, the shape and / or dimensions of the cross-section of the pressure chamber body 41a may differ depending on the position in the vertical direction.

[0062] The shape and dimensions of the descender 41b may also be set as appropriate. In the illustrated example, the shape of the descender 41b is a straight column. Also, in the illustrated example, the shape of the cross section is circular. Unlike the illustrated example, the descender 41b may be inclined with respect to the vertical direction, or its diameter may change depending on its position in the vertical direction. Furthermore, the shape of the cross section may be a shape other than a circle, such as an ellipse.

[0063] The connection position of the descender 41b to the pressure chamber body 41a in a plan view may also be set as appropriate. In the illustrated example, the descender 41b is connected adjacent to the outer edge of the circular pressure chamber body 41a. In cases where the shape of the pressure chamber body 41a is elliptical or rhombic, unlike the illustrated example, the descender 41b may be connected to the longitudinal end of the pressure chamber body 41a, for example.

[0064] The nozzle 43 opens into a part of the bottom surface of the descender 41b. The nozzle 43 may open in the center of the bottom surface of the descender 41b, or it may open at a position away from the center (as shown in the illustration). The longitudinal cross-sectional shape of the nozzle 43 is tapered, with the diameter decreasing towards the discharge surface 3a side. However, the nozzle 43 may be partially or entirely reverse-tapered. The cross-sectional shape of the nozzle 43 is, for example, circular.

[0065] The supply channel 39 has, for example, a first supply channel 39A and a second supply channel 39B. Unlike the illustrated example, the supply channel 39 may have only one of the first supply channel 39A and the second supply channel 39B. In the supply channel 39, the connection position to the supply manifold 33, the connection position to the pressure chamber 41, the channel shape and dimensions may be set as appropriate. In the illustrated example, these are as follows.

[0066] The first supply channel 39A connects the supply manifold 33 and the pressure chamber body 41a. The first supply channel 39A extends upward from the top surface of the supply manifold 33, then extends in the direction of D5, then in the direction of D4, and then extends upward again to connect to the bottom surface of the pressure chamber body 41a. The shape and dimensions of the cross-section of the first supply channel 39A are generally constant over most of its length (e.g., more than 60%). The shape of the cross-section over this majority is rectangular.

[0067] The second supply channel 39B connects the supply manifold 33 and the descender 41b. The second supply channel 39B extends from the lower surface of the supply manifold 33 toward direction D5, then extends toward direction D1, and is connected to the side of the descender 41b. The cross-sectional shape and dimensions of the second supply channel 39B are generally constant over most of its length (e.g., more than 60%). The cross-sectional shape over this majority is rectangular.

[0068] For example, only one recovery channel 45 is provided in one individual channel 35. However, unlike the illustrated example, two or more recovery channels 45 may be provided. In the recovery channel 45, the connection position to the recovery manifold 37, the connection position to the pressure chamber 41, the channel shape, and the dimensions may be set as appropriate. In the illustrated example, these are as follows:

[0069] The recovery channel 45 connects the recovery manifold 37 and the descender 41b. The recovery channel 45 extends from the side of the recovery manifold 37 toward the D2 direction, then extends toward the D4 direction, and is connected to the side of the descender 41b. The shape and dimensions of the cross-section of the recovery channel 45 are generally constant over most of its length (e.g., more than 60%). The shape of the cross-section over this majority is rectangular.

[0070] As previously described, the multiple individual flow paths 35 connected to the same supply manifold 33 and the same recovery manifold 37 are arranged at a constant pitch along the manifold. Therefore, the connection points between the first supply flow path 39A and the supply manifold 33 are aligned at a constant pitch along the supply manifold 33. The same applies to the connection points between the second supply flow path 39B and the supply manifold 33, and between the recovery flow path 45 and the recovery manifold 37.

[0071] As shown in Figures 6(a) and 6(b), the first flow channel member 25 is formed by stacking a plurality of plates 47A to 47M. The various flow channels of the first flow channel member 25 are formed by holes or recesses formed in the plates 47A to 47M. The plurality of plates 47A to 47M may be formed of, for example, metal or resin. In the example shown in Figure 6(b), dampers (not shown) are provided above and below the recovery manifold 37.

[0072] As previously described, the pressure chamber 41 opens to the pressurized surface 25a. Unlike the illustrated example, a plate that closes the pressure chamber 41 may be provided. However, in this case, it can be considered a matter of whether the plate closing the pressure chamber 41 is considered as part of the first flow path member 25 or as part of the actuator 21. In the description of this disclosure, such a plate will be considered as part of the actuator 21.

[0073] (Actuator) As shown in Figure 2(a), the actuator 21 is, for example, a generally flat plate-shaped member and is joined to the pressurized surface 25a of the first flow channel member 25 (more specifically, the area shown by the dotted line in Figure 2(a)). Then, as shown in Figures 6(a) and 6(b), the actuator 21 closes the opening above the pressure chamber 41. The actuator 21 basically extends over the entire area where all the pressure chambers 41 are located. The actuator 21 has a displacement element 49 for each pressure chamber 41.

[0074] The configuration of the actuator 21 may be various known configurations or applications of known configurations. In the illustrated example, the actuator 21 is a so-called unimorph type piezoelectric actuator. Specifically, it is as follows.

[0075] The actuator 21 has a diaphragm 51, a common electrode 53, a piezoelectric layer 55, and individual electrodes 57, which are stacked in order from the pressure chamber 41 side. The diaphragm 51, common electrode 53, and piezoelectric layer 55 basically extend over the entire area where the pressure chamber 41 is located. An individual electrode 57 is provided for each pressure chamber 41. The individual electrode 57 has a shape similar to the planar shape of the pressure chamber 41 in a planar perspective view, and it overlaps the central side of the pressure chamber 41.

[0076] The portion of the piezoelectric layer 55 sandwiched between the individual electrodes 57 and the common electrode 53 is polarized in the thickness direction. Therefore, when a voltage is applied to the individual electrodes 57 and the common electrode 53, the piezoelectric layer 55 contracts or expands in a direction along its surface. This contraction or expansion is restricted by the diaphragm 51, and the displacement element 49 bends like a bimetallic strip towards the pressure chamber 41 or the opposite side. This applies pressure to the liquid in the pressure chamber 41.

[0077] The material and thickness of each layer of the actuator 21 may be set as appropriate. For example, the diaphragm 51 and the piezoelectric layer 55 may be made of lead zirconate titanate (PZT), NaNbO3, BaTiO3, (BiNa)NbO3, or BiNaNb5O 15 The common electrode 53 and individual electrodes 57 may be made of a ceramic material such as an Ag-Pd system or an Au system.

[0078] The common electrode 53 is, for example, supplied with a constant potential (reference potential). The individual electrodes 57 are, for example, supplied with the drive signal described above. The driving method of the displacement element 49 (or, from another perspective, the waveform of the drive signal) may be as appropriate. For example, the driving method may be a so-called pull-and-drive type.

[0079] (liquid) Figure 7 shows the properties of the liquid used in the dispensing device 1. In this figure, 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 properties of the first and second examples of liquids used in the dispensing device 1.

[0080] As shown in this figure, the liquid used in the discharge device 1 is a pseudoplastic fluid. To confirm, a pseudoplastic fluid is a non-Newtonian fluid in which viscosity decreases as the shear rate increases. The shear rate is sometimes called shear rate, velocity gradient, or strain rate. For example, the shear rate can be simply calculated as the difference in velocity between two positions separated from each other in a direction perpendicular to the flow direction, divided by the distance between the two positions. Viscosity can be simply calculated as the shear stress divided by the shear rate. The shear stress is sometimes called shear stress. For example, the shear stress can be simply calculated as the force that tries to slide two parallel surfaces (of the same area) separated from each other in a direction perpendicular to the flow direction, divided by the area of ​​one of the surfaces.

[0081] Furthermore, for pseudoplastic fluids, the viscosity η is given by η = k × D p-1 A fluid can be described as a power-law fluid if, when approximated by a power law, the exponent p is less than 1. Here, k is the viscosity coefficient and D is the shear rate. Note that viscosity η is a function of D and is therefore sometimes called apparent viscosity.

[0082] The liquid used in the discharge device 1 may or may not have thixotropy, meaning its viscosity decreases as the time it is subjected to shear stress increases.

[0083] Specific components and / or compositions of the pseudoplastic fluid may be various known ones or those applying known ones. For example, generally, ink and paint are pseudoplastic fluids. The liquids according to the first example and the second example whose characteristics are shown in FIG. 7 are general paints (in other words, paints available on the market). Specific characteristics of the pseudoplastic fluid may also be appropriate ones. One example is given below.

[0084] For example, the liquid may have a viscosity of 0.02 Pa·s or more and 0.4 Pa·s or less when the shear rate is 1000 s -1 . In the paint according to the first example whose characteristics are shown in FIG. 7, the viscosity when the shear rate is 1000 s -1 is 0.3 Pa·s. In the paint according to the second example, the viscosity when the shear rate is 1000 s -1 is 0.1 Pa·s. The liquid may have a viscosity of 0.1 Pa·s or more and 0.3 Pa·s or less when the shear rate is 1000 s -1 .

[0085] Also, for example, the liquid may have a viscosity of 0.5 Pa·s or more and 50 Pa·s or less when the shear rate is 0.01 s -1 . In the paint according to the first example whose characteristics are shown in FIG. 7, the viscosity when the shear rate is 0.01 s -1 is 5 Pa·s. In the paint according to the second example, the viscosity when the shear rate is 0.01 s -1 is 30 Pa·s. The liquid may have a viscosity of 5 Pa·s or more and 30 Pa·s or less when the shear rate is 0.01 s -1 .

[0086] Also, for example, when the viscosity of the liquid is approximated by the power law, the viscous coefficient k may be 1.0 or more and 1.5 or less, and the power exponent p may be 0.35 or more and 0.65 or less. In the paint according to the first example, the viscous coefficient k is 1.0 and the power exponent p is 0.65. In the paint according to the second example, the viscous coefficient k is 1.5 and the power exponent p is 0.35. The approximation formula may be specified, for example, by the least squares method.

[0087] (average viscosity) The following introduces the concept of average viscosity. Normally, viscosity exhibits different values ​​for each minute region within a flow path. However, the viscosity of each minute region is not always suitable for determining the viscosity of the liquid within the flow path member 19, and its calculation can also be difficult. Therefore, the viscosity averaged across different parts of the flow path of the flow path member 19 is referred to as the average viscosity. Average viscosity is a single value for each part within the flow path. For example, the average viscosity of a single supply manifold 33 refers to the average viscosity of the entire supply manifold 33.

[0088] The average viscosity may be calculated, for example, as follows. First, the relationship between the shear rate D and viscosity η in the liquid used in the discharge device 1 is determined. Various known methods may be used for this determination, and known literature may also be referenced. Next, an approximate formula representing the relationship between the determined shear rate D and viscosity η is obtained. The approximate formula may be an appropriate one, such as a power law. The fitting method may also be a known one, such as the least squares method. Next, the circulating flow rate U(m³) 3 Using the boundary condition ( / s), a fluid simulation is performed for each part of the flow path using the above approximation formula to determine the differential pressure ΔP (Pa) between the upstream and downstream ends of each part. Then, the average viscosity μ (Pa·s) is calculated by substituting the circulating flow rate U, differential pressure ΔP, and the dimensions (m) of each part into a predetermined formula.

[0089] An example of a formula for calculating the average viscosity μ is shown below.

[0090] The formula for the case where the flow channel shape is cylindrical with the flow direction as the axial direction is as follows: U=(πr 4 ΔP) / (8μL) (1) Here, r is the radius of the cross-section, and L is the length of the channel.

[0091] Furthermore, the formula for the case where the flow channel shape is a prismatic shape (rectangular parallelepiped) with the flow direction as the axial direction is as follows: U=(w 3(hΔP) / (4μL) ×(16 / 3-1024 / π 5 × w / h ×Σ(1 / q 5 ×tanh(qπh / 2w)) (2) Here, q = 1, 3, 5, 7, 9, and 11, and Σ is the sum of the six (1 / q) values ​​obtained by substituting these six values ​​for q. 5 This is the sum of ×tanh(qπh / 2w). w is the width of the channel. h is the height of the channel. L is the length of the channel.

[0092] In the reservoirs (29 and 31) and manifolds (33 and 37), the flow rate U differs between the upstream and downstream sides. In this case, for example, the highest flow rate, the lowest flow rate, or the average flow rate may be used. The average viscosity described below may be considered as calculated using any of the above flow rates. 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 may be compared. For example, the average viscosities calculated using the highest flow rate (lowest average viscosity) may be compared, the average viscosities calculated using the lowest flow rate (highest average viscosity) may be compared, or the average viscosities calculated using the average flow rate (average average viscosity) may be compared. For example, the average viscosity described below may be considered as the average viscosity calculated using the highest flow rate (lowest average viscosity). For example, the average viscosity of the supply reservoir 29 and the supply manifold 33 may be considered as calculated using the flow rate furthest upstream. The average viscosity of the recovery reservoir 31 and the recovery manifold 37 can be considered to have been calculated using the flow rate at the furthest downstream point.

[0093] In the pressure chamber 41, or in the pressure chamber body 41a or descender 41b, the direction of liquid flow is not necessarily constant. In the following description, the average viscosity in these parts is calculated assuming the flow direction is from top to bottom. For example, the average viscosity in the descender 41b is calculated assuming the flow direction is from the pressure chamber body 41a to the nozzle 43.

[0094] (Average viscosity in the flow channel component) Figure 8 shows an example of the relative relationship between the average viscosity μ of each part of the flow channel in the flow channel member 19. In this figure, the horizontal axis corresponds to multiple parts of the flow channel in the flow channel member 19. The vertical axis shows the average viscosity μ at each part.

[0095] In the figure, the average viscosity μ2 represents the average viscosity μ of one of the multiple supply manifolds 33. Similarly, for the other flow paths, the average viscosity μ of one flow path is shown. The average viscosity μ3 of the supply flow path 39 may be considered as the average viscosity of either the first supply flow path 39A or the second supply flow path 39B.

[0096] The liquid discharge device 1 has a target flow rate for the circulating flow rate controlled by the flow rate setting unit 13, and the shape and dimensions of the flow path of the flow path member 19 are set so that the average viscosity relationship shown in the figure is satisfied. In other words, the flow path of the flow path member 19 has a flow path shape such that the relationship shown in Figure 8 is satisfied when the circulating flow rate is the target flow rate. In other words, the circulating flow rate is set to a value such that the average viscosity relationship shown in Figure 8 is satisfied in terms of the shape and dimensions of the flow path of the flow path member 19. For example, the circulating flow rate is set to a value such that the average viscosity of the liquid in the supply flow path 39 is half or less of the average viscosity of the liquid in the supply manifold 33 in terms of the shape and dimensions of the flow path of the flow path member 19.

[0097] When the circulation flow rate is controlled by open-loop control, the circulation flow rate fluctuates significantly due to the amount of droplets discharged from the multiple nozzles 43. In this case, the relationship shown in Figure 8 may hold true, for example, for the circulation flow rate when no droplets are being discharged from all nozzles 43. In other words, the circulation flow rate when no droplets are being discharged from all nozzles 43 in a product can be identified as the target flow rate for that product. This concept can also be applied to feedback control systems where the circulating flow rate's ability to track the target flow rate is low.

[0098] In Figure 8, for example, the following relationship holds true for average viscosity.

[0099] The average viscosity μ3 of the liquid in the supply channel 39 (39A or 39B) may be lower than the average viscosity μ2 of the liquid in the supply manifold 33. More specifically, for example, the average viscosity μ3 may be 1 / 2, 1 / 3, or 1 / 5 of the average viscosity μ2.

[0100] In this case, for example, because the average viscosity μ3 of the liquid in the supply channel 39 is low, the liquid can be smoothly supplied from the supply channel 39 to the pressure chamber 41. Also, because the average viscosity μ2 is high in the supply manifold 33, pressure waves are easily attenuated. As a result, the probability of pressure waves leaking from the pressure chamber 41 to the supply manifold 33 via the supply channel 39 propagating to other pressure chambers 41 via other supply channels 39 is reduced. In other words, so-called fluid crosstalk can be reduced.

[0101] The same relationship as described above may also hold between the recovery channel 45 and the recovery manifold 37. That is, the average viscosity μ5 of the liquid in the recovery channel 45 may be lower than the average viscosity μ6 of the liquid in the recovery manifold 37. More specifically, for example, the average viscosity μ5 may be 1 / 2, 1 / 3, or 1 / 5 of the average viscosity μ6. In this case as well, the same effect as described above will be achieved.

[0102] The average viscosity μ2 of the supply manifold 33 may be lower than the average viscosity μ1 of the supply reservoir 29. More specifically, for example, the average viscosity μ2 may be 1 / 2, 1 / 3, or 1 / 4 of the average viscosity μ1.

[0103] In this case, for example, the low average viscosity μ2 of the liquid in the supply manifold 33 allows for a smooth supply of liquid from the supply manifold 33 to the supply channel 39. Furthermore, the high viscosity in the supply reservoir 29 causes pressure waves to attenuate easily, thus reducing crosstalk caused by the propagation of pressure waves through the supply reservoir 29.

[0104] The same relationship as described above may also hold between the recovery manifold 37 and the recovery reservoir 31. That is, the average viscosity μ6 of the liquid in the recovery manifold 37 may be lower than the average viscosity μ7 of the liquid in the recovery reservoir 31. More specifically, for example, the average viscosity μ6 may be 1 / 2, 1 / 3, or 1 / 5 of the average viscosity μ7. In this case as well, the same effect as described above will be achieved.

[0105] The average viscosity μ4 of the descender 41b may be higher than the average viscosity μ5 of the recovery channel 45. More specifically, for example, the average viscosity μ4 may be 1.5 times or more the average viscosity μ5.

[0106] In this case, for example, if the viscosity is high, the resistance to bubble movement increases, which increases the likelihood that bubbles that have entered the descender 41b from the nozzle 43 can be recovered from the recovery channel 45.

[0107] The same relationship as described above may also hold between the descender 41b and the supply channel 39. That is, the average viscosity μ4 of the descender 41b may be higher than the average viscosity μ3 of the supply channel 39. More specifically, for example, the average viscosity μ4 may be 1.5 times or more, or 2 times or more, the average viscosity μ3.

[0108] In this case, for example, because the average viscosity μ3 of the supply channel 39 is low, liquid can be supplied smoothly to the descender 41b. As a result, for example, the probability that the liquid supply to the descender 41b will not keep up due to continuous liquid discharge is reduced.

[0109] The average viscosity μ2 of the supply manifold 33 may be higher than the average viscosity (μ3, μ4, and μ5) of each individual flow path 35 (excluding the pressure chamber body 41a). More specifically, for example, the average viscosity μ2 may be 1.5 times or more than any of the average viscosities μ3, μ4, and μ5.

[0110] In this case, for example, the low average viscosity μ in the individual flow path 35 allows for a smooth supply of liquid to the nozzle 43. Furthermore, the high average viscosity μ in the supply manifold 33 causes the pressure leaking from the individual flow path 35 into the supply manifold 33 to dissipate quickly. Therefore, fluid crosstalk is less likely to occur.

[0111] The same relationship as described above may also hold between the recovery manifold 37 and the individual flow channels 35. That is, the average viscosity μ6 of the liquid in the recovery manifold 37 may be higher than the average viscosity (μ3, μ4, and μ5) of each flow channel (μ3, μ4, and μ5) of the individual flow channels 35. More specifically, for example, the average viscosity μ6 may be 1.5 times or more than any of the average viscosities μ3, μ4, and μ5. In this case as well, the same effect as described above will be achieved.

[0112] (Example of values ​​such as average viscosity) There are countless combinations of liquid properties, circulation flow rate, flow path shape and dimensions, etc., that can achieve the above-described relationship of average viscosity μ, and these can be appropriately set according to the specific technical field to which the discharge device 1 is applied. Below, an example of values ​​when a general paint described with reference to Figure 7 is used is shown.

[0113] The circulation flow rate may be, for example, 50 ml / min to 300 ml / min. The pressure at nozzle 43 when no liquid is being discharged may be ±2 kPa relative to atmospheric pressure (approximately 100 kPa). The pressure difference between the supply port 3b and the return port 3c may be between 40 kPa and 160 kPa.

[0114] In the supply reservoir 29 and the recovery reservoir 31, the width w may be 4 mm or more and 20 mm or less, the height h may be 3 mm or more and 15 mm or less, and the length L may be 200 mm or more and 800 mm or less. In the supply manifold 33 and the recovery manifold 37, the width w may be 0.2 mm or more and 2 mm or less, the height h may be 0.5 mm or more and 6 mm or less, and the length L may be 5 mm or more and 20 mm or less. In the first supply channel 39A, the width w and height h may each be 50 μm or more and 200 μm or less. In the second supply channel 39B, the width w may be 50 μm or more and 200 μm or less, and the height h may be 25 μm or more and 200 μm or less. In the recovery channel 45, the width w may be 70 μm or more and 200 μm or less, and the height h may be 80 μm or more and 200 μm or less. The length L of the supply channel 39 and the recovery channel 45 may be 300 μm or more and 1500 μm or less. In the descender 41b, the radius r may be 50 μm or more and 250 μm or less, and the length L may be 0.5 mm or more and 2 mm or less. In the nozzle 43, the radius r may be 5 μm or more and 50 μm or less.

[0115] An example of calculating the average viscosity μ under the above conditions is shown below. Note that the average viscosity μ for descender 41b was calculated using equation (1), and the average viscosity μ for the other flow paths was calculated using equation (2). The average viscosity μ in the supply reservoir 29 and the recovery reservoir 31 is between 0.4 Pa·s and 2 Pa·s. The average viscosity μ in the supply manifold 33 and the recovery manifold 37 is between 0.1 Pa·s and 0.4 Pa·s. The average viscosity μ in the supply flow path 39 and the recovery flow path 45 is between 0.01 Pa·s and 0.1 Pa·s. The average viscosity μ in descender 41b is between 0.05 Pa·s and 0.2 Pa·s.

[0116] (fluid resistance) Fluid resistance (N·s / m) within the flow channel member 19 5 ) may be set as appropriate. For example, the fluid resistance may be set such that both of the following conditions 1 and 2 are satisfied.

[0117] Condition 1: (1 / 2) × R r ×U(1+1 / m), (1 / 2) × R m The sum of ×(U / m)×(1+1 / n) is It is smaller than 2σ / r. Condition 2: R r <1 / 10×R m ×(1 / m) Here, R r R is the fluid resistance of the liquid in the supply reservoir 29. m m 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) for each supply manifold 33. U is the flow rate of the liquid flowing into the supply reservoir 29 (m 3 The value is ( / s). σ is the surface tension of the liquid (N / m). r is the radius of the nozzle 43 (m).

[0118] Here, supply manifolds 33 connected only to dummy individual flow paths that are not capable of discharging droplets are ignored. It is also assumed that each supply manifold 33 has the same number of nozzles 43 connected to it. Furthermore, it is assumed that the pitch of 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.

[0119] (1 / 2) × R in condition 1 r ×U(1+1 / m) corresponds to the pressure drop within the supply reservoir 29 (pressure difference between upstream and downstream). Specifically, the pressure drop from the upstream end of the supply reservoir 29 to the first supply manifold 33 is U×R r / m, the pressure drop from the first supply manifold 33 to the second supply manifold is (UU / m) × R r It is calculated as / m. And the sum of the pressure drops from the upstream end to the downstream end is U × R r / m+(UU / m)×R r / m+…+U / m× / R r / m results in the above (1 / 2) × R r The result ×U(1+1 / m) is obtained.

[0120] (1 / 2) × R in condition 1 m ×(U / m)×(1+1 / n) corresponds to the pressure drop (pressure difference between upstream and downstream) within a single supply manifold 33. This equation is derived in the same way as the pressure drop within the supply reservoir 29 described above. That is, in the equation relating to the supply reservoir 29, the fluid resistance R of the supply reservoir 29 is used. r 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.

[0121] Under condition 1, (1 / 2) × R r ×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 upstream individual channel 35 and the downstream individual channel 35. The upstream individual channel 35 is the individual channel 35 connected to the upstreammost part of the supply manifold 33, which is connected to the upstreammost part of the supply reservoir 29. The downstream individual channel 35 is the individual channel 35 connected to the downstreammost part of the supply manifold 33, which is connected to the downstreammost part of the supply reservoir 29. Since the pressure drop in the individual channels 35 is approximately equal among multiple individual channels 35, the above sum corresponds to the pressure difference across all nozzles 43 (the pressure difference between the nozzle 43 with the highest pressure and the nozzle 43 with the lowest pressure).

[0122] Furthermore, when the above sum is less than 2σ / r, it is easy to maintain the meniscus under atmospheric pressure in all nozzles 43. Regarding condition 1, as already mentioned, the supply manifold 33 and the dummy individual flow paths connected only to it may be ignored. Also, the number of connected individual flow paths 35 may be less in the uppermost supply manifold 33 or the lowermost supply manifold 33 than in the other supply manifolds 33. In this case, for example, the uppermost supply manifold 33 or the lowermost supply manifold 33 may be ignored, or conversely, it may be assumed that the uppermost supply manifold 33 or the lowermost supply manifold 33 has the same number of individual flow paths 35 connected to it as in the other supply manifolds 33.

[0123] Condition 2 is the fluid resistance R of the supply reservoir 29. r And the fluid resistance R of the supply manifold 33 m This shows the relationship between the two. 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, and therefore the fluid resistance R m Multiplying this by 1 / m gives the fluid resistance R r And, fluid resistance R m This is being compared. And, if condition 2 is true, then the fluid resistance R of the supply reservoir 29 is... r The fluid resistance R of the supply manifold 33 m This means it is extremely small in comparison to [another entity].

[0124] For example, in conventional technology, R r R m It is approximately 1 / 5 of ×(1 / m). On the other hand, in this embodiment, R r R m ×(1 / m) may be set to 1 / 40 or more and less than 1 / 10. Of course, in this embodiment as well, as in the prior art, R r R m It's acceptable to use approximately 1 / 5 of ×(1 / m).

[0125] When condition 2 is met, for example, liquid flows more easily from the supply reservoir 29 to the locations of the multiple supply manifolds 33, and the difference in flow rates between the multiple supply manifolds 33 is mitigated. As a result, liquid can be supplied stably to all of the supply manifolds 33.

[0126] In addition to conditions 1 and 2, the fluid resistance may be set such that the following condition 3 is satisfied. Condition 3: R m <1 / 10×R n ×(1 / n) Here, R n This is the fluid resistance in nozzle 43.

[0127] Condition 3 is the fluid resistance R of the supply manifold 33. m This shows the relationship between the fluid resistance of the individual flow channels 35 and the fluid resistance R. n Since the fluid resistance of the individual channel 35 is far greater than that of other parts of the individual channel 35, the fluid resistance of the individual channel 35 is greater than that of the nozzle 43. n It is approximated by the following. Also, since 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, the fluid resistance R n Multiplying this by 1 / n gives the fluid resistance R m And, fluid resistance R n It is comparing the two.

[0128] If condition 3 is true, then the fluid resistance R of the supply manifold 33 is low. m The fluid resistance R of nozzle 43 n This means that it is extremely small in comparison to R. For example, in conventional technology, m R n It is approximately 1 / 6 of ×(1 / n). Furthermore, in this embodiment as well, as in the prior art, R m R n It's acceptable to use approximately 1 / 6 of ×(1 / n). For example, R m R n It is acceptable to consider it as between 1 / 10 and 1 / 4 of ×(1 / n).

[0129] When condition 3 is met, for example, liquid flows more easily from the supply manifold 33 to the locations of the multiple individual flow channels 35, and the difference in flow rates between the multiple individual flow channels 35 is mitigated. As a result, liquid can be supplied stably to all of the individual flow channels 35.

[0130] The example of flow path dimensions shown in Figure 8 as an example of dimensions that achieve the average viscosity may be used as an example of flow path dimensions that satisfy conditions 1 to 3.

[0131] (modified version) Figure 9 is a schematic cross-sectional view of an individual channel 235 according to a modified example.

[0132] The pressure chamber 241 of the individual flow path 235 has a pressure chamber body 241a and a descender 241b, similar to the pressure chamber 41 of the embodiment. However, the descender 241b has a first portion 241ba and a second portion 241bb, which have different cross-sectional areas.

[0133] 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. Furthermore, the cross-sectional area of ​​the second part 241bb is larger than that of the first part 241ba.

[0134] The first section 241ba and the second section 241bb have different average viscosities due to differences in their cross-sectional areas. For example, the average viscosity of the liquid in the second section 241bb is higher than the average viscosity of the liquid in the first section 241ba. In other words, the average viscosity in the descender 241b increases gradually as it approaches the pressure chamber body 41a from the nozzle 43. Note that the increase in average viscosity may occur in two or more stages, not just one. In other words, the descender may have a third section, etc., in addition to the first and second sections.

[0135] As in this modified example, when the average viscosity of the second part 241bb, which is located closer to the pressure chamber body 241a than the first part 241ba, is higher than the average viscosity of the first part 241ba, for example, bubbles that have entered the descender 241b from the nozzle 43 will have difficulty moving toward the pressure chamber body 241a. Consequently, the likelihood of bubbles accumulating in the pressure chamber body 241a and degrading the discharge characteristics will decrease.

[0136] Furthermore, if at least one of the two flow channels whose average viscosity is being compared has a portion with a different shape, the average viscosity of the portions where the two flow channels meet may be compared. For example, in the modified individual flow channel 235, when comparing the average viscosity of the recovery flow channel 45 with the average viscosity of the descender 241b, the average viscosity of the second portion 241bb directly connected to the recovery flow channel 45 may be used for comparison, rather than the average viscosity of the entire descender 241b. This is because the average viscosity of the second portion 241bb has a greater influence on the flow between the recovery flow channel 45 and the descender 241b.

[0137] The technology relating to this disclosure is not limited to the embodiments and modifications described above, and may be implemented in various forms.

[0138] For example, a liquid dispensing device is not limited to a piezoelectric type that applies pressure to the liquid using a piezoelectric element. A liquid dispensing device may also be a thermal type that generates bubbles in the liquid using heat, and applies pressure to the liquid due to the generation of these bubbles to dispense droplets.

[0139] The flow path configuration may be various configurations other than those shown in the illustration. For example, adjacent individual flow paths may share a portion of each other. For example, a portion of the recovery flow path on the recovery manifold side may be shared by adjacent individual flow paths.

[0140] The average viscosity setting may also be different from that of the embodiment. For example, the average viscosity μ3 of the supply channel 39 may be greater than the average viscosity μ5 of the recovery channel 45 or 1.5 times that, contrary to the embodiment. In this case, the liquid in the descender 41b is less likely to flow back when droplets are discharged (it is less likely to flow in the opposite direction to the circulation direction). Also, liquid and / or bubbles flow more easily into the recovery channel. [Explanation of Symbols]

[0141] 1...Liquid discharge device, 3...Head, 13...Flow rate setting unit, 19...Flow path member, 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.

Claims

1. The flow path includes a channel configured to carry a predetermined liquid having pseudoplastic properties, and the flow path is Supply reservoir, Multiple supply manifolds connected to the aforementioned supply reservoir, Multiple pressure chambers connected one-to-one to multiple supply channels, Multiple recovery channels connected separately to the aforementioned multiple pressure chambers, Multiple recovery manifolds for recovering the liquid from the multiple recovery channels, A flow path member having a recovery reservoir connected to the plurality of recovery manifolds for recovering the liquid from the plurality of recovery manifolds, An actuator configured to apply pressure to the liquid in the plurality of pressure chambers and to discharge droplets from a plurality of nozzles connected one-to-one to the plurality of pressure chambers, A pump configured such that the liquid flows sequentially through the supply reservoir, the plurality of supply manifolds, the plurality of supply channels, the plurality of pressure chambers, the plurality of recovery channels, the plurality of recovery manifolds, and the recovery reservoir, The system includes a controller configured to adjust the flow rate of the liquid to a predetermined target flow rate, Each of the aforementioned multiple pressure chambers is A pressure chamber body to which pressure is applied by the actuator, It has a descender connecting the pressure chamber body and the nozzle, The aforementioned recovery channel is connected to the descender, The aforementioned flow path has a flow path shape such that, when the flow rate is the target flow rate, the average viscosity of the liquid in the descender is 1.5 times or more the average viscosity of the liquid in the recovery flow path. Device.

2. The cross-sectional area of ​​the inlet surface of the supply channel or the recovery channel perpendicular to the flow direction of the liquid is S3, When S4 is the cross-sectional area of ​​the outlet surface of the descender that is perpendicular to the direction of liquid flow, S4 > S3 The apparatus according to claim 1.

3. Let S1 be the cross-sectional area of ​​the inlet surface of the nozzle perpendicular to the flow direction of the liquid. When S3 is the cross-sectional area of ​​the inlet surface of the supply channel or the recovery channel that is perpendicular to the flow direction of the liquid, S3 > S1 The apparatus according to claim 1 or 2.

4. The cross-sectional area of ​​the discharge surface of the nozzle perpendicular to the flow direction of the liquid is S2. When S3 is the cross-sectional area of ​​the inlet surface of the supply channel or the recovery channel that is perpendicular to the flow direction of the liquid, S3 > S2 The apparatus according to any one of claims 1 to 3.

5. The descender is Part 1 and, It has a second portion located closer to the pressure chamber body than the first portion, The flow path has a flow path shape such that, when the flow rate is the target flow rate, the average viscosity of the liquid in the second section is higher than the average viscosity of the liquid in the first section. The apparatus according to any one of claims 1 to 4.

6. A method using the apparatus described in any one of claims 1 to 5, The aforementioned liquid has a shear rate of 1000 s. －１ The viscosity at this point is 0.02 Pa·s or more and 0.4 Pa·s or less, and the shear rate is 0.01 s. －１ A pseudoplastic fluid with a viscosity of 0.5 Pa·s to 50 Pa·s is used. method.

7. The apparatus according to any one of claims 1 to 5, wherein the pump is a vacuum pump.

8. The apparatus according to any one of claims 1 to 5 and 7, wherein the target flow rate is 50 ml / min or more and 300 ml / min or less.

9. The cross-sectional area of ​​the inlet surface of the nozzle perpendicular to the direction of liquid flow is S1, When S2 is the cross-sectional area of ​​the discharge surface of the nozzle perpendicular to the direction of liquid flow, S1 > S2 The apparatus according to claim 3 or 4.

10. A method, The flow path member includes a supply reservoir, a plurality of supply manifolds connected to the supply reservoir, a plurality of supply channels connected to each of the plurality of supply manifolds (two or more), a plurality of pressure chambers connected one-to-one to the plurality of supply channels, a plurality of recovery channels connected separately to the plurality of pressure chambers, a plurality of recovery manifolds to which two or more of the plurality of recovery channels are each connected, and a recovery reservoir connected to the plurality of recovery manifolds, through which a pseudoplastic liquid is sequentially flowed. Pressurize the liquid in the plurality of pressure chambers and discharge droplets from a plurality of nozzles connected one-to-one to the plurality of pressure chambers. Each of the aforementioned multiple pressure chambers is The pressure chamber body to which pressure is applied by the actuator, and It has a descender that connects the pressure chamber body to the corresponding nozzle, The aforementioned recovery channel is connected to the descender, A method for adjusting the flow rate of the liquid such that the average viscosity of the liquid in the descender is 1.5 times or more the average viscosity of the liquid in the plurality of recovery channels.

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