CN116811431A

CN116811431A - Liquid ejecting apparatus and liquid ejecting method

Info

Publication number: CN116811431A
Application number: CN202310899871.0A
Authority: CN
Inventors: 宫原崇; 穗积大辅; 石原笃志
Original assignee: Kyocera Corp
Current assignee: Kyocera Corp
Priority date: 2020-03-30
Filing date: 2020-06-16
Publication date: 2023-09-29
Also published as: CN115315355A; EP4112316A4; JPWO2021199451A1; CN115315355B; US20230021666A1; JP6889810B1; EP4112316A1

Abstract

The present application relates to a liquid ejecting apparatus and a liquid ejecting method. The liquid ejecting apparatus includes: a flow path member having a flow path through which a pseudoplastic liquid flows; an actuator that applies pressure to the liquid in the flow path to eject the liquid droplets from the flow path member; and a flow rate setting unit that sets the flow rate of the liquid in the flow path. The flow rate setting unit adjusts the circulation flow rate of the liquid circulating in 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 in this order to a predetermined 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 half or less of the average viscosity of the liquid in the supply manifold when the circulation flow rate is the target flow rate.

Description

Liquid ejecting apparatus and liquid ejecting method

The present application is a divisional application of the application patent application with the application number 202080098938.5, the application name of the liquid ejecting apparatus and the liquid ejecting method, and the international application date of the application of year 2020, month 16 (priority date 2020/03/30).

Technical Field

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

Background

Liquid ejecting apparatuses such as ink jet printers are known. Patent document 1 discloses an ink jet recording apparatus using thixotropic ink as the ink.

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open No. 8-216425

Disclosure of Invention

The liquid ejecting apparatus 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 in which a pseudoplastic liquid flows. The actuator applies pressure to the liquid in the flow path to eject liquid droplets from the flow path member. The flow rate setting unit sets a flow rate of the liquid in the flow path. The flow path has 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 are supplied with the liquid from the supply reservoir. The plurality of supply channels are provided in a number of 2 or more with respect to the plurality of supply manifolds, and are connected to any one of the plurality of supply manifolds, respectively, and the liquid is supplied from the connected supply manifold. The plurality of pressure chambers and the plurality of supply channels are connected to each other, respectively, the liquid is supplied from the plurality of supply channels, and pressure is applied by the actuator. The plurality of nozzles and the plurality of pressure chambers are connected to each other, respectively, so that the liquid from the pressure chambers is discharged to the outside. The plurality of recovery flow paths and the plurality of pressure chambers are connected to each other, respectively, and the liquid is recovered from the plurality of pressure chambers. The plurality of recovery manifolds are connected to any two or more of the plurality of recovery channels, respectively, and recover the liquid from the plurality of recovery channels. The recovery reservoir is connected to the plurality of recovery manifolds from which the liquid is recovered. The flow rate setting unit adjusts the circulation flow rate of the liquid circulating in 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 in this order to a predetermined target flow rate. The flow path has a flow path shape in which an average viscosity of the liquid in the supply flow path is half or less of an average viscosity of the liquid in the supply manifold when the circulation flow rate is the target flow rate.

A liquid discharge method according to an aspect of the present disclosure is a liquid discharge method using the liquid discharge apparatus, and using a shear rate of 1000s ^-1 The viscosity is 0.02 Pa.s or more and 0.4 Pa.s or less, and the shear rate is 0.01s ^-1 A pseudoplastic fluid having a viscosity of 0.5pa·s or more and 50pa·s or less is used as the liquid.

Drawings

Fig. 1 is a schematic view showing the overall configuration of a liquid ejecting apparatus according to the embodiment.

Fig. 2 (a) is an exploded perspective view of a head of the liquid ejecting apparatus according to the embodiment, and fig. 2 (b) is a perspective view of a second flow path member included in the head.

Fig. 3 (a) and 3 (b) are top perspective views of the head according to the embodiment.

Fig. 4 is an enlarged view of area IV of fig. 3 (b).

Fig. 5 is a perspective view of an individual flow path of the head according to the embodiment.

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.

Fig. 7 is a diagram showing characteristics of a liquid used in the liquid ejecting apparatus according to the embodiment.

Fig. 8 is a diagram showing an example of average viscosity of each portion of the flow path according to the embodiment.

Fig. 9 is a schematic cross-sectional view of an individual flow path according to a modification.

Description of the reference numerals-

A liquid discharge device, 3..head, 13..flow rate setting section, 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.

Detailed Description

Embodiments of the present disclosure will be described below with reference to the drawings. The drawings described below are schematic. Therefore, details are sometimes omitted. The dimensional ratio does not necessarily coincide with the actual dimensional ratio. The dimensional ratios of the drawings are not necessarily identical to each other. Sometimes specific dimensions are larger than actual, and specific shapes are exaggerated.

In the drawings, arrows indicating the directions D1 to D6 are sometimes marked. These directions are directions parallel to the ejection face 3a described later. The D2 direction and the D5 direction are directions parallel to the longitudinal direction of the head 3 described later, for example, and are so-called main scanning directions from another point of view. The D3 direction and the D6 direction are directions orthogonal to the D2 direction and the D5 direction. The D1 direction and the D4 direction are directions inclined with respect to the D3 direction and the D6 direction.

(integral Structure of liquid ejection device)

Fig. 1 is a diagram schematically showing a main part configuration of a liquid ejecting apparatus 1 (hereinafter, sometimes referred to as "ejecting apparatus 1") according to the embodiment.

For example, as in an inkjet printer, the ejection device 1 is configured as a device that ejects liquid droplets from the ejection surface 3a of the head 3 toward the object 101 to adhere the liquid to the surface of the object 101. In the following description, for convenience, the direction in which the ejection surface 3a faces may be defined as a lower direction, and terms such as an upper surface and a lower surface may be used.

The specific type (application) of the ejection device 1 may be set to an appropriate type (application). For example, the discharge device 1 may be a device that prints characters and graphics (records information from another point of view) by adhering ink to a recording medium (for example, paper) that is the object 101. That is, the discharge device 1 may be a so-called printer. For example, the discharge device 1 may be a device for attaching paint to a vehicle body of an automobile as the object 101 to decorate the vehicle body. For example, the discharge device 1 may be a device that forms a wiring by adhering a liquid including conductive particles to a circuit board as the object 101.

Further, unlike the illustrated example, the ejection device 1 may not be a device that attaches liquid to the object 101. For example, the discharge device 1 may be a device for discharging a liquid chemical that reacts with a substance in a container into the container, or may be a device for scattering a disinfectant into the atmosphere.

As understood from the above description of a specific kind of the discharge device 1, the material, shape, and size of the object 101 can be appropriately set. Fig. 1 is a schematic diagram, and thus an object 101 is represented by a rectangular parallelepiped. Examples of the material of the object 101 include paper, cloth, resin, metal, ceramic, wood, and a combination thereof. Examples of the type of the object 101 include a recording medium (e.g., a roll paper or a sheet of paper), a circuit board, clothing, a container for beverage, a container for storage, a case of an electronic device, and a body of an automobile. The object 101 or the region where the liquid is adhered may be narrower or wider than the discharge surface 3a from which the liquid droplet is discharged.

As understood from the above description of the specific type of the ejection device 1, the type of the liquid may be appropriately set. Examples of the type of liquid include ink, paint, liquid containing conductive particles, chemical, and disinfectant. The ink and the paint may be distinguished according to the presence or absence of an organic solvent, the presence or absence of a function of protecting the surface of the object 101, or the like. However, such distinction may not be performed. In the following description, the paint may be replaced with ink as appropriate. And vice versa. The paint may or may not include a pigment for coloring purposes (for example, only gloss application and/or protection of the object 101), and may not include a pigment (colorless paint).

The discharge device 1 includes, for example, a head 3 for discharging liquid droplets, and a moving unit 5 for moving the head 3 and the object 101 relative to each other. The head 3 has an ejection face 3a with a plurality of nozzles (described later) for ejecting droplets. The moving unit 5 relatively moves the ejection face 3a and the surface of the object 101 along the ejection face 3a while maintaining a state in which the ejection face 3a faces the surface of the object 101, for example. The direction of the relative movement is, for example, the D3 direction or the D6 direction. As understood from the inkjet printer as a specific example of the ejection device 1, droplets are ejected from the ejection surface 3a in synchronization with the above-described relative movement, and thereby the droplets adhere to an area larger than the area of the area where the plurality of nozzles are arranged.

The discharge 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. I.e. the liquid circulates in the head 3 and in the tank 7. By circulating the liquid in this way, the likelihood of liquid, for example, becoming lodged in the head 3 is reduced. Further, the possibility of solidification of the retained liquid or precipitation of components in the retained liquid can be reduced. In the present embodiment, the liquid is circulated, so that the shear rate of the liquid and, further, the viscosity of the liquid can be adjusted as will be described later.

The ejection device 1 includes: a circulation operation unit 9 for applying pressure to the liquid to circulate the liquid; and a control unit 11 for controlling the respective units (for example, the head 3, the moving unit 5, and the circulation unit 9). The combination of the circulation operation unit 9 and the control unit 11 may be regarded as a flow rate setting unit 13 that sets a flow rate of the liquid circulated in the head 3 (hereinafter referred to as a circulation flow rate). The circulation flow rate can be regarded as the same as the flow rate of the liquid flowing out of the head 3 from the recovery port 3c, for example.

The discharge device 1 may have only one head 3 (and a tank 7) as in a monochrome printer, or may have a plurality of heads 3 (and a plurality of tanks 7) for discharging different types of liquids as in a color printer. The discharge device 1 may have a plurality of heads 3 for discharging the same type of liquid. The plurality of heads 3 ejecting the same kind of liquid is advantageous, for example, in shortening the time for attaching the liquid to a fixed area or in improving the dot density. In the following description, for convenience, only 1 head 3 is mentioned.

(moving part)

The moving unit 5 can move the object 101 relative to the head 3 at least in one of the direction D3 and the direction D6, for example. As described above, this direction is the moving direction when the liquid droplet is ejected, and is the so-called sub-scanning direction. The moving unit 5 may move the head 3 and the object 101 relative to each other in directions other than the D3 direction and the D6 direction. Examples of other directions in which the relative movement can be achieved include a D2 direction and a D5 direction orthogonal to the D3 direction and the D6 direction, and a direction orthogonal to the ejection face 3a (a direction in which the head 3 approaches the object 101, and a direction in which the head 3 is away from the object). The moving unit 5 may also be configured to rotate the head 3 and the object 101 relative to each other.

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

For example, in the case where the discharge device 1 is a so-called line printer, the moving unit 5 may be configured as a device that conveys a recording medium (for example, paper) that is the object 101. The apparatus includes, for example, a plurality of rollers that generate friction by contact with a recording medium, and a motor that rotates the plurality of rollers. Further, for example, in the case where the ejection device 1 is a so-called serial printer, the moving section 5 may include: a device that conveys a recording medium as an object 101 in a predetermined conveyance direction; and means for moving the head 3 in a direction orthogonal to the transport direction and along the recording medium.

Further, for example, the ejection device 1 may include a belt conveyor that conveys any kind of object 101. Further, for example, the ejection device 1 may include a movable table on which any kind of object 101 is placed. Further, for example, the ejection device 1 may include an industrial robot that moves any kind of object 101 and/or an industrial robot that moves the head 3. Examples of the industrial robot include a vertical multi-joint robot (multi-joint robot in a narrow sense), a horizontal multi-joint robot, a rectangular robot, and a parallel link robot.

(tank and circulation operation unit)

The tank 7 and the circulation operation unit 9 may be the same as or applied to a tank and a circulation operation unit in a known ink jet printer for circulating a liquid, for example.

For example, the tank 7 may be configured to accommodate the liquid supplied to the head 3 and the liquid recovered from the head 3 in the same space. The tank 7 may be configured to accommodate the liquid supplied to the head 3 and the liquid recovered from the head 3 in different spaces and to flow the liquid from the latter space to the former space. In this case, the tank 7 may have two spaces by dividing one tank by a partition wall, or may have two spaces by having two tanks connected to each other through a flow path. The inside of the tank 7 (the space described above) can be opened to the atmosphere, and the electricity can be sealed. In the latter case, the pressure in the tank 7 may be adjusted to an appropriate pressure by a valve, a vacuum pump, or the like. Tank 7 may also have a main tank and a sub-tank having a smaller capacity than the main tank. The sub-tank intermediates the main tank and the head 3.

In the illustrated example, the circulation operation unit 9 includes: a pump 15 for sending liquid from the tank 7 to the head 3; a pressure sensor 17A for detecting the pressure of the liquid on the supply port 3b side; and a pressure sensor 17B for detecting the pressure of the liquid on the recovery port 3c side. The control unit 11 performs feedback control of the pump 15 based on the detection values of the pressure sensor 17A and the pressure sensor 17B, for example, so that the pressure difference between the supply port 3B and the recovery port 3c converges to a predetermined target value. Thereby, the circulation flow rate is feedback-controlled to the target flow rate.

Unlike the illustrated example, a pump 15 for sending the liquid from the recovery port 3c to the tank 7 may be provided instead of the pump 15 on the supply port 3b side. In addition, instead of the pump 15 for sending out the liquid, or in addition to this, the flow of the liquid may be generated by pressure control in the tank 7 by a vacuum pump or the like. The flow of the liquid may be generated by making the liquid level in the tank containing the liquid for supply higher than the liquid level in the tank containing the recovered liquid.

Instead of the pressure sensors 17A and 17B, or in addition to these, 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 for controlling the circulation flow rate. As understood from various modes of generating the flow of the liquid described above, a sensor for detecting the air pressure in the tank 7 may be provided instead of or in addition to these sensors, for controlling the circulation flow rate. Instead of the feedback control by the sensor, open loop control may be performed. That is, the sensor may not be provided.

The tank 7 and the circulation unit 9 are not moved in an absolute coordinate system by the moving unit 5, for example. Therefore, for example, in the case where the moving unit 5 moves the head 3 in the absolute coordinate system, the head 3 moves relative to the tank 7 and the circulation unit 9. In this case, the head 3 is connected to the tank 7 and the circulation unit 9 through a flow path formed of, for example, a flexible pipe. In addition, in the case where the moving unit 5 does not move the head 3 in the absolute coordinate system, the head 3 is fixed to the tank 7 and the circulation unit 9. In this case, the structure of the flow paths between the connector 3 and the tank 7 and between the connector and the circulation unit 9 is arbitrary. Unlike the above description, all or part of the tank 7 and the circulation operation unit 9 may be moved together with the head 3.

(control part)

The control unit 11 is constituted by a computer, for example. Although not particularly shown, the computer includes a CPU (Central Processing Unit ), a ROM (Read Only Memory), a RAM (Random Access Memory ), and an external storage device. The CPU executes programs stored in the ROM and/or the external storage device, thereby performing control of the head 3, the moving section 5, and the circulation operation section 9.

(head)

Fig. 2 (a) is an exploded perspective view of the head 3.

The head 3 has: a flow path member 19 (reference numeral is fig. 1) having a flow path through which the liquid flows; an actuator 21 for applying pressure to the liquid in the flow path member 19; and a signal transmission member 23 (not shown in fig. 1) for inputting a drive signal to the actuator 21. The flow path member 19 has: a first flow path member 25 having an ejection face 3a; and a second channel member 27 having a supply port 3b and a recovery port 3c. The surface of the first flow path member 25 opposite to the ejection surface 3a may be referred to as a pressing surface 25a.

The first channel member 25 and the second channel member 27 are each formed in a substantially flat plate shape, and overlap each other to form a substantially flat plate-shaped channel member 19. The liquid supplied to the supply port 3b is supplied from the second channel member 27 to the first channel member 25, and is discharged from the discharge surface 3 a. The liquid remaining without being discharged flows from the first channel member 25 to the second channel member 27, and is recovered from the recovery port 3c.

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, attached to the signal transmission member 23, for example, via the signal transmission member 23. The driver generates a driving signal having a given waveform based on the inputted 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 path member 19 in a pressure waveform corresponding to the waveform of the drive signal. Thereby, the liquid in the flow path member 19 is discharged from the discharge surface 3 a. The operation sharing between the control unit 11 and the actuator may be appropriately set, and the actuator may be understood as a part of the control unit 11.

(second flow passage Member, supply reservoir, and recovery reservoir)

Fig. 2 (b) is a perspective view of the second channel member 27. More specifically, the drawing is a drawing of the second flow path member 27 as viewed from the first flow path member 25 side, and the upper side of the paper surface in fig. 2 (b) corresponds to the lower side of the paper surface in fig. 1 and 2 (a). Fig. 3 (a) is a top perspective view of the head 3 from the side opposite to the ejection face 3 a. In this figure, the shape of the second flow path member 27 and the actuator 21 are shown.

As shown in fig. 2 b, the second flow path member 27 has two grooves (refer to reference numerals 29 and 31) formed on the surface on the first flow path member 25 side. These two grooves are blocked by the first flow path member 25, and constitute a supply reservoir 29 and a recovery reservoir 31 shown in fig. 2 (b) and 3 (a). 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 tank 31 is a flow path communicating with the recovery port 3c, and recovers the liquid from the flow path of the first flow path member 25 and guides the recovered liquid to the recovery port 3 c.

The supply reservoir 29 and the recovery reservoir 31 have portions (main portions 29a and 31 a) extending linearly along the longitudinal direction (D2 direction and D5 direction) of the head 3, for example. The main portions 29a and 31a have a length extending over the entire length of a longitudinal direction (D2 direction and D5 direction) of an arrangement region (an arrangement region of the actuator 21 described below with reference to fig. 3 a) of a plurality of nozzles (described later). The main portions 29a and 31a are located on opposite sides (the direction D3 and the direction D6) of the head 3 in the short side direction with respect to the arrangement region of the plurality of nozzles. In the description of the embodiment, only the main portions 29a and 31a are focused on for convenience, and the shapes, sizes, and the like of the supply reservoir 29 and the recovery reservoir 31 are described in some cases.

The supply port 3b communicates with, for example, one end (end in the direction D2) of the supply reservoir 29. The other end (end in the direction D5) of the supply reservoir 29 is the end (in other words, the dead end). The liquid in the supply reservoir 29 flows in the direction (D5 direction) from the one end to the other end. The recovery port 3c communicates with, for example, one end (end in the direction D5) of the recovery reservoir 31. The other end (end in the direction D2) of the recovery reservoir 31 is the end (in other words, the dead end). The liquid in the recovery liquid reservoir 31 flows from the other end in the direction of the one end (direction D5). The direction of the liquid flow in the supply reservoir 29 and the direction of the liquid flow in the recovery reservoir 31 are in the illustrated example identical to each other. Wherein the two may also be opposite to each other.

The supply reservoir 29 may have only the main portion 29a, or may have other portions. In the illustrated example, the supply reservoir 29 includes a portion (reference numeral omitted) extending obliquely from the main portion 29a toward the longitudinal direction of the head 3 and reaching the supply port 3 b. Likewise, the recovery tank 31 may have only the main portion 31a, or may have other portions. In the illustrated example, the recovery tank 31 has a portion (reference numeral omitted) extending obliquely from the main portion 31a toward the longitudinal direction of the head 3 and reaching the recovery port 3 c.

The cross-sectional shapes and dimensions of the supply reservoir 29 and the recovery reservoir 31 (for example, the main portions 29a and 31a thereof) may be fixed irrespective of the positions in the longitudinal direction of the flow paths, or may be different depending on the positions. In the description of the embodiment, the former is sometimes taken as an example. Further, the shape of the cross section may be a rectangular shape or the like as appropriate. The various dimensions of the supply reservoir 29 and the recovery reservoir 31 may be set appropriately according to the specific technical field in which the ejection device 1 is applied.

In the illustrated example, the second flow path member 27 includes a slit 27a through which the signal transmission member 23 is inserted (fig. 2 (a) and fig. 2 (b)) and a recess 27b that accommodates the actuator 21 (fig. 2 (b) and fig. 3 (a)) in addition to the two grooves serving as the supply reservoir 29 and the recovery reservoir 31. The slit 27a penetrates the second channel member 27 from the first channel member 25 to the opposite side thereof, and extends in the longitudinal direction of the head 3. The recess 27b has a planar shape larger than the actuator 21 by one turn, and is rectangular in the illustrated example with the longitudinal direction of the head 3 being the longitudinal direction.

The material of the second flow path member 27 and the like are arbitrary. For example, the second flow path member 27 may be composed of metal, resin, or ceramic, or a combination thereof.

(first flow passage Member)

Fig. 3 (b) is a top perspective view of the head 3. In this figure, the shape of the first flow path member 25 and the actuator 21 are shown. Fig. 4 is an enlarged view of area IV in fig. 3 (b).

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

The first flow path member 25 may have, in addition to the plurality of supply manifolds 33, the plurality of individual flow paths 35, and the plurality of recovery manifolds 37, flow paths that are located in the D2 direction and the D5 direction and that connect the supply reservoir 29 and the recovery reservoir 31, although not particularly shown. Such a flow path helps, for example, to homogenize the temperature of the first flow path member 25.

(manifold)

The supply manifold 33 has, for example, a main portion 33a (in the illustrated example, substantially all of the supply manifold 33 is equivalent) extending linearly in the direction D4 from the supply reservoir 29 side toward the recovery reservoir 31 side. The direction D4 is inclined with respect to the short side direction (direction D6) of the head 3. Similarly, the recovery manifold 37 has, for example, a main portion 37a (in the illustrated example, substantially all of the recovery manifold 37) extending linearly in the direction D1 from the recovery reservoir 31 side to the supply reservoir 29 side. The direction D1 is inclined with respect to the short side direction (direction D3) of the head 3. In the description of the embodiment, for convenience, the shapes, sizes, and the like of the supply manifold 33 and the recovery manifold 37 may be described with attention paid only to the main portions 33a and 37 a.

One end (end in the D1 direction) of the supply manifold 33 overlaps the supply reservoir 29 in a plan view. The one end communicates with the supply reservoir 29 via an opening 33b that opens on the surface of the first flow path member 25 on the second flow path member 27 side. The other end (end in the D4 direction) of the supply manifold 33 is terminated. Accordingly, the liquid in the supply reservoir 29 is supplied to the one end of the supply manifold 33 through the opening 33b, and flows in the direction (D4 direction) from the one end to the other end in the supply manifold 33.

One end (end in the direction D4) of the collection manifold 37 overlaps the collection reservoir 31 in a top perspective view. The one end communicates with the recovery receiver 31 via an opening 37b that opens on the surface of the first flow path member 25 on the second flow path member 27 side. The other end (end in the direction D1) of the recovery manifold 37 is terminated. Accordingly, the liquid in the recovery manifold 37 flows from the other end in the direction of the one end (direction D4), and is recovered to the recovery reservoir 31 via the opening 37 b.

The supply manifold 33 and the recovery manifold 37 have lengths extending over the entire length of the short side direction (D3 direction and D6 direction) of the arrangement region (the arrangement region of the actuator 21 here) of the plurality of nozzles (described later). The end (end in the direction D4) of the supply manifold 33 on the side of the recovery tank 31 is located, for example, on the side of the supply tank 29 than the recovery tank 31. Similarly, the end (end in the direction D1) of the recovery manifold 37 on the side of the supply reservoir 29 is located, for example, on the side of the recovery reservoir 31 than the supply reservoir 29.

The plurality of supply manifolds 33 have, for example, the same structure as each other, and are arranged at fixed intervals along the D2 direction. In other words, the plurality of supply manifolds 33 extend in parallel to each other by the same length. The connection positions (openings 33 b) of the plurality of supply manifolds 33 with respect to the supply reservoir 29 are arranged at fixed intervals along the supply reservoir 29.

Similarly, the plurality of recovery manifolds 37 have, for example, the same structure as each other, and are arranged at a fixed pitch along the D2 direction. In other words, the plurality of recovery manifolds 37 extend parallel to each other by the same length. The connection positions (openings 37 b) of the plurality of recovery manifolds 37 with respect to the recovery reservoir 31 are arranged at fixed intervals along the recovery reservoir 31.

The plurality of supply manifolds 33 and the plurality of recovery manifolds 37 are alternately arranged at a fixed pitch, for example. The supply manifold 33 and the recovery manifold 37 are adjacent to each other and extend parallel to each other. In more detail, most of the supply manifold 33 excluding the upstream side and most of the recovery manifold 37 excluding the downstream side are adjacent to each other in the arrangement region of the plurality of nozzles.

The cross-sectional shapes and dimensions of the supply manifold 33 and the recovery manifold 37 (for example, the main portions 33a and 37a thereof) may be fixed irrespective of the positions in the longitudinal direction of the flow paths, or may be different depending on the positions. In the description of the embodiment, the former is sometimes taken as an example. Further, the shape of the cross section may be a rectangular shape or the like as appropriate. The various dimensions of the supply manifold 33 and the recovery manifold 37 may be appropriately set according to the specific technical field in which the ejection device 1 is applied.

(separate flow paths)

The separate flow paths 35 are located, for example, substantially between and connected to the supply manifold 33 and the recovery manifold 37 adjacent to each other. The individual flow paths 35 are provided in plural for each set of manifolds (33 and 37). The plurality of individual channels 35 connected to the same manifold (33 and 37) are arranged along the manifold (along the direction D1) at a fixed pitch, for example, to constitute 1 column of channels. The plurality of individual channels 35 are arranged in a matrix by arranging a plurality of channel rows along the direction D2. Unlike the illustrated example, 2 or more rows of individual channels 35 may be provided between the supply manifold 33 and the recovery manifold 37 adjacent to each other.

Within one flow path row, the structures of the plurality of individual flow paths 35 are substantially identical. The plurality of flow channel rows are also substantially identical in structure. Here, for example, the orientations of the individual channels 35 may be different between adjacent channel rows (illustrated example). In addition, for example, the shapes and/or sizes of the individual flow paths 35 may be slightly different in one flow path row. Among the plurality of flow channel rows, the flow channel row located at the end in the D2 direction and the flow channel row located at the end in the D5 direction may have so-called dummy individual flow channels that do not eject liquid droplets.

The individual flow path 35 has a nozzle 43 that opens on the discharge surface 3a and discharges liquid droplets. A row in which the plurality of nozzles 43 are arranged along the direction D1 is referred to as a nozzle row. The arrangement direction (D1 direction) of the nozzles 43 in the nozzle row is inclined with respect to the direction (D3 direction) of the relative movement of the head 3 with respect to the object 101. The nozzles 43 belonging to the same nozzle row are different from each other in the D2 direction position by the inclination described above. Further, a part of the plurality of nozzle rows overlap each other as viewed from the D3 direction. In this overlapping portion, the positions of the nozzles 43 of one nozzle row and the nozzles 43 of the other nozzle row in the D2 direction are different from each other. When the plurality of nozzles 43 are projected in the D3 direction, the plurality of nozzles 43 are arranged at substantially fixed intervals in the D2 direction.

As a result, a plurality of dots arranged in the D2 direction at a pitch shorter than the distance between the nozzles 43 adjacent to each other in the head 3 can be formed on the surface of the object 101. For example, 32 nozzles 43 are projected in the range of the virtual straight line R, and the nozzles 43 are arranged at intervals of 360dpi in the virtual straight line R. Accordingly, when the object 101 and the head 3 are relatively moved in the direction orthogonal to the virtual straight line R to eject the liquid droplets, printing can be performed at a resolution of 360 dpi.

Fig. 5 is a perspective view of the individual flow paths 35. Fig. 6 (a) and 6 (b) are cross-sectional views of the first flow path member 25 and the actuator 21. Fig. 6 (a) corresponds to line VIa-VIa of fig. 5. Fig. 6 (b) corresponds to the VIb-VIb line of fig. 5.

The separate flow path 35 includes, for example, a supply flow path 39 (a first supply flow path 39A and a 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 opens to the discharge surface 3a and communicates with the outside of the first flow path member 25. The liquid in the supply manifold 33 is supplied to the nozzles 43 via the supply flow path 39 and the pressure chamber 41. Then, the actuator 21 applies pressure to the pressure chamber 41, so that droplets are ejected from the nozzles 43. The separate flow path 35 has a recovery flow path 45 connecting the pressure chamber 41 and the recovery manifold 37. The liquid remaining in the pressure chamber 41 without being ejected is recovered from the recovery flow path 45 to the recovery manifold 37.

The pressure chamber 41 has, for example, a pressure chamber body 41a to which pressure is applied by the actuator 21, and a descender (descender) 41b that connects the pressure chamber body 41a and the nozzle 43.

The pressure chamber body 41a is opened to the pressurizing surface 25a of the first flow path member 25, for example, and is closed by the actuator 21. Then, the actuator 21 is deflected upward and/or downward, thereby applying pressure to the liquid in the pressure chamber body 41 a. The descender 41b extends from the lower surface of the pressure chamber body 41a toward the discharge surface 3 a. The area of the cross section of the descender 41b is smaller than the area of the cross section parallel to the pressurizing surface 25a of the pressure chamber body 41 a.

The shape and size of the pressure chamber body 41a can be appropriately set. In the illustrated example, the pressure chamber body 41a has a circular planar shape. 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 diamond. The pressure chamber body 41a is formed in a thin shape having a thickness smaller than a diameter in plan view. In the illustrated example, the shape of the cross section parallel to the pressing surface 25a of the pressure chamber body 41a and the size thereof are fixed in the up-down direction. The shape of the cross section of the pressure chamber body 41a and/or the size thereof may be different depending on the position in the up-down direction.

The shape and size of the descender 41b may be appropriately set. In the illustrated example, the descender 41b has a straight columnar shape. In the illustrated example, the cross-section is circular in shape. Unlike the illustrated example, the descender 41b may be inclined with respect to the vertical direction, or may have a diameter that varies depending on the position in the vertical direction. The cross-sectional shape may be other than circular, such as elliptical.

The connection position of the descender 41b with respect to the pressure chamber body 41a in the plan view may be appropriately set. In the illustrated example, the descender 41b is connected adjacent to the outer edge of the circular pressure chamber body 41 a. Unlike the illustrated example, in the case where the pressure chamber body 41a has an elliptical or diamond shape, for example, the descender 41b may be connected to the longitudinal end of the pressure chamber body 41 a.

The nozzle 43 opens at a part of the bottom surface of the descender 41 b. The nozzle 43 may be opened at the center of the bottom surface of the descender 41b, or may be opened at a position distant from the center (in the illustrated example). The nozzle 43 has a longitudinal cross-sectional shape of a tapered shape having a diameter smaller as it is closer to the discharge surface 3 a. Wherein some or all of the nozzles 43 may be of an inverted cone shape. The cross-section of the nozzle 43 is circular, for example.

The supply passage 39 has, for example, a first supply passage 39A and a second supply passage 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 flow path 39, the connection position with respect to the supply manifold 33, the connection position with respect to the pressure chamber 41, the flow path shape, and the size may be appropriately set. In the illustrated example, this is as follows.

The first supply flow path 39A connects the supply manifold 33 with the pressure chamber main body 41 a. The first supply flow path 39A extends upward from the upper surface of the supply manifold 33, extends in the direction D5, extends in the direction D4, and extends upward again to be connected to the lower surface of the pressure chamber body 41 a. The cross-sectional shape of the first supply flow path 39A and its size are substantially fixed throughout a large part (for example, 6 or more) of the length of the first supply flow path 39A. The cross-section across the majority is rectangular in shape.

The second supply flow path 39B connects the supply manifold 33 with the descender 41B. The second supply flow path 39B extends from the lower surface of the supply manifold 33 in the direction D5 and extends in the direction D1, and is connected to the side surface of the descender 41B. The cross-sectional shape of the second supply flow path 39B and its size are substantially fixed throughout most of the length of the second supply flow path 39B (for example, 6 or more). The cross-section across the majority is rectangular in shape.

The recovery flow paths 45 are provided in only one single flow path 35, for example. Unlike the illustrated example, two or more recovery flow paths 45 may be provided. In the recovery flow path 45, the connection position with respect to the recovery manifold 37, the connection position with respect to the pressure chamber 41, the flow path shape, and the size may be appropriately set. In the illustrated example, this is as follows.

The recovery flow path 45 connects the recovery manifold 37 with the descender 41 b. The recovery flow path 45 extends from the side surface of the recovery manifold 37 in the direction D2 and extends in the direction D4, and is connected to the side surface of the descender 41 b. The cross-sectional shape of the recovery flow path 45 and its size are substantially fixed throughout a large part (for example, 6 or more) of the length of the recovery flow path 45. The cross-section across the majority is rectangular in shape.

As described above, the plurality of individual flow paths 35 connected to the same supply manifold 33 and the same recovery manifold 37 are arranged at a fixed pitch along the manifold. Therefore, the connection positions of the first supply flow path 39A and the supply manifold 33 are arranged at a fixed pitch along the supply manifold 33. The connection position of the second supply channel 39B and the supply manifold 33 and the connection position of the recovery channel 45 and the recovery manifold 37 are also the same.

As shown in fig. 6 (a) and 6 (b), the first flow path member 25 is formed by stacking a plurality of plates 47A to 47M. The various flow paths of the first flow path member 25 are constituted 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 fig. 6 b, baffles (reference numerals are omitted) are provided above and below the recovery manifold 37.

As described above, the pressure chamber 41 opens at the pressing surface 25 a. Unlike the illustrated example, a plate may be provided to block the pressure chamber 41. In this case, however, a problem can be considered that the plate that closes the pressure chamber 41 is understood as a part of the first flow path member 25 or as a part of the actuator 21. In the description of the present disclosure, the plate as described above is understood as part of the actuator 21.

(actuator)

As shown in fig. 2 (a), the actuator 21 is, for example, a substantially flat plate-shaped member, and is joined to the pressing surface 25a (more specifically, a region indicated by a broken line in fig. 2 (a)) of the first flow path member 25. Then, as shown in fig. 6 (a) and 6 (b), the actuator 21 closes the opening above the pressure chamber 41. The actuator 21 extends over substantially the entire arrangement area of the pressure chamber 41. The actuator 21 has a displacement element 49 in each pressure chamber 41.

The structure of the actuator 21 may be various known structures and applied to known structures. In the illustrated example, the actuator 21 is a so-called unimorph piezoelectric actuator. Specifically, the following is described.

The actuator 21 includes a diaphragm 51, a common electrode 53, a piezoelectric layer 55, and an individual electrode 57, which are laminated in this order from the pressure chamber 41 side. The diaphragm 51, the common electrode 53, and the piezoelectric layer 55 extend over substantially all of the arrangement area of the pressure chamber 41. 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 plan view, for example, and also overlaps the center side of the pressure chamber 41.

The portion of the piezoelectric layer 55 sandwiched by 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 expands in the direction along the surface. The contraction or expansion is restricted by the diaphragm 51, and the displacement element 49 is deflected toward the pressure chamber 41 side or the opposite side thereof as a bimetal. Thereby, pressure is applied to the liquid in the pressure chamber 41.

The material, thickness, and the like of each layer of the actuator 21 can be appropriately set. For example, the diaphragm 51 and the piezoelectric layer 55 may be made of lead zirconate titanate (PZT) or NaNbO ₃ Tie, baTiO ₃ Is (BiNa) NbO ₃ Is BiNaNb system ₅ O ₁₅ Ceramic materials such as aluminum alloy. The common electrode 53 and the individual electrode 57 may be made of a metal material such as ag—pd or Au.

The common electrode 53 is given a fixed potential (reference potential), for example. The individual electrodes 57 are input with the drive signals described above, for example. The driving method of the displacement element 49 (from another point of view, the waveform of the driving signal) can be appropriately performed. For example, the driving method may be a so-called traction method.

(liquid)

Fig. 7 is a diagram showing characteristics of the liquid used in the discharge device 1. In the figure, the horizontal axis represents the shear rate D (1/s). The vertical axis represents viscosity η (pa·s). EX1 and EX2 show characteristics of a first example and a second example of the liquid used in the ejection device 1.

As shown in the figure, the liquid used in the ejection device 1 is a pseudoplastic fluid. The pseudoplastic fluid is said to be a non-newtonian fluid having a higher shear rate and a lower viscosity, when the fluid is described in the above-mentioned manner. The shear rate is sometimes referred to as shear (velocity), velocity gradient, or strain rate. The shear rate can be calculated simply as a value obtained by dividing a difference in velocity between two positions separated from each other in a direction orthogonal to the flow direction by a distance between the two positions. The viscosity can be calculated, for example, simply as a value obtained by dividing the shear stress by the shear rate. Shear stress is sometimes referred to as shear stress. The shear stress is simply calculated as a value obtained by dividing a force, which is offset in the flow direction, of two surfaces (same area) parallel to each other, which are separated from each other in a direction orthogonal to the flow direction, by the area of one surface.

In addition, the pseudoplastic fluid can be said to have a viscosity η of η=k×d ^p-1 A power law fluid having a power exponent p less than 1 when approximated by a power law. Here, k is a viscosity coefficient, and D is a shear rate. Further, the viscosity η is a function of D, and is therefore sometimes referred to as apparent viscosity.

The liquid used in the ejection device 1 may or may not have thixotropic properties that decrease in viscosity as the time under shear stress increases.

The particular composition and/or makeup of the pseudoplastic fluid may be varied as is known. For example, inks and coatings are typically pseudoplastic fluids. The liquids of the first and second examples of the characteristics shown in fig. 7 are usual paints (in other words, commercially available paints). The specific properties of the pseudoplastic fluid may also be set appropriately. An example is as follows.

For example, the liquid may be set to a shear rate of 1000s ^-1 The viscosity is 0.02 Pa.s or more and 0.4 Pa.s or less. In the paint according to the first example of the characteristics shown in fig. 7, the shear rate was 1000s ^-1 The viscosity at the time was 0.3 Pa.s. In the coating material according to the second example, the shear rate was 1000s ^-1 The viscosity at the time was 0.1 Pa.s. The liquid can also be set to have a shear rate of 1000s ^-1 The viscosity is 0.1 Pa.s or more and 0.3 Pa.s or less.

In addition, for example, the liquid may be set to a shear rate of 0.01s ^-1 The viscosity is 0.5 Pa.s or more and 50 Pa.s or less. In the paint according to the first example of the characteristics shown in fig. 7, the shear rate was 0.01s ^-1 The viscosity at the time was 5 Pa.s. In the coating material according to the second example, the shear rate was 0.01s ^-1 The viscosity at the time was 30 Pa.s. The liquid can be set to have a shear rate of 0.01s ^-1 The viscosity is 5 Pa.s to 30 Pa.s.

Further, for example, when the viscosity is approximated by a power law, the viscosity coefficient k of the liquid 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 viscosity coefficient k is 1.0 and the exponent p is 0.65. In the paint according to the second example, the viscosity coefficient k is 1.5, and the exponent p is 0.35. The approximation can be determined, for example, by the least squares method.

(average viscosity)

Hereinafter, the concept of average viscosity is introduced. The viscosity is originally different for each micro-region in the flow path. However, the viscosity of each minute region is not necessarily suitable for setting the viscosity of the liquid in the flow path member 19, and calculation thereof is also accompanied by difficulty. Therefore, the viscosity averaged for each portion of the flow path member 19 is referred to as an average viscosity. The average viscosity is a value with respect to a portion in the flow path. For example, the average viscosity of 1 supply manifold 33 is the average viscosity of the entire 1 supply manifold 33.

The average viscosity can be calculated, for example, as follows. First, the relationship between the shear rate D and the viscosity η in the liquid used in the ejection device 1 is determined. In this determination, various known methods may be used, and the determination may be performed by referring to known documents. Next, an approximation formula showing the relationship between the determined shear rate D and the viscosity η is obtained. The approximation formula may be set to an appropriate mathematical formula such as a power law. The fitting method may be a known method such as a least square method. Next, the circulation flow rate U (m ³ S) is defined as a boundary condition, and fluid simulation is performed on each portion of the flow path using the above-described approximation formula, and a differential pressure Δp (Pa) between the upstream end and the downstream end of each portion is obtained. Then, the circulation flow rate U, the differential pressure Δp, and the size (m) of each part are substituted into a predetermined mathematical expression, and the average viscosity μ (pa·s) is calculated.

An example of the mathematical formula for calculating the average viscosity μ is shown below.

The mathematical expression in the case where the flow path shape is cylindrical in the axial direction of the flow direction is as follows.

U＝(πr ⁴ ΔP)/(8μL) (1)

Here, r is the radius of the cross section. L is the length of the flow path.

In addition, the following formula is used when the flow path is prismatic (rectangular parallelepiped) with the flow direction being the axial direction.

U＝(w ³ hΔP)/(4μL)

×(16/3-1024/π ⁵ ×w/h

×∑(1/q ⁵ ×tanh(qπh/2w)) (2)

Here, q=1, 3, 5, 7, 9, and 11, Σ is 6 when these 6 values are substituted into q (1/q ⁵ X tan h (qpi h/2 w)). w is the width of the flow path. h is the height of the flow path. L is the length of the flow path.

In the reservoirs (29 and 31) and the manifolds (33 and 37), the flow rate U differs between the upstream side and the downstream side. In this case, for example, any one of the most flow rate, the least flow rate, or the average flow rate may be used. The average viscosity described below is understood to be the average viscosity calculated using any of the above-described flow meters. In addition, in the case of comparing the average viscosities of the reservoirs (29 and 31) with the average viscosities of the manifolds (33 and 37), the average viscosities calculated under the same conditions as each other can be compared with each other. For example, the average viscosities calculated using the most flow meters (the lowest average viscosities) may be compared with each other, the average viscosities calculated using the least flow meters (the highest average viscosities) may be compared with each other, or the average viscosities calculated using the average flow meters (the average viscosities) may be compared with each other. For example, the average viscosity described below can be understood as the average viscosity (lowest average viscosity) calculated using the most flow meters. For example, the average viscosity of the supply reservoir 29 and the supply manifold 33 can be understood to be calculated using the most upstream flow rate. The average viscosity of the recovery receiver 31 and the recovery manifold 37 can be understood as the average viscosity calculated using the most downstream flow rate.

In the pressure chamber 41 or the pressure chamber body 41a or the descender 41b, the direction of the flow of the liquid is not limited to be fixed. The average viscosity of these portions in the following description is calculated from the upward direction to the downward direction as the flow direction. For example, the average viscosity of the descender 41b is calculated using the direction from the pressure chamber body 41a to the nozzle 43 as the flow direction.

(average viscosity of flow passage Member)

Fig. 8 is a diagram showing an example of the relative relationship between the parts with respect to the average viscosity μ of each part of the flow path in the flow path member 19. In the figure, the horizontal axis corresponds to a plurality of portions of the flow path member 19. The vertical axis represents the average viscosity μ of each portion.

In the figure, the average viscosity μ2 represents the average viscosity μ in 1 supply manifold 33 out of the plurality of supply manifolds 33. The average viscosity μ in 1 flow path is similarly represented for the other flow paths. The average viscosity μ3 of the supply flow path 39 can be understood as any average viscosity of the first supply flow path 39A and the second supply flow path 39B.

The liquid ejecting apparatus 1 sets the target flow rate of the circulation flow rate controlled by the flow rate setting unit 13 and the shape and size of the flow path member 19 so as to satisfy the relationship of the average viscosity as shown in the figure. In other words, the flow path of the flow path member 19 has a flow path shape in which the relationship shown in fig. 8 is established when the circulation flow rate is the target flow rate. In other words, the circulation flow rate is set to a value at which the relation of the average viscosity shown in fig. 8 is established in the shape and the size of the flow path member 19. For example, in the shape and size of the flow path member 19, the circulation flow rate is set to a value at which the average viscosity of the liquid in the supply flow path 39 becomes half or less of the average viscosity of the liquid in the supply manifold 33.

When the circulation flow rate is controlled in an open loop, the amount of fluctuation of the circulation flow due to the discharge amount of the liquid droplets from the plurality of nozzles 43 is large. In this case, the relationship shown in fig. 8 may be established in the circulation flow rate at the timing when the liquid droplets are not discharged from all the nozzles 43, for example. In other words, in the implemented product, the circulation flow rate at the timing when the liquid droplets are not ejected from all the nozzles 43 may be determined as the target flow rate in the product. The idea can also be applied to feedback control in which the follow-up property of the circulation flow rate to the target flow rate is low.

In fig. 8, the following relationship holds for example for the average viscosity.

The average viscosity μ3 of the liquid in the supply flow path 39 (39A or 39B) may be lower than the average viscosity μ2 of the liquid in the supply manifold 33. In more detail, for example, the average viscosity μ3 may be 1/2 or less, 1/3 or less, or 1/5 or less of the average viscosity μ2.

In this case, for example, since the average viscosity μ3 of the liquid in the supply passage 39 is low, the liquid can be smoothly supplied from the supply passage 39 to the pressure chamber 41. Further, since the average viscosity μ2 is high in the supply manifold 33, the pressure wave is easily attenuated. As a result, the possibility of propagation of the pressure wave leaking from the pressure chamber 41 to the supply manifold 33 via the supply flow path 39 to the other pressure chamber 41 via the other supply flow path 39 is reduced. That is, so-called fluid crosstalk can be reduced.

The same relationship as described above may be established 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 may be lower than the average viscosity μ6 of the liquid in the recovery manifold 37. In more detail, for example, the average viscosity μ 5 may be 1/2 or less, 1/3 or less, or 1/5 or less of the average viscosity μ 6. In this case, the same effects as those described above are also achieved.

The average viscosity μ2 of the supply manifold 33 may be lower than the average viscosity μ1 of the supply reservoir 29. In more detail, for example, the average viscosity μ2 may be 1/2 or less, 1/3 or less, or 1/4 or less of the average viscosity μ1.

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

The same relationship as described above may be established between the recovery manifold 37 and the recovery receiver 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. In more detail, for example, the average viscosity μ6 may be 1/2 or less, 1/3 or less, or 1/5 or less of the average viscosity μ7. In this case, the same effects as those described above are also achieved.

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

In this case, for example, if the viscosity is high, the resistance against movement of the air bubbles becomes high, and therefore the possibility that the air bubbles entering the descender 41b from the nozzle 43 can be recovered from the recovery flow path 45 becomes high.

The same relationship as described above may be established between the descender 41b and the supply passage 39. That is, the average viscosity μ4 of the descender 41b may be higher than the average viscosity μ3 of the supply flow path 39. In more detail, for example, the average viscosity μ4 may be 1.5 times or more or 2 times or more of the average viscosity μ3.

In this case, for example, since the average viscosity μ3 of the supply passage 39 is low, the liquid can be smoothly supplied to the descender 41 b. As a result, for example, the possibility of the liquid supply to the descender 41b becoming insufficient is reduced by the continuous discharge of the liquid.

The average viscosity μ2 of the supply manifold 33 may be higher than the average viscosity (μ3, μ4, and μ5) of the individual flow paths 35 (except for the pressure chamber body 41 a). More specifically, for example, the average viscosity μ2 may be 1.5 times or more as large as the average viscosities μ3, μ4, and μ5.

In this case, for example, since the average viscosity μ in the individual flow path 35 is low, the liquid can be smoothly supplied to the nozzle 43. Further, the average viscosity μ in the supply manifold 33 is high, whereby the pressure leaked from the individual flow path 35 to the supply manifold 33 is rapidly attenuated. Therefore, fluid crosstalk is less likely to occur.

The same relationship as described above may be established 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 may be higher than the average viscosity (μ3, μ4, and μ5) of each of the individual flow paths 35. More specifically, for example, the average viscosity μ6 may be 1.5 times or more the average viscosities μ3, μ4, and μ5. In this case, the same effects as those described above are also achieved.

(examples of values such as average viscosity)

There are numerous combinations of characteristics of the liquid, circulation flow rate, shape and size of the flow path, etc. that achieve the above-described relationship of the average viscosity μ, and the combinations may be appropriately set according to the specific technical field in which the ejection device 1 is applied. Hereinafter, an example of values in the case of using the general paint described with reference to fig. 7 will be shown.

The circulation flow rate may be, for example, 50ml/min or more and 300ml/min. The pressure in the nozzle 43 when the liquid is not ejected may be ±2kPa with respect to the atmospheric pressure (about 100 kPa). The differential pressure between the supply port 3b and the recovery port 3c may be 40kPa to 160 kPa.

In each of the supply reservoir 29 and the recovery reservoir 31, the width w may be 4mm or more and 20mm or less, the height h may be 3mm or more and 15mm or less, and the length L may be 200mm or more and 800mm or less. In each of the supply manifold 33 and the recovery manifold 37, the width w may be 0.2mm or more and 2mm or less, the height h may be 0.5mm or more and 6mm or less, and the length L may be 5mm or more and 20mm or less. In the first supply channel 39A, the width w and the height h may be 50 μm or more and 200 μm or less, respectively. 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 flow path 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 0.5mm or more and 2mm or less. In the nozzle 43, the radius r may be 5 μm or more and 50 μm or less.

An example of the estimation of the average viscosity μ under the above-described conditions is shown below. The descender 41b calculates the average viscosity μ by the expression (1), and calculates the average viscosity μ by the expression (2) for the other flow paths. The average viscosity μ of each of the supply reservoir 29 and the recovery reservoir 31 is 0.4pa·s or more and 2pa·s or less. The average viscosity μ of each of the supply manifold 33 and the recovery manifold 37 is 0.1pa·s or more and 0.4pa·s or less. The average viscosity μ of each of the supply channel 39 and the recovery channel 45 is 0.01pa·s or more and 0.1pa·s or less. The average viscosity μ in the downer 41b is 0.05pa·s or more and 0.2pa·s or less.

(fluid resistance)

The fluid resistance (n·s/m 5) in the flow path member 19 can be appropriately set. For example, the fluid resistance may be set to be satisfied in both of the following conditions 1 and 2.

Condition 1:

(1/2)×R _r XU (1+1/m) and (1/2) XR _m The sum of X (U/m) X (1+1/n) is less than 2σ/r.

Condition 2:

R _r ＜1/10×R _m ×(1/m)

here, R is _r Is the fluid resistance of the liquid in the supply reservoir 29. R is R _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) per supply manifold 33. U is the flow rate (m ³ /s). Sigma is the surface tension (N/m) of the liquid. r is the radius (m) of the nozzle 43.

Here, the supply manifold 33 to which only a dummy individual flow path incapable of ejecting liquid droplets is connected is omitted. Further, it is assumed that the same number of nozzles 43 as each other are connected to the supply manifold 33. Further, it is assumed that the pitch of the plurality of 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.

(1/2). Times.R in condition 1 _r The x U (1+1/m) corresponds to the pressure drop amount (upstream and downstream pressure difference) in the supply reservoir 29. Specifically, the pressure drop from the upstream end of the supply receiver 29 to the first supply manifold 33 is set to be u×r _r M, the pressure drop from the first supply manifold 33 to the second supply manifold is calculatedIs (U-U/m). Times.R _r And/m. Further, by the sum of the pressure drop amounts from the upstream end to the downstream end, that is, U X R _r /m+(U-U/m)×R _r /m+...+U/m×/R _r And/m to give the above (1/2). Times.R _r ×U(1+1/m)。

(1/2). Times.R in condition 1 _m X (U/m) × (1+1/n) corresponds to the pressure drop amount (upstream and downstream pressure difference) in 1 supply manifold 33. This equation is obtained in the same manner as the pressure drop in the supply reservoir 29 described above. That is, in the mathematical expression relating to the supply reservoir 29, the fluid resistance Rr of the supply reservoir 29 is replaced with the fluid resistance R of the supply manifold 33 _m The flow rate U flowing into the supply reservoir 29 is replaced with the flow rate U/m of the liquid flowing into the supply manifold 33, and the number m of the supply manifolds 33 is replaced with the number n of the nozzles 43.

(1/2). Times.R in condition 1 _r XU (1+1/m) and (1/2) XR _m The sum of x (U/m) × (1+1/n) corresponds approximately to the pressure difference between the most upstream individual flow path 35 and the most downstream individual flow path 35. The most upstream individual flow path 35 is the individual flow path 35 connected to the most upstream of the supply manifold 33 connected to the most upstream of the supply reservoir 29. The downstream-most individual flow path 35 is the downstream-most individual flow path 35 of the supply manifold 33 connected to the downstream-most supply reservoir 29. The pressure of the individual flow paths 35 drops to be substantially equal to each other in the plurality of individual flow paths 35, and thus the sum corresponds to the pressure difference between all the nozzles 43 (the pressure difference between the nozzle 43 having the highest pressure and the nozzle 43 having the lowest pressure).

Moreover, in the case where the sum is smaller than 2σ/r, the meniscus is easily maintained at the atmospheric pressure in all of the nozzles 43. In addition, as already described, regarding condition 1, the supply manifold 33 to which only the dummy individual flow path is connected and the dummy individual flow path can be omitted. In addition, in the most upstream supply manifold 33, the most downstream supply manifold 33, or the like, the number of individual channels 35 connected may be smaller than that of the other supply manifolds 33. In this case, for example, the most upstream supply manifold 33 or the most downstream supply manifold 33 may be omitted, and conversely, it may be assumed that the same number of individual flow paths 35 as the other supply manifolds 33 are connected to the most upstream supply manifold 33 or the most downstream supply manifold 33.

Condition 2 indicates the fluid resistance R of the supply reservoir 29 _r Fluid resistance R with supply manifold 33 _m Is a size relationship of (a). 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 flow resistance R is set to _m Multiplied by 1/m, against the fluid resistance R _r And fluid resistance R _m A comparison is made. Moreover, the satisfaction of condition 2 means that the fluid resistance R supplied to the reservoir 29 _r In fluid resistance R with the supply manifold 33 _m Is extremely small.

For example, in the prior art, R _r Is R _m About 1/5 of X (1/m). On the other hand, in the present embodiment, R _r Can be set as R _m X (1/m) is 1/40 or more and less than 1/10. Of course, in the present embodiment, as in the prior art, R is also _r May also be set as R _m About 1/5 of X (1/m).

By satisfying the condition 2, for example, the liquid easily flows from the supply reservoir 29 to the positions of the plurality of supply manifolds 33, and the difference in flow rates between the plurality of supply manifolds 33 is alleviated. Further, the liquid can be stably supplied to all the supply manifolds 33.

In addition to the conditions 1 and 2, the fluid resistance may be set so that the following condition 3 is satisfied.

Condition 3:

R _m ＜1/10×R _n ×(1/n)

here, R is _n Is the fluid resistance in the nozzle 43.

Condition 3 indicates the fluid resistance R of the supply manifold 33 _m The magnitude of the fluid resistance of the individual flow path 35. Wherein the fluid resistance R of the nozzle 43 _n Much greater than the other parts of the individual flow paths 35, and therefore the flow resistance R through the nozzle 43 _n To approximate the fluid resistance of the individual flow paths 35. Further, 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 will be set _n Multiplying by 1/n to obtain the fluid resistance R _m And fluid resistance R _n A comparison is made.

Condition 3 is satisfied, which means that the fluid resistance R is supplied to the manifold 33 _m In fluid resistance R with nozzle 43 _n Is extremely small. For example, in the prior art, R _m Is R _n About 1/6 of X (1/n). In the present embodiment, R is also the same as in the prior art _m May also be set as R _n About 1/6 of X (1/n). For example, R _m Can be R _n X (1/n) is 1/10 or more and 1/4 or less.

By satisfying the condition 3, for example, the liquid easily flows from the supply manifold 33 to the positions of the plurality of individual flow paths 35, and the difference in flow rates between the plurality of individual flow paths 35 is alleviated. Further, the liquid can be stably supplied to all the individual channels 35.

As an example of the size of the flow path, which is exemplified as an example of the size of the average viscosity shown in fig. 8, an example of the size of the flow path satisfying the conditions 1 to 3 can be referred to.

(modification)

Fig. 9 is a schematic cross-sectional view of the individual flow paths 235 according to a modification.

The pressure chamber 241 of the separate flow path 235 has a pressure chamber body 241a and a descender 241b, as in the pressure chamber 41 of the embodiment. The descender 241b has a first portion 241ba and a second portion 241bb having different cross-sectional areas.

The first portion 241ba is connected to the nozzle 43. The second portion 241bb is connected to the pressure chamber main body 241 a. In other words, the second portion 241bb is located closer to the pressure chamber body 241a than the first portion 241 ba. Further, the second portion 241bb has a cross-sectional area wider than the first portion 241 ba.

Since the cross-sectional areas of the first portion 241ba and the second portion 241bb are different from each other, the average viscosities are different from each other. For example, the average viscosity of the liquid in the second portion 241bb is higher than the average viscosity of the liquid in the first portion 241 ba. In other words, the average viscosity in the descender 241b increases stepwise as approaching the pressure chamber body 41a from the nozzle 43. The increase in average viscosity may be increased not only in 1 stage but also in 2 stages or more. In other words, the descender may have a third portion or the like in addition to the first portion and the second portion.

When the average viscosity of the second portion 241bb located closer to the pressure chamber body 241a than the first portion 241ba is higher than the average viscosity of the first portion 241ba as in the present modification, for example, the bubbles entering the descender 241b from the nozzle 43 are less likely to move toward the pressure chamber body 241 a. Further, the bubbles may remain in the pressure chamber body 241a, and the ejection characteristics may be lowered.

In addition, when at least one of the two flow paths having the average viscosity is compared, and there is a portion having a different shape, the average viscosities of the portions where the 2 flow paths are in contact with each other may be compared with each other. For example, in the individual flow paths 235 according to the modification, when the average viscosity of the recovery flow path 45 is compared with the average viscosity of the downer 241b, the average viscosity of the second portion 241bb directly connected to the recovery flow path 45 may be used for comparison instead of the average viscosity of the downer 241b as a whole. The average viscosity of the second portion 241bb greatly affects the flow between the recovery flow path 45 and the descender 241 b.

The technology according to the present disclosure is not limited to the above embodiments and modifications, and may be implemented in various ways.

For example, the liquid ejecting apparatus is not limited to a piezoelectric apparatus that applies pressure to a liquid by a piezoelectric body. The liquid ejecting apparatus may be a heat-sensitive apparatus that generates bubbles in a liquid by heat and applies pressure to the liquid in accordance with the generation of the bubbles to eject liquid droplets.

The structure of the flow path may be various other than those shown in the drawings. For example, individual flow paths adjacent to each other may be partially shared. For example, a part of the recovery flow path on the recovery manifold side may be shared between the separate flow paths adjacent to each other.

The average viscosity may be set other than the embodiment. For example, the average viscosity μ3 of the supply flow path 39 may be larger than the average viscosity μ5 of the recovery flow path 45 or larger than 1.5 times thereof, contrary to the embodiment. In this case, at the time of droplet ejection, the liquid in the descender 41b is less likely to flow back (is less likely to flow in a direction opposite to the circulation direction). In addition, the liquid and/or the bubbles easily flow in the recovery flow path.

Claims

1. A liquid ejecting apparatus includes:

a flow path member having a flow path through which a pseudoplastic liquid flows;

an actuator that applies pressure to the liquid in the flow path to eject liquid droplets from the flow path member; and

a flow rate setting unit that sets a flow rate of the liquid in the flow path,

the flow path has:

a supply reservoir to which the liquid is supplied;

a plurality of supply manifolds connected to the supply reservoir and supplied with the liquid from the supply reservoir;

a plurality of supply channels provided in a number of 2 or more with respect to each of the plurality of supply manifolds, each of the plurality of supply channels being connected to any one of the plurality of supply manifolds, and the liquid being supplied from the connected supply manifold;

A plurality of pressure chambers connected to the plurality of supply channels, respectively, and supplied with the liquid from the plurality of supply channels and applied with pressure by the actuator;

a plurality of nozzles connected to the plurality of pressure chambers, respectively, and ejecting the liquid from the pressure chambers to the outside;

a plurality of recovery flow paths connected to the plurality of pressure chambers, respectively, for recovering the liquid from the plurality of pressure chambers;

a plurality of recovery manifolds connected to any two or more of the plurality of recovery flow paths, respectively, for recovering the liquid from the plurality of recovery flow paths; and

a recovery reservoir connected to the plurality of recovery manifolds, recovering the liquid from the plurality of recovery manifolds,

the flow rate setting unit adjusts the circulation flow rate of the liquid circulating in 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 in this order to a predetermined target flow rate,

the flow path has a flow path shape in which an average viscosity of the liquid in the supply flow path is half or less of an average viscosity of the liquid in the supply manifold when the circulation flow rate is the target flow rate.

2. The liquid ejection device according to claim 1, wherein,

the flow path has a flow path shape in which an average viscosity of the liquid in the supply manifold is half or less of an average viscosity of the liquid in the supply reservoir when the circulation flow rate is the target flow rate.

3. The liquid ejection device according to claim 1 or 2, wherein,

the pressure chamber has:

a pressure chamber body to which pressure is applied by the actuator; and

a descender connecting the pressure chamber body and the nozzle,

the recovery flow path is connected with the descender,

the flow path has a flow path shape in which the average viscosity of the liquid in the downer is 1.5 times or more the average viscosity of the liquid in the recovery flow path when the circulation flow rate is the target flow rate.

4. The liquid ejection device according to any one of claims 1 to 3, wherein,

the pressure chamber has:

a pressure chamber body to which pressure is applied by the actuator; and

a descender connecting the pressure chamber body and the nozzle,

the recovery flow path is connected with the descender,

the descender has:

a first portion; and

A second portion located closer to the pressure chamber body than the first portion,

the flow path has a flow path shape in which the average viscosity of the liquid at the second portion is higher than the average viscosity of the liquid at the first portion when the circulation flow rate is the target flow rate.

5. The liquid ejection device according to any one of claims 1 to 4, wherein,

setting the fluid resistance of the liquid in the supply reservoir to R _r ，

Setting the fluid resistance of the liquid in the supply manifold to R _m ，

Setting the number of the supply manifolds connected with the supply reservoir as m,

the number of said nozzles per said supply manifold is set to n,

the flow rate of the liquid flowing into the supply reservoir is set to U,

the surface tension of the liquid is set to sigma,

the radius of the nozzle is set to r, at which point,

(1/2)×R _r XU (1+1/m) and (1/2). Times.R _m The sum of X (U/m) X (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,

in setting the fluid resistance of the liquid in the nozzle as R _n In the time-course of which the first and second contact surfaces,

R _m ＜1/10×R _n ×(1/n)。

7. a liquid ejection method using the liquid ejection device according to any one of claims 1 to 6, wherein,

Using a shear rate of 1000s ^-1 The viscosity is 0.02 Pa.s or more and 0.4 Pa.s or less, and the shear rate is 0.01s ^-1 A pseudoplastic fluid having a viscosity of 0.5pa·s or more and 50pa·s or less is used as the liquid.