Syringe unit and discharge device

Abstract

To provide a syringe unit which can discharge air in a syringe in a more reliable manner.SOLUTION: A syringe unit 10 includes: a cylindrical syringe 20 having a discharge port 21 at a tip part and having an opening 22 at a base end part; a plunger 30 which is inserted into the syringe 20 from the opening 22 and may slide in an axial direction of the syringe 20; and a shaft member 40 which includes a rod-like shaft part 42 extending in the axial direction of the syringe 20, inserted into the opening 22 side relative to the plunger 30 in the syringe 20, and may slide in the axial direction of the syringe 20. The plunger 30 and the shaft member 40 are formed with passages 34, 43 which allow a space S1 at the discharge port 21 side relative to the plunger 30 and the outside S2 to communicate with each other. The syringe unit 10 further includes a ventilation member 50 which is provided so as to close the passages 34, 43, allows a gas to pass, and blocks a liquid.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a syringe unit and a discharge device equipped with the syringe unit. [Background technology]

[0002] Syringe units that discharge a stored fluid and discharge devices equipped with syringe units have been known for some time. For example, Patent Document 1 discloses a liquid discharge device that includes a syringe filled with a liquid, a plunger inserted into the syringe, a piston that presses the plunger, and an electric actuator that drives the piston. The plunger described in Patent Document 1 has a through-hole that penetrates it in the axial direction. A filter that allows gas to pass but not liquid to pass through is provided midway through the through-hole. According to Patent Document 1, when the plunger is inserted into the syringe, air inside the syringe is discharged through the through-hole. This is said to reduce the complexity of purging air from the syringe. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-221419 Summary of the Invention [Problem to be solved by the invention]

[0004] In the discharge device described in Patent Document 1, the through-hole of the plunger is blocked by the tip of the piston when the piston pushes the plunger to discharge liquid. Therefore, in the discharge device described in Patent Document 1, air cannot be removed from the syringe when the piston pushes the plunger. Therefore, if the air in the cylinder is not sufficiently removed when the plunger is inserted into the syringe, air will remain in the syringe during the discharge of liquid. Because air is a compressible fluid, if air remains in the syringe, there is a risk that the correct amount of liquid will not be discharged.

[0005] The present invention has been made in view of the above points, and its object is to provide a syringe unit that can more reliably discharge air from the syringe and stably discharge a fluid to be discharged, and also to provide a discharge device equipped with such a syringe unit. [Means for solving the problem]

[0006] The syringe unit disclosed herein includes a cylindrical syringe having a discharge port at its tip end and an opening at its base end, a plunger inserted into the syringe through the opening and slidable in the axial direction of the syringe, and a shaft member having a rod-shaped shaft extending in the axial direction of the syringe, inserted into the syringe closer to the opening than the plunger and slidable in the axial direction of the syringe. The plunger and the shaft member have a flow path formed therein that connects a space closer to the discharge port than the plunger with the outside. The syringe unit further includes a vent member that closes the flow path and allows gas to pass through but blocks liquid.

[0007] According to the syringe unit, the flow path formed in the plunger and the shaft member connects the space on the discharge port side of the plunger to the outside. The syringe unit includes a ventilation member that closes the flow path and allows gas to pass through but blocks liquid. Therefore, even when the plunger is pressed with the shaft member, air inside the syringe on the discharge port side of the plunger can be discharged to the outside via the ventilation member without being obstructed by the shaft member. Meanwhile, the ventilation member prevents leakage of the fluid inside the syringe, which is the object to be discharged. This ensures that the air inside the syringe is discharged reliably, allowing the fluid to be stably discharged. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view illustrating a discharge device according to an embodiment. [Figure 2] FIG. 2 is a front view showing the configuration near the syringe unit. [Figure 3] FIG. 2 is a cross-sectional view of the syringe unit. [Figure 4] FIG. 2 is a plan view of the plunger as viewed from the base end side. [Figure 5] FIG. 10 is a plan view of the contact portion as seen from the tip end side. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be noted that the embodiments described here are not intended to limit the present invention in any particular way. Furthermore, the same reference numerals are used to designate components and parts that perform the same functions, and redundant descriptions will be omitted or simplified as appropriate.

[0010] [Configuration of fluid ejection device] FIG. 1 is a perspective view of an incompressible fluid ejection device 100 (hereinafter referred to as the fluid ejection device 100) according to one embodiment. In the following description, left, right, top, and bottom refer to the left, right, top, and bottom directions, respectively, as viewed by a user standing in front of the fluid ejection device 100. The side of the user approaching the fluid ejection device 100 is referred to as the rear, and the side of the user moving away from the fluid ejection device 100 is referred to as the front. The symbols F, Rr, L, R, U, and D in the drawings represent the front, rear, left, right, top, and bottom, respectively. The fluid ejection device 100 according to this embodiment is placed on a plane defined by the X-axis and Y-axis, where the X-axis, Y-axis, and Z-axis are mutually orthogonal axes. Here, the X-axis extends in the left-right direction. The Y-axis extends in the front-back direction. The plane defined by the X-axis and Y-axis is a horizontal plane. The Z-axis extends in the up-down direction. However, these directions are merely for the convenience of explanation and do not limit the installation mode of the fluid ejection device 100 in any way.

[0011] The fluid discharge device 100 is a device that discharges a non-compressible fluid stored in a syringe unit 10 onto an object to be decorated 5 placed on a table 120. Below, the syringe unit 10 will be described while explaining the fluid discharge device 100.

[0012] The incompressible fluid contained in the syringe unit 10 includes Newtonian fluids and non-Newtonian fluids. Non-Newtonian fluids are a general term for fluids that do not fall under the Newtonian category and refer to fluids with viscosity in which the relationship between the shear stress (tangential stress) of the flow and the velocity gradient (shear rate) of the flow is not linear. Examples of non-Newtonian fluids include pseudoplastic fluids. When the incompressible fluid is a pseudoplastic fluid, its viscosity decreases when a force is applied, and it maintains a high viscosity until a force is applied. This is preferable because applying a pressing force, for example, from the plunger 30 (see FIG. 2 ) described below, improves the supplyability (fluidity) of the incompressible fluid when the incompressible fluid is supplied from the syringe unit 10. Here, the incompressible fluid refers to a fluid with a Mach number of less than 0.3 (i.e., a density change of less than 5%) and a fluid with such small volume change that the effects of compression and expansion are negligible. A compressible fluid is a fluid with a Mach number of 0.3 or greater (i.e., a density change of 5% or greater), and is a fluid (such as air) that experiences large volume changes due to compression or expansion.

[0013] Depending on the application, the incompressible fluid may satisfy safety standards for human consumption (including infants and young children) by limiting the content and elution amount of heavy metals in accordance with the Food Sanitation Act, the European Toy Directive, the ST (Safety Toy) standard, etc. Furthermore, the incompressible fluid may be composed of, for example, an edible material (food). The incompressible fluid may be placed on a substrate and decorate the substrate, either without hardening or after hardening. In this case, the substrate may be a food or a non-food material. Examples of food include condiments such as mayonnaise, meat pastes made from animals, fish, and their internal organs, various vegetable pastes, confectionery foods such as chocolate, fresh cream, and mousse.

[0014] The non-compressible fluid may also have a curing mechanism that hardens after being supplied to a substrate. For example, the curing mechanism of the non-compressible fluid may be any of a solvent evaporation type (which may be a dry curing type) that hardens by volatilizing a solvent or dispersion medium, a moisture curing type that hardens by reacting with moisture in the atmosphere, a heat curing type that hardens by activating a curing agent in the non-compressible fluid when heated, an energy ray curing type that hardens in a short time by irradiating with energy rays such as ultraviolet rays, and a heat melting type that hardens when supplied in a heated and molten state and cooled. The non-compressible fluid may also decorate a substrate by being placed on the substrate without hardening.

[0015] The viscosity of the incompressible fluid is not particularly limited. The viscosity of the incompressible fluid ejected using syringe unit 10 can range over a wide range, for example, from 10 mPa·s to 5 Pa·s at 25°C and a shear rate of 1000 mPa·s. To achieve smoother ejection, for example, depending on the shape of syringe unit 10, the viscosity of the incompressible fluid at 25°C and 1000 mPa·s is preferably 2 Pa·s or less, for example, 1 Pa·s or less, and more preferably 500 mPa·s or less. However, if the viscosity at 1000 mPa·s is too low, the ejected incompressible fluid will have too low a viscosity, which can cause sagging, and is therefore undesirable. The lower limit of the viscosity at 1000 mPa·s is not limited to this, but a preferred example is 80 mPa·s.

[0016] Hereinafter, the incompressible fluid to be ejected will be referred to as the "ejection material." In this embodiment, the ejection material contains particles. Here, the ejection material is a sol (colloid) in which particles, which are dispersoids, are dispersed in a liquid dispersion medium.

[0017] There is no particular limitation on the object to be decorated 5. For the sake of convenience, it will be referred to as the "object to be decorated," but the object to be decorated 5 is an object onto which the ejected material is ejected, and the application of the ejected material to be added is not limited to decorative purposes.

[0018] As shown in Fig. 1, the fluid ejection device 100 is formed in a box shape. The fluid ejection device 100 includes a housing 110 that is open at the front and top, a table 120 that is formed so that an object to be decorated 5 can be placed thereon, a syringe unit 10 that ejects a non-compressible fluid, a syringe moving device 130 that holds the syringe unit 10 and moves it in the X-axis, Y-axis, and Z-axis directions, and a pressing device 180 that presses a piston 40 (described below, see Fig. 2) of the syringe unit 10 to eject the ejection material. An openable cover is provided at the opening of the housing 110, but is not shown here.

[0019] 1, syringe moving device 130 is provided in the internal space of housing 110. Syringe moving device 130 includes syringe holder 140 that holds syringe unit 10, Z-axis direction moving mechanism 150 that moves syringe holder 140 in the Z-axis direction, X-axis direction moving mechanism 160 that moves syringe holder 140 in the X-axis direction, and Y-axis direction moving mechanism 170 that moves syringe holder 140 in the Y-axis direction.

[0020] 1, syringe holder 140 has a pair of arms 141 that form a roughly C-shape with an open front. Syringe holder 140 holds syringe unit 10 between pair of arms 141. More specifically, syringe holder 140 holds syringe 20 (see FIG. 2), which will be described later, of syringe unit 10.

[0021] FIG. 2 is a front view showing the configuration near syringe unit 10. As shown in FIG. 2, Z-axis direction movement mechanism 150 includes first carriage 151 on which syringe holder 140 is provided, a pair of Z-axis shafts 152 with which first carriage 151 is engaged so as to be slidable in the Z-axis direction, Z-axis motor 153, and a ball screw (not shown). The pair of Z-axis shafts 152 extend in the Z-axis direction. The ball screw is engaged with a screw provided on first carriage 151. Z-axis motor 153 rotates the ball screw. When Z-axis motor 153 is driven, first carriage 151 moves in the Z-axis direction along the pair of Z-axis shafts 152 due to the rotation of the ball screw.

[0022] The X-axis movement mechanism 160 moves the Z-axis movement mechanism 150 in the X-axis direction. As shown in FIG. 1 , the X-axis movement mechanism 160 includes a second carriage 161 on which the Z-axis movement mechanism 150 is mounted, a pair of X-axis shafts 162 with which the second carriage 161 is engaged so as to be slidable in the X-axis direction, left and right pulleys 163, a wire 164 wound around the left and right pulleys 163, and an X-axis motor 165. The pair of X-axis shafts 162 extend in the X-axis direction. The wire 164 is fixed to the second carriage 161. The wire 164 may be, for example, a belt. The X-axis motor 165 rotates one of the pulleys 163. When the X-axis motor 165 is driven, the second carriage 161 moves in the X-axis direction along the pair of X-axis shafts 162 as the wire 164 travels.

[0023] The Y-axis movement mechanism 170 moves the X-axis movement mechanism 160 in the Y-axis direction. The Y-axis movement mechanism 170 includes a third carriage 171 on which the X-axis movement mechanism 160 is mounted, a left Y-axis shaft 172L with which the third carriage 171 is slidably engaged in the Y-axis direction, and a right Y-axis shaft 172R with which the third carriage 171 is slidably engaged in the Y-axis direction. The left Y-axis shaft 172L extends in the Y-axis direction. The third carriage 171 includes a left sliding member 171L through which the left Y-axis shaft 172L is inserted. The Y-axis movement mechanism 170 includes a pair of front and rear left pulleys 173L, a left wire 174L wound around the pair of left pulleys 173L, and a Y-axis motor 175. The left wire 174L is fixed to the left sliding member 171L.

[0024] The right Y-axis shaft 172R extends in the Y-axis direction. The third carriage 171 includes a right sliding member 171R through which the right Y-axis shaft 172R is inserted. The Y-axis direction movement mechanism 170 includes a pair of front and rear right pulleys 173R and a right wire 174R wound around the pair of right pulleys 173R. The right wire 174R is fixed to the right sliding member 171R. The Y-axis motor 175 rotates one of the left pulleys 173L and one of the right pulleys 173R. When the Y-axis motor 175 is driven, the third carriage 171 moves in the Y-axis direction along the Y-axis shafts 172L and 172R due to the movement of the wires 174L and 174R.

[0025] However, the configuration of the syringe moving device 130 is not limited to the above. The syringe moving device 130 may be configured, for example, to move the syringe unit 10 in only some of the X-axis, Y-axis, and Z-axis directions, and to move the table 120 in some of the other directions. Furthermore, the syringe moving device 130 is not limited to a device that moves the syringe holder 140 using a ball screw or a wire. The syringe moving device 130 may be configured, for example, to move the syringe holder 140 using a rack-and-pinion mechanism.

[0026] The pressing device 180 is provided on the first carriage 151. The pressing device 180 moves in the Z-axis direction together with the first carriage 151. As shown in FIG. 2 , the pressing device 180 includes a pair of slide shafts 181, a pair of ball screws 182, a drive motor 183, a slider 184, and a connecting shaft 185. The slide shaft 181 and the ball screw 182 extend in the Z-axis direction. The drive motor 183 is connected to the ball screw 182 and rotates the ball screw 182. The ball screw 182 is engaged with a screw provided on the slider 184. The slider 184 is slidably engaged with the pair of slide shafts 181. The connecting shaft 185 is provided at the bottom of the slider 184. The connecting shaft 185 extends downward from the slider 184. The lower end of the connecting shaft 185 is connected to the piston 40 of the syringe unit 10.

[0027] The pressing device 180 moves the piston 40 in the Z-axis direction (which will be described later, is the axial direction of the syringe 20). When the drive motor 183 is driven, the slider 184 moves in the Z-axis direction along the slide shaft 181 due to the rotation of the ball screw 182. The movement of the slider 184 in the Z-axis direction causes the piston 40 to move in the Z-axis direction relative to the syringe 20. The drive motor 183 is configured so that its rotation angle can be controlled. The drive motor 183 is, for example, a servo motor. The pressing device 180 controls the rotation angle of the drive motor 183 to control the amount of movement of the piston 40 in the Z-axis direction.

[0028] [Syringe unit configuration] FIG. 3 is a cross-sectional view of the syringe unit 10. As shown in FIG. 3, the syringe unit 10 includes a syringe 20, a plunger 30, a piston 40, and a hydrophobic filter 50. The syringe 20 is configured in a cylindrical shape. Here, the syringe 20 is configured in a cylindrical shape. However, the syringe 20 may be configured in a polygonal cylindrical shape, for example. The syringe 20 contains the discharge material 1 inside. As shown in FIG. 3, the syringe 20 has a discharge port 21 at the tip end and an opening 22 at the base end. In this embodiment, the tip end is the lower end of the syringe 20. The base end is the upper end of the syringe 20. Hereinafter, the upper side may be referred to as the base end side, and the lower side may be referred to as the tip end side.

[0029] As shown in FIG. 3, the opening 22 has the same diameter as the inner diameter of the cylindrical portion 23 of the syringe 20. The base end of the syringe 20 is fully open. The extrusion material 1 is injected into the syringe 20 from the opening 22. The lower end of the cylindrical portion 23 forms an inclined portion 23a that slopes downward toward the center in the radial direction. The discharge port 21 extends downward from the bottom of the inclined portion 23a. The extrusion material 1 in the syringe 20 is discharged from the discharge port 21. The diameter of the discharge port 21 is smaller than the diameter of the cylindrical portion 23. Hereinafter, the central axis of the syringe 20 is represented by the symbol C1. As shown in FIG. 3, the central axes of the plunger 30 and the piston 40 coincide with the central axis C1 of the syringe 20.

[0030] The plunger 30 is configured to be insertable into the syringe 20 from the opening 22 and to be slidable in the axial direction of the syringe 20. The plunger 30 is inserted into the syringe 20 from the opening 22. In this embodiment, the axial direction of the syringe 20 is the Z-axis direction. Here, the plunger 30 is configured as a cylinder with a bottom having a diameter slightly larger than the inner diameter of the cylindrical portion 23 of the syringe 20. The plunger 30 is formed from an elastic material, such as rubber. The plunger 30 includes a cylindrical portion 31 that forms the outer circumferential surface, a bottom portion 32 connected to the lower end of the cylindrical portion 31, and a step portion 33 that receives the pressing force of the piston 40.

[0031] The cylindrical portion 31 has a diameter slightly larger than the inner diameter of the tubular portion 23 of the syringe 20. The plunger 30 is inserted into the syringe 20 while collapsing the cylindrical portion 31. The collapse of the cylindrical portion 31 seals the gap between the plunger 30 and the syringe 20. A step 33 having a smaller diameter than the inlet of the cylindrical portion 31 is provided inside the cylindrical portion 31. The tip of the piston 40 is inserted into the cylindrical portion 31 of the plunger 30 and abuts against the step 33. The bottom 32 of the plunger 30 is conically configured and convex downward. The shape of the bottom 32 corresponds to the shape of the inclined portion 23a of the syringe 20. However, the shapes of the inclined portion 23a of the syringe 20 and the bottom 32 of the plunger 30 are not limited to conical shapes and may be, for example, flat. In the following description, the space inside the syringe 20 that is closer to the discharge port 21 than the plunger 30 (here, below) will also be referred to as a space S1 below the plunger 30.

[0032] FIG. 4 is a plan view of the plunger 30 as viewed from the base end side. As shown in FIG. 4, the plunger 30 has a plurality of through holes 34 formed therein, penetrating in the axial direction of the syringe 20. The plurality of through holes 34 penetrate the bottom 32 of the plunger 30. In this embodiment, the through holes 34 are configured to have a circular cross section. However, the through holes 34 may have a cross section other than a circle, for example, an elliptical or rectangular cross section. Here, the phrase "the through holes 34 penetrate the plunger 30 in the axial direction of the syringe 20" broadly means that the through holes 34 communicate between the base end side and the tip end side of the plunger 30. This includes not only cases where the axial direction of the through holes 34 coincides with the axial direction of the syringe 20, but also cases where, for example, the axial direction of the through holes 34 is oblique to the axial direction of the syringe 20. In this embodiment, the axial direction of the plurality of through holes 34 coincides with the axial direction of the syringe 20. Furthermore, the flow path that penetrates the syringe 20 in the axial direction does not have to be a closed through-hole, and may be, for example, a notch that cuts through to the outer circumferential surface of the plunger 30.

[0033] The multiple through holes 34 are arranged, when viewed in the axial direction of the syringe 20, so as to avoid the shaft portion 42 and protrusion portion 41c of the piston 40, which will be described later (see FIGS. 3 and 5). Here, the multiple through holes 34 are arranged at positions offset from the periphery of the central axis C1 of the plunger 30. In this embodiment, the number of through holes 34 is four. Here, the four through holes 34 are arranged at 90-degree intervals on a circle set at a position close to the outer edge of the bottom portion 32. However, the arrangement of the multiple through holes 34 is not particularly limited. The multiple through holes 34 may be arranged, for example, in a matrix pattern. Furthermore, the number of through holes 34 is not limited. The number of through holes 34 may be one, two, or three, or may be five or more.

[0034] The shortest width of the flow path of the plunger 30, exemplified by the through hole 34, is preferably set to be longer than the longest width of the primary particles 2 contained in the discharge material 1 housed in the syringe 20 and discharged from the discharge port 21. Here, the smallest constituent unit of particles contained in the discharge material 1 is defined as the primary particle 2. The "longest width" of the primary particle 2 refers to the longest distance between two opposing ends of the primary particle 2. When the primary particle 2 is spherical, the "longest width" of the primary particle 2 refers to the diameter of the primary particle 2. In this embodiment, the through hole 34 has a circular cross section, and the "shortest width" of the through hole 34 refers to the diameter of the through hole 34. The diameter of the primary particles 2 contained in the discharge material 1 is typically on the order of several nanometers to several micrometers. The diameter of the through hole 34 is, for example, 0.2 mm or more. The diameter of the through hole 34 may be larger. When the cross section of the through hole 34 is non-circular, the "shortest width" of the through hole 34 refers to the distance between the two closest points on the cross section of the through hole 34.

[0035] The piston 40 transmits the driving force of the pressing device 180 to the plunger 30, causing the plunger 30 to slide within the syringe 20. As shown in FIG. 3 , the piston 40 is inserted into the syringe 20 closer to the opening 22 than the plunger 30. The piston 40 is configured to be slidable in the axial direction of the syringe 20. The piston 40 is configured in a rod shape extending in the axial direction of the syringe 20 and abuts against the base end of the plunger 30. More specifically, the tip end of the piston 40 is fitted into the inner space of the cylindrical portion 31 and the step portion 33 of the plunger 30 and is fixed to the plunger 30 by the elastic force of the plunger 30. The piston 40 is an example of a shaft member inserted into the syringe 20 closer to the opening 22 than the plunger 30 and configured to be slidable in the axial direction of the syringe 20.

[0036] 3, the piston 40 includes a contact portion 41 that contacts the base end of the plunger 30, and a rod-shaped shaft portion 42 that extends in the axial direction of the syringe 20. The shaft portion 42 is connected to the base end of the contact portion 41. The piston 40 is formed by resin molding here, and the contact portion 41 and the shaft portion 42 are integrally configured. However, the material of the piston 40 is not particularly limited. The contact portion 41 and the shaft portion 42 may be configured to be separable.

[0037] 3, in this embodiment, the abutment portion 41 has a flange portion 41a that abuts against the step portion 33 of the plunger 30, a columnar portion 41b that is inserted into the space inside the step portion 33, and a protrusion portion 41c that abuts against the bottom portion 32 of the plunger 30. The flange portion 41a, the columnar portion 41b, and the protrusion portion 41c are all centered on the central axis C1 of the piston 40.

[0038] The flange portion 41a is formed in an annular shape and has an outer diameter corresponding to the inner diameter of the cylindrical portion 31 of the plunger 30. The lower surface of the flange portion 41a abuts against the upper surface of the step portion 33 of the plunger 30. The columnar portion 41b is formed in a cylindrical shape with an outer diameter corresponding to the inner diameter of the step portion 33. The columnar portion 41b is inserted into the space inside the step portion 33. The lower surface of the columnar portion 41b is spaced apart from the bottom portion 32 of the plunger 30.

[0039] The protrusion 41c is configured in a cylindrical shape extending in the axial direction of the syringe 20. The protrusion 41c extends downward from the lower surface of the columnar portion 41b. The protrusion 41c has an even smaller diameter than the columnar portion 41b. The tip of the protrusion 41c is formed in a conical shape corresponding to the bottom portion 32 of the plunger 30. The protrusion 41c abuts against the upper surface of the bottom portion 32 of the plunger 30. FIG. 5 is a plan view of the abutment portion 41 as seen from the tip side. As shown in FIG. 5, the protrusion 41c is arranged to include the central axis C1 of the plunger 30 when viewed in the axial direction of the syringe 20.

[0040] As shown in FIG. 3 , the shaft portion 42 extends upward from the upper surface of the abutment portion 41. The shaft portion 42 is configured in a rod shape. The upper end of the shaft portion 42 of the piston 40 is connected to the connecting shaft 185 of the pressing device 180. As shown in FIG. 5 , the shaft portion 42 is provided so as to include the central axis C1 of the syringe 20 when viewed in the axial direction of the syringe 20. The shaft portion 42 is disposed on the central axis C1 in the radial direction of the piston 40. In this embodiment, the shaft portion 42 includes four plate-shaped members 42 a extending radially from the central axis C1 of the piston 40. The four plate-shaped members 42 a each extend in the axial direction and the radial direction of the syringe 20. When viewed in the axial direction of the syringe 20, the four plate-shaped members 42 a extend in directions spaced apart by 90 degrees from one another. However, the shape of the shaft portion 42 is not limited to the above. The shaft portion 42 may be configured, for example, in the shape of a simple cylinder or a prism.

[0041] The abutment portion 41 is provided with an air discharge path 43 that connects the through-hole 34 of the plunger 30 to the external space S2 of the syringe unit 10. In this embodiment, the air discharge path 43 is composed of a plurality of through-holes 43a formed in the columnar portion 41b and a space 40a below the columnar portion 41b. The space 40a below the columnar portion 41b is a space outside the protrusion 41c in the radial direction of the syringe 20. When viewed in the axial direction of the syringe 20, the through-hole 34 of the plunger 30 is disposed inside the space 40a below the columnar portion 41b and overlaps with the space 40a below the columnar portion 41b (the axial direction of the syringe 20 is not shown, but see FIG. 3). The through-hole 34 of the plunger 30 communicates with the space 40a below the columnar portion 41b. The plurality of through holes 43a each penetrates the columnar portion 41b in the axial direction of the syringe 20. As shown in FIG. 5, when viewed in the axial direction of the syringe 20, the plurality of through holes 43a are arranged inside the lower space 40a of the columnar portion 41b. The plurality of through holes 43a and the lower space 40a of the columnar portion 41b are in communication with each other. The through holes 43a of the piston 40 and the through hole 34 of the plunger 30 are in communication with each other via the lower space 40a of the columnar portion 41b.

[0042] As shown in FIG. 5, in this embodiment, four through holes 43a are provided. The four through holes 43a are respectively arranged in four regions on the columnar portion 41b partitioned by the four plate-like members 42a of the shaft portion 42. Here, the four through holes 43a are arranged at 90-degree intervals on a circle centered on the central axis C1 of the piston 40. The multiple through holes 43a are arranged to avoid the shaft portion 42 and the protrusion portion 41c when viewed in the axial direction of the syringe 20. The multiple through holes 43a communicate between the external space S2 of the syringe unit 10 and the space 40a below the columnar portion 41b. As a result, the through hole 34 of the plunger 30 communicates with the external space S2 of the syringe unit 10 via the through hole 43a of the piston 40 and the space 40a below the columnar portion 41b.

[0043] As described above, the plurality of through holes 34 of the plunger 30 and the air discharge passage 43 of the piston 40 form a flow passage that connects the space S1 below the plunger 30 with the external space S2.

[0044] As shown in FIG. 3 , the syringe unit 10 includes a hydrophobic filter 50 that blocks the multiple through-holes 34 of the plunger 30. The hydrophobic filter 50 is an example of a ventilation member that allows gas to pass through but blocks liquid. Here, the hydrophobic filter 50 is a woven fiber that forms gaps large enough to allow gas to pass through but not liquid. However, the ventilation member may also be made of a non-hydrophobic material that has been treated with a water-repellent coating. The hydrophobic filter 50 preferably has a Gurley second (the time it takes for 100 ml of air to pass through a filter under specified conditions using a Gurley tester, JIS P8117:2009) of 100 seconds or less. More preferably, the hydrophobic filter 50 has a Gurley second of 12 seconds or less. Here, the number of hydrophobic filters 50 is one. In this embodiment, one hydrophobic filter 50 blocks the multiple through-holes 34. However, the hydrophobic filter 50 may be divided into a plurality of hydrophobic filters that respectively block a plurality of through-holes 34. The hydrophobic filter 50 is fixed to the plunger 30 by being sandwiched between the plunger 30 and the piston 40. However, the method for fixing the hydrophobic filter 50 is not limited. For example, the hydrophobic filter 50 may be attached to the plunger 30 with an adhesive or the like.

[0045] The hydrophobic filter 50 may be provided so as to block the air discharge path 43 of the piston 40. For example, the hydrophobic filter 50 may be provided so as to block the upper end opening of the through-hole 43a of the piston 40. The hydrophobic filter 50 may be provided so as to block the flow path that connects the lower space S1 of the plunger 30 with the external space S2.

[0046] [Air exhaust procedure] The following describes an example of a procedure for discharging air from the syringe 20. Because air is a compressible fluid, if air remains in the syringe 20, it may not be possible to discharge an accurate amount of the discharge material 1. Therefore, the process of discharging the air from the syringe 20 is very important for accurate discharge of the discharge material 1.

[0047] According to a preferred example of the air discharge procedure, first, the discharge port 21 of the syringe 20 is plugged. Next, the discharge material 1 is injected into the syringe 20. At this time, air is partially contained within the syringe 20. Next, the plunger 30 and the piston 40 equipped with the hydrophobic filter 50 are inserted into the syringe 20. When the piston 40 is pushed toward the tip of the syringe 20 in this state, air within the syringe 20 is discharged through the through-hole 34 of the plunger 30 and the air discharge path 43 of the piston 40. The through-hole 34 of the plunger 30 is provided with a hydrophobic filter 50, but the hydrophobic filter 50 allows air to pass through, so the air is discharged without any problems. When the piston 40 is further pushed in after almost all of the air has been discharged, the discharge material 1 attempts to leak out through the through-hole 34, but the discharge material 1 is blocked by the hydrophobic filter 50. This allows the air within the syringe 20 to be discharged without causing the discharge material 1 to leak out. When in use, the plug attached to the outlet 21 of the syringe 20 is removed.

[0048] Even if the air is not sufficiently removed from the syringe 20 in the above process, it is possible to further remove the air from the syringe 20 after the syringe unit 10 is attached to the fluid ejection device 100. When the fluid ejection device 100 drives the pressing device 180 to eject the ejection material 1, the air in the syringe 20 is ejected from the through-hole 34 of the plunger 30 and the air ejection path 43 of the piston 40, using the same principle as in the above process. Even at this time, the hydrophobic filter 50 prevents the ejection material 1 from leaking out of the syringe unit 10 from the base end side.

[0049] [Effects of the embodiment] The following describes the effects that can be achieved by the syringe unit 10 and the fluid ejection device 100 according to this embodiment.

[0050] The syringe unit 10 according to this embodiment includes a cylindrical syringe 20 having a discharge port 21 at its tip end and an opening 22 at its base end, a plunger 30 inserted into the syringe 20 through the opening 22 and slidable in the axial direction of the syringe 20, and a piston 40 inserted into the syringe 20 closer to the opening 22 than the plunger 30 and slidable in the axial direction of the syringe 20. The piston 40 includes a rod-shaped shaft 42 extending in the axial direction of the syringe 20. The plunger 30 is formed with a flow path (in this embodiment, consisting of a plurality of through-holes 34 in the plunger 30 and an air discharge path 43 in the piston 40) that connects a space S1 on the discharge port 21 side of the plunger 30 to an external space S2. The syringe unit 10 further includes a hydrophobic filter 50 that is arranged to block the flow paths 34, 43 and allows gas to pass through but blocks liquid.

[0051] According to this syringe unit 10, the flow paths 34, 43 formed in the plunger 30 and the piston 40 connect the space S1 on the discharge port 21 side of the plunger 30 (the space below the plunger 30) to the external space S2. The syringe unit 10 is provided with a hydrophobic filter 50 that is arranged to block the flow paths 34, 43 and allows gas to pass but blocks liquid. Therefore, even when the piston 40 presses the plunger 30, air in the space S1 below the plunger 30 can be discharged to the outside via the hydrophobic filter 50 without being obstructed by the piston 40. Meanwhile, the hydrophobic filter 50 prevents leakage of the discharge material 1 from the syringe 20. This ensures that the air in the syringe 20 is discharged reliably, allowing the discharge material 1 to be stably discharged.

[0052] For example, the through-hole 34 of the plunger 30 may be positioned to overlap the shaft portion 42 of the piston 40, in which case the air discharge path 43 may be configured to penetrate the interior of the shaft portion 42. The piston 40 may only have the shaft portion 42 positioned to avoid the through-hole 34 of the plunger 30, and may not have a portion such as the abutment portion 41 of this embodiment. The phrase "the plunger 30 and the piston 40 are provided with a flow path that connects the space S1 on the discharge port 21 side of the plunger 30 to the external space S2" also includes, for example, the following configurations. These configurations also allow the space S1 below the plunger 30 to be connected to the external space S2, thereby allowing air to be released from the space S1 below the plunger 30.

[0053] In this embodiment, the shaft 42 is arranged to include the central axis C1 of the syringe 20 when viewed in the axial direction of the syringe 20. The flow paths 34, 43 are arranged to avoid the shaft 42 when viewed in the axial direction of the syringe 20. This configuration makes it easy to realize the flow paths 34, 43 that communicate the space S1 below the plunger 30 with the external space S2. A configuration in which the shaft of the piston is arranged on the central axis of the syringe is a common configuration for syringe units, and the technology of this embodiment can be suitably applied to such common syringe units. Because the shaft 42 is arranged to include the central axis C1 of the syringe 20, the through-hole 34 and the air discharge path 43 are arranged to avoid the central axis C1 of the syringe 20 when viewed in the axial direction of the syringe 20.

[0054] In this embodiment, the plunger 30 is formed with a plurality of through-holes 34 that constitute part of the flow paths 34, 43 and are each arranged to avoid the shaft portion 42. The hydrophobic filter 50 is provided to block the plurality of through-holes 34. With this configuration, by providing the plurality of through-holes 34, air can be discharged from the space S1 below the plunger 30 with less resistance. Furthermore, even if the hydrophobic filters 50 of some of the through-holes 34 are clogged by the discharge material 1, air can be discharged through the other through-holes 34. Note that, for example, if the piston 40 does not have the abutment portion 41, the plurality of through-holes 34 may constitute the entire flow path.

[0055] In this embodiment, the shortest width (diameter in this embodiment) of the through-holes 34 is longer than the longest width of the primary particles 2 contained in the discharge material 1. With this configuration, clogging of the through-holes 34 with the discharge material 1 due to the size of the through-holes 34 can be suppressed.

[0056] The fluid ejection device 100 according to this embodiment includes a pressing device 180 that moves the piston 40 in the axial direction of the syringe 20. With this configuration, when the pressing device 180 presses the piston 40, air is expelled from the syringe 20, even during the ejection of the ejection material 1, for example. Therefore, even if air removal before attaching the syringe unit 10 to the fluid ejection device 100 is insufficient, the air can be expelled from the syringe 20.

[0057] [Other embodiments] A preferred embodiment has been described above. However, the syringe unit and liquid discharge device of the present invention are not limited to the above embodiment. For example, in the above embodiment, the shaft 42 of the piston 40 is located on the central axis C1 of the syringe 20. However, the shaft of the piston may be located so as to avoid the central axis of the syringe. In that case, the through-hole of the plunger and the through-hole of the piston may be located on the central axis of the syringe. Furthermore, in the above embodiment, the plunger 30 and the piston 40 are configured as separate components. However, the plunger 30 and the piston 40 may be configured as a single, integrated component.

[0058] The configuration of the fluid ejection device 100 described above is merely an example, and the configuration of the fluid ejection device is not limited to the above. The fluid ejection device may suitably use any conventionally known fluid ejection device configuration that holds a syringe unit and pushes a plunger.

[0059] Unless otherwise specified, the embodiments do not limit the present invention. [Explanation of symbols]

[0060] 10 syringe units 20 syringes 21 Discharge port 22 Opening 30 Plunger 34 Through hole (flow path) 40 Piston (shaft member) 42 Shaft 43 Air exhaust channel (flow path) 50 Hydrophobic filter (ventilation material) 100 Fluid discharge device (discharge device) 180 Pressing device S1 Space below the plunger S2 External space

Claims

1. a cylindrical syringe having a discharge port at its tip end and an opening at its base end; a plunger inserted into the syringe through the opening and slidable in the axial direction of the syringe; a shaft member that has a rod-shaped shaft portion extending in the axial direction of the syringe, is inserted into the syringe closer to the opening than the plunger, and is slidable in the axial direction of the syringe; a flow path is formed in the plunger and the shaft member, the flow path connecting a space on the discharge port side of the plunger to the outside; The device further includes a ventilation member that is provided to close the flow path and allows gas to pass through but blocks liquid. Syringe unit.

2. the shaft portion is provided so as to include a central axis of the syringe when viewed in the axial direction of the syringe, The flow path is arranged to avoid the shaft portion when viewed in the axial direction of the syringe. The syringe unit according to claim 1 .

3. The plunger has a plurality of through holes that form at least a part of the flow path and are arranged so as to avoid the shaft portion, The ventilation member is provided to close the plurality of through holes. The syringe unit according to claim 2 .

4. the minimum width of the flow path is longer than the maximum width of primary particles contained in the liquid contained in the syringe and discharged from the discharge port; The syringe unit according to claim 1 .

5. A syringe unit according to any one of claims 1 to 4, a pressing device that moves the shaft member in the axial direction of the syringe.

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