Liquid injection devices and beauty devices

Abstract

This invention provides a novel liquid injection device that employs microneedles, enabling easy penetration of liquid to desired locations on the skin. [Solution] A liquid injection device comprising: a shaft portion having an internal space for containing liquid; a microneedle portion having a through hole communicating with the internal space; and a discharge portion for discharging liquid from the through hole, wherein the microneedle portion has a main body portion having a cylindrical side wall portion and a bottom portion connected to the side wall portion, a plurality of first microneedles provided at the bottom portion and having through holes, and a plurality of second microneedles provided at the bottom portion and smaller than the first microneedles, wherein the shaft portion has a cylindrical shaft portion body and a cylindrical adapter provided at one end of the shaft portion body, the adapter has a cylindrical adapter body into which the main body portion fits, and a flange provided circumferentially on the outer surface of the adapter body, the main body portion having liquid-tight contact between the inner surface of the bottom portion and the tip of the adapter body, and the end of the side wall portion and the flange being spaced apart.

Description

Technical Field

[0001] The present invention relates to a liquid injector and a beauty instrument.

Background Art

[0002] Conventionally, an instrument for transdermally administering a drug or the like using a fine needle called a "microneedle" is known. A microneedle is a needle with a diameter and length of less than 1 mm (on the order of μm).

[0003] As such an instrument, a microneedle sheet patch having a microneedle containing a polymer that dissolves in vivo and a functional material for administration target is known (see, for example, Patent Document 1). In the patch described in Patent Document 1, the functional material constituting the microneedle can be administered into the skin by the dissolution of the microneedle punctured into the skin in vivo.

[0004] However, the patch described in Patent Document 1 needs to be attached to the skin for a long time until the microneedle dissolves in vivo. Therefore, there is a risk that the skin at the attached portion may become inflamed.

[0005] In response to this problem, the inventors have developed a liquid applicator having a microneedle (see Patent Document 2). In the liquid applicator described in Patent Document 2, a fixed amount of liquid can be discharged in conjunction with a switch mechanism, and the liquid can be infiltrated to a desired position by a simple operation.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] In the liquid applicator described in Patent Document 2, liquid is dispensed via a dispensing section having minute protrusions (microneedles). However, considering the objective of penetrating the liquid to a desired location on the skin, there is still room for improvement in the configuration surrounding the microneedles.

[0008] This invention has been made in view of the above circumstances, and aims to provide a novel liquid injection device that employs microneedles and can easily penetrate liquid to a desired location on the skin. It also aims to provide a cosmetic device equipped with such a liquid injection device. [Means for solving the problem]

[0009] Microneedles, being tiny structures, are susceptible to damage when subjected to forces exceeding those typically experienced during normal use. For example, during the assembly of a liquid injection device, applying excessive force to a component containing microneedles can cause the microneedles to break. Therefore, the novel liquid injection device described above requires a configuration that suppresses damage to the component containing microneedles.

[0010] To solve the above problems, one aspect of the present invention includes the following aspects.

[0011] [1] A liquid injection device comprising: a shaft portion having an internal space for containing liquid; a microneedle portion having a through hole communicating with the internal space; and a discharge portion for discharging the liquid from the through hole, wherein the microneedle portion comprises a main body portion having a cylindrical side wall portion and a bottom portion connected to the side wall portion, a plurality of first microneedles provided on the bottom portion and having the through hole, and a plurality of second microneedles provided on the bottom portion and smaller than the first microneedles, wherein the shaft portion comprises a cylindrical shaft portion body and a cylindrical adapter provided at one end of the shaft portion body, the adapter comprises a cylindrical adapter body into which the main body portion fits, and a flange provided circumferentially on the outer surface of the adapter body, wherein the main body portion has liquid-tight contact between the inner surface of the bottom portion and the tip of the adapter body, and the end of the side wall portion and the flange are spaced apart.

[0012] [2] The liquid injection device according to [1], wherein the periphery of the outer surface of the bottom is a convex curved surface that is continuous in the circumferential direction of the bottom.

[0013] [3] The liquid injection device according to [1] or [2], wherein the side wall portion is thicker on the end side than on the bottom side.

[0014] [4] A liquid injection device according to any one of the claims [1] to [3], wherein at least one second microneedle is provided between the two first microneedles.

[0015] [5] The liquid injection device according to any one of the items [1] to [4], wherein the microneedle portion has a microneedle group comprising one first microneedle and three or more second microneedles adjacent to the first microneedle in a field of view along the central axis of the shaft portion, and in the microneedle group, the three or more second microneedles surround the first microneedle.

[0016] [6] The liquid injection device according to [5], wherein the distances from the first microneedle to the third or more second microneedles are equal in the group of microneedles.

[0017] [7] The micro needle part has a plurality of regions set concentrically with the central axis in a view along the central axis of the shaft part, and the plurality of first micro needles are arranged in the circumferential direction in an annular region sandwiched between two of the regions. The liquid injector according to any one of [1] to [6].

[0018] [8] The plurality of first micro needles are provided at equal angular intervals in the circumferential direction. The liquid injector according to [7].

[0019] [9] The distance between two of the first micro needles is 1.0 mm or more and 10 mm or less. The liquid injector according to any one of [1] to [8].

[0020]

[10] The diameter of the through hole is 50 μm or more and 300 μm or less. The liquid injector according to any one of [1] to [9].

[0021]

[11] The micro needle part is provided detachably with the shaft part via the main body part. The liquid injector according to

[10] .

[0022]

[12] A beauty instrument having the liquid injector according to any one of [1] to

[11] and the liquid accommodated in the internal space.

Advantages of the Invention

[0023] According to the present invention, it is possible to provide a novel liquid injector that employs a micro needle and can easily penetrate a liquid into a desired position on the skin. Further, it is possible to provide a beauty instrument provided with such a liquid injector.

Brief Description of the Drawings

[0024] [Figure 1] FIG. 1 is a schematic perspective view of the liquid injector 1 of the present embodiment. [Figure 2] FIG. 2 is a schematic cross-sectional view of the micro needle part 20. [Figure 3] Figure 3 is a schematic cross-sectional view of the microneedle portion 20. [Figure 4] Figure 4 is an explanatory diagram showing a part of the tip configuration of the liquid injection device 1. [Figure 5] Figure 5 is a schematic cross-sectional view illustrating the microneedles of the microneedle section 20. [Figure 6] Figure 6 is a schematic diagram of the microneedle portion 20 in a field of view along the central axis C of the shaft portion. [Figure 7] Figure 7 is a schematic diagram of the microneedle portion 20 in a field of view along the central axis C of the shaft portion. [Figure 8] Figure 8 is a schematic cross-sectional view of the liquid injection device 1 in a virtual plane along the central axis C. [Figure 9] Figure 9 is a schematic cross-sectional view of the tip portion of the liquid injector 1. [Modes for carrying out the invention]

[0025] [Liquid injection tool] The liquid injection device according to this embodiment will be described below with reference to Figures 1 to 9. Note that in all the following drawings, the dimensions and proportions of each component have been appropriately altered for clarity.

[0026] Figure 1 is a schematic perspective view of the liquid injector 1 of this embodiment. The liquid injector 1 has a shaft portion 10, a microneedle portion 20, and a discharge portion 30. The liquid injector 1 is used to inject liquid L into a desired location on the skin.

[0027] The shaft portion 10 has a cylindrical shaft body 11. The shaft body 11 is a single component formed by the communication of a cylindrical first member 111 and a cylindrical second member 112 having a smaller diameter than the first member 111. The shaft portion 10 has an internal space IS for containing the liquid L. In Figure 1, the shaft portion 10 is shown as a cylindrical component, but it is not limited to this and may be elliptical or rectangular. Furthermore, the shaft portion 10 may have a circumferential recess (constriction) in a part of it, so as to change its outer diameter.

[0028] The shaft portion 10 may be made of a polymer or a metal. Furthermore, a portion of the shaft portion 10 may be light-transmitting. It is preferable that the shaft portion 10 has light-transmitting properties at a position corresponding to the internal space IS, as this makes it easier to check the remaining amount of the contained liquid L.

[0029] The liquid L may be housed directly inside the shaft portion 10, or a cartridge (not shown) containing the liquid L may be housed inside the shaft portion 10. In the former case, the internal space IS is directly set inside the shaft portion 10. In the latter case, the internal space IS refers to the space in the cartridge that houses the liquid L.

[0030] The microneedle portion 20 is provided at the first end of the shaft portion 10 (the end on the second member 112 side). The microneedle portion 20 has a through hole (see Figure 2) that communicates with the internal space IS, and discharges the liquid L contained in the internal space IS through the through hole. The configuration of the microneedle portion 20 will be described in detail later.

[0031] The discharge section 30 has the function of discharging liquid L from the through-hole of the microneedle section 20. The discharge section 30 has a button 31 provided at the second end (the end on the first member 111 side) of the shaft section 10, a piston 32 housed in the internal space IS, and a shaft 33 connected to the piston 32. In addition, the discharge section 30 has a quantitative moving section (not shown) housed in the shaft section 10.

[0032] The dispensing unit 30 moves the shaft 33 toward the piston 32 by a fixed amount each time the user presses the button 31. The piston 32 is pushed out by the shaft 33 and moves the internal space IS toward the microneedle section 20. At this time, the dispensing unit 30 moves the piston 32 by a fixed amount each time the button is pressed by a quantitative movement mechanism (not shown). As a result, the dispensing unit 30 moves the piston 32 when the user presses the button 31, and the piston 32 pushes (dispenses) the liquid L contained in the internal space IS out of the through hole of the microneedle section 20.

[0033] The piston 32 has a cylindrical body 321 and a protrusion 322 provided on the microneedle portion 20 side of the body 321. The protrusion 322 has a smaller diameter than the body 321 and is frustoconical in shape, with its outer diameter gradually decreasing towards the microneedle portion 20 side.

[0034] The piston 32 is preferably formed from an elastic material. At least the portion of the piston 32 that contacts the inner wall of the shaft portion 10 facing the internal space IS is preferably made of an elastic material. A known synthetic rubber can be used as the elastic material.

[0035] The quantitative movement mechanism can be configured to advance the shaft 33 by pressing a button 31, similar to a known click-type mechanical pencil. In Figure 1, the button 31 is shown to be located at the second end of the shaft 10, but it is not limited to this configuration; it may also be located on the side of the shaft 10 (a so-called side-knock type).

[0036] In addition, the dispensing section 30 may employ a quantitative movement mechanism that extends the shaft 33 by rotating the button 31 in the circumferential direction of the shaft section 10, similar to known rotary (screw) type mechanical pencils.

[0037] Furthermore, the dispensing unit 30 may be configured so that the amount of liquid L dispensed is not fixed in quantity, but can be adjusted by the user depending on how much the button 31 is pressed.

[0038] In addition, the liquid injection device 1 has a protective cap 50 to protect the microneedle portion 20.

[0039] Figure 2 is a schematic cross-sectional view showing the detailed configuration of the tip of the liquid injector 1. Figure 3 is a schematic cross-sectional view showing the microneedle portion 20. Figures 2 and 3 show cross-sections when the liquid injector 1 is cut by a virtual plane containing the central axis C.

[0040] The shaft portion 10 includes a shaft body 11, an inner tube 12, and an adapter 13.

[0041] The inner tube 12 is a tubular member housed inside the second member 112 of the shaft body 11, and communicates with the internal space IS1, which is the internal space of the first member 111. The inner tube 12 communicates with the main tube 121 and a side tube 122 provided at the end of the main tube 121, which has a larger diameter than the main tube 121. A flange 123 is provided on the outer surface of the side tube 122 in the circumferential direction. The inner diameter of the side tube 122 gradually decreases toward the main tube 121 side.

[0042] The inner tube 12 is housed in the second member 112 from the flange 123 side. In the shaft body 11, the connection portion 11x between the first member 111 and the second member 112 has a smaller diameter than the outer diameter of the flange 123. Therefore, the inner tube 12 abuts against the connection portion 11x of the flange 123.

[0043] The adapter 13 is a cylindrical member that fixes the inner tube 12 to the shaft body 11 and the microneedle portion 20 to the shaft 10. The adapter 13 has a cylindrical adapter body 131 and a flange 132 provided circumferentially on the outer surface of the adapter body 131.

[0044] The outer diameter of the adapter body 131 is equal to the inner diameter of the second member 112, and the adapter body 131 is inserted into the second member 112. A groove 131x is formed in the circumferential direction on the outer surface of the adapter body 131 that faces the inner surface of the second member 112, and an O-ring 138 is provided in the groove 131x.

[0045] The inner diameter of the adapter body 131 is equal to or greater than the outer diameter of the main pipe 121 of the inner pipe 12. The inner pipe 12 is inserted inside the adapter body 131.

[0046] The adapter 13 is inserted into the second member 112 with the inner tube 12 housed within it. Inside the second member 112, the adapter 13 is inserted between the second member 112 and the inner tube 12 and abuts against the flange 123. The adapter 13 is fixed inside the second member 112 with an O-ring 138, thereby fixing the inner tube 12 with the flange 123 sandwiched between the adapter 13 and the shaft body 11.

[0047] The inside of the adapter 13 and the inner tube 12 is an internal space IS2 that communicates with the internal space IS1.

[0048] Furthermore, the main body portion 25 (described later) of the microneedle portion 20 is fitted to the tip side of the adapter body 131. A groove 131y is formed in the circumferential direction on the outer surface of the adapter body 131 that faces the inner surface 25x of the main body portion 25 (the inner surface 251x of the side wall portion 251), and an O-ring 139 is provided in the groove 131y. As a result, the microneedle portion 20 is detachably attached to the shaft portion 10. Because the microneedle portion 20 is detachable, it is easy to replace the microneedle portion 20 if it becomes contaminated.

[0049] At the tip end of the adapter 13 (the side with the microneedle portion 20), the inside of the adapter 13 consists of an interior 13a into which the main tube 121 is inserted, a neck 13b that communicates with the interior 13a and has a smaller diameter than the interior 13a, and an opening 13c that is continuous with the neck 13b and has a gradually increasing inner diameter. The space enclosed by the opening 13c and the inner surface 25x of the main body portion 25 (inner surface 252x of the bottom portion 252) is the internal space IS3.

[0050] The inner tube 12 and adapter 13 are made of resin. Examples of materials for the inner tube 12 and adapter 13 include thermoplastic resins such as polystyrene (PS), polypropylene (PP), acrylonitrile-butadiene-styrene resin (ABS), polyvinyl chloride (PVC), polycarbonate (PC), polyethylene (PE), polylactic acid (PLA), and polyglycolic acid (PGA). Furthermore, the above materials are examples, and any thermoplastic resin exhibiting a Young's modulus equivalent to the exemplified materials can be used in the same manner.

[0051] The microneedle section 20 includes a plurality of first microneedles 21 having through holes 211, a plurality of second microneedles 22 smaller than the first microneedles 21, and a main body section 25 on which the first microneedles 21 and the second microneedles 22 are provided.

[0052] In the following explanation, the "first microneedle" will be simply referred to as the "first needle," and the "second microneedle" will be simply referred to as the "second needle."

[0053] In the microneedle section 20, at least one second needle 22 is provided between the two first needles 21. In the microneedle section 20 of Figure 2, two second needles 22 are provided between the two first needles 21.

[0054] The main body 25 has a cylindrical side wall portion 251 and a bottom portion 252 connected to the side wall portion 251. In the main body 25, the area between the side wall portion 251 and the bottom portion 252 is chamfered and curved. Specifically, the outer edge of the bottom portion 252 is a convex curved surface 25a that is continuous in the circumferential direction of the bottom portion 252. The radius of curvature of the convex curved surface 25a is preferably 0.1 mm or more and 5.0 mm or less. A liquid injection device 1 in which the radius of curvature of the convex curved surface 25a is within the above range causes less irritation to the skin when the microneedle portion 20 comes into contact with the skin during use, resulting in a good user experience.

[0055] The radius of curvature can be measured by cutting the microneedle portion 20 to form a cross-section similar to that shown in Figure 3, and then taking an image of the cross-section to obtain a magnified photograph.

[0056] Multiple first needles 21 and multiple second needles 22 are provided in the bottom portion 252. The through holes 211 in the first needles 21 penetrate the first needles 21 and the bottom portion 252 and communicate with the internal space IS (internal space IS3).

[0057] In the cross-section shown in Figure 3, the angle θ between the inner surface 251x of the side wall 251 and the inner surface 252x of the bottom 252 is preferably 90°. The angle θ is allowed to deviate from 90° due to manufacturing tolerances.

[0058] Furthermore, while the thickness T of the side wall portion 251 may be uniform, it is preferable that the side opposite the bottom portion 252 (the end portion 251a side) is thicker than the side facing the bottom portion 252. By forming the end portion 251a side of the side wall portion 251 to be thicker, damage to the microneedle portion 20 during assembly can be suppressed.

[0059] At the end portion 251a of the side wall portion 251, the inner surface is chamfered, forming a continuous inclined surface 251b in the circumferential direction. This makes it easier to insert the microneedle portion 20 into the adapter 13.

[0060] The microneedle portion 20 is made of resin. Examples of materials for the microneedle portion 20 include thermoplastic resins such as PS, PP, ABS, PVC, PC, PE, PLA, and PGA, which were exemplified as materials for the inner tube 12 and adapter 13. Among these materials, polypropylene is preferred. A microneedle portion 20 made of polypropylene is moderately elastic and easily deforms under stress, and is less likely to break when the microneedle portion 20 is fitted into the adapter 13 during assembly.

[0061] Figure 4 is an explanatory diagram showing a part of the tip configuration of the liquid injection device 1. In the main body portion 25 of the microneedle portion 20, the inner surface 252x of the bottom portion 252 and the tip 131a of the adapter body are in liquid-tight contact, forming an internal space IS3.

[0062] On the other hand, the end portion 251a of the side wall portion 251 faces the flange 132 of the adapter 13, and is spaced apart from the flange 132. A gap G is formed between the end portion 251a of the side wall portion 251 and the flange 132. This allows the microneedle portion 20 to be pushed into the adapter 13 during assembly until the internal space IS3 becomes liquid-tight.

[0063] Furthermore, even if the microneedle portion 20 is pressed toward the shaft portion 10 during assembly and use, and the microneedle portion 20 undergoes elastic deformation due to the resulting stress, the microneedle portion 20 will not collide with the flange 132 as long as the deformation of the microneedle portion 20 does not exceed the separation distance of the gap G. Therefore, damage to the microneedle portion 20 when it is pressed toward the shaft portion 10 can be suppressed.

[0064] Furthermore, convex portions 125 and 126 are provided on the outer surface of the tip of the inner tube 12 (main tube 121), aligned in the direction in which the main tube 121 extends. At the tip of the main tube 121, the convex portion 126 is the one relatively closer to the tip of the main tube 121. Both convex portions 125 and 126 are continuous convex portions in the circumferential direction of the main tube 121. The convex portions 125 and 126 are in liquid-tight contact with the interior 13a of the adapter body 131 into which the main tube 121 is inserted.

[0065] In the adapter body 131, the position where the main pipe 121 comes into contact with the convex portions 125 and 126 does not have grooves into which the convex portions 125 and 126 fit, and the interior 13a is a uniform continuous surface.

[0066] The outer diameter DA of the main pipe 121 is equivalent to the inner diameter DC of the interior 13a of the adapter body 131 (DA ≈ DC). On the other hand, the outer diameter DB of the main pipe 121 including the convex portions 125 and 126 is larger than the inner diameter DC of the interior 13a. For example, if the outer diameter DA is 2.5 mm to 15 mm, the outer diameter DB is about 0.05 mm to 0.3 mm larger than the outer diameter DA. Also, the inner diameter DC should be -0.3 mm to +0.3 mm relative to the outer diameter DA.

[0067] Furthermore, a protrusion 135 is provided on the outer surface of the tip of the adapter body 131. The protrusion 135 may be a convex portion that is continuous in the circumferential direction of the adapter body 131, or it may be a plurality of protrusions that are discretely provided in the circumferential direction.

[0068] In the microneedle portion 20, the position where it contacts the protrusion 135 when the adapter body 131 is inserted (inner surface 251x of the side wall portion 251) does not have a groove into which the protrusion 135 fits. The inner surface 252x is a uniform continuous surface.

[0069] The protrusion 135 is provided between the convex portion 125 and the convex portion 126 in the direction of the central axis C. The distance between the convex portion 125 and the convex portion 126 in the direction of the central axis C is 0 mm to 10 mm. Furthermore, the distance HA between the convex portion 125 and the convex portion 135 and the distance HB between the convex portion 126 and the convex portion 135 are both preferably 0 mm to 5 mm.

[0070] When such a main tube 121 is inserted into the adapter body 131, the convex portions 125 and 126 elastically deform and make liquid-tight contact with the interior 13a. In addition, the convex portions 125 and 126 apply pressure in a direction that pushes the adapter body 131 outward (pressure 1).

[0071] Furthermore, when the adapter body 131 is inserted into the microneedle portion 20, the protrusion 135 elastically deforms and applies pressure in a direction that pushes the microneedle portion 20 outward (pressure 2).

[0072] These pressures 1 and 2 securely fix the microneedle section 20 to the adapter 13. Furthermore, the microneedle section 20 can be easily replaced.

[0073] In this configuration, if a protrusion 135 is provided on the adapter body 131 and a groove (recess) is provided on the inner surface 252x of the microneedle portion 20 for the protrusion 135 to fit into, the microneedle portion 20 can be easily fixed to the tip of the adapter 13. On the other hand, when molding the microneedle portion 20 which has a groove on the inside, it is difficult to remove the microneedle portion 20 from the mold, and the microneedles are prone to damage.

[0074] In contrast, the liquid injection device 1, instead of providing a groove on the inner surface 252x into which the protrusion 135 fits, has protrusions 125 and 126 on the main tube 121, and pressurizes the adapter body 131 in a direction that pushes it outward. This suppresses damage to the microneedle portion 20 during manufacturing and allows it to be easily fixed to the adapter 13.

[0075] Figure 5 is a schematic cross-sectional view illustrating the microneedles of the microneedle section 20. As shown in Figure 5, both the first needle 21 and the second needle 22 are frustoconical in shape, with their outer diameter gradually decreasing in the direction away from the base 252. In this embodiment, both the first needle 21 and the second needle 22 have a frustoconical outer shape.

[0076] The first needle 21 has a height H1 of 10 μm or more and 2000 μm or less, an outer diameter D11 of the top surface of 100 μm or more and 500 μm or less, and an outer diameter D12 of the lower end on the bottom 252 side of 200 μm or more and 1000 μm or less.

[0077] The second needle 22 has a height H2 of 10 μm or more and 2000 μm or less, an outer diameter D21 of the top surface of 40 μm or more and 400 μm or less, and an outer diameter D22 of the lower end on the bottom 252 side of 80 μm or more and 800 μm or less.

[0078] The height H1 of the first needle 21 and the height H2 of the second needle 22 may be different, but it is preferable that they be the same. If heights H1 and H2 are the same, molding tolerances are allowed.

[0079] The through-hole 211 has a shape in which a cylindrical first through-hole 211a and a frustoconical second through-hole 211b are in communication. In the through-hole 211 of this embodiment, the first through-hole 211a is cylindrical, and the second through-hole 211b is frustoconical. That is, the through-hole 211 is configured such that the inner diameter gradually decreases from the internal space IS side outwards.

[0080] In Figure 5, the central axis of the through-hole 211 is shown to coincide with the central axis of the frustoconical first needle 21. However, as long as the through-hole 211 opens onto the upper surface of the first needle 21, the central axis of the through-hole 211 may be offset from the central axis of the first needle 21.

[0081] The inner diameter (ID1) of the first through-hole 211a is preferably 30 μm or more and 300 μm or less. The inner diameter (ID2) of the second through-hole 211b is preferably 200 μm or more and 2000 μm or less. When the inner diameter ID1 is 30 μm or more, even highly viscous liquids L can be discharged without delay.

[0082] The multiple first needles 21 in the microneedle section 20 all have the same configuration. Similarly, the multiple second needles 22 in the microneedle section 20 all have the same configuration.

[0083] Figures 6 and 7 are schematic diagrams of the microneedle portion 20 in a field of view along the central axis C of the shaft portion (not shown).

[0084] In the field of view of Figure 6, the microneedle section 20 has a microneedle group G consisting of one first needle 21 and three or more second needles 22 adjacent to the first needle 21. In Figure 6, the microneedle group G has one first needle 21 and five or six second needles 22. In the following description, the microneedle group G will be simply referred to as "needle group G".

[0085] In the microneedle section 20, eight needle groups G are arranged circumferentially around the central axis C. That is, the microneedle section 20 has eight first needles 21. Adjacent needle groups G share one or two second needles 22.

[0086] The microneedle section 20 may have a group of microneedles Gx that does not include the first needle 21. In Figure 6, the group of microneedles Gx is arranged around the central axis C.

[0087] In needle group G, three or more second needles 22 surround the first needle 21. In needle group G, the multiple second needles 22 are arranged at equal angular intervals in the circumferential direction with the first needle 21 as the center.

[0088] Furthermore, in needle group G, the distances from the first needle 21 to the third or more second needles 22 are all equal. For example, in needle group GA shown in Figure 6, the distances L1, L2, and L3 from the first needle 21 to the second needle 22 are all equal.

[0089] In the microneedle section 20, all eight needle groups G are similar in that three or more second needles 22 surround a first needle 21, and the distance from the first needle 21 to the three or more second needles 22 is equal.

[0090] Note that the arrangement of the first needle 21 and the second needle 22 in needle group G is just one example, and various changes are possible.

[0091] In the field of view of Figure 7, the microneedle portion 20 has multiple regions AR1, AR2, and AR3 set concentrically with the central axis C. In Figure 7, the innermost region containing the central axis C is designated as AR1, and the annular regions AR2 and AR3 are set in the direction away from the central axis C.

[0092] The eight first needles 21 are contained within an annular region (region AR2) sandwiched between two regions AR1 and AR3, and are arranged circumferentially within region AR2. Furthermore, the eight first needles 21 are provided at equal angular intervals in the circumferential direction. That is, the angles θ1 to θ8 shown in Figure 7 are equal.

[0093] In region AR2, the distance W between two adjacent first needles in the circumferential direction is between 1.0 mm and 10 mm.

[0094] Figures 8 and 9 are explanatory diagrams showing the method of using the liquid injector 1 described above. Figure 8 is a schematic cross-sectional view of the liquid injector 1 in a virtual plane along the central axis C. Figure 9 is a schematic cross-sectional view of the tip portion of the liquid injector 1. For the sake of clarity, the configuration shown in Figure 2 is abbreviated in Figure 8.

[0095] As shown in Figure 8, when using the liquid injector 1, the user presses the button 31 (see Figure 1) on the discharge unit 30. This causes the shaft 33 of the discharge unit 30 to push out the piston 32 by a certain amount. Depending on the distance the piston 32 moves, liquid L is discharged from the through hole in the first needle 21 of the microneedle unit 20.

[0096] As described above, the shaft portion 10 of the liquid injector 1 is a cylindrical member formed by the communication and integration of a cylindrical first member 111 and a cylindrical second member 112 having a smaller diameter than the first member 111. The body 321 of the piston 32 is fitted into the internal space IS1 of the internal space IS. Furthermore, the protrusion 322 of the piston 32 is sized to fit into a part of the internal space IS2 (the end of the inner tube 12 described above). Therefore, when the piston 32 is pushed to the end of the internal space IS1, the protrusion 322 fits into the internal space IS2, and the liquid L in the internal space IS2 can also be discharged.

[0097] As shown in Figure 9, the user uses the liquid injection device 1 by pressing the microneedle portion 20 against the skin S. When the microneedle portion 20 is pressed against the skin S, the first needle 21 and the second needle 22 are pressed against the skin S.

[0098] At this time, the second needle 22 penetrates the skin S and functions as an "anti-slip" mechanism that suppresses the displacement of the microneedle portion 20 toward the surface of the skin S. Since the second needle 22 is smaller than the first needle 21, it presses down on the skin S with a pressure F2 that is higher than the pressure F1 applied to the skin S by the first needle 21. Therefore, the microneedle portion 20 is more effective at suppressing displacement on the surface of the skin S compared to, for example, a configuration in which the microneedle portion consists only of microneedles of the same size.

[0099] In this state, the user can press the button on the discharge part (not shown) of the liquid injector 1 to discharge liquid L from the through-hole 211 of the first needle 21 to the desired position where the liquid injector 1 is pressed, and inject the liquid L into the stratum corneum, intradermally, or subcutaneously. Because the liquid L is discharged from the tip of the first needle 21, which is a microneedle, it easily penetrates the skin S.

[0100] In this case, since the liquid injection device 1 suppresses positional displacement by the second needle 22 as described above, it is easy to stably discharge the liquid L to the desired position.

[0101] Furthermore, since the first needle 21 is larger than the second needle 22, it is possible to provide a through-hole 211 with a wider diameter than when the second needle 22 has a through-hole. Therefore, the microneedle section 20 can suitably discharge liquid L from the through-hole 211.

[0102] Thus, the liquid injection device 1, having two types of microneedles of different sizes in its microneedle section 20, can suitably dispense liquid L at a desired location and inject it into the stratum corneum, intradermis, or subcutaneous tissue.

[0103] Furthermore, the microneedle section 20 has the configuration described above using Figures 5 to 7. Specifically, in the microneedle group G (see Figure 6), three or more second needles 22 surround the first needle 21, and since the distance from the first needle 21 to the three or more second needles 22 is equal, displacement of the first needle 21 is further suppressed.

[0104] Furthermore, since the first needles 21 are arranged at equal angular intervals in the annular region AR2 of the microneedle section 20, it is easy to discharge the liquid L without bias toward the outer surface of the microneedle section 20.

[0105] In such a liquid injection device 1, the liquid L to be dispensed can be, for example, a liquid cosmetic or a medicinal solution. The "liquid" may be a solution, a dispersion, or a colloidal solution. The liquid injection device 1 employs the above-described configuration, and the inner diameter of the through-hole 211 of the first needle 21 can be adjusted to a size suitable for dispensing the liquid L, according to the viscosity of the liquid L to be dispensed.

[0106] [Beauty equipment] The beauty device of this embodiment comprises the liquid injection device 1 and the liquid L contained in the internal space IS. The beauty device contains a beauty serum as the liquid L.

[0107] The beauty serums usable in such beauty devices are preferably those containing ingredients that, when injected into the stratum corneum, are expected to provide beauty effects such as firmness, moisture, and radiance to the skin. Examples of such beauty serums include hyaluronic acid, collagen, elastin, ceramide, amino acids, vitamin C derivatives, glycyrrhizic acid, and niacinamide. In addition, pluripotent stem cells and somatic stem cells, as well as substances extracted from these cells (such as exosomes), and the culture supernatant of these cells can also be used as beauty serums.

[0108] In this type of beauty device, when the microneedle portion 20 of the liquid injector 1 is pressed against the skin, the tip of the first needle 21 reaches the stratum corneum, and the beauty serum (liquid L) is directly injected into the stratum corneum through the through-hole 211 of the first needle 21. When the beauty device (liquid injector 1) is removed from the skin, the tiny holes made in the skin by the first needle 21 close naturally due to the elasticity of the skin. As a result, the beauty serum injected into the stratum corneum is trapped within the stratum corneum and penetrates the skin.

[0109] Thus, using the beauty device of this embodiment, it is possible to easily inject and penetrate the beauty serum into the desired location within the stratum corneum.

[0110] With the liquid injection device 1 having the above configuration, it is possible to easily penetrate the liquid to a desired location on the skin by employing microneedles.

[0111] With a beauty device having the above configuration, it is possible to easily penetrate liquid (beauty serum) into the desired location on the skin by having a liquid injection device 1.

[0112] In this embodiment, the liquid injector 1 is configured such that a discharge portion 30 provided on the shaft portion 10 moves the piston 32 toward the microneedle portion 20 within the shaft portion 10, pushing out the liquid L contained in the internal space IS. However, this is not the only configuration. Any known configuration can be adopted as long as it allows the liquid L contained in the internal space IS to be discharged from the microneedle portion 20 and does not hinder the effects of the present invention.

[0113] For example, a liquid injection device may have a discharge section with a pump function at the tip side (microneedle side) of the shaft 10, and a configuration may be adopted in which liquid L is discharged by the pump function of the discharge section when the tip is pressed against the skin. In a liquid injection device with such a configuration, by providing a microneedle section at the tip, the action of pressing the microneedle section against the skin and the operation of discharging liquid L coincide, making it possible to easily penetrate the liquid to the desired location on the skin.

[0114] Preferred embodiments of the present invention have been described above with reference to the attached drawings, but the present invention is not limited to these examples. The shapes and combinations of the constituent members shown in the above examples are merely examples, and can be modified in various ways based on design, specifications, etc., without departing from the spirit of the present invention. [Explanation of symbols]

[0115] 1...Liquid injector, 10...Shaft, 11...Shaft body, 13...Adapter, 13a...Interior, 20...Microneedle section, 21...First microneedle, 22...Second microneedle, 25...Body section, 25a...Convex curved surface, 25x, 251x, 252x...Interior surface, 30...Discharge section, 123, 132...Flange, 131...Adapter body, 131a...Tip, 211...Through hole, 251...Side wall section, 251a...End section, 252...Bottom section, 321...Body, AR1~3...Region, C...Central axis, DA...Diameter, G,GA...Needle group, G,Gx...Microneedle group, ID1,ID2...Inner diameter (diameter), IS, IS1, IS2, IS3...Internal space, L...Liquid, W...Distance, S...Skin, θ1~θ8...Angle

Claims

1. A cylindrical shaft portion, A microneedle portion having a cylindrical side wall and bottom, which is integrally formed, It has an adapter that connects the shaft portion and the microneedle portion, The bottom portion has a plurality of microneedles, A liquid injection device in which an internal space is formed between the tip of the adapter and the inner surface of the bottom of the microneedle portion.

2. The tip of the adapter has a raised portion provided on its outer circumference in a field of view along the central axis of the shaft portion such that it forms the internal space with the bottom of the microneedle portion, The liquid injection device according to claim 1.

3. The adapter has grooves formed in the circumferential direction of the adapter on the portion facing the inner surface of the microneedle portion, and O-rings are provided in the grooves. A liquid injector according to claim 1 or 2.

4. The adapter has a flange provided on its outer surface in the circumferential direction, A liquid injection device according to any one of claims 1 to 3.

5. The periphery of the outer surface of the bottom is a convex curved surface that is continuous in the circumferential direction of the bottom. A liquid injection device according to any one of claims 1 to 4.

6. An inner tube is inserted inside the adapter, A liquid injection device according to any one of claims 1 to 5.

7. A liquid injection device according to any one of claims 1 to 6, A beauty device comprising a beauty serum contained in the aforementioned liquid injector.

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