JP7820808B2 - Liquid injection tools and beauty devices - Google Patents

Description

Application of Article 30, Paragraph 2 of the Patent Act (1) Announced in the catalog of the 10th International Cosmetics Exhibition - COSME TOKYO - (organizer: RX Japan Co., Ltd.) on the website published on December 24, 2021. https://www.cosme-week.jp/ja-jp/search/2022/tokyo/directory/directory-details.org-ba5c7421-51dd-4f22-bd2b-29436b579217. html#/ (2) Oral announcement on January 12, 2022 at the 10th International Cosmetics Exhibition - COSME TOKYO - (organizer: RX Japan Co., Ltd.), held from January 12 to January 14, 2022. (3) Published on the website for the product "Seleia" on January 12, 2022. (4) Announced on page 59 of the April issue of BiST (Kobunsha Inc.), published on February 17, 2022. (5) Announced on the website (https://www.instagram.com/p/CbT6-1JpNTS/) on March 20, 2022. (6) Announced on the website (https://be-story.jp/article/102978) on March 27, 2022.

The present invention relates to a liquid injection device and a beauty device.

Conventionally, devices that use tiny needles called "microneedles" to administer drugs and other substances transdermally have been known. Microneedles are needles with diameters and lengths of less than 1 mm (on the order of μm).

A known example of such a device is a microneedle sheet patch having microneedles containing a polymer that dissolves in the body and a functional material to be administered (see, for example, Patent Document 1). The patch described in Patent Document 1 allows the functional material that makes up the microneedles to be administered into the skin by dissolving in the body after puncturing the skin.

However, the patch described in Patent Document 1 needs to be left on the skin for a long period of time until the microneedles dissolve in the body. This poses a risk of causing a rash on the skin where the patch is attached.

To address this issue, the inventors have developed a liquid applicator with microneedles (see Patent Document 2). The liquid applicator described in Patent Document 2 is capable of discharging a fixed amount of liquid in conjunction with a switch mechanism, allowing the liquid to penetrate the desired location with a simple operation.

JP 2010-94414 A International Publication No. 2021/177318

The liquid applicator described in Patent Document 2 ejects liquid via an ejection section having tiny protrusions (microneedles). Given the goal of penetrating liquid into desired locations on the skin, there is still room for improvement in the structure surrounding the microneedles.

The present invention was made in consideration of these circumstances, and aims to provide a new liquid injection device that employs microneedles and can easily inject liquid into desired areas of the skin. It also aims to provide a beauty appliance equipped with such a liquid injection device.

Microneedles are tiny structures that are susceptible to breakage when subjected to forces exceeding those experienced during normal use. For example, when assembling a liquid injection device, if a strong force is applied to the component containing the microneedle, the microneedle may be damaged. Therefore, the above-mentioned new liquid injection device requires a configuration that prevents damage to the component containing the microneedle.

To solve the above problems, one aspect of the present invention includes the following:

[1] A liquid injection device comprising: a stem having an internal space for storing 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 having a cylindrical sidewall portion and a bottom portion connected to the sidewall portion; a plurality of first microneedles provided at the bottom portion and having the through-holes; and a plurality of second microneedles provided at the bottom portion and smaller than the first microneedles; the stem portion comprises a cylindrical stem main body and a cylindrical adapter provided at one end of the stem main body; the adapter has a cylindrical adapter main body into which the main body portion fits and a flange provided circumferentially on the outer surface of the adapter main body; and wherein the inner surface of the bottom portion and the tip of the adapter main body are in liquid-tight contact, and the end of the sidewall portion and the flange are spaced apart.

[2] A liquid injection device according to [1], wherein the peripheral edge of the outer surface of the bottom portion is a convex curved surface that continues in the circumferential direction of the bottom portion.

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

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

[5] A liquid injection device according to any one of [1] to [4], wherein the microneedle section has a microneedle group consisting of 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 stem section, and in the microneedle group, the three or more second microneedles surround the first microneedle.

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

[7] A liquid injection device described in any one of [1] to [6], wherein the microneedle portion has multiple regions set concentrically with the central axis of the shaft portion in a field of view along the central axis of the shaft portion, and the multiple first microneedles are arranged circumferentially in an annular region sandwiched between two of the regions.

[8] The liquid injection device described in [7], wherein the plurality of first microneedles are arranged at equal angular intervals in the circumferential direction.

[9] A liquid injection device described in any one of [1] to [8], wherein the distance between the two first microneedles is 1.0 mm or more and 10 mm or less.

[10] A liquid injection device according to any one of [1] to [9], wherein the diameter of the through-hole is 50 μm or more and 300 μm or less.

[11] The liquid injection device described in [10], wherein the microneedle portion is detachably attached to the shaft portion via the main body portion.

[12] A beauty device having the liquid injection device described in any one of [1] to [11] and the liquid contained in the internal space.

The present invention provides a novel liquid injection device that employs microneedles and can easily inject liquid into desired areas of the skin. It also provides a beauty device equipped with such a liquid injection device.

FIG. 1 is a schematic perspective view of a liquid injection device 1 according to the present embodiment. FIG. 2 is a schematic cross-sectional view of the microneedle portion 20. FIG. 3 is a schematic cross-sectional view showing the microneedle portion 20. FIG. 4 is an explanatory diagram showing a partial configuration of the tip of the liquid injection tool 1. As shown in FIG. FIG. 5 is a schematic cross-sectional view illustrating the microneedles of the microneedle unit 20. FIG. 6 is a schematic diagram of the microneedle portion 20 in a view along the central axis C of the stem portion. FIG. 7 is a schematic diagram of the microneedle portion 20 in a view along the central axis C of the stem portion. FIG. 8 is a schematic cross-sectional view of the liquid injection device 1 taken along an imaginary plane along the central axis C. FIG. 9 is a schematic cross-sectional view of the tip portion of the liquid injection tool 1.

[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 of the following figures, the dimensions and proportions of the components have been appropriately changed to make the drawings easier to understand.

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

The shaft portion 10 has a cylindrical shaft body 11. The shaft body 11 is a member formed by connecting a cylindrical first member 111 and a cylindrical second member 112 having a smaller diameter than the first member 111, forming a single member. The shaft portion 10 has an internal space IS for containing a liquid L. While the shaft portion 10 is shown as a cylindrical member in Figure 1, it is not limited to this and may also be an elliptical cylindrical member or a rectangular cylindrical member. The outer diameter of the shaft portion 10 may also vary, for example by having a recess (neck) in the circumferential direction in part of the shaft portion.

The stem 10 may be made of a polymer or metal. A portion of the stem 10 may also be optically transparent. It is preferable if the portion of the stem 10 corresponding to the internal space IS is optically transparent, as this makes it easier to check the remaining amount of liquid L contained therein.

The liquid L may be contained directly inside the stem 10, or a cartridge (not shown) containing the liquid L may be contained inside the stem 10. In the former case, the internal space IS is set directly inside the stem 10. In the latter case, the internal space IS refers to the space in the cartridge that contains the liquid L.

The microneedle portion 20 is provided at the first end (the end on the second member 112 side) of the shaft portion 10. The microneedle portion 20 has a through-hole (see Figure 2) that communicates with the internal space IS, and ejects 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.

The ejection unit 30 has the function of ejecting the liquid L from the through-hole of the microneedle unit 20. The ejection unit 30 has a button 31 provided at the second end (the end on the first member 111 side) of the stem unit 10, a piston 32 housed in the internal space IS, and a shaft 33 connected to the piston 32. In addition, the ejection unit 30 has a fixed-amount movement unit (not shown) housed in the stem unit 10.

When the user presses the button 31, the ejection unit 30 moves the shaft 33 toward the piston 32 by a fixed amount each time the button 31 is pressed. The piston 32 is pushed out by the shaft 33 and moves through the internal space IS toward the microneedle unit 20. At this time, the ejection unit 30 moves the piston 32 by a fixed amount each time the button 31 is pressed, using a fixed amount movement unit (not shown). As a result, when the user presses the button 31, the ejection unit 30 moves the piston 32, and the piston 32 pushes (ejects) the liquid L contained in the internal space IS out of the through-hole of the microneedle unit 20.

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

The piston 32 is preferably made of 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 should be made of an elastic material. Known synthetic rubber can be used as the elastic material.

The fixed-amount movement unit can be configured, for example, to advance the shaft 33 a fixed amount by pressing the button 31, similar to known knock-type mechanical pencils. In Figure 1, the button 31 is provided at the second end of the shaft 10, but this is not limiting; it may also be provided on the side of the shaft 10 (a so-called side-knock type).

Alternatively, the discharge unit 30 may employ a fixed-volume movement unit that advances the shaft 33 by rotating the button 31 in the circumferential direction of the shaft 10, similar to known rotary (screw) mechanical pencils.

Furthermore, the discharge unit 30 may not discharge a fixed amount of liquid L, but may allow the user to adjust the amount of liquid L discharged by adjusting the degree to which the button 31 is pressed.

In addition, the liquid injection device 1 has a protective cap 50 that protects the microneedle portion 20.

Figure 2 is a schematic cross-sectional view showing the detailed configuration of the tip of the liquid injection device 1. Figure 3 is a schematic cross-sectional view showing the microneedle portion 20. Figures 2 and 3 show a cross-section of the liquid injection device 1 cut along an imaginary plane including the central axis C.

The shaft 10 has a shaft body 11, an inner tube 12, and an adapter 13.

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

The inner tube 12 is housed in the second member 112 from the flange 123 side. In the shaft main 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 flange 123 of the inner tube 12 abuts against the connection portion 11x.

The adapter 13 is a cylindrical member that secures the inner tube 12 to the stem body 11 and secures the microneedle portion 20 to the stem 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.

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

The inner diameter of the adapter body 131 is equal to or larger 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.

The adapter 13 is inserted into the second member 112 with the inner tube 12 housed in the second member 112. The adapter 13 is inserted between the second member 112 and the inner tube 12 inside the second member 112 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 main body 11.

The interior of the adapter 13 and inner tube 12 is internal space IS2, which communicates with internal space IS1.

The main body 25 (described below) of the microneedle part 20 fits into the tip side of the adapter main body 131. A groove 131y is formed in the circumferential direction on the outer surface of the adapter main body 131 at a location facing the inner surface 25x of the main body 25 (the inner surface 251x of the side wall part 251), and an O-ring 139 is provided in the groove 131y. This allows the microneedle part 20 to be detachably attached to the shaft part 10. Because the microneedle part 20 is detachable, it can be easily replaced if it becomes contaminated.

On the tip side (microneedle portion 20 side) of the adapter 13, the interior of the adapter 13 is made up of an interior 13a into which the main tube 121 is inserted, a neck portion 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 portion 13b and has a gradually increasing inner diameter. The space surrounded by the opening 13c and the inner surface 25x of the main body portion 25 (the inner surface 252x of the bottom portion 252) is the internal space IS3.

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). The above materials are merely examples, and any thermoplastic resin with a Young's modulus equivalent to that of each of the listed materials can be considered equally usable.

The microneedle portion 20 has a plurality of first microneedles 21 each having a through-hole 211, a plurality of second microneedles 22 each smaller than the first microneedles 21, and a main body portion 25 on which the first microneedles 21 and second microneedles 22 are provided.

In the following description, the "first microneedle" will be referred to simply as the "first needle," and the "second microneedle" will be referred to simply as the "second needle."

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

The main body 25 has a cylindrical side wall 251 and a bottom 252 connected to the side wall 251. The portion of the main body 25 between the side wall 251 and the bottom 252 is chamfered to form a curved surface. Specifically, the outer peripheral edge of the bottom 252 is a convex curved surface 25a that continues in the circumferential direction of the bottom 252. The radius of curvature of the convex curved surface 25a is preferably 0.1 mm or greater and 5.0 mm or less. A liquid injection device 1 having a convex curved surface 25a with a radius of curvature within the above range causes less irritation to the skin when the microneedle portion 20 comes into contact with the skin during use, providing a comfortable feel.

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 photographing the cross section to obtain an enlarged image.

A plurality of first needles 21 and a plurality of second needles 22 are provided on the bottom portion 252. The through-holes 211 of the first needles 21 pass through the first needles 21 and the bottom portion 252 and communicate with the internal space IS (internal space IS3).

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

The thickness T of the side wall portion 251 may be uniform, but is preferably thicker on the side opposite the bottom portion 252 (the end portion 251a side) than on the bottom portion 252 side. By forming the end portion 251a side of the side wall portion 251 thicker, damage to the microneedle portion 20 during assembly can be suppressed.

The inner surface of the end 251a of the side wall portion 251 is chamfered to form a circumferentially continuous inclined surface 251b. This makes it easier to insert the microneedle portion 20 into the adapter 13.

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 are exemplified as materials for the inner tube 12 and the adapter 13. Of these materials, polypropylene is preferred. A microneedle portion 20 made of polypropylene is moderately elastically deformable under stress and is less likely to break when the microneedle portion 20 is fitted into the adapter 13 during assembly.

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

On the other hand, the end 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 251a of the side wall portion 251 and the flange 132. This allows the microneedle portion 20 to be pushed into the adapter 13 until the internal space IS3 becomes liquid-tight during assembly.

Furthermore, even if the microneedle portion 20 is pressed toward the shaft portion 10 during assembly and use and elastically deforms due to the stress caused by this, the microneedle portion 20 will not collide with the flange 132 unless the deformation of the microneedle portion 20 exceeds the separation distance of the gap G. Therefore, damage to the microneedle portion 20 when pressed toward the shaft portion 10 can be suppressed.

In addition, convex portions 125, 126 are provided on the outer surface of the tip of the inner pipe 12 (main pipe 121) side by side in the extension direction of the main pipe 121. At the tip of the main pipe 121, the convex portion 126 is the portion relatively closer to the tip of the main pipe 121. Both convex portions 125, 126 are convex portions that are continuous in the circumferential direction of the main pipe 121. Convex portions 125, 126 are in liquid-tight contact with the interior 13a of the adapter body 131 into which the main pipe 121 is inserted.

The adapter body 131 does not have grooves into which the convex portions 125, 126 fit at the positions that come into contact with the convex portions 125, 126 when the main pipe 121 is inserted, and the interior 13a is a uniform, continuous surface.

The outer diameter DA of the main pipe 121 is equal to the inner diameter DC of the interior 13a of the adapter body 131 (DA ≈ DC). Meanwhile, the outer diameter DB of the main pipe 121, including the convex portions 125, 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 approximately 0.05 mm to 0.3 mm larger than the outer diameter DA. It is also recommended that the inner diameter DC be -0.3 mm to +0.3 mm larger than the outer diameter DA.

In addition, a protrusion 135 is provided on the outer surface of the tip of the adapter body 131. The protrusion 135 may be a continuous protrusion in the circumferential direction of the adapter body 131, or may be multiple protrusions provided discretely in the circumferential direction.

The microneedle portion 20 does not have a groove into which the protrusion 135 fits at the position (inner surface 251x of the side wall portion 251) that comes into contact with the protrusion 135 when the adapter body 131 is inserted. The inner surface 252x is a uniform, continuous surface.

The convex portion 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.

When such a main pipe 121 is inserted into the adapter body 131, the convex portions 125, 126 elastically deform to come into liquid-tight contact with the interior 13a. The convex portions 125, 126 also apply pressure to the adapter body 131 in a direction that pushes it outward (pressure 1).

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

These pressures 1 and 2 ensure that the microneedle portion 20 is securely fixed to the adapter 13. They also make it easy to replace the microneedle portion 20.

Here, if a convex portion 135 is provided on the adapter body 131 and a groove (concave portion) into which the convex portion 135 fits is provided on the inner surface 252x of the microneedle portion 20, it is easy to fix the microneedle portion 20 to the tip of the adapter 13. However, when molding a microneedle portion 20 with a groove on the inside, it is difficult to remove the microneedle portion 20 from the mold, and the microneedle is prone to breakage.

In contrast, in the liquid injection device 1, instead of providing a groove on the inner surface 252x into which the protrusion 135 fits, convex portions 125 and 126 are provided on the main tube 121, and pressure is applied in a direction that pushes the adapter body 131 outward. This prevents damage to the microneedle portion 20 during manufacturing and allows it to be easily fixed to the adapter 13.

Figure 5 is a schematic cross-sectional view illustrating the microneedles of the microneedle unit 20. As shown in Figure 5, both the first needle 21 and the second needle 22 have a frustum shape with an outer diameter that gradually decreases in the direction away from the bottom 252. In this embodiment, both the first needle 21 and the second needle 22 have a truncated cone-shaped outer shape.

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.

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.

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 are the same. Note that when height H1 and height H2 are considered "the same," molding error is allowed for.

The through hole 211 has a shape in which a cylindrical first through hole 211a and a frustum-shaped second through hole 211b are connected to each other. In this embodiment, the first through hole 211a is cylindrical, and the second through hole 211b is frustum-shaped. In other words, the through hole 211 has a configuration in which the inner diameter gradually decreases from the internal space IS side toward the outside.

In Figure 5, the central axis of the through hole 211 is shown aligned with the central axis of the truncated cone-shaped first needle 21, but as long as the through hole 211 opens to the top surface of the first needle 21, the central axis of the through hole 211 may be misaligned (offset) from the central axis of the first needle 21.

The inner diameter (diameter) ID1 of the first through-hole 211a is preferably 30 μm or more and 300 μm or less. Furthermore, the inner diameter (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 liquid L can be ejected without delay.

All of the multiple first needles 21 in the microneedle unit 20 have the same configuration. Similarly, all of the multiple second needles 22 in the microneedle unit 20 have the same configuration.

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

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 the "needle group G."

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.

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

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 around the first needle 21.

Furthermore, in needle group G, the distances from the first needle 21 to the three or more second needles 22 are 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 needles 22 are all equal.

In the microneedle section 20, all eight needle groups G are similar, with a first needle 21 surrounded by three or more second needles 22, and the distances from the first needle 21 to each of the three or more second needles 22 are equal.

Note that the arrangement of the first needle 21 and the second needle 22 in the needle group G is an example and can be varied in various ways.

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 including the central axis C is designated AR1, and annular regions AR2 and AR3 are set in the direction away from the central axis C.

The eight first needles 21 are contained in an annular region (region AR2) sandwiched between two regions AR1 and AR3, and are arranged circumferentially in region AR2. The eight first needles 21 are also arranged at equal angular intervals in the circumferential direction. In other words, the angles θ1 to θ8 shown in Figure 7 are equal.

In region AR2, the distance W between two circumferentially adjacent first needles is 1.0 mm or greater and 10 mm or less.

Figures 8 and 9 are explanatory diagrams showing how to use the liquid injection device 1 described above. Figure 8 is a schematic cross-sectional view of the liquid injection device 1 on an imaginary plane along the central axis C. Figure 9 is a schematic cross-sectional view of the tip portion of the liquid injection device 1. For ease of explanation, the configuration shown in Figure 2 is abbreviated in Figure 8.

As shown in Figure 8, when using the liquid injection device 1, the user presses the button 31 (see Figure 1) provided 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 movement distance of the piston 32, liquid L is discharged from the through-hole of the first needle 21 of the microneedle unit 20.

As described above, the shaft 10 of the liquid injection device 1 is a cylindrical member formed by connecting and integrating a cylindrical first member 111 and a cylindrical second member 112 having a smaller diameter than the first member 111. The main body 321 of the piston 32 fits into the internal space IS1 of the internal space IS. The protrusion 322 of the piston 32 is sized to fit into a portion of the internal space IS2 of the internal space IS (the end of the inner tube 12 described above). Therefore, when the piston 32 is pushed all the way to the end of the internal space IS1, the protrusion 322 fits into the internal space IS2, allowing the liquid L in the internal space IS2 to be ejected as well.

As shown in Figure 9, the user presses the microneedle portion 20 of the liquid injection device 1 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.

At this time, the second needles 22 dig into the skin S and function as "anti-slip" devices that prevent the microneedle unit 20 from shifting toward the surface of the skin S. Because the second needles 22 are smaller than the first needles 21, they press down on the skin S with a pressure F2 that is higher than the pressure F1 applied to the skin S by the first needles 21. Therefore, the microneedle unit 20 is more likely to prevent shifting on the surface of the skin S than, for example, when the microneedle unit is configured to only have microneedles of the same size.

In this state, the user can press the button on the discharge section (not shown) of the liquid injection device 1 to discharge liquid L from the through-hole 211 of the first needle 21 at the desired position where the liquid injection device 1 is pressed, thereby injecting liquid L into the stratum corneum, intradermis, or subcutaneously. By being discharged from the tip of the first needle 21, which is a microneedle, liquid L easily penetrates the skin S.

At this time, as described above, the second needle 22 in the liquid injection device 1 prevents misalignment, making it easier to stably dispense the liquid L to the desired position.

Furthermore, because the first needle 21 is larger than the second needle 22, it is possible to provide a through-hole 211 with a larger diameter than if a through-hole were provided in the second needle 22. As a result, the microneedle unit 20 can eject the liquid L suitably from the through-hole 211.

In this way, the liquid injection device 1 has a microneedle section 20 with two different sizes of microneedles, which allows the liquid L to be ejected appropriately at the desired location and injected into the stratum corneum, intradermis, or subcutaneously.

The microneedle unit 20 also has the configuration described above with reference to 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 the distances from the first needle 21 to the three or more second needles 22 are equal, which further facilitates preventing the first needle 21 from shifting out of position.

Furthermore, since the first needles 21 in the microneedle portion 20 are arranged at equal angular intervals in the annular region AR2, it is easy to eject the liquid L evenly onto the outer surface of the microneedle portion 20.

In this type of liquid injector 1, the liquid L to be ejected can be, for example, a liquid cosmetic or a liquid medicine. The "liquid" may be a solution, a dispersion, or a colloidal liquid. By employing the above-described configuration, the liquid injector 1 can adjust the inner diameter of the through-hole 211 of the first needle 21 to a size that allows the liquid L to be ejected appropriately, depending on the viscosity of the liquid L to be ejected.

[Beauty equipment]
The cosmetic device of this embodiment includes the liquid injector 1 and a liquid L contained in the internal space IS. The liquid L contained in the cosmetic device is a cosmetic serum.

Preferably, beauty serums that can be used in such beauty devices contain ingredients that are expected to have beauty effects such as firmness, moisture, and luster on the skin when injected into the stratum corneum. Examples of such beauty serums include hyaluronic acid, collagen, elastin, ceramide, amino acids, vitamin C derivatives, glycyrrhizinic acid, and niacinamide. Furthermore, pluripotent stem cells and somatic stem cells, as well as substances extracted from these cells (such as exosomes), and culture supernatants of these cells can also be used as beauty serums.

In this type of beauty device, the tip of the first needle 21 reaches the stratum corneum where the microneedle portion 20 of the liquid injection device 1 is pressed, and the beauty serum (liquid L) is injected directly into the stratum corneum through the through-hole 211 of the first needle 21. When the beauty device (liquid injection device 1) is removed from the skin, the tiny hole made in the skin by the first needle 21 closes 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 into the skin.

In this way, using the beauty device of this embodiment, beauty serum can be easily injected into the desired location in the stratum corneum and penetrated.

The liquid injection device 1 configured as described above uses microneedles, making it possible to easily inject liquid into the desired location on the skin.

With a beauty device configured as described above, the inclusion of the liquid injection device 1 makes it possible to easily inject liquid (beauty serum) into the desired location on the skin.

The liquid injection device 1 of this embodiment is configured such that the ejection section 30 provided on the stem 10 moves the piston 32 within the stem 10 toward the microneedle section 20, thereby pushing out the liquid L contained in the internal space IS, but this is not limited to this. Any known configuration can be used as long as it can eject the liquid L contained in the internal space IS from the microneedle section 20 and does not impair the effects of the present invention.

For example, the liquid injection device may have a discharge section with pumping function on the tip side (microneedle section side) of the shaft section 10, and the pumping function of the discharge section may be used to discharge the liquid L by pressing the tip against the skin. In a liquid injection device configured in this way, by providing a microneedle section at the tip, the action of pressing the microneedle section against the skin and the action of discharging the liquid L coincide, making it possible to easily infiltrate the liquid into the desired location on the skin.

The above describes preferred embodiments of the present invention with reference to the accompanying drawings, but the present invention is not limited to these examples. The shapes and combinations of the components shown in the above examples are merely examples, and various modifications can be made based on the design, specifications, etc., without departing from the spirit of the present invention.

1...liquid injection device, 10...shaft portion, 11...shaft portion main body, 13...adapter, 13a...interior, 20...microneedle portion, 21...first microneedle, 22...second microneedle, 25...main body portion, 25a...convex curved surface, 25x, 251x, 252x...inner surface, 30...discharge portion, 123, 132...flange, 131...adapter main body, 131a...tip, 211...through hole, 251...side wall portion, 251a...end portion, 252...bottom portion, 321...main body, AR1-3...area, C...center 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...angles

Claims (12)

a stem having an interior space for containing a liquid;
a microneedle portion having a through hole communicating with the internal space;
a discharge portion that discharges the liquid from the through hole,
The microneedle portion includes 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 and having the through holes;
a plurality of second microneedles provided on the bottom and smaller than the first microneedles;
The shaft portion includes a cylindrical shaft main body and
a cylindrical adapter provided at one end of the shaft body,
The adapter includes a cylindrical adapter body into which the main body portion is fitted;
a flange provided circumferentially on the outer surface of the adapter body,
The main body has an inner surface of the bottom and a tip of the adapter body in liquid-tight contact, and an end of the side wall and the flange are spaced apart from each other. A liquid injection device as described in claim 1, wherein the peripheral edge of the outer surface of the bottom portion is a convex curved surface that continues in the circumferential direction of the bottom portion. A liquid injection device according to claim 1 or 2, wherein the side wall portion is thicker at the end than at the bottom. A liquid injection device according to any one of claims 1 to 3, wherein at least one second microneedle is provided between two first microneedles. the microneedle portion has a microneedle group composed of 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 stem portion;
The liquid injection tool according to claim 1 , wherein in the microneedle group, three or more of the second microneedles surround the first microneedle. The liquid injection device described in claim 5, wherein in the microneedle group, the distances from the first microneedle to three or more second microneedles are equal. the microneedle portion has a plurality of regions set concentrically with the central axis of the stem portion in a field of view along the central axis of the stem portion;
The liquid injection device according to claim 1 , wherein the plurality of first microneedles are arranged in a circumferential direction in an annular region sandwiched between the two regions. The liquid injection device according to claim 7, wherein the plurality of first microneedles are arranged at equal angular intervals in the circumferential direction. A liquid injection device according to any one of claims 1 to 8, wherein the distance between the two first microneedles is 1.0 mm or more and 10 mm or less. A liquid injection device according to any one of claims 1 to 9, wherein the diameter of the through-hole is 50 μm or more and 300 μm or less. The liquid injection device according to claim 10, wherein the microneedle portion is detachably attached to the shaft portion via the main body portion. The liquid injection device according to any one of claims 1 to 11;
The liquid contained in the internal space.