Interdental brushes

Abstract

To provide an interdental brush having high interdental insertion property and cleaning actual feeling, improving damage to a gingiva, and reducing occurrence of gingival pain.SOLUTION: There is provided an interdental brush comprising: a grip part 10 having a cylindrical guide part 12 on a tip side of a grip main body part 11; and a brush body 20 having a base shaft 22 on a rear end of the brush part 21. In the interdental brush 1, the base shaft 22 is stored in the guide part 12, the brush part 21 is exposed from the tip of the guide part 12, an elastic member 30 is provided between the base shaft 22 in the guide part 12 and the grip main body part 11, when a load directed toward a rear end is applied to the brush part 21, the elastic member 30 is elastically compressed in a long axis direction, and therefore the brush part 21 is energized to the tip in the long axis direction and is relatively retreated to the grip part 10.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to an interdental brush. [Background technology]

[0002] Interdental brushes are used as auxiliary cleaning tools to clean the gaps between teeth that are difficult to reach with a toothbrush. The brush head of the interdental brush is inserted between the teeth and moved back and forth along its longitudinal axis to remove food debris and plaque. In addition to basic performance such as ease of insertion between the teeth, effective cleaning, and ease of cleaning, low irritation to the gums and a comfortable feel are also important factors for interdental brushes.

[0003] Non-wire interdental brushes, in which the brush shaft is made of hard resin and the cleaning section, which is made up of multiple bristles, is made of soft resin, irritate the gums less than wire interdental brushes that use metal wire for the shaft. However, because the shaft made of hard resin still has a certain degree of rigidity, even non-wire interdental brushes may injure the gums if they are forcibly inserted between tight teeth. Therefore, attempts have been made to develop interdental brushes that are easy to insert between teeth and provide a cleaning sensation while reducing the harmful effects and minimizing irritation to the gums.

[0004] Patent document 1 discloses an interdental brush that has a brush part in which multiple frame-shaped parts are connected along a connecting axis (longitudinal direction), and the frame-shaped parts are deformed by the insertion pressure applied to the brush part when cleaning between teeth. Patent document 2 discloses an interdental brush in which the entire brush body is housed within a cylindrical body, the bristle portion of the brush body can be freely inserted and removed from the opening of the cylindrical body, and a buffer portion is provided on the periphery of the opening of the cylindrical body. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2018-68342 [Patent Document 2] Japanese Patent Application Laid-Open No. 2012-90798 Summary of the Invention [Problem to be solved by the invention]

[0006] However, conventional interdental brushes such as those disclosed in Patent Documents 1 and 2 have room for improvement in terms of reducing harm to the gums while ensuring ease of insertion between teeth and a feeling of effective cleaning. The present invention aims to provide an interdental brush that is improved in harm to the gums while maintaining high interdental insertion property and cleaning feeling, thereby reducing pain to the gums. [Means for solving the problem]

[0007] The present invention includes the following aspects. [1] An interdental brush comprising a gripping portion and a brush portion provided at the tip of the gripping portion, An interdental brush having a mechanism that, when a load is applied to the brush portion toward the rear end, urges the brush portion toward the tip in the longitudinal direction and moves backward relative to the grip portion. [2] A brush body having a brush part and a base shaft provided at the rear end of the brush part, The grip portion includes a grip main body portion and a cylindrical guide portion provided on a tip side of the grip main body portion, The interdental brush described in [1], wherein the brush body is attached to the grip portion so that the base shaft is housed within the guide portion and the brush portion is exposed from the tip of the guide portion. [3] An elastic member is provided between the base shaft and the grip body in the guide portion, [2] An interdental brush as described in [2], wherein when a load is applied to the brush portion toward the rear end, the elastic member is elastically compressed in the longitudinal direction, causing the brush portion to be urged toward the tip in the longitudinal direction while receding relative to the grip portion. [4] At least a part of the base shaft is made of an elastic member, [2] An interdental brush as described in [2], wherein when a load is applied to the brush portion toward the rear end, the elastic member is elastically compressed in the longitudinal direction, causing the brush portion to be urged toward the tip in the longitudinal direction while receding relative to the grip portion. [5] An interdental brush as described in [3] or [4], wherein when no load is applied to the brush portion toward the rear end, a gap exists between the elastic member and the side wall of the guide portion. [6] The interdental brush according to any one of [3] to [5], wherein an opening is formed in the side wall of the guide portion at a portion inside which the elastic member is located. [Effects of the Invention]

[0008] According to the present invention, an interdental brush can be provided which maintains high interdental insertion ease and cleaning sensation while improving harm to the gums and reducing pain to the gums. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a front view showing an interdental brush according to an embodiment; [Figure 2] 2 is a cross-sectional view of the interdental brush shown in FIG. 1 along the line AA. [Figure 3] FIG. 2 is a front view showing an example of a brush part of an interdental brush. [Figure 4] 3 is a cross-sectional view showing how the brush part of the interdental brush of FIG. 2 moves back. FIG. [Figure 5] 3 is a cross-sectional view showing deformation of the elastic member at a position where an opening is formed in the guide portion when the brush portion of the interdental brush of FIG. 2 is retracted. FIG. [Figure 6] FIG. 10 is a cross-sectional view showing an interdental brush according to another example of an embodiment. [Figure 7] FIG. 7 is a cross-sectional view showing how the brush part of the interdental brush of FIG. 6 moves back. DETAILED DESCRIPTION OF THE INVENTION

[0010] An example of the interdental brush of the present invention will be described below with reference to the drawings. It should be noted that the dimensions of the drawings illustrated in the following description are merely examples, and the present invention is not necessarily limited to them, and can be appropriately modified and implemented within the scope that does not change the gist of the present invention. In the following drawings, the dimensions of the components may be shown on different scales to make each component easier to see.

[0011] FIG. 1 is a front view showing a schematic diagram of an interdental brush 1 according to an embodiment. FIG. 2 is a cross-sectional view of the interdental brush 1 of FIG. 1 taken along the line AA.

[0012] 1, the interdental brush 1 of this embodiment includes a grip portion 10 and a brush body 20. The brush body 20 is attached to the tip side of the grip portion 10. In the following description, the axial direction of the grip portion 10 is referred to as the long axis direction, and the direction perpendicular to the long axis direction is referred to as the short axis direction.

[0013] (gripping part) The grip portion 10 includes a grip body portion 11 and a cylindrical guide portion 12 provided on the tip side of the grip body portion 11. The grip body 11 is typically a columnar member, but is not limited to this. In this example, the cross-sectional shape perpendicular to the longitudinal direction of the grip body 11 is circular. However, the cross-sectional shape of the grip body 11 is not limited to a circle, and may be, for example, a rectangle.

[0014] 2, a protrusion 13 that protrudes toward the tip is provided at the tip of the grip main body 11. The cross-sectional shape of the protrusion 13 perpendicular to the longitudinal axis direction is the same as the shape of the opening on the rear end side of the guide part 12, and in this example, is circular. The guide part 12 is attached to the tip of the grip main body 11 by fitting the protrusion 13 of the grip main body 11 into the rear end part of the guide part 12.

[0015] 1, the protrusion 13 of the grip body 11 is provided with a rotation restricting portion 14 that protrudes from the side surface of the protrusion 13 and extends in the longitudinal direction. Meanwhile, the rear end of the side wall 15 of the guide 12 is formed with a notch 16 that extends in the longitudinal direction from the rear end at a position corresponding to the rotation restricting portion 14. In this example, when the guide 12 is attached to the grip body 11, the rotation restricting portion 14 fits into the notch 16, restricting the guide 12 from rotating around its axis.

[0016] In this example, the shape of the rotation restricting portion 14 and the notch 16 in front view is rectangular, but is not limited thereto. In addition, if the cross-sectional shape perpendicular to the longitudinal axis direction of the convex portion 13 of the gripping main body portion 11 and the opening shape of the rear end of the guide portion 12 are not circular, the guide portion 12 with the convex portion 13 fitted into the rear end will not rotate, so it is not necessary to provide the rotation control portion 14 and the notch 16.

[0017] 1, the guide portion 12 has a cylindrical rear end portion and a truncated conical shape whose diameter gradually decreases toward the tip. However, the shape of the guide portion 12 is not limited to this and may be, for example, a cylindrical shape, a square cylindrical shape, a hexagonal cylindrical shape, or the like.

[0018] The dimensions of the grip portion 10 are not particularly limited and can be designed as appropriate. In order to prevent hands from getting dirty when cleaning between teeth, the length L1 of the grip portion 10 in the major axis direction is preferably 25 mm or more, and more preferably 30 mm or more. In terms of operability, L1 is preferably equal to or less than 65 mm, and more preferably equal to or less than 55 mm. The lower limit and upper limit of L1 can be arbitrarily combined, and for example, 25 to 65 mm is preferable, and 30 to 55 mm is more preferable.

[0019] In order to prevent hands from getting dirty when cleaning between teeth, the length L2 of the grip body 11 in the major axis direction is preferably 15 mm or more, and more preferably 20 mm or more. In terms of operability, L2 is preferably equal to or less than 40 mm, and more preferably equal to or less than 35 mm. The lower limit and upper limit of L2 can be arbitrarily combined, and for example, 15 to 40 mm is preferable, and 20 to 35 mm is more preferable.

[0020] The material constituting the grip body 11 and the guide portion 12 is not particularly limited, and may be, for example, a hard resin. However, "hard resin" refers to a resin having a Shore A hardness of more than 50. Furthermore, "Shore A hardness" refers to the Dilometer A hardness of plastic measured in accordance with JIS K 7215 or JIS K 6253. The hard resin is not particularly limited, and examples thereof include thermoplastic resins such as polypropylene, polyethylene, ABS (acrylonitrile-butadiene-styrene) resin, polybutylene terephthalate, polycarbonate, polyethylene terephthalate, polystyrene, and polyacetal. Among these, polypropylene is preferred because of its low molding temperature and ability to improve productivity. As the hard resin, one type may be used alone, or two or more types may be used in combination.

[0021] (Brush body) As shown in FIG. 2, the brush body 20 includes a brush portion 21 and a base shaft 22 provided at the rear end of the brush portion 21. The brush part 21 is a part that is inserted between the teeth to remove food debris, plaque, and the like. 3, brush unit 21 may include a shaft 23 and a cleaning unit 25 made up of multiple bristles 24 protruding from the side of shaft 23. When viewed from the tip end of shaft 23, multiple bristles 24 constituting cleaning unit 25 protrude radially from the side of shaft 23.

[0022] In terms of reducing pain to the gums, it is preferable that the interdental brush 1 is a non-wire interdental brush in which the shaft 23 and bristles 24 of the brush head 21 are made of resin. Note that the interdental brush 1 is not limited to a non-wire interdental brush, and may be a wire interdental brush in which a metal wire is used for the shaft 23.

[0023] In the interdental brush 1, which is a non-wire interdental brush, the shaft portion 23 is made up of a shaft core and a covering portion that covers the shaft core. The material constituting the shaft core is not particularly limited, but a hard resin is preferable. The hard resin constituting the shaft core is not particularly limited, and examples thereof include the same hard resins as those exemplified as materials constituting the grip body portion 11 and the guide portion 12. The hard resin constituting the shaft core may be one type or two or more types. The resin constituting the shaft core may contain a reinforcing material such as a fibrous reinforcing material, a needle-like reinforcing material, a plate-like reinforcing material, or a granular reinforcing material in order to increase the rigidity of the shaft core.

[0024] The covering portion and the brush portion 24 are preferably made of the same material, but this is not a limitation. A soft resin is preferred as the material for the covering portion and the brush portion 24. However, "soft resin" means a resin with a Shore A hardness of 20 or more and 50 or less. The soft resin is not particularly limited, and examples thereof include elastomers such as styrene-based elastomers, olefin-based elastomers, and polyester-based elastomers, as well as silicone resins. Among these, when the shaft portion 23 is made of polypropylene, styrene-based elastomers are preferred in terms of adhesiveness. The soft resins constituting the covering portion and the brush portion 24 may be one type or two or more types.

[0025] The base shaft 22 is connected to the base end of the shaft portion 23. The base shaft 22 has the same shape as the internal shape of the tip end portion of the guide portion 12. The brush body 20 is attached to the grip portion 10 with the base shaft 22 housed within the guide portion 12 and the brush portion 21 protruding and exposed from the opening on the tip end side of the guide portion 12. In this way, the interdental brush 1 has the brush portion 21 provided at the tip end of the grip portion 10. In the interdental brush 1, the base shaft 22 is housed within the guide portion 12, and the guide portion 12 restricts unexpected movement of the brush body 20 in the minor axis direction. This improves stability when inserting the brush head 21 between the teeth.

[0026] In this example, a truncated cone-shaped base shaft 22 with tapered sides is housed in the truncated cone-shaped cylindrical tip portion of the guide portion 12. This prevents the brush body 20 from falling off the tip of the guide portion 12. Note that the configuration of the tip portion of the guide portion 12 and the base shaft 22 of the brush body 20 is not limited to this example, and for example, both the tip portion of the guide portion 12 and the base shaft 22 of the brush body 20 may have a step that reduces the size of the tip side.

[0027] 1 and 2, the tip of the guide part 12 is provided with an annular protrusion 17 that protrudes inward from the tip of the side wall 15 of the guide part 12. The maximum length of the inner opening of the annular protrusion 17 in the short axis direction is smaller than the maximum length of the tip of the base shaft 22 in the short axis direction. As a result, the base shaft 22 is caught on the annular protrusion 17, which further prevents the brush body 20 from falling off the guide part 12. If a taper or a step is formed on the tip end portion of the guide part 12 and the base shaft 22 of the brush body 20, the annular protrusion 17 does not have to be provided on the tip end portion of the guide part 12. Also, if the annular protrusion 17 is provided on the tip end portion of the guide part 12, the taper or a step does not have to be formed on the tip end portion of the guide part 12 and the base shaft 22 of the brush body 20.

[0028] 2, in the interdental brush 1 of this example, when the base shaft 22 in the guide portion 12 is positioned at the most distal end, there is a space behind the base shaft 22 of the brush body 20 in the guide portion 12. In other words, the base shaft 22 is spaced apart from the convex portion 13 of the grip main body portion 11. Therefore, the base shaft 22 moves in the longitudinal direction within the guide portion 12, and the brush portion 21 moves in the longitudinal direction relative to the grip portion 10, making the interdental brush 1 extendable and retractable.

[0029] In terms of interdental cleaning performance, the length L3 of the brush part 21 in the major axis direction is preferably 10 mm or more, and more preferably 12 mm or more. In terms of operability, L3 is preferably equal to or less than 20 mm, and more preferably equal to or less than 18 mm. The lower and upper limits of L3 can be arbitrarily combined, and for example, 10 to 20 mm is preferable, and 12 to 18 mm is more preferable.

[0030] In view of the tendency for a load to be applied to the elastic member 30 when the brush body 20 retracts, the length L4 of the base shaft 22 is preferably 10 mm or more, and more preferably 12 mm or more. In terms of operability, L4 is preferably equal to or less than 20 mm, and more preferably equal to or less than 18 mm. The lower limit and upper limit of L4 can be arbitrarily combined, and for example, 10 to 20 mm is preferable, and 12 to 18 mm is more preferable.

[0031] The material constituting the base shaft 22 is not particularly limited, but a hard resin is preferable because it makes it easier to elastically compress the elastic member 30 in the longitudinal direction. The hard resin constituting the base shaft 22 is not particularly limited, and examples thereof include the same hard resins as those exemplified as materials constituting the grip main body 11 and the guide portion 12. The resin constituting the base shaft 22 may be one type or two or more types.

[0032] (elastic member) In the interdental brush 1 of this example, the elastic member 30 is disposed in the space rearward of the base shaft 22 within the guide part 12. That is, the elastic member 30 is disposed between the base shaft 22 within the guide part 12 and the convex part 13 of the grip body part 11. As a result, as shown in Fig. 4, when the brush part 21 moves backward in the longitudinal direction relative to the grip part 10, the elastic member 30 is sandwiched between the base shaft 22 of the brush body 20 and the convex part 13 of the grip body part 11 and is elastically compressed, and the restoring force of the elastic member 30 urges the brush part 21 toward the tip. Therefore, when the load on the brush part 21 toward the rear end is released, the urging force of the elastic member 30 causes the brush part 21 to return to its original position.

[0033] In this way, the interdental brush 1 has a mechanism that, when a load toward the rear end is applied to the brush head 21, urges the brush head 21 toward the tip in the longitudinal direction while retracting relative to the gripping portion 10. As a result, when the tip of the brush head 21 accidentally hits the gums when inserting the brush head 21 between teeth, or when inserting the brush head 21 into a narrow gap, the brush head 21 retracts relative to the gripping portion 10, thereby dissipating the load applied to the brush head 21. This improves harmlessness, reduces irritation to the gums when cleaning between teeth with the interdental brush 1, and also reduces the insertion pressure between teeth. Furthermore, the retracted brush head 21 is urged toward the tip by the elastic member 30, and returns to its original position when no load toward the rear end is applied, ensuring sufficient cleaning performance and interdental insertion.

[0034] 2, when no load is applied to the brush part 21 toward the rear end, it is preferable that a gap exists between the elastic member 30 and the side wall 15 of the guide part 12. This allows the elastic member 30 to be sufficiently elastically compressed and easily deformed within the guide part 12 when a load is applied to the brush part 21 toward the rear end (ensuring an allowable space for the elastic member 30 to deform). This makes it easier for the brush part 21 to retract sufficiently, further improving the effect of reducing the insertion pressure and the effect of improving the harmfulness.

[0035] It is preferable that a gap also exists between the base shaft 22 of the brush body 20 and the elastic member 30 within the guide portion 12. For example, a gap of approximately 0.5 to 1.0 mm may be formed in the longitudinal direction between the rear end of the base shaft 22 and the elastic member 30. As a result, even if the brush head 21 accidentally comes into contact with the gums when being inserted between the teeth, the biasing force of the elastic member 30 does not act until the base shaft 22 and the elastic member 30 come into contact, further reducing irritation to the gums.

[0036] The distance L5 (FIG. 4) by which the brush head 21 retracts when a load is applied to the rear end of the brush head 21 during insertion between the teeth can be adjusted as needed. In terms of reducing the insertion pressure and improving the harmful effects, L5 is preferably 1.0 mm or more, and more preferably 1.5 mm or more. In terms of excellent operability during interdental cleaning, L5 is preferably 3.0 mm or less, and more preferably 2.5 mm or less. The lower limit and upper limit of L5 can be arbitrarily combined, and for example, 1.0 to 3.0 mm is preferable, and 1.5 to 2.5 mm is more preferable.

[0037] The distance L5 by which the brush head 21 retracts can be adjusted by the biasing force applied to the brush head 21 from the elastically compressed elastic member 30. More specifically, it can be adjusted by the material, shape, size, etc. of the elastic member 30. For example, it is preferable to adjust the distance L5 so that the brush head 21 retracts 1 mm relative to the grip portion 10 when a load of 0.4 to 0.6 N is applied to the rear end of the brush head 21.

[0038] The area of ​​the rear end face of the base shaft 22 of the brush body 20 is preferably larger than the area of ​​the tip of the elastic member 30. In other words, when the elastic member 30 is not deformed and the tip of the elastic member 30 is in contact with the rear end face of the base shaft 22 of the brush body 20, it is preferable that a gap is formed around the contact point between the base shaft 22 and the elastic member 30. This makes it easier for the elastic member 30 to be elastically compressed and deformed within the guide part 12 (because an allowable space is secured for the elastic member 30 to deform), making it easier for the brush part 21 to retract sufficiently, further improving the effects of reducing insertion pressure and improving harm prevention.

[0039] For the same reason, it is preferable that the area of ​​the tip surface of the protrusion 13 of the grip body 11 is larger than the area of ​​the rear end of the elastic member 30. In other words, it is preferable that a gap is generated around the contact point between the protrusion 13 and the elastic member 30 when the rear end of the elastic member 30 is in contact with the tip surface of the protrusion 13 of the grip body 11 without the elastic member 30 being deformed.

[0040] Gaps are formed between the elastic member 30 and the side wall 15 of the guide part 12, between the elastic member 30 and the base shaft 22 of the brush body 20, and between the elastic member 30 and the convex part 13 of the grip main body part 11, and the elastic member 30 is easily elastically compressed in the longitudinal direction, so it is preferable that the elastic member 30 is spherical. When the elastic member 30 is spherical, the areas of the leading end and the trailing end of the elastic member 30 are both zero. The shape of the elastic member 30 is not limited to a sphere, but may be, for example, a truncated cone, a truncated pyramid, a cube, a rectangular parallelepiped, or the like.

[0041] In order to ensure that the elastic member 30 is sufficiently elastically compressed and a biasing force is easily obtained, the maximum length of the elastic member 30 in the major axis direction is preferably 2.0 mm or more, and more preferably 3.0 mm or more. In order to prevent the overall length of the interdental brush 1 from becoming too long and to ensure excellent usability, the maximum length in the longitudinal direction of the elastic member 30 is preferably 6.0 mm or less, and more preferably 5.0 mm or less. The upper and lower limits of the maximum length in the longitudinal direction of the elastic member 30 can be arbitrarily combined, and for example, a range of 2.0 to 6.0 mm is preferable, and a range of 3.0 to 5.0 mm is more preferable.

[0042] The maximum length in the minor axis direction of the elastic member 30 when it is most deformed due to elastic compression caused by the load applied to the brush part 21 is preferably smaller than the maximum length in the minor axis direction at the position where the elastic member 30 is disposed in the space within the guide part 12. In other words, even when the elastic member 30 is most deformed due to elastic compression caused by the load applied to the brush part, it is preferable that the elastic member 30 does not come into contact with the side wall 15 of the guide part 12. This makes it easier for the brush part 21 to retract sufficiently, thereby making it easier to obtain the effects of reducing insertion pressure and improving harm prevention.

[0043] In order to ensure that the brush head 21 can be easily inserted between the teeth and that the brush head 21 can easily return to its original position when the load on the brush head 21 is removed, the Shore A hardness of the material constituting the elastic member 30 is preferably 0 or more, and more preferably 5 or more. In order to ensure that the brush head 21 can be sufficiently retracted and that the effects of reducing insertion pressure and improving harmfulness can be easily obtained, the Shore A hardness of the material constituting the elastic member 30 is preferably 12 or less, and more preferably 10 or less. The lower and upper limits of the Shore A hardness of the material constituting the elastic member 30 can be arbitrarily combined; for example, a range of 0 to 12 is preferable, and a range of 5 to 10 is more preferable.

[0044] The material constituting the elastic member 30 is not particularly limited, and may be, for example, a thermoplastic elastomer. Examples of thermoplastic elastomers include styrene-based and olefin-based elastomers. Among these, styrene-based elastomers are preferred because they are easily deformable and soft, and because they improve the restoring ability of the elastic member 30 when elastically compressed, thereby increasing the biasing force on the brush head 21. The materials constituting the elastic member 30 may be used alone or in combination of two or more.

[0045] 1, openings 18 are formed in the side walls 15 of the guide part 12 at portions inside which the elastic members 30 are located. As a result, in the portions where openings 18 are formed, the elastic members 30 inside the guide part 12 can deform to a position outside the inner surface 15a of the side walls 15, as shown in FIG.

[0046] Interdental brushes are generally small enough to be held between the fingers, which places a limit on the size of the guide part 12. However, by forming openings 18 in the side walls 15 of the guide part 12 as in this example, the area in which the elastic member 30 can deform can be increased even if the space in the guide part 12 for arranging the elastic member 30 is small, making it easier to sufficiently retract the brush part 21. This makes it easier to achieve the effects of reducing insertion pressure and improving harm prevention. Furthermore, if the elastic member 30 and the opening 18 are arranged in the portion of the guide part 12 that the user grips with their fingers, when a large load is applied to the brush part 21, a part of the deformed elastic member 30 will protrude outside the side wall 15 and come into contact with the user's fingers. This allows the user to feel, through their sense of touch, that the insertion pressure is increasing when the brush part is inserted between the teeth.

[0047] 1, cutout 16 is longer than rotation restricting portion 14 in the longitudinal direction, and the portion of cutout 16 above rotation restricting portion 14 forms opening 18. Note that the form in which opening 18 is formed is not limited to this form, and opening 18 may be formed independently from cutout 16. In this example, the shape of the opening 18 in front view is a rectangle that is long in the long axis direction, but is not limited thereto. For example, the shape of the opening 18 in front view may be a circle, a polygon, or the like.

[0048] There are no particular limitations on the method for manufacturing the interdental brush 1. For example, the grip portion 10 and the brush body 20 can be manufactured by a known molding method such as injection molding.

[0049] As explained above, the interdental brush 1 has a mechanism that, when a load toward the rear end is applied to the brush head 21, urges the brush head 21 toward the tip in the longitudinal direction while moving backward relative to the grip head 10. Therefore, when a load toward the rear end is applied to the brush head 21, such as when the brush head 21 accidentally hits the gums, the brush head 21 moves backward relative to the grip head 10, allowing the load to be released, thereby reducing irritation to the gums and reducing the insertion pressure between the teeth. Furthermore, in the interdental brush 1, the brush head 21 itself does not expand or contract, but rather retracts while maintaining its original shape. The resilience of the elastic member 30, which is elastically compressed as the brush head 21 retracts, urges the brush head 21 toward the tip, so when the load toward the rear end is removed, the brush head 21 moves toward the tip again. In this way, the interdental brush 1 does not need to make the brush head 21 excessively soft, and can maintain the rigidity of the brush head 21 to ensure ease of insertion between teeth and a cleaning feel, while also achieving reduced insertion pressure and reduced harm.

[0050] The interdental brush of the present invention is not limited to the interdental brush 1 described above. For example, the interdental brush of the present invention is not limited to an embodiment in which the brush head 21 is biased toward the tip by an elastic member 30 provided separately from the brush body 20, and at least a portion of the base shaft of the brush body may be made of an elastic member. Specifically, for example, the interdental brush may be the interdental brush 2 illustrated in Figure 6. The same parts in Figure 6 as those in Figure 2 are designated by the same reference numerals, and their explanation will be omitted.

[0051] As shown in FIG. 6, the interdental brush 2 is similar to the interdental brush 1 except that it includes a brush body 20A having a base shaft 22A instead of the base shaft 22. The base shaft 22A of the brush body 20A has an elastic portion 26 made of an elastic member at its tip, and a gap is formed between the side surface of the elastic portion 26 and the side wall 15 of the guide part 12. Furthermore, there is no space behind the base shaft 22A of the brush body 20A within the guide part 12, and the base shaft 22A of the brush body 20A contacts the protrusion 30 of the grip main body part 11. Other aspects of the base shaft 22A of the brush body 20A are the same as those of the base shaft 22 of the brush body 20.

[0052] As shown in Figure 7, in the interdental brush 2, when a load toward the rear end is applied to the brush head 21, the elastic portion 26 made of an elastic member of the base shaft 22A is elastically compressed in the longitudinal direction, causing the brush head 21 to retract relative to the grip portion 10, thereby reducing the insertion pressure between the teeth and reducing harmful effects. In the interdental brush 2, the brush head 21 itself does not expand or contract but retracts while maintaining its original shape. The brush head 21 is urged toward the tip by the restoring force of the elastically compressed elastic portion 26, and moves toward the tip again when the load toward the rear end is removed. In this way, the interdental brush 2 can also achieve reduced insertion pressure and reduced harmful effects while maintaining the rigidity of the brush head 21 to ensure ease of insertion between teeth and a cleaning feel.

[0053] Furthermore, in the interdental brush 2, only a portion of the base shaft is made of an elastic material, but the entire base shaft may be made of an elastic material. The interdental brush of the present invention may be an interdental brush in which the guide portion of the gripping part includes a bellows-shaped portion made of an elastic material, the brush part is directly connected to the tip of the guide portion, and the bellows-shaped portion expands and contracts, causing the brush part to move relatively backward in the longitudinal direction. In addition, within the scope of the spirit of the present invention, the components in the above-described embodiments may be replaced with well-known components as appropriate, and the above-described modifications may be combined as appropriate. [Explanation of symbols]

[0054] 1, 2...interdental brush, 10...gripping portion, 11...gripping main body portion, 12...guide portion, 13...convex portion, 14...rotation control portion, 15...side wall, 16...cutout, 17...annular protrusion, 18...opening, 20, 20A...brush body, 21...brush portion, 22, 22A...base shaft, 23...shaft portion, 24...bristle portion, 25...cleaning portion, 26...elastic portion, 30...elastic member.

Claims

1. An interdental brush comprising a gripping portion and a brush body attached to a tip side of the gripping portion, The brush body includes a brush portion and a base shaft provided at the rear end of the brush portion, The grip portion includes a grip main body portion and a cylindrical guide portion provided on a tip side of the grip main body portion, the brush body is attached to the gripping portion so that the base shaft is housed in the guide portion and the brush portion is exposed from the tip of the guide portion; an elastic member is provided between the base shaft and the grip main body in the guide portion, the material constituting the elastic member is a thermoplastic elastomer, When a load is applied to the brush portion toward the rear end, the elastic member is elastically compressed in the long axis direction and elongated in the short axis direction, so that the brush portion is biased toward the tip in the long axis direction and moves backward relatively to the grip portion, The interdental brush has a retraction distance of 1.0 to 3.0 mm.

2. 2. The interdental brush according to claim 1, wherein a gap exists between the elastic member and the side wall of the guide portion when no load is applied to the brush portion toward the rear end.

3. 3. The interdental brush according to claim 1, wherein an opening is formed in a side wall of the guide portion at a portion inside which the elastic member is located.

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