toothbrush

Abstract

To provide a toothbrush which has a hollow structure, can relieve force to be applied by a brush to a part in an oral cavity so as not to damage the part in the oral cavity of a user when cleaning teeth, and also can be manufactured by easily adjusting a degree of relief.SOLUTION: A toothbrush includes: a head member 120 constituting a head part 12 where a brush is planted on a distal end side; and a hollow member 130 connected to the head member 120, constituting a handle part to be gripped to guide the head part 12 into an oral cavity, having a hollow cylindrical shape, and to be formed of an elastic material. The hollow member 130 includes flange-like parts 17 to be projected in a flange shape in a separating direction from the center axis. The flange-like part 17 is formed to be hollow and the inner part is in communication with the inner part of the hollow cylindrical part.SELECTED DRAWING: Figure 10

Description

[Technical field]

[0001] The present invention relates to a toothbrush, and more particularly to a toothbrush having a head portion with bristles attached to the tip side, and a handle portion that is gripped to guide the head portion into the oral cavity. [Background technology]

[0002] Conventionally, there are toothbrushes with a hollow structure in which part of the shaft is formed into a hollow cylinder (Patent Document 1). Such conventional toothbrushes with a hollow structure are relatively lightweight because the hollow part is not filled with a material such as synthetic resin that forms the part other than the hollow part.

[0003] In addition, the degree of flexure of the shaft can be adjusted by changing the dimensions of the hollow portion. In other words, when the hollow portion is elongated in the longitudinal direction of the shaft, the degree of hardness when cleaning the teeth can be adjusted by changing the length of the hollow portion and its position in the longitudinal direction, and the force that the brush applies to parts of the oral cavity can be cushioned.

[0004] As a result, conventional hollow-structure toothbrushes can be used lightly, and the degree of hardness when cleaning the teeth can be adjusted, so that they can meet a variety of needs, such as the physical strength of the user and the strength with which they clean. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2015 / 137180 Summary of the Invention [Problem to be solved by the invention]

[0006] In the conventional toothbrush with a hollow structure, the hollow portion is formed in a substantially cylindrical shape and extends straight along the longitudinal direction of the toothbrush. As a result, when a shear force is applied to the toothbrush to bend the head and handle sides when applying force to the bristles, the straight portion is unlikely to withstand the shear force and is likely to bend at the point where the force is concentrated. Alternatively, if the strength is increased to prevent such bending, the force applied to the part of the oral cavity by the bristles cannot be sufficiently buffered.

[0007] In addition, when a toothbrush is bent in this way, the bent part may injure the inside of the user's mouth. Furthermore, once bent, the toothbrush cannot easily return to its original shape, making it impossible to continue using the toothbrush.

[0008] To provide a toothbrush which has a hollow structure, can cushion the force applied by the bristles to parts of the oral cavity when cleaning the teeth to an extent that does not damage the inside of the oral cavity of a user, and can be manufactured with the degree of cushioning easily adjusted. [Means for solving the problem]

[0009] (1) The present invention provides a toothbrush comprising: a head member constituting a head portion with bristles attached at the tip; and a hollow member connected to the head member constituting a handle portion which is gripped to guide the head portion into the oral cavity, the hollow member being hollow and made of an elastic material, the hollow member having a flange-like portion which protrudes in a flange-like manner in a direction away from its central axis, the flange-like portion being hollow and its interior communicating with the interior of the hollow tubular portion. Furthermore, this flange-shaped portion is formed in an approximately circular shape when viewed in the direction of the central axis, and has an approximately annular surface portion and an approximately annular back portion arranged opposite each other in the direction of the central axis so as to sandwich the interior, and at least one of the surface portion and the back portion may have an inclined surface that decreases in diameter as it moves away from the other of the surface portion and the back portion, or a convex partial spherical surface that also decreases in diameter.

[0010] That is, the toothbrush of the present invention is lightweight because it has a hollow member that constitutes the handle and the interior of the hollow member is not filled with a material such as synthetic resin, so that even users with weak grip strength, such as elderly people and young children, can easily operate the toothbrush of the present invention to clean their teeth.

[0011] In addition, since the hollow member is made of an elastic material, the handle portion that the user holds has elasticity and can cushion the force applied to the part in the oral cavity through the head portion when cleaning the teeth. Moreover, since the hollow member is elastically deformable, the handle portion absorbs the force and returns to its original shape after being deformed, so the user can continue cleaning the teeth afterwards.

[0012] Furthermore, the inside of the cylindrical portion and the inside of the flange portion are connected, and the simple internal structure does not hinder the free deformation of the flange portion. For example, when a shear force is applied to the toothbrush that bends the hollow member on the head side relative to the central axis of the toothbrush, the inner part of the flange portion that is about to bend on the head side is compressed, and the outer part that is about to bend can be stretched. As a result, when the shear force is applied, the side of the hollow member closer to the head portion than the flange portion can tilt in any direction relative to the side opposite the head portion than the flange portion. And the head member can swing freely relative to the hollow member.

[0013] The head member can be tilted in any direction, allowing the user to evenly apply the brush to each part of the oral cavity for cleaning. For example, when the head member can only be tilted in a fixed direction, only a part of the brush may be applied. In contrast, the toothbrush of the present invention can apply the entire brush in any direction or angle, providing a high cleaning effect. In addition, even if a small child or elderly person falls over while holding the head member in their mouth, the toothbrush of the present invention can absorb impacts from all directions when the toothbrush falls over because the head member can be tilted in any direction, and there is little risk of the head poking the user's throat and causing injury.

[0014] In this way, by adjusting the thickness, shape, material, and other configurations of the flange during manufacture, the degree to which the head member can freely tilt relative to the hollow member, i.e., the hardness of the entire toothbrush, can be easily adjusted. Thus, the toothbrush of the present invention can buffer the force applied by the bristles to areas inside the mouth when cleaning the teeth to an extent that does not damage the inside of the mouth of the user, and can be manufactured with the degree of buffering easily adjusted.

[0015] Furthermore, since the hollow member has an internal structure in which the inside of the tubular portion and the inside of the flange-shaped portion are connected, when the material is synthetic resin, the entire member can be molded as a single piece, and it can be produced simply and efficiently by adopting a manufacturing method such as blow molding.

[0016] (2) The head member may have an opening on the base end side, the tip of the hollow member may be inserted into the opening, and the opening edge of the opening and the flange portion of the hollow member may be adjacent to each other in the direction of the central axis.

[0017] That is, when a user presses a part of the mouth with the brush to clean the teeth, the head member transmits the reaction force received from the part to the hollow member connected to the head member. When the reaction force generates a shear force that bends the hollow member, the shear force is transmitted from the opening of the head member to the hollow member. In this case, in the toothbrush of the present invention, the opening edge of the opening and the flange of the hollow member are adjacent to each other, so that the shear force is efficiently transmitted to the flange.

[0018] The hollow member cushions the shear force by elastically deforming so that the inner part of the flange that is about to bend is crushed and the outer part that is about to bend is stretched. Since the shear force is efficiently transmitted to the flange, the hollow member can easily adjust the degree to which it cushions the shear force by adjusting the thickness, shape, material, and other configurations of the flange. Thus, the toothbrush of the present invention can cushion the force applied to parts of the oral cavity by the bristles to an extent that it does not damage the oral cavity of the user when cleaning the teeth, and can be manufactured with the degree of cushioning easily adjusted.

[0019] (3) The handle portion may have a bulging portion that bulges out in a direction away from the central axis in a portion other than the flange portion.

[0020] That is, the toothbrush of the present invention has a handle that is elastically deformable and has a bulge, so that the user can hold the thick bulge with their fingers or their fingers and palm, allowing even the elderly and small children with weak grip strength to easily support the toothbrush. Moreover, the handle is made of a hollow member, so it is soft and even users with weak grip strength can firmly hold the hollow bulge. Therefore, the toothbrush of the present invention is less likely to be dropped while cleaning the teeth.

[0021] (4) The handle portion may have a narrowed portion between the flange portion and the bulge portion that narrows in a direction approaching the central axis.

[0022] That is, since the toothbrush of the present invention has a narrowed portion, the user can place his / her fingers on the narrowed portion to stably support the toothbrush when cleaning the teeth. In particular, since the narrowed portion is provided between the flange portion and the bulging portion, the user can place the index finger on the narrowed portion and the middle finger, ring finger, etc. on the bulging portion, for example, so that the index finger can control the position, angle, etc. of the head portion while the middle finger, ring finger, etc. can securely grip the handle portion. In this way, the toothbrush of the present invention can be used to clean teeth efficiently.

[0023] (5) Furthermore, the tip of the hollow member may be fitted into the opening, and either the fitting region of the tip of the hollow member or the fitted region of the opening may have an engagement convex portion protruding in a direction away from the central axis, and the other of the fitting region or the fitted region may have an engagement concave portion recessed in the receding direction, the engagement convex portion and the engagement concave portion engaging with each other, and the head member and the hollow member may be configured to be detachably connected.

[0024] That is, since the head member and the hollow member are detachably connected, the toothbrush of the present invention allows either the head member or the hollow member to be replaced, so that, for example, one of the head member and the hollow member can be discarded and the other can be continued to be used, which is efficient and reduces the burden on the global environment.

[0025] In addition, the head member can be separated from the hollow member and then reattached to the hollow member, so that a user can remove the head member to expose the insertion area and the inserted area for cleaning, thereby allowing the toothbrush of the present invention to be kept clean at all times.

[0026] In addition, although the toothbrush of the present invention allows the head member to tilt freely relative to the hollow member, the engagement between the convex and concave engagement portions makes it unlikely that the head member will come off the hollow member, even while cleaning the teeth. This prevents accidents such as the head member getting stuck in the throat, allowing the toothbrush to be used safely.

[0027] (6) Furthermore, one of the insertion area and the inserted area may have an engaging surface arranged to face in a circumferential direction of the central axis, and the other of the insertion area and the inserted area may have an engaging surface arranged to face in the opposite direction to the engaging surface in the circumferential direction, and the engaging surface may be configured to engage the engaging surface in the circumferential direction, thereby preventing the head member and the hollow member from rotating relative to each other.

[0028] That is, the toothbrush of the present invention has an engaging surface and an engaged surface, so that the rotation of the head member about the central axis relative to the hollow member is restricted. Therefore, even though the head member is detachably attached to the hollow member, the head member does not rotate even when the user is holding the handle portion to clean the teeth. This allows the user to efficiently clean the teeth by keeping the brush in a specific direction.

[0029] (7) Furthermore, a male threaded portion may be provided on the outside of the tip of the hollow member, and a female threaded portion into which the male threaded portion can be screwed may be provided on the inside of the opening, so that the head member and the hollow member can be connected freely and detachably.

[0030] That is, since the head member and the hollow member are detachably connected, the toothbrush of the present invention allows either the head member or the hollow member to be replaced. Also, the head member can be separated from the intermediate member and then reattached to the intermediate member. Furthermore, since the toothbrush of the present invention has a male threaded portion and a female threaded portion that screw together, there is little risk of the head member coming off the hollow member, even during cleaning of teeth, for example.

[0031] (8) The flange portion may be formed in a substantially circular shape when viewed in the direction of the central axis.

[0032] That is, since the flange is substantially circular when viewed in the direction of the central axis, no linear mountain folds or valley folds are formed in the flange, and therefore the deformation direction of the structure is less restricted to a specific direction as in the case where linear mountain folds or valley folds are formed. This allows the flange to be easily deformed in various directions, and also allows it to be flexibly deformed due to the small number of corners.

[0033] Therefore, the head member of the toothbrush of the present invention can be tilted in any direction more freely, and the force applied to parts of the oral cavity can be more easily buffered.

[0034] (9) The flange-shaped portion may have a substantially annular surface portion and a substantially annular back portion arranged opposite each other in the direction of the central axis so as to sandwich the interior, and at least one of the surface portion and the back portion may have an inclined surface whose diameter decreases as it becomes more distant from the other of the surface portion and the back portion, or a convex partial spherical surface whose diameter also decreases.

[0035] In the toothbrush of the present invention, at least one of the front and rear surfaces of the flange has an inclined surface or a partially spherical convex surface, so that the side of the flange of the hollow member closer to the head portion is inclined, and the one surface and the other surface are crushed so as to approach each other. The inventors discovered that the force applied to cause the inclination becomes constant when it exceeds a certain inclination (amount of deformation). Therefore, even if a force greater than a certain force is accidentally applied to the toothbrush when cleaning the oral cavity, the toothbrush of the present invention can moderately cushion the force. Thus, depending on the structure of the toothbrush of the present invention, the degree of cushioning of the applied force can be easily adjusted by adjusting the thickness, shape, material, etc. of the flange during manufacturing. Effect of the Invention

[0036] Thus, the present invention provides a toothbrush that is lightweight, can cushion the force applied by the bristles to the parts of the oral cavity when cleaning the teeth so as not to damage the oral cavity of the user, and has a structure that allows the degree of cushioning to be adjusted over a wide range during design and manufacturing. In particular, when a guardian or caregiver operates a toothbrush to clean the teeth of an infant or a person receiving care, it is difficult for the user to understand the amount of force being applied to the oral cavity of the person. In contrast, the toothbrush of the present invention has a head member that freely swings due to the extension and contraction of the flange, so that the force applied can be fully absorbed, and is extremely effective in protecting the oral cavity of the person having their teeth cleaned.

[0037] Furthermore, when synthetic resin is used as the material for the hollow member, the amount of synthetic resin used can be reduced due to the hollow structure, making it possible to provide a toothbrush that places less strain on the global environment. [Brief description of the drawings]

[0038] [Figure 1] 1A is a front view of a toothbrush according to a first embodiment of the present invention, and FIG. [Diagram 2] 2 is a perspective view of the toothbrush of FIG. 1 disassembled into a head member and a hollow member. [Diagram 3] 2(a) to 2(c) respectively show a front view, a partial cross-sectional view of the right side and a bottom view of the head member of the toothbrush shown in FIG. [Figure 4] 2(a) to 2(c) respectively show a partial cross-sectional view of the right side of the head member of the toothbrush shown in FIG. 1, an enlarged view of the partial cross-section of the right side, and an enlarged view of an undercut portion. [Diagram 5] 2(a) to (d) respectively show a plan view, a side view, a front view and a cross-sectional view of the hollow member of the toothbrush shown in FIG. [Figure 6] 2 shows a longitudinal cross-sectional view of a hollow member of the toothbrush shown in FIG. 1. [Figure 7] 2 shows a partial right side view of a hollow member of the toothbrush shown in FIG. 1. [Figure 8] 2 shows a partial right side cross-sectional view of a head member and a partial right side view of a hollow member in a combined state of the head member and hollow member of the toothbrush shown in FIG. 1. [Figure 9] 2(a) to 2(c) are plan views showing the toothbrush shown in FIG. 1 gradually bending backwards. [Figure 10] 2(a) to 2(c) show the toothbrush shown in FIG. 1 gradually bending backwards, as viewed from the right side slightly forward. [Figure 11] 2(a) to 2(c) respectively show right side cross-sectional views of the toothbrush shown in FIG. 1 in a state in which the toothbrush is gradually bent backward. [Figure 12] (a) shows the state of the apparatus used to measure the bending strength of the toothbrush shown in Figure 1 before the measurement started, and (b) shows the state of the same apparatus after the measurement started. [Figure 13] 2 shows a right side view of the toothbrush shown in FIG. 1 during bending strength measurement. [Figure 14] 2 shows the measurement results of bending strength of the toothbrush shown in FIG. [Figure 15] FIG. 4 shows a front view of a toothbrush according to a second embodiment of the present invention. [Figure 16] 13 shows a partial front view of a toothbrush according to a third embodiment of the present invention. [Figure 17] 13(a) and (b) are a front view and a right side view, respectively, of a toothbrush according to a fourth embodiment of the present invention. [Figure 18] 18 shows a partial cross-sectional plan view of the head member and a partial plan view of the hollow member in a combined state of the head member and hollow member of the toothbrush shown in FIG. 17. [Figure 19] 2 shows a partial front view of a toothbrush according to a modified embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0039] [First embodiment] A first embodiment of the present invention will be described with reference to Figs. 1 to 14. In the front view of Fig. 1(a) and the right side view of Fig. 1(b), reference numeral 11 denotes a toothbrush. The toothbrush 11 has a head portion 12 at the tip end thereof and a handle portion 13 which is gripped in order to guide the head portion 12 into the oral cavity. Bristles 14 are attached to the head portion 12. In the drawings, the arrow U points upwards of the toothbrush 11, and the arrow D points downwards. The arrow F points forwards, and the arrow B points backwards. The arrow L points leftwards, and the arrow R points rightwards.

[0040] The central axis of the toothbrush 11 is represented by the center line of C1. The cross sections of the neck portion 12a of the head portion 12 and the cross sections near the upper and lower ends of the handle portion 13 are each formed to be approximately circular, and the central axis C1 passes through the center of each of these cross sections in the vertical direction. This neck portion 12a refers to the portion of the head portion 12 located below the bristle implantation surface 12b on which the bristles 14 are implanted. A plurality of bristle implantation holes are formed in the bristle implantation surface 12b, and a plurality of bristles 14 are implanted in the front-rear direction in each of the bristle implantation holes.

[0041] The handle portion 13 has two upper and lower bulging portions 15 that bulge away from the central axis C1, and also has two upper and lower constricted portions 16 that constrict toward the central axis C1. In this case, the upper constricted portion 16a, the upper bulging portion 15a, the lower constricted portion 16b, and the lower bulging portion 15b are arranged in this order from top to bottom. The handle portion 13 also has a flange-shaped portion 17 above the upper constricted portion 16a that protrudes like a flange away from the central axis C1.

[0042] 2 shows a perspective view of the toothbrush 11 disassembled in the top-bottom direction so that the head member 120 and the hollow member 130 are separated. The head member 120 constitutes the head section 12 when combined with the hollow member 130. The hollow member 130, which is formed in a hollow cylindrical shape, constitutes the handle section 13 when combined with the head member 120. At this time, a tip section 131 of the hollow member 130, which will be described below, is located inside the head member 120 and constitutes part of the head section 12. A central axis C2 of the head member 120 and a central axis C3 of the hollow member 130 coincide with a central axis C1 of the toothbrush 11 when they are combined.

[0043] The head member 120 and the hollow member 130 are formed separately. The head member 120 is made of various synthetic resins including thermoplastic resins such as polypropylene (PP), saturated polyester (PET), polyacetal (POM), etc., and is a molded product, for example, by injection molding. Figures 3(a), (b), and (c) respectively show a front view, a partial right side cross-sectional view, and a bottom view of the head member 120. An opening 121 that opens downward is provided on the lower bottom side of the head member 120. The opening 121 has an internal space that is approximately truncated cone-shaped and the diameter of which decreases toward the upper side. The inner peripheral portion of the internal space is called the insertion region 122. The outer periphery of the lower end of the head member 120 is formed into a circle, and forms an opening edge 123 that is the outlet of the opening 121.

[0044] FIG. 4(a) shows a partial cross-sectional view of the right side of the head member 120, similar to FIG. 3(b). FIG. 4(b) shows an enlarged view of the lower bottom side of the head member 120 in FIG. 4(a). The fitted region 122 has a substantially annular undercut portion 124 that protrudes radially inward. FIG. 4(c) shows an enlarged view of the undercut portion 124. The undercut portion 124 is provided along the entire inner circumference of the fitted region 122. By providing this undercut portion 124, the portion of the fitted region 122 above the undercut portion 124 forms an engagement recess 125 that is recessed radially outward and has a larger diameter than the innermost apex of the undercut 124.

[0045] The fitted region 122 has four locked recesses 126 that are uniformly spaced apart in the circumferential direction and recessed radially outward. Each locked recess 126 forms a generally rectangular truncated space on the inside that is wider toward the bottom. Each locked recess 126 has a clockwise locked surface 127a that is an inner wall that faces the clockwise direction CL in a plan view. Each locked recess 126 also has a counterclockwise locked surface 127b that is an inner wall that faces the counterclockwise direction UC in a plan view and faces each clockwise locked surface 127a in the circumferential direction. Thus, the fitted region 122 has four clockwise locked surfaces 127a and four counterclockwise locked surfaces 127b.

[0046] The hollow member 130 is a molded product, for example, by blow molding, made of various synthetic resins including elastic thermoplastic resins such as low-density polyethylene (LDPE) and polypropylene (PP). FIG. 5(a) shows a plan view of the hollow member 130. FIG. 5(c) shows a front view of the hollow member 130. FIG. 5(b) shows a side view of the hollow member 130 rotated 30° counterclockwise around the central axis C3 from the position shown in FIG. 5(c). FIG. 5(d) shows a cross section and a bottom view at the corresponding position in the vertical direction. The upper end of the hollow member 130 is provided with a truncated cone-shaped tip portion 131 whose diameter decreases toward the upper side. The outer peripheral portion from the tip portion 131 to the top of the flange portion 17, including the tip portion 131, is called the fitting region 132. The head member 120 and the hollow member 130 are connected and assembled by fitting the fitting region 132 into the fitted region 122. The fitting region 132 is located radially inside the opening 121 and constitutes a part of the head portion 12 when the head member 120 and the hollow member 130 are connected to each other.

[0047] 5(d) and the longitudinal sectional view of hollow member 130 in Fig. 6, hollow member 130 has a hollow structure in which the entire interior forms a single hollow space E. That is, both tip portion 131 and flange portion 17 have a hollow structure, and the hollow space of the entire cylindrical hollow member 130 communicates with the hollow spaces of tip portion 131 and flange portion 17 to form a single hollow space E.

[0048] Moreover, the hollow member 130 is formed so as to have a uniform thickness over its entirety. The thickness referred to here is represented by the symbol t in FIG.

[0049] 5(d), the cross section of the hollow member 130 has a flange portion 17 formed in a circle, an upper constricted portion 16a formed in a circle with a smaller diameter than the flange portion 17, and each of the upper and lower bulging portions 15a, 15b formed in a substantially regular hexagon with rounded apex corners. Although not shown, the lower constricted portion 16b is also formed in a substantially regular hexagon with rounded apex corners.

[0050] 7 is an enlarged partial view of the vicinity of tip portion 131 in a right side view of hollow member 130. Fitting region 132 has a step 133 formed downward around the entire circumference midway in the up-down direction. A neck-shaped portion below step 133 is called neck portion 134. Tip portion 131 located above step 133 has a diameter one step larger than neck portion 134 near the lower end, forming engagement convex portion 135 that protrudes radially outward. The diameter of neck portion 134 and the diameter of the apex located at the innermost side of undercut 124 are approximately the same.

[0051] The fitting region 132 has four locking protrusions 136 arranged at equal intervals on the outer periphery of the neck portion 134 and formed to protrude radially outward. Each locking protrusion 136 has a generally rectangular truncated shape that is wider toward the bottom, and its bottom surface is integrally formed with a surface portion 138 of the flange portion 17. The surface portion 138 will be described in detail below. Each locking protrusion 136 has a clockwise locking surface 137a, which is an outer wall facing the clockwise direction CL in a plan view. Also, each locking protrusion 136 has a counterclockwise locking surface 137b, which is an outer wall facing the counterclockwise direction UC in a plan view and faces each clockwise locking surface 137a in the circumferential direction. Therefore, the fitting region 132 is formed with four clockwise locking surfaces 137a and four counterclockwise locking surfaces 137b.

[0052] The hollow member 130 has a surface portion 138 and a back surface portion 139 that constitute the flange portion 17. The upper surface portion 138 and the lower back surface portion 139 are disposed so as to sandwich the hollow space E inside the flange portion 17 in the vertical direction, and each is formed in a substantially annular shape, and the outer peripheries of each substantially annular shape are formed to be continuous with each other in the vertical direction. Of these, the surface portion 138 has a convex partial spherical surface whose diameter decreases toward the top. In other words, the surface portion 138 has a convex partial spherical surface whose diameter decreases toward the top.

[0053] FIG. 8 shows the state in which the head member 120 and the hollow member 130 are detachably connected. The head member 120 is shown in a partial right side cross-sectional view, as in FIG. 3(b) and FIG. 4(a)(b). The hollow member 130 is shown in an outline view as seen from the right side, as in FIG. 7. To assemble the head member 120 and the hollow member 130, the tip portion 131 is fitted upward into the opening 121. At this time, the engaging convex portion 135 is elastically deformed, and the outer diameter becomes slightly smaller than the diameter of the apex located at the innermost side of the undercut 124, and passes through this apex. In this way, the fitting region 132 and the fitted region 122 come into contact with each other, and the engaging convex portion 135 and the engaging concave portion 125 are engaged with each other. In addition, since the undercut 124 is located below the step 133, the tip portion 131 is engaged upward.

[0054] When the tip 131 is fitted upward into the opening 121 in this manner, the angle of the tip 131 with respect to the opening 121 around the central axis C1 is adjusted so that the corresponding locking protrusions 136 fit into the corresponding locked recesses 126. By combining the locking protrusions 136 with the locked recesses 126, the clockwise locking surfaces 137a face the clockwise locked surfaces 127a in the circumferential direction. Also, the counterclockwise locking surfaces 137b face the counterclockwise locked surfaces 127b. As a result, the locking surfaces 137a, 137b lock the locked surfaces 127a, 127b in the circumferential direction, thereby preventing the head member 120 and the hollow member 130 from rotating relative to each other.

[0055] Conversely, to remove the hollow member 130 from the head member 120, the tip 131 is pulled downward from the opening 121. At this time, the engaging convex portion 135 also elastically deforms and its outer diameter becomes slightly smaller than the diameter of the apex located at the innermost side of the undercut 124, and passes over this apex. In this way, the fitting region 132 and the fitted region 122 are separated from each other, and the engaging convex portion 135 and the engaging concave portion 125 are disengaged from each other. As a result, the head member 120 and the hollow member 130 are configured to be connected detachably.

[0056] In a state in which the head member 120 and the hollow member 130 are connected, as shown in FIGS. 1(a), 1(b) and 8, the opening edge 123 is adjacent to the flange portion 17 in the up-down direction on the surface portion 138 side.

[0057] 9(a) to (c) show the state in which the head member 120 gradually tilts relative to the hollow member 130, as viewed from above the toothbrush 11. Fig. 9(a) shows the state before the head member 120 tilts. Figs. 9(b) and (c) show, as an example, the state in which the head member 120 tilts backward when a backward force is applied to the bristle surface 12b. When the force applied to the bristle surface 12b is released, the head member 120 returns to its original position, restoring it to the original state of Fig. 9(a).

[0058] 9(b) and 9(c), the head member 120 will tilt in that direction. The toothbrush 11 does not have a structure in which the amount of possible tilt of the head member 120 with respect to the hollow member 130 and the amount of force required to obtain that tilt differ depending on the left / right, front / back, and other directions, so the head member 120 can tilt freely in any direction of 360°.

[0059] 10(a) to (c) show a state in which the head member 120 gradually tilts relative to the hollow member 130, as viewed from the right side slightly toward the front of the toothbrush 11. Fig. 10(a) shows the state before the head member 120 tilts. Figs. 10(b) and (c) show, as an example, a state in which the head member 120 tilts when a backward force is applied to the bristle surface 12b. That is, the angle between the central axis C2 of the head member 120 and the central axis C3 of the hollow member 130 gradually increases.

[0060] As shown in Figures 10(b) and (c), as the head member 120 tilts, the hollow member 130 elastically deforms. At this time, mainly the rear portions of the front surface 138 and back surface 139 of the flange portion 17 are crushed in the vertical direction. Conversely, the front portions of the front surface 138 and back surface 139 stretch in the front-rear direction. Since the engaging convex portion 135 and the engaging concave portion 125 are engaged with each other, the hollow member 130 does not come off the head member 120. When the applied force is released, the shape of the hollow member 130 formed of an elastic material is restored, and the head member 120 returns to its original position and posture.

[0061] 11(a) to 11(c) are right side cross-sectional views showing a state in which the head member 120 is gradually tilted with respect to the hollow member 130. As shown in the figures, the fitting region 132 of the hollow member 130 fitted into the fitted region 122 of the head member 120 also tilts in accordance with the tilt of the head member 120. Accordingly, the flange portion 17 adjacent to the fitting region 132 tilts. Due to these tilts, the front surface portion 138 and the back surface portion 139 are crushed so as to approach each other at the rear side because they are sandwiched between the fitting region 132 and the upper constricted portion 16a. In addition, they stretch so as to move away from each other at the front side.

[0062] At this time, when the inclination of the head member 120 is not large, the shape of the flange portion 17 is not significantly different from the shape before deformation, so the force required to cause the front surface portion 138 and the back surface portion 139 to tilt in order to maintain their original three-dimensional structure increases with the magnitude of the inclination. However, when the inclination of the head member 120 becomes large to a certain extent, for example as in the state of FIG. 11(c), the front surface portion 139 and the back surface portion 139 are in a state of almost abutting each other, so that the original three-dimensional structure changes to a state close to a two-dimensional structure. The inventors have found that the force required to cause further inclination at this stage is constant regardless of the magnitude of the inclination.

[0063] With the above configuration, toothbrush 11 is lightweight because it includes hollow member 130 that constitutes handle portion 13 and does not fill hollow space E of hollow member 130 with a material such as synthetic resin. Therefore, even users with weak grip strength, such as elderly people and young children, can easily operate toothbrush 11 to clean their teeth.

[0064] In addition, because the hollow member 130 is made of an elastic material, the handle portion 13 held by the user has elasticity and can cushion the force applied to parts of the oral cavity through the head portion 12 when cleaning the teeth. Moreover, because the hollow member 130 is elastically deformable, the handle portion 12 absorbs the force and returns to its original shape after being deformed, allowing the user to continue cleaning the teeth thereafter.

[0065] Furthermore, since the inside of the cylindrical part of the hollow member 130 and the inside of the flange part 17 are connected, the simple internal structure does not hinder the free deformation of the flange part 17. For example, when a shear force is applied to the toothbrush 11 to bend the upper part of the hollow member 130, such as the tip part 131 and the neck part 134, with respect to the central axis C1 of the toothbrush 11, the inner part of the flange part 17 that is about to bend is compressed, and the outer part that is about to bend can be stretched. As a result, when the shear force is applied, the part of the hollow member 130 above the flange part 17 can tilt in any direction relative to the part below the flange part 17. And the head member 120 can swing freely relative to the hollow member 130.

[0066] Since the head member 120 can be tilted in any direction, the user can clean by evenly applying the bristles to each part of the oral cavity. For example, when the head member 120 can only be tilted in a fixed direction, only a part of the bristles 14 may be applied. In contrast, the toothbrush 11 has a high cleaning effect because the entire bristles 14 can be applied in any direction and angle. In addition, even if a small child or elderly person falls while holding the head part in their mouth, the head member 120 can be tilted in any direction, so that the toothbrush 11 can absorb the impact from all directions when the toothbrush falls, and there is little risk that the head part 12 will poke the user's throat and injure them.

[0067] Due to this structure, the degree to which head member 120 can be freely tilted relative to hollow member 130, i.e., the hardness of toothbrush 11 as a whole, can be easily adjusted by adjusting the thickness, shape, material, etc. of flange portion 17 during manufacture. In this way, toothbrush 11 can cushion the force applied by bristles 14 to parts of the oral cavity when cleaning the teeth to an extent that does not damage the inside of the user's oral cavity, and furthermore, the degree of cushioning can be easily adjusted when manufactured.

[0068] Furthermore, since hollow member 130 has an internal structure in which the inside of the cylindrical portion and the inside of flange portion 17 are connected, when the material is synthetic resin, the entire member can be molded as a single piece, and it can be manufactured simply and efficiently by employing a manufacturing method such as blow molding.

[0069] Next, when the user presses a part in the oral cavity with the brush 14 to clean the teeth, the head member 120 transmits the reaction force received from this part to the hollow member 130 connected to the head member 120. When the reaction force generates a shear force that bends the hollow member 130, the shear force is transmitted from the opening of the head member 120 to the hollow member 130. At this time, since the opening edge 123 and the flange portion 17 of the toothbrush 11 are adjacent to each other, the shear force is efficiently transmitted to the flange portion 17. Meanwhile, the hollow member 130 buffers the shear force by elastically deforming so that the inner part of the flange portion 17 that is about to bend is crushed and the outer part that is about to bend is stretched. And because the shear force is efficiently transmitted to the flange portion 17, the hollow member 130 can easily adjust the degree to which it buffers the shear force by adjusting the thickness, shape, material, and other configurations of the flange portion 17. In this way, the toothbrush 11 can buffer the force applied by the bristles 14 to parts of the oral cavity when cleaning the teeth to an extent that does not damage the inside of the oral cavity of the user, and can be manufactured with an easily adjustable degree of buffering.

[0070] Next, the toothbrush 11 has an elastically deformable handle portion 13 and a bulging portion 15, so that the user can hold the thick bulging portion 15 with the fingers or the fingers and palm, allowing even the elderly and small children with weak grip strength to easily support the toothbrush 11. Moreover, the handle portion 13 is made of a hollow member 130 having a hollow structure, so it is soft and even a user with weak grip strength can firmly hold the hollow bulging portion 15. Therefore, there is little risk of the toothbrush 11 dropping from the hand while cleaning the teeth.

[0071] Furthermore, since the toothbrush 11 has a narrowed portion 16, the user can place his / her fingers on the narrowed portion 16 to stably support the toothbrush 11 when cleaning the teeth. In particular, since the upper narrowed portion 16a is provided between the flange portion 17 and the upper bulging portion 15a, the user can place the index finger on the upper narrowed portion 16a and the middle finger, ring finger, etc. on the bulging portions 15a, 15b, for example, to allow the index finger to control the position, angle, etc. of the head portion 12 while the middle finger, ring finger, etc. can securely grip the handle portion 13. In this way, the toothbrush 11 can be used to clean the teeth efficiently.

[0072] Next, because the head member 120 and the hollow member 130 are detachably connected, the toothbrush 11 allows replacement of either the head member 120 or the hollow member 130. Therefore, for example, it is possible to discard only one of the head member 120 and the hollow member 130 and continue to use the other, which eliminates waste and reduces the burden on the global environment.

[0073] In addition, the head member 120 can be separated from the hollow member 130, and then reattached to the hollow member 130. Therefore, the user can remove the head member 120 to expose and wash the fitting region 132 and the fitted region 122. This allows the toothbrush 11 to be kept clean at all times.

[0074] Furthermore, since the engaging convex portion 135 and the engaging concave portion 125 of the toothbrush 11 engage with each other, there is little risk of the head member 120 coming off the hollow member 130, even during tooth cleaning, for example. This prevents accidents such as the head member 120 getting stuck in the throat, allowing the toothbrush 11 to be used with peace of mind.

[0075] Moreover, because toothbrush 11 has locking surfaces 137a, 137b and locked surfaces 127a, 127b, rotation of head member 120 about central axis C2 relative to hollow member 130 is restricted. Therefore, even though head member 120 is detachably attached to hollow member 130, head member 120 does not rotate even when a user is gripping handle portion 13 to clean teeth. This allows the user to efficiently clean teeth by keeping bristles 14 in a predetermined direction.

[0076] Finally, because the flange portion 17 is substantially circular when viewed from the direction of the central axis C3, linear mountain folds or valley folds such as those in a square, polygon, or the like are not formed in the flange portion 17. Therefore, the direction of deformation when a force is applied is not limited to a specific direction, as occurs when linear mountain folds or valley folds are formed. This allows the flange portion 17 to be easily deformed in various directions, and since it has few corners, it can be deformed flexibly.

[0077] Therefore, head member 120 of toothbrush 11 can be tilted in any direction more freely, and the force applied to parts inside the oral cavity can be more easily buffered.

[0078] In addition, since the surface portion 138 of the flange portion 17 of the toothbrush 11 has a convex partially spherical surface, the portion of the hollow member 130 above the flange portion 17 is tilted, and the surface portion 138 and the back portion 139 are crushed so as to approach each other. The inventors discovered that when the force applied to cause the tilt exceeds a certain tilt (amount of deformation), the force becomes constant. Therefore, even if a force greater than a certain force is accidentally applied to the toothbrush 11 during cleaning of the oral cavity, the toothbrush 11 can moderately cushion the force. In this way, the structure of the toothbrush 11 of the present invention makes it easy to adjust the degree of cushioning of the applied force by adjusting the thickness, shape, material, and other configurations of the flange portion 17 during manufacturing.

[0079] [Example] The inventor measured the bending strength of the toothbrush 11 of the present invention. Figures 12(a) and (b) show photographs of the device used for the measurement. The inventor prepared the toothbrush 11 without the bristles 14, and held the toothbrush 11 at one end by clamping the hollow member 130 in the vertical direction of the photograph with the clamp C so that the central axis C1 direction coincides with the horizontal direction and the bristles surface 12b faces upward. Then, using a bending strength measuring device having an indenter I at its tip, the indenter I was lowered at a speed of 100 mm per minute while being placed against the bristles surface 12b, and the load applied to the indenter I was measured. The maximum distance that the indenter I was lowered was set to 25 mm. The unit of measurement for the load was Newton (N). The photograph in Figure 12(a) shows the state before the indenter I was lowered, and the photograph in Figure 12(b) shows the state after the indenter I was lowered 25 mm.

[0080] The toothbrush 11 of the present invention used in this example has a total length L of 183.5 mm in the up-down direction as shown in Fig. 13. In response to this, the inventors set the protruding length L1, which is the distance between the upper end of the toothbrush 11 and one end of the clamp C closer to the upper end of the toothbrush 11, to 80.0 mm. The toothbrush 11 has a head length L2, which is the length of the head portion 12 from the upper end to the opening edge 123, of 71.8 mm. As a result, the handle protruding length L3, which is the protruding length of the handle portion 13, was 8.2 mm.

[0081] Furthermore, toothbrush 11 of this embodiment employs polypropylene (PP) as the material for both head member 120 and hollow member 130. The hollow structure of hollow member 130 is formed with a uniform wall thickness t as shown in Fig. 6, and has a thickness of 0.4 mm.

[0082] On the other hand, the inventors prepared a toothbrush without a hollow structure as Comparative Example 1 for comparison with this embodiment. Like the toothbrush 11 of this embodiment, the toothbrush of Comparative Example 1 was also held by clamp C so that the protruding length L1 was 80.0 mm and measured. Polypropylene (PP) was used as the material for the toothbrush of Comparative Example 1.

[0083] By lowering the indenter I, the head member 120 of the toothbrush 11 tilted backward relative to the hollow member 130. As the head member 120 tilted, the upper end of the toothbrush 11 moved backward. This backward movement distance of the upper end is called the deformation distance d, and the deformation distance d of the toothbrush 11 of this embodiment when lowered was measured. The deformation distance d of the comparative example 1 was also measured in the same manner as in this embodiment.

[0084] Graph A in Fig. 14 shows the load (N) applied to the indenter I at each deformation distance d when the indenter I is lowered at a constant speed of 100 mm / min for the toothbrush 11 of this embodiment. The horizontal axis shows the deformation distance d in mm, and the vertical axis shows the load (N). Graph B shows the load (N) applied to the indenter I at each deformation distance d for Comparative Example 1.

[0085] As shown in graph B, in the toothbrush of Comparative Example 1, the load applied to the indenter I increases almost in proportion to the deformation distance d. In contrast, as shown in graph A, in the toothbrush 11 of the present embodiment, the load increased in proportion to the deformation distance d immediately after deformation began, but thereafter remained flat even as the deformation distance d increased. In addition, the magnitude of the load itself in the toothbrush 11 of the present embodiment was smaller than that in the toothbrush of Comparative Example 1.

[0086] From these findings, the inventors discovered that toothbrush 11 applies a smaller load to indenter I in response to an external force, and therefore is able to buffer the force to a greater extent than the toothbrush of Comparative Example 1. Furthermore, the inventors discovered that as the load applied to toothbrush 11 increases to a certain extent, once a certain deformation distance d, i.e., a certain inclination, is exceeded, the deformation does not increase any further and remains at a plateau. Thus, the inventors discovered that when a certain inclination (amount of deformation) is exceeded, the force applied to cause the inclination becomes constant.

[0087] [Second embodiment] A second embodiment of the present invention will be described with reference to FIG. 15. In the front view of FIG. 15, 21 denotes a toothbrush, which has a head portion 22 at the tip end and a handle portion 23 that is gripped to guide the head portion 22 into the oral cavity. Bristles 24 are implanted in the head portion 22. The handle portion 23 has two upper and lower bulging portions 25 that bulge away from the central axis C1 of the toothbrush 21, and also has two upper and lower narrowed portions 26 that narrow toward the central axis C1. At this time, the upper narrowed portion 26a, the upper bulging portion 25a, the lower narrowed portion 26b, and the lower bulging portion 25b are arranged in this order from top to bottom. In addition, the handle portion 23 has a flange-shaped portion 27 that protrudes in a flange-like shape away from the central axis C1 above the upper narrowed portion 26a.

[0088] The head portion 22 and the handle portion 23 are composed of a head member 220 and a hollow member 230 which are formed separately. The head member 220 constitutes the head portion 22 when combined with the hollow member 230. The hollow member 230, which is formed in a hollow cylindrical shape, constitutes the handle portion 23 when combined with the head member 220. The hollow member 230 has a hollow structure in which the entire interior forms a single hollow space E.

[0089] The hollow member 230 has a surface portion 238 and a back surface portion 239 that constitute the flange portion 27. The upper surface portion 238 and the lower back surface portion 239 are disposed so as to sandwich the intermediate space E inside the flange portion 27 in the vertical direction, and each is formed in a substantially annular shape, and the outer peripheries of each substantially annular shape are formed to be continuous with each other in the vertical direction. Of these, the surface portion 238 has an inclined surface whose diameter decreases toward the top. In other words, the surface portion 238 has an inclined surface whose diameter decreases toward the top as it moves away from the back surface portion 239.

[0090] The other configurations are common to the first embodiment.

[0091] As described above, in the toothbrush 21, the surface portion 238 of the flange portion 27 has an inclined surface, so that the portion of the hollow member 230 above the flange portion 27 is inclined, and the surface portion 238 and the back portion 239 are crushed so as to approach each other, as in the case of the surface portion 138 having a convex partially spherical surface in the first embodiment. The inventors have found that when the force applied to cause the inclination exceeds a certain inclination (deformation amount), the force becomes constant. Therefore, even if a force greater than a certain force is accidentally applied to the toothbrush 21 during cleaning of the oral cavity, the toothbrush 21 can moderately cushion the force. In this way, the structure of the toothbrush 21 of the present invention makes it easy to adjust the degree of cushioning of the applied force by adjusting the thickness, shape, material, and other configurations of the flange portion 27 during manufacturing.

[0092] [Third embodiment] A third embodiment of the present invention will be described with reference to FIG. 16. In the partial front view of FIG. 16, 31 denotes a toothbrush having a head portion 32 at the tip end and a handle portion 33 to be gripped in order to guide the head portion 32 into the oral cavity. The head portion 32 is provided with bristles 34 (not shown). The handle portion 33 has two upper and lower bulging portions 35 that bulge away from the central axis C1 of the toothbrush 31, and also has two upper and lower narrowed portions 36 that narrow toward the central axis C1. Of these, only the upper narrowed portion 36a is shown. The handle portion 33 also has two upper and lower flange portions 37 that protrude in a flange-like manner away from the central axis C1 above the upper narrowed portion 36a. The upper flange portion 37a and the lower flange portion 37b are arranged in this order from top to bottom.

[0093] The hollow member 330 has a hollow structure in which the entire interior thereof forms one hollow space E. That is, the upper and lower flange portions 37a, 37b each have a hollow structure, and the hollow space of the entire cylindrical hollow member 330 communicates with each of the flange portions 37a, 37b to form one hollow space E.

[0094] The hollow member 330 has an upper surface portion 338a, an upper back surface portion 339a, a lower surface portion 338b, and a lower back surface portion 338b, which respectively constitute the flange portions 37a and 37b. In the upper and lower stages, the upper surface portions 338a and 338b and the lower back surface portions 339a and 339b are arranged to sandwich the hollow space E inside each of the flange portions 37a and 37b in the vertical direction, and each is formed in a substantially annular shape, and the outer peripheries of each substantially annular shape are formed continuously with each other in the vertical direction. Of these, each of the surface portions 338a and 338b has an inclined surface whose diameter decreases toward the top. In other words, the upper surface portion 338a has an inclined surface whose diameter decreases toward the top as it moves away from the upper back surface portion 339a. Further, the lower front surface portion 338b has an inclined surface whose diameter decreases as it gets farther away from the lower back surface portion 339b.

[0095] Furthermore, the upper back surface portion 339a has an inclined surface that tapers downwards. In other words, the upper back surface portion 339a has an inclined surface that tapers away from the upper front surface portion 338a.

[0096] The other configurations are common to the second embodiment.

[0097] As described above, since the toothbrush 31 has two-stage flanges 37a, 37b, the degree of cushioning of applied force can be adjusted over a wider range by adjusting the thickness, shape, material, etc. of each flange 37a, 37b during manufacturing, compared to a toothbrush having only one flange. Also, while Fig. 16 shows an embodiment in which the outer diameter of the upper flange 37a and the outer diameter of the lower flange 37b are substantially the same, the degree of cushioning of applied force can also be adjusted over a wider range by making the upper and lower dimensions different.

[0098] [Fourth embodiment] A fourth embodiment of the present invention will be described with reference to Fig. 17. In the front view of Fig. 17(a) and the right side view of Fig. 17(b), reference numeral 41 denotes a toothbrush. The toothbrush 41 has a head portion 42 on the tip side, and a handle portion 43 that is grasped to guide the head portion 42 into the oral cavity. Bristles 44 are attached to the head portion 42.

[0099] The toothbrush 41 is made up of an upper head member 420 and a lower hollow member 430 that are combined together. The head member 420 is combined with the hollow member 430 to form the head section 42. The hollow member 430, which is formed in a hollow cylindrical shape, is combined with the head member 420 to form the handle section 43. At this time, the tip section 431 of the hollow member 430 is located inside the head member 420 to form part of the head section 42. The central axis C2 of the head member 420 and the central axis C3 of the hollow member 430 coincide with the central axis C1 of the toothbrush 41 when they are combined together.

[0100] The head member 420 and the hollow member 430 are formed separately. FIG. 18 shows a partial cross-sectional plan view of the head member 420 and a partial plan view of the hollow member 430 at the position where the head member 420 and the hollow member 430 are combined. An opening 421 that opens downward is provided on the lower bottom side of the head member 420. The opening 421 has an upper cylindrical internal space and a lower cylindrical internal space that communicates with the upper internal space and has a larger diameter than the upper internal space. The inner peripheral portion of the internal space that combines these is called the insertion region 422. The lower end of the head member 420 has a circular outer periphery and constitutes an opening edge 423 that is the outlet of the opening 421.

[0101] The fitted region 422 has a female screw portion 425 on the inner circumferential portion of the upper internal space. The head member 420 has a screw groove 425a recessed radially outward in the female screw portion 425. The screw groove 425a forms a spiral shape around the central axis C2 of the head member 420.

[0102] The hollow member 430 has a male screw portion 435 on the outer periphery of the tip portion 431. The male screw portion 435 has a screw thread 435a that protrudes radially outward. The screw thread 435a forms a spiral around the central axis C3 of the hollow member 430. The outer periphery portion from the tip portion 431 to the top of the flange portion 47, including the tip portion 431, is called the fitting region 432. The head member 420 and the hollow member 430 are combined by screwing the female screw portion 425 and the male screw portion 435 together and fitting the fitting region 432 into the fitted region 422 to connect them together.

[0103] The other configurations are common to the first and second embodiments.

[0104] With the above configuration, the head member 420 and the hollow member 430 are detachably connected, so that the toothbrush 41 allows replacement of either the head member 420 or the hollow member 430. Also, the head member 420 can be separated from the intermediate member 430, and the head member 420 can be attached to the intermediate member 430 again. Furthermore, since the male thread portion 435 and the female thread portion 425 of the toothbrush 41 are screwed together, there is little risk that the head member 420 will come off the hollow member 430, even during cleaning of the teeth, for example.

[0105] Although the embodiments of the present invention have been described above as examples, the present invention is not limited to these embodiments, and various modifications are possible without departing from the spirit of the present invention.

[0106] For example, the material of the head member is not limited to polypropylene (PP), saturated polyester (PET), polyacetal (POM), etc., but may be any other synthetic resin or material other than synthetic resin as long as the material allows bristles to be attached and has a strength sufficient to withstand tooth brushing. Also, the head member may be formed by a manufacturing method other than injection molding.

[0107] The material of the hollow member is not limited to low density polyethylene (LDPE), polypropylene (PP), etc., but may be any other synthetic resin or material other than synthetic resin as long as it can be formed hollow, has elasticity, and has the strength to support the head member. Also, the hollow member may be formed by a manufacturing method other than blow molding.

[0108] The cross section or lower end of the head member may be formed in a shape other than a circle, and the cross section of the hollow member may be formed in a shape other than a circle or a substantially regular hexagon. The cross section of the head member may be, for example, a polygonal shape, as long as it can accommodate the joining structure with the hollow member. The cross section of the hollow member may be, for example, a polygonal shape other than a hexagon or a polygonal shape other than a regular polygon, as long as it can be easily held by the fingers and palm of the hand.

[0109] The thickness of the hollow member does not have to be uniform throughout, and may even be uneven as long as the handle portion is elastic, the head portion can tilt freely, and the toothbrush has the necessary strength.

[0110] The engagement concave portion and the engagement convex portion do not have to be a recess and a protruding portion with a larger diameter as exemplified in the first embodiment, respectively, and may be, for example, a groove-shaped engagement concave portion and a ring-shaped engagement convex portion that can fit into the groove, as long as the head member and the hollow member can be securely and detachably connected.

[0111] If the head member and the hollow member are configured to be detachably and reliably connected, even if the engagement concave portion is provided on the head member and the engagement convex portion is not provided on the hollow member, the engagement concave portion may instead be provided on the hollow member and the engagement convex portion may be provided on the head member.

[0112] Regarding the locked recess, locking protrusion, locked surface, and locking surface, the recess provided in the head member is called the locked recess and locked surface, and the protrusion provided in the hollow member is called the locking protrusion and locking surface, but these are names for convenience of distinction, and for example, the recess may be called the locking recess and locking surface, and the protrusion may be called the locked protrusion and locked surface. Furthermore, as long as the relative rotation between the head member and the rotating member can be prevented, for example, the protrusion may be provided on the head member side and the recess may be provided on the hollow member side.

[0113] The arrangement of the partial spherical surface or inclined surface in the flange-shaped portion is not limited to the examples in the first to fourth embodiments, and as long as the head member can freely swing relative to the hollow member, for example, the back surface portion may have a convex partial spherical surface that tapers downward, or the back surface portion may have an inclined surface that tapers downward. Furthermore, both the front surface portion and the back surface portion may have such a partial spherical surface or inclined surface, and moreover, either one of the front surface portion and the back surface portion may have a partial spherical surface and the other an inclined surface.

[0114] The shape of the flange in a plan view does not have to be limited to a circle, and may be, for example, an ellipse, an oval, or a polygon with rounded apexes, so long as there is little hindrance to the inclination of the head member relative to the hollow member.

[0115] The flange-shaped portion does not have to be limited to a one-stage or upper and lower two-stage configuration; it may be, for example, a three-stage or four or more-stage configuration, as long as it can absorb the force applied to a part in the oral cavity and restore itself to its original shape after being deformed.

[0116] The head portion does not have to be shaped so as to become gradually thinner towards the top, or to become gradually thinner halfway up and down as in the fourth embodiment. As long as it does not cause problems such as poor weight balance when cleaning teeth, it may be, for example, a two-stage shape in which the diameter becomes smaller halfway up, as shown in the partial plan view of Figure 19. [Industrial Applicability]

[0117] The present invention can be used in a toothbrush for cleaning a user's teeth with implanted bristles. [Explanation of symbols]

[0118] 11,21,31,41 Toothbrush 12,22,32,42 Head 13, 23, 33, 43 Handle 14,24,34,44 brush 15,25,35 Bulge 16,26,36 Neck 17,27,37,47 Flange 120,220,320,420 Head parts 121,421 Openings 122,422 Inserted area 123,423 Opening edge 124 Undercut section 125 Engagement recess 126 Locking recess 130,230,330,430 Hollow members 131,431 Tip 132,432 Insertion area 133 Step 135 Engagement convex part 136 Locking protrusion 138,238,338 Surface part 139,239,339 Back part 425 Female thread 435 Male thread

Claims

1. A head member constituting a head part in which brush bristles are attached at a tip side; a hollow member that is connected to the head member, constitutes a handle portion that is gripped to guide the head portion into the oral cavity, and is hollow and tubular and made of an elastic material; The hollow member has a flange-like portion that protrudes in a direction away from the central axis thereof, The flange-shaped portion is hollow and formed in a substantially circular shape when viewed in the central axis direction, the interior of the flange-shaped portion is in communication with the interior of the hollow cylindrical portion, and has a substantially annular front surface portion and a substantially annular back surface portion that are arranged opposite to each other so as to sandwich the interior in the central axis direction, and at least one of the front surface portion and the back surface portion has an inclined surface whose diameter decreases as it becomes farther from the other of the front surface portion and the back surface portion, or a convex partial spherical surface whose diameter also decreases. A toothbrush characterized by

2. The head member has an opening on a proximal end side, The tip of the hollow member is inserted into the opening, The opening edge of the opening and the flange portion of the hollow member are adjacent to each other in the direction of the central axis.

2. The toothbrush of claim 1.

3. The handle portion has a bulging portion that bulges away from the central axis in a portion other than the flange portion.

2. The toothbrush of claim 1.

4. The handle portion has a narrowed portion between the flange portion and the bulge portion, the narrowed portion being narrowed toward the central axis.

4. The toothbrush of claim 3.

5. The tip of the hollow member is fitted into an opening on the base end side of the head member, one of the insertion region of the tip of the hollow member and the inserted region of the opening has an engagement convex portion protruding in a direction away from the central axis, The other of the insertion region and the inserted region has an engagement recess that is recessed in the away direction, The engagement convex portion and the engagement concave portion are engaged with each other, The head member and the hollow member are configured to be detachably connected to each other.

5. The toothbrush according to claim 1, wherein the toothbrush is disposed on the surface of the tooth.

6. a locking surface provided on one of the insertion region and the inserted region so as to face in a circumferential direction of the central axis, and a locking surface provided on the other of the insertion region and the inserted region so as to face in an opposite direction to the locked surface in the circumferential direction, The engaging surface engages the engaged surface in the circumferential direction, whereby the head member and the hollow member are prevented from rotating relative to each other.

6. The toothbrush of claim 5.

7. A male screw portion is provided on the outside of the tip of the hollow member, which is the tip of the hollow member, A female screw portion into which the male screw portion can be screwed is provided on the inside of an opening on the base end side of the head member, The head member and the hollow member are configured to be detachably connected to each other.

5. The toothbrush according to claim 1, wherein the toothbrush is disposed on the surface of the tooth.

Images