JP7656912B2 - toothbrush - Google Patents

Description

The present invention relates to a toothbrush, and more specifically to a toothbrush that has a head portion with bristles attached to the tip side, and a handle portion that is grasped to guide the head portion into the oral cavity.

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 rest of the toothbrush.

In addition, the degree of bending 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.

As a result, conventional hollow toothbrushes can be used lightly, and the hardness of the brush can be adjusted when cleaning the teeth, making it possible to meet the diverse needs of users, such as their physical strength and cleaning strength.

International Publication No. WO 2015/137180

In the conventional toothbrush with a hollow structure, the hollow portion is formed in a roughly cylindrical shape and extends straight along the length of the toothbrush. As a result, when a shear force is applied to the toothbrush that bends the head and handle sides when applying force to the bristles, the straight portion has a hard time withstanding the shear force, and there is a high risk of it bending at the point where the force is concentrated. Alternatively, if the strength is increased to prevent such bending, the bristles cannot adequately cushion the force applied to parts of the oral cavity.

Furthermore, when a toothbrush bends in this way, the bent part may injure the user's mouth. Furthermore, once bent, the toothbrush does not easily return to its original shape, making it impossible to continue using the toothbrush.

The objective of the present invention is to provide a toothbrush that has a hollow structure, can cushion the force applied by the bristles to areas inside the mouth of the user when cleaning the teeth so as not to injure the inside of the mouth of the user, and can be manufactured with the degree of cushioning easily adjusted.

(1) The present invention provides a toothbrush comprising: a head member constituting a head portion with bristles attached at the tip side; and a hollow member connected to the head member and constituting a handle portion to be gripped in order 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 protruding in a flange-like manner in a direction away from the central axis, the flange-like portion being hollow and its interior communicating with the interior of the hollow cylindrical portion. The flange-like portion is formed in a substantially circular shape when viewed in the direction of the central axis, and has a substantially annular front portion and a substantially annular back portion that are arranged opposite each other in the direction of the central axis so as to sandwich the interior in the direction of the central axis, and at least one of the front portion and the back portion may have an inclined surface that decreases in diameter as it moves away from the other of the front portion and the back portion, or a convex partial spherical surface that also decreases in diameter.

In other words, the toothbrush of the present invention is lightweight because it has a hollow member that constitutes the handle and does not have the interior of the hollow member filled with a material such as synthetic resin. Therefore, even users with weak grip strength, such as elderly people and young children, can easily operate the toothbrush of the present invention and clean their teeth.

In addition, because 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 parts of the oral cavity through the head portion when cleaning the teeth. Moreover, because the hollow member is elastically deformable, the handle portion absorbs the force and returns to its original shape after it is deformed. This allows the user to continue cleaning their teeth.

Furthermore, the inside of the cylindrical portion and the inside of the flange portion are connected, and this 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 stretch. 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 either 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.

The head member can be tilted in any direction, allowing the user to evenly apply the bristles to each part of the oral cavity for cleaning. For example, if the head member can only be tilted in a fixed direction, it may be that only part of the bristles will be applied. In contrast, the toothbrush of the present invention allows the entire bristles to be applied in any direction or angle, providing a high cleaning effect. Furthermore, even if a small child or elderly person falls while still holding the head in their mouth, the toothbrush of the present invention can absorb impacts from all directions when the toothbrush falls, as 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.

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 be freely tilted relative to the hollow member, i.e., the hardness of the entire toothbrush, can be easily adjusted. In this way, the toothbrush of the present invention can cushion 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 cushioning easily adjusted.

In addition, because the hollow member has an internal structure in which the inside of the tubular portion and the inside of the flange portion are connected, when the material is synthetic resin, the entire member can be molded as a single unit, and it can be manufactured simply and efficiently by using a manufacturing method such as blow molding.

(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.

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 this part to the hollow member connected to the head member. Then, when the reaction force generates a shear force that bends the hollow member, this shear force is transmitted from the opening of the head member to the hollow member. At this time, 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.

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. In this way, the toothbrush of the present invention can cushion the force applied to parts of the oral cavity by the bristles to an extent that does not damage the inside of the user's oral cavity when cleaning the teeth, and can be manufactured with the degree of cushioning easily adjusted.

(3) The handle portion may also have a bulge portion that bulges away from the central axis in a portion other than the flange portion.

In other words, the toothbrush of the present invention has a handle that is elastically deformable and has a bulge, so that the user can grasp the thick bulge with their fingers or their fingers and palm, allowing even the elderly and young 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 grasp the hollow bulge. Therefore, there is little risk of the toothbrush of the present invention being dropped from the hand while cleaning the teeth.

(4) The handle portion may also have a narrowed portion between the flange portion and the bulge portion that narrows toward the central axis.

That is, because the toothbrush of the present invention has a narrowed portion, the user can place their fingers against this narrowed portion to stably support the toothbrush when cleaning the teeth. In particular, because the narrowed portion is provided between the flange-shaped portion and the bulging portion, the user can, for example, place their index finger against the narrowed portion and their middle and ring fingers against the bulging portion, allowing the index finger to control the position, angle, etc. of the head portion while the middle and ring fingers can securely grip the handle portion. In this way, the toothbrush of the present invention can be used to clean teeth efficiently.

(5) 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 engaging convex portion that protrudes away from the central axis, and the other of the fitting region and the fitted region may have an engaging concave portion that is recessed in the receding direction, and the engaging convex portion and the engaging concave portion may be engaged with each other, and the head member and the hollow member may be connected in a detachable manner.

In other words, because 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. Therefore, for example, it is possible to discard only one of the head member and the hollow member and continue to use the other, which eliminates waste and reduces the burden on the global environment.

The head member can be separated from the hollow member and then reattached to the hollow member. This allows the user to remove the head member to expose the insertion area and the inserted area for cleaning. This allows the toothbrush of the present invention to be kept clean at all times.

In addition, although the toothbrush of the present invention allows the head member to tilt in any direction relative to the hollow member, the engagement convex portion and the engagement concave portion engage with each other, so there is little risk of the head member coming off the hollow member, even while cleaning the teeth. This prevents accidents such as the head member getting stuck in the throat, making it safe to use.

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

In other words, the toothbrush of the present invention has an engaging surface and an engaged surface, so that the rotation of the head member around 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 and cleaning their teeth. This allows the user to clean their teeth efficiently by keeping the brush bristles in a specified direction.

(7) In addition, 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 in a detachable manner.

In other words, because the head member and 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 the head member can be reattached to the intermediate member. Furthermore, because the toothbrush of the present invention has a male threaded portion and a female threaded portion that thread together, there is little risk of the head member coming off the hollow member, even while cleaning the teeth, for example.

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

In other words, because the flange is substantially circular when viewed in the direction of the central axis, no linear mountain or valley folds are formed in the flange. Therefore, the deformation direction of the structure is less restricted to a specific direction, as occurs when linear mountain or valley folds are formed. This allows the flange to be easily deformed in various directions, and because it has few corners, it can be deformed flexibly.

As a result, 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 cushioned.

(9) The flange portion may have a substantially annular surface portion and a substantially annular back surface portion that are 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 surface portion may have an inclined surface that decreases in diameter as it moves away from the other of the surface portion and the back surface portion, or a convex partial spherical surface that also decreases in diameter.

The toothbrush of the present invention has at least one of the front and back surfaces of the flange having an inclined surface or a partially spherical convex surface, so that the side of the hollow member closer to the head of the flange tilts 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 tilt becomes constant once it exceeds a certain tilt (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 adequately 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.

In this way, the present invention can provide a toothbrush that is lightweight, can cushion the force that the bristles apply to parts of the mouth when cleaning the teeth so as not to damage the inside of the user's mouth, 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 uses a toothbrush to clean the teeth of an infant or care recipient, it is difficult for the user to tell how much force is being applied to the mouth 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 it can fully absorb the applied force and is extremely effective in protecting the mouth of the person having their teeth cleaned.

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.

1A shows a front view of a toothbrush according to a first embodiment of the present invention, and FIG. 1B shows a right side view of the same toothbrush. 2 is a perspective view of the toothbrush of FIG. 1 disassembled into a head member and a hollow member. 2A to 2C are a front view, a partial right side cross-sectional view, and a bottom view, respectively, of the head member of the toothbrush shown in FIG. 1. 2A to 2C are 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 right side cross-section, and an enlarged view of an undercut portion, respectively. 2A to 2D are a plan view, a side view, a front view and a cross-sectional view, respectively, of the hollow member of the toothbrush shown in FIG. 2 shows a longitudinal cross-sectional view of the hollow member of the toothbrush shown in FIG. 1 . 2 shows a partial right side view of a hollow member of the toothbrush shown in FIG. 1 . 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 . 2(a) to 2(c) show in plan view the toothbrush shown in FIG. 1 gradually bending backwards. 2A to 2C show the toothbrush shown in FIG. 1 gradually bending backward, as viewed from the right side slightly forward. 2A to 2C are right side cross-sectional views of the toothbrush shown in FIG. 1 as it gradually bends backwards. 1A shows the state of the apparatus used to measure the bending strength of the toothbrush shown in FIG. 1 before the measurement was started, and FIG. 1B shows the state of the same apparatus after the measurement was started. FIG. 2 is a right side view of the toothbrush shown in FIG. 1 during measurement of bending strength. 2 shows the measurement results of the bending strength of the toothbrush shown in FIG. 2 shows a front view of a toothbrush according to a second embodiment of the present invention; 13 shows a partial front view of a toothbrush according to a third embodiment of the present invention. 13A and 13B are a front view and a right side view, respectively, of a toothbrush according to a fourth embodiment of the present invention. 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. 2 shows a partial front view of a toothbrush according to a modified embodiment of the present invention.

[First embodiment]
A first embodiment of the present invention will be described with reference to Figures 1 to 14. In the front view of Figure 1(a) and the right side view of Figure 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 figures, 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.

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 number of bristle implantation holes are drilled in the bristle implantation surface 12b, and a number of bristles 14 are implanted in the front-to-rear direction in each of the bristle implantation holes.

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 from top to bottom. In addition, the handle portion 13 has a flange-shaped portion 17 above the upper constricted portion 16a that protrudes like a flange away from the central axis C1.

Figure 2 shows a perspective view of the toothbrush 11 disassembled vertically so that the head member 120 and hollow member 130 are separated. The head member 120 is combined with the hollow member 130 to form the head section 12. The hollow member 130, which is formed in a hollow cylindrical shape, is combined with the head member 120 to form the handle section 13. At this time, the tip portion 131 of the hollow member 130, which will be described below, is located inside the head member 120 and forms part of the head section 12. The central axis C2 of the head member 120 and the central axis C3 of the hollow member 130 coincide with the central axis C1 of the toothbrush 11 when they are combined.

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), and polyacetal (POM), and is, for example, a molded product formed 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 in a circular shape, and forms an opening edge 123 that is the outlet of the opening 121.

Figure 4(a) shows a partial cross-sectional view of the right side of the head member 120, similar to Figure 3(b). Figure 4(b) shows an enlarged view of the lower bottom side of the head member 120 in Figure 4(a). The fitted region 122 has a substantially annular undercut portion 124 that protrudes radially inward. Figure 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.

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

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). Figure 5(a) shows a plan view of the hollow member 130. Figure 5(c) shows a front view of the hollow member 130. Figure 5(b) shows a side view of the hollow member 130 rotated 30° counterclockwise around the central axis C3 from the position shown in Figure 5(c). Figure 5(d) shows a cross section and a bottom surface 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 top. 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 insertion 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. When the head member 120 and the hollow member 130 are connected, the fitting region 132 is located radially inside the opening 121 and forms part of the head portion 12.

As shown in the cross-sectional views of FIG. 5(d) and the longitudinal cross-sectional view of the hollow member 130 in FIG. 6, the hollow member 130 has a hollow structure in which the entire interior forms a single hollow space E. In other words, both the tip portion 131 and the flange portion 17 have a hollow structure, and the hollow space of the entire cylindrical hollow member 130 communicates with the hollow spaces of the tip portion 131 and the flange portion 17 to form a single hollow space E.

The hollow member 130 is also formed so that its thickness is uniform throughout. The thickness referred to here is represented by the symbol t in FIG. 6.

As shown in the cross-sectional views of FIG. 5(d), the cross section of the hollow member 130 has a flange portion 17 formed in a circle, the upper constricted portion 16a formed in a circle with a smaller diameter than the flange portion 17, and 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.

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

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

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 arranged to sandwich the hollow space E inside the flange portion 17 in the vertical direction, and each is formed in a substantially annular shape, with the outer peripheries of each substantially annular shape being 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 the further it is from the back surface portion 139.

Figure 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 Figures 3(b) and 4(a) and (b). The hollow member 130 is shown in an outline viewable from the right side, as in Figure 7. To assemble the head member 120 and the hollow member 130, the tip 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 engage with each other. In addition, since the undercut 124 is located below the step 133, the tip 131 is engaged upward.

When the tip 131 is inserted 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, preventing the head member 120 and the hollow member 130 from rotating relative to each other.

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 as it passes through this apex. In this way, the insertion area 132 and the inserted area 122 are separated, and the engaging convex portion 135 and the engaging concave portion 125 are disengaged. As a result, the head member 120 and the hollow member 130 are configured to be connected in a detachable manner.

When the head member 120 and hollow member 130 are connected, as shown in Figures 1(a) and 1(b) and 8, the opening edge 123 is adjacent to the flange portion 17 in the vertical direction on the surface portion 138 side.

Figures 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. Figure 9(a) shows the state before the head member 120 tilts. Figures 9(b) and (c) show, as an example, the state in which the head member 120 tilts backwards 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 Figure 9(a).

Even if a force is applied to the head portion 12 in a direction other than backward, the head member 120 will tilt in that direction, as in Figures 9(b) and (c). The toothbrush 11 does not have a structure in which the amount of possible tilt of the head member 120 relative to the hollow member 130 and the amount of force required to achieve that tilt differ depending on the left/right or front/back direction, so the head member 120 can tilt freely in any direction, 360° left/right and front/back.

Figures 10(a) to (c) show the 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. Figure 10(a) shows the state before the head member 120 tilts. Figures 10(b) and (c) show, as an example, the state in which the head member 120 tilts when a backward force is applied to the bristle surface 12b. In other words, the angle between the central axis C2 of the head member 120 and the central axis C3 of the hollow member 130 gradually increases.

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

Figures 11(a) to (c) are right side cross-sectional views showing the state in which the head member 120 gradually tilts relative to the hollow member 130. As shown in the figure, as the head member 120 tilts, the fitting region 132 of the hollow member 130 that fits into the fitting region 122 of the head member 120 also tilts. Accordingly, the flange-shaped portion 17 adjacent to the fitting region 132 tilts. Due to these tilts, the front portion 138 and the back portion 139 are crushed so that they 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 that they move away from each other at the front side.

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 relatively large, for example as in the state shown in FIG. 11(c), the front surface portion 139 and the back surface portion 139 are in a state of approximately abutment, so that the original three-dimensional structure changes to a state closer to a two-dimensional structure. The inventors have discovered that the force required to cause further tilt at this stage is constant regardless of the magnitude of the inclination.

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

In addition, because the hollow member 130 is made of an elastic material, the handle portion 13 that the user holds 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 it is deformed. This allows the user to continue cleaning their teeth afterwards.

Furthermore, because the inside of the cylindrical part of the hollow member 130 and the inside of the flange part 17 are connected, these simple internal structures do 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, relative 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.

The head member 120 can be tilted in any direction, allowing the user to evenly apply the bristles to each part of the oral cavity for cleaning. For example, if the head member 120 can only be tilted in a fixed direction, it may happen that only part of the bristles 14 will be applied. In contrast, the toothbrush 11 allows the entire bristles 14 to be applied in any direction or angle, providing a high cleaning effect. Also, even if a small child or elderly person falls while still holding the head member in their mouth, the head member 120 can be tilted in any direction, allowing the toothbrush 11 to cushion the impact from all directions when the toothbrush falls, reducing the risk of the head member 12 poking and injuring the user's throat.

Because of this structure, the degree to which the head member 120 can be freely tilted relative to the hollow member 130, i.e., the hardness of the entire toothbrush 11, can be easily adjusted by adjusting the thickness, shape, material, and other configurations of the flange portion 17 during production. In this way, the toothbrush 11 can cushion the force that the bristles 14 apply 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 the degree of cushioning can be easily adjusted when produced.

In addition, because the hollow member 130 has an internal structure in which the inside of the cylindrical portion and the inside of the flange portion 17 are connected, when the material is synthetic resin, the entire member can be molded as a single unit, and it can be manufactured simply and efficiently by using a manufacturing method such as blow molding.

Next, when the user presses a part in the mouth 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, this 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 that the bristles 14 apply 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.

Next, because the toothbrush 11 has an elastically deformable handle portion 13 and a bulge portion 15, the user can grasp the thick bulge portion 15 with their fingers or their fingers and palm, allowing even the elderly and small children with weak grip strength to easily support the toothbrush 11. Furthermore, because the handle portion 13 is made of a hollow member 130 having a hollow structure, it is soft, and even users with weak grip strength can firmly grasp the hollow bulge portion 15. Therefore, there is little risk of the toothbrush 11 dropping from the hand while cleaning the teeth.

In addition, because the toothbrush 11 has a narrowed portion 16, the user can place their fingers against the narrowed portion 16 to stably support the toothbrush 11 when cleaning the teeth. In particular, because the upper narrowed portion 16a is provided between the flange portion 17 and the upper bulging portion 15a, the user can, for example, place their index finger against the upper narrowed portion 16a and their middle and ring fingers against the bulging portions 15a and 15b, allowing the index finger to control the position, angle, etc. of the head portion 12 while the middle and ring fingers can securely grip the handle portion 13. In this way, the toothbrush 11 can be used to clean the teeth efficiently.

Secondly, because the head member 120 and the hollow member 130 are detachably connected, either the head member 120 or the hollow member 130 of the toothbrush 11 can be replaced. 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.

In addition, the head member 120 can be separated from the hollow member 130 and then reattached to the hollow member 130. This allows the user to remove the head member 120 to expose the insertion area 132 and the inserted area 122 for cleaning. This allows the toothbrush 11 to be kept clean at all times.

Furthermore, because 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 while cleaning the teeth, for example. This prevents accidents such as the head member 120 getting stuck in the throat, allowing for safe use.

In addition, because the toothbrush 11 has the engaging surfaces 137a, 137b and the engaged surfaces 127a, 127b, the rotation of the head member 120 about the central axis C2 relative to the hollow member 130 is restricted. Therefore, even though the head member 120 is detachably attached to the hollow member 130, the head member 120 does not rotate even when the user is holding the handle portion 13 to clean the teeth. This allows the user to efficiently clean the teeth by keeping the orientation of the bristles 14 in a specified direction.

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 force is applied is less likely to be limited to a specific direction, as is the case when linear mountain folds or valley folds are formed. This allows the flange portion 17 to easily deform in various directions, and because it has few corners, it can deform flexibly.

This allows the head member 120 of the toothbrush 11 to tilt in any direction, and also makes it easier to cushion the forces acting on areas in the oral cavity.

And because 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 tilts, causing the surface portion 138 and the back portion 139 to collapse closer together. 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 when cleaning the oral cavity, the toothbrush 11 can adequately 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 manufacture.

[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 in a cantilever manner 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 the 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 distance that the indenter I was lowered was set to a maximum of 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.

The toothbrush 11 of the present invention used in this example has a total length L in the vertical direction shown in Figure 13 of 183.5 mm. In response to this, the inventors set the protruding length L1, which is the distance between the top end of the toothbrush 11 and the end of the clamp C closest to the top 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 top end to the opening edge 123, of 71.8 mm. As a result, the handle portion protruding length L3, which is the protruding length of the handle portion 13, was 8.2 mm.

In addition, the toothbrush 11 of this embodiment uses polypropylene (PP) as the material for both the head member 120 and the hollow member 130. The hollow structure of the hollow member 130 is formed with a uniform wall thickness t as shown in Figure 6, and has a thickness of 0.4 mm.

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

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. The distance that the upper end moved backward was called the deformation distance d, and the deformation distance d of the toothbrush 11 of this embodiment when it was lowered was measured. The deformation distance d of the comparative example 1 was also measured in the same manner as in this embodiment.

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.

As shown in graph B, in the toothbrush of Comparative Example 1, the load applied to the indenter I increases almost proportionally as the deformation distance d increases. In contrast, as shown in graph A, in the toothbrush 11 of this embodiment, the load increases in proportion to the deformation distance d immediately after deformation begins, but thereafter the load does not increase and remains flat even if the deformation distance d increases. Furthermore, the magnitude of the load itself in the toothbrush 11 of this embodiment is smaller than that in the toothbrush of Comparative Example 1.

The inventors found that toothbrush 11 applies a small 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. They also found 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 load does not increase any further and remains at a plateau. In this way, they found that when a certain inclination (amount of deformation) is exceeded, the force applied to cause that inclination becomes constant.

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.

The head section 22 and the handle section 23 are composed of a head member 220 and a hollow member 230, which are formed separately. The head member 220 constitutes the head section 22 when combined with the hollow member 230. The hollow member 230, which is formed in a hollow cylindrical shape, constitutes the handle section 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.

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 arranged 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 the further it is from the back surface portion 239.

The rest of the configuration is the same as in the first embodiment.

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 discovered that when the force applied to cause the inclination exceeds a certain inclination (amount of deformation), 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 appropriately 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, etc. of the flange portion 27 during manufacturing.

[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 order from top to bottom.

The hollow member 330 has a hollow structure in which the entire interior forms a single hollow space E. In other words, the upper and lower flanges 37a and 37b each have a hollow structure, and the hollow space of the entire cylindrical hollow member 330 communicates with each flange 37a and 37b to form a single hollow space E.

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 each of 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 an approximately annular shape, and the outer peripheries of each approximately 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 as it moves away from the upper back surface portion 339a. Additionally, the lower surface portion 338b has an inclined surface that narrows in diameter as it moves away from the lower back surface portion 339b.

Furthermore, the upper back surface portion 339a has an inclined surface that narrows in diameter as it goes downward. In other words, the upper back surface portion 339a has an inclined surface that narrows in diameter as it goes away from the upper front surface portion 338a.

The rest of the configuration is the same as in the second embodiment.

As described above, since the toothbrush 31 has two-stage flanges 37a, 37b, the degree of cushioning of applied forces can be adjusted over a wider range than when it has only a single-stage flange by adjusting the thickness, shape, material, and other configurations of the flanges 37a, 37b during manufacture. 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 approximately the same, it is also possible to adjust the degree of cushioning of applied forces over a wider range by making the dimensions of the top and bottom different.

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

The toothbrush 41 is made up of an upper head member 420 and a lower hollow member 430. 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 431 of the hollow member 430 is located inside the head member 420 and forms 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.

The head member 420 and the hollow member 430 are formed separately. Figure 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 base 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 area 422. The lower end of the head member 420 has a circular outer periphery and forms an opening edge 423 that is the outlet of the opening 421.

The insertion region 422 has a female thread portion 425 on the inner periphery of the upper internal space. In the female thread portion 425, the head member 420 has a screw groove 425a that is recessed radially outward. The screw groove 425a forms a spiral shape around the central axis C2 of the head member 420.

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

The rest of the configuration is the same as the first or second embodiment.

With the above configuration, the head member 420 and the hollow member 430 are detachably connected, so that either the head member 420 or the hollow member 430 of the toothbrush 41 can be replaced. In addition, the head member 420 can be separated from the intermediate member 430, and the head member 420 can be reattached to the intermediate member 430. Furthermore, since the male threaded portion 435 and the female threaded portion 425 of the toothbrush 41 are screwed together, there is little risk of the head member 420 coming off the hollow member 430, even during tooth cleaning, for example.

The above are examples of embodiments of the present invention, but the present invention is not limited to these embodiments, and various modifications are possible without departing from the spirit of the present invention.

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, so long as the material can accommodate bristles and is strong enough to withstand tooth brushing. Also, the head member may be formed by a manufacturing method other than injection molding.

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. It may also be formed by a manufacturing method other than blow molding.

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, polygonal, so long as it can accommodate the joining structure with the hollow member. The cross section of the hollow member may be, for example, polygonal, other than a hexagon, or polygonal, other than a regular polygon, so long as it can be easily gripped by the fingers and palm.

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

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. As long as the head member and the hollow member can be securely and detachably connected, the engagement concave portion may be, for example, groove-shaped and the engagement convex portion may be ring-shaped so that it can fit into the groove.

If the head member and hollow member are configured to be removably and securely connected, even if the engaging concave portion is provided on the head member and the engaging convex portion is not provided on the hollow member, the engaging concave portion may be provided on the hollow member and the engaging convex portion may be provided on the head member.

Regarding the locked recessed portion, the locking protruding portion, the locked surface, and the locking surface, the recessed portion provided on the head member is called the locked recessed portion and the locked surface, and the protruding portion provided on the hollow member is called the locking protruding portion and the locking surface, but these are names used for convenience to distinguish them, and for example, the recessed portion may be called the locking recessed portion and the locking surface, and the protruding portion may be called the locked protruding portion and the locked surface. Furthermore, if it is possible to prevent the relative rotation between the head member and the rotating member, for example, the protruding portion may be provided on the head member side and the recessed portion may be provided on the hollow member side.

The arrangement of the partial spherical surfaces or inclined surfaces 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 narrows toward the bottom, or the back surface portion may have an inclined surface that narrows toward the bottom. Furthermore, both the front surface portion and the back surface portion may have these partial spherical surfaces or inclined surfaces, and moreover, one of the front surface portion and the back surface portion may have a partial spherical surface and the other an inclined surface.

The shape of the flange in 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 tilt of the head member relative to the hollow member.

The flange does not have to be limited to a one-stage or two-stage configuration, but may be, for example, three-stage or four-stage or more, as long as it can absorb the force applied to the oral cavity and restore itself to its original shape after being deformed.

The head does not have to be shaped so that it tapers gradually towards the top, or so that it tapers gradually from the middle in the vertical direction as in the fourth embodiment. As long as it does not cause problems with the balance of weight when cleaning teeth, it may be shaped in two stages, with the diameter decreasing partway down, as shown in the partial plan view of Figure 19, for example.

The present invention can be used in toothbrushes that clean the user's teeth with implanted bristles.

11, 21, 31, 41 Toothbrush 12, 22, 32, 42 Head portion 13, 23, 33, 43 Handle portion 14, 24, 34, 44 Brush 15, 25, 35 Bulging portion 16, 26, 36 Narrowed portion 17, 27, 37, 47 Flange-shaped portion 120, 220, 320, 420 Head member 121, 421 Opening 122, 422 Inserted region 123, 423 Opening edge 124 Undercut portion 125 Engaging recessed portion 126 Engaged recessed portion 130, 230, 330, 430 Hollow member 131, 431 Tip portion 132, 432 Insertion region 133 Step 135 Engaging convex portion 136 Engaging convex portion 138, 238, 338 Surface portion 139, 239, 339 Back surface portion 425 Female thread portion 435 Male thread portion

Claims (7)

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
The head member has an opening on a proximal end side,
The tip of the hollow member is inserted into the opening,
2. The toothbrush according to claim 1, wherein an opening edge of the opening and a flange portion of the hollow member are adjacent to each other in the direction of the central axis.
2. The toothbrush according to claim 1 , wherein the handle portion has a bulging portion that bulges away from the central axis in a portion other than the flange portion.
4. The toothbrush according to claim 3, wherein the handle portion has a narrowed portion between the flange portion and the bulging portion, the narrowed portion being narrowed in a direction approaching the central axis.
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,
5. The toothbrush according to claim 1 , wherein the head member and the hollow member are configured to be detachably connected to each other.
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 toothbrush according to claim 5, wherein the head member and the hollow member are prevented from rotating relative to each other by the engaging surface engaging the engaged surface in the circumferential direction.
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 ,
5. The toothbrush according to claim 1 , wherein the head member and the hollow member are configured to be detachably connected to each other.

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