toothbrush

Abstract

To provide a toothbrush which is easily operated by a user and hardly hurts the gums of the user while cushioning external force in falling, and reduces a use amount of materials such as synthetic resins because of a cavity in the inside for a lower load on a global environment.SOLUTION: A toothbrush includes a head member 120 where a head part 12 in which a brush 14 is planted is formed and a hollow member 130 which constitutes a handle part 13 that is connected to the head member and is held to guide the head part into an oral cavity, is a hollow cylindrical shape, and is formed of an elastic material. The hollow member is a shade-like shape in which a central line coincides with a central axis of the cylindrical shape when the hollow member is not deformed, has a plurality of annular shade-like parts, and is configured that the central line of at least one of the shade-like parts inclines relative to the central axis when the hollow member is deformed.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a toothbrush. More specifically, it relates to a toothbrush having a head portion where bristles are implanted and a handle portion that is gripped to guide the head portion into the oral cavity.

Background Art

[0002] Conventionally, there is a toothbrush in which a part of the head portion and the handle portion are formed of a soft resin (Patent Document 1). Since a part of this conventional toothbrush is formed of a soft resin, for example, even when a user such as an infant falls while holding the toothbrush in the mouth, the soft resin deforms to buffer the external force applied from the floor and suppress damage to the user's oral cavity.

[0003] Also, inside the soft portion formed of the soft resin, there is a core-shaped hard portion formed of a hard resin and extending in the longitudinal direction of the toothbrush. This hard portion is formed so that the longitudinal direction of the cross section is a rectangle that coincides with the bristle implantation direction. Therefore, such a conventional toothbrush having the hard portion inside can transmit the force in the bristle implantation direction for brushing teeth to the maximum extent through the hard portion, and is easy to bend in a direction perpendicular to the longitudinal direction and perpendicular to the bristle implantation direction, so it can兼备 the brushing ability for teeth and the safety when falling.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The aforementioned conventional toothbrushes are made of soft and hard resins, so their mass is roughly the same as a typical toothbrush made entirely of hard resin. With such solid toothbrushes, it is difficult to reduce the weight, and they can be difficult to use for users with insufficient grip strength, such as infants and the elderly.

[0006] Furthermore, because the force from the user's fingers is transmitted to the maximum extent in the direction of the bristles, just like with a regular toothbrush made entirely of hard resin, there is a risk that the brush may injure the user's gums if too much force is applied.

[0007] Therefore, the present invention aims to provide a toothbrush that cushions external forces during falls, is easy for the user to operate, and is less likely to injure the user's gums. [Means for solving the problem]

[0008] (1) The present invention provides a toothbrush comprising a head member on which a head portion into which a brush is implanted is formed, and a hollow member connected to the head member and constituting a handle portion for gripping in order to guide the head portion into the oral cavity, the hollow member being hollow cylindrical and made of an elastic material, wherein the hollow member has a plurality of conical and annular cap-shaped portions, each having a center line that coincides with the central axis of the cylindrical portion when not deformed, and the first conical portion and the second conical portion which is inclined in the opposite direction to the first conical portion in the direction of each center line are adjacent in the direction of each center line, and are configured to deform so that the center line of at least one of the conical portions is inclined with respect to the central axis. Furthermore, the device comprises a head member on which a head portion into which a brush is implanted is formed, and a hollow member connected to the head member and constituting a handle portion that is held to guide the head portion into the oral cavity, the hollow member being hollow and cylindrical, and integrally formed as a whole from an elastic material, wherein the hollow member has a plurality of conical and annular cap-shaped portions, each having a center line that coincides with the central axis of the cylinder when not deformed, and the first conical portion and the second conical portion that is inclined in the opposite direction to the first conical portion in each center line direction are adjacent in each center line direction, and are configured to deform so that the center line of at least one conical portion is inclined with respect to the central axis, the tip of the connecting portion with the head member is frustoconical in shape, with the diameter decreasing towards the tip end, and the tip portion including the tip end has a hollow structure, and the head member may have an internal space that is substantially frustoconical in shape, with the opening of the connecting portion decreasing towards the back end. Furthermore, the hollow member has a plurality of conical and annular cap-shaped portions, each having a center line that coincides with the central axis of the cylindrical shape when not deformed, and a first conical portion and a second conical portion that is inclined in the opposite direction to the first conical portion in each center line direction are adjacent in each center line direction and are configured such that, upon deformation, the center line of at least one conical portion is inclined with respect to the central axis, the tip of the connecting portion with the head member is frustoconical in shape, decreasing in diameter towards the tip, the tip portion including the tip has a hollow structure, and has a step extending downward around the entire circumference in the middle of the central axis direction of the cylindrical shape, and the head member may have an internal space that is substantially frustoconical in shape, decreasing in diameter towards the back, and a substantially annular undercut portion that protrudes radially inward around the entire circumference of the internal space.

[0009] In other words, the toothbrush of the present invention has a hollow member formed of an elastic material, in which a first cap-shaped portion and a second cap-shaped portion facing the opposite direction from the first cap-shaped portion are adjacent. As a result, the hollow member deforms, and these cap-shaped portions expand and contract in the longitudinal direction of the toothbrush, or bend relative to the central axis, thereby cushioning the external force applied when the toothbrush falls over.

[0010] Furthermore, by incorporating a hollow, cylindrical component, the toothbrush has an internal cavity, resulting in a lighter overall mass. This makes it easy to use even for users with insufficient grip strength, such as infants and the elderly.

[0011] Furthermore, because the hollow member has an annular cap-shaped portion, when the toothbrush deforms, this hollow member can deform in any direction perpendicular to the longitudinal direction of the toothbrush. In this way, the toothbrush of the present invention can bend in any direction, so it can cushion external forces applied in any direction when it falls over, and the force of the user is distributed so that the brush is less likely to injure the gums.

[0012] (2) The hollow member may also be formed by molding a synthetic resin.

[0013] In other words, because the hollow component is made of synthetic resin, the manufacturer can heat and melt the raw resin, then cool it and mold it into the desired shape. It is known that the mechanical properties, such as hardness, may differ depending on the type of synthetic resin. Furthermore, by increasing or decreasing the wall thickness before cooling, the wall thickness of the hollow component after molding can be varied. As a result, by changing the material or wall thickness, the manufacturer can obtain toothbrushes with altered characteristics such as the degree of cushioning against external forces during tipping, the amount of mass, and the amount of pressure applied to the user's gums. Consequently, it is possible to provide an optimal toothbrush that suits the user's needs.

[0014] (3) The hollow member may also have a bellows structure in which the plurality of cap-shaped portions are arranged in a bellows-like manner.

[0015] In other words, because multiple cap-shaped sections, each of which deforms, overlap in a bellows-like manner, the length that the entire hollow member can deform increases as the number of overlapping cap-shaped sections increases. Similarly, the curvature angle of the entire hollow member also increases. As a result, the toothbrush of the present invention can absorb greater external forces. Furthermore, it distributes the user's force more evenly, making it less likely for the brush to injure the gums.

[0016] Furthermore, since the deformation and curvature of the entire bellows structure are shared by each elastically deformable cap-shaped section, each individual cap-shaped section is less prone to plastic deformation. Therefore, the toothbrush of the present invention continues to elastically deform despite repeated use, providing long-lasting cushioning against external forces in the event of a fall and minimizing damage to the user's gums.

[0017] (4) The hollow member may also have a gripping portion on the base end side in the direction of the central axis, and the bellows structure on the tip side of the gripping portion.

[0018] In other words, since the gripping portion of the hollow member is located on the base end side of the bellows structure, the user does not need to touch the bellows structure with their fingers when using the toothbrush. Therefore, the toothbrush of the present invention does not interfere with the expansion and contraction and bending of the bellows structure during use, can reliably absorb external forces in the event of a fall, and is less likely to injure the user's gums.

[0019] (5) Furthermore, the cap-shaped portion located at the very tip and the cap-shaped portion adjacent thereto combine to form a flange-shaped tip-side flange portion, and the tip-side flange portion may have a diameter greater than the length of the head portion in the direction perpendicular to its longitudinal direction. Furthermore, the first cap-shaped portion and the second cap-shaped portion are combined to form a flange-shaped tip portion, and the tip portion may have a larger diameter than the length of the head portion in the direction perpendicular to its longitudinal direction.

[0020] In other words, the toothbrush of the present invention has a tip-side flange-like portion on the proximal end side of the head member, and this tip-side flange-like portion has a larger diameter than the head portion on which the bristles are attached. Therefore, when the user inserts the head portion into the oral cavity to brush their teeth with the bristles, the tip-side flange-like portion is likely to come into contact with the user's front teeth, making it difficult for the portion on the proximal end side of the tip-side flange-like portion to enter the oral cavity.

[0021] As a result, even when only the head portion of the toothbrush of the present invention enters the oral cavity, it is difficult for the other portions to enter the oral cavity. Therefore, even if the toothbrush falls during use and the proximal end of the toothbrush hits the floor or the like, the portions other than the head portion do not enter the oral cavity, so that the occurrence of an accident of damaging the oral cavity by the tip of the toothbrush can be reduced. This is particularly effective for infants with a small oral cavity entrance.

[0022] (6) Further, the hollow member may have portions where the wall thickness varies depending on the circumferential position in at least a part of the bellows structure in the central axis direction.

[0023] That is, a part or all of the hollow member has a non-uniform wall thickness structure in which a part of the wall thickness in the circumferential direction of the central axis is larger than a part of the non-uniform wall thickness. Therefore, the hollow member has a large resistance to bending at a position around the central axis with a thick wall, and conversely, has a small resistance to bending at a position around the central axis with a thin wall. Therefore, the toothbrush of the present invention allows the manufacturer to change the angle at which it can be bent relatively easily depending on the bending direction, or the force that must be applied to bend it to a certain angle. As a result, the manufacturer can change the degree of buffering of the external force when the manufactured toothbrush falls, the degree of absorption of the force applied to the gums, etc. depending on the bending direction, and can provide an optimal toothbrush suitable for the user's circumstances.

[0024] (7) Further, the plurality of bristles may be implanted in the head member such that each bristle forms a radial shape in the view in the central axis direction.

[0025] That is, since the toothbrush of the present invention can be curved and deformed in any direction orthogonal to the longitudinal direction, it can absorb the user's force in any direction. On the other hand, each bristle is implanted in any direction. Therefore, when the user brushes teeth using the bristles implanted in any direction, the toothbrush of the present invention absorbs the force in that direction, so that the user's force is always dispersed and it is difficult for the bristles to damage the gums.

[0026] (8) Further, the cap-shaped portion may have a rib protruding in a direction away from the central axis and extending in a direction parallel to the central axis direction.

[0027] That is, since the rib protrudes from the cap-shaped portion, the hollow member is difficult to bend in the direction in which the rib is provided. Thereby, the manufacturer can manufacture a toothbrush in which the hollow member is difficult to bend in a specific direction by protruding the rib. Therefore, by changing the ease of bending depending on the direction, it is possible to provide an optimal toothbrush suitable for the user's circumstances.

Effect of the Invention

[0028] Thus, in the present invention, it is possible to provide a toothbrush that buffers an external force during a fall, is easy for the user to operate, and is difficult to damage the user's gums. Further, in solving these problems, it is possible to provide an optimal toothbrush suitable for characteristics such as the user's age, physical strength, behavior pattern, etc., toothbrush usage conditions, preferences, and the like. Furthermore, since the inside of the hollow member is hollow, the amount of material such as synthetic resin can be reduced, and a toothbrush with a low load on the global environment can be provided.

Brief Description of the Drawings

[0029] [Figure 1] (a) represents a front view of a toothbrush according to a first embodiment of the present invention. (b) Similarly represents a right side view of the toothbrush. [Figure 2] Represents a perspective view of the toothbrush of FIG. 1 in a state of being disassembled into a head member and a hollow member. [Figure 3] (a) to (c) show the front view, right side section section, and bottom view of the toothbrush head component shown in Figure 1, respectively. [Figure 4] (a) to (c) show a cross-sectional view of the right side portion of the toothbrush head member shown in Figure 1, an enlarged view of the right side portion of the cross-section, and an enlarged view of the undercut portion, respectively. [Figure 5] (a) to (d) show the plan view, side view, front view, and cross-sectional end view of the hollow toothbrush component shown in Figure 1, respectively. [Figure 6] Figure 5(a) shows a cross-sectional view of the hollow member along line AA. [Figure 7] Figure 6 shows a partially enlarged cross-sectional view of the section along line AA. [Figure 8] (a)(b) These figures show end views of the partially enlarged section shown in Figure 7. [Figure 9] Figure 1 shows a partial right side view of the hollow component of the toothbrush. [Figure 10] Figure 1 shows a partial right-side cross-sectional view of the head member and a partial right-side view of the hollow member when the head member and hollow member of the toothbrush are combined. [Figure 11] (a)(b)Figures 1 and 1 show the toothbrush before and after it is bent backward, in a plan view. [Figure 12] (a)(b)Figure 1 shows the toothbrush before and after it bends backward, viewed from a slightly forward, right-side perspective. [Figure 13] (a)(b) These figures show a front view and a right side view of a toothbrush according to a second embodiment of the present invention, respectively. [Figure 14] Figure 13 shows a perspective view of the toothbrush disassembled into a head component and a hollow component. [Figure 15] (a) to (d) show the plan view, side view, front view, cross-sectional end view, and bottom view of the hollow toothbrush component shown in Figure 13, respectively. [Figure 16] Figure 13 shows a partial right side view of the hollow component of the toothbrush. [Figure 17]Figure 13 shows a partial right-side cross-sectional view of the head member and a partial right-side view of the hollow member in the combined state of the toothbrush head member and hollow member. [Figure 18] (a)~(c) Figures 13 show the toothbrush gradually bending backward, viewed from a slightly forward, right-side perspective. [Figure 19] (a) to (c) show the right side cross-sectional view of the toothbrush as it gradually bends backward, as shown in Figure 13. [Figure 20] (a)(b) These figures show a front view and a right side view of a toothbrush according to a third embodiment of the present invention, respectively. [Figure 21] (a)(b) The figures show a plan view and a front view of a toothbrush according to a fourth embodiment of the present invention, respectively. [Figure 22] (a) to (c) show the left side view, cross-sectional end view, and plan view of a toothbrush according to the fifth embodiment of the present invention, respectively. [Figure 23] (a) to (c) show a front view, a right side view, and a cross-sectional end view of a toothbrush according to the fifth embodiment of the present invention, respectively. [Figure 24] (a) to (c) show the left side view, cross-sectional end view, and plan view of a toothbrush according to the sixth embodiment of the present invention, respectively. [Figure 25] (a)(b) Shows a right side view and a cross-sectional end view of a toothbrush according to the sixth embodiment of the present invention, respectively. [Figure 26] This figure shows a partial plan cross-sectional view of the head member and a partial plan view of the hollow member in a state in which the head member and hollow member of a toothbrush are combined according to a modified embodiment of the present invention. [Figure 27] This shows a partial front view of a toothbrush according to a modified embodiment of the present invention. [Modes for carrying out the invention]

[0030] [First Embodiment] A first embodiment of the present invention will be described with reference to Figures 1 to 12. In the front view of Figure 1(a) and the right side view of Figure 1(b), 11 is a toothbrush. The toothbrush 11 has a head portion 12 at the tip and a handle portion 13 at the base that is held to guide the head portion 12 into the oral cavity. Brushes 14 are embedded in the head portion 12. In the figures, the direction of arrow U indicates the upward direction of the toothbrush 11, and the direction of arrow D indicates the downward direction. The direction of arrow L indicates the left, and the direction of arrow R indicates the right. Also, the direction of arrow F indicates the forward direction, and the direction of arrow B indicates the rear.

[0031] The central axis of the toothbrush 11 is represented by the symbol C1. The cross-section 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 in a substantially circular shape, and the central axis C1 passes through the center of each of these cross-sections in the vertical direction. The neck portion 12a refers to the part of the head portion 12 that is located below the bristle surface 12b on which the brush bristles 14 are implanted. Multiple bristle holes are drilled in the bristle surface 12b. Multiple brush bristles 14 are implanted in the bristle surface 12b so that they are located on the front side of the head portion 12, for each bristle hole.

[0032] The handle portion 13 has a bellows section 15 on its upper, tip side, and a gripping portion 16 on its lower, base side for the user to grasp the toothbrush 11 with their fingers. The bellows section 15 has a plurality of flange-like portions 17, 18 that protrude in a flange-like manner away from the central axis C1. Of these flange-like portions 17, 18, the flange-like portion on the tip side is called the tip-side flange-like portion 17, and the flange-like portion adjacent to the base end side of the tip-side flange-like portion 17 is called the base-side flange-like portion 18.

[0033] Figure 2 shows a perspective view of the toothbrush 11 disassembled vertically so that the head member 120 and the hollow member 130 are separated. The head member 120, when combined with the hollow member 130, constitutes the head portion 12. The hollow member 130, which is formed in a hollow cylindrical shape, constitutes the handle portion 13 when combined with the head member 120. At this time, the tip portion 131 of the hollow member 130, as described below, is located inside the head member 120 and constitutes part of the head portion 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.

[0034] The head member 120 and the hollow member 130 are formed separately. The head member 120 is a molded product, for example, by injection molding, made from various synthetic resins including thermoplastic resins such as polypropylene (PP), saturated polyester (PET), and polyacetal (POM). Figures 3(a), 3(b), and 3(c) show the front view, the right side partial cross-sectional view, and the bottom view of the head member 120, respectively. An opening 121 that opens downwards is provided on the lower bottom side of the head member 120. The opening 121 has an internal space that is roughly frustoconical in shape, with the diameter decreasing towards the top. The inner circumference of this internal space is called the fitted area 122. The lower end of the head member 120 has a circular outer circumference and constitutes the opening edge 123, which is the exit of the opening 121.

[0035] Figure 4(a) shows a cross-sectional view of the right side portion 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 as seen 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 around 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 a retractable recessed portion 125 that is radially outward recessed and has a larger diameter than the innermost apex of the undercut 124.

[0036] Furthermore, the fitted region 122 has four locking recesses 126 that are arranged at uniform intervals in the circumferential direction and are formed to be recessed radially outward. Each locking recess 126 forms a roughly rectangular truncated space on the inside, which is wider towards the bottom. Each locking recess 126 has a clockwise locking surface 127a, which is the inner wall facing the clockwise direction CL in a plan view. It also has a counterclockwise locking surface 127b, which is the inner wall facing the counterclockwise direction UC in a plan view and is opposite to each clockwise locking surface 127a in the circumferential direction. Thus, the entire fitted region 122 has four clockwise locking surfaces 127a and four counterclockwise locking surfaces 127b.

[0037] The hollow member 130 is a molded product, for example, by blow molding, made from various synthetic resins including elastic thermoplastic resins such as low-density polyethylene (LDPE) and polypropylene (PP). The entire piece is molded as a single unit. Figure 5(c) shows a front view of the hollow member 130. Figures 5(a) and 5(b) show a plan view and a side view of the hollow member 130 rotated 45° counterclockwise around the central axis C3 from the position shown in Figure 5(c), respectively. Figure 5(d) shows the end faces of the cross-sections at corresponding vertical positions in Figures 5(b) and 5(c). The upper end of the hollow member 130 is provided with a frustoconical tip 131 that decreases in diameter towards the top. The outer circumference portion from the tip 131 to the uppermost part of the flange portion 17, including the tip 131, is called the fitting region 132. The head member 120 and the hollow member 130 are connected and assembled by the insertion area 132 being inserted into the insertion area 122. With the head member 120 and the hollow member 130 connected, the insertion area 132 is located radially inward of the opening 121 and constitutes a part of the head portion 12.

[0038] In Figures 5(b) and (d), the peak of the tip flange portion 17 that is formed furthest outward from the central axis C3 is called the tip peak portion 17a, and the peak of the base flange portion 18 that is formed furthest outward from the central axis C3 is called the base peak portion 18a. The tip peak portion 17a and the base peak portion 18a have the same inner diameter and the same outer diameter. The bottom of the valley located between the tip flange portion 17 and the base flange portion 18, and formed furthest inward towards the central axis C3, is called the tip valley portion 17b, and the bottom of the valley located at the lowest side of the bellows portion 15, and formed furthest inward towards the central axis C3, is called the base valley portion 18b. The gripping portion 16 is continuous below the base valley portion 18b. The tip-side valley 17b and the base-side valley 18b have the same inner diameter and the same outer diameter. Each peak 17a, 18a is formed such that both its inner diameter and outer diameter are larger than those of each valley 17b, 18b. However, each peak 17a, 18a may have different inner diameters and different outer diameters, as long as this does not interfere with the curvature of the entire hollow member 130 as described below. Similarly, each valley 17b, 18b may have different inner diameters and different outer diameters.

[0039] As shown in the cross-sectional views of Figure 5(d) and the longitudinal section of the hollow member 130 in Figure 6, the hollow member 130 has a hollow structure in which the entire interior forms a single hollow space E. Figure 6 is a cross-sectional view of the hollow member 130 along line AA as seen from line AA shown in Figure 5(a). That is, the tip portion including the tip portion 131, the bellows portion 15, and the gripping portion 16 all have a hollow structure, and the hollow space of the entire cylindrical hollow member 130 and the hollow spaces of the tip portion 131 and the ridge portions 17a and 17b described below are connected to form a single hollow space E.

[0040] Furthermore, the hollow member 130 is formed so that its wall thickness is substantially uniform throughout. Here, the wall thickness is represented by the symbol t in Figure 6. Note that the wall thickness t of the hollow member 130 does not have to be substantially uniform as long as it can maintain the overall strength of the hollow member 130 and does not interfere with the curvature described below.

[0041] As shown in Figure 6, when viewed from the inside, each valley 17b, 18b is convex in the hollow space E, moving toward the central axis C3. Conversely, each peak 17a, 18a is concave in the hollow space E, moving away from the central axis C3.

[0042] The cross-sections of the hollow member 130 are all formed in a circular shape, as shown in the cross-sectional views of Figure 5(d).

[0043] Figure 7 shows a magnified section of the longitudinal cross-section of the hollow member 130 shown in Figure 6, specifically a section near the tip. The hollow member 130 is conical and has multiple annular conical sections 161, 171, 172, 181, and 182. The centerlines of each conical section 161, 171, 172, 181, and 182 coincide with the central axis C3 of the hollow member 130. The multiple conical sections 161, 171, 172, 181, and 182 are arranged from the tip side in the order of the first conical section 171, the second conical section 172, the third conical section 181, the fourth conical section 182, and the fifth conical section 161.

[0044] The first cap-shaped portion 171 and the second cap-shaped portion 172 form the upper and lower parts of the tip-side flange-shaped portion 17, respectively, with the tip-side peak 17a serving as the vertical boundary. The third cap-shaped portion 181 and the fourth cap-shaped portion 182 form the upper and lower parts of the rear-side flange-shaped portion 18, respectively, with the base-side peak 18a serving as the vertical boundary. The fifth cap-shaped portion 161 is located at the most base end of the bellows portion 15 and occupies the portion where the diameter narrows from the tip-side edge of the circumferential surface of the gripping portion 16 toward the tip and approaching the central axis C3. The tip-side valley 17b forms the boundary between the second cap-shaped portion 172 and the third cap-shaped portion 181, and the base-side valley 18b forms the boundary between the fourth cap-shaped portion 182 and the fifth cap-shaped portion 161. As described above, the first to fifth cap-shaped sections 171, 172, 181, 182, and 161 are continuous in the vertical direction at the tip-side crest section 17a, the tip-side valley section 17b, the base-side crest section 18a, and the base-side valley section 18b.

[0045] Furthermore, the first cap-shaped portion 171, the third cap-shaped portion 181, and the fifth cap-shaped portion 161 are inclined so that their diameter increases towards the base end. Conversely, the second cap-shaped portion 172 and the fourth cap-shaped portion 182 are inclined so that their diameter increases towards the tip end.

[0046] In this way, the first cap-shaped portion 171 and the second cap-shaped portion 172, which is inclined in the opposite direction to the first cap-shaped portion 171, are adjacent to each other in the direction of the centerline. Similarly, the second cap-shaped portion 172 and the third cap-shaped portion 181, which is inclined in the opposite direction to the second cap-shaped portion 172, the third cap-shaped portion 181 and the fourth cap-shaped portion 182, which is inclined in the opposite direction to the third cap-shaped portion 181, and the fourth cap-shaped portion 182 and the fifth cap-shaped portion 161, which is inclined in the opposite direction to the fourth cap-shaped portion 182, are adjacent to each other. As a result, a bellows section 15 of a bellows structure is formed in which multiple cap-shaped portions 161, 171, 172, 181, and 182 are arranged in a bellows-like manner.

[0047] Figures 8(a) and 8(b) show the partially enlarged end faces of the hollow member 130 in a longitudinal cross-section when the user grips the handle portion 16 of the handle portion 13 and applies a rightward force to the head portion 12 to bend the toothbrush 11. The centerlines of each cap-shaped portion 161, 171, 172, 181, and 182 are denoted by the symbols C161, C171, C172, C181, and C182, respectively. These partially enlarged end faces are similarly shown when the toothbrush 11 is bent in directions other than to the right. Figure 8(a) shows the enlarged end face when a slight rightward force is applied from the state shown in Figure 7, where no force is applied. Figure 8(b) shows the enlarged end face when a further rightward force is applied from the state shown in Figure 8(a). As shown in each figure, the center line C131 of the frustoconical tip portion 131 is tilted to the right as it approaches the tip, relative to the original central axis C3 of the hollow member 130. At the same time, the center lines C161, C171, C172, C181, C182 of some or all of the cap-shaped portions 161, 171, 172, 181, 182 are also tilted to the right as they approach the original central axis C3, with the upper part being positioned to the right.

[0048] Furthermore, the inventors conducted deformation tests using prototypes and found that, under the right conditions, as shown in Figures 8(a) and (b), the hollow member 130 curves due to elastic deformation, where the gaps between the pair of conical sections 172 and 181 that sandwich the valley sections 17b and 18b in the direction of the central axis C, and the other pair of conical sections 182 and 161, widen or narrow, respectively. Subsequently, the hollow member 130 also curves due to elastic deformation, where the gaps between the pair of conical sections 171 and 172 that similarly sandwich the peak sections 17a and 18a, and the other pair of conical sections 181 and 182, widen or narrow. Moreover, the inventors found that in this case, the hollow member 130 curves gradually as the respective pairs of conical sections, either from the tip to the base, undergo elastic deformation, either from the tip to the base of each valley section 17b and 18b or from each peak section 17a and 18a.

[0049] At this point, focusing on the right side of the longitudinal cross-section of each conical section 171, 172, 181, 182, and 161, first, the right region 172r of the second conical section 172 and the right region 181r of the third conical section 181 come into contact or nearly come into contact. Next, the right region 182r of the fourth conical section 182 and the right region 161r of the fifth conical section 161 come into contact or nearly come into contact. After these, the right region 171r of the first conical section 171 and the right region 172r of the second conical section approach each other. Finally, the right region 181r of the third conical section and the right region 182r of the fourth conical section approach each other.

[0050] Similarly, focusing on the left side of the longitudinal cross-section of each cone-shaped section 171, 172, 181, 182, and 161, first, the left region 172l of the second cone-shaped section 172 and the left region 181l of the third cone-shaped section 181 separate. Next, the left region 182l of the fourth cone-shaped section 182 and the left region 161l of the fifth cone-shaped section 161 separate. After these, the left region 171l of the first cone-shaped section 171 and the left region 172l of the second cone-shaped section separate. Finally, the left region 181l of the third cone-shaped section and the left region 182l of the fourth cone-shaped section separate.

[0051] Note that Figures 8(a) and 8(b) show the state within the elastic deformation range and do not show the state where plastic deformation occurs beyond the elastic deformation range.

[0052] Thus, if the deformation pattern of the bellows section 15 follows a regular pattern, the user can predict when the plastic deformation of the bellows section 15 will begin. This allows the user to avoid plastic deformation of the hollow member 130 and use the toothbrush 11 for as long as possible.

[0053] Figure 9 shows an enlarged partial view of the vicinity of the tip portion 131 in the right side view of the hollow member 130. The fitting region 132 has a step 133 that is formed along the entire circumference and downwards midway in the vertical direction. The neck-like portion below this step 133 is called the neck portion 134. The tip portion 131, located above the step 133, has a diameter one step larger than the neck portion 134 near its lower end and forms an engaging convex portion 135 that protrudes radially outward. The diameter of the neck portion 134 and the diameter of the innermost apex of the undercut 124 are approximately the same.

[0054] Furthermore, the insertion region 132 has four locking protrusions 136 that are arranged at uniform intervals around the outer circumference of the neck portion 134 and are formed to protrude radially outward. Each locking protrusion 136 has a roughly square truncated base shape that is wider towards the bottom, and its bottom surface is integrally formed with the first cap-shaped portion 171 of the tip-side flange-shaped portion 17. Each locking protrusion 136 has a clockwise locking surface 137a, which is the outer wall facing clockwise CL in a plan view. It also has a counterclockwise locking surface 137b, which is the outer wall facing counterclockwise UC in a plan view and is opposite to each clockwise locking surface 137a in the circumferential direction. Thus, the entire insertion region 132 is formed with four clockwise locking surfaces 137a and four counterclockwise locking surfaces 137b.

[0055] Figure 10 shows the state in which the head member 120 and the hollow member 130 are detachably connected. A partial right side cross-sectional view of the head member 120 is shown, similar to Figures 3(b) and 4(a)(b). The outline of the hollow member 130 as seen from the right side is shown, similar to Figure 9. To assemble the head member 120 and the hollow member 130, the tip portion 131 is inserted upward into the opening 121. At this time, the engaging convex portion 135 elastically deforms so that its outer diameter becomes slightly smaller than the diameter of the innermost apex of the undercut 124, and it passes over this apex. In this way, the insertion area 132 and the insertion area 122 come into contact, and the engaging convex portion 135 and the engaging concave portion 125 engage. Also, since the undercut 124 is located below the step 133, it locks the tip portion 131 upward.

[0056] When inserting the tip portion 131 upward into the opening 121 in this manner, the angle of the tip portion 131 with respect to the opening 121 around the central axis C3 is adjusted so that the corresponding locking projection 136 fits into each locking recess 126. As each locking projection 136 is combined with each locking recess 126, each clockwise locking surface 137a faces each other clockwise locking surface 127a in the circumferential direction. Similarly, each counterclockwise locking surface 137b faces each counterclockwise locking surface 127b. In this way, each locking surface 137a, 137b locks each other locking surfaces 127a, 127b in the circumferential direction, thereby preventing the head member 120 and the hollow member 130 from rotating relative to each other.

[0057] Conversely, to remove the hollow member 130 from the head member 120, the tip portion 131 is pulled downward through 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 innermost apex of the undercut 124, allowing it to pass over this apex. In this way, the insertion region 132 and the insertion region 122 are separated, and the engaging convex portion 135 and the engaging concave portion 125 engage and disengage. Through these actions, the head member 120 and the hollow member 130 are configured to be detachably connected.

[0058] When the head member 120 and the hollow member 130 are connected, as shown in Figure 10, the opening edge 123 is adjacent in the vertical direction to the first cap-shaped portion 171 of the tip side flange-shaped portion 17.

[0059] Figures 11(a) and 11(b) show the state in which the head member 120 is tilted relative to the hollow member 130, as viewed from the plane of the toothbrush 11. Figure 11(a) shows the state before the toothbrush 11 bends and the head member 120 tilts. Figure 11(b) shows the state in which the head member 120 tilts backward when a backward force is applied to the bristle surface 12b, as an example. When the force applied to the bristle surface 12b is released, the head member 120 returns to its original position and restores to the original state shown in Figure 11(a).

[0060] Furthermore, even when a force is applied to the head portion 12 in a direction other than backward, the head member 120 tilts in that direction, similar to Figure 11(b). The toothbrush 11 of this embodiment does not have a structure in which the possible degree of tilt of the head member 120 relative to the hollow member 130 and the degree of force required to obtain that tilt differ depending on the left, right, front, and back directions, so that the head member 120 can tilt freely in all 360° directions.

[0061] Figures 12(a) and 12(b) show views of the toothbrush 11 from the right side near the front, before and after the head member 120 tilts relative to the hollow member 130. Figure 12(a) shows the state before the head member 120 tilts. Figure 12(b) shows the state when the head member 120 tilts, as an example, when a backward force is applied to the bristle surface 12b. That is, as the head 120 tilts, the angle between the central axis C2 of the head member 120 and the central axis C3 of the hollow member 130 before deformation gradually increases.

[0062] As shown in Figure 12(b), as the head member 120 tilts, the hollow member 130 deforms elastically. At this time, mainly the rear portion of the bellows section 15 is compressed in the vertical direction. Conversely, the front portion of the bellows section 15 stretches in the vertical direction. Then, when the force causing the head member 120 to tilt is released, the shape of the hollow member 130, which is formed by the elastic material, is restored, and the head member 120 returns to its original position and orientation.

[0063] Furthermore, the toothbrush 11 not only tilts, but the bellows section 15 also elastically deforms when the head member 120 is compressed or pulled in the vertical direction, causing it to contract or extend in the vertical direction. As a result, the toothbrush 11 can absorb vertical impact forces and restore itself to its original shape.

[0064] In this invention, the first conical portion 171 and the second conical portion 172 may be referred to as the "first conical portion" and the "second conical portion," respectively. Alternatively, the second conical portion 172 and the third conical portion 181 may be referred to as the "first conical portion" and the "second conical portion," respectively. Alternatively, the third conical portion 181 and the fourth conical portion 182 may be referred to as the "first conical portion" and the "second conical portion," respectively. Alternatively, the fourth conical portion 182 and the fifth conical portion 161 may be referred to as the "first conical portion" and the "second conical portion," respectively. As shown in each figure, the "first cap-shaped part" and the "second cap-shaped part" are inclined in opposite directions along their respective centerlines C161, C171, C172, C181, and C182. Furthermore, the "first cap-shaped part" and the "second cap-shaped part" are adjacent to each other along their respective centerlines C161, C171, C172, C181, and C182.

[0065] With the above configuration, the toothbrush 11 of the present invention has a hollow member 130 formed of an elastic material, in which one cone-shaped portion and another cone-shaped portion facing the opposite direction are adjacent to each other. For example, a first cone-shaped portion 171 and a second cone-shaped portion 172 inclined in the opposite direction to the first cone-shaped portion 171 are adjacent in the direction of the central axis C3. Also, a second cone-shaped portion 172 and a third cone-shaped portion 181 inclined in the opposite direction to the second cone-shaped portion 172 are adjacent in the direction of the central axis C3. The third cone-shaped portion 181, fourth cone-shaped portion 182 and fifth cone-shaped portion 161 are similarly adjacent. Therefore, the hollow member 130 deforms, and these cone-shaped portions 161, 171, 172, 181, and 182 expand and contract in the longitudinal direction of the toothbrush 11, or bend with respect to the central axis C1, thereby cushioning the external force applied when the toothbrush falls over.

[0066] Furthermore, by incorporating a hollow cylindrical component 130, the toothbrush 11 has a hollow interior, resulting in a lighter overall mass. This makes it easy to operate even for users with insufficient grip strength, such as infants and the elderly.

[0067] Furthermore, because the hollow member 130 has annular cap-shaped portions 161, 171, 172, 181, and 182, when the toothbrush 11 deforms, the hollow member 130 can also deform in the front, back, left, and right directions, as well as in diagonal directions, which are any direction perpendicular to the longitudinal direction of the toothbrush 11. In this way, the toothbrush 11 can bend in any direction, so it can cushion external forces applied in any direction when it falls over, and the force of the user is distributed so that the brush is less likely to injure the gums.

[0068] Furthermore, since the hollow member 130 is made of synthetic resin, the manufacturer can heat and melt the raw resin, then cool it to mold it into the desired shape. It is known that the mechanical properties, such as hardness, may differ depending on the type of synthetic resin. Also, by increasing or decreasing the wall thickness before cooling, the wall thickness of the hollow member 130 after molding can be changed. As a result, when manufacturing with different materials or wall thicknesses, the manufacturer can obtain toothbrushes 11 with varying degrees of cushioning against external forces during tipping, differences in mass, and the amount of pressure applied to the user's gums.

[0069] Furthermore, the multiple deformable cap-shaped sections 161, 171, 172, 181, and 182 overlap in a bellows-like manner within the bellows section 15. As the number of these overlapping cap-shaped sections increases, the length that the entire hollow member 130 can deform increases. Similarly, the curvature angle of the entire hollow member 130 also increases. As a result, the toothbrush 11 can absorb greater external forces. In addition, the force of the user is distributed more evenly, making it less likely for the brush to injure the gums.

[0070] Furthermore, since the deformation and curvature of the entire bellows structure of the bellows section 15 are shared by the elastically deformable cap-shaped sections 161, 171, 172, 181, and 182, each individual cap-shaped section is less likely to undergo plastic deformation. As a result, the toothbrush 11 continues to elastically deform despite repeated use, providing long-lasting cushioning against external forces in the event of a fall and minimizing damage to the user's gums.

[0071] Furthermore, since the gripping portion 16 of the hollow member 130 is located closer to the base end than the bellows portion 15, the user does not need to touch the bellows structure with their fingers when using the toothbrush 11. Therefore, the toothbrush 11 does not interfere with the expansion and contraction and bending of the bellows structure during use, can reliably absorb external forces in the event of a fall, and is less likely to injure the user's gums.

[0072] [Second Embodiment] A second embodiment of the present invention will be described with reference to Figures 13 to 19. In the front view of Figure 13(a) and the right side view of Figure 13(b), 21 is a toothbrush. The toothbrush 21 has a head portion 22 at the tip and a handle portion 23 that is held to guide the head portion 22 into the oral cavity. Brushes 24 are embedded in the head portion 22.

[0073] The central axis of the toothbrush 21 is represented by the center line of C1. The handle portion 23 has two bulging portions 29 at the top and bottom that bulge away from the central axis C1, and two constricted portions 30 at the top and bottom that narrow towards the central axis C1. In this case, the upper constricted portion 30a, the upper bulging portion 29a, the lower constricted portion 30b, and the lower bulging portion 29b are arranged in the order from top to bottom. The handle portion 23 also has a flange-like portion 27 above the upper constricted portion 30a that protrudes in a flange-like manner away from the central axis C1.

[0074] Figure 14 shows a perspective view of the toothbrush 21 disassembled vertically so that the head member 220 and the hollow member 230 are separated. The head member 220, when combined with the hollow member 230, constitutes the head portion 22. The hollow member 230, which is formed in a hollow cylindrical shape, constitutes the handle portion 23 when combined with the head member 220. At this time, the tip portion 231 of the hollow member 230 is located inside the head member 220 and constitutes part of the head portion 22. The central axis C2 of the head member 220 and the central axis C3 of the hollow member 230 coincide with the central axis C1 of the toothbrush 21 when they are combined.

[0075] Figure 15(c) shows a front view of the hollow member 230. Figures 15(a) and 15(b) show a plan view and a side view of the hollow member 230 rotated 30° counterclockwise around the central axis C3 from the position shown in Figure 15(c), respectively. Figure 15(d) shows the end face and bottom face of the cross section at corresponding positions in the vertical direction.

[0076] As shown in the cross-sectional views of Figure 15(d), the cross-section of the hollow member 230 has a flange-like portion 27 that is circular, an upper constricted portion 30a that is circular with a smaller diameter than the flange-like portion 27, and upper and lower bulging portions 29a and 29b that are roughly regular hexagons with rounded vertices. Although not shown, the lower constricted portion 30b is also roughly regular hexagon with rounded vertices.

[0077] Figure 16 shows an enlarged partial view of the vicinity of the tip portion 231 in the right side view of the hollow member 230. The peak of the flange portion 27 that is formed furthest outward from the central axis C3 is called the peak portion 27a. The flange portion 27 is composed of a first cap-shaped portion 271 above the peak portion 27a and a second cap-shaped portion 272 below it. This first cap-shaped portion 271 has a convex partial spherical surface that decreases in diameter towards the top.

[0078] Figure 17 shows the head member 220 and the hollow member 230 in a detachably connected state. A partial right side cross-sectional view of the head member 220 is shown. The outline of the hollow member 230 as seen from the right side is shown. To assemble the head member 220 and the hollow member 230, the tip portion 231 is inserted upward into the opening 221.

[0079] When the head member 220 and the hollow member 230 are connected, the opening edge 223 is adjacent to the flange-shaped portion 27 in the vertical direction on the side of the first cap-shaped portion 271.

[0080] Figures 18(a) to (c) show the state in which the head member 220 gradually tilts relative to the hollow member 230, as viewed from the slightly forward right side of the toothbrush 21. Figure 18(a) shows the state before the head member 220 tilts. Figures 18(b) and (c) show the state in which the head member 220 tilts when a force is applied backward to the bristle surface 22b, as an example. That is, the angle between the central axis C2 of the head member 220 and the central axis C3 of the hollow member 230 gradually increases. Note that while an example of the head member 220 tilting backward is shown, the toothbrush 21 changes similarly when tilted forward, to the left, to the right, etc.

[0081] As shown in Figures 18(b) and 18(c), the hollow member 230 deforms elastically as the head member 220 tilts. At this time, mainly the rear portions of the first cap-shaped portion 271 and the second cap-shaped portion 272 of the flange-shaped portion 27 are compressed in the vertical direction. Conversely, the front portions of the first cap-shaped portion 271 and the second cap-shaped portion 272 stretch in the vertical direction. As shown in Figure 17, the engaging convex portion 235 and the engaging concave portion 225 are engaged, so the hollow member 230 does not detach from the head member 220. When the applied force is released, the shape of the hollow member 230, which is formed of elastic material, is restored, and the head member 220 returns to its original position and orientation.

[0082] Figures 19(a) to (c) are right-side cross-sectional views showing the state in which the head member 220 is gradually tilted relative to the hollow member 230. As shown in Figures 19(b) and (c), in accordance with the tilt of the head member 220, the fitting region 232 of the hollow member 230, which is fitted into the fitting region 222 of the head member 220 as shown in Figure 17, also tilts. Consequently, the flange-shaped portion 27 adjacent to the fitting region 232 tilts. Due to these tilts, the first cap-shaped portion 271 and the second cap-shaped portion 272 are crushed so that they move closer to each other on the rear side, as they are sandwiched between the fitting region 232 and the upper constricted portion 30a. On the front side, they stretch so that they move away from each other. At this time, with respect to the original central axis C3 of the hollow member 230, at least the center line C271 of the first cap-shaped portion 271 of the cap-shaped portions 271 and 272 is tilted so that it is located further back as it goes higher.

[0083] Incidentally, when the tilt of the head member 220 is not large, the shape of the flange portion 27 is not significantly different from the shape before deformation, so the force required for the first cap portion 271 and the second cap portion 272 to tilt in an attempt to maintain their original three-dimensional structure increases with the magnitude of the tilt. However, as shown in Figure 19(c), for example, when the tilt of the head member 220 becomes large to a certain extent, the first cap portion 271 and the second cap portion 272 are in a state of near-contact, so the structure changes from its original three-dimensional structure to a state closer to a two-dimensional structure. The inventors have found that at this stage, the force required to create further tilting is constant regardless of the magnitude of the tilt.

[0084] The other components are the same as those of the first embodiment.

[0085] With the above configuration, the toothbrush 21 has a handle portion 23 that is elastically deformable and has a bulge portion 29, so even elderly people and infants with weak grip strength can easily support the toothbrush 21 by gripping the thick bulge portion 29 with their fingers or fingers and palm. Moreover, since the handle portion 23 is made of a hollow member 230 with a hollow structure, it is soft, and even users with weak grip strength can firmly grip the hollow bulge portion 29. Therefore, there is less risk of dropping the toothbrush 21 while cleaning teeth.

[0086] Furthermore, since the toothbrush 21 has a constricted portion 30, the user can stabilize and support the toothbrush 21's position when cleaning their teeth by placing their fingers on the constricted portion 30. In particular, since the upper constricted portion 30a is located between the flange portion 17 and the upper bulge portion 29a, the user can, for example, place their index finger on the upper constricted portion 30a and their middle and ring fingers on the respective bulges 29a and 29b, allowing the index finger to control the position and angle of the head portion 22 while the middle and ring fingers securely grip the handle portion 23. In this way, efficient teeth cleaning can be performed with the toothbrush 21.

[0087] Furthermore, because the first cap-shaped portion 271 of the flange-shaped portion 27 of the toothbrush 11 has a convex partial spherical surface, the portion of the hollow member 230 above the flange-shaped portion 27 tilts, causing the first cap-shaped portion 271 and the second cap-shaped portion 272 to collapse closer together. The inventor discovered that once the force applied to cause the tilt exceeds a certain degree of tilt (deformation), that force becomes constant. Therefore, even if a force greater than a certain force is accidentally applied to the toothbrush 21 during oral cleaning, the force can be appropriately cushioned. Thus, with the structure of the toothbrush 21 of the present invention, the degree of force cushioning can be easily adjusted by adjusting the thickness, shape, material, etc. of each cap-shaped portion 271, 272 during manufacturing.

[0088] [Third Embodiment] A third embodiment of the present invention will be described with reference to Figure 20. In the front view of Figure 20(a) and the right side view of Figure 20(b), 31 is a toothbrush. The toothbrush 31 has a head portion 32 at the tip and a handle portion 33 at the base that is held to guide the head portion 32 into the oral cavity. Brushes 34 are embedded in the head portion 32. The central axis of the toothbrush 31 is represented by the reference numeral C1. Although not shown, the toothbrush 31 is disassembled into a head member 320 and a hollow member 330 in the direction of the central axis C1. The head member 320, when combined with the hollow member 330, constitutes the head portion 32. The hollow member 330, which is formed in a roughly cylindrical shape, constitutes the handle portion 33 when combined with the head member 320.

[0089] The handle portion 33 has a bellows portion 35 at its tip and a grip portion 36 at its base for the user to grasp the toothbrush 31 with their fingers. The bellows portion 35 has a plurality of flange-like portions 37, 38A, and 38B that protrude in a flange-like manner away from the central axis C1. Of these flange-like portions 37, 38A, and 38B, the flange-like portion at the tip is called the tip-side flange portion 37, the flange-like portion adjacent to the base end of the tip-side flange portion 37 is called the first base-side flange portion 38A, and the flange-like portion further adjacent to the base end of the first base-side flange portion 38A is called the second base-side flange portion 38B.

[0090] The peak of the tip flange portion 37 that is formed furthest outward from the central axis C1 is called the tip peak portion 37a. The tip flange portion 37 is composed of a first cap-shaped portion 371 above the tip peak portion 37a and a second cap-shaped portion 372 below it. Thus, the first cap-shaped portion 371 and the second cap-shaped portion 372 are adjacent to each other in the vertical direction. A bellows-like structure bellows portion 35 is formed in which multiple cap-shaped portions, including the first cap-shaped portion 371 and the second cap-shaped portion, are arranged in a bellows-like manner.

[0091] The tip flange portion 37 is formed in a disc shape, and its outer diameter is larger than the outer diameters of the base flange portions 38A and 38B. Furthermore, the outer diameter of the tip flange portion 37 is longer than the length H in any direction away from the central axis C2 of the head member 320 in the head portion 32 on which the brush 34 is planted. Figure 20(b) shows Hfb, which is the length H in the front-rear direction.

[0092] The other components are the same as those of the first embodiment.

[0093] With the above configuration, the toothbrush 31 has a tip-side flange-shaped portion 37 on the proximal end side of the head portion 32, and this tip-side flange-shaped portion 37 has a larger diameter than the head portion 32 on which the brush 34 is attached. Therefore, when the user inserts the head portion 32 into the oral cavity to brush their teeth with the brush 34, the tip-side flange-shaped portion 37 is likely to come into contact with the user's front teeth, making it difficult for the portion of the toothbrush on the proximal end side of the tip-side flange-shaped portion 37 to enter the oral cavity.

[0094] As a result, even if only the head portion 32 of the toothbrush 31 enters the oral cavity, it is difficult for the rest of the toothbrush to enter the oral cavity. Therefore, even if the toothbrush 31 falls over during use and the base of the toothbrush 31 hits the floor or other surface, the fact that the rest of the toothbrush does not enter the oral cavity reduces the likelihood of the tip of the toothbrush 31 injuring the inside of the mouth. This is especially effective for young children with small oral openings.

[0095] [Fourth Embodiment] A fourth embodiment of the present invention will be described with reference to Figure 21. In the plan view of Figure 21(a) and the front view of Figure 21(b), 41 is a toothbrush. The toothbrush 41 has a head portion 42 at the tip end and a handle portion 43 at the base end which is held to guide the head portion 42 into the oral cavity. A brush 44 is attached to the tip portion of the head portion 42.

[0096] The central axis of the toothbrush 41 is represented by the symbol C1. The cross-section of the neck portion 42a of the head portion 42 is formed in a substantially circular shape, and the central axis C1 passes through the center of this cross-section in the vertical direction. The neck portion 42a refers to the part of the head portion 42 located below the bristle portion 42c, which is the part of the head portion 42 where the brush 44 is implanted at the tip. The bristle portion 42c is formed in a substantially cylindrical shape with its center line coinciding with the central axis C1, and is continuous with the neck portion 42a in the vertical direction. The entire front, back, left, and right sides of the bristle portion 42c form the bristle surface 42b. Since the brush 44 is implanted perpendicular to the curved bristle surface 42b, the whole arrangement is radial in a plan view.

[0097] Other configurations are common to the first, second, or third embodiment.

[0098] With the above configuration, the toothbrush 41 can bend and deform in any direction perpendicular to the central axis C1, thereby absorbing the user's force in any direction. In contrast, each bristle 44 is planted radially in any direction. Therefore, the toothbrush 44 absorbs the force in any direction the user uses to brush their teeth, regardless of which direction the bristle 44 is planted, thus always dispersing the user's force and making it less likely for the bristles to injure the gums.

[0099] Furthermore, because the brush bristles 44 are arranged radially, the user does not need to change their grip on the toothbrush 41 and rotate it when cleaning multiple teeth in the mouth using the toothbrush 41. In addition, because the toothbrush 41 can bend and deform in any direction perpendicular to the central axis C1, the user can brush any area they like without changing their grip on the toothbrush 41, and the brush bristles 44 are less likely to injure the gums in the process.

[0100] [Fifth Embodiment] A fifth embodiment of the present invention will be described with reference to Figures 22 and 23. In the right side view of Figure 22(a), 530 is a hollow member of the toothbrush 51. A plan view of the toothbrush 51 is shown in Figure 22(c). The brush 54 is planted on the bristle surface 52b so as to be located on the front side of the head portion 52, as in the other embodiments.

[0101] The tip flange portion 57, the base flange portion 58, and the gripping portion 56 have ribs 536 that protrude away from the central axis C3 of the hollow member 530 and extend in a direction parallel to the central axis C3. That is, the toothbrush 51 has the upper half of a rib 536 formed integrally with the second cap portion 572 and the third cap portion 581, and the lower half of a rib 536 formed integrally with the fourth cap portion 581 and the fifth cap portion 561. In the example in Figure 22, one rib 536 protrudes backward.

[0102] The rib 536 has a hollow structure, and its hollow space communicates with and is common to the hollow space E of the hollow member 530. Furthermore, the rib 536 is integral with the other parts of the hollow member 530, and is made of the same material and molded in the same process. Figure 22(b) shows the end faces in a cross-section of the hollow member 530, showing, from top to bottom, the end face of the tip side crest 57a, the end face of the tip side valley 57b, the end face of the base side crest 58a, and the end face of the base side valley 58b, respectively. Of these, the rib 536 is shown projecting backward from the end faces of each valley 57b and 58b.

[0103] Furthermore, in the example shown in Figure 23, three ribs 536, 537l, and 537r are projected backward, to the left, and to the right, respectively. The front view in Figure 23(a) shows the rib 537l projecting to the left and the rib 537r projecting to the right. The right side view in Figure 23(b) shows the rib 537r projecting to the right, and the rib 536 projecting backward, similar to Figure 22. In Figure 23(c), the end faces of the tip-side valley 57b and the base-side valley 58b show, clockwise from the top of the figure, the rib 537l projecting to the left, the rib 536 projecting backward, and the rib 537r projecting to the right, respectively.

[0104] Other configurations are common to the first, second, third, or fourth embodiment.

[0105] With the above configuration, the ribs 536, 537l, and 537r are provided protruding from the cap-shaped portions 561, 571, 572, 581, and 582, making the hollow member 530 less likely to bend in the direction in which the ribs 536, 537l, and 537r are provided. As a result, the manufacturer can produce a toothbrush 51 in which the hollow member 530 is less likely to bend in a specific direction by providing the ribs 536, 537l, and 537r protruding. Therefore, by changing the degree of bending depending on the direction, it is possible to provide an optimal toothbrush 51 that suits the user's needs.

[0106] For example, in the example in Figure 22, it is difficult for the toothbrush 51 to bend backward where the rib 536 is located. Also, it is slightly more difficult to bend forward, which is opposite to the rib 536, compared to the leftward or rightward directions. Therefore, the force applied by the user gripping the toothbrush 51 is less likely to escape backward and is efficiently transmitted in other directions. In the example in Figure 23, it is difficult for the toothbrush to bend leftward, backward, and rightward where the ribs 536, 537l, and 537r are located. Therefore, the force is efficiently transmitted forward. For example, the force is efficiently transmitted in the direction of the brush 54.

[0107] Although not shown in the diagram, any number of ribs can be provided in any direction, such as providing only two ribs, 537l protruding to the left and 537r protruding to the right.

[0108] [Sixth Embodiment] A sixth embodiment of the present invention will be described with reference to Figures 24 and 25. In the right side view of Figure 24(a), 630 is a hollow member of the toothbrush 61. A plan view of the toothbrush 61 is shown in Figure 24(c). The bristles 64 are planted on the bristle surface 62b so as to be located on the front side of the head portion 62, as in the other embodiments.

[0109] Figure 24(b) shows the end faces in a cross-section of the hollow member 630, showing, from top to bottom, the end face of the tip-side peak 67a, the end face of the tip-side valley 67b, the end face of the base-side peak 68a, the end face of the base-side valley 68b, and then the end face of the gripping portion 66. In these examples of end faces, the inner wall in the hollow space E of the hollow member 630 is indicated by reference numeral 638. This inner wall is called the hollow member inner wall 638.

[0110] In this example, the bellows section 65 and gripping section 66 of the hollow member 630 are formed such that the shape of the inner wall 638 of the hollow member is circular in cross-section, and this circular shape is eccentric to the outer circle in the same cross-section. That is, at each end face in Figure 24(b), the center of the inner wall 638 of the hollow member is offset forward compared to the center of the outer circle. For example, at the end face of the tip-side peak 67a, the center point C4 of the inner wall 638 of the hollow member is positioned forward compared to the center point C3 of the outer circle of the hollow member 630. As a result, the bellows section 65 and gripping section 66 of the hollow member 630 have parts where the wall thickness differs depending on the circumferential position, with the rear side being the thickest and the front side being the thinnest, and the left and right sides having thicknesses intermediate between these.

[0111] Figure 25(b) also shows the end faces in the cross-section of the hollow member 630, and, as with Figure 24(b), from top to bottom, the end faces of the tip-side peak 67a, the tip-side valley 67b, the base-side peak 68a, and the base-side valley 68b are shown, followed by the end face of the gripping portion 66. In these examples of end faces, the inner wall in the hollow space E of the hollow member 630 is indicated by reference numeral 639. This inner wall is called the hollow member inner wall 639.

[0112] In this example, the bellows section 65 and gripping section 66 of the hollow member 630 have a circular outer circumference in their cross-section, while the inner wall 638 of the hollow member is formed to have an elliptical shape with a major axis in the front-to-back direction in its cross-section. The center point of this ellipse coincides with the center point C3 of the outer circumference. As a result, the bellows section 65 and gripping section 66 of the hollow member 630 have parts where the wall thickness differs depending on the circumferential position, with the front and rear sides being the thinnest, the left and right sides being the thickest, and the other parts having thicknesses intermediate between these.

[0113] Furthermore, as in these examples, the inner walls 637 and 638 of the hollow members do not need to be eccentric or elliptical throughout the entire bellows section 65 and gripping section 66; they may be eccentric or elliptical only in parts of the bellows section 65 and gripping section 66. Also, the inner walls 637 and 638 of the hollow members of the entire or partial insertion area 632 may be eccentric or elliptical. Moreover, the wall thickness may vary depending on the circumferential position due to irregular shapes other than eccentric circles or elliptical inner walls.

[0114] Other configurations are common to the first, second, third, fourth, or fifth embodiment.

[0115] With the above configuration, part or all of the hollow member 630 has portions with different wall thicknesses in the circumferential direction of the central axis C3, and has a wall thickness variation structure where the thickness differs depending on the circumferential position. Therefore, the hollow member 630 has greater resistance to bending at the thicker walled portions and, conversely, less resistance to bending at the thinner walled portions. As a result, the manufacturer of the toothbrush 61 can change the angle at which it can be bent relatively easily, or the force that must be applied to bend it to a certain angle, depending on the direction of bending. This makes it possible for the manufacturer to change the degree of cushioning of external forces when the toothbrush 61 falls over, the degree of force absorption applied to the gums, etc., depending on the direction of bending, and to provide an optimal toothbrush that suits the user's needs.

[0116] For example, the toothbrush 61 in the example in Figure 24 is relatively thick and difficult to bend backward. Conversely, it is relatively thin and easy to bend forward. Therefore, the force applied by the user when gripping the toothbrush 61 is not easily lost backward, but is efficiently transmitted forward. For example, the force is efficiently transmitted in the direction of the brush bristles 64. The toothbrush 61 in the example in Figure 25 is relatively thick and difficult to bend to the left and to the right. Conversely, it is relatively thin and easy to bend forward and backward.

[0117] Although embodiments of the present invention have been illustrated above, the present invention is not limited to these embodiments, and various modifications are possible without departing from the spirit of the invention.

[0118] For example, the material of the head component is not limited to polypropylene (PP), saturated polyester (PET), polyacetal (POM), etc. It may be any other synthetic resin or material other than synthetic resin, as long as it can accommodate bristles and has sufficient strength to withstand tooth brushing. It may also be formed by a manufacturing method other than injection molding.

[0119] Furthermore, 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 into a hollow shape, is elastic, and has sufficient strength to support the head member. It may also be formed by a manufacturing method other than blow molding.

[0120] The cross-section or lower end of the head member may be formed in a shape other than circular, and the cross-section of the hollow member may be formed in a shape other than circular or a substantially regular hexagon. The head member may have a polygonal cross-section, for example, as long as it can accommodate the joint structure with the hollow member. Furthermore, the cross-section of the hollow member including the bellows section may be an ellipse, an oblong, a polygon other than a hexagon, or a polygon other than a regular polygon, as long as it can be easily grasped by the fingers and palm and the curvature of the bellows section is not difficult.

[0121] The number of cap-shaped sections in the bellows section is not limited to the first and second cap-shaped sections or the first to fifth cap-shaped sections as shown in each of the embodiments described above, but may be less or more, as long as it does not hinder tooth brushing, bending, or restoration after bending.

[0122] Furthermore, as illustrated in Figure 26, the head member may have a female threaded portion in the insertion area and the hollow member may have a male threaded portion in the insertion area. In this way, the head member and the hollow member can be combined by screwing the female threaded portion and the male threaded portion into each other and by the insertion area fitting into the insertion area.

[0123] Furthermore, the head does not necessarily have to be shaped to gradually narrow towards the top; as long as the weight balance for cleaning teeth is not poor, it may also have a two-tiered shape where the diameter decreases from the middle, as exemplified in the partial front view of Figure 27. [Industrial applicability]

[0124] This invention can be used in a toothbrush for cleaning the user's teeth with embedded brushes. [Explanation of Symbols]

[0125] 11, 21, 31, 41, 51, 61 toothbrushes 12,22,32,42,52,62 Head section 13, 23, 33, 43, 53, 63 Handle section 14,24,34,44,54,64 brush 15, 25, 35, 45, 55, 65 Bellows 16,26,36,46,56,66 Gripping part 17, 37, 57, 67 Tip side flange 17a,37a,57a,67a Tip side mountain part 17b,57b,67b Tip side valley 18,38,58,68 Base end flange 18a,58a,68a Proximal mountain part 18b, 58b, 68b Base end valley 27 Flange 27a Yamabe 29 Bulge 30. Constricted area 120, 220, 320, 420, 520, 620 Head components 130, 230, 330, 430, 530, 630 Hollow members 161,561,661 Fifth cap 171 ,271,371,571,671 1st cap 172 ,272,372,572,672 Second cap 181 ,581,681 Third cap 182,582,682 4th cap

Claims

1. The device comprises a head member in which a head portion into which a brush is implanted is formed, and a hollow member connected to the head member and forming a handle portion for gripping in order to guide the head portion into the oral cavity, the hollow member being cylindrical and integrally formed from an elastic material, The hollow member has a plurality of conical and annular cap-shaped portions, each having a center line that coincides with the central axis of the cylindrical shape when not deformed, and a first conical portion and a second conical portion that is inclined in the opposite direction to the first conical portion in the direction of each center line are adjacent in the direction of each center line, and are configured such that when deformed, the center line of at least one conical portion is inclined with respect to the central axis, the tip of the connecting portion with the head member is frustoconical in shape, decreasing in diameter towards the tip, the tip portion including the tip has a hollow structure, and has a downward step that extends around the entire circumference in the middle of the central axis direction of the cylindrical shape. The head member has an opening in the connecting portion which has a substantially frustoconical internal space that narrows in diameter towards the back, and a substantially annular undercut portion that protrudes radially inward around the entire circumference of the internal space. A toothbrush characterized by the following features.

2. The hollow member is formed by molding synthetic resin. The toothbrush according to feature 1.

3. The hollow member has a bellows structure in which the plurality of cap-shaped portions are arranged in a bellows-like manner. The toothbrush according to feature 2.

4. The hollow member has a gripping portion on the base end side in the direction of the central axis, and the bellows structure is located on the tip side of the gripping portion. The toothbrush according to feature 3.

5. The first cap-shaped portion and the second cap-shaped portion are combined to form a flange-shaped tip side flange portion. The aforementioned flange-like portion at the tip has a larger diameter than the length of the head portion in the direction perpendicular to its longitudinal direction. The toothbrush according to feature 1.

6. The hollow member has a portion in which the wall thickness differs depending on the circumferential position, at least in a part of the bellows structure in the central axis direction. The toothbrush according to feature 3.

7. Multiple brushes are arranged on the head member such that each brush forms a radial pattern when viewed in the direction of the central axis. The toothbrush according to feature 1.

8. The aforementioned cap-shaped portion has ribs that protrude away from the central axis and extend in a direction parallel to the central axis direction. A toothbrush according to any one of features 1 to 7.

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