Toothbrush

Abstract

To provide a toothbrush which has high versatility and allows a user to recognize a proper brushing pressure.SOLUTION: A toothbrush has: a head part provided on a tip side in a long axis direction and has an implantation surface; a grip part arranged on a rear end side of the head part; and a neck part arranged between the implantation surface and the grip part, wherein a sensing part which senses that external force in a first direction orthogonal to the implantation surface exceeds a threshold is provided on a rear end side than the implantation surface. The toothbrush comprises: an inversion part for connecting a first region on a tip side than the sensing part and a second region on the rear end side, and snap buckling and inverting, following to displacement of the head part to a back surface side caused by the external force greater than the threshold; and an elastic deformation part arranged at an interval from the inversion part, connecting the first region and the second region, and elastically deforming to at least a degree of the external force in which the inversion part snap buckles and inverts. The inversion part is positioned between an external shape contour on the implantation surface side in the elastic deformation part and an external shape contour on the back surface side, in side view from a direction which is orthogonal to a long axis direction and the first direction.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a toothbrush. This application claims priority based on Japanese Patent Application No. 2018-246145, filed on December 27, 2018, the contents of which are incorporated herein by reference. [Background technology]

[0002] While the percentage of people who have 20 teeth at age 80 is about 50%, the percentage of elderly people with caries (root caries) is increasing. Root caries is caries in the dentin exposed by gingival recession, but dentin has a higher organic component ratio than enamel, so caries progresses more quickly. One of the causes of gingival recession is overbrushing, which is brushing with more pressure than is appropriate.

[0003] Since the brushing pressure is defined as the load / flocked area, the brushing pressure can be reduced by at least one of reducing the load and increasing the flocked area. Regarding the reduction of the load, toothbrushes are commercially available that are designed to tilt the neck part above the flocked surface in advance, so that the neck part bends during brushing and brush with a force that makes the neck part straight during brushing, soft toothbrushes using fine bristles, and toothbrushes that are designed to place the center of gravity of the grip part closer to the rear end of the handle so that the flocked part is less likely to be subjected to force. Regarding the increase of the flocked area, toothbrushes with a wide head width are commercially available. However, although it is possible to reduce the brushing pressure with these specifications, it is difficult to make all users recognize the appropriate brushing pressure at the same level and control the brushing pressure.

[0004] In addition, although dental clinics provide guidance on proper brushing methods, it has been found that many users are aware that they are overbrushing but are unable to improve because they find it difficult to do so on their own due to reasons such as not being clear about how much pressure to use.

[0005] Thus, an example of a means for allowing a user to recognize the appropriate brushing pressure is the toothbrush disclosed in Patent Document 1. The toothbrush disclosed in Patent Document 1 is disposed between the head and the grip, and has a two-beam structure consisting of a rear beam to which a compressive stress is applied during normal use, and a face beam to which a tensile stress is applied.

[0006] In this toothbrush, when a compressive force exceeding a determined force is applied to the rear beam while the user is holding the gripping portion, the rear beam elastically buckles and reverses from an upwardly convex arc to a downwardly convex arc. In this way, the toothbrush disclosed in Patent Document 1 can make the user aware that the appropriate brushing pressure has been exceeded by the rear beam reversing. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Special Publication No. 6-504937 Summary of the Invention [Problem to be solved by the invention]

[0008] However, in the toothbrush disclosed in Patent Document 1 mentioned above, when excessive brushing load is applied, the rear beam deforms in a direction approaching the face beam, so there is a limit to the amount of deformation of the rear beam and it cannot be said to be sufficiently versatile.

[0009] The present invention has been made in consideration of the above points, and has an object to provide a toothbrush that is highly versatile and allows the user to recognize the appropriate brushing pressure. [Means for solving the problem]

[0010] According to a first aspect of the present invention, a hair-planting device includes a head portion having a hair-planting surface provided at a tip end side in a long axis direction, a grip portion disposed rearward of the head portion, and a neck portion disposed between the hair-planting surface and the grip portion, and a sensing portion is disposed rearward of the hair-planting surface for sensing that an external force in a first direction perpendicular to the hair-planting surface has exceeded a threshold value, the sensing portion connects a first region on the tip side of the sensing portion to a second region on the rear side of the sensing portion, and detects that an external force in the first direction has exceeded a threshold value. The toothbrush provided is characterized in that it comprises an inverted portion that snaps through and inverts as the head portion is displaced toward the back side, which is the side opposite the bristle implantation surface, and an elastically deforming portion that is arranged with a gap from the inverted portion, connects the first region and the second region, and elastically deforms at least up to the external force at which the inverted portion snaps through and inverts, the inverted portion being located between the outer contour of the bristle implantation surface side and the outer contour of the back side of the elastically deforming portion when viewed from the side in a direction perpendicular to the longitudinal axis and the first direction.

[0011] Furthermore, in the toothbrush according to one aspect of the present invention described above, the elastic deformation portion and the inverted portion are arranged with a gap therebetween in a second direction perpendicular to the first direction and the long axis direction, respectively.

[0012] Furthermore, in the toothbrush according to one aspect of the present invention described above, the elastic deformation portion and the inverted portion are arranged with a gap therebetween in a second direction perpendicular to the first direction and the long axis direction, respectively.

[0013] Furthermore, in the toothbrush according to one aspect of the present invention described above, the inverted portion is convex toward the rear surface side when the external force in the first direction is equal to or less than a threshold value, and is inverted to a convex shape toward the bristle surface side when the external force in the first direction exceeds the threshold value.

[0014] Furthermore, in the toothbrush according to one aspect of the present invention described above, when the external force in the first direction is below a threshold value, the inverted portion inclines in a direction toward the bristle implantation surface as it moves from the apex of the convex shape toward the end in the longitudinal direction, and the angle at which the inverted portion inclines with respect to planes parallel to the first direction and the longitudinal direction is greater than or equal to 5 degrees and less than or equal to 11 degrees.

[0015] Furthermore, in the toothbrush according to one aspect of the present invention described above, the inverted portion is characterized in that it has a groove portion extending in the second direction on at least one of the bristle implantation surface side and the back side in a region including the apex of the convex shape.

[0016] In addition, in the toothbrush according to one aspect of the present invention described above, when the inverted portion snaps and buckles, the movement distance of the apex of the convex shape in the first direction is 0.2 mm or more and 5.0 mm or less.

[0017] Furthermore, in the toothbrush according to one aspect of the present invention described above, the inverted portion is provided in the center in the second direction, and the elastic deformation portions are provided on both sides of the inverted portion in the second direction.

[0018] Furthermore, in the toothbrush according to one aspect of the present invention described above, when the maximum thickness of the inverted portion in the first direction is T and the maximum thickness of the elastically deformable portion in the first direction is t, the value expressed by T / t is greater than or equal to 0.05 and less than or equal to 0.35.

[0019] Furthermore, in the toothbrush according to one aspect of the present invention described above, when the maximum width of the inverted portion in the second direction is L and the maximum width of the elastically deforming portion in the second direction is W, the value expressed by L / W is greater than or equal to 0.05 and less than or equal to 0.35.

[0020] In addition, in the toothbrush according to one aspect of the present invention described above, the inverted portion is formed from a hard resin, and a portion of the elastic deformation portion is formed from a resin having a hardness different from that of the hard resin.

[0021] In the toothbrush according to the above aspect of the present invention, the hard resin has a flexural modulus of elasticity of 1500 MPa or more and 3500 MPa or less.

[0022] In the toothbrush according to the above aspect of the present invention, a portion of the elastically deforming portion is formed from a soft resin.

[0023] In the toothbrush according to the above aspect of the present invention, the gap is a through hole extending in the first direction. Effect of the Invention

[0024] The present invention can provide a toothbrush that is highly versatile and allows the user to recognize the appropriate brushing pressure. [Brief description of the drawings]

[0025] [Figure 1] FIG. 1 is a front view of a toothbrush 1 according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view of the toothbrush 1 taken along a plane including the center in the width direction. [Diagram 3] 1 is a cross-sectional view of the sensing unit 70 cut along a plane parallel to the thickness direction and width direction. [Figure 4] 1 is a cross-sectional view of the sensing unit 70 taken along a plane parallel to the thickness direction and the long axis direction. [Diagram 5] 13 is a partial front view of the periphery of the sensing unit 70 in the hard portion 70H. FIG. [Figure 6] 13 is a partial side view of the periphery of the sensing unit 70 in the hard portion 70H. [Figure 7] FIG. 11 is a cross-sectional view of the sensing unit 70 cut along a plane parallel to the thickness direction and the long axis direction, for explaining the inversion of the inverted portion. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the toothbrush of the present invention will be described with reference to FIGS. The following embodiment shows one aspect of the present invention, does not limit the present invention, and can be arbitrarily modified within the scope of the technical idea of ​​the present invention. In the following drawings, the scale and number of each structure are different from the actual structure in order to make each configuration easier to understand. In the following description, the direction perpendicular to the implanted surface in side view is defined as the up-down direction, the implanted surface side is defined as the upper side, and the back side opposite the implanted surface is defined as the lower side. Note that the up-down direction, the upper side, and the lower side are names used simply for explanation, and do not limit the actual positional relationship or direction in the present invention.

[0027] Fig. 1 is a front view of toothbrush 1. Fig. 2 is a cross-sectional view of toothbrush 1 cut along a plane including the center in the width direction (the vertical direction in Fig. 1).

[0028] The toothbrush 1 of this embodiment comprises a head portion 10 arranged at the tip side in the longitudinal direction (hereinafter simply referred to as the tip side) and having bundles of bristles (not shown) implanted therein, a neck portion 20 extending to the rear end side in the longitudinal direction of the head portion 10 (hereinafter simply referred to as the rear end side), a sensing portion 70 extending to the rear end side of the neck portion 20, and a gripping portion 30 extending to the rear end side of the sensing portion 70 (hereinafter, the head portion 10, neck portion 20, gripping portion 30 and sensing portion 70 are collectively referred to as the handle body 2).

[0029] The toothbrush 1 of this embodiment is a molded body formed integrally of a hard part H made of hard resin and a soft part E made of soft resin. The hard part H constitutes at least a part of each of the head part 10, the neck part 20, the grip part 30, and the sensing part 70. The soft part E constitutes a part of each of the grip part 30 and the sensing part 70 (details will be described later).

[0030] [Head section 10] The head portion 10 has a hair implantation surface 11 on one side in the thickness direction (the direction perpendicular to the paper surface in FIG. 1). In the following, the side of the hair implantation surface 11 in the thickness direction is referred to as the front side in the front direction, the side opposite the hair implantation surface is referred to as the back side, and the direction perpendicular to the thickness direction and the longitudinal direction is referred to as the width direction (or side direction, as appropriate). A plurality of hair implantation holes 12 are formed in the hair implantation surface 11. Bundles of hair (not shown) are implanted in the hair implantation holes 12.

[0031] The width of the head part 10, i.e., the length in the width direction parallel to the bristle implantation surface 11 on the front side and perpendicular to the longitudinal direction (hereinafter simply referred to as width), is not particularly limited, and is preferably, for example, 7 mm or more and 13 mm or less. If it is equal to or more than the above lower limit, a sufficient area for implanting tufts of bristles can be secured, and if it is equal to or less than the above upper limit, operability in the oral cavity can be further improved.

[0032] The length of the head portion 10 in the long axis direction (hereinafter simply referred to as the length) is not particularly limited, and is preferably, for example, 10 mm or more and 33 mm or less. If the length of the head portion 10 is equal to or more than the above-mentioned lower limit, the area for planting the hair bundles can be sufficiently secured, and if it is equal to or less than the above-mentioned upper limit, the operability in the oral cavity can be further improved. In this embodiment, the boundary in the long axis direction between the neck portion 20 and the head portion 10 is the position where the width of the neck portion 20 becomes the minimum value from the neck portion 20 toward the head portion 10.

[0033] The length in the thickness direction of the head portion 10 (hereinafter simply referred to as thickness) can be determined taking into consideration the material, etc., and is preferably 2.0 mm or more and 4.0 mm or less. If the thickness of the head portion 10 is equal to or more than the above lower limit, the strength of the head portion 10 can be further increased. If the thickness of the head portion 10 is equal to or less than the above upper limit, the reachability to the back of the molars can be improved, and the operability in the oral cavity can be further improved.

[0034] The hair bundle is a bundle of multiple hairs. The length from the hair implantation surface 11 to the tip of the hair bundle (hair length) can be determined taking into consideration the desired hair stiffness of the hair bundle, and is, for example, 6 to 13 mm. All the hair bundles may have the same hair length or may have different hair lengths.

[0035] The thickness of the hair bundle (hair bundle diameter) can be determined taking into consideration the desired hair stiffness of the hair bundle, and is, for example, 1 to 3 mm. All the hair bundles may have the same hair bundle diameter, or may have different diameters.

[0036] The bristles constituting the bristle bundle include, for example, bristles whose diameter gradually decreases toward the tip and whose tips are sharpened (tapered bristles), bristles whose diameter is almost constant from the implantation surface 11 toward the tip (straight bristles), etc. Examples of straight bristles include bristles whose tips are flat and nearly parallel to the implantation surface 11, and bristles whose tips are rounded into a hemisphere.

[0037] Examples of the material of the bristles include polyamides such as 6-12 nylon (6-12NY) and 6-10 nylon (6-10NY), polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), and polybutylene naphthalate (PBN), polyolefins such as polypropylene (PP), polyolefin-based elastomers, and styrene-based elastomers, and the like. These resin materials can be used alone or in combination of two or more. In addition, examples of the bristles include polyester bristles having a multi-core structure having a core and at least one or more layers of sheath provided on the outside of the core.

[0038] The cross-sectional shape of the bristles is not particularly limited, and may be a circle, an ellipse or other circle, a polygon, a star, a three-leaf clover, a four-leaf clover, etc. The cross-sectional shapes of all the bristles may be the same or different.

[0039] The thickness of the bristles can be determined taking into consideration the material, etc., and when the cross section is circular, it is, for example, 6 to 9 mil (1 mil = 1 / 1000 inch = 0.025 mm). In addition, taking into consideration the feel of use, brushing feel, cleaning effect, durability, etc., multiple bristles of different thicknesses may be used in any combination.

[0040] [Neck section 20] From the viewpoint of operability, the length of the neck portion 20 is preferably 40 mm or more and 70 mm or less. As an example, the width of the neck portion 20 is formed so as to gradually increase from the position where the width is the minimum toward the rear end. In this embodiment, the neck portion 20 is formed so that the width gradually increases from the position where the width is the minimum toward the rear end. Also, the neck portion 20 is formed so that the thickness gradually increases from the position where the width is the minimum toward the rear end.

[0041] The width and thickness of the neck portion 20 at its minimum position are preferably 3.0 mm or more and 4.5 mm or less. If the width and thickness of the neck portion 20 at its minimum position are equal to or more than the above-mentioned lower limit, the strength of the neck portion 20 can be increased, and if they are equal to or less than the above-mentioned upper limit, the lips can be easily closed, the reach to the molars can be improved, and the operability in the oral cavity can be improved. The width and thickness of the neck portion 20, which are formed so as to gradually increase from the minimum position toward the rear end, can be appropriately determined taking into consideration the material, etc.

[0042] The front side of the neck portion 20 in a side view is inclined toward the front side toward the rear end. The back side of the neck portion 20 in a side view is inclined toward the back side toward the rear end. The neck portion 20 in a front view is inclined in a direction such that the distance from the width center increases toward the rear end.

[0043] In this embodiment, the boundary between the neck portion 20 and the sensing portion 70 is the position of the tip of the neck side 20 where the elastic deformation portion 90 described later is provided. Here, the width from the neck portion 20 to the grip portion 30 expands in an arc-shaped outline in both front and side views, and the position of the center of curvature of the arc coincides with the position in the long axis direction where the arc changes. More specifically, the boundary between the neck portion 20 and the sensing portion 70 coincides with the position in the long axis direction where the center of curvature changes from the outside of the arc-shaped outline to the center in the width direction in the front view shown in FIG. 1. Also, the boundary between the neck portion 20 and the sensing portion 70 coincides with the position in the long axis direction where the center of curvature changes from the outside of the arc-shaped outline to the center in the thickness direction in the side view shown in FIG. 2.

[0044] [Gripping part 30] The gripping portion 30 is disposed along the long axis direction. As shown in Fig. 1, the width of the gripping portion 30 gradually narrows from the boundary with the sensing portion 70 toward the rear end, and then extends at a substantially constant length. As shown in Fig. 2, the thickness of the gripping portion 30 gradually narrows from the boundary with the sensing portion 70 toward the rear end, and then extends at a substantially constant length.

[0045] In this embodiment, the boundary between the sensing unit 70 and the gripping unit 30 is the position of the tip of the gripping unit side 30 where the elastic deformation unit 90 described later is provided. Here, the width from the sensing unit 70 to the gripping unit side 30 is reduced in an arc-shaped outline in both front and side views, and the position of the center of curvature of the arc coincides with the position in the long axis direction where the center of curvature changes from the center side in the width direction to the outside of the arc-shaped outline in the front view shown in FIG. 1. Also, the boundary between the sensing unit 70 and the gripping unit 30 coincides with the position in the long axis direction where the center of curvature changes from the center side in the thickness direction to the outside of the arc-shaped outline in the side view shown in FIG. 2.

[0046] The position in the longitudinal direction where the widthwise length of gripping portion 30 gradually narrows from the boundary with sensing portion 70 toward the rear end and then becomes approximately constant length is the same as the position in the longitudinal direction where the thicknesswise length of gripping portion 30 gradually narrows from the boundary with sensing portion 70 toward the rear end and then becomes approximately constant length.

[0047] The gripping portion 30 has a soft portion 31E in the center in the width direction on the front side. The soft portion 31E constitutes a part of the soft portion E. The soft portion 31E gradually narrows from the boundary with the sensing portion 70 toward the rear end side in a front view, and then extends a substantially constant length. In a front view, the side edge of the soft portion 31E and the side edge on the outer side in the width direction of the gripping portion 30 are formed at a substantially constant distance.

[0048] The gripping portion 30 has a hard portion 30H. The hard portion 30H constitutes a part of the hard portion H. The hard portion 30H has a recess 31H on the front side in which a part of the soft portion 31E is embedded. The recess 31H gradually narrows from the boundary with the sensing portion 70 toward the rear end side in a front view, and then extends a substantially constant length.

[0049] A part of the soft portion 31E protrudes further than the hard portion 30H exposed on the front side. The other part of the soft portion 31E is substantially flush with the hard portion 30H exposed on the front side.

[0050] The gripping portion 30 has a soft portion 32E in the center in the width direction on the rear side (see Figs. 1 and 2). The soft portion 32E constitutes a part of the soft portion E. The soft portion 32E has an outer contour that is substantially the same as the outer contour of the soft portion 31E in a front view. That is, the soft portion 32E gradually narrows from the boundary with the sensing portion 70 toward the rear end side, and then extends a substantially constant length. In a rear view, the side edge of the soft portion 32E and the outer side edge of the gripping portion 30 in the width direction are formed at a substantially constant distance.

[0051] The hard portion 30H has a recess 32H (see FIG. 2) on the rear side in which a part of the soft portion 32E is embedded. The recess 32H gradually narrows from the boundary with the sensing portion 70 toward the rear end side in rear view, and then extends a substantially constant length.

[0052] A part of the soft portion 32E protrudes further than the hard portion 30H exposed on the rear side. The other part of the soft portion 32E is substantially flush with the hard portion 30H exposed on the front side.

[0053] Since the soft portion 31E is provided on the front side of the grip portion 30 and the soft portion 32E is provided on the back side, the gripping ability when the grip portion 30 is gripped is improved.

[0054] [Sensing section 70] The sensing unit 70 senses that an external force in a first direction perpendicular to the implanted surface 11 exceeds a threshold value. As shown in FIG. 1, the sensing unit 70 has an inverted portion 80 and an elastically deformable portion 90 that connect the neck portion 20 on the tip side of the sensing unit 70 to the grip portion 30 on the rear side of the sensing unit 70.

[0055] Fig. 3 is a cross-sectional view of the sensing unit 70 taken along a plane parallel to the thickness and width directions. Fig. 4 is a cross-sectional view of the sensing unit 70 taken along a plane parallel to the thickness and major axis directions. As shown in Fig. 3, the elastic deformation portions 90 are provided on both sides of the inverted portion 80 in the width direction with a gap S therebetween. The gap S is formed by a through hole K penetrating in the thickness direction. As shown in Fig. 1, the through hole K is formed in a rectangular shape in a plan view extending in the long axis direction.

[0056] By providing the gap S, the inverting portion 80 can be inverted (easier to invert) without interfering with the surrounding structure. In addition, since the deformation of the inverting portion 80 does not follow the deformation of the elastic deformation portion (because there is no interference), the functional roles of the inverting portion 80 and the elastic deformation portion 90 (described later) can be made independent. This increases the degree of freedom in design to obtain the following effects, for example. For example, it is possible to clearly generate vibrations and sounds when the inverting portion 80 inverts (described later). In addition, for example, it is possible to increase the repulsive force up to the threshold value in proportion to the amount of displacement, and it is possible to maintain the proportional relationship even in the vicinity of the threshold value (the degree of increase in the repulsive force does not become gentle). As a result, in the region up to the amount of displacement that reaches the upper limit pressure, the pressure assumed by the user is reflected as it is in the repulsive force, so the brushing load can be appropriately controlled. If the degree of increase in the repulsive force is gradually decreased near the threshold value, the user may unintentionally continue brushing with a pressure near the upper limit. In addition, if the gap S is connected to both sides in the thickness direction of the inverting portion 80, the above effect is further improved. By widening the gap S in the thickness direction, the vector of the load applied to the brush part (bristles) during brushing, the direction in which the gap opens, and the direction in which the reversing part 80 and the elastically deforming part 90 deform are parallel (see FIG. 7), making it easy to link the generation of vibration and sound due to reversal with the brushing load. Furthermore, if the gap S is made to penetrate the front side and the back side by the through hole K, for example, the movable area of ​​the elastically deforming part 90, which is responsible for the bending function of the toothbrush skeleton against the load during brushing, can be further expanded (the tensile behavior on the front side and the compressive behavior on the back side associated with bending are less likely to be hindered). If there is no through hole K between the elastically deforming part 90 and the reversing part 80, the movable area of ​​the elastically deforming part 90 is narrowed. In this case, it is assumed that the opportunity for the reversing part 80 to reverse is not given in the appropriate load range, and the reversing part 80 reverses before reaching the appropriate load range, or does not reverse even when the load range is appropriate. In response to this, by providing a through hole K between the elastic deformation portion 90 and the inverted portion 80, the "threshold value" at which the inverted portion 80 inverts, which will be described later, can be controlled in a finer range.The gap S does not have to penetrate in the thickness direction, and may be formed, for example, by a closed cavity extending in the long axis direction inside the elastic deformation portion 90. Also, the gap S may be formed by a recess (described later) that opens to the front side or the back side.

[0057] Each elastic deformation part 90 has a hard part 90H and a soft part 90E. As shown in FIG. 1, the hard part 90H and the soft part 90E connect the rear end of the neck part 20 and the front end of the grip part 30. As shown in FIG. 3 and FIG. 4, a recess (recess) 71 opening to the front side and a recess (recess) 72 opening to the rear side are provided between the pair of elastic deformation parts 90. The bottoms of both ends in the width direction of the recess 71 and the recess 72 are connected to the through hole K. The inverted part 80 is exposed and provided at the bottom in the center of the width direction of the recess 71 and the recess 72. By providing the recesses 71 and 72, for example, the movable area of ​​the elastic deformation part that performs the bending function of the toothbrush skeleton against the load during brushing can be further expanded, and the bending anisotropy in the thickness direction can be improved. The recess between the pair of elastic deformation parts 90 does not have to penetrate in the thickness direction, and may open only on one side in the thickness direction. Also, for example, a closed cavity extending in the long axis direction may be formed inside the elastic deformation portion 90, and a pair of elastic deformation portions may be formed in the width direction with the cavity sandwiched in between.

[0058] The pair of elastic deformation parts 90 have the ends of the soft parts 90E in the long axis direction connected to each other in the width direction on both the front side and the back side. The soft parts 90E of the pair of elastic deformation parts 90 are provided around the oval recesses 71, 72 in a front view. The rear end side of the soft part 90E is connected to the soft part 31E of the grip part 30.

[0059] Since the soft parts 90E are connected in the width direction at both the front and rear ends of the elastic deformation part 90, stress is less likely to concentrate on the end of the hinge structure even if it is repeatedly inverted, and it is less likely to break. Furthermore, since the soft parts 90E are connected in the width direction at both the front and rear ends of the elastic deformation part 90, the anisotropy in the sensing part 70 is increased, and for example, the pair of elastic deformation parts 90 can bend without twisting in the thickness direction in response to the movement during brushing. Furthermore, since the soft parts 90E are connected in the width direction, the amount of heat that the soft resin (elastomer) has during injection molding increases, and the adhesion between the neck part 20 and the sensing part 70 (neck part 20 and elastic deformation part 90) is improved.

[0060] Fig. 5 is a partial front view of the periphery of the hard part 70H of the sensing unit 70. Fig. 6 is a partial side view of the periphery of the hard part 70H of the sensing unit 70. As shown in FIG. 5, the hard portion 70H is formed in a rectangular shape in a plan view, connecting the hard portion 20H, which is the neck portion 20, and the hard portion 30H of the grip portion 30 in the long axis direction.

[0061] As shown in FIG. 6, the front end of the hard portion 70H is connected to the hard portion 20H by a curved surface 73H that is arc-shaped in a side view. The rear end of the hard portion 70H is connected to the hard portion 30H by a curved surface 74H that is arc-shaped in a side view. The arc centers of the curved surfaces 73H and 74H are located closer to the front than the hard portion 70H in a side view. The front end of the hard portion 70H is connected to the hard portion 20H by a curved surface 75H that is arc-shaped in a side view. The rear end of the hard portion 70H is connected to the hard portion 30H by a curved surface 76H that is arc-shaped in a side view. The arc centers of the curved surfaces 75H and 76H are located closer to the rear than the hard portion 70H in a side view.

[0062] If the curved surfaces 73H-76H were not present, stress would likely concentrate at the boundary between the tip side of the hard portion 70H and the hard portion 20H, and at the boundary between the rear end side of the hard portion 70H and the hard portion 30H. In contrast, the presence of the curved surfaces 73H-76H alleviates the concentrated stress. Furthermore, the presence of the curved surfaces 73H-76H allows both the elastically deforming portion 90 and the tip and rear end sides of the inverted portion 80 to deform flexibly (the degree of deformation of the elastically deforming portion 90, which is the trigger for inversion, can be sensed more precisely).

[0063] The hard portion 70H has through holes 73 provided on both sides of the inverted portion 80 in the width direction. The through holes 73 each extend in the long axis direction. The long axis length of the through hole 73 is the length at which the tip end of the through hole 73 is separated from the hard portion 20H and the rear end of the through hole 73 is separated from the hard portion 30H. As shown in FIG. 3, the soft portion 90E is provided in the through hole 73 closer to the hard portion 90H in the width direction, and the through hole K is formed closer to the inverted portion 80 in the width direction.

[0064] In the hard part 70H, the hard part 90H is arranged on both sides of the inverted part 80 in the width direction through the through holes 73, so that even if a load is applied and the elastic deformation part 90 is deformed, the shape of the inverted part 80 can be maintained. When the hard part H constituting the toothbrush 1 over its entire length is bent, the inverted part 80 of the sensing part 70 is inverted in an attempt to release the accumulated strain energy. For example, if the hard part 70H is connected to the neck part 20 and the grip part 30 only by the inverted part 80, the energy cannot be accumulated and the inverted part will be inverted immediately. If the inverted part 80 is injection molded integrally with the first region A1 and the second region A2 described later, as well as the neck part 20, the grip part 30, and the hard part 70H, the accumulated strain energy can be efficiently transmitted to the inverted part.

[0065] The hard portion 90H is formed on the outer side of the through hole 73 in the width direction of the hard portion 70H. As shown in FIG. 3, the hard portion 90H has a substantially rectangular cross-sectional shape. The hard portion 90H is embedded in the soft portion 90E. Since the hard portion 90H is embedded in the soft portion 90E, the stress applied to the hard portion 90H can be alleviated in terms of strength. In addition, in terms of the degree of bending of the toothbrush 1 in response to a load, the elastic behavior of the elastically deforming portion 90 can be controlled. In addition, the bending anisotropy in the sensing portion 70 is increased, and for example, it becomes possible to bend the elastically deforming portion 90 in response to the movement during brushing without twisting in the thickness direction.

[0066] As an example of the material of the hard portion H, there is a resin having a flexural modulus (JIS7171) of 1500 MPa or more and 3500 MPa or less, for example, polyacetal resin (POM). The flexural modulus of the hard portion H is more preferably 2000 MPa or more and 3500 MPa or less. By using a material with a high elastic modulus (for example, POM), even if the shape is made thin or slender, snap-through buckling occurs when an excessive load is applied, resulting in vibration. In addition, by using a material with a high elastic modulus, it is possible to quickly return to the initial state (a state in which the deflection of the elastic deformation portion 90 is released) after snap-through buckling occurs.

[0067] As a material for the soft part E, a material having a Shore hardness A of 90 or less is preferable, and a material having a Shore hardness A of 50 to 80 is more preferable, because the load at which snap-through buckling occurs is close to the value of the recommended brushing load. Examples of soft resins include elastomers (e.g., olefin-based elastomers, styrene-based elastomers, polyester-based elastomers, polyurethane-based thermoplastic elastomers, etc.) and silicones. Styrene-based elastomers are preferable because of their excellent miscibility with polyacetal resins.

[0068] As shown in Fig. 5, the inverted portion 80 extends in the long axis direction in front view, and connects a first region A1 on the tip side of the through hole 73 in the hard portion 70H with a second region A2 on the rear end side of the through hole 73. In a first stable state (hereinafter referred to as the first state) shown in Fig. 4 in which no external force is applied to the head portion 10 toward the rear side (or an external force equal to or less than a predetermined threshold value described later is applied), the inverted portion 80 is formed in a substantially V-shape in side view that gradually inclines toward the rear side from both ends in the long axis direction toward the center. That is, in the first state, the inverted portion 80 is formed in a convex shape on the rear side with the center in the long axis direction as the apex.

[0069] For example, when an external force is applied to the rear side of the head portion 10 while the gripping portion 30 is being gripped, if the magnitude of the external force is below a predetermined threshold value, the elastic deformation portion 90 and the inversion portion 80 elastically deform in accordance with the magnitude of the external force.

[0070] When the magnitude of the external force exceeds a predetermined threshold, the elastic deformation portion 90 bends and elastically deforms according to the magnitude of the external force that exceeds the threshold. On the other hand, when the magnitude of the external force exceeds the predetermined threshold, the inverted portion 80, as shown by the two-dot chain line in FIG. 7, snaps through and inverts when the neck portion 20 is deformed, and enters a second stable state (hereinafter referred to as the second state). In the second state, the inverted portion 80 inverts in a direction that gradually inclines toward the front side as it approaches the center, forming a substantially inverted V shape in side view. In the second state, the inverted portion 80 is formed in a convex shape toward the front side, with the center in the long axis direction being the apex.

[0071] That is, when the magnitude of the external force exceeds a predetermined threshold value, the elastic deformation portion 90 is elastically deformed, and the reversal portion 80 jumps from the first state, buckles, and reverses to the second state while the bending strength of the sensing portion 70 is guaranteed. In addition, since the through hole K is provided between the reversal portion 80 and the elastic deformation portion 90, the reversal portion 80 and the elastic deformation portion 90 can be deformed independently of each other, and the reversal portion 80 can be easily reversed. In other words, since the through hole K is provided, when the brushing load is applied, the reversal portion 80 can bend after the elastic member 90 is bent without hindering the deformation behavior of each other. Note that the reversal portion 80 and the elastic deformation portion 90 do not necessarily need to be penetrated, and it is sufficient that a gap S is formed.

[0072] The vibration generated when the inversion portion 80 jumps through, buckles, and inverts allows the user holding the grip portion 30 to sense that the external force acting on the back side of the head portion 10 has exceeded a threshold value, resulting in an overbrushing state.

[0073] The inverted portion 80 has a groove portion 81 in the center of the long axis direction on the front side, that is, in a region including the apex of the convex shape. The inverted portion 80 has a groove portion 82 in the center of the long axis direction on the back side, that is, in a region including the apex of the convex shape. The groove portions 81 and 82 extend in the width direction. The groove portion 81 is formed in an arc shape in a side view with the arc center located on the front side. The groove portion 82 is formed in an arc shape in a side view with the arc center located on the back side. If the groove portions 81 and 82 are not provided in the inverted portion 80, stress is generated uniformly throughout the inverted portion 80, making it difficult for snap-through buckling to occur. On the other hand, if the grooves 81 and 82 are provided in the inverted portion 80, stress is generated intensively in the groove portions 81 and 82, making it easier for snap-through buckling to occur.

[0074] The radius of the grooves 81, 82, which are arc-shaped in side view, is preferably 1 mm or more and 2 mm or less. If the radius of the grooves 81, 82 is less than 1 mm, the reversing portion 80 may not be reversed. If the radius of the grooves 81, 82 exceeds 2 mm, the vibration of the reversing portion 80 when reversing may be small, making it difficult to sense the overbrushing state.

[0075] Regarding the depth of groove portions 81 and 82, it is preferable that groove portion 81 is deeper than groove portion 82. When groove portion 82 is deeper than groove portion 81, inversion portion 80 is less likely to invert even when the magnitude of an external force exceeds a predetermined threshold value. Also, when groove portion 81 is deeper than groove portion 82, it is possible to induce inversion portion 80 to be more likely to snap-through buckling toward the front side. It is to be noted that instead of providing both the grooves 81 and 82, a configuration in which only the groove 81 is provided without providing the groove 82 may also be used.

[0076] Since the grooves 81 and 82 are provided in the region including the apex of the convex shape of the inverted portion 80, the region including the apex of the convex shape becomes thinner than other regions. Therefore, the strain energy accumulated due to the deformation of the inverted portion 80 caused by an external force exceeding a threshold value can be instantly released from the grooves 81 and 82 as a starting point, thereby inverting the inverted portion 80. In addition, by adjusting the positions of the grooves 81 and 82 in the thickness direction, it becomes possible to adjust the position where the inverted portion 80 inverts from the first state to the second state.

[0077] In addition, since groove portions 81 and 82 are formed in an arc shape when viewed from the side, stress concentration at the apex of inversion portion 80 including groove portions 81 and 82 can be alleviated even when the apex moves in the thickness direction, compared to, for example, a case in which groove portions 81 and 82 are formed in a V shape by two intersecting planes.

[0078] The threshold value of the external force applied to the rear side of the head portion 10 is, for example, the upper limit of the appropriate brushing pressure.

[0079] As shown in FIG. 4, the inclination angle θ of the inverted portion 80 with respect to a plane parallel to the long axis direction and the width direction is preferably 5 degrees or more and 11 degrees or less, and more preferably 7 degrees or more and 11 degrees or less. If the inclination angle θ is less than 5 degrees, the inverted portion 80 may deform without snap-through buckling, making it difficult to detect the overbrushing state. If the inclination angle θ exceeds 11 degrees, the inverted portion 80 may snap-through buckle and become difficult to invert due to overbrushing pressure, or the inverted portion 80 may break when snap-through buckling occurs and become inverted, resulting in loss of reversibility.

[0080] The thickness of the inverted portion 80 is preferably 1 mm or more and 2 mm or less, excluding the grooves 81 and 82. If the thickness of the inverted portion 80 is less than 1 mm, it may deform but not snap-through buckle, making it difficult to detect the overbrushing state. If the thickness of the inverted portion 80 exceeds 2 mm, it may become difficult for the inverted portion 80 to snap-through buckle and invert due to overbrushing pressure, or it may break when the inverted portion 80 snaps through and inverts, resulting in no reversibility.

[0081] If the maximum thickness of the inverted portion 80 is T (mm) and the maximum thickness of the sensing portion 70 is t (mm), then by defining the value represented by T / t, it becomes possible to control the ease with which the inverted portion 80 inverts when an excessive brushing load is applied, and the timing (threshold value) of the inversion. The value represented by T / t is preferably 0.05 or more and 0.35 or less, and more preferably 0.10 or more and 0.35 or less. When the value represented by T / t is less than 0.05, the inverted portion 80 also deforms in a manner following the bending of the sensing portion 70 (elastic deformation portion 90), but does not buckle by snap-through, so that it may be difficult to detect the overbrushing state. When the value represented by T / t exceeds 0.35, it may be difficult for the inverted portion 80 to snap-through buckle and invert due to the overbrushing pressure, or it may break when snap-through buckling and inverting, resulting in the inversion portion 80 losing its reversibility.

[0082] That is, by setting T / t within the above range, the bending strength of the inverted part 80 becomes flexible at a constant rate with respect to the elastic deformation part 90, and it becomes possible to operate the inverted part 80 with a slight delay with respect to the bending of the elastic deformation part 90 which supports the handle skeleton. This makes it possible to control the ease with which the inverted part 80 turns over and the timing (threshold value) that triggers the inversion of the inverted part 80 even when an excessive brushing load is applied.

[0083] As shown in FIG. 3, if the maximum width of the reversing portion 80 is L (mm) and the maximum width of the sensing portion 70 is W (mm), then by defining the value represented by L / W, it becomes possible to control, for example, the ease with which the reversing portion 80 reverses when an excessive brushing load is applied, and the timing (threshold value) of the reversing portion 80 reverses. The value represented by L / W is preferably 0.05 or more and 0.35 or less, and more preferably 0.10 or more and 0.35 or less. When the value represented by L / W is less than 0.05, the reversing portion 80 also deforms in a manner that follows the bending of the sensing portion 70 (elastic deformation portion 90), but it is difficult to cause snap-through buckling, and it may be difficult to detect an overbrushing state. When the value represented by L / W exceeds 0.35, the reversing portion 80 becomes difficult to deform and reverse due to the bending of the handle body 2 that occurs within the range of normal brushing. Therefore, the inversion part 80 may snap-through buckle under overbrushing pressure, making it difficult to invert, or may break when snap-through buckling occurs and the inversion part 80 loses its reversibility. That is, by setting L / W within the above range, the bending strength of the inversion part 80 becomes flexible at a certain rate relative to the elastic deformation part 90, and it becomes possible to operate the inversion part 80 with a slight delay relative to the bending of the elastic deformation part 90 that supports the handle skeleton. Therefore, even when an excessive brushing load is applied, it becomes possible to control the ease of inversion of the inversion part 80 and the timing (threshold value) that triggers the inversion of the inversion part 80.

[0084] The length of the inverted portion 80 in the long axis direction is 15 mm or more and 30 mm or less. Preferably, it is 15 mm or more and 25 mm or less, more preferably 15 mm or more and 20 mm or less. The position of the tip end of the inverted portion 80 is the position of the tip end of the through hole 73. The position of the rear end of the inverted portion 80 is the position of the rear end of the through hole 73. If the length of the inverted portion 80 in the long axis direction is less than 15 mm, it may be difficult for the inverted portion 80 to snap-through buckle and be inverted with normal brushing pressure, and it may not be possible to generate the deformation required for the snap-through buckling to occur. If the length of the inverted portion 80 in the long axis direction exceeds 30 mm, the displacement required for the snap-through buckling to occur becomes very large, so that the usability is greatly reduced, and the deformation behavior of the inverted portion 80 may be similar to that of the elastic deformation portion 90.

[0085] The inverted portion 80 is located between the outer contour of the bristle-implanted surface side 11 and the outer contour of the back side of the elastically deforming portion 90 in a side view. More specifically, the position of the inverted portion 80 in the thickness direction is set to a position that does not protrude from the thickness of the elastically deforming portion 90 in a side view so that the inverted portion 80 does not form the outermost contour of the toothbrush, thereby preventing the inverted portion from coming into contact with the user during use, for example. Specifically, it is preferable that the inverted portion 80 is located on the back side of the position where the thickness of the elastically deforming portion 90 is half. If the position of the inverted portion 80 in the thickness direction is located on the back side of the position where the thickness of the sensing portion 70 is half, when the inverted portion 80 is inverted to the second state, the possibility that the apex of the inverted portion 80 will protrude from the front surface of the elastically deforming portion 90 and come into contact with the user's finger can be reduced. Furthermore, by positioning the inversion portion 80 on the rear side of the position where the thickness of the elastic deformation portion 90 is half, when the inversion portion 80 bends, the rear side is compressed more than the front side. As a result, for example, energy that triggers inversion is more likely to accumulate, and the strain energy can be efficiently transferred to the inversion portion 80.

[0086] The flexural modulus of the hard resin constituting the inverted portion 80 is preferably 1500 MPa or more and 3500 MPa or less, and more preferably 2000 MPa or more and 3500 MPa or less. If the flexural modulus of the hard resin is less than 1500 MPa, the inverted portion 80 may deform but not snap-through buckle, making it difficult to sense that it is in an overbrushing state. If the flexural modulus of the hard resin exceeds 3500 MPa, the inverted portion 80 may snap-through buckle under overbrushing pressure, making it difficult to invert, or may break when snap-through buckled and inverted, causing the inverted portion 80 to lose its reversibility. In addition, by using a material with a specified flexural modulus, the vibration associated with snap-through buckling occurs intensively in a short period of time, making it sharp (sharp, large). As a result, the user can easily sense that he or she is overbrushing.

[0087] When the inverted portion 80 snaps, the thickness direction movement distance of the apex of the convex shape is preferably 0.2 mm or more and 5.0 mm or less. If the thickness direction movement distance of the apex is less than 0.2 mm, the vibration when snap buckling occurs is small, and it may be difficult to detect the overbrushing state. If the thickness direction movement distance of the apex exceeds 5.0 mm, it may be difficult for the inverted portion 80 to snap buckle and be inverted by the overbrushing pressure, or it may break when snap buckled and inverted, and the reversibility of the inverted portion 80 may be lost. If the movement distance of the inverted portion 80 when snap buckling is within the above range, the vibration generated by snap buckling occurs intensively in a short time and becomes sharp (sharp, large). As a result, the user can easily detect overbrushing.

[0088] The thickness of the hard portion 90H in the elastic deformation portion 90 is 2.0 mm or less, and it is preferable that the width is greater than the thickness. When the thickness of the hard portion 90H is 2.0 mm or less, the hard portion 90H is in a plane stress state, so that the hard portion 90H is less likely to generate internal stress. As a result, even if the hard portion 90H is deformed, it is less likely to break, and it is possible to sufficiently accumulate the energy required for the inversion of the inversion portion 80.

[0089] In addition, in the toothbrush 1 of this embodiment, the inverted portion 80 and the elastically deforming portion 90 are arranged with a gap in the width direction, so that the sensing portion 70 can be easily deformed in the front and back sides, and can be in a plane stress state where it is hardly deformed in the long axis direction and width direction. That is, in the toothbrush 1 of this embodiment, the direction in which the inverted portion 80 and the elastically deforming portion 90 deform is the thickness direction separated from each other in the width direction, and they are configured not to be on the same plane. In other words, the path in which the elastically deforming portion 90 deforms due to an external force in the thickness direction and the path in which the inverted portion 80 deforms due to an external force in the thickness direction are provided so as not to interfere with each other. Therefore, in the toothbrush 1 of this embodiment, the elastically deforming portion 90 and the inverted portion 80 are less likely to be restricted by each other and can be deformed, so that it is possible to more fully accumulate the energy required for inverting the inverted portion 80, and stress is concentrated in the inverted portion 80 (especially the groove portions 81 and 82), resulting in sensitive snap-through buckling.

[0090] Furthermore, in the toothbrush 1 of the embodiment, because shaking in the width direction is suppressed, bending in the thickness direction caused by brushing can be transmitted to the inverted portion 80 without loss. Furthermore, by arranging the inverted portion 80 and the elastic deformation portion 90 in the width direction, it is possible to separate the bending of the elastic deformation portion 90 and the inversion of the inverted portion 80, and to shift the timing. If the elastic deformation portion 90 and the inverted portion 80 were arranged in the thickness direction, there is a possibility that the bending of the elastic deformation portion 90 and the inversion of the inverted portion 80 would hinder each other's roles.

[0091] As described above, in the toothbrush 1 of this embodiment, the elastic deformation portion 90, which elastically deforms at least until an external force is applied that causes the inverted portion 80 to snap-through buckle and reverse, and the inverted portion 80, which snap-through buckles and reverses when an external force on the rear side exceeds a threshold value, are arranged with a gap in the width direction.Therefore, when an external force on the rear side exceeding a predetermined threshold value is applied to the head portion 10, the vibration caused by the inverted portion 80 snap-through buckling and reverses allows a user holding the grip portion 30 to sense that the external force applied to the head portion 10 on the rear side has exceeded the threshold value, indicating that the user is in an overbrushing state.

[0092] [Example] The present invention will be described in detail below with reference to examples. However, the present invention is not limited to the following examples and can be modified appropriately without departing from the gist of the present invention.

[0093] (Examples 1 to 9, Comparative Examples 1 to 4) According to the specifications shown in [Table 1], toothbrushes with different bending elastic modulus and inclination angle θ of the inverted portion 80 were used as samples for Examples 1 to 9 and Comparative Examples 1 to 4. For Comparative Example 1, a toothbrush (Clinica Advantage Toothbrush, manufactured by Lion Corporation) that does not have a sensing portion (inverted portion and elastically deforming portion) was used as a sample. For Comparative Example 2, a toothbrush in which the elastically deforming portion and the inverted portion are aligned in the thickness direction was used as a sample, compared to the sample for Example 2. For Comparative Example 3, a toothbrush in which there is no elastically deforming portion and the sensing portion is only the inverted portion was used as a sample, compared to the sample for Example 2. For Comparative Example 4, a toothbrush in which the elastically deforming portion and the inverted portion are joined and there is no gap between the elastically deforming portion and the inverted portion was used as a sample, compared to the sample for Example 2.

[0094] [Evaluation method] (1) Vibration at the inverted part [Test method] A panel of five experts brushed each sample and rated on a 5-point scale whether they felt any vibration when the tooth-turning part was turned over, and the average score was calculated as shown below. The average score was rounded off to the first decimal place and rounded down to the first decimal place. [Score] 5 points: Very sensitive, 4 points: Sensitive, 3 points: Slightly sensitive, 2 points: Not sensitive at all, 1 point: Not sensitive at all [Evaluation] ◎: 4.6 to 5 points, ○: 4.1 to 4.5 points, △: 3.1 to 4.0 points, ×: 3.0 points or less (2) Reversible inversion of the inversion part [Test method] A panel of five experts used each sample for one week and evaluated the presence or absence of reversal after one week. [Evaluation] ○: Inversion, ×: No inversion (× if even one line is inverted) (3) Vibration occurs at about 200-250g [Test method] For each sample, the gripping part 30 side was fixed from the boundary between the sensing part 70 and the gripping part 30 so that the bristled surface of the head part was horizontal. A test was conducted in which a load was applied to the back side in the thickness direction to the bristled surface of the head part. The presser of a push-pull gauge (DS2-50N, manufactured by IMADA) was used to press the center of the bristled surface of the head part as seen from the front, and the load was measured when the inverted part was inverted. The measurement was performed three times and the average value was rounded off to the nearest whole number. [Rating] ◎: 200-250g, ○: 251-300g, △: 150-199g, ×: 149g or less or 301g or more, -: No vibration The evaluation results were indicated as ◎, ○, and △ as passing (OK), and × as failing (NG). The evaluation of the measured load is based on the fact that by generating vibrations during inversion in the range of, for example, 230 to 250 g, the load applied when a user actually brushes with toothbrush 1 is the recommended value of 200 g.

[0095] As shown in Table 1, in the samples of Examples 1 to 9, in which the flexural modulus was 1500 MPa or more and 3500 MPa or less and the inclination angle θ of the inverted portion was 5 degrees or more and 11 degrees or less, it was confirmed that vibration associated with inversion of the inverted portion, reversible inversion of the inverted portion, and vibration under a load of approximately 200 to 250 g were sufficiently exhibited.

[0096] On the other hand, even if the flexural modulus is in the range of 1500 MPa or more and 3500 MPa or less, the sample of Comparative Example 1, which does not have a sensing part (reversed part and elastically deformed part), does not undergo reversal itself, and therefore, no vibration associated with reversal of the reversal part or vibration at a load of about 200 to 250 g occurs. Also, even if the elastic modulus is in the range of 1500 MPa or more and 3500 MPa or less, the inclination angle θ of the reversal part is in the range of 5 degrees or more and 11 degrees or less, and the value represented by T / t and the value represented by L / W are in the range of 0.05 or more and 0.35 or less, in both the sample of Comparative Example 2, in which the elastically deformed part and the reversal part are aligned in the thickness direction, and the sample of Comparative Example 3, which has a sensing part consisting only of the reversal part without the elastically deformed part, no vibration associated with reversal of the reversal part or vibration at a load of about 200 to 250 g occurs.

[0097] Furthermore, even when the elastic modulus was in the range of 1500 MPa or more and 3500 MPa or less, the inclination angle θ of the inverted portion was in the range of 5 degrees or more and 11 degrees or less, and the value expressed by T / t and the value expressed by L / W were in the range of 0.05 or more and 0.35 or less, for the sample of Comparative Example 4 having a sensing portion in which the elastic deformation portion and the inverted portion are joined with no gap between them, vibration occurred due to inversion of the inverted portion, but no vibration occurred at a load of approximately 200 to 250 g.

[0098] [Table 1]

[0099] Although the preferred embodiment of the present invention has been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to the examples. The shapes and combinations of the components shown in the above examples are merely examples, and various modifications can be made based on design requirements, etc., without departing from the spirit of the present invention.

[0100] For example, in the above embodiment, the sensing unit 70 is provided between the neck portion 20 and the grip portion 30, but is not limited to this configuration. The sensing unit 70 may be provided in the neck portion 20 or in the grip portion 30.

[0101] In addition, in the above embodiment, a configuration in which one reversing unit 80 is provided in the sensing unit 70 has been exemplified, but the present invention is not limited to this configuration, and a configuration in which a plurality of reversing units 80 are provided may also be used. For example, when two reversing portions 80 are provided, one is formed with a thickness, inclination angle θ, etc. that reverses at the upper limit of the appropriate brushing load, and the other is formed with a thickness, inclination angle θ, etc. that reverses at the lower limit of the appropriate brushing load, making it possible to easily specify both the upper and lower limits of the brushing load.

[0102] In the above embodiment, the reversing portion 80 is configured to be reversed in the thickness direction, but the present invention is not limited to this configuration, and may be configured to be reversed in the width direction or in an oblique direction perpendicular to the long axis direction and intersecting the width direction and thickness direction. By adopting a configuration in which the reversing portion 80 is reversed in an oblique direction, it becomes possible to detect over-brushing when brushing with the rolling method. [Industrial Applicability]

[0103] The present invention is applicable to toothbrushes. [Explanation of symbols]

[0104] REFERENCE SIGNS LIST 1...toothbrush, 2...handle body, 10...head portion, 11...bristle surface, 20...neck portion, 30...gripping portion, 70...sensing portion, 80...reversed portion, 81, 82...groove portion, E, 31E, 32E...soft portion, H...hard portion, K...through hole, S...gap

Claims

1. It has a head portion having a bristle surface provided on the tip side in the longitudinal direction, a gripping portion positioned at the rear end of the head portion, and a neck portion positioned between the bristle surface and the gripping portion. A sensing unit is provided at the rear end of the aforementioned bristled surface to detect when an external force in a first direction perpendicular to the bristled surface exceeds a threshold value. The sensing unit is A reversing section is provided that connects a first region on the tip side of the sensing section and a second region on the rear end side of the sensing section, and in response to the displacement of the head portion toward the back side, which is opposite to the flocked surface in the first direction, due to the external force exceeding the threshold, the reversing section jumps, buckles, and reverses, The reversal portion is positioned with a gap between it and the first region and the second region, and comprises an elastically deformable portion that elastically deforms at least until the external force causes the reversal portion to jump, buckle, and reverse, The inversion portion is located between the outer contour on the flocked surface side and the outer contour on the back side of the elastically deformable portion in a side view taken in a direction perpendicular to the long axis and the first direction, The reversing portion has grooves on the flocked surface side and the back side, respectively. A toothbrush characterized in that the groove on the bristle-planted surface is deeper than the groove on the back surface.

2. The toothbrush according to claim 1, characterized in that the path through which the elastic deformation portion deforms due to the external force in the first direction and the path through which the reversal portion deforms due to the external force in the first direction are provided in a non-interfering manner.

3. The elastic deformation portion and the reversal portion are arranged with a gap between them in a second direction that is perpendicular to the first direction and the long axis direction, respectively. The toothbrush according to claim 2.

4. The reversing portion is provided in the center of the second direction, The toothbrush according to claim 3, wherein the elastic deformation portion is provided on both sides of the reversal portion in the second direction.

5. The reversing portion is convex on the back side when the external force in the first direction is less than or equal to the threshold, and reverses to a convex shape on the flocked surface side when the external force in the first direction exceeds the threshold. The toothbrush according to any one of claims 1 to 4.

6. The inverting portion is inclined toward the flocked surface side as it moves from the apex of the convex shape toward the end in the longitudinal direction, when the external force in the first direction is less than or equal to the threshold, The angle at which the reversing portion is inclined with respect to a plane parallel to the first direction and the longitudinal axis is 5 degrees or more and 11 degrees or less. The toothbrush according to claim 5.

7. The inverted portion has the groove portion extending in a second direction perpendicular to the first direction and the longitudinal axis, respectively, in a region including the vertex of the convex shape. The toothbrush according to claim 5 or 6.

8. When the reversing portion jumps and buckles and reverses, the distance traveled by the vertex of the convex shape in the first direction is 0.2 mm or more and 5.0 mm or less. The toothbrush according to any one of claims 5 to 7.

9. The maximum thickness of the reversing portion in the first direction is T, If the maximum thickness of the elastically deformable portion in the first direction is t, The value expressed as T / t is between 0.05 and 0.

35. A toothbrush according to any one of claims 1 to 8.

10. The maximum width of the reversing portion in the second direction which is perpendicular to the first direction and the long axis direction, respectively, is L. If the maximum width of the elastically deformable portion in the second direction is W, The value expressed as L / W is between 0.05 and 0.

35. A toothbrush according to any one of claims 1 to 9.

11. The reversing portion is formed of a hard resin, A portion of the elastically deformable portion is formed of a resin with a different hardness than the hard resin. A toothbrush according to any one of claims 1 to 10.

12. The flexural modulus of the rigid resin is 1500 MPa or more and 3500 MPa or less. The toothbrush according to claim 11.

13. A portion of the elastically deformable portion is made of a soft resin. The toothbrush according to claim 11 or 12.

14. The gap is a through hole extending in the first direction. A toothbrush according to any one of claims 1 to 13.

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