toothbrush

Abstract

We offer a toothbrush that provides both a pleasant massage sensation and a feeling of thorough cleaning between teeth. [Solution] The head portion has a hair-planted surface, and in a front view from the front side facing the hair-planted surface, there are a plurality of hair-planted portions arranged in an independent planar shape on the hair-planted surface with a single bundle of hair. Each hair-planted portion has a central bundle of hair located in the central region of the hair-planted surface, and a plurality of peripheral bundles of hair spaced apart from the central bundle of hair and surrounding the central bundle of hair at intervals from each other. The central bundle of hair has a recess in the outer contour in a front view that is recessed in the direction away from the peripheral bundle of hair at a position facing at least one of the peripheral bundles of hair, and when the peripheral bundle facing the recess is bent by an external force, a portion of the opposing bundle of hair enters the recess.

Description

Technical Field

[0004]

[0001] The present invention relates to a toothbrush.

Background Art

[0002] As a method for manufacturing a toothbrush, a method is known in which tufts of bristles are inserted into a plurality of bristle insertion holes formed in advance on the bristle-inserting surface of the head portion and fixed with a flat wire. Further, a method of fixing the tufts to the head portion by heat fusion, a method by in-mold, etc. are known (for example, Patent Document 1). According to these methods, since the tufts can be fixed without using a flat wire, there is an advantage that tufts having various cross-sectional shapes can be implanted.

[0003] In order to improve the comfortable massage feeling of the gums in a toothbrush, it is effective to increase the bristle area that contacts the gums. As a means for this, implanting bristles at high density in large holes can be mentioned.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the conventional large-hole high-density specification has a problem that the tufts are rigid and difficult to bend, the force of pressing the gums with the tufts becomes strong, and it is difficult to obtain a comfortable massage feeling. Further, while the tooth surface is easy to polish, there is a problem that it is difficult for the bristles to enter narrow gaps such as between teeth and the cervical part of teeth, and thus a sufficient cleaning feeling cannot be obtained. Therefore, in order to improve the gap cleaning feeling, a method of reducing the area of each tuft is adopted by measures such as connecting a plurality of small holes to substantially form a large tuft, but a problem occurs that the bristles are bent too much and the massage feeling is impaired.

[0006] This invention was made with the above points in mind, and aims to provide a toothbrush that can achieve both a pleasant massage sensation and a sense of thorough cleaning of gaps between teeth. [Means for solving the problem]

[0007] The present invention has the following aspects. [1] A head portion having a bristle surface, In a front view from the front side facing the aforementioned hair-planted surface, the hair-planted surface is provided with a plurality of hair-planted sections arranged in an independent planar manner with a single bundle of hair, Equipped with, The aforementioned hair follicle portion is, A central hair bundle is positioned in the central region of the aforementioned hair implantation surface, Multiple peripheral hair bundles are spaced apart from the central hair bundle and surround the central hair bundle at intervals from each other, It has, The central hair bundle has a recess in the front view outline that is recessed in a direction away from the surrounding hair bundle at a position opposite to at least one of the surrounding hair bundles, A toothbrush in which, among the surrounding bristle bundles, the opposing bristle bundles facing the recess partially enter the recess when bent by an external force. [2] The shortest distance between the opposing hair bundle and the recess is 0.5 mm or less. The toothbrush described in [1] above. [3] The opposing hair bundle has a projection that faces the recess and tapers towards the recess. The toothbrush described in [1] or [2] above. [4] The projection is in the shape of a circular arc with radius r, having its center of curvature on the side opposite to the recess in the front view. The radius of the virtual circle connecting one end of the outer contour of the recess in the front view, the other end, and the position furthest from the projection in the opposing direction of the opposing hair bundle and the recess is greater than or equal to the radius r. The toothbrush described in [3] above. [5] The aforementioned recess is provided in the outer contour of the central hair bundle that extends in the direction of the major axis when viewed from the front. A toothbrush as described in any one of the above items [1] to [4]. [6] At least two of the surrounding hair bundles have a second recess on the side opposite to the side facing the central hair bundle in the front view outline, The second recess is provided symmetrically with respect to the center line that is located in the center of the central hair bundle in the minor axis direction and extends in the major axis direction. The toothbrush described in [5] above. [7] The opposing hair bundles are arranged on both sides of the central hair bundle in the direction of its shorter axis, with the central hair bundle in between. On either side of the central hair bundle in the longitudinal direction, the first non-opposing hair bundles from the peripheral hair bundles that are not facing the recess are respectively arranged. On both sides of the central hair bundle, in diagonal directions that intersect both the major and minor axes, a second non-opposing hair bundle from the peripheral hair bundle that is not facing the recess is positioned. The opposing hair bundles taper towards the central hair bundle, At least one of the first non-opposing hair bundle and the second non-opposing hair bundle tapers towards the central hair bundle. The toothbrush described in [5] or [6] above. [8] Among the surrounding hair bundles, the non-opposing hair bundles that are not facing the recess and are adjacent to the opposing hair bundles have protrusions that taper towards the central hair bundle. The central bundle of hair has a protrusion at a position opposite to the projection. A toothbrush as described in any one of the above items [1] to [7]. [Effects of the Invention]

[0008] This invention provides a toothbrush that offers both a pleasant massage sensation and a feeling of thorough cleaning of gaps between teeth. [Brief explanation of the drawing]

[0009] [Figure 1]It is a partial front view of the toothbrush 1 according to the first embodiment. [Figure 2] It is a partially enlarged view around the central bristle bundle 20. [Figure 3] It is a partial front view of the toothbrush 1 according to the second embodiment.

Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments of the toothbrush of the present invention will be described with reference to FIGS. 1 to 3. The following embodiments show one aspect of the present invention, do not limit this invention, and can be arbitrarily changed within the scope of the technical idea of the present invention. Also, in the following drawings, in order to make each configuration easy to understand, the actual structure, the scale, the number, etc. in each structure are made different.

[0011] [First Embodiment of Toothbrush] FIG. 1 is a partial front view of the toothbrush 1 according to the first embodiment. FIG. 2 is a partially enlarged view around the central bristle bundle 20 described later. As shown in FIGS. 1 and 2, the toothbrush 1 has a head portion 3 having a bristle planting surface 2 and a handle portion 4 connected to the head portion 3. The head portion 3 has the bristle planting surface 2 on the front side. The head portion 3 is located on the distal end side in the longitudinal axis direction (the vertical direction in FIG. 1) of the handle portion 4.

[0012] In the following description, the direction parallel to the bristle planting surface 2 and orthogonal to the longitudinal axis direction (the left - right direction in FIG. 1) will be described as the width direction. Among the width direction, in FIG. 1, the left side may be referred to as one side of the width direction, and the right side in FIG. 1 may be referred to as the other side of the width direction. Also, the side facing the bristle planting surface 2 is appropriately described as the front side, and the side opposite to the front side is described as the back side. Regarding the longitudinal axis direction, the side where the head portion 3 is arranged with respect to the handle portion 4 is the distal end side, and the side where the handle portion 4 is arranged is the rear end side.

[0013] The head portion 3, when viewed from the front, extends in the direction of its long axis and is, for example, oval in shape. The front view shape of the head portion 3 is not limited to oval, and any shape such as elliptical or rectangular can be selected. The head portion 3 has multiple bristle portions 10 on the bristle surface 2. The bristle portions 10 are provided in an independent planar shape with a single bundle of hair.

[0014] The hair implantation section 10 comprises a central hair bundle 20 and multiple peripheral hair bundles 30. The central hair bundle 20 is positioned in the central region 10A of the hair implantation surface 2. The peripheral hair bundles 30 are positioned at intervals from the central hair bundle 20. Multiple peripheral hair bundles 30 (eight in Figure 1) are positioned around the central hair bundle. The peripheral hair bundles 30 are positioned at intervals from each other.

[0015] The central bristle bundle 20 is oval-shaped when viewed from the front, with its major axis running along its long axis. In other words, the maximum dimension of the central bristle bundle 20 in the long axis direction is longer than the maximum dimension in the short axis direction. The center of the central bristle bundle 20 in the short axis direction is located in the center of the width direction of the toothbrush 1 and is at the same position as the center line J that extends in the long axis direction.

[0016] The central hair bundle 20 has a recess 21 and a protrusion 22. The recess 21 is located opposite at least one of the peripheral hair bundles 30. The recess 21 is located on the outer contour of the central hair bundle 20 that extends in the major axis direction when viewed from the front. The recess 21 is located on both sides of the outer contour in the minor axis direction. The recess 21 is concave on the inside in the minor axis direction and concave on the outside in the minor axis direction. The recess 21 is an arc shape with its center of curvature on the outside in the minor axis direction. The recess 21 may also have a straight portion.

[0017] The recess 21 preferably intersects with the vertex of the central hair bundle 20. In other words, it is preferable that the recess 21 is formed by intersecting with the vertex where the arc portion and the straight portion intersect with a hypothetical ellipse in which the recess 21 is not formed. The convex portion 22 of the central hair bundle 20 promotes twisting behavior by contacting the surrounding hair bundles 30, so the thinner the convex portion 22, the more effective it is. For this reason, it is preferable that the central hair bundle 20 is concave from the top.

[0018] The protrusions 22 are formed by arcs that are located at both ends in the major axis direction of the oval-shaped central hair bundle 20 and project outward. The protrusions 22 include a chamfer formed at the intersection of the arc that projects outward in a front view and the arc that forms the outer contour of the recess 21.

[0019] In the convex portion 22, the intersection region where it intersects with the recess 21 is thinner compared to other parts of the central bristle bundle 20 because the intersection angle between the arc of the convex portion 22 and the arc forming the recess 21 is small. This makes it more flexible when external force is applied during brushing. Therefore, for example, when polishing the occlusal surface, it becomes possible to clean the uneven surface while maintaining the feeling of plaque removal, thus improving cleaning power.

[0020] Furthermore, regarding the tips of the central hair bundle 20, in the case of a multi-pronged profile where the hair length is longest in the center and shortest at the edges, the hair length is shorter at the edges of the central hair bundle 20 and it is less prone to bending. Therefore, by providing a recess 21 at the edge of the hair bundle, the hair becomes more prone to bending. This allows for cleaning of uneven surfaces while maintaining cleaning power, such as the feeling of surface plaque removal when polishing the occlusal surface.

[0021] The peripheral hair bundle 30 includes an opposing hair bundle 40, a first non-opposing hair bundle 50, and a second non-opposing hair bundle 60. The opposing hair bundle 40 is spaced apart on both sides of the central hair bundle 20 in the minor axis direction. The opposing hair bundle 40 faces the recess 21 in the minor axis direction. That is, the recess 21 is recessed in the peripheral hair bundle 30 in the direction away from the opposing hair bundle 40. The opposing hair bundle 40 has a roughly triangular shape, with its maximum length in the major axis direction gradually decreasing from the outside in the minor axis direction toward the central hair bundle 20.

[0022] As shown in Figure 2, the opposing bristle bundle 40 has a projection 41 at its inner end in the minor axis direction. The projection 41 is arc-shaped with its center of curvature opposite the recess 21 in a front view. The projection 41 is arc-shaped, facing the recess 21 and tapering towards the recess 21. When the opposing bristle bundle 40 is bent by an external force, a portion of it (the projection 41) enters the recess 21. When the opposing bristle bundle 40 is moved in the minor axis direction due to an external force applied during brushing, the projection 41, which is part of the outer contour, enters the recess region 21a without interference between the outer contours of the central bristle bundle 20 and the opposing bristle bundle 40. The recess region 21a is the area enclosed by the arc that forms the outer contour of the recess 21 and the line segment connecting one end and the other end of the arc.

[0023] When the gaps between the bristle bundles narrow, the area becomes denser, enhancing the massage sensation. On the other hand, the bristles in the bundles become less flexible, which may reduce the cleaning sensation. By having the central bristle bundle 20 have a recess 21, and the opposing bristle bundle 40 fitting into the recess 21, it is possible to maintain high density while creating areas that are more flexible (the intersection of the convex part 22 and the recess 21), thereby achieving both a massage sensation and cleaning power.

[0024] Furthermore, if the central bristle bundle 20 has a recess 21 and the surrounding bristle bundles 30 are shaped to fit into the recess 21, the bending of one bristle bundle is more likely to come into contact with the other bristle bundle, and the direction of that bending changes. Therefore, in addition to the complex bending originating from the shape of each bristle bundle, it is possible to further enhance the feeling of gum massage.

[0025] Furthermore, depending on the direction in which the hair strands bend, they may or may not move together as a single unit when they enter a recess. Therefore, while maintaining high density, users can recognize the shape of each hair strand and experience the different movements of each strand while massaging. Specifically, when massaging the gums with the entire head 3 after brushing, the central bristle bundle 20 and the surrounding bristle bundle 30 move together as a unit, and the combination of bending and twisting of the bristles enhances the massage sensation.

[0026] If the radius of the projection 41 is r, it is preferable that the radius R of the virtual circle (in this embodiment, the arc forming the outer contour of the recess 21) connecting one end of the arc forming the outer contour of the recess 21, the other end, and the position furthest from the projection 41 in the opposing direction of the opposing hair bundle 40 and the recess 21 is greater than or equal to the radius r. By having a radius R greater than or equal to radius r, the opposing hair bundles 40 can enter the recess 21, maintaining high density and enhancing the massage sensation.

[0027] Furthermore, the wider the hair bundle, the more difficult it is for the hair bundle to move in that direction. Therefore, by providing a recess 21 in the outer contour of the central hair bundle 20 that extends in the long axis direction when viewed from the front, the protrusion 22 can be bent (twisted) in the circumferential direction along the arc, starting from the most recessed point in the recess 21. This promotes bending in the direction of the longer hair bundle, even while maintaining high density. This allows for the removal of plaque from the occlusal surface while maintaining a sense of surface cleanliness, enabling a balance between a massage-like sensation and effective cleaning.

[0028] The shortest distance t between the opposing hair bundle 40 and the recess 21, that is, the shortest distance t between the projection 41 and the recess 21, is preferably 0.5 mm or less. If the shortest distance t exceeds 0.5 mm, even if external force is applied during brushing of the opposing hair bundle 40 and the opposing hair bundle 40 enters the recess 21, there may be insufficient contact, resulting in an unsatisfactory massage sensation. By setting the shortest distance t to 0.5 mm or less, sufficient contact is achieved when the opposing hair bundle 40 enters the recess 21, thereby enhancing the massage sensation.

[0029] The first non-opposing hair bundles 50 are arranged in pairs on both sides of the central hair bundle 20 in the long-axis direction. The first non-opposing hair bundles 50 are not opposite to the recess 21. The second non-opposing hair bundles 60 are arranged in pairs on both sides of the central hair bundle 20 in the diagonal direction that intersects both the long-axis and short-axis directions. The second non-opposing hair bundles 60 are not opposite to the recess 21.

[0030] Among the peripheral hair bundles 30, the second non-opposing hair bundle 60 adjacent to the opposing hair bundle 40 has a projection 61 that tapers towards the central hair bundle. The projection 61 faces the convex portion 22. The protrusion 61 faces the convex portion 22, allowing the second non-facing bristle bundle 60 to efficiently and precisely contact the convex portion 22 of the central bristle bundle 20. This promotes the twisting motion of the convex portion 22, enhancing the cleaning sensation while maintaining the massage sensation.

[0031] The surrounding hair bundles 30, including the opposing hair bundle 40, the first non-opposing hair bundle 50, and the second non-opposing hair bundle 60, taper towards the central hair bundle 20. The surrounding hair bundles 30 are positioned around the central hair bundle 20, and as they taper towards the central hair bundle 20, the area where the central hair bundle 20 and the surrounding hair bundles 30 come into contact and become the densest is more prone to bending. Furthermore, because the opposing bristle bundles 40 that enter the recess 21 are located on both sides of the central bristle bundle 20 in the width direction, the protrusions 61 come into contact with the central bristle bundle 20, promoting twisting behavior, thus enhancing the feeling of cleaning while maintaining the feeling of massage. In addition, because the opposing bristle bundles 40, the first non-opposing bristle bundle 50, and the second non-opposing bristle bundle 60, which have different shapes, are arranged around the central bristle bundle 20, the bending of the bristles can be felt by the gums and perceived as a feeling of massage. Moreover, because the surrounding bristle bundles 30 taper towards the central bristle bundle 20, the distribution of bending of the bristle bundles becomes larger in terms of shape, and the twisting effect is enhanced compared to cases where there is no tapering shape.

[0032] At least two of the peripheral hair bundles 30 have a second recess on the side opposite to the side facing the central hair bundle in the outer contour when viewed from the front. In this embodiment, the opposing hair bundle 40 has a second recess 42, and the first non-opposing hair bundle 50 has a second recess 51. The second recess 42 and the second recess 51 are provided symmetrically with respect to the center line J. When the central bristle bundle 20 and the surrounding bristle bundles 30 move together due to the recess 21 in the central bristle bundle 20 and the protrusion 41 in the opposing bristle bundle 40, the outer surfaces of the opposing bristle bundle 40 and the first non-opposing bristle bundle 50 are recessed, increasing their flexibility and enabling a balance between a cleaning sensation and a massage sensation. Furthermore, the second recesses 42 and 51 are positioned symmetrically with respect to the center line J, making it easier to recognize the shape of the bristle bundles, for example, enhancing the feeling of enveloping the gums.

[0033] The second recess 42 forms the outermost outer edge of the opposing hair bundle 40 in the short-axis direction, and it is preferable that a portion of it is recessed. It is more preferable that the maximum dimension of the second recess 42 in the long-axis direction is less than 50% of the maximum dimension of the opposing hair bundle 40 in the long-axis direction. It is preferable that the maximum dimension of the second recess 42 in the long-axis direction is shorter than the maximum dimension of the outer edge line (projection 41) closer to the central hair bundle 20 in the long-axis direction. The opposing bristle bundle 40 has a second recess 42 on its outer side, as well as a protrusion 22. Unlike the central bristle bundle 20, by leaving the outermost line intact and recessing a portion of it, the bristle bundle shape is less likely to collapse, and by maintaining the bristle bundle shape, the gum massage effect can be enhanced by the surface derived from the bristle bundle shape.

[0034] The second recess 51 forms the outermost edge of the first non-opposing bristle bundle 50 in the long axis direction, and it is preferable that a portion of it is recessed. More preferably, the maximum dimension of the second recess 51 in the short axis direction is less than 50% of the maximum dimension of the first non-opposing bristle bundle 50 in the short axis direction. It is preferable that the maximum dimension of the second recess 51 in the short axis direction is shorter than the outer edge line closer to the central bristle bundle 20. The first non-opposing bristle bundle 50 has the second recess 51 on its outside. Unlike the central bristle bundle 20, the opposing bristle bundle 40 and the first non-opposing bristle bundle 50 retain their outermost edge line and are partially recessed, making it less likely for the bristle bundle shape to collapse and enhancing the gum massage effect on surfaces derived from the bristle bundle shape.

[0035] The depth of the second recess 42 is preferably shorter than the straight distance of the outermost outer edge in the minor axis direction of the opposing hair bundle 40 that is not recessed, and more preferably longer than the depth of the recess 21 of the central hair bundle 20. The depth of the second recess 51 is preferably shorter than the straight distance of the outermost outer edge in the major axis direction of the first non-opposing hair bundle 50 that is not recessed, and more preferably longer than the depth of the recess 21 of the central hair bundle 20. The protrusions created on the opposing hair bundle 40 by the second recess 42 and the protrusions created on the first non-opposing hair bundle 50 by the second recess 51 are less prone to twisting due to contact with other hair bundles compared to the central hair bundle 20, so increasing the depth of the recess makes them more flexible.

[0036] As shown in Figure 1, it is preferable that the curve or line segment L forming the recess 21 of the central hair bundle 20 overlaps with the line segment of the second non-opposing hair bundle 60 closer to the opposing hair bundle 40 when extended. More preferably, the first groove 71 between the opposing hair bundle 40 and the second non-opposing hair bundle 60 and the second groove 72 between the central hair bundle 20 and the opposing hair bundle 40 have the same width. When line L is extended, it overlaps with the line segment of the second non-opposing hair bundle 60 closer to the opposing hair bundle 40, allowing the second non-opposing hair bundle 60 to contact the convex portion 22 of the central hair bundle 20 more efficiently, thereby promoting the twisting behavior of the convex portion 22. Furthermore, by making the widths of the first groove 71 and the second groove 72 the same, even if each hair bundle moves in a complex manner, the overall texture is unified, improving the massage sensation.

[0037] Since the surrounding hair bundles 30 that interact with the central hair bundle 20 are easily flexible, it is preferable that the area of ​​the central hair bundle 20 is the largest in the implanted hair section 10 when viewed from the front, as this promotes the twisting behavior of the convex portion 22 caused by the recess 21.

[0038] It is preferable that the area of ​​the first non-opposing hair bundle 50, which does not enter the recess 21 and is not located in the direction of extension of the line L involved in the recess 21, is the largest among the surrounding hair bundles 30. This results in the presence of relatively large, less flexible bristle bundles, allowing a single head unit 3 to possess multiple types of flexibility characteristics, thereby improving cleaning power. In other words, by surrounding the central bristle bundle 20 with at least two or more types of surrounding bristle bundles 30, a complex bending behavior is achieved, which allows for both effective cleaning (tooth surface and fine gaps) and a massage-like sensation.

[0039] The bristles that make up the central bristle bundle 20 and the surrounding bristle bundles 30 include straight bristles, bristles whose diameter gradually decreases towards the tip (tapered bristles), branched bristles, spiral bristles, and bristles with irregular cross-sections. From the viewpoint of cleaning effectiveness around orthodontic appliances and the gingival margin, tapered bristles are preferable for making up the bristle bundles. By using tapered bristles, it is possible to ensure scraping power while allowing the bristles to reach even small areas and improving the cleaning effect. The tip shape of the bristle bundles includes flat cuts, mountain cuts, convex shapes, and concave shapes. By making the tip shape of the bristle bundle mountain cut or hill-shaped, it is possible to reach even small areas and improve the cleaning effect.

[0040] The bristles described above are not particularly limited in terms of material, but examples include synthetic resin materials such as polyamide (e.g., 6-12 nylon, 6-10 nylon), polyester (e.g., polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate), polyolefin (e.g., polypropylene), and elastomer (e.g., olefin-based, styrene-based). Furthermore, multiple resin materials may be used in combination, and different resin materials can be used for the core and sheath portions, for example, in a core-sheath structure.

[0041] The diameter of the bristles constituting the above-mentioned bristle bundle is, for example, 4 to 7 mil (1 mil = 1 / 1000 inch = 0.025 mm). If it is 4 mil or more, sufficient bristle stiffness is ensured to effectively clean the gingival margin, while if it is 7 mil or less, flexibility is ensured to reduce irritation to the gums, etc. Note that the bristle diameter in tapered bristles is the diameter at the base.

[0042] The material of the handle portion 4 is not particularly limited, but it is preferable to use, for example, polypropylene (PP) resin, polyacetal (POM) resin, polybutylene terephthalate (PBT) resin, polyethylene terephthalate (PET) resin, etc.

[0043] As a method for fixing the central bristle bundle 20 and the surrounding bristle bundles 30 to the bristle-planted surface 2, a heat fusion method (pressure-temperature-time (PTt) method) can be used, in which the molten portion of the lower end of the bristle bundle is pressed into the molten resin that will become the head portion 3 to fix it, or an in-mold method can be used, in which the lower end of the bristle bundle is heated to form a molten mass, and then the molten resin is injected into a mold to form the head portion.

[0044] As described above, in the toothbrush 1 of this embodiment, the central bristle bundle 20 has a recess 21 in its outer contour that is recessed away from the opposing bristle bundle 40 at a position opposite to the opposing bristle bundle 40. This makes the thin portion of the central bristle bundle 20 more flexible, allowing for cleaning of uneven surfaces while maintaining the feeling of plaque removal, thus improving cleaning power. In addition, in the toothbrush 1 of this embodiment, when the opposing bristle bundle 40 of the surrounding bristle bundle 30 that faces the recess 21 is bent by external force, a portion of it enters the recess 21, so the gaps between the bristle bundles become narrower and denser, enhancing the feeling of massage. Therefore, the toothbrush 1 of this embodiment can achieve both a pleasant massage sensation and a feeling of thorough cleaning of gaps between teeth.

[0045] [Second embodiment of a toothbrush] Next, a second embodiment of toothbrush 1 will be described with reference to Figure 3. In this figure, elements identical to those in the first embodiment shown in Figures 1 and 2 are denoted by the same reference numerals, and their descriptions are omitted. In the second embodiment, the number and shape of the recesses 21 and protrusions 41 differ from those in the first embodiment.

[0046] Figure 3 is a partial front view of the toothbrush 1 according to the second embodiment. The central hair bundle 20 of this embodiment has an outer contour formed by straight lines that taper outward in the direction of the major axis at both ends. There are four recesses 21 in total, two on each side of the central hair bundle 20 in the direction of the minor axis. On one side in the direction of the minor axis, the recesses 21 are spaced apart in the direction of the major axis. The outer contour of each recess 21 is formed by straight lines that taper inward in the direction of the minor axis.

[0047] The opposing hair bundle 40 has two protrusions 41. The two protrusions 41 are positioned opposite each other in the minor axis direction to two recesses 21 on one side of the central hair bundle 20. The other configurations are the same as those of the first embodiment described above.

[0048] In the toothbrush 1 with the above configuration, the number of thin-walled areas where the outer contours intersect on the outer side in the minor axis direction of the two grooves 21 aligned in the long axis direction increases, making it more flexible when external force is applied during brushing. In addition, as the number of grooves 21 formed in the central bristle bundle 20 increases, the protrusions 41 fit into the grooves 21, making the bristle bundle denser. Therefore, in addition to obtaining the same actions and effects as the first embodiment described above, the toothbrush 1 of this embodiment can exhibit an even stronger massage sensation and cleaning power.

[0049] Preferred embodiments of the present invention have been described above with reference to the attached drawings, but it goes without saying that the present invention is not limited to these examples. The shapes and combinations of the constituent members shown in the above examples are merely examples, and can be modified in various ways based on design requirements, etc., without departing from the spirit of the present invention.

[0050] For example, in the above embodiment, a configuration was illustrated in which the major axis direction of the central bristle bundle 20 coincides with the major axis direction of the toothbrush 1, and the minor axis direction of the central bristle bundle 20 coincides with the minor axis direction of the toothbrush 1, but the configuration is not limited to this. A configuration in which the major axis direction of the central bristle bundle 20 coincides with the minor axis direction of the toothbrush 1, and the minor axis direction of the central bristle bundle 20 coincides with the major axis direction of the toothbrush 1, is also possible.

[0051] Furthermore, the shapes of the recess 21 and projection 41 shown in the above embodiment are just examples, and various other shapes can be selected as long as a part of the opposing hair bundle 40 enters the recess 21 when it is bent by an external force. [Explanation of symbols]

[0052] 1...Toothbrush, 2...Bristle surface, 3...Head section, 4...Handle section, 10...Bristle section, 10A...Central area, 20...Central bristle bundle, 21...Indentation, 22...Convex section, 30...Peripheral bristle bundle, 40...Opposite bristle bundle, 41...Protrusion, 42...Second indentation, 50...First non-opposing bristle bundle, 60...Second non-opposing bristle bundle, 61...Protrusion

Claims

1. A head portion having a bristle surface, In a front view from the front side facing the aforementioned hair-planted surface, the hair-planted surface is provided with a plurality of hair-planted sections arranged in an independent planar manner with a single bundle of hair, Equipped with, The aforementioned hair follicle portion is, A central hair bundle is positioned in the central region of the aforementioned hair implantation surface, Multiple peripheral hair bundles are spaced apart from the central hair bundle and surround the central hair bundle at intervals from each other, It has, The central hair bundle has a recess in the front view outline that is recessed in a direction away from the surrounding hair bundle at a position opposite to at least one of the surrounding hair bundles, A toothbrush in which, among the surrounding bristle bundles, the opposing bristle bundles facing the recess partially enter the recess when bent by an external force.

2. The shortest distance between the opposing hair bundle and the recess is 0.5 mm or less. The toothbrush according to claim 1.

3. The opposing hair bundle has a projection that faces the recess and tapers towards the recess. The toothbrush according to claim 1.

4. The projection is arc-shaped with radius r, having its center of curvature on the side opposite to the recess in the front view. The radius of the virtual circle connecting one end of the outer contour of the recess in the front view, the other end, and the position furthest from the projection in the opposing direction of the opposing hair bundle and the recess is greater than or equal to the radius r. The toothbrush according to claim 3.

5. The aforementioned recess is provided in the outer contour of the central hair bundle that extends in the direction of the major axis when viewed from the front. The toothbrush according to any one of claims 1 to 4.

6. At least two of the surrounding hair bundles have a second recess on the side opposite to the side facing the central hair bundle in the outer contour of the front view, The second recess is provided symmetrically with respect to the center line that is located in the center of the central hair bundle in the minor axis direction and extends in the major axis direction. The toothbrush according to claim 5.

7. The opposing hair bundles are arranged on both sides of the central hair bundle in the direction of its shorter axis, with the central hair bundle in between. On either side of the central bundle of hair in the longitudinal direction, the first non-opposing bundles of hair from the peripheral bundles that are not facing the recess are respectively arranged. On both sides of the central hair bundle, in diagonal directions that intersect both the major and minor axes, a second non-opposing hair bundle from the peripheral hair bundle that is not facing the recess is positioned. The opposing hair bundles taper towards the central hair bundle, At least one of the first non-opposing hair bundle and the second non-opposing hair bundle tapers towards the central hair bundle. The toothbrush according to claim 5.

8. Among the surrounding hair bundles, the non-opposing hair bundles that are not facing the recess and are adjacent to the opposing hair bundles have protrusions that taper towards the central hair bundle. The central bundle of hair has a protrusion at a position opposite to the projection. The toothbrush according to any one of claims 1 to 4.

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