Toothbrush

Abstract

To provide a toothbrush which causes an inside hair bundle to enter an interdental complicated portion, for preferably cleaning the portion, and suppresses damage applied to a gum by the inside hair bundle.SOLUTION: A toothbrush 1 comprises: multiple inside hair bundles 8 which are arranged on a center region in a width direction of a head part 3; and multiple outside hair bundles 9 which are arranged in both outside regions sandwiching the center region in the width direction of the head part 3. The multiple inside hair bundles 8 include multiple long bristles 10 whose bristle lengths are longer than those of the multiple outside hair bundles 9. A ratio of a thickness of each long bristle 10 to a thickness of each outside bristle 12 forming the outside hair bundles 9 is 0.9 or more and 1.6 or less.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to toothbrushes. [Background technology]

[0002] A toothbrush has a structure in which a bristle base (referred to as a "head" in this disclosure) is connected to the tip of a handle, and bristle bundles each consisting of a bundle of bristles are implanted in a plurality of bristle implantation holes formed in the head. Toothbrushes are required to be effective not only in cleaning relatively smooth tooth surfaces, but also in cleaning intricate areas between teeth. For this reason, various studies have been conducted on the shape of the plurality of bristle bundles provided in the head.

[0003] For example, in the toothbrush described in Patent Document 1, the thickness and length (bristle length) of the bristle bundles (inner bristle bundles) arranged in the center of the head are different from that of the outer bristle bundles arranged on both sides of the center of the head. Specifically, the inner bristle bundles are made thinner and longer than the outer bristle bundles, which allows the inner bristle bundles to reach the intricate areas between the teeth. As a result, the toothbrush described in Patent Document 1 has a good cleaning effect on the interdental spaces that are difficult to clean with a normal toothbrush. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2001-309819 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, if the inner bristles are longer than the outer bristles, as in the toothbrush described in Patent Document 1, the force (brushing pressure) applied to the tooth surfaces and gums by the tips of the inner bristles when brushing the teeth will be greater, which may cause damage to the gums, etc.

[0006] In order to solve the above problems, the present disclosure aims to provide a toothbrush that can reduce damage to the gums. [Means for solving the problem]

[0007] In order to solve the above problems, the toothbrush of the present disclosure encompasses as its subject the toothbrush described in item 1 below.

[0008] Item 1. A toothbrush in which a plurality of bristles are bundled and planted in a plurality of bristles planting holes formed in the head portion, A plurality of inner hair bundles arranged in a central region in a width direction of the head portion; A plurality of outer hair bundles arranged in both outer regions sandwiching the central region in the width direction; Equipped with the inner hair bundles include a plurality of long bristles having a length longer than that of the outer hair bundles, The toothbrush, wherein the ratio of the thickness of the long bristles to the thickness of the outer bristles constituting the plurality of outer bristles bundles is 0.9 or more and 1.6 or less.

[0009] Furthermore, the toothbrush of the present disclosure encompasses the toothbrush described in Item 2 below as a preferred embodiment of the toothbrush described in Item 1 above.

[0010] Item 2. The toothbrush according to item 1, wherein at least a portion of the plurality of long bristles included in the inner bristle bundle are spiral bristles twisted in the longitudinal direction.

[0011] Furthermore, the toothbrush of the present disclosure encompasses the toothbrush described in the following item 3 as a preferred embodiment of the toothbrush described in items 1 and 2 above.

[0012] Item 3. The toothbrush according to item 1 or 2, wherein the inner bristle bundles are arranged continuously along the longitudinal direction of the head portion.

[0013] Furthermore, the toothbrush of the present disclosure encompasses the toothbrush described in item 4 below as a preferred embodiment of the toothbrush described in items 1 to 3 above.

[0014] Item 4. The toothbrush according to any one of Items 1 to 3, wherein the inner bristle bundles include a plurality of short bristles having a shorter length than the long bristles.

[0015] Furthermore, the toothbrush of the present disclosure encompasses the toothbrush described in item 5 below as a preferred embodiment of the toothbrush described in items 1 to 4 above.

[0016] Item 5. The toothbrush according to any one of items 1 to 4, wherein some of the outer bristle bundles are arranged in pairs in the width direction in both outer regions of the head portion.

[0017] Furthermore, the toothbrush of the present disclosure encompasses the toothbrush described in item 6 below as a preferred embodiment of the toothbrush described in items 1 to 5 above.

[0018] Item 6. The toothbrush according to any one of items 1 to 5, wherein two of the inner bristle bundles are arranged in the width direction in the central region of the head portion.

[0019] Furthermore, the toothbrush of the present disclosure encompasses the toothbrush described in item 7 below as a preferred embodiment of the toothbrush described in items 1 to 6 above.

[0020] Item 7. The toothbrush according to any one of Items 1 to 6, wherein each of the outer bristle bundles is composed of outer bristles having the same length. Effect of the Invention

[0021] According to the toothbrush of the present disclosure, the inner bristles can penetrate into the complicated areas between the teeth to clean those areas well, and damage to the gums caused by the inner bristles can be prevented. [Brief description of the drawings]

[0022] [Figure 1] FIG. 1 is a plan view showing a schematic configuration of a toothbrush according to one embodiment of the present disclosure. [Diagram 2]FIG. 2 is an enlarged plan view of the head portion of the toothbrush of FIG. [Diagram 3] FIG. 3 is an enlarged side view of the head portion of the toothbrush of FIG. [Figure 4] FIG. 4 is a cross-sectional view for explaining bristles constituting the inner hair bundle and bristles constituting the outer hair bundle. [Diagram 5] FIG. 5 is a diagram for explaining the twist of the long bristles constituting the inner hair bundle. [Figure 6] FIG. 6 is a diagram for explaining a modified example of long bristles constituting the inner hair bundle. [Figure 7] FIG. 7 shows a modification of the head portion of the toothbrush of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] Hereinafter, an embodiment of the toothbrush of the present disclosure will be described with reference to the attached drawings. In this disclosure, unless otherwise specified, the front-rear, back-rear, left-right, and other directions used in relation to each part of the toothbrush, the front-rear direction shown in FIG. 1 corresponds to the longitudinal direction (vertical direction) of the handle 2 and head 3, and the left-right direction corresponds to the width direction (horizontal direction) of the handle 2 and head 3. Also, the direction perpendicular to both the longitudinal direction and the width direction is the height or thickness direction. In the front-rear direction, the tip side where the head 3 is connected to the handle 2 is the "front side", and the opposite side is the "rear side".

[0024] Fig. 1 shows the appearance of toothbrush 1 of this embodiment. Fig. 2 and Fig. 3 show enlarged views of the appearance of head portion 3 of toothbrush 1. Toothbrush 1 comprises a long, rod-shaped handle portion 2, a thin, plate-shaped head portion 3 connected to the tip of handle portion 2, and a plurality of bristle bundles 8, 9 provided on head portion 3.

[0025] As shown in FIG. 1, the handle 2 is a portion that a user holds when using the toothbrush 1. The handle 2 has a dimension longer in the front-rear direction than the head 3. The handle 2 may be molded integrally with the head 3, or may be formed as a separate member from the head 3, with the head 3 joined to the tip of the handle 2. The handle 2 of this embodiment is made of a material such as polypropylene resin, and is molded integrally with the head 3. The outer shape and cross section (cross section perpendicular to the longitudinal direction of the handle 2) of the handle 2 are not particularly limited, and various shapes that have been publicly known in the art can be adopted.

[0026] 1 and 2, the head portion 3 has a generally octagonal shape that is long in the front-rear direction when viewed from above, for example, with the four corners of a rectangle gently cut off. The head portion 3 is preferably symmetrical (bilaterally symmetrical) with respect to a center line that is parallel to the longitudinal direction and passes through the center in the width direction.

[0027] The front end 4, which is a part of the front end side of the head part 3, is formed in a tapered shape in which the length in the width direction (horizontal width) gradually decreases toward the front in a plan view. In other words, the left and right side edges 40, 41 of the front end 4 extend so as to approach each other toward the front. The left and right side edges 40, 41 of the front end 4 are connected to the tip edge 31 of the head part 3. The tip edge 31 of the head part 3 extends linearly in the width direction or in a convex, concave or zigzag curved shape, and the front end 4 has, for example, a triangular shape (including an approximately triangular shape with rounded tip corners) or a trapezoid shape (including an approximately trapezoid shape with rounded two tip corners) in a plan view. The front end 4 does not necessarily have to be formed in a triangular shape or trapezoid shape in a plan view, and may be formed in a tapered shape while being curved overall, such as a semicircular shape or semielliptical shape.

[0028] The rear end 5, which is a part of the rear end side of the head 3, is formed in a narrowed shape in which the lateral length (width) gradually decreases toward the rear in a plan view. In other words, the left and right side edges 50, 51 of the rear end 5 extend so as to approach each other toward the rear. The rear end 5 is not particularly limited, but may have a substantially inverted trapezoid shape, for example. The left and right side edges 50, 51 of the rear end 5 are connected to the left and right side edges of the handle 2. The boundary between the head 3 and the handle 2 is the position of the boundary line if the boundary line is clearly indicated. On the other hand, if the head 3 and the handle 2 are seamlessly molded as one piece, the boundary between the head 3 and the handle 2 can be determined based on the position where the head 3 is narrowest on the inside, or the position where the thickness changes if the head 3 and the handle 2 have different thicknesses.

[0029] In a plan view, an intermediate portion 6 between the front end portion 4 and the rear end portion 5 of the head portion 3 has left and right side edges 60, 61 that extend parallel to each other in the front-rear direction. The intermediate portion 6 of the head portion 3 is not particularly limited, but may have, for example, a substantially rectangular shape.

[0030] The tapered front end 4 of the head 3 increases the force with which the toothbrush 1 penetrates into the oral cavity, allowing the toothbrush 1 to clean even the back teeth well. In addition, the discomfort felt by the user due to the tip of the head 3 touching the cheek can be reduced. The shape of the head 3 in a plan view is not limited to a substantially octagonal shape, and various known shapes can be adopted.

[0031] The thickness of head portion 3 is preferably 3.0 mm or more and 3.6 mm or less, and more preferably 3.2 mm or more and 3.4 mm or less. By forming head portion 3 thin while maintaining a certain degree of strength, toothbrush 1 can be easily inserted into the oral cavity.

[0032] The maximum width W of the head part 3 (the width of the middle part 6, which is the maximum length in the width direction in this embodiment) is preferably 10 mm or more and 20 mm or less, more preferably 13 mm or more and 17 mm or less, and more preferably 14 mm or more and 16 mm or less. If the maximum width W of the head part 3 is large, the number of bristle bundles 8, 9 that can be arranged in the width direction in the head part 3 increases, and a large cleaning area can be secured by the head part 3. If the head part 3 is wide and the maximum width W is 15 mm or more, five or more, preferably six or more, bristle bundles 8, 9 can be arranged in the width direction. On the other hand, by making the maximum width W of the head part 3 20 mm or less, the head part 3 can be easily handled in the oral cavity.

[0033] In this embodiment, the maximum width W of the head portion 3 is designed to be shorter than the bristles of the long bristles 10 described below and longer than the bristles of the outer bristles 12. However, the maximum width W of the head portion 3 is not necessarily limited to the above design.

[0034] The front surface 30 of the head portion 3 forms a tufting surface. As shown in FIG. 4, a plurality of tufting holes 7 are formed on the front surface 30 of the head portion 3. The plurality of tufting holes 7 are arranged at intervals in the longitudinal and width directions of the head portion 3. The shape of the tufting holes 7 is not particularly limited, and examples thereof include a circle, an ellipse, a polygon, etc. in a plan view. It is preferable that the shapes and dimensions of the plurality of tufting holes 7 are all substantially the same. For example, if the shape of the tufting holes 7 is a circle in a plan view, the dimensions of the tufting holes 7 can be exemplified as a diameter of 1.0 mm or more and 2.0 mm or less, preferably 1.2 mm or more and 1.8 mm or less.

[0035] As shown in Fig. 4, bristle bundles 8, 9 each made of a bundle of bristles are implanted in each of the bristle implantation holes 7. For example, each bristle bundle 8, 9 is made by bundling a bundle of bristles, folding the bundle in half, attaching a known flat wire to the folded portion, and driving and fixing the folded portion together with the flat wire into the bristle implantation hole 7, thereby implanting the bundle into each bristle implantation hole 7. Examples of materials for the bristles include saturated polyester resins such as polybutylene terephthalate, nylon, etc., but it is preferable to use polybutylene terephthalate as the bristle material from the viewpoint of high durability.

[0036] As shown in FIG. 2, the multiple hair bundles 8, 9 are arranged on the front surface 30 of the head unit 3 at intervals in the longitudinal direction and width direction of the head unit 3 according to the arrangement of the multiple hair implantation holes 7. The multiple hair bundles 8 are arranged in the central region of the head unit 3 in the width direction. In this disclosure, the hair bundles 8 arranged in the central region of the head unit 3 in the width direction are referred to as "inner hair bundles 8". On the other hand, the multiple hair bundles 9 are arranged in both outer regions of the head unit 3 on either side of the central region in the width direction. In this disclosure, the hair bundles 9 arranged in the outer regions of the head unit 3 in the width direction are referred to as "outer hair bundles 9". In FIG. 2, for convenience of explanation, the hair bundles are colored according to type, with the inner hair bundles 8 being indicated by black circles and the outer hair bundles 9 being indicated by white circles.

[0037] In this embodiment, multiple horizontal rows of multiple bristle bundles 8, 9 aligned in the width direction of the head portion 3 are aligned in the longitudinal direction of the head portion 3. For example, in the intermediate portion 6, which has the largest width in the head portion 3, six bristle bundles 8, 9 are aligned in the width direction of the head portion 3, and five horizontal rows of these six bristle bundles 8, 9 are provided in the longitudinal direction of the head portion 3.

[0038] 4, each of the multiple bristle bundles 8, 9 provided on the head portion 3 is an assembly of multiple bristles, with the inner bristle bundle 8 being mainly composed of long bristles 10, and the outer bristle bundle 9 being composed of short bristles 11. In other words, the multiple bristle bundles 8, 9 provided on the head portion 3 include multiple inner bristles 8 mainly composed of multiple long bristles 10, and multiple outer bristles 9 composed of multiple short bristles 11.

[0039] The inner bristles 8 are composed of a plurality of long bristles 10. The length of the long bristles 10 is longer than the length of the bristles (referred to as "outer bristles" in this disclosure) 12 constituting the outer bristles 9.

[0040] Since the inner bristle bundle 8 includes a plurality of long bristles 10 having a length longer than the outer bristle bundles 10 constituting the outer bristle bundle 9, the long bristles 10 can easily get into the gaps between the teeth when the toothbrush 1 is moved in the longitudinal direction while brushing the teeth. Therefore, the long bristles 10 can be inserted into the complicated areas between the teeth, and the long bristles 10 can clean the gaps between the teeth well.

[0041] In addition, since the outer bristles 12 constituting the outer bristle bundle 9 are shorter than the long bristles 10 constituting the inner bristle bundle 8, the angle at which the long bristles 10 are inserted between the teeth during brushing is stable. This makes it possible to improve the ease of inserting the long bristles 10 between the teeth.

[0042] The bristles 10 have a bristle length of, for example, 12 mm to 16 mm, preferably 13 mm to 15 mm, so that the bristles 10 can be easily inserted between the teeth when brushing teeth.

[0043] In the present disclosure, the bristles 10-13 are lengths from the front surface 30 of the head unit 3 to the tips of the respective bristles. When there is variation in the bristles of the multiple bristles, the average of the bristles is regarded as the bristles length.

[0044] From the viewpoint of improving the cleaning effect of the long bristles 10 when brushing teeth, the shape of the cross section of the long bristles 10 (a cross section perpendicular to the length direction of the bristles) is preferably a polygonal shape, and preferably a regular square shape, a regular hexagon shape, etc. The shape of the cross section of the long bristles 10 may be a circle, etc.

[0045] From the viewpoint of optimizing the brushing pressure, the thickness of the long bristles 10 is preferably 0.152 mm or more and 0.239 mm or less (6 mil or more and 9 mil or less), and more preferably 0.165 mm or more and 0.216 mm or less (6.5 mil or more and 8.5 mil or less).

[0046] The thickness of the long bristles 10 may be thinner than or the same as the thickness of the outer bristles 12, but it is preferable that the thickness is thicker than that of the outer bristles 12.

[0047] In the present disclosure, the thickness of the various bristles 10-13 is the thickness measured at the root of the bristles (a portion 5 mm away from the front surface 30 of the head part 3). The thickness of the bristles is the maximum thickness in the cross section of the bristles. When the cross section of the bristles is, for example, a circular shape, the diameter is the maximum thickness, and when the cross section of the bristles is a regular square or regular hexagon, the length of the diagonal is the maximum thickness. The thickness of the bristles can be measured by pinching the root of the bristles using a digital thickness gauge.

[0048] The long bristles 10 may be of various shapes known for bristles used in toothbrushes, such as flat bristles having a generally uniform thickness over the entire length, round bristles with rounded tips, branched bristles with a portion of the tip branched, tapered bristles with at least a portion of the tip tapered, etc. From the viewpoint of favorably improving the ease of insertion of the long bristles 10 between the teeth when brushing teeth, it is preferable that the long bristles 10 are tapered bristles.

[0049] From the viewpoint of good insertion between teeth when brushing, the long bristles 10 are preferably spiral bristles twisted in the length direction as shown in Fig. 5. By having a twist in the long bristles 10, the stiffness of the long bristles 10 is increased, and the angle at which the long bristles 10 insert between teeth is stabilized. This improves the ease of insertion of the long bristles 10 between teeth.

[0050] All of the multiple long bristles 10 included in the inner bristles bundle 8 may be spiral bristles, or most (e.g., about 80%) of the multiple long bristles 10 included in the inner bristles bundle 8 may be spiral bristles. From the viewpoint of favorably improving the ease of inserting the long bristles 10 between teeth when brushing teeth, the number of twists of the spiral bristles is preferably 1.5 to 4 twists per cm in the length direction of the long bristles 10, and more preferably 2 to 3.5 twists per cm in the length direction.

[0051] From the viewpoint of favorably improving the insertability of the long bristles 10 between teeth when brushing teeth, the buckling strength of the multiple long bristles 10 provided on the head portion 3 is preferably 350 g or more, and more preferably 450 g or more. The buckling strength can be measured by abutting the tips of the multiple long bristles 10 provided on the head portion 3 against a flat surface, applying a load vertically to the head portion 3 from the side opposite the front surface 30, and measuring the load (g) when the multiple long bristles 10 buckle.

[0052] The inner hair bundle 8 may include a plurality of short bristles 11 having a shorter length than the long bristles 10. In other words, the inner hair bundle 8 may be configured by bundling a plurality of long bristles 10 and a plurality of short bristles 11, in addition to being configured by bundling a plurality of long bristles 10.

[0053] When the inner bristle bundle 8 includes the short bristles 11, the short bristles 11 support the long bristles 10, making the long bristles 10 less likely to fall over, compared to when the inner bristle bundle 8 does not include the short bristles 11. This stabilizes the angle at which the long bristles 10 enter between the teeth, and when the toothbrush 1 is moved in the longitudinal direction while brushing the teeth, the long bristles 10, which have a long bristles length, can easily enter narrow gaps between the teeth. This improves the ease with which the long bristles 10 can be inserted between the teeth when brushing the teeth, allowing the long bristles 10 to effectively clean between the teeth.

[0054] The short bristles 11 may be of various known forms for bristles used in toothbrushes, such as flat bristles having a roughly uniform thickness over the entire length, round bristles having rounded tips, branched bristles having a branched tip, tapered bristles having at least a portion of the tip tapered, etc. Similarly to the long bristles 10, the short bristles 11 may be spiral bristles twisted in the length direction.

[0055] The bristles 11 may have a bristle length longer, shorter or the same as that of the outer bristles 12. The bristles 11 have a bristle length of, for example, 7 mm to 11 mm, preferably 8 mm to 10 mm, so that the short bristles 11 can satisfactorily brush the tooth surface when brushing teeth and can create a step so that the long bristles 10 can be satisfactorily inserted between the teeth.

[0056] From the viewpoint of improving the cleaning effect of the short bristles 11 when brushing teeth, the cross-sectional shape of the short bristles 11 is preferably a polygonal shape, and preferably a regular square shape, a regular hexagon shape, etc. However, the cross-sectional shape of the short bristles 11 may be a circle, etc.

[0057] From the viewpoint of optimizing the brushing pressure, the thickness of the short bristles 11 is preferably 0.127 mm or more and 0.178 mm or less (5 mil or more and 7 mil or less), and more preferably 0.140 mm or more and 0.165 mm or less (5.5 mil or more and 6.5 mil or less).

[0058] The outer bristles 9 are made up of a plurality of outer bristles 12 having a shorter length than the long bristles 10. In other words, the outer bristles 9 are made up of a plurality of outer bristles 12 bound together.

[0059] It is preferable that the multiple outer bristles 12 constituting the outer bristle bundle 9 all have the same bristles length. If the multiple outer bristles 12 constituting the outer bristle bundle 9 all have the same bristles length, the angle at which the multiple long bristles 10 constituting the inner bristle bundle 8 are inserted between the teeth when the outer bristles bundle 9 comes into contact with the teeth is more stable than when the multiple outer bristles 12 have different bristles lengths. This makes it possible to improve the ease of inserting the long bristles 10 between the teeth. The concept of bristles having the same bristles length includes not only cases where the bristles are completely the same length, but also cases where the bristles are substantially the same length (for example, the difference in bristles length is about 1 mm).

[0060] The outer bristles 12 may be of various types known for use in toothbrushes, such as flat bristles having a generally uniform thickness over the entire length, round bristles with rounded tips, branched bristles with a portion branched off at the tip, and tapered bristles with at least a portion tapered off at the tip. For example, of the multiple outer bristles 12 constituting the outer bristle bundle 12, half of the outer bristles 12 may be tapered bristles, and the remaining half of the outer bristles 12 may be flat bristles. Similarly to the long bristles 10, the outer bristles 12 may be spiral bristles twisted in the length direction.

[0061] The length of the outer bristles 12 is, for example, 7 mm or more and 11 mm or less, preferably 8 mm or more and 10 mm or less, so that the outer bristles 12 can effectively brush the tooth surface when brushing the teeth and a step can be created so that the long bristles 10 can be effectively inserted between the teeth.

[0062] The difference in bristle length between the long bristles 10 and the outer bristles 12 is preferably 4 mm or more and 6 mm or less, and more preferably 8 mm or more and 10 mm or less, from the viewpoint of improving the ease of inserting the long bristles 10 between the teeth when brushing teeth.

[0063] From the viewpoint of improving the cleaning effect of the outer bristles 12 when brushing teeth, the cross-sectional shape of the outer bristles 12 is preferably a polygonal shape, and preferably a regular square shape, a regular hexagon shape, etc. However, the cross-sectional shape of the outer bristles 12 may be a circle, etc.

[0064] From the viewpoint of optimizing the brushing pressure, the thickness of the outer bristles 12 is preferably 0.127 mm or more and 0.178 mm or less (5 mil or more and 7 mil or less), and more preferably 0.140 mm or more and 0.165 mm or less (5.5 mil or more and 6.5 mil or less).

[0065] The long bristles 10 have a long length, so that the force (brushing pressure) applied by the bristles to the tooth surfaces and gums by the bristles when brushing teeth is large, which may cause damage to the gums, etc. The inventors of the present disclosure have discovered that by adjusting the ratio between the thickness of the long bristles 10 that mainly constitute the inner bristle bundle 8 and the thickness of the outer bristles 12 that constitute the outer bristle bundle 9, it is possible to reduce the brushing pressure applied to the tooth surfaces and gums by the long bristles 10, and to gently contact the gums, etc., while maintaining the high cleaning power and cleaning feeling of the long bristles 10 between the teeth when brushing teeth.

[0066] Specifically, in the toothbrush 1 of the present disclosure, the ratio of the thickness of the long bristles 10 to the thickness of the outer bristles 12 is 0.9 or more and 1.6 or less, preferably 1.0 or more and 1.5 or less, more preferably 1.0 or more and 1.3 or less, and most preferably greater than 1.0 and 1.2 or less. As a result, in the toothbrush 1 of the present disclosure, the long bristles 10 can improve the interdental cleaning effect (e.g., plaque removal effect) while suppressing damage to the gums, such as gum pain, caused by the long bristles 10 when brushing teeth.

[0067] It is preferable that the multiple inner hair bundles 8 are continuously arranged along the longitudinal direction of the head portion 3 in the central region in the width direction of the head portion 3, forming a group of inner hair bundles 80 extending in the longitudinal direction.

[0068] The outer hair bundles 9 are preferably arranged continuously along the longitudinal direction of the head portion 3 in each outer region in the width direction of the head portion 3, forming an outer hair bundle group 90 extending in the longitudinal direction. The inner hair bundle group 80 is sandwiched between the two outer hair bundle groups 90, 90. For example, in the middle portion 6, which has the largest width in the head portion 3, there are five horizontal rows of hair bundles, each row having six hair bundles arranged in the width direction of the head portion 3, and of the six arranged hair bundles, two on each side are outer hair bundles 9, and the two in the middle are inner hair bundles 8.

[0069] When multiple inner bristles 8 are continuously arranged along the longitudinal direction of the head part 3, the long bristles 10 are less likely to fall over when the toothbrush 1 is moved longitudinally while brushing teeth, as adjacent inner bristles 8 support the long bristles 10, compared to when multiple inner bristles 8 are discontinuously arranged along the longitudinal direction of the head part 3. Therefore, the angle at which the multiple long bristles 10 are inserted between the teeth is stabilized, and the ease of inserting the long bristles 10 between the teeth can be favorably improved.

[0070] Although there is no particular limitation, it is preferable that the inner hair bundle group 80 is not completely surrounded by the multiple outer hair bundles 9. For example, at the front end 4 of the head part 3, at least one inner hair bundle 8 protrudes forward from the two outer hair bundle groups 90, 90 on the left and right. In other words, no outer hair bundle 9 is positioned forward of the inner hair bundle 8 located most forward of the inner hair bundle group 80, and the inner hair bundle 8 is closest to the front end edge 31 of the head part 3.

[0071] When at least one inner bristle bundle 8 is located closest to the front edge 31 of the head portion 3, compared to when not located otherwise, when moving the toothbrush 1 in the longitudinal direction to brush the teeth, the bristle bundle located at the frontmost side of the head portion 3 that comes into contact with the teeth first is the inner bristle bundle 8 with a long bristles, so the inner bristle bundle 8 is less likely to fall over than the outer bristle bundles 9 with a short bristles, and the inner bristle bundles 8 adjacent to this inner bristle bundle 8 are also less likely to fall over. This stabilizes the angle at which the multiple long bristles 10 constituting the inner bristle bundle 8 are inserted between the teeth, and the ease of inserting the long bristles 10 between the teeth can be improved.

[0072] Even at the rear end 5 of the head portion 3, the inner bristles bundle 8 does not protrude rearward from the two outer bristles bundles 90, 90 on the left and right, but the outer bristles bundle 9 is not positioned rearward of the inner bristles bundle 8 that is positioned furthest rearward of the inner bristles bundle group 80. This, for the same reason, stabilizes the angle at which the multiple long bristles 10 constituting the inner bristles bundle 8 are inserted between the teeth when the toothbrush 1 is moved in the longitudinal direction while brushing teeth. This can favorably improve the ease of inserting the long bristles 10 between the teeth.

[0073] In addition, at the rear end 5 of the head portion 3, one outer hair bundle 9 arranged on each side of the inner hair bundle 8 located at the rearmost position of the inner hair bundle group 80 may not be arranged (may not exist).

[0074] In the central region of the head portion 3, the multiple inner hair bundles 8 are preferably arranged along the longitudinal direction of the head portion 3 with at least a portion of them being lined up in pairs in the width direction of the head portion 3. In this embodiment, in the front end portion 4 of the head portion 3, the inner hair bundles 8 are arranged two on the left and right, one on the right, two on the left and two on the right, two on the right, two on the right, and one on the left and one on the right, one on the right, one on the right, one on the right.

[0075] When at least some of the multiple inner bristles 8 are arranged in twos lined up in the width direction of the head part 3 along the longitudinal direction of the head part 3, the bristles 10 constituting the inner bristles 8 are stiffer than when one inner bristles 8 is lined up in the width direction, and the insertability of the long bristles 10 between teeth can be improved. Also, the width occupied by the inner bristles 8 is ensured to be wide, so that the insertability of the long bristles 10 between teeth can be improved.

[0076] In each of both outer regions of the head part 3, the multiple outer hair bundles 9 are preferably arranged along the longitudinal direction of the head part 3 with two bundles lined up in the width direction of the head part 3 for at least a portion of the head part 3. In this embodiment, at the front end part 4 of the head part 3, 0, 1, and 2 outer hair bundles 9 are arranged on the left and right from the front, at the central part 6, 2, 2 outer hair bundles 9 are arranged on the left and right from the front, and at the rear end part 5, 2 and 1 outer hair bundles 9 are arranged on the left and right from the front.

[0077] When at least some of the outer bristle bundles 9 are arranged in two in the width direction of the head part 3 along the longitudinal direction of the head part 3, the angle at which the long bristles 10 of the inner bristle bundle 8 are inserted between the teeth becomes more stable compared to when one outer bristle bundle 9 is arranged in the width direction. Therefore, when brushing teeth while moving the toothbrush 1 in the longitudinal direction, the ease of inserting the long bristles 10 between the teeth can be improved.

[0078] The density of the long bristles 10 of the inner bristle bundle 8 implanted in the implantation hole 7 is preferably 18 bristles / mm 2 in order to improve the ease of insertion of the long bristles 10 between teeth. 2 Over 26 lines / mm 2 More preferably, 20 fibers / mm 2 24 or more / mm 2 The following is the result.

[0079] The density of the outer bristles 12 of the outer bristle bundle 9 implanted in the implantation hole 7 is preferably 28 bristles / mm 2 from the viewpoint of ensuring that the outer bristles 12 can thoroughly remove plaque from the tooth surface. 2 Over 42 lines / mm 2 More preferably, 30 fibers / mm 2 More than 40 pieces / mm 2 The following is the result.

[0080] From the viewpoint of favorably improving the insertability of the long bristles 10 between the teeth, the area of ​​the inner bristle bundle group 80 is preferably 1 / 3 or more and 2 / 3 or less of the total area of ​​the outer bristle bundle group 90. The area of ​​the inner bristle bundle group 80 is the area of ​​the region surrounded by a circular line connecting the outer edges of the bristle implantation holes 7 into which the inner bristle bundles 8 located at the outermost periphery of the inner bristle bundle group 80 are implanted. The area of ​​the outer bristle bundle group 90 is the area of ​​the region surrounded by a circular line connecting the outer edges of the bristle implantation holes 7 into which the outer bristle bundles 9 located at the outermost periphery of the outer bristle bundle group 90 are implanted.

[0081] According to the toothbrush 1 of the present embodiment described above, a plurality of inner bristles 8 are arranged in the central region in the width direction of the head part 3, and a plurality of outer bristles 9 are arranged in both outer regions on either side of the central region in the width direction of the head part. The long bristles 10 that mainly constitute the inner bristles bundle 8 are formed to have a longer bristles length than the outer bristles 12 that constitute the outer bristles bundle 9. As a result, when the toothbrush 1 is moved in the longitudinal direction while brushing teeth, the long bristles 10 of the inner bristles bundle 8 reach into the complicated areas between the teeth, so that difficult-to-clean spaces can be cleaned well and plaque adhering between the teeth can be removed well.

[0082] The ratio of the thickness of the long bristles 10 to the thickness of the outer bristles 12 is set to 0.9 to 1.6. The long bristles 10 exert a large force (brushing pressure) on the tooth surface and gums by the bristles when brushing teeth because of their long length. However, by adjusting the thickness of the long bristles 10 relative to the thickness of the outer bristles 12, the brushing pressure exerted by the long bristles 10 on the tooth surface and gums can be suppressed. Therefore, even if the long bristles 10 are long, the long bristles 10 can be gently applied to the gums, and thus damage to the gums, such as pain caused by the long bristles 10, can be suppressed. In addition, the long bristles 10 have a certain thickness and exert a high cleaning power, so that the cleaning effect and cleaning sensation (e.g., removal of plaque, etc.) by the long bristles 10 can be improved between the teeth.

[0083] Although one embodiment of the toothbrush of the present disclosure has been described above, the toothbrush of the present disclosure is not limited to the above-mentioned embodiment, and various modifications can be made without departing from the spirit of the present disclosure. For example, the following modifications can be made. In addition, the gist of the following modifications can be combined as appropriate.

[0084] For example, in the above-described embodiment, the plurality of long bristles 10 that mainly constitute the inner bristle bundle 8 may have a curved tip portion as shown in Fig. 6. When the tip portion of the long bristles 10 is curved, the long bristles 10 that reach between the teeth can efficiently scrape off plaque adhering between the teeth, thereby enabling more thorough cleaning between the teeth.

[0085] For example, in the above-described embodiment, the arrangement and number of the inner hair bundles 8 and the outer hair bundles 9 on the front surface 30 (hair implantation surface) of the head portion 3 is not particularly limited, as long as multiple inner hair bundles 8 are arranged in the central region in the width direction of the head portion 3, and multiple outer hair bundles 9 are arranged in both outer regions on either side of the central region in the width direction of the head portion 3, and can be changed as appropriate, for example, as shown in Figure 7.

[0086] In the example shown in Fig. 7(A), compared to the above-described embodiment, the number of inner hair bundles 8 provided in the central portion 6 of the head portion 3 is reduced. In the example shown in Fig. 7(A), six hair bundles 8, 9 are lined up in the width direction in the central portion 6 of the head portion 3, and three horizontal rows of these six hair bundles 8, 9 are provided in the longitudinal direction of the head portion 3.

[0087] In the example shown in Fig. 7(B), the number of inner hair bundles 8 provided in the central region in the width direction of the head part 3 is increased compared to the above-mentioned embodiment, and the number of outer hair bundles 9 is decreased accordingly. In the example shown in Fig. 7(B), for example, six hair bundles 8, 9 are lined up in the width direction in the central part 6 of the head part 3, and of the six lined up hair bundles, one each on the outside is an outer hair bundle 9, and the four in the center are inner hair bundles 8. The number of inner hair bundles 8 is also increased at the front end part 4 and the rear end part 5 of the head part 3.

[0088] In the example shown in Figure 7(C), compared to the above-mentioned embodiments, the multiple inner hair bundles 8 arranged in the central region of the head portion are not continuous in the longitudinal direction of the head portion 3, and there are short hair bundles (shown by light black circles in Figure 7(C)) interspersed here and there, and the multiple inner hair bundles 8 are arranged in an interrupted manner in the longitudinal direction of the head portion 3.

[0089] In the example shown in Figure 7 (D), compared to the above-mentioned embodiment, the number of inner hair bundles 8 and outer hair bundles 9 provided on the head portion 3 is reduced, while the thickness of the inner hair bundles 8 and outer hair bundles 9 is increased.

[0090] In the example shown in Figure 7 (E), compared to the above-described embodiment, the arrangement and number of inner hair bundles 8 provided in the central region in the width direction of the head portion 3 have been changed, and multiple inner hair bundles 8 are arranged in a staggered pattern.

[0091] 7(F) and 7(G), compared to the above-described embodiment, the thickness of the inner hair bundle 8 and the outer hair bundle 9 provided on the head portion 3 are different. In the example of Fig. 7(F), the thickness of the outer hair bundle 9 is thicker than the inner hair bundle 8, and in the example of Fig. 7(G), the thickness of the inner hair bundle 8 is thicker than the outer hair bundle 9. EXAMPLES

[0092] The action and effect of the toothbrush of the present disclosure will be specifically explained below with reference to examples and comparative examples; however, the toothbrush of the present disclosure is not limited to the following examples.

[0093] A toothbrush having the same arrangement and number of inner and outer bristles as the toothbrush 1 of the above-mentioned embodiment was used to conduct a brushing pressure test and a test of interdental cleaning power. In the toothbrushes of Examples 1 to 6 and Comparative Examples 1 to 4, the thickness of the long bristles that mainly constitute the inner bristles and the thickness of the outer bristles that constitute the outer bristles are as shown in Table 1 below. The bristles of the long bristles have a length of 14 mm, and the bristles of the long outer bristles have a length of 9 mm.

[0094] In the brushing pressure test, the brushing pressure of the toothbrush was evaluated using a pressure measurement film. The pressure measurement film used was "Prescale Ultra-low Pressure (5LW)" manufactured by Fujifilm Corporation. First, the pressure measurement film was set on the toothbrush pressure tester using double-sided tape. The toothbrush was also set on the brushing machine so that the tip of the inner bristle bundle of the head part was in contact with the surface of the pressure measurement film. Then, the toothbrush was moved along the longitudinal direction by the brushing machine under the following conditions: load (load applied vertically from the opposite side to the front surface of the head part) 300g, reciprocating operation time 20 seconds, vibration frequency 240 times / min, reciprocating distance 20 mm, and the surface of the pressure measurement film was brushed with the bristle bundle provided on the head part. The brushing marks on the surface of the pressure measurement film after brushing with the toothbrush were photographed at a position 10 cm above the film surface in the vertical direction, and the area occupied by the brushing marks in the brushing range was calculated using image processing software (e.g., ImageJ). The ratio of the brushed area to the brushed area is shown in Table 1. The brushed area was calculated from the product of the maximum width from the tuft at one end to the tuft at the other end in the width direction of the head and the brushing distance (the aforementioned round trip distance).

[0095] The cleaning power test for the interdental spaces was evaluated based on the removal power of artificial plaque applied to a tooth model. First, artificial plaque manufactured by Nissin Corporation was applied to the model teeth of the lower jaw left 5th and left 6th teeth. Next, the toothbrush was applied to the teeth with a brushing machine tilted 45° downward relative to the tooth surface. Then, the toothbrush was moved along the longitudinal direction to clean the lower jaw left 5th and left 6th teeth under the following conditions: load 200g, reciprocating operation time 10 seconds, vibration frequency 240 times / min, and reciprocating distance 20 mm. The interdental spaces of the lower jaw left 5th and left 6th teeth after cleaning with the toothbrush were photographed, and the area of ​​the area where the artificial plaque was removed from the interdental spaces was calculated using image processing software (e.g., ImageJ). The ratio of the area of ​​the artificial plaque removed to the area of ​​the applied artificial plaque is shown in Table 1.

[0096] In the evaluations in Table 1, "S" means excellent, "A" means good, and "B" means poor.

[0097] [Table 1]

[0098] According to Table 1, it was confirmed that when the ratio of the thickness of the long bristles to the thickness of the outer bristles is 0.9 to 1.6, both the brushing pressure evaluation and the cleaning power evaluation are excellent. Therefore, it can be seen that the toothbrush of the present disclosure can improve the interdental cleaning effect of the long bristles while suppressing damage to the gums, such as gum pain, caused by the long bristles when brushing teeth.

[0099] Furthermore, according to Table 1, it was confirmed that when the ratio of the thickness of the long bristles to the thickness of the outer bristles is 1.0 or greater and 1.3 or less, and even more than 1.0 and 1.2 or less, the brushing pressure evaluation and cleaning power evaluation are particularly excellent. [Explanation of symbols]

[0100] 1 Toothbrush 2 Handle 3 Head section 8 Inner hair bundle 9 Outer bundle 10 Long hair 11 Short hair 12 External bristles

Claims

1. A toothbrush in which a plurality of bristles are bundled and planted in a plurality of bristles planting holes formed in a head portion, A plurality of inner hair bundles arranged in a central region in a width direction of the head portion; A plurality of outer hair bundles arranged in both outer regions sandwiching the central region in the width direction; Equipped with the inner hair bundles include a plurality of long bristles having a length longer than that of the outer hair bundles, The toothbrush has a ratio of the thickness of the long bristles to the thickness of the outer bristles constituting the outer bristles bundles of 0.9 or more and 1.6 or less.

2. The toothbrush according to claim 1 , wherein at least a portion of the plurality of long bristles included in the inner bristle bundle are spiral bristles having a twist in the longitudinal direction.

3. The toothbrush of claim 1 , wherein the inner bristle bundles are arranged continuously along the longitudinal direction of the head portion.

4. The toothbrush of claim 1 , wherein the inner bristle bundles include a plurality of short bristles having a length shorter than that of the long bristles.

5. The toothbrush according to claim 1 , wherein some of the outer bristle bundles are arranged two by two in the width direction in both outer regions of the head portion.

6. The toothbrush according to claim 1 , wherein two of the inner bristle bundles are arranged in the width direction in the central region of the head portion.

7. 2. The toothbrush of claim 1, wherein each of the outer bristle bundles is made up of outer bristles having the same bristle length.

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