toothbrush

Abstract

The objective of the present invention is to provide a toothbrush having excellent insertability, operability, and durability. In this toothbrush: the maximum thickness of a head portion (5) is at least 2.0 mm and less than 4 mm; when a brush main body (2) is viewed from the side, a bristle implanting surface side includes a first linear region (S1) extending continuously in a straight line from a bristle implanting surface (5a), a first curved region (E1) which has a center of curvature on the bristle implanting surface side, and which extends in an arc shape from a first inflection point (P1) toward the rear end side, and a second curved region (E2) which has a center of curvature on the rear surface side, which is the opposite side to the bristle implanting surface side, and which extends in an arc shape from a second inflection point (P2), positioned at the rear end of the first curved region, toward the rear end side; and the angle of inclination of a neck portion is at least equal to 8° and at most equal to 25°, where the angle of inclination is represented by the angle at which, when viewed from the side, a straight line passing through a rear end side edge portion of a bristle implanting hole positioned on the rearmost end side, among a plurality of bristle implanting holes, and the second inflection point, intersects a virtual line (50) passing through the rear end side edge portion (Q1) positioned on the rearmost end side, and a rear end side edge portion (Q2) of the bristle implanting hole positioned second from the rear end side.

Description

[Technical field]

[0001] The present invention relates to a toothbrush. This application claims priority based on Japanese Patent Application No. 2019-237178, filed on December 26, 2019, the contents of which are incorporated herein by reference. [Background technology]

[0002] To prevent dental caries and periodontal disease, it is important to remove plaque from the mouth by brushing with a toothbrush. As a toothbrush that can reach the back of the molars (the throat side of the molars) that are difficult to reach with a normal toothbrush, for example, there are toothbrushes on the market that have tufts on the bristles at the tip of the head, making it easier for the bristles to reach the molars.

[0003] Patent Document 1 also discloses a toothbrush having a neck portion in which a curved surface of an arc contour is formed on both the bristle-implanted side and the back side, with the center of the arc being located on the bristle-implanted side and the bristle-implanted side being concave in side view. The toothbrush disclosed in Patent Document 1 has the above-mentioned curved surfaces, which improves ease of insertion into the last molar and operability. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2018 / 079114 Summary of the Invention [Problem to be solved by the invention]

[0005] However, commercially available toothbrushes that have tufts at the tip of the bristles as described above have the problem that only the tufts come into contact with the tooth surface when brushing, making it difficult to brush large areas of the tooth surface.

[0006] The toothbrush disclosed in Patent Document 1 has an S-shaped neck on the back side that first curves back near the boundary between the head and neck and then curves back toward the bristles, so when the toothbrush is inserted deep inside the mouth, the back side of the neck may come into contact with the cheek, reducing the comfort of use, and so a toothbrush with a better comfort of use was desired. Also, if the neck extending from the head is too thick, it becomes necessary to open the lips widely when inserting the toothbrush into the mouth, reducing operability.

[0007] The present invention has been made in consideration of the above points, and an object of the present invention is to provide a toothbrush that is easy to insert and easy to operate. [Means for solving the problem]

[0008] According to a first aspect of the present invention, there is provided a toothbrush comprising a brush body provided with a handle portion along a long axis direction, a neck portion extending from a tip of the handle portion, and a head portion located at the tip of the neck portion, and tufts of bristles are planted in a plurality of bristle planting holes formed in a bristle planting surface of the head portion, the brush body having a shape in which the thickness of the neck portion increases continuously from the head portion toward the handle portion, the maximum thickness of the head portion is 2.0 mm or more and less than 4 mm, and when the brush body is viewed from the side, the brush body has a first linear region extending linearly from the bristle planting surface toward a rear end side, and a second linear region extending linearly from the bristle planting surface toward a rear end side, the ... the first curved region having a center of curvature on the back side opposite the bristle implantation surface side and extending in an arc from a first inflection point located at the rear end of the first curved region to the rear end side, and a second curved region having a center of curvature on the back side opposite the bristle implantation surface side and extending in an arc from a second inflection point located at the rear end of the first curved region to the rear end side, wherein an inclination angle of the neck portion, represented by the angle at which a virtual line passing through a rear end edge of the bristle implantation hole located most rearward in side view and a rear end edge of the bristle implantation hole located second most rearward in side view intersects with the rear end edge of the bristle implantation hole located most rearward in side view and the second inflection point, is 8° or more and 25° or less.

[0009] Furthermore, in the toothbrush according to one aspect of the present invention described above, on the rear side when viewed from the side, there is a second straight region that extends in a straight line from the rear side of the head portion toward the rear end, and a third curved region that has a center of curvature on the bristle implantation surface side and extends in an arc from a third inflection point located at the rear end of the second straight region toward the rear end.

[0010] Furthermore, in the toothbrush according to one aspect of the present invention described above, on the rear side when viewed from the side, there is a fourth curved region having a center of curvature on the rear side and extending in an arc shape from a fourth inflection point located at the rear end of the third curved region toward the rear end.

[0011] In the toothbrush according to one aspect of the present invention, the neck portion has a minimum thickness of 3.0 to 4.0 mm and a length in the major axis direction of 5 mm or more.

[0012] In the toothbrush according to the above aspect of the present invention, the cross-sectional shape at the boundary between the neck portion and the handle portion is elliptical.

[0013] In the toothbrush according to one aspect of the present invention, the length of the neck portion in the major axis direction is not less than 25 mm and not more than 45 mm.

[0014] Furthermore, in the toothbrush according to one aspect of the present invention described above, the position in the longitudinal direction at which the distance between the handle portion on the bristle surface side and the imaginary line is longest in the side view is located toward the tip side rather than the center of the handle portion in the longitudinal direction.

[0015] In addition, in the toothbrush according to one aspect of the present invention, the tip side of the head portion is inclined at an angle of 5° or more and 15° or less toward the bristle surface with respect to the imaginary line when viewed from the side. Effect of the Invention

[0016] The present invention makes it possible to provide a toothbrush that is easy to insert and easy to operate. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a diagram showing an embodiment of the present invention, and is a side view showing the configuration of a toothbrush 1. [Diagram 2] FIG. 2 is a front view of the toothbrush 1 as viewed from the bristle surface 5a side. [Diagram 3] FIG. 2 is an enlarged front view of the head portion 5. [Figure 4] FIG. 2 is an enlarged side view of the head portion 5. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] BEST MODE FOR CARRYING OUT THE DISCLOSURE 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 modified as desired within the scope of the technical idea of ​​the present invention. In addition, 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.

[0019] In the following description, the side on which the bristle surface 5a of the head portion 5, which will be described later, is provided is the front side of the toothbrush 1, and the side opposite the side on which the bristle surface 5a of the head portion 5 faces is the back side of the toothbrush 1. In addition, the direction parallel to the bristle surface 5a and perpendicular to the length direction of the brush body 2 is the width direction of the toothbrush 1, and the direction perpendicular to the bristle surface 5a is the thickness direction of the toothbrush 1. The side on which the head portion 5 is provided is the tip side, and the side on which the handle portion 3 is provided is the rear side.

[0020] Fig. 1 is a side view showing the configuration of toothbrush 1. Fig. 2 is a front view of toothbrush 1 as viewed from bristle surface 5a. Fig. 3 is an enlarged front view of head portion 5. Fig. 4 is an enlarged side view of head portion 5. Brush 40 is omitted from Figs. 2 to 4.

[0021] As shown in FIGS. 1 and 2, the toothbrush 1 of this embodiment includes a brush body 2 and a brush 40, which are made of a resin molded body formed into an elongated shape as a whole.

[0022] The brush body 2 is provided with a handle portion 3 along the longitudinal direction, a neck portion 4 extending from the tip of the handle portion 3, and a head portion 5 provided at the tip of the neck portion 4. The longitudinal direction is the direction in which an imaginary line 50, which will be described later, extends. With the toothbrush 1, the inside of the oral cavity can be cleaned by a plurality of bristle bundles 41 planted on the bristle planting surfaces 5a to 5d of the head portion 5.

[0023] For example, polypropylene (PP) resin, polyacetal (POM) resin, polybutylene terephthalate (PBT) resin, polyethylene terephthalate (PET) resin, etc. are preferably used as the resin constituting the brush body 2. Among them, it is preferable to use PP resin in the present invention, which has a good balance between stress dispersion and strength.

[0024] Furthermore, the flexural modulus (JIS K 7171) of the resin constituting the brush body 2 is preferably 1000 to 2800 MPa, more preferably 1200 to 2500 MPa, and further preferably 1500 to 2000 MPa.

[0025] (Shape of the front side of the brush body) The toothbrush 1 of this embodiment, when the brush body 2 is viewed from the side, has, on the front side of the brush body 2, a first straight line region S1 that extends in a straight line from the bristle surface 5a of the head portion 5 toward the handle portion 3 from the rear end side of the head portion 5 (the "rear end side of the head portion 5" will be described later), a first curved region E1 that has a center of curvature on the front side and extends in an arc from a first inflection point P1 located at the rear end of the first straight line region S1 toward the rear end, and a second curved region E2 that has a center of curvature on the rear side and extends in an arc from a second inflection point P2 located at the rear end of the first curved region E1.

[0026] The first inflection point P1 is located in the head portion 5. The second inflection point P2 forms the boundary between the neck portion 4 and the handle portion 3. That is, the rear end side of the second inflection point P2 is the handle portion 3. Details of the second inflection point P2 at the boundary between the neck portion 4 and the handle portion 3 will be described later.

[0027] (Shape of the back side of the brush body) When the toothbrush 1 of the present embodiment is viewed from the side, on the back side of the brush body 2, from the rear end side of the head portion 5 toward the handle portion 3 side, there is a second substantially straight region S2 that extends linearly from the back of the head portion 5 continuously toward the rear end side, a third curved region E3 that has a center of curvature on the front side and extends in an arc shape from the third inflection point P3 located at the rear end of the second straight region S2 toward the rear end side, and a fourth curved region E4 that has a center of curvature on the back side and extends in an arc shape from the fourth inflection point P4 located at the rear end of the third curved region E3 toward the rear end side. The third inflection point P3 is located in the head portion 5.

[0028] The fourth curved region E4 is the portion where the finger touches when gripping the handle portion 3. The fourth curved region E4 is an arc shape having a center of curvature on the back side and is curved in a concave shape on the back side. Therefore, the finger fits well with the handle portion 3, improving the ease of holding and the ease of brushing the back teeth.

[0029] If the radius of curvature of the first curved region E1 is R1, the radius of curvature of the second curved region E2 is R2, the radius of curvature of the third curved region E3 is R3, and the radius of curvature of the fourth curved region E4 is R4, it is preferable to satisfy the relationship R1 < R3 and R2 < R4. As the radius of curvature R1, it is preferably 60 mm or more and 150 mm or less. As the radius of curvature R2, it is preferably 50 mm or more and 100 mm or less. As the radius of curvature R3, it is preferably 80 mm or more and 400 mm or less. As the radius of curvature R4, it is preferably 70 mm or more and 200 mm or less.

[0030] As the radius of curvature R1, 50 to 250 mm is preferable, 60 to 200 mm is more preferable, and 60 to 150 mm is even more preferable. The radius of curvature R2 is preferably from 50 to 250 mm, more preferably from 60 to 200 mm, and further preferably from 50 to 100 mm. The radius of curvature R3 is preferably from 50 to 600 mm, more preferably from 60 to 500 mm, and further preferably from 80 to 400 mm. The radius of curvature R4 is preferably from 50 to 400 mm, more preferably from 60 to 300 mm, and further preferably from 70 to 200 mm.

[0031] The cross-sectional shape at the boundary (P2) between the neck portion 4 and the handle portion 3 is preferably a substantially square, a substantially polygonal, a perfect circle, or an ellipse, and more preferably an ellipse. The above shapes make it difficult to change grips, which reduces operability when brushing back teeth.

[0032] The cross-sectional area at the boundary between the neck portion 4 and the handle portion 3 is 20 to 80 mm 2 is preferable, and 25 to 55 mm 2 More preferably, 25 to 45 mm 2 It is more preferable that the thickness is not more than 1 mm. By keeping the thickness in the above range, it is possible to ensure durability.

[0033] (Head section) The head portion 5 is a portion for cleaning the oral cavity with a plurality of bristle bundles 41, and is substantially rectangular parallelepiped-shaped with rounded corners. In the present embodiment shown in Figs. 1 and 4, the head portion 5 has a flat plate portion 51 located at the rear end side and having a bristle planting surface 5a on the front side as a reference surface, and an inclined plate portion 52 located at the tip side of the flat plate portion 51. The flat plate portion 51 has a bristle planting surface 5a and a back surface on the opposite side thereof that form flat surfaces. The flat plate portion 51 is substantially parallel to a virtual line 50 described later in side view. In the present embodiment shown in Figs. 1 and 4, the inclined plate portion 52 is included, but the head portion 5 may be composed of only the flat plate portion 51 without the inclined plate portion 52.

[0034] When the inclined plate portion 52 is provided, it is preferable that the inclined plate portion 52 is inclined toward the front side (i.e., the side of the flocked surface) toward the tip side. The inclined plate portion 52 is preferably inclined at an angle of 5° or more and 15° or less with respect to the flat plate portion 51 (virtual line 50 in side view). In the present embodiment shown in Figs. 1 and 4, the inclined plate portion 52 is inclined at an angle of 10° with respect to the flat plate portion 51, for example.

[0035] By inclining the inclined plate portion 52 relative to the flat plate portion 51, the bristles of the bristle bundle 41 at the tip of the head portion 5 become shorter, and the bristles become less likely to bend compared to the bristle bundle 40 at the rear end of the head portion 5, improving the bristles' stiffness, resulting in a high feeling of cleaning the molars. The inclination angle of the inclined plate portion 52 is in the range of 5° to 15°, resulting in an excellent feeling of cleaning the molars.

[0036] As shown in Figures 3 and 4, the inclined plate portion 52 has three bristle-implanted surfaces 5b to 5d with different heights. Each of the bristle-implanted surfaces 5b to 5d is parallel to the bristle-implanted surface 5a. The bristle-implanted surfaces 5b to 5d are successively higher toward the tip side according to the inclination of the inclined plate portion 52. Also, as shown in Figure 1, the bristle length of the bristle bundles 41 planted on the bristle-implanted surfaces 5b to 5d is equal to the bristle length of the bristle bundles 40 planted on the bristle-implanted surface 5a. The bristle length of the bristle bundles 41 planted on the bristle implantation surfaces 5b to 5d may be shorter or longer than the bristle length of the bristle bundles 40 planted on the bristle implantation surface 5a.

[0037] A plurality of tufting holes 6 of the same diameter are arranged in a staggered pattern on the tufting surfaces 5a to 5d. The tufting holes 6 are arranged at positions that are shifted by half a pitch between adjacent rows in the long axis direction. The tufts are planted in each tufting hole 6 by bundling a plurality of brush bristles (filaments) and folding them in half, sandwiching a metal stopper (not shown) called a flat wire between the bristles and driving the bristles into the tufting hole 6.

[0038] The tufting holes 6 are not limited to being arranged in a lattice pattern, but may be arranged in a staggered pattern. The inner diameter of the tufting holes 6 is correlated with the number of tufts of hair to be implanted, and therefore affects the hardness and feel of the tufts. Although the feel can be adjusted to some extent by the thickness and length of the tufts used when implanting the tufts, the range of 1.0 to 3.0 mm is generally preferred.

[0039] The tufting holes 6 in the tufting surface 5a are formed in the normal direction of the tufting surface 5a. The tufting holes 6 in the tufting surfaces 5b to 5d are formed inclined, for example, by 5° with respect to the normal direction of the tufting surfaces 5b to 5d, such that the openings face the rear end side.

[0040] When the hair bundle 41 is folded and driven into the hair implantation hole using a flat wire, the hair can be implanted stably because the hair implantation surfaces 5a to 5d are arranged perpendicular to the driving direction. If the hair implantation hole 6 is significantly inclined with respect to the driving direction (e.g., if it is inclined in a direction perpendicular to the inclined plate portion 52), the hair bundle 41 may be driven unstably, but the hair implantation holes 6 provided in the hair implantation surfaces 5b to 5d are inclined at about 5° in the direction in which the opening faces the rear end, so the hair bundle 41 can be driven without any problems.

[0041] Although the material of the bristle bundle 41 is not particularly limited, examples of the material 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), elastomer (e.g., olefin-based, styrene-based), etc. A combination of these resin materials may also be used, and different resin materials may be used for the core and sheath, such as in a core-sheath structure.

[0042] The bristles constituting the bristle bundle 41 may be, for example, bristles whose diameter gradually decreases toward the bristle tip and whose bristle tip is sharpened (tapered bristles), bristles whose diameter is almost the same from the bristle implantation surface 5a toward the bristle tip (straight bristles), etc. Straight bristles may be bristles whose bristles tip is a flat surface almost parallel to the bristle implantation surface 5a, or bristles whose bristles tip is rounded into a hemisphere. The bristles constituting the bristle bundles 41 planted on the bristle planting surfaces 5b to 5d are preferably tapered bristles or straight bristles. The bristles constituting the bristle bundles 40 planted on the bristle planting surface 5a are preferably tapered or straight. The tips of any of the bristles on the implanted surfaces 5a to 5d may be cut.

[0043] The cross-sectional shape of the bristles is usually circular, but is not limited to such a shape and can be any shape, such as an ellipse, a triangle, a rectangle, a hexagon, a star, a three-leaf clover, or a four-leaf clover.

[0044] The bristle length of the bristle bundle 41 is preferably 8 mm to 13 mm for adults and 6 mm to 9 mm for children from the bristle implant surface 5a of the head portion 5. The thickness (maximum diameter) of the bristles is preferably 0.12 mm to 0.26 mm in terms of usability and usability in the oral cavity. In addition, multiple bristles of different thicknesses may be used in any combination, taking into consideration usability, brushing feel, cleaning effect, durability, etc.

[0045] As a method for implanting the bristle bundles 41, in addition to the flat wire implantation method in which the above-mentioned bristle bundle is folded in half, a flat wire is sandwiched between them, and the bristle bundle is implanted in the bristle implantation hole 6, other methods that can be used include a heat fusion method in which the lower end of the bristle bundle is pressed and fixed into the molten resin that will become the head portion 5, and an in-mold method in which the lower end of the bristle bundle is heated to form a molten mass, and then the cavity of a mold is filled with molten resin to form it integrally with the head portion 5.

[0046] The head portion 5 has a generally rectangular flat plate shape with four apexes cut off by curved lines in a front view. In this embodiment, the boundary O between the head portion 5 and the neck portion 4 is the end point of the curve forming the corner cut off from the neck portion 4 in the front view of the head portion 5, i.e., the position where the bending direction of the curve forming the corner cut off changes. Therefore, the boundary O between the head portion 5 and the neck portion 4 is the position where the curve or straight line forming both edges where the width of the corner cut off part of the head portion 5 from the neck portion 4 in a plan view changes to a curve where the width increases.

[0047] The head portion 5 may have any shape and size that allows easy brushing of the oral cavity, and is not particularly limited in its shape, and may have a shape that gradually narrows from its base end toward its tip end. The head portion 5 may also have a tapered shape that gradually thins from its base end toward its tip end, or may have a rounded shape with a raised center on the back side of the head portion 5.

[0048] The thickness of the head portion 5 is preferably 2 mm or more and less than 4 mm, and more preferably 2.5 to 3.5 mm. When the thickness of the head portion 5 is not constant, the thickness of the head portion 5 is defined as the maximum thickness of the head portion 5. If the thickness of the head portion 5 is less than 2 mm, durability may decrease. If the thickness of the head portion 5 is 4 mm or more, insertion into molars and operability may decrease. By making the thickness of the head portion 5 2 mm or more and less than 4 mm, it is possible to improve insertion into molars and operability without decreasing durability.

[0049] (Neck) The neck portion 4 is a portion that connects the handle portion 3 and the head portion 5 . In this embodiment, the external shape of the neck portion 4 and the handle portion 3 in front and side views is a shape in which multiple gentle curves are connected from a boundary O between the head portion 5 and the neck portion 4 toward the handle portion 3. In side view, the position where the bending direction of the gentle curves is reversed is defined as the boundary between the neck portion 4 and the handle portion 3. That is, in side view of FIG. 1, the curve of the neck portion 4 on the front side is directed from the boundary O toward the handle portion 3, and the position where the center of curvature of the first linear region S1 having a center of curvature on the front side starts to change toward the rear side (second inflection point P2) is defined as the boundary between the neck portion 4 and the handle portion 3.

[0050] The length of the neck portion 4 in the major axis direction is defined as the shortest distance between the position of the inflection point P2 and the boundary O in a side view. The length of the neck portion 4 is preferably 25 to 45 mm, and more preferably 25 to 40 mm. By setting the length of the neck portion 4 within the above range, it is possible to improve the ease of insertion into the molars and the ease of operation when cleaning the molars.

[0051] The cross-sectional shape of the neck portion 4 is preferably a substantially square, a substantially polygon, a perfect circle, or an ellipse, more preferably an ellipse, and even more preferably an ellipse with the thickness direction being the major axis. The thickness of the neck portion 4 increases continuously from the tip side to the rear end side. By continuously increasing the thickness of the neck portion 4, the strength of the neck portion 4 can be increased compared to when the thickness of the neck portion 4 is constant. In addition, by continuously increasing the thickness of the neck portion 4 from the tip side to the rear end side, the opening of the lips does not become large when the neck portion 4 is inserted into the oral cavity, and operability in the oral cavity can be ensured. In addition, since the position of stress concentration applied to the neck portion 4 during brushing is provided on the head portion 5 side, a sufficient distance can be secured to disperse the stress in the direction of the handle portion 3 described later, and excessive bending of the neck portion 4 can be suppressed.

[0052] The minimum thickness of the neck portion is preferably 3.0 to 4.0 mm, and more preferably 3.0 to 3.6 mm. The minimum width of the neck portion is preferably 3.0 to 4.5 mm, and more preferably 3.5 to 4.2 mm. The minimum diameter of the neck portion 4 is preferably 3.0 to 4.0 mm, and more preferably 3.0 to 3.6 mm. If the minimum thickness, width and diameter of the neck portion 4 are less than 3.0 mm, the neck portion 4 may be easily bent, and operability may decrease. If the minimum thickness, width and diameter of the neck portion 4 are more than 4.0 mm, operability in the oral cavity may decrease. By setting the minimum thickness, minimum width and minimum diameter of the neck portion 4 to 3.0 mm or more and 4.0 mm or less, operability can be ensured. Furthermore, the length of the neck portion having a minimum thickness of 3.0 to 4.0 mm is preferably 5 mm or more, more preferably 6 mm or more, and even more preferably 7 mm or more. The length of the neck portion having a minimum width of 3.0 to 4.5 mm is preferably 5 mm or more, more preferably 6 mm or more, and even more preferably 7 mm or more. The length of the neck portion having a minimum diameter of 3.0 to 4.0 mm is preferably 5 mm or more, more preferably 6 mm or more, and even more preferably 7 mm or more. By ensuring that the thickness is within the above range, ease of insertion into the back of the molars and ease of operation can be improved.

[0053] As described above, the first curved region E1 forming the front side of the neck portion 4 in a side view and the third curved region E3 forming the back side of the neck portion 4 in a side view are both arc-shaped with a center of curvature on the front side, so that they follow the curve of the dentition and improve insertion ease when brushing the cheek sides of the back teeth.

[0054] The inclination angle θ of the neck portion 4 is represented by the angle at which a straight line passing through the rear end edge of the tufting hole 6 located most rearward in a side view and the second inflection point P2 intersects with an imaginary line 50 shown in Fig. 1. The imaginary line 50 is a straight line passing through the rear end edge Q1 of the tufting hole 6 located most rearward in a side view and the rear end edge Q2 of the tufting hole 6 located second most rearward. In a typical toothbrush, Q1 and Q2 are parallel to the bristle surface on the rear end side of the head. The inclination angle of the neck portion 4 is preferably 8° or more and 25° or less.

[0055] If the inclination angle of the neck portion 4 is less than 8°, the lips must be opened widely to the side when brushing the cheek side of the molars, which may reduce ease of insertion and operability. If the inclination angle of the neck portion 4 is more than 25°, the wrist must be bent widely when changing the area to be brushed, which may reduce operability when brushing the molars. By setting the inclination angle of the neck portion 4 to be 8° or more and 25° or less, it is possible to ensure ease of insertion and operability when brushing the cheek side of the molars, and operability when changing the area to be brushed.

[0056] The shortest distance between the second inflection point P2 and the imaginary line 50 in a side view is preferably 5 mm or more and 15 mm or less, and more preferably 8 mm or more and 12 mm or less, which ensures the S-shape and improves ease of insertion into the oral cavity and usability. The shortest distance between the "back side P2'" opposite the second inflection point P2 in a side view and the imaginary line 50 is preferably 1 mm or more and 3 mm or less, and more preferably 1.5 mm or more and 3 mm or less. This ensures an S-shape and improves ease of insertion into the oral cavity and usability.

[0057] As described above, the toothbrush disclosed in Patent Document 1 has an S-shaped neck portion on the back side that first warps back near the boundary between the head and neck and then warps back toward the bristles, so that when the toothbrush is inserted into the oral cavity, the back side of the neck portion may come into contact with the cheek, resulting in a poor feeling of use. On the other hand, in this embodiment, as shown in FIG. 1, the shape of the back side of the head and neck portion in the side view is curved from the third inflection point to the front side, forming a third curved region E3 having a center of curvature on the front side. In other words, the toothbrush does not have a shape that once warps back near the boundary between the head and neck portion. Therefore, when the toothbrush is inserted into the oral cavity, the back side of the neck portion can be reduced from coming into contact with the cheek, improving the feeling of use. Furthermore, by making the thickness of the head portion 5 thin, at 2 to 4 mm, and by making the thickness, width and diameter of the neck portion thin, at 3.0 to 4.5 mm, and making the length in the major axis direction 5 mm or more, the ease of insertion, usability and operability can be further improved. In addition, even if the length of the neck portion 4 is shortened to 25 to 45 mm, the first straight region S1, the first curved region E1 having a center of curvature on the front side, and the second curved region E2 having a center of curvature on the back side are connected by a gentle curve at inflection points P1 and P2, further improving usability and operability.

[0058] (Handle section) The handle portion 3 is a portion that is gripped by a user and is formed in a long columnar shape. In order to ensure a sufficient length for gripping and using the handle portion 3, it is preferable that the length from the boundary O to the rear end of the handle portion 3 in a front view be 100 to 200 mm.

[0059] In this embodiment, when the brush body 2 is viewed from the side, the handle portion 3 has a shape in which the thickness (the distance between the second curved region E2 and the fourth curved region E4) increases continuously from the tip side (the side of the second inflection point P2) toward the rear end side, and after reaching a maximum thickness, the thickness decreases toward the rear end side.

[0060] In addition, in the case where the handle portion 3 has multiple locations with the maximum thickness, the location closest to the neck portion 4 is uniquely defined as the location with the maximum thickness of the handle portion 3. In Fig. 1, the location with the maximum thickness of the handle portion 3 is handle portion 3Amax.

[0061] The handle portion 3 has a long axis direction position P11 where the distance between the front surface in a side view and the imaginary line 50 is the longest (i.e., position P11 is at the maximum height relative to the imaginary line 50 in a side view) located on the handle portion 3A on the tip side of the center in the long axis direction of the handle portion 3. In other words, the handle portion 3 has position P11 at a position closer to the tip side of the head portion than the center position of the length in the long axis direction of the handle portion 3. In a side view, the tip side of the head portion is the handle portion 3A, and the rear end side of the handle portion is the handle portion 3B, with position P11 as the boundary. In the handle portion 3, it is preferable for the position of the front surface in a side view to be close to the tip position of the hair bundle 41 in order to finely control the hair tips.

[0062] Here, the distance between the position P11 and the virtual line 50 is longer than the tip of the bristle bundle 41. On the other hand, the second inflection point P2, which is the tip of the handle part 3 (handle part 3A), is shorter than the tip of the bristle bundle 41. Also, the distance between the virtual line 50 and the rear end of the handle part 3 (handle part 3B) is longer than the tip of the bristle bundle 41. That is, on the front side surface of the handle part 3, the area between the position P11 and the second inflection point P2 has a large change with respect to the position of the tip of the bristle bundle 41, whereas the area between the position P11 and the rear end has a small change with respect to the position of the tip of the bristle bundle 41 and is suitable for fine control of the bristle tip. Therefore, by positioning the position P11 on the handle part 3A, the area suitable for fine control of the bristle tip becomes longer, and the molars can be easily brushed even when the rear end side of the handle part 3 is gripped.

[0063] The shortest distance between the imaginary line 50 and a position P11 on the front surface of the handle portion 3 in a side view is preferably 20 mm or more and 32 mm or less, and more preferably 22 mm or more and 26 mm or less. If the distance between position P11 and the virtual line 50 is less than 20 mm, or if the distance between position P11 and the virtual line 50 exceeds 32 mm, the position of the front surface at the rear end of the handle portion 3 in a side view may be significantly separated from the tip of the hair bundle 41, which may reduce controllability of the hair tip. At position P11 on the front surface of the handle portion 3 in a side view, the shortest distance between imaginary line 50 and position P11', which is the intersection point between imaginary line 50 and the rear side surface facing position P11 and extends perpendicular to imaginary line 50, is preferably 8 mm or more and 12 mm or less, and more preferably 10 mm or more and 12 mm or less. This ensures an S-shape and improves ease of insertion into the mouth and usability.

[0064] Moreover, it is preferable that the rear side of the handle portion 3 does not intersect with the imaginary line 50 up to the end portion of the handle portion. In a side view, the shortest distance between the rear surface of handle portion 3B at the distal end side of the handle portion and imaginary line 50 is preferably 8 mm or more and 20 mm or less, and more preferably 10 mm or more and 15 mm or less. The shortest distance between the extreme end of the handle portion and the imaginary line 50 in a side view is preferably 8 mm or more and 20 mm or less, and more preferably 12 mm or more and 18 mm or less. This makes it possible to ensure the S-shape, and improves ease of insertion into the oral cavity and usability. Moreover, the shortest distance of the line segment connecting the boundary O and the position P11 in a side view is preferably 70 to 110 mm, more preferably 80 to 110 mm, further preferably 80 to 100 mm, and particularly preferably 90 to 100 mm. Moreover, the shortest distance of the line segment connecting the inflection point P2 and the position P11 in a side view is preferably 40 to 80 mm, and more preferably 50 to 70 mm.

[0065] The cross-sectional shape of the handle portion 3 is preferably a substantially square, a substantially polygonal, a perfect circle, or an ellipse, more preferably an ellipse, and even more preferably an ellipse with the major axis extending in the width direction. The thickness of the handle portion 3 is greatest at the handle portion 3A. The maximum thickness of the handle portion 3A is preferably 9 mm or more and 14 mm or less, and more preferably 10.5 mm or more and 12.5 mm or less.

[0066] The width of the handle portion 3 is greatest at the handle portion 3A. The maximum width of the handle portion 3A is preferably 11 mm or more and 16 mm or less, and more preferably 12.5 mm or more and 14.5 mm or less. This allows the handle portion 3 to be easily grasped, and provides excellent operability using a palm grip or the like. It is preferable that the handle portion 3A has the maximum thickness and width. This ensures an S-shape and improves ease of insertion into the oral cavity and usability, while also making the handle portion 3 easy to hold and providing excellent operability with a palm grip, etc. The shortest distance between the imaginary line 50 and the position where the handle portion 3 has the maximum thickness in a side view (handle portion 3Amax) is preferably 20 mm or more and 32 mm or less, and more preferably 22 mm or more and 26 mm or less. At the position (handle portion 3Amax) where the handle portion 3 is at its maximum thickness in a side view, the shortest distance between the imaginary line 50 and handle portion 3Amax', which is the intersection point between the imaginary line 50 and the rear surface facing the handle portion 3Amax and extends perpendicularly to the imaginary line 50, is preferably 8 mm or more and 12 mm or less, and more preferably 10 mm or more and 12 mm or less. This ensures an S-shape to improve ease of insertion into the mouth and usability, and also makes the handle portion 3 easy to hold, resulting in excellent operability with a palm grip, etc.

[0067] The ratio of the maximum thickness of the handle portion 3 to the maximum width of the handle portion 3 (maximum thickness of the handle portion 3 / maximum width of the handle portion 3) is preferably 0.6 or more and 1.3 or less, and more preferably 0.7 or more and 1.0 or less.

[0068] The ratio of the maximum thickness of the handle portion 3 to the maximum thickness of the head portion 5 (maximum thickness of the handle portion 3 / maximum thickness of the head portion 5) is preferably 2.3 or more and 7.0 or less, and more preferably 2.8 or more and 4.2 or less.

[0069] The ratio of the maximum thickness of the handle portion 3 to the minimum thickness of the neck portion 4 (maximum thickness of the handle portion 3 / minimum thickness of the neck portion 4) is preferably 2.0 or more and 5.6 or less, and more preferably 2.6 or more and 4.8 or less.

[0070] The cross-sectional area of ​​the handle portion 3 is maximum at the handle portion 3A. The cross-sectional area of ​​the handle portion 3 is 70 mm 2 Above 200mm 2 Preferably less than 90 mm 2 More than 150mm 2 It is more preferable that:

[0071] In the toothbrush 1 of this embodiment, the first inflection point P1 is located in the head portion 5, and the second inflection point P2 is located on the rear end side. In a side view (FIG. 1) of the brush body 2, the shortest distance connecting the first inflection point P1 and the second inflection point P2 when viewed from the front side (FIG. 2) is preferably 28 mm or more and 40 mm or less, and more preferably 30 mm or more and 35 mm or less. This allows the surface between the head portion 5 and the handle portion 3 to be continuously connected by a smooth curve via the neck portion 4 in a shape in which the thickness of the neck portion 4 increases continuously from the head portion 5 toward the handle portion 3. In addition, the neck portion 4 can be made thinner over its entire length.

[0072] In the toothbrush 1 of this embodiment, the first inflection point P1 is located in the head portion 5, and the second inflection point P2 is located on the rear end side. In a front view of the brush body 2, the distance between the first inflection point P1 and the second inflection point P2 is preferably 28 mm or more and 45 mm or less, more preferably 28 mm or more and 41 mm or less, and even more preferably 30 mm or more and 40 mm or less. This allows the surface between the head portion 5 and the handle portion 3 to be continuously connected by a smooth curve via the neck portion 4, in a shape in which the thickness of the neck portion 4 increases continuously from the head portion 5 toward the handle portion 3. Also, the neck portion 4 can be made thinner over its entire length.

[0073] The toothbrush 1 of this embodiment has a thin head portion 5, a narrow neck portion 4, and a thick handle portion 3, so that when a load is applied to the head portion 5 during brushing, stress is first concentrated at the first inflection point P1 via the first substantially linear region S1 on the front side. The first inflection point P1 is located in a position opposite to the second substantially linear region S2 on the rear side. Therefore, in the second substantially linear region S2, a resistance (repulsion) acts in the front direction to disperse the stress received in the rear direction at the first inflection point P1.

[0074] When stress is concentrated in the back direction at the first inflection point P1, if the region opposite the first inflection point P1 has a substantially linear shape (the second substantially linear region S2), a reaction force acts on the front side in the second substantially linear region S2. This reaction force is then transmitted to the first curved region E1 on the front side opposite the second substantially linear region S2.

[0075] Furthermore, when the first curved region E1 having a center of curvature is provided on the front side of the brush body 2, if stress is concentrated in the rear direction at the first inflection point P1, a resistance force tends to act on the front side due to the nature of the curved shape. In addition, the larger the radius of curvature of the first curved region E1, the easier it is to disperse and transmit the resistance force.

[0076] Furthermore, if a third curved region E3 having a center of curvature on the front side is provided on the rear side of the brush body 2, when a stress in the rear direction is transmitted to the third inflection point P3, a resistance force is likely to act on the front side in the third curved region E3 due to the nature of the curved shape. In addition, the larger the radius of curvature of the third curved region E3, the more easily the resistance force is dispersed and transmitted.

[0077] In a side view of the brush body 2, the second inflection point P2 is located at an opposing position within the third curved region E3. In addition, since the first curved region E1 and the third curved region E3 have a shape with a center of curvature on the front side of the brush body 2, the direction of the resistance at the second inflection point P2 is the front side. Here, if the second curved region E2 having a center of curvature on the back side of the brush body 2 is provided on the front side, when a resistance in the front direction acts at the second inflection point P2, the resistance tends to act on the back side due to the nature of the curved shape. In addition, the larger the radius of curvature of the second curved region E2, the easier it is to disperse and transmit the resistance.

[0078] In this embodiment, when a frontal resistance acts at the second inflection point P2, the rearward resistance due to the second curved region E2 acts more easily and is transmitted toward the handle portion 3, allowing stress dispersion. In addition, the frontal force from the third curved region E3 is also transmitted to the second curved region E2, so it is expected that the acting resistance will cancel each other out on the front side and rear side, allowing for better stress dispersion. In the toothbrush 1 of this embodiment, the characteristic shapes of the front and rear sides of the brush body 2 in a side view prevent stress concentration on the neck portion 4, and distribute stress over the entire brush body 2 from the head portion 5 to the handle portion 3, thereby suppressing bending of the neck portion 4.

[0079] The handle portion 3 is provided with a covering material 8 on a part of its outer circumferential surface. The covering material 8 is made of soft resin. The covering material 8 is provided in a counterclockwise spiral shape toward the rear end. The covering material 8 may be configured to cover the entire outer circumferential surface of the handle portion 3. As the soft resin, for example, elastomer resins such as polyolefin-based elastomers, styrene-based elastomers, polyester-based elastomers, and polyurethane-based thermoplastic elastomers, or silicone resins can be used.

[0080] By providing the covering material 8 on part of the outer circumferential surface of the handle portion 3, the toothbrush 1 has improved grip when holding the handle portion 3, and improved operability when brushing the back teeth.

[0081] As described above, with the toothbrush 1 of the present embodiment, it is possible to provide a toothbrush that is easy to insert, easy to operate, and durable, even when brushing the back teeth.

[0082] 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. EXAMPLES

[0083] The effects of the present invention will be more clearly understood by the following examples. Note that the present invention is not limited to the following examples, and can be modified as appropriate without departing from the spirit and scope of the present invention.

[0084] (Examples 1 to 4, Comparative Examples 1 to 3) In the present example, toothbrushes of Examples 1 to 4 and Comparative Examples 1 to 3 were produced according to the specifications shown in Table 1 below. A toothbrush similar to that shown in FIG. 1 and FIG. The overall length of the handle body of each example of toothbrush was 180 mm, and the dimensions of each part were as shown in Table 1. On the head portion, 23 pieces of bristles (made of PBT: 7.5 mil) were bundled together to form a bristles bundle, which were then planted in the bristles planting pattern shown in FIG. 2 to provide a bristles planted portion.

[0085] [Easy operation when cleaning molars in the oral cavity] Ten monitors cleaned the oral cavity and evaluated the ease of use of each toothbrush. Usability was evaluated on a 7-point scale from 1 to 7, with higher scores being given to those who felt the operability was better. The average scores of the 10 monitors were classified into the following criteria to judge the operability in the oral cavity. <Judgment criteria> ◎◎(twin double-circle mark): Average score is 6 points or above. ◎ (double-circle mark): Average score is 5 or more but less than 6 points. ○ (circle mark): Average score is 4 or more but less than 5 points. △ (triangle mark): Average score is 3 or more but less than 4 points. ×(cross mark): Average score is 2 or more but less than 3 points.

[0086] [Usability when cleaning molars in the oral cavity] Ten monitors cleaned the inside of the mouth and evaluated the feel of each toothbrush in terms of the way it felt when the back side of the neck of the toothbrush touched the cheek when the toothbrush was inserted into the mouth. Usability was evaluated on a seven-point scale from 1 to 7 points, with higher scores indicating that the back of the neck did not touch the cheek when inserted into the mouth and that insertion was easy. The average scores of the 10 monitors were classified according to the following criteria to judge the operability in the oral cavity. <Judgment criteria> ◎◎: Average score is 6 or above. ◎: Average score is 5 or more but less than 6 points. ○: Average score is between 4 and 5 points. △: Average score is between 3 and 4 points. ×: Average score is 2 or more but less than 3 points.

[0087] [Table 1]

[0088] As shown in Table 1, the toothbrushes of Examples 1 to 4, in which the maximum thickness of the head portion was 2.0 mm or more and less than 4 mm, and the inclination angle of the neck portion was 8° or more and 25° or less, showed good results in terms of both ease of use when cleaning the back teeth and the feel of use when cleaning the back teeth.

[0089] 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. [Industrial Applicability]

[0090] The present invention is applicable to toothbrushes. [Explanation of symbols]

[0091] REFERENCE SIGNS LIST 1...toothbrush, 2...brush body, 3...handle portion, 4...neck portion, 5...head portion, 5a-5d...bristle implantation surface, 6...bristle implantation holes, 41...bristle bundle, 50...virtual line, E1...first curved region, E2...second curved region, E3...third curved region, E4...fourth curved region, P1...first inflection point, P2...second inflection point, P3...third inflection point, P4...fourth inflection point, S1...first linear region, S2...second linear region, θ...tilt angle

Claims

1. The brush body includes a handle portion along a longitudinal axis, a neck portion extending from a tip of the handle portion, and a head portion located at the tip of the neck portion. A toothbrush having tufts of bristles planted in a plurality of tufting holes formed on the tufting surface of the head portion, The brush body has a shape in which the thickness of the neck portion increases continuously from the head portion toward the handle portion, The maximum thickness of the head portion is equal to or greater than 2.0 mm and less than 4 mm; When the brush body is viewed from the side, the brush body has a first linear region on the bristle-implanted surface side, which extends linearly from the bristle-implanted surface toward the rear end side, a first curved region having a center of curvature on the bristle-implanted surface side and extending in an arc shape from a first inflection point located at the rear end of the first linear region toward the rear end side, and a second curved region having a center of curvature on the back side opposite to the bristle-implanted surface side and extending in an arc shape from a second inflection point located at the rear end of the first curved region toward the rear end side, A second linear region extending linearly from the rear surface of the head portion toward the rear end side on the rear surface side in the side view; a third curved region having a center of curvature on the brush-implanted surface side and extending in an arc shape from a third inflection point located at a rear end of the second linear region toward the rear end side, a fourth curved region having a center of curvature on the rear side and extending in an arc shape from a fourth inflection point located at a rear end of the third curved region toward the rear end, When a radius of curvature of the first curved region is R1, a radius of curvature of the second curved region is R2, a radius of curvature of the third curved region is R3, and a radius of curvature of the fourth curved region is R4, a relationship of R1<R3 and R2<R4 is satisfied, a center of curvature of the radius of curvature of the second curved region is located closer to the head portion than a center of curvature of the radius of curvature of the fourth curved region; an inclination angle of the neck portion, which is represented by an angle at which a straight line passing through the rear end edge of the tufting hole located at the rear end side in the side view and the second inflection point intersects with an imaginary line passing through the rear end edge of the tufting hole located at the rear end side in the side view and the second inflection point, among the plurality of tufting holes, in the side view; is 9° or more and 25° or less; a position in the longitudinal direction where a distance between the handle portion on the hair-implanted surface side and the imaginary line is longest in the side view is located toward a tip side from a center of the handle portion in the longitudinal direction, A toothbrush characterized in that the position along the longitudinal axis at which the handle portion has its maximum thickness is located toward the tip side of the center of the handle portion along the longitudinal axis, straddling the second curved region and the fourth curved region.

2. The length of the major axis of the neck portion having a minimum thickness of 3.0 to 4.0 mm is 5 mm or more.

2. The toothbrush of claim 1.

3. The cross-sectional shape at the boundary between the neck portion and the handle portion is elliptical.

3. The toothbrush according to claim 1 or 2.

4. The length of the neck portion in the major axis direction is 25 mm or more and 45 mm or less. A toothbrush according to any one of claims 1 to 3.

5. 5. The toothbrush according to claim 1, wherein the toothbrush does not have a shape that temporarily curves backward near the boundary between the head portion and the neck portion.

6. The tip side of the head portion is inclined at an angle of 5° or more and 15° or less toward the hair implantation surface with respect to the imaginary line in the side view.

6. A toothbrush according to any one of claims 1 to 5.

Images