Toothbrush and method for manufacturing the same

Abstract

To provide a toothbrush capable of removing moisture to be likely stored in bristles on a rear surface side of a head part and keeping cleanliness, and also to provide a manufacturing method of the toothbrush.SOLUTION: A toothbrush 1 includes: bristles 4a; and a head part 2 where bristle bundles 4 obtained by binding a plurality of bristles are implanted. The head part has an implantation surface 2a, and implantation holes 3 are formed in the implantation surface. The bristle bundles are double-folded and implanted in the implantation holes by allowing folded parts being double-folded parts to be leading parts in a double-folded state. The implantation holes penetrate a rear surface on the opposite side of the implantation surface in the head part. The folded parts of the bristle bundles are exposed in openings on a rear surface side.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a toothbrush and a method for manufacturing a toothbrush, and in particular to a toothbrush having bristle holes penetrating a head portion and a method for manufacturing a toothbrush including a toothbrush preparation step of preparing a toothbrush having a head portion provided with penetrating bristle holes. [Background technology]

[0002] Conventionally, there is a toothbrush that includes a brush and a head portion in which a bristle bundle formed by bundling a number of the bristles is implanted, the head portion having a bristle implantation surface with implantation holes opened in the bristle implantation surface, the bristle bundle being folded in two, and in this folded state, the folded portion is implanted in the bristle implantation hole with the folded portion at the front. (Patent Document 1)

[0003] In conventional toothbrushes, the bristle bundle is folded in half into a U-shape, and the flat wire sandwiched between the bristle bundle is driven into the bristle hole, thereby allowing the bundle of multiple bristles to be implanted into the head portion.

[0004] The flat wire is a thin rectangular plate of metal or the like, which is inserted into the entrance of the tufting hole, and the edges of the two opposing sides of the flat wire move partway through the tufting hole, drawing two grooves in the axial direction on the inner peripheral surface of the tufting hole. However, because the two grooves are narrow, even if the flat wire tries to return in the opposite direction through the tufting hole, friction in the axial direction of the tufting hole is generated between the edges of the two sides and the grooves. As a result, the brush maintains its implanted state without falling out of the tufting hole.

[0005] In addition, since the head portion has a constant thickness, the tufting holes can be opened to a depth corresponding to the thickness, and the length of the groove can be ensured to generate the necessary friction.

[0006] As a result, conventional toothbrushes can reliably fix the bristles to the head portion while employing a simple assembly method of hammering the flat wire and the bristle bundle into the bristle holes. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2016-63912 A Summary of the Invention [Problem to be solved by the invention]

[0008] In conventional toothbrushes, the bristles are not exposed on the back side of the head because the bristles have a bottom surface and the bristles are closed on the back side of the head, which is the opposite side to the bristles.

[0009] On the other hand, when a toothbrush is used to clean the teeth, gums, and other parts of the oral cavity, moisture such as the user's saliva and cleaning liquids may run down the bristles and accumulate at the bottom of the bristle holes. In addition, moisture such as running water and cleaning water used to clean the toothbrush may accumulate. Since the bristle bundles are stuck in the bristle holes, it is difficult for this moisture to flow back through the bristle holes and be discharged. Furthermore, since the bristles on the bottom side are contained inside the blocked bristle holes, they cannot be easily dried with air, gas, or other gas, and cannot be wiped with absorbent materials such as cloth, cotton, or paper.

[0010] As a result, the accumulation of moisture makes it easy for bacteria to grow, making it difficult to keep the toothbrush clean.

[0011] In view of the above problems, the present invention aims to provide a toothbrush that can remove moisture that tends to accumulate on the bristles on the back side of the head and keep it clean, and to provide a method for manufacturing such a toothbrush. [Means for solving the problem]

[0012] (1) The present invention provides a toothbrush comprising a brush and a head portion in which a bristle bundle formed by bundling a number of the bristles is implanted, the head portion having a bristle implantation surface and having bristle implantation holes formed in the bristle implantation surface, the bristle bundle being folded in two and implanted in the folded state into the bristle implantation holes with the folded portion at the leading edge, the bristle implantation holes penetrating the back surface of the head portion opposite the bristle implantation surface, and the bristle bundle having the folded portion exposed at the opening on the back surface. Also, a toothbrush may include a brush and a head portion in which a bristle bundle formed by bundling a plurality of the bristles is implanted, the head portion having a bristle implantation surface and having bristle implantation holes in the bristle implantation surface, the bristle bundle being folded in two and implanted in the folded state into the bristle implantation holes with the folded portion at the leading edge, the bristle implantation holes penetrating the back surface of the head portion opposite the bristle implantation surface, the bristle bundle having the folded portion exposed at the opening on the back surface, and part or all of the folded portion protruding from the head portion. Furthermore, the inside of the folded portion may be placed within the tufting hole.

[0013] That is, in the toothbrush of the present invention, the folded-back portion of the bristle bundle is exposed at the opening on the back side, so that the toothbrush can be used to clean the oral cavity, and when cleaning, moisture such as saliva, medicinal liquid, running water, cleaning water, etc. can be wiped off by applying a water-absorbent material such as cloth, cotton, or paper to the exposed bristle bundle. By removing moisture in this way, the toothbrush can be kept clean.

[0014] In addition, when the hair bundle comes into contact with the inner wall of the implantation hole, the turned-back portion where the hair bundle makes a U-turn does not come into contact with the inner wall, whereas the hair bundle comes into contact with the inner wall at the straight portion, which is a generally columnar bundle continuing from the turned-back portion on the implantation surface side of the hair bundle. Even if the hair bundle tries to exit the implantation hole in the opposite direction due to an external force, a frictional force is generated between the hair bundle and the inner wall in the axial direction of the implantation hole at the straight portion, and the hair bundle tries to stay in place.

[0015] Therefore, the toothbrush of the present invention is configured so that the folded portion is exposed on the back side, and therefore the area of ​​contact with the inner wall in the straight portion is larger than that of a toothbrush that does not have this exposed portion. Also, even if the thickness of the head portion is made smaller, the frictional force is large and the bristle bundles can be reliably kept in the planted position. And, by the bristle bundles staying in the planted position, the water-absorbing material can be applied to the exposed bristle bundles for a long time, and the toothbrush can be kept clean. Moreover, the bristles are less likely to fall out of the bristle planting holes, and the toothbrush can be used for a long time.

[0016] Incidentally, it is known that by reducing the thickness of the head portion, the toothbrush can more easily reach the back teeth and clean the inside of the oral cavity. Therefore, the toothbrush of the present invention makes it easy to clean the inside of the oral cavity and can be used for a long time.

[0017] (2) The hair tuft may further include a flat wire that is driven into the tufting hole, and the tuft may be folded in two by the flat wire and then pushed into the tufting hole.

[0018] That is, the flat wire is inserted from the entrance of the tufting hole, and the edges of the two opposing sides of the flat wire move through the tufting hole so as to draw two axial grooves on the inner peripheral surface of the tufting hole. However, because the two grooves are shallow and narrow, even if the flat wire tries to return to the tufting hole in the opposite direction, friction in the axial direction of the tufting hole is generated between the edges of the two sides and the grooves. As a result, the brush maintains its implanted state without falling out of the tufting hole.

[0019] In this case, for example, when there are two types of head parts of the same plate thickness, and the folded-back part is not exposed in one head part and the folded-back part is exposed in the other head part, the other head part can fold the bristle bundle in two at a deeper position, and the depth to which the flat line can be inserted in the one head part is greater than the depth of the other head part. In this way, the toothbrush of the present invention is configured so that the folded-back part is exposed in the head part, so that the flat line can be pushed deeper and the friction between the edges of the two sides and the grooves is large.

[0020] As described above, by making the friction relatively large, the toothbrush of the present invention can generate the necessary amount of friction even if the plate thickness of the head portion is made thinner.

[0021] By reducing the thickness of the head portion, the toothbrush can more easily reach the back teeth and clean the inside of the oral cavity. Therefore, the toothbrush of the present invention makes it easier to clean the inside of the oral cavity and can be used for a long time.

[0022] (3) The inner space of the tufting hole may be formed in an approximately cylindrical shape, and the flat line may be arranged so that the lower end of the flat line, which is one side on the rear side, is located on the tufting surface side of a virtual bottom surface of the tufting hole, which is the virtual rear side end surface of the approximately cylindrical shape.

[0023] In other words, by configuring one side of the flat line to be located closer to the implantation surface than the imaginary bottom of the implantation hole, the flat line does not protrude beyond the imaginary bottom of the implantation hole on the rear side of the head part, thereby preventing accidents such as the flat line protruding from the head part and injuring the inside of the user's mouth.

[0024] Thus, the toothbrush of the present invention can be used for a long time in a hygienic manner while preventing injuries to the oral cavity caused by the flat wire.

[0025] (4) The inner space of the tufting hole is formed in a substantially cylindrical shape, and the flat line is such that the lower end of the flat line, which is one side of the rear surface side, is inscribed in a virtual bottom surface of the tufting hole, which is a virtual rear surface side end surface of the substantially cylindrical shape. I will The electrodes may be arranged as follows.

[0026] In other words, by configuring the flat line to be inscribed in the imaginary bottom surface of the tufting hole, the flat line does not protrude beyond the imaginary bottom surface of the tufting hole on the rear side of the head part, thereby preventing accidents such as the flat line protruding from the head part and injuring the inside of the user's mouth.

[0027] At the same time, since the flat line is inscribed in the virtual bottom surface of the tufting hole, it can be positioned at the deepest position of the tufting hole. Therefore, the friction between the flat line and the groove is large, the straight portion is long, and the tuft of tufts adheres more firmly to the inner wall, so that the tuft of tufts can stay more reliably in the planted position and will not fall out even when the plate thickness of the head part is small.

[0028] Thus, the toothbrush of the present invention can be used for a long time in a hygienic manner while preventing injuries to the oral cavity caused by the flat wire.

[0029] (5) The head portion may have a plate thickness in the range of 1.5 mm or more and less than 4.0 mm.

[0030] In the toothbrush of the present invention, even when the thickness of the head portion is made small, the bristle bundles remain securely in the planted position.

[0031] Conventionally, the thickness of the head of a thin toothbrush is said to be about 2.5 mm. Meanwhile, according to the explanation of "Toothbrush JIS S 3016-1995" revised by the Japan Industrial Standards Committee (currently the Japan Industrial Standards Committee) on March 1, 1995, the bristle retention strength is stipulated as "maximum tensile force of 8N or more" based on the resolution of the Standards Committee of the Japan Industrial Standards Committee on June 1, 1990. Therefore, the inventors have found through experiments that, in the case of the toothbrush of the present invention, even if the head is as thin as 1.5 mm, the bristle retention strength shows a value of 15N or more, which is greater than the above-mentioned stipulated value of 8N. Furthermore, even if the head is 1.5 mm or more thick and less than 4.0 mm thick, the bristle retention strength shows the above-mentioned value of 15N or more. Furthermore, the same experiment revealed that even when the plate thickness of the head portion is 4.0 mm or more and 5.0 mm or less, the hair retention strength decreases when some of the tufting holes have a small diameter, but still shows the above-mentioned value of 15 N or more.

[0032] In this way, the toothbrush of the present invention can set the thickness of the head portion to the range of 1.5 mm or more and 5.0 mm or less, and by forming the thickness to the range of 1.5 mm or more and less than 4.0 mm, it can have sufficient bristle retention strength, which is more desirable for a toothbrush.

[0033] (6) The implantation hole may have a reduced diameter portion whose inner diameter is smaller than the opening diameter in the implantation surface.

[0034] That is, when the bristles are implanted, the narrowed portion of the implantation hole prevents the bristles from being unnecessarily pushed toward the back side. Therefore, the toothbrush of the present invention has the bristles implanted at a predetermined depth and can be easily manufactured. Furthermore, the bristles do not fall out toward the back side even during use, and the bristles do not fall out of the implantation hole, so the toothbrush can be used for a long time.

[0035] (7) The reduced diameter portion may have a virtual bottom surface, which is an imaginary rear end surface of the inner space, coincident with a virtual bottom surface of the tufting hole.

[0036] That is, since the virtual bottom surface of the reduced diameter portion coincides with the virtual bottom surface of the tufting hole, the reduced diameter portion is biased toward the back side of the tufting hole. Since the depth to which the tuft is pushed is restricted by the reduced diameter portion, the tuft is pushed deeper and the contact area of ​​the straight portion with the inner wall of the tufting hole is larger than when the reduced diameter portion is located closer to the tufting surface. Therefore, the frictional force generated between the straight portion and the inner wall is large, and the risk of the tuft being pulled out from the tufting surface is small.

[0037] In addition, since the flat wire can be inserted deeper, the frictional force generated between the flat wire and the groove in the tufting hole is large, and the flat wire that holds the tuft of hair is prevented from returning to the tufting surface side. This also reduces the risk of the tuft of hair falling out from the tufting surface side.

[0038] (8) The flat line may be disposed such that a lower end of the flat line is circumscribed on an imaginary upper surface of the reduced diameter portion, which is an imaginary end surface of the inner space of the reduced diameter portion on the side of the flocking surface.

[0039] In other words, since the flat wire circumscribes the imaginary upper surface of the reduced diameter portion, it does not penetrate any further into the reduced diameter portion and is not inserted therein. Therefore, it is not necessary to apply a larger pressure to fit the flat wire into the reduced diameter portion whose inner diameter is smaller than the opening diameter in the bristle implantation surface, and the toothbrush of the present invention can be easily manufactured.

[0040] (9) The inner space of the bristle implantation hole may be formed in a substantially cylindrical shape, and the folded portion of the bristle bundle may be inscribed in the virtual bottom surface of the bristle implantation hole, which is the virtual rear end surface of the substantially cylindrical shape. Furthermore, a toothbrush may include a brush and a head portion into which a bristle bundle formed by bundling a plurality of the bristles is implanted, the head portion having a bristle implantation surface and having bristle implantation holes formed in the bristle implantation surface, the bristle bundle is folded in two, and implanted in the bristle implantation hole in this folded state with the folded portion as the leading edge, the bristle implantation hole may have an inner space formed in a substantially cylindrical shape and penetrate the rear surface opposite to the bristle implantation surface of the head portion, the bristle bundle has the folded portion exposed at the opening on the rear side, and the folded portion may be inscribed in the virtual bottom surface of the bristle implantation hole, which is the virtual rear end surface of the substantially cylindrical shape. The folded portion may have an inner side where the folded portion is folded twice, the inner side being fitted within the tufting hole.

[0041] In other words, the folded part of the bristle bundle is inscribed in the virtual bottom surface of the bristle implantation hole, so it does not protrude further to the back side. Therefore, even if the bristle bundle is implanted with the back side of the head part abutting a flat surface such as a workbench, the protruding part of the toothbrush of the present invention does not interfere with the flat surface. In this way, the toothbrush can be easily manufactured.

[0042] (10) The present invention A method for producing the toothbrush described in (1) above, comprising the steps of:The present invention provides a method for manufacturing a toothbrush, comprising: a preparation step including a toothbrush preparation step of preparing a toothbrush having a head portion with a bristle implantation hole passing therethrough; and an implantation step of folding a bristle bundle formed by bundling a number of bristles in half by placing a flat line against the bristle bundle, and inserting both the folded bristle bundle and the flat line into one opening of the bristle implantation hole, with the folded portion being the part that is folded in half, at the front, and pushing the folded portion in until it is exposed at the other opening of the bristle implantation hole. The toothbrush may also include a preparation step including a toothbrush preparation step of preparing a toothbrush having a head portion with a bristle implantation hole passing therethrough, and an implantation step of folding a bristle bundle formed by bundling multiple bristles in half by placing a flat line against the bristle bundle, and inserting both the folded bristle bundle and the flat line from one opening of the bristle implantation hole with the folded portion at the front, and exposing the folded portion at the other opening of the bristle implantation hole and pushing in until part or all of the folded portion protrudes from the head portion. Furthermore, the method may include a preparation step including a toothbrush preparation step of preparing a toothbrush having a head portion with a bristle hole passing therethrough, and an implantation step of folding a bristle bundle formed by bundling multiple bristles in half by applying a flat line to the bristle bundle, and inserting both the folded bristle bundle and the flat line from one opening of the bristle implantation hole with the folded portion at the front, exposing the folded portion at the other opening of the bristle implantation hole, and pushing the folded portion inwardly into the virtual bottom surface of the bristle implantation hole, which is the virtual rear end surface in the inner space of the bristle implantation hole, which is formed in an approximately cylindrical shape.

[0043] That is, the toothbrush produced by the method of the present invention has bristles exposed at the other opening, so that it can be used to clean the oral cavity, and when cleaning, the exposed bristles can be covered with absorbent material such as cloth, cotton, or paper to wipe off saliva, medicinal liquids, running water, cleaning water, etc. By removing moisture in this way, the toothbrush can be kept clean.

[0044] (11) The method further includes, before the step of embedding, a step of preparing a flat wire pushing aid having a concave recess on a plane, and the step of embedding includes inserting the flat wire so that the recess overlaps the opening on the other side. Push The method may include a step of attaching an assisting tool to the other opening side of the head portion.

[0045] That is, in the method for manufacturing a toothbrush of the present invention, the recessed portion of the flat wire pushing aid and the other opening of the bristle hole overlap, so that the folded portion protruding from the other opening can be inserted into the recessed portion. As a result, when the toothbrush is placed on a flat surface such as a workbench or device via the flat wire pushing aid and the bristle bundle and the flat wire are pushed into the bristle hole, such a workbench does not get in the way of the folded portion protruding, and the toothbrush can be manufactured efficiently.

[0046] (12) The step of implanting may include a step of inserting the flat wire until the folded portion abuts against a bottom of the recessed portion.

[0047] That is, since the folded part of the bristle bundle abuts against the bottom of the recessed part of the flat wire pushing aid, the depth of the recessed part can regulate the length of the folded part protruding from the other opening. This makes it possible to set the protruding length to a length sufficient for wiping off saliva, medicine, running water, cleaning water, etc., with a water-absorbing material such as cloth, cotton, or paper, and to set it to a length that is not too long for work, use, storage, aesthetics, etc. Moreover, since the friction between the flat wire and the groove is large, the straight part is long, and the bristle bundle adheres more strongly to the inner wall, the bristle bundle can stay in the planted position more reliably and will not fall out even when the plate thickness of the head part is small. In this way, it is possible to manufacture a toothbrush that can remove the moisture, be kept clean, and be used for a long time.

[0048] (13) In addition, in the toothbrush preparation step, a toothbrush having a reduced diameter portion in which the inner diameter of the bristle implantation hole is smaller than the opening diameter of the one of the openings may be prepared, and in the implantation step, the folded portion may be pushed in so as to abut against the reduced diameter portion. Furthermore, there is provided a method for manufacturing a toothbrush including a preparation step including a toothbrush preparation step of preparing a toothbrush having a head portion with a bristle planting hole passing therethrough, and an implantation step of folding a bristle bundle formed by bundling a number of bristles in half by applying a flat line to the bristle bundle, and inserting both the folded bristle bundle and the flat line from one opening of the bristle planting hole with the folded portion at the leading edge, exposing the folded portion at the other opening of the bristle planting hole, and pushing the folded portion inwardly into a virtual bottom surface of the bristle planting hole, which is a virtual rear end face in the inner space of the bristle planting hole which is formed in an approximately cylindrical shape, or until a part or all of the folded portion protrudes from the head portion, wherein in the toothbrush preparation step, a toothbrush having a reduced diameter portion whose inner diameter is smaller than the opening diameter at the one opening is prepared as the toothbrush, and in the implantation step, the folded portion is pushed in so as to abut against the reduced diameter portion.

[0049] That is, when implanting the bristles, the folded portion is pushed into contact with the narrowed portion, so the bristles are prevented from being pushed further into the other opening side by the narrowed portion. Therefore, the toothbrush can be easily manufactured by implanting the bristles at a predetermined depth using the toothbrush manufacturing method of the present invention. Furthermore, the bristles do not fall out to the back side even during use, and the bristles do not fall out of the implantation holes, so the toothbrush can be used for a long time. Effect of the Invention

[0050] In this way, it is possible to provide a toothbrush that can be kept clean by removing moisture that tends to accumulate on the bristles on the back side of the head, and a method for manufacturing such a toothbrush. Also, by reducing the plate thickness of the head, it is possible to provide a toothbrush that is easy to clean inside the oral cavity, and a method for manufacturing such a toothbrush. [Brief description of the drawings]

[0051] [Figure 1] 1(a) is a diagram of a toothbrush 1 according to a first embodiment of the present invention, and FIG. 1(b) is a diagram of the toothbrush 1 in FIG. 1(a) as viewed from the left side. [Diagram 2] 1A is a partial cross-sectional front view of a head portion 2 according to a first embodiment of the present invention, and FIG. [Diagram 3] FIG. 1 is a perspective view of a toothbrush 1 according to a first embodiment of the present invention. [Figure 4] FIG. 2 is an explanatory diagram showing the arrangement of tufting holes 3 according to the first embodiment of the present invention. [Diagram 5] FIG. 2 shows a flow diagram illustrating a method S1000 for manufacturing a toothbrush according to a first embodiment of the present invention. [Figure 6] 1 is a front partial cross-sectional view of a flat wire pushing aid 8 according to a first embodiment of the present invention. [Figure 7] FIG. 2 is an explanatory diagram showing a state in which a flat wire pushing-in aid 8 according to a first embodiment of the present invention is attached to a head portion 2. [Figure 8] 1A is a partial cross-sectional front view of a head unit 102 according to a second embodiment of the present invention, and FIG. [Figure 9] 10A is a schematic diagram of a cylindrical space C of a tuft-implanting hole 103 according to a second embodiment of the present invention, and FIG. 10B is a schematic diagram of a cylindrical space E of a reduced diameter portion of the tuft-implanting hole 103 according to the second embodiment of the present invention. [Figure 10] FIG. 11 shows a flow diagram illustrating a method S1100 for manufacturing a toothbrush according to a second embodiment of the present invention. [Figure 11] 10(a) is a partial cross-sectional front view of a head unit 112 according to a third embodiment of the present invention, and (b) is a partial cross-sectional right side view of the head unit 112. [Figure 12] FIG. 12 shows a flow diagram illustrating a method S1200 for manufacturing a toothbrush according to a third embodiment of the present invention. [Figure 13] 10(a) is a partial cross-sectional front view of a head portion 12 according to a fourth embodiment of the present invention, and (b) is a partial cross-sectional right side view of the head portion 12. [Figure 14] FIG. 13 is an explanatory diagram showing a state in which a flat wire pushing-in aid 8 according to a fourth embodiment of the present invention is attached to a head portion 12. [Figure 15] 13 shows a table showing the results of measuring the bristles retention strength of toothbrush 11 according to a fourth embodiment of the present invention. [Figure 16] 13 shows a graph illustrating the results of measuring the bristles retention strength of toothbrush 11 according to a fourth embodiment of the present invention. [Figure 17] 13A is a partial cross-sectional front view of a head portion 22 according to a fifth embodiment of the present invention, and FIG. [Figure 18] FIG. 13 shows a flow diagram illustrating a method S2000 for manufacturing a toothbrush according to a fifth embodiment of the present invention. [Figure 19]FIG. 13 is an explanatory diagram showing a state in which a flat wire pushing-in aid 8 according to a fifth embodiment of the present invention is attached to a head portion 22. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0052] [First embodiment] 1 to 7 illustrate a first embodiment of the present invention, in which 1 is a toothbrush.

[0053] The head 2 of the toothbrush 1 has a bristle implantation surface 2a, in which a number of bristle implantation holes 3, which are round holes, are formed. The bristle implantation holes 3 are regularly arranged, as shown in the example of FIG. 1(a). As shown in FIGS. 2(a) and (b), the bristle implantation holes 3 penetrate from the bristle implantation surface 2a to the back surface 2b, which is the surface opposite the bristle implantation surface 2a with respect to the head 2. FIG. 3 is a perspective view showing the toothbrush 1 before the bristle bundles 4 are implanted, as in FIG. 1(a), and is an oblique view of the toothbrush 1. The toothbrush 1 is made of synthetic resin, such as saturated polyester (PET), polypropylene (PP), or polyacetal resin (POM).

[0054] A plurality of bristle bundles 4 for cleaning the inside of the oral cavity M, such as teeth and gums (not shown), are implanted in each of the bristle implantation holes 3, and each bristle bundle 4 is formed by bundling individual bristles 4a aligned in the longitudinal direction. In FIG. 1(b), which shows the toothbrush 1 in FIG. 1(a) as viewed from the left side, only one bristle bundle 4 is shown in solid line for ease of viewing, and the remaining bristle bundles 4 are shown gathered together in two-dot chain lines (imaginary lines). The user cleans the inside of the oral cavity M using the bristles 4a on the bristle implantation surface 2a side.

[0055] Fig. 4 is an explanatory diagram showing the arrangement of the tufting holes 3. The state in which the tufts 4 are gathered is shown by a two-dot chain line, similar to Fig. 1(b).

[0056] Each hair bundle 4 is folded in two, and is pushed into each hair implantation hole 3 with the folded part 5 at the leading edge. FIG. 2(a) is a partial front cross-sectional view of the hair bundle 4 folded in two by a flat wire 6 and pushed into the hair implantation hole 3, as seen from the direction of the flat surface of the flat wire 6. FIG. 2(b) is a partial right side cross-sectional view of the head part 2, as seen toward the flat right surface of the flat wire 6. The partial front cross-sectional view is a cross-sectional view including the horizontal section of the flat wire 6, and the partial right side cross-sectional view is a cross-sectional view including the vertical section of the flat wire 6. Hatching is omitted to make the symbols, leader lines, etc. easier to see. FIG. 1(a) shows the state before each hair bundle 4 is implanted and the flat wire 6 is driven in. The flat wire 6 is omitted from FIG. 1(b) and FIG. 4.

[0057] The flat wire 6 is made of a material such as copper or brass, and is hard enough to be driven into the head portion 2 made of synthetic resin.

[0058] In Fig. 2(a), arrows U, D, L, and R indicate the upper side (facing up), the lower side (facing down), the left side (facing left), and the right side (facing right). In Fig. 2(b), in addition to the arrows U and D, arrows F and B indicate the front side (facing forward) and the rear side (facing backward).

[0059] Each bristle bundle 4 includes a straight portion 7, which is a generally columnar bundle continuing to the bristle implantation surface 2a side of the folded portion 5. Here, the straight portion 7 refers to the range from the upper end of the folded portion 5 to the bristle implantation surface 2a in the vertical direction, as shown in Fig. 2(a). Although not shown, the multiple bristles 4a constituting each bristle bundle 4 are arranged in a curved line surrounding the horizontal line lower end 6a, which is the lower end of the horizontal line 6 in front view, in the folded portion 5, and are arranged in a generally linear line in the vertical direction in the straight portion 7.

[0060] At this time, the hair bundle 4 is pushed into the tufting hole 3, so that the straight portion 7 comes into close contact with the tufting hole wall 3a, which is the inner wall of the tufting hole 3.

[0061] A part of the folded portion 5 protrudes and is exposed from the head portion 2 at the opening on the rear surface 2b side. The lower end of the folded portion 5 is located below the rear surface 2b, and the upper end of the folded portion 5 is located above the rear surface 2b.

[0062] The flat wire 6 is disposed so that its lower end 6a is located above the back surface 2b. That is, the inner space of the round tufting hole 3 is formed into a cylindrical tufting hole space C, and this cylindrical tufting hole space C has a virtual tufting hole bottom surface Cb, which is an end surface on the side of the virtual back surface 2b. The flat wire 6 is disposed so that its lower end 6a is located closer to the tufting surface 2a than the virtual tufting hole bottom surface Cb.

[0063] The flat wire 6 is driven downward and inserted into the entrance of the tufting hole 3, and the edges 6b, 6b of the two sides facing each other in the front-to-rear direction draw two axial grooves 2c, 2c on the inner peripheral surface of the tufting hole 3, progressing halfway into the tufting hole 3. However, because the two grooves 2c, 2c are shallow and the width of the grooves 2c, 2c is narrow, even if the flat wire 6 tries to return upward in the tufting hole 3, frictional force is generated in the axial direction of the tufting hole 3 between the edges 6b, 6b of the two sides and the grooves 2c, 2c. As a result, each bristles 4a maintains its implanted state without falling out of the tufting hole 3.

[0064] As described above, the toothbrush 1 has the bristles 4 exposed on the back surface 2b side, so that when the toothbrush 1 is used to clean the inside of the oral cavity M and when cleaning, moisture such as saliva, medicinal liquids, running water, cleaning water, etc. can be wiped off by applying a water-absorbing material such as cloth, cotton, or paper to the exposed bristles 4. By removing moisture in this way, the toothbrush 1 can be kept clean.

[0065] Furthermore, when the hair bundle 4 comes into contact with the wall 3a of the tufting hole, the folded portion 5 does not come into contact with the wall 3a of the tufting hole, whereas the hair bundle 4 comes into contact with the wall 3a of the tufting hole at the straight portion 7. Even if the hair bundle 4 tries to exit the tufting hole 3 upward due to an external force, a frictional force is generated between the hair bundle 4 in the axial direction of the tufting hole 3 and the wall 3a of the tufting hole at the straight portion 7, so that the hair bundle 4 tries to stay in place.

[0066] In the toothbrush 1 of the present invention, the folded portion 5 is exposed from the head portion 2 on the back surface 2b side, and therefore the contact area with the tufting hole wall 3a in the straight portion 7 is larger than in a toothbrush that is not exposed. Therefore, the frictional force is relatively large, and the tufts 4 can stay securely in the planted position.

[0067] Moreover, compared to a toothbrush with no exposed portion, the flat wire 6 can be inserted to a greater depth, so that the flat wire 6 can be pushed in deeper, and the friction between the edges 6b, 6b of the two sides and the grooves 2c, 2c is greater.

[0068] Furthermore, since the lower end 6a of the flat line is positioned closer to the tufting surface 2a than the virtual bottom surface Cb of the tufting hole, the flat line 6 does not protrude downward from the virtual bottom surface Cb of the tufting hole. This prevents the flat line 6 from protruding from the head portion 2 and causing injury to the inside of the mouth M of the user.

[0069] [Manufacturing method] In FIG. 5, S1000 illustrates a method for manufacturing a toothbrush in the first embodiment of the present invention.

[0070] The manufacturing method S1000 of the toothbrush 1 of the present invention includes the steps of preparing S1010 and implanting S1020 in this order.

[0071] The preparation step S1010 includes a toothbrush preparation step S1011 and an aid preparation step S1012. In the toothbrush preparation step S1011, the toothbrush 1 is prepared, and bristle holes 3 are provided in the head portion 2 of the toothbrush 1. The toothbrush 1 is formed by molding the head portion 2 and a handle portion continuous with the head portion 2, for example, by injection molding.

[0072] Meanwhile, in an auxiliary tool preparation step S1012, a flat wire pushing auxiliary tool 8 is prepared, which has a plurality of concave recesses 9 on a flat head receiving surface 8a, as shown in the front partial cross-sectional end view of Fig. 6. In the flat wire pushing auxiliary tool 8, each recess 9 opens upward in the figure.

[0073] Each recess 9 is substantially circular when viewed from the head receiving surface 8a, and the diameter of the recess edge 9a, which is the boundary with the flat portion of the head receiving surface 8a, matches the diameter of each tufting hole 3. The arrangement of each recess 9 in the flat wire pushing aid 8 matches the arrangement of the tufting holes 3 in the head 2 in the left-right and front-back directions. The flat wire pushing aid 8 is made of a material harder than the flat wire 6; for example, when the flat wire 6 is made of brass, it is made of a metal harder than brass.

[0074] The implantation process S1020 includes the steps of attaching the assisting tool S1021, pushing in the assisting tool S1022, and removing the assisting tool S1023, in that order.

[0075] In the aid attachment step S1021, the flat wire pushing aid 8 is attached to the head part 2 so that the back surface 2b of the head part 2 and the head part receiving surface 8a of the flat wire pushing aid 8 are in contact with each other. At this time, the back surface 2b and the head part receiving surface 8a are arranged so that the back surface opening edge 3b, which is the boundary between the flat surface of the back surface 2b and the back surface 2b side opening of each tufting hole 3, and the recess edge 9a overlap. As a result, each tufting hole 3 and each corresponding recess 9 communicate with each other.

[0076] In the pushing step S1022, the bristle bundle 4 consisting of multiple bristles 4a is folded in half by pressing against a flat line 6, and the folded bristle bundle 4 and the flat line 6 are inserted together from the opening on the bristle implantation surface 2a side of the bristle implantation hole 3, starting from the folded part 5 at the front, and the folded part 5 is pushed through the opening on the back surface 2b side of the bristle implantation hole 3 until it protrudes from the head portion 2.

[0077] At this time, the flat wire 6 is driven downward, and the two edges 6b, 6b of the two sides form two grooves 2c, 2c and advance partway into the tufting hole 3. Also, Fig. 7 shows the state in which the flat wire pushing aid 8 is attached to the head part 2, and the tip of the folded part 5 advances to the inside of the recessed part 9 as shown in Fig. 7.

[0078] In the auxiliary tool removal step S1023, the flat wire pushing auxiliary tool 8 is removed from the head part 2 so that the head part receiving surface 8a is separated from the back surface 2b. Through the auxiliary tool removal step S1023, the toothbrush 1 is completed in which the bristles 4a are planted so that the bristle bundles 4 are exposed from the head part 2 on the back surface 2b side.

[0079] In this way, toothbrush 1 cleans the inside of oral cavity M using bristles 4a on bristles surface 2a, and because bristles 4 protrude and are exposed from head 2 on back surface 2b, moisture such as saliva, medicine, running water, and cleaning water can be wiped away by applying absorbent material such as cloth, cotton, or paper to protruding bristles 4 during cleaning. By removing moisture in this way, toothbrush 1 can be kept clean.

[0080] Furthermore, the recessed portion 9 of the flat wire pushing aid 8 overlaps with the opening on the back surface 2b of the tufting hole 3, and the tufting hole 3 and the recessed portion 9 communicate with each other, so that the folded portion 5 protruding from the opening on the back surface 2b can be inserted into the recessed portion 9. As a result, when the toothbrush 1 is placed on a flat surface such as a workbench or device via the flat wire pushing aid 8 and the bristle bundle 4 and the flat wire 6 are pushed into the tufting hole 3, such a workbench or the like does not interfere with the protrusion of the folded portion 5, and the toothbrush 1 can be manufactured efficiently.

[0081] [Second embodiment] 8 to 10 illustrate a second embodiment of the present invention. In the figures, 101 denotes a toothbrush.

[0082] The head 102 of the toothbrush 101 has a bristle implantation surface 102a, which has a number of round implantation holes 103. As shown in Figures 8(a) and 8(b), the implantation holes 103 penetrate from the bristle implantation surface 102a to the back surface 102b, which is the surface opposite the bristle implantation surface 102a with respect to the head 102.

[0083] The tufting hole 103 has a reduced diameter portion 103c whose inner diameter is smaller than the opening diameter in the tufting surface 102a. The reduced diameter portion 103c forms an annular step at its upper end, and forms a step edge 103d which is the inner edge of the step. The step edge 103d forms a circle in a plan view. The inner space occupied by the reduced diameter portion 103c forms a reduced diameter portion cylindrical space E which is approximately cylindrical between the step edge 103d and the rear opening edge 103b.

[0084] 9(a) and (b) show the entire tufting hole 103, and are schematic front cross-sectional views of the tufting hole cylindrical space C and the reduced diameter portion cylindrical space E. FIG. 9(a) shows the tufting hole cylindrical space C, and the hatched portion in FIG. 9(b) shows the reduced diameter portion cylindrical space E. Here, the tufting hole cylindrical space C has a tufting hole virtual bottom surface Cb, which is the end surface on the imaginary back surface 102b side. The reduced diameter portion cylindrical space E has a reduced diameter portion virtual top surface Ea, which is the end surface on the imaginary tufting surface 102a side, and a reduced diameter portion virtual bottom surface Eb, which is the end surface on the imaginary back surface 102b side.

[0085] These imaginary bottom surfaces Cb, Eb are all located at the bottom of the tufting hole 103 because the reduced diameter portion 103c is biased toward the rear surface 102b of the tufting hole 103. In other words, the reduced diameter hole cylindrical space C and the reduced diameter portion cylindrical space E coincide at the reduced diameter portion 103c located closer to the rear surface 102b, so the imaginary bottom surface Cb of the tufting hole and the imaginary bottom surface Eb of the reduced diameter portion coincide with each other.

[0086] 8(a) and 8(b), the flat wire 106 is disposed so that its lower end 106a is located closer to the implantation surface 102a than the imaginary bottom surface Cb of the implantation hole. The flat wire 106 is also disposed so that its lower end 106a circumscribes the imaginary upper surface Ea of the reduced diameter portion and faces downward into the reduced diameter portion cylindrical space E. Then, the pressed folded portion 105 abuts against the step edge 103d, completing the implantation of the tuft 104.

[0087] The other configurations are common to the first embodiment.

[0088] With this configuration, when the toothbrush 101 is implanted, the folded-back portion 105 of the bristle bundle 104 is prevented from being unnecessarily pushed toward the back surface 102b by the stepped edge 103d of the narrowed portion 103c. Therefore, the bristle bundle 104 is implanted at a predetermined depth, and the toothbrush 101 can be easily manufactured. Furthermore, the bristle bundle 104 does not fall out toward the back surface 102b even during use, and the bristles 104a do not fall out of the implantation holes 103, so the toothbrush can be used for a long time.

[0089] In addition, the narrowed portion 103c is biased toward the rear surface 102b of the tufting hole 103, and the depth to which the tuft 104 is pushed is restricted by the narrowed portion 103c, so the tuft 104 is pushed deeper than when the narrowed portion 103c is located closer to the tufting surface 102a. Therefore, the area of ​​the straight portion 107 that comes into close contact with the tufting hole wall 103a is large, and the frictional force generated between the straight portion 107 and the tufting hole wall 103a is large. This reduces the risk of the tuft 104 coming off from the tufting surface 102a.

[0090] Furthermore, since the flat wire 106 can be inserted deeply, a large frictional force is generated between the flat wire 106 and the grooves 102c, 102c in the tufting hole 103, and the flat wire 106 that holds down the tuft 104 is prevented from returning to the tufting surface 102a side. This also reduces the risk of the tuft 104 falling out from the tufting surface 102a side.

[0091] And, since the flat wire 106 is circumscribed on the reduced diameter portion imaginary upper surface Ea, it does not penetrate any further into the reduced diameter portion 103c and is not inserted therein. Therefore, it is not necessary to apply a larger pressure to fit the flat wire 106 into the reduced diameter portion 103c, and the toothbrush 101 can be easily manufactured. On the other hand, the flat wire 106 is pushed in deeper than when the flat wire 106 does not circumscribe the reduced diameter portion imaginary upper surface Ea and stops above the reduced diameter portion imaginary upper surface Ea. This also reduces the risk of the bristle bundle 104 coming off from the bristle implantation surface 102a.

[0092] [Manufacturing method] In FIG. 10, S1100 illustrates a method for manufacturing a toothbrush in accordance with the second embodiment of the present invention.

[0093] The manufacturing method S1100 of toothbrush 101 of the present invention includes the steps of preparing step S1110 and implanting step S1120, in this order.

[0094] The preparation step S1110 includes a toothbrush preparation step S1111 and an aid preparation step S1112. In the toothbrush preparation step S1111, a toothbrush 101 is prepared, and bristle holes 103 are provided in a head portion 102 of the toothbrush 101. The toothbrush 101 is formed by molding the head portion 102 and a handle portion continuous with the head portion 102, for example, by injection molding.

[0095] In this case, the implantation hole 103 has a reduced diameter portion 103c whose inner diameter is smaller than the opening diameter in the implantation surface 102a. The reduced diameter portion 103c forms an annular step at its upper end, and forms a step edge 103d which is the inner edge of the step. The step edge 103d forms a circle in a plan view.

[0096] Next, an implantation step S1120 includes the steps of attaching an assisting tool S1121, pushing in a step S1122, and removing an assisting tool S1123, in that order.

[0097] In the pushing step S1122, the bristle bundle 104 consisting of multiple bristles 104a is folded in half by contacting it with the flat line 106, and the folded bristle bundle 104 and the flat line 106 are inserted together from the opening on the bristle implantation surface 102a side of the bristle implantation hole 103, starting from the folded portion 105, and the folded portion 105 is pushed through the opening on the back surface 102b side of the bristle implantation hole 103 until it protrudes from the head portion 102.

[0098] The pushing step S1122 includes a folded portion contacting step S1122a. By the pushing back portion contacting step S1122a, the tuft 104 advances through the tufting hole 103, and the folded portion 105 contacts the step edge 103d. The tuft 104 is prevented from advancing any further by the step edge 103d, and the tufting is completed.

[0099] The other processes and steps are common to the manufacturing method of the toothbrush in the first embodiment.

[0100] With this manufacturing method, when implanting the bristles, the folded portion 105 is pushed into contact with the narrowed portion 103c, so that the bristles 104 are prevented from being pushed any further toward the back surface 102b by the narrowed portion 103c. Therefore, the bristles 104 are implanted to a predetermined depth, and the toothbrush 101 can be easily manufactured. Furthermore, the bristles 104 do not fall out toward the back surface 102b even during use, and the bristles 104a do not fall out of the bristles implantation holes 103, so that the toothbrush 101 can be used for a long time.

[0101] [Third embodiment] 11 and 12 illustrate a third embodiment of the present invention. In the figures, 111 is a toothbrush.

[0102] The head 112 of the toothbrush 111 has a bristle implantation surface 112a, which has a number of circular bristle implantation holes 113. As shown in Figures 11(a) and 11(b), the bristle implantation holes 113 penetrate from the bristle implantation surface 112a to the back surface 112b, which is the surface opposite the bristle implantation surface 112a with respect to the head 112.

[0103] The tufting hole 113 has a reduced diameter portion 113c whose inner diameter is smaller than the opening diameter in the tufting surface 112a. The reduced diameter portion 113c forms a ring-shaped step at its upper end, and forms a step edge 113d, which is the edge on the inside of this step. The step edge 113d draws a circle in a plan view. The inner space occupied by the reduced diameter portion 113c forms a reduced diameter portion cylindrical space E that is approximately cylindrical between the step edge 113d and the back side opening edge 113b. The reduced diameter portion virtual bottom surface Eb, which is the virtual back side 112b side end surface of the reduced diameter portion cylindrical space E, coincides with the tufting hole virtual bottom surface Cb, which is the virtual back side 112b side end surface of the reduced diameter hole cylindrical space C.

[0104] The folded portion 115 of the bristle bundle 114, which is pushed into the cylindrical space C of the bristle hole, is inscribed in the virtual bottom surface Cb of the bristle hole. In this way, the toothbrush 111 has the bristle bundle 114 exposed on the back surface 112b side, so that when the toothbrush 111 is used to clean the inside of the oral cavity M and when cleaning, moisture such as saliva, medicinal liquid, running water, and cleaning water can be wiped off by applying a water absorbent material such as cloth, cotton, or paper to the exposed bristle bundle 114. By removing moisture in this way, the toothbrush 111 can be kept clean.

[0105] The other configurations are common to the second embodiment.

[0106] With this configuration, toothbrush 111 has folded portion 115 inscribed in virtual bottom surface Cb of the bristle implantation hole, and bristle bundle 114 does not protrude further toward back surface 112b. Therefore, even if bristle bundle 114 is implanted with back surface 112b of head portion 112 in contact with a flat surface such as a workbench, the protruding portion of toothbrush 111 will not interfere with said flat surface. Thus, toothbrush 111 can be easily manufactured.

[0107] [Manufacturing method] In FIG. 12, S1200 illustrates a method for manufacturing a toothbrush according to the third embodiment of the present invention.

[0108] The manufacturing method S1200 of toothbrush 111 of the present invention includes a preparation step S1210 and an implantation step S1220, in that order. The preparation step S1210 includes a toothbrush preparation step S1211. The implantation step S1220 also includes a pushing step S1222. The pushing step 1222 includes a folded portion abutting step S1222a. In the folded portion abutting step S1222a, folded portion 115 abuts against step edge 113d and is inscribed in virtual bottom surface Cb of the tufting hole.

[0109] These processes and steps are common to the toothbrush manufacturing method of the second embodiment. Note that, since the folded portion 115 of the toothbrush 111 of this embodiment does not protrude from the back surface 112b side, the flat wire pushing aid 8 used in the second embodiment is not necessarily required. Therefore, the manufacturing method of this embodiment does not necessarily require the aid preparation step S1112, aid attachment step S1121, and aid removal step S1123 included in the manufacturing method of the second embodiment.

[0110] [Fourth embodiment] 13 to 16 show a fourth embodiment of the present invention, in which 11 is a toothbrush.

[0111] The head 12 of the toothbrush 11 has a bristle implantation surface 12a, and multiple bristle implantation holes 13, which are round holes, are opened in the bristle implantation surface 12a. As shown in Figures 13(a) and (b), the bristle implantation holes 13 penetrate from the bristle implantation surface 12a to the back surface 12b. Multiple bristle bundles 14 are implanted in each bristle implantation hole 13, and each bristle bundle 14 is formed by bundling individual brush bristles 14a. Each bristle bundle 14 is folded in two, and is inserted into each bristle implantation hole 13 with the folded portion 15 at the front end. Figures 13(a) and (b) are partial front and right side cross-sectional views, respectively, showing the state in which the bristle bundle 14 is folded in two by a flat line 16 and inserted into the bristle implantation hole 13.

[0112] Each tuft 14 includes a straight portion 17, which is a generally columnar tuft, continuing from the folded portion 15 on the implantation surface 12a side. As the tuft 14 is pushed into the implantation hole 13, the straight portion 17 comes into close contact with the implantation hole wall 13a, which is the inner wall of the implantation hole 13.

[0113] The folded portion 15 protrudes from the head portion 12 at the opening on the rear surface 12b side and is exposed. The lower end of the folded portion 15 is located lower than the rear surface 12b, and the upper end of the folded portion 15 coincides with the position of the rear surface 12b in the up-down direction.

[0114] The flat line 16 is driven downward, and the edges 16b, 16b of the two sides draw two grooves 12c, 12c until it approaches the lower end of the tufting hole 13. The flat line 16 is then positioned so that its lower end 16a is located above the back surface 12b. In other words, the flat line 16 is positioned so that its lower end 16a is located closer to the tufting surface 12a than the imaginary bottom surface Cb of the tufting hole cylindrical space C of the tufting hole 13.

[0115] The lower end of the straight portion 17 coincides with the position of the back surface 12b in the up-down direction. That is, the thickness of the head portion 12 and the height of the straight portion 17 coincide with each other, and the entire tufting hole wall 13a is in close contact with the straight portion 17.

[0116] FIG. 14 shows the state in which the flat wire pushing aid 8 is attached to the head portion 12, and the folded back portion 15 advances to the inside of the recessed portion 9 as shown in FIG.

[0117] The other configurations are common to the first embodiment.

[0118] In the toothbrush 11 of the present invention, the entire folded portion 15 protrudes and is exposed from the head portion 12 on the rear surface 12b side, so that the straight portion 17 is in close contact with the entire tufting hole wall 13a. This makes the area of ​​contact between the tufts 14 and the tufting hole wall 13a larger, increasing the frictional force, and allowing the tufts 14 to stay securely in the position where they are implanted.

[0119] [Example] Fig. 15 shows the results of measuring the bristle retention strength when the bristles 14a of the toothbrush 11 were pulled out of the bristle hole 13 when the bristles 14a were planted in the bristle hole 13 using the flat wire 16 as shown in Fig. 13. The bristles 14a used were made of nylon, had a thickness of 6 mils, and a length of 33 mm. The toothbrushes 11 prepared had bristle hole 13 diameters of 1.0 mm, 1.2 mm, 1.4 mm, 1.6 mm, 1.8 mm, and 2.0 mm, and head 12 thicknesses represented by the symbol t in Fig. 4 of 1.5 mm, 2.0 mm, 2.5 mm, 3.0 mm, 3.5 mm, 4.0 mm, and 5.0 mm, respectively. For each diameter of the bristle hole 13, the number of bristles 14a constituting each bristle bundle 14 was 22 for 1.0 mm by folding back 11 bristles 14a, 40 for 1.2 mm, 52 for 1.4 mm, 72 for 1.6 mm, 90 for 1.8 mm, and 114 for 2.0 mm.

[0120] When implanting the tufts 14, a flat wire pushing aid 8 was used in accordance with the toothbrush manufacturing method S1000.

[0121] The hair retention strength test was performed using a tensile tester in accordance with the instructions in the aforementioned "Toothbrush JIS S 3016-1995." The pull-out speed in the strength test using the tensile tester was set at 20 mm / min.

[0122] The table in Figure 15 shows the average bristle retention strength (N) when the above-mentioned number of bristles 14a were planted and strength tests were then performed three times for each of the head portion 12 plate thicknesses (mm) shown in each row and bristle hole diameters (mm) shown in each column.

[0123] Fig. 16 shows graphs for each diameter of the tufting holes 13, with the bristle retention strength (N) on the vertical axis and the thickness (mm) of the head portion 12 on the horizontal axis. As the values ​​in Fig. 15 and the graphs in Fig. 16 show, it was confirmed that the bristle retention strength is 15.0N or more in all cases where the thickness of the head portion 12 is 1.5mm or more and 5.0mm or less, which is greater than the 8N specified value based on the resolution of the Standards Committee of the Japanese Industrial Standards Committee dated June 1, 1990. Therefore, the toothbrush 11 of the present invention can set the thickness of the head portion 12 to 1.5mm or more and 5.0mm or less.

[0124] On the other hand, in each of the graphs, it was found that when the diameter of the tufting hole 13 is 1.0 mm, the tufting strength is at its peak when the head portion 12 is 4.0 mm thick, and when the thickness is 4.0 mm or more, the tufting strength decreases as the thickness increases. It was also found that the minimum limit size for the thickness of the head portion 12 in forming the tufting hole 13 of the above dimensions and driving the flat wire 16 is 1.5 mm. As such, when planting the tufts 14 in the straight tufting hole 13 of the above dimensions, it is more preferable that the thickness of the head portion 12 is formed in the range of 1.5 mm or more and less than 4.0 mm.

[0125] Therefore, toothbrush 11 of the present invention, by forming head portion 12 with a plate thickness in the range of 1.5 mm or more and less than 4.0 mm, can have a bristles retention strength that is more desirable for a toothbrush.

[0126] Even if the head portion 12 is extremely thin, such as having a thickness of 1.5 mm or more and less than 2.0 mm, the hair retention strength is 15.0 N or more. Even if the head portion 12 is thin, such as having a thickness of 2.0 mm or more and less than 2.5 mm, the hair retention strength is 25.0 N or more.

[0127] By reducing the thickness of head portion 12 in this way, toothbrush 11 can more easily reach back teeth and clean the inside of the oral cavity. Therefore, toothbrush 11 of the present invention makes it easy to clean the inside of the oral cavity, and bristles 14a are less likely to fall off and can be used for a long time.

[0128] [Fifth embodiment] 17 to 19 show a fifth embodiment of the present invention. In the figures, reference numeral 21 denotes a toothbrush.

[0129] The head 22 of the toothbrush 21 has a bristle implantation surface 22a, and multiple bristle implantation holes 23, which are round holes, are opened in the bristle implantation surface 22a. The bristle implantation holes 23 penetrate from the bristle implantation surface 22a to the back surface 22b, as shown in Figures 17(a) and (b). Multiple bristle bundles 24 are implanted in each bristle implantation hole 23, and each bristle bundle 24 is formed by bundling individual brush bristles 24a. Each bristle bundle 24 is folded in two, and is inserted into each bristle implantation hole 23 with the folded portion 25 at the leading edge. Figures 17(a) and (b) are a front partial cross-sectional view and a right partial cross-sectional view, respectively, showing the state in which the bristle bundle 24 is folded in two by the flat line 26 and inserted into the bristle implantation hole 23.

[0130] Each tuft 24 includes a straight portion 27, which is a generally columnar tuft, continuing from the folded portion 25 on the tufting surface 22a side. Since the tuft 24 is pressed into the tufting hole 23, the straight portion 27 comes into close contact with the tufting hole wall 23a, which is the inner wall of the tufting hole 23.

[0131] The folded portion 25 protrudes from the head portion 22 at the opening on the rear surface 22b side and is exposed. The lower end of the folded portion 25 is located lower than the rear surface 22b, and the upper end of the folded portion 25 coincides with the position of the rear surface 22b in the up-down direction.

[0132] The flat line 26 is driven downward, and the edges 26b, 26b of the two sides form two grooves 22c, 22c, progressing until the lower end 26a of the flat line reaches the back surface 22b of the head portion 22. In other words, the flat line 26 is disposed so that the lower end 26a is inscribed in the imaginary bottom surface Cb of the cylindrical space C of the tufting hole 23 and is in contact with the imaginary bottom surface Cb downward. The length of the two grooves 22c, 22c is equal to the thickness of the head portion 22.

[0133] The lower end of the straight portion 27 coincides with the position of the back surface 22b in the up-down direction. That is, the thickness of the head portion 22 and the height of the straight portion 27 coincide with each other, and the entire tufting hole wall 23a is in close contact with the straight portion 27.

[0134] The other configurations are common to the fourth embodiment.

[0135] In the toothbrush 11 of the present invention, the flat line 26 is disposed at the lowest part of the tufting hole 23, so that the bristle bundle 24 is pressed radially outward at the deepest position of the tufting hole 23. Therefore, the bristle bundle 24 adheres more firmly to the tufting hole wall 23a. This allows the bristle bundle 24 to remain more reliably in the planted position. In addition, the two grooves 22c, 22c are the longest, and the friction between the edges 26b, 26b of the two sides and the respective grooves 22c, 22c is also greater.

[0136] Furthermore, since the lower end 26a of the flat line is configured to be inscribed in the imaginary bottom surface Cb of the tufting hole, the flat line 26 does not protrude downward from the imaginary bottom surface Cb of the tufting hole. Therefore, it is possible to prevent an accident in which the flat line 26 protrudes from the head portion 22 and injures the inside of the mouth M of the user.

[0137] [Manufacturing method] In FIG. 18, S2000 illustrates a method for manufacturing toothbrush 21 according to the fifth embodiment of the present invention.

[0138] The pushing step S2022 of the toothbrush manufacturing method S2000 includes a flat wire bottoming step S2022a, which is a step of inserting the flat wire 26 until each folded portion 25 abuts against the recess bottom 9b, which is the bottom of each recess 9 into which the flat wire 26 is to be inserted. At this time, the flat wire pushing aid 8 shown in Fig. 6 is configured so that the depth of the recess 9 matches the vertical height of each folded portion 25. Therefore, the flat wire 26 stops entering the tufting hole 23 downward when the lower end of each folded portion 25 abuts against the recess bottom 9b.

[0139] In addition, since the flat wire pushing aid 8 is made of a material harder than the flat wire 26, even if an attempt is made to push the flat wire 26 further in, the flat wire lower end 26a will not be embedded in the head receiving surface 8a.

[0140] FIG. 19 shows the state in which the flat wire pushing aid 8 is attached to the head portion 22, the folded portion 25 is fitted inside the recessed portion 9, and the lower end of the folded portion 25 abuts against the bottom portion 9b of the recess.

[0141] The other processes and steps are common to the manufacturing method of the toothbrush in the fourth embodiment.

[0142] In this way, the depth of recess 9 can regulate the length by which folded portion 25 protrudes from the opening on rear surface 22b. This makes it possible to set the protruding length to a length sufficient for wiping off saliva, medicinal liquids, running water, cleaning water, etc. with absorbent material such as cloth, cotton, or paper, while not being too long for work, use, storage, aesthetics, etc. In this way, toothbrush 21 can be manufactured that can remove moisture and be kept clean.

[0143] Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications are possible without departing from the spirit of the present invention.

[0144] For example, the bristles implantation holes do not have to be round holes, and may be elliptical or rectangular holes as long as the bristles can be bound together and implanted in a bundle.

[0145] In addition, the head portion does not have to have multiple tufting holes, and may have a single tufting hole. Accordingly, the tufted hair bundle may also be a single tuft. Furthermore, the flat wire pushing aid may have a single recess.

[0146] When the folded portion protrudes and is exposed from the head portion, the rear side opening edge of the flat wire pushing aid does not have to be the same diameter as the recessed edge, and may be smaller or larger in diameter than the recessed edge, as long as it does not interfere with the folded portion protruding from the head portion.

[0147] The material of the flat wire does not have to be metal, and may be, for example, plastic, as long as it is hard enough to be hammered into the head portion.

[0148] When the folded portion protrudes and is exposed from the head portion, as long as the folded portion does not interfere with the protrusion of the head portion when driving in the flat wire, it is possible to, for example, support the head portion in the air with one hand and support and push in the hair bundle with the other hand without using a flat wire pushing aid.

[0149] When the tuft of bristles is attached to the head portion, a flat wire is not used, and the bristles may be fixed to the head portion by welding, for example.

[0150] The upper end of the flat line does not necessarily have to circumscribe the imaginary upper surface of the narrowing portion, but may be located above the imaginary upper surface of the narrowing portion as long as the flat line can be pushed in deeply enough to prevent the bristle bundle from falling out from the implantation surface.

[0151] The narrowing portion does not have to be biased toward the back side, but may be arranged so that the imaginary bottom surface of the narrowing portion is located above the imaginary bottom surface of the tufting hole, as long as the flat wire can be pushed in deeply enough so that the tuft does not fall out from the tufting surface side. [Industrial Applicability]

[0152] INDUSTRIAL APPLICABILITY The present invention can be utilized in a toothbrush manufacturing method including a toothbrush preparation step of preparing a toothbrush having bristle implantation holes penetrating a head portion and a toothbrush having a head portion provided with penetrating bristle implantation holes. [Explanation of symbols]

[0153] 1,11,21,101,111 Toothbrush 2,12,22,102,112 Head 3,13,23,103,113 Hair transplant hole 103c,113c Reduced diameter part 4,14,24,104,114 Hair bundle 4a,14a,24a,104a,114a brush 5,15,25,105,115 Folded part 6,16,26,106,116 Flat Line 7,17,27,107,117 Straight section 8 Flat wire pushing aid 9. Hollow section C Cylindrical space of implant hole (approximately cylindrical) Cb Virtual bottom of implant hole E. Cylindrical space at reduced diameter Ea Virtual upper surface of reduced diameter part Eb Virtual bottom surface of reduced diameter Manufacturing method for S1000, S1100, S1200, S2000 toothbrushes S1010,S1110,S1210,S2010 Preparation process S1011, S1111, S1211, S2011 Toothbrush preparation process S1012,S1112,S2012 Auxiliary tool preparation process S1020,S1120,S1220,S2020 Planting process S1021, S1121, S2021 Steps for attaching auxiliary equipment S1022, S1122, S1222, S2022 Push-in step S1023, S1123, S2023 Auxiliary equipment removal step

Claims

1. A toothbrush comprising a brush and a head portion in which a bristle bundle formed by bundling a plurality of said bristles is planted, said head portion having a bristle planting surface and having bristle planting holes in said bristle planting surface, said bristle bundle being folded in two, and being planted in said bristle planting holes in said folded state with said folded portion being the leading edge, The bristles are arranged in a bristle-implanting hole, and the bristles are arranged in a bristle-implanting hole. The hair bundle has a folded portion exposed at the rear opening, The folded portion is configured so that the inner side of the folded portion fits within the tufting hole and a part or the whole of the folded portion protrudes from the head portion. A toothbrush characterized by

2. A flat wire is driven into the implantation hole, The hair bundle is folded in two by the flat wire and pushed into the hair implantation hole.

2. The toothbrush of claim 1.

3. The inner space of the tufting hole is formed in a substantially cylindrical shape, The flat line is disposed so that a lower end of the flat line, which is one side on the rear side, is located on the implantation surface side of a virtual bottom surface of the implantation hole, which is a virtual end surface located on the rear side of the approximately cylindrical body.

3. The toothbrush of claim 2.

4. The inner space of the tufting hole is formed in a substantially cylindrical shape, The flat line is disposed so that a lower end of the flat line, which is one side on the rear side, is inscribed in a virtual bottom surface of the tufting hole, which is a virtual end surface located on the rear side of the approximately cylindrical body.

3. The toothbrush of claim 2.

5. The thickness of the head portion is formed in the range of 1.5 mm or more and less than 4.0 mm.

5. The toothbrush according to claim 3 or 4.

6. The implantation hole has a reduced diameter portion whose inner diameter is smaller than the opening diameter in the implantation surface.

2. The toothbrush of claim 1.

7. The reduced diameter portion has a virtual bottom surface, which is a virtual end surface located on the rear side of the inner space of the reduced diameter portion, and a virtual bottom surface of the tufting hole, which is a virtual end surface located on the rear side of the inner space of the tufting hole formed in a substantially cylindrical shape.

7. The toothbrush of claim 6.

8. The flat line driven into the tufting hole is arranged so that the lower end of the flat line, which is one side on the back side, is circumscribed to the virtual upper surface of the reduced diameter portion, which is a virtual end surface located on the tufting surface side of the inner space of the reduced diameter portion.

7. The toothbrush of claim 6.

9. A toothbrush comprising a brush and a head portion in which a bristle bundle formed by bundling a plurality of said bristles is planted, said head portion having a bristle planting surface and having bristle planting holes formed in said bristle planting surface, said bristle bundle being folded in two, and being planted in said bristle planting holes in said folded state with said folded portion being the leading edge, The tufting hole has an inner space formed in a substantially cylindrical shape and penetrates a back surface of the head portion opposite to the tufting surface, The hair bundle has a folded portion exposed at the rear opening, The folded portion is such that the inner side of the folded portion fits within the tufting hole and is inscribed in a virtual bottom surface of the tufting hole, which is a virtual end surface of the substantially cylindrical body located on the rear side. A toothbrush characterized by

10. 13. A method for making the toothbrush of claim 1, comprising the steps of: a preparation step including a toothbrush preparation step of preparing a toothbrush having the head portion; and a planting step of folding the hair bundle in half by applying a flat line to the hair bundle, and inserting the folded hair bundle and the flat line together from one opening of the hair planting hole with the folded part at the front, and pushing the folded part into the other opening of the hair planting hole until the folded part is exposed at the other opening and a part or the whole of the folded part protrudes from the head part. A method for manufacturing a toothbrush.

11. The method includes, before the step of tying, a step of preparing a flat wire pushing aid having a concave recess on a flat surface, The step of embedding the wire includes a step of attaching the flat wire pushing aid to the other opening side of the head portion so that the recessed portion overlaps the other opening. A method for manufacturing a toothbrush according to claim 10.

12. The step of embedding includes a step of inserting the flat wire until the folded portion abuts against the bottom of the recessed portion. A method for manufacturing a toothbrush according to claim 11.

13. 13. A method for making the toothbrush of claim 1, comprising the steps of: a preparation step including a toothbrush preparation step of preparing a toothbrush having the head portion; and a planting step of folding the tuft in half by placing a flat line against the tuft, inserting the tuft in half and the flat line into one opening of the tufting hole with the folded portion at the front, exposing the folded portion at the other opening of the tufting hole, and pushing the folded portion in until it comes into contact with a virtual bottom surface of the tufting hole, which is a virtual back end surface in the inner space of the tufting hole formed in a substantially cylindrical shape. A method for manufacturing a toothbrush.

14. 13. A method for making the toothbrush of claim 1, comprising the steps of: a preparation step including a toothbrush preparation step of preparing a toothbrush having the head portion; a step of folding the bristle bundle in half by placing a flat line against the bristle bundle, inserting the folded bristle bundle and the flat line together from one opening of the bristle implantation hole with the folded part at the front, exposing the folded part at the other opening of the bristle implantation hole, and pushing the folded part inwardly into a virtual bottom surface of the bristle implantation hole, which is a virtual back end surface in the inner space of the bristle implantation hole formed in a substantially cylindrical shape, or until a part or all of the folded part protrudes from the head part, In the toothbrush preparation step, a toothbrush having a reduced diameter portion in which the bristle implantation hole has an inner diameter smaller than the opening diameter of the one of the openings is prepared as the toothbrush, In the step of implanting, the folded portion is pushed so as to abut against the reduced diameter portion. A method for manufacturing a toothbrush.

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