Replacement brushes for electric toothbrushes and electric toothbrushes

Abstract

To provide a replaceable brush for an electric toothbrush whose movements of brush tips of a brush part are big and which has high cleaning performance, and an electric toothbrush.SOLUTION: A replaceable brush which is freely attachable / detachable to / from an electric toothbrush body 2 includes: a shank body 10 housing a drive part 2c inside; a transplant base 21 which is provided on a front surface side of an end side part of the shank body 10 and where a plurality of bristle bundles are transplanted; and a conversion mechanism 40 which converts a reciprocating linear motion transmitted from the drive part 2c into a reciprocating rotational motion in a vertical direction of the transplant base 21. The conversion mechanism 40 is provided with: a shaft 41 which reciprocally linearly moves in the vertical direction by the reciprocating linear motion of the drive part 2c; a conversion support member 42 which is provided on a rear surface 21b of the transplant base 21 and converts the reciprocating linear motion in the vertical direction of the shaft 41 into a reciprocal rotational motion in the vertical direction of the transplant base 21; and a support shaft 43 which is provided on the rear surface 21b of the transplant base 21 and freely rotatably supports the transplant base 21.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a replacement brush for an electric toothbrush and an electric toothbrush. [Background technology]

[0002] One example of a proposed replacement brush for an electric toothbrush is described in Patent Document 1. The replacement brush described in Patent Document 1 includes a brush section including a bristle base on which filaments are planted, and a shaft connected to a drive section provided in the electric toothbrush body, and the brush section moves up and down in a linear reciprocating motion in response to the linear reciprocating motion of the drive section. The drive section of the electric toothbrush body includes, for example, a motor and a conversion mechanism such as a gear or cam that converts the rotational motion of the motor into linear motion, and a connecting rod provided on the cam of the conversion mechanism is connected to the shaft of the replacement brush. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2019-115470 Summary of the Invention [Problem to be solved by the invention]

[0004] In the invention described in Patent Document 1, the reciprocating linear motion of the drive unit of the electric toothbrush body is transmitted to the brush unit via a shaft. To increase the vibration of the brush unit and widen the cleaning range for efficient cleaning, the reciprocating linear motion of the drive unit must be increased. However, to increase the reciprocating linear motion of the drive unit, the size of the conversion mechanism must be increased, which increases the size of the electric toothbrush body that houses the conversion mechanism, making it difficult to grip and otherwise reducing usability. For this reason, the linear motion of the drive unit cannot be increased beyond a certain size, which poses a problem: the cleaning range cannot be widened and cleaning performance cannot be improved.

[0005] The present invention has been made in light of the above-mentioned problems, and aims to provide a replacement brush for an electric toothbrush and an electric toothbrush that have large bristles that move easily and are easy to clean. [Means for solving the problem]

[0006] The replacement brush for an electric toothbrush according to the present invention, which can be freely attached and detached to the electric toothbrush body, comprises a handle body connected to the electric toothbrush body which has a drive unit housed inside, a bristle base which is provided on the front side of the tip end portion of the handle body and has multiple bristle bundles attached, and a conversion mechanism which converts the reciprocating linear motion transmitted from the drive unit into vertical reciprocating rotational motion of the bristle base, the conversion mechanism comprising: a shaft which moves vertically in a linear manner in response to the reciprocating linear motion of the drive unit; a conversion support member which is provided on the rear surface of the bristle base and converts the vertical reciprocating linear motion of the shaft into vertical reciprocating rotational motion of the bristle base; and a support shaft which is provided on the rear surface of the bristle base and which supports the bristle base so that it can rotate freely.

[0007] The linear reciprocating motion transmitted from the drive unit of the electric toothbrush body is converted by the conversion mechanism into vertical rotational reciprocating motion of the bristle base. The linear reciprocating motion of the drive unit causes the shaft to move vertically, and the vertical reciprocating linear motion of the shaft is transmitted to the bristle base by the conversion support member, causing the bristle base to rotate vertically around the support shaft.

[0008] When the bristle base moves linearly up and down, as in the conventional technology, the distance traveled by the tips of the bristle bundles in the vertical direction corresponds to the distance traveled by the linear up and down movement of the drive unit of the electric toothbrush body. However, in the present invention, the linear up and down movement of the drive unit of the electric toothbrush body is transmitted as a linear up and down movement of the shaft, and the linear up and down movement of the shaft is converted into a reciprocating rotational movement of the bristle base, so the distance traveled by the tips of the bristle bundles in the vertical direction is greater than when the bristle base moves linearly as in the conventional technology. As a result, even if the distance traveled by the linear up and down movement of the drive unit of the electric toothbrush body and the linear up and down movement of the shaft are small, the bristle base can be moved a long way, improving cleaning performance.

[0009] In a preferred embodiment, the hair dryer further comprises a deformable connecting member connecting the tufting base and the handle body.

[0010] It is preferable that the joining member has an annular shape and the tufting base is provided in a hollow portion.

[0011] It is preferable that a groove be formed in the front surface of the joining member at a position corresponding to the support shaft and extending in the direction in which the support shaft extends.

[0012] It is preferable that the joining member has a U-shaped or V-shaped cross section along a plane perpendicular to the circumferential direction that opens to the rear, and has at least inner and outer sides.

[0013] The inner side preferably has a curved portion that is convex toward the outside or the inside.

[0014] The inner side may have a straight portion extending diagonally outward from the front surface of the tufting base.

[0015] In a preferred embodiment, an elastic body is further provided on the rear side of the support shaft to bias the support shaft forward.

[0016] The object of the present invention can also be achieved by an electric toothbrush comprising any of the above-mentioned replacement brushes for an electric toothbrush and an electric toothbrush body having the drive unit therein for rotating the bristle base back and forth. [Effects of the Invention]

[0017] According to the present invention, it is possible to provide a replacement brush for an electric toothbrush and an electric toothbrush in which the vibration of the bristle base is less likely to be transmitted to the handle body, and the bristles of the brush part have large movement and are highly cleanable. [Brief explanation of the drawings]

[0018] [Figure 1]1 is a perspective view showing a replacement brush for an electric toothbrush and an electric toothbrush according to an embodiment of the present invention. [Figure 2] FIG. 2 is a front view of a replacement brush for an electric toothbrush. [Figure 3] 3 is a cross-sectional view of the replacement brush taken along line AA in FIG. 2. [Figure 4] 1A is an enlarged cross-sectional view of the upper part of the replacement brush, and FIG. 1B is an enlarged view of the main part of FIG. [Figure 5] FIG. 2 is an enlarged perspective view of the upper part of the replacement brush. [Figure 6] FIG. [Figure 7] FIG. 10 is a perspective view of a cover member to which an elastic body is attached. [Figure 8] 3 is a cross-sectional view of the replacement brush taken along line BB in FIG. 2. [Figure 9] 1A and 1B are cross-sectional views of the main part illustrating the reciprocating rotational motion of the tufting table, in which (A) shows the state when rotated downward, and (B) shows the state when rotated upward. [Figure 10] 1A is a cross-sectional view of a main part for explaining the reciprocating rotational movement of the tufting table, and FIG. 1B is an enlarged view of a main part of FIG. [Figure 11] 10(A) and 10(B) are cross-sectional views showing other examples of the joining member. [Figure 12] FIG. 10 is an explanatory diagram of the movement distance of a hair bundle in the prior art. DETAILED DESCRIPTION OF THE INVENTION

[0019] An embodiment of the present invention will be described with reference to the drawings. In this embodiment, the up-down direction and the front-rear and left-right directions will be defined based on the electric toothbrush 1 being positioned in a vertical orientation, with the brush head 20 side defined as the upper or tip side, the electric toothbrush body 2 side defined as the lower or base side, and the bristle-implanted side of the brush head 22 defined as the front side. The reciprocating rotational movement of the bristle implantation base 21 in the up-down direction refers to the repeated rotational movement of the bristle implantation base 21 in a direction in which the front surface 21a of the bristle implantation base 21 faces downward and upward, with the support shaft 43 extending in the left-right direction as the fulcrum.

[0020] 1 shows an electric toothbrush 1 of this embodiment. The electric toothbrush 1 includes an electric toothbrush main body 2 and a replacement brush for the electric toothbrush 3 (hereinafter also referred to as the "replacement brush 3") that can be freely attached and detached to the electric toothbrush main body 2.

[0021] (2 electric toothbrushes) As shown in Figures 1 and 2, the electric toothbrush body 2 includes a main body case 2a that houses a drive unit 2c, a power supply unit, and other components. The main body case 2a is a cylindrical member made of synthetic resin, metal, or the like, and has a shape that can be held by hand. A connecting recess 2b is formed at the upper end of the main body case 2a for connecting to a replacement brush 3. The drive unit 2c includes a drive source such as a motor and a drive converter connected to the drive source's output shaft. The drive converter converts the motor's rotational motion into linear motion, such as a known crank mechanism using a cam, link, or the like, but is not limited to this and may also be a rack and pinion mechanism. The drive unit 2c may have any configuration as long as it can linearly move the output shaft up and down. For example, a linear actuator having a coil and a permanent magnet may be used. The power supply supplies power to the drive source and may be an existing battery or the like. A switch 2d is provided on the front of the main body case 2a. When the user presses the switch 2d, the drive unit 2c moves linearly back and forth, driving the electric toothbrush 1. The electric toothbrush body 2 may have any known configuration as long as it can be connected to the replacement brush 3 and can impart a reciprocating linear motion to the replacement brush 3.

[0022] (3 replacement brushes) As shown in Figures 1 to 10, the replacement brush 3 comprises a handle 10 connected to the electric toothbrush main body 2, a brush head 20 provided on the front side of the tip portion of the handle 10 and comprising a bristle base 21 and a brush section 22, a connecting member 30 connecting the bristle base 21 of the brush head 20 to the handle 10, a conversion mechanism 40 that converts the motion transmitted from the drive section 2c of the electric toothbrush main body 2 into a reciprocating rotational motion in the up and down direction of the bristle base 21, and an elastic body 50.

[0023] (Handle 10) As shown in FIGS. 3 and 5, the handle 10 comprises a hollow upper portion 10A with a circular front surface and a cylindrical lower portion 10B that is continuous with the upper portion 10A and expands in diameter downward. A connecting tube 10a is formed at the lower end of the lower portion 10B of the handle 10 for connecting the replacement brush 3 to the electric toothbrush body 2. A first opening 11 is formed on the front side of the upper portion 10A, into which the brush head 20 and connecting member 30 are attached. The rear side of the handle 10, extending from the upper portion 10A to the upper side of the lower portion 10B, is formed by a removable cover member 12. When the cover member 12 is removed, a second opening 13 is revealed through which the bristle base 21, connecting member 30, and conversion mechanism 40 can be attached. As shown in FIGS. 7 and 8, a protrusion 12a is formed on the inner surface of the cover member 12 for engaging the elastic body 50. As shown in FIGS. 1 and 3, third openings 14, 14 are formed on the front and rear surfaces of the handle body 10 for visually checking the movement of a shaft 41, which will be described later.

[0024] As shown in Fig. 6, a shaft 41 (described later) is housed inside the handle 10 so as to be slightly movable in the front-rear direction, and a plurality of ribs 10b are formed on the inner peripheral surface of the handle 10 to guide the shaft 41 so as to be freely movable up and down. A pair of shaft support portions 15A, 15B for engaging both ends of a shaft 43 (described later) with a support member are provided near the upper left and right edges of the second opening 13, at a height position at the center in the up-down direction of the tufting base 21 (described later). As shown in Figs. 6 and 8, one support portion 15A for the shaft 43 is provided with an insertion hole 15a, and the other support portion 15B for the shaft 43 is formed with a groove 15b opening to the rear side. One end of the shaft 43 is inserted into the insertion hole 15a, and the other end of the shaft is slid in the groove 15b, thereby fitting and supporting the shaft 43 between the pair of shaft support portions 15A, 15B. The rear opening of the groove 15b is covered by the cover member 12, so that the support shaft 43 does not fall out of the groove 15b. The material constituting the handle body 10 is a synthetic resin, and the same material as that of the tufting base 21 described later can be used.

[0025] (20 brush heads) As shown in Figures 3, 5, etc., the bristle base 21 of the brush head 20 has a generally circular plate-like shape when viewed from the front, and in this embodiment, it has a diameter of approximately 11 cm and a thickness of 2.5 cm. When the electric toothbrush 1 is stopped, as shown in Figures 3, 4(A), and 4(B), the front surface 21a of the bristle base 21 is parallel to the planes along the vertical and horizontal directions, and the brush head 22 is in a third position P3 (also referred to as the "origin position P3") extending in the front-to-back direction. The brush head 22 is composed of one or more bristle bundles 22a formed by bundling multiple synthetic resin filaments, and each bristle bundle 22a is implanted in a bristle implantation hole 23 formed in the front surface 21a of the bristle base 21. The brush head 20 may have a known configuration. Note that the brush head 22 is not shown in Figure 5.

[0026] The shape of the bristle implantation base 21 as viewed from the front is not limited to a circle, but can be any shape that allows for reciprocating rotation, such as a substantially circular, elliptical, rectangular, square, triangular, pentagonal, hexagonal, or star-shaped shape. The front surface 21a of the bristle implantation base 21 can have not only a flat surface, but also various three-dimensional structures such as a convexly curved surface, an inclined surface, or a surface with a step in the front-to-rear direction. The arrangement of the implantation holes 23 for the bristle bundles 22a in the bristle implantation base 21 is not particularly limited and can be freely set regardless of the shape of the bristle implantation base 21. Furthermore, filaments may be mixed with structures other than filaments, such as pointed cones or thin cylinders, and arranged on the bristle implantation base 21.

[0027] The means for implanting the bristle bundles 22a on the bristle implantation base 21 can be a method of fixing the bristle bundles 22a to the bristle implantation base 21 using a small flat piece of metal called a "flat wire," or a method of integrating one end of the bristle bundles 22a made of synthetic resin by melting or gluing, and then embedding and fixing it in the bristle implantation base 21 with resin by melting, gluing, or injection molding. However, the method is not limited to these, and any ordinary method can be used.

[0028] The filaments of the bristle bundle 22a can be made of synthetic resins, silicones, or elastomers. Examples include polyamide resins such as nylon 610, nylon 612, and aramid; polyester resins such as polybutylene terephthalate (PBT), polypropylene terephthalate (polytrimethylene terephthalate, PPT, or PTT), and polyethylene terephthalate (PET); polyolefin resins such as polypropylene (PP) and polyethylene (PE); and thermoplastic elastomers (TPEs) such as polystyrene-based (SBC), polyolefin-based (TPO), polyvinyl chloride-based (TPVC), polyurethane-based (PU), polyester-based (TPEE), and polyamide-based (TPAE). These materials can be used alone or in combination with a mixture of two or more materials processed into filaments, or as composite filaments made by structurally combining and joining components made of multiple materials.

[0029] The material constituting the tufting base 21 is a synthetic resin, and examples of the types of synthetic resin that can be used include polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polytrimethyl terephthalate (PTT), polycarbonate (PC), polyoxymethylene (polyacetal resin (POM)), styrene-acrylonitrile resin (AS), acrylonitrile-butadiene-styrene resin (ABS), and cellulose. Examples of suitable materials include cellulose propionate (CP), polyamide (PA), polymethyl methacrylate (PMMA), polyarylate (PAR), and polylactic acid (PLA). Among these, polypropylene (PP), polyethylene terephthalate (PET), polyoxymethylene (polyacetal resin (POM)), acrylonitrile-butadiene-styrene resin (ABS), and polylactic acid (PLA) are preferred, and from the viewpoint of durability, polypropylene (PP) and polyoxymethylene (polyacetal resin (POM)) are more preferred. For the tufting base 21, polyoxymethylene (polyacetal resin (POM)) is most preferred.

[0030] (Joint member 30) The connecting member 30 is made of a deformable material and connects the handle 10 and the brush head 20 to prevent vibrations from the bristle base 21 of the brush head 20 from being transmitted to the handle 10. As shown in FIGS. 4(A), 4(B), and 5, the connecting member 30 is an approximately circular ring-shaped member, with the bristle base 21 provided in a hollow portion 30a. The cross-sectional shape of the connecting member 30 along a plane perpendicular to the circumferential direction is a modified U-shape, convex toward the front and open toward the rear. Specifically, as shown in FIG. 4(B), the connecting member 30 includes an inner portion 31, which is the side located on the inside of the cross-sectional shape, an outer portion 32, which is the side located on the outside, and a connecting portion 33, which is the side connecting the front end of the inner portion 31 and the front end of the outer portion 32. The inner portion refers to the side facing the center point of the annular connecting member 30, and the outer portion refers to the side opposite the inner portion. The outer portion 32 extends linearly in the front-to-rear direction and is joined to the entire peripheral edge of the first opening 11 of the handle body 10 by any adhesive or other adhesive means. The connecting portion 33 extends linearly in the up-down direction. The inner portion 31 includes a curved portion 31a that is convex outward and a straight portion 31b that is continuous with the rear end of the curved portion 31a and extends linearly in the front-to-rear direction. The curved portion 31a is arc-shaped with a curvature radius r, which is set to be greater than or equal to 1 and less than or equal to 2, and is set to 2 in this embodiment. The front end of the straight portion 31b, i.e., the rear end of the curved portion 31a, is aligned with the front surface 21a of the tufting base 21 in the front-to-rear direction. The straight portion 31b is joined to the outer peripheral surface of the tufting base 21 by any adhesive or other adhesive means. Note that the cross-sectional shape is not limited to that of the above embodiment; it may be a substantially V-shape in which the front ends of the inner portion 31 and the outer portion 32 are connected to each other without the connecting portion 33.

[0031] As shown in FIG. 5 , a groove 34 is formed on the front surface of the joining member 30. The groove 34 is a recessed portion provided on the front side of the joining member 30, and two grooves 34 are provided on the left and right sides at positions corresponding to the support shafts 43 (described later). The left and right sides of the groove 34 are open, and the bottom of the groove 34 is aligned with the handle 10 or slightly forward of the handle 10. In this embodiment, the width (vertical length) of the groove 34 is constant, but the width may narrow toward the outside. When the bristle implantation base 21 rotates downward, a radially outward force acts on the portion of the joining member 30 above the groove 34, and a radially inward force acts on the portion of the joining member 30 below the groove 34. Furthermore, when the bristle implantation base 21 rotates upward, an inward force acts on the upper portion of the joining member 30, and an outward force acts on the lower portion. Therefore, twisting occurs in the joint member 30 when the tufting base 21 rotates, but by providing the grooves 34, the twisting can be reduced.

[0032] The material constituting the joining member 30 is not particularly limited as long as it can be deformed by the motion transmitted from the drive unit 2c of the electric toothbrush body 2, and examples thereof include metals, synthetic resins, elastomers, and silicones that can form elastic bodies or easily deformable bodies. Among these, elastomers and silicones are preferred because they are excellent in terms of manufacturing cost and energy efficiency, and elastomers and silicones with a Shore A hardness of 30 to 55, preferably 40 to 55, and more preferably 40 to 50 are most preferred from the viewpoints of reducing power consumption and utilizing the energy generated by the deformation and recovery of the joining member 30 as kinetic energy for the bristle base 21.

[0033] The cross-sectional shape of the joining member 30 is not limited to a modified U-shape or V-shape, and may be any shape that allows the structure of the joining member 30 to be deformed by the driving force of the electric toothbrush 1. Examples of the structure of the joining member 30 include a thread-like structure that is stretchable in a linear direction, a thin film or thin plate-like structure that is stretchable in a planar direction or deformable in the up-down direction, a coil-like structure, a structure with a deformable W-shape, zigzag-like or wave-like cross-sectional shape, and a structure with a sponge-like internal structure that can be compressed and deformed.

[0034] Furthermore, the brush head 20 is inserted into the mouth during use, and if moisture, toothpaste, etc., gets into the handle 10, it becomes difficult to adequately clean and dry, which not only causes inconvenience from a hygienic standpoint but also may reduce the durability and movement function of the replacement brush 3. Therefore, it is preferable that the first opening 11 of the handle 10 and the bristle base 21 are joined watertight by the joining member 30 so that water, etc., cannot get into the handle 10 from the joining portion between the joining member 30 and the handle 10 or the joining portion between the joining member 30 and the bristle base 21.

[0035] (Conversion mechanism 40) As shown in Figures 3 and 6, the conversion mechanism 40 comprises a shaft 41 that moves back and forth in a linear manner in the vertical direction in conjunction with the movement of the drive unit 2c of the electric toothbrush body 2, a conversion support member 42 that converts the vertical reciprocating linear movement of the shaft 41 into vertical reciprocating rotational movement of the bristle planting base 21, and a support shaft 43 that is provided on the rear surface 21b of the bristle planting base 21 and supports the bristle planting base 21 so that it can rotate back and forth freely.

[0036] (Shaft 41) The shaft 41 is a rod-shaped member extending from the lower end of the handle body 10 to the upper end thereof, and is guided by a protrusion 10b formed inside the handle body 10, allowing it to move up and down. The shaft 41 includes a fitting tubular portion 41a formed at the lower end thereof for detachably fitting an output shaft of the drive unit 2c of the electric toothbrush body 2, a shaft main portion 41b extending upward from the fitting tubular portion 41a, a diagonal portion 41c extending diagonally rearward from the shaft main portion 41b, and a pair of arms 41d, 41d bifurcating upward from the diagonal portion 41c. The pair of arms 41d, 41d are aligned in the left-right direction, and a guide rod 41e is attached to the ends of the pair of arms 41d, 41d, connecting the arms 41d, 41d. The guide rod 41e is a rod-shaped member with a circular cross section. The shaft 41 is made of metal or synthetic resin. In the case of synthetic resin, the same material as that of the tufting base 21 can be used, and polyoxymethylene (polyacetal resin (POM)) is most preferable. In this embodiment, the shaft 41 moves upward and downward by a distance of 1.0 mm each from the state in which the tufting base 21 is in the third position (origin position) P3 as shown in Figure 3, that is, the movement distance L10 (Figure 10(B)) along the vertical direction of the shaft 41 is set to 2.0 mm, but the movement distance L10 is not limited to this.

[0037] (Conversion support member 42) The conversion support member 42 is located below the vertical center of the rear surface 21b of the tufting base 21. As shown in Figures 4(B) and 6, the conversion support member 42 has a guide portion 42a consisting of a long hole or groove that is long in the front-to-rear direction and into which the guide rod 41e of the shaft 41 is freely fitted. In this embodiment, the conversion support member 42 is a U-shaped member that opens to the rear in a side view, and has a pair of upper and lower arms 42b, 42b that protrude rearward from the rear surface 21b of the tufting base 21, and a groove that serves as the guide portion 42a is formed between the pair of arms 42b, 42b. The guide rod 41e is inserted into the guide portion 42a through the opening of the conversion support member 42 and is movable within the guide portion 42a. The conversion support member 42 is made of a synthetic resin, and the same material as the tufting base 21 can be used.

[0038] (Spindle 43) The support shaft 43 is a rod-shaped member with a circular cross section that extends in the left-right direction along the rear surface 21b of the tufting table 21. As shown in FIGS. 6 and 8, both ends of the support shaft 43 are fixed to a pair of support shafts 15A and 15B formed on the handle body 10. As shown in FIGS. 4(A), 6, and 8, the support shaft 43 is engaged with a support shaft support member 44 provided at the center of the rear surface 21b of the tufting table 21 in the up-down and left-right directions. The support shaft support member 44 is a rectangular parallelepiped member and has a groove 44a that is open on the rear and left and right sides and corresponds to the diameter of the support shaft 43. The support shaft 43 is supported in the groove 44a so that the tufting table 21 can rotate relative to the support shaft 43. The support shaft 43 is made of a metal, and although stainless steel is used in this embodiment, the material is not limited to this.

[0039] The conversion support member 42 and the spindle support member 44 may be provided separately from the tufting base 21 and fixed to the rear surface 21b of the tufting base 21, or the tufting base 21, the conversion support member 42, and the spindle support member 44 may be formed as a single unit by injection molding or the like.

[0040] (elastic body 50) The elastic body 50 is disposed between the cover member 12 and the support shaft 43 and biases the support shaft 43 forward. This biasing force is applied to the support shaft 43, preventing the support shaft 43 from bending or breaking due to force applied to the support shaft 43 via the bristle base 21 when the electric toothbrush 1 is in use. As shown in FIGS. 6 to 8 , the elastic body 50 is made of a leaf spring and includes a rectangular plate-shaped main body 51 and a pair of legs 52, 52 folded back from both left and right ends of the upper edge of the main body 51 and extending parallel to the main body 51. A locking hole 51a is formed in the center of the main body 51 to be engaged with a protrusion 12a on the inner surface of the cover member 12, and the elastic body 50 is attached to the cover member 12 by locking the protrusion 12a into the locking hole 51a. By assembling the cover member 12 to the second opening 13 of the handle body 10, the outer surfaces of the pair of legs 52, 52 of the elastic body 50 come into contact with the support shaft 43, applying a biasing force to the support shaft 43. The pair of legs 52, 52 come into contact with the support shaft 43 at positions symmetrical on either side of the support shaft support member 44. The material constituting the elastic body 50 is metal, and in this embodiment, a stainless steel leaf spring is used, but the material is not limited to this.

[0041] (operation) The operation of the electric toothbrush 1 and the replacement brush 3 for the electric toothbrush of this embodiment will be described. When the electric toothbrush 1 is stopped, the bristle base 21 is in the third position P3, as shown in FIGS. 3 and 4A. When the user presses the switch 2d of the electric toothbrush 1 and the electric toothbrush 1 starts operating, the vertical reciprocating linear motion of the drive unit 2c of the electric toothbrush body 2 is transmitted to the shaft 41. As shown in FIGS. 9A and 10B, when the shaft 41 moves upward (arrow Y1), the guide rod 41e of the shaft 41 moves rearward along the circumference of the imaginary circle C (counterclockwise around the circumference of the imaginary circle C in FIG. 9A), and moves relatively within the guide portion 42a of the conversion support member 42 toward the opening of the guide portion 42a. As a result, the bristle base 21 rotates around the support shaft 43 in a direction in which the front surface 21a faces downward (arrow Y2) until it reaches the first position P1. The imaginary circle C is an imaginary circle whose center is the center point of the cross-sectional shape of the support shaft 43 and whose radius is set to the distance between the center point of the cross-sectional shape of the support shaft 43 and the center point of the cross-sectional shape of the guide rod 41e when the tufting base 21 is at the third position P3 as shown in Figure 3. In Figure 10(B), the guide rod 41e' is shown when the tufting base 21 is at the third position P3, and when the tufting base 21 has rotated to the first position P1, the guide rod 41e has moved in a counterclockwise direction more than the guide rod 41e'.

[0042] Next, as shown in FIGS. 9(B) and 10(B), when the shaft 41 moves downward (arrow Y3), the guide rod 41e of the shaft 41 moves along the circumference of the imaginary circle C toward the front side in the front-to-rear direction (clockwise around the circumference of the imaginary circle C in FIG. 9(B)), and moves relatively within the guide portion 42a of the conversion support member 42 toward the opposite side of the opening of the guide portion 42a. As a result, the bristle implantation base 21 rotates around the support shaft 43 in a direction in which the front surface 21a faces upward (arrow Y4) to the second position P2. In FIG. 10(B), the guide rod 41e'' is indicated when the bristle implantation base 21 is in the second position P2. In this embodiment, the guide rod 41e'' is aligned with the support shaft 43 in the vertical direction. In this manner, the bristle implantation base 21 repeatedly rotates between the first position P1 and the second position P2, and the brush head 20 including the bristle implantation base 21 rotates back and forth in the vertical direction. In this embodiment, the rotation center angle α of the bristle implantation base 21 about the support shaft 43 between the first position P1 and the second position P2 is set to 38 degrees, but is not limited to this. For the sake of explanation, Fig. 10(B) shows the bristle implantation base 21, the brush part 22, the conversion support member 42, the guide rod 41e of the shaft 41, and the support shaft 43, and does not show the other components.

[0043] (Cleaning area) The cleaning range of the brush part 22 due to the rotational movement of the bristle base 21 is the range in which the brush part 22 is located when the bristle base 21 rotates, when viewed in cross section of the replacement brush 3. As shown in Figure 10(A), the distance L1 in the vertical direction between the lower end of the front end of the brush part 22 when the bristle base 21 is in the first position P1 and the upper end of the front end of the brush part 22 when the bristle base 21 is in the second position P2 is used as an indicator of the width of the cleaning range.

[0044] In this embodiment, as shown in Figures 4, 10(A), and 10(B), the vertical length L3 of the bristle base 21 (diameter of the bristle base 21) is set to 11.0 mm, the length L4 of the brush portion 22 from the surface 21a of the bristle base 21 to the tip is set to 10.0 mm, the vertical movement distance L10 of the shaft 41 is set to 2.0 mm, the diameter L6 of the support shaft 43 is set to 1.0 mm, the width L7 of the upper arm portion 42b forming the guide portion 42a of the conversion support member 42 is set to 1.0 mm, the width L8 of the lower arm portion 42b is set to 1.2 mm, and the diameter L9 of the guide rod 41e of the shaft 41 is set to 1.0 mm.

[0045] The vertical length L5 between the center point of the cross-sectional shape of the support shaft 43 and the center point of the cross-sectional shape of the guide rod 41e of the shaft 41 is determined according to the vertical length L3 of the tufting base 21, the diameter L6 of the support shaft 43, the width L7 of the upper arm portion 42b of the guide portion 42a, the width L8 of the lower arm portion 42b, and the diameter L9 of the guide rod 41e of the shaft 41. The minimum distance of the vertical length L5 between the support shaft 43 and the guide rod 41e is determined by the diameter L6 / 2 of the support shaft 43 + the width L7 of the upper arm portion 42b + the diameter L9 / 2 of the guide rod 41e, which is 1.0 mm / 2 + 1.0 mm + 1.0 mm / 2 = 2.0 mm in this embodiment. In addition, the maximum distance L5 in the vertical direction between the support shaft 43 and the guide rod 41e is determined by the vertical length L3 / 2 of the tufting base 21 - the width L8 of the lower arm portion 42b - the diameter L9 / 2 of the guide rod 41e, which in this embodiment is 11.0 mm / 2 - 1.2 mm - 1.0 mm / 2 = 3.8 mm.

[0046] When the vertical length L5 between the support shaft 43 and the guide rod 41e is set to the maximum distance, the cleaning range L1 is 15.6 mm. When the length L5 is set to the minimum distance, the cleaning range L1 is 19.0 mm. Thus, the cleaning range L1 can be determined by adjusting the vertical length L5 between the support shaft 43 and the guide rod 41e. Shortening the vertical length L5 between the support shaft 43 and the guide rod 41e widens the cleaning range L1, but increases the distance the guide rod 41e moves around the circumference of the imaginary circle C, resulting in greater movement in the front-to-back direction. This requires increasing the front-to-back length (thickness) of the handle 10, resulting in a poor user experience when inserted into the oral cavity. Increasing the vertical length L5 between the support shaft 43 and the guide rod 41e narrows the cleaning range L1, but shortens the distance the guide rod 41e moves around the circumference of the imaginary circle C. This allows for a smaller front-to-back length (thickness) of the handle 10, resulting in a good user experience. In this way, the vertical length L5 between the support shaft 43 and the guide rod 41e is set taking into consideration the cleaning range L1 and the front-to-back length (thickness) of the handle body 10, and in this embodiment is set to 3.8 mm.

[0047] FIG. 12 illustrates a conventional technique. In the conventional technique, the vertical reciprocating linear motion of the drive unit of the electric toothbrush body is transmitted to the shaft 141. When the shaft 141 moves upward, the bristle base 121 connected to the shaft 141 moves upward to the position indicated by the two-dot chain line in FIG. 12. When the shaft 141 moves downward, the bristle base 21 moves downward to the position indicated by the solid line. In this manner, the brush head 120 including the bristle base 121 performs vertical reciprocating linear motion. The movement distance of the shaft 141 is the same as the movement distance of the bristle base 121. The distance L2 between the lower end of the front end of the brush head 122 when the bristle base 121 is in the upper position and the upper end of the front end of the brush head 122 when the bristle base 121 is in the lower position is used as an index of the size of the cleaning area.

[0048] When the travel distance of shaft 141 in Fig. 12 is set to be the same as travel distance L10 of shaft 41 in this embodiment, and the length from surface 121a of bristle base 121 to the tip of brush unit 122 in Fig. 12 is set to be the same as length L4 from surface 21a of bristle base 21 to the tip of brush unit 22 in this embodiment, distance L2 indicating the cleaning range is 10.0 mm in the prior art in Fig. 12. In this way, distance L1 indicating the cleaning range in this embodiment is greater than distance L2 indicating the cleaning range, and the cleaning range in this embodiment is wider than that of the prior art.

[0049] With the above configuration, the vertical reciprocating linear motion of the drive unit 2c of the electric toothbrush body 2 is converted into reciprocating rotational motion of the bristle base 21, and the vertical movement distance of the tips of the bristle bundles is greater than with the reciprocating linear motion of the bristle base 21 in conventional technology. Therefore, even if the linear movement distance of the reciprocating linear motion of the drive unit 2c of the electric toothbrush body 2 is small, the bristle base 21 can be moved a long distance, improving cleaning performance. In addition, the bristle base 21 and the handle 10 are joined by the joining member 30, which absorbs vibrations of the bristle base 21, so vibrations of the bristle base 21 are less likely to be transmitted to the handle 10.

[0050] Furthermore, in this embodiment, the entire outer periphery of the bristle base 21 can be joined to the joining member 30, and the entire outer periphery of the joining member 30 can be joined to the handle 10, so that the bristle base 21 is firmly joined to the handle 10 via the joining member 30, and the bristle base 21 will not come off the handle 10 even if pressure is applied to the bristle base 21 when using the electric toothbrush 1. Furthermore, by disposing the joining member 30 between the handle 10 and the bristle base 21, it is possible to prevent moisture such as water from entering the handle 10.

[0051] Furthermore, the bristle implantation base 21 rotates vertically around the support shaft 43, but since the bristle implantation base 21 is joined to the joining member 30, by providing a groove 34 at a location corresponding to the support shaft 43 of the joining member 30, the location corresponding to the support shaft 43 of the joining member 30 does not become tense when the bristle implantation base 21 rotates vertically, and the joining member 30 does not interfere with the rotational movement of the bristle implantation base 21.

[0052] By making the cross-sectional shape of the joining member 30 a U-shape or V-shape with an opening, the joining member 30 is easily bent when the tufting base 21 rotates back and forth, and the joining member 30 does not interfere with the rotational movement of the tufting base 21.

[0053] Furthermore, when the electric toothbrush 1 is in use, if a reaction force generated by the force pressing the bristle bundle against the surface of the teeth is applied to the support shaft 43 via the bristle implantation base 21, the support shaft 43 may bend or break; however, by biasing the support shaft 43 forward with the elastic body 50, bending or breakage of the support shaft 43 can be prevented.

[0054] FIG. 11 shows another example of the joining member 30. In the examples shown in FIGS. 11(A) and 11(B), the shape of the inner portion 31 of the U-shaped cross section of the joining member 30 differs from that of the joining member 30 of the embodiment shown in FIGS. 1 to 10. In the example shown in FIG. 11(A), the inner portion 31 of the U-shaped cross section of the joining member 30 includes a first linear portion 31c extending linearly in the front-to-rear direction from the end of the connecting portion 33, a second linear portion 31d extending obliquely from the rear end of the first linear portion 31c, and a linear portion 31b extending linearly in the front-to-rear direction from the rear end of the second linear portion 31d. When the electric toothbrush 1 is stopped, the second linear portion 31d extends outward at an angle β with respect to a plane (a plane along the vertical and horizontal directions) including the front surface 21a of the bristle base 21. The angle β is set to be equal to or greater than 60 degrees and equal to or less than 80 degrees, and is set to 60 degrees in this embodiment. Since the other configurations of the joining member 30 are the same as those in the embodiment of Fig. 1, the same reference numerals are used for corresponding parts and the description thereof will be omitted.

[0055] 11(B), the inner portion 31 includes a curved portion 31f that is convex toward the inside and a straight portion 31b that is continuous with the rear end of the curved portion 31f and extends linearly in the front-to-rear direction. The curved portion 31f has an arc with a curvature radius r, which is set to be greater than or equal to 1 and less than or equal to 2, and is set to 2 in this embodiment. The other configurations of the joining member 30 are the same as those in the embodiment of FIG. 1, and therefore corresponding parts are denoted by the same reference numerals and description thereof will be omitted.

[0056] 11(A) and 11(B), the joint members 30 are easily bent when the tufting base 21 rotates back and forth, and the joint members 30 do not interfere with the rotation of the tufting base 21.

[0057] Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the spirit of the present invention. [Explanation of symbols]

[0058] 2 Electric toothbrush body 2c Drive unit 3 Replacement brushes for electric toothbrushes 10 handle 21 Hair transplantation base 21b Rear 30 Joint material 31a Curved section 31b Straight section 30a Hollow part 34 Groove 40 Conversion Mechanism 41 Shaft 42 Conversion support member 43 Spindle 50 Elastic Body

Claims

1. a handle body connected to an electric toothbrush body having a drive unit housed therein; a bristle implantation base provided on the front side of the tip end portion of the handle body and having a plurality of bristle bundles implanted therein; a conversion mechanism that converts the reciprocating linear motion transmitted from the drive unit into a reciprocating rotational motion in the up and down direction of the tufting table, The conversion mechanism is a shaft that moves linearly back and forth in the vertical direction due to the linear movement of the drive unit; a conversion support member provided on the rear surface of the tufting table, which converts the vertical reciprocating linear motion of the shaft into the vertical reciprocating rotational motion of the tufting table; a support shaft provided on the rear surface of the tufting base for rotatably supporting the tufting base; a deformable joining member that connects the tufting base and the handle body, The joining member is annular, and the tufting base is provided in a hollow portion thereof. The replacement brush for the electric toothbrush is detachable from the electric toothbrush body, and a groove is formed in the front surface of the joining member at a position corresponding to the support shaft along the direction in which the support shaft extends.

2. 2. The replacement brush for an electric toothbrush according to claim 1, wherein the cross-sectional shape of the joining member along a plane perpendicular to the circumferential direction is U-shaped or V-shaped with an opening toward the rear, and the joining member has at least inner and outer sides.

3. The replacement brush for an electric toothbrush according to claim 2 , wherein the inner side has a curved portion that is convex outward or inward.

4. The replacement brush for an electric toothbrush according to claim 2 , wherein the inner side has a straight portion extending diagonally outward from the front surface of the bristle base.

5. The replacement brush for an electric toothbrush according to claim 1 , further comprising an elastic body provided on the rear side of the support shaft for biasing the support shaft forward.

6. A replacement brush for an electric toothbrush according to any one of claims 1 to 5; and an electric toothbrush body having the drive unit therein for rotating the bristle base back and forth.

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