JP2003210495A - Electric toothbrush - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric toothbrush equipped with an output shaft having wear resistance and rust-proof function without plating the surface in the electric toothbrush in which a movable part comprising the output shaft provided with a plunger is driven to reciprocate. <P>SOLUTION: This electric toothbrush is mainly composed of a movable part 1, and a fixed part 2 for supporting the movable part 1 in an axially reciprocating manner and driving it to reciprocate. The fixed part 2 is composed of a body casing 3; a bearing 42; a coil 5, a permanent magnet 81 and a yoke 82 for driving the movable part 1 to reciprocate; a dynamic vibration damper 71; and a spring 72. A bearing contact shaft part 11a serving as a contact part with the bearing 42 of the output shaft 11 is formed of martensite-based stainless steel, and a rust-proof shaft part 11b which is a part other than the bearing contact shaft part 11a is formed of austenite-based stainless steel. The bearing contact shaft part 11a and the rust-proof shaft part 11b independent of each other are jointed to form the output shaft 11. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric toothbrush having a linear oscillator as a drive section.

[0002]

2. Description of the Related Art Conventionally, electric toothbrushes having a linear oscillator as a drive unit have been used, which will be described below.

As shown in FIG. 13, the electric toothbrush is composed of a movable portion 1 provided with a brush portion 13 and a fixed portion 2 which supports the movable portion 1 to reciprocate and reciprocally drives it. The movable part 1 is configured by providing a plunger 12 on an output shaft 11.

The fixed portion 2 has a substantially cylindrical main body casing 3 serving as an outer shell, and a pair of bearing units 4 (4a, 4a, 4a, 4a, 4a, 4b) disposed in the main body casing 3 and reciprocally receiving the movable portion 1. 4b), a coil 5 and a yoke unit 6'provided in the main body casing 3 for reciprocatingly driving the movable portion 1, and a dynamic vibration absorber 71 and a spring arranged in the main body casing 3 for moving together with the movable portion 1. 72 and 72.

The bearing units 4 are respectively arranged at both ends in the longitudinal direction inside the main body casing 3, and the bearings 42 provided inside the output shaft 1 of the movable portion 1
1 is reciprocally movable in the axial direction. The permanent magnet 81 and the yoke 82 are disposed in one bearing unit 4a of the two bearing units 4.

A coil 5 and a yoke unit 6'are arranged between the bearing units 4 on both sides inside the main body casing 3. The yoke unit 6'is a substantially tubular main body tubular portion 6
An annular ring portion 63 ′ through which the movable portion 1 is inserted is provided inside 1 ′, and in the space on the coil 5 side partitioned by the ring portion 63 ′ inside the main body tubular portion 61 ′, A permanent magnet 81b and a yoke 82b similar to the permanent magnet 81a and the yoke 82a provided on the one bearing unit 4a are provided. Further, the dynamic vibration absorber 71 is arranged in the space S on the side of the annular portion 63 ′ of the main body tubular portion 61 ′ where the permanent magnet 81b and the yoke 82b are not provided.

Inside the main body casing 3, the above-mentioned one bearing unit 4a, the coil 5, the yoke unit 6'and the other bearing unit 4b are arranged in this order, and the one bearing unit 4a and the movable portion 1 are arranged. A spring 72 is provided between the plunger 12, the plunger 12 and the dynamic vibration absorber 71, and between the dynamic vibration absorber 71 and the other bearing unit 4b.
Is provided. By doing so, the same permanent magnet 81 and yoke 82 are arranged on both sides of the coil 5, and the plunger 12 of the movable part 1 is fixed to the fixed part 2.
The movable part 1 is vibrated by the spring (including the dynamic vibration reducer 71).

The dynamic vibration reducer 71 is for suppressing the force and vibration transmitted to the fixed part 2 (excluding the dynamic vibration reducer 71) due to the vibration of the movable part 1, and it depends on the mass of the movable part 1. It requires mass.

By the way, in such an electric toothbrush, the movable portion 1 is reciprocally supported by the fixed portion 2 as described above, and more specifically, the bearing 42 of the fixed portion 2 is supported by the fixed portion 2. The output shaft 11 of the movable part 1 is supported so as to be reciprocally movable. Since such an output shaft 11 comes into contact with the bearing 42, quenching processing for wear resistance is required, and plating processing for rust prevention is required because water, toothpaste, etc. adhere. In order to manufacture the output shaft 11, the output shaft 11 is hardened and then plated.

However, in such an output shaft 11, since the surface is plated, the plating is peeled off by contact with the bearing 42, and the output shaft 11
There is a problem that the clearance between the bearing 42 and the bearing 42 becomes large and the vibration and noise of the bearing system become large.

[0011]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and an object of the present invention is to electrically drive a movable portion including an output shaft provided with a plunger so that the movable portion can be reciprocally driven. It is an object of the present invention to provide an electric toothbrush having an output shaft which can be provided with wear resistance and anticorrosion function without plating the surface.

[0012]

In order to solve the above problems, an electric toothbrush according to the present invention has a movable part 1 having an output shaft 11 provided with a plunger 12, and a reciprocating motion of the movable part 1 in the axial direction. The movable portion 1 is reciprocally movable in the axial direction in a main body casing 3 having a substantially cylindrical shape, which is roughly constituted by a fixed portion 2 which is freely supported and reciprocally driven, and which is an outer shell of the fixed portion 2. In the electric toothbrush that forms the fixed portion 2 by disposing the bearing 42 that supports it, the coil 5 that reciprocally drives the movable portion 1, the permanent magnet 81 and the yoke 82, the dynamic vibration absorber 71 and the spring 72, the output shaft 11 1. The bearing contact shaft portion 11a, which is the portion that comes into contact with the bearing 42, is formed of martensitic stainless steel, and the rust preventive shaft portion 11b, which is the portion other than the bearing contact shaft portion 11a, is austenitic stainless steel. Formed, bearing contact shank portion 11a of the separate
And the rustproof shaft portion 11b are joined together to form the output shaft 11. With such a configuration, the output shaft 11 can be provided with wear resistance and rust preventive function without plating the output shaft 11 for rust prevention, and the output due to the peeling of the plating can be achieved. It is possible to prevent an increase in clearance between the shaft 11 and the bearing 42 and an increase in vibration and noise of the bearing system resulting from the increase.

Further, the bearing contact shaft portion 11a and the rustproof shaft portion 11
It is preferable that the output shaft 11 is formed by welding and b. With such a structure, it becomes possible to bond them with high strength in a short time.

Further, the bearing contact shaft portion 11a and the rustproof shaft portion 11
It is preferable that the output shaft 11 is formed by forming the joint surfaces 91 with b respectively in a flat shape, and abutting and welding the joint surfaces 91. With such a configuration, the joint strength between the bearing contact shaft portion 11a and the rustproof shaft portion 11b can be improved.

Further, the bearing contact shaft portion 11a and the rustproof shaft portion 11
The convex portion 92 is provided on one side of the joint surface 91 with b and the concave portion 93 for fitting with the convex portion 92 is provided on the other side.
It is preferable that the output shaft 11 is formed by fitting concave and convex portions, butting them together, and welding them together. With such a configuration, the bearing contact shaft portion 11a and the rustproof shaft portion 11b to be joined are joined together.
It is possible to improve the positioning accuracy of coaxiality with
The tipping accuracy of the shaft tip can be improved.

Further, the bearing contact shaft portion 11a and the rustproof shaft portion 11
Recesses 93 into which both ends of the pin 94 are fitted are provided in the joint surface 91 with b, and the joint surface 91 is abutted to form the recess 9
It is preferable to form the output shaft 11 by welding and joining the both ends of the pin 94 to the pin 3 respectively. With such a configuration, the bearing contact shaft portion 11 to be joined
It is possible to improve the positioning accuracy of the coaxiality between the a and the rust preventive shaft portion 11b, and to improve the tilt accuracy of the shaft tip.

Further, the bearing contact shaft portion 11a and the rustproof shaft portion 11
It is preferable that the output shaft 11 is formed by bonding and b to each other. With such a configuration, it is possible to join without particularly investing in equipment.

Further, the bearing contact shaft portion 11a and the rustproof shaft portion 11
It is preferable that the output shaft 11 is formed by forming each of the joint surfaces 91 with b in a planar shape and adhering the joint surfaces 91 by butting. With such a configuration, the joint strength between the bearing contact shaft portion 11a and the rustproof shaft portion 11b can be improved.

Further, the bearing contact shaft portion 11a and the rustproof shaft portion 11
The convex portion 92 is provided on one side of the joint surface 91 with b and the concave portion 93 for fitting with the convex portion 92 is provided on the other side.
It is preferable that the output shaft 11 is formed by fitting concave and convex portions, butting them together, and adhering them. With such a configuration, the bearing contact shaft portion 11a and the rustproof shaft portion 11b to be joined are joined together.
It is possible to improve the positioning accuracy of coaxiality with
The tipping accuracy of the shaft tip can be improved.

Further, the bearing contact shaft portion 11a and the rustproof shaft portion 11
Recesses 93 into which both ends of the pin 94 are fitted are provided in the joint surface 91 with b, and the joint surface 91 is abutted to form the recess 9
It is preferable to form the output shaft 11 by adhesively joining the both ends of the pin 94 to the pin 3 in a fitted state. With such a configuration, the bearing contact shaft portion 11 to be joined
It is possible to improve the positioning accuracy of the coaxiality between the a and the rust preventive shaft portion 11b, and to improve the tilt accuracy of the shaft tip.

Further, the bearing contact shaft portion 11a and the rustproof shaft portion 11
By providing the convex portion 92 on one side of the joint surface 91 with b and the concave portion 93 having a diameter smaller than the diameter of the convex portion 92 on the other side, the joint surface 91 is formed into a concavo-convex fit and abutted and joined. It is preferable to form the output shaft 11. With such a configuration, it is possible to improve the positioning accuracy of the coaxiality between the bearing contact shaft portion 11a and the rustproof shaft portion 11b to be joined, and it is possible to improve the accuracy of tipping of the shaft tip. Since the joint strength can be adjusted by adjusting the diameter of the convex portion 92 and the inner diameter of the concave portion 93, no equipment investment is required to adjust the joint strength.

Further, the bearing contact shaft portion 11a and the rustproof shaft portion 11
Recesses 93 each having a diameter smaller than the diameter of the pin 94 into which both ends of the pin 94 are fitted are provided in the joint surface 91 with b, and the joint surface 91 is abutted with each other so that both ends of the pin 94 are tightly fitted. It is preferable to form the output shaft 11 by joining them in a fitted state. With such a configuration, the bearing contact shaft portion 11a and the rustproof shaft portion 11 to be joined are joined together.
The positioning accuracy of the coaxiality with b can be improved, and the tilting accuracy of the shaft tip can be improved. Further, by adjusting the diameter of the convex portion 92 and the inner diameter of the concave portion 93, the joining can be achieved. Since the strength can be adjusted, no equipment investment is required to adjust the bonding strength.

Further, the bearing contact shaft portion 11a and the rustproof shaft portion 11
The convex portion 92 is provided on one side of the joint surface 91 with b, and the concave portion 93 that fits with the convex portion 92 is provided on the other side.
2 and the recess 93 are recessed and engaged with each other, a communication hole 95 that communicates in the direction orthogonal to the axial direction is bored in the projection 92 and the recess 93, and the female screw f is inserted in the communication hole 95 drilled in the projection 92. The male screw m is formed at a portion corresponding to the convex portion 92 of the pin member 96 that is formed and fitted into the communication hole 95, and the bearing contact shaft portion 11a is formed.
The joint surface 91 of the rust preventive shaft portion 11b and the rust prevention shaft portion 11b is fitted into and abutted against each other, and the pin member 96 is inserted into the communication hole 95 and the portion corresponding to the convex portion 92 is screwed into and joined to the output shaft. It is preferable to form 11. With such a configuration, the strength of the output shaft 11 in the axial direction of movement is determined by the shear strength of the pin member 96 that has been tightened. Therefore, by increasing the diameter of the pin member 96, high-strength joining can be achieved. It can be in a state.

Further, the bearing contact shaft portion 11a and the rustproof shaft portion 11
The convex portion 92 is provided on one side of the joint surface 91 with b, and the concave portion 93 that fits with the convex portion 92 is provided on the other side.
It is preferable that the output shaft 11 is formed by forming a male screw m on the second portion, forming a female screw f on the concave portion 93, and screwing and joining the convex portion 92 and the concave portion 93. With such a configuration, the strength of the output shaft 11 in the axial direction of movement is determined by the tensile strength of the tightened screw thread. Therefore, by increasing the screw thread, a high-strength welded state can be obtained. can do.

Further, the bearing contact shaft portion 11a and the rustproof shaft portion 11
The convex portion 92 is provided on one side of the joint surface 91 with b, and the concave portion 93 that fits with the convex portion 92 is provided on the other side.
2 and the recess 93 are recessed and engaged with each other, a communication hole 95 that communicates in a direction orthogonal to the axial direction is bored in the projection 92 and the recess 93 to join the bearing contact shaft 11a and the rust preventive shaft 11b. Face 9
It is preferable that the output shaft 11 is formed by fitting 1 into a concavo-convex fit and abutting them together, and fitting the pin member 96 into the communication hole 95 in an interference fit shape and joining. With such a configuration, the strength of the output shaft 11 in the axial direction of movement is determined by the shear strength of the pin member 96 fitted in the interference fit, and therefore the diameter of the pin member 96 can be increased. A high-strength bonded state can be obtained.

Further, the bearing contact shaft portion 11a and the rustproof shaft portion 11
The convex portion 92 is provided on one side of the joint surface 91 with b, and the concave portion 93 that fits with the convex portion 92 is provided on the other side.
2 the protruding base is formed to have a smaller diameter than the tip,
It is preferable to form the output shaft 11 by fitting the convex portion 92 and the concave portion 93 into concave and convex portions and caulking and joining the tip end opening portion of the concave portion 93 to the protruding base portion side of the convex portion 92. With such a configuration, since caulking is performed on the circumference of the output shaft 11, tilting or the like in the axial direction can be minimized.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below based on the embodiments shown in the accompanying drawings. First, the overall configuration of the electric toothbrush in this embodiment will be described.

As shown in FIG. 1, the electric toothbrush has a movable portion 1 constructed by providing a plunger 12 on an output shaft 11.
And a fixed portion 2 which supports the movable portion 1 so as to be reciprocally movable in the axial direction and is driven to reciprocate.

The movable part 1 has a plunger 1 on the output shaft 11.
2 is provided. The output shaft 11 has a cylindrical shape and is formed to be longer than the length of the main body casing 3 in the longitudinal direction, which will be described later. As will be described later, the bearing contact shaft portion 11a and a rust preventive shaft that is a separate body from the bearing contact shaft portion 11a. It is formed by joining the portion 11b. Further, the brush portion 13 of the attachment is detachably attached to the tip portion of the output shaft 11 of the movable portion 1. The plunger 12 is made of a magnetic material such as iron attached to a part of the outer peripheral surface of the output shaft 11 in the axial direction, and has a large diameter in the vicinity of both ends in the axial direction and a small diameter in the central portion. Such a movable portion 1 is supported by the fixed portion 2 so as to be reciprocally movable in the axial direction with respect to the fixed portion 2.

The fixed portion 2 has a substantially cylindrical main body casing 3 serving as an outer shell, and a pair of bearing units 4 disposed in the main body casing 3 to reciprocally receive the movable portion 1.
(4a, 4b), the coil 5 and the yoke unit 6 which are arranged in the main body casing 3 and reciprocally drive the movable portion 1.
And a dynamic vibration absorber 71 and a spring 72 that are arranged in the main body casing 3 and move together with the movable portion 1.

The bearing unit 4 comprises one bearing unit 4a and the other bearing unit 4b, which are arranged at both ends in the longitudinal direction in the main body casing 3. The bearing unit 4 includes a bearing casing 41, a bearing 42, and a spring bearing member 43 as a basic part.
The bearing casing 41 has an outer shape along the inner surface of the main body casing 3 and a substantially columnar shape in which an insertion hole 45 through which the output shaft 11 of the movable portion 1 is inserted is bored. A bottomed groove 46 that opens is formed along the insertion hole 45. The bearing 42 is fitted and provided so as to abut the bottom surface 46 a of the bottomed groove 46, and the spring receiving member 43 is provided so as to be fitted into the bottomed groove 46 so as to abut the side surface of the bearing 42.
By thus providing the bearing 42, the output shaft 11 of the movable portion 1 is reciprocally received in the axial direction. Further, the spring receiving member 43 is formed by continuously connecting the cylindrical side surface portion 48 from the outer peripheral edge of the disk 47 in which the hole 47a similar to the insertion hole 45 of the bearing casing 41 is drilled, and the spring 72 described later has a bottom. The bearing 42 is sandwiched between the bottom surface 46a of the groove 46 and the bottom surface 46a of the bottomed groove 46 by being biased by the spring.

The above is the basic structure of the bearing unit 4, and the other bearing unit 4b of the pair of bearing units 4a, 4b is the same as the above described structure. Is a permanent magnet 8 to be described later.
1 and the yoke 82 are provided. In this configuration, a cylindrical portion 44 is continuously provided from the outer peripheral edge of the end surface of the bearing casing 41 of one bearing unit 4a on the main body casing 3 side, and the permanent magnet 81a and the yoke 82a on one side are provided inside the cylindrical portion 44. It is provided. This one side permanent magnet 81
The a and the yoke 82a have an outer shape that follows the inner wall surface of the tubular portion 44 of the bearing casing 41, and have an annular shape into which the movable portion 1 is inserted. The yoke 82a, the permanent magnet 81a, and the yoke 82a. Bearing casing 41 in line
The permanent magnet 81a and the yoke 82 on one side of the bearing casing 41 and the coil 5 are arranged inside the tubular portion 44 of the.
It sandwiches a with a.

The coil 5 has a ring-like shape having an outer shape along the inner surface of the main body casing 3, and the movable portion 1 is inserted therein. In particular, when the movable portion 1 supported by the fixed portion 2 is stationary, the plunger 12 of the movable portion 1 is formed so as to be located immediately outside the coil 5. Such a coil 5 is arranged adjacent to one bearing unit 4a, and further adjacent to the opposite side of the coil 5 from the one bearing unit 4a.
Is provided.

The yoke unit 6 is a yoke casing 6
1 and the permanent magnet 81b and the yoke 82b on the other side. The yoke casing 61 has a cylindrical side surface portion 62 having an outer shape along the inner surface of the main body casing 3, and an annular plate portion 6 provided at an end edge of the cylindrical side surface portion 62 and through which the movable portion 1 is inserted.
3 and 3. The permanent magnet 81b and the yoke 82b on the other side are arranged inside the cylindrical side surface portion 62. The permanent magnet 81b and the yoke 82b on the other side are the same as the permanent magnet 81a and the yoke 82a on the one side,
The outer shape has a shape along the inner wall surface of the cylindrical side surface portion 62 of the yoke casing 61 and has an annular shape into which the movable portion 1 is inserted. The yoke 82b, the permanent magnet 81b, and the yoke 8 are provided.
2b are arranged inside the cylindrical side surface portion 62 of the yoke casing 61, and the permanent magnet 81b and the yoke 82 on the other side are arranged by the annular plate portion 63 of the yoke casing 61 and the coil 5.
It is for sandwiching b and.

In this way, one bearing unit 4a, the coil 5, the yoke unit 6 and the other bearing unit 4b are arranged in this order in the main body casing 3, and the permanent magnet 81 and the yoke 82 are arranged on both sides of the coil 5. Then, the movable part 1 is reciprocally driven. At this time, in order to sandwich the coil 5 between the yoke unit 6 and one bearing unit 4a,
The yoke unit 6 is hooked on a hooking piece 73 protrudingly provided on the inner surface of the main body casing 3, and the coil 5 is brought into contact with the yoke unit 6 and one bearing unit 4a is brought into contact with the coil 5 so that the one bearing This is because the unit 4a is fixed. The hooking piece 73 is provided by forming a protrusion on the inner surface of the main body casing 3 so that the yoke unit 6 can be hooked.

In the body casing 3, the movable part 1
A spring 72 for reciprocating the fixed part 2 with respect to the fixed part 2,
A dynamic vibration absorber 71 that prevents the vibration of the movable portion 1 from being transmitted to the fixed portion 2 is provided.

The dynamic vibration reducer 71 has an annular shape in which the output shaft 11 of the movable portion 1 is inserted, and the yoke unit 6
And the other bearing unit 4b. Then, the dynamic vibration absorber 71 and the other bearing unit 4b on both sides thereof.
Between the spring and the plunger 12 are springs 72b, 7 respectively.
2c is urged and arranged, and a spring 72 is also provided between the plunger 12 and one bearing unit 4a.
It is arranged such that a is biased. The end of the spring 72 on the side biased by the bearing unit 4 is arranged on the spring bearing member 43 of the bearing unit 4 described above.

The above is the overall structure of the electric toothbrush of the present embodiment, and the drive unit is called a so-called linear oscillator. The operation of this electric toothbrush will be described.

First, when the coil 5 is not energized, the permanent magnet 81 is connected to the plunger 1 via the yoke 82.
The magnetic force exerted on 2 and the spring force of the spring 72 balance each other, so that the plunger 12 is stationary.

Next, when a current is applied to the coil 5, a unidirectional current is applied to the coil 5, and the permanent magnets 8 on both sides of the coil 5 are applied.
When one of the magnetic fluxes of 1 is weakened to move to the other permanent magnet side 8 against the spring force and a reverse current is applied to the coil 5, the magnetic flux of the other permanent magnet 81 is weakened and the spring force is increased. The plunger 12 reciprocates in the axial direction by passing an alternating current through the coil 5 since it moves toward the opposite permanent magnet 81 side against the force.

At this time, by applying an alternating current near the resonance frequency determined by the mass of the movable portion 1,
The reciprocating motion of is a vibration in a resonance state. Here, focusing on the axial movement of the movable part 1 including the plunger 12 and the output shaft 11, the dynamic vibration absorber 71, and the fixed part 2 excluding the dynamic vibration reducer 71, one bearing unit 4a of the fixed part 2 is provided. And the dynamic vibration reducer 71, between the dynamic vibration reducer 71 and the plunger 12 of the movable part 1, and between the plunger 12 and the other bearing unit 4b of the fixed part 2 respectively. Since it is biased by the spring 72 constituted by 72, it can be considered as a vibration model of a three-mass system including the movable part 1, the dynamic vibration reducer 71, and the fixed part 2 excluding the dynamic vibration reducer 71.
When operating these, the movable part 1 and the dynamic vibration reducer 7
By performing the motions in the vibration mode in which 1 and 2 vibrate in the opposite phase, the inertial forces of the movable portion 1 and the dynamic vibration absorber 71 cancel each other out, and the movable portion 1 and the dynamic vibration absorber 71 move from the main body casing 3 It is possible to keep the power transmitted to the body small.

According to the present invention, in the output shaft 11 of the electric toothbrush as described above, the bearing contact shaft portion 11a, which is a portion that comes into contact with the bearing 42, is formed of martensitic stainless steel, and the parts other than the bearing contact shaft portion 11a are formed. The rust preventive shaft portion 11b which is a part is formed of austenitic stainless steel, and the separate bearing contact shaft portion 11a and the rust preventive shaft portion 11b are joined to form one output shaft 11. Detailed description.

As shown in FIG. 2, the output shaft 11 has a bearing contact shaft portion 11a which contacts the bearing 42, and a portion other than the bearing contact shaft portion 11a (that is, the brush portion of the output shaft 11 in this embodiment). The side on which 13 is attached is the rustproof shaft portion 11b.

The bearing contact shaft portion 11a is made of martensitic stainless steel, and is used as a wear resistant material for suppressing wear due to rolling contact with the bearing 42. The rust preventive shaft portion 11b is made of austenitic stainless steel and is used as a rust preventive material for preventing rust due to adhesion of water, toothpaste or the like.

In such an output shaft 11, as shown in FIG. 2, the joint surfaces 91a and 91b of the bearing contact shaft portion 11a and the rust preventive shaft portion 11b are formed in a flat shape. The output shaft 11 is formed by abutting 91b and joining them by welding or adhesion.

As described above, since the output shaft 11 is formed by joining the bearing contact shaft portion 11a and the rustproof shaft portion 11b, which are separate members, to each other, the bearing contact portion 11a contacting the bearing 42 is made of martens. In addition to forming the site-type stainless steel, the rust-preventing shaft portion 11b, to which water, dentifrice, etc. easily adhere, is formed of austenitic stainless steel and these are joined together, so that the output shaft 11 is plated for rust-prevention. The output shaft 11 can be provided with abrasion resistance and anticorrosion function without applying it, and the clearance between the output shaft 11 and the bearing 42 increases due to the peeling of the plating, and the vibration and noise of the bearing system resulting from the increase. It is possible to prevent the increase of Further, in the case where the bearing contact shaft portion 11a and the rustproof shaft portion 11b are joined by welding, it is possible to join them with high strength in a short time. In the case where the rust preventive shaft portion 11b is joined by adhesion, the joining can be made possible without particularly investing in equipment.
Furthermore, by forming the joint surfaces 91a and 91b by welding the bearing contact shaft portion 11a and the rust-preventive shaft portion 11b respectively in a flat shape, the joint strength between these can be improved.

Further, the bearing contact shaft portion 11a and the rustproof shaft portion 11
The convex portion 92 is provided on one side of the joint surface 91 with b and the concave portion 93 for fitting with the convex portion 92 is provided on the other side.
It is also possible to fit them by concavo-convex fitting and butting them together. As shown in FIG. 3, this is because the projection 92 is provided on the joint surface 91b of the rustproof shaft 11b and the bearing contact shaft 11a.
Is provided with a concave portion 93 for fitting with the convex portion 92, or, as shown in FIG. 4, the bearing contact shaft portion 11
The convex portion 92 is provided on the joint surface 91a of "a" and the rustproof shaft portion 1 is formed.
A concave portion 93 that fits with the convex portion 92 on the joint surface 91b of 1b.
Is provided, and the convex portion 92 and the concave portion 93 are fitted in the concave and convex portions. Then, the abutting faces are welded or bonded to each other, or the inner diameter of the concave portion 93 is made smaller than the diameter of the convex portion 92 and the fitting portions are fitted into each other by interference fitting to join them.

By doing so, the positioning accuracy of the coaxiality between the bearing contact shaft portion 11a and the rustproof shaft portion 11b to be joined can be improved, and the tilting accuracy of the shaft tip can be improved. In addition, in the case of fitting in an interference fit shape, the joint strength can be adjusted by adjusting the diameter of the convex portion 92 and the inner diameter of the concave portion 93, so that a capital investment is particularly required to adjust the joint strength. And not.

Further, as shown in FIG. 5, the bearing contact shaft portion 1
The joint surface 91 between the 1a and the rustproof shaft portion 11b is provided with recesses 93 into which both ends of the pin 94 are fitted, and the joint surface 91 is butted to fit both ends of the pin 94 into the recessed portion 93, and the butted surfaces are joined together. Are joined together by welding or adhering, or by forming the inner diameter of the concave portion 93 to be smaller than the diameter of the pin 94 and fitting it into an interference fit.

By doing so, the positioning accuracy of the coaxiality between the bearing contact shaft portion 11a and the rustproof shaft portion 11b to be joined can be improved, and the tilting accuracy of the shaft tip can be improved. In addition, in the case of fitting in an interference fit shape, the joint strength can be adjusted by adjusting the diameter of the convex portion 92 and the inner diameter of the concave portion 93, so that a capital investment is particularly required to adjust the joint strength. And not.

Further, as shown in FIG. 6 (a), a convex portion 92 is provided on one of the joint surfaces 91 of the bearing contact shaft portion 11a and the rustproof shaft portion 11b, and the convex portion 92 is fitted on the other. A concave portion 93 is provided (in the structure shown in FIG. 6, a convex portion 92 is provided on the joint surface 91a of the bearing contact shaft portion 11a, and a concave portion 93 for fitting with the convex portion 92 is provided on the joint surface 91b of the rust preventive shaft portion 11b. ), When the convex portion 92 and the concave portion 93 are fitted in the concave and convex portions, a communicating hole 95 that communicates in a direction orthogonal to the axial direction is formed in the convex portion 92 and the concave portion 93, and the communicating hole 95 is formed in the convex portion 92. A female screw f is formed on the surface of the pin member 96, and a male screw m is formed on a portion of the pin member 96 that is fitted into the communication hole 95 at a position corresponding to the convex portion 92 of the pin member 96.
6 is fitted in a concavo-convex shape and abutted against each other, and as shown in FIG.
You may screw and join the part corresponding to.

By doing so, the strength of the output shaft 11 in the axial direction of movement is determined by the shear strength of the pin member 96 tightened. Therefore, increasing the diameter of the pin member 96 results in high strength. It can be in a bonded state.

Further, the bearing contact shaft portion 11a and the rustproof shaft portion 11
The convex portion 92 is provided on one side of the joint surface 91 with b, and the concave portion 93 that fits with the convex portion 92 is provided on the other side.
It is also possible to form a male screw m in 2 and a female screw f in the concave portion 93, and screw the convex portion 92 and the concave portion 93 together to join them. This is as shown in FIG.
b is provided with a convex portion 92 on the joint surface 91b and the joint surface 91a of the bearing contact shaft portion 11a is provided with a concave portion 93 for fitting with the convex portion 92, or, as shown in FIG. A male screw formed on the convex portion 92 as shown in FIGS. 7 and 8 is provided with a convex portion 92 on the joint surface 91a and a concave portion 93 for fitting with the convex portion 92 on the joint surface 91b of the rustproof shaft portion 11b. m and the female screw f formed in the recess 93 are screwed together and joined.

By doing so, the strength of the output shaft 11 with respect to the axial movement direction is determined by the tensile strength of the tightened screw thread. Therefore, by increasing the screw thread, a high-strength welded state can be obtained. Can be

Further, the bearing contact shaft portion 11a and the rustproof shaft portion 11
The convex portion 92 is provided on one side of the joint surface 91 with b, and the concave portion 93 that fits with the convex portion 92 is provided on the other side.
2 and the recess 93 are recessed and engaged with each other, a communication hole 95 that communicates in a direction orthogonal to the axial direction is bored in the projection 92 and the recess 93 to join the bearing contact shaft 11a and the rust preventive shaft 11b. Face 9
It is also possible to fit 1 into a concavo-convex shape and abut against each other, and to insert the pin member 96 into the communication hole 95 in an interference-fitting manner to join them. As shown in FIG. 9, this is because the projection 92 is provided on the joint surface 91b of the rustproof shaft 11b and the bearing contact shaft 1 is formed.
A concave portion 93 that fits with the convex portion 92 on the joint surface 91a of 1a
10, or as shown in FIG. 10, a convex portion 92 is provided on the joint surface 91a of the bearing contact shaft portion 11a, and a concave portion 93 for fitting with the convex portion 92 is provided on the joint surface 91b of the rust preventive shaft portion 11b. As shown in FIGS. 9 and 10, a convex portion 92, a concave portion 93, and a communication hole 95 are bored, and a joint surface 91 between the bearing contact shaft portion 11a and the rustproof shaft portion 11b is fitted in a concavo-convex shape and abutted to form a communication hole. The pin member 96 is fitted into the pin 95 in a form of interference fit and joined.

By doing so, the strength of the output shaft 11 in the axial direction of movement is determined by the shear strength of the pin member 96 fitted in the interference fit, and therefore the pin member 96.
It is possible to obtain a high-strength joined state by increasing the diameter of.

Further, the bearing contact shaft portion 11a and the rustproof shaft portion 11
The convex portion 92 is provided on one side of the joint surface 91 with b, and the concave portion 93 that fits with the convex portion 92 is provided on the other side.
2 the protruding base is formed to have a smaller diameter than the tip,
The convex portion 92 and the concave portion 93 may be fitted in the concave and convex portions, and the tip end opening portion of the concave portion 93 may be caulked to the protruding base portion side of the convex portion 92 to be joined. This is because, as shown in FIG. 11, a convex portion 92 is provided on the joint surface 91b of the rust preventive shaft portion 11b and a concave portion 93 for fitting with the convex portion 92 is provided on the joint surface 91a of the bearing contact shaft portion 11a. Alternatively, as shown in FIG. 12, the convex portion 92 is provided on the joint surface 91a of the bearing contact shaft portion 11a, and the convex portion 9 is formed on the joint surface 91b of the rust preventive shaft portion 11b.
2 is provided, the protruding base portion of the protruding portion 92 is formed to have a diameter smaller than that of the tip end portion as shown in FIGS. 11 and 12, and the protruding portion 92 and the recessed portion 93 are fitted in a concavo-convex shape. At the same time, the tip end opening of the concave portion 93 is caulked to the protruding base portion side of the convex portion 92 to join them.

By doing so, since caulking is performed on the circumference of the output shaft 11, tilting in the axial direction can be minimized.

[0059]

As described above, in the invention according to the first aspect of the present invention, the movable portion having the plunger provided on the output shaft, and the movable portion supported so as to be reciprocally movable in the axial direction. And a fixed portion that is reciprocally driven, and a bearing that supports the movable portion in an axially reciprocating manner in a substantially cylindrical main body casing that serves as an outer shell of the fixed portion, and the movable portion reciprocates. In an electric toothbrush that forms the fixed portion by arranging a coil to be driven, a permanent magnet and a yoke, a dynamic vibration reducer and a spring, a bearing contact shaft portion that is a portion that comes into contact with the bearing of the output shaft is made of martensitic stainless steel. Formed from steel, the rustproof shaft that is the part other than the bearing contact shaft is formed from austenitic stainless steel, and the separate bearing contact shaft and rustproof shaft are joined to form the output shaft. Because I did
This output shaft can be equipped with abrasion resistance and rust prevention function without plating the output shaft for rust prevention.
It is possible to prevent an increase in clearance between the output shaft and the bearing due to peeling of the plating and an increase in vibration and noise of the bearing system resulting from the increase.

According to the invention of claim 2, in addition to the effect of the invention of claim 1, the output shaft is formed by joining the bearing contact shaft portion and the rustproof shaft portion by welding. Therefore, it becomes possible to bond them with high strength in a short time.

According to the invention of claim 3, in addition to the effect of the invention of claim 2, the joint surfaces of the bearing contact shaft portion and the rust preventive shaft portion are each formed into a flat surface, Since the output shaft is formed by welding the joint surfaces to each other by welding, the joint strength between the bearing contact shaft portion and the rustproof shaft portion can be improved.

According to the invention of claim 4, in addition to the effect of the invention of claim 2, a convex portion is provided on one of the joint surfaces of the bearing contact shaft portion and the rust preventive shaft portion, and the other is formed. Since the concave portion to be fitted with the convex portion is provided in, and the output surface is formed by welding the joint surfaces by concavo-convex fitting and butting,
It is possible to improve the positioning accuracy of the coaxiality between the bearing contact shaft portion and the rustproof shaft portion to be joined, and to improve the accuracy of tipping of the shaft tip.

According to the invention of claim 5, in addition to the effect of the invention of claim 2, both ends of the pin are fitted into the joint surface between the bearing contact shaft portion and the rustproof shaft portion. Since the output shaft was formed by providing recesses respectively and joining the joint surfaces and welding both ends of the pins into the recesses, the output shaft was formed. The positioning accuracy can be improved and the tipping accuracy of the shaft tip can be improved.

According to the invention of claim 6, in addition to the effect of the invention of claim 1, the output shaft is formed by bonding the bearing contact shaft portion and the rustproof shaft portion by adhesion. Therefore, joining can be made possible without particularly investing in equipment.

According to the invention of claim 7, in addition to the effect of the invention of claim 6, the joint surfaces of the bearing contact shaft portion and the rust preventive shaft portion are each formed into a flat surface, Since the output shaft is formed by abutting and joining the joint surfaces to each other, the joint strength between the bearing contact shaft portion and the rustproof shaft portion can be improved.

In addition to the effect of the invention described in claim 6, the invention described in claim 8 provides a convex portion on one of the joint surfaces of the bearing contact shaft portion and the rust-preventive shaft portion and the other. Since the concave portion to be fitted with the convex portion is provided in, and the joint surface is concave-convex fitted, the output shaft is formed by butt-bonding and joining,
It is possible to improve the positioning accuracy of the coaxiality between the bearing contact shaft portion and the rustproof shaft portion to be joined, and to improve the accuracy of tipping of the shaft tip.

According to the invention of claim 9, in addition to the effect of the invention of claim 6, both ends of the pin are fitted into the joint surface between the bearing contact shaft portion and the rustproof shaft portion. Since the output shaft was formed by providing concave portions respectively, and by joining the joint surfaces and fitting both ends of the pins into the concave portions, the output shaft was formed. The positioning accuracy can be improved and the tipping accuracy of the shaft tip can be improved.

In addition to the effect of the invention described in claim 1, in the invention described in claim 10, a convex portion is provided on one of the joint surfaces of the bearing contact shaft portion and the rust-preventive shaft portion, and the other is formed. Since the output shaft is formed by providing a concave portion having a diameter smaller than that of the convex portion, and joining and joining the joint surfaces by concavo-convex fitting in a form of interference fit, the bearing contact shaft portion and the rust preventive shaft portion to be joined are The positioning accuracy of the concentricity can be improved, the tilting accuracy of the shaft tip can be improved, and the joint strength can be adjusted by adjusting the diameter of the convex portion and the inner diameter of the concave portion. It does not require any capital investment to adjust the strength.

According to the eleventh aspect of the invention, in addition to the effect of the first aspect of the invention, both ends of the pin are fitted into the joint surface between the bearing contact shaft portion and the rustproof shaft portion. Since the output shaft is formed by providing concave portions each having a diameter smaller than the diameter of the pin, and joining the joint surfaces in a state in which both end portions of the pins are fitted into the concave portions in an interference fit shape, the bearing contact shaft portion to be joined is formed. It is possible to improve the positioning accuracy of the coaxiality between the shaft and the rust preventive shaft part, and improve the accuracy of tilting the shaft tip, and to adjust the diameter of the convex part and the inner diameter of the concave part. Since the joint strength can be adjusted by means of this, no particular capital investment is required to adjust the joint strength.

According to the twelfth aspect of the invention, in addition to the effect of the first aspect of the invention, a convex portion is provided on one of the joint surfaces of the bearing contact shaft portion and the rust-preventive shaft portion, and the other is formed. Providing a concave portion that fits with the convex portion on the convex portion and the concave portion, the communicating hole that communicates in the direction orthogonal to the axial direction when the convex portion and the concave portion are fitted into the concave and convex portions is formed in the convex portion and the concave portion, and the convex portion is perforated. Female thread is formed in the communicating hole, and male thread is formed in the part corresponding to the convex part of the pin member inserted in the communicating hole, and the joint surface of the bearing contact shaft part and the rust-proof shaft part is mated unevenly. The output shaft was formed by inserting the pin member into the communication hole and screwing and joining the parts corresponding to the protrusions, so that the strength of the output shaft in the axial movement direction was tightened. Since it is determined by the shear strength of the pin member, increasing the diameter of the pin member ensures a high-strength joint. It is possible.

In addition to the effect of the invention described in claim 1, in the invention described in claim 13, a convex portion is provided on one of the joint surfaces of the bearing contact shaft portion and the rust preventive shaft portion while the other is provided. Since the convex portion is provided with a concave portion, the convex portion is formed with a male screw and the concave portion is formed with a female screw, and the convex portion and the concave portion are screwed together to form an output shaft. Since the strength with respect to the axial movement direction of the output shaft is determined by the tensile strength of the tightened screw thread, a high-strength joint can be obtained by increasing the screw thread.

In addition to the effect of the invention described in claim 1, the invention according to claim 14 provides a convex portion on one of the joint surfaces of the bearing contact shaft portion and the rust-preventive shaft portion and the other. A concave portion that fits with the convex portion is provided on the bearing contact shaft portion, and a communicating hole that communicates in a direction orthogonal to the axial direction when the convex portion and the concave portion are fitted into each other is formed in the convex portion and the concave portion. Since the output shaft is formed by fitting the mating surfaces of the rust prevention shaft and the rustproof shaft into a concavo-convex shape, and by fitting the pin member into the communication hole in a tight fit, the output shaft is formed. Since the strength in the direction is determined by the shear strength of the pin member fitted in the interference fit shape, it is possible to obtain a high-strength joined state by increasing the diameter of the pin member.

In addition to the effect of the invention described in claim 1, the invention described in claim 15 provides a convex portion on one of the joint surfaces of the bearing contact shaft portion and the anticorrosive shaft portion and the other. A concave portion that fits with the convex portion is provided, and a protruding base portion of the convex portion is formed to have a diameter smaller than that of the tip portion. Since the output shaft is formed by caulking and joining to the projecting base side, the caulking is performed on the circumference of the output shaft, so that tilting in the axial direction can be minimized.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an embodiment of the present invention.

FIG. 2 shows an example of an output shaft in the above embodiment,
(A) is an explanatory view showing a state where the bearing contact shaft portion and the rustproof shaft portion are separated, and (b) is an explanatory view showing a state where the bearing contact shaft portion and the rustproof shaft portion are joined. is there.

FIG. 3 shows another example of the output shaft in the above embodiment,
(A) is an explanatory view showing a state where the bearing contact shaft portion and the rustproof shaft portion are separated, and (b) is an explanatory view showing a state where the bearing contact shaft portion and the rustproof shaft portion are joined. is there.

FIG. 4 shows still another example of the output shaft in the above embodiment, (a) is an explanatory view showing a state where a bearing contact shaft portion and a rust preventive shaft portion are separated, and (b) is a bearing contact portion. It is explanatory drawing which shows the state by which the shaft part and the rustproof shaft part were joined.

FIG. 5 shows still another example of the output shaft in the same embodiment, (a) is an explanatory view showing a state where a bearing contact shaft portion and a rust preventive shaft portion are separated, and (b) is a bearing contact portion. It is explanatory drawing which shows the state by which the shaft part and the rustproof shaft part were joined.

FIG. 6 shows still another example of the output shaft in the above embodiment, (a) is an explanatory view showing a state where a bearing contact shaft portion and a rust preventive shaft portion are separated, and (b) is a bearing contact portion. It is explanatory drawing which shows the state by which the shaft part and the rustproof shaft part were joined.

FIG. 7 shows still another example of the output shaft in the above embodiment, (a) is an explanatory view showing a state where a bearing contact shaft portion and a rust preventive shaft portion are separated, and (b) is a bearing contact portion. It is explanatory drawing which shows the state by which the shaft part and the rustproof shaft part were joined.

FIG. 8 shows still another example of the output shaft in the above embodiment, (a) is an explanatory view showing a state in which the bearing contact shaft portion and the rust preventive shaft portion are separated, and (b) is a bearing contact portion. It is explanatory drawing which shows the state by which the shaft part and the rustproof shaft part were joined.

FIG. 9 shows still another example of the output shaft in the above embodiment, (a) is an explanatory view showing a state in which the bearing contact shaft portion and the rust preventive shaft portion are separated, and (b) is a bearing contact portion. It is explanatory drawing which shows the state by which the shaft part and the rustproof shaft part were joined.

FIG. 10 shows still another example of the output shaft in the same embodiment, (a) is an explanatory view showing a state in which the bearing contact shaft portion and the rust preventive shaft portion are separated, and (b) is a bearing contact portion. It is explanatory drawing which shows the state by which the shaft part and the rustproof shaft part were joined.

FIG. 11 shows still another example of the output shaft in the same embodiment, (a) is an explanatory view showing a state where the bearing contact shaft portion and the rustproof shaft portion are separated, and (b) is a bearing contact portion. It is explanatory drawing which shows the state by which the shaft part and the rustproof shaft part were joined.

FIG. 12 shows still another example of the output shaft in the above-mentioned embodiment, (a) is an explanatory view showing a state where a bearing contact shaft portion and a rust preventive shaft portion are separated, and (b) is a bearing contact portion. It is explanatory drawing which shows the state by which the shaft part and the rustproof shaft part were joined.

FIG. 13 is a sectional view of a conventional example.

[Explanation of symbols]

1 Moving part 11 Output shaft 11a Bearing contact shaft 11b Rust prevention shaft 12 Plunger 2 Fixed part 3 body casing 42 bearing 5 coils 71 Dynamic vibration absorber 72 spring 81 permanent magnet 82 York

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hiromitsu Inoue             1048, Kadoma, Kadoma-shi, Osaka Matsushita Electric Works Co., Ltd.             Inside the company (72) Inventor Tomio Yamada             1048, Kadoma, Kadoma-shi, Osaka Matsushita Electric Works Co., Ltd.             Inside the company F term (reference) 3B202 AA07 AB19 BA03 BC05 BE09                       DB05 DB09

Claims (15)

[Claims] 1. A movable portion having a plunger provided on an output shaft and a fixed portion that supports the movable portion so as to reciprocate in the axial direction and is reciprocally driven. A bearing that supports the movable portion so as to reciprocate in the axial direction, a coil that reciprocally drives the movable portion, a permanent magnet and a yoke, a dynamic vibration absorber and a spring are provided in a substantially cylindrical main body casing that serves as an outer shell. In the electric toothbrush that constitutes the fixed portion, the bearing contact shaft portion that is the portion that contacts the bearing of the output shaft is formed of martensitic stainless steel, and the portion other than the bearing contact shaft portion is rustproof. An electric toothbrush, characterized in that the shaft portion is formed of austenitic stainless steel, and a bearing contact shaft portion and a rustproof shaft portion which are separate bodies are joined to form an output shaft. 2. The output shaft is formed by joining the bearing contact shaft portion and the rustproof shaft portion by welding.
Electric toothbrush as described. 3. The output shaft is formed by forming the joint surfaces of the bearing contact shaft portion and the rust-preventive shaft portion into a flat shape, and by welding the joint surfaces by butting. Item 2. The electric toothbrush according to Item 2. 4. A welding is provided by providing a convex portion on one of the joint surfaces of the bearing contact shaft portion and the anticorrosive shaft portion and a concave portion for fitting with the convex portion on the other surface, and fitting the joint surfaces into a concavo-convex shape and abutting against each other. The electric toothbrush according to claim 2, wherein the output shaft is formed by joining them together. 5. Welding is performed in a state where recesses into which both ends of the pin are fitted are provided in a joint surface between the bearing contact shaft portion and the rust-preventive shaft portion, and the joint surfaces are butted and both ends of the pin are respectively fitted into the recess portions. The electric toothbrush according to claim 2, wherein the output shaft is formed by joining them together. 6. The output shaft is formed by bonding the bearing contact shaft portion and the rustproof shaft portion by adhesion.
Electric toothbrush as described. 7. The output shaft is formed by forming the joint surfaces of the bearing contact shaft portion and the rust-preventive shaft portion in a flat shape, and adhering and joining the joint surfaces. The electric toothbrush according to claim 6. 8. A convex portion is provided on one of the joint surfaces of the bearing contact shaft portion and the anticorrosive shaft portion, and a concave portion for fitting with the convex portion is provided on the other surface, and the joint surfaces are fitted in a concavo-convex shape and abutted and bonded together. The electric toothbrush according to claim 6, wherein the output shaft is formed by joining them together. 9. A joint is provided in each of the joint surfaces of the bearing contact shaft portion and the anticorrosion shaft portion so that both end portions of the pins are fitted, and the joint surfaces are butted and both end portions of the pins are respectively fitted in the concave portions. The electric toothbrush according to claim 6, wherein the output shaft is formed by joining them together. 10. A convex portion is provided on one of the joint surfaces of the bearing contact shaft portion and the anticorrosive shaft portion, and a concave portion having a diameter smaller than the diameter of the convex portion is provided on the other surface, and the joint surface is fitted in a concavo-convex shape by interference fitting. The electric toothbrush according to claim 1, wherein the output shaft is formed by butting and joining the output shaft. 11. The joint surface between the bearing contact shaft portion and the rustproof shaft portion is provided with recesses each having a diameter smaller than the diameter of the pin into which both end portions of the pin are fitted, and the joint surfaces are abutted to each other so that both end portions of the pin are in the recesses. The electric toothbrush according to claim 1, wherein the output shafts are formed by joining the respective parts in a state of being fitted in an interference fit shape. 12. A convex portion is provided on one of the joint surfaces of the bearing contact shaft portion and the anticorrosive shaft portion, and a concave portion for fitting the convex portion is provided on the other surface, and the convex portion and the concave portion are fitted in concavo-convex. At this time, a communicating hole communicating in the direction orthogonal to the axial direction is drilled in the convex portion and the concave portion, and a female screw is formed in the communicating hole drilled in the convex portion to correspond to the convex portion of the pin member fitted into the communicating hole. A male screw is formed on the part to be fitted, and the joint surface of the bearing contact shaft part and the rustproof shaft part is mated with each other by concavo-convex fitting, and the pin member is inserted into the communication hole to screw the part corresponding to the convex part. The electric toothbrush according to claim 1, wherein the output shaft is formed by joining them together. 13. A convex portion is provided on one of the joint surfaces of the bearing contact shaft portion and the anticorrosive shaft portion, and a concave portion for fitting with the convex portion is provided on the other surface, and a male screw is formed on the convex portion and a concave portion is formed. 2. The electric toothbrush according to claim 1, wherein a female screw is formed on the shaft, and the convex portion and the concave portion are screwed and joined to each other to form the output shaft. 14. A convex portion is provided on one of the joint surfaces of the bearing contact shaft portion and the anticorrosive shaft portion, and a concave portion is provided on the other surface so as to be fitted with the convex portion, and the convex portion and the concave portion are fitted in concave and convex. At this time, a communicating hole communicating in the direction orthogonal to the axial direction is drilled in the convex portion and the concave portion, the joint surface of the bearing contact shaft portion and the rust-proof shaft portion is fitted with the concave and convex portions, and the pin is inserted into the communicating hole. The electric toothbrush according to claim 1, wherein the output shaft is formed by fitting and joining the members in an interference fit shape. 15. A convex portion is provided on one of the joint surfaces of the bearing contact shaft portion and the anticorrosive shaft portion, and a concave portion that engages with the convex portion is provided on the other surface, and the projecting base portion of the convex portion is more than the tip portion. It is characterized in that it is formed to have a small diameter, the convex portion and the concave portion are fitted in concave and convex, and the tip end opening of the concave portion is caulked and joined to the protruding base portion side of the convex portion to form the output shaft. Claim 1
Electric toothbrush as described.