JPWO1997034710A1 - Vibration generating device and oral hygiene device using the same - Google Patents

Abstract

(57) [Abstract] A vibration generator and an oral hygiene device using the same are provided, which are inexpensive to manufacture and capable of transmitting vibrations efficiently, and which comprise a rotating body (22) attached to the rotating shaft (21) of an electric motor (14), an output shaft (11) elastically supported via a resonance pin (25) so as to be able to slightly swing, a driving magnetic body (23) attached to the rotating body (22), and a driven magnetic body (31) attached to the output shaft (11) facing the driving magnetic body (23) but not in contact with it, and the driving magnetic body (23) and the driven magnetic body (31) are constructed of permanent magnets, and the output shaft (11) is vibrated at high speed by a fluctuating magnetic field generated between the two magnetic bodies (23, 31) as the rotating body (22) rotates.

Description

[Detailed Description of the Invention] Vibration Generator and Oral Hygiene Device Using the Same Technical Field The present invention relates to a vibration generator that generates vibrations using an electric motor and an oral hygiene device using the same.

BACKGROUND ART For example, electric toothbrushes are known as oral hygiene devices. They include a first type in which an eccentric weight is rotated by an electric motor to impart vibration to the replacement brush; a second type in which the rotational motion of the electric motor is converted to linear motion via a cam or other device, causing the replacement brush to reciprocate; and a third type, as described in JP-A-7-505069, in which direct current obtained from a battery or other source is converted to alternating current by an inverter and supplied to a coil, causing the replacement brush to vibrate due to the coil's alternating magnetic field.

The first type of electric toothbrush has a simple structure and can be manufactured inexpensively. However, because vibrations are transmitted to the replacement brush via a casing that houses the electric motor and battery, some of the vibrations are transmitted to the fingers via the casing, and the replacement brush bristles do not have sufficient amplitude. As a result, the replacement brush only serves as a supplement to manual brushing. Furthermore, because the replacement brush vibrates at the same frequency as the electric motor, it is difficult to change the frequency of the replacement brush.

The second type of electric toothbrush uses a cam or other mechanical device to convert the rotational motion of the electric motor into linear reciprocating motion, which can provide vibrations that more closely resemble those experienced during actual brushing. However, the structure is complex and expensive to manufacture, and the electric motor may be overloaded and damaged if a large load is applied to the replacement brush. Furthermore, increasing the reciprocating motion speed increases mechanical loss.

The third type of electric toothbrush can easily increase the frequency of the replacement brush to dramatically improve cleaning performance, but it requires an inverter, which increases manufacturing costs and power consumption.

The object of the present invention is to provide a vibration generator that can be manufactured inexpensively and is capable of efficiently transmitting high-speed vibrations, and an oral hygiene device using the same.

Disclosure of the Invention The vibration generator according to claim 1 comprises a rotor attached to the rotating shaft of an electric motor, a driving magnetic body attached to the rotor, an output member elastically supported to allow for minute oscillation, and a driven magnetic body attached to the output member facing the driving magnetic body without contacting it. At least one of the driving magnetic body or the driven magnetic body is composed of a permanent magnet or an electromagnet, and the output member is vibrated by a fluctuating magnetic field generated between the two magnetic bodies as the rotor rotates.

Therefore, when the rotating body is rotated by the electric motor, the driving magnetic body on the rotating body repeatedly faces the driven magnetic body on the output member, and the rotating motion of the rotating body is converted into vibration of the output member by the varying magnetic field acting between the driving magnetic body and the driven magnetic body, causing the output member to vibrate in accordance with the rotation speed of the electric motor.

As described in claim 2, it is preferable that the driving magnetic body and the driven magnetic body are constructed of permanent magnets or electromagnets, with the same poles of both magnetic bodies facing each other. In other words, a mutually repulsive force acts between the two magnetic bodies, so that even if there is some play in the support of the rotating body or output member, the driving magnetic body and the driven magnetic body will not come into close contact with each other.

As described in claim 3, the frequency of the varying magnetic field may be set to the resonant frequency of the combination of the output member and a member attached to the output member that vibrates together with the output member. In this case, the combination will vibrate greatly due to resonance with the varying magnetic field acting between the driving magnetic body and the driven magnetic body.

As described in claim 4, an adjustment means may be provided for adjusting the distance between the driving magnetic body and the driven magnetic body. In this case, the amplitude is changed by adjusting the distance between the two magnetic bodies with the adjustment means. Specifically, increasing the distance between the two magnetic bodies weakens the vibration of the output member, and decreasing the distance between the two magnetic bodies strengthens the vibration of the output member.

As described in claim 5, the driving magnetic body may be fixed eccentrically from the rotating shaft of the electric motor, and the driven magnetic body may be provided facing the rotational path of the driving magnetic body. This configuration makes it possible to easily generate a fluctuating magnetic field between the driving magnetic body and the driven magnetic body.

As described in claim 6, it is preferable to set the elastic support point of the output member at approximately the center of gravity of the combination of the output member and the member attached to the output member that vibrates together with the output member. With this configuration, the combination vibrates approximately at the center of gravity, and the rotational motion of the rotating body is efficiently converted into vibration of the output member.

As described in claim 7, the output member may be a shaft whose distal end is coaxial with the rotary shaft of the electric motor and whose intermediate portion is bent proximally from the elastic support point so that the driven magnetic body fixed to the proximal end faces the rotational path of the driving magnetic body. In this case, the output member, the rotary body, and the electric motor can be configured compactly in the radial direction of the rotary shaft. Furthermore, the distal end of the shaft serving as the output member will vibrate significantly.

As described in claim 8, two permanent magnets may be provided as the driving magnetic body and one permanent magnet as the driven magnetic body. In this case, the output member vibrates at a frequency twice the rotational frequency of the electric motor.

An oral hygiene device according to claim 9 comprises an oral hygiene implement detachably attached directly or indirectly to an output member of the vibration generator according to any one of claims 1 to 8.

That is, an oral hygiene tool can be attached directly or indirectly to the output member of the vibration generator according to any one of claims 1 to 8 to brush teeth, clean between teeth, or massage gums.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal cross-sectional view of an electric toothbrush according to the present invention. FIG. 2 is a longitudinal cross-sectional front view of the main components of the electric toothbrush. FIG. 3 is a diagram of the overall configuration of the drive unit of the electric toothbrush. FIG. 4 is a longitudinal cross-sectional view of the upper half of the electric toothbrush. FIG. 5 is a longitudinal cross-sectional view of the lower half of the electric toothbrush. FIG. 6 is a longitudinal cross-sectional view of the electric toothbrush near the adjustment ring. FIG. 7 is a perspective view of the adjustment ring of the electric toothbrush. FIG. 8 is an explanatory diagram of adjusting the vibration intensity of the electric toothbrush. FIG. 9 is a longitudinal cross-sectional view of the output shaft near an electric toothbrush according to another embodiment, in which the output shaft configuration is partially modified. FIG. 10(a) is a longitudinal cross-sectional view of the output shaft near an electric toothbrush according to another embodiment, and FIG. 10(b) is an explanatory diagram showing the brush movement of the electric toothbrush. FIG. 11 is a longitudinal cross-sectional view of the output shaft near an electric toothbrush according to another embodiment. FIG. 12 is a longitudinal cross-sectional view of the output shaft near an electric toothbrush according to another embodiment. 13(a) is a front view of the output shaft and its vicinity of an electric toothbrush according to another embodiment, and FIG. 13(b) is a partially cutaway side view of the output shaft and its vicinity of the electric toothbrush. FIG. 14 is a side view of an interdental cleaning tool that can be attached to the vibration generator of the present invention. FIG. 15 is a side view of interdental floss that can be attached to the vibration generator. FIG. 16 is a side view of a tooth surface cosmetic finishing tool that can be attached to the vibration generator. FIG. 17 is a side view of a gum massager that can be attached to the vibration generator. FIG. 18 is a side view of a nail file that can be attached to the vibration generator. FIG. 19 is a side view of a shoulder tapper that can be attached to the vibration generator. FIGS. 20(a), (b), and (c) are perspective views of a face massager that can be attached to the vibration generator. FIG. 21 is a vertical cross-sectional view of a cleaning device incorporating the vibration generator of the present invention. FIG. 22 is a vertical cross-sectional view of a cleaning device according to another embodiment.

Best Mode for Carrying Out the Invention The following describes an embodiment of the present invention with reference to the drawings.

In this embodiment, the present invention is applied to a vibration generator for an electric toothbrush.

As shown in Figures 1 and 2, the electric toothbrush 1 basically comprises a vibration generator 10 and a replacement brush 2 detachably attached to an output shaft 11 serving as an output member of the vibration generator 10.

As shown in FIGS. 1 to 8, the vibration generator 10 includes a generally cylindrical casing 12. An electric motor 14 and a battery 15 are housed and supported in the lower half of the casing 12 via a holder member 13 that can be separated into upper and lower halves, allowing them to move vertically.

An adjustment ring 16 is fitted liquid-tightly to the lower end of the casing 12 via multiple claws 16a, preventing it from moving up and down but allowing it to rotate freely. A threaded portion 17 is formed near the lower end of the holder member 13, and the middle portion of the threaded portion 17 is threadedly engaged with the adjustment ring 16. In other words, the holder member 13 is restricted from moving up and down within the casing 12 via the adjustment ring 16, and is assembled to the casing 12 so that the position of the holder member 13 within the casing 12 can be finely adjusted up and down by rotating the adjustment ring 16, as shown in Figures 5 and 8. The holder member 13 and adjustment ring 16 constitute an adjustment means.

A cap member 18 is threaded onto the threaded portion 17 of the holder member 13, and the lower end of the casing 12 is liquid-tightly closed via the cap member 18 with a packing 33 (see Figure 6).

The holder member 13 is provided with wiring for supplying power to the electric motor 14, and a reed switch 19 is interposed in the wiring. By sliding a switch button 20 provided on the outer periphery of the casing 12, the electric motor 14 can be switched on and off.

A roughly disk-shaped rotor 22 is attached to the rotary shaft 21 of the electric motor 14. The rotor 22 has four mounting holes with open tops formed at equal intervals around its circumference, and a driving magnetic body 23 made of a permanent magnet is attached to each of these four mounting holes.

A pair of front and rear notches 24 are formed at the upper end of the casing 12, and a resonating pin 25, consisting of a torsion bar extending in the front-to-rear direction, is provided transversely within the casing 12 near its upper end as a support member. Flat plate-shaped fixing portions 25a are formed at both ends of the resonating pin 25, and the fixing portions 25a are fitted into the notches 24, thereby non-rotatably attaching the resonating pin 25 to the casing 12. A cap member 28 is fitted and fixed to the upper end of the casing 12, sandwiching the outer periphery of a washer 26 and a sealing film 27. The resonating pin 25 is fixed to the casing 12 via the cap member 28 and immovable in the vertical direction. A boss 29 is formed midway along the length of the resonating pin 25, and the output shaft 11, extending vertically, is inserted and fixed through the boss 29. The output shaft 11 is attached to the casing 12 via the resonating pin 25, allowing slight left-to-right swing, as shown by the arrow in FIG. 2 . The reference numeral 32 denotes a cover member for the output shaft 11. The cover member 32 is made of a resilient material such as synthetic resin or synthetic rubber, and is designed to prevent strong impacts caused by vibrations even when it hits the teeth.

The output shaft 11 extends upward, fluid-tightly penetrating the sealing membrane 27, and a replacement brush 2 is removably attached to its upper end. The lower half of the output shaft 11 is gently bent backward in a crank-like manner so that its lower end faces the front of the rotational path of the driving magnetic body 23, and a mounting fixture 30 is fixed to the lower end of the output shaft 11. A mounting hole with an open bottom is formed in the lower half of the mounting fixture 30, and a driven magnetic body 31 is assembled in this mounting hole so that it faces the driving magnetic body 23 with a small gap between them.

The driven magnetic body 31 and the driving magnetic body 23 are made of permanent magnets or electromagnets, and the magnetic bodies 23, 31 are respectively attached to the rotating body 22 and the mounting fixture 30 with like poles facing each other. Because four driving magnetic bodies 23 and one driven magnetic body 31 are used, the output shaft 11 vibrates at a frequency four times the rotational speed of the electric motor 14. However, the driven magnetic body 31 and the driving magnetic body 23 may also be attached with opposite poles facing each other, or with like poles and opposite poles facing each other alternately. Furthermore, at least one of the driving magnetic body 23 or the driven magnetic body 31 may be made of a ferromagnetic material that can be attracted to a magnet, such as iron, nickel, cobalt, or an alloy of these metals.

Furthermore, the number of driving magnetic bodies 23 and driven magnetic bodies 31 may be set arbitrarily. Furthermore, when a plurality of driven magnetic bodies 31 and a plurality of driving magnetic bodies 23 are provided, the pitch between adjacent driven magnetic bodies 31 can be set to an integer multiple of the pitch between adjacent driving magnetic bodies 23, allowing a plurality of driven magnetic bodies 31 to simultaneously face the driving magnetic body 23, and enabling a large force to be applied to the output shaft 11.

Regarding the replacement brush 2, as shown in FIGS. 1 and 2, a bristle base 4 is provided with a brush 3 attached thereto. The bristle base 4 has a fitting hole 5 into which the upper end of the output shaft 11 fits. By fitting the upper end of the output shaft 11 into the fitting hole 5 and engaging the retaining pin 11a of the output shaft 11 with the fitting slit 6 of the bristle base 4, the replacement brush 2 can be securely fastened to the output shaft 11.

The shape and mass of the combined assembly of the output shaft 11, mounting fixture 30, driven magnetic body 31, and replacement brush 2—i.e., the vibrating components—are set so that the resonant frequency of this combined assembly is approximately the same as the frequency of the fluctuating magnetic field generated between the magnetic bodies 23 and 31, as described below. Furthermore, elastically supporting this combined assembly at approximately the center of gravity with a resonance pin 25 is preferable for efficient vibration of the replacement brush 2.

Next, the operation and effects of the electric toothbrush 1 will be described.

When the switch button 20 is turned on, the rotor 22 rotates, causing the four driving magnetic bodies 23 attached to the rotor 22 to sequentially face the driven magnetic bodies 31. As the driving magnetic bodies 23 approach the driven magnetic bodies 31, a fluctuating magnetic field is generated, increasing the repulsive force (or attractive force if opposite poles are facing each other) between the two magnetic bodies 23 and 31. This fluctuating magnetic field converts the rotational motion of the rotor 22 into vibration of the output shaft 11, causing the replacement brush 2 to vibrate back and forth around the resonance pin 25 at a frequency four times the rotational frequency of the rotor 22. Furthermore, by rotating the adjustment ring 16 to adjust the distance between the driving magnetic bodies 23 and the driven magnetic bodies 31 between L1 and L2, as shown in Figures 5 and 8, the strength of the magnetic field acting between the magnetic bodies 23 and 31 can be adjusted, thereby adjusting the vibration strength. This allows the replacement brush 2 to vibrate at an appropriate strength while brushing teeth.

In this way, the output shaft 11 and the rotor 22 are kept in a non-contact state, and the output shaft 11 is vibrated by the rotational force of the rotor 22 via a fluctuating magnetic field. Therefore, even if a large load acts on the replacement brush 2 during brushing, the load on the electric motor 14 is not excessive. Furthermore, since mechanical vibration is not caused by gears or cams, no loud noise is generated, and since the casing 12 itself is not vibrated, there is no loss of vibration to the casing 12, and no discomfort to the fingers gripping the casing 12.

Furthermore, because the output shaft 11 is vibrated by a fluctuating magnetic field, gentle brushing is achieved without the problem of excessive force being applied to the gums or other areas. Furthermore, as brushing pressure increases, the driven magnetic body 31 moves toward the rotating shaft 21 of the electric motor 14, as shown by the phantom lines in Figure 1. This increases the distance between the driving magnetic body 23 and the driven magnetic body 31, weakening the vibration of the replacement brush 2 and further effectively preventing damage to the gums or other areas. However, since users may desire more forceful brushing when brushing pressure increases, it is also possible to position the driven magnetic body 31 so that it faces the center of the electric motor 14, as shown in Figure 9, and then, when brushing pressure increases, have the driven magnetic body 31 face the driving magnetic body 23, as shown by the phantom lines.

Furthermore, because the resonant frequency of the combined body is set to be approximately the same as the frequency of the fluctuating magnetic field generated between the two magnetic bodies 23, 31, it is possible to sufficiently increase the amplitude of the output shaft 11 (e.g., 4 mm in both directions), which allows for efficient vibration transmission and reduces magnetic loss.

Next, we will explain another embodiment in which the configuration of the electric toothbrush 1 is partially modified. Note that the same components as those in the previous embodiment are designated by the same reference numerals, and detailed descriptions thereof will be omitted.

(1) Instead of the resonating pin 25, an elastic member can be provided to elastically support the output shaft 11 so that it can freely rotate back and forth around its axis. As shown in FIG. 10(b), the vibration direction of the replacement brush 2 can be set to the rotational direction around the axis P of the bristle base 4. For example, as shown in FIG. 10(a), a vibration generator 70 can be employed in which the middle portion of the output shaft 11 is rotatably supported in the casing 12 via a pair of upper and lower bearing members 71, 72, via bearing devices 73 such as ball bearings or bearing metals made of synthetic resin or metal with low sliding resistance. A connecting member 74 is fixed to the output shaft 11 between the bearing members 71, 72 via a pin member 75 or the like. An elastic member 76, such as a torsion spring made of elastic metal or synthetic resin, is provided, with one end fixed to the connecting member 74 and the other end fixed to the bearing member 71, the bearing member 72, or the casing 12. However, axial movement of the output shaft 11 is restricted by an elastic member 76 or a bearing 73, or by forming a flange or the like at the middle of the output shaft 11 that abuts against the bearing members 71 and 72.

In this vibration generator 70, the brush 3 rotates back and forth as shown by the arrows in FIG. 10(b), so brushing by the rolling method can be easily performed simply by placing the brush 3 on the teeth.

Alternatively, as in the vibration generator 80 shown in FIG. 11, the output shaft 11 may be formed straight, the lower end of the output shaft 11 may be branched into two, and the driven magnetic bodies 31 may be attached to the lower ends of the two branched portions 81 so as to face the driving magnetic body 23.

In this case, uneven loads are prevented from acting on the bearing 73, preventing uneven wear of the bearing 73. Furthermore, the output shaft 11 rotates back and forth smoothly, enabling efficient torque transmission. Furthermore, since there is no need to incline the lower portion of the output shaft 11, the casing 12 can be made smaller in both the radial and longitudinal directions, resulting in a compact vibration generator 80.

(2) The vibration direction of the replacement brush 2 can also be set to the vertical direction. For example, as shown in FIG. 12, a vibration generator 40 may be provided in place of the resonating pin 25. A pair of upper and lower, approximately circular diaphragms 41 made of a highly elastic material such as rubber or synthetic resin, or a springy metal, may be provided. The output shaft 11 is inserted and fixed through the center of the diaphragm 41, and the output shaft 11 is guided vertically relative to the casing 12 via a slide bearing 42 above the diaphragm 41. In this case, only the vertical movement of the output shaft 11 due to the repulsive or attractive force acting between the driven magnetic body 31 and the driving magnetic body 23 is permitted via the diaphragm 41 and the slide bearing 42, causing the replacement brush 2 to vibrate vertically.

(3) As shown in FIG. 13, a cover portion 43 may be formed on the cap member 28 to fit over the output shaft 11, and the upper end of this cover portion 43 may be extended to the rear side of the replacement brush 2 to prevent damage to the mucous membrane in the oral cavity due to direct contact of the vibrating replacement brush 2 with the mucous membrane.

(4) Although the driving magnetic body 23 is attached to the upper surface of the rotor 22, the driving magnetic body 23 may be attached to the peripheral surface of the rotor 22, and the lower end of the output shaft 11 may be extended toward the outer periphery of the rotor 22 to provide the driven magnetic body 31 facing the driving magnetic body 23.

(5) Although not shown, when an electromagnet is used as the driven magnetic body 31, to prevent breakage of the lead wires used to energize the electromagnet, it is preferable to fix the lead wires from the electromagnet along the output shaft 11 and extend them from the resonance pin 25, which has the least movement, toward the casing 12. Furthermore, when an electromagnet is used as the driving magnetic body 23, current is applied using a sliding brush that slides against the rotor 22. Using electromagnets as the driven magnetic body 31 and the driving magnetic body 23 in this way allows for easy external control of drive/stop, and also allows for continuous adjustment of the strength of vibration by changing the magnetic force through adjustment of the voltage supplied to the electromagnet.

In this embodiment, the present invention is applied to an electric toothbrush 1. However, instead of the replacement brush 2, various functions can be imparted by detachably attaching an interdental brush 50 as shown in FIG. 14, an interdental floss 51 as shown in FIG. 15, a tooth surface cosmetic finisher 52 as shown in FIG. 16, a gum massager 53 as shown in FIG. 17, a nail file 54 as shown in FIG. 18, a shoulder massager 55 as shown in FIG. 19, or face massagers 56A, 56B, and 56C as shown in FIG. 20, etc., to the output shaft 11 of the vibration generator 10.

The present invention can also be similarly applied to various vibration generators other than those illustrated. For example, as shown in FIG. 21 , when applied to vibration generator 61 of cleaning device 60, an opening is formed in the bottom or side of cleaning tub 62, and a resilient membrane 62a made of silicone or the like is provided to close the opening. A driven magnetic body 31 is attached to membrane 62a, and a driving magnetic body 23 is disposed facing the driven magnetic body 31. Rotating driving magnetic body 23 together with rotor 22 using electric motor 14 vibrates membrane 62a, thereby cleaning small items such as eyeglasses immersed in cleaning tub 62. Reference numeral 63 denotes a basket for removing small items such as eyeglasses from cleaning tub 62. Alternatively, as shown in FIG. 22 , vibration generator 61A of cleaning device 60A may be configured such that driving magnetic body 23 is attached to the outer periphery of rotor 22 and a driven magnetic body 31 faces the driving magnetic body 23.

INDUSTRIAL APPLICABILITY The vibration generator of the present invention has a simple configuration consisting of a rotor with a driving magnetic body, an output member with a driven magnetic body, and an electric motor for rotating the rotor. A fluctuating magnetic field acts between the two magnetic bodies, thereby vibrating the output member. This reduces the manufacturing cost of the vibration generator while efficiently transmitting vibration to the output member. Furthermore, by changing the number of driving and driven magnetic bodies, the vibration frequency of the output member can be changed. Furthermore, because the output member is vibrated via a fluctuating magnetic field, even if a large load is applied to the output member, the electric motor will idle, preventing overload and damage.

The configuration described in claim 2 makes it possible to position the two magnetic bodies as close together as possible while preventing contact between them, and allows a large repulsive force to act on the driven body, thereby vibrating the output member strongly.

With the configuration as described in claim 3, the combined body resonates due to the varying magnetic field, so that the rotational motion of the rotor can be efficiently converted into vibration of the output member, and the amplitude of the combined body can be set large.

With the configuration as set forth in claim 4, the vibration of the output member can be increased or decreased by changing the distance between the two magnetic bodies with the adjustment means.

With the configuration described in claim 5, by appropriately setting the mounting position of the driving magnetic body relative to the rotating body, it is possible to easily generate a fluctuating magnetic field between the driving magnetic body and the driven magnetic body.

With the configuration as set forth in claim 6, the output member vibrates about approximately the center of gravity of the combined body, so that the rotational motion of the rotating body can be efficiently converted into vibration of the output member.

The configuration described in claim 7 allows the output member, rotor, and electric motor to be configured compactly in the radial direction of the rotary shaft, making it easy to realize a configuration suitable for handheld use. Furthermore, because the tip of the shaft serving as the output member vibrates strongly, it is possible to attach an oral hygiene tool or the like to the tip of the shaft and use it while vibrating it.

With the configuration as set forth in claim 8, it is possible to vibrate the output member at a frequency twice the rotational frequency of the electric motor.

According to the oral hygiene device of claim 9, an oral hygiene implement is attached to the output member of the vibration generating device of any one of claims 1 to 8, so that an inexpensive and high-performance oral hygiene device can be realized.

───────────────────────────────────────────────────── (Note) This publication is based on the publication published internationally by the International Bureau of Patents (WIPO). The effect of the international publication of the Japanese patent application (Japanese utility model registration application) related to this publication arises pursuant to Article 184-10, Paragraph 1 of the Patent Act (Article 48-13, Paragraph 2 of the Utility Model Act) and is unrelated to this publication.

Claims (9)

[Claims] 1. A vibration generator comprising: a rotor attached to the rotating shaft of an electric motor; a driving magnetic body attached to the rotor; an output member elastically supported to allow for minute oscillation; and a driven magnetic body attached to the output member facing the driving magnetic body but not in contact with it; wherein at least one of the driving magnetic body or the driven magnetic body is a permanent magnet or an electromagnet; and wherein the output member is vibrated by a fluctuating magnetic field generated between the two magnetic bodies as the rotor rotates. 2. The vibration generator according to claim 1, wherein the driving magnetic body and the driven magnetic body are composed of permanent magnets or electromagnets, with the same poles of both magnetic bodies facing each other. 3. A vibration generator according to claim 1 or 2, wherein the frequency of the varying magnetic field is set to the resonant frequency of the combination of the output member and a member attached to the output member so as to vibrate together with the output member. 4. The vibration generator according to any one of claims 1 to 3, further comprising an adjustment means for adjusting the distance between the driving magnetic body and the driven magnetic body. 5. A vibration generating device according to any one of claims 1 to 4, wherein the driving magnetic body is fixed eccentrically from the rotating shaft of the electric motor, and the driven magnetic body is provided facing the rotational path of the driving magnetic body. 6. The vibration generator according to any one of claims 1 to 5, wherein the elastic support point of the output member is set at approximately the center of gravity of a combination of the output member and a member attached to the output member to vibrate together with the output member. 7. A vibration generator according to any one of claims 1 to 6, wherein the output member is a shaft whose distal end is arranged coaxially with the rotary shaft of the electric motor and whose intermediate portion is bent proximally from the elastic support point so that the driven magnetic body fixed to the proximal end faces the rotational path of the driving magnetic body. 8. The vibration generator according to any one of claims 1 to 7, wherein two permanent magnets are provided as the driving magnetic body and one permanent magnet is provided as the driven magnetic body. 9. An oral hygiene device in which an oral hygiene implement is detachably attached directly or indirectly to the output member of the vibration generator according to any one of claims 1 to 8.