Patent Publication Number: US-2011047729-A1

Title: Electric toothbrush

Description:
TECHNICAL FIELD 
     The present invention relates to an electric toothbrush. 
     BACKGROUND ART 
     Conventionally, an electric toothbrush is known that is configured to provide a vibration source within the body of a toothbrush for transmitting vibration to a brush (see Patent Documents 1 and 2). In such an electric toothbrush, for example, the techniques for improving the vibration transmission efficiency and producing resonance are used in order to efficiently vibrate the brush. 
     However, the above-described techniques tend to complicate the mechanism for transmitting vibration or make it difficult to reduce the dimension of the portion around the brush part. Accordingly, there is a need for a technique for more greatly vibrating a brush with less vibration in a vibration source. 
     PRIOR ART DOCUMENTS 
     Patent Documents 
     Patent Document 1: Japanese Registered Utility Model No. 3008856  
     Patent Document 2: Japanese Patent Laying-Open No, 10-192054 
     SUMMARY OF THE INVENTION 
     Problems to be Solved by the Invention 
     An object of the present invention is to provide an electric toothbrush capable of causing great vibration of a brush with less vibration by a vibration source. 
     Means for Solving the Problems 
     The present invention employs the following means for solving the above-described problems. 
     An electric toothbrush of the present invention includes a cylindrical case; and a vibration body having one end located within the case and an other end provided so as to protrude through an opening at a tip of the case to outside of the case and vibrating a brush located in proximity to the other end. The vibration body is provided with a vibration source on the one end side and has an outer peripheral surface supported in a position close to the vibration source side with respect to a midpoint in a longitudinal direction of the vibration body. 
     According to the present invention, the vibration body provided with a vibration source on the one end side has an outer peripheral surface supported in the position close to the vibration source side with respect to the midpoint in the longitudinal direction of the vibration body. Consequently, the vibration of the vibration source causes the vibration body to be vibrated in the position as a supporting point at which the vibration body is supported. Since, the distance from the supporting point to the other end is longer than the distance from the supporting point to the vibration source, the other end is vibrated more greatly than the vibration source. In other words, the vibration caused by the vibration source is amplified and transmitted to the other end side. 
     Thus, the vibration body according to the present invention allows the vibration of the vibration source provided on the one end side to be amplified and transmitted to the other end (in proximity to the brush), thereby allowing the brush to be greatly vibrated with less vibration caused by the vibration source. 
     It is preferable that the vibration source includes a motor fixed on the one end side of the vibration body and a weight attached to a rotation shaft of the motor and having a center of gravity in a position displaced from a rotation center of the rotation shaft. 
     Consequently, the vibration body vibrates so as to cause a pivotal movement of the one end side. 
     Furthermore, it is preferable that the weight is attached on the one end side of the motor. 
     It is preferable that a position restricting portion for restricting movement of the vibration body toward the one end side while permitting vibration of the vibration body is provided within the case. 
     Consequently, the vibration body can be prevented from moving toward the one end side. 
     It is preferable that a vibration damping structure for suppressing transmission of vibration of the vibration source to the case is provided within the case. 
     Consequently, the transmission of the vibration to the case can be suppressed. 
     It is preferable that the electric toothbrush includes an eccentric shaft including a shaft body and a weight fixed to the shaft body and having a center of gravity located in a position displaced from a shaft center; and a driving source rotating the eccentric shaft. The vibration body includes a hollow member, a bearing is provided in proximity to a tip on the other end side within the hollow member, and the eccentric shaft is supported by the bearing. 
     Consequently, since the eccentric shaft causes vibration on the other end side of the vibration body, the other end side of the vibration body can be further greatly vibrated. 
     It is preferable that the center of gravity of the weight of the eccentric shaft is located in a position displaced by approximately 180° from the center of gravity of the weight included in the vibration source with respect to the rotation center. 
     Consequently, the other end side of the vibration body can be effectively vibrated. 
     It is to be noted that the above-described configurations can be employed in every possible combination. 
     EFFECTS OF THE INVENTION 
     As described above, the present invention allows a brush to be greatly vibrated with less vibration caused by a vibration source. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a partial cutaway perspective view of an electric toothbrush according to the first embodiment of the present invention. 
         FIG. 2  is a partial enlarged view of  FIG. 1 . 
         FIG. 3  is a diagram of an internal configuration of the electric toothbrush according to the first embodiment of the present invention. 
         FIG. 4  is a schematic cross-sectional view showing a main component part of the electric toothbrush according to the first embodiment of the present invention. 
         FIG. 5  is a diagram for illustrating the state of vibration transmission in the electric toothbrush according to the first embodiment of the present invention. 
         FIG. 6  is a partial cutaway perspective view of an electric toothbrush according to the second embodiment of the present invention. 
         FIG. 7  is a schematic cross-sectional view showing a main component part of the electric toothbrush according to the second embodiment of the present invention. 
         FIG. 8  is a schematic cross-sectional view showing a main component part of an electric toothbrush according to the third embodiment of the present invention. 
         FIG. 9  is a schematic cross-sectional view showing the main component part of the electric toothbrush according to the third embodiment of the present invention. 
         FIG. 10  is a schematic cross-sectional view showing a main component part of an electric toothbrush according to the fourth embodiment of the present invention. 
         FIG. 11  is a diagram of an internal configuration of an electric toothbrush according to the fifth embodiment of the present invention. 
         FIG. 12  is a schematic cross-sectional view showing a main component part of the electric toothbrush according to the fifth embodiment of the present invention, 
         FIG. 13  is a diagram for illustrating the state of vibration transmission in the electric toothbrush according to the fifth embodiment of the present invention. 
         FIG. 14  is a schematic cross-sectional view showing a main component part of an electric toothbrush according to the sixth embodiment of the present invention. 
         FIG. 15  is a schematic cross-sectional view showing a main component part of an electric toothbrush according to the seventh embodiment of the present invention. 
         FIG. 16  is a schematic cross-sectional view showing the main component part of the electric toothbrush according to the seventh embodiment of the present invention. 
     
    
    
     MODES FOR CARRYING OUT THE INVENTION 
     The modes for carrying out the present invention will be hereinafter described in detail based on embodiments by way of example with reference to the accompanying drawings. It is to be noted that size, material, shape, relative arrangement and the like of the components described in the embodiments are not intended to limit the scope of the present invention thereto unless otherwise defined herein. In the following description, the terms “one end side” and “the other end side” represent the side opposite to that having a brush provided thereon (the side gripped by a hand during toothbrushing) and the side having a brush provided thereon, respectively, in the longitudinal direction of the electric toothbrush. 
     First Embodiment 
     Referring to  FIGS. 1 to 5 , an electric toothbrush according to the first embodiment of the present invention will be hereinafter described.  FIG. 1  is a partial cutaway perspective view of an electric toothbrush according to the first embodiment of the present invention.  FIG. 2  is a partial enlarged view of  FIG. 1 .  FIG. 3  is a diagram of an internal configuration of the electric toothbrush according to the first embodiment of the present invention.  FIG. 4  is a schematic cross-sectional view showing a main component part of the electric toothbrush according to the first embodiment of the present invention.  FIG. 5  is a diagram for illustrating the state of vibration transmission in the electric toothbrush according to the first embodiment of the present invention. 
     [Overall Electric Toothbrush] 
     Particularly referring to  FIGS. 1 to 4 , the configuration and the like of the overall electric toothbrush according to the first embodiment of the present invention will then be described. An electric toothbrush  100  according to the first embodiment of the present invention includes a cylindrical case  20  corresponding to a portion gripped by a hand during toothbrushing, a vibration body  30 , and a brush part  40  attached to vibration body  30 . Vibration body  30  has one end located within case  20  and the other end provided so as to protrude through an opening  20   a  at the tip of case  20  to the outside of the case. 
     Brush part  40  is attached so as to cover this vibration body  30 . Brush part  40  has a body part  41  which is made of a cylindrical member such that it can be attached to vibration body  30 . At the end of body part  41 , a brush  42  is provided. It is to be noted that this brush part  40  is consumable, and thus, configured to be attachable to and detachable from vibration body  30  in order to allow exchange of the part with a new one as appropriate. 
     Case  20  is provided inside with a battery (rechargeable battery)  50  serving as a power supply and a circuit board  60  performing drive control of a vibration source  10  described below. Furthermore, an annular support member  21  supporting the outer peripheral surface of vibration body  30  is provided at the inner peripheral edge of opening  20   a  of case  20 . In the present embodiment, an annular groove is formed at the outer periphery of vibration body  30  and the inner peripheral edge of support member  21  is fit into this annular groove. Consequently, vibration body  30  is supported and positioned by support member  21 . Furthermore, this support member  21  not only supports vibration body  30  but also performs a function as a seal for preventing water and the like from coming into case  20 . Accordingly, it is necessary to use a material having an appropriate hardness for a material of this support member  21  in order to achieve both of the supporting function and the waterproof function. Thus, in the present embodiment, an elastomer is employed as a material of support member  21 . Furthermore, as shown in  FIG. 3 , a wiring line L electrically connects between battery  50  and circuit board  60 , and between circuit board  60  and a motor  11  which is a component of vibration source  10 . 
     Vibration body  30  is formed of a cylindrical hollow member. Vibration body  30  includes a cylindrical portion  31  provided on its one end side and a tapered portion  32  integrally provided in cylindrical portion  31  and tapered toward the other end side. Furthermore, vibration source  10  is provided in cylindrical portion  31  on the one end side of vibration body  30 , Vibration source  10  includes motor  11  fixed in the state where it is inserted into cylindrical portion  31  and a weight  12  attached to the rotation shaft of motor  11 . In this case, weight  12  is configured to have the center of gravity in the position displaced from the rotation center of the rotation shaft of motor  11 . It is to be noted that weight  12  is provided on the one end side of motor  11 . 
     Furthermore, vibration body  30  is in contact with an annular member  22  fixed to the inner peripheral surface of case  20  and is restricted in movement toward the one end side in order to prevent the movement toward the one end side. In other words, this annular member  22  serves as a position restricting portion. In addition, since vibration body  30  is merely in contact with annular member  22 , vibration body  30  can be freely moved along the plane orthogonal to the shaft center (pivoting plane) in its longitudinal direction, which allows vibration (see  FIG. 4 . It is to be noted that annular member  22  is not shown in  FIGS. 1 to 3  for the sake of explanation.). Furthermore, vibration body  30  is supported at its outer peripheral surface by support member  21  as described above in the position close to the vibration source  10  side (the one end side) with respect to the midpoint in the longitudinal direction of vibration body  30 . 
     [Explanation of Operation of Electric Toothbrush] 
     Particularly referring to  FIGS. 4 and 5 , electric toothbrush  100  according to the first embodiment of the present invention will be hereinafter described. 
     When electric toothbrush  100  is powered on, the rotation shaft of motor  11  is rotated to cause rotation of weight  12  attached to this rotation shaft, As described above, weight  12  has the center of gravity in the position displaced from the rotation center of the rotation shaft of motor  11 . Accordingly, rotation of weight  12  produces a centrifugal force, which causes vibration body  30  to be vibrated such that the one end side is pivotally moved. 
       FIG. 5  schematically shows the state where vibration body  30  vibrates (pivots). The part indicated by an arrow P in  FIG. 5  corresponds to the part on one end of vibration body  30 , as indicated by an arrow P also shown in  FIG. 4 . Furthermore, a reference character X in  FIG. 5  shows a pivot diameter at one end of the central axis of vibration body  30  at the time when vibration body  30  is pivotally moved. Furthermore, the part indicated by an arrow S in  FIG. 5  corresponds to the part in vibration body  30  supported by support member  21 , as indicated by an arrow S also shown in  FIG. 4 . The part indicated by an arrow A in  FIG. 5  corresponds to the part on the other end of vibration body  30  as indicated by an arrow A also shown in  FIG. 4 . Furthermore, a reference character Y in  FIG. 5  shows a pivot diameter at the other end of the central axis of vibration body  30  at the time when vibration body  30  is pivotally moved. 
     The positional displacement of the part indicated by arrow S in vibration body  30  is prevented by support member  21 . Accordingly, the pivot diameter of the central axis in this part is theoretically zero. Vibration body  30  then pivotally moves in the state where the part S supported by this support member  21  is set as the center of the movement. During the pivotal movement, the positional relationship is maintained such that the one end and the other end of the central axis are displaced by 180 degrees from each other with respect to the pivot center axis. The ratio between a pivot diameter Y and a pivot diameter X is theoretically equal to the ratio between a distance L1 from the supported part S to part A on the other end and a distance L2 from the same part S to part P on the one end in vibration body  30  (Y:X L1:L2). 
     In the present embodiment, as described above, vibration body  30  is supported at its outer peripheral surface by support member  21  in the position close to the vibration source  10  side (the one end side) with respect to the midpoint in the longitudinal direction of vibration body  30 . Accordingly, assuming that L1&gt;L2, the result is Y&gt;X. 
     As described above, when the one end side of vibration body  30  is pivoted (vibrated) by vibration source  10 , the other end side of vibration body  30  can also be pivoted (vibrated). Consequently, brush part  40  attached to vibration body  30  is also vibrated. In particular, brush  42  can be greatly vibrated that is located near the other end pivoted (vibrated) most greatly in vibration body  30 . In this way, the vibration of vibration source  10  can be transmitted to brush  42  to allow brushing of teeth by placing brush  42  on the teeth. 
     Advantages of the Present Embodiment 
     As described above, in electric toothbrush  100  according to the present embodiment, vibration body  30  provided with vibration source  10  on its one end side is supported at its outer peripheral surface by support member  21  in the position close to the vibration source  10  side with respect to the midpoint in the longitudinal direction of vibration body  30 . Accordingly, the vibration of vibration source  10  causes vibration body  30  to be vibrated (pivoted in the present embodiment) in the position as a supporting point at which vibration body  30  is supported by support member  21 . Assuming that L1&gt;L2 as described above, the vibration on the other end of vibration body  30  is greater than that of vibration source  10 . In other words, the vibration by vibration source  10  is amplified and transmitted to the other end side. In this way, according to vibration body  30  in accordance with the present embodiment, vibration of vibration source  10  provided on the one end side can be amplified and transmitted to the other end (near brush  42 ), Therefore, brush  42  can be greatly vibrated with less vibration by vibration source  10 . 
     Furthermore, in vibration source  10  according to the present embodiment, weight  12  is provided on the one end side of motor  11 . Accordingly, weight  12  is disposed on the side corresponding to an open end of vibration body  30 , which leads to an advantage that the state where weight  12  is attached can be readily checked. Furthermore, when changing the manner of vibration, weight  12  can be changed and adjusted even after completion of assembly of vibration body  30 . Furthermore, the type of attached weight  12  can also be visually recognized. It is to be noted that weight  12  may be formed in the shape of a blade to produce airflow within case  20  for cooling the inside of case  20 . 
     Second Embodiment 
       FIGS. 6 and 7  each show the second embodiment of the present invention. The first embodiment as described above describes the case where a weight is provided on the one end side of the motor, whereas the present embodiment will describe the case where the weight is provided on the other end side of the motor. Since other configurations and operations are the same as those in the first embodiment, the same components are designated by the same reference characters, and the description thereof will not be repeated. 
       FIG. 6  is a partial cutaway perspective view of the electric toothbrush according to the second embodiment of the present invention.  FIG. 7  is a schematic cross-sectional view showing a main component part of the electric toothbrush according to the second embodiment of the present invention. 
     Also in an electric toothbrush  100   a  according to the present embodiment, a vibration source  10   a  includes a motor  11   a  fixed in the state where it is inserted into cylindrical portion  31  in vibration body  30  and a weight  12   a  attached to the rotation shaft of motor  11   a . The present embodiment is different from the above-described first embodiment only in that weight  12   a  is provided on the other end side of motor  11   a.    
     Also in electric toothbrush  100   a  according to the present embodiment, the rotation of weight  12   a  causes a pivotal movement of the one end side of vibration body  30 , in which case the operation similar to that in the above-described first embodiment is performed. Therefore, the effects similar to those obtained in the above-described first embodiment can be achieved also in the present embodiment. 
     Third Embodiment 
       FIGS. 8 and 9  each show the third embodiment of the present invention. The present embodiment describes the configuration in which a vibration damping body for suppressing transmission of vibration of the vibration body to the case is additionally provided between the vibration body and the annular member (member serving as a position restricting portion). Since other configurations and operations are the same as those in the first embodiment, the same components are designated by the same reference characters, and the description thereof will not be repeated. 
       FIGS. 8  and  FIG. 9  each are a schematic cross-sectional view showing a main component part of the electric toothbrush according to the third embodiment of the present invention. 
     As described in the first embodiment, case  20  has an inner peripheral surface provided with annular member  22  for restricting movement of vibration body  30  toward the one end side. This annular member  22  serves to restrict movement of vibration body  30  toward the one end side while permitting vibration of vibration body  30 . Although this annular member  22  permits vibration of vibration body  30 , the vibration of vibration body  30  is directly transmitted to annular member  22  when employing the configuration in which the movement of vibration body  30  is restricted by the structure that annular member  22  is in direct contact with vibration body  30 . Consequently, significant vibration may be transmitted to case  20  through annular member  22 . 
     The user feels uncomfortable when vibration occurs in case  20  gripped by a hand during toothbrushing. Accordingly, it is generally undesirable that case  20  is vibrated. Thus, the present embodiment employs the configuration in which a vibration damping body for suppressing transmission of the vibration of vibration body  30  to case  20  is provided between annular member  22  and vibration body  30 .  FIG. 8  shows an example in which a spring  23  is employed as a vibration damping body.  FIG. 9  shows an example in which a vibration energy absorber (for example, gel-like material)  24  is employed as a vibration damping body. It is to be noted that the vibration damping body is not limited thereto but may be any component that can absorb vibration energy. As described above, in the present embodiment, a vibration damping body is provided between annular member  22  and vibration body  30  to form a vibration damping structure for suppressing transmission of the vibration of vibration body  30  to case  20 . 
     As described above, in addition to the effects obtained in the above-described first embodiment, the present embodiment has an effect that vibration of case  20  can be suppressed. It is to be noted that the present embodiment shows the configuration in which a vibration damping body is provided so as to be in contact with cylindrical portion  31  in vibration body  30 , thereby suppressing transmission of vibration of vibration source  10  to case  20 . However, it is also possible to employ the configuration in which a vibration damping body is provided so as to be in direct contact with vibration source  10  (motor  11 ), thereby suppressing transmission of vibration of vibration source  10  to case  20 . 
     Fourth Embodiment 
       FIG. 10  shows the fourth embodiment of the present invention. The above-described third embodiment shows that a vibration damping structure is formed by providing a vibration damping body between the annular member and the vibration body, whereas the present embodiment shows that a vibration damping structure is formed by providing an annular member with a vibration damping function. Since other configurations and operations are the same as those in the first and third embodiments, the same components are designated by the same reference characters, and the description thereof will not be repeated. 
       FIG. 10  is a schematic cross-sectional view showing the main component part of the electric toothbrush according to the fourth embodiment of the present invention. As shown in the figure, the present embodiment provides a configuration in which an annular member  22   a  includes a plurality of conical protrusions  22   b  which protrude toward the other end side and have tips in contact with vibration body  30 . It is to be noted that these conical protrusions  22   b  are provided at regular intervals in the circumferential direction. Furthermore, annular member  22   a  according to the present embodiment is made of hard elastomer material and has a function of damping vibration by itself. Thus, in the present embodiment, annular member  22   a  itself has a function of damping vibration, to thereby form a vibration damping structure for suppressing transmission of the vibration of vibration body  30  to case  20 . 
     As described above, in addition to the effects obtained in the above-described first embodiment, the present embodiment also has an effect that vibration of case  20  can be suppressed as in the case of the third embodiment. It is to be noted that the present embodiment shows the configuration in which conical protrusions  22   b  in annular member  22   a  are provided so as to be in contact with cylindrical portion  31  in vibration body  30 , thereby suppressing transmission of vibration of vibration source  10  to case  20 . However, it is also possible to employ the configuration in which conical protrusions  22   b  in annular member  22   a  are provided so as to be in direct contact with vibration source  10  (motor  11 ), thereby suppressing transmission of vibration of vibration source  10  to case  20 . Furthermore, the present embodiment also shows the configuration in which a plurality of conical protrusions  22   b  are provided at regular intervals in the circumferential direction. However, the important requirement is to make it difficult to transmit the vibration of vibration source  10  to the annular member. Accordingly, the area coming into contact with vibration source  10  or vibration body  30  of the annular member only needs to be decreased. For example, it is also preferable to employ the configuration in which the annular member has annular protrusions protruding (each having a pointed tip) toward the other end side (annular protrusions provided concentrically with the annular member over the entire circumference) and the tip of each annular protrusion is in contact with vibration body  30  or vibration source  10 . 
     Fifth Embodiment 
       FIGS. 11 to 13  each show the fifth embodiment of the present invention. The present embodiment shows the configuration in which an eccentric shaft for directly vibrating the other end of the vibration body is additionally provided in the configuration in the above-described first embodiment. Since other configurations and operations are the same as those in the first embodiment, the same components are designated by the same reference characters, and the description thereof will not be repeated. 
       FIG. 11  is a diagram of an internal configuration of an electric toothbrush according to the fifth embodiment of the present invention.  FIG. 12  is a schematic cross-sectional view showing a main component part of the electric toothbrush according to the fifth embodiment of the present invention.  FIG. 13  is a diagram for illustrating the state of vibration transmission in the electric toothbrush according to the fifth embodiment of the present invention. 
     Also in an electric toothbrush  200  according to the present embodiment, as in the case of the above-described first embodiment, a vibration body  230  includes a cylindrical portion  231  and a tapered portion  232 , in which a vibration source  210  including a motor  211  and a weight  212  is provided in cylindrical portion  231  on the one end side of vibration body  230 . 
     Furthermore, an eccentric shaft  250  is provided in the present embodiment. This eccentric shaft  250  is configured to be rotated by motor  211 . In other words, in the present embodiment, motor  211  that is a component of vibration source  210  also serves as a driving source for rotating eccentric shaft  250 . It is to be noted that eccentric shaft  250  includes a shaft body  251  and a weight  252  fixed to shaft body  251  and having the center of gravity located in the position displaced from the shaft center. In this case, weight  252  is configured to have the center of gravity located in the position displaced by 180° from the center of gravity of weight  212  included in vibration source  210  with respect to the rotation center in terms of design. 
     Furthermore, in the present embodiment, a bearing  233  is provided near the tip on the other end side of hollow tapered portion  232  in vibration body  230 . Eccentric shaft  250  is fixed at its one end side to motor  211  and supported at the other end side by this bearing  233 . 
     When electric toothbrush  200  according to the present embodiment is powered on, the operation caused by vibration of vibration source  210  similar to that in the above-described first embodiment is performed. In the present embodiment, when electric toothbrush  200  is powered on, eccentric shaft  250  is also rotated. As described above, eccentric shaft  250  is provided with weight  252  having the center of gravity located in the position displaced from the shaft center. Accordingly, if eccentric shaft  250  is rotated in the state where the tip of eccentric shaft  250  is not supported by bearing  233 , eccentric shaft  250  is pivotally moved around the shaft center while eccentric shaft  250  itself rotates. Consequently, eccentric shaft  250  is rotated in the state where eccentric shaft  250  is supported by bearing  233 , which allows the operation to be performed in such a manner that the outer wall surface near the tip of eccentric shaft  250  repeatedly strikes against the inner wall surface of bearing  233  a number of times for a short time period. 
     When the above-described operation is performed, the portion around the other end of vibration body  230  provided with bearing  233  can be vibrated directly through bearing  233 . Then, when vibration body  230  is vibrated, the vibration can be transmitted to brush part  40 . 
     As described above, according to the present embodiment, the vibration of vibration source  210  can be amplified and transmitted to the other end (near brush  42 ) of vibration body  230 , and the portion around the other end of vibration body  230  can also be vibrated directly by eccentric shaft  250 . It is to be noted that a reference character Z shown in  FIG. 13  schematically shows the state where vibration body  230  is vibrated directly by eccentric shaft  250 . Therefore, electric toothbrush  200  according to the present embodiment allows the other end side of vibration body  230  to be further greatly vibrated as compared to each of the above-described embodiments. Furthermore, in the present embodiment, the center of gravity of weight  252  is located in the position displaced from the center of gravity of weight  212  included in vibration source  210  by 180° with respect to the rotation center in terms of design. Therefore, the other end side of vibration body  230  can be effectively vibrated without damping of the vibration caused by each of vibration source  210  and eccentric shaft  250 . 
     Sixth Embodiment 
       FIG. 14  shows the sixth embodiment of the present invention. The above-described fifth embodiment shows that a weight is provided on the one end side of the motor, whereas the present embodiment shows that a weight is provided on the other end side of the motor. Since other configurations and operations are the same as those in the fifth embodiment, the same components are designated by the same reference characters, and the description thereof will not be repeated. 
       FIG. 14  is a schematic cross-sectional view showing the main component part of an electric toothbrush according to the sixth embodiment of the present invention. 
     Also in the present embodiment, a vibration source  210   a  includes a motor  211   a  fixed in the state where it is inserted into cylindrical portion  231  in vibration body  230  and a weight  212   a  attached to the rotation shaft of motor  211   a . The present embodiment is different from the above-described fifth embodiment only in that weight  212   a  is provided on the other end side of motor  211   a.  It is to be noted that the present embodiment is identical to the above-described first embodiment in that the center of gravity of weight  252  of eccentric shaft  250  is located in the position displaced from the center of gravity of weight  212   a  included in vibration source  210   a  by 180° with respect to the rotation center in terms of design. 
     It is needless to say that the above-described configuration allows the effects similar to those obtained in the above-described fifth embodiment to be achieved also in the present embodiment. 
     Seventh Embodiment 
       FIGS. 15 and 16  each show the seventh embodiment of the present invention. The present embodiment shows the configuration in which a vibration damping body for suppressing transmission of vibration of the vibration body to the case is additionally provided between the vibration body and the annular member (member serving as a position restricting portion) in the configuration in the above-described fifth embodiment. Since other configurations and operations are the same as those in the fifth embodiment, the same components are designated by the same reference characters, and the description thereof will not be repeated. 
       FIGS. 15 and 16  each are a schematic cross-sectional view showing the main component part of the electric toothbrush according to the seventh embodiment of the present invention. 
     As in the third embodiment, the present embodiment employs the configuration in which a vibration damping body for suppressing transmission of the vibration of vibration body  230  to case  20  is provided between annular member  22  and vibration body  230 .  FIG. 15  shows an example in which spring  23  is employed as a vibration damping body.  FIG. 16  shows an example in which vibration energy absorber (for example, gel-like material)  24  is employed as a vibration damping body. It is to be noted that the vibration damping body is not limited thereto but may be any component that can absorb vibration energy. 
     As described above, in addition to the effects obtained in the above-described fifth embodiment, the present embodiment has an effect that the vibration of case  20  can be suppressed. It is to be noted that the present embodiment shows the configuration in which the vibration damping body is provided so as to be in contact with cylindrical portion  231  in vibration body  230 , thereby suppressing transmission of the vibration of vibration source  210  to case  20 . However, it is also possible to employ the configuration in which the vibration damping body is provided so as to be in direct contact with vibration source  210  (motor  211 ), thereby suppressing transmission of the vibration of vibration source  210  to case  20 . Furthermore, as shown in the above-described fourth embodiment, it is also possible to employ the configuration in which the vibration is suppressed by providing the annular member itself with a function of damping the vibration. 
     DESCRIPTION OF THE REFERENCE SIGNS 
       10 ,  10   a  vibration source,  11 ,  11   a  motor,  12 ,  12   a  weight,  20  case,  20   a  opening,  21  support member,  22 ,  22   a  annular member,  22   b  conical protrusion,  23  spring,  24  vibration energy absorber,  30  vibration body,  31  cylindrical portion,  32  tapered portion,  40  brush part,  41  body part,  42  brush,  50  battery,  60  circuit board,  100 ,  100   a  electric toothbrush,  200  electric toothbrush,  210 ,  210   a  vibration source,  211 ,  211   a  motor,  212 ,  212   a  weight,  230  vibration body,  231  cylindrical portion,  232  tapered portion,  233  bearing,  250  eccentric shaft,  251  shaft body,  252  weight, L wiring line.