Abstract:
This invention relates to a battery powered electric toothbrush whose toothbrush head can vibrate laterally relative to the longitudinal axis of the toothbrush. The electric toothbrush comprises a handle containing a drive head eccentrically mounted to a motor shaft, a toothbrush head, and a sleeve intermediate the toothbrush head and the handle accommodating a swing arm. The swing arm has a head portion adjoining the toothbrush head pivotally attached in the forward end of the sleeve and has a tail portion provided with a transverse groove receiving the drive head. The head portion of the swing arm is bent to facilitate itself in contact within the forward end of the sleeve to minimize the impact on the motor power as a user presses the toothbrush head in a daily tooth cleaning. The toothbrush head is attachable, sealed, and secured to the drive portion with a flexible collar member.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates to electric toothbrushes, more particularly this invention is an improvement in the structure of a vibratory electric toothbrush whose head can vibrate laterally with respect to the longitudinal axis of the toothbrush.  
           [0002]    The benefit of using an electrically operated toothbrush to clean one&#39;s teeth is well known and has resulted in many innovations for electric toothbrushes. However, there have been not many innovations that are related to vibratory electric toothbrushes. A vibratory electric toothbrush generally comprises an electric motor, a mechanism that translates the motor movement into lateral vibratory movement, a toothbrush head mounted with plurality of bristles which deliver the vibratory movement onto user&#39;s teeth, a battery source, and a holder that holds all parts in a workable condition. When such a vibratory electric toothbrush is operated in a daily tooth cleaning, the toothbrush head and the bristles vibrate laterally with respect to the longitudinal axis of the toothbrush and moves approximately in a plane parallel to the tooth surface. Since the vibratory movement in the bristles can be adapted to the up-and-down movement along tooth gaps by a user holding the toothbrush horizontally in the tooth cleaning, this kind of electric toothbrush has an advantage of effectively cleaning in tooth gaps as well as cleaning the tooth surfaces with minimum hurting to the gums between user&#39;s teeth.  
           [0003]    U.S. Pat. No. 2,439,262 for a Power-Operated Mechanism discloses a hand manipulable device applicable to a vibratory electric toothbrush having a motion translating mechanism that translates rotary movement into rocking movement. The motion translating mechanism generally comprises a handle, a drive pin within the handle eccentrically extended to a driven shaft which is rotated by an external source during its operation, and a rock arm, pivotally attached in one end of the handle by a spheroidal bearing, having a working end portion projecting beyond the end of the handle to drive an applicable head and having a head at the other end provided with a transverse slot which receives the drive pin. When the mechanism is operated, the drive pin circulates and slides in the slot of the rock arm head and causes rocking movement in the arm. To restrict the rock arm to move in a plane, two spaced-apart guiding walls are provided for the rock arm. The mechanism is substantially simple in structure for translating the rotary movement into the rocking movement, but it is not sufficiently energy efficient since the mechanism employs the guiding walls and the spheroidal bearing that require several substantial contacts between static parts and moving parts which cause an additional energy loss due to the friction while the mechanism is operated. Hence it is not suitable for a portable electric toothbrush powered by a battery that needs better energy efficiency.  
           [0004]    U.S. Pat. No. 5,365,627 for a Stem Brush With Automatic Insertion System discloses a joint structure of a handle and a stem brush connection for an oral hygiene device. The structure generally comprises a pair of keys on a motor driven shaft in a handle, a radially extending flange on the base of the shaft, and a receiving portion in a stem brush which comprises a bore to receive the shaft, slots to receive the keys, a pair of ramping sleeves to guide the keys into the slots, and a pair of flexible arms having a recess to receive the flange on the base of the shaft. Although the system has an advantage of easy connection of the handle to the stem brush, it has a drawback of a gap left between the handle and the stem brush, which allows fluids to leak into the handle that degrades its hygienic function since bacteria may grow inside the handle.  
         BRIEF SUMMARY OF THE INVENTION  
         [0005]    One object of the present invention is to provide an improved electric toothbrush powered by battery that can generate lateral vibratory movement in the toothbrush head with respect to the longitudinal axis of the toothbrush. The mechanism generally comprises a toothbrush head and a swing arm pivotally attached in the forward end of a sleeve whose other end is longitudinally attached to a toothbrush handle. The swing arm comprises a tail portion and a head portion and an elongated middle portion intermediate the tail portion and the head portion. The tail portion of the swing arm has a transverse groove with an elongated opening to receive a drive head mounted eccentrically to the motor shaft aligned within the toothbrush handle; and the head portion extending to the toothbrush head has a transverse bore penetrating therein to receive a pivotal pin for the pivotal attachment of the swing arm to the forward end of the sleeve. As an electric toothbrush with this structure is operated, the drive head circulates in a plane approximately perpendicular to the axis of the motor shaft and slides in the transverse groove of the swing arm; and the drive head is able to slide freely in the transverse groove in the lengthwise direction of the transverse groove opening without causing the swing arm to move, but pushes back and forth within the transverse groove in the other direction perpendicular to the first said direction, which causes the swing arm and the toothbrush head to vibrate laterally or to swing with the pivot pin as a fulcrum.  
           [0006]    Another object of the invention is to provide an electric toothbrush that is simple in construction and effective in transforming electric energy into useful vibratory movement in the toothbrush head. The structure of the head portion of the swing arm in the present invention is invented for two major working characteristics: first, the head portion of the swing arm is bent from the longitudinal axis thereof to cause the toothbrush head to be inclined from the longitudinal axis of the swing arm, which is desirable in cleaning user&#39;s back teeth; secondly, there is a lateral prominent point portion on the lower part of the head portion, distal from the toothbrush head. This prominent point portion is in contact with the inner wall proximal thereto in the forward end of the sleeve when a user presses the bristles in the toothbrush head against teeth as in a daily tooth cleaning. The contact helps to dissipate the force generated by the user&#39;s pressing of the bristles against teeth with minimum impact on the motor power.  
           [0007]    Still another object of the invention is to provide an electric toothbrush having a toothbrush head that is attachable, secured, and sealed to a drive portion. The toothbrush head in this invention is attachable to the drive portion and is secured by a flexible collar member. The toothbrush head has a base portion mounted with plurality of bristles and a neck portion extended downward to the base portion. A recess with an opening at the free end of the neck portion is provided within the toothbrush head to receive an extension in the head portion of the swing arm. An annular recess is transversely positioned on the neck portion to receive an annular inward projection in the collar member for the secured attachment of the toothbrush head to the drive portion. The collar member also serves as a waterproof means to prevent liquids from leaking into the drive portion by covering the joint gap between the toothbrush head and the end of the drive portion adjoining the toothbrush head. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]    [0008]FIG. 1 is a front plan view of a vibratory electric toothbrush according to the present invention;  
         [0009]    [0009]FIG. 2 is a side sectional view of the same vibratory electric toothbrush taken along the plane II-II of FIG. 1;  
         [0010]    [0010]FIG. 3 is an enlarged perspective view of an attachable toothbrush head of the same vibratory electric toothbrush shown in FIG. 2;  
         [0011]    [0011]FIG. 4 is an enlarged perspective view of a swing arm of the same vibratory electric toothbrush shown in FIG. 2;  
         [0012]    [0012]FIG. 5 is an enlarged cross sectional view of the same vibratory electric toothbrush taken along the plane V-V of FIG. 2;  
         [0013]    [0013]FIG. 6 is an enlarged cross sectional view of the same vibratory electric toothbrush taken along the plane VI-VI of FIG. 2;  
         [0014]    [0014]FIG. 7 is an enlarged perspective view of a sleeve of the same vibratory electric toothbrush shown in FIG. 2;  
         [0015]    [0015]FIG. 8 is an enlarged perspective view of a collar member with a small portion being broken away of the same vibratory electric toothbrush shown in FIG. 2.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0016]    [0016]FIGS. 1 and 2 shows a preferred embodiment of the present invention of a vibratory electric toothbrush which comprises a toothbrush head  1 , a swing arm  33 , a sleeve  45 , a collar member  10 , and a handle portion  80  generally included within an elongated case of two covers  70  and  71  preferably made of plastic material and secured by screws  73 . Within the handle portion  80  are an electric motor  75  whose motor shaft  65  is in alignment therein, a disk member  61  having a drive head  60  and a bore at its center tightly receiving the motor shaft  65 , an electric switch  76 , a rechargeable battery pack  77 , charging leads  78 , and electric wires  79  connected in a workable condition well known in the art.  
         [0017]    The sleeve  45  is an elongated hollow body that has a forward end  46  holding the swing arm  33  by a pivotal pin  20  and has a base portion  51  to be attached uprightly to the handle portion  80 . The swing arm  33  disposed in the sleeve  45  is an elongated body having a head portion  25  at one end thereof and a tail portion  35  at the other end thereof The swing arm  33  is pivotally attached in the head portion  25  thereof to the forward end  46  of the sleeve  45  by a pivotal pin  20 . The pivotal pin  20  is preferably threaded on the front head thereof, as indicated by the reference numeral  21 , to secure the attachment thereof An extension  26  in the head portion  25  of the swing arm  33  projects beyond the forward end  46  of the sleeve  45  and is received by a recess  7  in the toothbrush head  1 . The tail portion  35  of the swing arm  33  is provided with a transverse groove  38  that receives the drive head  60 . The drive head  60  generally in thin cylindrical form is extended vertically and eccentrically to the disk member  61  which is mounted vertically at the center thereof onto the motor shaft  65 .  
         [0018]    A collar member  10  preferably made of rubber covers over the joint gap between the forward end  46  of the sleeve  45  and the toothbrush head  1  for both sealing the joint gap and securing the toothbrush head  1  to the sleeve  45 .  
         [0019]    The toothbrush head  1 , best see in FIG. 3, which is detachable from the vibratory electric toothbrush has a base portion  3  mounted with plurality of bristles similar to the head portion of a manual toothbrush, an annular flange  4  developed longitudinally from the base portion  3  with a diameter matching the width of the base portion  3 , and a neck portion  5  extended downward to the annular flange  4  with a cross dimension smaller than the diameter of the flange  4 . An annular recess  6  is transversely positioned on the surface of the neck portion  5 . The toothbrush head  1  is provided with another recess  7  in alignment therein with an opening at the free end  8  of the neck portion  5 .  
         [0020]    The swing arm  33 , best see in FIG. 4, has a head portion  25 , a tail portion  35 , and a rod  34  attached to both the head portion  25  at one end thereof and the tail portion  35  at the other end thereof. The rod  34  is an elongated body, which provides a longitudinal axis of the swing arm  33 .  
         [0021]    The head portion  25  of the swing arm  33  has an extension  26  with a suitable dimension that is snugly contained in the recess  7  in the toothbrush head  1 , a spherical portion  31 , and a bend cylindrical portion  27  extending at one end thereof to the extension  26  and at the other end thereof to the spherical portion  31 . The bend cylindrical portion  27  has a cross dimension approximately equal to that of the neck portion  5  of the toothbrush head  1 . The head portion  25  is bent laterally approximately in the middle of the bend cylindrical portion  27 . A bore  28  penetrating transversely through the body of the bend cylindrical portion  27  is positioned approximately at the middle of the bending thereof and is in alignment within the same. A bearing means or bushing  29  with suitable length is placed in the bore  28  of the head portion  25  by a pressed fit. The bearing means  29  snugly receives the pivotal pin  20 .  
         [0022]    The spherical portion  31  has a spherical exterior. A recess  32  in the head portion  25  with an opening on the spherical portion  31  is approximately positioned perpendicularly to and pointing to the middle of the bore  28  and has a depth reaching near but not touching the bore  28  to receive one end of the rod  34  by a pressed fit.  
         [0023]    A front point portion  30  is the most distal one from the opening of the recess  32  on the spherical portion  31  along the inner portion of the borderline  42  formed between the bend cylindrical portion  27  and the spherical portion  31 , see FIG. 5. The front point portion  30  is laterally prominent over the head portion  25  mainly due to the bending of the head portion  25  and facilitates itself in contact with the inner wall proximal thereto in the forward end  46  of the sleeve  45 .  
         [0024]    The head portion  25  of the swing arm  33  is preferably made first by molding with plastic material to make the desired portion without the bearing means  29  and then by press fitting the bearing means  29  into the bore  28 .  
         [0025]    The rod  34  of the swing arm  33  is an elongated body preferably made of stainless steel in tubular form or other materials having the working characteristic of effectively delivering the vibratory energy from the tail portion  35  to the head portion  25  through the rod  34 .  
         [0026]    The tail portion  35  has a base portion  41  that is transversely elongated and has a tapered portion  40  that is extended upwardly and symmetrically to the base portion  41  with generally a spherical surface on top thereof The tail portion  35  is provided with a transverse groove  38  in alignment within the base portion  41  with an elongated opening at the free end  39  thereof The transverse groove  38  has an elongated cross dimension as the elongated opening thereof at the free end  39  with a length corresponding to the throw of the drive head  60  and a width slightly larger than the diameter of the drive head  60 , see FIG. 6. The transverse groove  38  sufficiently receives the drive head  60  and allows the same movable freely therein along the long edges  37  thereon, or in the lengthwise direction of the elongated opening thereof A recess  36  with an opening at the top of the tapered portion  40  is provided in alignment within the same with a depth reaching near but not touching the transverse groove  38  to receive the other end of the rod  34  by a pressed fit. The tail portion  35  is preferably made of plastic material.  
         [0027]    The swing arm  33  is preferably assembled by first press fitting one end of the rod  34  into the recess  32  of the head portion  25  and then by press fitting the other end of the rod  34  into the recess  36  of the tail portion  35  with the alignment of the bore  28  being parallel to the long edges  37  on the transverse groove  38  in the tail portion  35 .  
         [0028]    The extension  26  in the head portion  25  of the swing arm  33  is inclined with respect to the longitudinal axis of the swing arm  33 . This inclination of the extension  26  in present embodiment is caused by the bending of the head portion  25  and results in bowing down in the toothbrush head  1  toward the tail portion  35  of the swing arm  33 .  
         [0029]    The sleeve  45 , best see in FIG. 7, is hollow and has a base portion  51 , a tapered portion  50  extended upwardly to the base portion  51 , an intermediate portion  49  extended upwardly to the end having smaller cross dimension of the tapered portion  50 , and a forward end  46  extended upwardly to the intermediate portion  49 .  
         [0030]    The forward end  46  is enlarged outwardly and has a uniform hollow interior as that of the intermediate portion  49  which is hollow. The interior cross dimension of the forward end  46  of the sleeve  45  is only slightly larger than the overall cross dimension of the head portion  25  of the swing arm  33  to prevent other movement in the head portion  25 . A pair of diametric bores  47  and  48  penetrates transversely through the walls of the forward end  46  to receive the pivotal pin  20  on which the swing arm  33  is pivotally attached therein. The bore  48  is preferably threaded to receive the threaded front head  21  of the pivotal pin  20  for secured attachment of the same.  
         [0031]    The tapered portion  50  is hollow and has a larger dimension at one end that matches the base portion  51  and gradually becomes smaller toward the other end that matches the intermediate portion  49 . The base portion  51  is hollow with a suitable cross dimension that snugly receives the head portions  72  in the handle portion  80  and allows the swing arm  33  to swing freely therein. Two pairs of coaxial bores  52  transversely penetrate the base portion  51  to receive the screws  73  for securing the attachment of the sleeve  45  to the handle portion  80 . The sleeve  45  is preferably molded with plastic material and then threaded in the bore  48 .  
         [0032]    The collar member  10 , best see in FIG. 8, comprises two hollow cylindrical portions extended longitudinally to each other, an upper portion  11  covering the neck portion  5  of the toothbrush head  1  and a lower portion  13  covering over the forward end  46  of the sleeve  45 . The exterior of the upper portion  11  evenly matches the annular flange  4  of the toothbrush head  1 . To the inner surface of the upper portion  11  is extended inwardly and transversely an annular projection  12  that is snugly received by the annular recess  6  on the neck portion  5  of the toothbrush head  1 . The lower portion  13  has a beveled end  15  to smooth the edge to the intermediate portion  49  of the sleeve  45 . An annular recess  14  is positioned transversely in the inner wall of the lower portion  13  close to the upper portion  11  and receives the forward end  46  of the sleeve  45 . The upper portion  11  of the collar member  10  is preferably made to be inclined with respect to the lower portion  13  to match the inclination in the extension  26  of the swing arm  33 . The collar member is preferably made of flexible materials such as rubber.  
         [0033]    The vibratory electric toothbrush is preferably assembled in the following procedure. First, the middle portion including the sleeve  45  of the vibratory electric toothbrush is assembled by inserting the swing arm  33  into the sleeve  45  with the head portion  25  of the swing arm  33  being close to the forward end  46  of the sleeve  45  and the tail portion  35  being close to the base portion  51 , then the bore  28  in the head portion  25  of the swing arm  33  is aligned with the bores  47  and  48  in the forward end  46  of the sleeve  45 , and then the pivotal pin  20  is inserted into the bore  47  and pushed through the head portion  25  and finally tightened to the bore  48 ;  
         [0034]    Secondly, the handle portion  80  is assembled by placing in covers  70  and  71  with the electric motor  75  whose motor shaft is tightly attached with the disk member  61 , the rechargeable battery pack  77 , the electric switch  76 , the charging leads  78 , and electric wires  79  connected in a workable condition;  
         [0035]    Thirdly, the sleeve  45  attached with the swing arm  33  in the forward end  46  is attached to the handle portion  80  by inserting the head portions  72  of the handle portion  80  into the base portion  51  thereof with the transverse groove  38  in the swing arm  33  sufficiently receiving the drive head  60  in the disk member  61 . The attachment completes by tightening the covers  70  and  71  with the screws  73 ;  
         [0036]    And finally, the lower portion  13  of the collar member  10  is placed over the forward end  46  of the sleeve  45 , then the toothbrush head  1  is attached to the extension  26  of the swing arm  33  by inserting the neck portion  5  of the toothbrush head  1  snugly into the upper portion  11  of the collar member  10 . In the assembling, alignments are made to ensure that the extension  26  of the swing arm  33 , the upper portion  11  of the collar member  10 , and the toothbrush head  1  are all inclined in the same direction and that the face with the bristles  2  of the base portion  3  of the toothbrush head  1  bows down toward the handle portion  80  of the vibratory electric toothbrush.  
         [0037]    As the vibratory electric toothbrush is operated, the drive head  60  engaged in the transverse groove  38  of the swing arm  33  circulates in a plane approximately perpendicular to the longitudinal axis of the handle portion  80 . The circular motion of the drive head  60  is composed of two motion components perpendicular to each other. The first component parallel to the long edges  37  on the transverse groove  38  does not cause the swing arm  33  to move since the drive head  60  slides freely in the transverse groove  38  in the lengthwise direction of the same, but the second motion component causes the swing arm  33  to move back and forth generally in the direction perpendicular to the first motion component. Hence the toothbrush head  1  attached to the swing arm  33  vibrates or swings laterally with the pivotal pin  20  as a fulcrum while the motor shaft  65  rotates.  
         [0038]    When a user presses the bristles  2  in the toothbrush head  1  of the vibratory electric toothbrush against teeth as in a daily tooth cleaning, a force in the pressed direction exerts on the toothbrush head. This force, otherwise is harmful to the operation of the electric toothbrush, is dissipated mainly by the means of the contacting of the front point portion  30  on the head portion  25  of the swing arm  33  with the inner wall proximal to the same in the forward end  46  of the sleeve  45  with minimum impact on the motor power.  
         [0039]    Thus the invention has been described with the preferred embodiment being disclosed for illustrative purposes. It should be understood that modifications or variations in the embodiment may be made within the scope of the appended claims.