Abstract:
An electric toothbrush including a handle, a battery and a motor in the handle, a head, and a tuft carrier movably mounted on the head for oscillation about an axis. The tuft carrier also moves axially as the carrier oscillates. This three-dimensional motion is provided by a plurality of cams and a plurality of cam followers on the head and the tuft carrier. The cam followers engage the cams such that as the tuft carrier oscillates back-and-forth, the cam followers ride up and down over the cams consequently raising and lowering the tuft carrier with respect to the toothbrush head.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention relates to electric toothbrushes, and more particularly to an electric toothbrush with three-dimensional motion.  
         [0002]     Electric toothbrushes are well known and believed to increase plaque removal and prevent gum recession. Conventional electric toothbrushes include an elongated body with a handle at one end and a head at the other end. The head end supports a cylindrical tuft carrier containing a number of tufts of bristles. The tuft carrier is provided with a back-and-forth reciprocating and oscillating motion a by drive shaft and motor located within the body of the toothbrush. The drive shaft rotates about a longitudinal axis and includes an eccentric tip that engages a slot in the side wall of the tuft carrier so that the tuft carrier oscillates as the tip rotates.  
         [0003]     In an effort to improve the cleaning effect of electric toothbrushes, manufacturers are now attempting to develop tuft carriers with three-dimensional motion, the third dimension being generally perpendicular to the oscillating dimensions. For example, U.S. Pat. No. 5,974,613 issued Feb. 19, 2002 to Fattori discloses a tuft carrier that is pivotally mounted on an angled drive shaft. The drive shaft extends through a lower portion of the tuft carrier, so that tuft carrier pivots back and forth as the drive shaft rotates. U.S. Pat. No. 6,347,425 issued Nov. 2, 1999 to Herzog discloses a drive shaft with an eccentric tip that engages a hole in the side wall of the tuft carrier. The tuft carrier pivots back and forth within a socket as the shaft rotates. While these and other designs provide their respective electric toothbrushes with some degree of three-dimensional motion, a significant amount of additional manufacturing time and labor is required to produce these specially made drive shafts and tuft carriers.  
         [0004]     Accordingly, manufacturers in this competitive market are continually searching for simpler and more cost-effective ways to provide electric toothbrushes with three-dimensional motion.  
       SUMMARY OF THE INVENTION  
       [0005]     The aforementioned problems are overcome by the present invention wherein three-dimensional motion is produced by simply molding cooperating features into the head and tuft carrier of a electric toothbrush to provide movement in the axial direction as the tuft carrier oscillates. In the disclosed embodiment, the cooperating features are cams and cam followers. The cam engages the cam follower such that as the tuft carrier reciprocates back-and-forth the cam rides up and down over the cam follower, consequently raising and lowering the tuft carrier with respect to the toothbrush head.  
         [0006]     The present invention provides an efficient and cost effective means for providing an electric toothbrush with three-dimensional motion. The cams and cam followers that provide up-and-down motion can be molded integrally into the body and the tuft carrier of a conventional electric toothbrush.  
         [0007]     These and other objects, advantages, and features of the invention will be more fully understood and appreciated by reference to the detailed description of the current embodiments and the drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]      FIG. 1  is a perspective view of an electric toothbrush in accordance with the present invention.  
         [0009]      FIG. 2  is an exploded view of the electric toothbrush.  
         [0010]      FIG. 3A  is a cross-sectional view of the tuft carrier in a first position.  
         [0011]      FIG. 3B  is a cross-sectional view of the tuft carrier in a second position.  
         [0012]      FIG. 4  is a perspective view of the bottom and side wall tuft carrier.  
         [0013]      FIG. 5  is an exploded view of an electric toothbrush according to a first alternative embodiment.  
         [0014]      FIG. 6  is a cross-sectional view of the first alternative embodiment.  
         [0015]      FIG. 7  is a bottom view of the tuft carrier according to the first alternative embodiment. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
     I. First Embodiment  
       [0016]     As shown in  FIG. 1 , the present invention is directed to an electric toothbrush that is generally designated  10 . The toothbrush includes an elongated body  12  having a handle  14  at one end, a head  16  at the other end, and a neck  18 . The head  16  includes a plurality of stationary bristles  20 , and supports a tuft carrier  22 , also having a plurality of bristles  24 . In operation, a switch  26  is activated by a user and an electric motor inside the body  12  provides motion to the tuft carrier  22 .  
         [0017]     Referring now to  FIG. 2 , the body  12  includes an upper body  28  and a lower body  30 . The upper body  28  and lower body  30  are preferably molded plastic, and are conventionally attached around a peripheral edge  32  of the upper body  28  and a corresponding edge  34  of the lower body  30  to create a hollow inner chamber  36 .  
         [0018]     The inner chamber  36  generally includes a battery  38  or multiple batteries, such as a AA form battery, and a cylindrical direct current motor  40  positioned within the handle  14 . The battery  38  is held in place by ribs  42  and  44 , and the motor  40  is held in place by ribs  46  and  48 . The ribs  42 ,  44 ,  46 , and  48  extend around the wall of the chamber  36  on both the upper body  28  and the lower body  30 . Ribs  44  and  46  are positioned in between the motor  40  and the battery  38 . A positive metal stamping  50  is disposed between the ribs  44  and  46  to connect one terminal  37  of the battery  38  to a first end  56  of the motor  40 . A negative metal stamping  52  is attached to the switch  26  through an elongated slot  54  in the upper body, such that when the switch  26  is moved along the slot  54 , the stamping  52  slides along the upper surface of the upper body  28  within the chamber  36 . The negative stamping  52  includes a flange  58  extending downwardly from a first end  60 , and a pair of fingers  62  extending downwardly from a point near the second end  64 . A sealing O-ring  66  is disposed between the switch  26  and the upper body  28 .  
         [0019]     A drive shaft  68  is attached to drive pin  70  extending from a second end  72  of the motor  40 . The drive shaft  68  is preferably a plastic rod, but may be made from a variety of materials. The pin  70  interfits with a hole  74  on a first end  76  of the drive shaft  68  and provides rotational motion to the drive shaft  68  when the motor  40  is activated. The drive shaft  68  is generally an elongated cylinder that extends through the inner chamber  36  from the neck  18  to the head  16  to define a longitudinal axis  88 . A central portion  78  of the shaft  68  is supported by a rib  80  within the neck  18 . A second sealing O-ring  82  is disposed about the central portion  78  within the rib  80 . A second end  84  of the drive shaft  68  includes an eccentric finger  86  that extends from the drive shaft at a slight angle with the axis  88  and engages a slot  112  in the tuft carrier  22  (described below in detail).  
         [0020]     The toothbrush head  16  includes a portion  90  of the upper body  28 , a portion  92  of the lower body  30 , and the tuft carrier  22 . The upper body portion  90  includes a plurality of stationary bristles  20 . The bristles  20  are generally conventional, and may be of various sizes, cross-sections and strengths and may extend from the upper portion  90  at various angles. Alternatively, or additionally, the toothbrush may include an elastomer extending from upper portion  90 . The lower body portion  92  extends past the upper portion  90  and includes an mounting surface  94 . The mounting surface  94  includes a generally circular wall  96  extending upwardly at the periphery of the surface  94 , a pair of stop pins  104 , and a receptacle  98  defining a hole  100  in the surface  94  and a wall extending upwardly from the center of the surface  94 . The receptacle  98  further includes a plurality of evenly spaced cams  102  extending around its upper surface. As illustrated, the present invention includes four cams, however, any desired number of cams  102  may be used.  
         [0021]     The tuft carrier  22  is generally circular to correspond to the shape of the peripheral wall  96  of the mounting surface  94 , and includes an upper surface  106 , a lower surface  108 , and a side wall  110 . The upper surface  106  includes a plurality of conventional bristles  24 . The side wall  110  includes a slot  112  that extends up a substantial portion of the side wall  110  from the lower surface  108 . The lower surface  108  is generally flat, but as shown in  FIG. 4  it includes a pair of stop fingers  113  extending down from either side of the slot  112 , a boss  114  extending from the center of the surface  108 , and a plurality of cam followers  116  evenly spaced about the boss  114 . The number of cam followers  116  generally correspond to the number of cams  102 , however, this is not necessary. The boss  114  is sized so that is can fit within the receptacle  98 . The cam followers  116  are sized to engage the cams  102  when the boss  114  is fitted within the receptacle  98 . A pin  118  with a head  120  extends through the receptacle  98  and the boss  114  to attach the tuft carrier  22  to the mounting surface  94 . The length of the pin  118  allows the tuft carrier to move a small distance up and down with respect to the mounting surface  94 . The pin  118  may be press fit into the boss  114 , or may be conventionally attached for example by a sonic weld. A spring (not shown) may be placed between the pin  118  and the lower body  92  of the head to keep the cams  102  and cam followers  116  in constant contact.  
         [0022]     In operation, the switch  26  is actuated within the slot  54  so that the flange  58  and the fingers  62  on the negative stamping  52  contact the second terminal  37  of battery  38  and the motor  40  to complete a circuit. The motor  40  then rotates the drive pin  70  and in turn the drive shaft  68  and the finger  86 . The finger  86  engages the slot  112  of the tuft carrier  22 , and moves up and down within the slot  112 . In turn, the tuft carrier  22  reciprocates back and forth along an arcuate path, while the cam followers  116  run up and down over the cams  102 . The tuft carrier  22  thereby raises and lowers as it reciprocates.  FIG. 3A  shows the actuation of the drive shaft  68  with the tuft carrier  22  in a first, lower position.  FIG. 3B  shows the actuation of the drive shaft  68  with the tuft carrier  22  in a second, raised position.  
       II. Second Embodiment  
       [0023]      FIGS. 5-7  show an alternative configuration of the drive shaft  68 ′ and tuft carrier  22 ′. In this configuration, the end  84 ′ of the drive shaft  68 ′ does not require the eccentric finger  86  of the previously disclosed embodiment. The drive shaft  68 ′ may terminate in a variety of shapes. As shown, the drive shaft  68 ′ terminates in a ball  86 ′. The drive shaft  68 ′ includes a central portion  78 ′ supported by a rib  80 ′ and a sealing O-ring  82 ′ as in the previously disclosed embodiment, but in this embodiment the rib  80 ′ is positioned substantially farther from the end  84 ′. The first end  76 ′ of the drive shaft  68 ′ engages with a drive cam  119 ′ attached to the motor  40 ′ so that the end  76 ′ of the drive shaft is eccentric with the axis  88 ′. The drive shaft  68 ′ is preferably steel, but may also be plastic or another suitable material. The tuft carrier  22 ′ includes a socket  112 ′ to accommodate the ball  86 ′. The remaining parts of the toothbrush are generally the same.  
         [0024]     In operation, when the switch  26  is actuated the cam shaft  119 ′ rotates and the first end  76 ′ of the drive shaft  68 ′ travels in a circular path about the axis  88 ′, causing the central portion  78 ′ of the shaft  68 ′ to pivot about a fulcrum created by the rib  80 ′. This causes the ball  86 ′ to travel eccentric to the longitudinal axis  88 ′ and reciprocates the tuft carrier  22 ′. The cams  102  and cam followers  116  operate in the same manner as the previously disclosed embodiment to provide the tuft carrier  22 ′ with a three-dimensional motion.  
         [0025]     The above descriptions are those of current embodiments of the invention. Various alterations and changes can be made without departing from the spirit and broader aspects of the invention, which are to be interpreted in accordance with the principles of patent law including the Doctrine of Equivalents.