Abstract:
An electric toothbrush has bristle heads that rotate counter to each other. The toothbrush operates from a battery stored in the handle section of the toothbrush.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to the general art of toothbrushes, and to the particular field of electric toothbrushes. 
   2. Description of the Related Art 
   The use of manual toothbrushes has, of course, been known for many years. Indeed, the use of mechanical toothbrushes, typically those which are electrically driven, has been known for a number of years. The purpose, in any event, is to clean the teeth, usually with a toothbrush which comprises a plurality of bristles that are used in conjunction with a dentifrice. Very often, the dentifrice is mildly abrasive. 
   The dental profession has propounded, for many years, a technique known as the “Bass Technique” which, if properly performed, is said to achieve superior results in terms of cleaning one&#39;s teeth using a manual toothbrush. Essentially, the Bass Technique requires the user to position a manual toothbrush over a zone of the teeth, and then to use very short stokes so as to more or less vibrate the brush at that zone where the brush has been located. This short-stroke brushing should continue for a period of time—typically, twenty to forty strokes—so as to remove any foreign material from that zone. The brush is then repositioned and typically another twenty to forty short strokes are performed. Because each zone is very small, the Bass Technique can be very time-consuming. Moreover, since it is a requirement that the strokes be very short which, in turn, requires excellent muscle control, exercising the Bass Technique can be very tiring. 
   The theory is that, at the end of any given stroke, the bristles will flex so as to become oriented in such a manner that the ends of the bristles point generally away from the direction of the travel of the bristles across the teeth. However, at the beginning of the next stroke, in the opposite direction, the still-flexed bristles will then be pointed in the direction of the stroke and this may cause the bristle to chisel the foreign material away from the teeth for a moment before the bristle again begins to flex so as to sweep across the surface of the tooth in the zone where it is located. 
   However, a more efficacious manner for brushing teeth comprises a variation of the Bass Technique, whereby oscillatory movement is imparted to a toothbrush. Of course, such oscillatory movement is not capable of being executed manually. 
   Apart from the removal of leftover food particles and the like, a particular purpose for cleaning the teeth is to remove plaque build-up from the teeth. Typically, when using a manual toothbrush, plaque build-up is removed much more easily from the buccal surfaces of the teeth than from the lingual surfaces of the teeth, with relatively good foreign material removal from the occlusal surfaces of the teeth also being achieved. 
   One development that has occurred in respect of manual toothbrushes is the provision of twin-headed brushes, whereby the lingual and buccal surfaces of the tooth can be scrubbed using the bristles of the brush at the same time, with the same stroking action of the brush. 
   As to electric toothbrushes, most electric toothbrushes provide groups of bristles which are located in concentric circles, where the brush head thus provided is rotated or, more usually, it is reciprocally rotated. 
   While electric toothbrushes are more efficient than manual toothbrushes, there is a need for an electric toothbrush which is even more efficient than known electric toothbrushes. 
   PRINCIPAL OBJECTS OF THE INVENTION 
   It is a main object of the present invention to provide an electric toothbrush which is even more efficient than known electric toothbrushes. 
   SUMMARY OF THE INVENTION 
   These, and other, objects are achieved by a toothbrush that has two counter-rotating heads. The heads have bristles thereon and the counter-rotation improves the cleaning efficiency of the toothbrush. 

   
     BRIEF DESCRIPTION OF THE DRAWING FIGURES 
       FIG. 1  is an exploded perspective view of a toothbrush embodying the present invention. 
       FIG. 2  is a perspective view of a head portion of the toothbrush embodying the present invention and showing the counter-rotating dual heads of the toothbrush. 
       FIG. 3  is an end elevational view of the head shown in  FIG. 2 . 
       FIG. 4  is a detailed view of the counter-rotating axles used in the toothbrush. 
       FIG. 5  is a detailed view of the control switch on the body of the toothbrush. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Other objects, features and advantages of the invention will become apparent from a consideration of the following detailed description and the accompanying drawings. 
   Referring to the Figures, it can be understood that the present invention is embodied in a toothbrush  10  that achieves the above-stated objectives. 
   Toothbrush  10  comprises a hollow body  12  having a first portion  14  which includes a first end  16  which is a front end when body  12  is in use, a second end  18 , and a longitudinal axis  20  which extends between first end  16  and second end  18 . 
   First portion  14  further includes an outer surface  22 . 
   A screw thread  24  is defined on outer surface  22  of first portion  14  adjacent to second end  18 , and an interior volume  28  is defined in first portion  14 . 
   Body  12  further includes a second portion  40  which has a first end  42  which is located adjacent to second end  18  of first portion  14  when body  12  is in use. Second portion  40  further includes a second end  44  which is a rear end when body  12  is in use, and a longitudinal axis  46  which extends between first end  42  and second end  44 . Longitudinal axis  46  of second portion  40  is co-linear with longitudinal axis  20  of first portion  14  when body  12  is in use. 
   An inner surface  48  is defined on second portion  40  and a screw thread  50  is defined on inner surface  48  of the second portion  40  adjacent to first end  42  of the second portion  40 . Screw thread  50  on the second portion  40  is adapted to matingly engage screw thread  24  on first portion  14  when body  12  is in use. 
   A control switch  56  is mounted on first portion  14  and is used to control operation of toothbrush  10  in a manner known to those skilled in the art. 
   A power source, such as a rechargeable battery  60 , or the like, is located in second portion  40 . 
   First and second electric motors  70  and  72  are located on first portion  14  of body  12 . Each motor  70 ,  72  includes a drive shaft, such as drive shaft  74  of motor  70  and drive shaft  76  of motor  72 , that extends out of first end  16  of first portion  14 . 
   The electric motors  70 ,  72  are arranged to rotate the drive shafts  74 ,  76  in opposite directions when activated whereby drive shaft  74  of the first motor rotates clockwise in direction  80  with regard to longitudinal axis  20  of the first portion  14  of body  12  and drive shaft  76  of second motor  72  rotates counterclockwise in direction  82  with regard to longitudinal axis  20 . Each of the electric motors  70 ,  72  is electrically connected to control switch  56  to be electrically connected to the power source  60  via the control switch  56  to be activated when the control switch  56  is in an “on” condition as will be understood by those skilled in the art based on the teaching of the present disclosure. 
   A head unit  90  is mounted on first end  16  of the first portion  14  of body  12  when in use. Head unit  90  includes a C-shaped body section  92  which has a first end  94 , a second end  96 , and a longitudinal axis  98  which extends between first end  94  and second end  96  and which is co-linear with longitudinal axis  20  of first portion  14  of body  12  when in use. 
   Two holes  100  and  102  are defined through second end  96  of C-shaped body section  92 . 
   A neck section  120  is located on second end  96  of the C-shaped body section  92  and has a first end  124  unitary with second end  96  of the C-shaped body section  92 , a second end  126 , and a longitudinal axis  128  which extends between first end  124  and second end  126  and which is co-linear with longitudinal axis  98  of the C-shaped body section  92 . 
   First and second bores  130  and  132  extend through neck section  120  from first end  124  to second end  126 . The bores  130 ,  132  of the neck section  120  are located to receive the drive shafts  74 ,  76  of the first and second motors  70 ,  72  so those drive shafts  74 ,  76  will extend through the neck section  120  and through holes  100  and  102  defined through the second end  96  of the C-shaped section  92  and into the C-shaped body section  92 . 
   First and second cylindrical brushes  140  and  142  are mounted on respective drive shafts  74 ,  76  of the electric motors  70 ,  72  for rotation therewith. The cylindrical brushes  140 ,  142  are positioned in the C-shaped body section  92  and rotate in opposite directions as indicated by arrows  80 ′ and  82 ′ whereby, when motors  70  and  72  are activated, first cylindrical brush  140  rotates clockwise with regard to longitudinal axis  20  of first portion  14  of body  12  and second brush  142  rotates counterclockwise with regard to longitudinal axis  20  of the first portion  14  of the body  12 . 
   It is to be understood that while certain forms of the present invention have been illustrated and described herein, it is not to be limited to the specific forms or arrangements of parts as described and shown.