Stroke transmission gear mechanism, and electric toothbrush having such a gear mechanism

Abstract

Electric toothbrushes have a replaceable head part having a brush head and a hand part provided with a drive motor for the brush. When a head part is pushed onto the hand part, a drive pin which performs an axial stroke motion is connected to the brush head. A gear mechanism in the head part transmits the stroke motion of the drive pin, for example in a stroke motion of the brush head, upon which a lateral tilting motion is superimposed. However, the stroke of the drive pin provided by some hand parts is not matched to the desired stroke of the brush head. Therefore, a stroke transmission gear mechanism is provided in the head part in the mechanical linkage between the drive pin and the brush head, the drive rod of the stroke transmission gear mechanism being connected to the drive pin, and the stroke transmission gear mechanism in particular is installed in such a way that a stroke reduction occurs. In this manner it is possible for the stroke supplied by the drive pin to be translated into a stroke that is matched to the brush head.

1 . A stroke transmission gear mechanism for an electric toothbrush to translate an oscillating stroke motion of a drive rod into an oscillating amplitude-modified stroke motion of an output rod, comprising a transmission lever which is pivotable about a swivel bearing being provided between the two rods, both of which are linked to the transmission lever at different distances from the swivel bearing, wherein the drive rod is connected to the end of the transmission lever opposite from the swivel bearing via a hinge, and the other end of the transmission lever is held in the swivel bearing in a displaceable manner.  
   
   
       2 . A gear mechanism according to  claim 1 , wherein the drive rod has a laterally stepped projection on its front end to which the transmission lever is pivotably mounted in a hinge.  
   
   
       3 . A gear mechanism according to  claim 2 , wherein the other end of the transmission lever has a slot through which a pin projects which is stationarily mounted to the gear mechanism and which forms the pivot axis of the transmission lever.  
   
   
       4 . A gear mechanism according to  claim 3 , wherein a transmission rod connected to the output rod is linked to the transmission lever via a hinge.  
   
   
       5 . UA gear mechanism according to  claim 4 , wherein the transmission rod is connected to the output rod via a ball joint, and the output rod is guided into a slot running obliquely to the longitudinal axis of the output rod.  
   
   
       6 . A gear mechanism according to  claim 4 , wherein at least the transmission lever, the projection, and the transmission rod are fabricated from a plastic, and the hinges are film hinges.  
   
   
       7 . An electric toothbrush comprising a hand part provided with a drive, a drive pin which performs at least one axial stroke motion projecting at the slip-on end of the hand part, and a head part, which can be pushed onto the slip-on end of the hand part, in which a brush head which bears bristle tufts is mounted so that it can perform at least one back-and-forth stroke motion in the longitudinal direction of the head part, for which purpose the brush head is connected to the drive pin when the head part is pushed onto the hand part, a stroke transmission gear mechanism is provided in the head part in the mechanical linkage between the drive pin and the brush head, the drive rod of the stroke transmission gear mechanism being connected to the drive pin, and the stroke transmission gear mechanism in particular is installed in such a way that a stroke reduction occurs.  
   
   
       8 . A toothbrush comprising a hand part provided with a drive, a drive pin which performs at least one axial stroke motion protecting at the slip-on end of the hand part, and a head part, which can be pushed onto the slip-on end of the hand part, in which a brush head which bears bristle tufts is mounted so that it can perform at least one back-and-forth stroke motion in the longitudinal direction of the head part, for which purpose the brush head is connected to the drive pin when the head part is pushed onto the hand part, a stroke transmission gear mechanism provided in the head part in the mechanical linkage between the drive pin and the brush head, the drive rod of the stroke transmission gear mechanism being connected to the drive pin, and the stroke transmission gear mechanism in particular is installed in such a way that a stroke reduction occurs, wherein the stroke transmission gear mechanism is as claimed in  claim 1 .  
   
   
       9 . A toothbrush according to  claim 8 , wherein the output rod is provided with a head which bears one or more bristle tufts.  
   
   
       10 . A toothbrush according to  claim 9 , wherein the ball joint is formed from a ball head on the transmission rod and a ball socket on the output rod.