Electrically driven toothbrush

Abstract

The invention relates to an electrically driven toothbrush comprising an electric motor for rotationally driving a drive shaft around a drive axis, a brush shaft having a first free outer end provided with a bristle, conversion means for converting the rotational movement of the drive shaft into a reciprocal rotational movement of the brush shaft around a brush shaft axis according to conversion characteristics, and pivoting means for enabling the pivoting of at least part of the brush shaft around a pivot axis, extending perpendicularly to the longitudinal direction of the drive shaft, from a neutral pivoting position and against the action of forcing means, to a non-neutral position due to forces acting on the bristle, the pivoting of the at least part of the brush shaft around the pivot axis to the non-neutral position causing a change in the conversion characteristics.

1 . An electrically driven toothbrush comprising an electric motor for rotationally driving a drive shaft around a drive axis, a brush shaft having a first free outer end provided with a bristle, conversion means for converting the rotational movement of the drive shaft into a reciprocal rotational movement of the brush shaft around a brush shaft axis according to conversion characteristics, and pivoting means for enabling the pivoting of at least part of the brush shaft around a pivot axis, extending perpendicularly to the longitudinal direction of the drive shaft, from a neutral pivoting position and against the action of forcing means, to a non-neutral position due to forces acting on the bristle, characterized in that the pivoting of the at least part of the brush shaft around the pivot axis to the non-neutral position causes a change in the conversion characteristics.  
     
     
         2 . An electrically driven toothbrush according to  claim 1 , characterized in that the conversion means comprise an arm member extending essentially radially from the brush shaft and an excenter body, being rotatable about an excenter axis which is located at a radial distance from the brush shaft axis, the excenter body and the arm member being constantly in contact with each other during rotational movement of the excenter body, the pivoting of the at least part of the brush shaft around the pivot axis causing a change in the magnitude of the radial distance.  
     
     
         3 . An electrically driven toothbrush according to  claim 2 , characterized in that the bristle faces away from the excenter axis.  
     
     
         4 . An electrically driven toothbrush according to  claim 2 , characterized in that the bristle faces the excenter axis.  
     
     
         5 . An electrically driven toothbrush according to  claim 1 , characterized in that the forcing means comprise spring means.  
     
     
         6 . An electrically driven toothbrush according to  claim 1 , characterized in that the excenter body is a cam having an odd number of lobes, said number being equal to or larger than three.  
     
     
         7 . An electrically driven toothbrush according to  claim 1 , characterized in that the brush shaft is rigid.