Electric toothbrush with skewed neck

Abstract

An elongate neck of a toothbrush extends askew to an elongate handle which encloses a rotary motor. At the end of the neck is a head to which brush blocks are mounted for movement relative to the head. The transmission includes a driving member and a driven member for transmitting torque from the motor, the driving member rotating about a driving member axis, and the driven member rotating about a driven member axis. A crankshaft mounted to the head converts rotation of the driven member to movement of a brush block, the driven member axis is skewed or offset relative to the driving member axis, and the driving member and the driven member are connected by a helical spring flexible coupling. One brush block rotates in an oscillating manner and a pair of brush blocks oscillate, in a linear manner, 180 degrees out of phase.

1 . An electric toothbrush comprising:
 an elongate handle enclosing a rotary motor;   an elongate neck extending askew to the handle and having a head at a distal end of the neck;   at least one brush block mounted to the head for movement relative to the head;   a transmission including a driving member connected to a driven member for transmitting torque from the motor, the driving member rotating about a driving member axis, the driven member rotating about a driven member axis;   a helical spring flexible coupling connecting the driving member to the driven member; and   a conversion mechanism mounted to the head for converting rotation of the driven member into movement of the brush block, wherein the driven member axis is skewed or offset relative to the driving member axis.   
     
     
         2 . The toothbrush of  claim 1  including fastening means at a proximal end of the neck for releasably fastening the neck to the handle. 
     
     
         3 . The toothbrush of  claim 2  wherein the fastening means is a bayonet coupling fastening the neck to the handle by a push-turn action. 
     
     
         4 . The toothbrush of  claim 1  wherein the driving member is mounted at a proximal end, the driven member is mounted in the head, and the helical spring flexible coupling is elongated to extend within the neck between the driving and driven members. 
     
     
         5 . The toothbrush of  claim 4  wherein the helical spring flexible coupling has a substantially cylindrical body with outwardly tapered frusto-conical ends for receiving cooperating tapered portions of the driving and driven members in a push fit. 
     
     
         6 . The toothbrush of  claim 5  wherein the transmission further includes a gearbox for increasing the torque applied to the driving member and reducing speed of rotation of the driving member, axes of the motor, the gearbox, and the driving member being coaxial with a central longitudinal axis of the handle. 
     
     
         7 . The toothbrush of  claim 6  wherein the conversion mechanism comprises a crankshaft. 
     
     
         8 . The toothbrush of  claim 7  including at least one sliding brush block mounted for linear sliding movement relative to the head and at least one rotary brush block mounted to rotate relative to the head. 
     
     
         9 . The toothbrush of  claim 8  including three brush blocks mounted to the head for separate oscillatory movement relative to the head, the brush blocks including a pair of sliding brush blocks and one rotary brush block. 
     
     
         10 . The toothbrush of  claim 9  wherein
 the crankshaft is connected to the driven member coaxially,   each sliding brush block is mounted for sliding movement substantially perpendicular to the driven member axis,   each rotary brush block is mounted for rotation about a respective rotary block axis substantially perpendicular to the sliding block axis, and   the crankshaft has an eccentric throw for engaging each sliding and rotary brush block.   
     
     
         11 . The toothbrush of  claim 10  wherein each sliding block throw is received in an aperture in a respective sliding brush block, the aperture extending substantially parallel to an axis of the crankshafts, and each rotary brush block throw is received in a slot in the rotary brush block, the slot extending substantially parallel to a rotary brush block axis. 
     
     
         12 . The toothbrush of  claim 11  wherein the neck is curved. 
     
     
         13 . A replaceable brushing attachment comprising:
 an elongate hollow neck having a proximal end with means for releasably fastening to a handle enclosing a rotary motor, the neck further having a head on a distal ends of the neck;   at least one brush mounted to the head for movement relative to the head;   a transmission enclosed substantially within the neck, the transmission including a driving member joined by a connector to a driven member for transmitting torque from the motor, the driving member rotating about a driving member axis, the driven member rotating about a driven member axis;   a conversion mechanism mounted to the head for converting rotation of the driven member into movement of the brush, wherein
 the driven member axis is skewed or offset relative to the driving member axis, and 
 the connector comprises a helical spring flexible coupling. 
   
     
     
         14 . The replaceable brushing attachment of  claim 13  including fastening means at a proximal end of the neck for releasably fastening to the handle. 
     
     
         15 . The replaceable brushing attachment of  claim 14  wherein the fastening means is a bayonet coupling, fastening the neck to be the handle by a push-turn action. 
     
     
         16 . The replaceable brushing attachment of  claim 14  wherein the driving member is mounted at a proximal end, the driven member is mounted in the head, and the helical spring flexible coupling is elongated to extend within the neck between the driving and driven members. 
     
     
         17 . The replaceable brushing attachment of  claim 16  wherein the helical spring flexible coupling has a substantially cylindrical body with outwardly tapered frusto-conical ends for receiving cooperating tapered portions of the driving and driven members in a push fit. 
     
     
         18 . The replaceable brushing attachment of  claim 17  wherein the conversion mechanism comprises a crankshaft. 
     
     
         19 . The replaceable brushing attachment of  claim 18  including at least one sliding brush block mounted for linear sliding movement relative to the head and at least one rotary brush block mounted to rotate relative to the head. 
     
     
         20 . The replaceable brushing attachment of  claim 19  including three brush blocks mounted to the head for separate oscillatory movement relative to the head, the brush blocks including a pair of sliding brush blocks and a one rotary brush block. 
     
     
         21 . The replaceable brushing attachment of  claim 20  wherein
 the crankshaft is connected to the driven member coaxially,   each sliding brush block is mounted for sliding movement substantially perpendicular to the driven member axis,   each rotary brush block is mounted for rotation about a respective rotary brush block axis substantially perpendicular to the sliding block axis, and   the crankshaft has an eccentric throw for engaging each sliding and rotary brush block.   
     
     
         22 . The replaceable brushing attachment of  claim 21  wherein each sliding block throw is received in an aperture in a respective sliding brush block, the aperture extending substantially parallel to an axis of the crankshafts, and each rotary brush block throw is received in a slot in the rotary brush block, the slot extending substantially parallel to a rotary brush block axis. 
     
     
         23 . The replaceable brushing attachment of  claim 22  wherein the neck is curved.