Toothbrush employing acoustic waveguide

Abstract

A power toothbrush ( 10 ) is disclosed having a handle ( 15 ), battery ( 12 ), ultrasonic drive circuit ( 14 ), motor ( 16 ), control unit ( 18 ), and toothbrush head ( 20 ). The toothbrush head includes bristles ( 26 ) and a waveguide ( 24 ) that is operatively connected to an ultrasonic transducer ( 22 ). The waveguide facilitates the transmission of acoustic energy into the dental fluid to achieve improved cleaning and stain removal and improved cleaning in interproximal and subgingival regions. In one embodiment an ultrasound transducer module ( 30 ) includes a plurality of piezoelectric elements ( 32, 34 ) that may be mechanically connected in series, and electrically connected in parallel. One or more contacts ( 36 ) connect the elements, and a waveguide structure ( 50 ). An impedance matching layer ( 38 ) may be provided between the waveguide and the ultrasonic transducer module. The waveguide may be formed from an relatively soft material, for example, a polymer having a hardness between 10 and 65 Shore A.

1 . A toothbrush comprising: 
 a toothbrush head including an acoustic waveguide and a plurality of bristle tufts projecting from a toothbrush head support structure, wherein the acoustic waveguide comprises a polymer having a durometer hardness less than 100 Shore A; and    an ultrasonic transducer acoustically coupled to the acoustic waveguide, wherein the ultrasonic transducer is adapted to oscillate at ultrasonic frequencies.    
   
   
       2 . The toothbrush of  claim 1 , wherein the polymer has a durometer hardness between about 10 and about 65 Shore A.  
   
   
       3 . The toothbrush of  claim 1 , wherein the polymer is silicone rubber.  
   
   
       4 . The toothbrush of  claim 1 , wherein the ultrasonic transducer is mounted in the toothbrush head in proximity to the acoustic waveguide.  
   
   
       5 . The toothbrush of  claim 1 , wherein the acoustic waveguide comprises a base structure mounted in the toothbrush head and a distal portion extending outwardly from the base structure.  
   
   
       6 . The toothbrush of  claim 5 , wherein the base structure is larger cross-section than the distal portion.  
   
   
       7 . The toothbrush of  claim 1 , wherein the acoustic waveguide is substantially rectangular in profile.  
   
   
       8 . The toothbrush of  claim 1 , wherein the acoustic waveguide includes oppositely disposed side walls that are tapered and terminate distally in a waveguide face.  
   
   
       9 . The toothbrush of  claim 1 , further comprising an impedance matching layer disposed between the ultrasonic transducer and the acoustic waveguide.  
   
   
       10 . The toothbrush of  claim 1 , wherein the ultrasonic transducer comprises a plurality of piezoelectric elements.  
   
   
       11 . The toothbrush of  claim 10 , wherein the plurality of piezoelectric elements are mechanically stacked and electrically connected in parallel.  
   
   
       12 . The toothbrush of  claim 11 , wherein the plurality of piezoelectric elements comprise two piezoelectric elements.  
   
   
       13 . The toothbrush of  claim 12 , further comprising at least one electrical contact contacting each of the piezoelectric elements.  
   
   
       14 . The toothbrush of  claim 1 , wherein the ultrasonic transducer operates at an ultrasound carrier frequency in the range of about 100 kHz to about 750 kHz.  
   
   
       15 . The toothbrush of  claim 1 , wherein the ultrasonic transducer operates at an ultrasound carrier frequency of less than about 750 kHz.  
   
   
       16 . The toothbrush of  claim 1 , wherein the ultrasonic transducer operates at an ultrasound carrier frequency of less than about 500 kHz.  
   
   
       17 . The toothbrush of  claim 1 , wherein during use the ultrasonic transducer oscillates periodically with a pulse repetition frequency of between about 0.5 Hz and about 225 Hz.  
   
   
       18 . The toothbrush of  claim 1 , wherein the ultrasonic transducer oscillates periodically with a pulse repetition frequency of between about 5 Hz and about 1,500 Hz.  
   
   
       19 . The toothbrush of  claim 18 , wherein the ultrasonic transducer operates with a duty cycle between about 5% and about 15%.  
   
   
       20 . A toothbrush comprising: 
 an ultrasonic transducer adapted to operate within the following ranges of operating parameters during use: 100-750 kHz carrier frequency; 0.5-1500 Hz pulse repetition frequency (PRF); and 50-10,000 cycles/burst;    a plurality of bristle tufts projecting from a toothbrush head; and    an acoustic waveguide acoustically coupled to the ultrasonic transducer and projecting from the toothbrush head.    
   
   
       20 . The toothbrush of  claim 19 , wherein the ultrasonic transducer operates at a mechanical index of less than 1.9.  
   
   
       21 . The toothbrush of  claim 19 , wherein the ultrasonic transducer operates at a duty cycle of less than about 15%.  
   
   
       22 . A toothbrush of claims  19  wherein the ultrasonic transducer operates at a pulse repetition frequency (PRF) of from about 40-200 Hz.  
   
   
       23 . A toothbrush of  claim 19  wherein the ultrasonic transducer operates at a pulse repetition frequency (PRF) of less than about 20 Hz.  
   
   
       24 . A toothbrush comprising: 
 a toothbrush head having an acoustic waveguide and a plurality of bristle tufts, the acoustic waveguide having at least two opposing faces terminating in a distal waveguide face; and    a sonic component coupled to the toothbrush head to vibrate the acoustic waveguide and the bristle tufts at a sonic acoustic frequency.    
   
   
       25 . The toothbrush of  claim 24 , wherein the acoustic waveguide has tapered side walls forming generally a wedge-shaped waveguide, wherein a waveguide base portion has a larger cross-sectional area than the distal waveguide face.  
   
   
       26 . The toothbrush of  claim 24 , wherein the distal waveguide face is curved.  
   
   
       27 . The toothbrush of  claim 24 , wherein the distal waveguide face is generally convex.  
   
   
       28 . The toothbrush of  claim 24 , wherein the acoustic waveguide has a hardness of approximately 40 Shore A or less.  
   
   
       29 . The toothbrush of  claim 24 , wherein the acoustic waveguide is oriented generally parallel to a longitudinal axis of the toothbrush head.  
   
   
       30 . The toothbrush  claim 24 , wherein the acoustic waveguide is oriented generally transverse to a longitudinal axis of the toothbrush head.  
   
   
       31 . A toothbrush head comprising a support structure, an acoustic waveguide and a plurality of bristle tufts projecting from the support structure, the acoustic waveguide having multiple opposing faces, with at least two opposing faces having walls terminating in a distal waveguide face; and 
 an ultrasonic transducer acoustically coupled to the acoustic waveguide and capable of producing ultrasonic energy at frequencies of less than about 1000 kHz.    
   
   
       32 . A toothbrush head for mounting on a toothbrush handle, the toothbrush head comprising an acoustic waveguide, an ultrasonic transducer operably connected to the acoustic waveguide, and a plurality of bristle tufts projecting from a toothbrush head support structure, the acoustic waveguide having a generally block-like structure and having an exposed height that is greater than about 50% and less than about 120% of the exposed height of the bristle tufts.  
   
   
       33 . The toothbrush of  claim 32 , wherein the acoustic waveguide comprises a polymer having a durometer hardness between about 10 and about 65 Shore A.  
   
   
       34 . The toothbrush of  claim 33 , wherein the polymer is silicone rubber.  
   
   
       35 . The toothbrush of  claim 32 , further comprising an impedance matching layer disposed between the ultrasonic transducer and the acoustic waveguide.  
   
   
       36 . The toothbrush of  claim 32 , wherein the ultrasonic transducer comprises a plurality of piezoelectric elements.  
   
   
       37 . The toothbrush of  claim 36 , wherein the plurality of piezoelectric elements are mechanically stacked and electrically connected in parallel.  
   
   
       38 . The toothbrush of  claim 37 , wherein the plurality of piezoelectric elements comprise two piezoelectric elements.  
   
   
       39 . The toothbrush of  claim 37 , further comprising at least one electrical contact contacting each of the piezoelectric elements.  
   
   
       40 . The toothbrush of  claim 32 , wherein the ultrasonic transducer operates at an ultrasound carrier frequency in the range of about 100 kHz to about 750 kHz.  
   
   
       41 . The toothbrush of  claim 40 , wherein the ultrasonic transducer oscillates periodically with a pulse repetition frequency of between about 0.5 Hz and about 225 Hz.