Oral hygiene devices employing an acoustic waveguide

Abstract

An oral hygiene device having an ultrasound transducer 22 and an acoustic waveguide 24 facilitating the transmission of ultrasonic acoustic energy to fluids in the oral cavity is disclosed. Preferred ultrasound operating parameters for operation in aqueous environments and in dental slurries are disclosed. Devices may incorporate a drive motor 16 for oscillating a device head 23, acoustic waveguide 24 and one or more bristle tuft(s) 26 at sonic frequencies, and preferred sonic operating parameters are also provided. Multi-element piezoelectric transducer assemblies 30, 40, and various control and communications features are disclosed. Oral hygiene devices disclosed herein achieve improved plaque and stain removal from the teeth as well as interproximal and subgingival regions, while enhancing the user experience, massaging the gums, stimulating dental tissue, and disrupting biofilm.

1 . An oral hygiene device that is user-activatable to initiate an operating cycle comprising: 
 a device head support structure having an acoustic waveguide and at least one bristle tuft projecting from the support structure;    an ultrasound transducer acoustically coupled to the acoustic waveguide that operates, during the operating cycle, to produce ultrasonic energy at frequencies of less than 1500 kHz; and    a motor mechanically coupled to the support structure that operates, during the operating cycle, to produce oscillation at sonic frequencies of less than 1000 Hz and to produce oscillation of the bristle tips at a velocity of less than 1.5 m/sec.    
     
     
         2 . The device of  claim 1 , wherein the ultrasound transducer comprises multiple piezoelectric elements.  
     
     
         3 . The device of  claim 1 , wherein the ultrasound transducer comprises multiple piezoelectric elements connected mechanically in series and electrically in parallel.  
     
     
         4 . The device of  claim 1 , additionally comprising an impedance matching layer contacting the ultrasound transducer.  
     
     
         5 . The device of  claim 1  comprising a plurality of bristle tufts, wherein at least one bristle tuft has an exposed length that is greater than the exposed length of at least one other bristle tuft.  
     
     
         6 . The device of  claim 1  comprising a plurality of bristle tufts, wherein at least one bristle tuft has a stiffness that is greater than the stiffness of at least one other bristle tuft.  
     
     
         7 . The device of  claim 1 , wherein at least one bristle tuft has an angle of orientation that is different from the angle of orientation of at least one other bristle tuft.  
     
     
         8 . The device of  claim 1 , wherein the motor operates, during an operating cycle, to produce oscillation at the bristle tips of a peak amplitude of less than 2.2 mm.  
     
     
         9 . The device of  claim 1 , wherein the motor comprises a limited angle torque motor.  
     
     
         10 . An oral hygiene device that is user-activatable to commence an operating cycle comprising: 
 a motor mechanically coupled to a support structure that operates, during the operating cycle, to produce vibration at sonic frequencies of less than 2000 Hz;    an ultrasound transducer that operates, during the operating cycle, to produce ultrasonic energy at frequencies of less than 1500 kHz; and    at least one controller that controls operation of the ultrasound transducer and the motor during the operating cycle; wherein the output of the ultrasound transducer and motor are variable during an operating cycle.    
     
     
         11 . The device of  claim 10 , wherein the output of the ultrasound transducer and motor are varied synchronously during an operating cycle.  
     
     
         12 . The device of  claim 10 , wherein the ultrasound transducer operates at a duty cycle of less than 100% during an operating cycle and the output of the motor is reduced when the ultrasound transducer is active during an operating cycle.  
     
     
         13 . The device of  claim 10 , wherein the output of the motor is modulated by modulating the current supplied to the drive motor.  
     
     
         14 . The device of  claim 10 , wherein the current drawn by the drive motor is monitored.  
     
     
         15 . The device of  claim 10 , wherein the drive frequency of the motor is monitored.  
     
     
         17 . The device of  claim 10 , additionally comprising an ultrasound drive circuit and a transformer assembly that inductively couples and transfers power from the ultrasound drive circuit to the ultrasound transducer.  
     
     
         18 . An oral hygiene device comprising: 
 a support structure having an acoustic waveguide and at least one bristle tuft comprising a plurality of bristles projecting from the support structure;    an ultrasound transducer acoustically coupled to the acoustic waveguide that operates, during the operating cycle, to produce ultrasonic energy at frequencies of less than 1500 kHz; and    a motor mechanically coupled to the support structure that operates, during an operating cycle, to vibrate the bristle tips at a peak bristle tip velocity of less than 1.5 m/sec and at a peak bristle amplitude of less than 2.2 mm.    
     
     
         19 . An oral hygiene device of  claim 18 , wherein the motor comprises a stepper motor.  
     
     
         20 . An oral hygiene device of  claim 18 , wherein the motor comprises a limited angle torque motor.  
     
     
         21 . An oral hygiene device of  claim 18 , wherein the motor produces an oscillating motion at an included angle of less than about 12° during an operating cycle.  
     
     
         22 . An oral hygiene device of  claim 18 , wherein the motor produces an oscillating motion at an included angle of between about 3° and 7° during an operating cycle.  
     
     
         23 . An oral hygiene device of  claim 18 , additionally comprising an ultrasound drive circuit and a transformer assembly that inductively couples and transfers power from the ultrasound drive circuit to the ultrasound transducer.  
     
     
         24 . An oral hygiene device of  claim 18 , additionally comprising a detection feature that allows initiation of an operating cycle only when the ultrasound transducer is determined to be operational.  
     
     
         25 . An oral hygiene device of  claim 18 , additionally comprising a controller that provides a timing function that separates a device operating cycle into a plurality of operating subcycles.  
     
     
         26 . An oral hygiene device of  claim 18 , additionally comprising a controller that monitors the resonant operating conditions of the motor.  
     
     
         27 . An oral hygiene device of  claim 18 , additionally comprising a controller that modulates the ultrasound drive frequency and/or amplitude during an operating cycle.  
     
     
         28 . An oral hygiene device of  claim 18 , additionally comprising a controller that provides frequency sweeping of the ultrasound transducer drive frequency within a predetermined frequency range at one or more predetermined modulating frequencies.  
     
     
         29 . An oral hygiene device of  claim 18 , additionally comprising a controller that monitors current drawn by the ultrasound power supply circuit and ultrasound transducer during an operating cycle.  
     
     
         30 . An oral hygiene device of  claim 18 , additionally comprising a controller that is programmed to count the number of device operating cycles.  
     
     
         31 . An oral hygiene device of  claim 18 , additionally comprising a controller that is programmed to monitor the function of the ultrasound transducer.  
     
     
         32 . An oral hygiene device of  claim 18 , additionally comprising a controller that is programmed to monitor conditions of the fluid environment during operation and modify operating parameters of the device based on the detected conditions of the fluid environment.  
     
     
         33 . An oral hygiene device comprising: 
 a support structure having at least one implement projecting from the support structure;    an ultrasound transducer assembly acoustically coupled to the implement and an ultrasound drive circuit and power supply in operative communication with the ultrasound transducer assembly to drive the transducer assembly to produce ultrasonic energy during an operating cycle; and    a transformer assembly that inductively couples and transfers power from the ultrasound drive circuit to the ultrasound transducer.    
     
     
         34 . The device of  claim 33 , wherein the transformer assembly comprises a primary coil and core in operative communication with the ultrasound drive circuit and a secondary coil and core in operative communication with the ultrasound transducer assembly.  
     
     
         35 . The device of  claim 33 , wherein the transformer assembly additionally comprises an additional transformer component that enables the exchange of electrical information between the primary coil and core and the secondary coil and core.  
     
     
         36 . A device head adapted for detachable attachment to a device handle having a power source, comprising: 
 an implement projecting from a device head support structure; and    an ultrasound transducer having multiple piezoelectric elements connected mechanically in series and electrically in parallel acoustically coupled to the implement.    
     
     
         37 . A device head adapted for detachable attachment to a device handle having a power source, comprising 
 an implement projecting from a device head support structure, the implement adapted to be powered by a power source; and    a transformer coil and core mounted in the device head and adapted to cooperate with a transformer coil and core mounted in the device handle to inductively couple power from the device handle to the device head.    
     
     
         38 . An ultrasound transducer assembly comprising: 
 at least two piezoelectric elements arranged in a cooperating configuration in which the elements are arranged mechanically in series, each piezoelectric element having electrically conductive material associated with one or more surfaces and each piezoelectric element being electrically connected to another piezoelectric element in parallel.    
     
     
         39 . The ultrasound transducer assembly of  claim 38 , additionally comprising at least one acoustic impedance matching element mounted in proximity to the piezoelectric elements.  
     
     
         40 . The ultrasound transducer assembly of  claim 39 , wherein the acoustic impedance matching element comprises graphite.  
     
     
         41 . The ultrasound transducer assembly of  claim 38 , wherein the piezoelectric elements are bonded and arranged in a stacked arrangement with an electrically conductive layer provided on at least a portion of the element surfaces.  
     
     
         42 . The ultrasound transducer assembly of  claim 38 , wherein the at least two piezoelectric elements form a transducer array.  
     
     
         43 . An ultrasound module comprising an ultrasound transducer assembly of  claim 38  in combination with an acoustic waveguide that contacts a substantial portion of the transducer assembly.  
     
     
         44 . An ultrasound module of  claim 43 , wherein the acoustic waveguide is acoustically transmissive and comprises a material having a hardness less than 80 Shore A.