Power toothbrush with adjustable operation

Abstract

The system changes frequency of the toothbrush to adjust the amplitude of motion of the brush portion of the toothbrush. The change in frequency occurs either manually or automatically. In the manual embodiment, the user, via a switch and internal circuitry, can adjust the operating frequency of the toothbrush which results in a change of amplitude to a value which is most comfortable to the user. In the automatic mode, the resonant frequency of the toothbrush is determined upon initiation of the operation of the toothbrush. The resonant frequency value is then offset by a selected amount, usually higher than the resonant frequency; this offset frequency is the operating frequency of the toothbrush.

1 . A manual system for changing the amplitude of motion of a brush portion of a power toothbrush, comprising:
 a drive system for a power toothbrush which operates at a selected frequency to move the brush portion at a resulting amplitude; and   a frequency adjustment system, including a member operable by a user, for changing the frequency of the drive system and hence the amplitude of motion of the brush portion.   
   
   
       2 . The system of  claim 1 , wherein the operable member is a mechanical switch located on the handle of the toothbrush. 
   
   
       3 . The system of  claim 2 , wherein the frequency adjustment system includes a microprocessor which in turn includes a counter responsive to the switch for changing the frequency output of a timer by a selected amount wherein the frequency output controls the frequency of the drive system. 
   
   
       4 . The system of  claim 1 , wherein the frequency adjustment system is operable any time that the toothbrush is on. 
   
   
       5 . An automatic system for changing the amplitude of motion of a brush portion of a power toothbrush, comprising:
 a drive system for a power toothbrush for operating the toothbrush at a particular frequency to produce a resulting amplitude;   a system for determining the resonant frequency of the toothbrush at a selected time following initiation of operation of the toothbrush by a user; and   a frequency adjustment system, which controls the setting of the operating frequency of the toothbrush at a value which is offset by a preselected amount from the determined resonant frequency.   
   
   
       6 . The system of  claim 5  wherein the resonant frequency determination occurs approximately upon initiation of operation of the toothbrush. 
   
   
       7 . The system of  claim 5  wherein the resonant frequency determining system includes a microprocessor, under program control, for determining phase shift values of current applied to a motor portion of the drive system for a range of successive frequency values which includes the resonant frequency, and for selecting the resonant frequency of the toothbrush which is associated with a minimum phase shift value. 
   
   
       8 . The system of  claim 5 , wherein the set operating frequency is higher than the resonant frequency.