Patent ID: 8766568

Claim:
A system for maintaining performance of an electric toothbrush powered by a battery, comprising: a system for measuring the battery voltage of the electric toothbrush and/or the current value in a stator portion of the motor for the electric toothbrush from which current value the corresponding amplitude of movement of the workpiece of the toothbrush is then obtained; a circuit/program routine for changing the pulse width of the drive signal for the motor if the battery voltage drops below a first voltage threshold value and/or a circuit/program routine for changing the drive signal frequency if the amplitude falls below a first amplitude threshold value, to increase the amplitude of movement of the workpiece; and a circuit/program routine for terminating the operation of the appliance if the battery voltage drops below a second voltage threshold value which is lower than the first voltage threshold value and/or if the workpiece amplitude drops below a second amplitude threshold value which is lower than the first amplitude threshold value.