Patent ID: 8424143

Claim:
An electric toothbrush, comprising: a housing; a brush; an electric motor for driving the brush; a power supply for providing the electric power required for operation of the toothbrush, wherein a voltage supplied by the power supply declines with the discharge status of the power supply from a high-voltage range to a low-voltage range; a switch mechanism for turning the drive on and off; and an electronic circuit for adjusting the effective voltage (U Mot ) applied to the electric motor, such that during operation of the toothbrush in the high-voltage range (H), the effective voltage (U Mot ) applied to the electric motor is lowered to a level at which the electric motor has reached a rotational speed corresponding essentially to the rotational speed of the electric motor in the medium-voltage range, wherein the electric motor is designed so that it still reaches a required minimum rotational speed in the range of low admissible voltages range; and wherein the effective voltage (U Mot ) on the electric motor is measured via a measurement device and compared with a setpoint value (U Ref ), the electronic circuit activating the voltage of the power supply when the effective voltage (U Mot ) drops below the setpoint value (U Ref ) and switches the effective voltage (U Mot ) off when the effective voltage (U Mot ) rises above the setpoint value (U Ref ).