US Patent 10449023 Oral cleansing device with energy conservation

A brushing device including a motor having an eccentric drive shaft, an output shaft operably connected to the motor, and a power train assembly coupled between the eccentric drive shaft and the output shaft. The power train converts rotation of the eccentric drive shaft into an oscillating movement of the output shaft. The power train includes one or more conservation features that absorb energy when the output shaft rotates in a first direction and reapply energy to the output shaft when it rotates in a second direction.