An oral hygiene device is disclosed having at least two motors to simultaneously vibrate and impart motion upon the head portion of the oral hygiene device, most beneficially at the tip. A first motor is positioned in the handle portion of the device to impart a first frequency of movement to the tip....http://www.google.es/patents/US6955539?utm_source=gb-gplus-sharePatente US6955539 - Characterization of motion of dual motor oral hygiene device
Characterization of motion of dual motor oral hygiene device
