US Patent 7197784 Electric toothbrush

An electric toothbrush includes a casing having a handle and a neck extending from the handle. A motor is situated within the handle and has an output shaft with an eccentric cam on it. A tuft block is located at a remote end of the neck. A rocker arm extends longitudinally within the neck and has a proximal end driven by the cam, and a distal end driving the tuft block. A resilient bushing is sealed within the neck and intermediate-portion of the rocker arm extends through it in sealed manner to allow pivoting of the rocker arm across the bushing.