Patent ID: 7136678

Claim:
A vibrating portable electronic device, comprising: a body; a driving axle having a rotational axis about which it rotates, the driving axle being rotatably supported by the body; a weight unit comprising at least two weight elements, the weight unit having a total mass m and being coupled to the driving axle for being rotated about the rotational axis of the driving axle; wherein the weight unit has a mass center with an offset r with respect to the rotational axis, so that the vibration of the portable device assumes an amplitude of vibration depending on the product of the offset r and the mass m; an electrical motor for rotating the driving axle, and is adapted to adjust the product of the offset r and the mass m; wherein the electrical motor is adapted to adjust the angular disposition of the at least two weight elements in a first angular direction in order to change the offset r to a desired level within a predetermined range; and wherein the device further comprises a member for forming a force that tries to change said adjusted angular disposition of the weight elements in a second angular direction opposite to the first angular direction in order to maintain the offset r on said desired level within said predetermined range.