(1) due to the eccentric rotation of the metal rod.
Because of the high speed rotation of the metal rod in the sealed metal box, the internal air of the metal box through the friction force is also caused by the violent movement. Thus causing the entire sealed metal box vibration, and then drive the entire cell phone vibration. It is known that the above calculation, the metal rod to do high-speed rotation of the energy share of a large share, so the main reason for the vibration caused by the phone.
(2) caused by the instability of the center of gravity.
The metal rod which is connected with the rotating shaft of the vibration motor is not based on the geometric alignment.
(3) the manner in which the
Therefore, the rotating shaft of the vibration motor rotates in the direction of the center of mass. Therefore, the metal rod is not in fact in the horizontal plane rotation. In the rotation, where the centroid position will change along with the change of the metal rod position. Therefore, metal rod rotation plane and horizontal plane form a certain angle changing. The movement of the center of mass in a certain range of space is bound to cause the position of the object to be moved. When the changes are small and very frequent, it is shown as the vibration.