Linear vibration motor

A linear vibration motor, comprising:

• a base having a receiving space,
• a vibration unit located in the receiving space,
• an elastic member fixed to the base and suspending the vibration unit in the receiving space, and coils fixed to the base and opposite to and spaced away from the vibration unit;
• wherein the vibration unit comprises a magnet, the magnet is opposite to and spaced away from the coils;
• wherein the coils comprise:
• a first coil for connecting an electric signal and
• a second ring coil disposed on one side of the first coil;
• a third ring coil disposed on the other side of the first coil;
• and both the second ring coil and the third ring coil are insulated from the first coil;
• the first coil, the second ring coil and the third ring coil are all non-coaxially winded;
• both ends the second ring coil and the third ring coil are connected to each other to form a closed loop and the second ring coil and the third ring coil are not connected to an external electric signal;
• when the magnet of the vibration unit reciprocates, the second ring coil and the third ring coil generate an induced current which hinders the motion of the vibration unit.