Imaging device and its use method

An imaging device comprises a central processing unit used for processing data in a high speed, a lens driven unit, a lens and a lens protection unit; the lens drive unit drives the lens to extend and retract; the lens protection unit comprises a voltage adjustment subunit used for adjusting the drive voltage of the lens drive unit and a detection subunit used for detecting whether the imaging device is in a falling state; when detecting that the imaging device is in a falling state, the detection subunit outputs a signal to the central processing unit; after receiving the signal, the central processing unit outputs a voltage adjustment signal to the voltage adjustment subunit which raises the drive voltage of the lens drive unit, and then outputs a lens retracting drive signal to the lens drive unit which retracts the lens in a high speed. The invention also relates to a method for applying the imaging device.