Two-step auto focus camera and method for driving the same

A two-step auto focusing camera comprising:

• a lens unit having a barrel, a lens mounted to the barrel and a permanent magnet fixed to the barrel, a movement of the permanent magnet causing the lens and the barrel to move accordingly;
• upper and lower coil seats being mounted around the lens unit and being arranged at upper and lower sides of the magnet, respectively;
• upper and lower coils winding around the upper and lower coil seats, respectively;
• a printed circuit board electrically connecting with the upper and lower coils and supplying a current thereto;
• wherein the current has at least first and second groups of square waves, the at least first group of square waves causing the magnet to move upwardly, and the at least second group of square waves causing the magnet to move downwardly.