| 主权项 |
1. A method of driving a voice coil motor (VCM) that includes a stator including a magnet and a base, a mover including a bobbin and a coil block at a periphery of the bobbin, a cover coupled to the base, and an elastic member including a first elastic member and a second elastic member, wherein the first elastic member includes a first member connected to one end of the coil block and a second member connected to the other end of the coil block and separated from the first member, wherein each of the first member and the second member includes a first inner elastic unit coupled to a lower portion of the bobbin, a first outer elastic unit and a first connection elastic unit connecting the first inner elastic unit and the first outer elastic unit, and wherein the second elastic member includes a second inner elastic unit coupled to an upper portion of the bobbin, a second outer elastic unit and a second connection elastic unit connecting the second inner elastic unit and the second outer elastic unit, and wherein the elastic member is configured to support the bobbin, the method for obtaining an optimum focus comprising:
providing the mover at an initial position while no current is applied to the coil block, wherein a bottom surface of the first inner elastic unit of the first elastic member is spaced apart from the base by a first gap in a direction along or parallel to an optical axis and a top surface of the second inner elastic unit of the second elastic member is spaced apart from the cover by a second gap in the direction along or parallel to the optical axis, such that the first gap between the first inner elastic unit of the first elastic member and the base is smaller than the second gap between the second inner elastic unit of the second elastic member and the cover, and the bottom surface of the first inner elastic unit of the first elastic member is positioned below the bottom surface of the first outer elastic unit of the first elastic member in the direction along or parallel to the optical axis, and the top surface of the second inner elastic unit of the second elastic member is positioned below the top surface of the second outer elastic unit of the second elastic member in the direction along or parallel to the optical axis; applying a backward current to the coil block of the mover in the initial position to move the mover in a first direction to a first position that a bottom surface of the bobbin approaches the base from the initial position, wherein the first direction is a direction from an upper surface of the bobbin to the bottom surface of the bobbin, such that the bottom surface of the first inner elastic unit of the first elastic member approaches the base from the initial position while a bottom surface of the first outer elastic unit of the first elastic member is stationary; applying a forward current to the coil block after receiving the backward current to move the mover in a second direction, opposite to the first direction, toward a second position that the top surface of the second inner elastic unit of the second elastic member approaches the cover from the first position; stopping the mover at a position past the optimum focus by increasing the forward current to the coil block; returning the mover to a position corresponding to the optimum focus located between the first position and the second position by adjusting the forward current to the coil block; and maintaining the mover at the position corresponding to the optimum focus by maintaining an amount of the forward current, such that the optimum focus is formed. |
