Driving system for shape memory alloy based actuator and camera module using same

摘要

A driving system for an SMA based actuator having SMA wires or rods includes a capture module, a determination module, and four drive modules. The capture module captures current position of a lens module from a position sensor. The displacement difference between the current position and a target position is determined. The first drive module can rapidly or slowly increase the current to the SMA, or rapidly or slowly decrease the current to the SMA, causing fast or slow movement of a lens module in one direction or fast or slow movement in the opposite direction, to achieve the desired auto-focus of a camera module.

主权项

1. A driving system for a shape memory alloy (SMA) based actuator having SMA wires, comprising:
a capture module configured to capture a current position of a lens module from a position sensor; a determination module configured to calculate difference P0 between the current position and a target position and to determine which range out of a plurality of ranges the difference P0 may fall into; a first drive module configured to rapidly increase the current applied to the SMA wires to rapidly contract the SMA wires to move the lens module to the target position when P0≧20 μm; a second drive module configured to rapidly decrease the current applied to the SMA wires to rapidly extend the SMA wires to move the lens module to the target position when P0≦20 μm; a third drive module configured to slowly increase the current applied to the SMA wires to slowly contract the SMA wires to move the lens module to the target position when 0