Compact camera module with zoom and auto-focus actuators sharing the same rotating annular magnet with alternating thick and thin poles

Abstract

A compact camera modules has first, second, and third lens groups that move along an optical axis. A stepping motor is centered on the optical axis rather than offset from the optical axis. The motor has two coils that are fixed in place and a shared rotating magnet. The magnet is attached to a rotating guide that has slots to move the first and second lens groups as it rotates. The two coils are alternately energized to rotate the magnet, the rotating guide, and to move the first and second lens groups for zoom. The magnet has alternating thicker and thinner segments of opposite polarity. The thicker segments exert a greater force on an autofocus coil that is energized to move the third lens for the autofocus function. The same shared rotating magnet is used for both zoom and autofocus functions. A more compact design is possible using a shared magnet.