Preload force optimization for stable ball bearing contact

A device, comprising:

• one or more processors;
• memory storing program instructions executable by the one or more processors to control operation of a camera;
• and
• the camera, comprising:
• a shield can that houses components of the camera;
• a carrier fixedly coupled with at least one component of the camera;
• and
• a ball bearing voice coil motor (VCM) actuator to move the carrier relative to the shield can, the ball bearing VCM actuator comprising:
• a coil;
• a magnet;
• a first plurality of ball bearings aligned along a first track and a second plurality of ball bearings aligned along a second track, wherein the first and second track are respectively formed by one or more portions of the carrier and one or more portions of a stationary structure of the camera, and wherein the ball bearings are configured to allow motion of the carrier along the first and second tracks, and wherein the first and second plurality of ball bearings are located between the magnet and a preload plate;
• and
• the preload plate, wherein the preload plate is magnetically attracted to the magnet to cause a preload force,
• and wherein the preload plate is configured to cause a center of the preload force to be at a location of the preload plate such that the preload force is shared among two of the first plurality of ball bearings and one of the second plurality of ball bearings, and wherein the location of the center of the preload force prevents a portion of the preload force from being shifted to another of the second plurality of ball bearings during the motion of the carrier.

A ball bearing voice coil motor (VCM) actuator, the ball bearing VCM actuator comprising:

• a coil;
• a magnet;
• a first plurality of ball bearings aligned along a first track and a second plurality of ball bearings aligned along a second track, wherein the first and second track are respectively formed by one or more portions of a carrier and one or more portions of a stationary structure of a device, and wherein the ball bearings are configured to allow motion of the carrier relative to the stationary structure along the first and second tracks, and wherein the first and second plurality of ball bearings are located between the magnet and a preload plate;
• and
• the preload plate, wherein the preload plate is magnetically attracted to the magnet to cause a preload force,
• and wherein the preload plate is configured to cause a center of the preload force to be at a location of the preload plate such that the preload force is shared among two of the first plurality of ball bearings and one of the second plurality of ball bearings, and wherein the location of the center of the preload force prevents a portion of the preload force from being shifted to another of the second plurality of ball bearings during the motion of the carrier.