Preload force optimization for stable ball bearing contact
Various embodiments include a device (e.g., a camera or other type of device) that optimizes a preload force for a ball bearing voice coil motor (VCM) actuator in order to achieve a stable ball bearing contact. To optimize the preload force, a plate may be placed and/or shaped in a way that causes the center of the preload force to be at a location that results in stable ball bearing contact (e.g., to prevent dynamic tilt/rocking of a frame/carrier during movement). In embodiments, the device includes a flexure (flexible circuit) to supply a drive current to the ball bearing VCM actuator. In some embodiments, the ball bearing VCM actuator is used in a camera device to move an image sensor of a carrier, relative to a lens, to provide focus and/or autofocus (AF) functionality.
1 . A 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.
2 . The camera of claim 1 , wherein to cause the center of the preload force to be at the location of the preload plate, a center of mass of the preload plate is located closer to at least one of the first plurality of ball bearings than the second plurality of ball bearings.
3 . The camera of claim 2 , wherein the center of mass of the preload plate is located closer to the at least one of the first plurality of ball bearings than the second plurality of ball bearings based on one or more of:
placement of the preload plate closer to the at least one of the first plurality of ball bearings than the second plurality of ball bearings, or
an asymmetric shape of the preload plate.
4 . The camera of claim 1 , wherein the at least one component fixedly coupled with the carrier comprises an image sensor to capture image data based on light that has passed through at least one lens of the camera.
5 . The camera of claim 1 , wherein the coil is fixedly coupled with the carrier, such that the coil moves together with the carrier.
6 . The camera of claim 1 , further comprising a flexure provides an electrical connection between the carrier and another stationary structure of the camera, wherein a flexible portion of the flexure allows motion of the carrier relative to the other stationary structure enabled by the ball bearing VCM actuator while maintaining the electrical connection, and wherein the flexure conveys electrical signals between the carrier and the other stationary structure via the electrical connection.
7 . The camera of claim 1 , wherein the first plurality of ball bearings comprises one or more ball bearings between the two ball bearings that are smaller in size than the two ball bearings.
8 . 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.
9 . The device of claim 8 , wherein to cause the center of the preload force to be at the location of the preload plate, a center of mass of the preload plate is located closer to at least one of the first plurality of ball bearings than the second plurality of ball bearings.
10 . The device of claim 9 , wherein the center of mass of the preload plate is located closer to the at least one of the first plurality of ball bearings than the second plurality of ball bearings based on one or more of:
placement of the preload plate closer to the at least one of the first plurality of ball bearings than the second plurality of ball bearings, or
an asymmetric shape of the preload plate.
11 . The device of claim 8 , wherein the at least one component fixedly coupled with the carrier comprises an image sensor to capture image data based on light that has passed through at least one lens of the camera.
12 . The device of claim 8 , wherein the coil is fixedly coupled with the carrier, such that the coil moves together with the carrier.
13 . The device of claim 8 , further comprising a flexure provides an electrical connection between the carrier and another stationary structure of the camera, wherein a flexible portion of the flexure allows motion of the carrier relative to the other stationary structure enabled by the ball bearing VCM actuator while maintaining the electrical connection, and wherein the flexure conveys electrical signals between the carrier and the other stationary structure via the electrical connection.
14 . The device of claim 8 , wherein the first plurality of ball bearings comprises one or more ball bearings between the two ball bearings that are smaller in size than the two ball bearings.
15 . The device of claim 8 , wherein the one or more processors are configured to cause the ball bearing VCM actuator to move the carrier in at least one direction parallel to an optical axis defined by at least one lens of the camera.
16 . 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.
17 . The ball bearing VCM actuator of claim 16 , wherein to cause the center of the preload force to be at the location of the preload plate, a center of mass of the preload plate is located closer to at least one of the first plurality of ball bearings than the second plurality of ball bearings.
18 . The ball bearing VCM actuator of claim 17 , wherein the center of mass of the preload plate is located closer to the at least one of the first plurality of ball bearings than the second plurality of ball bearings based on one or more of:
placement of the preload plate closer to the at least one of the first plurality of ball bearings than the second plurality of ball bearings, or
an asymmetric shape of the preload plate.
19 . The ball bearing VCM actuator of claim 16 , wherein the device is a camera, and wherein the carrier is fixedly coupled with an image sensor to capture image data based on light that has passed through at least one lens of the camera.
20 . The ball bearing VCM actuator of claim 16 , wherein the coil is fixedly coupled with the carrier, such that the coil moves together with the carrier.