MEMS-based optical image stabilization
In one example, a camera is provided that includes: a plurality of MEMS electrostatic comb actuators, each actuator operable to exert a force on at least one lens; and an optical image stabilization (OIS) algorithm module operable to command the plurality of actuators to actuate the at least one lens responsive to motion of the camera.
1. A camera, comprising:
at least one motion sensor configured to detect a motion of the camera;
a plurality of electrostatic actuators configured to move at least one lens based on the detected motion of the camera to implement image stabilization;
a fixed portion on which the plurality of electrostatic actuators are supported to surround the at least one lens, wherein each of the plurality of electrostatic actuators comprises a movable portion configured to move, relative to the fixed portion, between a first position, in which the actuator is operable, and a second position, in which the actuator is non-operable; and
a latch configured to latch the movable portion in the first position.
2. The camera of claim 1 , wherein each actuator is configured to exert a tangential force on the at least one lens, and wherein the plurality of actuators tangentially actuate the at least one lens in response to a motion of the camera.
3. The camera of claim 2 , further comprising:
a plurality of position sensors corresponding to the plurality of actuators, each position sensor measuring a tangential displacement of its corresponding actuator; and
a translator module operable to translate the tangential displacements from the position sensors into a displacement for the lens.
4. The camera of claim 1 , wherein the movable portion is configured to latch to the first position when an accelerated pulse is applied to the movable portion.
5. The camera of claim 1 , wherein the plurality of actuators are further configured to rotate the at least one lens when the plurality of actuators actuate the at least one lens tangentially in coordination.
6. The camera of claim 1 , wherein the camera is integrated into a cellular telephone.
7. The camera of claim 1 , wherein the actuators are electrostatic comb actuators comprising interdigitated fingers and the interdigitated fingers are configured to be moved apart to allow room for actuation when the movable portion moves from the second position to the first position.
8. The camera of claim 7 , further comprising a circular stage to receive the at least one lens, wherein the plurality of actuators comprises three actuators evenly spaced around the circular stage.
9. The camera of claim 1 , wherein each of the plurality of actuators comprises a flexure connecting each actuator to the at least one lens, wherein the flexure is more flexible in a radial direction away from the at least one lens than in a linear direction tangent to the at least one lens.
10. The camera of claim 9 , wherein the flexure is folded and has a V-shape with a longitudinal axis aligned in the linear direction.
11. The camera of claim 1 , further comprising a gyroscope configured to measure a pitch and yaw of the camera, wherein the plurality of actuators actuate the at least one lens based on the pitch and yaw of the camera.
12. An actuator, comprising:
a plurality of electrostatic actuators configured to move at least one lens to implement image stabilization, wherein each actuator is configured to tangentially actuate the at least one lens in response to a motion of the actuator;
a fixed portion on which the plurality of electrostatic actuators are supported to surround the at least one lens, wherein each of the plurality of electrostatic actuators comprises a movable portion configured to move, relative to the fixed portion, between a first position, in which the actuator is operable to move the at least one lens based on a detected motion of a camera, and a second position, in which the actuator is non-operable; and
a latch configured to latch the movable portion in the first position.
13. The actuator of claim 12 , further comprising a coplanar deployment lever configured to pivot about a fulcrum at the movable portion, wherein the coplanar deployment lever pivots to engage the latch when the movable portion moves to the first position.
14. The actuator of claim 13 , wherein the coplanar deployment lever comprises a cam surface configured to engage the latch when the movable portion is in the first position.
15. The actuator of claim 13 , wherein the latch comprises a coplanar over-center latch configured to receive the cam surface of the coplanar deployment lever.
16. The actuator of claim 15 , wherein the coplanar over-center latch comprises a latch flexure configured to bias the coplanar over-center latch toward a lock position locking the coplanar deployment lever in the first position.
17. A system, comprising:
at least one motion sensor configured to detect a motion of the system;
a lens;
a stage holding the lens within a curved aperture;
three integrally formed tangential actuators symmetrically disposed about the stage in a fixed portion, each tangential actuator operable to displace the stage in a direction tangential to a curve defined by the curved aperture, wherein each tangential actuator comprises a movable portion configured to move, relative to the fixed portion, between a first position, in which the tangential actuator is operable to move the stage based on the detected motion of the system, and a second position, in which the tangential actuator is not operable; and
a latch configured to latch the movable portion in the first position.
18. The system of claim 17 , wherein the curved aperture is a circle and the curve defined by the curved aperture is a circle.
19. The system of claim 17 , further comprising three V-shaped flexures corresponding to the three tangential actuators, wherein each tangential actuator couples to the stage through the corresponding V-shaped flexure.
20. The system of claim 19 , wherein each V-shaped flexure has a longitudinal axis aligned in the direction tangential to the curve.