Autofocus camera systems and methods
View Patent ↗A method for focusing a miniature camera includes providing a current through a coil, moving a lens of a camera based on the current to adjust a focus of the camera, and limiting movement of the lens along an optical path of the camera.
1. A method, comprising:
providing a variable current through a coil; and
moving an optical element, based on the current, with respect to an image sensor, the optical element being disposed on a stage comprising a magnet resiliently suspended adjacent to the coil for movement relative to the coil; and wherein
the coil is wound around an axis that is perpendicular to a direction of movement of the optical element; and
the direction of movement of the optical element comprises a direction of movement toward and/or away from the image sensor along an optical axis of the optical element.
2. The method of claim 1 , wherein:
the optical element comprises a lens disposed on a ring shaped lens mount;
the lens mount is disposed on the stage; and
the stage is constrained by a snubber mechanism against movement other than rectilinear movement along an axis that is parallel to an optical axis of the lens.
3. The method of claim 1 , wherein the stage comprises a micro
electromechanical systems (MEMS) stage.
4. The method of claim 1 , wherein
the stage moves with the optical element; and
the stage remains within a plane defined by the stage itself when the stage moves.
5. The method of claim 4 , wherein the magnet and the optical element are disposed on opposite sides of the stage.
6. The method of claim 1 , further comprising:
providing a housing around the optical element; and
attaching the coil to the housing, whereby the coil is aligned relative to the magnet by the housing.
7. The method of claim 1 , further comprising controlling the current through the coil using a processor to adjust the focus of an image on the image sensor.
8. A device, comprising:
an imaging sensor;
a coil;
circuitry for providing a variable current through the coil; and
an optical element disposed on a stage comprising a magnet resiliently suspended adjacent to the coil for movement relative to the coil; and wherein
the coil is wound around an axis that is perpendicular to a direction of movement of the optical element; and
the direction of movement of the optical element comprises a direction of movement toward and/or away from the imaging sensor along an optical axis of the optical element.
9. The device of claim 8 , wherein the optical element comprises a lens disposed on a ring shaped lens mount, wherein the lens mount is disposed on the stage, and wherein the stage is constrained by a snubber mechanism against movement other than rectilinear movement along an axis that is parallel to an optical axis of the lens.
10. The device of claim 8 , wherein the stage comprises a micro electromechanical systems (MEMS) stage.
11. The device of claim 8 , wherein:
the stage moves with the optical element; and
the stage remains within a plane defined by the stage itself when the stage moves.
12. The device of claim 8 , wherein the magnet and the optical element are attached to the stage in a planar fashion.
13. The device of claim 12 , wherein the magnet and the optical element are disposed on opposite sides of the stage.
14. The device of claim 8 , further comprising:
a housing around the optical element; and wherein
the housing holds the coil and aligns the coil relative to the magnet.
15. A method, comprising:
coupling an optical element to a magnet via a stage; and
suspending the magnet adjacent to a coil via the stage so that the optical element and the magnet move conjointly in response to a variable current through the coil; and wherein
the coil is wound around an axis that is perpendicular to a direction of movement of the optical element; and
the direction of movement of the optical element comprises a direction of movement toward and/or away from an imaging sensor along an optical axis of the optical element.
16. The method of claim 15 , wherein:
the optical element comprises a lens disposed on a ring shaped lens mount;
the lens mount is disposed on the stage; and
the stage is constrained by a snubber mechanism against movement other than rectilinear movement along an axis that is parallel to an optical axis of the lens.
17. The method of claim 15 , wherein the stage comprises a micro electromechanical systems (MEMS) stage.
18. The method of claim 15 , wherein the stage remains within a plane defined by the stage itself when the stage moves conjointly with the magnet and the optical element.
19. The method of claim 15 , wherein the step of coupling the optical element to the magnet via the stage comprises assembling the stage, the magnet, and the optical element in a stacked fashion.
20. The method of claim 19 , wherein the magnet and the optical element are disposed on opposite sides of the stage.
21. The method of claim 15 , further comprising:
providing a housing around the optical element; and
attaching the coil to the housing, whereby the coil is aligned relative to the magnet by the housing.