Impulse actuated MEMS devices
View Patent ↗An impulse actuated mechanism for, e.g., a digital camera shutter, includes a shutter blade disposed at a first end of a flexure having an opposite second end fixed so as to constrain the blade to move along a planar, relatively long, first trajectory between opposite initial and final blade positions, and a short-throw, high force blade actuator that includes a stator and a stage supported for movement relative to the stator and along a second trajectory intersecting the initial blade position, and a mechanism for accelerating the stage along the second trajectory and against the blade such that at least some of the momentum of the stage is imparted to the blade, causing the blade to move along the first trajectory from the initial blade position to the final blade position, where it blocks the passage of light through a light aperture of the camera.
1. An impulse actuated shutter, comprising:
a shutter blade, comprising a blade disposed at a first end of a flexure and having an opposite second end fixed so as to constrain the blade to move along a first trajectory and between opposite initial and final blade positions;
an actuator, comprising a stator and a stage supported for movement relative to the stator along a second trajectory intersecting at least the initial blade position of the blade trajectory and between opposite initial and final stage positions; and,
a mechanism for accelerating the stage along the second trajectory and against the blade such that at least some of the momentum of the stage is imparted to the blade and causes the blade to move away from the stage, along the first trajectory, and from the initial blade position to the final blade position.
2. The shutter of claim 1 , further comprising a mechanism disposed at the final blade position and operable to arrest and hold the blade in the final blade position.
3. The shutter of claim 2 , wherein the flexure is operable to return the blade from the final blade position to the initial blade position, and further comprising a mechanism for releasing the blade from the blade arrest and hold mechanism.
4. A method for actuating the shutter of claim 3 , the method comprising:
accelerating the stage along the second trajectory and against the blade with the stage accelerating mechanism such that at least a portion of the momentum of the stage is imparted to the blade and causes the blade to move along the first trajectory from the initial blade position to the final blade position and to obscure a light aperture located adjacent thereto.
5. The method of claim 4 , wherein accelerating the stage comprises:
biasing the stage against a spring such that potential energy is stored in the spring and the stage moves away from the initial stage position and to a second initial stage position; and,
releasing the stage from the second initial stage position.
6. The method of claim 5 , further comprising applying a biasing force to the blade such that the blade is attracted to the stage and follows the stage to the second initial stage position.
7. The method of claim 4 , further comprising:
arresting and holding the blade in the final blade position for a selected period of time with the blade arrest and hold mechanism; and,
releasing the blade from the blade arrest and hold mechanism with the blade release mechanism such that the flexure returns from the blade from the final blade position to the initial blade position.
8. The shutter of claim 1 , wherein the second trajectory is substantially shorter than the first trajectory.
9. The shutter of claim 1 , wherein the stage accelerating mechanism is motivated at least in part by electrostatic, electromagnetic, piezoelectric, electrostrictive, or electro-thermal forces.
10. The shutter of claim 1 , wherein the blade and the stage are in contact with each other when respectively disposed in the initial blade and stage positions.
11. The shutter of claim 1 , wherein the blade and the stage are spaced apart from each other when respectively disposed in the initial blade and stage positions.
12. The shutter of claim 1 , wherein the blade is operable to completely obscure a light aperture located adjacent to the final blade position when the blade is disposed in the final blade position.
13. The shutter of claim 1 , wherein the flexure is operable to return the blade from the final blade position to the initial blade position.
14. An impulse actuated MEMS shutter, comprising:
a shutter, comprising a planar blade integrally formed at a first end of an elongated, resilient, planar flexure and having an opposite second end fixed so as to constrain the blade to move along a planar, arcuate first trajectory and between opposite initial and final blade positions;
an actuator, comprising a planar stator and a planar stage supported above the stator for parallel movement relative to the stator along a second trajectory coplanar with the blade and between opposite initial and final stage positions, each of the stator and the stage having a plurality of planar electrodes disposed on respective opposing surfaces thereof; and,
a mechanism for selectably applying electrostatic charges of opposite polarities to the respective electrodes on the opposing surfaces of the stator and the stage such that the stage is accelerated along the second trajectory and against the blade, at least some of the momentum of the stage is imparted to the blade, and the blade moves away from the stage, along the first trajectory, from the initial blade position to the final blade position and obscures a light aperture located adjacent to the final blade position.
15. The shutter of claim 14 , further comprising:
a receptacle disposed at the final blade position and configured to receive the blade; and,
a mechanism for applying an electrostatic charge to the receptacle such that the receptacle attracts the blade and arrests and holds the blade in the final blade position.
16. The shutter of claim 14 , wherein at least one of the blade, the flexure, the stator and the stage is formed by micromachining.
17. The shutter of claim 16 , wherein the micromachining comprises at least one of photolithography, etching or photolithography and etching.
18. The shutter of claim 14 , wherein at least one of the blade, the flexure, the stator and the stage comprises silicon.
19. A digital camera, comprising:
an array of photosensitive pixels;
optics, including a light aperture, disposed in front of the array and operable to admit light from a subject onto the array; and,
an impulse actuated shutter mechanism, comprising:
a shutter blade, comprising a blade disposed at a first end of a flexure and having an opposite second end fixed so as to constrain the blade to move along a first trajectory and between opposite initial and final blade positions;
an actuator, comprising a stator and a stage supported for movement relative to the stator along a second trajectory intersecting at least the initial blade position of the blade trajectory and between opposite initial and final stage positions; and,
a mechanism for accelerating the stage along the second trajectory and against the blade such that at least some of the momentum of the stage is imparted to the blade and causes the blade to move away from the stage, along the first trajectory, and from the initial blade position to the final blade position.
20. The camera of claim 19 , wherein the stage of the shutter mechanism is accelerated at least in part by electrostatic, electromagnetic, piezoelectric, electrostrictive, or electro-thermal energy.
21. The camera of claim 19 , wherein the shutter mechanism further comprises a mechanism disposed at the final blade position and operable to arrest and hold the blade in the final blade position for a selected period of time.