High-G acceleration protection by caging
First Claim
1. For use in a MEMS device having a proof mass flexibly coupled to a substrate, the proof mass having a normal operating range of motion, a method for securing the MEMS device during a period of high acceleration, the method comprising applying a DC voltage between the proof mass and a non-suspended structure of the device, the DC voltage being sufficient to create an electrostatic force that maintains the proof mass in a displaced position that is outside the normal operating range of motion of the proof mass.
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Accused Products
Abstract
For use in a MEMS device having a suspended proof mass, a method and apparatus for securing the MEMS device during a period of high acceleration. The method may include applying a DC voltage between the proof mass and a non-suspended structure of the device. The non-suspended structure may be mounted on a substrate, and the substrate or the non-suspended structure may be electrically isolated from the proof mass by an insulating layer or by one or more islands. Applying the DC voltage creates an electrostatic force that moves the proof mass toward (or holds the proof mass near) the substrate. Movement of the proof mass may be limited by mechanical contact between the proof mass and the insulating layer, the one or more islands, or by a cage mounted on the substrate during the period of high acceleration.
32 Citations
21 Claims
- 1. For use in a MEMS device having a proof mass flexibly coupled to a substrate, the proof mass having a normal operating range of motion, a method for securing the MEMS device during a period of high acceleration, the method comprising applying a DC voltage between the proof mass and a non-suspended structure of the device, the DC voltage being sufficient to create an electrostatic force that maintains the proof mass in a displaced position that is outside the normal operating range of motion of the proof mass.
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7. A micromachined device comprising:
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a proof mass flexibly coupled to a substrate, the proof mass having a normal operating range of motion;
at least one non-suspended structure mounted on the substrate; and
an insulating member positioned between the proof mass and the substrate, the insulating member preventing electrical contact between the proof mass and the at least one non-suspended structure;
wherein a DC voltage applied between the proof mass and the at least one non-suspended structure causes the proof mass to move toward the non-suspended structure beyond the normal operating range of motion, the insulating member limiting the motion and preventing electrical contact between the proof mass and the at least one non-suspended structure. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15)
a cage in a fixed positional relationship to the substrate, the cage being outside of the normal operating range of motion of the proof mass;
wherein the cage limits the motion of the proof mass in a direction parallel to the substrate when the DC voltage displaces the proof mass to a position toward the substrate that is beyond the normal operating range of motion of the proof mass.
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14. The micromachined device of claim 13, wherein the cage limits the motion of the proof mass in any direction parallel to the substrate.
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15. The micromachined device of claim 14, wherein the at least one island is mounted on or is a part of the cage.
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16. A micromachined device comprising:
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a proof mass flexibly coupled to a substrate, the proof mass having a normal operating range of motion;
at least one non-suspended structure mounted on the substrate; and
a layer of insulating or semi-insulating material positioned between the proof mass and the substrate, the layer preventing electrical contact between the proof mass and the at least one non-suspended structure;
wherein a DC voltage applied between the proof mass and the at least one non-suspended structure displaces the proof mass to a position beyond the normal operating range of motion of the proof mass. - View Dependent Claims (17, 18, 19, 20, 21)
the displacement of the proof mass due to the DC voltage causes the proof mass to maintain contact with the insulating or semi-insulating layer.
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19. The micromachined device of claim 16, wherein the insulating or semi-insulating layer is affixed to the proof mass, and wherein;
the displacement of the proof mass due to the DC voltage causes the insulating or semi-insulating layer to contact the non-suspended structure.
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20. The micromachined device of claim 16, further comprising:
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a cage mounted on the substrate, the cage being beyond the normal operating range of motion of the proof mass;
wherein the cage limits the motion of the proof mass in a direction parallel to the substrate when the proof mass is moved toward the substrate beyond the normal operating range of motion by the DC voltage.
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21. The micromachined device of claim 20, wherein the cage limits the motion of the proof mass in any direction parallel to the substrate.
Specification