Micro-machined electromechanical system (MEMS) accelerometer device having arcuately shaped flexures

DETAILED DESCRIPTION The present invention overcomes limitations of the prior art for providing proof mass suspension in a force sensor, which is critical to isolating the accelerometer mechanism from in-plane force inputs during operation while responding to out-of-plane force inputs.
The arcuate suspension apparatus of the invention is stiffer when loaded in the plane of the arcuate shape than out-of-plane.
The arcuate suspension apparatus transfers in-plane loads along the included arch, which causes the arcuate suspension apparatus to be strong and rigid in opposing in-plane loads, and flexes or bends when subjected to out-of-plane loads, which causes the arcuate suspension apparatus to be flexibly compliant when loaded out-of-plane.
According to one aspect of the invention, the arcuate suspension apparatus includes a first substantially arcuately shaped flexure having a cross-section that is relatively substantially extended in the plane of the arcuate shape, the first flexure having a first end structured for connection to a support structure and a second end structured for connection to a movable structure to be suspended from the support structure; and a second substantially flexure that is arcuately shaped similarly to the first flexure and having a cross-section that is relatively substantially extended in the plane of the arcuate shape and having a first end structured for connection to the support structure and a second end structured for connection to the movable structure, the arcuate shape of the second flexure being aligned with the arcuate shape of the first flexure and with the first flexure forming a hinge having an axis of rotation that extends through the first and second flexures.
The arcuate shape of the first and second flexures are aligned either facing oppositely from one another, or facing toward one another.
According to another aspect of the invention, the invention includes a structure to be suspended and a support structure spaced away from the structure to be suspended