Monolithic Inertial Device with Integrated Clock
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Solution Overview
Problem
Conventional mass/spring based inertial sensing devices require multiple sensors to measure three-dimensional space, leading to increased cost, size, and complexity, as they need to be orthogonally directed and fabricated separately, whereas a single monolithic device capable of measuring all six axes on the same substrate is desired for reduced complexity and cost.
Innovation Solution
An in-plane, monolithically-integrated inertial device with first and second spring mass systems, utilizing time domain digital triggers to measure rotation and acceleration across multiple axes, allowing for a single substrate fabrication and minimizing the number of springed proof masses, enabling the device to operate in three-dimensional space with reduced complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple orthogonally directed sensors are used to measure three-dimensional space, then measurement capability is improved, but device complexity and size increase
Solution Approach 1:
The patent merges multiple inertial sensors (accelerometers and gyroscopes for different axes) into a single monolithic device fabricated on the same substrate. The first and second spring mass systems are integrated on one substrate, allowing simultaneous measurement of rotations about multiple axes and accelerations in multiple directions, thereby reducing device complexity while maintaining comprehensive measurement capability.
Solution Approach 2:
The single substrate serves multiple functions by accommodating different sensor types (accelerometers and gyroscopes) and measurement axes within one device. The first spring mass system measures both rotation about the first axis and acceleration in the second direction, while the second spring mass system measures rotation about the second axis and acceleration in the first direction, demonstrating multi-functionality.
2Adaptability or versatility
If multiple orthogonally directed sensors are used to measure three-dimensional space, then measurement capability is improved, but device size increases
Solution Approach 1:
The patent combines multiple sensor systems into a single integrated device on one substrate, significantly reducing the overall device volume. Instead of requiring separate devices for different axes, the first and second spring mass systems share the same substrate and packaging space, achieving compact integration.
3Manufacturing precision
If conventional separate sensor fabrication is used, then manufacturing precision can be maintained, but manufacturing cost and complexity increase
Solution Approach 1:
The patent merges the fabrication processes of multiple sensors into a single manufacturing sequence on one substrate. By fabricating the first and second spring mass systems using the same standard MEMS semiconductor processing techniques in sequence, the patent reduces manufacturing complexity and cost while maintaining the precision required for inertial measurements.
4Device complexity
If minimum number of springed proof masses is used, then device complexity is reduced, but measurement capability may be compromised
Solution Approach 1:
The patent achieves multi-functionality with a minimum number of springed proof masses. The first spring mass system uses a single proof mass to measure both rotation about the first axis and acceleration in the second direction, while the second spring mass system uses a single proof mass to measure rotation about the second axis and acceleration in the first direction. This demonstrates that multiple measurements can be obtained from minimal physical components through clever mechanical design.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution allows for a compact, cost-effective, and simplified inertial sensing device capable of measuring all six axes on a single substrate, reducing size and complexity while maintaining accuracy and stability by using time domain digital triggers to monitor oscillations and Coriolis forces.
Implementation Method 1
Proof-mass based gyroscopes require an oscillating proof-mass moving orthogonal to the axis of measured spin, as well as spring proof-mass(es) on the oscillating proof mass to measure the Coriolis forces caused by rotation
Implementation Method 2
Accelerometers require a springed proof mass with the direction of motion in the direction of measured force
Data Source
AI summary
An in-plane, monolithically-integrated, inertial device comprising: a support structure and first and second spring mass systems springedly coupled to the support structure. The first spring mass system comprises first and second time domain digital triggers configured to measure rotation and displacement respectively of the support structure about a first axis and along an orthogonal second axis respectively. The second spring mass system comprises third and fourth time domain digital triggers configured to measure acceleration and displacement respectively of the support structure about the second axis and along the first axis respectively.