Micromechanical Shock Sensor Latch Mechanism
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Solution Overview
Problem
Conventional shock sensors require constant power and are not suitable for small-scale or long-life applications, as they draw power even when no acceleration or impact is present, and their high threshold sensitivity is affected by friction forces, making them unreliable for detecting mechanical shock in fragile devices.
Innovation Solution
A micromechanical shock sensor with a latch mechanism that uses a proof mass coupled to a substrate via a spring system, featuring a latch spring with different stiffness directions and a mass element to reduce contact forces, allowing reliable detection of critical accelerations without power and maintaining a latched state under multi-axial conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional accelerometers are used to monitor acceleration loads, then shock detection capability is provided, but constant power draw is required even when no acceleration or impact is present
Solution Approach 1:
The patent employs a dynamic latch mechanism where a proof mass moves in response to acceleration forces and engages with a latch structure. The system transitions from a static conventional accelerometer to a dynamic mechanical system that only consumes energy during shock events when the proof mass overcomes friction and engages the latch, rather than requiring constant power for detection.
Solution Approach 2:
The patent replaces the electronic/conventional accelerometer system with a micromechanical latch-based system. Instead of using electronic sensors that require constant power, the invention uses purely mechanical elements (proof mass, spring, latch) that passively detect shock through mechanical movement and latching, eliminating the need for continuous electrical power.
2Measurement precision
If high threshold sensitivity is used in shock sensors, then detection capability is improved, but friction forces affect reliability making detection unreliable
Solution Approach 1:
The patent introduces a mass element that generates an inertial force counteracting the friction force at the latch contact interface. This counterweight mechanism creates a force balance where the inertial force of the mass element offsets the friction resistance, allowing the latch to engage reliably at the desired threshold sensitivity without being受阻 by friction forces.
Solution Approach 2:
The patent changes the physical parameters of the latch mechanism by introducing a mass element with specific inertia properties. This parameter change transforms the force balance equation at the latch interface, modifying the relationship between threshold acceleration and friction force to achieve reliable engagement at the desired sensitivity threshold.
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 micromechanical shock sensor effectively detects critical accelerations without power consumption, ensuring reliable operation even in powered-off devices, and reduces the dependency on friction forces, providing accurate shock detection with low contact forces and robustness against multi-axial vibrations.
Implementation Method 1
a spring system coupled between the proof mass and the substrate
Implementation Method 2
a latch mechanism having a latch spring attached to the surface and a latch tip extending from a movable end of the latch spring
Data Source
AI summary
A micromechanical shock sensor includes a proof mass coupled to a surface of a substrate and a projection element extending laterally from the proof mass. The shock sensor further includes a latch mechanism and a retention anchor. The latch mechanism has a latch spring attached to the surface and a latch tip extending from a movable end of the latch spring. The retention anchor is attached to the surface and is located proximate the latch tip. The proof mass is configured for planar movement relative to the substrate when the proof mass is subjected to a force of at least a threshold magnitude. Movement of the proof mass in response to the force causes the latch tip to become retained between the projection element and the retention anchor to place the shock sensor in a latched state. The latched state may be detected by optical inspection, probe, or external readout.