Variable Elastic Constant Micromechanical Accelerometer

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Solution Overview

Problem

Current acceleration sensors require multiple types and increased complexity to detect both low and high accelerations, leading to larger size, higher costs, and reduced portability due to the need for multiple sensors and complex control circuits.

Innovation Solution

A micromechanical device with two seismic masses and spring assemblies that adjust elastic constants based on force thresholds, allowing a single sensor to detect a wide range of accelerations by altering its mechanical response through stopper and housing elements, reducing the need for multiple sensors and simplifying the control circuitry.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple different accelerometers are integrated in an electronic device to detect both low and high accelerations, then the detection capability for various acceleration ranges is improved, but the device complexity, integration area, and manufacturing cost increase

Engineering Contradiction:
Improvedetection capabilityVSAvoidcontrol circuitry complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent implements a single accelerometer that can operate in multiple detection modes by switching between different spring constants. The accelerometer includes a first spring element for low-G detection and a second spring element for high-G detection, allowing one device to perform functions that previously required two separate accelerometers. This multi-functionality reduces device complexity while maintaining versatility in detecting both low and high accelerations.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent employs dynamic switching between different spring elements based on the acceleration magnitude being detected. A switching mechanism activates the appropriate spring element (first for low-G, second for high-G) depending on the detected acceleration range. This dynamic adaptation allows a single accelerometer to effectively handle multiple detection scenarios without requiring permanently integrated multiple sensors, thereby reducing overall device complexity.

Inventive Principle:
Principle #15Dynamics

2Adaptability or versatility

If multiple different accelerometers are integrated in an electronic device to detect both low and high accelerations, then the detection capability for various acceleration ranges is improved, but the integration area increases

Engineering Contradiction:
Improvedetection capabilityVSAvoidintegration area
Core Design Contradiction:
Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

The patent implements a single accelerometer that can operate in multiple detection modes by switching between different spring constants. The accelerometer includes a first spring element for low-G detection and a second spring element for high-G detection, allowing one device to perform functions that previously required two separate accelerometers. This multi-functionality reduces device complexity while maintaining versatility in detecting both low and high accelerations.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent combines the functionality of two separate accelerometers (low-G and high-G) into a single integrated device. By merging the detection capabilities and sharing common components such as the seismic mass, support structure, and control circuitry, the patent significantly reduces the integration area required compared to housing two independent accelerometers. The switching mechanism enables one physical device to fulfill the role of multiple sensors.

Inventive Principle:
Principle #5Merging (Combining)

3Adaptability or versatility

If multiple different accelerometers are integrated in an electronic device to detect both low and high accelerations, then the detection capability for various acceleration ranges is improved, but the manufacturing cost increases

Engineering Contradiction:
Improvedetection capabilityVSAvoidmanufacturing cost
Core Design Contradiction:
Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent implements a single accelerometer that can operate in multiple detection modes by switching between different spring constants. The accelerometer includes a first spring element for low-G detection and a second spring element for high-G detection, allowing one device to perform functions that previously required two separate accelerometers. This multi-functionality reduces device complexity while maintaining versatility in detecting both low and high accelerations.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent combines the functionality of two separate accelerometers (low-G and high-G) into a single integrated device. By merging the detection capabilities and sharing common components such as the seismic mass, support structure, and control circuitry, the patent significantly reduces the integration area required compared to housing two independent accelerometers. The switching mechanism enables one physical device to fulfill the role of multiple sensors.

Inventive Principle:
Principle #5Merging (Combining)

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 device provides a compact, cost-effective solution for detecting both low and high accelerations with improved mechanical stability and reduced power consumption, enabling efficient measurement of various acceleration ranges.

Implementation Method 1

a first spring assembly (57) and a second spring assembly (59)... The first and second spring assemblies (57, 59) have respective elastic constants (K1, K2} different from one another

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

at least one stopper element (66a) and a respective housing element (66b)... adapted, in use, to alter the elastic response of the sensor (50)

Methodology Applied
Scientific EffectMechanical Force: Mechanical Force

Data Source

PatentEP3839520B1Micromechanical device with elastic assembly having variable elastic constant
Publication Date: 2024.05.01 STMICROELECTRONICS SRL
  • EP3839520B1 patent drawingFigure 1A~1B
  • EP3839520B1 patent drawingFigure 2
  • EP3839520B1 patent drawingFigure 2A

AI summary

A micromechanical device (50) comprising: a semiconductor body (51); a first mobile structure (53; 253); an elastic assembly (57, 59; 259), coupled to the first mobile structure and to the semiconductor body (51) and adapted to undergo deformation in a direction (X) ; and at least one abutment element (66b; 66a). The elastic assembly (57, 59; 259) is configured to enable an oscillation of the first mobile structure (53; 253) as a function of a force applied thereto. The first mobile structure (53; 253), the abutment element (66b; 66a) and the elastic assembly (57, 59; 259) are arranged with respect to one another in such a way that: when said force is lower than a force threshold, the elastic assembly (57, 59; 259) operates with a first elastic constant (K1; K4); and when said force is greater than the threshold force, then the first mobile structure is in contact with the abutment element, and a deformation of the elastic assembly is generated, which operates with a second elastic constant (K1 + K2; K5) different from the first elastic constant. Main figure: Figure 2