3D MEMS Magnetic Sensor for Tamper-Resistant Door and Window Detection

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Solution Overview

Problem

Existing door and window contact sensors relying on reed and magnet (RM) technology have limitations such as a limited protection distance and vulnerability to being defeated by additional magnets, and existing improvements increase unit costs.

Innovation Solution

A three-dimensional (3D) microelectromechanical system (MEMS) magnetic sensor is used to detect three-dimensional movement and magnetic field parameters, allowing for secure detection of door or window positions and preventing tampering by identifying changes in magnetic fields, with control circuitry and software to analyze and transmit status signals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If reed and magnet (RM) technology is used in door/window contact sensors, then the unit cost is low, but the protection distance is limited and the sensor can be defeated by introducing another magnet in close proximity

Engineering Contradiction:

Improvesensor securityVSAvoidvulnerability to magnet tampering

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the traditional reed switch and magnet mechanical magnetic field detection system with a 3D MEMS magnetic sensor that uses micromachined structures to detect magnetic field changes. This substitution provides enhanced security against magnet tampering while maintaining cost-effectiveness through the integrated microelectromechanical design.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the detection parameter from simple magnetic field presence (traditional RM technology) to three-dimensional magnetic field vector analysis using 3D MEMS sensors. This parameter change enables the sensor to detect changes in magnetic field direction and magnitude, making it resistant to defeat by additional magnets.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If traditional RM contact sensors are used, then the device complexity is low, but the measurement precision of door/window position is insufficient

Engineering Contradiction:

Improveposition detection accuracyVSAvoidsensor structure

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent transitions from traditional one-dimensional magnetic field detection to three-dimensional magnetic field vector measurement using 3D MEMS sensors. This dimensional change enables precise detection of door and window position in multiple spatial directions, significantly improving measurement precision while the integrated nature of MEMS keeps the overall device complexity manageable.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Reliability

If improvements are made to overcome RM technology limitations, then the protection distance and security are improved, but the unit cost increases significantly

Engineering Contradiction:

Improvesensor securityVSAvoidunit cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent merges the magnetic sensor, signal processing circuitry, and control functions into a single integrated 3D MEMS contact sensor unit. This consolidation reduces the number of separate components needed, simplifying manufacturing and reducing unit cost while maintaining the enhanced security features provided by 3D magnetic field detection.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

By replacing expensive separate reed switches and magnets with an integrated 3D MEMS magnetic sensor that combines sensing and processing functions, the patent achieves improved security at a lower unit cost. The MEMS technology integrates multiple functions into a single micromachined component, reducing overall system complexity and cost.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 3D MEMS sensor effectively enhances the security and reliability of door and window contact sensors by detecting relative movement in three dimensions and preventing tampering attempts without significantly increasing the unit cost, providing robust and efficient threat detection within security systems.

Implementation Method 1

a three-dimensional (3D) microelectromechanical system (MEMS) magnetic sensor to detect three-dimensional movement and magnetic field parameters

Methodology Applied

Scientific EffectMagnetic field detection: Magnetic Field

Data Source

PatentUS10643440B2Door/window sensor

Publication Date: 2020.05.05 RESIDEO USA LLC

AI summary

Systems and methods for a door or window contact sensor are provided. Some systems can include a three-dimensional (3D) microelectromechanical system (MEMS) magnetic sensor, a programmable processor, and executable control software stored on a non-transitory computer readable medium, wherein the 3D MEMS magnetic sensor can measure magnetic parameters of a magnetic field along three axes, and wherein the programmable processor and the executable control software can compare the magnetic parameters to reference values to determine whether the magnetic parameters indicate that a door or a window associated with the 3D MEMS magnetic sensor is open or closed.