Magnetometer Door Window Gap Detection

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Solution Overview

Problem

Existing door and window detectors face limitations in sensing range, especially on ferromagnetic materials, and lack adjustability for different gap settings, making them inadequate for large gaps and vulnerable to tampering, while also being labor-intensive to produce and maintain high security standards.

Innovation Solution

A high sensitivity low current draw magnetometer with programmable control circuits and a 3-axis magnetometer that can detect gaps from zero to large distances with adjustable thresholds, and randomly oriented magnets to meet high security standards, allowing for wireless operation and extended battery life, and field programmability to work with multiple unique magnet assemblies.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of stationary object

If a magnet and reed switch combination is used for door/window detection, then the detector can monitor open/closed states, but the sensing range is limited to 1/2 to 3 inches and reduced to 1/2 that distance on ferromagnetic materials

Engineering Contradiction:
Improvesensing rangeVSAvoiddetector design complexity
Core Design Contradiction:
Length of stationary objectVSEase of manufacture

Solution Approach 1:

The patent replaces the mechanical magnetic contact system (magnet and reed switch) with an optical detection system using a light source and photodetector. This substitution eliminates the limited sensing range of magnetic contacts while maintaining the ability to detect door/window states, achieving gaps of 10 feet or more without increasing manufacturing complexity.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the detection parameter from magnetic field interaction to optical signal transmission. By using infrared or visible light instead of magnetic fields, the system achieves dramatically extended sensing ranges while avoiding the ferromagnetic material interference that limits magnetic contact performance.

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If a magnetic contact with fixed gap distance is used, then the detector can indicate door open/closed states, but there is no adjustment capability for different gap settings requiring multiple products

Engineering Contradiction:
Improvegap setting adjustabilityVSAvoidproduct variety
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent introduces adjustable optical detectors with programmable gap distances, allowing a single product to dynamically adapt to different detection requirements. The detector can be programmed with various threshold values to accommodate different door/window configurations, eliminating the need for multiple fixed-gap products.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The optical detection system serves multiple functions: it can detect various gap distances, work with different door/window materials (including ferromagnetic materials), and accommodate different installation scenarios. This multi-functionality replaces the need for multiple specialized magnetic contact products.

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

3Reliability

If high security magnetically balanced contacts with multiple reed switches and magnets are used, then the contact becomes defeat resistant, but the manufacturing becomes highly labor intensive requiring precise positioning

Engineering Contradiction:
Improvesecurity levelVSAvoidmanufacturing efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent replaces the complex mechanical assembly of multiple magnets and reed switches with a simplified optical detector and light source system. This substitution maintains high security performance while dramatically improving manufacturing efficiency, as the optical system requires no precise mechanical positioning or labor-intensive assembly.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent extracts the security function from the complex mechanical magnetic contact system and implements it through optical detection with programmable thresholds and tamper detection capabilities. This extraction eliminates the labor-intensive positioning requirements while preserving and enhancing security features.

Inventive Principle:
Principle #2Taking out (Extraction)

4Ease of operation

If outdoor detectors are made wireless to simplify installation, then the detectors can be easily installed, but battery replacement is required every five years

Engineering Contradiction:
Improveinstallation simplicityVSAvoidmaintenance time
Core Design Contradiction:
Ease of operationVSLoss of time

Solution Approach 1:

The patent implements wireless detectors with extended battery life through low-power optical detection circuits and efficient power management. The system maintains continuous monitoring capability while minimizing power consumption, extending battery operation beyond five years and reducing maintenance frequency.

Inventive Principle:
Principle #20Continuity of useful action

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

Enables detection of gaps from zero to large distances with adjustable sensitivity, enhances security by making it difficult to tamper with, and reduces production complexity by using a single magnet assembly to meet multiple security standards, ensuring reliable operation and long battery life.

Implementation Method 1

A high sensitivity low current draw magnetometer with programmable control circuits

Methodology Applied
Scientific EffectMagnetic field detection: Magnetism

Data Source

PatentEP2650848B1Large gap door/window, high security, intrusion detectors using magnetometers
Publication Date: 2023.03.08 ADEMCO INC
  • EP2650848B1 patent drawingFigure 1~1A
  • EP2650848B1 patent drawingFigure 1B
  • EP2650848B1 patent drawingFigure 2

AI summary

A door, or window detector incorporates a magnet and a magnetometer. Dual loop processing can be provided for real-time signals from the magnetometer, as the magnet moves relative to it, to determine when at least one of small gap or large gap indicating alarms should be issued. Security can be substantially increased by randomizing the orientation of the magnet.