Omnidirectional Pull-Cord Sensor With Magnetic Activation and Break-Away
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Solution Overview
Problem
Current pull-cord sensors in care facilities face issues such as mechanical wear, false indications due to shock and vibration, high activation force requirements, entanglement hazards, and difficulty in cleaning, especially in wet areas with high humidity.
Innovation Solution
An omnidirectional pull-cord sensor using a solid-state magnetic field detector with a permanent magnet in an elastomeric body, incorporating a cord break-away feature and a low activation force mechanism, sealed to prevent water ingress, and designed for easy cleaning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical switches are used in pull-cord sensors, then the sensor can detect pull forces, but the mechanical switches are subject to mechanical wear, contamination, fretting, and corrosion, leading to limited operational life
Solution Approach 1:
The patent replaces mechanical switches with a magnetic field detection system consisting of a magnet attached to the pull cord and a magnetic sensor (such as a Hall effect sensor or reed switch) mounted on the panel. This substitution eliminates mechanical contacts that are subject to wear, contamination, and corrosion, thereby significantly improving operational life and reliability while maintaining the pull-force detection function.
2Reliability
If high activation pull force is required for mechanical switches, then false indications due to vibration and shock are reduced, but residents with limited arm/hand mobility and strength cannot easily activate the sensor
Solution Approach 1:
The magnetic field detection system is inherently more sensitive to small movements and requires minimal activation force compared to mechanical switches. The magnet-sensor configuration can detect even slight displacements of the pull cord, enabling residents with limited mobility to easily activate the sensor while the magnetic field's stability provides immunity from false indications caused by vibration and shock.
3Ease of manufacture
If the cord remains attached to the signalling device, then the sensor structure is simplified, but the cord is time consuming and difficult to clean completely in wet areas
Solution Approach 1:
The patent divides the pull cord system into separable components: the cord assembly can be detached from the signalling device panel. This segmentation allows the cord to be easily removed for thorough cleaning and disinfection in wet areas, addressing infection control requirements while maintaining a relatively simple overall sensor structure through modular design.
4Object-affected harmful factors
If a break-away feature is implemented to reduce entanglement hazards, then safety is improved, but the cord assembly complexity increases
Solution Approach 1:
The magnetic coupling system inherently provides a break-away feature because the magnetic attraction force has a limited range and strength. If the cord becomes excessively tangled or subjected to extreme forces, the magnetic coupling will fail or the cord can be easily detached, providing safety without requiring complex mechanical break-away mechanisms. The simplicity of the magnetic system keeps the overall assembly relatively uncomplicated.
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 sensor provides reliable activation in any direction with low force, reduces mechanical wear, prevents entanglement, and ensures easy cleaning and disinfection, while maintaining operational integrity in humid environments.
Implementation Method 1
an activation portion including a magnet portion for generating a magnetic field; a sensor portion for sensing a level of the magnetic field level
Data Source
Figure 1
Figure 2a~4
Figure 5~8
AI summary
The disclosure is directed at a method and system for a pull-cord sensor assembly that includes an activation portion including a magnet portion for generating a magnetic field; a sensor portion for sensing a level of the magnetic field level; a comparator for comparing the level of the magnetic field with a threshold value; and a pull cord integrated with the activation portion.