System for reducing injury from pinch zones in adjustable height work surface assemblies
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Solution Overview
Problem
Adjustable height work surface assemblies pose a risk of pinch injuries due to the movement of desktops colliding with obstructions, including human limbs and immovable objects, as existing systems fail to effectively prevent such collisions during height adjustments.
Innovation Solution
A system comprising a Hall-effect sensor and an LC tank circuit-based proximity detection system, integrated with a motor controller, which monitors motor current draw and detects changes in capacitance to prevent motor operation when collisions or obstructions are detected, ensuring safe height adjustments by disabling the motor when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If height adjustment mechanism is provided, then usability and adaptability are improved, but risk of pinch injuries and collision damage increases
Solution Approach 1:
The system performs preliminary detection of obstructions in the path of the desktop before the height adjustment completes. The sensor detects objects in advance, and the controller preemptively stops motor operation to prevent pinch injuries or collision damage, rather than reacting after contact occurs.
Solution Approach 2:
The system continuously monitors motor current draw during height adjustment and compares it against predetermined thresholds. When current exceeds the threshold indicating potential collision or pinch zone contact, the controller receives feedback and automatically stops motor operation to prevent injury or damage.
2Reliability
If sensor-based obstruction detection is implemented, then safety is improved, but device complexity increases
Solution Approach 1:
The system replaces complex mechanical safety mechanisms with an electrical sensing approach. Instead of using mechanical interlocks or physical guards, the invention uses motor current monitoring and optical sensors to detect obstructions, simplifying the overall system architecture while maintaining safety.
Solution Approach 2:
The controller acts as an intermediary between the motor and the sensor system. It receives signals from the sensor about obstruction detection and intermediates the motor operation by stopping operation when hazards are detected, providing a simple yet effective safety mechanism without requiring direct mechanical intervention.
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 system effectively prevents pinch injuries and damage to the desk and surrounding items by reliably detecting collisions and obstructions, ensuring safe operation of height-adjustable desks by interrupting motor function when hazards are present.
Implementation Method 1
A Hall-effect sensor provides a signal to the system corresponding to a current draw of the motor
Implementation Method 2
a proximity detection sensor connected to the system, wherein said proximity detection sensor is a strip of conducting material disposed adjacent to a perimeter of the desk surface and in electrical connection with an LC tank circuit, wherein said LC tank circuit is configured to exhibit a change in state when an object is in close proximity to the strip of conducting material
Data Source
AI summary
Embodiments of a system for reducing injury from pinch zones in adjustable-height work surface assemblies are shown, the system including a desk surface; one or more adjustable-height legs, a controller for the adjustable-height legs; a Hall-effect sensor providing a signal to the system corresponding to a current draw of a motor in the adjustable height leg and wherein the system disables the motor if the current draw of the motor exceeds a fixed set point; and a proximity detection sensor being a strip of conducting material disposed adjacent to a perimeter of the desk surface and in electrical connection with an LC tank circuit, wherein the LC tank circuit is configured to exhibit a change in state when an object is in close proximity to the strip of conducting material and wherein the system disables the motor when the LC tank circuit exhibits the change in state.