Flexible Arcuate-Band Chair Back for Passive Posture Adjustment
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Solution Overview
Problem
Traditional task chairs require complex mechanisms for adjusting seating positions, which can be cumbersome and do not easily accommodate the varied postures and movements needed for healthier working practices, especially in environments where workers frequently change between sitting and standing.
Innovation Solution
A chair back design featuring resiliently flexible arcuate bands that connect the backrest to the seat, allowing for self-adjustment of seating postures from upright to reclined without traditional pivot points or mechanisms, using elastic materials that deform under user weight to change the backrest angle and return to an upright position when unloaded.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional mechanisms with pivot points, springs and tensioners are used beneath the seat pan to control backrest movement, then the backrest can be adjusted to different positions, but the device complexity increases and the ease of operation deteriorates due to cumbersome adjustment requirements
Solution Approach 1:
The patent removes the traditional complex mechanism (pivot points, springs, tensioners) from beneath the seat pan and extracts only the essential function of backrest positioning. The backrest is simplified to a rigid lever that rotates freely, eliminating unnecessary mechanical components while maintaining the core functionality of position adjustment.
Solution Approach 2:
The system uses the user's own weight and natural movements to automatically adjust and maintain backrest position. When the user leans forward or shifts weight, the backrest spontaneously moves to the appropriate angle without requiring manual operation of adjustment mechanisms. The elastic element provides automatic locking and unlocking based on user posture changes.
2Adaptability or versatility
If traditional mechanisms with multiple adjustment controls are used to accommodate varied postures and movements, then seating position adaptability improves, but the ease of operation worsens due to multiple adjustment requirements
Solution Approach 1:
The backrest automatically adapts to user needs through natural body movements. When a user leans forward to type or reaches back to stretch, the backrest passively follows these movements and maintains the new position through the elastic element's locking action, eliminating the need for conscious adjustment operations.
Solution Approach 2:
The system transitions from static fixed-position mechanisms to a dynamic response system. The backrest continuously adapts its angle in real-time based on user posture changes, providing seamless transition between working positions without discrete adjustment steps or controls.
3Ease of operation
If elastic elements are used to provide spontaneous backrest adjustment, then the ease of operation improves, but the reliability may worsen due to dependence on user weight and movement
Solution Approach 1:
The elastic element acts as a feedback mechanism that continuously monitors user posture through weight distribution changes. When the user shifts position, the elastic element detects the change in load and automatically adjusts the backrest angle to maintain optimal support, providing continuous adaptive feedback without electronic sensors.
Solution Approach 2:
The elastic element is pre-tensioned to provide immediate resistance against unwanted backrest movement. This preliminary counter-force ensures that the backrest remains stable during normal use while still allowing spontaneous adjustment when deliberate user movement occurs, preventing both over-adjustment and stuck positions.
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 continuous, self-adjusted sitting with various postures from reclined to upright, requiring only a single height adjustment lever, promoting ergonomic flexibility and comfort without the need for complex mechanisms, while maintaining structural integrity and ease of use.
Implementation Method 1
the lower section is formed from a pair of resiliently flexible arcuate bands... elastic materials that deform under user weight to change the backrest angle and return to an upright position when unloaded
Data Source
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AI summary
A chair back (2) comprising an upper back rest section (2), and a lower section (30) adapted to support the back rest section (2) relative to a chair seat (14), wherein the lower section (30) comprises a pair of resiliently flexible arcuate bands (4).