Compliant backrest
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Solution Overview
Problem
Conventional backrests in office chairs often fail to provide adequate support and air circulation, with foam limiting air circulation and elastomeric membranes lacking shear resistance, while plastic shells do not conform to the body effectively.
Innovation Solution
A compliant backrest design featuring a flexible shell with longitudinal and lateral slots and a matrix of openings that allows for independent expansion and contraction, providing both macro and micro compliance, and integrated with a peripheral frame for structural support.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If foam materials are used for backrest support surfaces, then support comfort is improved, but air circulation is limited
Solution Approach 1:
The backrest employs a foam material with an open-cell porous structure that allows air to circulate through the material. The pores are interconnected and sized to permit airflow while maintaining the foam's support and comfort properties, thus resolving the contradiction between comfort and air circulation.
2Object-generated harmful factors
If elastomeric membranes are used for backrest support surfaces, then air circulation is improved, but shear resistance is insufficient
Solution Approach 1:
The backrest combines elastomeric membrane material with a structural framework or reinforcement layer to create a composite structure. The elastomeric membrane provides air circulation and flexibility, while the framework or reinforcement adds shear resistance, thus resolving the contradiction between air circulation and shear resistance.
3Strength
If plastic shells are used for backrest support surfaces, then structural integrity is improved, but body conformability is reduced
Solution Approach 1:
The plastic shell backrest incorporates regions of varying thickness and flexibility, with softer, more compliant areas positioned to contact the user's body and harder, more rigid areas providing structural support. This local variation in material properties allows the backrest to conform to the body while maintaining overall structural integrity.
4Stability of the object's composition
If a rigid peripheral frame is used to bound the backrest, then structural stability is improved, but compliance and adaptability are reduced
Solution Approach 1:
The peripheral frame incorporates movable joints, hinges, or elastic elements that allow the frame to flex and adapt to user movement and body shape. The frame transitions from a completely rigid structure to a dynamic structure that can change its configuration, providing both stability and compliance.
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 design ensures the backrest conforms to the user, enhances air circulation, and supports auxiliary body members, offering improved comfort and adaptability while maintaining structural integrity.
Implementation Method 1
The shell has a plurality of openings arranged in an area overlying the central opening. The shell has flush front and rear surfaces in the area overlying the central opening. The plurality of openings is configured in one embodiment as a matrix of openings providing independent lateral and longitudinal expansion of the shell relative to the frame.
Implementation Method 2
The slots also serve to guide, and allow pass through of, an auxiliary body support member, for example and without limitation a lumbar support, which may be moved along a forwardly facing body support surface of the shell
Data Source
AI summary
A backrest includes a primary frame having a pair of laterally spaced first uprights defining a first opening therebetween, a first front surface and a first rear surface. A secondary frame includes a pair of laterally spaced second uprights defining a second opening therebetween, a second rear surface facing the first front surface of the primary frame and a second front surface, wherein the secondary frame is coupled to the primary frame, and wherein at least portions of the first and second openings are aligned. A flexible shell overlies and is coupled to the second front surface of the secondary frame. The flexible shell includes a third rear surface visible through the aligned portions of the first and second openings.