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, elastomeric membranes lacking shear resistance, and plastic shells not conforming to the body.
Innovation Solution
A compliant backrest design featuring a flexible shell with a three-dimensional shape, including a peripheral frame with slots and openings for expansion, and an auxiliary body support member that can move along the shell, providing both macro and micro compliance for body-conforming support and air circulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If foam materials are used for backrest support surfaces, then comfort and body conforming are 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 cushioning and body-conforming 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 reinforcing structure or composite layering approach. The elastomeric membrane provides air circulation and flexibility, while the composite construction adds shear resistance through layered materials or integrated reinforcement elements, resolving the contradiction between air circulation and shear resistance.
3Strength
If plastic shells are used for backrest support surfaces, then structural integrity and shear resistance are improved, but body conforming capability is reduced
Solution Approach 1:
The backrest uses a plastic shell with locally varied properties - thicker and stiffer in regions requiring structural integrity and shear resistance, while thinner and more flexible in regions that need to conform to the body. This non-uniform construction allows the single plastic shell material to simultaneously provide both structural support and body conforming capability.
4Strength
If a peripheral frame is used to bound the backrest, then structural integrity is improved, but compliance and adaptability are reduced
Solution Approach 1:
The peripheral frame is designed with segmented or articulated connections rather than rigid fixed joints. The frame may include flexible segments, hinges, or elastic elements that allow controlled movement and deformation, enabling the framed structure to adapt to body contours while maintaining overall structural integrity through the frame's geometric configuration.
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 allows the backrest to adapt to the user's shape while maintaining structural integrity, providing excellent air circulation and shear resistance, ensuring comfort and support.
Implementation Method 1
The shell includes first and second slots extending longitudinally along opposite sides of the shell inboard of locations where the shell is connected to the upright members, and one or more third slots extending laterally along the lower portion of the shell
Implementation Method 2
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
Data Source
Figure 1A~1B
Figure 1C~2
Figure 3A~3B
AI summary
A backrest includes a frame having a pair of laterally spaced upright members connected with longitudinally spaced upper and lower members. A flexible shell has opposite sides coupled to the upright members and upper and lower portions coupled to the upper and lower members. The shell includes first and second slots extending longitudinally along opposite sides of the shell inboard of locations where the shell is connected to the upright members, and one or more third slots extending laterally along the lower portion of the shell above a location where the shell is connected to the lower member. The terminal ends of the one or more third slots are spaced apart from lower terminal ends of the first and second slots. In other embodiments, the shell is a three-dimensional molded component having a plurality of openings. In various embodiments, the slots and/or openings provide different levels of compliance to the backrest.