Elastomeric Chair Back Frame for Linkage-Free Reclining

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Solution Overview

Problem

Existing lounge chair designs either lack recline functionality, compromising comfort, or utilize expensive and bulky linkage systems that restrict design aesthetics.

Innovation Solution

A lounge chair design featuring a back frame with elastomeric members that allow the upper portion to recline without a mechanical linkage system, using elastomeric straps to maintain the reclined position without the need for expensive mechanisms, while allowing for various seating configurations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a mechanical linkage system is used to enable reclining, then user comfort and recline functionality are improved, but manufacturing cost and device complexity increase

Engineering Contradiction:
Improverecline functionalityVSAvoidlinkage system complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical linkage systems with elastomeric members (rubber or elastic elements) that provide the same recline functionality through elastic deformation. The elastomeric members connect the seat frame and back frame, allowing the back to recline when force is applied and return to upright position when force is removed, eliminating the need for linkages, levers, and mechanical joints.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The elastomeric members are configured to automatically return the back frame to its upright position after reclining, without requiring mechanical locks or additional actuating mechanisms. The elastic properties of the members provide automatic restoration, making the system self-servicing and eliminating complex position-maintaining mechanisms.

Inventive Principle:
Principle #25Self-service

2Ease of operation

If a mechanical linkage system is used to enable reclining, then user comfort is improved, but manufacturing cost increases

Engineering Contradiction:
Improverecline functionalityVSAvoidmanufacturing cost
Core Design Contradiction:
Ease of operationVSEase of manufacture

Solution Approach 1:

The patent uses inexpensive elastomeric members (rubber bands, elastic straps, or simple spring elements) instead of expensive mechanical linkage systems. These elastomeric components are much cheaper to manufacture and can be easily replaced if needed, significantly reducing the overall manufacturing cost while maintaining full recline functionality.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Ease of operation

If a mechanical linkage system is used to enable reclining, then recline functionality is improved, but design flexibility and aesthetic options are reduced

Engineering Contradiction:
Improverecline functionalityVSAvoiddesign aesthetics
Core Design Contradiction:
Ease of operationVSShape

Solution Approach 1:

The patent extracts the visible mechanical linkage components from the chair design, leaving only the elastomeric members which can be concealed within the frame structure or upholstered. This removal of external linkages allows for cleaner lines and greater freedom in designing the chair's aesthetic appearance without the constraint of visible mechanical parts.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The elastomeric members can be covered with fabric or integrated into the upholstery, allowing the recline mechanism to be aesthetically blended with the chair's exterior. This enables designers to create seamless appearances where the functional elements are hidden within the decorative surfaces.

Inventive Principle:
Principle #30Flexible shells and thin films

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 comfortable reclining without costly linkage systems, expanding design options and maintaining the reclined position without constant user input, enhancing user comfort and aesthetic flexibility.

Implementation Method 1

The one or more first elastomeric members are configured so that the upper portion of the back frame is moveable to a reclined position upon a first force acting on the upper portion of the back frame to move the upper portion and is also configured to maintain that position after the first force is removed until a second force is applied to the upper portion of the back frame to move the upper portion to a different position

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP2579745B1Article of furniture
Publication Date: 2015.03.18 KNOLL INC
  • EP2579745B1 patent drawingFigure 1
  • EP2579745B1 patent drawingFigure 2
  • EP2579745B1 patent drawingFigure 3

AI summary

An article of furniture (1) includes a base (2), a seat frame (12) supported by the base (2), and a back frame (11) attached to the seat frame (12). The back frame (11) includes an upper portion (13) and a lower portion (14). The upper portion (13) is connected to the lower portion (14) by at least one first elastomeric member such that the upper portion (13) is moveable relative to the lower portion (14). The upper portion (13) is moveable from an upright position to at least one reclined position. In some embodiments of the article of furniture (1), the at least one first elastomeric member is a strap composed of a polymeric material, such as, for example, a thermoplastic polyester elastomer or a polymeric material containing at least one elastomer. In some embodiments, the article of furniture (1) may be designed as a chair, a lounge chair, or an office chair.