Flexible Backrest Structure for Posture-Adaptive Armchairs

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Solution Overview

Problem

Prior art armchairs with posture-changing mechanisms are costly to manufacture and prone to malfunction, as they require complex mechanical hardware to accommodate different postures.

Innovation Solution

An upholstered armchair with a support frame featuring a rigid wooden framework encircled by elastic bands and upholstered with polyurethane foam, incorporating a plurality of flexural springs made of flat spring steel bars that provide elasticity and comfort, allowing the back to adapt to various postures without complex mechanical hardware.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If posture-changing mechanisms are added to armchairs to accommodate different postures, then adaptability is improved, but device complexity and manufacturing cost increase

Engineering Contradiction:

Improveposture adaptabilityVSAvoidmechanical hardware complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The backrest is designed with dynamic flexibility through elastic bands and flexural springs, allowing it to adapt to different postures without mechanical hardware. The elastic bands connect the backrest frame to the seat frame, enabling continuous adjustment as the user changes position, while the flexural springs in the upholstery provide additional compliance and comfort across varying angles.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The backrest's physical parameters (flexibility, elasticity) are changed through the selection of elastic materials and spring configurations. This allows the backrest to naturally assume different angles and positions based on user needs, achieving posture adaptability through material properties rather than mechanical adjustment mechanisms.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If posture-changing mechanisms are added to armchairs to accommodate different postures, then adaptability is improved, but manufacturing cost increases

Engineering Contradiction:

Improveposture adaptabilityVSAvoidmanufacturing cost

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

Complex mechanical posture-adjustment mechanisms are replaced with a system based on elastic bands and flexural springs. This substitution eliminates the need for motors, sensors, and control systems while achieving the same functional outcome through passive elastic deformation and spring compliance, significantly reducing manufacturing cost.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The backrest system is self-adjusting through the inherent elasticity of the bands and springs, requiring no external power source or control mechanism. The system automatically adapts to user posture changes through elastic deformation, eliminating the need for expensive actuation systems and control electronics.

Inventive Principle:

Principle #25Self-service

3Adaptability or versatility

If posture-changing mechanisms are added to armchairs to accommodate different postures, then adaptability is improved, but reliability decreases due to malfunctioning and failures

Engineering Contradiction:

Improveposture adaptabilityVSAvoidmechanical system reliability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

Active mechanical adjustment mechanisms with multiple moving parts, motors, and control systems are replaced with a passive elastic system. The elastic bands and flexural springs have no failure points related to actuation or control, eliminating common sources of malfunction while maintaining continuous posture adaptability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The elastic components and springs are simple, replaceable elements that can be easily replaced if worn, rather than complex mechanical assemblies that require disassembly and repair. This approach improves reliability by using simple, failure-resistant components that can be quickly replaced if needed.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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 armchair offers high comfort and versatility, allowing use as a conversation armchair, bergere, or lounge without expensive mechanical hardware, with the flexible back structure naturally fitting any user position and returning to its original shape when standing up.

Implementation Method 1

The support frame 5 of the back 3 comprises a plurality of springs 51a, 51b, 52a, 52b... 52n, 53, which have a flexural behavior and are attached to the support frame 4 of the seat 3. The flexural springs 51a, 51b, 52a, 52b, ...52n, 53 are incorporated in the upholstery of the back 3 and extend from bottom to top to about the upper edge of the back 3. By being attached to the support frame 4 of the seat 2, the flexural springs 51a, 51b, 52a, 52b, ...52n, 53 impart elasticity to the whole back 3, from the seat level to the upper end.

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentEP2363042B1Armchair

Publication Date: 2012.06.13 GIORGETTI

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Figure 1A
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AI summary

There is disclosed an upholstered armchair (1) comprising: - an upholstered seat (2), - an upholstered back (3), - a support frame (4) for said seat (2); - a support frame (5) for said back (3); wherein said support frame (5) of said back (3) comprises a plurality of torsion springs (51, 51, ... 51), attached to said support frame (4) of said seat (3).