Forward-Leaning Chair Design for Active Posture and Low Muscle Tension
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Solution Overview
Problem
Conventional sitting furniture often fails to provide an ergonomically optimal and active sitting position, leading to muscle tension and reduced cognitive engagement, especially during prolonged use like computer work or gaming, where comfort and ergonomic benefits are not adequately met.
Innovation Solution
A chair design featuring a seat that inclines the femur bone at least 40° anteriorly, a lower leg support for the anterior legs, and a chest support that encourages a forward leaning position, with the third lumbar vertebrae in a support plane perpendicular to the sagittal plane, promoting an active and relaxed posture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional office chairs are designed with multiple configuration possibilities for seat height and angle, back support, and suspension, then the adaptability to different users is improved, but the device complexity increases
Solution Approach 1:
The patent applies parameter changes by defining specific geometric parameters for the seat (inclination angle α between 5-15 degrees, depth 400-600mm, width 400-600mm) and support surface positions to achieve ergonomic optimization without requiring multiple adjustable configurations. This fixed-parameter approach resolves the contradiction by providing adaptability through precise design rather than through adjustability mechanisms.
2Productivity
If conventional sitting furniture is designed to encourage an active, forward-leaning sitting position, then the cognitive engagement and reaction times are improved, but the comfort for prolonged use deteriorates
Solution Approach 1:
The patent changes the geometric parameters of the sitting furniture to achieve an optimal balance between active posture and comfort. The seat is inclined at angle α (5-15 degrees) to encourage forward leaning and active posture, while the back support surface is positioned at angle β (20-40 degrees) and the lower leg support at angle γ (10-30 degrees) to distribute body weight ergonomically. This parameter optimization allows the user to maintain an active sitting position during prolonged use without excessive muscle tension, thus improving both cognitive engagement and comfort.
Solution Approach 2:
The patent segments the support functions into three distinct components: seat (for buttocks and posterior thigh), back support surface (for lumbar region and chest), and lower leg support (for anterior lower legs). This segmentation allows each component to be optimized for its specific function, enabling the chair to promote active posture while maintaining comfort through targeted support at key anatomical points.
3Reliability
If the seat is designed to incline the femur bone at least 40° anteriorly, then the ergonomic benefit is improved, but the ease of manufacture deteriorates
Solution Approach 1:
The patent specifies the seat inclination angle α within the range of 5-15 degrees, which achieves the ergonomic benefit of femur bone inclination without requiring extreme angles that would complicate manufacturing. The back support surface angle β (20-40 degrees) and lower leg support angle γ (10-30 degrees) are also defined within manufacturable ranges. These parameter specifications ensure ergonomic effectiveness while maintaining ease of manufacture through standard woodworking and assembly processes.
Data Source
AI summary
Sitting furniture (100) comprising a seat (110), a lower leg support (120) and a chest support (130). The invention is characterised in that the seat (110) is arranged to support the posterior thigh (11) and/or buttocks (12) of a seated user (10) such that the femur bone (13) of the seated user (10) is downwards inclined in the anterior direction at an angle of at least 40° downwards in relation to the horizontal, in that the lower leg support (120) is arranged to support the anterior side of the lower legs (14) of the seated user (10), and in that the chest support (130) is arranged to support the chest (15) of the seated user (10) in a forward leaning position of the seated user (10) such that the third lumbar vertebrae body (16) of the seated user (10) is arranged in a support plane (150), which support plane (150) is perpendicular to the sagittal plane of the user and in which support plane (150) the respective pivot point (17) of the seated user's (10) hip joints and the respective pivot point (18) of the seated user's (10) shoulder joints are also arranged when the posture of the seated user (10) is symmetric about the seated user's (10) sagittal plane.