Adjustable Ergonomic Postural Chair With Passive Tibial Constraint
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Solution Overview
Problem
Existing ergonomic chairs fail to maintain a correct sitting posture without requiring user collaboration, leading to muscle fatigue and incorrect postures over time.
Innovation Solution
An ergonomic chair design with adjustable backrest and seat inclination, combined with a lumbar support and tibial constraint, to maintain a predetermined posture without user effort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional chairs are used, then simplicity and low cost are maintained, but they create points pressing on the hip bones, coccyx and legs, imposing an incorrect sitting position that leads to discomfort and back pain
Solution Approach 1:
The chair is divided into multiple functional segments: a seat with specific geometry, a backrest with adjustable lumbar support, and a footrest with tibial constraint. Each segment independently addresses specific anatomical needs, transforming the monolithic traditional chair into a modular system that distributes support forces appropriately across the user's body.
Solution Approach 2:
Different parts of the chair provide specialized local support: the seat geometry supports the ischial tuberosities, the lumbar support targets the lower back curvature, and the footrest constrains the tibial region. This localized quality of support replaces the uniform, harmful pressure points of traditional chairs with targeted, beneficial support at each anatomical region.
2Reliability
If ergonomic chairs with adjustable backrest and lumbar support are used, then spine support is improved, but they still require user collaboration to maintain correct posture, leading to muscle fatigue over time
Solution Approach 1:
The chair is designed to automatically maintain correct posture through its mechanical structure without requiring active user effort. The seat geometry, backrest inclination, and footrest constraint work together to passively enforce the predetermined sitting angle, allowing the chair to 'serve itself' by continuously guiding the user into the correct position without muscle engagement.
Solution Approach 2:
The chair incorporates adjustable components that can adapt to different users and situations. The backrest inclination and footrest position can be modified to create different predetermined sitting angles, making the system dynamically adaptable while maintaining the core principle of passive posture enforcement.
3Ease of operation
If the user leans forward to write, then writing comfort is improved, but the back inclination varies towards an incorrect posture and the backrest does not provide effective ergonomic support
Solution Approach 1:
The footrest with tibial constraint is merged with the seat and backrest system to create an integrated posture control mechanism. This additional constraint element works in conjunction with the backrest to maintain the predetermined sitting angle even when the user leans forward, combining multiple support functions into a unified system that preserves ergonomic integrity during dynamic use.
4Reliability
If kneeling chairs are used, then pelvis rotation and lumbar curvature are improved, but they require continuous user collaboration to maintain posture, which becomes tiring and fails in the long term
Solution Approach 1:
The chair automatically maintains the correct lumbar curvature and pelvis rotation through its mechanical design, eliminating the need for continuous user collaboration. The seat geometry and backrest configuration passively enforce the correct posture, allowing the chair to maintain lumbar curvature support without requiring the user to actively engage lumbar muscles.
Data Source
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AI summary
An ergonomic postural chair (1) to keep a user in a correct sitting position, comprising a seat (8), front constraint means (5), a lumbar support (4) and a backrest (3), the position thereof is adjustable to each other. The front constraint means (5) prevents the user from moving her/his thighs forward and from assuming an incorrect position, whereas the lumbar support (4) follows the physiological curvature of lumbar lordosis. A support base (6) of the chair (1) on the floor is further provided, comprising movement wheels (6c).