Tilting Backrest Joint Geometry to Prevent Clothing Displacement
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Solution Overview
Problem
Existing chair designs with tilting backrests experience a mismatch between the center of rotation of the backrest and the user's back, leading to relative movement and clothing displacement during backward tilting, such as shirts being pulled out of trousers.
Innovation Solution
A chair with a tilting backrest connected via side joints comprising inner and outer curved components in a telescopic arrangement, with a helical compression spring and preload component, ensuring the tilting axis aligns with the user's back and preventing excessive tilting through a guided sliding mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the backrest is connected by simple elastic components, then the structure is simple and economical, but the center of rotation does not align with the user's back causing clothing displacement
Solution Approach 1:
The patent employs curved components with specific radii of curvature in the telescopic joint mechanism. The inner curved component and outer curved component have precisely calculated curvature radii that ensure the backrest's center of rotation aligns with the user's back center during tilting movement, eliminating relative movement and clothing displacement while maintaining a simple elastic structure.
Solution Approach 2:
The patent optimizes geometric parameters of the telescopic joint, specifically the curvature radii of the inner and outer curved components, and the distance between their centers. By carefully selecting these parameters, the mechanism achieves proper alignment of rotation centers without increasing structural complexity, resolving the contradiction between simplicity and comfort.
2Adaptability or versatility
If elastic components are used to allow backward tilting, then the tilting movement is enabled, but excessive tilting occurs without proper constraint
Solution Approach 1:
The telescopic joint acts as an intermediary mechanism between the backrest and base structure. It mediates the tilting movement by allowing controlled backward rotation while preventing excessive tilting through its mechanical geometry. The joint transforms the user's backward push into a controlled rotational movement around the aligned center of rotation.
Solution Approach 2:
The curved geometry of the telescopic joint components provides inherent mechanical constraints on the tilting angle. The specific curvature radii and center distances create a natural stop point for backward tilting, ensuring the backrest returns to the vertical position without requiring additional active control mechanisms.
3Ease of operation
If curved components with telescopic arrangement are used, then the center of rotation aligns with user's back, but the manufacturing precision requirements increase
Solution Approach 1:
The patent provides specific numerical values for the geometric parameters of the curved components, including curvature radii and center distances. By specifying these parameters, the invention balances the need for precise alignment with practical manufacturing capabilities, achieving center of rotation alignment without requiring extreme manufacturing precision.
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 solution provides a simple, economical, and effective tilting mechanism that aligns the backrest's center of rotation with the user's back, minimizing clothing displacement and enhancing user comfort during backward tilting.
Implementation Method 1
the return from the tilted position back to the rest position takes place by effect of elastic means integrated into the side joints 26
Implementation Method 2
a helical compression spring
Data Source
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AI summary
Chair comprising: - a base structure (12) bearing a seat (14), - a tilting backrest (16), and - at least one joint (26) which connects the backrest (16) to the base structure (12) and allows a movement of the backrest (16) between a rest position and a backward tilted position under a backwards push applied by the user, wherein said joint (26) comprises a first and a second curved component (28, 30) with a circular profile coupled together in a telescopic manner and fixed to the base structure (12) or to the seat and, respectively, to the backrest (16).