Backrest Linkage Adjustment for Precise Chair Positioning
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Solution Overview
Problem
Conventional chairs with fixed backrests cannot be adjusted to accommodate users of different statures, causing inconvenience.
Innovation Solution
A backrest adjustment device featuring a bottom board, a movable support board, and pivotally mounted linkages with gear portions that mesh to change the distance between the support board and the bottom board, allowing for smooth and exact adjustment of the backrest's position relative to the seat.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the backrest is fixed on the seat, then the structure is simple and stable, but the position cannot be adjusted to accommodate users of different statures
Solution Approach 1:
The backrest is transformed from a fixed structure to a dynamically adjustable one through the linkage mechanism. The support board can move relative to the bottom board along the extension line of the linkage, enabling continuous position adjustment while maintaining structural integrity through the interconnected linkage system.
Solution Approach 2:
The adjustment mechanism is divided into distinct functional segments: the bottom board, the support board, and the linkage system with gear portions. This segmentation allows independent movement and adjustment of the support board while the bottom board remains stable, resolving the contradiction between adjustability and structural simplicity.
2Measurement precision
If the gear portions of the two linkages mesh with each other, then the two linkages are pivoted simultaneously to adjust the position smoothly and exactly, but the device complexity increases
Solution Approach 1:
The gear portions are integrated directly into the linkage components themselves rather than being separate elements. This merging of the driving mechanism into the linkages reduces overall device complexity while achieving synchronized pivoting of both linkages through the meshing gear portions, ensuring precise and smooth position adjustment.
3Length of moving object
If the two linkages co-operate with the two secondary linkages, then the travel between the support board and the bottom board is doubled, but the device complexity increases
Solution Approach 1:
The secondary linkages are positioned asymmetrically relative to the main linkages, creating a mechanical advantage that doubles the travel distance of the support board relative to the bottom board. This asymmetric arrangement of the linkage system achieves extended range of motion without requiring proportional increases in overall mechanism complexity.
Data Source
AI summary
A backrest adjustment device includes a bottom board, a support board movable relative to the bottom board, and two opposite linkages pivotally mounted between the support board and the bottom board to drive the support board to move relative to the bottom board to change the distance between the support board and the bottom board. Thus, the two linkages are pivoted to drive the support board to move relative to the bottom board to change the distance between the support board and the bottom board so as to adjust the position of the backrest relative to the seat.