Window Blind Slat Closure via Movable Bottom Rail
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Solution Overview
Problem
Conventional window blinds experience light leakage due to slats not being able to close tightly when lowered, as the warps of the ladder tapes are restricted by the unmoving bottom rail, causing the lifting cords to tighten and leave gaps between slats.
Innovation Solution
The window blind design includes ladder tapes with two warps and horizontal strings supporting the slats, allowing the warps to move relative to the bottom rail, with one warp going up and the other down when the ladder drums are rotated, ensuring the slats can be tightly closed by synchronously rotating the direction-changing members and transmission shaft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the bottom rail is kept stationary during slat rotation, then the lifting mechanism remains simple, but the warps are restricted from approaching each other causing light leakage
Solution Approach 1:
The bottom rail is transformed from a stationary component to a movable one that rotates synchronously with the slats. This dynamic adjustment allows the warps to freely approach each other during slat rotation, eliminating the restriction that caused light leakage, while the movable bottom rail tracks the slat movement to maintain proper tension in the lifting cords.
2Object-affected harmful factors
If the warps are allowed to move freely during slat rotation, then light leakage is prevented, but the lifting cords may become loose or tangled
Solution Approach 1:
The bottom rail rotates synchronously with the slats through a transmission mechanism, dynamically adjusting its position to match the slat rotation angle. This synchronous movement ensures that the lifting cords remain properly tensioned throughout the rotation process, preventing them from becoming loose or tangled while allowing the warps to move freely for tight slat closure.
Solution Approach 2:
The transmission mechanism between the ladder drum and bottom rail creates a feedback system where the bottom rail's rotation is directly coupled to the slat rotation. This feedback ensures that the bottom rail continuously adjusts its position in response to slat movement, maintaining proper geometric relationships and cord tension throughout the operation.
Data Source
AI summary
A window blind includes a headrail, a bottom rail, and a plurality of slats. The slats are horizontally suspended between the headrail and the bottom rail through ladder tapes. Each ladder tape has two warps, wherein an end of the warps is connected to a ladder drum, and another end thereof passes through the bottom rail to be connected thereto. When the ladder drum is rotated, the ladder tapes could be pulled smoothly, and the slats supported by the ladder tapes could be tightly closed. Whereby, the window blind could provide a good shielding effect.