Concave Bottom Rail for Cordless Blinds
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Solution Overview
Problem
Existing bottom rails for cordless blinds are difficult to grasp securely, leading to slippage and increased effort when raising or lowering the blind, and may detract from appearance and increase cost with added handles or mechanisms, while also posing child safety concerns due to cord entanglement risks.
Innovation Solution
A bottom rail with a concave front and rear face provides comfortable gripping areas, optionally hollow with longitudinal stiffening ribs and end caps, and can include weights for counterbalancing spring motors, enhancing security and ease of use without external handles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a flat front surface and flat rear surface are used on the bottom rail, then the manufacturing is simple, but the hand of an operator can easily slip from the bottom rail
Solution Approach 1:
The patent applies curvature by forming concave gripping surfaces on the front and rear of the bottom rail, replacing flat surfaces with curved contours that conform to the operator's hand shape. This curvature provides mechanical interlocking and friction enhancement, preventing slippage during operation without adding external handles or complex mechanisms.
2Ease of operation
If cylindrical bottom rails are used, then they are easier to grasp, but they are easily dislodged when the shade is in a fully lowered position
Solution Approach 1:
The patent applies local quality by providing concave gripping surfaces only at specific locations (front and rear) of the bottom rail, while maintaining a different profile elsewhere. This localized curvature provides easy grasping where needed, while the overall cylindrical or slightly tapered shape maintains stability when resting on the window sill, avoiding the dislodgement issue of fully cylindrical rails.
3Ease of operation
If short handles are attached to the bottom rail, then grasping is easier, but they detract from appearance and add to cost
Solution Approach 1:
The patent merges the gripping function directly into the bottom rail body by forming concave surfaces as integral parts of the extrusion. This eliminates the need for separate attached handles, reducing the number of parts, simplifying assembly, lowering cost, and maintaining a clean aesthetic appearance while still providing comfortable grasping surfaces.
4Force
If pull rod mechanisms are added to the bottom rail, then pulling down is easier, but they detract from appearance and increase cost
Solution Approach 1:
The patent extracts the mechanical advantage function from external pull rod mechanisms and integrates it directly into the bottom rail structure through the concave surface geometry. The shaped surfaces provide mechanical interlocking and friction that naturally assist in gripping and pulling down, eliminating the need for separate pull rods, clips, or storage mechanisms while maintaining aesthetic appearance.
Data Source
AI summary
A bottom rail for a cordless blind has an elongated body having a bottom, a top spaced apart from and substantially parallel to the bottom, a concave front face connected between the bottom and the top and a concave rear face connected between the bottom and the top. The concave surfaces provide comfortable gripping areas enabling a user to easily grasp the bottom rail and raise or lower the cordless blind.