Retractable Blind Assembly with Single-Cord Self-Leveling Deployment

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing retractable blind assemblies with angled head rails face issues such as separation of middle and bottom rails during deployment, incomplete deployment, and the need for precise cord length adjustments, leading to potential damage and complexity.

Innovation Solution

A retractable blind assembly with a single lift cord routed in a loop between the head, middle, and bottom rails, allowing staged deployment and self-leveling of the middle and bottom rails, reducing the risk of separation and simplifying installation by eliminating the need for precise cord length adjustments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If two cords are used to deploy the top shade, then the top shade can be deployed, but the lower rail may become separated from the middle rail before the middle rail reaches the horizontal

Engineering Contradiction:
Improvedeployment reliabilityVSAvoidcord arrangement complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the deployment function of both the top shade and bottom shade into a single cord system. The single cord is routed through the middle rail and bottom rail, allowing both sections to be deployed simultaneously in a coordinated manner, eliminating the separation issue that occurs with independent cord systems

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The single cord acts as an intermediary element that coordinates the movement between the middle rail and bottom rail. By routing the cord through both rails and using it to deploy both shades, the system ensures synchronized deployment without requiring separate control mechanisms for each rail

Inventive Principle:
Principle #24Intermediary (Mediator)

2Manufacturing precision

If two lift cords are used, then the middle rail can be positioned, but the lengths of the cords must be precisely adjusted relative to each other to ensure the middle and lower rails are level

Engineering Contradiction:
Improverail levelnessVSAvoidinstallation complexity
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The single cord system is designed to self-level the rails through its routing configuration. As the cord is pulled to deploy the shades, the geometry of the cord path through the middle and bottom rails automatically ensures they reach the correct horizontal position, eliminating the need for manual length adjustments during installation

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent changes the deployment parameter from two independent cord lengths requiring precise adjustment to a single cord length that automatically determines the position of both rails. This parameter change simplifies the installation process while maintaining the required levelness through the inherent geometry of the single cord routing

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP4219877B1Retractable blind assembly
Publication Date: 2025.07.09 HUNTER DOUGLAS IND BV
  • EP4219877B1 patent drawingFigure 1A~1B
  • EP4219877B1 patent drawingFigure 1C
  • EP4219877B1 patent drawingFigure 2

AI summary

The present invention provides a retractable blind assembly including a covering material, a fixed inclined head rail and a middle rail that is pivotable with respect to the head rail. The head rail extends upwardly at an acute angle. The middle rail is pivotable between a top deployed position and a retracted position. The retractable blind assembly also includes a bottom rail. The bottom rail is movable vertically between a bottom deployed position and the top deployed position. The retractable blind assembly has a single lift cord configured to raise and lower the bottom rail to retract and extend the covering material. The single lift cord is routed in a single lift cord loop from the head rail, through the middle rail and the bottom rail, and back to the head rail.