Reversible Transmission for Architectural Coverings with Single Operating Element
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Solution Overview
Problem
Conventional window covering operating systems require users to choose the direction of the operating element, leading to confusion, especially when elements are tangled, and often feature long operating elements that pose a strangulation hazard, particularly for children. Additionally, these systems lack compatibility with all window covering systems and could benefit from improved operational smoothness and dependability.
Innovation Solution
A control system for roller tube retractable coverings that uses a single reciprocally movable operating element, allowing users to raise or lower the covering by imparting a repetitive up and down motion. This system includes an input assembly, a reversible transmission, and an output assembly, which converts linear motion into rotational motion of the head roller, enabling automatic retraction of the operating element and providing a braking feature to hold the covering in place.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a long operating element is used to raise or lower the shade or blind, then the operating range is improved, but the strangulation hazard to children increases
Solution Approach 1:
The patent extracts the operating element from the traditional long-cord configuration and replaces it with a compact drum mechanism housed within the head rail. The operating element becomes a short, contained component that rotates on the drum rather than extending as a long external cord, thereby maintaining operational functionality while eliminating the strangulation hazard associated with long exposed cords.
Solution Approach 2:
The operating element is nested within the head rail assembly, with the drum mechanism contained inside the housing. The cord or chain is wound around the drum and stored within the head rail when not in use, creating a compact integrated system that eliminates the need for long external operating elements while preserving the full range of motion for raising and lowering the covering.
2Ease of operation
If a looped operating element is used, then ease of operation is improved, but device complexity and tangling risk increase
Solution Approach 1:
Instead of using a looped cord that requires the user to pull in different directions to change operation mode, the patent inverts the approach by using a single-ended operating element attached to a drum. The user always pulls in the same direction (downward), and the drum's rotation direction is controlled by the direction of pull, simplifying the user interface while maintaining full functionality.
Solution Approach 2:
The drum acts as an intermediary mechanism between the user's linear pull on the operating element and the rotational motion required to raise or lower the covering. This intermediary converts the simple linear pulling motion into controlled bidirectional rotation, eliminating the need for looped cords or complex switching mechanisms while maintaining ease of operation.
3Device complexity
If a single operating element is used for both raising and lowering, then device complexity is reduced, but operational smoothness may worsen
Solution Approach 1:
The patent employs a dynamic transmission mechanism that automatically adapts its gear ratio based on the direction of drum rotation. When the drum rotates in the raising direction, the transmission engages a higher gear ratio to provide mechanical advantage for lifting the heavy covering. When rotating in the lowering direction, it switches to a lower gear ratio for smoother, more controlled descent, thereby maintaining operational smoothness while using a single operating element.
Solution Approach 2:
The transmission system changes its mechanical parameters (gear ratio) dynamically based on the operational direction. This parameter change allows the system to optimize performance for each direction: higher mechanical advantage for raising and lower mechanical advantage for lowering, ensuring smooth operation in both directions while maintaining a simple single-element control interface.
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 allows for seamless operation in both directions with reduced risk of tangling and strangulation hazards, enhances compatibility with various window covering systems, and improves operational smoothness and dependability by automatically retracting the operating element and providing a mechanical advantage for efficient movement.
Implementation Method 1
The transmission is operative to translate rotation of the first motion transfer element in the first direction into rotation of a second motion transfer element through at least one planet gear rotatably connected with a planet carrier.
Implementation Method 2
The input assembly includes a braking element adapted to brake the planet carrier to cause rotation of the second motion transfer element in the second direction
Implementation Method 3
The input assembly includes a spool around which the operating element is wrapped, a biasing element, and a shift arm. The spool is rotatably mounted on a first axle and adapted to storably receive the operating element.
Data Source
AI summary
A retractable covering for an architectural opening is reversibly driven through an input assembly, a transmission and an output assembly by a reciprocal operating cord that can be pulled down by an operator and will automatically retract while the covering is held in a predetermined position. While the input assembly is always driven in a first direction, a transmission is shifted between two operative positions through movement of a shift arm depending upon the positioning of the shift arm by the operating cord. The shift arm is pivotal about an axis parallel with a roller for the covering and when the operating cord is pulled straight downwardly, the covering is moved in an upwardly or retracting direction while if the operating cord is pulled downwardly and toward the operator, i.e. away from the architectural opening, the covering is driven in a downwardly or extending direction.