Screen Rail Coupling Mechanism Prevents Cord Entanglement
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Solution Overview
Problem
Existing window screen systems with multiple control units face issues of cord entanglement and loss of tension due to simultaneous movement of middle and bottom rails in the same plane, leading to operational failures.
Innovation Solution
A shaft rotation limiting system with a threaded shaft and toothed nut coupling mechanism that maintains a minimum distance between the middle and bottom rails, preventing cord entanglement by ensuring the rails move in a coordinated manner, with the toothed nut engaging and disengaging based on rail positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the middle rail and bottom rail are allowed to move independently in the same plane, then each rail can be controlled separately for flexible operation, but the lift cords will lose tension and become entangled resulting in knots
Solution Approach 1:
A coupling element is introduced as an intermediary mechanism between the first and second drive shafts. This coupling element synchronizes the rotation of both shafts, ensuring that the middle rail and bottom rail maintain a minimum distance during operation. The coupling element acts as a mediator that coordinates the independent control operations while preventing cord entanglement through synchronized movement.
Solution Approach 2:
The system dynamically adjusts the relationship between the two rails through the coupling mechanism. The coupling element allows the drive shafts to rotate in a coordinated manner, creating a dynamic synchronization that maintains the minimum distance requirement between rails during various operational states, preventing cord slack and entanglement.
2Adaptability or versatility
If the middle rail is lowered while the bottom rail remains stationary, then the middle rail can be positioned independently, but the middle rail will abut the bottom rail and the cords will lose tension
Solution Approach 1:
The coupling element provides mechanical feedback between the two drive shafts. When one shaft rotates to move a rail, the coupling element transmits this rotational information to the other shaft, ensuring coordinated movement. This feedback mechanism prevents the middle rail from abutting the bottom rail by synchronizing their positions, thereby maintaining cord tension.
Solution Approach 2:
The coupling element performs preliminary coordination before the rails reach positions that would cause cord slack or entanglement. By synchronizing the rotation of both drive shafts in advance, the system prevents the middle rail from abutting the bottom rail and maintains proper cord tension throughout the operation.
3Ease of operation
If the bottom rail is raised while the middle rail remains stationary, then the bottom rail can be repositioned independently, but the bottom rail will drag the middle rail along and the cords will become entangled
Solution Approach 1:
The coupling element serves as a mediator that prevents the bottom rail from dragging the middle rail during independent operation. By synchronizing the rotation of both drive shafts, the coupling element ensures that when the bottom rail moves, the middle rail moves in a coordinated manner, preventing cord entanglement while maintaining independent control capability.
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 system effectively prevents cord entanglement and maintains tension, ensuring smooth operation of the screen by ensuring the middle and bottom rails maintain a minimum distance, thus preventing operational failures.
Implementation Method 1
a shaft rotation limiting system comprising a threaded shaft arranged on and rotatable in unison with one of the first and the second drive shafts and a coupling element threaded on said threaded shaft
Implementation Method 2
The shaft rotation limiting system further comprises a toothed shaft arranged on and rotatable in unison with the other drive shaft, wherein the coupling element is a toothed nut that is in continuous engagement with the toothed shaft
Data Source
AI summary
The invention relates to a screen, comprising a first control unit (610) comprising a first drive shaft (612) and at least one first cord spool (630) rotatable with the first drive shaft for winding and unwinding a first lift cord (634) extending between a head rail and a middle rail;a second control unit (620) comprising a second drive shaft (622), and at least one second cord spool (632) rotatable with the second drive shaft for winding and unwinding a second lift cord (636) extending between the head rail and the bottom rail;and a shaft rotation limiting system (100) comprising a threaded shaft arranged on and rotatable in unison with one of the first and the second drive shafts, a coupling element threaded on said threaded shaft, wherein the coupling element is associated with and rotatable in unison with the other drive shaft.