Cordless Window Shade Spring Drive Mechanism
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Solution Overview
Problem
Traditional spring boxes for cordless window shades are complex, large, and heavy due to multiple movable elements, and may not maintain the bottom rail at a desired height without proper torque, while also posing a risk of strangulation from operating cords.
Innovation Solution
A spring drive system comprising a housing, rotary members, a spring, and a latch, where the rotary members are rotationally linked and pivotally connected, with the spring biasing the rotary drum for winding the suspension member, and the latch allowing or preventing rotation of the drum, ensuring the bottom rail can be maintained at any vertical position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a traditional spring box is used to raise and lower the bottom rail, then the window shade can operate without cords, but the spring box becomes complex and requires multiple movable elements which increase the size and weight
Solution Approach 1:
The patent extracts and eliminates the operating cord from the window shade system, replacing it with a cordless spring drive mechanism. The spring box is designed to contain all necessary components internally, with only a simple release cord extending outward for user activation, thereby removing the strangulation hazard while maintaining functionality
Solution Approach 2:
The patent combines multiple functions into a single integrated spring box unit that houses the spring mechanism, rotary drum, suspension member, and release cord system together. This consolidation simplifies the overall structure compared to traditional separate components, reducing the number of movable elements while achieving cordless operation
2Power
If multiple movable elements are used in the spring box to transfer torque, then the torque can be transmitted to the rotary drum, but the size and weight of the spring box increase
Solution Approach 1:
The patent replaces complex multi-element mechanical torque transmission systems with a simplified direct-drive mechanism. The spring directly drives the rotary drum through a streamlined connection, eliminating the need for multiple intermediate movable elements, gears, or linkages, thereby reducing weight while maintaining effective torque transmission
3Device complexity
If the spring box is simplified to reduce size and weight, then the construction becomes less complex, but the bottom rail may not be kept at a desired height without proper torque
Solution Approach 1:
The patent incorporates a release cord mechanism that provides user feedback and control. When the user pulls the release cord, it triggers the spring mechanism to unwind and lower the bottom rail. The system responds to user input by adjusting the bottom rail position, allowing precise control while maintaining simplicity in the overall construction
Solution Approach 2:
The patent optimizes the spring parameters (coil density, wire diameter, free length) to provide the exact torque needed to hold the bottom rail at any desired height. By carefully selecting and adjusting spring parameters, the simplified construction achieves reliable position maintenance without requiring complex additional mechanisms
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 spring drive system effectively adjusts and maintains the window shade's bottom rail at any desired height, reducing complexity and size, and eliminates the risk of strangulation by eliminating the need for an operating cord.
Implementation Method 1
The spring is assembled with the housing, and can bias the rotary drum in rotation for winding the suspension member
Data Source
AI summary
A spring drive system for a window shade includes a housing, a plurality of rotary members, a spring and a latch. The rotary members are rotationally linked to one another and pivotally connected with the housing, wherein the rotary members include a rotary drum that is connected with a suspension member and is rotatable relative to the housing for winding or unwinding the suspension member. The spring is assembled with the housing, and can bias the rotary drum in rotation for winding the suspension member. The latch is assembled with the housing, the latch being movable to engage with and disengage from one of the rotary members to respectively prevent and allow rotation of the rotary drum.