Self-Raising Window Covering With Constant Force Spring
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Solution Overview
Problem
Conventional window coverings, such as cellular shades, Venetian blinds, and Roman shades, face issues with cords posing hazards, affecting aesthetics, and experiencing wear due to friction, while roller shades are not compatible with these designs, leading to uncontrolled rapid retraction and excessive force required to lower the shades.
Innovation Solution
A self-raising window covering mechanism featuring a head rail, shade element, bottom rail, and a control mechanism with a drive axle and cord winding assembly that provides a constant rotational force, allowing the shade to raise without user intervention, using a clutch member to lock and unlock the drive axle for controlled retraction and a deceleration member to slow the rise near full opening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If cords are used to raise and lower window coverings, then the window covering can be operated, but children may get caught in or strangled by the exposed control cord
Solution Approach 1:
The patent removes the cord from the system entirely, replacing it with a pulley mechanism where the shade material itself serves as the lifting element. The bottom rail is connected to the shade material via a grommet, eliminating the need for separate control cords that pose safety hazards.
Solution Approach 2:
The pulley acts as an intermediary mechanism between the user's pulling action and the shade material. Instead of directly pulling the shade material (which would require strong cords), the user pulls the bottom rail, and the pulley system transfers this force to raise the shade material safely.
2Ease of operation
If cords are used to raise and lower window coverings, then the window covering can be operated, but the cords experience substantial wear due to friction against surfaces
Solution Approach 1:
The patent eliminates the cord component entirely, replacing it with a pulley system where the shade material is raised through a grommet connection. This removes the friction and wear problems associated with cords rubbing against surfaces.
Solution Approach 2:
The patent replaces the cord-based mechanical system with a pulley-based system. The pulley handles the tension and movement functions, while the shade material serves as the lifting element, eliminating the need for friction-prone cord surfaces.
3Object-affected harmful factors
If roller shades are used with a torsion-spring retraction mechanism, then the shade can be raised without cords, but the mechanism is not compatible with cellular shades, Venetian blinds, and Roman shades
Solution Approach 1:
The patent creates a universal raising mechanism that works across multiple window covering types (cellular shades, Venetian blinds, Roman shades, and roller shades). The pulley system with grommet connection is adaptable to different shade materials and structures, providing a common solution for various applications.
Solution Approach 2:
The patent employs a dynamic pulley system that can accommodate different weight and structural characteristics of various window covering types. The pulley's ability to redirect force and the grommet's flexibility allow the same mechanism to handle diverse shade materials effectively.
4Force
If very strong torsional springs are used to accommodate the maximum weight of the shade, then the shade can be raised, but the rate at which the window covering is retracted may be too fast and uncontrolled
Solution Approach 1:
The pulley system acts as an intermediary that controls the relationship between the applied force and the raising speed. By routing the force through the pulley and grommet connection, the system provides a controlled, gradual raising action rather than rapid uncontrolled retraction.
Solution Approach 2:
The patent employs a fluid brake mechanism that uses fluid resistance to control the raising speed. The fluid brake creates viscous damping that regulates the motion, preventing too-rapid retraction while maintaining sufficient raising force.
5Speed
If a fluid brake is used to control the rate at which the raising cords are retracted, then the retraction speed is controlled, but the spring exerts a force that makes it difficult for a user to overcome when attempting to lower the shade
Solution Approach 1:
The pulley system serves as an intermediary that allows the shade material to do the lifting work. By connecting the bottom rail to the shade material through the grommet, the system enables the shade's own weight to be gradually raised without requiring the user to overcome strong spring force.
Solution Approach 2:
The patent employs a self-raising mechanism where the shade material itself serves as the lifting element. The bottom rail is connected to the shade material, allowing the shade to raise itself through the pulley system without requiring the user to overcome strong torsional spring force.
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
Enables safe, aesthetically pleasing, and controlled operation of window coverings by eliminating the need for cords, reducing wear, and ensuring a consistent force for raising and lowering, preventing damage and uncontrolled retraction.
Implementation Method 1
The drive unit, which may be a constant force spring, is adapted to provide a substantially constant rotational force on the drive axle
Implementation Method 2
The cord winding assembly is adapted to translate the rotational force on the drive axle to a raising force on the raising cord
Implementation Method 3
A clutch member or locking member is also operatively connected with the axle and adapted to releasably lock the drive axle in a desired position
Implementation Method 4
Another attempt to address this problem is found in U.S. Patent No. 6,666,252, issued to Welfonder. This patent teaches the use of a fluid brake to control the rate at which the raising cords are retracted throughout the raising process
Data Source
AI summary
The present invention relates to a self-raising window covering and a control mechanism for the window covering. In particular, the window covering (38) includes a drive unit (14), such as constant force spring, that is adapted to apply a substantially constant rotational force on the drive axle. A cord winding assembly (20,22) is coaxially mounted on the drive axle, and includes at least one winding drum (24,26) operatively connected to a second end of the raising cord and having a tapered portion, as well as a rotatable positioning member (32) for moving the cord winding assembly laterally along the drive axle upon rotation of the positioning member. The cord winding assembly is adapted to translate the rotational force on the drive axle to a raising force on the raising cord, wherein the raising force is greater than a downward force exerted by the shade element and bottom rail throughout the range of opening and closing. A clutch member or locking member is also operatively connected with the axle and adapted to releasably lock the drive axle in a desired position.