Single Pull Cord Roller Blind Drive Mechanism
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Solution Overview
Problem
Conventional roller blind systems using two pull cords are inconvenient and pose safety risks, particularly for children, as it is difficult to determine which cord is for forward or reverse rotation, leading to potential accidents due to cord entanglement.
Innovation Solution
A roller blind drive device operated by a single pull cord with a one-stage clutch structure, inclined roller protrusion parts for radial movement, and roller teeth on the drive connector to prevent slipping, ensuring precise power transmission and safety features like a guide wing for resistance control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If two pull cords are used for forward and reverse rotation, then the drum can be rotated in both directions, but it becomes difficult to determine which cord is for which direction and creates safety risks
Solution Approach 1:
The patent extracts the directional control function from the two-cord system and consolidates it into a single pull cord system. The single pull cord is connected to a drive manipulation part that includes a clutch mechanism, eliminating the need for two separate cords while maintaining bidirectional control capability.
Solution Approach 2:
The single pull cord serves multiple functions: it controls both forward rotation (to lower the curtain) and reverse rotation (to raise the curtain) through the clutch mechanism. The drive manipulation part acts as a universal control element that handles both directional operations through one cord.
2Object-affected harmful factors
If a single pull cord is used, then safety is improved and cord entanglement is prevented, but the mechanism for transmitting unidirectional rotational force becomes more complex
Solution Approach 1:
The drive manipulation part is segmented into distinct functional components: a clutch mechanism with clutch plates, springs, and levers. This segmentation allows each component to perform a specific function (engaging/disengaging, storing energy, transmitting force) while collectively achieving the overall control objective through a simple single-cord interface.
3Ease of manufacture
If a one-stage clutch structure is used, then manufacturing time is reduced, but the precision of power transmission may be compromised
Solution Approach 1:
The inclined roller protrusion parts are provided with specific local geometric features (inclined surfaces) at critical locations where contact with the drive rollers occurs. This local quality enhancement ensures precise radial movement control and reliable power transmission only where needed, without requiring the entire mechanism to be overly complex.
4Reliability
If roller teeth are formed on the drive connector, then slipping between drive rollers and connector is prevented, but manufacturing complexity increases
Solution Approach 1:
The roller teeth on the drive connector feature asymmetric inclined surfaces that engage with the drive rollers in a specific direction. This asymmetric geometry ensures reliable power transmission during the intended rotation direction while allowing easy disengagement or reverse operation, achieving both reliability and operational flexibility without excessive complexity.
Data Source
AI summary
Proposed is a roller blind drive device operated by a single pull cord which lowers or raises a curtain fabric by performing forward/reverse rotation of a drum, on which the curtain fabric is wound, by only the single pull cord, the drive device including a drive casing disposed fixedly on one side of the drum, a drive manipulation part mounted rotatably inside the drive casing and connected with the pull cord, and a drum control part mounted rotatably on an outer part of the drive casing and configured to receive a rotational force from the drive manipulation part and rotate the drum, the drum control part being configured to hold the drum or rotate the drum reversely when the rotational force of the drive manipulation part is blocked.