Blind Cord Drive Position Sensing Without Mechanical End Stops
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Solution Overview
Problem
Existing electric drive units for blinds experience issues with mechanical stress on cords and mechanical components due to high torque at the wound up end position, leading to cord weakening over time, and require mechanical adjustments to change the end position.
Innovation Solution
An electric drive unit with a DC motor and control circuitry that uses rotation detection sensors to control the motor based on the time development of detected passages, allowing for adaptive winding and unwinding without mechanical means, reducing stress on cords and enabling easy adjustment of the wound up end position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If mechanical means (abutment) are used to define the wound up end position, then the position is precisely defined, but the cords and mechanical components experience high stress and torque leading to reduced reliability
Solution Approach 1:
The patent replaces the mechanical abutment-based position definition system with an electronic control system using rotation detection sensors. The control unit determines the wound up end position by detecting the number of rotations of the cord winding/unwinding unit, eliminating the need for mechanical contact between the blind and abutment. This substitution removes the harmful mechanical stress and torque that caused reliability issues while maintaining precise position definition through electronic counting of rotations.
2Ease of operation
If mechanical abutment is used to stop the winding process, then the end position is mechanically enforced, but changing the end position requires mechanical adjustments increasing device complexity
Solution Approach 1:
The patent implements a dynamic end position definition system where the wound up end position can be changed by modifying the programmed number of rotations in the control unit, rather than requiring physical repositioning of mechanical abutments. The control unit stores and processes the rotation count parameter, allowing flexible adjustment of the end position through electronic programming. This dynamic approach eliminates mechanical adjustments while maintaining ease of operation.
Solution Approach 2:
The patent changes the defining parameter of the end position from a fixed mechanical dimension (abutment position) to a programmable rotational parameter (number of rotations). By controlling the cord winding/unwinding unit based on detected rotation increments, the system allows the end position to be adjusted by changing the rotation count parameter in the control unit, simplifying the overall device structure while maintaining operational flexibility.
3Manufacturing precision
If the blind hits against mechanical means to reach the wound up end position, then the position is accurately achieved, but the cords experience repeated stress leading to weakening over time
Solution Approach 1:
The patent replaces the mechanical impact-based position achievement method with an electronic rotation-counting method. The control unit monitors rotation increments detected by the rotation detection sensor and stops the cord winding/unwinding unit when the predetermined number of rotations is reached, without requiring the blind to physically hit or strike against any mechanical component. This eliminates repeated stress on the cords while maintaining accurate end position achievement through electronic control.
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 reduces mechanical stress on blinds and components, extends cord lifespan by avoiding high torque at a fixed position, and allows for effortless reconfiguration of the wound up end position without mechanical adjustments.
Implementation Method 1
The control circuitry is functionally connected to one or more rotation detection sensors, each rotation detection sensor being arranged for detecting increments of the rotation of the electric motor by cooperating with a rotating element driven by the electric motor
Data Source
AI summary
Electric drive unit (104) for cords of blinds, comprising:a DC driven electric motor (106),a cord winding/unwinding unit (107) driven by the electric motor (106), for winding/unwinding one or more cords (102a) of a blind (103),a control circuitry (105) arranged for controlling the operation of the electric motor (106) by controlling the DC supply of the electric motor (106),the control circuitry (105) being functionally connected to one or more rotation detection sensors (108), each rotation detection sensor (108) being arranged for detecting increments of the rotation of the electric motor (106) by cooperating with a rotating element (109) driven by the electric motor (106), the rotating element (109) having at least two discrete elements (110), wherein the passage of which is detected as detection pulses by the one or more rotation detection sensor (108), characterized in that the control circuitry (105) is arranged for controlling the electric motor (106) dependent on the time development of the detected passages.