負梯度扭力彈簧是無拉繩百葉窗機構能達到靜平衡的主要元件，目前無拉繩百葉窗的設計大都仰賴設計人員的經驗進行變負載靜平衡機構之調整，亦即透過改變施力方向及繩索纏繞方式使整體機構達到靜平衡的狀態，設計人員與彈簧製造商需不斷來回溝通及嘗試，因此開發時程長，開發經費亦高。為克服此問題，本研究針對無拉繩百葉窗設計靜平衡分析的實驗方法，來探討「百葉窗重量與繩索阻力」及「彈簧圈數與實際扭矩」的關係，前者是探討實際百葉窗受力狀況，針對繩索經轉向裝置產生之阻力進行分析與驗證，而後者是探討百葉窗作動過程中，負梯度扭力彈簧之扭矩隨圈數變化的趨勢。除了提出靜平衡分析的實驗方法外，本研究並據以開發無拉繩百葉窗機構設計的電腦介面，以協助設計者快速求得窗簾靜平衡所需之彈簧製造參數，以利縮短產品開發時間。

Gradient negative torsion springs are the main components used in cordless blinds to achieve static balance of the window blinds mechanism. Nowadays, the design of cordless blinds is mostly relied on the experience of the product designer to adjust the statically balanced mechanism with variable payloads by changing the load directions and the cord windings. The designer thus has to continuously discuss with the manufacturer, resulting in long development cycle time and high cost. To overcome this problem, this study proposes some experimental methods to analyze the static balance behavior of the cordless blinds so that the following two relationships can be found: (1) the relationship between the window blinds’ weight and the cords’ force components, and (2) the relationship between the spring coil number and the resulting torque. The former analyzes the factors that influence the force components of the blinds, and the latter discusses the variation of spring torque with respect to the number of the spring coil. In addition to proposing the experimental methods for statically balanced analysis, this study has developed a computer interface to help designers quickly obtain parameters for manufacturing the gradient negative torsion spring so as to shorten the product development time.

Keyword: Cordless blinds, Gradient negative torsion spring, Statically balanced mechanism

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