| 摘要 |
<p>A window covering includes at least one spring motor attached to a rotatable shaft. The spring motor includes at least one spring member that has an elongated body having a windable length, a uniform thickness throughout the windable length, a uniform width throughout the windable length, and a uniform rectangular cross section throughout the windable length. The spring member is configured so that it has a different microstructure at different portions of the first spring member located along the windable length of such that the spring member exerts an amount of force as the portions of the first spring member may wind about a roller of the spring motor that progressively increases such that the roller may prevent movement of the shaft to maintain a position of the window covering material after the window covering material is moved to a particular raised position.</p> |
