Persiana enrollable porque incluye un miembro de hoja flexible que tiene un primero y segundo borde paralelo opuesto, un eje enrollable giratorio en cada uno de las dos direcciones opuestas de rotacion, el miembro de hoja flexible siendo unida a lo largo de su primer borde al eje enrollable en una direccion longitudinal.

摘要

A roller shade including a flexible sheet member having opposite parallel first and second edges, and a roller shaft rotatable in each of two opposite directions of rotation. The flexible sheet member being attached along its first edge to the roller shaft, while the second edge of the flexible sheet member is freely depending from the roller shaft. The roller shade further comprises a counterbalancing device for balancing a portion of the flexible sheet member that is unwound from the roller shaft. This counterbalancing device has means for storing a variable torque that is complementary to a variable weight of the portion of flexible sheet member that is depending from the roller shaft. The means for storing variable torque includes a helically wound tension spring operatively interposed between a stationary central rod and the roller shaft.