Preassembled roller blind

摘要

A blocking device (17,18,29) prevents a spring drive (12) from acting between a wind-up shaft (14) and a bearing device (6,24) when the wind-up shaft is pretensioned corresponding to a window shade web (12). The blocking device is releasable without using tools during or after installation of a window shade device to allow the spring drive to act between the bearing device and the wind-up shaft.