| 摘要 |
<p>A mechanism for extending or retracting for a covering for an architectural opening with respect to architectural opening, including a rotatable drive shaft (5); at least one lift cord (11,13), at least one cord spool (7,9) for winding and unwinding the at least one lift cord, the cord spool being mounted for rotation with the drive shaft and being axially stationary. The cord spool has a first diameter end (21, 27) and a second diameter end (23, 29), the first diameter being larger than the second diameter, and the spool has a first generally conical circumferential spool portion (33) therebetween, wherein the first spool portion (33) comprises a plurality of steps (35, 37, 39, 41, 43, 45) each step having a tread (35A, 37A, 39A, 41A, 43A, 45A).</p> |
