Device for rotating vertical slat blinds, with measures to avoid gear tooth damage

摘要

A device for adjusting a slat (100, fig 2) of a window blind which has a rod 20 with teeth, a transmission member 40 and a turning member 30. The transmission member has a first 42 and second rack 44, where the first rack is meshed with the rod to move the transmission member between a first and second position, and the second rack is meshed with the turning member in a rack and pinion formation. The first rack has a plurality of teeth in a line where the end teeth (421, 426 fig 6) are shorter than the other teeth (422-425, fig 6). The end teeth, and adjacent teeth (422 & 425, fig 6) may be asymmetrical and may have a curved profile. The tooth shape is designed to protect the teeth in the event of overturning of the rod.