Taiwanese Patent # I403434/201204598 - KCNC

Taiwanese patent 201204598 - KCNC main image

This is the second of three patents, held by Chang-Hui Lin of KCNC, relating to derailleur designs. This one involves a pulley cage and p-pivot that travel along a set of rails, pulled along by a conventional cable. The rails are cunningly shaped to track the shape of the freewheel.

I don't think that KCNC put this design into production.