This patent describes the Simplex Selematic 5. It is one of the most complex, sophisticated and interesting derailleur patents that you will find. Anyone who can understand all of its intricasies deserves a medal.
It's such a pity that the resulting derailleur was a total dog - ludicrously heavy and laughably ineffective.
If you want to read the same patent in English, it is here.
Browse associated derailleurs.
Simplex Selematic 5 1981