Having followed the Shimano trend and butchered their Mistral design by hiding the bolt in the p-knuckle (see French patent 2,628,383) Ofmega seem to have wanted to take the next step - to add a Shimano-style (or possibly more correctly Simplex-style) sprung b-pivot. This is certainly what is described in this patent. Perhaps they dreamed of an indexed Mistral.

I don’t think this particular ‘improvement’ ever made it into production.

• Publisher: L’Institut national de la propriété industrielle
• Inventor: Dino Perotti & Mario Perotti
• Country: France
• Date: Italian application November 1988, French application August 1989
• Derailleur brands: Ofmega
• Derailleurs: unknown