I just discovered that my grandfather had established a US, CA, and GB patent for a pontoon floating bridge around 1930. My grandfather died at an early age around 1941 and the patent was left to the family. I also just discovered that my grandfather’s patent has been referenced and cited in at least 8 other patents over the years since his death with the most current being in 2007. My question, is the family entitled to any royalties or patent infringement penalties from these other patents and implementations of patented items?
Of course those patents would have expired long ago. Only activities carried out while a patent is in-force would be susceptible to royalties and there is a statute of limitations on asserting those claims. Someone citing his patents and even patenting things that build on his work would not entitle him to compensation. Only making, selling, offering for sale and using things covered by in force patents would do that.