My grandfather Arden A. Alfvegren - patented this screen in his spare time, while working for an architecture firm. He died in 1976, nine months before I was born. I am the only grandchild in the family; my mother and her three siblings are all a bit crazy. My uncle tells me that this screen held his invention, a proto-solar panel, and that the architecture firm he worked for at the time, sued him for it, although they didn't understand the concept of solar power. I know he started his own company, called Solar-On. And he affixed prototypes of this invention in a few places around Los Angeles. How can I find out if someone still holds this patent? Or is doing anything with it? I understand patents expire within two decades of their being issued, but know nothing of patent law beyond that. Thank you kindly.
In reference to the patent: USD201045