A man who claims to have invented the iPhone 15 years before Apple began selling it is suing the tech giant nearly 25 years later for copyright infringement.

Thomas Ross of Florida in the US launched the proceedings last week seeking a whopping $US10 billion in compensation, plus forfeit of patents. The claim dwarfs a previously successful patent infringement case in which Samsung paid just $US548 million to Apple.

An image from the claim.

It all centres around a design Ross came up with in 1992 for an "electronic reading device", which featured a back-lit touchscreen, wireless communication capability, and rounded edges.

Ross, a former software engineer who now manages a law firm, told The Guardian he spent more than a year on the design. He filed a US patent for the design in November 1992, but it was marked as 'abandoned' three years later because he failed to pay the required fees. In the absence of a patent, Ross is now pursuing Apple under copyright law.