Discovery Communications, the owner of cable channels like FitTV and Animal Planet, is suing Amazon.com, maker of the Kindle, over an electronic-books patent taken out by its founder and CEO, John Hendricks, years ago.

Why is a cable company dabbling in the e-books business? Aside from running Discovery, Hendricks has long played at being a part-time inventor. In 1999, he and two co-inventors filed for a patent, granted in 2007, on an "electronic book security and copyright protection system" which included "a portable book-shaped viewer is used for secure viewing of the text."

Sounds like Hendricks might have a case against Amazon.com, whose Kindle is widely viewed as the first e-book reader with commercial promise. But why does he care? The answer may lie in another patent Hendricks registered, which describes a system for transmitting e-books over "video signals" — an apparent reference to cable-TV systems. Discovery styles itself as a "nonfiction media company." Either Hendricks fears Amazon getting a lock on the nonfiction market. Or perhaps he's just wasting corporate resources to bolster his reputation as an inventor.