Flap cards were in use as far back as Jacques Ozanam's Récréations Mathématiques et Physiques, 1694, p. 113 of the Pieper translation. This book was translated in Gibecière, Winter 2011, p. 79-156. The flaps were not powered by any type of springs or flaps; they had to be manually flipped over.
Professor Kunard, in his Book of Card Tricks, 1888, p. 133, made it clear that conjurers of the nineteenth century had taken to constructing spring-flap changing-cards, using bits of flat elastic. In August Roterberg's New Era Card Tricks, 1897, p. 226, he talks of using sheet rubber to fabricate various self-activating card quite similar in construction to the acrobatic card feke that would become popular in the 1960s. Given that much of Roterberg's material was drawn from German sources, earlier publication of these ideas may have occurred in German.