"Adult Arcade" means any establishment offering adult material as a substantial portion of its stock-in-trade, to which the public is permitted or invited for any form of consideration and wherein coin operated, slug operated, or electronically, electrically, or mechanically controlled still or motion picture machines, projectors, video or laser disc players, or other image-producing devices are maintained to show images to five or fewer persons per machine at any one time, and where the images so displayed are distinguished or characterized by the depiction or display of specified sexual activities or specified sexual anatomical areas.