Thomas Alva Edison (1847-1931), US inventor. Edison is famous for inventing or improving devices such as the phonograph and the electric light bulb. He founded several laboratories and companies, and filed over 1000 patents. Other work included improvements to telegraphy, cameras, and motion picture cameras, as well as promoting his DC (direct current) electrical distribution systems. In 1880, Edison founded the journal Science, which is now the journal of the American Association for the Advancement of Science. He also discovered the Edison Effect, on which thermionic valves are based. 19th-century engraving.