 By the end of 1930, the Phonofilm business would be liquidated.In Europe, others were also working on the development of sound-on-film.In 1919, the same year that DeForest received his first patents in the field, three German inventors, Josef Engl (1893–1942), Hans Vogt (1890–1979), and Joseph Massolle (1889–1957), patented the Tri-Ergon sound system.