High Quality Content by WIKIPEDIA articles! The Tri-Ergon sound-on-film system was patented from 1919 on by German inventors Josef Engl (1893-1942), Hans Vogt (1890-1979), and Joseph Massolle (1889-1957). The name Tri-Ergon was derived from Greek and means "the work of three." (See FilmSoundSweden website under External Links section below.)