PATENTS FOR MAJOR SOUND-ON-FILM
DEVELOPMENTS THROUGH 1927

Year Inventor and patent number

1900 V. Poulsen: Magnetic wire recording US 661,619

1905 V. Poulsen: Magnetic wire recording US 789,336

1906 J. Ballance: Groove-on-film system US 823,022

Lee De Forest: Diode Audion with B battery US 836,070

V. Poulsen: Magnetic wire recording US 873,078

V. Poulsen: Magnetic wire recording US 873,083

1907 Lee De Forest: Audion with external electrodes US 841,386

Lee De Forest: Audion Amplifier US 841,387

R. T. Haines, J. S. Pletts, and Eugene Lauste: Sound and picture recorded on single film Gr. Br. 18,057

1923 E. E. Ries: Single film sound-system US 1,473,976

1924 Lee De Forest: Sound-on-film system US 1,489,314

1925-26 H. Vogt, J. Massolle, and J. Engl: Tri-Ergon system US 1,512,681; 1,534,148; 1,555,301; 1,557,678; 1,558,032; 1,566,413; 1,590,185; 1,597,323; 1,608,261; 1,628,377; 1,634,201; 1,713,726 (the flywheel patent); 1,756,681; 1,825,598.

1927 Lee De Forest: Equipment for talking films US 1,653,155

T. W. Case: Aeo-Light US 1,816,825.