Guillermo González Camarena independently invented and developed a field-sequential tricolor disk system in México in the late 1930s, for which he requested a patent in México on August 19, 1940, and in the United States in 1941. González Camarena produced his color television system in his Gon-Cam laboratory for the Mexican market and exported it to the Columbia College of Chicago, which regarded it as the best system in the world. Goldmark had actually applied for a patent for the same field-sequential tricolor system in the US on September 7, 1940, while González Camarena had made his Mexican filing 19 days before, on August 19.