He was upset by the low quality and high cost of existing patent reproductions, and so he started to develop a system of dry photocopying, which he patented in the late 1930s, and which became the first dry photocopier that was commercially practical
Él estaba molesto por la baja calidad y alto costo de las copias de las patentes existentes, así que comenzó a desarrollar un sistema de fotocopiado en seco, que patentó a finales de los 1930s; y