translation.en: 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 in 1960.
translation.zh: 他对于当时低质量高成本的 复印技术专利很失望 于是他开始发明一套 干法复印系统 并在19实际30年代后期申请了专利-- 于1960年成为了第一个 用于商业用途的 干式复印机