Who invented the copier?

Chester Carlson, the inventor of the copier, was originally a patent lawyer, part-time researcher and inventor. His job in new york Patent Office requires copying many important documents. Calvin suffers from arthritis and regards copying documents as a painful and monotonous job. This encouraged him to conduct photoconductive experiments, and it is estimated that he can copy them in the simplest way. Carl Johnson conducted an electrophotographic experiment in his kitchen, and applied for a technology patent at 1938. He made the first photocopy of zinc sheet covered with sulfur. He made the first "copier" from zinc plates coated with sulfur. The words "10-22-38 Astoria" are printed on a microscope slide, under the strong light of sulfur. After the slides were taken away, the mirror images of those words were left on the sulfur. Carlson intends to sell his invention to some companies, but the process is not mature enough to achieve results. At that time, a lot of copying work was done with carbon paper or photocopiers, and the demand for electronic photocopiers was not strong. From 1939 to 1944, Carlson was rejected by more than 20 companies such as IBM and GE, and none of them thought that there would be a great market demand for photocopiers. 1944, Bater Memorial Institute, a non-profit organization located in Columbus, Ohio, signed a contract with Carlson to improve his new technology. In the next five years, this institution conducted many experiments to improve the electrophotographic process. 1947, Haloid (a small organization located in new york at that time) contacted Battelle and asked for authorization to develop and sell photocopiers based on this technology. Harold realized that the word "electrophotography" was too complicated to have a good memory. After consulting the professor of classical languages at Ohio State University, Harold and Carlson changed the name of this process to "xerography", which is derived from the Greek word "dry writing". Harold decided to name the new copier "Xerox", and Xerox became a trademark on 1948. In the early 1950s, RCA (American Radio Company) developed a series of processes called electronic fax, in which images were generated directly on special coated paper and colored with liquid toner. 1949, Xerox developed the first electrostatic image copier, called Model A ... Xerox achieved such great success that the photocopying technology was called "Xerox" by the public, and Xerox actively responded to prevent "Xerox" from becoming a general trademark. "Xerox" appears as a synonym for photocopying in some dictionaries, which leads Xerox to send letters and advertisements asking them to change these items and asking people not to use "Xerox" like this. However, this is only the case in North America. For example, in the British Isles, "photocopying" is far more common than "Xerox", which may be because after the popularization of photocopying technology, the number of photocopiers of Japanese and European manufacturers far exceeds that of Xerox products. Mixed words are used in some languages, such as kserokopia ("Xerocopy"), which is widely used in Polish, although the market share of Xerox brand photocopiers is very small. With the development of technology, xerographic technology was born. Firstly, a high-contrast electrostatic image is generated on the toner box, and then a meltable plastic powder (called toner) is transferred to ordinary paper and melted on the paper after heating. This process is similar to the technology used in laser printers. Technical progress brought about the development of color photocopying and electrostatic photocopying in1970s and1980s. Some products sold as photocopiers in the market use inkjet or film expansion technology instead of the working process based on toner cartridges.