Electrophotography

Abstract

AbstractElectrophotography, also called xerography, is a process for producing high quality copies or images of a document. Electrophotography is based on forming an electrostatic charge pattern or image of the original document that is made visible by ultrafine electrically charged particles.The advent of the personal computer and desktop publishing created a need for convenient, low‐cost, point‐of‐need printing. At first, typewriters were adapted to perform impact printing, followed by dot matrix printers, but these concepts had many disadvantages. Small (and slow) ink jet printers have come to dominate the low‐volume desktop publishing market at this time. The mid‐volume and high‐volume markets, however, are presently dominated by faster and more reliable laser and light‐emitting‐diode (LED) electrophotographic printers. The print quality of these modern printers approaches that of offset lithography quite closely, so many electrophotographic machines compete effectively with the offset press. There are business advantages for each type of printer, however, and offset print shops are certainly not going to go out of business in the foreseeable future. Because of the popularity of electrophotographic printers, both large and small, color and black only, this article explores the fundamentals involved in producing hard copy by this process.This article first presents an overview of the essential elements in an electrophotographic imaging system. Then, each of the commercialized process steps is covered in some detail to lead the reader from corona sensitization of the photoconductor to fixing of the final image. An extension of the electrophotographic process to color printing is discussed in the final section.In a form of electrophotography called xeroradiography, the X‐ray portion of the electromagnetic spectrum is used to form a latent image on a photoconductor.