Electrophotographic Processes

Dual-Spectrum Also called Workman. A thermographic copying process. A transparent film base, coated with 4-methoxy-l-naphthol and a photo-reducible dye such as erythrosine, receives the image, which is then transferred to a paper sensitized with sodium behenate. Invented in 1961 by W. R. Workman at the Minnesota Mining and Manufacturing Company, MN, and commercialized for office copying, but later superseded by various electrophotographic processes. 

The electrophotographic process involves the production of an electrostatic latent image on a photocondnctor (also called a photoreceptor) and the conversion of this into a visible image with a charged toner, which is then transferred to the substrate, (usually paper) where it is fixed. The six individual steps in the process are ... 

Figure 2.37 The electrophotographic process using organic photoconductors (a) photocopying and (b) laser printing.

Biodegradable carboxy aromatic polyhydroxyalkanoate resins, (II), having high thermal stability were prepared by Fukui et al. (4) and used as toners in electrophotographic processes. 

Electrophotography. The main stages of the electrophotographic process consist of charging the photoconductive layer on the conducting plate, formation of the latent potential image under illumination, and visualization of the image. 

Organic chemicals are used in electrophotographic processes as dyes, pigments, charge transport compounds, spectral sensitizers and components of the photoconducting medium. 

Figure 5.29 Schematic diagram of new multiduplication processes based on polysilanes (A) an electrophotographic process (B), an electrostatic process. Reprinted with permission from reference 146. Copyright 2000 Kluwer Academic Pulishers.

Because of the very considerable process complexity of xerography, there have been many attempts to develop alternative electrophotographic processes. A review of early work has been given by Caillson (1965), Claus and Corrsin (1965), Schaffert (1965. 1975), and Weigl (1977). More recent work has been reviewed by Schein (1988. 1992, 1995). The more prominent of these processes are briefly discussed below. 

For reasons of cost, image quality", and process speed, none of the above processes is competitive with xerography. For these reasons, there has been little commercial emphasis on alternative electrophotographic processes during the past two decades. For office and desktop nonimpact printing applications, the principal alternatives to xerography are thermography and inkjet. 

Fridkin, V. M.. in The Physics of the Electrophotographic Process, Focal Press, New York, 1972. 

The electrophotographic process is initiated by deposition of a uniform surface charge from the corona on the xerographic photoreceptor belt in the... 

The importance of (x in the electrophotographic process can be understood as follows For an increase in the light exposure intensity (AF), the final decrease in surface potential (AV) is proportional to the number of injected carriers (supply) and the distance they travel within the TL (if the GL is... 

Figure 1. An electrophotographic process with web-based photoreceptor. (Reprinted with permission from Ref. [3q].)...

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