Electrophotographic image

In other areas, POD has been used to improve the wear resistance of a mbber latex binder by incorporation of 25% of Oksalon fibers. Heat-resistant laminate films, made by coating a polyester film with POD, have been used as electrical insulators and show good resistance to abrasion and are capable of 126% elongation. In some instances, thin sheets of PODs have been used as mold release agents. For this appHcation a resin is placed between the two sheets of POD, which is then pressed in a mold, and the sheets simply peel off from the object and mold after the resin has cured. POD-based membranes exhibit salt rejection properties and hence find potential as reverse osmosis membranes in the purification of seawater. PODs have also been used in the manufacturing of electrophotographic plates as binders between the toner and plate. These improved binders produce sharper images than were possible before. 

The electrophotographic system (102,103) involves two key physicochemical elements a photoreceptor and a toner. The minimum requirements of the process are (/) to charge a photoconductive photoreceptor uniformly (2) to illuminate selectively the photoreceptor to form a latent electrostatic image and (J) to develop the image by applying charged toner. These steps are illustrated in Figure 17. 

The Development Process. In the original electrophotographic demonstration, development was accompHshed by dusting lycopodium powder over an exposed sulfur film. This yielded low density images of poor resolution. Considerable powder settied in the exposed background areas (the white areas of a document), and image transfer to paper could only be achieved by prior coating of the paper with wax or another sticky material. 

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W. R. Workman at the Minnesota Mining and Manufacturing Company, MN, and commercialized for office copying, but later superseded by various electrophotographic processes.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 ... 

The photoconductivity of organic dyes, especially phthalocyanine pigments, could be utilized to provide reusable or non-reusable electrophotographic plates having sensitivities that extend over the entire visible spectrum and produce high-contrast images 167,168) Microcrystalline dispersions of metal-free phthalocyanine in suitable binders have a white-light sensitivity equal to that of selenium 169> and can be incorporated into coated papers and drums. 

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. 

Poly(vinylcarbazole), of course, is the polymer that is generally utilized in electrophotographic imaging processes such as xerography, but the polymer is not totally satisfactory from a mechanical viewpoint (Section 1.11.2.1.1). Better strength, flexibility, ozone resistance and adhesive properties were said to result by utilizing a modified poly(epichlorohydrin)... 

Heterocyclic compounds are also used in electrophotographic materials as image dyes and their precursors. The acyl leucophenoxazine (171) is an example of the latter (81USP4284696). 

Count An electrophotographic plate for producing an electrostatic latent image on the... 

JP 05197182 (Japanese) 1993 Electrophotographic Photoreceptor with Amorphous Silicon Pho-toconductive Layer Fuji Xerox Co. Ltd., Japan S Yagi et al. Copolymer useful for surface protective coating photoreceptor shows stability and gives sharp images Maleimide-terminated siloxane-imides crosslinked coatings were used to protect photoreceptors. 

Fig. 7. Electrophotographic imaging process steps see text for details...

Figure 3 A reproduction of a photographic print of the first electrophotographic image, created by Carlson and Koreni in 1938.

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. 

Enokida, T. and Hirohashi, R. (1992). Electrophotographic dual-layered photoreceptors incorporating copper phthalocyanines. / Imag. Sci. TechnoL, 36, 135 1. [207]... 

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