Laser Printing and Photocopying

Laser printers and photocopiers use electricity and light to produce an image. The two main components are the photoconductor, now invariably an organic 

Full color printing is essentially the same as for black and white but requires four steps, one each for the yellow, magenta, cyan, and black toners needed for full color reproduction [2,3], Consequently, color laser printers and copiers are significantly more expensive than monochrome laser printers and especially inkjet printers. They are also slower than monochrome laser printers. 

Most modem laser printers now use titanyloxy phthalocyanine, type IV polymorph, as the CGM. This pigment has the best combination of properties and is unlikely to be surpassed. 

CCAs can be colored or colorless and are mainly dyes rather than pigments. Colored CCAs are more effective than colorless CCAs but, because of their color, are restricted to black toners. Colorless CCAs are needed for yellow, magenta, and cyan toners. 

The CCAs which impart a negative charge to the toner are invariably metal complexes, particularly 2 1 Cr111 azo dye complexes such as (6), and colorless complexes such as (7), both of which have a delocalized negative charge [2,3], 

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