HP Color LaserJet 8500 Service Manual - Page 145

Electrostatic latent image formation block One of the differences between color and black-and-white laser imaging is that the color image is created with multiple layers. This printer contains four toner cartridges (cyan, magenta, yellow, and black). The electrostatic latent image formation block consists of three steps for forming the image on the imaging drum. At the end of the last step, the negative charge on the unexposed area remains while the negative charge on the exposed area is decreased. This potential image on the drum is invisible to the human eye and is called electrostatic latent image. 1. Preconditioning exposure To prepare for primary charging, the preconditioning exposure lightemitting diode (LED) unit removes the residual charge on the imaging drum surface. This helps prevent uneven surface charge on the imaging drum. Figure 26. Preconditioning exposure EN Image formation 143