HP 4600 Service Manual - Page 161

Development block The second part of the image-formation process is the development block, where toner is transferred onto the electrostatic latent image on the surface of the photosensitive drum to create a visible image. This printer uses a contact development method that keeps the developing cylinder in contact with the drum, pushing the toner against the drum surface for development. The toner is nonmagnetic and consists of resins. This block consists of two steps: ■ Toner charging ■ Development Figure 5-23 Development block shows a cross-section of a print cartridge and illustrates the development block. Figure 5-23 Development block Step 4: Toner charging As the toner stirring blade turns inside the cartridge, the friction creates a negative potential on the toner. A negative voltage is applied to the toner charging roller and creates a uniform negative potential on the toner. Step 5: Development The areas on the photosensitive drum that have been exposed to the laser beam have a higher potential (are less negatively charged) than the toner particles on the developing cylinder. As the photosensitive drum rotates, the toner adheres to the exposed areas on the photosensitive drum. At this point, the image is visible on the drum surface. ENWW Image-formation system 145