HP Color LaserJet CP2020 Service Manual - Page 87

These processes are divided into nine steps, which are shown in Figure 5-9 Image-formation process on page 67 and described in the following sections. Figure 5-9 Image-formation process Delivery 7. Fusing Fuser Latent image formation 2. Laser beam exposure 1. Primary charging 3. Development Development Transfer 6. Separation Photosensitive drum cleaning 9. Drum cleaning 5. Secondary transfer 4. Primary transfer 8. ITB cleaning : Media path : Direction of drum rotation : Block : Step Registration ITB cleaning Pickup Latent-image formation stage During the three steps that comprise this stage, a latent image is formed by applying a negative charge to the photosensitive drum. You cannot see this image on the drum. Step 1: primary charging A high-voltage DC bias is applied to the primary charging roller, which is made of conductive rubber and is in contact with the drum surface. As the roller moves across the drum, it applies the negative charge to that surface. Figure 5-10 Primary charging Primary charging roller Photosensitive drum DC bias ENWW Image-formation system 67