HP Color 9850mfp Service Manual - Page 67

I OUTLINE hp Color 9850mfp 5.2 Charging process (Step 1) IMAGE CREATION PROCESS The charging corona, having a gold-plated tungsten wire, is applied with a high DC voltage (minus) to negatively charge the surface of the photosensitive drum by wire discharge. The charging corona is provided with a charging grid plate to make charges on the surface of the photosensitive drum uniform. Photosensitive drums are provided for the four colors of Y, M, C and K. [1] [2] [1] Drum [2] Charge (negative) [4] [3] [3] Charging corona [4] Charging grid plate 5.3 Laser exposure process (Step 2) Charges on the surface of the photosensitive drum have a characteristic that when they are irradiated with light, they are neutralized and vanish. Using this characteristic, a laser beam is irradiated on the image region to create an image by removing charges on the photosensitive drum. This image is referred to as an electrostatic latent image. A laser beam is irradiated on each photosensitive drum of Y, M, C and K corresponding to the four color data resolved by the image processing section. [4] [3] [1] [1] Write unit [2] Laser beam [2] [3] Neutralized section [4] Charge (negative) 1-41