Brother International HL-720 Service Manual - Page 47

2.5.3 Developing Developing causes the toner to be attracted to the electrostatic image on the drum so as to transform it into a visible image. The Developer Consists of the non-magnetic toner. The developer roller made of conductive rubber and the supply roller made of conductive sponge rotate on each other. The toner is charged and carried from the supply roller to the developer roller. Thus, the toner is adhered to the developer roller and conveyed to the drum with its thickness made even by the blade. The toner is nipped between the developer roller and the drum and developed on the latent image. Electrostatic field between the drum and the developer roller, which is DC-biased from the High-voltage power supply, makes electrostatic potential to attract toner particles from the devel oper roller to the drum. Blade Transfer roller (a) Transfer process [ON] Toner (b) Cleaning process [ON] Auger Develop housing Erase lamp Supply roller DC-bias Drum Developer roller Fig. 2.34 Cleaner roller 2.5.4 Transfer (a) Transfer process After the drum has been charged and exposed , and has received a developed image, the toner formed image is transferred onto the paper, applying the negative charge from the backside of the paper. The negative charge to the paper causes the positive charged toner to leave the drum, and adhere to the paper. As a result, the image is visible on the paper. (b) Cleaning process of transfer roller If the toner is not transferred onto the paper perfectly due to jamming etc., it is possible that the toner adheres to the charge transfer roller. The transfer voltage charges to positive voltage during non transferring process. Therefore the transfer roller is cleaned by returning the positive charged toner adhered on the transfer roller onto the photo-conductive drum. II-30