Brother International HL-3400CN Service Manual - Page 73

CHAPTER 4 STRUCTURE OF SYSTEM COMPONENTS 9 Drum Cleaning The drum cleaning process is where the residual toner on the transfer drum is removed. (1) Structure of Drum Cleaning (Refer to Fig.4-23.) i) The drum cleaning unit is located as shown in Fig. 4-8. ii) The drum cleaning brush is a semiconductor type so that the brush can clean the surface of the rotating transfer drum. The Drum cleaning brush is kept out of contact with the transfer drum when the print image on the transfer drum is being created. iii) The drum cleaning roller is positively biased by the positive voltage FCBV(V). iv) FCBV(V) is fed to the cleaning brush in contact with the roller and the cleaning brush is self-biased by the resistance of the brush. v) The drum cleaning roller rotates in contact with the drum cleaning brush. (2) Process of Drum Cleaning (Refer to Fig.4-23.) i) There is residual toner on the surface of the transfer drum after the paper transfer process. ii) The Drum cleaning brush is positively self-biased and so the negatively charged residual toner is removed from the surface of the transfer drum onto the drum cleaning brush. iii) The Drum cleaning roller has been biased to the positive voltage FCBV(V). As the cleaning brush rotates, the residual toner absorbed into the brush from the transfer drum is attracted by the positive FCBV(V) voltage on the roller and adheres to the surface of the drum cleaning roller. iv) Waste toner adhering to the surface of the drum cleaning roller is scavenged by the cleaning blade and collected into the waste toner pack by the waste toner feeder. Cleaning brush Drum cleaner Residual Toner FCBV FCBV: Cleaning roller Power supply for fuser cleaner bias @ Transfer drum Fig. 4-23 West toner feeder Drum cleaning unit 4-22