Brother International HL-1260 Service Manual - Page 27

3.3 Operation When the engine controller circuit receives a print signal (PRINT) or a pre-feed signal (PRFD) from the video controller circuit, the engine controller circuit drives the main motor to rotate the photosensitive drum. After the drum surface is charged negatively by the primary charge roller, the laser beam modulated by a DATA signal scans the drum surface to from a latent image on the drum. The latent image formed on the drum surface is converted into a visible image by the toner on the developing cylinder and then image is transferred onto the paper by the transfer roller unit. Then the residual toner is removed from the drum surface with the cleaner blade. The cartridge also has a toner sensor. When the output from this sensor falls below a certain level, it warns that the EP-ED cartridge will be out of toner with an alarm. Scanner unit Laser beam Reflection mirror EP-ED cartridge Transfer roller Scanner motor drive signal (SDRIVE) Laser diode drive signal (DATA) Main PCB Primary charge (AC) drive (HV1AC) Primary charge (DC) drive (HV1DC) Developing bias (AC) drive (DBAC) Developing bias (DC) drive (DBDC) Transfer charger 1 drive (HVT1) Transfer charger 2 drive (HVT2) Transfer charger 3 drive (HVT3) Transfer charger 4 drive (HVT4) Toner sensor signal 1 (TONER 1) Toner sensor signal 2 (TONER 2) High-voltage power supply PCB Figure 2.17 II - 11