HP 4550 Service Manual - Page 121

Figure 5-21 Toner carousel operation Toner cartridge contact/separation function This function brings the developing sleeve closer to the photosensitive drum by pushing the toner cartridge push cam out so that the toner cartridge rotates up onto the cam. The DC controller determines the time lapse of the developing stop position flag with the carousel position sensor (PS10) to determine that the toner cartridge is in position. The DC controller then activates the toner cartridge motor (M5), and the motor begins to rotate clockwise. This causes the toner cartridge push cam to rotate and push out. The toner cartridge then rotates up onto the cam. This positions the toner cartridge and the developer sleeve near the drum and puts the spacers in contact with the drum (see Figure 5-22). The toner cartridge contact sensor (PS11) detects when the toner cartridge is close to the drum (see Figure 5-22). Once the toner cartridge is facing the drum, the DC controller deactivates the carousel motor (M3), which stops the rotation of the carousel. At the same time, the DC controller starts development by rotating the toner cartridge motor (M5) counter clockwise to begin rotation of the developing sleeve. Once development is complete, M5 again rotates clockwise, moving the toner cartridge away from the drum. The toner cartridge contact sensor detects when the toner cartridge has moved away from the drum. The carousel motor (M3) again begins the carousel rotation, and the process is repeated for each toner cartridge. Figure 5-22 Toner cartridge contact/separation function Toner level detection/toner cartridge detection This function detects the remaining toner level in the toner cartridge and the presence of the toner cartridge in the carousel. C7085-90921 Chapter 5 Theory of operation 119