EPSON Stylus C110/C120/D120 Revision B
OPERATING PRINCIPLE      Printer Mechanism Operating Principles 27
2.2.3.1  Paper Loading Mechanism (ASF Unit)
The paper loading mechanism loads paper from the ASF unit and feeds paper to the PF 
roller. The ASF unit includes the hopper, change lever, LD roller shaft, and clutch 
mechanism. 
 
The change lever and the clutch mechanism play an important role in the paper loading 
operation as described below. 
1. ASF home position detection function 
The change lever and the clutch mechanism are used to detect the ASF home 
position.
 
The counterclockwise rotation of the PF motor brings the change lever to engage 
with the clutch mechanism. The ASF home position is detected by the engagement 
of the change lever at the beginning of the paper loading operation. At this time, 
paper is not fed to the PF roller because the PF motor drive force is not yet 
transmitted to the LD roller shaft.
2. Paper loading function 
When the change lever is disengaged from the clutch mechanism by the 
counterclockwise rotation of the PF motor pinion gear, the printer changes to the 
paper loading state from the ASF home position detection state. The PF motor 
drive force is transmitted to the LD roller, and paper is fed from the ASF unit.
The rotation of the two cams on the LD roller feeds paper into the printer.
 Larger cam:  moves the hopper
 Smaller cam:moves the paper back lever
When the first sheet of paper has been fed, the second sheet is returned to the standby 
position by the hopper and the paper back lever, which are moved by the cams.
The following sections explain the paper loading sequence and operations of each 
components.
STEP1: ASF HOME POSITION
The counterclockwise rotation of the PF motor pinion gear (as seen from the left of the 
printer) causes the change lever to push down on the clutch lever, and the clutch lock 
tab is disengaged from the clutch gear as shown in 
Figure 2-8. This cuts the PF motor 
drive transmission to the LD roller shaft, and the shaft does not move at all. At the 
same time, the hopper is pushed down by the two cams on the LD roller shaft, and the 
paper back lever is set at the position to prevent paper from being fed. The “ASF home 
position” indicates all of the above statuses. 
Figure 2-8.  ASF Home Position