Service manual

EPSON Stylus Photo 870/1270 Revision B
OPERATING PRINCIPLES Overview 37
Figure 2-4 gives the paper feeding mechanism block diagram, showing
the parts along the PF motor drive transmission paths.
Figure 2-4. Paper Feeding Mechanism
The printer loads paper at the ASF, which is detected by the PE sensor
attached to the right side of the top frame, and advances it to send the
paper’s leading edge to the halfway of the front paper guide. Then, to
correct paper deflection, the printer feeds the paper back specified steps
toward ASF, and advances the paper again toward the front paper guide
and stops it at the specified TOF (Top Of Form) position. Once printing
starts, the paper is fed by the PF rollers and sub rollers. For printing or
transporting the tailing edge area (14 mm), a notched roller and drive
from the paper eject roller are used. Like the Stylus Photo 750/1200, this
printer also provides this extra printable range of 14 mm from the bottom
edge, excluding the bottom margin of 3mm, by changing the position of
the star wheel gear; it has been shifted by 5
°
from the top of the eject
roller toward the front paper guide. Due to this change, the tailing edge of
paper is suppressed, and the printer can advance paper steadily. See
Figure 2-5 next page that shows how paper is transported and parts
involved.
Figure 2-5. Paper Transportation
PF Motor Pinion Gear
Paper Eject Roller
Front Paper Guide
Combination Gear
(13.5, 308)
PF Roller
Paper Eject Roller
Spur Gear (76)
PF Motor
[Previous Models]
Paper
Notched Roller
Printhead
Support Roller
PF Roller
Paper Eject Roller
Platen Surface
5
°
°°
°
Steady Feeding
Bottom Margin (3 mm)
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Stylus Photo 870/1270
]