Xerox Phaser 6121MFP Service Manual page 101

Phaser 6121MFP Service Manual
A loop correction mechanism is provided to prevent skew from occurring in the
second page. The Registration Solenoid is energized after the lapse of a given
period of time after the Paper Loop Sensor has been activated. This drives the
Registration Roller, and the paper is conveyed into the machine.
Duplex Unit Transport Operations
The following steps detail the transport operations for single, hand-fed sheets.
1. The first sheet of paper is taken up and fed in from the main tray and the first
print cycle begins. Immediately before the one-sided print leaves the Exit
Roller, the direction of rotation of the Exit Roller is reversed and the 1-sided
print is transported toward and into the Duplex Unit.
2. The print moves through the Duplex Unit and is temporarily stopped at the
Duplex take-up position. Any skew in the paper is corrected at the Registration
Roller before the paper is fed by the Duplex Unit.
3. The second print cycle begins to produce the second image on the original
sheet. While feeding the first two-sided print to the Exit Tray, the first print
cycle for the second sheet begins. This process repeats until the print job is
complete.
4. The first sheet of paper is then taken up and fed in from the tray and the first
print cycle begins to produce the print image on the second page of the
original. Immediately before the first one-sided print leaves the Exit Roller, the
Exit Roller is reversed and the first 1-sided print is transported into the Duplex
Unit.
5. At the same time, the second sheet of paper is fed into the print engine. The
first print cycle for the second sheet produces the image on the fourth page of
the original.
6. Also at the same time, the first 1-sided print is transported through the Duplex
Unit. The main unit produces the print image of the first page of the original
on the first one-sided print that has been fed through the Duplex Unit. At the
same time, the second sheet of paper is subjected to a switchback sequence
at the exit section and fed into the Duplex Unit. Also, the third sheet of paper
is taken up and fed into the main unit.
7. While feeding the first 2-sided print out, the main unit produces the print
image of the 6th page of the original on the third sheet of paper. The second
sheet of paper waits at the Duplex take-up position until the third sheet of
paper is subjected to a switchback sequence.
8. Immediately before the first one-sided print leaves the Paper Exit Roller, the
direction of rotation of the Paper Exit Roller is reversed and the first 1-sided
print for the third sheet is transported toward and into the Duplex Unit.
9. At the same time, the second sheet of paper is fed into the main unit again.
The main unit carries out the first print cycle for the second sheet of paper to
produce the print image of the third page of the original. At the same time,
the first 1-sided print for the third is transported through the Duplex Unit. Also
at the same time, the forth sheet of paper is taken up and fed into the main
unit.
10. While feeding the second 2-sided print out, main unit produces the print
image of the 8th page of the original on the fourth sheet of paper. The third
sheet of paper waits at the Duplex take-up position until the fourth sheet of
paper is subjected to a switchback sequence. The process repeats until the
print job is complete.
Theory of Operation
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