25 PFU centering error (image suddenly shifts by 5mm)
[Symptom]
During continuous printing using Tray 4 and Tray 5, the image on the paper suddenly shifts by
around 5 mm.
[Probable causes and solution]
The centering sensor located at the PFU exit detects paper edge and calculates the off-center
amount. For the correction, the image writing position is shifted according to the detected
off-center amount to achieve high accuracy of the registration between side 1 and side 2.
The off-center detection range is +/-5mm and if off-center amount exceeds the detection range,
the centering correction mechanism cannot work. Consequently, the image suddenly shifts
by around 5mm.
The presumed causes are following 3.
The cause differs by the problem occurrence paper side (side 1 or side2)
[CAUTION FOR THE CAUSE ANALYSIS]
・
Breakage of the sensor is cause in a few cases. Therefore please check if the sensor
functions correctly.
・
For the 5mm shifts, the causes may be all of the 1, 2 and 3 or combination of two of them.
(If both side 1 and side 2 shift, all of them may affect)
1) Side guide is not set properly.
Side guide is not set symmetrical from the center. There is a space between paper edge
and side guide.
To correct it refer to
26.Centering error, skew (How to set paper on PFU)
2) Main body and PFU connection was not adjusted properly at the installation.
The main body and PFU connection was not adjusted properly at the installation and the
main body and PFU height is not correctly adjusted.
To correct it, check the position of main body and PFU. If the adjustment is not enough,
perform the adjustment as stated in next page.
32
