Xerox M20 - WorkCentre B/W Laser, Service Manual

Page: 80 / 314

December 2006
3-4 WorkCentre M20, 4118, FaxCentre 2218 Family
IQ1
Image Quality
Figure 1 Test pattern 1
Repeat images Refer to offsetting defects and residual image defects. 1, 4
Residual
image A previous image that was not removed from the photorecep-
tor during the cleaning cycle. 1, 4
Skew A difference in angular alignment between image on the print
and the original document. 6
Skips Loss or stretching of the image, and compression of the
image, in bands across the process direction. 1
Smears Loss or stretching of the image, and compression of the
image, in bands across the process direction. 1, 2
Smudges Darker images across the process direction. 1
Spots Dark spots in the non-image areas of the print. Make a blank
copy
Streaks Lines on the print, in the process direction of the non-image
area. 1, 6, 7
Stretched and
distorted
images The image on the paper is stretched or distorted. 1
Toner contami-
nation on the
back of prints Random black spots or marks Make a blank
copy
Uneven den-
sity Variation in image density across the print. See also non uni-
formity. 1
Unfused prints The toner image on the finished print is not fused to the print
medium.
5
Table 2 Internal test patterns
Number Description Purpose
1 S600 Pattern, Figure 1. Light density uniformity, deletions, lines,
bands, streaks, smears, solid area reproduc-
ibility, motion quality (LSU).
2 Course grey dusting pattern, Figure
2. Skips, smears, print damage.
3 Fine grey dusting pattern, Figure 3. Print damage.
4 Ghosting pattern, Figure 4. Ghost imaging, fuser offset, print damage.
5 Dark dusting, Figure 5. Fix, white lines, white spots.
6 Skew test, Figure 6. Lead edge registration, side edge registra-
tion, skew, magnification.
7 Character test pattern (duplex), Fig-
ure 7. Light density uniformity, deletions, lines,
bands, streaks, smears, solid area reproduc-
ibility, motion quality (LSU), print damage.
N/A Blank copy 0% area coverage. Background defects,
black spots, black lines, scratches, beads.
Table 1 Image quality defects
Image quality
defect
Description of defect
Optimum
internal test
pattern