due to incorrect settings, product limitations, or easily solvable mistakes. A failure mode is due to
malfunctions of some of the scanner components.
Scanner cleanliness is paramount to ensure good image quality. Before proceeding with any troubleshooting,
please make sure the glass scanbars are clean and in good condition and the pressure sliders (wide, white
plastic parts) are also in good and clean condition.
Some of the corrective actions proposed here require the use of the Scanner Diagnostic Plot, which you can
print and scan as indicated in The scanner diagnostic plot on page 167. When copying, to be sure that the
defect does not come from the printing function, use this diagnostic plot to detect any scanning issue. Please
do not use any printed version of this guide to test the scanner, as the resolution of the images included here
is
insuicient. Use the diagnostic plot when recommended in response to any of the errors described in this
chapter.
Random vertical lines
This is one of the most common issues in sheet-fed scanners. Usually, the vertical streaks are caused by dust
particles inside the scanner, or miscalibration of the scanner (in these cases, the problem can be solved). Here
are some examples of images suering from vertical lines or streaks. Please note the black arrow indicating
the scanning direction in these examples.
Actions
1. Clean the scanner’s glass scanbars and the original to be scanned as described in Clean the scanner
scanbars on page 111. Re-boot the printer and re-scan your original afterwards.
2. If the streaks remain, recalibrate the scanner as indicated in Calibrate the scanner on page 112. Re-boot
the scanner and re-scan your original after the calibration is completed.
3. If the streaks still remain, check the scanner’s glass scanbars and sliders visually. If they are damaged
(scratched or broken), call HP support.
NOTE: The problem of vertical streaks cannot always be solved, due to the technological limitations of CIS
technology. HP oers HD Scanners with CCD technology for higher quality requirements. If the streaks remain
after the corrective actions explained above, then no further action can be taken to improve the image
quality, except to buy a more expensive CCD scanner.
Wrinkles or folds
Scanners based on CIS technology have a high optical resolution within their focus plane, at the price of a very
limited depth of eld. Hence, the images are sharp and detailed when the scanned original is perfectly at
against the glass plate. However, whenever the original contains wrinkles or folds, these defects are clearly
visible in the scanned image (as shown in the following example).
150 Chapter 17 Troubleshooting copy and scan quality issues ENWW
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