HP Designjet T3500 Production eMFP - Manual (Page 223)

● A copied or scanned image is very skewed
In this chapter the most common defects and failure modes are shown, sorted by relevance and frequency of
appearance. A defect is a common image artifact that usually appears when using any CIS scanner. These are
due to incorrect settings, product limitations, or easily solvable mistakes. A failure mode is due to
malfunctions of some of the scanner components.
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 231 . Please do not use any printed version
of this guide to test the scanner, as the resolution of the images included here is insufficient. 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 suffering from vertical lines or streaks. Please note the black arrow
indicating the scanning direction in these examples.
Actions
1. Clean the scanner’s glass plate and the original to be scanned as described in Clean the scanner’s glass
plate on page 163 . Re-scan your original afterwards.
2. If the streaks remain, recalibrate the scanner as indicated in Calibrate the scanner on page 171 . Make
sure you clean the maintenance sheet before calibrating the scanner, and check that the maintenance
sheet is not damaged (if so, call HP support and ask for a new maintenance sheet). Re-scan your
original after the calibration is completed.
3. If the streaks still remain, check the scanner’s glass plate visually. If it is damaged (scratched or
broken), call HP support.
4. If the streaks remain, there may be dust particles inside the glass plate. Carefully take out the glass
plate and clean it as described in
Replace the scanner’s glass plate on page 166 .
NOTE: The problem of vertical streaks cannot always be solved, due to the technological limitations of CIS
technology. HP offers 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 field. Hence, the images are sharp and detailed when the scanned original is perfectly
flat 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).
ENWW Random vertical lines 213