There are a few possible causes for why a scanner is producing blurred images. The most common cause is due to the resolution, or DPI (dots per inch), being too low. If the DPI is set too low, the resulting image will be blurry since each dot of color won’t be adequately represented. Additionally, if the area being scanned is larger than the document size, this can also result in blurred images.
Another potential cause of blurry scans is if the scanner’s focus is incorrect. All modern scanners have lenses that allow them to focus on either side of the document, depending on whether it’s letter-size or legal-size paper. If the scanner is incorrectly set for the wrong document size, the resulting scan will be blurry.
Another likely culprit is if the glass on the scanner’s plattern isn’t clean. dirt, smudges, or other debris on the glass can cause the light from the scanning head to be diffused, resulting in a blurred image. Regularly cleaning the scanner glass with window cleaner and a microfiber cloth should help alleviate this issue.
Lastly, some older scanners may just not be able to handle higher resolution settings. This is especially prevalent in flatbed scanners that do not feature a digital screen. If the settings are pushed beyond what the scanner can handle, the images will be distorted and blurry.
In short, a scanner producing blurry images typically has to do with incorrect resolution and focus settings, dirt on the scanner glass, or the device being too old to effectively scan at the desired resolution.