Canon DR-5020 - Manual (Page 84)

84
Chapter 5 Daily Cleaning
4
Use a clean, soft cloth to wipe the scanning glasses.
Be sure to clean both scanning glasses, the one below and one above.
Never spray mild detergent or water directly on the scanning glasses. The spray
could penetrate below the glass and contaminate the internal light source and
lenses.
Scanning glasses
CAUTION