Canon MF3110 - ImageCLASS Laser Multifunction - Page 33

Chapter 2
2-5
Drum Cover Shutter
If the surface of the photosensitive drum is exposed to strong light, it develops what is know as "photo memory,"
which can cause white spots or black lines in images. To protect the drum against light, the machine is equipped with
a drum cover shutter. The drum cover shutter must never be opened unless doing so proves to be absolutely
necessary.