Canon H12157 - Manual (Page 104)

4-10 Paper Handling Chapter 4
You can also use face-up delivery when printing or receiving a large
number of pages. In this case, remove the extension tray and place the
unit on the edge of a table. This will allow the pages to fall away from the
unit and avoid blocking the face-up delivery slot. You may also want to
place a box below the unit so that the pages can collect into the box. N