The mechanism that controls the simultaneous opening of the scanner (top cover) and the DF prevents the DF from falling.
When opening the top cover, the DF locks and does not open.
When closing the DF, the lock of the opening and closing lever on the top cover unlocks.
The top cover will open slowly when it reaches a 90 degree angle due to the brakes [A], the spring [B], and the hinge brake [C].