If you look at the claims they actually patented this (I translated it into English):
> For a scanner with a near and far end, position one cart near the near end. Remove a tray from the cart. Pass it through the scanner. Put the tray in a second cart at the far end of the scanner. Move the second cart to the near end of the scanner.
I'm not exaggerating. That's what claim 1 says. If you do that they can sue you for infringement.
The subordinate claims talk about stackable trays, but you only have to infringe claim 1 to be infringing. Claim 1 is written as broadly as possible in order to "catch" as many infringers as possible, and then the subordinate claims are there in case the courts actually rule that claim 1 was too broad.
So you can say "Fine, we can't patent using a cart to move trays, but what about claim 3? We patented using stackable trays! That's very novel!"
> For a scanner with a near and far end, position one cart near the near end. Remove a tray from the cart. Pass it through the scanner. Put the tray in a second cart at the far end of the scanner. Move the second cart to the near end of the scanner.
I'm not exaggerating. That's what claim 1 says. If you do that they can sue you for infringement.
The subordinate claims talk about stackable trays, but you only have to infringe claim 1 to be infringing. Claim 1 is written as broadly as possible in order to "catch" as many infringers as possible, and then the subordinate claims are there in case the courts actually rule that claim 1 was too broad.
So you can say "Fine, we can't patent using a cart to move trays, but what about claim 3? We patented using stackable trays! That's very novel!"