curved plastic platen

[denbox00]

I came across these pictures of the "Travellers Book Copier." One of them shows a curved plastic platen. What do you think the reason is for the curve? Does this cut down on glare, given the placement and proximity of the lights?

[daniel_reetz]

It may simply act as a spring, so that when you apply pressure the page is flat as can be. Very interesting, and a new idea to me.