There are two types of sensor in a scanner. The one I mainly used is actually a CIS (Contact Imaging Sensor) and not a CCD (Charged Coupled Device). You can either, but CCDs are really small. To cover a large screen, it's easier to use a CIS. 

I've actually mistaken CCD and CIS on the video, I will change it soon...

I ordered several CIS sensors from "ON SEMICONDUCTOR" on Ebay :

-> The CE841-60111 which has 1728 sensors on 232mm

-> The CB376-67901 which has 2048 sensors on 272mm

If they work well, it's going to be a good start for building a screen frame. 

This website is really insterresting in helping you  understand the differences.