A flatbed scanner document scanner includes a large format document scanner body accommodating a rectangular rigid frame with an upwardly facing plane face and a rectangular transparent plate for supporting a large format document. The rectangular transparent plate overlies the upwardly facing plane face all around the metal frame. The scanner also includes a movable carriage configured to move along and below the rectangular transparent plate and carrying a line camera extending across the rectangular transparent plate. The rectangular transparent plate and the metal frame are bonded together by a hard glue seam that runs on the upwardly facing plane face of the metal frame. A predetermined deflected shape can be formed when the bonded plate and frame are turned upside-down. The rectangular metal frame can deform under its own load to a cambered shape, a flat shape or a less deflected shape when turned upright in a normal position.