Introduction: The Footsie Book Scanner
There are many people across the world making devices to photograph an opened book with a digital camera.
The basic principle used is to hold the book against a glass (or sometimes plastic) platen, and to take the photograph through the glass, with illumination from above. See the diagram above. Most of the scanners built to date have moved the platen down to the book, and moved the book sideways as pages are turned by hand. I have decided to develop a scanner which moves the book up to the platen. This has resulted in some novel techniques.
By googling for “book scanner” you can find a discussion group covering all aspects of the subject.
Step 1: Platen Made From Picture Frames.
This photograph shows the completed platen. The frames are of wood, with sufficient material to enable the assembly to be held rigidly in position relative to the cameras and lighting system. The book will move up to the platen in this design. The end pieces or side cheeks are from 3mm MDF sheet, strengthened where appropriate with wooden struts. Glue is used to hold everything rigid.
Step 2: Picture Frames
This shows the two frames bought from a local store for £7 each.
Step 3: MDF Template
The angle between the two sheets of glass needs to be about 100deg. This is set up from an MDF template.
This shows the template with the lines of sight of the cameras and the illumination marked out. The template is used throughout the assembly of the scanner.
Step 4: 100deg Angle
This shows how to mark out and cut the 100deg angle in 3mm MDF.
Step 5: Mitred Frames
This shows the frames with the glass removed, temporary struts attached, and one frame side removed from each frame.
Step 6: Side Cheeks
The template is used to make the side cheeks.
Aligning the two frames is the most tricky part of the assembly. The two glass edges must just touch along their whole length. The glue is then applied to form a rigid structure. Lots of small G clamps are needed.
Step 8: Close Up
A close up of the glass edges. Not perfect, but probably OK.
Step 9: Edge Protection
This shows how wooden barbeque sticks can be glued along the V joint to cover the sharp glass edges.
Step 10: The Platen Ready for Assembly Into the Support Structure
Step 11: Scanner Frame
This photo shows the upper portion of the frame that supports the platen, cameras, lamp for illuminating the book pages, and screening. It is important that stray light doesn't get reflected from the platen glass. This particularly applies in my workshop, since it has roof windows.
There are just three vertical struts that make up the frame, of 50mm by 25mm planed timber. This gives a rigid but lightweight structure when attached to the platen. The flat roof gives strength at the top, and supports the side screens and the lamp (a 10watt LED floodlight costing less than 10 Ukpounds).
The two side struts are located at the mid point of the platen, hence can be used to hold the camera mounts (see below).
Below the platen, there is ample room to install the book lift and to provide access to the book for pages to be turned by hand.
All three struts are secured to a floor on which the book sits (before it is raised up to the platen).
Step 12: Camera Mount
A 50mm brass hinge holds the mount to the side strut. The mounting bolts should be smaller than the holes in the strut, so that the camera can be aligned about this axis. Adjustment in the other axis is provided by the slotted aluminium strap. This arrangement makes it possible to take photographs of the book page that are truly rectangular. I am using Canon A810's, bought second hand from eBay.
Step 13: Pulleys
Ideas for the book lifting mechanism were derived from historical hand looms and pole lathes. Motive force comes from a foot pedal via a rope and pulley system. The pulleys are mounted just below the attachments for the platen to the side struts. Pulley wheels are removed from assemblies bought from eBay. They are drilled out to fit the diameter of brass woodscrews, and assembled into MDF blocks. These in turn are screwed onto the side struts (see above). The rope is 4mm diameter, used for hanging pictures.
Step 14: Book Lift
This shows the layout of the foot pedal,rope and book cradle. The small foot pedal is used to send a switch closure signal to the cameras.
Step 15: Book Cradle
It was found that a very simple hinged cradle gave the best results. The outrigger arms ensure that the rope runs more or less vertical, with enough freedom to let the book move sideways as the pages are turned.
Step 16: Video
This shows how pages are turned, and the book helped into position by hand.
I've decided to give the scanner a name --- The Footsie BookScanner
To come – cameras, electronics and scanned images