A new scanner design using plastic tubing

[bsbob]

That's what I was thinking before... a wood dowel. Cheaper than copper.

I notice the lights on this model....
BC100 Book Capture System
http://www.youtube.com/watch?v=9dSJG433Gp8


Interesting details on the motivation. Thanks.

[Catapult]

I was originally planning to mount the cameras alongside the platen on separate vertical arms. But a flash of inspiration led me to the realisation that the cameras could be raised and lowered together with the platen on the same support arms, and simply by adding to the counterbalance weights there would be no need for any extra physical human effort to lift and lower the cameras too. It would still be light as a feather. A side benefit of this was that there would always be a fixed distance bertween the camera and the page it was photographing. This would never change because the page, the platen and the camera lens would always be at the same fixed distance apart.

I left this out of my design because I was concerned about the cameras coming out of alignment since they are constantly moving, but I guessing you didn't have that problem?

[davidlandin]

I was originally planning to mount the cameras alongside the platen on separate vertical arms. But a flash of inspiration led me to the realisation that the cameras could be raised and lowered together with the platen on the same support arms, and simply by adding to the counterbalance weights there would be no need for any extra physical human effort to lift and lower the cameras too. It would still be light as a feather. A side benefit of this was that there would always be a fixed distance bertween the camera and the page it was photographing. This would never change because the page, the platen and the camera lens would always be at the same fixed distance apart.

I left this out of my design because I was concerned about the cameras coming out of alignment since they are constantly moving, but I guessing you didn't have that problem?

No I haven't had a problem with the cameras getting out of alignment. The movement of the platen is very smooth and gentle, just raising and lowering. I put a cushion at the back, below the counterbalance weights so when the platen is raised the weights have a soft landing. There is no vibration, just a smooth and soft raising and lowering motion. The cameras are firmly fixed to the arms, and it all seems to work well.

David Landin

[bsbob]

Do you have to stop and adjust the camera focus now and then while taking images straight through a book? I'm thinking not, if the cameras are in a fixed position to the platen.

I saw a post somewhere on here where the poster said they would stop and refocus the cameras periodically. Sounds like a pain.



Also, how much can you get the 'target' part of the page in the picture vs. how much do you have to crop out? It would vary by camera... And it's not like it's wasting much -- crop out a lot vs. crop out a little -- except possibly for how much you can zoom in later. What I'm wondering is if it's possible to take pics and not have to crop later.

I'm mostly interested in the information, not a great e-book. If I could take images and transform those straight into a PDF, that might work for me.

[davidlandin]

Do you have to stop and adjust the camera focus now and then while taking images straight through a book? I'm thinking not, if the cameras are in a fixed position to the platen.

Yes, you are right, it isn't necessary to refocus half way through a job with this scanner. I think if the cameras were mounted on a separate structure (not on the counterbalance arms as in this scanner), refocussing might be needed especially when scanning a thick book, because there would be maybe an inch or two difference between the distance from page to lens at the beginning compared with the distance from page to lens at the end.

Also, how much can you get the 'target' part of the page in the picture vs. how much do you have to crop out? It would vary by camera... And it's not like it's wasting much -- crop out a lot vs. crop out a little -- except possibly for how much you can zoom in later. What I'm wondering is if it's possible to take pics and not have to crop later. I'm mostly interested in the information, not a great e-book. If I could take images and transform those straight into a PDF, that might work for me.

You can zoom in, but I think you will probably want to do some cropping. I recommend the free post-processing software YASW (see this video)
http://youtu.be/__a9urAtQD4. YASW allows you to do batch cropping of the images, batch correction of keystone effects and export direct to pdf files.

David Landin

[dpc]

Yes, you are right, it isn't necessary to refocus half way through a job with this scanner. I think if the cameras were mounted on a separate structure (not on the counterbalance arms as in this scanner), refocussing might be needed especially when scanning a thick book, because there would be maybe an inch or two difference between the distance from page to lens at the beginning compared with the distance from page to lens at the end.

If your cradle can move left to right (as most scanners on this site do) during the course of scanning the book, the distance from the page to the camera on the first page will be the same as the last page. Of course if you have a split cradle and allow the book's binding to slide lower in the cradle that would affect this, but mathematically the distance should be the same at the start and end of the book.

Depending on how tight the book's binding is (and how thick the book is), you might see a small difference from the camera distance on the first or last pages and the distance when scanning the middle of the book but this will be about 1/2" with a 3" thick book. So the distance to the camera won't vary much, but the center of the page may shift a bit (which would likely affect post-proc batch crop operations). I can dig up the geometry that proves this if there's enough interest but it's pretty simple trig.

[davidlandin]

Do you see any advantage in having the cameras mounted as part of a separate structure?

[bsbob]

Weight on the counter balance arm. Wear and tear.

But it's not worth having to refocus the camera to me. Or risk messing up a bunch of images -- Take a bunch of pics, then realize half are blurry? No. Haha.


I guess a flatbed scanner must be doing the same -- Focused at a fixed point from camera to glass. I don't remember any signs of auto-focusing, not blurry images up close or clear images from farther away.

[bsbob]

What's the current thinking on lighting this model?

And does anyone have ideas of where to get non-reflective acrylic (is that plastic?) glass for the platen? If it's possible, having it bent sounds easier than gluing, but it would probably cost more. I was thinking maybe a framing shop or museum might have something. Some place where their business would be to display things.

[davidlandin]

What's the current thinking on lighting this model?

I've just bought a low cost LED floodlight. It cost about $20 US on eBay

LED floodlight 20 watt

LED floodlight.jpg (10.59 KiB) Viewed 8078 times

It is very bright. I've suspended it about 15inch (40 cm) vertically above the gutter of the platen. It is suspended on a new plastic tube coming from the top tube of the vertical frame (the one above the pivot).

It gives a very nice even light over the entire document, both pages, and it is cool to the touch. It does have some cooling fins, but so far I haven't felt any heat coming off it.

And does anyone have ideas of where to get non-reflective acrylic (is that plastic?) glass for the platen? If it's possible, having it bent sounds easier than gluing, but it would probably cost more. I was thinking maybe a framing shop or museum might have something. Some place where their business would be to display things.

I think people in the US have been buying it from a crafts store where it is sold to cover framed photos etc. I bought mine from a UK company
http://www.livsupplies.co.uk/product_li ... php?id=384 and it was very cheap (about $12 US) for the two sheets ( left and right sides) of the platen (though they charged quite a bit for shipping).

For my first attempt at making a platen I went to a plastic acrylic fabricating company, and asked them to make a sharp 90 degree bend in a sheet of acrylic. It didn't work very well. The problem was that although the curvature of the bend was quite small, it was not tight enough. So it prevented the platen from fitting deep into the gutter of the book. Basically the bottom of the V was not tight into the open book. Many of my books have very narrow margins at the gutter (the inside margins of the pages) so this meant that the images were cut off simply because the platen would not descend far enough into the book because the bend of the plastic was not sharp enough. However with a glued or screwed platen, you can get a sharp 90 degree bend that works well.