Brainstorming about portable book scanners.

[spamsickle]

The "different sized pages" thing is probably a problem that's unique to my initial setup -- no fixed-to-a-column platen, and no sliding book cradle. My cameras were fixed, and my book cradle was fixed, so the first page of a 3-inch-thick book was three inches closer to the camera than the last page.

I don't think you'll have that problem per se with the platen-on-a-column and sliding book cradle, as the plane of the page should be the same distance from the camera for you too. The problem I think you'll still have is that the in-frame position of the first page of that 3-inch book will be 3 inches "higher" than the last page. With the camera attached to the platen, you'll theoretically get each page framed more or less the same way.

I think you should be able to use manual focus with your setup as well.

[daniel_reetz]

Thanks, I understand now. I'm making a folding scanner - each part of it collapses somehow. Camera mounting is proving to be the greatest difficulty so far.

[you1]

Spamsickle, You1,

I'm starting the build of my third scanner. What do you think are the advantages to having the cameras move with the platen like that? I'm having a hard time imagining why you'd want to do it.

Sorry for the delayed response...
As already mentioned, the major benefit of mounting cameras is that cameras will no longer need refocusing (and can be locked). I'm guessing with a good design, the vibrations should not be an issue!

Now for the bad news.... the above design is a flop and should be avoided or revised for the following reasons:
1) when trying to raise the glass platen, the two sides of the ears are uneven and thus, I am unable to raise the platen with one hand
2) Because I intended to add a handle to the platen, the raise puts stress at the pinched area, which could lead to breakage. I don't know if counter weight could help!

To make the above system "possibly" work, I think the top of the cameras need to be connected (upside down U), where the light can also be mounted on it. A handle against the top of the unit can help raise the lights, camera and platen.
With all these elements the counter weight would certainly be helpful. (see image)

Alternatively, rather than using the "pinching" glass idea, a strong frame around the platen can act as the base of the U connection.


Daniel, the beauty of your original design was its simplicity.
I'm not sure if even if the above design works, it is worth the effort.


Best,
Edvin

[xylon]

perhaps counter weights with pulleys would help. like the mechanics of a double hung window.

[you1]

perhaps counter weights with pulleys would help. like the mechanics of a double hung window.

Possible...

I'm scrapping the effort. Too much effort / complexity when the project doesn't seem to be working
I keep thinking KISS (Keep It Simple Stupid) to myself.

[Kirtai]

For a portable scanner, having the platten upside down with the book lying on top, and the cameras underneath it might make for a more rigid structure, though it'd be more work to actually scan with. The SVG at http://www.tekstadventure.nl/branko/inv ... canner.svg shows the idea. (Not my image)

[you1]

Since we are discussing new ideas...

I like to refer to another user's build who commented on instructables during the early days of the scanner.
Unfortunately, I could not find the link; however, his design looked something like the below image. Which I think we can make collapsible for portability.

[daniel_reetz]

That was Ian from BKRPR.org, which is a sort of "sister project". We have essentially the same idea. Ian contacted me and was looking for developer help (right before the launch of this website). He never replied to my reply, but I'm assuming they're still out there and I hope they are doing well.

http://bkrpr.org/doku.php has the basics of their project, including a youtube video. Their design could well be made portable, especially with my hinged platen, but for whatever reason I want to try a few other things first.

[you1]

...for whatever reason I want to try a few other things first.

I think that's a great idea.

BTW, I moved the rollers to the back; and with a spring, the platen raised "okay". In the next couple of days I intend to use a counter weight instead of the spring, which I'm sure will be magnitudes better.

[daniel_reetz]

Cool!

I moved the rollers to the back;

Good to know. My friend John has some kind of weird high-stability linear bearings he's going to give to me, probably tomorrow -- I'll post if they're anything special.