dtic wrote:jck57: I've not had any problems caused by the length of the arm/finger. Exact movements are more important for side finger(s). The page grabbing finger in my arduino setup works well as long as it hits somewhere in the middle of the book, so it moving a little now and then doesn't matter much. I've only had problems with too many pages being grabbed and with the tape losing stickiness of course. (To use tape reliably some mechanism for feeding fresh tape strips to the finger head automatically would be needed. But I doubt that would work well. Tape is only good for prototyping.) But long fingers are likely less durable and makes the build bigger and slower so I'm eager to see design that improve on that front.
I've attached the arduino sketch.
Thanks. I saw you are using a serial hookup. What is the reason?
Are the two small page holders in the second video Snaguy posted ( A Kirtas APT 1200;
http://youtu.be/Kp3LhkT1jZY ) close to what you had in mind for a platenless scanner jck57? I like that scanner.
Something like the Kirtas, yes. My latest idea is for two V-type tabs that hinge down at the top and bottom of the crease. This should be sufficient to hold the pages flat for scanning.
Some thoughts:
- to prevent extra pages from lifting two problems need to be solved: the vacuum finger must not lift more than one page and the tendency of adjacent pages to "follow after" the one page being lifted anyway (not caused by the suction per se) must be blocked. That second problem is caused by the binding of the book. Flexing the book before scanning will likely decrease but not solve the problem. The Kirta machine doesn't have any mechanism that blocks the second problem from what I can see.
Although it is hard to see, the Kirtas does have a little flipper that hinges up and hangs in the path of the flipping page. Thin and springy, It contacts the page at the back right corner area as the page is moving from right to left. The Treventus scanner has something like it: a rod with plastic (rubber?) tip that extends in from the right side and contacts the page as it lifts. If I return to working on the pneumatic scanner I may try something similar.
- for the fingers to move in/out up/down the machine needs not just small, cheap servos but also solenoids.
We'll see if it works, but my plan is for the reciprocal movement of the turner to be accomplished with a servo and connecting rod acting on a drawer slide. My present idea for the lifting finger is a servo arm with spring loaded elbow. I'll have to post a drawing or a protype pic.
So one task is finding a good source of inexpensive solenoids (preferably some international webstore similar to dealextreme.com ) that work well with arduino.
- if a platen is replaced by fingers moving in and pressing page top/bottom margin then the finger positioning presents a new challenge. Too far out and the page won't be pressed down. Too far in and they will cover text that was to be scanned. In the Kirtas video they scan a hard cover book. It looks like the margin fingers are secured to a part that is clamped to the hard cover edges. I guess they calibrate the fingers position manually for each scan based on the distance between the hard cover edges and the page edges. But what about paperback books then? A platen avoids those problems.
My plan is for the hold down fingers on one side of the book to be adjustable for different book page heights. Yes, the covers need to be clamped to the cradle so the book stays positioned. Hopefully, a clamping method safe for paperbacks can be found.
Thanks for the comments
But I still don't see it. Did you mean some other Kirta model? Or is it the component to the bottom right, which I thought only clamped the book in place.