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Web camera as a paper tape reader?

tingo

tingo

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I'm not really sure if this is the right forum, but I'll take my chances.

Has anyone tried to use a web camera (or other computer-connected camera) as an optical reader for (computer) paper tapes?
 
I don't know why it wouldn't work, but it would seem to be slow, given that you'd need to get a complete frame scanned before moving the tape.

Give me a bunch of photodiodes any day.
 
Well, most webcams (on modern machines at least) can easily do 10 - 15 frames per second I think, so the acquisition part should be fast enough. To mke the image processing fast enough, just ditch all but one of equal images. I am thinking of using a "slot" (for lack of a better word) to feed the paper tape through. This slot would be sized so that only one row of the paper tape would show at any time, this would simplify the image processing even more.
 
First off I should say that I have no experience with paper tape, but I do think that Chuck(G) is right about photo diodes. Surely that solution is both cheap and trivial to implement. I would think that the software would require much more work than a simple reader. Of course, many computer people shy away from even simple circuitry and would rather program their way out of a problem. Fair enough. In that case, why not use an optical mouse? I've seen them used as scanners. Just an idea. :p
 
The nice thing about a photodiode array is that the sprocket holes can be used to generate clock pulses. Then the speed becomes a matter of how fast you can pull the tape. No intelligence required.
 
NeXT said:
Can you still get photodiodes? I checked my local electronics supplier and he has not seen them in ages.
Click to expand...

Has he ever heard of a CD-ROM or DVD drive? I wonder what they use as detectors? Them new-fangled fiber-optic networks, it seems to me use PIN photodiodes.

If he needs a resource, tell him to contact Hamamatsu sales.

You could also use phototransistors. Even an LED will serve as an adequate photodiode in a pinch--and I think they're still made... :p
 
Chuck(G) said:
I don't know why it wouldn't work, but it would seem to be slow, given that you'd need to get a complete frame scanned before moving the tape.

Give me a bunch of photodiodes any day.
Click to expand...

Well, I'm trying to work with what I got (or can get without to much hassle and within an acceptable price range), and photo diodes that can work for a paper tape reader seems to be hard to get here.
 
Ole Juul said:
Fair enough. In that case, why not use an optical mouse? I've seen them used as scanners. Just an idea. :p
Click to expand...
Interesting. Do you have any references to such projects?
What kind of optical sensor sits in an optical mouse? (A bit later) Interesting, it seems that optical mice uses image processing, so the electronics would be suitable for this task, if it is possibøe to get it to work the way I want.

Later: Ok, I found this: Optical Mouse Cam and Sprites Optical mouse-cam. I have an old optical mouse with the A2051 chip. But based on the results of those tests I'm not certain that this will work.
 
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How about a bunch of good old-fashioned ball mice? Each contains at least two light-sensitive components of some kind, and you get the matching IR light source for free ;-)
 
I saw the mouse scanner on endgadet but the link is dead. I believe the second link you posted is to the same project. Ya, maybe it's not such a brilliant idea for this purpose. :( Regarding photodiodes, there's always mailorder. Some places don't mind small orders and the shipping cost is minimal on such small parts.

EDIT: I just noticed that cosam has what is indeed an excellent idea. I'd like to see some of those old ball mice put to good use. :)
 
You realize, of course, if you wanted to keep this thing completely vintage, you wouldn't wimp out with any of that solid-state stuff--you'd use an array of vacuum phototubes (still made by Hamamatsu):

8F15AD49A16847E0878789C4CF2FFE70.jpg
 
I'd vote for the sensor from an old flatbed scanner as Chuck suggested.

May I ask what you're planning to read with this gizmo?
 
I think I can get vintage tubes if you want to go that route. My buddy Joe (and me for that matter) have a lot of tubes that really have nothing to do.
 
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