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Optical reading of paper cards/tape? Answered

Hi everyone, 

I wanted to know what would be involved in reading the position of dark marks on paper cards or tape, a la IBM. Something that can read the information from the card with things like pencil/ink marks instead of holes punched through it. 

What would I need? Could I get away with basic LEDs, or would I need something more complex like a CCD from a scanner? 

Many thanks!


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Best Answer 5 years ago

Depending on the size of the marks and assuming a good contrast level is there it should be enough to use photodiodes.
But if you want it easy use a scanner and a mask in the software to filter the results.
AFAIK IBM used a technique similar to our optical mouse just that instead of reflection "see through the holes" was used.
Of course a barcode scanner with modified software would do as well as a modified QR code scanner app on your mobile....


5 years ago

You can probably do it with a webcam these days