My camera has a resolution of 640x480 and a low-ish frame rate that I don’t know for sure…

What size of screen should I build that this camera will work tolerably for? I was hoping for about a 34 x 26” display. Is that possible with such a low resolution for sensing the touch?

640 x 480 is actually standard. Anything higher resolutions is hard to find without paying a lot.

The biggest issue is how easy it’ll be to remove the IR filter. You’ll need to either buy a wide angle lens or use a mirror to get a long enough throw to see the full display (34” x 26").

Actually I was very lucky in that the camera can already see IR. I was using my TV remotes to draw stuff in smoke yesterday.
thanks for the mirror suggestion though : )

I don’t mean to spoil it, but all cameras can see some IR pretty much. You’ll still need to remove the IR filter eventually. A remote control / IR light will totally white out the camera when the filter is removed vs just showing up as a blog on camera (with the filter on).

oh....ha ha, that’s ok. I guess I don’t mind removing the filter. Where can I find out how to safely remove the IR filter from an older Quick Cam logitech webcam (PIN 861193-1000)?
Also, If it’s not too much trouble I’d like some advice on what kind of IR LEDs to get. I found this inexpensive kind:
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=QEC113-ND
I can get 10 of them for just a couple dollars, but does that mean they won’t work? Is ten chep IR LEDs enough for a 34x26 display?

these LED’s are way too weak for achieving any blobs… a good way to decide which ones to buy would be to go thru the spec/data sheets and look for the Radiant Intensity at the typical current range of 100mA - 150mA ... these are rated at 14mW/sr .... anything less than 80 - 100 mW/sr wont give desired results…

hope this helps

cheers!!!

I’d search the forum a bit as far as removing the quick cam filter.

As far as the LEDs, I’d say 1 led every inch on both long sides is best (at minimum). So no, 10 won’t nearly be enough. Also, the cheaper the LEDs usually means the specs aren’t as great and therefore you’ll end up needing even more LEDs. So it’s better to go with good ones (since you’ll need less and it’ll cost only slightly more.) A lot of people are using ORSRAM 485

and for a similar size setup of mine (32” X 24") i am using 60 LED’s rated at 130mW/sr ... 30 to each long side.. spaced at 1” .. most would agree its a bit of overkill but it gives me super bright blobs and works in daylit indoor conditions as well!!!!

Excellent! I will use 60 OSRAM LEDs. I’ve decited to go with FTIR because there is more available help than for DI. Is silicon rubber the best thing to use on top of the acrylic?