This multitouch display screen design is based on the description in Jeff Han's paper,Han, J. Y. 2005. Low Cost Multi Touch Sensing through Frustrated Total Internal Reflection. When your finger comes in contact with the acrylic, it scatters infrared light out the back where it is visible via infrared camera. As long as nothing is touching the acrylic, very little of the light escapes, instead just reflecting around inside. Image processing takes care of detecting tips of fingers and relaying their location to application software. Since the camera "reads" the whole display in parallel, it is easy to detect multiple fingertips at once, even those belonging to multiple users. Excluding the projector and modified webcam (commodity items these days), the only thing complicated is the software. Halfway through this project, I was happy to discover that there is thriving DIY community which has already undertaken cheap Air Jordan 5 the task of writing the image processing code and several cool open source demos which can be found here:touchlib

Though my understanding Is minimal of how this works I believe that the only problem would be drawing on the surface with dry erase markers because you would be pushing on the "screen" maybe a program that creates a button in the corner that can turn off it's sensitivity on all but te button. 3v will do, since (I think) that's within the LED's electric tolerance. Then you hook up (as i said) N modules, with this I mean until you complete the average total amperage of a normal ATX power supply (commonly 19amps), with that you can plug as many LED's as you want (as long as theyre within your power supply capabilities).

Im sorry for the delay, but heres a quick schematic. The thick lines are the 3v power output from the ATX power supply, (positive and negative respectively). the rectangles are (supposedly) LEDs hooked up in series of two LEDs drawing a total voltage of 3 volts (YAY! thats exactly the same voltage than the ATX! xD), thats what we'll call a "module". If we assume that each LED draws 50 Ma (milliamperes), then each "module" will draw that amount from the power supply, if you hook up more modules to the power output of the ATX power suply in PARALLEL you can keep up until you fill the 19,000 Ma (19Amps [depending on your power supply capacity]) of total capacity. that's a HELL LOTTA LEDS MAN!

PS: im sorry for the lame paint made schematic.

PPS:I know, I made a short story long. Who cares? xD

Dear Zeeebus

i know what i wanted to ask is out of line but believe me i wouldn't ask if this was not my last chance .

I toms outlet really really need to have the PDF version of this multi touch screen here coz i took it as my major project and i have to build it in a week time and to be honest i don't have the money to be a pro member and since i'm a student i don't have any visa card as well.

I was wondering to ask if possible can you downloaded it for me and send it to my mail i would mean a lot to me .

THANK you so muchYou could, but it's not technically a camera in the same way a normal webcam or digicam is. It has a CCD array that detects a grid of light just like a regular camera, but it doesn't output video, instead it outputs a serial protocol that tells you the center coordinates of the four brightest blobs of IR light. A microcontroller inside the Wiimote camera does all the DSP of working out the blob centres.

While you could use the camera from a scrapped Wiimote (the camera itself isn't possible to find on it's own, the company that makes it ONLY makes it for Nintendo) you couldn't detect more than four fingers with it.

it would be a honer to pick a expert brain on my major project .

Contact :skype : hosseinkarimi7

most regardsI used to work in a plastics shop, and I guarantee the best options for nice clear edges are flame polishing or clothwheel wax buffing (but as buffing is pretty straightforward, and similar to other media I won't go into any tips).

Flame polishing is really the best, and potentially fastest, but you should really practice on a similar thickness scrap first because you risk burning if you move the flame too slowly. I recommend using an oscillating power sander with 200 grit, then 600 grit til the edges 2014 new air jordan shoes are silky smooth. Then use a MAPP or hotter (for best results, we even used to use oxy propane smallllll tip) torch to QUICKLY run the furthest tip of the feather of the flame around the edges at a backwards angle (so the cone is pointed opposite the direction you are moving) after all dust and masking is cleared from the edges. You'll see the hazy sanded area turn clear and reflective very quickly if you are looking at the right angle.

If you miss a spot, or if some deeper sanding scratches remain, buy cheap nike air max you can retouch with quick swipes keeping the flame even further back; if you air jordan 3 womens burn it (and its VERY easy to do if you don't keep it moving) just resand the edge with 600 grit, and use some soap and water with a cotton (or preferably microfiber) rag to remove any scuz from the faces of the acrylic sheet. NEVER USE PAPER TOWELS ON ACRYLIC they have wood pulp and will scratch it, eventually turning it cloudy.

This will give you nice crystal clear (acrylic is of course clearer than glass.) edges that will transmit wayyy more of your IR light!