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Touch Screen Computer: Madeleine R

Page history last edited by Madeleine 7 years, 4 months ago

Project Summary: I based my project off of and article on http://www.maximumpc.com/article/features/maximum_pc_builds_a_multitouch_surface_computer?page=0,1

 Basically, these guys (Alex Castle) and his group of friends and co-workers decided to build a multitouch screen computer from scratch. They used a FTIR screen (short for Frustrated Total Internal Screen). That means that tiny IRLEDs were attached to the perimeter of the screen that shine in through the sides. When you place your fingers on this scree, they interrupt the light:

(courtesy of www.maxiumumpc.com)  

The first step to builing this was to alter the camera. In this case, I used a PS3 eye. I carved out the first "layer" of glass so that it would pick up only a certain type of light emitted by the IRLEDs: infrared light.


(courtesy of www.maxiumumpc.com)


Then I cut out some magnetic tape from a floppy disc and that served as a filter for the infrared light.



(courtesy of www.maxiumumpc.com)


I then put the camera back together and moved on to soldering the IRLEDs together in about 10-12 strands of eight lights.



(courtesy of www.maximumpc.com)


This was the longest and most strenuous part of the project. It took me six or eight weeks to solder 110 IRLEDs together. I had to redo it because I had soldered some of the negative ends to the negative ends. I was very happy to learn this as you can imagine.

After the lights were finally finished, I hooked them up to a 12 volt power supply and after many burned out bulbs, finally got to light up. It was not after some time though, that I actually hooked them up to the acrylic screen.

Whe I was adjusting and learning about the open source software that I would be using, called CCV and TUIO mouse (the receptive software and the mouse driver), I used the natural IR light from a lightbulb to experiment with the computer. Unfortunately, I had a bit of a setbcak because the bulb exploded and caught the paper put over the screen (to hold the image from the projector) on fire. All of the glass from the bulb melted into the carpet and there were scortch marks on the paper. You'd be suprised to learn that it took me three whole weeks to get "back in bussiness" in working on the computer again.

At this point, the lights were working, but the paper was ruined and the "computer" didn't even have a box or a cabinet to live in yet. But a week or two later, I had replaced the paper and had started constuction of the box.



courtesy of www.maximumpc.com


It took me quite a bit of time to figure out how I was going to go about building this. Making allowances for the lights, buying plywood, cutting the frame, and cutting the trim (harder than you might think). My box looks a bit different than the one above. My box has all four sides attached, but with a door in the side that can be opened for ventilation and closed to conceal the chaos that is the very messy interior of the computer. 

On the paper (called vellum, which is just a heavy-weight tracing paper) I spread silicon, the compliant surface, which maximizes the blobs that the camera picks up, onto the vellum.

After this was all done, I finished the frame and got to work building the trim and re-wiring the power supply to the lights so that they would fit nicely through the holes that I drilled in the sides. I adjusted a camera stand to accomodate the PS3 eye. This would make adjustment easier if I were to move everything, plus I was able to get everything out of a box full of packing peanuts.

At this point, the computer was working very nicely (after some tedious calibration) so all I had to do was find some demos to make it look cool and impressive. Turns out, it was a lot more camplicated than I thought it would be. I had to find the right version of Adobe Flash Player which this particular article was published in 2009, and they were using an older version of Adobe Flash. This took a day or so, then I embarked on a long journey of figuring out file extraction and which demos were compatible with my computer types. Eventually I ended up with one demo from www.sethsandler.com/my-software/  (the Bloom application) and the other one from http://sethsandler.com/wp-content/uploads/2009/05/fluidsolver.swf It's basically just a particle emitter activated by your finger, and it changes occasionally. Really cool stuff.

This project has been possibly the best experience of my middle school "career". Totally made possible by Mr. Howard and Mr. Slater. I will be ever eternally grateful to these two teachers for helping me through this project. Thanks.



Madeleine R




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