I spend ~185 euro
may you can excuse my bad englisch ;D
Things you will need:
1 webcam - modified this way
~50 IR-LED's I used these ones
stuff to make the LED's work
for example wires,10 resistors and a power supply unit
1 acrylic glass
1 transparency paper
Things you will need to setup the wooden box ,... for example wood ;D
Power glue ;D I used Patex extreme repair
other great intructions :
by turkey tek
and Christopher Jette
Step 1: How Does It Work ?
Basically I'm working with infrared light.
LED's placed all around the acrylic glass 'fill' this acrylic glass with infrared light due to the total internal reflection. If you now touch the acrylic glass your finger reflects infrared light and the infrared webcam will see it. you may take a look at the image below to understand.
picture was taken from here
the picture coming from the webcam can now be read by tbeta or your self-made software ;D
this technique makes it possible to read many user interactions at the same time.
for further information on my setup please see the second image below
1) acrylic glass
2) infrared LED.
Step 2: Assembly
Your setup may be very different to mine
but there are some things that are quite important.
the degree between the light that falls on the mirror an the light that is reflected should be as small as possible !
otherwise you may see a green shadow on your display.
next thing is that transparency paper is not cheap but worth it, if you have to buy some sheets take the good ones. but may you can get something from a construction business too.
do also take care of your acrylic glass. you can cut it with any saw you like to use but if the saw blade is to small the acrylic glass will melt together immediately.
and if your edges are not totally clear finish them up with some fire or a hot fan.
Step 3: How to Mount the Screen
Just glue everything together until you know how big your screen will be
first layer frotm the top to the bottom is the acrylic glass with the led's
next layer to consist of wood, connecting the led's and the acrylic glass
last layer is the transperency paper
I connected 5 led's in a row with a resistor
and this parralel 10 times. therefore i used 50 led's and 10 resistors with 37,5 ohm
everything ist connected to a 12V power supply
Step 4: Software
Step 5: Conclusion
this is a very short instruction
but I am looking forward to add some more pictures of my setup the next days.
may there will also be a better video of my screen in action ;D
If you want to learn more you can visit
and Christopher Jette
their explanations are much more detailed.
please tell me if you also realized your multitouch device ;D