DIY Multitouch Display
By Jakob Griffith on Jun 6th, 2009 at 6:51PM
I’m not sure about you, but I’ve always loved the idea of tangible computer interfaces. I’ve built some plain paper and cardboard box multitouch displays, and some advanced IR projections ones. I found that both were lacking in giving you a nice clear display to work with, so this Saturday I set out to make a multitouch system out of an LCD.
The parts required are simple. You’ll need an LCD that you can tear apart, a box, light source (60 watt bulb in my case), a camera, some film negatives, plexan/glass, and all the necessary cables.
Tools are scissors, duct tape, hot glue, and TouchLib.
The instructions are similar to building a display with just plexan, but we’ll take it a step further. I began by disassembling my LCD and removing the backlight and any non translucent material. This varies from display to display so I’ll spare you the details.
I then sandwiched it between two sheets of plexan to give it some strength. It’s being held together with hot glue.
Build a box that can hold your display, camera, and light. You’ll need to modify the camera to make it only sensitive to IR.
Finally, you should make an IR pen.
Assemble…
Install TouchLib by running the Config.bat, adjust the sliders to only read the correct ‘blobs’ or IR light. Hit enter to run calibration, finally end with ESC to save. Then you can run any Clients or TouchLib applications.
quick tip: a floppy diskette makes an almost perfect infrared-pass filter =D
[Reply]
It looks like your LCD has PCBs and ribbons coming off 2 sides, how did you join them? Or did you only need to connect to one?
[Reply]
@Borgel: Yep, I only had to connect the top one, the second just kind of sits there – I didnt even have to ground it (but its probably a good idea).
Also, a note to those wondering how my pen ‘clicks’, there is a hidden button :D!.
[Reply]
How do you right click? :)
[Reply]
Hello,
I’m quite interrested in your work. I was taking appart my lcd display (the backlight broke off).
And then I tough why not making a multipoint/multitouch screen?
I love the way you’re pointing with your homemade pen.
1. About the light, my lcd use a “plexiglas” and light tubes to light up the display. This device has no color, you can see through, why aren’t you using it to light up your screen?
2. About the multi point system, why don’t you use IR-LED inside the top layer of your screen (the protecting one) so that when your finger touches the screen the camera see-it? I’ve seen that in the multi touch technology book you can find on nuigroup.com.
With this IR-LED device you can still use your pretty pen (did i tell you that i love it :D) by turning off the IR-LED.
3. About the side connector, what is it used for usualy? I’m wondering why it’s there if you can use your screen without it.
[Reply]
What kind of monitor/lcd did you take the panel and whatnot from?
[Reply]
@Will: I dont ;D. I think if the driver detects two points of IR light, it considers it a right click, but Ive never tested.
@Nicolas: Theoretically if your backlight has no color/diffuse property then it wont light up the display anyway. Most displays have some thin film thats mirrory to reflect light through the display. I chose not to do this A. the CCFL in my monitor was broken, B. the diffuse backlight would work both ways, and my IR pen would most likely not be as accurate. It would however make it 10 times more compact, and I like the idea.
Yes, I had considered the FTIR method (with the leds in the top plexan), but I’m cheap and wanted to get it built in a day or so and not have to wait on shipping. I might order some LEDs and do it in the future though :D!
As for the connector, still dont really know what it does XD, but I figure the screen probably needs it…or else the manufacturer wouldnt have put it on in the first place. Im not about to tare it off either to test as its not bothering me.
@Bomberboysk: The screen I used is a 15inch LG Phillips model LS150X03. I wouldnt really recommend it as it is kinda small in todays age and it only has VGA, not DVI input. Any LCD (theoretically) would work though :).
[Reply]
Probably a stupid Q But were do you find the Config.bat file to install it?
[Reply]
@Mark Farrow: That is not a stupid question at all, after checking my post I found that the link for TouchLib was wrong. So you have every right to ask where the Config file is! I’ve updated the link in the post, but here is a direct link to the download…
http://nuigroup.com/touchlib/downloads/
Simple download and unzip the file to someplace and run the Config.bat inside. Easy as pie :D. If you have any more questions (including still not being able to find it), feel free to ask!
[Reply]
Anyone know were I can find a Inferred LED?
[Reply]
I found mine on EBay really cheap. I paid $7 shipped for 100 (of the correct wavelength) with resistors.
[Reply]
Thanks. You mentioned wavelengths. How do I know if I’ve got the correct wavelength (I’m thinking of stealing one form a TV Remote).
[Reply]
Ah, I accidentally confused your use. If you only need one, then yeah, one from a TV remote would be fine I would guess. I was building a larger table that detects fingers, and so I needed many for a somewhat different usage.
In any case, I think mine were 850nm. But the NUI group’s forums (as mentioned before, but located here [http://nuigroup.com/]) is the best website I’ve found so far for finding information. So I think that was where I went to find out what wavelength of IR I needed. I strongly recommend you peruse the resources available there.
[Reply]
hi, im fascinated with this, you are awesome!, want to make some question(somehow dumb).
about the backlight, i can use an hi-intensity LED grid array or CCFL tube on the bottom of the box to make it brighter?
borgel said “correct wavelenght” what about that, what will be the specs of the leds i will need to use if i choose to put them into the protective layer plexan?
many thanks and sorry for so slefish questions
awesome work, thank for sharing it
[Reply]
@ivan quaglia: If you plan to use a method such as mine, where you use an IR pen, you can use whatever method you wish to light up the LCD. I would think a white LED array with perhaps a small diffuse layer between it and the screen would light it up nice and bright, but still have accuracy with the pen tool.
What Borgel is trying his hand at, is called FTIR. By using an array of IR LEDs (at the wavelength of Infrared light) along the edge of the top layer of plexan, you will not need a pen tool. Rather your finger tips touching the plexan will act as said pen. I however, havn’t had a chance to try this method, so I cant tell you much more. And this method would still require some form of lighting up the LCD.
Best of luck to whichever you choose!
[Reply]