Comments on: DIY Multitouch Display

By: Mitch

Mitch — Fri, 27 May 2011 13:45:44 +0000

I know this is quite an old post, but I can’t seem to find the answer to this anywhere.
Does the LCD screen not provide it’s own light? Is that what the backlight is for?
It may have been better explained in the video, but the link is dead.

By: Jakob Griffith

Jakob Griffith — Wed, 25 Nov 2009 00:53:54 +0000

@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!

By: ivan quaglia

ivan quaglia — Sat, 21 Nov 2009 11:47:14 +0000

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

By: Borgel

Borgel — Tue, 10 Nov 2009 04:34:14 +0000

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.

By: Mark Farrow

Mark Farrow — Tue, 10 Nov 2009 04:21:42 +0000

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).

By: Borgel

Borgel — Mon, 09 Nov 2009 20:44:09 +0000

I found mine on EBay really cheap. I paid $7 shipped for 100 (of the correct wavelength) with resistors.

By: Mark Farrow

Mark Farrow — Mon, 09 Nov 2009 17:01:30 +0000

Anyone know were I can find a Inferred LED?

By: Jakob Griffith

Jakob Griffith — Fri, 06 Nov 2009 15:37:10 +0000

@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!

By: Mark Farrow

Mark Farrow — Fri, 06 Nov 2009 14:58:00 +0000

Probably a stupid Q But were do you find the Config.bat file to install it?

By: Jakob Griffith

Jakob Griffith — Wed, 10 Jun 2009 01:30:56 +0000

@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 :).