Comments on: LCD Multitouch Table Mark 1

By: LCD Displays

LCD Displays — Fri, 11 Mar 2011 12:38:31 +0000

I love these home made touch screen projects, so mean seem to be popping up all over the web, it makes you wonder why companies like apple charge so much for these things?!

By: LCD Display guy

LCD Display guy — Thu, 29 Jul 2010 10:21:45 +0000

That is probably the coolest mod I’ve ever seen, home made touch screen table.

Would any other touch sensors be viable to work with on a home project for example resistive, or is that likely to put oo much strain on the LCD?

By: Industrial LCD

Industrial LCD — Mon, 21 Jun 2010 15:39:45 +0000

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

By: Stewart

Stewart — Mon, 03 May 2010 01:27:18 +0000

Hi John,

I asked the suppliers to polish the edges after cutting. I’m not sure what method they used. The surface looked pretty smooth, though it was not completely “flat”, probably cut with a bandsaw. If it is laser-cut then you’d probably get a better finish.

A flat, highly polished surface is more important for FTIR designs, where you need as much internal reflection as possible. If you are using a DSI design (with Endlighten), its probably not that critical.

Are you sure you’ve got enough power to your LEDs? If you’re using the flex ribbon you’ll need at least a 2A at 12V. Check the data sheet for the power consumption per meter.

By: John

John — Sat, 01 May 2010 18:59:48 +0000

Hi again,

You site is a big help and thanks for answering our questions.

Did you polish the edges of the acrylic? If so, what method did you use?

I polished mine with 320 - 400 grit sand paper and then a buffing wheel on a drill.
It doesn’t have the same finish you would expect from something like flame polishing and I am afraid that it the way I will have to go.
I am just not getting the IR lights into the acrylic good enough.

Thanks again,
John

By: Stewart

Stewart — Tue, 06 Apr 2010 02:43:01 +0000

Hi John,

Here’s the part description from the invoice:

1 x Narrow Dimmable LED Ribbon Flex by the 5-meter reel
(InfraRed 850 nm) (irrf850-reel)

At the time, the cost was $177 plus freight.

The size of the acrylic depends on how you’re going to mount it. I ended up mounting the acrylic as the top surface of my box, so it rested on top of the four sides. I made it big enough for a 25mm border on all sides. Initially I was going to sandwich the panel between the endlighten and a separate smaller sheet of perspex, but in the end I supported the panel on a small ledge inside the box. An advantage of the “sandwich” idea is that the whole assembley is more-or-less self supporting, but if you include the driver board in the sandwich its quite a bit larger on the top side. Make sure you support the weight of the acrylic - don’t just rest it on top of the LCD or you’ll end up distorting or cracking it.

Hope this helps.

By: John

John — Tue, 30 Mar 2010 22:53:39 +0000

Sorry, I thought of another question.
How much larger should the Acrylic be than the actual LCD?

Thanks again,
John

By: John

John — Tue, 30 Mar 2010 22:14:20 +0000

I am looking on Environmental Light’s website and see 658 mW/meter and 1,752 mW/meter brightness. Which one did you use?
Do you still have the part number?

Thanks
John

By: Stewart

Stewart — Thu, 25 Mar 2010 22:05:19 +0000

That’s what I thought would happen, but it doesn’t seem to work. If you put IR illuminators behind the LCD, you don’t get any signal back from the front surface. I’m not sure of the reason, but I haven’t found anyone who has got it to work that way.

By: vossler

vossler — Thu, 25 Mar 2010 19:18:29 +0000

Hi Stewart,

Impressed work!

I am curious if you put some IR LEDs in the table’s bottom, is that gonna make fiducial marker more clear?