Hello Community

When i first saw Jeff Han’s Multitouch introduction i was blown away. I got instantly infected by the idea to have and build such a multitouch screen… After searching the net for a while i found this community. Here i found all the relevant information on how to build one. So a *BIG HUG* goes to the whole community for sharing your knowledge and work! I finally decided to go with the DSI concept and a LCD and make it portable.

porta∼touch - portable 24” DSI - LCD MT

Specs:

Benq 2410 HD LCD Panel (1920 x 1080 Pixel)
8mm Endlighten XL Plexiglas (Touch Panel Frame)
IR-Led-Ribbon 850nm with 160 Led’s
8 mm Endlighten XL Plexiglas (for the Backlight)
2 Original Backlight Tubes from the Benq 2410 HD Panel
Unibrain Fire-i Firewire Camera, 30fps, 640x480 Pixel, 81° Wide Lens
850nm Acrylic IR-Longpass-Filter
MacMini Core 2Duo 2.66 Ghz running OS X Leopard, CCV 1.2, ReacTIVision 1.4 and Quarz Composer
Fiducial (with ReacTIVision) and finger recognition (with CCV 1.2 / 5 ms response latency)

Mounted Dimensions: 75cm x 45cm x 35cm (W x D x H)
Mounting Time: 3 min. with 12 Screws, few cables
Boxed Dimensions in Flightcase: 75cm x 45cm x 15cm (W x D x H)

Layers:

- 8mm Endlighten Touch Panel Frame with IR-Led-Ribbon
- Benq 24” LCD Panel
- 8mm Endlighten with Backlight Tubes on the long sides
- 3mm Plexiglas on Aluminium Frame as Mounting Surface
- Fire-i Camera mounted 30cm under Touch Panel

Issues:

- The Backlight is just bright enough, but there is no overhead if i need it brighter. So maybe i add two more tubes on the sides of the Endlighten.
- The IR-Longpass Filter is not perfect. It still sees some light. I want to try a steep bandpass filter for better results.
- A HD Cam with a resolution of 1280 x 720 (Logitech Pro 9000) may give a better touch response on the sides of the screen compared to the 640 x 480 camera since it has to cover the touch range of 1920 x 1080 pixels and it’s distorted because of the wide lens.
- The screen with it’s ratio of 16:9 isn’t perfect to use and hard to calibrate with ReacTIVision. So i’m waiting for CCV with fiducial support

Being a total noob in coding i ended up with visual programming to fiddle some sort of MIDI-Controller with Quartz Composer. It is in a early alpha stage. Enough writing. Here is the result of the last weeks of work.

cheers
rob

Really good work. I have been planning on doing something very similar but haven’t found the time yet.

Really stunning work Rob… that kit is very clean great work all around and thanks for sharing

thank you for your kind comments!

Excellent work!

A very nice setup man, I like the midi interface thingy you show.
The future looks promising.
Anyway, I was thinking of doing an LCD DSI myself, but my biggest concern was the fact that Endlighten would distort and blur the image from the LCD.
Some people here on the forum claim that Endlighten isn’t good for LCD DSI for this reason.
What’s your perspective on that? I cannot really tell from the vids you’ve posted, because of the somewhat poor quality.

Also you mentioned that the brightness of your screen is marginal with the original tubes from your LCD.
The Endlighten reflects some of the visible light downwards to your cam, this could technically be solved by placing a cold mirror in between your cam and the Endlighten.
This reflects the visible light back to you LCD, but allows the IR to go through though.
I’m still trying to find some kind of cold mirror film or a larger piece of cold mirror (acryllic or so), but till now no success.
(Anyone else here familiar with this kind of material?)

Regards,

Michael

thanks boogieman.

i don’t think the endlighten is distorting or blurring. i don’t want to open it up again to see the difference.
it is less bright and a bit blurred because the polarizers and the white reflective backfoil of the lcd are missing.

attached are two pictures i took from a 17” macbook and the 24” portatouch.
the quality is not that bad for me, bit brighter would be perfect…

maybe your proposed cold mirror is the solution… will investigate.

cheers, rob

left is macbook - right is portatouch

Congratulations! Very good job with your DSI-LCD.
Just a question: Is the Backlight Tubes you use are the orignal ones inside your Benq24 screen ?

hi speedman, yes, the tubes are the original ones, like i wrote in the specs…

Hey Rob,

Thanks for the update.
The pictures show little difference between a regular lcd image and the same image behind Endlighten.
This should be good enough for my future setup.
I’m planning a 2 Player MAME Bartop Multitouch Cabinet (19” 4:3).
And if all goes well I would love to try interfacing with Ableton Live, but let’s not jump to conclusions…
I’ve got miles ahead before even getting there…

Anyway...I’ve got some more questions:
- Did you use larger Endlighten than you screen size?
- How did you stack all layers? Is it possible to stack them all onto each other or do you need a small gap between some layers?
- What audio app are you intending to use you beta midi controller app for?

Regards,

Michael

hi boogieman

yes, the endlighten is about 10% bigger as the LCD which is still in the original frame without polarizers and rear planel mounted on a plexiglas. sandwich design… i only replaced the backlite-plexi with a new endlighten. on top is the frame containing the IR-Leds and the endlighten to touch. there’s no gap between the layers.

the midi controller works with all applications that are capable of midi… but i will mainly use it with ableton live and logic pro.

rob

Very nice!

This makes me want to rethink my whole design stratergy!

I love the flat pack soloution.

Great job

You could put the white backlight foil back in again, on the back side, or maybe even a mirror, so that all the light is thrown upward towards your screen.
You could also think about setting up white foils at the side, but I think they wouldn’t be too effective.

@boogieman: Now there is an interface for ableton live, just saw it here on NUI:
http://nuigroup.com/forums/viewthread/8692/

Greets, Mastermind

How is the ficudal response in the center of the screen? Significantly blurred or trackable in the center and getting worse toward the edges?

Hi Connor

yes, it’s good in the center and gets worse on the sides… that’s because it gets distorted by the wide-lens on the camera and also because the camera is 4:3 and the screen to cover is 16:9…

How do you mean the polarizers are missing?

Can you explain a little more in detail. isn’t the polarizer a layer built in the LCD?

tx in advance,

Goran

portatouch - 20 January 2010 05:43 PM

thanks boogieman.

i don’t think the endlighten is distorting or blurring. i don’t want to open it up again to see the difference.
it is less bright and a bit blurred because the polarizers and the white reflective backfoil of the lcd are missing.

attached are two pictures i took from a 17” macbook and the 24” portatouch.
the quality is not that bad for me, bit brighter would be perfect…

maybe your proposed cold mirror is the solution… will investigate.


cheers, rob

left is macbook - right is portatouch

This is a really cool design! Kudos! Right now Im trying to build a pretty sizable one for myself as well and was going to use it as a eating table/ entertainment piece. I also am going to use it to test my programs im writing for touch. How do you handle the heat? And how does this design work for you?