Multitouch screen with an TFT Panel! 
Posted: 01 August 2008 04:39 AM   [ Ignore ]
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Hi all,

I will use the panel of an 19´´ display.
I hope that the tft panel will pass the ir-light so that it can go through it to my fingers and then back to the camera!
here are some pictures of my multi touch table. it isn´t finished yet but tomorrow i will get the web-cam and can finish it…

I used 20 IR-led´s
2 halogen lights (12V!)
19´´ tft panel

in the middle of the ground in the box i install the web-cam.

Does someone know if the panel will pass the IR-light???
and if you have any idea for improvements tell me!

thanks for answers and sorry for my broken English wink

greetings from Germany

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Posted: 01 August 2008 05:10 AM   [ Ignore ]   [ # 1 ]
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I think the halogen will kick out tones of infrared! You would be better off replacing the bulbs with white led type ones these don’t emit any infrared, or else you’re gunna get hotspots all over your screen, its gunna be an infrared blood bath!!!

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Posted: 01 August 2008 07:20 AM   [ Ignore ]   [ # 2 ]
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ohh that´s terrible!
thanks for the advicesmile
i have good connections to a company who produce led´s...the company is called vishay and temic (maybe you know themwink )
so i had ordered 30 super-bright and white led´s smile smile
maybe it will work with them

today i installed the electronic from the panel!

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Posted: 01 August 2008 08:32 AM   [ Ignore ]   [ # 3 ]
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My backlight also shed a TON of IR light and totally flooded my camera with a block of white light.  However, I was able to cover it with two sheets of Heat Control Window Film from a local hardware store.  It eliminated all the IR light and only affects the light a small amount.  Plus I’ve still got the even lighting with the original backlight.  If I need additional brightness I may add a couple rails of LED’s that don’t cast IR.

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Elemental Multitouch Project ~ http://eleme.ntal.ws/

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Posted: 01 August 2008 02:03 PM   [ Ignore ]   [ # 4 ]
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so i changed the halogens...into 26 white led´s they are enough that i can see the windows screen on the panel
in the picture only the outline of the led-range is powered on!

greetings henrik

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Posted: 01 August 2008 02:49 PM   [ Ignore ]   [ # 5 ]
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tomorrow i will finish the hardware so i can so i can see with the software if everything is all right!

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Posted: 01 August 2008 05:55 PM   [ Ignore ]   [ # 6 ]
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Im glad you’ve re-configured your set up so fast cant wait to see it in action!

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Posted: 02 August 2008 10:18 AM   [ Ignore ]   [ # 7 ]
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Henrik - 01 August 2008 02:03 PM

so i changed the halogens...into 26 white led´s they are enough that i can see the windows screen on the panel
in the picture only the outline of the led-range is powered on!

greetings henrik

How is the screen brightness compared to a normal LCD monitor?  Is the brightness uniform?
When I tested my LCD panel with white LED’s, I got very uneven brightness and I could see the LED’s through the screen.

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Posted: 02 August 2008 11:55 AM   [ Ignore ]   [ # 8 ]
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Yes you are right that isn´t so good but i think if i put a diffusor between the lcd and the the led´s i could be better right??

So well Today I have tested the camera settings...but i had problems with the lcd who make a bit problem including the Ir-lights.
I think they were to less and the angle in which the led´s shine is to small.
so i decided quickly to test another solution which come up during a brainstorming^^:-D

On the bottom of the picture you can see a light shield. In it there is the Camera...I don´t used any Ir-lights.

Then in the middle there´s a acryl boardand under it a kind uf diffusor:I got it from the TFT screen where it was installed between the panel and the backlight!

over that all there is the lcd and a kind of backlight.

So the trick by the thing is that the acry board is like a mirror so you could see the lcd reflecting on the acryl !!
the acryl is naturally also the “touch-screen”smile
the result of that all--> don´t try to clone this stupid idea!! no it was funny but you don´t have the agreements between your finger on the acryl and the reflection from the LCD!
So finally i took a lesson for myself

I also tried to put the lcd direct under and over the acry board but for this thing, witch i later took out to build the next days i will need many Ir-lights

Can anybody tell how he arrayed the Ir-leds? i often can see in the forum those Ir-spotlights...is it also possible to array them in a cicle as i do in the pictures so far?

thanks for answers! and have a nice weekend

Henrik

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Posted: 06 August 2008 01:45 PM   [ Ignore ]   [ # 9 ]
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dear all,
because of the inaccuracy of the rear Di method I changed to FTIR !
so I used 70 Ir-leds as you can see in the picture..

The thicknesses are from down to high:
-diffusor
-lcd
-acryl
-silicon(in plan)

Tomorrow I will build the case of the Multi touch gadget

Henrik

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Posted: 28 April 2009 04:44 AM   [ Ignore ]   [ # 10 ]
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hi henrik,

i am from germany too, and want to make a multitouch table, out of some tft.

are you finished with your project yet?

have you got a tutorial how to build one of those?

i hope you can help me, cause i am new in this kind of thing, and we can speak german if necesery.

hope to hear from you soon, because i like to build this table, soon smile.

have a nice day

kamue

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