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Multitouch display, build your own: testing tracing paper and sketch paper
Finally I was able to use some spare time to buy and try the tracing paper, to be honest, I din't post the tests done with it because it didn't worked out as expected! Sorry for being away so much time!
Of course there's another reason why I'm writing this post, I could not be so motivated by a tracing paper flop!
Last sunday, after I wrote the last post in which I said that I didn't have the tracing paper to test, a friend of us came home. Before she came, I was speaking with her on the phone and, knowing that she's an artist and she's always experimenting a lot of materials, I was asking her for a small piece of tracing paper. She brought an entire roll of sketch paper saying that she didn't had the tracing paper but this was so similar to it and I could give a try. I really have to say: THANKS CAMILLA!
If you look at the video you'll understand everything. Infact the tracing paper is not working as expected. I think that this is due to the fact that the tracing paper is too smooth and bright and it just sticks on the silicone rubber like the rear projection was doing alone. This partially sets off FTIR on the whole contact surface and finger touches are not so bright and recognizable.
The sketch paper is instead less smooth, more porous and even if it sticks a little bit on the silicone rubber, it detaches from it very quickly. As result it gives very good and usable blobs with just some persistance but anyway really a good behaviour compared to what I got from the tracing paper.
Luckily this is happening also with the projection film on it and not only! With the whole setup that is: silicone rubber, the sketch paper on it and the projection film on top I have constant and bright blobs even when I quickly move the fingers around. With just the bare silicon rubber I had great blobs that become very faded and less recognizable when moving the fingers.
I'm pretty happy of this results, hopefully this is the solution to the silicone rubber failure. Now I feel really more confortable with my multitouch table and I'm ready to go over. Even if the sketch paper roll width is smaller than my plexiglass I already covered the whole display surface with it, using two stripes. I hope that the background remove feature of the multitouch software may overcome the possible issue of the paper junction line. On top of all, I really hope to find some time during this week because I don't have enough time today to test the whole screen setup! But, don't worry I have anyway other news to post so I will not leave this blog alone for another whole week!
Stay tuned!
Of course there's another reason why I'm writing this post, I could not be so motivated by a tracing paper flop!
Last sunday, after I wrote the last post in which I said that I didn't have the tracing paper to test, a friend of us came home. Before she came, I was speaking with her on the phone and, knowing that she's an artist and she's always experimenting a lot of materials, I was asking her for a small piece of tracing paper. She brought an entire roll of sketch paper saying that she didn't had the tracing paper but this was so similar to it and I could give a try. I really have to say: THANKS CAMILLA!
If you look at the video you'll understand everything. Infact the tracing paper is not working as expected. I think that this is due to the fact that the tracing paper is too smooth and bright and it just sticks on the silicone rubber like the rear projection was doing alone. This partially sets off FTIR on the whole contact surface and finger touches are not so bright and recognizable.
The sketch paper is instead less smooth, more porous and even if it sticks a little bit on the silicone rubber, it detaches from it very quickly. As result it gives very good and usable blobs with just some persistance but anyway really a good behaviour compared to what I got from the tracing paper.
Luckily this is happening also with the projection film on it and not only! With the whole setup that is: silicone rubber, the sketch paper on it and the projection film on top I have constant and bright blobs even when I quickly move the fingers around. With just the bare silicon rubber I had great blobs that become very faded and less recognizable when moving the fingers.
I'm pretty happy of this results, hopefully this is the solution to the silicone rubber failure. Now I feel really more confortable with my multitouch table and I'm ready to go over. Even if the sketch paper roll width is smaller than my plexiglass I already covered the whole display surface with it, using two stripes. I hope that the background remove feature of the multitouch software may overcome the possible issue of the paper junction line. On top of all, I really hope to find some time during this week because I don't have enough time today to test the whole screen setup! But, don't worry I have anyway other news to post so I will not leave this blog alone for another whole week!
Stay tuned!
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| « Multitouch display, build your own: paper on the silicone rubber layer |
| Multitouch display, build your own: silicone rubber preparation video in progress » |
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Hello Blaxwan,
My name is Afonso and I live in Florian�polis, Santa Catarina, Brazil. I'm new on this subject, and I'm working in a project here with the FTIR technology. I read a lot about what you wrote, your posts and stuff and I enjoied all this information. I guess I've faced the same problem. I need a paper that doesn't reflect the light of the projector and doesn't affect the touch and the effects of the touch on the surface. A lot of other kinds of materials doesn't work, because they reflect part of the light of the projector or because the touch isn't well perceptibel over it. You said that the sketch paper is efficient. In my case, do you think that this sketch paper will solve my problems and be eficient for me?
I would be very happy with your help.
You have my email, I wait an answer.
Thanks for everything.
Hi Afonso, thanks a lot for your comment, I'm really happy to see that you enjoyed reading my pages!
Regarding your question, I can only say that the sketch paper improved a lot my setup with the silicone rubber which was faulty mainly for (I suppose) the kind of silicone rubber I used that is still too sticky. Actually the paper is reflecting a little bit the projector light but it is absolutely not disturbing the camera, my last problem is still with the touch trays.
Unfortunately I can't tell you much more because basically you told me what you're expecting from this paper (no projector light reflection, no effect on the touch) but not what's your problem you're looking to solve with it! Are you facing the same silicone rubber stickyness?
Let us know!
Hello Blaxwan,
My name is denghuaqin and I from China. I'm study the multitouch recently, and very happy to read your pages. I want't to bulding a multi-touch by myself,but I have some problem to consult you.
1.can the plexiglas replace by glass?
2.is the led-hole drill in the plexiglas?.
3. what's the fuction of the silicone rubber layer?
I'm very sorry to my poor english!
I would be very happy with your help.
You have my email, I wait an answer.
Thanks for everything.
Hi Denghuaqin,
very shortly:
- the glass is less efficient than plexiglas and is harder to work with
- no holes for LED, there's no particular advantage in doing it
- silicone rubber is used to couple the plexiglas and the rear projection screen, see the multitouch guide pages
Hello Blaxwan,
Thank you for your help.However,I still have several questions,I can't buy the silicone rubber here,can I use the patch-style projection screen instead of the silicone rubber and projection screen? Does the FTIR relate with the silicone robbe layer?
I used the glass instead of Acrylic,and not adhibit the silicone rubbe on it,and then I find the blobs is not clear,could you please tell me why?
I am looking forward to your prompt reply
Thank you for your help.However,I still have several questions,I can't buy the silicone rubber here,can I use the patch-style projection screen instead of the silicone rubber and projection screen? Does the FTIR relate with the silicone robbe layer?
I used the glass instead of Acrylic,and not adhibit the silicone rubbe on it,and then I find the blobs is not clear,could you please tell me why?
Hi, what is the patch-style projection screen?
With FTIR you need the silicone rubber layer to improve the coupling beetween the acrylic and the rear projection screen. You don't need any silicone rubber with DI. Use plexiglas, as I said, the glass is less efficient for this application.
a patch-style projection screen has three layer,the middle layer is glutinous ,it can direct adhibit on the plexiglas surface.
Actually the rear projection surface has a bad coupling with the plexiglas. This means that I need to press quite hard on the display in order to have workable "blobs" or decent reflected spotlight under the finger touch. why a bad coupling with the plexiglas will lead to a unwordable "blobs" while the silicone rubber layer can't disturb the Frustrated Total Internal Reflection?
why glass is less efficient for this application?
can you explain to me more clearly?
Denghuaqin:
- glass is less transparent to infrared than acrylic
- bad coupling is the cause for lack of FTIR
Anyway this is the place for comments to the blog post, if you need to ask other things please use the email.
I'm glad that the paper works!
;-D
Thanks a lot Camilla! Your sketch paper gave outstanding results!
Snx for you job!
It has very much helped me!
Thanks Guus and Dencreede!