Flush Touch Screen Working Prototype, Version 8

Flush Touch Screen working prototype

So obvious question is; whats different from version 7. The answer is not much in that it uses the design articulated in verion 7. But this is not a test, it is a real working prototype, with all the machining done to specifications. It has a finished rectangular LED Guide, inset into a plywood version of the MDF table material that will be used in the real INVIVIA conference table version. And, I might add, done on a DIY CNC milling machine by a guy with a walker…(‘cuz the idiot broke his hip skiing!)

Flush Touch Screen LED Guideback of Flush Touch Screen LED Guide inset into \ Done by a guy with a walker

There is one important difference with version 7 test. Here I have only had to use one line of LEDs running along the top of the LED Guide. That this would be enough was a pleasant surprise, and it bodes well for using it in an environment where there is more ambient IR light that would force me to use LEDs on all sides to compete.

Here’s video of demo shown above and video from camera’s view

[The blob tracker is still jittery and sometimes looses the blob position, even though the video image is solid. I worked for about an hour and found the place in the python code where this is happening, but couldn’t find a way to keep python from forgetting what it should do. This will take some work to fix, but is very fixable.]

[The melamine screen edge in this prototype version was cut into squares and taped to the plywood guide holder as a way of conserving the one sheet of melamine I plan to use for the real table. In the real table there will be a perfect hole that the screen sits flush into.]

Next Steps:

Lenseless Projector, no mirrors approach:

The big question, as I see it, is what kind of projector to use which determines how the table will look. I think there are two options. The simplest and initially most expensive one, and the one I believe will produce the best looking table uses the NECWT610e lenseless projector that was demo’d to us at INVIVIA.

This option is different from all the alternatives to follow in that there is no additional large mirror to mount under the table. The folding of the optical path is all done in the one projector. The big downside, beside the cost of the projector, is that the projector needs to be oriented vertically which will decrease the bulb life (but maybe not by much). This is an unknown we will need to deal with if we choose this options. (and sorry for the crude representation of the projector, but I think the massing and position is correct)

Conventional Projector, one or more mirrors approach:

The other approach uses a conventional projector, 1/3 the cost, but since the throw distance is so much longer must use two mirrors mounted under the table. This version, really just a klugy repurposing of an earlier design, folds the optics so that we get the shortest table, but what that does is put the mirrors down near the floor… maybe not the best design for the conference room table. Biggest downside to this design is that it would be very difficult to sit on either side of this table.

Here’s another two mirror conventional projector mirror arrangement. It is much less deep but not really as simple as it can be. We would choose this version if people had to sit on all sides of the table, as it gives a reasonable amount of leg room all around.

This final version turns the projector upside down, mounts it to the underside of the table at the very end, where these is just enough room to project an image large enough to fill the one, medium sized mirror, right below the screen. The mirror is held in place under the table by two clear polycarb supports that connect cross members with mirror position adjusting screws. Only downside I can see is that the projector is at the end of the table, making that side impossible to sit at. Otherwise this is the second simplest to build, with the NECWT projector version being the simplest.

here it is seen from slightly below. The mirror rests against the 3 angle adjusting screws.

Currently, I am working out the best way to cut a perfect (+/-.003″) rectangular hole into the top melamine sheet.

Further Next Steps Thoughts:


Having become more informed about MS Surface, INVIVIA would be crazy not to differentiate what we are doing as much as possible from the current Surface direction. To this end I have found another projector type, an ultra short throw conventionally lensed 2000 lumen DLP projector that allows us to fill nearly the whole conference table surface with bright projected image using one mirror. The projector is the Toshiba TDP-EW25U Conference Room Projector.

Here we see the table from the side showing the light fan (imagine the room filled with smoke) which shows how the projected image approaches and bounces off the mirror. This arrangement has a projector throw distance of just 26 inches, projecting an image 26 by 44 inches (50 inch diagonal). The projector has a native resolution of 1280 by 800 pixels.

The projector and mirror need to be protected from the sides and this is done with long pieces of frosted plexi attached to legs.

This size and shape would allow 4-6 people to work comfortably around the table, each with enough real estate to not feel squeezed. Given the 2000 lumens and the fact that the projector uses DLP the image should be bright, sharp and nice contrast. We need to see whether 1280 by 800 is enough resolution for that size.

Dual Use Version:


Following up on a suggestion by Daniel Spann that it might be really nice to use the touch table in a (near) vertical orientation, I reworked the optical path, added a mirror and projector cowl and added a hinge so that the table can now be used in either the horizontal or (near) vertical orientations.

Lifting the back of the table swings it to the near vertical orientation.

Of course there are many specific details to be worked out, but I think this concept sketch gives an idea of one way to make a very flexible prototype for exploring more uses of the touch table approach.

The projection surface shown here is ~ 22 by 35in (41in diagonal), set in a 28 by 41in table top. This is the smallest image the projector is made to deliver without modification. I think it may be possible to demount the lens and add a short lens extender tube to make projecting a smaller image possible.


2 Responses to Flush Touch Screen Working Prototype, Version 8

  1. Kityknine says:

    Amazing, very interesting subject. I will write about it too!!

  2. Generally I do not post on blogs, but I would like to say that this post really forced me to do so, Excellent post!

    I’m Out! 🙂

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