E3 progress and testing

July 4th, 2008 by NearInteraction

We did a test with the IR LED’s in the bottom of the table to see how they reacted to fingers touching the screen. The results were all right in the middle, but not enough to cover the whole surface. A trial was made with LED’s in groups spread out over a grid in the bottom to give fuller coverage.

It seemed though that it would be better to have LED’s around the edge of the plexi on all sides.

John held a small soldering workshop for me and Miguel and we worked on putting LED’s on the two sides of the frame that didn’t have any yet.

When testing the different surface materials they all had different pro’s and con’s. Some reacted quicker to the body heat and with less pressure. Others gave a sharper image when projecting on them. We have to find the material that gives the most of both factors.

More tests have been made with different materials (Black= 3M Vikuiti, white, clear and grey= Rosco)

I contacted a company in Sweden (Teknilux.com) about another type of back projection material but have got no answer from them so far.

A test was made with the sharpness of the 3M projector and we measured that it keeps sharp at 70 cm’s from the screen. One also has to take in consideration the angle of the projector inside the table to compensate for the sharpness and how it spreads the image across the screen.

Also some testing was made with the brightness and contrast of the projector to see how it interacted with the different materials.

A problem occurred with the angle of the projector. It’s not possible to center it under the screen = it will stick out from the “frame” of the table that has been designed. This means either we must change the design for it to work or try other projectors. We’ll have access to other projectors to test and see if they do a better job. For instance they have a smaller body and mirror (that might be used to adjust the angle?).

A test was supposed to be made 080702 with silicone to cover the plexi but we had the wrong type. 080703 the right type was bought and the surface was covered with it. It had to settle over night since it takes around 14 hours to do so.

When the cover for the silicone had been taken off, it showed that the surface wasn’t very smooth.

It will be checked if this has impact on the focus of the projector or not. The surface was covered with a diffusor-material and now testing was supposed to begin with the different Rosco-materials etc after fitting the plexi back in the LED-frame.

The inside of the edges of the LED-frame was taped with silver-tape for reflection spreading as much light as possible towards the screen.

After putting the plexi back in the frame:

we chose to save the diffusor-material for later testing with another coating (probably clear latex) and put back the tracing paper instead.

Now testing with the different projection materials.

Note: The top material is not supposed to be glued to the surface on top of the diffusor. It has to be stuck with a frame or similar. How is it supposed to be fit without getting air-bubbles underneath? This needs to be figured out.