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Build Your Own SLA/SLS • Kindle screens
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Kindle screens

Posted: Wed Apr 06, 2016 10:49 pm
by Redrichie
I know I saw it mentioned but can not find the comment or answers. But is there any way the kindle paper white screen could be moded for sla projection purposes? It only uses electricity to make the "ink" move to places to block out the back light. It even holds that "image" after the power is turned off and the screen removed.
There are a few articles about using the screen via a WiFi connection as a display only device. Since the back light lcd is removable does anyone with more knowledge than me know if replacing with uv or any other light would work. Since we are basically after relatively slow, refreshed, silhouettes.
I guess the limiting factor is the resolution. But I keep wondering of another way to basically make a moving mask to block targeted light.

Re: Kindle screens

Posted: Thu Apr 07, 2016 7:53 am
by James
Yeah, I too have heard of people turning their Kindles into monitors, but I think it was for older model Kindles. There may be people out there somewhere doing it with newer models though. I think the industry term for these types of displays is E ink displays.

As for using a UV back light I think you would run into the same problems you get when one attempts that with a LCD panel i.e. the plastics used to make such are compounded with UV inhibitors. It would work though I think with something like 410 nm light and a visible light polymerizing resin. One could also use it in a fashion similar to an opaque projector without having to take it apart and add a back light. In this case the light would be bounced right off the front of the screen into a projection lens.

If somebody could get a kindle to work one would be able to do SLA far cheaper than LCD methods I think.

Re: Kindle screens

Posted: Thu Apr 07, 2016 10:40 am
by Redrichie
I have also been thinking of the opaque projector route. I have a good one. I use it for mural art. It has an easily replaceable bulb and a double lens that focuses from 2 inches tall to 15 feet. However as known, that distance is very light projections. Any recommendations as to a specific bulb if I were to attempt to mod my opaque? If it were to expose resin with the use of an unmodded lcd sitting atop it then an easy shutter mechanism could be ran from an arduino or ramps without an issue.
I was reading about the teacher who ran a regular over head as a slide show through a mag lens and had sucess. Obviously not as high end as some the awesome stuff ive seen here is.

Re: Kindle screens

Posted: Thu Apr 07, 2016 4:44 pm
by James
Yeah, I would try LEDs as close to the edge of the lens as possible. The main problem I think that would come up is light bouncing off the entire surface of the screen and not the E ink below the surface. A benefit of LEDs is you wouldn't need a shutter. A shutter is used when one is using something like a DLP projector that is leaking light past the DMD chip with a high intensity discharge light that cannot be turned off and on quickly.

Re: Kindle screens

Posted: Thu Apr 07, 2016 5:35 pm
by Redrichie
Well if using an opaque do I even need to worry about e ink? If the visible image in the screen were only black and white from the slicer playing the image then the whites would be projected as pure light anyhow. At least to my unexperimented thoughts.
My opaque is a high end art device yet it is still archaic as can be. A switch, a bulb, a couple mirrors, and a lens.
I can replace the bulb with any bulb I wish.
Just thought experiment.

Re: Kindle screens

Posted: Thu Apr 07, 2016 8:41 pm
by James
When the light arrives at the outer surface of the screen, you'd want it to travel through the plastic or glass face plate and then reflect off the white areas and then start its way back out through the face plate and on up to the lens. For the black areas you'd want a very large percentage of the light to be absorbed and not reflected back out to the lens.

If you could get your Kindle to display a large black area you could put it in your projector and see how much light was being transmitted through the lens from the black area. If it turned out to be very low transmission you could probably get it to work. If it turned out that the black areas didn't look very black at all then I would bet that a large percentage of light was reflecting off the front face plate of the screen. In that case one possible solution would be to make the front surface anti-reflective, if it's not already. Come to think of it, it probably already has an anti-glare treatment of some kind on the face plate surface.