UV Sensitive Filament As A Persistent Display

Some of the hacks we feature are modifications of existing devices, others are ground-up builds of entirely new ones. And then there are the experiments, things that have to be worth trying because they just might work. In this final category we have [Matt]’s work with¬† UV sensitive plastic to form the basis of a simple persistent display, which has created something best described as a proof-of-concept that shows promise, and definitely proves that he had an idea very much worth trying.

The idea makes use of a plastic that changes colour from white to purple when exposed to UV light. He 3D printed a waffle-like structure to locate over a 3×3 grid of UV LEDs, which he could then illuminate under the control of an Arduino Mini Pro. A short illumination changes the colour of the plastic above it, creating a “pixel” that persists for several seconds. In this he has created a working proof of concept for a very simple 3×3 matrix display, albeit rather an unwieldy one. The advantage the idea offers is that a relatively long time of display can be achieved for a relatively short LED illumination, giving a potential for power saving.

The proof-of-concept itself isn’t particularly useful, but from this idea it’s possible a larger display could be practically made. An array of surface-mount LEDs could perhaps illuminate a larger array of plastic to a greater resolution, it’s definitely an idea that was worth trying, and which shows promise for further pursuit. If you’d like to see it in action he’s posted a video, which we’ve placed below the break.

 

32 thoughts on “UV Sensitive Filament As A Persistent Display

  1. Perhaps some low power UV-LEDs could “flood” the plastic “screen” with just enough power to maintain a “pixel” once changed.
    I’m thinking along the lines of the “Flood Guns” used in old CRT storage oscilloscopes.

    1. I’d also love to see if a very thing ribbon could be 3D printed. With a “regular” “printhead” with a UV laser diode, you might be able to print out a message that persists for a reasonable amount of time with a reasonable density of type.

  2. This reminds me of an installation I saw at a Science Museum years ago. (Maybe Toronto CA?) There was a dark room/corridor walled with phosphorescent panels. A strobe light would fire at regular intervals leaving persistent shadows on the walls.

  3. Isn’t eink the same as far as low power and long lasting persistent display? eink has higher resolution, better readability, and can be made in limited color. What am I missing as far as UV plastic display?

    1. You’re missing the “Because I can” aspect. Also the “Why the Hell not?” aspect. and the ability to potentially do this on 3d printed structures in customized shapes, not just a grid.

    2. eInk has some big downsides, especially when working at the screen driver levels.
      The multi-color eInk displays also have some downsides just in general usage, even if the built in screen driver is acceptable to you.

      eInk is controlled by magnetic field polarity, but each pixel must be driven with an equal/zero field on average.
      If you send 5 “positive” pole fields at it in a row, you must send it an equal number of “negative” pole fields after to balance it out, or it will physically damage the balls within the screen and destroy the pixel.
      Even the simplest way of doing this requires maintaining two screen buffers (current and new) to know when and most importantly when not to update a pixel.

      Multi-color screens also throw in not just the field polarity but the strength, and again these all must average out in the end or you will destroy pixels. This also makes it harder to just flip a pixel as needed, since changing between two colors that happen to both require a “positive” field of different strengths would still count as a change that must be made, but will accumulate far from neutral and can destroy the pixel element. (This is why those types of screens show bizarre artifacts when changing frames)

      eInk pixels also are based around those magnetic painted balls to be floating in a mostly viscous fluid.
      This fluid is quite sensitive to ambient temperatures, and doesn’t function in lower temps, combined with very low temps (below freezing) being able to destroy the entire display.

      There is nothing better than having multiple options to choose from to best fit your use and needs.

      1. I did something like that a few years ago… I had a jar of phosphorescent paint, and I found that I could draw glowing shapes on it with a blue laser pointer, and “erase” lines into the glowing area using a red laser pointer. Amused me for hours on end, LOL.

          1. Just tried it with a UV LED and red laser module

            The red LED on my white/red/UV torch wasn’t powerful enough to significantly effect the GITD marker I tested, but >100mW of red laser light was enough to dim it significantly faster than the normal decay rate.

    1. Howabout you get some of that thermal paper like receipt printers at stores use, shine it with a focussed laser to turn it black. That could allow a readable display for like a whole month.

      1. If the thermal paper was on a loop, it could be advanced to allow new designs to be printed. If the loop is long enough, after a few weeks when it cycles around the printed parts will have faded completely.

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