Persistent Displays With UV Light

This year’s Hackaday Prize has “Rethink Displays” as one of its first theme, and [Tucker Shannon] has given us his best shot on that subject with a set of impressive displays that “write” on glow-in-the-dark material using ultra-violet light. These materials glow for a while after UV illumination, so moving a light source like a UV LED over the surface draws glowing text or simple graphics which can be readily consumed.

One of the examples this a clock we were first smitten with back in 2018. It is a rather attractive 3D-printed affair with those servos mounted below the screen that moves a UV LED through a pair of linkages. Other offerings that play on the same UV stylus medium include a laser on an az-el mount controlled by a Raspberry Pi Zero. It’s a neat idea very effectively done, and we can see it has a lot of potential.

But the most impressively advanced so far is the model shown in the image at the top of the article and the demo video at the bottom. A loop of phosphorescent material is the display surface itself. This one moves that loop with two rollers to make up the X axis, and moves the UV source up and down for the Y axis. As with all of these designs, whatever is written will soon fade, leaving the surface ready for the next bit of information.

Interested in this project and think you could do a display of your own? The Hackaday Prize 2021 is live, and we’d love to see you enter it!

49 thoughts on “Persistent Displays With UV Light

    1. I guess they have to write laudations for each and every submission. Be glad they don’t have to write internal reports on top of that, on how relevant each project is for individual Siemens business branches.
      Or maybe they do ;)

  1. I wonder if you could do something like this with a UV blast projected through a transparent no-backlight OLED? OLED displays the time, UV light kicks on to expose through the transparent parts…

    1. OLED screens don’t block light, they make it, like plasma screens. That could work, though, with a transparent LCD!

      Alternately, make an OLED that displays UV instead of visible light, and is bright enough to “charge” the film.

      Either way, you might have trouble with the glass in the screen blocking the UV. Maybe there are plastic LCD’s? Or use near-UV light that can go through the glass?

      1. Kinda pointless though isn’t it? Why not just make it white light and backlight the LCD :D

        I dunno. I like this as it’s a mechanism and entertaining to watch, and LCD with UV backlight – seems a bit non-descript.

      2. It would work.. But it wouldn’t last long. This is the same principle that a lot of resin based 3d printers use. The screens are damaged pretty swiftly by the UV and have a lifetime of around 1000 hours or so. You could probably get away with using less intense UV and more robust LCDs than a printer in order to extend the lifespan but you’d still have a device that would need a new screen every few months.

  2. Love it, would pay real money for one, Also, if you want a more “permanent” display you could replace the UV sensitive material with regular plastic “tape”, the LED with a dry erase marker and put an eraser on it to erase the writing when you want to. (You would need a way to cap the marker too.)

  3. This is very similar to something I’ve wanted to build for a long time–a scrolling marquee text display drawn in place on a flexible whiteboard backing (a la Panaboard) by a dry erase marker, with the eraser located just prior to the write (and right) side, leaving a substantial backspace buffer behind the backside and quick backspaces for typos entered via Bluetooth keyboard. Really neat implementation! I’ll be interested to see how the “belt” seam was joined.

  4. I usually just silently shake my head when I read the editing mishaps on HaD, but as many others have pointed out, this article’s typo is absolutely inexcusable. As professional writers, you are expected to produce professional-level writings.
    I’m not trying to tear anyone down or act superior. I am simply pleading with the writer’s of this site to take this aspect of their job more seriously.

        1. Believe me, the irony was not lost on me. However, I wasn’t throwing stones. As I said, I’m not trying to be aggressive. I’m just trying to impress upon the HaD staff that proper proofreading is important to their readers and is something that *should* be part of their process when releasing an article.

          1. “proper proofreading is important to their readers” There is no evidence for this statement, but there is plenty of evidence that hackaday readers are equipped with functional error-correcting software, and your comment is one of the data points in my analysis.

      1. Spelling Nazi, maybe.
        Personally, I have no issues with grammar Nazis even when they call me out – why wouldn’t you strive to be better?
        We could all just give up and follow no rules.

    1. I usually just silently shake my head when I read the comment mishaps on HaD, but as many others have pointed out, this comment’s typo is absolutely inexcusable. As professional trolls, you are expected to produce professional-level gamma nazi-ing.

      I’m not trying to tear anyone down or act superior. I am simply pleading with the readers of this sight to take this aspect of their job more seriously.

    2. I cannot care less about mistyping anywhere…. they could write whatever they wanted, if I could understand it’s fine. This isn’t a site about correct English anyway.

      So unless something is so badly written that the meaning is confusing, it’s fine. They are paid to write, ok, but I am here for the hacks, not for the language.

      And congratulations on unlocking the “Skitt’s Law Achievement.” :)

      1. This is a little like claiming you don’t mind watching Netflix in super compressed form (due to a fault with your internet connection) because you’re able to still see what’s happening and your ears make up for the errors when you can’t quite see it properly. Sure your ISP got it to you, and Netflix has evolved far enough to be able to send *something* intelligible through the poor connection, but that doesn’t mean you should just accept it as the way things should be. That said, in this case, I’m not sure I’d have made quite such a “thing” of it as some commentators have.

        1. That would be a great analogy if we had to pay for the content here. The issue isn’t the quality of the delivery or content, it’s the expected value. I expect to get a great value consuming content from Hackaday, as around 75% of the content is specific to my interests, roughly 50-60% of that are new ideas or perspectives, or novel applications (to me), and all of it’s free. (In the end, you made at least as much of ‘a “thing” of it as some commentators(sic) have.’

    3. You’re not paying them for perfection. Hell, you’re not paying them at all.

      Not sure how this (or any) typo is “inexcusable”, unless it somehow killed your beloved family pet.

  5. A matrix of LEDs would eliminate a motor for this build. Actually, if you expanded the LED matrix into 2D, then you eliminate the other motor too, but then you just have an LED clock.

  6. Since this isn’t about simple… I’m imagining a semi-deconstructed laser printer that runs the same continuous loop of phosphorescent material. The laser (maybe with a new module, unless the existing one can excite the phosphorescent surface) prints the image on the material as it would normally print onto the drum. All the subsequent steps to place the toner on the paper and fuse it there would be removed.
    The power requirements might make it a bit wasteful, though removing the fusing portion would help.

    Might make for an interesting interactive display. Send a message to the printer and it spits out a very ephemeral display.

  7. I found that the glow-in-the-dark material is very persistent, and in a dark room is visible for hours. Which means a display rolls back to the start that still has some remnants of the previously written stuff visible.

    In the display I built a couple of years back ( first version: https://youtu.be/4Vhdp7ZXU_8 – you see the ghostly shadow when it rolls around to the xkcd) I ended up making a second version with the fluorescent canvas more than double the length to have enough room for somewhat frequent time updates and not too many ghostly shadows.

    1. From what I’ve read it should be possible to “quench” the written surface on the backside of the conveyor belt using IR leds to effectively erase what was written and leave a blank surface

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