Persistent Displays With UV Light

May 24, 2021 by Jenny List 52 Comments

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!

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Helmet Decal Charger Keeps Them Ready To Glow

August 15, 2020 by Kristina Panos 9 Comments

When firefighters are battling a blaze, it’s difficult for them to find each other in the smoky darkness. To help stand out they wear glow-in-the-dark decals on their helmets, but since they spend so much of their down time stowed away in a dark locker, they don’t always have a chance to charge up.

[Bin Sun]’s firefighter friend inspired them to build a portable charging system that can stuff those helmet decals full of photons in a matter of minutes. Although phosphorescent materials will charge in any light, they charge the fastest with ultraviolet light. This uses a pair of UV LED strips controlled by an off-the-shelf programmable timer, and powered with an 18-volt drill battery stepped down to 12 V. The timer makes it easy for [Bin Sun]’s friend to schedule charge times around their shifts, so the battery lasts as long as possible while keeping the decals ready to glow.

We love that [Bin Sun] seems to have thought of everything. The light strips are nestled into 3D-printed holders that also house small magnets. This makes it easy to position the lights on either side of the locker so both the front and back decals soak up the light.

Phosphorescent materials are great as a reusable display medium, especially when they’re designed to look like Nixie tubes.

Persistence Of Phosphorescence Clock Displays YouTube Stats Too

April 5, 2018 by Dan Maloney 21 Comments

Looking for an eye-catching and unique way to display the time and date? Want the flexibility to add other critical information, like the number of YouTube subs you’ve got? Care to be able to read it from half a block away, at least at night? Then this scrolling glow-in-the-dark dot-matrix display could be right up your alley.

Building on his previous Morse code transcriber using a similar display, [Jan Derogee] took the concept and went big. The idea is to cover a PVC pipe with phosphorescent tape and rotate it past a row of 100 UV LEDs. The LEDs are turned on as the glow-in-the-dark surface passes over them, charging up a row of spots. The display is built up to two rows of 16 characters by the time it rotates into view, and the effect seems to last for quite a while. An ESP8266 takes care of driving the display and fetching NTP time and YouTube stats.

We’ve seen “persistence of phosphorescence” clocks before, but not as good looking and legible as this one. We like the approach, and we can’t help but think of other uses for glow-in-the-dark displays.

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Spell Out The Time With Frickin’ Laser Beams

August 29, 2017 by Dan Maloney 17 Comments

Clocks are a never-ending source of fascination to hackers. We get all kinds around here, from Steampunk Nixie clocks to retro cool flip clocks to clocks that don’t even look like clocks. But this is something new — a glow-in-the-dark laser tracing clock.

What [tuckershannon]’s clock lacks in practicality it makes up for in the gee-whiz department. The idea is simple: trace the characters out on a phosphorescent screen using a laser. To accomplish this, [tuckershannon] adapted the design of this whiteboard marker robot clock, replacing the drawing surface with glow-in-the-dark stickers. A 405 nm laser diode module is traced over the surface by the two-servo pantograph plotter, charging up the phosphors. He offers no clue as to how long the ghostly image lingers, but from the look of it, we’d bet that it lasts for a good fraction of a minute, especially in a dark room. Then again, you’d want the image totally faded before the next write cycle comes up, to prevent overwriting the previous time.

All in all, it’s a nice design and a clever new clock display modality. And who knows — maybe this whole glowing phosphor display thing could really catch on.

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Living Night Light With Glowing Algae

April 18, 2013 by Caleb Kraft 79 Comments

I may sound like I’m being over enthusiastic in this video. I’m not. Everyone who has seen this thinks it is simply amazing.

My father, an ex navy man, has told me stories of glowing water since I was little. Being a person who was obsessed with all things that light up, this always stuck with me. I saw a headline one day that someone was making an algae-light. Sadly when I clicked on it, the algae was just there to create oxygen. It was a cool idea, but not what I was hoping for.

That slight disappointment drove me to create a night light using glowing algae. The process could be extremely simple.

1. Buy Algae.

2. set up light for algae (it needs a 12 hour light cycle and putting it in a window sill would kill it due to heat). It needs bulbs labelled 6500k or higher.

3. shake algae at night (it only lights up when agitated, and when it is on its “night” cycle).

I really wanted to add more to this project though, so I decided to put the algae in a klein bottle and build a custom base for it that would allow me to move a BB around inside the bottle using magnets. This would in turn, hopefully, agitate the algae and make it light up.

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