We’re big fans of unusual timepieces here at Hackaday, so it didn’t take long before somebody called our attention to the gloriously luminescent watch that [Henner Zeller] was wearing at this year’s Supercon.
He calls it the Glowtape, and it uses a dense array of UV LEDs and a long strip of glow-in-the-dark material to display the time and date, as well as images and long strings of text written out horizontally to create an impromptu banner. It looked phenomenal in person, with the energized areas on the tape glowing brightly during the evening festivities in the alleyway.
The text and images would fade fairly quickly, but in practice, that’s hardly a problem when you’re just trying to check the current time. If there was something to limit the practicality on this one, it would have to be the meter-long piece of material that you’ve got to keep pushing and pulling through the mechanism — but it’s a price we’re willing to pay.
Want one of your own? [Henner] has shared all of the source code for the wearable, from the OpenSCAD scripts to generate the 3D printed enclosure to the C firmware for the RP2040 that runs the show. The LED array itself is actually a spin-off of his Glowxels project, which is worth checking out if you’d like to recreate this concept on a much larger scale.
This isn’t the first time we’ve seen this technique used for this kind of thing, but it may be the most compact version of the concept we’ve seen so far.
I love this haha
Can the tape be made into a loop and automatically moved through?
That (a loop) was exactly what I was expecting.
haha put it on reels within the device. make it practical
i want this to work like those cheap ass roll up window shades, “hol on buddy let me consult my scroll, it says to go that-a-way”
One way to make it loop is to make it into a disk that spins.
The size of the disk will be dictated by the persistence of the Imprint and the speed it spins.
It would be cool if it could display each second.
What’s the optimum wavelength to excite this glowstuff? A 405 nm LED seems to work much better than a 365 nm. Is there something better? I can’t see in the repo what was used here.
its all about energy in. with leds i typically find that the higher the frequency the stronger the glowification. blue leds do it, purple do it better. you can also brute force it with a microwave (more power less frequency). id love to stick one of these strips in front of an xray tube.
No, it isn’t “all about energy in”. The incoming photons must match the energy of the accepting atomic or molecular construct in order to be absorbed and transfer their energy. Absorbers are different, and some are quite specific.
Phosphorescent materials absorb photons at short wavelengths (high energy), and release that stored energy at a lower energy (longer wavelength) with some useful time constant (minutes). The difference in photon energies (the ‘Stokes shift’) generally gets released as heat.
The commonly-found green phosphorescent material is mostly blind to 365 nm photons, and does nothing with 550 nm (green) light, but works OK with 405 nm light. My question is: what’s the optimum absorbing wavelength, or peak of the excitation spectrum?
(If you’re coaxing green light out of phosphors with microwaves, that’s a different mechanism that’s releasing energy stored in defect traps)
According to the docs, glowtape is an offshoot of the glowxel project, which seems to use 405nm LEDs
Have to comment just to say how much I like the looks of this display type / watch.
Too bad the category “display bracelets” went quiet again after the last hype with e-paper strips (Looksee’s Eyecatcher Bracelet and the like).
Now what about a bracelet in which either a flex PCB with the LEDs is moved around inside, or one where the plastic film on the outside can be rotated.
What time is it? Tine to get a new watch, this one! An interesting modification would be a glow tape panel covering the leds on a spring plate, push the plate, a switch makes the leds flash the tape, the tape flips 180 degrees and you see the glowing time, then you just push the panel back over the leds. Kind of a “mouse trap” watch.
Kind of like those watch cuffs that have a protective cover over the watch face that you have to lift up to tell the time, except the protective cover is the watch face.
Exactly.
“the evening festivities in the alleyway.”
Hahahaha I bet.