It’s Glow Time!
Glowtape is a unique DIY watch by Henner Zeller that is powered by an RP2040 microcontroller and uses glow-in-the-dark tape as a display.
Some people are into cutting-edge technology and want the latest smartwatch on their wrist the moment it hits the shelves at their local store. Others are into a more classic and minimal aesthetic, and go with something like a Casio F-91W, or perhaps a calculator watch or a Timex Ironman. And then there is Henner Zeller, who recently built the coolest watch that you wouldn’t want to be caught dead wearing in public — at least outside of the Hackaday Supercon anyway, where this very unique timepiece was spotted.
Zeller’s watch is called the Glowtape, and as the name implies, it displays the time via a glow-in-the-dark display. So far this sounds pretty normal, and you might be expecting something like an Indiglo effect. But that is not at all what this watch is. The display is actually a long piece of 2-inch wide glow-in-the-dark tape. This tape passes through a housing that activates areas of it like pixels, then when it emerges, it displays the time (or for that matter, anything else you program it to display).
Inside the watch is an array of 64 ultraviolet LEDs, which shine on the tape as it is manually pulled past them. This activates the glow-in-the-dark effect, which displays the time underneath a clear plastic panel that diffuses the light and adds to its brightness. The LEDs are controlled by a Raspberry Pi RP2040 microcontroller. A pretty beefy LiPo battery is needed to power all of the LEDs, which adds to the size of the watch, but when you cross a certain threshold (which Glowtape crossed long ago), who is even counting anymore?
The glowing effect does not last very long, so it is necessary to regularly pull more tape past the LEDs if you want to know what time it is. Having what appears to be nearly a foot of tape hanging out of the watch at all times is not exactly practical either, so this watch is really more of something to show off than it is a practical timepiece.
Putting the wristwatch concept aside, this type of display could be very interesting for a desktop clock or banner. If the tape were made into a loop, and it was automatically moved past the LEDs, that would make for quite a unique gadget. Zeller has provided schematics and firmware if you would like to tinker with this concept on your own. And if you do, make sure you post it to Hackster so we can take a look!