How do you read your text messages when you’re in a meeting? If you’re like most people, you either try to discretely look at your phone or you use a smartwatch. But, staring at your watch for a full minute makes you look like a fool who can’t tell time. Befinitiv’s POV display smartpen is a far better solution.
This project started with one goal in mind: display messages on a pen. Pens are unobtrusive and ubiquitous in business meetings, which makes them perfect for stealth message-reading. The real trick, of course, is how to fit a readable display onto a small pen. That’s why Befinitiv decided on a POV (Persistence of Vision) setup, which only requires a line of LEDs.
POV displays aren’t exactly common, but they’re not rare either. Most of them are absurdly low-resolution, and that didn’t meet Befinitiv’s standards, so they came up with an ingenious solution for a compact, yet high-resolution, POV display. That started with a string of tiny LEDs, but even those were too big for Befinitiv’s particular tastes.
There really aren’t any smaller individually-addressable RGB LEDs available, so Befinitiv turned to fiber optics. The LEDs are laid out in four rows in 3D-printed mounts, and then optical fiber leads from those to the outer face of the pen clip. That setup essentially quadruples the pixel density of the POV display.
With the LEDs setup, Befinitiv was able to use an IMU (Inertial Measurement Unit) and a Raspberry Pi to actually output the message to the LEDs. The IMU senses the movement of the pen as it’s flicked back and forth, and the Raspberry Pi processes that to refresh the LEDs and display the message. It’s not perfect, mostly due to issues with the LED refresh rate, but Befinitiv has built an extremely compact POV display with an almost unheard of pixel density.