You’ve probably seen a spinning fan with LED lights that forms text or images mid-air — like magic! But what’s really going on?
This cool effect is based on a concept called Persistence of Vision (POV). By spinning an LED strip fast and changing the lights at the right moment, our brain gets tricked into seeing a complete image — even though it’s really just one line of lights!
Persistence of Vision is a visual phenomenon where an image stays in our brain for a tiny fraction of a second after it disappears. This is the same principle that makes movies work — you see 24 still images per second, but your brain blends them into smooth motion.
In numbers: Our eyes “remember” an image for about 1/10th of a second (100 milliseconds)
Now imagine an LED strip with just a single row of lights, spinning quickly in a circle.
The strip lights up different LEDs at different times as it spins.
Since it’s moving fast, each LED’s light appears in a slightly different position around the circle.
Because of persistence of vision, your eye blends all these positions into a full image or pattern.
It’s like the LED strip is “painting” the image into the air one line at a time — and your brain is filling in the rest!
Know the rotation speed (usually measured using a sensor like a Hall effect sensor or magnet).
Change the LEDs precisely as the strip spins, so the right pixels show up at the right angles.
Repeat this cycle fast enough to make the image appear stable.