A short history of the split-flap display
Split-flap displays were invented by the Italian company Solari di Udine in the 1950s for train and airport timetables, and became a design icon through the 1970s-90s before LCD/LED screens largely replaced them. Flip-dot signs are a parallel technology using rotating dots instead of full-character flaps. Both are having a design revival — including in software like FlipLetters.
The split-flap display was invented by the Italian company Solari di Udine in the 1950s, originally for railway timetables and later adopted by airports worldwide. Each character sits on a small stack of hinged flaps — one letter or number per flap — that rotate over a drum to reveal the next character, driven by an electromechanical stepper mechanism.
Through the 1970s, 80s, and into the 90s, the distinctive clack of a split-flap board updating became a defining sound of air travel, synonymous with departures and arrivals boards worldwide. As LCD and LED screens got cheaper, most airports and stations replaced their mechanical boards — famously, few remain in daily service today, which is part of why the look and sound have become nostalgic rather than merely functional.
Flip-dot displays are a related but distinct technology: instead of full-character flaps, each pixel is a small disc that flips between two colored faces (usually black and yellow, or black and white) using a tiny electromagnet. That's what gives flip-dot signs — common on buses and older digital signage — their dot-matrix look and higher-pitched, fizzier click compared to a full-character split-flap board.
Both technologies have seen a real design revival in the last decade: DIY split-flap kits and desk clocks, motion-graphics tutorials recreating the effect in After Effects, Blender geometry-node renders, and now web tools like FlipLetters that let anyone program the choreography and sound without owning — or building — the physical hardware.