Mechanical television may belong to the 1920s, but maker James Brown has used the concept to create a pocket-size widescreen display with an unusual resolution of 4,096 × 20 pixels. Called the Scanwheel, the electromechanical television combines century-old scanning principles with modern microcontrollers, LEDs, and 3D printing, tells IEEE Spectrum.
Early mechanical televisions used Nipkow disks containing spirals of holes. As a disk rotated past a light source, each hole traced a scan line. Rapid rotation and changing light intensity created an image through persistence of vision. Brown replaced the disk with a cylindrical Nipkow drum, originally intending to build a clock.
The drum proved important for miniaturization. Its stair-step arrangement of holes produces straight horizontal scan lines without requiring the large diameter of a disk. Brown settled on a 6-centimeter-wide drum and placed five LEDs inside it. He later realized that the five individual display zones could operate together as one widescreen display.
Rapid LED modulation gives the Scanwheel its 4K horizontal resolution. Brown has achieved more than 8,000 horizontal pixels in testing, although onboard memory currently limits normal operation to 4,096. Vertical resolution remains just 20 pixels, yet the wide horizontal resolution provides enough detail to display recognizable video.
A Raspberry Pi Pico based on the RP2040 microcontroller controls the system. The chip’s programmable input/output coprocessors handle the demanding task of synchronizing the spinning drum with the LEDs while retrieving pixel information from the frame buffer. A stepper motor rotates the drum, while video arrives through a network interface.
The Scanwheel’s casing and drum are 3D printed. Brown has also released project files, including a customizable OpenSCAD model, allowing makers to alter the drum, increase scan lines, and experiment with their own mechanical displays.
