John Logie Baird demonstrated a color TV system, the first one that actually worked, in 1928. Baird used a Nipkow disk, with the disk divided into three sections, each with its own spiral system of holes, with each section covered by a red, green, or blue filter. As the disk spun, it scanned a red image, followed by a green image, then a blue image, generating all three components of a full color image with each turn of the disk.

A similar disk in the receiver decoded the three signals, and displayed them on a small screen. The screen consisted of a grid of cells containing either neon for red light, helium for blue light, or mercury for green light. The images were bright and vivid, but the screen was tiny and the frame rates low.

This article, written in 1939, described Baird's mechanical  systems, and a demonstration using a projection CRT that produced a picture about 3 ft square.

Washington Post, July 7, 1928

(Courtesy of John Pinckney)