Cathode-Ray Tube Day Date in the current year: December 20, 2024

A cathode-ray tube (CRT) is a vacuum tube that contains one or more electron guns. The electron guns emit electron beams that are manipulated to display images on a phosphorescent screen. CRTs can be used in various devices such as oscilloscopes, radars, television sets, computer monitors, etc.

Cathode rays were first observed in 1859 by German physicists Julius Plücker and Johann Wilhelm Hittorf, who used vacuum tubes in their experiments. In 1879, British chemist and physicist William Crookes named the rays observed by Plücker and Hittorf “cathode rays”. While investigating their properties, he discovered they could be deflected by magnetic fields.

The earliest version of the cathode-ray tube was created by German physicist Ferdinand Braun in 1897. It consisted of a modification of the Crookes tube (a cold cathode tuber invented by Crookes in the late 1860s) and a phosphor-coated screen. In 1908, Scottish electrical engineer Alan Campbell-Swinton proved that the Braun tube could be used to both transmit and receive images, providing the theoretical basis for electronic television.

The first all-electronic television receiver with a CRT was built and demonstrated in 1926 by Japanese engineer Kenjiro Takayanagi. Takayanagi’s invention played a key role in the development of television in Japan, but it wasn’t much recognized in the West. The first Western all-electronic television was invented by Philo Farnsworth, who demonstrated it in 1927.

Another pioneer of CRT technology was Russian-American inventor and engineer Vladimir Zworykin. He filed two patent applications for a television system in 1923 and 1925, and gave the cathode-ray tube its name in 1929. Zworykin’s employer, the Radio Corporation of America, filed an interference claim against Farnsworth, and litigation lasted for years. Eventually, the RCA lost, and Farsnworth was declared the inventor of electronic television. Nevertheless, Zworykin did receive his patent on December 20, 1938. The anniversary of this patent is now observed as Cathode-Ray Tube Day.

CRTs were widely used in television sets, computer monitors, and other devices throughout the 20th century. Since the late 1990s, they have been replaced by LCDs in computer monitors and televisions. Today, CRT-based television and computer monitors are largely obsolete, but some industries still use CRTs because they are hard to replace or have no alternatives. For example, CRTs are still used in some airplanes and military equipment.

The origins of Cathode-Ray Tube Day are unclear, but don’t let it stop you from celebrating this amazing invention. You can observe the holiday by learning more about the history of CRTs and sharing the facts you’ve learned with others, visiting a technology museum that has old television sets and computer monitors, playing retro computer games, and spreading the word about the holiday with the hashtags #CathodeRayTubeDay and #CRTDay.