Katoderør

A katoderør, also known as a cathode ray tube (CRT), is a specialized vacuum tube in which a beam of electrons is projected onto a phosphorescent surface. This projection causes the surface to emit light, creating a display. The electron beam is generated by an electron gun at the rear of the tube and is controlled by electrostatic or magnetic fields. These fields deflect the beam, allowing it to scan across the screen in a specific pattern, typically from top to bottom and left to right.

The inner surface of the front of the katoderør is coated with phosphors, which glow when struck by the electron beam. Different phosphors emit different colors, and by using multiple beams or strategically placed phosphors, a full-color image can be produced. The intensity of the electron beam, controlled by a grid within the electron gun, determines the brightness of the illuminated spot on the screen.

Katoderør were widely used in older television sets, computer monitors, and oscilloscopes. Their ability to produce bright, high-resolution images made them the dominant display technology for many decades. However, due to their bulkiness, high power consumption, and susceptibility to image burn-in, they have largely been replaced by newer technologies such as liquid crystal displays (LCDs) and organic light-emitting diodes (OLEDs). Despite their decline in mainstream use, katoderør remain historically significant in the development of electronic display technology.