Katodisädeputkissa

Katodisädeputkissa, commonly known as cathode ray tubes (CRTs), are vacuum tube devices that were a foundational technology in early electronic displays and televisions. Their operation relies on the emission of electrons from a heated cathode. These electrons are then accelerated and focused into a beam by a series of electrodes. The electron beam is directed towards a phosphor-coated screen at the front of the tube. When the energetic electrons strike the phosphor coating, they cause it to emit light, creating a visible image.

The deflection of the electron beam, which allows it to scan across the screen and draw a complete image, is typically achieved by either electrostatic or magnetic fields. Electrostatic deflection uses electric fields generated by deflection plates, while magnetic deflection uses electromagnets placed around the neck of the tube. The intensity of the electron beam is modulated by a control grid, which determines the brightness of each point on the screen. CRTs were dominant for many decades due to their ability to produce high-quality images with good contrast and color reproduction, though they were bulky and consumed significant power. Their widespread use declined with the advent of newer display technologies like LCD and OLED.