katodisädeputkea

A katodisädeputki, or cathode ray tube (CRT), is a vacuum tube that contains one or more electron guns and a fluorescent screen, used to display images. The electron beams emitted by the electron guns are directed by magnetic or electrostatic deflection coils onto the fluorescent screen. When the electrons strike the screen, they cause the phosphors to emit light, creating a visible image. CRTs were the dominant display technology for televisions and computer monitors for many decades, from the mid-20th century until the early 21st century.

The operation of a CRT relies on several key components. The electron gun, typically located at the narrow end of the tube, generates a focused beam of electrons. These electrons are accelerated towards the screen by a high voltage. Deflection coils, positioned around the neck of the tube, manipulate the path of the electron beam, allowing it to scan across the screen in a pattern, usually from left to right and top to bottom. The intensity of the electron beam is modulated to control the brightness of the illuminated pixels on the screen, forming the image. Color CRTs employ multiple electron guns and a shadow mask or aperture grille to direct the beams to the correct color phosphors (red, green, and blue) on the screen.

While CRTs offered excellent image quality and response times for their era, they were bulky, heavy, and consumed significant power. Their widespread use began to decline with the advent and increasing affordability of flat-panel display technologies such as LCD (liquid crystal display) and plasma displays. By the 2010s, CRTs had largely been replaced by these newer technologies in consumer electronics.