CRO & DSO Lacture 2nd | Function and Working of CRT ( cathode ray Tube) and internal Structure

A cathode-ray tube (CRT) is a vacuum tube containing one or more electron guns, which emit electron beams that are manipulated to display images on a phosphorescent screen.[2] The images may represent electrical waveforms on an oscilloscope, a frame of video on an analog television set (TV), digital raster graphics on a computer monitor, or other phenomena like radar targets. A CRT in a TV is commonly called a picture tube. CRTs have also been used as memory devices, in which case the screen is not intended to be visible to an observer. The term cathode ray was used to describe electron beams when they were first discovered, before it was understood that what was emitted from the cathode was a beam of electrons.
Cutaway rendering of a color CRT:
Three electron emitters (for red, green, and blue phosphor dots)
Electron Beams and Electron Guns
Focusing coils
Deflection coils
Connection for final anodes (referred to as the "ultor"[1] in some receiving tube manuals)
Mask for separating beams for red, green, and blue part of the displayed image
Phosphor layer (screen) with red, green, and blue zones
Close-up of the phosphor-coated inner side of the screen
Cutaway rendering of a monochrome CRT:
Deflection coils
Electron Beam and Electron Gun
Focusing coil
Phosphor layer on the inner side of the screen; emits light when struck by the electron beam
Filament for heating the cathode
Graphite layer on the inner side of the tube
Rubber or silicone gasket where the anode voltage wire enters the tube (anode cup)
Cathode
Air-tight glass body of the tube
Screen
Coils in yoke
Control electrode regulating the intensity of the electron beam and thereby the light emitted from the phosphor
Contact pins for cathode, filament and control electrode
Wire for anode high voltage
The only visible differences are the single electron gun, the uniform white phosphor coating, and the lack of a shadow mask.
In CRT TVs and computer monitors, the entire front area of the tube is scanned repeatedly and systematically in a fixed pattern called a raster. In color devices, an image is produced by controlling the intensity of each of three electron beams, one for each additive primary color (red, green, and blue) with a video signal as a reference.[3] In modern CRT monitors and TVs the beams are bent by magnetic deflection, using a deflection yoke. Electrostatic deflection is commonly used in oscilloscopes.[3]
The rear of an LG.Philips Displays 14-inch color cathode-ray tube showing its deflection coils and electron guns
Braun's original cold-cathode CRT, 1897
Typical 1950s United States monochrome CRT TV
Snapshot of a CRT TV showing the line of light being drawn from left to right in a raster pattern
Animation of image construction using the interlacing method
Color computer monitor electron gun
The tube is a glass envelope which is heavy, fragile, and long from front screen face to rear end. Its interior must be close to a vacuum to prevent the emitted electrons from colliding with air molecules and scattering before they hit the tube's face. Thus, the interior is evacuated to less than a millionth of atmospheric pressure.[4] As such, handling a CRT carries the risk of violent implosion that can hurl glass at great velocity. The face is typically made of thick lead glass or special barium-strontium glass to be shatter-resistant and to block most X-ray emissions. This tube makes up most of the weight of CRT TVs and computer monitors.[5][6]
Since the early 2010's, CRTs have been superseded by flat-panel display technologies such as LCD, plasma display, and OLED displays which are cheaper to manufacture and run, as well as significantly lighter and thinner. Flat-panel displays can also be made in very large sizes whereas 40-45 inches (100-110 cm) was about the largest size of a CRT.[7]
A CRT works by electrically heating a tungsten coil[8] which in turn heats a cathode in the rear of the CRT, causing it to emit electrons which are modulated and focused by electrodes. The electrons are steered by deflection coils or plates, and an anode accelerates them towards the phosphor-coated screen, which generates light when hit by the electrons.[9][10][11]

[@surajkumar-gi5xc]

Nice explanation 👍

[@lalitkashyap3696]

This is knowledge full , you understand very well👍