Plasma Screens How it works Cathode Ray Tubes
Plasma Screens ‘How it works? ’
Cathode Ray Tubes Television screens used to use a technology called, cathode ray tubes (CRT). An electron gun emitted electrons inside a glass tube onto phosphor atoms at the end of the glass tube, causing the phosphor atoms to light up. The electron gun scanned the screen many times per second, producing an image. Cathode Ray Tube diagram Cathode Ray Tubes Output devices
Coloured Fluorescent Lights A plasma screen works by illuminating tiny coloured fluorescent lights; a red, blue and a green light. The intensity of these three lights is varied so to make up different colours. Varying each light intensity produces an image. Plasma Screen Output devices
Plasma Screen Cell Inside one of the lights is a gas, usually Xenon or Neon These atoms are neutrally charged, although when they become unstable they can release photons producing ultraviolet light. A gas usually Xenon or Neon. Plasma Screen Output devices
Passing Electricity Flow of electrons Electricity is then passed between the gas, Xenon and Neon. This means that electrons flow through the gas freely. Electricity passed through the Xenon and Neon gas. Plasma Screen Output devices
Atoms Plasma is a gas, made up of free flowing ions (electrically charged ions) and electrons (negatively charged particles) Introduce free flowing electrons into a gas 1 2 Electrons are forced from the gas atom. Plasma Screen 4 Negative electrons rush towards the ion releasing a photon in the process 3 The atom is now ionised as it is missing an electron Output devices
Ultraviolet to Visible Light The ultraviolet light (photons) released when the ionised gas collides with negative electrons, produces ultraviolet light. The ultraviolet photons strike the surface of Phosphorus giving off light. Introduce free flowing electrons into a gas Negative electrons rush towards the ion releasing a photon in the process The ultraviolet light photons hit a phosphorous surface producing visible light. Ultraviolet photon atoms are released Plasma Screen Output devices
Ultraviolet to Visible Light The ultraviolet light (photons) released when the ionised gas collides with negative electrons, produces ultraviolet light. The ultraviolet photons strike the surface of Phosphorus giving off light. Visible Light Ultraviolet Light Plasma Screen The ultraviolet light photons hit a phosphorous surface producing visible light. Output devices
Summary How do plasma screens work? - They are made up of tiny fluorescent light cells of red, blue and green that produce light by varying their intensity. - Inside each cell is a neutral gas usually Xenon or Neon. - A controlled charge of electricity is passed through the gas allowing electrons to flow freely. - The electrons collide with the gas atoms, freeing electrons from the atoms and thus ionising the atoms giving them a positive charge. - The flowing electrons are drawn towards the ionised atoms and ultraviolet photons are released. - When the ultraviolet light hits a phosphorous surface, the ultraviolet light is transferred into visible light. Plasma Screen Output devices
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