Monday, October 5, 2009

Plasma Flatscreen Television

Until fairly recently when LCD and plasma flatscreen television was introduced, all television screens were cathode ray tubes. The cathode ray tube was invented in 1897 by Karl Braun. The cathode ray tube is commonly called a picture tube. Inside a picture tube is an electron gun that fires a stream of electrons inside the vacuum tube. The back of the viewing screen is coated with phosphorous. Phosphorous is a metal that glows when the atoms are �excited� by being hit with the negatively charged electrons coming from the electron gun. The picture is created by causing different areas of the screen to glow with different colors at different levels of intensity. Plasma flatscreen television works on the same general principles but does it differently.

Cathode ray tubes produce clear vibrant images with great color depth. The problem is that to increase the screen size, you have to increase the overall size of the tube. This results in a big, bulky and extremely heavy TV sets. Enter LCD and plasma flatscreen TVs as a solution to the problem.

Plasma flatsceen television can have a 60 inch wide screen but only need to be about 15 inches thick. They weight only a fraction of what a CRT television with the same size screen weighs. However they are not lightweights either. But they do take up a whole lot less space in a room. The screen is composed of individual pixels (or dots) however unlike other technologies these dots are made up of three solid state florescent lights that glow red, green and blue. Using a very high energy electron gun, the florescent lights are �turned on� to produce the correct color to create the image.

Remember high school chemistry? The plasma flatsceen television is filled with plasma. Plasma is basically an inert (neither positive nor negatively charged) gas. By introducing negative electrons into the gas, collisions are created and the gas becomes charged which causes it to glow. The charge causes to positive and negative particle to rush toward each other and the same signed particles to repel each other. Remember all the neat experiments you did in grade school with magnets?

The gases used in the screen of a Plasma flatsceen television are xneon and neon. They are contained in thousands of tiny cells between two plates of glass. Electrodes are placed in-between each cell and the whole thing is insulated with dielectric material and then coated with magnesium oxide. The inside of the cell is coated with phosphorous. This setup converts each one of these tiny cells into a florescent light.

Pictures are created by hitting each individual cell within a Plasma flatsceen television with a current where it connects to another cell. The charge difference cause current to flow through the cell and the gas releases ultraviolet photons which collide with the phosphorous atoms causing them to glow in different colors depending on the prosperous compound used. Varying the current controls the intensity of the red, blue and green colors in each cell which makes it possible to create all colors visible to the human eye. And that, a folk is how a Plasma flatsceen television works.

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