Plasma Display

What is Plasma?

The central element in a fluorescent light is a plasma, a gas made up of free-flowing ions (electrically charged atoms) and electrons (negatively charged particles). Under normal conditions, a gas is mainly made up of uncharged particles. That is, the individual gas atoms include equal numbers of protons (positively charged particles in the atom's nucleus) and electrons. The negatively charged electrons perfectly balance the positively charged protons, so the atom has a net charge of zero.

Inside the Display

The xenon and neon gas in a plasma television is contained in hundreds of thousands of tiny cells positioned between two plates of glass. Long electrodes are also sandwiched between the glass plates, on both sides of the cells. The address electrodes sit behind the cells, along the rear glass plate. The transparent display electrodes, which are surrounded by an insulating dielectric material and covered by a magnesium oxide protective layer, are mounted above the cell, along the front glass plate.

Contrast ratio

Contrast ratio is the difference between the brightest and darkest parts of an image, measured in discrete steps, at any given moment. Generally, the higher the contrast ratio, the more realistic the image is. Contrast ratios for plasma displays are often advertised as high as 10,000:1. On the surface, this is a significant advantage of plasma over other display technologies. Yet there are no standardized tests for contrast ratio, meaning that each manufacturer can publish virtually any number. However, most manufactures follow an ANSI standard or do full on full off test. ANSI uses a checkered test pattern and measure the darkest blacks and the lightest whites at the same time, this gives a more accurate, real world rating.

Plasma TV  

Plasma television is a flat, lightweight surface covered with millions of tiny glass bubbles. Each bubble contains a gas-like substance, the plasma, and has a phosphor coating. Think of the bubbles as the pixels. Essentially millions of Neon signs.

Uniform screen brightness

Unlike some rear and front projection televisions that suffer from uneven screen brightness -- seen as "hot spots" in the middle of the screen or a darkening near the edges and especially corners -- plasma displays illuminate all pixels evenly across the screen.

 Abstract

A plasma display is made up of many thousands of gas-filled cells that are sandwiched in between two glass plates, two sets of electrodes, dielectric material, and protective layers.  The address electrodes are arranged vertically between the rear glass plate and a protective layer.  This structure sits behind the cells in the rear of the display, with the protective layer in direct contact with the cells.  On the front side of the display there are horizontal display electrodes that sit in between a magnesium-oxide (MgO) protective layer and an insulating dielectric layer. 

Conclusion

Plasma screens first entered the US market towards the end of 1999, but the concept has been around since its inception in July of 1964 at the University of Illinois. The first displays were nothing more than points of light created in laboratory experiments. The technology was developed and improved, and by the late 60's, it had become advanced enough to allow the scientists to construct geometric shapes. Today the progression in high speed digital processing, materials, and advanced manufacturing technology has made full color, bright plasma displays possible.