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Nolan Petrehn Plasma Televisions
Plasma TVs • In the last two decades, plasma technology formerly found only in monochrome computer displays has been adapted into full-color HD television displays. Plasma is one of the more cutting-edge TV screen technologies available today, but what is plasma? How does a plasma TV work? Also, what’s better, Plasma or LCD screens?
What is Plasma? • Plasma is, most simply put, a partially ionized gas. • Since its properties are so distinct from solids, gases, and liquids, plasma is considered to be a fourth state of matter. • While not as recognized as the other three states of matter, plasma actually accounts for over 99% of all matter in the visible universe, both in volume and in mass. • Our sun, like all stars, is made of plasma. • Also, lightning is a plasma.
How does it work? • Plasma displays are made up of millions of tiny cells between two plates of glass. • Each cell contains a mixture of noble gases: Helium, Neon, and Xenon. • Two sets of long electrodes are positioned between the two glass panels, a vertical set in front of the cells and a horizontal set behind them. • Very precise circuitry is used to charge the two electrodes that cross paths at a particular cell, creating a difference in voltage between the front and back electrodes. • This voltage difference causes the gases inside the cell to ionize, forming plasma.
How does it work? • The gas ions rush towards the electrodes and collide, emitting ultraviolet light, invisible to the human eye. • The back of each cell is coated with a phosphor, a substance that, when exposed to energized particles, produces visible light (a phenomenon known as Phosphorescence). • The ultraviolet photons produced in the ion collisions excite the phosphor coating of the cell, producing visible light.
The Big Picture • Each cell in the plasma display has either a red, green, or blue phosphor coating, and thus produces either red, green, or blue light. • The cells, called subpixels, are grouped in sets of three: one red, one green, one blue. Each set of three subpixels is called a pixel. • An HD plasma display can consist of over 2 million pixels! • By changing the pulses of current running through each subpixel, the TV’s control system can control the brightness of each subpixel. • So by changing the ratios of each subpixel’s intensity, the TV’s control system can blend each of the three colors in a pixel in billions of different combinations to produce most of the colors visible to the human eye.
Music Credit “Black and White” By KgZ