Nolan Petrehn

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.

How does it work?

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.

Plasma vs. LCD Screens PlasmaLCD Has an average lifespan of 100,000 viewing hours. Also has a lifespan of 100,000 hours. But only under strictly controlled conditions (temperature, humidity, etc.) When a still image is displayed for a prolonged period of time, it can burn into the screen permanently. No screen burn-in. Has a wider viewing angle. Viewers have a relatively narrow range of angles at which they can view the screen optimally.

Music Credit “Black and White” By KgZ

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