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10 · Self-emissive

Plasma & the screen made of a million tiny neon lamps

Plasma picked up exactly where the tube left off. It makes its own light, like a CRT, but it lies flat against the wall. Behind the glass sit millions of sealed cells, each a microscopic fluorescent lamp filled with a neon and xenon gas mix. Pulse a few hundred volts across a cell and the gas breaks down into glowing plasma, which throws off ultraviolet light you cannot see. That invisible light lands on a coat of red, green or blue phosphor inside the cell, and the phosphor answers back in visible color. Every pixel is three of these cells firing together. For about a decade plasma gave the best moving picture money could buy, with deep blacks and color that an LCD of the day could not touch. Then it ran out of road.

Inside one plasma cell
Raise the voltage to fire the cell, or pick a layer
Drive voltage204 V, firing
Cell is emittingUV becomes visible light
A flat screen that lights itself

Each cell is a tiny gas lamp. Raise the voltage and the gas flashes into plasma, throwing off ultraviolet that lands on red, green or blue phosphor and glows. Drag the voltage, or pick a layer to see its job.

Station 01

From neon orange to full color

The first plasma panels held a single gas, neon, and glowed its natural orange the moment a cell fired, one color and no phosphor at all. Color plasma added xenon, which throws off ultraviolet instead of useful visible light, and painted each cell red, green or blue so that invisible light became a picture. Flip between them.

Station 02

How a cell makes gray

A plasma cell has only two states, fully on or fully off. To show a dim gray it flashes the cell on and off many times inside one frame, and your eye averages those flashes into a steady level. Each bar here is driven harder from left to right. Slow it down to catch the individual flashes, speed it up to watch them blend into smooth shades.

What you seeSmooth shades of gray

Station 03

Motion almost as clean as a tube

Plasma drives each cell in short pulses, much closer to a CRT than to a backlit panel that holds every frame lit. That is why plasma kept fast sports and film sharp while early LCDs smeared. Tap to compare the same moving block.

Station 04

Plasma against the flat panels that beat it

Plasma and LCD arrived as rivals for the flat television. OLED came later and claimed the self-emissive crown plasma was reaching for. Tap a column to see where each one stands.

TraitPlasmaLCDOLED
Makes its own light?Yes, glowing phosphorNo, filtered backlightYes, per pixel
How it lights upGas flashes into plasmaLiquid crystal valvesOrganic film glows
Motion clarityExcellent, pulsedSmears the mostVery good
Black levelDeepDark grayPerfect
BrightnessModestVery brightBright
Viewing angleWideNarrow on many panelsWide
Power & heatHungry, runs hotEfficientModerate
Burn-in riskPossible over yearsNonePossible over years
Still made?No, ended 2014Yes, everywhereYes, premium

The tradeoff

What plasma got right, and what ended it

Plasma was the first flat screen that could fill a wall and still look like a real picture. For about ten years it was the choice of people who cared most about image quality, and then it lost the war in the factory.

Strengths

  • Deep blacks and accurate color, because every cell makes its own light instead of fighting a backlight that leaks through.
  • Motion clarity close to a CRT, since the pulsed drive flashes each cell and lets it go dark rather than holding a still frame.
  • Wide viewing angles with almost no color or contrast shift, again because each cell emits its own light straight at you.

Weaknesses

  • Power hungry and hot. A big panel drew real wattage and warmed the room, sometimes with a faint buzz from the drive electronics.
  • Hard to make bright, sharp and high resolution at small sizes, so it never won the computer monitor or small television market.
  • Phosphors could burn in, and LCD got cheaper, lighter and brighter every year until plasma could not keep up. The last panels were built in 2014.

Questions

Plasma, quick answers

Why did plasma TVs disappear?

It lost on the things shoppers and factories cared about. LCD got cheaper to build, lighter to ship, brighter in a sunny room and ran cooler, while plasma stayed heavy, power hungry and hard to make in small or very high resolution sizes. Panasonic, the last big maker, stopped building plasma in 2014.

Did plasma really burn in?

It could, especially on early sets and during the first hours of use. Because the picture comes from phosphor, leaving a bright static logo or channel bug onscreen for a long time could age those cells faster and leave a faint ghost. Later sets added pixel shifting and screen wipes that made everyday burn-in rare.

Plasma or early LCD, which looked better?

For movies and sports in a dim room, plasma usually won, with deeper black, better motion and wider viewing angles. LCD won in a bright room and on a spec sheet, with more brightness, less weight, lower power and sharper text for computer use. OLED later combined most of plasma's strengths in a thin, efficient panel.