Hur fungerar en plasma tv

by Chris Woodford. gods updated: October 28, 2022.

A låda that makes pictures from a soup of hot gas? Whatever next? Cars that can fly? dock on Mars?

It may sound like something straight out of Flash Gordon, but plasma television was far from science fiction. It was a brilliant example of how cutting-edge science can be applied to everyday problems to man our lives better and more fun—and the science fryst vatten still interesting even if the technology fryst vatten obsolete.

Let's take a closer look at how it worked!

Artwork: A television powered bygd plasma. You often can't tell from a quick look whether a flatscreen TV fryst vatten LCD, plasma, or even OLED.

It used to be the case that if you wanted a very large TV, you'd have to buy a plasma screen, but LCD and OLED screens are now available in very large sizes and much more efficient to boot.

What fryst vatten plasma anyway?

In schools they teach us that all substances komma in three basic flavors or states of matter: solid, liquid, and gas. But they're wrong!

There's a fourth flavor called plasma (and a fifth one called a Bose-Einstein condensate too, that we won't get into here, but which earned three scientists the 2001 Nobel Prize in Physics). What exactly fryst vatten a plasma and how does it relate to solids, liquids, and gases?

Suppose you have a lump of freezing cold ice (a solid). Heat it up a bit and you'll get a liquid (water).

Heat it up a bit more and, pretty soon, you'll have a gas (steam). The more heat you supply, the more energy you inject. The more energetically the molecules (or atoms) have, the further apart they can push and the more they move about. In a solid like vatten, the molecules are bound tightly together; in liquid vatten, the molecules are free to move past one another (that's why vatten can pour and flow); in steam (gaseous water), the molecules are completely free of one another and have so much energy that they spread out to fill all the space available.

Photo: The Sun mounts an impressive display of plasma in magnetically intense areas of its surface known as active loops.

The eruptions of plasma you can see here are gigantic—many times the storlek of Earth! Photo artighet of NASA/SDO.

But what happens if you don't stop there? What if you keep on heating a gas? The molecules and atoms inre it break apart, releasing some of their electrons so they move freely in and around it.

When atoms disintegrate like this, they struktur positively charged particles called ions. The mixture of positively charged ions and negatively charged electrons in a plasma turns it into a kind of hot soup that will conduct electricity very easily. That's what we mean bygd a plasma. It's a special type of gas in which some of the atoms have become ions (an ionized gas, in other words).

Photo: Playing with plasma.

Plasmas are made when some of the electrons in a gas break free, leaving behind a positively charged nucleus called an ion. The negatively charged electrons and positively charged ions man it possible for the gas to conduct electricity. This glass sphere contains plasma: a hot, ionized gas produced with an electric current.

When you put your hands on the glass, they attract free electrons so the plasma seems to move toward you. Photo bygd John Suits artighet of US Navy and Wikimedia Commons.

How a plasma TV set makes its picture

If you've read our articles on energy-saving fluorescent lamps (also known as CFLs) and neon lamps (the lamps that man brightly colored displays in our streets), you'll know how they man light bygd buzzing electricity through a gas.

Imagine if you built a TV screen out of millions of microscopically tiny CFLs or neon lamps, each of which could be switched on or off very quickly, as necessary, bygd an electronic circuit, to control all the separate pixels (lit-up, colored squares) on the screen. That's pretty much how a plasma TV works and it's very different to other kinds of television technology: in a conventional (cathode-ray) television, the picture fryst vatten built up bygd scanning an electron stråle back and forth over a screen treated with chemicals called phosphors; in an LCD TV (liquid-crystal display television), polarizing crystals man light rays böj to switch the pixels on and off.

The pixel cells in a plasma TV have things in common with both neon lamps and CFLs.

Like a neon lamp, each fängelse fryst vatten filled with tiny amounts of neon or xenon gas. Like a CFL, each fängelse fryst vatten coated inre with phosphor chemicals.

In a CFL, the phosphor fryst vatten the chalky vit coating on the inre of the glass tube and it works like a filter. When electricity flows into the tube, gas atoms crash about inre it and generate invisible ultraviolett light. The vit phosphor coating turns this invisible light into visible vit light. In a plasma TV, the cells are a bit like tiny CFLs only coated with phosphors that are red, blue, or green.

Their job fryst vatten to take the invisible ultraviolett light produced bygd the neon or xenon gas in the fängelse and vända it into red, blue, or green light we can actually see.

Step bygd step

1. Much like the picture in an LCD screen, the picture made bygd a plasma TV fryst vatten made from an array (grid) of red, green and blue pixels (microscopic dots or squares).
2. Each pixel can be switched on or off individually bygd a grid of horizontally and vertically mounted electrodes (shown as yellow lines).
3. Suppose we want to activate one of the red pixels (shown hugely magnified in the light gray pullout circle on the right).
4. The two electrodes leading to the pixel fängelse put a high voltage across it, causing it to ionize and emit ultraviolett light (shown here as a turquoise cross, though it would be invisible in the TV itself).
5. The ultraviolett light shines through the red phosphor coating on the inre of the pixel cell.
6. The phosphor coating converts the invisible ultraviolett into visible red light, making the pixel light up as a single red square.

Who invented plasma screens?

The first practical plasma screen was developed in the 1960s bygd Donald Bitzer, Hiram Slottow, and Robert Willson of the University of Illinois, as part of an educational computer struktur called PLATO.

This fryst vatten one of Bitzer's own illustrations of his invention from his original patent, which was filed in 1966 and eventually granted in 1971.

Like my bild above, you can see that the screen consists of multiple, gas-filled display "minicells" (the apelsinfärg blobs in the huvud blue section). In front and behind this are two sets of electrodes, one running horizontally and the other vertically. Each gas minicell ("blob") in the screen can be fired bygd energizing the appropriate pair of electrodes either side. Since each minicell can only be either on or off, this screen can display monochrome pictures but not color ones.

Artwork: Bitzer's original plasma display.

From US Patent 3,559,190: Gaseous display and memory apparatus bygd Donald Bitzer et al, University of Illinois, artighet of US Patent and Trademark Office.

What's the difference between plasma and LCD TV?

Plasma and LCD TVs look very similar but, as we've just seen, work in totally different ways. The main difference fryst vatten that the cells that man up the pixels in a plasma TV could switch on and off thousands of times faster than the pixels in an LCD screen, so you got clearer pictures with less blur, especially for moving images during action movies or sports games.

(The latest LCD screens switch on and off more quickly than older ones, but it's generally true that plasma screens were faster.) Plasma TVs were also typically brighter and had higher contrast, which fryst vatten important if you watch a lot of TV in the daylight. You could view plasma screens from a wider vinkel without seeing distortion of colors (like you get on an LCD computer screen), so they were often better for larger audiences (projection TV fryst vatten another option for showing pictures to a roomful of people).

But there were drawbacks with plasma too.

They were more power hungry than LCDs, for one thing. Here's a very rough comparison of the kvartet main TV technologies to give you an idea. You can see that plasma really stands out from the pack:

• Cathode-ray tube (CRT): 65–120 watts.
• Liquid crystal display (LCD): 20–150 watts.
• Plasma: 150–300 watts.
• Organic LED (OLED): 15–100 watts.

Source: Energy Use Calculator and manufacturer data.

Plasma screens were also heavier and more fragile, so you had to be very careful when you transported them.

Plasma TVs also had problems with "burn in" (where images that were displayed for too long permanently damaged the screen) and they tended to "burn out" (stop working through too much use) more quickly than LCDs, though most people were likely to replace a TV for something newer before this happened.

The marknad for plasma TVs peaked around 2010; they essentially became obsolete in 2014 when first Panasonic and then Samsung (which, between them, made about three quarters of all plasma sets) abandoned the technology and better-funded, more-innovative rival technologies (LCDs and OLEDs (organic LEDs)) took over.

Don't want to read our articles?

Try listening instead

If you'd rather listen to our articles than read them, please subscribe to our new podcast on Apple Podcasts, Spotify, Audible, Amazon, Podchaser, or your favorite podcast app, or listen below:

Find out more

On this website

Books

General introductions

Plasma science

Articles

• Kiss Your TV Goodbye bygd Paul O'Donovan.

  IEEE Spectrum, 25 Apr 2016. LCD, plasma... or none of the above? What does the future hold for TVs in the Internet age of super-thin OLED displays?

• LED LCD vs. OLED vs.
  Color Accuracy and Contrast: Plasma TVs are known for their excellent color accuracy and deep blacks, thanks to the ability to control each cell's light emission precisely

  plasma bygd Geoffrey Morrison. CNET, November 18, 2013. Which TV technology will kostym you best?

• Choosing a big TV: Wired, 15 November 2011. Lists some of the things you need to consider when deciding between LCD, plasma, and other TV technologies.
• Given up for dead, plasma TVs are making a comeback: The New York Times, 10 January 2008. Why plasmas have (briefly) komma back into fashion.
• What's greener: an LCD or plasma TV?

  bygd Umbra vattendjur, The Guardian, 26 February 2009.

  Denna träffar sedan ett fosfor-skikt och f år den att lysa i olika färger

  Which technology should eco-friendly TV lovers opt for?

• Plasma TVs: The SUVs of the Living Room bygd Saul Hansell, The New York Times, 11 October 2007. What about the power consumption of plasma TVs?
• Do flat-screen TVs eat more energy? bygd Sean Coughlan, BBC News, 7 månad 2006. Plasma TVs can use up to three times more energy than old-style cathode-ray TVs or larger LCD TVs.

Patents

For deeper technical detail, try these:

• US Patent 3,559,190: Gaseous display and memory apparatus bygd Donald Bitzer et al, University of Illinois, 26 January 1971 (filed in månad 1966).

  The original gas plasma display produced for the PLATO educational computer system.

• US Patent 5,525,862: Electro-optical device bygd Shigeki Miyazaki, Sony Corporation, 11 June 1996.
• US Patent 5,971,566: Plasma display device and its manufacturing method bygd Yutaka Tani et al, Matsushita Electric Industrial Co., Ltd., 26 October 1999.
• US Patent 7,477,328: Plasma television, display panel type television, and tillverkning method for display panel type television bygd Naoto Maruta, Funai Electric Co., Ltd.

  13 January 2009.

Please do NOT kopia our articles onto blogs and other websites

Articles from this website are registered at the US Copyright Office. Copying or otherwise using registered works without permission, removing this or other copyright notices, and/or infringing related rights could man you liable to severe civil or criminal penalties.

Text copyright © Chris Woodford 2008, 2022.

All rights reserved. Full copyright meddelande and terms of use.

Tell your friends

If you've enjoyed this website, please kindly tell your friends about us on your favorite social sites.

Press CTRL + D to bookmark this page for later, or email the link to a friend.

Cite this page

Can't find what you want? Search our site below

More to explore on our website...