Retrospectacle: A Neuroscience Blog

Ever wonder how plasma TV’s work? Well, I did, and decided to figure it out!

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“Traditional” televisions use cathode ray tubes, in which a gun fires a beam of electrons inside a large glass tube at phosphor atoms at the other end. The electrons excite the phosphor atoms, causing them to light up as pixels. The image is produces by lighting up different areas of the phosphor coating with different colors (red, green, blue) at varying intensities. While this sort of TV produces nice images, physically they are bulky. In order to increase screen size, you have to increase the length of the cathode ray tube. So, a big-screen TV of this sort will take up a lot of room.

Flat panel plama TVs on the other hand, can have large screens and only be a few inches thick. The basic idea of a plasma display is to use tiny fluorescent lights–made up of either red, blue, or green– to form an image on the screen. Plasma refers to gas made up of free-flowing ions and electrons. When you introduce many free electrons into the gas by exerting electrical current across it, they collide with the gas’ atoms knocking loose other electrons. This forms ions (an atom with a net positive charge).

In a plasma with an electrical current running through it, negatively charged particles are rushing toward the positively charged area of the plasma, and positively charged particles are rushing toward the negatively charged area. While the particles are bumping into each other, these collisions excite the gas atoms (xenon and neon) in the plasma causing them to release photons of light. Most of light released is UV light, which is invisible to the human eye. BUT this UV light can be used to produce light in the visible spectrum.

(More under the fold…)


The xenon and neon gas is contained in hundreds of thousands of tiny cells positioned between two glass plates. Electrodes are positioned between the glass plates; the transparent display electrodes, which are surrounded by an insulating dieletric material and covered by magnesium oxide, are mounted above the cell. So essentially, to ionize the gas in a particular cell, the plasma display’s computer charges the electrodes that intersect at that cell—it does this thousands of times in a fraction of a second. This induces the gas to release UV photons which intersect with the phosphor material which coats the inner part of the cell. This cause it to release a photon of visible light.

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Every pixel in a plama display is made up of three seperate sub-pixels—-red, blue, and green—which can be activated alone or together to create a picture. And, by varying the pulses of electricity through the different cells, the intensity of each subpixel can increase or decrease. This results in a very bright picture that looks good from any angle, but surprisingly, the image quality is not as good as the highest quality cathode ray tube televisions. (Interesting, seeing as how they are touted to be a step up in picture quality!)
Information from How Stuff Works!

Also, 10 points to whomever knows where I got the title of this post (and no Google-cheating!).

Comments

  1. #1 J-Dog
    September 15, 2006

    Without Google, I guess Star Trek!

  2. #2 Ryan S.
    September 15, 2006

    “This results in a very bright picture that looks good from any angle, but surprisingly, the image quality is not as good as the highest quality cathode ray tube televisions. (Interesting, seeing as how they are touted to be a step up in picture quality!)
    Information from How Stuff Works!

    Yes, this is important thing to realize if for instance you are purchasing a monitor to do graphics editing, and need a high degree of resolution. You will not be happy the performance.

  3. #3 Anthony
    September 15, 2006

    An Essay on Criticism by Alexander Pope
    This is from memory:
    “A little learning is a dangerous thing;
    Drink deep, or taste not, the Pierian spring.”

  4. #4 Ryan S.
    September 15, 2006

    Wow, Typos!
    Yes, this is a important thing to realize. If you are purchasing a monitor to do graphics editing, and need a high degree of resolution. You will not be happy with the performance.

    Sorry, I had to redo it. It was driving me crazy.

  5. #5 grammer nazi
    September 15, 2006

    an important

  6. #6 Kagehi
    September 15, 2006

    Unfortunately for the plasma people, new LCD types are being made that use RGBCYM. Yep, 6 colors, instead of 3, in order to produce more accurate color, with the same refresh rate as an normal LCD, which Plasma really can’t match. Then of course, some people are working on alloys that bend like plastic and can be “printed”, which has been, until now, the primary reason why we still don’t have flexible displays. Some one else is also developing a class of display that doesn’t suffer from the pain in the rear problem my Palm and Cell do, and can be read, in color, in sunlight.

    We are close to some major jumps in this tech, and Plasma… probably isn’t in a position to make the leap.

  7. #7 Shelley Batts
    September 16, 2006

    Sorry re: the typos—my on-board spell check/grammar check committed suicide. :)

  8. #8 Shelley Batts
    September 16, 2006

    10 points to Anthony—nice job!

    Although the 100% credit answer is that this quote is from “They Fly” (the Jeff Golblum one):

    Seth’s saying, “Drink deep, or taste not, the plasma spring”, is a reference to a famous quote from Alexander Pope’s “An Essay on Criticism”. The full quote is: “A little learning is a dang’rous thing; drink deep, or taste not the Pierian Spring: Their shallow draughts intoxicate the brain, and drinking largely sobers us again.”

  9. #9 linoos
    September 16, 2006

    The SED Technology that some companies (Toshiba?) are working on will be as good or better as the CRT and much cheaper to implement than any other.. But then the Nanotubes are not far behind…

  10. #10 LordZ
    September 16, 2006

    thanks for the useful info!!

  11. #11 Mark
    September 16, 2006

    @ Ryan S – to correct your correction, it should be “…an important thing to realise…”

  12. #12 Bill A
    September 16, 2006

    Yea.. SED is what i’m waiting for.. until then i keep my trusty Trinitron. Here is some basic info on SED technology
    http://www.behardware.com/articles/593-1/close-encounters-of-the-third-kind-sed.html

  13. #13 oops
    September 17, 2006

    well – why the mad rush into next gen video screens when so much more could be accomplished in the field of breast augmentation – seeing is believing!

  14. #14 lechat
    September 17, 2006

    The title is taken from the fly which referenced pope.

  15. #15 Mr Satyre
    September 17, 2006

    Plasmas have a much wider color gamut than any LCD design on the market. LCDs are limited to 16.7 million colors because of their very limited grey scale range (256 per R,G, and B pixel), which is why LCDs all suffer from cartoonish colors and low detail in high contrast areas of the picture. Plasmas have grey scales in the thousands, resulting in colors combinations ranging in the billions (wherein any plasma can have independant RGB-CYMK control). LCDs are also very far behind the curve where refresh rates are concerned, which is why LCDs have extreme difficulty in reproducing fast motion. They are catching up, but still have a ways to go.

    LCDs were designed for text and graphics (at which they excel), not for video. Plasma was designed from the ground up as a video display technology. Each has its place in the industry, but anyone who claims that an LCD has better color accuracy, better detail and better motion than a plasma needs to look at any plasma offering by Pioneer, Panasonic, Fujitsu or Samsung side-by-side with an LCD. Even the LCD engineers I deal with on a daily basis agree that plasmas far exceed what LCDs are capable of.

  16. #16 reza
    September 27, 2006

    that was good article. if you can please send me more about Plasma tecnology.thnak you.