how plasma tv works

7/30/2019 How Plasma TV Works

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What is Plasma?Plasma is often called the "Fourth State of Matter", the other three

being solid, liquid and gas. A plasma is a distinct state of mattercontaining a significant number of electrically charged particles, anumber sufficient to affect its electrical properties and behavior. Inaddition to being important in many aspects of our daily lives, plasmas

are estimated to constitute more than 99 percent of the visibleuniverse.In an ordinary gas each atom contains an equal number of positive and

negative charges; the positive charges in the nucleus are surroundedby an equal number of negatively charged electrons, and each atom iselectrically "neutral". A gas becomes a plasma when the addition of heat or other energy causes a significant number of atoms to release

some or all of their electrons. The remaining parts of those atoms areleft with a positive charge, and the detached negative electrons arefree to move about. Those atoms and the resulting electrically chargedgas are said to be "ionized". When enough atoms are ionized tosignificantly affect the electrical characteristics of the gas, it is a

plasma.In many cases interactions between the charged particles and the

neutral particles are important in determining the behavior andusefulness of the plasma. The type of atoms in a plasma, the ratio of ionized to neutral particles and the particle energies all result in abroad spectrum of plasma types, characteristics and behaviors. These

unique behaviors cause plasmas to be useful in a large and growingnumber of important applications in our lives.

The plasma behind the plasma TV screenFor the past 75 years, the vast majority of televisions have been builtaround the same technology: the cathode ray tube (CRT). In a CRTtelevision, a gun fires a beam of electrons (negatively-charged

particles) inside a large glass tube. The electrons excite phosphoratoms along the wide end of the tube (the screen), which causes thephosphor atoms to light up. The television image is produced bylighting up different areas of the phosphor coating with different colors

at different intensitiesCathode ray tubes produce crisp, vibrant images, but they do have aserious drawback: They are bulky. In order to increase the screenwidth in a CRT set, you also have to increase the length of the tube (togive the scanning electron gun room to reach all parts of the screen).Consequently, any big-screen CRT television is going to weigh a tonand take up a sizable chunk of a room.

Recently, a new alternative has popped up on store shelves: the

plasma flat panel display. These televisions have wide screens,comparable to the largest CRT sets, but they are only about 6 inches(15 cm) thick. Based on the information in a video signal, thetelevision lights up thousands of tiny dots (called pixels) with a high-energy beam of electrons. In most systems, there are three pixelcolors -- red, green and blue -- which are evenly distributed on the

screen. By combining these colors in different proportions, thetelevision can produce the entire color spectrum.The basic idea of a plasma display is to illuminate tiny coloredfluorescent lights to form an image. Each pixel is made up of three

fluorescent lights -- a red light, a green light and a blue light. Just likea CRT television, the plasma display varies the intensities of the

different lights to produce a full range of colors.



The central element in a fluorescent light is a plasma, a gas made upof free-flowing ions (electrically charged atoms) and electrons

(negatively charged particles). Under normal conditions, a gas ismainly made up of uncharged particles. That is, the individual gasatoms include equal numbers of protons (positively charged particles inthe atom's nucleus) and electrons. The negatively charged electrons

perfectly balance the positively charged protons, so the atom has a netcharge of zero.If you introduce many free electrons into the gas by establishing anelectrical voltage across it, the situation changes very quickly. The free

electrons collide with the atoms, knocking loose other electrons. With amissing electron, an atom loses its balance. It has a net positivecharge, making it an ion.In a plasma with an electrical current running through it, negativelycharged particles are rushing toward the positively charged area of theplasma, and positively charged particles are rushing toward thenegatively charged area.

In this mad rush, particles are constantly bumping into each other.These collisions excite the gas atoms in the plasma, causing them torelease photons of energyXenon and neon atoms, the atoms used in plasma screens, releaselight photons when they are excited. Mostly, these atoms releaseultraviolet light photons, which are invisible to the human eye. Butultraviolet photons can be used to excite visible light photons, as we'll

see in the next section.

Inside the DisplayThe xenon and neon gas in a plasma television is contained inhundreds of thousands of tiny cells positioned between two plates of

glass. Long electrodes are also sandwiched between the glass plates,on both sides of the cells. The address electrodes sit behind the cells,



along the rear glass plate. The transparent display electrodes, whichare surrounded by an insulating dielectric material and covered by a

magnesium oxide protective layer, are mounted above the cell, alongthe front glass plate.

Both sets of electrodes extend across the entire screen. The displayelectrodes are arranged in horizontal rows along the screen and theaddress electrodes are arranged in vertical columns. As you can see in

the diagram below, the vertical and horizontal electrodes form a basicgrid.

To ionize the gas in a particular cell, the plasma display's computer

charges the electrodes that intersect at that cell. It does this thousandsof times in a small fraction of a second, charging each cell in turn.When the intersecting electrodes are charged (with a voltagedifference between them), an electric current flows through the gas inthe cell. As we saw in the last section, the current creates a rapid flowof charged particles, which stimulates the gas atoms to releaseultraviolet photons.

The released ultraviolet photons interact with phosphor material coatedon the inside wall of the cell. Phosphors are substances that give off

light when they are exposed to other light. When an ultraviolet photonhits a phosphor atom in the cell, one of the phosphor's electrons jumps



to a higher energy level and the atom heats up. When the electron fallsback to its normal level, it releases energy in the form of a visible light

photon.

The phosphors in a plasma display give off colored light when they areexcited. Every pixel is made up of three separate subpixel cells, eachwith different colored phosphors. One subpixel has a red lightphosphor, one subpixel has a green light phosphor and one subpixel

has a blue light phosphor. These colors blend together to create theoverall color of the pixel.By varying the pulses of current flowing through the different cells, the

control system can increase or decrease the intensity of each subpixelcolor to create hundreds of different combinations of red, green andblue. In this way, the control system can produce colors across theentire spectrum.

The main advantage of plasma display technology is that you canproduce a very wide screen using extremely thin materials. Andbecause each pixel is lit individually, the image is very bright and looksgood from almost every angle. The image quality isn't quite up to the

standards of the best cathode ray tube sets, but it certainly meetsmost people's expectations.The biggest drawback of this technology has to be the price. Withprices starting at $4,000 and going all the way up past $20,000, thesesets aren't exactly flying off the shelves. But as prices fall andtechnology advances, they may start to edge out the old CRT sets. Inthe near future, setting up a new TV might be as easy as hanging a

picture!

A Note About DTV and HDTVOn April 4, 1997, the FCC ushered in digital television (DTV) by giving6MHz of spectrum to approximately 1,500 stations for DTV

broadcasting. The decree required the three commercial networks inthe top ten markets to broadcast digitally by May 1, 1999, withmarkets 11 through 30 online by November 1, 1999. All stations mustbroadcast digitally by 2006, when their current analog spectrum is

scheduled to revert back to the Fed.While there is only one standard, there are 18 different video formats.The first split is between high definition and standard definition TV. Sixof the video formats in the ATSC DTV standard are high definition TV:

these are the 1080-line by 1920-pixel formats at 24 and 30 frames persecond (1080i) , and at 60 fields per second for interlaced HDTV, andthe 720-line by 1280-pixel formats at 24, 30 and 60 fps (720p). The

HDTV formats have a 16:9 aspect ratio.



The 12 video formats which compose the remainder are standarddefinition television -- not high definition. These consist of the 480-line

by 704-pixel formats in 16:9 widescreen and 4:3 aspect ratios (at the24, 30 and 60 pictures per second rates); and the 480-line by 640-pixel format at a 4:3 aspect ratio at the same picture rates.The formats which represent HDTV are 1020i and 720p. The "i" and

the "p" in the format names refer to interlaced and progressivescanning. In interlaced scanning, half of the lines in a full frame arescanned onto the screen in a sixtieth of a second, followed by theremaining half of the scan lines in the next sixtieth. The odd lines are

scanned first, then filled in by the even lines.In an attempt to meet expectations, many plasma manufacturers arebuilding both standards into their units.

PLASMA TV Vs LCD TVPLASMA TV Vs LCD TVPLASMA TV Vs LCD TVPLASMA TV Vs LCD TV

Size: Both LCD TVs and plasma TVs are thin as you could hope for. In screen

size plasmas usually run larger though don’t usually come in smaller sizes,which is sometimes needed. Viewing Angle: Plasma have a wider viewing angle.Life Span: Both have good lifespan. Issues: Plasma sometimes suffer from

“burn in” effect. LCD TVs are sometimes susceptible to a delay that causes theoutline of figures or objects to appear jagged. Color: LCD TVs are renowned fora sharp picture and vibrant color. Plasma TVs are known for a wide range of colors and accurate color reproduction. Brightness: LCD TVs are said to doslightly better in bright-light conditions. Black Levels: Plasma TVs generallyproduce very black blacks whereas an LCD TV will produce a very dark charcoalgray. Contrast Levels: Plasma TVs, technically, are said to have greater contrast

levels. Cost: Prices for both types of TVs are decreasing rapidly.

Burn-In Effect

For plasma TVs, one of the biggest potential negatives is the “burn in” effect. Burn in is whenan image stays on the screen for an extended period of time and then gets somewhat burnedin to the screen. This might happen, for example, when you watch a movie that places blackbars on the edges in order to keep the original theater ratio. To avoid this with movies, youcan zoom in one click to fill the screen. But burn-in might also occur if you leave your TV on anews channel that runs a news ticker across the bottom. The better plasma TVs have afeature called “white flash” that allows for correction if burn-in occurs; however using thisfunction is said to shorten the TV's lifespan. For most TV viewers, however, burn-in will not bean issue. Unless you keep your TV constantly tuned to a news channel, or run movies 24

hours a day, you won’t have to worry much about this. For LCD TVs, burn-in isn’t a problem.

Watching Motion

It’s generally thought that plasma TVs handle fast-moving action better than LCD TVs. On anLCD TV, when watching a football player moving down the field, for example, it might seemas if the edges of his body are somewhat fuzzy – a jagged and blocky line rather than a crisp,clean one. This is a delay caused by the TV not being able to keep up with the action. LCDTVs are improving in this area, however, and the problem lessens considerably whenwatching high-definition TV. This is something for sports fans, especially, to consider. Butmany sports fans with a large plasma or LCD TV will already have HDTV. As mentioned, anHDTV signal increases picture quality dramatically.



Pixel Problems

Both LCD TVs and plasma TVs may suffer from pixel problems – when a pixel is either always “on” (lit up when the screen is black, for example), or the pixel is always “off” (blackwhen it should have color or be white). A few dead pixels here and there are not going to benoticeable, and companies usually state that a few dead pixels are “allowed.” One of the best

ways to avoid problems with dead pixels is to go with reputable manufacturers. If you go witha reputable manufacturer, you’re less like to have the problem in the first place, and if for some reason you do have the problem, a reputable manufacturer will take care of it.

Life Span

Both LCD TVs and Plasma TVs have a good expected life span, and it’s getting better all

the time. That said, LCD TVs ultimately win in this category because their light source can

be replaced. Once a plasma TV has faded, that’s pretty much it.

Plasma TVs are said to last up to at least 30,000 hours before noticeable depreciation takes place. Some manufacturers are now saying their plasma TVs are testing up to 60,000 hours

before any quality is lost. The questions to ask, then, are obvious: How much TV do I

watch? And when will I be buying another TV? Even at the low-end mark of 30,000 hours,

if you watched TV 10 hours a day, 365 days a year, you would go a little over 8 years

before seeing major picture depreciation. If you dropped that number down to 4 hours a

day, 365 days a year, you’d get over twenty years before seeing depreciation.

As was said before, an LCD TV can theoretically last longer than a plasma TV because the

light source can be replaced. Replacing the bulbs on an LCD, however, can be quite

expensive in itself (a few hundred dollars). By the time you’re ready to do that, you might

be ready for a new TV anyway. But, if not, an investment of a few hundred dollars will get

your old TV back, good as new.

Plasma vs. LCD TVs: Overall Picture Quality

Color, Brightness, Black Levels, & Contrast

This area is obviously the most subjective of all the areas, but perhaps the most important too. What

someone’s personal taste is will determine what he or she considers to be pleasing. It’s this area that

will probably determine more than any other which type of TV you get in the end. It’s not about

saying one is “better” than the other, but instead, it’s about saying one has “this type of quality aboutit” and the other has “that type of quality about it.”

This is what all the peanut butter vs. jelly nonsense was about in the beginning. They each have their

own qualities, and if you can’t have both, you have to decide which one you would rather live with.

Color

In general, most agree that LCD TVs produce “sharper” pictures with colors that seem more alive.

Sounds like a winner automatically, but not necessarily. With plasma TVs, you generally get more

realistic colors and a wider range of colors. An LCD TV might be more likely to wow you when you

walk in the room, but once you stay in the room for a while, you might prefer the warmth and depth



of the plasma. LCD TVs, you might say, give you a vibrant, primary colors type of feel. Plasma TVs

give you subtler, warmer pastels, but perhaps more realistically accurate. Again, it’s all personal

taste. Blondes vs. Brunettes. Tank tops vs. Cardigans. Impressionism vs. Realism.

Brightness

As for brightness, most would agree that the numbers the manufacturer gives you are nearly

worthless. The numbers, even if you were to understand them, aren’t achieved in real-life conditions

with various types of ambient light. Your own particular viewing area will play into this

considerably, but most people report LCD TVs doing slightly better in bright-light conditions.

Again, going with the general theme here – LCD TVs tend to be brighter and more colorful; plasma

TVs tend to be warmer with more accurate color reproduction.

Black Levels

The one area of this section that would seem to go against the generalizations made above is the areaof “black levels.” You might think that LCD TVs, having the reputation for being “sharper,” would

produce deeper, darker blacks. But most agree this isn’t so. Producing a deep, dark black on an LCD

TV is a somewhat complicated process. Instead of producing a full, deep blackness when required to

do so, a very dark gray is produced instead. For many, however, this goes unnoticed, especially after

growing used to the set’s colors. But it is another check mark in plasma column, and another reason

why lovers of plasma TVs are in their corner.

Contrast Levels

As for contrast levels, you will see all sorts of ratios such as 3000:1. This is a measure of the darkest

black compared to the lightest white. Because of plasma TVs’ ability to produce blacker blacks, theyusually win out in this category. Most people see LCD TVs as being more “vibrant,” however,

which would appear to be at least partly related to contrast. So the decision is a personal one, based

on personal taste.

Plasma vs. LCD TV Prices

Finally, price. At the moment, in general, the price of a large LCD TV is going to be alittle more expensive than the same large-sized plasma TV. The caveat with all of LCD

TVs negatives, as you may have noticed, is that “they’re improving.” The same is true

here. While plasma TVs have been out on the market for a while and have established

something of a reputation, the truth is, LCD TVs are hot in the public’s mind at the

moment. Maybe that’s because they’re new. Maybe it’s because they’ve gotten some

good press and good advertising. Whatever the reason, that fact alone will help push

manufacturers to lower prices to make them more competitive with plasma TVs. The

LCD vs. Plasma battle is already on, but when prices come down even more for each,

it’s going to get fierce. But maybe everyone will win in the end. Unlike computers,

where compatibility with other computers is an issue, in the TV market, two competing

technologies don’t necessarily have to be at odds with each other. Some people will

simply have an LCD TV in their homes, and others will have a plasma. No beefs, no



problems, no hard feelings. The LCD vs. Plasma war is only important for those in the

buying stage.

One last word on prices: Obviously, they can fluctuate quickly, from day to day even.

And so listing prices here is almost pointless. You’ll need to check a dealer for the

latest.

A Summary of LCD vs. Plasma TVs

Size

Both LCD TVs and plasma TVs are as thin as you could hope for. In viewable screen size, though LCD

TVs are getting bigger everyday, plasmas generally run larger. Once you get into the larger sizes, you

will also find a bigger selection among the plasma TVs. Plasma TVs, however, don’t generally come in

smaller sizes, and sometimes you need a smaller size.

Viewing Angle

Plasma TVs generally have a larger viewing angle than LCD TVs, however high-end LCD TVs do live

up to their claimed 170° viewing angle.

Life Span

Both LCD TVs and plasma TVs have good lifespan, but LCD TVs can technically last longer because

their light source can be replaced. The low end for both LCD TVs and plasma TVs these days is 30,000

hours, with many going up to 60,000 hours before noticeable picture depreciation takes place.

Issues with Each Type of TV

Burn-in: Plasma TVs have a reputation of occasionally suffering from “burn in” effect. This is not such

a problem for your average user, unless you leave your TV tuned to a channel with a continuous news

ticker. A function called “white flash” can erase the burn in effect, but it takes some life off the TV’s

lifespan.

Watching Motion: LCD TVs can be susceptible to a delay that causes the outline of figures or objects to

appear jagged or blocky when in motion. High definition TV greatly reduces this effect.

Pixel Problems: Both LCD TVs and plasma TVs can be affected by pixel problems. This is not generally

a problem with name brand versions, and if it occurs severely, your warranty will cover it.

Color, Brightness, Black Levels, & Contrast

Color: LCD TVs are known for their sharp pictures and lively color. An LCD TV’s colors are vibrant

and can wow you when you walk into a room. Plasma TVs are known for their wide range of colors and

their accurate color reproduction. A plasma TV’s colors are warm and deep.

Brightness: Brightness numbers from manufacturers will mean little because they aren’t measured under

real-life conditions. Your own viewing area will play into this considerably. LCD TVs have the

reputation of doing slightly better in bright-light conditions.

Black Levels: Plasma TVs generally produce very black blacks whereas an LCD TV will produce a very



dark charcoal gray. The very dark gray that LCD TVs produce is sufficiently dark for most people.

Many would take it for black if not told otherwise.

Contrast Levels: Plasma TVs, technically, are known to have greater contrast levels than LCD TVs,

however many see LCD TVs as being more vibrant, which seems connected to contrast, at least in the

mind of most viewers.

Cost

LCD TVs are generally a little more expensive than plasma TVs when talking about the larger sizes.

Prices for both, however, are coming down rapidly.

The 12 Most Important Differences:

1. Plasmas TVs are made of chemical compounds called phosphors. LCD TVs use millions of crystalssuspended in a liquid crystal sandwich.

2. You have a wider selection of larger-size TVs with plasmas (though LCDs are catching up).

3. Plasma don’t come in smaller sizes, which you will need for places like the kitchen.

4. Plasmas tend to have a wider viewing angle (though, again, LCDs are catching up).

5. Plasmas can suffer from burn-in effect; LCD don’t.

6. LCDs can produce a jagged figure when in motion. Plasmas tends to do better. HDTV improves this

problem dramatically for both.

7. You can replace the light source with an LCD, thereby bringing your original picture back. With

plasmas you can’t.

8. LCDs produce sharp, lively colors. Plasmas produce warmer and more accurate colors.

9. LCDs tend to do better in bright-light conditions.10. Plasmas tend to produce blacker blacks.

11. Plasmas, “technically,” produce a higher contrast range.

12. At the moment, plasmas tend to run a little cheaper, but this is changing rapidly as LCDs flood into

the market.

Plasma vs. LCD TVs: An Analogy

And so, back to our peanut butter and jelly analogy. If I can, without seeming too ridiculous, I’d like to

propose that plasma TVs are like peanut butter and LCD TVs are like jelly. Plasma TVs are like

peanut butter because, at least for now, they’re generally bigger (more filling in that way). Their picture, compared to an LCD TV’s picture, is also somewhat smoother and creamier, like peanut

butter. Plasma TVs aren’t so much flashy and sweet as they are filling and hearty. Their colors are

earthy and authentic. LCD TVs are like jelly in that they are flashy and sweet. LCD TVs are known

for their color and vibrancy, their crisp picture. It’s this crispness, this type of tanginess that brings to

mind the tangy sweetness of jelly, the colorful, clean transparency of it. If you have a sweet tooth, if

you favor this particular taste, nothing else is going to satisfy you. Not peanut butter, not hamburger,

not even a 20-ounce steak. You need an LCD TV. But if you want a good, down-to-earth, filling meal,

a plasma TV is probably your choice.

(Warning: Actually ingesting either of the of TVs has been known to cause indigestion.)

how plasma tv works

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