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Plasma Televisions – How Plasma Works

Posted by Eric Smith on

PLASMA TV

How a plasma TV works -A plasma TV is sometimes called an "emissive" display — the panel is actually self-lighting. The display consists of two transparent glass panels with a thin layer of pixels sandwiched in between. Each pixel is composed of three gas-filled cells or sub-pixels (one each for red, green and blue). A grid of tiny electrodes applies an electric current to the individual cells, causing the gas (a mix of neon and xenon) in the cells to ionize. This ionized gas (plasma) emits high-frequency UV rays, which stimulate the cells' phosphors, causing them to glow the desired color. A plasma cell is switched on and off by its own electrode. A plasma HDTV can have up to 6 million cells. -Because a plasma panel is illuminated at the sub-pixel level, light output is very consistent across the entire screen area. Plasmas produce the widest horizontal and vertical viewing angles available — pictures look crisp and bright from virtually anywhere in the room. -Do to the fact that Plasma TV screens use a phosphor coating like CRT-based TVs, the possibility of screen burn-in exists, though it's unlikely to happen with current models. To reduce the chance of burn-in, be sure to follow the manufacturer's recommendations on setup and use. (See below) Plasma TV Screen Burn-In: Is It Still a Problem? -Looking for information on other plasma tv problems? You may be interested in our article that debunks some Common Myths About Plasma TVs.Besides questions about the average lifespan of plasma TVs, the question I get most from people has to do with plasma TV screen burn-in. Which raises the question: What is plasma display burn-in, and how does one know what to expect and is it still a problem? -All phosphor based display systems (CRT direct and rear view and plasma) are susceptible to image retention also known as "ghosting, image shadowing, image burn in." This is due to physical properties of phosphor and how it reacts to light and electric impulse. -The good news is that for the past couple of years quality manufacturers have been steadily working on improving plasma technology resistance to "burn in" with great success. One technique used is motion adaptive anti burn in technology, which focuses on moving the on-screen image ever so slightly. The goal is to avoid detection by the human eye, but still move the image enough to cause color changes in the pixels. A second improvement by some manufacturers is improvement in the phosphor gas itself in order to make it more resistant. The green phosphor is the most important in this process. This is also a key element in increasing phosphor and screen lifespan to CRT levels.As a result of these advancements, a couple of prominent manufacturers now claim that plasma TVs have the same burn in resistance and susceptibility as CRT TVs. When was the last time you heard someone say that they were concerned about image burn in on their tube TV? Never? -But to digress, burn in, simply put, is a damaged pixel, whose phosphors have been prematurely aged and therefore glow less intensely than those of surrounding pixels on the plasma TV screen. The damaged or "burned in" pixel has developed a "memory" of the color information that was repeatedly fed to it in a static manner over a period of time. And that phosphor color information has actually become seared or etched into the plasma TV glass. Hence the term, "burn-in." Once these phosphors are damaged, they cannot give the same output as the other phosphors around them do. But pixels do not suffer burn-in singly. Burn-in occurs in the shape of a static image that persists on TV screens -- things like network logos, computer icons, Internet browser frames, or an entire image that has been displayed in a static manner etc. Network logos were a problem initially but they have now become sensitive to the problem and have also adapted a motion logo technology which prevents burn in. So, how do you prevent burn-in on your brand-new plasma TV screen? (1) Some obvious advice: Do not leave static images on your plasma TV screen for more than an hour. Turn off your unit when you are not watching it. Do not pause DVDs for more than 20 minutes at a time. (2) Know that plasma screens are more prone to burn-in during their first 200 hours of use. When phosphors are fresh, they burn more intensely as they are ignited. This means that relatively new plasma display TVs are prone to "ghosting", which occurs when on-screen images appear to stay on the screen belatedly. This is a function of the high intensity with which new phosphors "pop," and this phenomenon usually "washes out" on its own, as the screen displays subsequent images. Displaying a bright, or moving snow image (as with a DVD or VCR with no input) will "wash" a ghost image from the screen in most cases. Many plasma manufacturers have installed anti-burn settings, which are monotone gray or snow screen settings which recalibrate pixel intensity levels uniformly - thus eliminating any image retention (ghosting). It is a good idea to run this type of program after the first 100 hours or so. (3) Adjust the CONTRAST setting at or below 50% on your new plasma TV. These days most plasma TVs are preset to either peak or very high contrast (also called picture setting on many TVs). This forces phosphors to glow more intensely, which decreases the length of time necessary for burn-in to occur. Our advice is to reduce the contrast setting to 50% or less for the first 200 hours of use. And, be sure to avail yourself of your plasma's anti-burn-in features. (4) Some plasma televisions burn-in more easily than others. In my experience, AliS type panels -- the ones utilized by Hitachi and Fujistu -- seem more readily given over to problems with burn-in. As well, be more wary of the 2nd and 3rd tier brands as their technology is usually not as up to date as some of the better 1st tier brands. (5) When displaying video games and other content which have static images, use your burn-in protection features like power management settings, full-time picture shift (both vertical and horizontal), and automatic screen-saver functions. Check your Owner's Manual for further information. (6) Realize that quality matters with burn-in as with everything else. Purchase a plasma display that has really good scaling, so that you can watch 4:3 TV programs in widescreen comfortably. It is better not to display black bars on your TV screen for prolonged periods of time (especially in the first 200 hours), so you are probably better off watching most everything in "full screen" mode. This should not be much of a problem todays selection of widescreen HDTV and DVDT content. Also, higher quality TVs tend to be more resistant to burn-in -- though not entirely immune to it. Of the plasma displays I've owned and/or tested extensively, Samsung, Pioneer, and Panasonic seemed least prone to burn-in once the plasma screen was properly broken in. -Note: There are some applications which are simply not well suited to plasma display technology. The static flight schedule signage at airports, for example. It amazes me to walk into an airport and see a ruined plasma display monitor hanging from the ceiling with what is obviously an extreme case of permanent burn- in. As LCD monitors have decreased in price, they are being used to replace plasma displays in this types of setting. THE BOTTOM LINE ON BURN-IN Plasma TV burn-in is not an issue that should cause undue concern in the average user. With a modicum of caution, most plasma TVs will probably never have a problem with image retention. A viewer may experience temporary ghosting, but this is not cause for alarm. -If you need more information, feel free to contact us. Our representatives are happy to share their knowledge about plasma televisions and can help you make the best plasma TV choice.

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