HDTV Plasma Display Technology

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Plasma TV Technology.

Plasma history
Plasma screens first entered the U.S. market towards the end of 1999, but the concept has been around since July of 1964 at the University of Illinois.

Digital television is now a reality -- but you're not going to see it the way it was meant to be seen using yesterday's TV sets. Today, we're in the midst of a digital video revolution, thanks to HDTV, DTV, DVD-Video, digital satellite broadcasts and computer video. Plasma display technology is one way to fully enjoy the dramatically improved image quality of all these digital video sources.

How does a plasma display work ?

The plasma panel is composed of two sheets of glass with a series of ribs ( like corrugated cardboard ) filled with color phosphors in between. The top glass with embedded electrodes seals and forms a pixel where the junctions of the channels and the plate come together. Inside the sealed pixel, is a mixture of rare gases- typically argon and neon, although xenon has also been used.

Actually a small electric capacitor has been created, with one electrode on the rear and a pair on the front. These 3 electrodes control the capacitor charge, sustain and discharge functions intrinsic to the plasma imaging process.

The plasma imaging cycle can be broken into following steps. initially, the pixel is at its resting ( ie. Off ) state. When a voltage is applied to the addressing electrodes ( pixel ) and the applied voltage reaches a certain level- say 200+ volts - the resistance in the pixel is overcome, and an electrical discharge is made across the electrodes. Once this discharge occurs, the mixture of rare gases is ionized into a plasma state, which means the gas mixture can now conduct electricity, an intense burst of ultraviolet ( UV ) light is emitted. This burst of UV energy stimulates the color phosphors, in turn makes them glow brightly.

Once the pixel is switched On, a much lower voltage sustains the UV emissions and keeps the phosphors glowing. This sustain voltage is typically in the 50 volts range. Eventually, the pixel will need to be turned off to rest the phosphors. This is done by removing the sustain voltage first, then reversing the charge in the pixel through the addressing electrodes. At this point, the pixel is back to its resting state.

What is Life Expectancy of a Plasma TV?

There has been much discussion about the life expectancy of plasma monitor/TVs. It is an interesting topic with many misconceptions.

The long and short of it is that it depends upon your daily hourly usage as well as how you use the monitor. 12 to 17 years is the short answer.

Manufacturer’s figures for longevity vary by manufacturer but they all fall in the range of 20,000 to 30,000 hrs.

For consumer use these numbers should be comforting. Plasma Displays are now about equivalent in longevity to CRTs, which typically state 25,000 hours or so life. Let's put these hours in perspective.

The average U.S. household watches 4 to 6 hours of television per day. Taking a mean time manufacturer stated longevity of 22,500 hours of usage, times our average 5 hours per day we come up with over 12 years of usage. And that is on the low side of estimates. At 4 hours per day and 25,000 hours we are looking at 17 years.

Now, there are varying degrees of phosphor ignition along the way (the same way a CRT fades). Dissipation begins the moment you turn the set on. After 1000 hours of usage a plasma monitor should measure around 94% brightness, which is barely noticeable to the naked eye. At 15,000 to 20,000 hours the monitor should measure around 68% brightness or to say it differently, 68% of the phosphors are being ignited.

There are steps you can take to ensure longer and better life from your plasma display panel.

1) Never leave static images on the unit. Do not pause a picture on the plasma for more than a minute. This will cause phosphor burn in. Watch the unit in full widescreen format as much as possible to avoid differentiation between the side bands of the unit. While this does not actually decrease the longevity of the phosphors it does cause an annoyance to have to play a gray static image to "erase" the burn in.

2) Use Brightness and Contrast levels that are necessary for viewing - not excessive. In a brightly lit room you may need to use more contrast and brightness, which will decrease the life of the unit. However, there are memory setting adjustments available on most recent plasma monitors that allow the user to choose a memory setting to suit viewing needs. At night, or in a lower light room use lower contrast and brightness levels and extend the life.

3) Keep the unit in a well-ventilated area. It will not have to work as hard to cool itself.

4) Turn the unit off when not in use.

How do the manufacturers know how to calculate the figures since plasma monitors have not been out long? The manufacturer facilities in Japan test plasma panels at 100% white image light and measure down from that point with meter readings. It takes hours to find that 50% mark - between 30,000 and 50,000 hours.

How do I input a television signal to a plasma screen display?
Only a few Plasma monitors come with built in tuners. For most Plasma TV Monitors an NTSC/ATSC television signal must be passed through a satellite box, cable box, HDTV receiver, VCR/VHS device, or an outboard tuning device. Most of these components offer an RF style cable input (what we think of as a cable connection). Signals are then passed to the plasma TV using the following connections:

From a satellite box an S-video cable is normally utilized.
From a cable box a composite RCA to RCA or RCA to BNC connection is used.
From an HDTV decoder box a 15 pin VGA to 15 pin VGA cable is normally used; though 3 cable component RCA to component RCA or BNC is also often an option.
From a VCR/VHS an RCA to RCA or BNC is normally used though S-video is better option if available on the VCR.
Optional decoders will have a mix of the above options.

Will Plasma TVs become outdated soon?

Absolutely not, Plasma TVs are ready for the future. Whether it be DVD, HDTV, Digital TV, or a digital satellite receiver, the Plasma TV is the perfect display companion. The dramatic, high-impact picture makes it not only compatible but a very wise choice of television viewing.

Why a Plasma TV?.

Digital television is now a reality-- but you're not going to see it the way it was meant to be seen using yesterday's TV sets. Today, we're in the midst of a digital video revolution, thanks to HDTV, DTV, DVD-Video, digital satellite broadcasts and computer video. Plasma display technology is one way to fully enjoy the dramatically improved image quality of all these digital video sources.

Higher resolution
Plasma display devices have higher resolution than conventional TV sets, and are capable of displaying full HDTV and DTV signals as well as XGA, SVGA and VGA signals from a computer. For example, you can get plasma displays with a 1024 x 1024 pixel high-resolution that can display images at true 1080i and 720p HDTV resolution, as well as 480i and 480p HD signals.

No scan lines

Plasma screens have no scan lines due to the fact that each and every pixel cell has its own transistor electrode. This creates a smooth evenly lit image across the entire surface of the display.

Most current plasma displays also include built-in line doubling to improve image quality from low resolution video signals (VCR tapes). Conventional CRTs use an electron beam to scan the picture tube from top to bottom at regular intervals, lighting the phosphors to create the image. With standard (NTSC) TV, visible scan lines can be seen.

Exceptional color accuracy
High-end plasma displays are capable of displaying 16.77 million colors -- providing superb color realism with exceptionally subtle gradations between colors.

Widescreen aspect ratio
Plasma display devices have a widescreen (16:9) aspect ratio, which states the dimensional relationship between the screen's width and height. This is the proper aspect ratio for HDTV viewing, and also allows many DVD-Video movies to be viewed in widescreen format, as originally seen in the theater.

What happens when viewing a regular TV or computer image? Does the image look stretched? There are several aspect ratios which plasma displays use to size the incoming video image. All plasma screens can show the image in its original 4:3 format with bars (either black or gray) on the sides of the image. There can be some variation among plasma screens in how well they convert a 4:3 image to the widescreen monitor. Manufacturing engineers accomplish a best of all worlds approach by limiting the stretching in the center of the screen and also by enlarging the entire image size to larger than the screen size. This scaling technique allows the most stretching to be located on the sides of the image thus reducing visible distortion.

So the answer to the question is that a viewer may watch the image on the plasma screen in a variety of ways when displaying an incoming "normal" or 4:3 picture image from satellite, VCR, or cable TV. It can be displayed as is with the bars on the sides. In Zoom mode the image will have very little distortion or stretching and will fill the entire screen area. However, this mode usually is not favorable because it cuts off too much of the picture image and also because it causes motion artifacts and pixelation, or grainy appearance. The 16:9 aspect option will not be the preferred method of converting a 4:3 image because it will be the most visibly stretched and distorted of all the options.

The best option for converting a 4:3 NTSC TV signal to the widescreen monitor is the "just" or "full" mode. Each manufacturer calls this mode something different. This aspect ratio option converts the 4:3 image with specially designed algorithms, which reduce the visible "stretching" as much as possible by using a combination of techniques. The end result is that the viewer will get passable performance and be able to enjoy the full screen dimension of the plasma display. This is accomplished by slightly enlarging the picture past the actual viewing area of the plasma panel while keeping the center of the picture more accurate. The sides of the image will appear slightly more distorted and stretched but the overall result is acceptable for long and short-term viewing. Much will depend upon what the viewer is watching. Of course, HDTV is shown in widescreen, which gives the widescreen format an advantage on future viewing.

Perfectly flat screen

Plasma display monitors have screens that are perfectly flat, with no curvature whatsoever. This eliminates the edge distortion that can occur in CRT displays and also assists in allowing the wide viewing angles. The plasma display element (glass) is most often protected by an antiglare Plexiglas layer.

Uniform screen brightness

Unlike some rear and front projection televisions that suffer from uneven screen brightness -- seen as "hot spots" in the middle of the screen or a darkening near the edges and especially corners -- plasma displays illuminate all pixels evenly across the screen. This gives plasma displays their "smooth" appearance.

Slim, space-saving design
In addition to stand mounting, they can be hung on a wall or from a ceiling, allowing you to enjoy big-screen home theater impact from a component that doesn't dominate floor space.

Plasma display monitors are only a few inches in depth, providing installation options never before possible. Depth is usually measured at around 3.5 inches on 42" displays and 4" for 50" screens. Conventional CRT's, DLP TVs, and rear projection TVs take up far more space and are much more limited in placement flexibility.

Plasma monitors are constructed with a chassis that's not much wider than the actual display screen, giving the monitors an elegant, understated "picture frame" appearance that blends inconspicuously with any décor.

Because they eliminate the need for a front projection unit and a projection screen, plasma display monitors are also ideal for use in a wide variety of business and commercial applications where the use of a front projector would not be feasible.

Wide viewing angle
Plasma displays offer a viewing angle of 160 degrees (top to bottom and left to right) -- much better than rear projection TVs and LCD displays. This allows a larger number of viewers to enjoy proper image reproduction from a wider variety of locations throughout the room.

Universal display capability
Most plasma monitors can accept any video format. Typically, they will include composite video (NTSC, PAL SECAM) (standard RCA or BNC jacks), S-video and component video inputs, plus one or more RGB inputs to accept the video output from a computer.

Whether you want to view a sporting event on HDTV, a DVD-Video movie, a satellite broadcast or even surf the Internet with incredible big screen impact, chances are a plasma monitor will accommodate your needs.

Immunity from magnetic fields
Because plasma displays do not use electron beams, as conventional CRT displays do, they are immune to the effects of magnetic fields. Components such as loudspeakers that contain strong magnets can distort the picture if placed too close a standard TV (which has a CRT). On the other hand, plasma displays can be placed in close proximity to any type of loudspeaker and not experience image distortion.