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Plasma Television Vs. DLP Rear Projection Television

By , Reviewer

Plasma and DLP are two relatively new display technologies, which have begun to compete broadly for their respective shares of the hi-resolution television market. Despite similar target audiences, these technologies differ widely in the ways they process light-source information.

Plasma technology consists hundreds of thousands of individual pixel cells, which allow electric pulses (stemming from electrodes) to excite rare natural gases-usually xenon and neon-causing them to glow and, thus, produce light. This light illuminates the proper balance of red, green, or blue phosphors contained in each cell to display the proper color sequence from the light. Each pixel cell is essentially an individual microscopic florescent light bulb, receiving instruction from software contained on the back electrostatic silicon board.

DLP (Digital Light Processing) technology utilizes a small Digital Micromirror Device (DMD) to tilt more than 1.3 million micromirrors-each of them less than the width of a human hair-toward (ON) or away from (OFF) the light source inside the DLP. This process creates light or dark pixels on the face of the projection screen. The light then filters to a color wheel, which rotates 120 times per second, producing the correct hue. Each mirror can turn on or off several thousands of times per second resulting in a technology that can reproduce up to 1024 shades of gray. In short, the gradations in color that make DLP images stand-out are the result of color filters backlit by just the right intensity of white light. There are 4 main components in the system: the DMD chip, color wheel, light source, and optics. Light from the lamp passes through a color wheel filter and into the DMD chip which will switch its mirrors on or off in relation to the color reflecting off them, producing an image.

PICTURE CONSIDERATIONS:

CONTRAST - The measure of the darkest black in relation to the lightest white

Plasma technology has come a long way in this area. We've all heard Panasonic boast of having achieved 3000:1 and 4000:1 contrast ratings. And though these are certainly self-serving figures, I have to admit that the black levels are looking very good these days, while still showing a lot of definition. Some plasma manufacturers have not quite achieved such black levels yet, so the average contrast ratio for plasma technology as a whole is about 1000:1 or so. This figure takes into account brands from China and Taiwan that have just entered the market.

Since it is a relatively new technology, DLP displays do not have much of a track record. Samsung cites a contrast ratio of 1000:1 for their 50" DLP TV. RCA, on the other hand, does not list a contrast ratio. Nevertheless, when I compare the black levels of RCA and Samsung DLP TVs to those of Toshiba and Panasonic plasma TVs, my eyes (and my light meters) tell me the plasmas have the superior black levels-by 30% or so.

Advantage: Plasma

 

CLARITY - The measure of clean edges and lines around and inside images.

This is an interesting topic to consider because, in my opinion, it depends upon which plasma or DLP you're viewing. Both technologies are known to have excellent clarity. However, clarity of reproduced film content depends upon the internal conversion chipset, so it varies from plasma to plasma-as much as it varies from plasma to DLP. DLP appears to have inherent display clarity by virtue of the clean mirror technology it utilizes. Plasma requires mega processing and conversion, which often succeeds at producing crystal clear images and occasionally fails miserably.

Issues like clarity also depend upon the signal being viewed. HDTV will appear perfectly clear on either plasma sets or DLP ones. Which means that DVD film content should prove an excellent head-to-head test for both plasma and DLP displays.

In my tests, plasma exceeded DLP in the clarity with which it reproduced DVD signals, though not by much. That much was evident to this reviewer, but it did take some time to sort out. The Toshiba and Panasonic plasmas outperformed the Samsung and RCA DLP TVs by roughly 10% overall.

Advantage: Plasma

 

COLOR SATURATION AND ACCURACY

There is no question among onlookers that plasma technology has the advantage here. Colors appear richer, fuller, and deeper-which are precisely the traits one looks for in a great TV picture. With good Japanese brands of plasma displays, the factory settings are usually good enough to receive a picture that is virtually "spot on" with SEMPTE color standards of 6500K, thus eliminating the need for do-it-yourself picture calibration.

DLP has good color in some areas, but it is frequently spotty-missing some green here, some blue there. DLP televisions are relatively new inventions, so this could be an area of great improvement in the future. While color vibrancy is superb with DLP compared to other rear projection solutions, colors appear hazy (bright yet slightly pale or faint) next to those produced by plasmas. Hence, the Toshiba and Panasonic Plasma TVs get the nod by 25% over the Samsung and RCA DLP models.

Advantage: Plasma

 

BRIGHTNESS

This is the real genius of DLP technology when compared to its counterpart rear-projection televisions. DLPs also have a tremendous viewing angle, which differentiates them from the rest of the pack of projection TVs. DLP displays are bright and have nothing to burn out, except for a lamp that (in some cases) can be easily replaced.

The plasma TVs I reviewed are equally as bright as the DLPs, only the former look bright in different ways. The DLP brightness level washes out color richness. The picture on the Toshiba plasma is rich and consistently vibrant.

Advantage: Chalk it up to preference

 

VIDEO PLAYBACK

Everyone seems to agree that the two Plasma displays showed better with any video playback, though the difference is much less discernable with poor quality satellite or cable signals. DLP does a great job of processing this information, that is, for a rear projection TV.

Advantage: Plasma

 

OTHER CONSIDERATIONS:

SIZE

DLP televisions are rear-projection devices and thus quite well suited to larger sizes. In most cases, they require nearly the amount of room that traditional rear projection TVs do-minus the base, of course. DLP TVs fit well on to tabletop stands and are available in popular 40-, 50-, and 61-inch models. They will soon be available in 72- and 84-inch diagonal image sizes, too. Moreover, DLPs are slimmer than other rear projection TVs, measuring around 15" to 17" in depth. RCA claims to have a couple of prototypes in the 50- and 61-inch size image range that will actually hang on the wall! Manufacturers are working hard to create slimmer DLP displays to suit more applications. By late 2004, you can expect to see new prototypes being rolled out that are as slim as 8" in depth. Stay tuned.

Plasma television displays range in size from 37" to 61" along the diagonal. Plasma technology allows for a super slim design-the norm being 3.5" in depth-allowing them to be mounted in various ways on walls or set atop tables or on even on special plasma TV carts. Plasma displays are designed with minimalist decorators in mind: They have little in the way of bezel framing, and speakers are often optional. If you want an exceptionally "clean" look for your home theater, think plasma.

Advantage: Even

 

PRICE/VALUE

DLP televisions clearly possess the price advantage over plasma per viewing inch. The technology is much less expensive to product than plasma. The Texas Instruments DMD chip must is, of course, no small part of the displays overall production cost. The screen is also different from other rear projection devices and not inexpensive. You may have noticed the draught in DLP product in the fall of 2003. This was primarily due to difficulty in production capacity of the front screen panel-not the DMD chips. Aside from this, though, the modern DLP utilizes a lot of technologically commonplace materials in its design, which helps to offset the cost of its processor and screen.

Plasma TVs have been steadily encroaching upon affordability in the last few years. Many new manufacturing plants have opened in China and Korea that produce the glass panel, which is the chief plasma display element. As more plasmas displays flood the market, prices will continue to fall. Inch for inch, plasma technology will continue to beat-out LCD technology, but the former will have a more difficult time keeping pace with DLP technology.

Price Advantage: DLP per square inch.

Value Advantage: Difficult to gauge. Depends on the need.

 

MENU OPTIONS/ FUNCTIONALITY

The Toshiba and Panasonic plasma TVs I tested had clear and easy-to-control settings for the most part, though the Panasonic manual left something to be desired.

The menu settings and control options for the RCA and Samsung DLP TVs, on the other hand, were anything but clear and direct. For example, changing the green tint through the menu options on the RCA DLP required six steps. All in all, the menus offered on the DLPs were cryptic and not very user-friendly.

Advantage: Plasma-for the time being, anyway.

 

COMPUTER USE

Most plasma displays have computer input, many even having the split screen option, which allows for surfing the web while watching television. Now that is information overload! This was the case with the Panasonic I tested.

Rear projection DLP TVs are designed primarily for use as home-entertainment devices. Most DLPs are not meant to do double-duty as computer monitors.

Advantage: Plasma

 

VIEWING ANGLE

Along with D-ILA, DLPs are the best of the best among rear-projection TV technologies. Still, they are far from perfect. The eyeball test of effective viewing gives me about a 100° side-to-side viewing angle. One very important note here is that, with DLPs, the vertical positioning of the display should be very close to eye level. The vertical viewing angle on DLP televisions is far less protracted than its side-to-side viewing angle. Indeed, the vertical viewing angles of the DLPs I tested were maybe 40° or so.

Because each individual pixel is its own light and color source, plasma-display TVs are evenly lit across the surface and have a nearly perfect 180° viewing angle. This figure is uniform across all manufacturers and applies to side-to-side and to top-to-bottom viewing angles.

Advantage: Plasma

 

ALTITUDE

DLP technology is not affected by altitude considerations.

Since the plasma display element on a plasma TV is actually a glass substrate envelope containing rare natural gases, thinner air causes increased stress on the gases inside the envelope. This increases the amount of power required to run and cool the plasma, which causes louder buzzing or fan noise (do to the unit's increased self-cooling efforts). These problems usually start to occur at around 6500 feet. Lately, some plasma manufacturers such as NEC have come out with special models capable of handling altitudes to up to 8500 feet without noticeable increases in unit noise.

Advantage: DLP

 

LIFESPAN

DLP manufacturers list the backlight bulb hours at around 80,000 hours. What's more, this bulb can be replaced for as little as $200 in some cases. Certain DLP TV displays require a technician to change their bulbs, and this will cost you more than the lamp itself. In other cases, though, the DLP is configured in a way that makes it easy for a layperson to replace burned-out bulbs. It all depends on the make and model of your DLP.

And, since DLP is a mirror and light technology, once the bulb is replaced, the DLP should perform as well as it did when it was brand new.

Plasma, by contrast, uses a small electric pulse for each pixel to excite the rare natural gases argon, neon, and xenon (a k a "phosphors") to produce the color information and light. As electrons excite the phosphors, oxygen atoms dissipate. These rare gases actually have a life and fade over time. Manufacturers of plasma have estimated the life of these phosphors to be about 60,000 hours. The life of the plasma display itself is usually determined by half-life of the phosphors. So at 30,000 hours the phosphors will be at their half-life, and the viewer will be seeing an image that has half the brightness capability that it did when originally purchased. This should be a good point at which to consider its life over. The gases in plasma TVs cannot be replaced. There is no phenomenon of "pumping" new gases into a plasma display.

Advantage: DLP



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