Introduction to High-End TVs March 28, 2005

Introduction

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Once you're done reading this article, you'll hopefully be able to figure out which TV technology is right for you and will understand the basics of big screen TVs. That’ll help keep your list of TVs to shop for short. As a disclaimer, in order to make this article accessible to the widest audience, this isn’t a comprehensive or technical buyer’s guide – this one is for the novices.

TV Technology 101

All TVs can be grouped into one of two categories: those that "burn-in" and those that do not. TVs in the first category uses electricity to blast tiny particles called phosphors that glow when energized. Over time, the phosphors wear out and dim. If the phosphors on the screen all wear out evenly, it's not a problem because the changes are gradual and our eye and brain will compensate. "Burn-in" occurs when the phosphors in one part of the screen wears out prematurely.

This occurs with static images such as a TV station logo or a video game health status bar. The result is a "burned-in ghost image" – you'll see that shadow of a TV station logo on everything you watch. Another source of burn-in comes from watching non-widescreen TV shows (4:3 aspect ratio) on a widescreen TV; if the edges are always black, they will look brighter than the center of the screen.

Regular TVs and computer monitors are in this category; an electron gun (a cathode ray gun) blasts phosphors on a glass screen (the tube). CRT rear projection TVs and plasma screens also use variants of this technology. A CRT rear projector can be thought of as being made up of 7 to 9" regular TVs with a picture so bright, that the image is projected onto a screen. Plasma screens work somewhat similarly except the phosphors are energized through a different approach.

A key point is that since both CRT rear projection TVs and plasma screens more intensely energize the phosphors than a typical CRT TV, the phosphors wear out more quickly and thus more easily burn in than your classic TV or computer monitor.

The second type of TV uses a transparent or reflective colored filter and a bright light bulb. Think of it as an overhead or slide projector. There is no burn-in with this approach because the light source shines evenly across the screen. For projection TVs, a high-intensity discharge bulb similar to a luxury car headlamp or hydroponic grow light is used. These light bulbs burn out after 2000 to 5000 hours (it varies by manufacturer), but you can easily replace the bulb for about $200-$300. This is the approach used by LCD, DLP, and LCoS projection televisions. LCD flat panels also fit into this category, with the exception that it is a row of cold cathode fluorescent bulbs that light up the screen.




SIDEBAR: LCD Panels using LED backlighting technology have been demoed. They won’t be affordable for many years.

Color and Contrast

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With phosphor based technology, black is easy to produce – you don't energize that area. On the other hand, something like LCD has to create black by trying to block out as much light as possible, ultimately resulting in a dark gray. That means that TVs that burn-in can offer a better picture. As a general rule of thumb, and if your budget allows, I wouldn't recommend going with a TV that can burn-in if videogames are going to be played more than 25% of the time or if you prefer to watch old non-widescreen TV shows without stretching them to fill the widescreen.

"HDTV Ready" vs. "Integrated HDTV"

Many televisions sold today have the label HDTV ready. With an HDTV ready television, you will only be able to watch high-definition shows if you subscribe to HD cable, HD satellite, or purchase a separate $250 HDTV tuner to receive the free high-definition broadcasts from the major studios such as CBS, NBC, ABC, and FOX (you can check http://www.antennaweb.org/aw/Address.aspx to see if HDTV is available in your city).

TV's that have the capability to receive free off-the-air high-definition programs are called "Integrated HDTVs" and will mention an "ATSC tuner" in its specifications. With these TVs and an appropriate antenna, you'll be able to enjoy high definition programming right away. HDTVs with "CableCard" support add an additional benefit. Currently, HD cable TV subscribers need a cable box. In the future, with "CableCard" you will be able to subscribe to premium HD cable channels without a separate cable box. Integrated HDTV means one less piece of equipment to clutter your entertainment system and one less remote control to lose.

How big is too big? How small is too small?

Most people say that if the diagonal screen size is less than 4 times the distance to the viewer, the TV is too small. So, if you're 8 feet away from the TV, you'll want a TV that's at least 32 inches. 16 feet away? A 65" TV is the recommendation.

A true theater experience as defined by the Society of Motion Picture and Television Engineers is a 30-degree viewing angle. This means that at 8 feet, you'd already need 60" TV. If you wanted to meet THX recommended theater specifications, the viewing angle needs to be 36 degrees and you need to make that a 72" TV when you're sitting 8 feet away. Don't worry if you think these numbers seem enormous – they're not supposed to be practical in a home theater. Just think of this as a way to rationalize that you're saving thousands of dollars by choosing not to replicate a THX theater.

Now for the interactive part that will give you specific advice on the best TV for your needs…

Is it important for you to be able to hang your TV on the wall?
1) Yes, my next TV must have that feature (Click here to go to page 3)
2) I know it looks cool, but I can do without it (Skip ahead to page 4)




SIDEBAR: Hollywood movies processed for playback on Imax theaters have a big picture, but often have worse audio than a high-end traditional theater.

Flat panel TVs

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EDTV Plasma: $1500 to $3500; 37 to 46 inches

HDTV Plasma: $2500 to $20,000; 32 to 61 inches

"Enhanced Definition" Plasma screens (EDTV) do not offer true high-definition TV quality. Instead they offer a "DVD quality" screen resolution of 852x480. For watching DVD-movies, conventional cable or television, or playing video games, the lower resolution is not a factor. You will still be able to enjoy TV shows broadcast in high-definition, however the show will only be as sharp as a DVD. By convention, any plasma with a resolution greater than 852x480 is considered HDTV plasma. These panels include resolutions such as 852x1024, 1024x768, 1024x1024, 1280x768, and 1366x768. With a higher resolution screen, you will be able to take advantage of the additional resolution that high-definition broadcasts offer.

HDTV LCD flat panel: $500 to $10,000; 17 to 46 inches

Compared to plasma screens, LCD panels will not offer as nice of a picture or as large of a size. However, the listed price range can be misleading. While 46" LCD flat panels run close to $10,000 and 46" HDTV plasma screens are half that price, LCD technology is cheaper for smaller sizes. Generic-brand LCD TV's with HD resolutions (1280x768) at 30 inches are only $1000, significantly less than the comparable sized HD plasma. These 30” TVs from companies such as Syntax, Olevia, Maxent, Sceptre, represent the best bang for the buck when it comes to stylish TVs with an acceptable image quality. The 46" LCD panel is really only for those who can afford the very best, with a flagship 1080p resolution.

Bottom line?

LCD offers the best value if you're looking to get something in the 30-inch range or smaller. The quality is almost as good as HDTV plasma and it's much more reliable. If you're not much of a gamer and simply want a great screen for your DVDs, an EDTV Plasma is a good bet as well. If you're looking a luxury product in the 50-60 inch screen size with a $5000 to $10,000 budget, you won't find anything with more wow factor than the plasma.



SIDEBAR: Size matters.

Projection Technology

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While flat panel TVs may look great, the price premium is substantial. For the majority of people, projection technology offers the best value. Projection TVs come in two formats, front and rear projection. Front projections are like slide projectors. They offer the largest possible screen size, but are difficult to place, require a dark room and a dedicated screen (not a blank wall) for best results. Since front projectors are considered a secondary display since they do not work well in daylight, we'll focus on rear projection TVs only.

CRT RPTV; $1500 to $2500; 47 to 65-inch

CRT rear projection is the original big screen TV technology. They're big, heavy, and consume a lot of power. You can't see a thing in the daytime. The viewing angle is narrow that you won't get a good picture sitting off to the side. Over time (years), the alignment of the electron guns goes off resulting in an unfocused picture. All that said, CRT rear projection is the cheapest big screen technology out there and for the group of viewers sitting in the middle of the room with the lights turned off, it offers the best picture quality of any TV at any price. That’s right, a $2500 65” rear-projection TV will look better than a $15,000 plasma. Burn-in is something to be concerned about, but when you factor in inflation, you can still replace a CRT RPTV almost twice and still come out ahead. The real disadvantage to the CRT RPTV will always be size. Are you likely to move to a new home soon? Will it fit in your home without rearranging the furniture?

Three-chip LCD: $2500 to $7000; 42 to 70 inches

LCD rear projection takes an approach similar to the classic overhead projector. In this approach, the light from a high-intensity bulb is split into polarized red, blue, and green beams. The LCD panels can control the amount of light reaching the screen by changing the angle of polarization of the liquid crystal inside each cell. If you recall from high school physics, if the polarization is parallel, all the light goes through and when it is perpendicular, no light goes through. There is precise control over the amount of light filtered. Gray can be produced by only partially polarizing the light. When the red, green, and blue light combine, you get your full color picture.

Unlike computer LCD monitors or flat panel LCD monitors in which the individual red, green, and blue pixels are located side by side, LCD rear projection TVs are projected over each other. Combined with the use of a high-intensity discharge bulb rather than a cold-cathode fluorescent, rear projection LCD TVs offer better overall color than PC monitors.

3-chip LCD technology offers excellent color and more brightness than a CRT rear projection TV. TVs are relatively thin (~1 foot) and light, and offer wide viewing angles appropriate for a big party. Unfortunately, because LCD panels cannot completely filter out light, the color black ends up being a very dark gray. Lastly, part of the LCD panel circuitry blocks the light going through, resulting in a faint grid pattern and a picture that appears slightly soft.

Single-chip DLP

With DLP, a high-intensity light bulb illuminates a group of almost a million microscopic mirrors. Each microscopic mirror can be tilted to bounce the light toward the screen or away from it. This can happen several thousand times a second. So if you can imagine that a mirror is rapidly cycling between on (reflect the white light toward the screen) and off (angle the light away from the screen), a gray picture is produced. To get a color picture, the light passes through a rotating colored filter. Because the mirrors of the DLP device move so quickly, alternating monochrome images end up producing a normal color picture. That is, a red square immediately followed by a blue square in a thousandth of a second will appear purple to our eyes.

DLP offers better contrast and brightness than LCD. Since the circuitry for controlling the microscopic mirrors are not in the path of the light, images also appear sharper than LCD TVs. Unfortunately, the rotating color wheel cannot provide the same color purity as a three-chip design. In particular, black and white scenes or fast moving action can produce the appearance of rainbows at the edge. Imagine if the purple square was moving so fast that the red and blue did not perfectly overlap, you'd end up seeing a purple rectangle with a blue and red border. The majority of individuals are not sensitive enough to notice the color errors produced by the spinning wheel and this isn't a problem. However, others will complain of a headache after watching a movie on a single-chip DLP screen. To minimize the rainbow effect, some high-end DLP TVs spin the wheel at faster rates than their budget competitors. In the next 5 years, we may begin to see affordable three-chip DLP rear projection TVs which will alleviate this problem but until then, this remains an Achilles heel of the technology.

1 Mpixel single-chip LCoS: $3500 to $4000; 55 to 62 inches

1 Mpixel 3-chip: $3500 to $4500; 52 to 61 inches

2 Mpixel 3-chip LCoS: $8000 to $20000; 60 to 82 inches;

LCoS, or "Liquid crystal on silicon" offers a glimpse at the future. In this variant of LCD technology, light is reflected off the colored LCD rather than filtered through it. This can offer even superior brightness and contrast to DLP. Like single-chip DLP, single chip LCoS (marketed by Philips) uses a spinning color wheel. This means that the "rainbow" artifacts can also be a problem.

However, the majority of LCoS designs (Sony SXRD, JVC D-ILA, Mitsubishi Alpha, and the stillborn Sears Veos) are three chip designs and therefore offer the same color offered by three-chip LCD. Moreover, whereas conventional DLP and LCD technology are limited to approximately one megapixel of resolution, the Sony SXRD, Mitsubishi Alpha, and Sears Veos LCoS products offer 2 megapixels of resolution.

With the contrast and brightness of DLP, the color of three-chip LCD, and unparalleled resolution, HDTVs using 1920x1080 LCoS technology truly offer the best of all worlds. The main disadvantage is price. Very few people can afford the technology and DLP and LCD rear projection TVs offer a better overall value.

Final thoughts

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Bottom line?

For most people, DLP and LCD based technology offers the best balance of performance, price, and reliability. Neither technology is inherently superior to the other so you will need to do some shopping. DLP TV's look better in daylight, however the rainbow effects can be problematic for those sensitive to it. When you visit your retailer, ask them to show you a DLP television and to demo an action movie or music video. While watching, try to see if you see rainbow artifacts during fast movement or black and white scenes. If you see rainbows, it’s not worth buying a DLP TV no matter how cheap it is – you’ll end up with a headache at the end of the movie.

If you don’t see any rainbows, you’re in great shape. That means that DLP is a potential contender for you. The next step will be to ask your retailer to take a look at an LCD rear projection TV. Here, you’ll want to compare the color between the two TVs. At a quality retailer, the TVs should be calibrated (usually a “Pro” configuration and Warm color temperature). Since this isn’t always the case, when comparing color, try not to look at which is more intense but which one seems to have the most natural gradation and tone. See if can appreciate the extra color resolution of an LCD RPTV.

If the answer is no, you’ll be sold on DLP TVs and won’t need to shop for any other type of TV. If the color is appreciably better on the LCD rear projection TVs, your final step is to compare the TVs from the distance you will be viewing the TV at home. You’ll be looking for the “sharpness” of the screens and will try to see if you notice the “screen door” effect. If you don’t see the screen door effect, then your best TV will be an LCD RPTV.