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Buying a TV 101

Plasma vs. LCD - Plasma TV's - LCD TV's - DLP TV's - HDTV - 720p, 1080i or 1080p - Size & Placement

Plasma vs. LCD

You're really selecting between competing technologies, both of which achieve similar features, bright, crystal-clear images, super color-filled pictures) and come in similar packages, a narrow flat screen casing. Price and size are two previous considerations that are rapidly becoming non-issues.

The decision is complicated by the fact that both LCD and plasma technologies have been working on their technological shortcomings, so there isn't a lot to choose between them anymore. The best way to begin is deciding where you plan to put the TV in your home and what you'll be watching. If your TV will reside in the living room with a lot of ambient light, LCD -- which has a brighter screen -- is a better choice. For darker locations such as basements and media rooms, plasma, which has a diminishing edge in depth of colour, is the suggested technology. If you watch lots of sports, plasma, with its fast screen-refresh rate, has historically had the edge, but LCD has narrowed that gap substantially.

If having a thin flat screen is not a priority there is a third option, DLP, (Digital Light Processing), which are still less expensive than plasma or LCD's but the gap is narrowing.

Plasma TV's

Plasma displays have higher resolution than most 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, a plasma display with a 1366 x 768 native resolution can display images from 1080i and 720p HDTV resolution, as well as 480i and 480p DVD video signals.

Plasma screens have no scan lines due to the fact that each and every pixel cell has its own transistor electrode. creating 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 analog video signals. Plasma displays illuminate all pixels evenly across the screen. This gives plasma displays their "smooth" appearance, and ultimately a more accurate picture.

Plasma televisions have a widescreen 16:9 aspect ratio, which was originally designed to match the natural field of view of the human eye. Of course you're familiar with the wide screen aspect from watching movies in the theater—and a widescreen plasma TV allows you to watch movies in the format the director intended. The 16:9 aspect ratio is also the chosen format for HDTV content, whether it's broadcast over the air or through digital cable or satellite TV. All plasma screens can show original 4:3 format with bars (either black or gray) on the sides of the image, but there can be some variation among plasma screens in how well they convert a 4:3 image to the widescreen monitor.

Today's top-of-the-line plasma televisions display billions of colors, resulting in smooth gradations between even subtle shades, and an overall picture quality that is extremely realistic and lifelike. Plasma sets in general boast the best color reproduction of any flat panel TV technology, and advances are made with each new model year, for color accuracy.

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LCD TV's

Liquid crystal displays use twisted nematic (TN) liquid crystal. It has a naturally twisted crystalline structure, a particular feature is that it reacts to electric currents in predictable ways by untwisting to varying degrees depending on the voltage of the current to which it is exposed. Hence the "liquid" part of the crystal's name.

LCD monitors work by blocking light, sandwiching a solution of TN liquid crystals between two perpendicularly aligned panes of polarized glass, it becomes possible to manipulate the intensity of light as it passes through this crystalline matrix and out the glass panel at the other end. Depending on the voltage of the electrical charge running through them, liquid crystals will untwist so that the intensity of light able to pass through the second polarized pane is affected.

The light source in an LCD display is a florescent bulb, which emits white light through a polarized glass pane behind the liquid crystal solution. Since all wavelengths can pass through, the full spectrum of light can be manipulated to create the desired color. To achieve a full color pallet on your LCD display, each pixel is divided into three subpixels-red, green, and blue-that work in conjunction to determine the LCD pixel's overall hue. These subpixels are created by subtracting certain wavelengths, and the corresponding colors using filters. By exploiting a combination of red, green, and blue subpixels of various intensities (or gray scales), a single pixel triad can reproduce approximately 16.8 million colors.

LCD TVs generally come with tuners and speakers already built in, so they're more or less plug-and-play devices. They are ideal for smaller applications, where space is at a premium (like bedrooms and small living rooms) or where clutter is inconvenient.

LCDs have none of those annoying scan lines that conventional sets do. This owes to the fact that each subpixel has its own transistor electrode, which creates smooth, evenly lit images across the entire surface of the display. It also enables these displays to reproduce images that are saturated with color, 256 shades of red x 256 shades of green x 256 shades of blue equalling 16.8 million different colors.

LCD displays come either with a 16:9 aspect ratio, the proper one for viewing HDTV and for watching DVDs, or with a 4:3 aspect ratio, the norm for most broadcast television shows. When displaying a "normal" or 4:3 picture image from satellite, VCR, or cable TV, the image can be viewed in a number of ways, in its original format (with black or gray bars on the sides of the screen), or in "full" mode (where the image is converted or "stretched" using specially designed algorithms to reduce the visible stretch marks as much as possible). The quality of the picture produced under such circumstances depends largely on the quality of the television with which you scale-up 4:3 pictures or scale-down 16:9 ones.

It's also a computer monitor. In fact, it can accept any video format. LCD displays typically include inputs for (a) composite video, (b) S-video and component video, and (c) one or more RGB inputs from a computer. Because of the high resolution of LCDs, text and graphics look especially sharp when viewed on them, which makes them the best solution for displaying data and web-based content.

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DLP TV's

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 or away from 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.

With DLPs, the vertical positioning of the display should be very close to eye level. The vertical viewing angle is far less protracted than its side-to-side viewing angle.

DLP manufacturers list the backlight bulb hours at around 80,000 hours, this bulb can be replaced for as little as $200 in some cases.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.

DLPs generally come with NTSC tuners and speakers already built-in to them, for standard-television watching. Some of the newer DLP models also include ATSC tuners for high-definition reception.

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HDTV

High-Definition Television is a new type of television that provides much better resolution than current televisions based on the NTSC standard. HDTV is a digital TV broadcasting format where the broadcast transmits widescreen pictures with more detail and quality than found in a standard analog television, or other digital television formats. HDTV is a type of Digital Television (DTV) broadcast, and is considered to be the best quality DTV format available. HDTV requires an HDTV tuner to view and the most detailed HDTV format is 1080i.

When you start shopping, keep in mind that HDTV requires three parts:
• A source, such as a local, cable or satellite HDTV station

• A way to receive the signal, like an antenna, cable or satellite service .

- An antenna, depending on your location relative to the stations you want to watch, a set of rabbit ears might do, but you might need a rooftop or attic antenna.
- Cable, digital cable is not the same as HDTV, you'll need to check with your provider to determine which packages include HDTV stations. You'll also either need a set-top cable box or a CableCARD™ to allow your television to receive and decode the cable signal.
- Satellite service, as with cable, check with your provider to determine which plans and stations use HDTV signals.

• An HDTV set

You can choose:
- An integrated HDTV, which has a digital tuner, also known as an ATSC tuner, built in.

- An HDTV-ready set, which does not have an HDTV tuner. HDTV-ready sets often have NTSC tuners, so you can still watch analog TV with them. This is an option if you want to have HDTV capabilities later on but aren't ready for the financial commitment yet.

Five Ways to Optimize Your HDTV Experience

- Must read article from Macworld on setting up a HDTV for the best viewing experience.

720p, 1080i, or 1080p

There are two main flavors of high definition TV,1080i (the i is for interlaced) and 720p (p for progressive). 1080i offers the most pixels, with a matrix of 1920x1080 pixels, while 720p has fewer pixels at 1280x720 pixels. However, the difference is made up with the frame rate, which is only 30 frames per second with 1080i, but is double that with 720p, at 60 frames per second. The total pixels displayed per second is actually very similar, with 720p offering 55 million pixels per second, while 1080 is slightly higher at 62 million pixels per second.
What does all that mean?  It all depends on the type of TV you watch. 720p is better at showing pictures with plenty of motion, since the higher frame rate helps smooth any quick motion on the screen - this is better for sports or action movies. 1080i offers more detail, which is for movies with lots of images or panoramas.
The best of all is the 1080p option. It offers the best of both worlds, 60 frames per second at 1920 x 1080 pixels. The total bandwidth is 124 million pixels per second, double that of 1080i. It can display any HDTV signal without any downconverting.  720p signals are upconverted, while 1080i signals only require some gently "de-interlacing" to work properly. 1080p is the perferred option its backwards compatible with all old formats, and is ready for upcoming high definition discs.

Size & Placement

You should go with the largest screen your room, viewing distance, and budget will accommodate. Sitting the right distance from your TV is an important part of optimizing the viewing experience, too far away diminishes the overall impact. too close is also less than ideal. An indication that you're sitting too close to a screen is if you find yourself distracted by the screen's tiny "dots" (pixels), or for CRT-based TVs, horizontal scan lines. With today's high-definition TVs, you can sit closer than you could with older analog TVs.

If you're not sure which screen size is best for your room size, check these guidelines.
Screen Size Viewing Distance
30" 3' - 6 '
34" 4' - 7'
42" 5' - 9'
50" 6' - 11'
56" 7' - 12'
62" 8' - 13'
70" 9' - 15'

Viewing angle is another factor that affects a TV's performance. Your TV will look its best when viewed from straight ahead, at a height where your eyes are level with the middle of the screen.

The lighting conditions in your room are also important; some screen types perform better than others when it comes to dealing with room light. Most plasma, LCD's and DLP models do a fine job in rooms with regular indoor lighting, front projectors generally require a darkened room.
Flat screen TVs are less susceptible to reflected glare than TVs with a rounded screen. Here are some more suggestions for optimizing your room's lighting:
• Windows that let in bright sunlight should have easily adjustable blinds and/or curtains.
• Light from a window behind the TV makes it difficult for your eyes to adjust to the very different brightness of the television.
• With just about any TV (except a front projector), it's best to have a little bit of light shining on the wall behind it. If you watch in total darkness, the TV's range of brightness can cause eyestrain.
• If you're using a plasma or LCD flat-panel TV, a little bit of controlled background lighting can improve picture quality, background light helps give the black portions of the picture a deeper, darker look.


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