Benefits of flat-panel TVs | Flat-panel features to consider
A quick comparison of LCD, LED, OLED and plasma TVs
Flat-panel TV technologies: LCD | LED | Plasma | OLED
More information

 

A flat-panel TV is a television set that uses one of several different technologies for display in a flat, thin format. Most new televisions are flat-panel models; older TV sets, which use cathode ray tubes (CRT), are much bulkier. CRT televisions are still available but increasingly uncommon because of the advantages of flat-panel displays.

Plasma and LCD are the two most common technologies used for flat-panel displays. Variations on those include LED and 3-D TV. OLED, an emerging technology, is distinct from plasma and LCD; another separate technology, rear-projection, is less commonly used.

Benefits of flat-panel over CRT:
Because the screens of flat-panel TVs are not curved, as they are on CRT sets, the display is not distorted at the edges. Flat screens are also less prone to reflection and viewable from a wider angle than curved displays. The technologies used make it possible for flat-panel models to be much lighter than CRT TVs, which means that larger sizes are feasible. Because they're light and thin, flat-panels can also be wall-mounted. The 16:9 aspect ratio (basically, the proportion of width to height) of most flat-panel TVs optimizes them for watching movies.

General flat-panel TV features to consider:

Bear in mind that you probably want your new flat-panel TV to last for years, so think of future needs as well as present ones.You may not be setting up a home theater right now, for example, but it could be a consideration in the not-too distant future. Also, as television and Web continue to converge, you're likely to want that capacity in the future. Likewise the capacity for 3-D -- it might not seem essential now, but within a few years it could be something that you wish you'd considered. 

Here are a few specific things to think about when you're shopping for a flat-panel TV:

• Size – Size-wise, you're going to want the biggest display that's feasible for your viewing space and budget, while also ensuring that you get the features and quality that you want. These TVs are typically larger than CRT models, although some types are available in very small sizes. You need to take into account the available space and how far you'll be from the screen. The general rule is that you want to sit no closer than the diagonal measurement of the TV multiplied by 1.5 and no farther than the diagonal measurement multiplied by 2. If you want the TV to fit into a confined space, such as an entertainment armoire, bear in mind that the width of a flat-panel TV is usually 1-3 inches less than the diagonal measurement (which is the size specified). 

  Approximate viewing ranges for various display sizes:

  Display size	Minimum	Maximum
  37 inches	4.6 feet	6.2 feet
  40 inches	5.0 feet	6.7 feet
  42 inches	5.3 feet	7.0 feet
  46 inches	5.8 feet	7.7 feet
  52 inches	6.5 feet	8.6 feet
  58 inches	7.3 feet	9.7 feet
  65 inches	8.2 feet	10.8 feet
  70 inches	8.8 feet	11.7 feet

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• Closer distances are better for watching high-definition content and farther distances are better for lower-quality programming, such as analog cable.
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• Contrast ratio -- the ratio of the luminance of the brightest white to the darkest black that the display is capable of. A higher contrast ratio means a sharper picture. A ratio of 500:1 is the bare minimum -- the higher the better.
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• Resolution - the number of pixels (individual points of color) on a display. Resolution is expressed in terms of the number of pixels on the horizontal axis and the number on the vertical axis. A larger display needs a higher resolution. A resolution that looks fine on a smaller display is not as sharp on a larger one because the same number of pixels are being spread out over a larger area. At a minimum, HDTVs support 1280x720 resolution; most support 1366x768. Some newer HDTV-compatible displays support 1920x1080 pixels.
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• Refresh rate (also known as the response rate) - the number of times a display is repainted per second. The refresh rate is expressed in hertz (hz). A higher refresh rate means a smoother display that is clearer and free of motion blur. The original standard for HDTV was 60hz. Displays with 120hz or higher refresh rates offer a better viewing experience; the refresh rate may also be integrated with video processing software that further improves the display.
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• Wi-Fi – are you going to want to connect wirelessly to your home network? If not now, you probably will want to in the future.
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• Dot pitch -- the amount of space between adjacent pixels of the same color. The closer pixels of the same color are, the sharper the picture will be. For both plasma and LCD TVs, dot pitch should be approximately 0.25 mm to 0.30 mm.
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• Optimization for Internet connectivity – separate services, such as Hulu and Netflix, are sometimes built in. Some other products, such as Google TV, enable fully integrated Web browsing and search into the television.
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• 3-D, which enables a display that appears to have depth as well as height and width. Any of the main types of flat-panel TVs are capable of including 3-D as a feature. Typically, users have to wear special glasses for the 3-D content. Autosteroscopic (auto 3-D) TVs are becoming available: 3-D TVs with screen-based technology to take the place of 3-D glasses.
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• Ease of use and availability of on-screen help.
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• Energy use. As a rule, for example, a plasma TV uses twice as much electricity as a similarly-sized LCD model.
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• The screen's finish – a gloss finish will reflect more in a bright environment.
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• Black-level performance -- the depth of black that the display is capable of. Deeper black makes for better contrast.
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• USB ports and memory card slots, so you can display pictures and play other content.
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• Whether there are enough HDMI inputs, as well as inputs for other devices you might want to connect, such as a computer.

 

 

Types of flat-panel TVs: 

(Click the links to see our full definitions for the terms.)

LCD TV, which is based on a liquid crystal display (LCD). LCD displays work on the principle of blocking light rather than emitting it, which enables them to consume much less power than either CRT or plasma-based displays.  

Plasma TV -- In a plasma display, each pixel on the screen is illuminated by a tiny bit of plasma (which is charged gas) and the whole is encased between two thin sheets of glass. Plasma TVs are generally thought to offer a superior picture to that of LCD displays, especially for dark-room viewing, but the gap between the two is narrowing. 

LED TV, which is really just an LCD display technology based on light-emitting diodes (LEDs) backlighting the display instead of the cold cathode fluorescent lights (CCFLs) used in standard LCD televisions. The correct name for LED TV is LED-backlight LCD television. LEDs enable more precise lighting than fluorescent lighting and lower power use. 

OLED TV, which exploits the properties of organic light-emitting diodes (OLED). OLED TV is a different technology than LED TV. OLED displays don't require backlighting, which means that they use much less power than most display technologies and can be extremely thin.

                                                                         

Learn more:

See our Guide to Digital TV.

See a comprehensive report on flat-panel TVs on CNET reviews. 

Practical Home Theater Guide provides an in-depth comparison of plasma vs. LCD.

See a guide to buying 3-D TVs. 

At a Glance: Comparing LCD, LED, OLED and Plasma TVs

Flat-panel TV technology	Pros	Cons	Features to look for
LCD	better bright room performance lower energy consumption not prone to burn-in	can have slower response times can suffer motion blur viewing angle not as wide as plasma	active matrix display anti-motion blur 500:1 contrast ratio at a bare minimum -- the higher, the better
Plasma	better dark room performance wide viewing angles superior color accuracy faster refresh rates	higher energy use than LCD can be prone to burn-in slightly heavier than LCD TV of the same size  black-level performance may degrade over time	anti-burn in protection anti-glare screen treatment  longevity of black-level performance
LED TV	faster refresh rates than other LCD TVs RGB: better contrast ratio than other LCD TVs RGB: truer blacks and whites (See also: LCD TV pros)	more expensive than plasma TVs and other LCD TVs depending on the specific technology, may not deliver a higher quality picture than other LCD TVs	RGB LED display for picture quality, or edge-lit LED, for thinnest display
OLED TV	best picture quality thinnest display extremely high contrast ratio very low power requirements very wide viewing angle	very expensive not widely available	The vast majority of consumers will not be shopping for OLED TVs in the near future.
All Flat-panel TVs	wider viewing angles lighter no picture distortion at the edge less prone to reflection widescreen aspect ratio	more expensive than CRT TVs	HDTV-readiness refresh rate of 120hz or higher computer / Wi-Fi connectivity HDMI input matte screen 1366x768 or higher resolution dot pitch of 0.25 mm to 0.30 mm

22 Dec 2010