LCD TVs vs Plasma TVs

As long as we can remember people have debated; what is the best HDTV technology? Sure every technology has it downsides, but when we are talking about picture quality above all else, which is the best? In the past people would debate LCD vs Plasma which really left us scratching our head because at the time the smallest Plasma was 37″ and the largest LCD was 32″. Well those times are over and many LCDs and Plasmas are the same size — well almost the same size, while Plasmas are 37″, 42″, 50″ and 60″ LCDs are 32″, 40″, 42″, 46″, 52″ and a host of other sizes. There is little doubt that LCD has more sizes available and arguably more detail, it also costs more, but we aren’t talking about size here, we’re talking about picture quality. Plasmas have been able to boast better blacks and better colors than LCD, but in recent years LCD technology has made leaps and bounds in this area as well as the new 120Hz models, which begs the question do Plasmas still have better blacks and colors than LCDs? Sure they are susceptible to burn in and many are only 720p vs 1080p, but most ISF engineers agree that accurate colors and black are more important than resolution.

Choosing The Proper Size Panel

In the age of High Definition TV size matters most. What many shoppers and salesmen don’t realize, buying a screen that is too small or sitting too far away from the display will rob you from seeing all the high definition the set has to offer, thereby wasting your money. HDTV provides a more immersive viewing experience than old style 4:3 standard definition TV, as well more picture detail than you have ever seen on a home display. In order to fully resolve all the detail within HDTV, you must sit in the optimum viewing range. Sit further and your eyes will not be able discern all the detail within the image. There are three levels of resolution for flat TVs. The first level is not HDTV; it is called Enhanced Definition at 480 vertical lines. The two classes of HDTV grade displays are 720p/768p with the display showing either 720 lines (or 768 lines) of resolution from top to bottom and 1080 (i or p), the highest quality HDTV display, with 1080 lines of resolution. For ED sets you can sit as far as 3.4 times the screen diagonal to see all detail. This means up to 142.8 inches (just under 12 feet) from an ED (480p) 42” set. Using the same size screen a 720p/768p you need to be at a viewing distance of at 2.3 times the screen size or closer, which is equal to 96.6 inches or eight feet. With a 1080 (i or p) 42inch set you should at no more than 1.55 times the screen size or 65.1 inches (just under 5½ ft.) to distinguish ever pixel within the image.

How Plasma Works

Plasma is a flat, lightweight surface covered with millions of tiny glass bubbles. Each bubble contains a gas-like substance, the plasma, and has a phosphor coating. Think of the bubbles as the pixels.

Now, think of each pixel-bubble as having three sub-pixels - one red, one green, one blue. When it is time to display an image signal (RGB or video), a digitally controlled electric current flows through the flat screen, causing the plasma inside designated bubbles to give off ultraviolet rays. This light in turn causes the phosphor coatings to glow the appropriate color.

Millions of RGB bubbles glow and dim to make a rich, vivid image on your plasma TV.

How LCD TVs Work

What Is LCD Technology?

Like popular LCD monitors you commonly see used with computers, LCD TVs have a slim design and a flat viewing surface, but have been fine tuned for video display. Recent advances in flat panel LCD technology now allow for larger screens, wider viewing angles, and higher-quality video images. LCD TVs are also competition for trendy-but-heavy, plasma display technology. They are several times lighter than comparably sized plasmas, and are far more durable.

How do LCD TV’s work?

Two sheets of polarized transparent material, one with a special polymer coating that holds liquid crystals, are adhered together. Electric current is passed through individual crystals, which interpret the information from the broadcast signal to allow or disallow light through them to create an image. The crystals themselves do not produce light, so the technology is “non-emissive” and therefore does not give off radiation like an older television does. Fluorescent tubes housed behind the transparent material illuminate the image. They require less power to operate than CRT and plasma televisions which require powering hundreds of electrodes to stimulate the phosphorous.

Set-top Boxes and External Tuners

In order to watch regular television on your LCD TV or plasma television it must have a tuner to receive the broadcast signal. Tuners can either be built-in to your LCD TV or plasma television, or they can be external, in the form of an HDTV receiver, cable or satellite box, VCR, or another tuning device.

In many cases, an LCD TV or plasma television comes with an external set-top box. Set-top boxes include the tuner and connections necessary to connect to other devices such as a DVD player or VCR.

Comb Filtres

Why do some displays need a “comb filter”?

Composite video signals are the most common but lowest-quality video signals available today. You could call it the lowest common denominator of video connectivity. Due to limited bandwidth, composite video signals luminance or brightness (Y), and chrominance, or color (C), are designed to overlap. This overlap can make it difficult for TVs to differentiate the Y information from the C information, which sometimes creates artifacts of fuzziness in your TV’s image.

Comb filters are designed to clean up any fuzziness or artifacts brought in by the composite signal. Comb filters use various methods to clean up artifacts and therefore vary in effectiveness.

Analog Filters Found on less expensive TV sets, usually on smaller screens (25 inches or less). Types include CCD (charge coupled device) and glass. These are less common today.

2-Line Digital Separates Y and C signals while processing two consecutive horizontal scan lines and makes adjustments to lessen the effects of signal overlap.

3-Line Digital Separates Y and C signals while processing three consecutive horizontal scan lines and makes adjustments to lessen effects of color bleed and dot crawl.

3-D Digital Analyzes three consecutive scan lines as well as pre-analyzing previous and subsequent video fields to improve overall color accuracy and stability of image. It also effectively diminishes issues of color bleed and dot crawl.

NOTE — A TV’s comb filter is bypassed when S-Video or component video is used as the input signal, because S-Video and component video signals are comprised of separate Y and C elements already.

LCD TVs and Response Time

Response time is basically the amount of time it takes for a liquid crystal cell to go from active (black) to inactive (white) and back to active (black) again. It is measured in milliseconds or (ms). Lower numbers mean faster transitions (eg. 16 ms is faster than 25 ms.) and therefore less visible image artifacts.

LCD TV manufacturers have been steadily improving response times as the demand for fast moving full motion video has increased. A good response time starts at around 25-30 ms. Some newer model LCD TVs have response times as fast as 16 ms.

LCD TV Viewing Angles

LCD displays were originally designed as computer monitors, which were intended primarily for “straight-on” viewing at arms length. However, with the migration of LCDs into home settings, new ways of viewing are being considered.

At home, people watch TV from a variety of angles (from side-to-side and above-or-below) and distances. New LCD TVs have greatly improved to accommodate home viewers. Current LCD TVs have viewing angles of as high as 175° horizontally and 160° vertically.

Brightness and contrast levels can vary on an LCD TV depending on where you stand in relation to the center point of the screen, however the degree of “fall-off” is far less than it used to be.

Viewing Angles At-A-Glance

-Originally designed for single-person viewing, LCD TVs used to have viewing angles as low as 40°.
-New LCD TVs have wider viewing angles than current plasmaTVs – some as high as 175°.
-Because of the flat design of LCD TVs, more usable viewing space can be created in a room.

Technical comparison

Screen Size

Plasma

Screen sizes range from 32 inches to 63 inches. Larger plasmas, like a 103 inch unit from Panasonic, are in production, but are still prohibitively expensive for consumer use.

LCD

Sizes range from 13 inches to 45 inches. As with plasma, there are larger LCD TVs made, like a 100 inch display recently released by LG, but they are not readily available or affordable at the consumer level

Conclusion

Plasma TVs are the current size champions, particularly when comparing TVs that consumers can easily purchase. LCDs are catching up in size with their developing technology, however, and may surpass Plasmas in the near future. This may be due to difficulties in producing glass large enough for larger plasmas.

Viewing Angle

Plasma

Up to 160°

LCD

Up to 175°

Conclusion

LCD TVs have the advantage here, but by a small margin. Your viewing experience is not going to be ideal at 160 or 175 degree angles. LCD TVs used to have a problem in this area, primarily because LCDs were originally used as single person computer monitors.

Screen Refresh Rates

Plasma

Plasma displays refresh and handle rapid movements in video about as well as CRT televisions.

LCD

LCD TVs were originally designed for data display, and not video. Therefore refresh rates had to be improved. LCD TVs with refresh rates below 16 ms or lower (5-15 ms) show very few noticeable artifacts. LCD TVs are now available with refresh rates as low as 5ms.

Conclusion

Slight edge to plasma technology.

Burn-in or Stuck Pixels

Plasma

Plasma TVs can suffer from burn-in produced by static images. After extended periods, stationary images “burn in” and produce an after-image ghost which remains permanently on the screen. With technologies such as ‘pixel orbitor,’ new plasma TVs have addressed burn-in and significantly reduced the issues of older models.

LCD

LCD TVs do not suffer from burn-in, but can have a “retained pixel charge” which may also produce ghosting. Stuck pixels are also possible with an LCD display.

Conclusion

With the latest plasma technology, this is less of an issue than ever before. “Pixel orbitor,” for example, is one method of reducing burn in used by plasma manufacturers. It requires no additional programing from the end user as some older burn-in prevention techniques did. If you plan to use a plasma for gaming, some games with permanent ‘dashboards’ may still cause some burn-in. Check user-manuals for available solutions by model.

Product Life-span

Plasma

Plasma TVs have a reported half life of 30,000 to 60,000 hours. Half-life is the time it takes the lamp to fade to half its original brightness.

LCD

LCD TVs also have replaceable backlights, but the expense of replacing one when the time comes may be greater than simply replacing the entire TV

Conclusion

Both Plasma and LCD technology should more than adequately satisfy most consumers. The average CRT TV (the kind most of us have at home) has a half-life of around 25,000 hours. If the average American household watches an average of four to six hours of television a day, even a 30,000 hour lamp would give you over 16 years of use. By then you’ll be enjoying your new ‘Holodeck.’

Weight

Plasma

Plasma displays are fairly heavy, and may need additional supports to be mounted onto a wall.

LCD

LCD TVs weigh less than comparably sized plasma TVs.

Conclusion

LCD TVs are considerably lighter, more portable, and cheaper to ship.

Durability

Plasma

Plasmas are very fragile making them tricky to ship and install. Unlike the commercials where plasmas are mounted on the ceiling, plasmas are best installed by a professional, and should be installed on a wall that can bear a good deal of weight.

LCD

Much more durable than plasmas. End users can easily mount an LCD TV themselves if desired.

Conclusion

LCD TVs are far less fragile than plasmas.

Shipping

Plasma

Due to their fragile nature, plasma TVs need to be shipped by specialty carriers. Overnight or fast delivery options are not recommended. Special shipping methods and their heavier weight add to higher shipping costs.

LCD

Shipping LCD TVs is not difficult, and is not as expensive as shipping plasma displays

Conclusion

LCD TVs are lighter and far less fragile than plasma displays making shipping easier and less expensive.

Installation

Plasma

Plasmas are heavier, use more power, and run hotter than LCD TVs, and therefore require more planning when mounting them. Plasmas are generally best installed by professionals.

LCD

End users can easily install LCD TVs themselves, or can use them just as they use a traditional TV using a stand.

Conclusion

LCD TVs are much easier to install than plasma TVs.

Brightness/Contrast

Plasma

Plasma TVs report higher brightness and contrast levels than LCDs. Under ideal conditions (no ambient light) this is a true advantage of plasma technology, because LCD TVs are backlit and therefore light must be blocked to create blacks. Plasmas have individual pixels that either on or off, creating deeper blacks and better contrast.

LCD

LCD TVs can often look better in ‘real-world’ situations. Plasmas are made with a special glass surface that can reflect light, which dulls the brightness and contrast of the image. LCD TVs reflect very little light, allowing them to maintain levels in well-lit rooms.

Conclusion

Both LCD and plasma TVs will meet the brightness expectations of most consumers. However, in ‘real world’ situations with ambient light, LCD TVs will generally look a little brighter.

Performance at High Altitude

Plasma

High altitudes can affect the performance of plasma displays because the gas held inside each pixel is stressed, and has to work harder to perform. Some manufacturers make plasmas that are specifically designed for high-altitudes, but they may be priced higher than standard models.

LCD

LCD TVs are not affected by high altitudes.

Conclusion

LCD TVs

Summary

Hopefully, this essential guide to LCD vs Plasma screens has made things a bit clearer. Of course, the type of screen you buy is dependent on the function. Smaller LCD TVs are more suited if they mounted in the bedroom, office or kitchen, whereas, larger screens such as large LCDs and plasmas will suit a living room destined for the ultimate home cinema set up

Source: flattvpeople ezinearticles plasma

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