LCD TVs – What You Should Know

Television imaging technology has come a long way since the 1931 when the first commercially practical cathode ray tube (CRT) was made for television. Today liquid crystal display (LCD) TVs are becoming the dominant image technology. If you are thinking about buying a new LCD TV what should you know?

Plasma and LCD TVs – What's the difference?

You will soon learn that there are two types of flat screen, high definition television (HDTV) – Plasma and LCD. When you watch a movie on either Plasma or LCD, you are looking at possibly 2 million tiny pixels as they change color and form a moving image.

In Plasma TVs, each pixel cell is like a tiny neon light bulb (containing plasma), switching on and off rapidly, contributing its part to the overall image you see on the screen.

LCD TVs are based on an entirely different principle. A tiny LCD pixel requires a separate light source in back of the pixel. That lighting is called backlighting. The LCD pixel acts like a tiny shutter, reducing or blocking the light or allowing it to shine through as needed to form its small part of the big picture.

Compared to LCD TVs, plasma TVs are generally brighter with higher contrast. They display images with less blur due to faster refresh rates and the inherent properties of the plasma pixels. However, Plasma TVs are generally more expensive, heavier, more fragile, require more electricity, and are more likely to have problems with burn-in (from images displayed too long) and burn-out (from long, extended use). The quality of LCD TVs has been rapidly improving due to advances in LCD TV design and manufacturing. Some manufacturers have discontinued production of plasma HDTVs and concentrated on LCD models.

Backlighting

Backlighting used in LCD TVs can be by CCFL (cold cathode fluorescent lamp) or LED (light emitting diode) LED backlighting produces more contrast compared to CCFL. Newer, high quality LCD TVs use LED backlighting.

LED backlighting can be either edge-lit or full-array. Edge lighting uses small LED lights arranged around the rim or perimeter of the TV behind the screen, along with a diffusion surface to distribute light as evenly as possible throughout the screen image. Full-array backlighting uses small LED lights distributed, not along the edge, but throughout the back of the screen. Improvements to full array backlighting include Local Dimming, where portions of the array are controlled separately.

In Local Dimming, each group of LEDs lights only a small part (zone) of the screen allowing finer-grain control of blacks and colors. The larger the number of dimming zones, the better the result. (Another, more expensive, dimming technology using colored LED lights produces even more stunning results.)

Sharpness and smooth motion

For the sharpest image in a number of different formats, go for 1080p (1920×1080 pixels). That's over 2 million pixels. To view Blu-Ray and HD DVDs in native full resolution, you need 1080p. You also need 1080p for best results with gaming and computer applications. Look for compatibility with other formats – 1080i, 720P, 480P, 480i.

Fast action movies call for blur-free images. With 240 Hz you are viewing 240 scenes per second. This ought to make for blur-free motion, but there are technical complications. Movies are generally shot at 24 frames per second, video at different rates. Engineers and manufacturers have come up with a number of methods to blend these different together and to produce a more blur-free motion picture at blazing fast 240 Hz refresh rates.

Vizio, a highly-rated up-and-coming HDTV, uses its own approach called "Smooth Motion" – a 240Hz SPS Smooth Motion technology that delivers 240 scenes per second producing enhanced frame rate and delivering sharper clarity of fast action scenes for blur free images.

Final suggestion

Because an LCD is complex electronics, check manufacturers' warranties. Purchasing an Extended Warranty is not a bad idea. Although manufacturers are improving the quality of their products and reducing manufacturing defects, the possibility remains (however remote) that the one you get will be faulty, or will develop a problem down the road.


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