Tech Talk-Buying a new TV

By Kayla Jean Woods
kayla@liveittexas.com

Are you considering buying a new TV? Some experts believe March is the best time to buy one because retailers want to get rid of inventory that didn’s sale during their pre-Super Bowl sales in February. Prices are low so they can make room for new inventory.
March is when the new models ship out, so if you don’t want an older model you may want to wait until later in the month or early April.
Which kind of TV should you buy? What is the difference between LED and LCD?
An LED TV is an LCD TV even though they are marketed as different types of TVs. An LED TV is actually an LED-back lit LCD TV, but that is a really long name, so most people just shorten it to LED which can cause confusion.
Both types of TVs use a liquid crystal display (LCD) panel to control where light is displayed on the screen. These panels are usually made up of two sheets of polarizing material with a liquid crystal solution between them.
When an electric current passes through the liquid it causes the crystals to align so that light can or can’t pass through.
Since both LED and LCD TVs use LCD technology, what is the difference? The answer is backlighting. Regular LCD TVs use cold cathode fluorescent lamps (CCFLs) to provide backlighting. LED TVs use smaller, more effcient light emitting diodes (LEDs) to illuminate the screen which gives them a few advantages of regular LCDs.
The first advantage is that LEDs are considerably smaller than CCFL tubes, which means the TVs can be made thinner. Today, most LED TVs measure less than an inch in thickness.
LEDs also use less power than CCFLs, but the most important difference is a feature called local dimming.
Local dimming is a selective lighting technique that allows for deeper blacks and a better overall picture.
With CCFL backlighting, the fluorescent tubes must light the entire screen evenly, so designers can not vary the backlighting intensity in different parts of the screen.
Even if you wanted to have only one white pixel lit on an all black screen, the backlight has to be on at full brightness.
LED TVs, on the other hand, can make use of local dimming. This technique can control the output of LEDs so that they can be dimmed or turned off completely.
This makes for better black levels and contrast. If you have the black screen with one white pixel, only the one pixel will be lit and the rest of the screen with be a dark black. With the LCD TV the black would appear to be washed out and brighter.

Read more in the March/April issue of LiveIt magazine.

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