Slim HDTV Models
April 20th, 2010 by Rachel Plut
Television technology has come a long way in the last decade. The image quality that they display is clearer (the resolution), the darks have become darker and the lights lighter (the contrast ratio), and the number of images that can be displayed per second much higher (the refresh rate). All of these have dramatically improved the viewing experience of televisions in the home. However, maybe the most immediately noticeable change in TVs over the past decade is how slim they have gotten.
The old tube TVs that we all grew up with (CRTs or Cathode Ray Tubes) and the old-school big-screen TVs (rear-projection TVs) are quickly becoming unfashionable, inconvenient, and obsolete. In their place have emerged two key new types of screens – LCD and Plasma.
Plasma TVs
Plasma TVs display pictures on the screen using tiny gas plasma cells. Each of these plasma cells emits light and color, which means two things. First, it means that plasma TVs do not require any sort of backlighting like LCD TVs require. And second, it means that they can produce very dark darks and very light lights. Many home theater pundits recommend plasma TVs over LCD TV for this reason; although technologies like local dimming using LED backlighting in LCD TVs has started to close this gap.
There are several issues to consider with plasma TVs. Due to the nature of the plasma in the TVs, the screens have to be made of layers of glass, which often creates problems with glare in lighted rooms in the home. They have also had problems in the past of burn-in, although this has improved significantly in past years.
Plasma TVs are an improvement over previous TV technologies, but their market share in the flat-panel TV market is falling year after year to LCD TVs as LCD panels become more common and more economical to produce in large sizes.
LCD TVs
One of the biggest differences between LCD screens and plasma screens is that LCD screens require backlighting, which has conventionally come in the form of fluorescent lighting tubes. Although manufacturers have been able to fit these tubes into tighter and tighter spaces, a recent development in the market has revolutionized backlighting – the implement of LED lights in TVs, such as the Samsung C7000 Series.
There are three key advantages to true LED backlighting in LCD TVs. The first advantage is in power consumption – since LED lights do not require nearly as much power as florescent tubes, LED-backlit TVs consume less power.
Second, LED backlighting reduces the amount of space required within the TV, thus allowing manufacturers to produce extremely slim sets. Some sets, such as the LED-backlit LG 55LE9500, are less than an inch thick. This is a remarkable upgrade even from flat-panel TVs several years ago.
The third advantage of true LED backlighting is the ability to increase the contrast ratio through local dimming, like the LG 47LE8500. Since the LCD panel is illuminated by a series of LED lights instead of large florescent tubes, the lights can be dynamically turned off to create darker darks.
One thing to keep in mind is that some companies, such as Samsung, produce edge-lit LED backlighting instead of true LED backlighting. This means that instead of having LEDs directly behind the LCD screen, they install LEDs around the edge of the screen which shine on a screen that goes across the back of the panel, diffusing the light forward. This does reduce the number of lights required, but it also eliminates the ability to locally dim lighting to produce darker darks.
