What are the characteristics that differentiate the TV? Screens LED, LCD and Plasma
The imaging technology is advancing faster than ever, high definition (FullHD) has become a standard and the choice of which TV to buy is going to be based on other factors, parameters and prices.
Since the advent of digital terrestrial many people are forced to buy a new TV, let's try together to see which technology is better, between the LCD TV, Plasma or LED.
As already done for computers, we see things to know before buying a new TV.
Unfortunately, because of the commercial strategies of electronics manufacturers, it is diffcult to understand whether a technology is better than another.
A TV can cost less but have the sharpest image over another, according to the seller, superior technology.
The consumer remains very confused in the face of these indications would seem to disprove what you see by eye.
This simplified guide can be a basis for the selection and purchase, maybe to carry around when you go to the mall and to compete on equal terms with the salesman / seller.
First of all let's see what are the most important terms related to HD TV, which to know the meaning.
- Contrast Ratio: (native contrast): one of the objectives common to all manufacturers is to be able to get a black level as close as possible to what they could get with cathode ray tubes, as this is the feature that is able to confer a better image depth, a greater body of colors and a greater contrast, and hence a better image quality. Sometimes we talk about dynamic contrast ratio, ie the ratio between the pixels illuminated white and the black to the maximum to a minimum, not to be confused with the native contrast that instead measures the ratio between maximum brightness of a pixel white and one black.
- Refresh rate: How many times the screen redraws ("refresh") the created image.
The refresh rate is measured in hertz or cycles per second.
The higher the refresh rate, the better the quality of moving images with reduced blur and clarity.
The plasma screens usually have a refresh rate much higher, with refresh rates of 600Hz, but LCD and LED TVs are catching up with values ranging between 60, 120, 240, or 480Hz.
- Pixel Response Time: similar to the refresh rate, the response time of the pixels is the number of milliseconds by which individuals react to the change of image pixels.
The response time refers to how quickly the individual pixels can change colors from white to black, red or green.
The lower the time, the better and faster-moving images will be less blurry.
- Resolution: FullHD TV All have the same resolution of 1920 × 1080 at 16/9, if you want to spend less you can still find and buy a HD Ready TV with lower resolution and, therefore, a picture less sharp (however, the transmissions of the normal channels Mediaset and RAI are not HD). Full HD with a resolution of 1920 × 1080 pixels, and HD-ready TVs with a resolution of 1280 × 720 pixels compared to the early reproduce images that are less defined.
- Aspect ratio, ie the ratio between the width and height of the panel. The format currently is the most common 16:9 (wider by about 33% compared to 4:3), but they are beginning to spread to the first televisions with 21:9 ratio used in CinemaScope.
- The viewing angle is the angle by which a screen is able to offer the best quality of 'image. LCD TVs are in fact subject to a drop in brightness or a significant change in color reproduction while you are away from the central viewing position. The TV should offer an ideal viewing angle of 180 degrees both horizontally and vertically
The models of television sets sold in the malls are, broadly speaking, three types of
1) LCD: An acronym for Liquid Crystal Display (LCD), is the most common screen model and is present in televisions, computer monitors, to laptops, in some watches, cell phones, and microwave ovens.
The LCD screens were the first type of monitor thin, with a good image quality.
Until recently, the LCD showed a lower image quality than the CRT (cathode ray tube tv old), with a lower color depth and contrast ratios are lower, but today have improved considerably and you can see very well in rooms illuminated.
Liquid crystals do not emit any light and must be back-lit.
When a HDTV is classified as an LCD television, means that it is backlit with CCFLs, or cold cathode fluorescent lamps.
2) LED: Acronym for Light Emitting Diode, is equal to an LCD screen, with a different type of backlight (Light Emitting Diodes).
LED TVs are highly publicized in the market and sold at higher prices but I'm not the revolutionary innovation that would have us believe.
They offer some advantages over the LCD-HD, including: lower energy consumption, no mercury and therefore more eco-sustainability, a higher contrast with blacker blacks, a wider color range, and improved aesthetics with screens thinner.
Conversely, the price is much higher and, if I may, in an unjustified manner.
There are two types of LEDs: Full LED with truer blacks and a higher dynamic contrast ratio, Edge-LED TV screens are ultra-thin with uniform distribution of color that are also cheaper.
The LEDs still do not reach the contrast ratios obtainable with Plasma TVs but they offer a picture quality much better than an LCD.
3) Plasma
Televisions Plasma have the best image quality that you can find on the market because they have a high contrast ratio and wide range of colors available.
The Plasma is used only for very large screens and are also 50 "at prices that are exorbitant.
The plasmas are also thin and can be hung on the walls such as LCD or LED.
The response time of the pixels is significantly higher than the LEDs and the LCD then the images are moving fast (like a game of football or tennis), you see better.
Plasma TVs have a wider viewing angle so the image looks good even if it takes a sidewise and become better than others when watching tv in the group.
Although plasma TV screens are the best, they have the big drawback to consume a lot of energy compared to other technologies.
They are also not sustainable for the presence of harmful chemicals within and disposal of a plasma TV is more expensive.
Another drawback of this technology is the so-called "ghost effect" or burn-in. Basically, if you project the same image for too long on the panel, it ends up imprints upon the phosphor layer since in that case the pixels age unevenly scintillators, which lose efficiency. This phenomenon could occur tuning always on the same channel, whose logo is always displayed in the same location, or viewing for a long period of time movie with black stripes. Unfortunately, the aging of scintillators there is no remedy.
The Plasmas are also more vulnerable, less durable and easier to break than the LCD / LED.
For these reasons, fewer and fewer models of plasma TVs that are on the market.
Other types of TV are:
4) Rear projection televisions (RPTVs)
This type of TV is no longer located in shopping malls and today serve only for specific needs.
It is an evolution of the CRT cathode ray tube, with a thickness much thinner and a weight significantly lower (inside are almost empty).
Projection televisions are recommended for those who need a very large screen, even from 82 "(a big LCD so it would cost a lot).
The biggest problem, from what I've seen, is that they work with a lamp (like normal projectors), which, if it breaks should be replaced at minimal cost of 200 Euros.
5) 3D TVs
Taking advantage of the tendency of the film in 3D, many HDTVs have support for watching movies in 3D.
The main problems are the lack of 3D-TV (not to mention the total absence) offer TV programs in 3D and the need to use special glasses depending on the model.
6) The Smart TV or Smart TV with internet connection.
When you buy a television must also look to have all the sockets for connecting external devices.
In another article I explained the various types of sockets connectors and cables more common.
Must not be missed, in a new TV, the USB port for connecting external hard drives or thumb.
Important can also be the power outlet to connect the TV to the Internet even if you can not for now, hope to surf the web smoothly from television.
Unfortunately, the various models of TV-HD also differ depending on the software that they use in them.
The important thing is to check that the TV can play the DivX video (eg read from the USB stick).
In conclusion, we can not say whether it is better or worse, a type of TV or the other.
Figure out which TV to buy depends very much on the specific needs and use that is made of the TV.
For example, if you look at football matches and sports, will be favored a tv screen with high response speed (Plasma), if you look at the little TV, maybe you would prefer that it is aesthetically a beautiful piece of furniture (LED) , If you often see in movies Blueray, it takes a high contrast ratio (LED), if you use your TV only to see the RAI and Canale 5, needless to spend much, just a mid-level LCD; video game players may prefer to see the hotfix and the bright colors of the LED and Plasma TVs, in certain circumstances, if you would need a very large screen tv, you could opt for a rear projection television.
10/01/2011
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Translated via software
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Source:
Italian version of ReteArchitetti.it