Sunday, 12 December 2010

Type of TV

type of TV

LCD is short for 'liquid crystal display' which is a type of display that uses an array of crystals in front of a backlight source. When voltage is applied to these crystals they twist to allow varying amounts of light to pass through colour filters, this is a process that happens at every pixel to essentially display the entire image on the screen or TV.

With LCD being such a widely available display technology, you won't have a hard time finding many different styles and brand names. Although not being available in larger sizes used to limit the LCD technology, this is no longer true. The range is from about 7 inches to 65+ inches in size. The smaller and more common sizes are also very budget friendly because they are mass produced on such a large scale for everything from TVs to computer displays. When you get into the larger LCD sizes, usually 50+ inches, then the price starts to get a little more costly than some of their plasma and DLP counterparts. Since the main source of an LCD's image is produced by the flat panel and the accompanying backlight, these are not very deep TV's and are popular for wall-mounting and also outperform all other TV styles when displaying static images. The good news is that with LCD panels being such widely produced in such a large variety of sizes now, prices are continually dropping on this technology. Being very budget-friendly is what makes LCD such a popular choice amongst typical home users who aren't looking to spend a lot of cash to build a big home theater system. Due to the design of an LCD panel there is no need to worry about any sort of “burn-in” time where you need to be careful with the display settings. We'll touch more on this subject in a bit. We are also past the days of slow LCD panels where ghosting would be an issue and that is another area you simply do not need to worry about when shopping for an LCD TV.

Visually, LCD buyers often enjoy the ability to choose between models with the typical non-reflective front panel and those with thin glass overlays on the front. This is quite different front plasma TVs where the gases used to create the plasma are sandwiched between two [reflective] glass panels. Depending on the style of room a plasma TV is being put into, this highly reflective front may not always work to the buyers liking.

Although there are some cons to the LCD TV category, I personally don't find these big enough to sway me away from buying one. First off is the problem of viewing angle, which is continually being improved upon as LCD technology advances. The viewing angle of an LCD display is somewhat less than their plasma and DLP counterparts. Plasma's have a viewing angle of up to 180 degrees where as LCDs tend to fall short of that at around 175 degrees (give or take a few degrees on each comparison). Since LCD displays were originally designed for a single-user experience, such as a computer monitor, they have a “sweet spot” viewing angle where all the colours and intensities are better balanced. Plasmas do not suffer from this “sweet spot” and can be viewed equally from any angle.

Another bound-to-happen issue on most LCD TVs is backlight leakage. Since the backlight on these displays is what makes the LCD panel bright enough for the picture to be visible, it must always be turned on. When an LCD panel shows black it is simply blacking out the pixels that must be black but there is still a backlight turned on behind these pixels. This often causes the blacks to not be a rich and deep black, but to be slightly lighter. Depending on the quality of the TV and your viewing angle, the blacks in your picture may sometimes be very noticeably lighter, often with a slight white hue to them from this bleeding of the backlight. Keep in mind that's often only common on cheaper TVs, and if you try out a few before buying and invest your money wisely you won't run into a problem this severe.

Plasma HDTV
A plasma TV is made up of millions of cells containing the inert gases required to illuminate the display when they are charged. Each pixel of a plasma television is divided into three “sub-pixels”, one for red, one for green and one for blue. When the gas in these sub-pixels has a charge applied to it, it turns into a luminous plasma. Through this happening in every single pixel of your TV, the right colours will be lit up to create an image. Another option you'll have in your search for a new Television is a plasma TV. Plasma televisions don't come in sizes nearly as small as their LCD counterparts, but they are just as thin as a lot of LCD TVs so they can be easily mounted on a wall as well. When it comes to buying a larger sized TV, plasma is often one of the two cheaper routes to go; with DLP being another option we'll discuss soon. Although plasma doesn't always share the same resolutions as similar sized and priced LCD panels do, most plasma TVs are capable of 1080p.

Since illumination is created by a chemical reaction at each pixel and does not rely on a backlight that is always turned on like the LCD technology, a plasma TV will have much better blacks than an LCD can achieve. This will be especially noticeable with off-axis viewing, a case where LCD's will commonly lose black intensity. When it comes to contrast ratio, black levels, and depth perception it is said that plasma has a great advantage over LCD's in normal to low room lighting conditions. When you're in a really bright room or have nearby windows then make sure you watch out for reflections off the glass front!

As plasma TV's commonly only come in 42”+ sizes, you can't expect to go out and buy a “cheap” or “small” plasma. Once you do buy that new plasma, keep in mind that a lot of people don't realize that there is a “burn-in” time. For the first 100 operational hours of the TV you should run it at a reduced contrast level because it is possible to get a permanent image “burned” into the screen. During this time you will want to make sure that all the content you watch is in full widescreen mode. Any black bars at the sides of the screen from watching 4:3 ratio video will further contribute to this burn-in. After that initial 100 hours the TV will be much less sensitive to burn-in, although not completely clear of it. For minor burn-in, there are applications out there that can be executed from a computer to try and fix it.

DLP is certainly the more technologically complex of the three major television styles. A DLP chip containing over a million small mirrors (one for each pixel) is a chip that is small enough to be held in the palm of your hand. By tilting a mirror towards a light source or away from it, the corresponding pixel's 'on' or 'off' state can be controlled. Since each mirror can be turned on and off thousands of times per second, the chip has the capabilities to keep up to creating action-intense scenes without a problem. The replaceable lamp bulb that lights up these mirrors is first filtered through a colour wheel before reflecting off the DLP chip mirrors. This colour wheel is what creates the red, green and blue colours required to create a full-colour image. The last of the three major options you'll have to choose between is a DLP TV.

The projection method used on these TV's will make them quite a bit deeper than a plasma or LCD set of the same screen size. That cuts out the option to wall-mount these guys; they must be set on a stand in order to elevate them to optimal viewing level. Having an excellent size to price ratio, these are another very popular style of TV for those wanting to go big. A DLP television will often cost less than it's identical sized plasma counterpart. As with plasma, you will only find DLP TV's on the larger size (commonly 42”+). Also similar to plasma is the absence of a backlight behind the panel of a DLP television. This will also give it far better blacks than an LCD screen would have.

Being in such an affordable price range means that you will have lots of options to choose from when buying a DLP TV, so count that as another plus. Being a continually evolving format, DLP manufacturers are starting to improve upon some issues this technology faced when it was newer. The “rainbow effect” is something you may experience on a DLP TV with a bulb backlight. Since only one colour on the internal colour wheel is shown at a time, if you pan your eyes across the image or look away and then look back quickly, some people say they can actually see the colour separation. Newer DLP designs are improving upon this by using LED backlighting with RGB LED's to essentially replace the traditional bulb and colour wheel all together. This not only cuts down on that expensive bulb cost, but also rules out the fact that the colour wheel may be subject to future failure because it is a mechanical device (and as we know, few mechanical devices will last forever). Unlike older DLP's that would achieve 1080p through a method called 'Wobulation', newer chip designs are also enhancing upon this by allowing the TV to natively produce 1080p content without some mirrors doing “double duty”.


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