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Buyers Guides > Home CinemaA Simple Guide to Buying an LCD Screen or LCD Television
LCD TV Technology Explained (LCD Liquid Crystal Display) Your old TV has some new competition by innovative new Liquid Crystal Display (LCD) flat panel televisions. Like popular LCD monitors you commonly see used with computers, LCD TV's have a slim design and a flat viewing surface, but have been fine tuned for video display. Recent advances in flat panel LCD technology now allow for larger screens, wider viewing angles, and higher-quality video images. LCD TV's are also competition for trendy-but-heavy, plasma display technology. They are several times lighter than comparably sized plasmas, and are far more durable. How do LCD TV's work? Unlike plasma, light isn't created by the liquid crystals, but filtered
through it. The screen is segmented into thousands of tiny cells (pixels)
and the liquid crystal is sandwiched between two pieces of glass (substrate)
that can have light electric current passed through. A backlight behind
the liquid crystal panel shines light through the display. When an
electric current passes through the liquid, it causes the crystals
to align so that light cannot pass through them. Each crystal acts
like a shutter, either allowing light to pass through or blocking it.
The pattern of transparent and dark crystals forms the image. The crystals
themselves do not produce light, so the technology is non-emissive
and therefore does not give off radiation like an older TV does. Because
florouescent tubes housed behind the transparent material are used
to illuminate the image, so they require less power to operate than
CRT televisions and plasma displays. Most flat panel TVs (Plasma and LCD) are 16:9 – also known as widescreen format. This is the ratio of width to height for the screen. The European PAL television standard uses a 4:3 ratio producing a more square-like image, however DVDs and HDTV are best viewed in widescreen. Contrast ratio Measures the difference between the brightest whites and the darkest
blacks a display panel can show. The higher the contrast ratio, the
greater the ability of a display to show subtle colour details and
tolerate ambient room light. A good contrast ratio is an important
requirement for all types of TV display. HDTV broadcast services will start in Europe in 2006. This will deliver viewers the best picture quality ever seen in the history of broadcast television. HDTV refers to the highest-resolution format of digital broadcast TV. While there is still some discussion about what is true HDTV, it is generally accepted that 1,080-line interlaced (1080i) or 720-line progressive (720p) are HDTV. A TV that is described as ‘HDTV-ready’ is usually capable of properly displaying at least 1000-line interlaced or 720-line progressive. Progressive scan In Europe progressive scan displays 50 full frames per second resulting in a picture quality that is more filmlike, with more fine detail and less flicker. For progressive-scan viewing, you'll need a TV that's HDTV-ready. Resolution You will need a TV or monitor that is capable of displaying HDTV and DVD signals. This requires a screen capable of showing over 1000 lines for interlaced or 720 for progressive scan. Resolution is also sometimes represented as the number of pixels in a width x height (eg. 1024 x 768) format. DVI & HDMI These are both signal connections that enable the TV/monitor to connect directly to a digital signal so that there is no conversion of signal between its source and the screen. Most of the older TV systems convert a digital output signal (from a DVD player, for example) to an analog signal for the display panel. DVI (Digital Video Signal) carries a video-only digital signal and HDMI (High Definition Multimedia Interface) carries a digital video signal plus audio. 16:9 (Widescreen) and 4:3 Aspect Ratio Most flat panel TVs (Plasma and LCD) are 16:9 – also known as
widescreen format. This is the ratio of width to height for the screen.
The European PAL television standard uses a 4:3 ratio producing a more
square-like image, however DVDs and HDTV are best viewed in widescreen. Measures the difference between the brightest whites and the darkest
blacks a display panel can show. The higher the contrast ratio, the
greater the ability of a display to show subtle colour details and
tolerate ambient room light. A good contrast ratio is an important
requirement for all types of TV display. HDTV broadcast services will start in Europe in 2006. This will deliver viewers the best picture quality ever seen in the history of broadcast television. HDTV refers to the highest-resolution format of digital broadcast TV. While there is still some discussion about what is true HDTV, it is generally accepted that 1,080-line interlaced (1080i) or 720-line progressive (720p) are HDTV. A TV that is described as ‘HDTV-ready’ is usually capable of properly displaying at least 1000-line interlaced or 720-line progressive Progressive scan In Europe progressive scan displays 50 full frames per second resulting in a picture quality that is more filmlike, with more fine detail and less flicker. For progressive-scan viewing, you'll need a TV that's HDTV-ready Resolution You will need a TV or monitor that is capable of displaying HDTV and
DVD signals. This requires a screen capable of showing over 1000 lines
for interlaced or 720 for progressive scan. Resolution is also sometimes
represented as the number of pixels in a width x height (eg. 1024 x
768) format. These are both signal connections that enable the TV/monitor to connect directly to a digital signal so that there is no conversion of signal between its source and the screen. Most of the older TV systems convert a digital output signal (from a DVD player, for example) to an analog signal for the display panel. DVI (Digital Video Signal) carries a video-only digital signal and HDMI (High Definition Multimedia Interface) carries a digital video signal plus audio. Things to think about before you buy...When deciding on buying a new flat panel TV, there are a number of
considerations that are worth bearing in mind before you purchase. Your viewing habits will be different for each of the different rooms in the house and this should be taken into account when buying a flat panel TV. For example, viewing while preparing a meal in the kitchen is very different from settling down with your feet up to watch a feature-length movie in a living room. The compactness of flat panel TV’s mean that bigger screens can now be used in more confined spaces. Typically LCD TVs are better in smaller rooms (where TV viewing is not the main function of the room) such as kitchens and bedrooms. For larger bedrooms and living rooms, a Plasma is preferable b) What size screen would allow for maximum viewing pleasure, without it being too big or too small for the room? As a rule of thumb, you should always be able to sit at least three times the height of the screen in distance away from the screen when viewing it. For example a 42-inch plasma (which is about 2ft in height) should be viewed from at least 6ft away for best effect c) How will you arrange the layout of the room around the new screen? Most of us tend to have traditional TVs located in the corner of a living room because this is the best way to use the space when you have a bulky, cube shaped TV – but flat panel TVs can be hung on a wall, set up in a table-top or even integrated into a wall shelving unit. But remember, a TV tends to create a focal point in any room so consider how the location of the flat panel TV will affect how you use the room. This will help you decide on how your furniture should be laid out d) Can you hang your flat panel TV on the wall? If you plan to hang the flat panel TV on a wall, make sure that the wall is capable of taking the weight of the screen. (A 42-inch panel weighs about 35kgs / 78 pounds). If you have plaster-board/cavity walls then you need to ensure that the mounting brackets are sunk into the stud framework within the wall. Never hang a flat panel TV over a working fireplace. Also, make sure that there is a way to conceal the signal and power wires – if not moved out of sight, a cluster of cables can spoil the aesthetic effect of the clean lines of a slim flat panel TV. e) Where are the windows and what sort of lighting does the room have? Direct sunlight on any screen, whether Plasma, LCD or CRT degrades the viewing experience. The best contrast and picture quality is achieved when the ambient light in the room is relatively low and there is no light source shining directly into the screen. Be careful to consider the location of windows when you are hanging a flat panel TV – do not hang an LCD or Plasma screen facing an outside window – unless the window can be completely blacked-out for day-time viewing. f) Do you plan to use the TV with a games console or connect a PC to it? If you plan to use your new flat panel screen for gaming or surfing the internet using a PC this will have an impact on where you locate the flat panel screen in its chosen room. You will also need to be sure that the flat panel TV you buy has the appropriate signal input connections for these items. Ideally you want to have sufficient connection points on the TV to avoid having to disconnect and re-connect your DVD player/VCR/digibox each time you want play a game or use the computer. g) Do you want surround-sound with your new TV? For living rooms, TV rooms and dedicated home cinema theatres, a good surround-sound system can significantly improve your viewing experience. A variety of dedicated surround solutions are available today, varying in price and performance. Most hi-fi stereos are also built with the available connections to allow for the TV’s audio signal to be played through them. In addition, most flat panel screens are supplied with speakers, either integral to the screen or detachable
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