LCD offers the most convenient format to watch television because it operates well under any light conditions while its low
weight and ultra slim design makes it suitable for any room location. Whether you want a television for a bedroom or kitchen,
on a wall or free standing or in a bright or dark environment, an LCD television will do the job.
An LCD screen consists of a solution of liquid crystals sandwiched between 2 panes of polarized glass. The crystals untwist as they
are subjected to differing electrical voltages, which in turn determine the amount of light the crystals allow to pass through them.
The light is provided by a florescent bulb and the electrical supply is controlled by Thin Film Transistors (TFT's.) Each panel is made
up around 1 million pixels each of which is sub divided into 3 sub pixels to display a red, green and blue tone. Each sub pixel can
be independently controlled by a transistor meaning that a pixel can reproduce 16.8 million different colours. Consequently, there
is even colour saturation across the screen with no scan lines.
The pixels are constantly refreshed by changing the voltage via the transistors to the crystal. Early models of LCD had a slower refresh
rate meaning that a moving image on the screen would lag. However, screens can now refresh at over 50 times a second giving a clear
definition to moving objects.
LCD panels can be made efficiently up to 32” in size and while larger screen sizes are available, these tend to be proportionately more
expensive to make.
Flat panels such as LCD have been hailed as the future of television as they have so many benefits. These include:
Sharp, clear pictures with less reflection from sunlight. There are no scan lines which are an accepted weakness of conventional tube televisions. With a choice of 16.8 million colours per pixel and a quick image refresh rate, the picture is colour rich and well defined making it very easy on the eye.
Ultra slim and light so can be used in many locations where space is at a premium such as kitchens and bedrooms and are easily wall mountable with the correct kit.
They have a 160 degree viewing angle so can be comfortably watched from most any position.
Most LCD's come complete with a tuner and speakers so have the same functionality as a conventional television and can be watched straight out of the box.
Some models can be used as a PC Monitor.
Manufacturers now claim that the life expectancy of an LCD panel is 60,000 hours which is nearly 20 years at an average daily usage of 8 hours. Even if these claims are overstated, a panel should last at least as long as a conventional tube television. The florescent light source may not last this long but in most cases this can be replaced and in any event, the better the brand of equipment purchased, the longer the quality of the light source you will enjoy.
What should I consider before buying an LCD TV?^ top
Purchasing an LCD television is a major financial decision so it is important to consider the
following before making the investment.
Contrast Ratio – This is the variation between the blackest blacks and the whitest whites and is measured in ratios of 1000:1. The first number is how bright the screen can go, while the second is the darkest. So a screen with a contrast ratio of 4000:1 would give a better definition between light and dark.
Screen Size - LCD panels are easier on the eye than conventional tube televisions so you can watch with more comfort if you need to be close to it. However, your seating position should be at least 6 foot away for any screen size in excess of 28”. If you sit closer than you should consider a smaller screen size. If you are considering a screen size above 30” then it would pay to also consider plasma panels which represent increasingly better value for money the larger the screen gets.
Digital tuner – If you want to watch Freeview without the use of a separate set top box then it is important to select a panel with an integrated digital tuner although presently few smaller sized panels offer this facility.
Computer Monitor - If you want to use your LCD television as a computer monitor, be sure that the model selected can do this. Many do not have the appropriate RGB inputs.
Pixel drop out - A pixel can stop working which may allow a constant light through. This can sometimes be seen as a red, green, blue or in some cases a black dot on the screen. This is known as Pixel Drop Out and will occur at some point during the life of the panel. Given that most panels have a minimum of 786,000 pixels, your eyes will not notice it but in exceptional circumstances this can be an issue if a number should drop out close to each other near the centre of the screen. Nothing can be done to replace these pixels and there is little redress to be had with the manufacturer.
The truism that the more you pay the more you get applies in spades to LCD televisions. The refresh rate,
bulb life span, viewing angle and colour definition all improve with price so be careful before selecting the cheapest Chinese
produced panel from a brand that you do not know or associate with quality.
The very latest products automatically detect the brightness levels of the input signal and adjusts the backlight accordingly in real-time.
This represents a dramatic improvement over conventional LCD TVs, which commonly suffer from insufficient maximum brightness and a
lack of depth due to weak black reproduction. The result is a greatly expanded dynamic range from black to white peak, with crisp, natural
pictures that assure dynamic viewing.
Plasma televisions offer the ultra slim design of LCD, the big movie experience of front projection with the day-to-day practicality of
a conventional tube television and are considered by many to be the original hang on the wall television.
Plasma screens use thousands of tiny gas filled cells using a mixture of Xenon and Neon gas to produce a picture , which
when charged emit UV light and hit coloured phosphors in red, green or blue on the back of the screen. These phosphors
emit the amount of light and colour necessary to create an image.
Some plasma televisions are supplied without a tuner and others without sound as a number of home cinema enthusiasts
prefer to use a separate audio and tuner source. Others such as the beautiful Panasonic TH37E30B come complete with stereo
sound and digital tuner, with optional floor, pedestal stand or wall mounting kit, it can offer a complete solution that would grace
any living room.
For many people, a large plasma panel represents the pinnacle for home television as it offers so many advantages:
Plasma panels have sharp, clear pictures with excellent colour saturation. There are no scan lines which are an accepted weakness of conventional tube televisions. With a choice of 16.8 million colours per pixel and a quick image refresh rate, the picture is colour rich and well defined making it very easy on the eye.
The screen is pure flat and has an antiglare Plexiglas layer. Taken together, this drastically reduces reflection from sunlight that afflicts many conventional tube televisions when viewed in a sun lit environment.
The ultra slim design means that they are wall mountable with the correct kit.
They have a 160 degree viewing angle so can be comfortably watched from almost any position.
Large screen sizes of up to 61” are available for a real home cinema experience. Furthermore, these large screen sizes represent good value for money when compared to LCD which struggles with production difficulties.
Some models come complete with a tuner and speakers so have the same functionality as a conventional television and can be watched straight out of the box. However, many home cinema enthusiasts prefer to use a separate digital tuner and surround sound speaker configuration so do not want to pay for a built in tuner and speaker. There are a wide choice of plasma monitor only options available for this situation.
What should I consider before buying a Plasma TV? ^ top
With prices starting from £2000, buying a plasma television is a major decision and the following
should be considered before making a purchase.
Contrast Ratio – This is the variation between the blackest blacks and the whitest whites and is measured in ratios of 1000:1. The first number is how bright the screen can go, while the second is the darkest. So a screen with a contrast ratio of 4000:1 would give a better definition between light and dark.
Screen Size – Plasma panels start from 32” in size with the most popular being 32”, 37” and 42”. You should be sitting a minimum of 6 feet away from the 32” panel, 10 feet from the 42” and 13 feet from a 50” panel.
Digital tuner – If you want to watch Freeview without the use of a separate set top box then it is important to select a panel with an integrated digital tuner although presently few smaller sized panels offer this facility.
Wall hanging – P lasma televisions are far heavier than LCD televisions so if you plan to secure it to the wall, you must use the correct fittings and insure it is solidly mounted. There are a number of wall mountings available which may tilt the panel downwards or sideways. However, beware of putting the panel too high (such as above a fireplace), as the viewing angle may be uncomfortable. It is also recommended that a plasma screen should not be mounted above a heat source such as a fireplace or radiator. Doing so can run the risk of overheating the screen, leading to limited life or malfunction.
If a static image is left on the screen an after image can be left permanently on it. This is known as screen burn and cannot be fully repaired so it is important to be careful not to leave a still image displayed on the screen for too long.
The life expectancy of a plasma panel is hard to estimate because time does not stop the panel from working but only dims the colour quality. The phosphor gases decay at a constant rate so the colour intensity will degrade at the same rate. Typically, after 15,000 to 20,000 hours the picture will have retained 68% of its original colour intensity which is perfectly acceptable. The point this becomes unacceptable is subject to personal taste but most manufacturers quote around 30,000 viewing hours which is around 10 years assuming average viewing usage. Keeping the contrast and brightness levels in the mid range helps extend the life expectancy. The plasma pixels cannot be re-gassed so treat with suspicion any sales claim to the contrary.
Plasma panels do not suffer from pixel drop out to the same incidence as LCD panels. However, should the screen be damaged then in many instances it is beyond repair. Its weight and complexity also mean that plasmas are more expensive to repair.
Plasma panels are heavier than the equivalent LCD panel and consume more power. It helps to turn the panel off when it is not being watched and to make sure it is in a well-ventilated environment.
Front projectors employ similar technology to that used in you local cinema by projecting an image onto a reflective screen.
This makes front projection for some enthusiasts the only true home cinema experience. The projector is connected to a tuner
such as a digital set top box or DVD to receive a visual feed. This tuner also outputs the sound feed to an amplifier or home
cinema AV kit.
There are 3 different types of front projection units available.
CRT Projectors.
These use individual red, blue and green guns to project an image onto the screen. These projectors are
arguably the best in picture quality but given their overall size and weight they are more suited to a bespoke
home cinema environment than a living room.
LCD Projectors.
These use a small LCD screen inside the projector to make an image through which a beam of light is shone so
as to project the image onto the screen. This is by far the most affordable type of projection unit available, but
can lose out on the quality and brightness of the image when pushed to its limits.
Digital Light Projection.
DLP is the most advanced method of projection currently available using over a million tiny moving mirrors.
A very powerful beam of light is passed through a rotating colour wheel onto these mirrors, and by individually
tilting each mirror the projector can reflect the correct amount of light through the projection lens. Overall this
process contributes to an exceptional picture quality in a very small unit. However these units are quite expensive.
The image is lost if there is too much ambient light so it is important to control the viewing environment.
Objects in the path of the light projection will blank out part of the image for everyone. This may be minimised by ceiling mounting the unit or encouraging everyone to stay seated!
In practice, the need to control the environment means that front projectors are less suitable for every day use such as watching the news while reading the newspaper. It is however unbeatable for the big movie experience.
Rear Projection televisions are the most affordable way of getting large screen viewing of 40” and above. Most are fully functional
televisions with speakers and tuners all incorporated. There are three variations of these televisions available.
CRT.
These use three colored guns ( red, green and blue) which are fired at a mirror inside the TV and reflected back onto the reverse
of the screen. Televisions of up to 60” can be created using this method, but there is a down side. To gain the best overall performance
you have to be sitting almost directly in line with the screen. Too much to one side or standing too close will cause your viewing picture
to dim. Also for optimum viewing, the room in which it is situated can't be too bright as any light will diminish the brightness of the TV.
LCD.
These use a small LCD screen inside the projector to make an image through which a beam of light is shone so as to project the image onto
the rear of the screen. The resulting image is brighter and more detailed image. Increasingly rear projection televisions use this method because
of its overall efficiency.
DLP.
The new kid on the block which is starting to make a name for itself as the best method to get a picture within this field. DLP is the most
advanced method of projection currently available using over a million tiny moving mirrors. A very powerful beam of light is passed through
a rotating colour wheel onto these mirrors, and by individually tilting each mirror the projector can reflect the correct amount of light onto the
rear of the screen. These units are currently supplied as a monitor only (without sound or tuner) as the specialist home cinema enthusiast
prefers to use their own source. The quality however comes at a price.
What are the benefits and drawbacks of rear projection: ^ top
Benefits can include:
It provides the largest screen sizes from 40” to 61” at a more affordable price.
Relatively shallow cabinet depth, compared to a conventional CRT Television.
Disadvantages can include:
Using in well-lit environments can hinder overall performance. Optimum performance is obtained by sitting on a similar level to the screen. Rear projection can also have a narrow viewing angle, with the picture dimming or disappearing when sitting an angle to the screen.
Some would have you believe that a television sold without a digital tuner capable of receiving Freeview services will be
obsolete once analogue transmission is switched off. This argument over looks the fact that the old analogue signal is
not planned to be turned off in the last ITV region until 2012 and that many people no longer use the tuner provided by
their television preferring instead to use a SKY or digital set top box. This trend may well increase as digital tuners begin
to be used in recordable devices such as DVD recorders and hard disk drives. In this event people may use this signal
rather than that from their television.
Undoubtedly having a digital tuner integrated into a television gives you more flexibility and is essential if you want to
receive Freeview without using any other device. But this flexibility and convenience comes at a price with most integrated
televisions being over £100 more expensive than their analogue counterpart. So while it is preferable to have a
digital tuner in your television, it comes at a price and may not even be used.
What are the different types of surround sound? ^ top
Most of us are used to watching television and films in stereo through our televisions, but what if you could listen to the sound
from your favourite film as if you were at the cinema. Well you can with the use of a surround sound system.
Surround systems generally use a selection of speakers placed around the room. The first speaker called a centre speaker, is
placed on or underneath you television. Two more speakers are placed either side, these are the stereo speakers. Behind you
there are two more speakers provided the surround effects, and finally there is a subwoofer, a speaker which supplies all of the
base sound, for those explosions. These speakers work together to give you that cinema feel.
There are different formats in surround sound, with the most common being Dolby Digital. This is used mainly on DVD's and uses
all six of the speakers, each with its own channel or sound. The centre speaker carries the majority of the sound and dialogue throughout
the film. The stereo speakers provide directional sound, the rear speakers supply the effects while the subwoofer packs a base punch. By
using this system, the sound can be steered around your living room so for example if a plane flew across the screen, the sound would
start from the left front speaker and then feed to the right rear speakers.
There are three types of system you can consider.
Integrated Surround Sound
Many televisions have the centre, stereo and subwoofer speakers built into it which looks the most discreet. The rear speakers are still
separate and have a cable to each one coming from the television. In some cases all you then have to do is connect a DVD player to
your television using a Scart cable for the picture and a Digital lead for the sound. Once done, you have surround sound for watching DVD's.
This is the least expensive option but there is a limitation to the overall sound output from the speakers.
DVD/AV Systems
This is a one-box solution that sits under your television consisting of a DVD player, Amplifier and Speakers in an easy to use
and set-up system. All of the speakers are connected via cables to the main DVD/Amplifier and are controlled from there. This
type of system gives a greater output from each speaker, giving a better quality sound overall.
Separates
The ultimate is a separates system, consisting of a separate amplifier/surround processor, DVD player, and independent speakers.
This type of system can have individual units tailored to your personal taste that can be upgraded at any time so as technology
progresses, so can you.
There are several different formats of recordable DVD. While this may cause some confusion, it should not cause concern as all discs
made by a DVD recorder can be played back on that recorder and every player of that type. Some will also play back on other formats of
DVD players so enabling you to lend the discs to all your friends. So what is the best one to go for? Well it all depends on what you
require the machine to do. Here is an explanation to the different formats.
DVD+R/DVD+RW.
These types of discs provide the user with the versatility of playing back your recordings on around 70% of other DVD players.
This is because the recording uses a Video format which is the same as that used by recording studios to make conventional DVDs.
You can purchase +R discs which are write once which means that only one recording can be made and this can not be erased. You
can also purchase +RW discs that can be written and erased over again without any loss of quality. To play these discs back on other
machines they have to be finalized. This is achieved by closing the disc so no more can be added which turns it into a proper DVD disc.
Major manufacturers that support these formats are:
DVD+R: PHILIPS & SONY
DVD+RW: PHILIPS & SONY
DVD-R/DVD-RW.
DVD-R offers playback of a finalized disc on the widest choice of other DVD players, surpassing that of DVD+R. This is also recorded in
Video format. You can purchase -R discs which can record only once so any mistakes will remain. You can also purchase -RW discs which
can be recorded in either Video or VR formats. The Video format is similar to that of +RW in that you may record and erase many times
over without a loss of quality. I f you select the VR record mode, more editing capabilities become possible which is useful if you wish to
edit what has been recorded onto the disc. This ultimately means that you can erase or ignore adverts in recorded films, and trim sections
of recordings copied from camcorders so you can make home movies. The only downside to this is that this disc will only play back in the
machine it was recorded on. Major manufacturers that support these formats are:
This is the only type of DVD format that currently supports simultaneous playback and recording. This superb facility allows you to pause live
TV while you go to answer the phone or make a cup of tea. On your return, you can continue to watch the program exactly where you left it
safe in the knowledge that the rest of the program is still being recorded. This is made possible by recording in the land and troughs (raised and lowed)
parts on the disc. Seamless editing is possible, as the DVD recorder can just skip from scene to scene in an instant. The only drawback to this
recording format is that it can only be played back on the original recorder or DVD RAM compatible player. DVD RAM discs can be used many
times over and do not need finalising like +RW or -RW discs. Major manufacturers that support these formats are:
