Television

No home cinema system is complete without a television. This page explains the different types of TV, from the normal 4:3, to widescreen and more exotic prijection systems, plus a guide to the features that are found on the most common models.
TELEVISION

 

ASPECT RATIO

The aspect ratio of a television screen is the ratio of horizontal units compared with the number of vertical units. Two aspect ratios are used in televisions - either the common 4:3 or the 16:9 widescreen, where a 4:3 screen has 4 horizontal units to 3 vertical units and a similar relationship applies to 16:9.

 


Look at this scene from The Lost World: Jurassic Park. On the left is the original widescreen release with an aspect ratio of 16:9. On the right is the cut down 4:3 'Pan-and-Scan' version from the non-widescreen television and video release.

 
   

SCREEN SIZE

Televisions of each aspect ratio are available with different screen sizes. The screen size is the diagonal dimension measured between a top corner of the screen to the opposite bottom corner. 4:3 ratio televisions come with common screen sizes of between 14 inches up to about 40 inches, while the 16:9 widescreen sets are available with screen sizes between 20 inches up to around 36 inches.

These screen sizes can be found on the televisions with the traditional cathode ray picture tube. To get a screen size even bigger, a different type of television is needed, as detailed below.

 
   
 

Cathode Ray Tube (CRT)

If you use a TV with a heavy glass screen it will be a CRT model. The Cathode Ray Tube has been the standard technology for television screen construction for many years and has been adapted and developed to give us large screen 4:3 televisions and the current 16:9 widescreen sets. A CRT screen is made up of hundreds of tiny coloured dots called 'pixels'. Each pixel is coloured either red, blue or green (the primary colours). A picture is displayed as a series of pixels of different colours that are so close together they blend and mix to create every colour you see. But the technology has reached its limit - existing screens can't be made any bigger than they are now using CRT methods.

 
Hitachi C2586TN 4:3 Television with Cathode Ray Tube (CRT)
   
 

Rear Projection Television

The next step up from a large 4:3 television is a rear projection model. These TV's have a large flat screen in place of the normal heavy glass screen found on CRT sets. The picture is decoded and displayed on a small screen inside the television. It is then magnified and projected onto the back of the screen. You view the picture from the front as you would any other television.

The normal cathode ray television tube can only be made up to a certain size, but rear projection sets can go much bigger without the tube limitations. Screen sizes range from about 41 inches right up to an incredible 53 inches. However, the price of these sets are higher and are usually best suited to larger rooms. Expect to pay between £1500 to £5000 for a set depending on the screen size.

 
Toshiba 56PW8DB Rear Projection Widescreen Television
   
 

Front Projection Television

Not really a television in the normal sense, projection systems work in a similar way to the large projectors in your local cinema. The projector unit can be placed on the ceiling, behind the viewing position, or on a stand in front of the viewing position. You may have seen this type of equipment showing sports at your local pub, with the projector itself hanging from the ceiling. The source video is fed to the projector and the picture is projected onto a large flat screen in the position where a normal television would be placed. The advantage of a front projector is that very large screen sizes are possible, sometimes up to six times bigger than a rear projection unit. Expect to pay between £2,500 to £5,000 for a good all-round projector, and up to £20,000 for the top-of-the-range designs.

 
Sharp XG-NV4SE Front Projector
   
 

Plasma Televisions

The latest technology to grace the TV world, Plasma screens use a thin layer of chemical gel that reacts to an electrical current by changing colour. This technology enables screens to be made perfectly flat and very thin, with most sets measuring about 100mm (4 inches) from front to back. You could hang them from a wall if you wanted! Plasma screens are mainly all 16:9 widescreen, and quite impressive screen sizes are possible without the restrictions of CRT. Expect to pay a small fortune, though.

 


Eiki PV4210AT Flat Screen Television - only 100mm thick!

   

THE WIDESCREEN FORMAT

First, let me clear up some confusion that has been spread due to some manufacturers and retailers not understanding the widescreen format, and the lack of information available to the consumer. Widescreen televisions have an aspect ratio of 16:9, or in real terms 1.77:1. Widescreen movies on software such as DVD, Laserdisc, television and VHS video tapes come in various sizes from 1.77:1 up to 2.35:1. The aspect ratio of the software represents the same picture size as the original movie when it was shown at the cinema, not the size of a widescreen television.

The confusion has arisen because people with widescreen televisions have assumed that a widescreen movie will fill the entire 1.77:1 screen with no black bars. For this to happen, you would need a television for each of the different software ratios available! The widescreen television ratio of 1.77:1 has not been agreed at random. It has been adopted because 1.77:1 best suited the majority of widescreen movie videos that would be viewed on them at home, and it is the minimum requirement to benefit from widescreen software. If the screen ratio was 2.35:1, some software would have black bars at the sides and people would be equally unhappy about that also. Furthermore, it is unlikely that the normal widescreen television based on the cathode ray tube design can be made any wider than 1.77:1 without some form of picture distortion at the sides.

 
   

When any widescreen movie is viewed on a 4:3 ratio television, black bars are displayed at the top and bottom of the screen where there is no picture, and the movie is shown in its original 'letterbox' style. When a widescreen movie is viewed on a widescreen television the picture can be zoomed-in to fill the full width of the screen. However, black bars will still appear above and below the picture if the aspect ratio of the movie is greater that the 1.77:1 ratio of the television screen.

The perception of the quality of widescreen televisions has been further damaged by some retailers. They have a display of expensive widescreen televisions showing a 4:3 picture that they have expanded from left to right, giving the picture a stretched and distorted appearance simply to fill the screen. This is wrong and I know of people who have been put off buying a widescreen set because they think that all 4:3 pictures will be distorted in this way - they don't know that it's the untrained shop assistants who have created this effect and that the expand feature is not used to view a picture on a widescreen television in this way.

A widescreen television will eventually be at the centre of nearly all home cinema systems in the future, as more and more television programmes are made with a 16:9 picture size. With any ratio software, the picture will be much bigger and more like the real cinema than a normal 4:3 ratio television, with or without the small black bars. However, at the moment, even with the limited (but increasing) use of widescreen transmissions on digital television, a good 4:3 television should not be dismissed. A large screen 40 inch 4:3 TV showing a widescreen movie will probably have an actual picture size bigger than a 28 or 32 inch widescreen television, although it would have the black borders above and below the picture. And when viewing a 4:3 movie, the picture size is huge! But it's with DVD-Video that widescreen televisions really become a distinct advantage, by presenting the common widescreen movie format at its best.

 
   
For a more detailed look at the widescreen format, aspect ratios and movie film see the Moving Pictures page.  
   

SURROUND SOUND DECODERS

Some televisions have a built-in Dolby Pro-Logic decoder, or even a Dolby Digital decoder, and a set of rear surround speakers. These televisions can achieve quite high quality surround sound and are useful as a one-box way to get home cinema, particularly in rooms where space is limited, or the extra hardware and large speakers are unwanted. But as with video recorders and satellite receivers with built-in decoders, they can be out performed by a separates system made up from dedicated home cinema hardware.

 
   

CONNECTIONS

There are several types of connections that can be found on televisions:

 
   
 

Euro A/V SCART

Most video sources will be connected to a television using SCART cable. Some televisions have input sockets for up to three SCART cables, useful if you want to connect a DVD player, video recorder and, say, a satellite receiver. SCART cables carry both picture and sound information from the source to the television, although when using an external audio amplifier and separate speakers to hear a soundtrack, the television volume needs to be turned right down. The minimum requirement of any television should be a SCART input which is the most widely used way of connecting a source component.

   
 

Composite Audio / Video

You will also find some televisions with a composite audio/video input. This consists of three phono sockets that carry left audio (red), right audio (white) and video (yellow) from the source to the television using phono cables. These connections can be found on the back of some televisions and on the front of televisions and video recorders for receiving signals from other composite video sources or camcorders.

   
 

S-Video

You may also find a high quality video-only input called S-Video. This is a single socket with four pins and works by separating the colour and brightness components of the video signal which reduces interference within the cable and produces a better picture. S-Video connections are a 4 pin DIN type, and can be found on most DVD players and the high quality S-VHS video recorders. When using S-Video to carry video signals, the sound information is carried along separate cables.

   
 

Phono Audio Outputs

Very useful if you want to send the sound from the television to an external amplifier or a processor with a built-in Dolby Pro-Logic decoder using a pair of phono audio interconnects.

   

FEATURES

These features are not essential but can be useful in some circumstances and may be standard features on some televisions.

 
   
 

Multi-standard

All televisions sold in the UK use the PAL picture standard. Televisions with the capability to display other formats such as NTSC and SECAM will allow imported software to be viewed, even if the source component can't convert the software standard to a PAL format.

   
 

100 hz Sampling

Most televisions operate at 50 hz, that is they update the screen picture 50 times per second. Some televisions produce a smoother picture by using 100 Hz technology enabling the picture to be updated 100 times per second.

   
 

Picture In Picture

Some televisions have two tuners that can allow two pictures to be displayed on the screen at the same time - handy if you are watching a programme and want to monitor another channel. Some widescreen sets also allow you to watch two programmes at the same time, one on the left side of the screen and one on the right side.

   
 

Digital TV Decoders

More and more televisions are being equipped with built-in receivers for digital television in the UK. The decoders generally receive digital terrestrial signals that are obtained from a standard roof mounted antenna, although a few sets are now being supplied with digital satellite receivers. These televisions mean that an external receiver is not required, thereby reducing cost and saving space.