LCD and plasma TVs: Features explained
LCD and plasma TVs – the basics
A slim, stylish Panasonic LCD TV
The beauty of LCD and plasma TVs is that they're much slimmer than conventional televisions (about 20cm to 30cm deep compared with 50cm to 60cm deep for a 32-inch conventional TV set with a cathode ray tube). LCD and plasma TVs take up less space, have bigger screens, can be mounted on walls and look incredibly stylish.
Standard-definition television (SDTV)
Most of us watch standard-definition TV images. These are made up of 576 horizontal lines stacked up to form a picture.
High-definition television (HDTV)
HDTV boasts roughly double the resolution of a standard-definition signal, making it more detailed and realistic. HDTV is available on Sky or Virgin for a monthly fee, or via Freesat for free.
To watch you'll also need an 'HD-ready' TV. However, not everything on the dedicated HD channels is actually recorded in HD. More programmes are being recorded in HD all the time, but content can be thin on the ground.
Plans are also afoot to launch HDTV channels on Freeview – starting on a regional basis in 2009. Details are still sketchy, but your LCD or plasma television will need to be an HD-ready TV, and you'll need a special digital box to receive the HD content. Without this box, no currently-available IDTVs, PVRs or set-top boxes will be able to receive the new channels.
1080i and 1080p
There are two main types of HD picture – 1080i and 1080p. HDTV is broadcast in 1080i, but high-definition Blu-ray discs are recorded in 1080p. 1080p is marginally more detailed and realistic, but the effect is really quite subtle.
Logos and labels on LCD and plasma TVs
HD-ready and HD-ready 1080p
The official logo
The HD-ready label means the LCD or plasma television has the minimum screen resolution (of at least 720 horizontal lines) and digital sockets (HDMI or DVI) to receive and display a 1080i HD picture – so they're perfect for watching HDTV from Sky, Virgin or Freesat. Most new HD-ready television sets will also support the 1080p HD signal. If the TV does not support 1080p, it simply switches to 1080i.
The relatively new HD-ready 1080p logo from EICTA (the same people behind HD-ready) means the LCD or plasma TV can process a 1080p signal, but also has a high screen resolution of 1080 horizontal lines (1920x1080). In theory, this should mean even better HD pictures, but in practice the quality of the TV picture has a lot more to do with the picture processing software that powers the set, than just the resolution of the screen.
For instance, many of our Best Buy Panasonic televisions have a relatively low screen resolution, but boast fantastic pictures.
Similar-sounding and looking logos such as, HD Full, 1080HD or 1080HD-ready are also commonplace, but exact meanings can differ between manufacturers.
24fps
The whole 1080i versus 1080p question is further complicated by something called 24fps (frames per second). It's not unusual for new TVs to sport logos boasting 1080/24 compatibility. This simply means that the TV can process the 1080p signal and display it on screen at 24 frames per second. The HD-ready 1080p logo is a guarantee of this but most new HD-ready television sets will process 1080/24 too.
1080/24 can become an issue if you want to watch Blu-ray movies on your TV. The high-definition discs are recorded at 24 frames per second , rather than the traditional European speed of 25fps. If the output from the player and the refresh rate on the TV screen don't match, the result can be juddery movements on camera-panning or fast motion scenes.
Look for the digital tick logo on your LCD or plasma TV
Digital tick, Freeview or DVB
The digital tick is an assurance that the LCD or plasma TV will work after the digital switchover. In reality, using the logo costs manufacturers money, so it’s not widely used. DVB and Freeview logos mean the LCD or plasma TV has a digital tuner built-in.
LCD and plasma TVs with digital processing
Many of the fancy-sounding labels refer to the digital-processing software used by LCD and plasma televisions. Philips uses Pixel Plus and Panasonic Vreal².
Decent processing software usually equals good pictures. For instance, most new Panasonic LCD and plasma TVs feature Vreal², and they all have decent pictures.
Colours
When a manufacturer claims an LCD or plasma TV can display more colours, it’s unlikely you’ll actually see more colours on screen. However, it's a sign of faster processing technology and potentially better picture quality.
100Hz
The 100Hz logo
This is one of the newest logos. It means an LCD or plasma television has digital-processing software, which should make panning and motion sequences marginally smoother.
LCD and plasma screen features
Native/screen resolution
This is the number of pixels or lines displayed on the television screen. Expressed as width x height, the highest screen resolution currently available is 1,920x1,080.
This is desirable for use with high definition material, but it doesn't necessarily equate to the best pictures for watching normal TV broadcasts or DVDs. A good LCD or plasma TV often relies far more on decent digital processing software.
Most LCD and plasma TVs have an aspect ratio of 16:9
Aspect ratio
The shape of the screen (width x height). Most LCD and plasma TVs are now widescreen, with an aspect ratio of 16:9. Older televisions and some portable TVs have an aspect ratio of 4:3. Digital TV is broadcast in a widescreen format.
Auto-format switching
It's a good idea to choose a widescreen LCD or plasma TV that automatically alters how different broadcasts are displayed – eg showing standard (4:3) broadcasts with black bands on either side so the images aren't stretched out of proportion. Most widescreen LCD and plasma televisions will do this.
Picture-in-picture
Picture-in-picture displays a small image in the corner of the TV screen while you watch the main image. Some LCD and plasma televisions let you watch another broadcast channel in this way – so you can check the progress of a football match, say.
However, with many of the LCD and plasma TVs in the Which? test, the picture-in-picture system lets you monitor only those pictures from external equipment, such as a DVD player or set-top box.
Still pictures on your LCD or plasma TV
With the popularity of digital cameras and photos stored on CDs, LCD and plasma TVs are increasingly used for 'slideshows'.
The main ways to display digital photos on screen are by connecting your digital camera to one of the TV's audio-visual (Scart or phono) inputs, or by watching picture CDs via a DVD player, but memory card and USB ports are increasingly common.
Memory card slots and USB ports
Many of the latest LCD and plasma TVs are equipped with memory card slots that let you plug the card from your digital camera directly into the TV. More common are USB ports for connecting USB memory sticks or digital equipment to your television.
Either way, the picture quality is typically excellent. As an added bonus, the USB option sometimes allows playback of MP3 music files via your TV's speakers.
Power saving features
Eco modes
Many new LCD and plasma TVs have eco or energy-saving settings. Occasionally, this can be slightly misleading and may refer only to an option to switch off the front panel LED – making a negligible power saving.
Some television manufacturers have also taken to adding a quick-start standby mode. This allows the TV set to be turned on marginally quicker than from regular standby, but often uses considerably more power. Some energy-saving modes can simply involve switching the wasteful quick-start option off.
The most effective energy-saving modes will usually involve an ambient light sensor.
Ambient light sensor
If selected an ambient light sensor will automatically adjust the brightness of the TV's back-light, according to how dark or light the room is. In dark conditions, the most efficient sensors can dramatically reduce a television's power consumption – slashing a typical 100 watt reading for a 32-inch TV screen in half.
Radio blanking
Some TVs can blank the screen when tuned to a digital radio channel, saving power in the process. It’s still not quite as green as listening via a typical tabletop DAB radio, but can significantly reduce energy consumption. On average, a TV with radio blanking activated consumes around 20 watts. For larger TVs, that can slash around 100 watts off the total. On smaller television sets the effect is less dramatic, but power use is still typically cut in half.
On/Off switches
Many new TVs have ‘soft’ on/off switches rather than traditional mechanical buttons. These have the advantage of being less prone to breaking. However, in the absence of any moving parts, the ‘soft’ on/off switch requires an electrical current to turn the set back on – meaning many LCD and plasma TVs consume power even when they are switched off.
The power used is low (usually in the region of 0.2 to 0.5 watts), but if you truly want to switch your TV set off, the only choice may be to switch it off at the mains.
For more on this subject, see energy saving applicances.
Electronic Programming Guide (EPG)
LCD and plasma TV's have an on-screen channel guide
Found on all IDTVs, this is an on-screen channel guide showing programming for the week ahead – a bit like having an electronic copy of the Radio Times at the touch of a button, on your LCD or plasma TV screen.
The style and format of an EPG depends on the particular model of LCD or plasma TV, but most show programmes at least seven days ahead, plus a 'Now and Next' option.
The best EPGs show several channels over a fixed time period, say two hours, making comparing channels and planning an evening's viewing more convenient. Some also display a handy 'picture-in-picture' of the current channel in the corner of the TV screen.
Audio description
An additional narration for visually-impaired people that describes significant visual information, such as body language and scenery. The service is available on Sky and Freeview.
Only a few of the latest LCD and plasma TVs (mostly Panasonic and Sony) can decode audio description on Freeview. A schedule of Freeview programmes with audio description on the DTG website.
Text and digital text
With a set-top box or integrated digital TV, you can access the digital text services available on some digital channels. These look like internet pages, and some let you watch an inset of the TV picture at the same time.
Sockets and plugs on LCD and plasma TVs
RF input
This is the socket for your aerial and allows the broadcast signal to be received by your tuner.
Scart inputs
Scarts are the best way to connect equipment like DVD players and VCRs to your television. Most LCD and plasma TVs come with at least two Scart sockets. If you need more, you can buy a Scart switching box for £10 or so to expand your LCD or plasma TV's capacity.
For the best picture, look for Scarts that support the high-standard RGB signal. This splits the video signal into its red, blue and green components to give an improved picture.
Composite video and s-video input
If you're short of Scart inputs, composite video and s-video are an alternative. S-Video signals are split into colour and brightness but are slightly inferior to Scart RGB.
Composite video (usually a yellow phono socket) is the lowest-quality video connection.Both let you plug other AV equipment, such as camcorders and games consoles, directly into your LCD or plasma TV.
HDMI input
VGA input to connect your PC
If you're interested in HD, this is the high-capacity input for high-definition video and audio signals.Two HDMI sockets mean you could plug in both an HD set-top box and an HD DVD player to your LCD or plasma TV.
VGA input
An analogue VGA input lets you connect your PC – effectively turning your LCD or plasma TV into a PC monitor. Some LCD and plasma TVs can also be connected via a digital input. This can either be a DVI socket or now, more commonly, an HDMI input configured to support PC screen resolutions.
Component video input
This is a high quality video input made up of three sockets coloured red, green and blue.
Component video input
Also known as YPbPr, it splits the video signal into three separate parts for an improved picture on your LCD or plasma TV.
However, component connections are still not widely used on AV equipment such as televisions, and unlike Scart sockets they don't carry the widescreen switching signal.
Phono socket
These red and white sockets allow you to connect your LCD or plasma TV to a stereo amplifier – useful if the built-in speakers aren't quite up to the job.
Coaxial and optical outputs
Optical output
Many LCD and plasma TVs have 'virtual' surround sound: they mimic the effect using the two main speakers, but this is usually disappointing. The best solution for good-quality surround sound is a dedicated home cinema system.
If you want to connect your LCD or plasma TV directly to a surround sound system there are two types of digital connections – coaxial (wire) and optical (fibre optic). Make sure your surround sound system input matches the input on your LCD or plasma television.
However, digital surround-sound on Freeview is virtually non-existent, so to make use of the socket, surround-sound signals from other pieces of equipment (such as DVD players or Sky boxes) have to be channeled through the television – a handy trick that only works on some LCD and plasma TV models.
Common interface (CI) port
Setanta Sports and Top-Up TV are additional subscription services to Freeview and require a smart card to watch. Most Top-Up TV viewers will use a special Top-Up receiver/PVR but Setanta viewers can use any IDTV, set-top box or PVR that has a card reader.
The card reader fits into the CI port – and according to a European directive this CI port must be present on any TV with a DVB-T (Freeview) tuner. Occasionally we do come across models without a CI port, which won’t be of any interest to most consumers but nevertheless makes the product technically illegal.
The card reader or CAM (conditional access modules) which slots into the CI port costs about £40-£50.
Still confused? Check out our TV jargon buster. And for more advice, check our guide to buying TVs.