LCD or Plasma TV - Which is the best?

What is the difference between LCD and Plasma Televisions?


Comparison of the flat screen tv technologies

When it comes to flat screen TVs the two technologies LCD and Plasma look very similar with almost lifelike images and the ability to be hung on the wall. Although LCD tvs and Plasma tv panels may look very similar in the shops, there are various differences between the two technologies.

How LCD tvs work

LCD means Liquid Crystal Display. The LCD tv screen is a thin, flat display device comprised of two clear panels that have a number of colour liquid crystal-filled pixels arrayed between them. The crystals twist or untwist and reposition themselves to either let light pass through or block light and this results in a picture being displayed when millions of crystals do this concurrently. The reposition of the crystals is triggered by a small voltage and uses very little power. The LCD tv screen is backlit so this behaviour creates light or dark spots on the screen and colour depending on the pixels that are repositioned. LCD tvs are available in sizes from a few inches to over 108 inches. All top manufacturers have LCD televisions including Sony, Panasonic, Philips, JVC, Toshiba, Hitachi, Samsung, LG, Pioneer and Sharp.

How plasma tvs works

A Plasma tv screen comprises of millions of minuscule 'light bulbs' which are tiny glass cells filled with inert gases such as xenon and neon. These cells are illuminated by a current being applied to electrodes in the gas filled cell and its atoms become 'excited' to a plasma and emit photons of ultraviolet light. These photons in turn hit a phosphor coating which emits visible light. The colour of the visible light emitted by each cell depends on the three different coloured phosphors - red, blue and green, and can together make billions of colours when combined. As with the LCD tv screen, the millions of cells intermix to form the image on the screen. Currently the only manufacturers of Plasma tvs in the UK are Panasonic, Pioneer, Philips, LG, and Samsung. Plasma tvs are available in sizes from 32 inches to 150 inches.

Performance and Picture quality compared

Brightness

LCD TVs can be brighter than plasma TVs. This perception of this brightness is of course reliant on where the TV is situated and what is being watched. In reality both technologies are capable of producing a level of brightness that is in excess of what is needed in normal viewing.

Contrast Ratio and Black Levels

The contrast ratio is a measure of the difference in light and dark tones that a panel can produce - in general a high ratio means greater details can be discerned. Historically LCD tv panels have had a lower contrast ratio than plasma tvs because the backlight bleeds through darkened pixels and lightens the image. Recent advances in technology have produced techniques to thwart light leakage, and improvecontrast ratios so that they are more comparable with Plasma tv, but still not as good. Because each cell on a plasma tv is able to be switched off rather than blocking the light as per LCD tvs the blacks are blacker. For a television picture, the black level is very important because black encompasses the entire spectrum of colour. Thus the deepest blacks create the richest colours and thus more realism. Without deep black levels the colours look more 'pastel' like. Typically the black on an LCD tv screen is more 'grey' when compared to the plasma tvs black.

Colour Saturation

This is a gauge of the correctness of the colours on the screen based on the presence of grey shades - the higher grey shades results in lower colour saturation. Plasma TVs have high colour saturation due to the way they emit light. The capability of Plasma tv pixels to be switched off when they are not in use stops the emission of stray light that diffuses colour. This is why tints and hues on Plasma TVs are noticeably more vivid and vibrant

Colour Gamut

Is the breadth and amount of colours that can be displayed. The most expensive models are now claiming to have colour gamut's getting quite close to the full spectrum for plasma tv and LCD tv. In fact most plasma TVs tend to be better than most LCD tvs apart from the top of the range ones. With the cheapest LCD tv models more often than not offering a colour gamut that isn’t as good the higher LCD tv models. So as a rule the plasma tv has the best colour gamut.

Resolution

This is the quantity of pixels that make up the screen. The higher the resolution is, the higher the definition and the sharper picture is. Currently, LCD HDTV’s create the image at 1920 pixels x 1080 pixels, full 1080p resolution at a lower cost than plasma tv panels of the same size. There is no difference in an HD LCD tv or Plasma tv for screen sizes above 37 inches. Though plasma tv screens of 37 inches and below are at present only HD Ready but LCD tv models are available from 32 inches upwards in full HD or 1080P.

Response Time and Refresh Rate

These two attributes in combination establish how fast a moving picture a screen can reproduces without the image blurring. Response time is a measure of how quickly a screen can vary when an input is received. Historically LCD tv panels had slow response times which was the limiting factor causing motion blur because each pixel has to go from an on state, to an off state, and back to on in order to refresh an image. Improvements in pixel response times on LCD tv screens means that the actual response time isn't the main cause of motion blur, its mostly caused by the refresh rate, or the frame rate.

All LCD tvs and Plasma tvs have until of late had frame rates of 50 frames per second or 50hz. The more expensive LCD tv and Plasma tv models now have 100 Hz to compensate for any motion blur. Since the normalsignal is only 50 Hz the additional frames are created with signal processing software which interpolates what the add-on middle frames ought to look like. The consequence is moving pictures that loose hardly any definition and are more fluid. The best Plasma tv screens nonetheless respond better to rapid motion than LCD tv but the difference has lessened as the best LCD tvs motion response time has improved and 100hz and 200hz has been introduced.

Viewing Angle

Pictures on plasma TVs are nevertheless clearly viewable at about 160 degrees and on some models up to 180 degrees. the picture dulls further than about 100 degrees.

The screen surface of lcd tvs and plasma tvs

LCD tv screens are available with matt finish screens which lessen glare whereas Plasma tvs have a reflective screen.

Burn-in

This can result if a static image is displayed on the screen for an extended time, and even once the image is changed or removed, the 'ghost image' of the previously displayed static image is still visible on the screen for the rest of the screens life. burn-in doesn’t take place on LCD tvs. Though the expose of burn-in on plasma tv is usually exaggerated and not likely.

Image retention

A lot of people mix up burn-in with image retention which is very similar. With image retention the 'ghost image' disappears quickly either once a new, bright image is displayed or after a few seconds. image retention is infrequently noticed but normal on plasma tvs because of the technology used, but it can be minimised by having a 'break-in' period when the plasma tv is first bought. The break-in period normally lasts 100 hours, during this time you shouldn't view any programs that don't fill in the whole screen, and you should notview any programmingthat have static images such as bright station logos or news scrolls at the bottom of screens, and you should lower the contrast and brightness to a mid level. Nowadays there are also features built in to the plasma tvs to decrease the possibility of either burn-in or image retention.

Power consumption

LCD tvs have a backlight that is alwayson and uses virtually constant power. LCD tvs usually have an adjustable back light which uses more power when it is on a high setting and not as much of on a low setting. The power required to alter the pixels is infinitesimal.

But Plasma tvs charge a gas to a plasma to create light. The more light that is required the more often this is done. So it's normal for plasma tvs to require more energy on an image with high levels of brightness, and less energy on low brightness scenes. Accordingly the power consumption varies.

On paper it might appear that the Plasma tvs employ a lot more power than LCD tvs. Plasma tv manufacturers tend to quote the highest power usage at full brightness. However the plasma tvs power power consumption varies depending on the signal and the amount dark and bright areas on the screen. Studies have revealed that when watching mainly dark programs and movies the average power power consumption of an identical sized plasma tv is really lower than LCD tv. However if lots of cartoons and sport are viewed then the LCD tv uses less power. Consequently on average with varied viewing content there is little difference between LCD tvs and Plasma tvs. Plasma tv manufacturers are shortly going to be launching models that will cut the power consumption by over half.

Life expectancy

Plasma tv manufacturers are nowadays quoting statistics of 100000 hours for the life expectancy. This represents a usage level of almost 11.5 years of non stop use. Thus any concerns concerning the life expectancy of plasma tvs being less than LCD tvs are unfounded.

Conclusion

Both technologies have benefits. Plasmas tvs typically have a better subjective picture with better black level, higher contrast, and superior colour rendering than LCD TVs. While LCD TVs have higher brightness, freedom from screen burn-in worries, and are lighter and thinner. This is not always the case becausea good LCD TV could have a better picture than an middling or poor plasma TV. Nevertheless on balance I consider that a plasma tv is the superior option with extra advantages. In the end you get what you pay for so spend as much as you can find the money for on you preferred format.

For more information go to Discount LCD TV and Discount Plasma TV