[b]Are there any differences between the two technologies?[/b]
Both LCD tvs and Plasma tvs appear to give similar levels of performance. So is there any real difference? Both are slim and can be hung on the wall. Many people will incorrectly refer to small screens as plasma tvs when they are LCD tvs. However both technologies work and perform very differently. What is the difference between the two technologies?
How does an LCD (Liquid Crystal Display) television 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 together. The reposition of the crystals is caused 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 leading manufacturers have LCD televisions including Sony, Panasonic, Philips, JVC, Toshiba, Hitachi, Samsung, LG, Pioneer and Sharp.
How does a Plasma television work ?
A Plasma tv screen comprises of millions of microscopic '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 strike a phosphor coating which emits visible light. The colour of the visible light emitted by each cell depends on the three different coloured phosphors - green, blue and red, and can together make billions of colours when combined. As with the LCD tv screen, the millions of cells combine 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 existing in sizes from 32 inches to 150 inches.
Performance and Picture quality compared
Brightness
The picture on LCD tv screens can be brighter than Plasma tvs. Depending on where the television is located and what is being viewed will determine how this difference in screen brightness is perceived. However both Plasma tv and LCD tv screens are capable of producing brightness levels that in normal viewing conditions are in excess of what is needed.
[b]The effect of the Contrast Ratio and the Black Levels.[/b]
The contrast ratio is a measure of the variance 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 poorer contrast ratio than plasma tvs because the backlight bleeds through darkened pixels and lightens the image. New advances in technology have created techniques to prevent light leakage, and increasecontrast 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 significant because black encompasses the entire spectrum of colour. And so, the deepest blacks generate 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
The colour saturation measures the accuracy of how colours are presented on the screen in the presence of grey shades. A higher grey shade will result in lower colour saturation. The colour saturation of a Plasma tv screen is high because of their black levels, their low grey shades, and their ability to switch off pixels when they aren't in use, thus preventing colours being diffused by the stray light emissions. Hence the tints and hues are visibly more colourful and more life like.
Colour Gamut
The colour gamut is a measure of the number of colours that a screen can display. For the most expensive models of LCD tvs and Plasmas tvs the manufacturers are now claiming to have colour gamuts very close to the full spectrum. Again on a like for like basis the Plasma tvs still out perform the LCD tvs on all but the most expensive models. This is because on cheaper LCD tv models the colour gamut isn't as good as the top LCD tv models from the same manufacturer. Whereas for Plasma tvs the difference isn't as great.
[b]Screen Resolution[/b]
This can be defined as the amount of information shown on a screen. The more information that is on a screen the higher the quality of the image. The higher resolution usually means that the screen can display a higher quality image with more detail and sharpness. The resolution is measure in pixels. LCD HDTVs and Plasma HDTVs (High Definition Televisions) have a resolution of 1920 pixels x 1080 pixels or 1080P. Where '1080' is the vertical resolution and 'P' is progressive scan meaning that the image isn't interlaced. Usually LCD HDTVs are cheaper than the same sized Plasma's. HD plasma are available in sizes of 42 inches upwards whereas LCD HDTVs are available from 32 inches upwards. Therefore at sizes 32 inches to 37 inches LCD tvs have the advantage of offering 1080P HD compared to the 720P (1280 pixels x720 pixels) HD Ready Plasma tvs. At sizes less than 32 inches there aren't any plasma tv models.
[b]Refresh Rate and Response Time of the screen[/b]
These two attributes in combination influence how fast a moving picture a screen can reproduces without the image blurring. Response time is a measure of how quickly a screen can change 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 by and large caused by the refresh rate, or the frame rate.
Lower model of LCD televisions and Plasma televisions operate at a frame rate of 50hz or 50 frames per second. In fact until recently, before 100hz models were launched, all models operated at 50 Hz. Now on more expensive models of LCD tv and Plasma tv motion blur is reduced with the addition of 100hz which create an extra frame that is placed between the normal frames. Because a normal signal is 50 Hz an additional middle frames is created by signal processing software that interpolates what the extra middle frame should look like. This results in picture motion that is more fluid and looses little if any definition. However the best Plasma tvs still show fast moving images better than the best LCD tvs but the difference is narrowing because the LCD tvs response time has reduced and 100hz and 200hz models have been established.
[b]The Viewing Angle of the screen[/b]
This is the maximum side angle that a viewer can see the image on the screen clearly. Plasma tvs usually have a viewing angle of between 160 degrees to 180 degrees whereas LCD tvs have a viewing angle of around 100 degrees after which the picture dulls.
[b]The screen surface[/b]
A plasma tvs screen is a shinny reflective surface which can suffer from glare depending on the room conditions, whereas LCD tv screens have matt finish that reduces glare.
Burn-in
This is characterised by a 'ghost image' of a previously displayed static image that had been displayed for a prolonged period of time and is still present. Even if the screens image is changed from the original 'ghost image' or removed it is present for the rest of the plasma tvs life. For LCD tv screens burn-in isn't a problem no matter how long the static image is displayed. Nonetheless the burn-in risk is overstated and improbable in normal viewing conditions.
Image retention
This is often confused with burn-in which appears to be similar but it isn't permanent. The 'ghost images' vanish quickly with image retention when a new bright image appears or after a few seconds. For technical reasons image retention is normal and present on Plasma tvs but hardly ever noticed. This effect can be minimised by having a 'break-in' period for the first 100 hours of the plasma tvs life. During this period you should watch programs that fill the whole screen and don't have any bright static images such as station logos or news scrolls at the bottom of the screen. You should also reduce the brightness and contrast to a middle level. The latest Plasma televisions have circuits built in to them to greatly reduce the chance of either image retention or burn-in.
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 necessary to modulate the pixels is infinitesimal.
Because Plasma TVs charge the gas in the individual pixels to a plasma to create the light, and the more light that is required on a scene the more energy is used. So pictures with low brightness in them use less energy, and high brightness more energy i.e. the power consumption varies.
The energy requirements that are quoted for Plasma tvs are for full brightness settings. The effect of this is that lcd tvs seem to use less power than plasma tvs. But the power consumption of a plasma tv varies depending on the amount of dark and bright areas on the displayed image. Studies have found that when the viewed programs are mainly dark or on movies the amount of power consumed for plasma tvs will be lower than an lcd tv. However when the viewed programs are sports and cartoons the power consumption for plasma tvs is greater than on lcd tvs. When varied programs are viewed the power consumption is similar for LCD tvs and Plasma tvs. Future plasma tvs are going to consume less than half the amount power consumed at present.
Life expectancy of Plasma televisions
Plasma tv manufacturers are nowadays quoting statistics of 100000 hours for the life expectancy. This represents a running level of just about 11.5 years of non stop use. Hence any concerns about the life expectancy of plasma tvs being less than LCD tvs are unfounded.
Conclusion
Both lcd tvs and plasma tvs are able to offer pros and cons. The lcd tvs have higher brightness and no chance of any screen burn. They are also available in thinner designs and they are lighter. When comparing picture quality the plasma tv have more life like colours, higher contrast and blacks that are blacker than lcd tvs. This is not necessarily the case for all plasma tvs compared to lcd tvs. A budget plasma tv will be out performed by a top of the range LCD tv. On balance when the pros and cons are considered a plasma tv is the obvious choice but spend as much as to can on one. - 16492
Both LCD tvs and Plasma tvs appear to give similar levels of performance. So is there any real difference? Both are slim and can be hung on the wall. Many people will incorrectly refer to small screens as plasma tvs when they are LCD tvs. However both technologies work and perform very differently. What is the difference between the two technologies?
How does an LCD (Liquid Crystal Display) television 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 together. The reposition of the crystals is caused 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 leading manufacturers have LCD televisions including Sony, Panasonic, Philips, JVC, Toshiba, Hitachi, Samsung, LG, Pioneer and Sharp.
How does a Plasma television work ?
A Plasma tv screen comprises of millions of microscopic '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 strike a phosphor coating which emits visible light. The colour of the visible light emitted by each cell depends on the three different coloured phosphors - green, blue and red, and can together make billions of colours when combined. As with the LCD tv screen, the millions of cells combine 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 existing in sizes from 32 inches to 150 inches.
Performance and Picture quality compared
Brightness
The picture on LCD tv screens can be brighter than Plasma tvs. Depending on where the television is located and what is being viewed will determine how this difference in screen brightness is perceived. However both Plasma tv and LCD tv screens are capable of producing brightness levels that in normal viewing conditions are in excess of what is needed.
[b]The effect of the Contrast Ratio and the Black Levels.[/b]
The contrast ratio is a measure of the variance 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 poorer contrast ratio than plasma tvs because the backlight bleeds through darkened pixels and lightens the image. New advances in technology have created techniques to prevent light leakage, and increasecontrast 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 significant because black encompasses the entire spectrum of colour. And so, the deepest blacks generate 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
The colour saturation measures the accuracy of how colours are presented on the screen in the presence of grey shades. A higher grey shade will result in lower colour saturation. The colour saturation of a Plasma tv screen is high because of their black levels, their low grey shades, and their ability to switch off pixels when they aren't in use, thus preventing colours being diffused by the stray light emissions. Hence the tints and hues are visibly more colourful and more life like.
Colour Gamut
The colour gamut is a measure of the number of colours that a screen can display. For the most expensive models of LCD tvs and Plasmas tvs the manufacturers are now claiming to have colour gamuts very close to the full spectrum. Again on a like for like basis the Plasma tvs still out perform the LCD tvs on all but the most expensive models. This is because on cheaper LCD tv models the colour gamut isn't as good as the top LCD tv models from the same manufacturer. Whereas for Plasma tvs the difference isn't as great.
[b]Screen Resolution[/b]
This can be defined as the amount of information shown on a screen. The more information that is on a screen the higher the quality of the image. The higher resolution usually means that the screen can display a higher quality image with more detail and sharpness. The resolution is measure in pixels. LCD HDTVs and Plasma HDTVs (High Definition Televisions) have a resolution of 1920 pixels x 1080 pixels or 1080P. Where '1080' is the vertical resolution and 'P' is progressive scan meaning that the image isn't interlaced. Usually LCD HDTVs are cheaper than the same sized Plasma's. HD plasma are available in sizes of 42 inches upwards whereas LCD HDTVs are available from 32 inches upwards. Therefore at sizes 32 inches to 37 inches LCD tvs have the advantage of offering 1080P HD compared to the 720P (1280 pixels x720 pixels) HD Ready Plasma tvs. At sizes less than 32 inches there aren't any plasma tv models.
[b]Refresh Rate and Response Time of the screen[/b]
These two attributes in combination influence how fast a moving picture a screen can reproduces without the image blurring. Response time is a measure of how quickly a screen can change 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 by and large caused by the refresh rate, or the frame rate.
Lower model of LCD televisions and Plasma televisions operate at a frame rate of 50hz or 50 frames per second. In fact until recently, before 100hz models were launched, all models operated at 50 Hz. Now on more expensive models of LCD tv and Plasma tv motion blur is reduced with the addition of 100hz which create an extra frame that is placed between the normal frames. Because a normal signal is 50 Hz an additional middle frames is created by signal processing software that interpolates what the extra middle frame should look like. This results in picture motion that is more fluid and looses little if any definition. However the best Plasma tvs still show fast moving images better than the best LCD tvs but the difference is narrowing because the LCD tvs response time has reduced and 100hz and 200hz models have been established.
[b]The Viewing Angle of the screen[/b]
This is the maximum side angle that a viewer can see the image on the screen clearly. Plasma tvs usually have a viewing angle of between 160 degrees to 180 degrees whereas LCD tvs have a viewing angle of around 100 degrees after which the picture dulls.
[b]The screen surface[/b]
A plasma tvs screen is a shinny reflective surface which can suffer from glare depending on the room conditions, whereas LCD tv screens have matt finish that reduces glare.
Burn-in
This is characterised by a 'ghost image' of a previously displayed static image that had been displayed for a prolonged period of time and is still present. Even if the screens image is changed from the original 'ghost image' or removed it is present for the rest of the plasma tvs life. For LCD tv screens burn-in isn't a problem no matter how long the static image is displayed. Nonetheless the burn-in risk is overstated and improbable in normal viewing conditions.
Image retention
This is often confused with burn-in which appears to be similar but it isn't permanent. The 'ghost images' vanish quickly with image retention when a new bright image appears or after a few seconds. For technical reasons image retention is normal and present on Plasma tvs but hardly ever noticed. This effect can be minimised by having a 'break-in' period for the first 100 hours of the plasma tvs life. During this period you should watch programs that fill the whole screen and don't have any bright static images such as station logos or news scrolls at the bottom of the screen. You should also reduce the brightness and contrast to a middle level. The latest Plasma televisions have circuits built in to them to greatly reduce the chance of either image retention or burn-in.
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 necessary to modulate the pixels is infinitesimal.
Because Plasma TVs charge the gas in the individual pixels to a plasma to create the light, and the more light that is required on a scene the more energy is used. So pictures with low brightness in them use less energy, and high brightness more energy i.e. the power consumption varies.
The energy requirements that are quoted for Plasma tvs are for full brightness settings. The effect of this is that lcd tvs seem to use less power than plasma tvs. But the power consumption of a plasma tv varies depending on the amount of dark and bright areas on the displayed image. Studies have found that when the viewed programs are mainly dark or on movies the amount of power consumed for plasma tvs will be lower than an lcd tv. However when the viewed programs are sports and cartoons the power consumption for plasma tvs is greater than on lcd tvs. When varied programs are viewed the power consumption is similar for LCD tvs and Plasma tvs. Future plasma tvs are going to consume less than half the amount power consumed at present.
Life expectancy of Plasma televisions
Plasma tv manufacturers are nowadays quoting statistics of 100000 hours for the life expectancy. This represents a running level of just about 11.5 years of non stop use. Hence any concerns about the life expectancy of plasma tvs being less than LCD tvs are unfounded.
Conclusion
Both lcd tvs and plasma tvs are able to offer pros and cons. The lcd tvs have higher brightness and no chance of any screen burn. They are also available in thinner designs and they are lighter. When comparing picture quality the plasma tv have more life like colours, higher contrast and blacks that are blacker than lcd tvs. This is not necessarily the case for all plasma tvs compared to lcd tvs. A budget plasma tv will be out performed by a top of the range LCD tv. On balance when the pros and cons are considered a plasma tv is the obvious choice but spend as much as to can on one. - 16492
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