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 tvs panels may look very similar in the shops, there are many differences between the two technologies.
LCD screens explained
The LCD tv screen is a thin flat display device and is made up of a two clear panels which have many colour liquid crystal filled pixels that are arranged in arrays in between them. When a small voltage is applied to the crystals they twist or untwist repositioning themselves so that light can either pass through or it is blocked. When millions of crystals do this a picture is displayed. Very little power is used in this process. Behind the screen is a back light that illuminates the pixels and displays a colour depending on their colour (either red, blue or green), also areas of light and dark spots are displayed depending on how they are positioned. LCD devices are available in small sizes for items such as a watch up to 108 inches. Most television manufacturers produce LCD television including Hitachi, JVC, LG, Panasonic, Pioneer, Philips, Samsung, Sharp, Sony, and Toshiba.
How plasma tvs works
A Plasma tv screen comprises of millions of tiny 'light bulbs' which are small glass cells filled with inert gases such as xenon and neon. These cells are lit 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 - green, blue and red, and can together produce 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 Samsung, Philips, LG, Panasonic, and Pioneer. Plasma tvs are available in sizes from 32 inches to 150 inches.
A comparison of the Picture quality and Performance
The Brightness of the picture
LCD tv screens are able to produce a brighter picture than a Plasma screen. How noticeable or useable this difference is will depend on the location of the screen and what is being viewed. But in normal viewing conditions both LCD televisions and Plasma televisions are able to produce more than enough picture brightness.
The effect of the Contrast Ratio and the Black Levels.
This is a measure of the difference of the luminosity of the brightest white on the screen and the darkest black. So a contrast ratio of 3000:1 means that the brightest white is 3000x brighter than the darkest black. Details can be more easily differentiated the higher the contrast ratio is as long as the the black levels aren't 'grey'. Previous models of LCD tvs had lower contrast ratio than plasma tvs because the pixels weren't able to block the back light for dark areas and the light would leak through making the image lighter. Improvements in technology have reduced this leakage so that the contrast ratio is much closer to those of plama tvs. But ultimately plasmas are able to produce blacker blacks because the pixel cells are able to be switched off instead of blocking the light as lcd tvs do. The blacker the black on a tv the better the picture quality it is able to produce. The colour saturation or colour palette is affected if the blacks aren't black enough . When the black level on a plasma is compared with the black level on an comparable priced LCD tv, the plasma tv black often makes the LCD tv black look grey.
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
Is the breadth and number of colours that can be displayed. The most expensive models are now claiming to have colour gamut's getting rather close to the full spectrum for plasma tv and LCD tv. In fact most plasma TVs have a propensity to be better than most LCD tvs apart from the top of the range ones. With the cheapest LCD tv models usually 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.
Screen Resolution
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'20 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.
Refresh Rate and Response Time of the screen
The combination of these two characteristics affects how a screen can handle fast moving pictures without blurring. The gauge of how quickly a screen can change when an input signal is received is the response times. In the past motion blur on LCD tvs was caused by slow response times where the pixels took too long to change state from, on to off, and back on to refresh an image. The latest models of LCD tv screens have improved pixel response times that now mean that actual response time is no longer the cause of motion blur. The main cause is now the frame rate refresh rate.
All LCD tvs and Plasma tvs have until a short time ago had frame rates of 50 frames per second or 50hz. The more costly LCD tv and Plasma tv models now have 100 Hz to compensate for any motion blur. Since the standard signal is only 50 Hz the added frames are fashioned with signal processing software which interpolates what the extra middle frames should look like. The result is moving pictures that loose little to no definition and are more fluid. The best Plasma tv screens still respond better to fast motion than LCD tv but the variation has narrowed as the best LCD tvs motion response time has improved and 100hz and 200hz has been introduced.
The Viewing Angle of the screen
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'0 degrees whereas LCD tvs have a viewing angle of around 100 degrees after which the picture dulls.
[b]The screen surface[/b]
Plasma tvs have reflective shinny screen surface which can be affected by glare depending on the viewing conditions. Lcd tvs have a matt finish which reduces glare.
Image 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.
[b]Screen Image retention[/b]
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.
[b]Is there any difference in power consumption of LCD tvs or Plasma tvs ?[/b]
LCD tvs have a backlight that is constantlyon and uses virtually constant power. LCD tvs usually have an adjustable back light which uses extra power when it is on a high setting and less on a low setting. The power required to alter 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.
On paper it might seem that the Plasma tvs use a lot more power than LCD tvs. Plasma tv manufacturers have a tendency to quote the highest power usage at full brightness. Although the plasma tvs power power consumption varies depending on the signal and the amount dark and bright areas on the screen. Studies have shown that when watching mainly dark programs and movies the average power power consumption of an identical sized plasma tv is in reality lower than LCD tv. Then again if lots of cartoons and sport are viewed then the LCD tv consumes less power. So 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 reduce the power consumption by over half.
Life expectancy
It is common myth that is quoted that plasma tv screens don't last very long. However manufacturers such as Panasonic are quoting a life expectancy of 100000 hours which is 11.5 years of continuous use. Therefore any concerns are unsubstantiated
Conclusion - which is the best?
Plasma televisions and LCD televisions both have advantages and disadvantages. LCD tvs have higher brightness, no concerns about screen burn, and they are thinner and lighter. But Plasma tvs have a better real world picture with a higher contrast, blacker blacks, and more natural colours than LCD tvs. Obviously not all Plasma tvs are better than all LCD tvs. A top specification LCD tv will out perform a cheap plasma tv. If you weigh up the advantages and disadvantages a good plasma tv is the best option but you do get what you pay for. - 29967
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 tvs panels may look very similar in the shops, there are many differences between the two technologies.
LCD screens explained
The LCD tv screen is a thin flat display device and is made up of a two clear panels which have many colour liquid crystal filled pixels that are arranged in arrays in between them. When a small voltage is applied to the crystals they twist or untwist repositioning themselves so that light can either pass through or it is blocked. When millions of crystals do this a picture is displayed. Very little power is used in this process. Behind the screen is a back light that illuminates the pixels and displays a colour depending on their colour (either red, blue or green), also areas of light and dark spots are displayed depending on how they are positioned. LCD devices are available in small sizes for items such as a watch up to 108 inches. Most television manufacturers produce LCD television including Hitachi, JVC, LG, Panasonic, Pioneer, Philips, Samsung, Sharp, Sony, and Toshiba.
How plasma tvs works
A Plasma tv screen comprises of millions of tiny 'light bulbs' which are small glass cells filled with inert gases such as xenon and neon. These cells are lit 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 - green, blue and red, and can together produce 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 Samsung, Philips, LG, Panasonic, and Pioneer. Plasma tvs are available in sizes from 32 inches to 150 inches.
A comparison of the Picture quality and Performance
The Brightness of the picture
LCD tv screens are able to produce a brighter picture than a Plasma screen. How noticeable or useable this difference is will depend on the location of the screen and what is being viewed. But in normal viewing conditions both LCD televisions and Plasma televisions are able to produce more than enough picture brightness.
The effect of the Contrast Ratio and the Black Levels.
This is a measure of the difference of the luminosity of the brightest white on the screen and the darkest black. So a contrast ratio of 3000:1 means that the brightest white is 3000x brighter than the darkest black. Details can be more easily differentiated the higher the contrast ratio is as long as the the black levels aren't 'grey'. Previous models of LCD tvs had lower contrast ratio than plasma tvs because the pixels weren't able to block the back light for dark areas and the light would leak through making the image lighter. Improvements in technology have reduced this leakage so that the contrast ratio is much closer to those of plama tvs. But ultimately plasmas are able to produce blacker blacks because the pixel cells are able to be switched off instead of blocking the light as lcd tvs do. The blacker the black on a tv the better the picture quality it is able to produce. The colour saturation or colour palette is affected if the blacks aren't black enough . When the black level on a plasma is compared with the black level on an comparable priced LCD tv, the plasma tv black often makes the LCD tv black look grey.
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
Is the breadth and number of colours that can be displayed. The most expensive models are now claiming to have colour gamut's getting rather close to the full spectrum for plasma tv and LCD tv. In fact most plasma TVs have a propensity to be better than most LCD tvs apart from the top of the range ones. With the cheapest LCD tv models usually 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.
Screen Resolution
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'20 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.
Refresh Rate and Response Time of the screen
The combination of these two characteristics affects how a screen can handle fast moving pictures without blurring. The gauge of how quickly a screen can change when an input signal is received is the response times. In the past motion blur on LCD tvs was caused by slow response times where the pixels took too long to change state from, on to off, and back on to refresh an image. The latest models of LCD tv screens have improved pixel response times that now mean that actual response time is no longer the cause of motion blur. The main cause is now the frame rate refresh rate.
All LCD tvs and Plasma tvs have until a short time ago had frame rates of 50 frames per second or 50hz. The more costly LCD tv and Plasma tv models now have 100 Hz to compensate for any motion blur. Since the standard signal is only 50 Hz the added frames are fashioned with signal processing software which interpolates what the extra middle frames should look like. The result is moving pictures that loose little to no definition and are more fluid. The best Plasma tv screens still respond better to fast motion than LCD tv but the variation has narrowed as the best LCD tvs motion response time has improved and 100hz and 200hz has been introduced.
The Viewing Angle of the screen
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'0 degrees whereas LCD tvs have a viewing angle of around 100 degrees after which the picture dulls.
[b]The screen surface[/b]
Plasma tvs have reflective shinny screen surface which can be affected by glare depending on the viewing conditions. Lcd tvs have a matt finish which reduces glare.
Image 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.
[b]Screen Image retention[/b]
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.
[b]Is there any difference in power consumption of LCD tvs or Plasma tvs ?[/b]
LCD tvs have a backlight that is constantlyon and uses virtually constant power. LCD tvs usually have an adjustable back light which uses extra power when it is on a high setting and less on a low setting. The power required to alter 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.
On paper it might seem that the Plasma tvs use a lot more power than LCD tvs. Plasma tv manufacturers have a tendency to quote the highest power usage at full brightness. Although the plasma tvs power power consumption varies depending on the signal and the amount dark and bright areas on the screen. Studies have shown that when watching mainly dark programs and movies the average power power consumption of an identical sized plasma tv is in reality lower than LCD tv. Then again if lots of cartoons and sport are viewed then the LCD tv consumes less power. So 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 reduce the power consumption by over half.
Life expectancy
It is common myth that is quoted that plasma tv screens don't last very long. However manufacturers such as Panasonic are quoting a life expectancy of 100000 hours which is 11.5 years of continuous use. Therefore any concerns are unsubstantiated
Conclusion - which is the best?
Plasma televisions and LCD televisions both have advantages and disadvantages. LCD tvs have higher brightness, no concerns about screen burn, and they are thinner and lighter. But Plasma tvs have a better real world picture with a higher contrast, blacker blacks, and more natural colours than LCD tvs. Obviously not all Plasma tvs are better than all LCD tvs. A top specification LCD tv will out perform a cheap plasma tv. If you weigh up the advantages and disadvantages a good plasma tv is the best option but you do get what you pay for. - 29967
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