Comparison of the flat screen tv technologies
When it comes to flat screen TVs the two technologies LCD and Plasma seem very similar with almost lifelike images and the ability to be hung on the wall. Although LCD tvs and Plasma tvs displays may look very similar in the shops, there are numerous differences between the two technologies.
How LCD tvs work
LCD is an abbreviation for Liquid Crystal Display. A LCD tv screen is made up of two clear panels between which is a matrix of colour liquid filled pixels. These pixels respond to a small voltage which makes them change state by twisting or untwisting which allows light to pass through them or to be blocked depending on the state of the pixel. This process of twisting takes very little power. The pixels are either red, green or blue and they are structured in a matrix of millions of pixels to make a picture. The coloured pixels of the panel are illuminated from Behind with a back light to show their colour, and areas of light and dark, depending on how the pixels are twisted. Lcd screens are available in small sizes for watches up to 108 inches for large televisions. Manufacturers such as LG, Samsung, Hitachi, Panasonic, JVC, Pioneer, Sharp, Toshiba, Philips and Sony have a range of lcd televisions available.
How does a Plasma screen display a picture?
The screen of a Plasma tv is made up of millions of microscopic gas filled glass cells which have electrodes in them. The cells are filled with inert gases including xenon and neon and form each pixel. When a current is applied to the cell electrodes the gas atoms become 'excited' and become a plasma emitting photons of ultraviolet light. When the photons strike the phosphor coating that is inside the glass cells light is emitted. The light colour emitted is determined by which of the three coloured phosphors are used - Red, green or Blue. These colours can be combined to produce billions of colours. When millions of the pixels are combined they form an image on the screen like LCD televisions. Plasma tvs are only manufactured by Panasonic, Philips, Pioneer, LG, and Samsung and are available in range of sizes from 32 inches through to 150 inches.
How does the Picture quality and the performance compare?
The Brightness of the picture
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 required in normal viewing.
Contrast Ratio and 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.
Levels of Colour Saturation
This is a measure of the accuracyof the colours on the screen based on the existence 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
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.
TV Screen Resolution
This is the amount 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'20 pixels x 1080 pixels, full 1080p resolution at a lesser 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 this time only HD Ready but LCD tv models are available from 32 inches upwards in full HD or 1080P.
Response Time and Refresh Rate
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.
Less expensive models of Plasma televisions and LCD televisions operate at frame rates of 50 frames per second or 50hz. Recently 100hz tv models were launched on more expensive models which reduced motion blur by creating an extra middle frame which is placed in between the normal frames. This middle frame is created by advanced signal processing software that interpolates what the middle frame would look like. The addition of the middle frame results in moving images that are fluid with little, if any definition loss. Even with 100hz the best plasma tvs still out perform the best LCD tv models but by a narrowing margin because of reduced response times and 100hz and 200hz.
The Viewing Angle
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.
The screen surface of lcd tvs and plasma tvs
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.
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.
Image retention
image retention is often confused with burn-in which has similar characteristics. However image retention is a 'ghost image' that appears on a plasma tvs after a still picture has been displayed for an extended period of time, but then disappears when a bright new image is displayed. Or it vanishes after a few seconds. By having a 'break in' period of about 100 hours from new, this can be minimised. Whist watching programs during this break in period care should be taken to watch programs that don't have any static bright images like station logos and scrolling news headlines at the bottom of the screen. Also try to watch programs that fill the whole of the screen. It recommended that during this period the brightness and the contrast is kept at about a mid level. These characteristics of image retention and burn-in have been greatly reduced by technical improvements to reduce the possibility of burn-in or image retention.
[b]Is there any difference in power consumption of LCD tvs or Plasma tvs ?[/b]
The backlight on an LCD tv is constantly on so the power consumption is almost constant. By manually adjusting the brightness of the back light up or down the power consumption is either increased or decreased. The twisting and untwisting of the LCD pixels consumes hardly any power.
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.
[b]Plasma tv Life expectancy[/b]
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
[b]Conclusion - which should you buy?[/b]
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. - 30542
When it comes to flat screen TVs the two technologies LCD and Plasma seem very similar with almost lifelike images and the ability to be hung on the wall. Although LCD tvs and Plasma tvs displays may look very similar in the shops, there are numerous differences between the two technologies.
How LCD tvs work
LCD is an abbreviation for Liquid Crystal Display. A LCD tv screen is made up of two clear panels between which is a matrix of colour liquid filled pixels. These pixels respond to a small voltage which makes them change state by twisting or untwisting which allows light to pass through them or to be blocked depending on the state of the pixel. This process of twisting takes very little power. The pixels are either red, green or blue and they are structured in a matrix of millions of pixels to make a picture. The coloured pixels of the panel are illuminated from Behind with a back light to show their colour, and areas of light and dark, depending on how the pixels are twisted. Lcd screens are available in small sizes for watches up to 108 inches for large televisions. Manufacturers such as LG, Samsung, Hitachi, Panasonic, JVC, Pioneer, Sharp, Toshiba, Philips and Sony have a range of lcd televisions available.
How does a Plasma screen display a picture?
The screen of a Plasma tv is made up of millions of microscopic gas filled glass cells which have electrodes in them. The cells are filled with inert gases including xenon and neon and form each pixel. When a current is applied to the cell electrodes the gas atoms become 'excited' and become a plasma emitting photons of ultraviolet light. When the photons strike the phosphor coating that is inside the glass cells light is emitted. The light colour emitted is determined by which of the three coloured phosphors are used - Red, green or Blue. These colours can be combined to produce billions of colours. When millions of the pixels are combined they form an image on the screen like LCD televisions. Plasma tvs are only manufactured by Panasonic, Philips, Pioneer, LG, and Samsung and are available in range of sizes from 32 inches through to 150 inches.
How does the Picture quality and the performance compare?
The Brightness of the picture
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 required in normal viewing.
Contrast Ratio and 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.
Levels of Colour Saturation
This is a measure of the accuracyof the colours on the screen based on the existence 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
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.
TV Screen Resolution
This is the amount 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'20 pixels x 1080 pixels, full 1080p resolution at a lesser 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 this time only HD Ready but LCD tv models are available from 32 inches upwards in full HD or 1080P.
Response Time and Refresh Rate
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.
Less expensive models of Plasma televisions and LCD televisions operate at frame rates of 50 frames per second or 50hz. Recently 100hz tv models were launched on more expensive models which reduced motion blur by creating an extra middle frame which is placed in between the normal frames. This middle frame is created by advanced signal processing software that interpolates what the middle frame would look like. The addition of the middle frame results in moving images that are fluid with little, if any definition loss. Even with 100hz the best plasma tvs still out perform the best LCD tv models but by a narrowing margin because of reduced response times and 100hz and 200hz.
The Viewing Angle
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.
The screen surface of lcd tvs and plasma tvs
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.
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.
Image retention
image retention is often confused with burn-in which has similar characteristics. However image retention is a 'ghost image' that appears on a plasma tvs after a still picture has been displayed for an extended period of time, but then disappears when a bright new image is displayed. Or it vanishes after a few seconds. By having a 'break in' period of about 100 hours from new, this can be minimised. Whist watching programs during this break in period care should be taken to watch programs that don't have any static bright images like station logos and scrolling news headlines at the bottom of the screen. Also try to watch programs that fill the whole of the screen. It recommended that during this period the brightness and the contrast is kept at about a mid level. These characteristics of image retention and burn-in have been greatly reduced by technical improvements to reduce the possibility of burn-in or image retention.
[b]Is there any difference in power consumption of LCD tvs or Plasma tvs ?[/b]
The backlight on an LCD tv is constantly on so the power consumption is almost constant. By manually adjusting the brightness of the back light up or down the power consumption is either increased or decreased. The twisting and untwisting of the LCD pixels consumes hardly any power.
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.
[b]Plasma tv Life expectancy[/b]
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
[b]Conclusion - which should you buy?[/b]
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. - 30542
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