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 Post subject: plasma vs lcd? power usage?
PostPosted: Fri Nov 26, 2010 12:30 pm 
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This is purely based on old information, but don't plasma displays use waaay more power than equivalently sized LCDs of any back-lighting derivative? Not that this is necessarily a deal-breaker, but something to keep in mind.

Edit: oops, this was supposed to be a reply to the LCD back lighting question thread. Not sure how I managed to make this its own! Is there a magic admin button to move it? Don't worry about it if it's a pain!

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 Post subject: Re: plasma vs lcd? power usage?
PostPosted: Tue Nov 30, 2010 8:34 am 
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Yes, they use quite a bit more, which manifests itself in the form of additional heat.

My friend has a Panasonic 50" plasma, uses 400-500 watts during use. Not sure how much at idle. Maybe time to bust out the kill-a-watt.

My TV is a 46" LED edge-lit LCD, uses 120-150W from what I've read. Again, more precise testing would have to be done to be sure.

IMO the LCD televisions @ 120Hz are superior to plasma televisions- I love the picutre on mine, seems to be sharper and more defined than the plasmas, I have huge contrast and the motion is very smooth. Then again, the only big downside to plasma is the heat/power issue I believe.

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 Post subject: Re: plasma vs lcd? power usage?
PostPosted: Tue Nov 30, 2010 9:23 am 
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http://reviews.cnet.com/green-tech/tv-c ... ion-chart/

Check out some ~46" and some outliers (it varies widely)

Sony KDL-46EX700 LED/LCD 46" 87.22 watts
LG 47LE8500 LED/LCD 47" 90.01 watts
Sharp LC-46LE700UN LED/LCD 46 101.58 watts
Samsung UN46B6000 LED/LCD 46 106.40 watts
Panasonic TC-P46G10 plasma 46 168.78 watts
Sony KDL-46W4100 LCD 46 274.43 watts
Panasonic TH-46PZ85U plasma 46 454.51 watts

so same brand comparisons from that show

Sony KDL-46EX700 LED/LCD 46" 87.22 watts
Sony KDL-46W4100 LCD 46 274.43 watts

and

Panasonic TC-P46G10 plasma 46 168.78 watts
Panasonic TH-46PZ85U plasma 46 454.51 watts

showing that just because it's LCD or just because it's plasma doesn't tell you if it will be efficient. It just varies too darn much to make generalizations.

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 Post subject: Re: plasma vs lcd? power usage?
PostPosted: Tue Nov 30, 2010 11:05 am 
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As I remember
with plasma it depends on what you are watching
snow scenes - high energy
underground darkness - low energy.

The figures the manufacturer are obliged to publish are the maximum figures - only applicable if you only watch ski sunday.

with lcd the energy figure is constant, it is not able to vary.


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 Post subject: Re: plasma vs lcd? power usage?
PostPosted: Tue Nov 30, 2010 2:05 pm 
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FWIW my Panasonic 42G20 has an average (specified) power draw of 130W, it's fanless and doesn't get hot under normal viewing.
That's having the digital receiver as input. However, when using the PC as input 1080p / 60Hz, it gets a bit hot, I'm not sure why.
A friend of mine said it could be because the receiver feeds it 1080i / 50Hz.
I have seen a few LED backlit LCDs that have slightly better contrast than my plasma, but the viewing angles were poor.


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 Post subject: Re: plasma vs lcd? power usage?
PostPosted: Tue Nov 30, 2010 6:53 pm 
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sorrera wrote:
As I remember
with plasma it depends on what you are watching
snow scenes - high energy
underground darkness - low energy.

The figures the manufacturer are obliged to publish are the maximum figures - only applicable if you only watch ski sunday.

with lcd the energy figure is constant, it is not able to vary.


yes, but the numbers I quoted are actual measurements not manufacturers specs.

So even a LCD that draws 87W no matter what is on the screen will always use less energy than a plasma that does 450+W on the test picture.

Quote:
Plasma TVs use more power than LCD TVs. In our tests of TVs since the beginning of 2008 plasmas consume, on average, roughly two to three times more electricity to produce an image of the same brightness as LCD. In the last couple of years, plasma TV makers have made some progress--Panasonic claims improvements of 30 percent yearly, for example--but they still can't compete with LCD for energy efficiency. One problem is that in plasma TVs, each pixel is a discrete light source (think of it as a tiny light bulb), so when resolution increases, say from 720p to 1080p, power use goes up as well. The intensity of light from each pixel must be increased to brighten the picture as a whole.

CNET follows the standards outlined in IEC 62807, the same methodology employed by Energy Star, to test TV power usage. Per these methods, TV power draw is tested in the default picture setting and in standby mode. At CNET, we also test two additional picture-setting scenarios: post-calibration and power saver. Unlike Energy Star, we also disable room lighting sensors in default mode, if possible, before running the test. For the full details of Energy Star 3.0 testing requirements, click here (PDF). We have not made any changes to our testing with the advent of Energy Star 4.0.

To collect the data, we use a Chroma 66202 Digital Power Meter, which is designed to meet Energy Star/IEC 62301 measurement requirements. The meter automatically averages 1-second interval wattage measurements over the 10-minute test period, and is capable of accurate standby measurements. (We retired our old Watts Up meter, which was not capable of accurately measuring the fractional watts drawn by most new HDTVs' standby mode, in June 2009, so most measurements made before then showed standby consumption of zero watts.)

The basic test procedure goes as follows:

* Plug the television into the meter and the meter into a wall outlet.
* Connect a DVD player via an HDMI input.
* Insert the IEC 62087 test DVD, which contains a specific 10-minute clip of program material, into the player.
* Turn on the television.
* If the TV has a "home" mode available as a choice during initial setup, choose it and go through the rest of the initial setup process, making sure to not change any of the picture settings. This ensures the closest to "default" picture setting.
* If the TV's default settings incorporate an automatic brightness control with a room lighting sensor, turn it off. If the control cannot be turned off, make sure the light level striking the sensor is as close to 300 lux as possible.
* Run the IEC test DVD for an hour by setting the 10-minute clip to repeat six times. This warms up the TV and stabilizes its power consumption.
* Default test: After the warm up period is over, run the test DVD for the official 10-minute clip, making sure to increase the volume to a moderate level the tester can hear clearly.
* Power-saving mode test: If the TV has a power-saver mode, engage that mode in its most-efficient setting, the one that uses the least power, and repeat the 10-minute clip.
* Post-calibration test: Repeat the 10-minute clip again in the calibrated picture settings, with a light output of 40 footlamberts measured on a specific window test pattern (more information).
* Standby test: Turn the TV off and observe the meter's readout after it settles down into a steady standby power draw, typically after a minute or two.
* The three 10-minute clip tests, along with the reading from standby power, are reported in the Juice box attached to every TV review (see below).


As we mentioned, Energy Star does not report on the effects of power saver or post-calibration picture settings. We chose to include these tests because they give a better overall picture of TV power use, rather than what you get simply with the default picture settings. The post-calibration results in particular are useful for leveling the field of comparison between different TVs. Default picture modes can vary widely in light output, and thus power use, but our calibration specifies a set light output.

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 Post subject: Re: plasma vs lcd? power usage?
PostPosted: Tue Nov 30, 2010 7:01 pm 
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sorrera wrote:
with lcd the energy figure is constant, it is not able to vary.

This is quite untrue. Some led-backlit lcd tvs supporting local dimming also have varying power consumption depending on the content. And even without local dimming, I believe quite a few (led or ccfl-backlit) lcd tvs support global dimming, which will change power consumption just as well.
The power draw difference dependent on content might be lower with lcds though compared to plasmas (not sure really but with plasmas it's pretty large).
In general I think it's safe to say however that plasmas (of the same size) still have higher power draw compared to LCDs on average.
Of course, a true LED-TV (i.e. not the marketing-type LED-TV which is just a LCD-TV with led back light but really using led/oled for the pixels) should have the lowest power consumption (and the best picture quality).


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