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Old 04-02-2009, 09:25 PM   #27  
What's all this, then?...
BobY's Avatar

Join Date: Jan 2006
Posts: 6,197

Originally Posted by nmlobo View Post
What is the source for your claim that "a PDP can use much less power than an LCD of the same size"? I looked and can not find anything to support it.
We've discussed it often over the years here, you can search the threads out, but here is a recent discussion:

and here is the link in that thread to some data:;rb_mtx

The data shows a number of LCD's that draw more power on an absolute basis than a number of Plasmas and the Watts-per-Square-Inch is all over the place--you'll see many LCD's with "poor" scores per size and many Plasmas with "good" scores per size. While on average LCD's are better, there are far too many "poor" LCD's (per size) and far too many "average" and "good" Plasmas (per size) for anyone to say it's a slam-dunk.

Originally Posted by nmlobo View Post
"many flat LCDs actually have adjustable backlights that you can turn down to consume less power and produce a dimmer image, while some newer LCDs, including ones that use LED backlights, can be set to dynamically adjust the backlight intensity and use less power in dim scenes."
But if owners leave the backlight all the way up, what difference does it make? Those with Plasma displays can turn the brightness down also, so that really doesn't affect the debate.

Selective backlights are a good way to reduce LCD power consumption, but few LCD's have them (particularly in the price range that most people are buying) and none of them have an LED-per-pixel, so there is efficiency loss there as well.

Part of the issue we had with some of C-Nets results is they intentionally left the displays in factory default "torch" mode for their tests, assuming that owner's would do the same, but that doesn't really tell you what the power consumption would be if the user decides his display is using too much electricity and wants to cut down.

If I set my thermostat to 72 degrees in the winter, it uses a lot more energy than if I set it to 68 degrees, so I don't set it to 72. If I didn't care about wasting energy, I would be more comfortable at 72--it's up to the user to set things the way they want if they are concerned about energy usage or their electric bill.

Originally Posted by nmlobo View Post
"Because LCD uses a backlight system and closes pixels off to produce darkness, the power consumption of an LCD HDTV is constant whether the image is bright or dark. Plasma panels produce more brightness by pumping more energy into each cell or pixel that needs to be brightened, and it turns down the power to cells that need to be darkened. As a result, plasma power consumption varies with the brightness of the picture. For most content people tend to watch Plasma HDTVs tend to use more power. It is true that plasmas are likely to use less power displaying dark scenes, or movies that are dark in general, but averaged out; plasmas do tend to use more power. "
That's pretty much what I said and it's true. Why should something be banned based on being "averaged out"? If they want to beat up on something, beat up on specific products that are inefficient relative to comparable products, regardless of the technology or size.

Originally Posted by nmlobo View Post
"One new feature in the latest HDTV report is energy consumption. CRís engineers determined the amount of energy used by typical LCD, plasma, and rear-projection TVs turned on for 8 hours a day, 365 days a year. Most sets didnít use significantly more energy than a 32- to 36-inch picture tube TV. One exception was 50-inch 1080p plasmas, which used twice-as-much energy as the biggest picture-tube set, and more than a comparably-sized LCD. Not surprisingly, bigger screens of all types consume more electricity than smaller ones."
Well, 50" Plasma displays are much bigger than the biggest "picture-tube set", so the real question is power-usage-per-square-inch. Mid-size cars use more gas than subcompacts. Should we ban mid-size cars?

The article doesn't say what "comparably-sized" LCD's draw, only that Plasma draws more, so it's an unfair comparison. C-Net's comparisons indicate that even some of the least efficient Plasmas would cost less than $10/Month more than a comparably sized LCD and that's assuming torch mode at 8 hours/day, 365 days/year, so the real-world difference would be less and could easily be compensated for in other ways.
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