Plasma Or LCD? Which is Greener?

Speaking of cool solutions, which technology wins the green test.
LCD or Plasma?

First, I am really glad to see whole communities like the one in John Blackstone's piece putting up solar panels. If everyone in the US did that, the cost per watt would go down through mass production and more efficient cells will be developed. My #1 issue in the next presidential election is not the war on terror, but becoming more energy independent and if a candidate had a real "Manhattan" style project plan to do so, our country would be better off 10 year from now if elected in my opinion, but now on to a serious matter.

I am just about to make the switch from old picture tube TV in the living room to a flat screen since the old 25 incher is about to die.

I have been torn between LCD and Plasma since the price of Plasma screens almost match LCD's and have a more realistic picture, in my opnion. I had also been told that the power consumption between the two was a wash but that turns out not to be so. I have two reasons to consider this, both green. One, a green environment and the other greenbacks. I replaced all my incandescent lights years ago to save money. I only have one regular bulb since the clapper doesn't work with a florescent and my dining room lights, but they are just 5 25 watt bulbs on a dimmer.

I recently attended a SMPTE meeting that had a comparison between LCD's, Plasmas, and DLP as far as color accuracy (Plasmas were the closest by the way, but none were spot on yet) but the thing that alarmed me was the difference in power consumption between LCDs and plasmas of the same size. The speaker for the evening took a watt meter and ran regular off-air programming to both types and found that after 6 hours of real world pictures, not a test pattern, his test Plasma used 320 watts to operate at normal brightness, while the LCD only used a little over 100 watts. It took real video to measure this since the power consumption on a plasma varies depending on picture content since each pixel is emanating light of its own and an LCD has a constant power drain mostly from the florescent back light.

There are a few changes around the corner that favor LCDs even more.
One is using LEDs as backlights that would be keyed on as necessary using pulsing circuits using even less power to operate, and adding black frames at the rate of 120 a second to give richer blacks.

When you watch a film projected in a theater, there is a brief moment of black as the film is moved from frame to frame in the shutter. The movie screen is designed to hold some of the light from the previous frame until the next is displayed so you don't see flicker. With an LCD screen, the "twist time" between all white (no
voltage) to black (full voltage) is more gradual than a regular TV, about 8 microseconds, reducing flicker naturally, but this additional black insertion is supposed to vastly improve the blacks to make it almost on par with plasma. We will have to wait a little to see that, and a lot longer for the LED backlights estimated to be out by winter 2007.

In commercial applications where there is more ambient light like in a lobby, plasmas have the edge now, but in the home outside light is more controllable. Also viewing angles are both very wide, about 170 degrees, so that is no longer a factor. Rear projection TVs have improved left to right but still roll off up and down so everyone has to be at the same height. Considering that living room TV's are watched as well as background for a busy family and left on the longest, LCD's with the lower power consumption appears to be the clear choice. By comparison, the largest HD CRT set, the Sony 34"

WEGA uses 240 watts. Also I didn't know that 90% of all screens are made by LG and Sharp and are all the same. The difference is in the electronics. So one other thing to consider when choosing is the fact that standard definition is going to be around for awhile so how well do the internal electronics up-convert standard 480i to 720p, the most common LCD. This is something that is not stated in any spec so the bottom line is you have to look at the screen in person and watch standard TV to see how well it handles the conversion. Sets with a lower price point have basic up-conversion circuitry. I have been told that some of the newest DVD players that have HD up-conversion, look better than letting the TV do the conversion. The best possible way to get great standard TV on a HD set is use a dedicated up- converter, but with a $1,500 price tag, that about doubles the price of the TV, but can be also used on future sets.

Finally, I would like to eventually replace all the smaller TV's with LCDs in the bedrooms since my 2 kids can't seem to find the off button, and LCDs are not a possible fire or shock hazard if a drink is spilled sitting on top. All this said, I will probably not get to actually WATCH the new set because by the time I get home, the evening's schedule is already in full swing. I need to read more anyway.


  • Charlie Wilson

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