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Friday, February 10, 2012

Plasma vs. LCD vs. LED

Plasma vs. LCD vs. LED

I know there is an enormous amount of information on the Internet regarding this subject, with thousands of Blog Posts taking up space on servers everywhere. Even so, the first thing a customer asks me when they are looking to purchase a new television is:

"What's better, Plasma, LCD, or LED?"
or the infamous:

"What's the difference between LCD and Plasma?" 
So, even though there is a plethora of information about the topic, people still ask this (rather annoying) question. This post will offer an answer without a lot of technical information. In other words, I'll spare you the geek talk and give you some practical information for purchasing a new TV.

General Criteria

First let's set out some general criteria for purchasing any of the current technologies. First get a 1080p television. You may encounter the classic part-time sales person that says, 
"You don't need 1080p, you can't really tell the difference between 720p and 1080p unless you are watching a Blu-Ray disc and how often do watch those? Do You even have a Blu-Ray player?"
Ignore this person and walk away. There is a significant mathematical difference between 1080p and 720p. Specifically, 1080p is 1920x1080 pixels, while 720p is 1280x720 pixels. Most over-the-air broadcasts are in 1080i - the i stands for interlaced and the p stands for progressive. Progressive scan technology literally scans the entire picture line by line every sixteenth of a second, while interlaced scanning divides the horizontal lines of the television into odd and even lines and then alternately refreshes them at 30 frames per second. The second number in the pixel aspect ratio indicates the horizontal lines. Thus, a 1080i scan will be 540 odd and 540 even. Now on a 1080p television all 1080 horizontal lines will be there. However, on a 720p television there will only be 720 lines, thus a 360 odd and 360 even split. Whoops, we just lost about 360 lines of resolution! If your following the logic, only a 1080p television set can produce full resolution pictures on all types of scans - interlaced and progressive. So stick with a 1080p set (no matter what the technology). Especially if you are purchasing a TV 40" or larger, do yourself a favor and buy a 1080p set (your eye cannot really tell the difference below 40"). Now, from resolution to speed.

Early LCD televisions had severe problems with what is know as response time. Response time is the amount of time a pixel in an LCD monitor takes to go from one value to another and back again and is measured in milliseconds (ms). The higher the response time, the slower each pixel is to change and thus the higher the lag on your television set. I have an old 26" Sharp Aquos from 2003 (or maybe 2004) with a response tome of 8ms. When I watch a football game on this set all I see are squares and lag lines (artifacts which are a result of its slow response time). The set lags terribly! Response time and refresh rate are different and most LCD/LED screen have ultra fast response times in today's market. Refresh rate is not response time but it is still important.

I suggest that you buy a television which has at least a 120hz refresh rate. Television is recorded in 24hz   (frames per second) and unconverted to 30 frames per second. (fps) This is know as 3:2 pull down. The process is used to transfer film which runs at 24fps to 30fps to match you television's interlaced scan (progressive scan makes a huge improvement on any video). The frames are then combined and interchanged to get 60hz. So why so we need 120hz if the image is actually being presented at 60hz? The answer is that companies have developed advanced algorithms which are able to smooth the picture out better than the standard 60hz, by producing frames in-between frames, which already exist. They are not adding any more detail, but they are making the conversion easier on your eyes. TVs with 120hz or above  (although anything over 120hz does not significantly add to the picture quality and hikes the price up unnecessarily) produce a picture which is substantially more smooth than TVs at 60hz and most people can tell the difference.

These are the two criteria that I think every TV purchase should include. Now let's get to the different technologies.

Plasma: Pros and Cons

Don't let the myths about Plasma TVs prevent you from considering this technology! Plasma TVs have no issues with speed - most run at 600hz per sub-pixel and response time is irrelevant. Football, basketball, hockey, the explosion in space - it will all be smooth with a Plasma. Black levels will be amazing - no strange back-light bleed through to worry about. Color reproduction will be accurate and the colors will be rich and deep. Most plasma sets have 100,000 to half-life, meaning that you will get about 40 years of viewing at 6 hours a day! These sets do not need to be re-charged or refilled (I don't even know where that rumor started, nor do I care). In fact, these are awesome TVs, especially from the brand Panasonic. Most importantly Plasma has a huge advantage in PRICE! The technology for Plasma sets has been around longer and the manufacturing process is cheaper, allowing you to get more "bang for your buck". This can mean a difference, for two sets with the same specs, of just under $1000.00 in some cases - plus you can get larger Plasma sets for the price of some smaller LCD models (i.e. a 46" LCD will be the same price - sometimes higher - as a 50" Plasma). 

There are a few cons. First, these TVs have a thick glass screen which can produce glare (however, most LCD TVs now have a super-glossy screen anyway, so if you have a glare problem it's hard to get away from in some cases). Second, the color pallet for whites is not as pure as on an LCD or LED TV. In fact, shades of white can look rather grey, milky, or even purplish on Plasma screens - it can be annoying. Next, plasma screens are not as bright as most LCD / LED televisions; but really this doesn't matter when the TV is in your house and not side-by-side with 15 other TV models that are all on the "dynamic" picture setting. I am always amazed by the customer who says, "but that TV is brighter and I like bright", not bothering to look at the picture quality. Finally, and most importantly, Plasma screens still experience burn-in. Burn-in occurs when a static image is left on the screen for hours at a time - I have recently witnessed this occur with a static image which was left on a brand new Plasma for only 4 hours! Thus, if you watch Fox News, ESPN, or MSNBC religiously and they have that stock / news ticker on the bottom of the screen, it will become a part of your screen (it actually looks like a dark shadow which will become most noticeable when lighter images are on the screen). Moreover, the scroll bar "fix" (this black and white interchanging bar that just rolls accross the screen for hours in hopes of removing the burn-in) does not work, so don't bother using that feature at all. Burn-in will eventually fade out, but it takes a really long time. 

The conclusion here is that Plasma sets actually have a fantastic picture with rich colors, dark blacks, and super smooth images. Plasma is still a viable technology for anyone interested in buying an HDTV. But BEWARE, Plasma screens are still sold in the 720p resolution - LCD and LED TVs are not sold with this resolution in larger sizes anymore. Buy 1080p unless your really care less about resolution and are just looking for the so called "basement TV".

LCD and LED: Pros ans Cons


Liquid Crystal Diode displays and Light Emitting Diode based displays are essentially the same thing, except that LCD displays use fluorescent lamps for illumination, while LEDs use light emitting diodes to illuminate the TV. Liquid crystal technologies do not produce light on their own (like Plasma TVs which burn phosphors) so they must be back-lit. LCD have come a long ways since they were introduced. They are very bright televisions with most florescent bulbs putting out around 80 lumens (most plasma sets can produce around 3 lumens). But as I already said, this may not be a significant advantage. LCDs and LED also have very good color reproduction in today's models, not so much in the past. LCD TVs have also corrected the issue with response time, yet LCD TVs are still slower than Plasma models. Moreover, as long as the LCD or LED has 120hz motion technology, it will have a smooth picture. LCD TVs are also lighter and have more diverse mounting options; Plasma screens are heavier and require a two-stud mount, but most LCD TVs are light enough to use one-stud full swivel mounts. LCD televisions tend to have more depth than Plasma sets, meaning that the pictures are much more vibrant under normal conditions, especially on static images. Finally, LCDs with a "matted" screen eliminates nasty glare; this only applies to LCD sets without the glossy screen, some LCD / LED sets have MORE glare than any Plasma and some Plasma TVs have an anti-glare coating which makes them as good as any matted LCD. Another advantage is power consumption. LCD sets utilize less power than plasma sets because the technology needs less power to operate. Moreover, the LCD and LED TVs generally have a higher native resolution than Plasma, which will still offer a range of 720p sets. As mentioned before, still images look amazing on LCD and LED TVs; thus they are much better for use as a duel TV / Computer Monitor.

There are a few cons. First black levels on most LCD TVs can be improved. The contrast ratio tells us the ratio of the luminance (a measure of the intensity of light) of the brightest color white to the darkest color black. Just because a TV is brighter than the rest does not mean it has a better contrast ratio. Plasma sets produce very dark blacks and thus can reach very high contrast ratios without having to be super bright. LCD (we will get to LED shortly) sets are back-lit with fluorescent tube lighting and have the tendency to allow light to bleed through, preventing perfect blacks (which will affect the dark colors on your set). Thus, LCD sets have trouble presenting true blacks which are important for overall picture quality. The viewing angle on an LCD (because it is back-lit) is only 178 degrees, rather the full 180 degrees of most plasma sets. Thus at the extreme viewing angles the picture on an LCD can be distorted. LCDs and Plasma sets have similar life spans, thus there is no real difference in this category. Plasma sets have burn-in (which is not permanent), but LCDs also have their idiosyncratic issue called "defective pixels" or the "dead pixel effect". A defective pixel is literally a pixel on an LCD / LED screen which either never shows light or always shows light - essentially it is static and never presents an image leaving a small point on the screen which never changes. I hate these little monsters! Imagine you are watching a Star Trek movie where the Enterprise is about to kick in to warp drive. The image on the screen shows the Enterprise in deep space... wait what it that thing in the middle of the screen?... Is it a star?... No it's a neon green defective pixel that you are just noticing for the first time because a dark image is on the screen. Now whenever you look at your set you will see that neon green bastard. Worse, you call the manufacturer and they tell you that they will not cover this defect under the one-year limited warranty unless there are 20 or more defective pixels in a cluster on the screen - otherwise they don't consider it a "defect". That is the truth of the matter and I know several customer who went through this nasty scenario. By the way, most "extended warranties" only extend the manufactures warranty and will not cover this issue.

Speaking of "extended warranties" do not buy one on an LCD unless it covers 1 or more defective pixels! LCD sets require very little maintenance and outside of the defective pixel issue, these TVs are generally stable. The only major issue is the defective pixel so if the extended warranty covers this issue, you might want to go for it. You have to replace the entire LCD panel to fix the problem and that costs about 80% of the value of the TV. The same goes for Plasma, if they cover burn-in, it may be a decent deal. However, some Plasma sets do have substantial cooling systems which should be occasionally cleaned. If the extended warranty offers preventative maintenance (PM) checks or cleanings it may be worth it. I am not advocating for the "extended warranty" by any means, but in some cases - if the cost is low enough - it could be worth it. In most cases it's not worth it at all. Think about it in terms of expected value and probability theory.

Let's say for the sake of argument that 10% (a high estimate) of TVs like the one you are going to buy will require a repair 2, 3, or 4 years (not per year) after the initial one year warranty. Let's say that the extended warranty costs $150.00 (most cost more) for 3 years additional coverage beyond the manufacture warranty (usually the extended warranty subsumes the manufactures, but I'll give them the benefit of the doubt in this example). Let us further assume that the average repair costs is about $300. Thus, 10% of the time we would have a $300 repair three years after the manufactures warranty expires and the extended warranty costs us an initial $150, while 90% of the time we would not need a repair in four years and the warranty still costs us $150. Let's do the math to find the expected value of the extended warranty: .10(300-150) + .90(-150) = .10(150) - 135 =  15 - 135 = -120. Thus, on average a customer should expect to lose $120 on the purchase of the extended warranty - and keep in mind that I chose a percentage of defection that is rather high. The point of this exercise is to demonstrate that generally risk adverse people (who are scared or pressured by the salesman) purchase these warranties. Now, of course, if the warranty offers additional services beyond repair (like PM checks and cleanings) it might be worth it because it is possible for the warranty to "pay for itself". For example, if a PM check costs $100 a year and the warranty costs $300, and you use all your PM checks, then it has paid for itself. Or if the warranty covers high probability repairs which cost a lot to fix (like defective pixels) it might be worth it. It's your call!

All LED Technology Is Not Created Equal

LED sets are LCD TVs with a different back-light - they use Light Emitting Diodes rather the Cold Cathode Fluorescent Lighting. They are thinner, lighter, and have more versatile and slim-fit mounting systems. There are generally three types of LED lighting patters: (1) Edge-Lit; (2) Full Array; and (3) Dynamic Clusters. The most common type is Edge-Lit, which means that the TV has LED around the edge and that light is diffused throughout the rest of the TV and is also the most useless advertising mechanism to inflate price - yes these LED sets do not provide any advantage over LCD sets, except maybe slightly purer whites. The advantage of LED rests in the "local dimming" feature of Full-Array and Dynamic sets. When a TV is a full array LED, this means that each diode is independently controlled and thus certain areas of the screen can be dimmed to achieve more balanced blacks and ultimately higher contrast ratios. Edge-Lit sets do not have local dimming. Dynamic cluster, while not as good as Full-Array, do have the ability to dim clusters of diodes and thus improve picture performance. Thus, Full-Array and Dynamic Cluster LED sets are worth the extra cost, while Edge-Lit LED sets do not actually improve the picture quality in any substantial way, other than to make colors slightly more pure. Moreover, in some cases Edge-Lit LED TVs can have more light distribution problems because they tend to be brighter at the edges! Don't be fooled, not all LED sets are created equal.

A Brief Word on 3D

There are generally two types of 3D televisions: (1) Active and (2) Passive. 3D works by tricking your eyes to see two slightly different images. Active 3D technology uses glasses equipped with little LCDs (that generally cost $149.00!!) to dim (not block) right and left images in succession to trick your eyes. These glasses have to communicate with the TV via an inferred sensor and need batteries to operate. Why anyone would buy this technology is beyond me! For a family of 4 to watch a single 3D movie they have to make an initial investment of $450 (the first pair are free). The price of your new TV just went up by almost 1/3 of the cost of most 50" screens. Do the movie theaters spend $150 on their 3D glasses? NO, because they use Passive 3D technology. Passive 3D works by using a special pair of polarized glasses which are designed to block specific types of light emitted by the TV. Thus, the TV does all the work and the glasses don't need batteries and cost about $10.00. But, technically, since the glasses are blocking (not dimming) out light you are not getting the full 1080p resolution with the passive technology. Nevertheless, I have seen both operate and the Active 3D is not that much better (if at all) than the passive 3D - it is definitely not worth the extra $450 (as most Passive sets come with 4 pairs of glasses upon purchase). 3D is cool and it will get better over time, especially because actual broadcast television swill start to utilize the technology, but right now it should not make or break your decision on which TV to buy (unless of course you really care about this feature - it's subjective); but I would never buy an active 3D TV since the future of the technology will be  most likely be Passive. 

Conclusion

All three types of TV sets are viable technologies and you should consider all three when purchasing a TV. They all have pros and cons to look out for. In fact, I own all three types (plus a rear projection LCD which I am not going to bother to talk about because no one sells them anymore, albeit in the largest of the large sizes and even then front projection is better. There was also DLP technology which suffered the same fate as Rear projection LCD). If you have a budget constraint I think Plasma sets give you the most for the money. If you have a huge budget, Full-Array LED TVs are great but so are THX certified Plasma sets. I am not going to crown a winner but I should have given you enough information to make up your own mind. Happy TV Hunting! 

17 comments:

  1. If I don't want to buy "outdoor tv" because so much more exp, but I want outdoor 60 inch tv on outdoor wall under covered area, what is best to avoid glare?

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    Replies
    1. Hi Howard,

      You are absolutely right about what manufactures call "outdoor televisions". These products are very expensive and many do not offer the same quality as "indoor televisions". For example take the Skyvue (SKY6020) 60" outdoor LED that costs $$4,499. I would bet that a high-end Sony or Samsung LED has a better picture than the Skyvue (maybe not) but the price will definitely be cheaper.

      Now of course, outside of water/snow damage, operating temperature is huge consideration. Most outdoor TVs have an operating temperature between -20 degree Fahrenheit and 150 degrees Fahrenheit. If you have tried to operate an LCD display in the cold you know that they become slow to respond and images ghost over each other. Moreover, heat is the number one enemy of all electronics. This is something to think about. If you are planning on operating the set in relatively cold or hot temperatures then you might want to consider a true "outdoor television". Take the Samsung 60" 7500 LED that costs about $2,900, it has an operating temperature between 32 degrees Fahrenheit and 122 degrees Fahrenheit. I live in upstate New York and in the winter that operating temperature will be no good for me. But if you live in an area like North Carolina or Florida that TV might be good outside all year round.

      So let's assume that operating temperature is not an issue and that the TV will not be exposed to water/snow. Your original question was about glare. The answer is LCD or LED, not plasma. All plasmas have a thick glass screen and will produce glare (there were some Panasonic models with an anti-glare protective coating a year or two ago, but even then glare was still somewhat present and the picture quality was compromised). Thus, LCD/LED are the way to go. But beware, some LCD/LED TVs have a clear coated screen that produces just as much glare as any plasma! Especially Samsung models with what they call the "Ultra Clear Panel".

      My personal recommendation would be a Sony Bravia like the 60" EX645 coming out soon for about $2,000 - great picture quality with the matted screen that heavily reduces glare. However, it can only be operated at temperatures above 41 degrees Fahrenheit. Nevertheless, any LCD or LED TV with a matted screen will do. I hope that helps!

      Best,
      Nick

      Delete
  2. Thanks Nick! This is a fantastic article and it explaines a lot of stuff that i would never have guessed before. I have to agree that 3D is pointless. But i am going out to find a new flatscreen tv for my churches youth group so it can be hooked up to an ipad and basically be soly used by youth (meaning it will probably get A LOT of use) what would you suggest for something durable that can survive a ton of use by not so gentile people?

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  3. Hi Brandon,

    I am glad you found the article useful.

    There are really two things to think about when answering this question: (1) Physical Damage and (2) Image retention.

    First, lets's take LCD and LED televisions. The screen on these TVs is very fragile and can easily be cracked. They are made of a very thin panel with two (also very thin) pieces of glass which sandwich the crystals and TFT mechanisms. I have seen many break in the past from things such: as throwing a rubber ball at the screen; knocking the set to the ground accidentally; and simply the desire to press really hard on the screen to see the beautiful rainbow interrupting the LCD crystals produces (you can easily try this by gently running your finger across an LCD screen, you will see how easily it bows and produces the spectrum of colors). In fact, poking an LCD can cause other types of less serious damage as well, such as broken or stuck pixels. of course there are LCD sets with protective coatings which do a better job, but your average LCD is fragile and the more protected sets cost a considerably more money.

    Now, let's look at plasma. These TVs have a thick tough glass screen that can really withstand a lot of torture. In the 15 years or so that I have been in the Home theater businesses, I have seen cracked plasma screens only a handful of times and it was usually because of a faulty mounting system where the TV fell 6-feet down to ground. With LCD/LED TVs the frequency of cracked screens in much, much higher. There is no question that plasma screens are the tougher variety.

    But, in your case, I must still recommend LCD/LED.

    The reason is what you are connecting it to - an iPad. It seems like there is the potential for there to be a static image on the screen for a considerable period of time. Even if people use it to watch movies, there will still be times where they will use apps that have static images that do not move. Plasmas are notorious for what we call image retention or "Burn-In". This occurs when a static image is left on the screen for as little as a few hours. The image will literally ghost into the television and thus can be seen even after the app or image is removed. This is an issue near and dear to my heart because I own several plasma TVs and unfortunately they have various things burned into the screen - such as the A&E logo because I really like that station.

    While plasma TV have come a long way in this respect, they still burn in and I would consider your television a "high risk" scenario. Still, the image retention tends to wash out over time and correct itself, but this assumes that the static images (i.e. the app screen) will not be a constant variable.

    The solution may be to mount the television in a way where it will not be touched, while still allowing people full access. Maybe mounted on a way 4-6 feet from the ground? Obviously the remote control is a good way keep people from touching the TV itself. But I also recommend Apple TV for the iPad rather than an HDMI tether. Apple TV will allow the iPad to me mirrored on the television without anyone needing to actually touch the TV. This seems like the best case scenario.

    So LCD/LED is the way to go to escape the burn-in, which I think is a bigger threat to the television than users. But if you don't care about image retention, then Plasma are the tougher TV.

    I hope this helps!Have a great evening!

    Best Regards,
    Nick

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  4. Thanks so much for this one! Not everyone can understand the technicality of modern TVs and what happens most is that the buyers are deceived by good word-of-mouth-advertisers with the tendency that they buy the more expensive ones, when all they had to do is read and read and read before buying.

    Lance Vartanian

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  5. Among both led is better than lcd tv. It displays colors brighter than lcd tv. Also,it is eco-friendly and energy efficient.
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  8. This is a fantastic article and it explaines a lot of stuff that i would never have guessed before. I have to agree that 3D is pointless. Art Lighting

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