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LCD? LED? Plasma? The How-To Geek Guide to HDTV Technology

HDTVs

With image technology progressing faster than ever, High-Def has become the standard, giving TV buyers more options at cheaper prices. But what’s different in all these confusing TVs, and what should you know before buying one?

If you’re considering buying a television this Holiday season for a loved one (or simply for yourself), it can be a big help to know what to look for. Take a look to find out what sets HD televisions apart, learn some of the confusing jargon associated with them, and see a comparison of four of the types of HDTVs commonly sold today.

HDTV versus Standard Definition

tv pixels close up

Televisions and monitors create images in the same way, illuminating combinations of Red, Green, and Blue to create single picture elements, or pixels. Different types of displays have their unique ways of doing this, but in theory, they’re all doing the same thing: creating the illusion of an image with tiny points made from combinations of various amounts of primary colors.

For years, the standard for television and home theater were Low-Def Cathode Ray Tube monitors, which in ordinary household situations would usually have a paltry 640 pixels by 480 pixels. While it was possible to create images full of detail by shooting movies with quality film stock, when it was played on low def televisions, quality could not help but be lost as high-quality film photography is forced into a low-resolution TV medium. While film photography is independent of the confinements of pixel-based video, it was impossible for consumers to view beautiful high-quality movies without purchasing copies of movie reels and setting up old fashioned theater projectors, which are also independent of resolution.

The simple answer was just to create home monitors with more and more pixels, with the modern widescreen definition at 1920 pixels by 1080 pixels. This makes each individual pixel smaller, creating images that look sharper and cleaner. However, HDTVs and computer monitors are more complicated than simply the sum of their pixels.

Important Terms to Know When Buying HDTVs

3396427350_b6893da4bd_o

With each subsequent generation of television, the language and buzzwords surrounding Hi-Def televisions become more and more complex. Here’s a rundown of the terms you’re likely to hear, and what each of them mean.

Contrast Ratio: A number ratio resembling 1:1 or 10,000:1, which illustrates how much difference there is between the brightest whites and the darkest black colors the screen can display. The higher the ratio, the better the contrast.

Refresh Rate: How often the display hardware will redraw (or “refresh”) the image created on the screen. Videos are made of “frames,” which are flashed on screen multiple times per frame because the Refresh Rate is faster than the Frame rate. In other words, you’ll watch the same frame multiple times in a single second, because the refresh is so incredibly fast. Refresh rates are measured in Hz, or cycles per second.

The higher the refresh rate, the better your picture will be, affecting the way fast-moving images appear, reducing blurring and improving clarity. Plasma displays usually have a much higher refresh rate, with the typical screen having a 600hz refresh rate, but LCD or LED TVs have been catching up with 60, 120, 240, or even some 480hz refresh rates available.

Pixel Response Time: Similar to refresh rate, Pixel response time is the number of milliseconds the individual pixels take to react to a refreshed image. While Refresh rate deals with the time it takes the hardware to refresh the image, response time refers to how quickly the individual pixels change color from white to black or red or green. The lower the time, the better. Better response times will also create less blurry pictures for fast moving images.

CRT: Acronym for Cathode Ray Tube, the oldest commercial model of televisions and computer monitors. Cathode Ray Tubes are not preferred by modern consumers, despite excellent picture quality, because they necessarily huge, bulky, and heavy.

LCD: An acronym for Liquid Crystal Display, an extremely common model of display, found in laptops and TVs, as well as displays on alarm clocks and microwaves. LCD is a very energy efficient way of creating color displays compared to CRT.

LED: Stands for Light Emitting Diode, a simple circuit that emits light. LED is the newer addition to the HDTV bestiary, and is the new, hip product to push on consumers.

Plasma: Plasmas use the same technology that the Fluorescent lights over your head use to light televisions. Plasma screens were the Rolls Royce of television screens for years, with LED displays only recently being pushed into the forefront.

Rear Projection: Also called RPTV, rear projection TVs are effectively projectors casting high-resolution images on the back of large screens, similar to movie theater projectors, except contained in a television unit.

Composite: The yellow video cable that connects old-fashioned analog signal into televisions. Composite connections are only low-resolution, and are not ideal for HDTVs.

Component: A cable connection splitting video into three signals, allowing for HD signal.

HDMI: The standard for digital input, HDMI is a digital connection for devices to televisions, capable of output of high-def video and audio.

DVI: The PC input counterpart for HDMI, How-To Geek has already explained the differences between HDMI and DVI.

Liquid Crystal Display (LCD) Televisions

lcd television

Liquid Crystal Displays, or LCD, were the first type of monitor to provide the smaller profile, allowing for thinner displays that provide good picture quality. While they do not have the depth of color range or high contrast ratios of CRT monitors, modern LCD TVs have a good range of color that can light up even bright rooms.

Liquid Crystals do not emit any light, and have to be backlit in order to produce bright colors. (If you’ve ever owned a first generation Gameboy Advance, you’ll understand what a non-backlit LCD screen looks like.) When an HDTV is classified as an LCD television, it usually means that it is backlit with CCFLs, or Cold Cathode Fluorescent Lamps.

Light Emitting Diode (LED) Televisions

led tv

While LED televisions are what is currently being pushed on consumers, they are not quite the breakthrough that the commercials would lead consumers to believe. LED televisions are actually LCD televisions that are lit with Light Emitting Diodes as opposed to the standard CCFLs, discussed in the LCD section, above. They do offer certain advantages, but as they are the new tech offered to consumers, they are pricier than older models, and do not necessarily have the best picture because they are newer.

CCFL-style LCD televisions and Plasma televisions use more energy than LED lights, which are extremely energy efficient producers of extraordinarily bright light. For this reason, LEDs are offered as the “Eco-conscious” alternative to Plasma and traditional LCD. They are also free of harmful chemicals like mercury.

There are two styles of LED televisions. One is called “edge-lit”, with lights set around the television frame; the other is “full-array,” with lights set behind the screen in a grid pattern. Edge-lit models reflect light into the center of the monitor, and are the thinnest, lightest models available. Since they have fewer lights inside, edge-lit LED models are cheaper compared to full-array models. Full-arrays, however, have the best contrast ratios in LED technology.

LED does not quite live up to the contrast ratios and colors Plasma displays can create, although they do have excellent image quality and contrast ratios no standard LCD screen can hold a candle to.

Plasma Televisions

plasma ball

When electric currents (electrons) are passed through positively-charged gasses (protons and neutron nucleuses) inside bulbs. This soup of electrical current and ions is called “Plasma,” and emits light (photons) at different wavelengths (colors). So what does this mean for your television?

Plasma screen televisions produce some of the best image quality consumers are likely to find. Their model is well suited for larger screens, and provides some of the best contrast ratios and colors available. Plasmas are also small profile, thin monitors, capable of being hung on walls like LCD or LED televisions. Pixel response is also a key benefit to plasma televisions; their images are rendered quickly, countering image blurring effects of fast-moving images on screen, providing clear pictures. In addition to all of this. Plasma televisions also have the widest angle viewing image, with quality constant from direct, in-front viewing to side angles, delivering a better picture to a larger crowd.

While they can provide some of the best images, Plasmas are the biggest energy hogs of modern flatscreen HDTVs. While many are Energy Star compliant, LEDs consume less power and contain fewer harmful chemicals. Eco-conscious and ethical gadget buyers may wish to consider this when buying a television. Plasmas are also more vulnerable to burned-in images than LCD/LED flatscreens if users are not as careful as they should be.

Rear Projection Televisions (RPTVs)

RPTV

The forgotten ancestor to theater televisions, RPTVs still have a lot to offer consumers. Since they are lit from the back by projectors, their contrast ratio is somewhat more limited, and their images look best in dark rooms. They are also thicker and deeper than any modern HDTV, which is usually a flatscreen to be mounted on the wall. While many modern projection televisions are thinner than older models, many consumers see this as a limitation, as space and viewing distance may be an important buying factor.

You’ll find that RPTVs are surprisingly lightweight, because they are almost entirely empty space. Moving an RPTV is a simple task, while some dense flatscreens may actually be heavier by comparison.

Because the images are projected, the cost of huge screens is similar to the cost of smaller units, with excellent picture quality and reasonably price on units as large as 82 inches. By comparison, Plasma or LED screens of that size would be so outrageously expensive, most stores would not care to carry them. Despite their shortcomings, RPTVs can deliver an excellent HD experience to the budget-conscious home theater.

3D-Capable Televisions

3d tvshot

Capitalizing on the current 3D movie trend, many HDTVs are including 3D-Capable hardware in their monitors. 3D Televisions and hardware are complex, confusing, and potentially very expensive. Stay tuned to How-To Geek for a complete rundown on 3D HDTVs, and what you’ll need to get 3D in your home theater.


Many readers will find that this guide doesn’t offer any clear-cut answers as to “which HDTV is better?” There is no objective answer, as each buyer will have unique needs. Video game players might enjoy the fast refresh and bright colors of LEDs, and sports and movie buffs may like the better contrast ratio and better colors available in Plasma TVs. Others still may want to recreate the theater-like experience with an enormous Rear-projection TV in a large dark room. Spend some time thinking about your own situation, and this guide can help you make a more informed decision for your own needs.

Image credit: First two images by the author, available freely under Creative Commons. Unnamed cables image by GKS, available under Creative Commons. LG TV Image by LGEPR, available under Creative Commons. Led 1 by Alessandro Vannucci, available under Creative Commons. Plasma Ball by BlazerMan, available under Creative Commons. DSCF1457 by lyrislite, available under Creative Commons.

Source: Howstuffworks.com; FirstGlimpse , July 2009 Issue.

Edit: Some helpful readers have pointed out that I had  flipped around a key feature of edge-lit versus full-array televisions. After looking back at my source, I found that its wording was confusing, and had to switch the one key fact about edge-lit and full-array televisions because I had read it wrong.

Eric Z Goodnight is an Illustrator and Graphics Geek who hopes to make Photoshop more accessible to How-To Geek readers. When he’s not headbanging to heavy metal or geeking out over manga, he’s often off screen printing T-Shirts.

  • Published 12/6/10

Comments (47)

  1. InDiSent

    Shouldn’t this (“CCFL-style LED televisions and Plasma televisions use more energy than LED lights”) read :
    CCFL-style LCD televisions and Plasma televisions use more energy than LED lights?

  2. The Geek

    Thanks for spotting that typo… will fix it right away.

  3. Duckbrain

    I think “Plasma screens televisions” should read “Plasma screen televisions”.

    Thank you for this guide. I have been trying to help my dad with some of this stuff, but I did not know enough about it. This is great because it outlines how to choose what type of TV you need for your uses. I also like that you provided some definitions for those terms that they use for TVs. Keep up the great work.

  4. Will Zegeer

    I’ve always heard that Plasma’s life span is shorter than the others. Is that true?

    =)

  5. Jedijax

    Impressive article. Not too “techie”, and yet thorough enough for me to understand and explain to most people Geek, you are a life-saver!

  6. Antrikshy

    As many readers may ask, plasmas do have a shorter life span because of the technology they use. Also, if you leave an image paused on out for days, the colours might get ‘stuck’ on them. Moreover they are big energy hoggers. That is why very few companies are still producing them.

  7. Béranger

    I hoped you will address a major issue, but you didn’t.

    The term LCD is abusive. The correct term is TFT or TFT LCD.

    LCD is that 80ish monochrome (gray-greenish) display with no backlight that is still used in some watches. There is no silicon in them.

    What people abusively call today LCD is actually Thin-Film Transistor TFT (TFT-LCD), with an active semiconductor matrix. A hugely different technology and a tremendous improvement.

    And LED is actually AMOLED (Active-matrix organic light-emitting diode), right? Not like the LEDs you can have on front panels and in some torches…

  8. cg

    Great article. This sentence is a bit confusing though

    “LED does not quite live up to the contrast ratios and colors Plasma displays can create, although they do have excellent image quality and contrast ratios no other display can compare to.”

    Do LEDs have better contrast ratio than plasma or not?

  9. Gouthaman Karunakaran

    That was an eye-opener. Like you mentioned in the article LEDs are hyped in the commercial. But, I still can’t understand why they are so pricey!

  10. Ivan

    2007 58″ Panasonic Plasma – 720 Watts
    2010 63″ Samsung Series 8 Plasma – 500 Watts

  11. pitman

    This article came at a perfect time because they started promoting LEDs here and I was wondering what the fuss was all about, also people usually come to me for electronic advice (since I’m a tech-guy) and now I can tell them what is all the LED rage.

  12. sam0t

    Is the following statement really correct, it is in conflict with information I read on another site.


    Edge-lit models reflect light into the center of the monitor, and need a larger profile to have enough room to do this. Since they have fewer lights inside, edge-lit LED models are cheaper compared to full-array models. Full-arrays, however, have the best contrast ratios in LED technology, and are the thinnest, lightest models available.

    http://www.ledtele.co.uk/whatisledtv.html

    According to the site linked above, the edge-lit LED models are thinner than full-array ones. Maybe there has been advancements in the field and the link I posted is not valid anymore, but which one is more correct today?

  13. Fabian

    Are you sure that the “Full-array” LED’s are really the “thinnest and lightest models”? Afaik the edge-led’s are thinner because they can utilize flat light guiding structures to distribute the light from the edge to the center whilst full-arrays have to have the room for the led array matrix behind the screen making them thicker.

  14. Geoff

    “effecting the way” should be “affecting the way”

  15. Eric Z Goodnight

    Thanks for spotting those typos. In particular, I kept typing LED when I meant LCD, or even CRT when I meant LCD.

    @Fabian, @sam0t: I’ve checked my source and what you’re pointing out is correct–the source was simply worded poorly, and I was misinformed by what I thought it said. I’ll change it immediately.

  16. Hatryst

    Another very informative article !
    And this proves that there’s no room for CRT TVs now :)

  17. Bobro

    nice artical…

    if we can get some info on OLED screens too that would be cool (also are these the ones that can be just a display on a clear material that can then be rolled up whilst the image is still being displayed (there is a vid on YouTube of this, it is cool!!)

  18. Bob Bowen

    I’m still “in the dark.” What is the best desktop monitor for the home user, LCD or LED, Plasma being too too power-hungry? Good, article, though, because now I understand what these terms mean. The answer seems to be LED? But is it? Thanks.

  19. GaGator

    Thanks for timely and helpful article. I am in the process of
    replacing my older 4:3 ratio SONY desktop HDTV and now
    know exactly what I need.

  20. Daniel

    @Béranger: no, it’s not AMOLED. The LEDs used in ‘LED’ televisions are much more like the ones found in the torches. AMOLED screens will be the next hype in this market, but today they’re yet too expensive.

  21. Daniel

    Béranger: no, it’s not AMOLED. The LEDs used in ‘LED’ televisions are much more like the ones found in the torches. AMOLED screens will be the next hype in this market, but today they’re yet too expensive.

  22. mrphil

    OLED TV’s are already in the marketplace and have been for a couple of years.. albeit they are mostly portable size, but they are Televsisions and so deserve a place in this article regardless of their ridiculous price tag. This article is a great reference for newbies.. please update to include OLED :)

  23. Colin

    A very interesting and informative article. It seems manufacturers are fudging over their claims again! When I read about the new LED models being launched I assumed (stupidly) that they would ALL be the ‘full array’ type that would switch off the back-light in areas of black in the picture to create truer blacks and massively increasing the contrast ratio. So, it seems we are being sold LED models as the next big thing when the majority are simply edge lit and replacing the CCFL’s? Not so ‘cool’ after all :0(
    I too would like to hear about emerging technologies such as OLED and UHDTV?

  24. Al

    Several years ago I purchased a 65″ RPTV and have been very satisfied. The lamps have limited life but the replacement was $160 after 3+ years of steady service. This was much better than the $400 they were when I purchased it. The plus is a really big screen for a budget price and the image quality is good. The short coming is the viewing angle is pretty limited. If you sit right in front of it, it is really great but the picture quality diminishes as move off center.

  25. Larry Bumgardner

    One more problem with plasma…I understand about 5% of the viewing public can’t look at a plasma and get a clear picture due to the way it presents a picture to the eye. I remember reading this and can’t remember the details about why this is so.

  26. nicky

    Hi Will Zegeer
    My top of the range Panasonic lasted 4years and cost nearly £2000,the screen went blank, it was to costy to have repaired so it ended up on the rubbish tip,I now have a Sony,don’t believe all you read about top of the range equipment.

  27. kzinti1

    According to C/NET, Plasma TV’s are also being phased out over the next couple of years.
    Why? Manufacturers are pushing 3D capable TV’s. Even when most people don’t even want 3D.
    I certainly don’t want 3D. Those glasses give me an almost instant migraine.

  28. Ram Agarwal

    very informative article…

    Eye opener for me…

    Thanks a lot HTG…….

  29. LaRoy Tymes

    I live at an altitude of 7300 feet. Plasmas do not work well above about 3000 feet.
    I have a DLP (Digital Light Processor) that works very well. What is the future of the DLP???

  30. Eric Z Goodnight

    Interesting they wouldn’t work at high altitudes, but given that they operate using gasses, it seems logical that the change in pressure affects it.

    DLP is a Projection technology, isn’t it? It’s supposed to be a good model for such, although the companies only seem to be interested in marketing the newest thing–3D television, LED, OLED. I would say that its support is limited, unfortunately. They’re going to keep pushing out the “newest thing” to keep people rebuying every couple of years.

  31. Camilo Martin

    Has anyone tried plugging a computer on a digital projector?

  32. indianacarnie

    think the people complaining about typos are nit-pickers and distracting from the very useful information the geek has given us free. lighten up you guys! we’re not all english majors or 1000 wpm typists.

  33. Mike McPherson

    The information, which was presented was very informing. A question that I have is about cables, you presented that HDMI handles 1920 X 1280, what cable handles 2560 x 1600 pixels you mentioned in the DVI information?

    Sincerely,

    Mike

  34. glenn

    Why is this scam auction link on your site?

    Ads by Google Top 10 Best LED TVs Rated
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    GeniusFind.com/LED-TVs Laptops Sold for $33.33
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    These folks should be in jail!

  35. glenn

    Amended to show the culprit!

    Laptops Sold for $33.33
    Today: All HP Laptops are Sold for up to 98% Off. Buy Yours Today?
    QuiBids.com

  36. Karakero

    really great article. thanks :D

  37. Paul

    I think the opening comments about frame rates is potentially misleading. You are quoting sub frame rates which improve fast motion smoothness but are sub fields not actual screen renders.

  38. Paul

    Just to throw a spanner in the works Sharp now has Quattron which adds yellow pixels to red, green & blue. Supposed to give more vibrant images and brighter yellows. But I Haven’t seen out for myself.

  39. James

    Almost all modern rear projection televisions use DLP technology. It is a very cost effective way of producing large screen sizes, especially anything larger the 65″. DLP is extensively used in front projection, along with LCD.

    With plasmas I wouldn’t pay any attention to the rumors that they are “being phased out in X years.” That rumor has been around for at least the six years and has yet to come true. Also, don’t worry about life span, the newest models have typical lifespans of 60,000+ hours and for the LG INFINIA 60PX950, its lifespan is 100,000+ hours. By comparison, a plain old CRT’s lifespan is around 80,000+ hours. Finally, lifespan is used to measure how much time it takes for a monitor to output half of its original brightness at the same settings, so once a monitor reaches its lifespan it should still work just fine.

    One thing that this guide didn’t touch on was screen size. I would add that for any TV under 42″, get a 720P monitor. It will be cheap then a 1080P version and most people will not be able to see the difference. Also, when you start getting above 50″ there are fewer and fewer LCD’s and plasmas become to primary option.

  40. glowflu

    super NIFFTY AND NATIOUS

  41. glowflu

    its niFFTY and led rocks and its niffty somtimes people fart but im not fat kk

    !!!!!!!!!!!!!!!!!!!!!!!!!1

  42. Ja5087

    But CRTs have a long life, I still have my 10 year old CRT in my house for watching movies in the dark.

  43. nirmala

    this article is good. But it doesnt give good differences between lcd,led,plasma

  44. Stephen Blaine

    Nobody has addressed plasma TV heat.

    Go to any show room, e.g. Best Buy. Place your hand on a plasma TV that has been on for a few hours. It will be very hot to the touch. There are numerous posts on the internet that a plasma that has been running for several hours, in a den or living room, can heat the room noticeably.

  45. horrido

    Yes, plasmas run hot, but no hotter than CRTs. Plasma’s have far richer colors, and darker blacks. I love the glossy screens, but reflection can be an issue on sunny days. After getting used to a plasma, the matte screens on LCD look so dead.

  46. PAUL

    :) :)

  47. amber

    hi there. hopefully someone can help me out. i am new to this led and plasma stuff. i have owned a panasonic reg tv now for 14 years so i want to get with the time i guess slow starter i am. anyways i am looking at 2 models of tv one is the samsung led un55d8000 y model and a panasonic plasma viera tcp55gt30 again i know nothing about these tvs if anyone could tell me which one is the best out of the 2 i would really appricate it. thank you all for reading amber

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