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Monitor Basics - LCD vs. CRT

Herbal V wrote in with a little article discussing the differences between LCD and CRT. Briefly summarizes all the major issues (Price, Refresh Rate etc). More of a beginner level piece, but as LCD prices are dropping like rocks, it's good to be aware.

33 of 521 comments (clear)

  1. Nothing for you to see here. Please move along. by LiquidCoooled · · Score: 5, Funny

    Nothing for you to see here. Please move along.

    Typical, a story about monitors comes along, and mine decides to censor it.

    --
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  2. Full article before their servers crash by mwsmith824 · · Score: 3, Informative

    Monitors - LCD vs. CRT

    As the technology has improved and the prices have come down, LCD (Liquid Crystal Display) monitors have rapidly been replacing CRT (Cathode Ray Tube) monitors on desktops around the world. ComputerWorld first reported that LCD sales would surpass CRT sales for the first time in 2003, a lead that it didn't hold for good. But according to DisplaySearch, a flat panel display market research and consulting company, the sales of LCD monitors regained the lead over CRT sales in the third quarter of 2004,a lead that it should eventually hold for good.

    The question is why choose LCD over CRT? There are several pros and cons to consider, and a few items will be considered in this Tech Tip, such as: Price, Size, Image Quality, Energy Consumption, Personal Comfort, and Response Time.

    Price

    The price of LCD monitors is much lower than a few years (or even months) ago, but still far exceeds the price of a comparable CRT monitor. For example, I spent about $600 (US) on a Viewsonic VA-720 17" LCD monitor in early 2003, and see that the same model now sells for less than $300. A significant price drop, but in comparison a 17" Viewsonic CRT monitor can currently be purchased for less than $100. The ratio of prices may have narrowed from about 5:1 to 3:1, but the aging technology behind CRTs still allows it to hold the lead.

    You can't even compare prices of CRTs to LCDs in ComputerGeeks.com's monitor section as they are right in step with the sales information provided above, and now only carry LCD monitors. Prices vary, even among LCD monitors of the same screen size, so there has to be something more to it than price.

    Size

    One reason that LCDs have gained in popularity is because of their small foot print. The overall size and weight of CRT monitors far exceeds that of LCD monitors. CRTs share the same image processing technology with tube televisions, and therefore share the same bulky style of housing. For example, the manufacturer's web page lists this ACER 19" LCD monitor as having a depth of a mere 6.9" (including the base) and a weight of 12.1 pounds. As a point of reference, a 19" ACER CRT is significantly larger with a depth of 16.86" and a hefty weight of 46.31 pounds.

    Desktop real estate is precious, and an LCD will require only a small fraction of the depth that a CRT would require. And if there isn't even enough room on your desk for a slim LCD monitor, the low weight makes them perfectly adaptable to be hung on the wall, or off of a radial arm mount, such as this one from Office Innovations.

    Image Quality

    Image quality is generally considered to be better on an LCD, as each pixel is generated by a specific set of transistors in the screen, which produces a crisp image. But some features that fall under the general heading of image quality might not favor an LCD, including viewing angle, brightness, and contrast.

    Early LCD monitors had a fairly narrow viewing angle that made clearly seeing the screen from anywhere but directly in front of it difficult. This has improved greatly, but still doesn't quite rival the viewing angle of CRTs which provide the same picture quality regardless of the angle. A monitor with a maximum vertical viewing angle of 120 degrees should not be hard to find at this point, with many monitors now being able to provide an even greater angle.

    Brightness is an area that LCD monitors may have the edge over CRTs, but it varies widely from unit to unit. The standard measure for brightness is referred to as "nits", which have units of cd/m2 (candelas per square meter), where a higher number is better. Looking at three of the 17" LCD monitors currently available from ComputerGeeks.com as examples shows two with brightness specifications of 400 cd/m2 and one with a brightness specification of 250 cd/m2. As a comparison, the typical CRT monitor may provide half the brightness of an LCD, as confirmed at Viewsonic's Monitor University.

    Contrast is similar to brightness in the fact that

    1. Re:Full article before their servers crash by molo · · Score: 4, Informative

      I just got a 20" 1600x1200 LCD after years of using a 19" CRT in the same resolution.

      What this article does not talk about is color gamut. CRTs are able to display a much wider range of color compared to LCDs. Any application where color is important (desktop publishing, graphics work, etc.) will want to use a CRT for the forseeable future. On this LCD, whites are not really white, blacks are not really black.

      That said, the LCD display really does very well in two areas: 1) lack of refresh rate, even at 60Hz things are nice and solid. 2) lack of convergence artifacts. Because each pixel has seperate addressable color components, you don't have to worry about gun convergence like CRTs. Individual pixels are nice and sharp. On lower priced CRTs (particularly OEM ones) convergence is often never quite right. If the convergnce is adjusted properly for one area of the screen, it will be off in another. Buying a higher priced CRT will end up with better results, but be sure it is always transported in its original packaging, or else the convergence can get shot to hell.

      Both CRTs and LCDs have their probelms and benefits, and the choice between them depends on what your application is. For my purposes, I think I will end up going with a CRT and LCD dual-display system. I'll see how that goes.

      -molo

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  3. Website go boom! by Trifthen · · Score: 4, Funny

    And now, what was described as a quick and useful overview of LCD vs. CRT displays, has become neither.

    Anybody else see the irony in this?

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    Read: Rabbit Rue - Free serial nove
    1. Re:Website go boom! by LakeSolon · · Score: 3, Funny

      Anybody else see the irony in this?

      Uhm. Not really, no.

      ~Lake

  4. 2 Years On, On LCD by ackthpt · · Score: 4, Interesting
    2 Years and I still love my Samsung Synchmaster 172t, though my only gripe is it's TOO BRIGHT! Even on the lowest settings I think I'm getting some sort of tan. Manufacturers may wish to consider some users sit in dark rooms, plugging away at nefarious^H^H^H^H^Hworking very diligently on upstanding fine projects their mothers would be proud of!

    Thing even came with a wall mount, too bad I live in an apartment (though toothpaste does have its other uses...)

    Size is great, too, because a 17" LCD is almost as big as a 19" CRT :-)

    --

    A feeling of having made the same mistake before: Deja Foobar
  5. What drops? by Morgahastu · · Score: 3, Interesting

    Everyone has been talking about LCD price drops for the past 2 years but it just has not happened. I've been in the market to buy an LCD monitor for the past 2 years and I have not seen any significant drop.

    With all the news of companies dropping plasma, more LCD plants being opened, production being increased, technology improving, why hasn't the price of LCD monitors been cut in half?

    I think it's because it has the cool factor that lets the companies sell it at whatever price they want.

    Look at the quality of LCDs in some laptop and how cheap they are. OFten times a comparable LCD for a Pc would be more expensive than he laptop WITH the lcd.

    1. Re:What drops? by sootman · · Score: 4, Informative

      I've been in charge of buying flat panels for my company for the last few years. In that time, 20" LCDs from Dell have gone from $2000 to $599. In the same time, high-end Apple LCDs have gone from 22" 1600x1024 for $4000 to 30" 2560x1600 for $3000 (plus a $600 video card to run it.) If you haven't seen any drops, you haven't been looking very hard. As for your last point, I can go to CompUSA and buy a 17" LCD for $279 or a 15" laptop for $649.

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  6. Response time by Monkey+Angst · · Score: 5, Interesting

    The article only briefly mentions response time -- doesn't explain it. Response time was the reason I returned the LCD I bought and went back to my CRT -- DVD playback was awful. I imagine there are people who don't notice it, just as there are people who are more sensitive to lower CRT refresh rates, but it was hellish for me.

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    1. Re:Response time by Jeffrey+Baker · · Score: 3, Informative

      The manufacturers don't give enough specifications to evaluate the response time properly. The response times refer to a fully-off to fully-on step transition, which is actually the fastest response a CRT has. A change from 50% gray to 51% gray will be very slow, by comparison, and that's much more important for video. Some LCD displays have circuits that intentionally overdrive the pixel to get faster small-signal response, but it is difficult to find out which manufacturers to this. The best way is to hook up a video source and just watch it.

    2. Re:Response time by kmo · · Score: 3, Informative
      Response time was the reason I returned the LCD I bought and went back to my CRT -- DVD playback was awful.

      A response time of 40ms means it takes a pixel 40 milliseconds to change color. At that rate, it can change 1/.040 times per second, or 25 frames/sec if new images are perfectly in sync (and they never are). That's slow enough that most people will notice rapidly changing images bleed into one another as the pixel is given a new value more rapidly than it can change. Thus a 40ms LCD is a poor choice for action games and DVDs. It may be fine for web browsing, word processing, and email.

      Newer LCDs typically have 25ms (40 fps), 16ms (62 fps) or even faster response times. Look for them if that's important to you.

  7. Health Issues by Drexus · · Score: 5, Interesting

    It's funny, the main reason why I dumped 3 of my 20" Sun monitors for an Apple Cinema Display was the health issues. Sure, we have herd all the stories about special cameras that can read the material on your CRT through walls (and the person sitting in front of it), but that didn't stop me. No, I went ahead and set myself up with enough radiation to cook lunch. 5 months later, I found myself having trouble shaking off common colds, and my appetite went down hill. People should be aware of the health issues, not just specs.

    1. Re:Health Issues by .orvp · · Score: 5, Interesting

      I switched to an LCD for health reasons as well, just a different one. Mine dealt with the refresh of a CRT. When in college, I had a 19" CRT that I would program on. At night, I was having a hard time falling to sleep, and so when I couldn't sleep, I went back to programing. This really messed up my sleep patern to the point I was at a 26 hour day (where I could only fall asleep every 26 hours). That doesn't really help when trying to go to classes.

      After a while, I would just fall asleep at random points because of sleep deprivation, missing classes and all. When I finally went to a sleep doctor, I learned it could be from the refresh of my CRT. I then moved to an LCD and haven't had that problem. I can now sleep 10 minutes after getting of the computer where as before I would need to wait 90 minutes for my brain to wind down.

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    2. Re:Health Issues by Photon+Ghoul · · Score: 4, Insightful

      5 months later, I found myself having trouble shaking off common colds, and my appetite went down hill. People should be aware of the health issues, not just specs.

      I'm not trying to troll here, but maybe... just maybe.... those health issues aren't from sitting around in front of 5 CRTs necessarily, but maybe years of just sitting around, period.

      Exercise improves your health and your appetite.

  8. Too Cool for School by MrAsstastic · · Score: 5, Funny

    Un ortun tely, my LCD sc een su fer fr m a h rible case of de d pixels. So tim s it is very dif cult to re ly to the any gre t ar icles on Sla dot and other f ne for ms. Oh wel , I will gladl pay the price j st so hat I may ska e on the e ge of the raz and la gh at t se moron with their big du b box . Ha Ha Ha !

  9. Save you energy, health, and space! by garcia · · Score: 5, Informative

    I just recently purchased my first Mac. Scary I know but I promise not to become a Slashmacbot... Anyway, in line with the purchase I figured why not move to an LCD setup as well? This article explains several of my reasons for doing so but leaves one out...

    Energy Consumption

    LCD monitors definitely hold the edge over CRT monitors when it comes to being energy efficient. The huge tube in a CRT monitor is the source of most of its energy consumption, and a comparably sized LCD may use just a fraction of the electricity. Taking a look at this 19" Jetway LCD monitor shows that it consumes 48 Watts during normal operation, which is less than your typical light bulb. In contrast, a 19" CRT such as this one from Viewsonic may draw up to 160 Watts. Therefore the fraction of electricity used in this case is 3/10, and could translate to noticeable savings on your electric bill.


    I currently have two 17" CRT monitors on my L-shaped desk. One is a newer model "flat screen" and the other was a freebie HP branded CRT. I know that they are sucking power and sending that power back out as radiation directly into the side and front of my face (as they are surrounding two of the three sides of my head). I have switched to a lot of energy saving bulbs in my house and I plan to switch more as the bulbs die off. I have switched to a programmable thermostat (that isn't 5 degrees off like the one that the original owners had) to save electricity/gas during the day and evenings. Why not my computer crap too?

    I have even gone so far as to make sure that if I am not going to be home for more than 24 hours my non-essential computer equipment is off. A few bucks here and there equals beer later.

    Personal Health and Comfort

    The main benefit that LCDs have when it comes to comfort is the reduced strain on your eyes. The reduced glare on the screen's surface, and the elimination of a typical CRT's "refresh", can prevent your eyes from getting tired from extended use. A CRT monitor redraws the image on the entire screen as it refreshes, whereas an LCD monitor only changes the necessary pixels during a refresh.

    There may also be the unquantifiable effect of reduced electromagnetic emissions on LCD monitors. The exact impact of electromagnetic emissions may not be fully understood, but in general less is considered to better, as addressed in this article. And, your back may also appreciate an LCD when it comes time to move, as the example above shows a 19" LCD monitor weighs about ¼ as much as its CRT counterpart.


    What I have noticed is that using both at work (and now both at home) that I have significantly MORE eyestrain. Moving back and forth between the two seems more harmful than just sticking with one or the other. Sadly I am going to be in this situation at home for a while yet but at work I have only this 20" CRT to replace. The 23" LCD is in IT and waiting for install so it won't be too long. I was QUITE surprised when I went to pick up the 17" LCD at the FedEx hub that it fit easily in my trunk and was light enough for me to hold with one arm safely. I can't say that much about lugging my 17" CRTs around. Woo for that.

    My other reason for loving LCDs is desk real estate. With my CRTs tons of desk space is lost to their screen, their rear ends, and their bases. With the new LCDs I have quite a bit more room to stack cans, plates, etc. It also makes me feel more "free" to move around in the tight space that my computer area is located.

    I look forward to my second LCD at home and the savings in health, energy, and space it will give me.

    1. Re:Save you energy, health, and space! by gkuz · · Score: 3, Funny
      (as they are surrounding two of the three sides of my head)

      If I send you my e-mail address, can you send me your picture? I've never run across anyone with a triangular head before.

  10. Re:horizontal or vertical frequencies? by Anonymous Coward · · Score: 4, Funny

    I know the answer to your question but I refuse to answer you because you're an iPod whore.

    I hate you.

  11. Don't forget ClearType on your LCD by Lev13than · · Score: 5, Interesting

    Kind of OT, but important - if you are running XP with an LCD screen, don't forget to turn on ClearType. ClearType dramatically improves the quality of text displayed on screen, to the point where my work laptop almost looks as good as my OS X box w/CRT at home.

    ClearType takes advantage of the fact that LCDs make coloured pixels out of three adjacent sub-pixels (usually R-G-B), rather than a CRT which focuses all three of its guns on the same spot. By varying the intensity of the three colours in each pixel, ClearType effectively triples the horizontal resolution of type. The trade-off is some slight colour-banding in small fonts, but the payoff is a much more readable screen.

    I stumbled across the settings by accident. With the increasing popularity of LCDs, I'm surprised that Microsoft doesn't promote it more.

    --
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    1. Re:Don't forget ClearType on your LCD by Hoplite3 · · Score: 4, Informative

      This is known in general as "sub-pixel rendering". It's available in Linux and on Macs. Check a control panel / system settings / control center module near you!

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    2. Re:Don't forget ClearType on your LCD by TheRaven64 · · Score: 3, Interesting

      I don't know if this is true of Windows, but when you take a screen shot in OS X it stores the sub-pixel anti-aliasing in the screen shot. It's quite interesting to zoom in so that a single character fills the screen, and see how it works.

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    3. Re:Don't forget ClearType on your LCD by Malc · · Score: 4, Informative

      Actually, CRTs are also made of separate coloured elements. I don't think ClearType can be used though because it's very hard (impossible?) to address individual screen elements accurately with a CRT.

    4. Re:Don't forget ClearType on your LCD by Anonymous Coward · · Score: 4, Informative

      You need the ClearType Tuner PowerToy ClearType Tuner (New) This PowerToy lets you use ClearType technology to make it easier to read text on your screen, and installs in the Control Panel for easy access. Cleartype Tuner PowerToy

    5. Re:Don't forget ClearType on your LCD by sootman · · Score: 4, Informative

      Here's a great overview of what cleartype is and does and how it works. Also, in OS X, go to System Preferences, Appearance. If you choose "medium - best for flat panel" that will activate sub-pixel rendering.

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    6. Re:Don't forget ClearType on your LCD by LiquidCoooled · · Score: 3, Informative

      The difference between CRT and LCD is the arrangement of the pixel elements.

      In a CRT monitor, an individual pixel is made up as a triangle with RGB on each corner.
      However, on an LCD, the individual color elements are arranged in horizontal strips

      rgbrgbrgbrgb
      rgbrgbrgbrgb
      rgbrgbrgbrgb
      rgbrgb rgbrgb
      rgbrgbrgbrgb

      On a CRT monitor, a dot is basically a dot.
      On an LCD, its a strip.
      Cleartype works by performing antialiasing on these elements, but "borrowing" adjacent color elements.

      --
      liqbase :: faster than paper
    7. Re:Don't forget ClearType on your LCD by squiggleslash · · Score: 3, Informative
      In a CRT monitor, an individual pixel is made up as a triangle with RGB on each corner.
      Kinda. The problem actually isn't this (as others have pointed out, the precise pattern varies by CRT and some do use strips), but that computer pixels and CRT pixels are not one-for-one matches. CRTs tend to be "as many dots as the manufacturer could fit", and the red beam strikes red dots, blue blue, green green, etc, and all the red dots that the red electron beam is passing are illuminated during the time the red pixel is being transmitted.

      As a result, this kind of anti-aliasing just isn't possible with a CRT. You can't really know, programatically, when each colour dots are going to be illuminated.

      By comparison, LCDs have a 1:1 pixel colour component to screen pixel colour element mapping (assuming you're running it in full resolution of course, but if you have a 640x480 view stretched to fit a 1024x768 LCD screen then it's going to look pretty ugly regardless...), hence this trick works.

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    8. Re:Don't forget ClearType on your LCD by operagost · · Score: 3, Informative
      That's fine, but I've found that Cleartype helps a lot if you're using your LCD in its non-native resolution. My Jetway's is 1280x1024, but I don't like that mode because it actually messes up the aspect ratio of the screen. If I run at 1280x960, the ratio is correct but some text looks a little chunky. Cleartype largely corrects this.

      This was a beginner's article, but the author probably should have mentioned these other caveats with LCDs:

      Native resolution issue mentioned above.

      Dead pixels. Unless you have several, mail-order companies won't issue an RMA. I bought a model that was reviewed on newegg.com by umpteen people and many said they had no dead pixels. Naturally, mine does. Fortunately, it's only one.

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  12. It's easy. by Realistic_Dragon · · Score: 4, Funny

    Do you have a big desk?
    Buy a CRT.
    Spend the rest on booze and hookers.

    Do you have limited space and/or need to move around.
    Buy a LCD.
    Pay for booze and hookers with a credit card.

    --
    Beep beep.
  13. Re:horizontal or vertical frequencies? by Akaihiryuu · · Score: 3, Informative

    It depends...if you're using the VGA input, the card is still outputting an analog signal with refresh. It's handled within the monitor with an analog to digital converter. So as long as you don't specify frequencies or refresh rates that the converter can't handle, there's no problem. I usually just set mine to 75 Hz. If you're using DVI, then none of that applies...but monitors that support DVI are still too expensive.

  14. Instead of a summary.... by Elledan · · Score: 4, Informative

    Try this article for a good overview of the different types of LCD panels (TN, MVA, PVA & IPS):

    X-bit's Guide: Contemporary LCD Monitor Parameters and Characteristics

    It weighs in at 27 pages, but if you really want to know what you're talking about when discussing LCDs, it's required reading.

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  15. Re:Geek news??? by LiquidCoooled · · Score: 5, Insightful

    Actually, these beginner guides and technology simplified articles are handy for us geeks to have.
    Presenting facts and information to the layman can be a difficult task, and its good for us to see how its done.

    Instead of us all saying something like "let me try try to explain it" to a family member or friend, you can direct them to an article written with them in mind, and with enough information to answer most of their queries.

    --
    liqbase :: faster than paper
  16. When I was a kid by khrtt · · Score: 3, Funny

    How do my fellow Slashdotters recycle their old CRTs?

    Out the window, then drop a mallet on it (literally, out the same window), repeatedly, until the screen with the metal frame around it is the only part remaining, and the rest is pulverized. The screen will be the only part remaining, because it's a half-inch thick glass, as opposed to the wimpy glass in the back part of the tube, and the cheap plastic that the rest of the thing is made out of. Then take the screen, line it with a doormat, and ride it off snowy hill. Glass has a really small friction coefficient against snow.

    Don't try this at home:-)

  17. Good pixel response == great gaming on LCDs by MooseByte · · Score: 3, Informative


    Don't give up, give a quality LCD a try first and you may never go back.

    Response time is a critical feature for me. I won't buy any LCD screen unless it's in the 16ms-or-better range for typical pixel response.

    My NEC LCD1760NX is great for games and movies. No hint of ghosting at all. Solid, bright, good footprint too. Digital/Analog connections as well.

    LCDs still have problems with color correction for serious graphics work, or so I'm told. But you couldn't pay me to get in front of a CRT anymore. My eyes won't take it.