LCD terms, what to look for.

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emericanchaos

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i've been looking into purchasing an LCD but while surfing around i found all these terms that i knew nothing about. i decided to do some research after posting in here and i made this little write up to help other people learn some of these terms and understand what is good to have in a LCD monitor and what sorts of things they should look for in a given monitor size.

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LCD.
An LCD is a liquid crystal display. LCDs are most often used for notebook computer screens and is used in electronic computer projection equipment. It is important to note that Liquid crystal displays do not emit light. They only control whether light gets through them or not. The specifics are quite technical and rely on something called the "polarization" of light. For more on polorization check out http://travel.howstuffworks.com/sunglass.htm

Active and passive matrix LCD.
Active matrix LCDs are more responsive and therefore appropriate for full motion video, computer animation, and fast mouse movement. Active matrix also provides a higher degree of color saturation.

Contrast ratio.
Contrast ratio is an average measurement of a totally white image vs. a totally black image at the 9 points described in lumens measurements. The higher the contrast ratio, the more vibrant the colors will be. Look for monitors with 250:1 or better.


Brightness
Brightness influences contrast (and thus readability) but it's more a comfort thing -- most CRTs display low-100s in brightness, so an LCD of any kind will still be 2x brighter. Brightness should be 250cd/m or better.

Color
Alot of companies will give you the number of colors. Most LCD's are 16.7 Million colors (24bit).

Dot Pitch/Pixel Pitch
The picture on your monitor is made up of lots of tiny dots of the same color. The dot pitch is the distance between dots that make up the image on your screen. The smaller the distance between dots, the better the image. .264 seems the be the best, most others are .29x. if you can get lower than .264 than you'll be very well off.

Response Time
Response Time refers to the screen's input signal reaction speeds, and the time required for the screen to turn from completely white to completely black and vice versa. Technically, this is referred to as the sum of (Rise Time (tr) + Fall Time (tf)). Response time is measured in milliseconds (ms, 1 second = 1000 milliseconds). In general, our eyes can take 24 successive still images per second as an active image. Movies for example display 24 images per second, and television displays 30 images per second.

Generally, lowest response is best. Response times on larger LCD's tend to grow higher. Try to stick around 24ms. On Larger LCD's (19"+) this will be somewhat difficult BenQ LCD's offer 17ms response times for 17" or smaller LCD's. The rest of their numbers are average. If gaming is your thing than these would most likely suit you best as the rest of their specs are about average but the ultra low response will offer smoother play.
 

Hookem

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Well IMHO response time is the most critical...16ms is the bar right now...Hictachi CML174 and a couple of others...If it has 16ms response time you should be gettin the very latest technology...;)
 

HotKoala

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Here we go. My guide for another friend who queried on the same topic. Decided to add so that it didn't seem incomplete and therefore leading to wrong conclusions.

Screen Size and Resolution:

LCDs are measured from one edge of the screen to the other. CRTs are measured from the it's physical edge to the other. As a result, while LCDs are smaller, its screen size is a few notches higher.

17" CRT - 15" LCD
19" CRT - 17 to 18.1" LCD
21" CRT - 19 to 20" LCD

Do remember a 19" CRT with viewable size of 18" is of course larger than a 17" LCD.

15" LCD 1024X768
17-18.1" LCD 1280X1024
19" 1280X1024 - 1600X1200
20" 1600X1200

Take into consideration the screensize and ratio if you intend to game. The lower you get from the native resolution, the worst the game will look, even if you do have a hardware calibration unit. Even worst is when the aspect ratios are different.

If your videocard plays at 1024X768 and no more, you'll be seriously dissapointed when you game on a 18.1" monitor. Or it can be a excuse to upgrade once again.


Contrast Ratio:

Light intensity from the brightest white to the darkest black. Higher contrast ratio means better colour reproduction. The better the colours will look and be displayed, the more detail and saturation. LCD range is from 150:1 to 600:1. They average around 350:1 and 450:1. 350:1 should be the minimum.

Contrary to popular belief, while CRTs are capable of displaying more colours than a LCD, many do not. You get what you pay for.

Colour Depth:

Most LCDs can display 15.2 million colours. That's 8 bits per primary. Remember, the alpha channel doesn't really exist. Merely a blend of the 3 primaries. To decrease the response rates, some manufactors start at 262K colours then use varying voltages to output 14.9 million colours.

As far as that goes, it's not much different from what most CRTs actually display. Again, even so, it is still preferred that you stick with a high-end CRT if you demand 100% colour accuracy. Tried and true.

Response Rate:

Mostly been covered by original poster. Just to add that some manufactors will usually state their tr time. You have to add tr and tf together to get the full response time.

In addition, they will commonly state those response time given several conditions. Say 80% contrast and 50% brightness. If you want full colours, you will bring those up and response will suffer. This varies upon monitors.

Being that there are so many ways mislead, a 30ms spec'd monitor may very well ghost LESS than a 20ms spec'd monitor. When contrast et brightness are turned up, same applies.

Refresh Rate:

Ignore this. LCDs don't flicker at 60Hz. Most glass screens only do 60Hz. Few will do 75Hz. Models that state they do 75+ are 90% of the time limited by the glass screen and circuitry anyways. Either way, you won't see any flicker.

Analogue or Digital:

Digital is clearly better to the keen. On LCDs will hardware calibration, it's subtle but still there. There are problems with using analogue connection to a LCD and those are usually sync problems. This leads to "shimmering" lines and irregular sized text. You can adjust it by eye or have hardware calibration do it for you.

All LCDs have adjustments by hand. If you don't know what it is, it's fustrating and usually leads to no gain.

Hardware is harder to come by in that they come on $1000+ models generally. But you get other features that are well worth it. Most are passable. EIZO's hardware unit is a whole in a league of its own.

As far as quality. DSub < DVI-A < DVI-D

Cables:

Not all cables are created equal. There is no such thing as a high quality bundled cable. While most of us would say it's very well good enough, it never hurts to get a new one if you experience excessive ghosting blurriness or dull colours. Do not mix and match cables as some meet the requirements for their monitor only. In that I mean, bandwidth. Higher resolution monitors require higher bandwidth. Using a cable from a 15" unit will be far from great on a 18" unit. Leads to horrid picture quality, shimmering, shaking, ghosting, et-c.

Brightness:

LCDs are all bloody bright. If you look at a unit over 250cdm^2 for too long, you're asking for trouble. Since LCDs do depend on the backlight for colour, take this into consideration. There are always gamma adjustments to make if dark areas are too dark. No different from a CRT.

Backlight:

While many manufactors use the same screen in their display, they will use different backlights. Quality will vary. Which is why, for example, NEC and Hitachi, even though they use the same panel in their 16ms monitors, the NEC has better colour.

Backlight are of very high quality nowadays. Many have a life of >40,000 hours. That's 4.5 years of 24/7/356. 9 years at 12/7/356. How many of you even do 12 hours a day?

Burn-in & Screen Fade:

Unlike CRTs, the LCD screen never degrades over time. It will be just as crisp 4 years from the day you opened it up for the first time. This makes it a very good long term investment. You can keep it att 100% contrast and brightness and it will never degrade. Do that on a CRT, and you've cut its life in half.

It is still possible to burn in an image on a LCD screen. Say, you left your desktop on for 12 hours. To rid of that, just run a screen saver the next time. If you actually did get a burn in image, again run something with motion for the same amount of time and the image will soon disapear.

Dead Pixels:

CHECK to see what the manufactor policy is on this. Some will let you return after 3 dead pixels. Some will be 7-8 sub pixels. Some will be 5 but only if they're noticable spot and/or in a cluster. If this bothers you, check before you buy.

Technology on dead pixels have improved by quite a bit from even last year. It's rare to have a fully dead pixel now. A dead sub-pixel is one that displays one colour and only that one no matter what the others are doing.

Not to be confused with a lazy pixel. These change a bit slower than the others. Usually, this is normal on a new or display that hasn't been used in a while. Use the screen for 5-10 minutes in some fast movement game and you'll find it has vanished.

Keep the screen clear of dust particles as those may block a pixel and you may see it as being dead till you wipe it.
 

HotKoala

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Again, not all LCDs are created equal. Here are real world specs of today's common LCDs.

Acer AL732: DVI, SubD, Video, S-Video in, nice design, small bezel, built-in speakers w/ 2x audio-in (PC and video), grayscale not pure gray, trise 14 ms, tfall 6 ms, 77-200 cd/m² contrast 576:1, settings for shortest response times: contrast 80, brightness 80, picture too bright and noticeable loss of bright grayscale detail at those settings.

ADI A715: DVI, SubD, nice design, built-in speakers, headphone out, height adjustible, poor analogue image quality, very good digital quality (on par with the others), ok interpolation (others are better, ALL screens always interpolate to full-screen, distorting the image a bit since they're 5:4), trise 12 ms, tfall 9 ms, 100-184 cd/m² (this might be too bright for dimly lit rooms, turning darker only possible by reducing contrast), contrast 394:1, settings for shortest response times: contrast 100, very noticeable loss of bright grayscale detail at this setting.

Hitachi CML174SXWB:
17", 262K/14.2M colours...blah display. Many others are much better using the same panel.

NEC-Mitsubishi Multisync LCD 1760NX: DVI, SubD, nice design IMHO, small bezel, height adjustible, problems with dark grayscale, but stays gray, doesn't become colored, brightness needs long to stabilize, trise 12 ms, tfall 5.5 ms, 70-250 cd/m², contrast 499:1, settings for shortest response time: contrast min. 50, brightness 100, picture too bright and slight loss of bright grayscale detail at this setting.
 

PhobMX

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IMHO the best balanced 17" LCD right now is my Hitachi CML174... 16ms response time and 450:1 contrast ratio for $475 is unbeatable. Not to mention view angles aint an issue :D
 

Cisco Kid

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Jan 13, 2001
I have to buy a monitor real soon and I figure I will go LCD. Up to now I have figured on the Nec 1760NX here in Vancouver for $670 canadian = $485 US. I PLan to buy local as well.

But I have come across the Samsung 171N Silver 17" TFT LCD , it does not have DVI but I can get for $70 Canadian less. Reviews I have found say it will game quite decently. I am not a huge gamer but I will game every other day or so for 30 minute to an hour.

Should I consider the Sammy based on my wallet or spend the extra for the NEC and benefit from DVI with my 9500 Pro??

What would be a good CRT in 19" for cheaper as I see they can be had for alot cheaper as well (this will prolly be another thread on its own)

Cisco KId
 

Hookem

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I have this Sony 19” CRT… http://www.sonystyle.com/is-bin/INT...tID=9aMKC0.NkDMAAAD1iDmOZmjy&ContentItemPage= Awesome specs…dual inputs…Probably the best electronics, specs and the picture aint bad either…But with the 24.dot pitch across the entire screen and what I consider the best picture is this Mitsubishi http://www.necmitsubishi.com/products/home/mitsubishi_index.cfm Warm, vibrant colors…Picture will knock off your feet…These monitors will come in about 360.00 to 400.00 and believe me they are really nice pieces…NEC, Samsung, make excellent aperature grill monitors…The ViewSonic P95 is a “best buy” in my book…Can be had for under 300.00…Here is a link that does a comparison of 19” CRT’s http://www6.tomshardware.com/display/20020319/index.html …Some good information, talks about shadow mask versus aperature grill technology…Good read…Of course I bought my Sony a couple of weeks before I found out about the Hitachi CML 174…But I have no regrets…Take a pretty high dollar LCD to hang… :D
 

HotKoala

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Heh, it has been stickied=)

One more to add before I'm off to work.

Dot Pitch(Desktop LCDs only):

The native/optimal resolution of the LCD unit is how many physical pixels it has. A monitor with a resolution of 1280X1024 has 1310720 pixels total.

On average it's something like:

15" 1024X768
17-18.4" 1280X1024
19 1280X1024-1600X1200
20" 1600X1200

The most common aspects are either 3:4 or 4:5. The diagonal completes the triangle. Let's take the 17" units because they seem to most popular and therefore more relevant to this crowd.

17" = 374mm

Therefore:

Vertical length = 270mm
Horizontal length = 338mm

To find pixel pitch:

Vertical Length / Vertical (Native) Resolution = Pixel Pitch

In this case:

270mm/1024=.264mm
338/1280=.264mm

Both are the same because, unlike CRTs, LCD pixels are square not rectangular.

.26mm is the standard for 17" monitors and you aren't likely to find any lower/better.

15" .297mm
17" .264mm
18" .28mm
19" .294mm for 1280X1024 models
19" .257mm for 1600X1200 models
20" .255mm

Note higher resolutions generally have higher pixel pitches.

Generally you won't find much deviation from that unless you've a wide screen or a Laptop(but they're a whole different story). But the formula for finding dot pitch is always the same. You can derive one or the other given two.

Desktop LCDs don't have a higher dot pitch mostly due to cost. They have to be somewhat competitive with the CRTs. Since you have sharper pixels on a LCD, the pixel pitch between the two can not be compared anyways.
 

HotKoala

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Penguin4x4 said:
Sorry for this somewhat n00bish response, but since both LCD's and CRT's share the same 4:3 screen ratio size (640/480 = 800/600 = 1024/768 = 1154/864 = 1600/1200 = 4/3), shouldn't it be 1280 x 960 instead of 1280 x 1024?

Not all CRTs and LCDs share the same aspect ratio.

1280X1024 resolution LCD monitors are naturally 4:5.

1024X768, 1600X1200 resolution LCD monitors are naturally 3:4.

While most CRTs are indeed 3:4 (draw a circle in a 4:5 resolution and you get an ellipse) I know of quite a few wide screen ones too. Their aspect ratios are also different.

Keep this in mind when you pick out a LCD. Does your card game well at 1280X1024? Are the vast majority of your games 3:4 aspect?(100% of those old ones are)

If so, does your monitor have hardware calibration?

If not, your games will either play in a tiny window in the centre equal to however many pixels the game uses, in the upper left corner equal to however many pixels the game uses, or stretched across the entire screen messing up the aspect ratio.

That last part was my experience with Matrox, nV, and ATi driver resizing. Their drivers all resize and position differently.
 

HotKoala

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Audioaficionado said:
Great sticky HotKoala
icon14.gif


How does the Benq FP767 analog only LCD stack up against the DIV competition? I've heard only good things but have you found anything about them I should be conerned about?

http://www.benq.com/display/lcd_fp767_specs2.html

I actually don't like them much. Colour quality is lacking compared to others using the same panel(meaning every single one I listed in this thread use the same 16ms panel. Other things such as backlight and electronics make some better than others.). I only posted the ones with DVI *and* analogue inputs using the same panels. Analogue only were skipped because DVI quality is simply better that instant. On an exceptional LCD however, you'd be hard pressed to see the difference. None of the above are exceptional LCDs.
 

HotKoala

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Up to your priorities. If gaming is your most important, then the 16ms are probably your best bet.

I perfer better colour and...well, just about everything else. I can live with the oh so slight ghosting that comes on 25ms panels.

If I were to buy a panel, not for myself, I'd def get the one you linked to there. How many people would know the difference or even really care so long as it's a LCD?
 

lightbulb8817

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My igloo
I'm glad I ran into someone that knows soooo much about LCD. I'm getting ready to purchase one.

What's the difference between the NEC 1760V and the NEC 1760NX? The V is considerably cheaper and they both use the same panels. There are differences in stand structure (I think)... but is there a difference is picture quality?

THANK YOU!

edit: I'm gonna cut to the chase-
Which 17" 16ms LCD do you recommend?
 
Last edited:

HotKoala

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SwishBish33 said:
HotKoala -

For someone who likes to game on a semi-daily basis, would a Samsung 957MB be better than a BenQ FP767? Is the color reproduction on that model really that poor? THANKS

What do you do other than game? Unless you photoshop; anything that doesn't need 100% colour accuracy, your eyes will thank you for getting a LCD over a CRT.

LCDs are getting more affordable. People are finally realising LCDs aren't anywhere as bad as their past myths.
 

SwishBish33

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Koala-

I'm a LCD newbie, and a CRT newbie when it comes to the real technical stuff, so please bear with me. What needs 100% color accuracy besides photo editing? Games? Nothing? I don't do any, or very little, photo editing, so that isn't important. Is the image quality (sharpness, brightness, etc) better on the FP767 (getting rave reviews from users on this forum) compared to a CRT, even one as good as the Samsung 957MB (that keeps getting rave reviews from people who have it also). I am willing to buy the 957MB over the FP767 if the image quality is better on the CRT, but if it is the same or better on the LCD, I'd rather get that as it would be EXTREMELY nice to have the desk space. Is the ghosting on an LCD noticeable too, even with a 16ms response? If that isn't a problem either, then the FP767 is the way to go. Also, Koala, just curious, how come you said you didn't like the FP767 that much? Sorry for all the questions. THANK YOU VERY MUCH.
 

HotKoala

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The FP767 is more than ideal for you then. Chances are you won't even notice the differences in colour reproduction unless you were trained to do it or worked on images where it was apparent to the eye(you'd see dithering when there isn't any on a CRT)

Ghosting isn't much of a problem on <25ms models. Numbers do vary though, across panels. I think you'd be more than happy with the FP767.

I don't like it because I'm a bloody elitist ******* that doesn't like to settle for less. Huge strain on the wallet though=P If I were to, say, choose between the highest quality CRT or the FP767, I'd go with the FP767 everytime for productivity reasons. Can't work if you have eye strain.
 

SwishBish33

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Koala -

So the image quality between the highest quality CRT and the FP767 is going to be the same? What's the risk of getting one with dead pixels? Thanks man. Never met anyone as knowledgable about LCDs than you. Thanks for helping me out. Just outta curiosity, where did all the LCD experience come from? Personal use?!?! If so, you the man!