LCD – For the Novice and the Expert
by Kristopher Kubicki on September 4, 2003 12:13 AM EST- Posted in
- Displays
Common LCD problems
What is ghosting?
Once upon a time, passive LCDs roamed the earth. Unfortunately, they were too slow and painful to look at for any extended period of time. 120ms response times assured anything over 7 frames per second left a lasting impression on your screen. Today, we have monitors that produce 16ms response times, although with the obvious sacrifice of color depth.Perhaps almost half of the people we talk to misinterpret ghosting. By definition from the VESA Flat Panel Display Manual, ghosting is actually the problem of interference over the signal, which results in an “echoed” image. However, misuse has somewhat skewed the word’s definition to also mean problems due to poor response times. To make matters more confusing, ghosting in the signal sense of the word and in the response sense are very hard to tell apart sometimes (especially if you don’t know what to look for).
We polled a few users in our forums that had “ghosting” problems. Three out of the five retracted their problem after we made them replace the analog signal cable with a DVI cable. Thus, we can infer that only two users really suffered from problems with the response time.
The new trend in LCD measurements is shifting to gray-to-gray response times, rather than black-to-white. As we mentioned earlier, black-to-white response times usually do not represent the most real world operations of LCDs. Part II of this LCD FAQ will deal most explicitly with response time issues, so we will not get too far into the subject here. As a simple word of advice, we encourage you to take a look at the LCD that you plan on buying in a store before you buy it online. Stay tuned for our Response Time follow up to this FAQ.
Other Image Problems
One of the other common types of interference on LCD screens has more to do with poor power supplies. Occasionally, an LCD will display an image, but seconds later, the image still persists. Below is an example:When the external brick overheats, we have noticed that its ability to produce clean signals degrades. Thus, the monitor does not properly modulate the signal. Our solution is to make sure your power supply is properly ventilated and not hot to the touch.
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Anonymous User - Sunday, September 7, 2003 - link
http://www.anandtech.com/showdoc.html?i=1730Its ok from what I hear.
Anonymous User - Saturday, September 6, 2003 - link
Great article - typical AnandTech coverage/information! I have a question though - I would like to get a 17" LCD with DVI and S-Video inputs (for playing console games). The Samsung MP series has VGA and S-Video, but no DVI. Albatron has a one with some nice specs - the L17AT.http://www.albatron.com.tw/english/ia/pro_view.asp...
The only problem is that I have seen no reviews of them. I am a little leery of spending $500+ on a monitor sight unseen. Any suggestions?
KristopherKubicki - Saturday, September 6, 2003 - link
#49, Ill add that into Part II then.#50, perhaps down the line I will try to do that. It would not really fit into part II right now.
Cheers,
Kristopher
artifex - Saturday, September 6, 2003 - link
Also, I'd really like to own an LCD because of the weight and size issues (I want larger than my current 16" viewable CRT, 17 or 19 maybe), but also because of the expected power savings. Would you consider adding a comparison of the power consumption in future roundups?artifex - Saturday, September 6, 2003 - link
I am disgusted to discover that many manufacturers using the 262000 color panels are lying and claiming 16.7 million. I challenge Anandtech to clearly identify these manufacturers in future product reviews, because if they can't tell the truth about this simple spec, how can we trust them on things like warranties?KristopherKubicki - Saturday, September 6, 2003 - link
#47 - Yes, SamsungUSA anyway. Computex is around the corner, maybe we can find out something new there =)Anonymous User - Friday, September 5, 2003 - link
Hi Kristopher, is Samsung still denying/not talking about their X line of 16ms panels?KristopherKubicki - Friday, September 5, 2003 - link
Hi Dan,The Apple 23" monitor is OK, but its more bark than bite (Apple does these amazing things with advertising). I would be very hesitant to judge a monitor by its contrast ratio.
In fact, one monitor we reviewed a few months ago, the Samsung 192T claimed a 500:1 contrast ratio when we recieved. Now, the specifications claim 750:1 even though nothing has changed on the monitor.
In any case, do remember that the Cinematic Displays are expensive as well. Samsung has done some very neat things in the 21 and 23" area, and in my opinion they are better than apples. To further sweeten the deal you wont need a seperate adaptor to convert the signal.
If you use graphics heavily (as in professionally) CRT is still your only option.
As for your question about DVI, there are actually about 3 versions of the technology. However, almost all hardware on the PC uses the DVI-I format. This format is backwards compatible with the other two, so you'll be just fine.
Cheers,
Kristopher
Anonymous User - Friday, September 5, 2003 - link
Hi my old 17" CRT is dying, and I'll need to replace it very soon. I have found that when working in PhotoShop, my old 17" monitor is just to small, and my eyes get quit sore. I think I would like to get and LCD of around 19". I am a PC user and am running Windows 98se.In my research "the Monitor to which all others is compaired" is the Apple 23" Cinem HD Display Having a resolution of 1920 by 1200, 170 viewing angle, brightness of only 200 cd/m2, lowsey 350:1 contrast ratio, and a half decient pixel pitch of 0.258.
Here in Australia coumptor stores aren't at all helpful in showing you their monitors in real world sisutions. So I've only been able to read the technical specs found on the internet. It seems a number of monitors have hit the 700 to 1 mark, and Planar offer a 19" with a pixel pitch of 0.242mm at 1600 x 1200 while most offer a auful 0.290mm at 1280 x 1024.
Going on specifications alone, I think I would like a 19" LCD with 1600 x 1200 resolution, 300 CD/m2 brightness, 700 to 1 contrast ratio, 25ms or less response time, 170 degree horizonal and vertical viewing angle, 0.242 mm pixel pitch, and of course a DVI coennection. I am not a gamer.
Is this reasonable and practical, or is a CRT a better option, and if so which one would best suit the graphics environment?
I recently read something about there being two kinds of DVI, DVI and DVI-D, is this a concern?
Thank You for any help you can give me, my e-mail address is danandrews@optusnet.com.au
Sincerely, Dan Andrews
Anonymous User - Friday, September 5, 2003 - link
What's the deal with all the misleading and irrelevant hypertext links in the article (e.g. "computer", "connection", "solution", etc?)