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TN? Non-TN? TFT? What's all this LCD tech mean?

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July 20, 2008 7:15:16 PM

I've seen people around here throw around a lot of LCD panel related acronyms which I have no idea what they mean, but a lot of people seem to dislike TN for some reason. Could someone fill me in on this? I'd like to know because I'm going to be looking for a nice 24", 1920x1200, low-response time capable monitor sometime in the next month or so and if knowing more of this stuff helps, then I'd like to know.

More about : tft lcd tech

a c 365 U Graphics card
July 20, 2008 8:10:37 PM

The following are two of my posts from the "Should I buy a 22" monitor or a 24" monitor?" thread that is in the Tom's Hardware Forums » Computer Peripherals » Flat Panels/ LCDs section:

http://www.tomshardware.com/forum/53818-3-should-monitor-monitor

jaguarskx said:
You need to do a lot of research to find out what type of panel an LCD monitor uses. In other words: GOOGLE. I probably spent in excess of 50 hours doing research over the course of 9 months before deciding on the 26" NEC monitor I bought last November.

TN Panel:

+ Inexpensive
+ Fast response time
+ Generally good enough for most people and gamers

- 6-bit panel tech *
- Poor color accuracy = bad for professional graphics
- More likely to have image artifacts in both pictures and video
- Poor viewing angles (anything less than 178/178 viewing angle is TN) - images washes out or turns negative.
- Poor black levels
- Seems to be more prone to backlight bleeding. (all LCD panels suffers some level of backlight bleeding)

S-PVA / P-MVA Panels:

+ 8-bit panel tech **
+ Great black levels
+ Good color accuracy - good enough for professional graphics (but IPS panel tech is even better; more expensive too)
+ Good viewing angle (178/178) - colors starts to wash out at more extreme angles than TN panels
+ Less prone to image artifacts in pictures and video


- More expensive
- Slower response time

==============================================

* 6-bit panel tech means 6-bits are used to represent each color (red, green, blue) in binary. That means "2 to the power of 6" = 2^6 = multiply the number by itself 6 times = 64.

There are 64 shades of each color (R, G, B); to determine the number of colors simply multiply the number of shades 64^3 = 64 x 64 x 64 = 262,144 colors. That works out to 256K colors (1k in "PC language" = 1,024; 262,144 / 1,024 = 256k).

There for a 6-bit panel can only produce 256k colors, not 16.7 million colors. Thru a process called dithering these 256k colors are basically blended together to estimate (guess-timating) the remaining 16.2 - 16.5 million colors. This is why a TN panel is:

1. Poor choice if you are a graphics professional.
2. Image artifacts in both pictures and video (especially HD video)
3. Poor black levels
4. Possible color banding - Shades of colors do not transition smoothly from dark to light. For example, black transitions to white from left to white on the screen. You should see black smoothly turning to dark gray, medium gray, light gray, then finally white. Color banding will mean you will see actual columns (bands) of colors shifting from darker to lighter colors.

Note: Sometimes manufacturers will actually list "8-bit" instead of "6-bit" because it "adds" an extra 2-bit for dithering purposes and is sometime referred to as Frame Rate Control (FRC). Not absolutely sure if FRC is related to dithering, but nevertheless it is still a "6-bit" panel for all intents and purposes. Manufactures are simply trying to confuse the consumer.


** 8-bit panels - 8-bits used for each color (R, G, B) that means 2^8 = 256 shades of each color. Multiply shades to get total number of colors = 256 x 256 x 256 = 256^3 = 16.7 million colors.

8-bit panels generally have slower response times than TN panels because they need time to actually "calc and display the other 16.5 million real colors" that a TN panel cannot display.

======================================================================



AND....


jaguarskx said:
TN panels are usually "rated" at a max of 170/170 viewing angle. But at that extreme angle there will be lots of color distortions.

S-PVA / P-MVA / IPS are "rate" at a max of 178/178 viewing angle. These panels also suffer from color distortions at extreme angles, but less so than TN.

There are TN panels that are rated at 5ms or slow. The general rule is if response time is faster than 5ms, then it is definitely a TN panel.

Without spending some indepth research, if a monitor is inexpensive compared to other monitors of the same size then it is a TN panel. The only tips are as follows:


1. If a 22" LCD monitor is not the Lenovo ThinkVision L220x (~ $400) or any one of 22" LCD monitors made by Eizo selling for over $600, then it is a TN panel.

2. In General, 24" monitors selling for less than $550 is built around a TN panel (unless it is on sale at an online store).

3. Only non-TN panel will provide 8-bit colors (aka 24-bit color) or 16.7 million real colors.

4. A non-TN panel will have viewing angles rated at 178/178.

5. TN panels can have viewing angles ranging from 130 to 170 degrees.

6. Non TN panels response times are no faster than 5ms and can be slower.

7. TN panels response times are as fast as 2ms, but can be slower.

====================================

There is no such thing as a LCD monitor with 180+ degree viewing angle unless the LCD monitor is curved. At 180 degrees you are looking at the side edge of your monitor. Over 180 degrees and you will be seeing the back of your monitor.


a c 365 U Graphics card
July 20, 2008 8:15:27 PM

To access all my posts about LCD monitor in general:

1. Click my SLAYER icon.
2. Scroll down a bit and click "Access to the whole list of his/her messages"
3. In the drop down list select "Computer Peripherals"
4. Click the "See Results" button.
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July 21, 2008 5:07:32 AM

Hmmm. So to a gamer, like me, it's kind've a choice between...

- less expensive
- faster response

or

- better colors
- wider viewing angle

Kind've a tough choice for me. I mean, I don't know really if I notice ghosting at all when I play games and if it'd really be a problem for me anyway. And I do like my image quality... damn, tough choices.

So would this be an example of a non-TN display?
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
a b U Graphics card
July 21, 2008 5:12:32 AM

Considering that the good non-TN panels are at 5 or 6 ms response time, you shouldn't notice any ghosting. Really, in my opinion, it's simply a matter of do you have the money for a non-TN display. If so, go for it every time. TN gives cheap large displays (like the $280 22" with webcam that I'm using right now), but the S-PVA or S-IPS is always worth it if you can spare the cash. The image quality difference is definitely noticeable.

For a 24, if you can blow $700 or so, the dell Ultrasharp 2408WFP is an absolutely STUNNING S-PVA display. The colors will blow your mind. Half life 2 is a brand new experience, Crysis is stunning, Bioshock amazing. You'll have to play through all your games again just to see them on that monitor.
July 21, 2008 5:14:19 AM

Well I figure that by the end of August I'll have a total of around $1200 to spend on upgrading my PC, a good chunk of which I was going to devote to a new monitor and a new video card.

Wow, that Dell Ultrasharp you mentioned look awesome and it's getting a lot of good reviews too. Still... $700 is a bit much... but it does support a LOT and I guess it could double as a TV... man, tough choice.

By the way, why are there USB ports and card readers on that Dell monitor? What's the point?
a b U Graphics card
July 21, 2008 5:37:27 AM

Mostly that it is really convenient. You can plug a USB drive straight into the side of your monitor, you can easily transfer pictures from your camera. Trust me, it's really convenient. It also has 2 USB ports on the back (it just acts like a USB hub for all of the ports), so you can easily plug a keyboard, mouse, joystick, etc straight into your monitor, rather than threading wires all around. It also has Dell's premium panel warranty - if even one bright pixel is found in the warranty period (standard 3 yr, extendable to 5 yr), they'll replace the entire panel for free. It's a really nice warranty.

Oh, and as for price, that Dell goes on sale all the time. You won't get it dirt cheap or anything, but with constant checking and a bit of patience, you can probably get it for $550-$600, instead of the $670 or so that it normally goes for. Heck, about a week ago it was on sale for $599 for a couple of days.
July 21, 2008 5:58:47 AM

Still, the monitor isn't connected to the motherboard, unless there's a USB cable that goes from the Mobo to the monitor, in which case I understand then.

Anyways, sounds pretty good. I think I'll keep an eye out for this one. Could serve as a nice monitor and TV replacement. And if it's as great as everyone claims it is, then I think I'll be seeing some damn nice colors when I play my Xbox 360, PC, PS2 and Wii games.
a b U Graphics card
July 21, 2008 6:17:48 AM

Yep - the monitor has a USB data cable to hook up to one of your computer's USB ports. Actually, most of the Dell flatscreens do now (except for the very smallest and cheapest ones). The USB cable is how the card reader and the 4 USB ports on the monitor work. Basically, it has an integrated USB hub.
July 21, 2008 1:45:53 PM

Has anyone tried hooking up video game consoles and other component/composite/HDMI related stuff to this monitor by the way? I'd like to know if it handles those kinds of inputs well and if it's easy to play off of stuff other than a PC and have 720/1080 resolution without needing to refer to a bulky instruction manual or a customer support site.
a c 365 U Graphics card
July 21, 2008 2:49:08 PM

mathiasschnell said:

So would this be an example of a non-TN display?
http://www.newegg.com/Product/Product.aspx?Item=N82E168...


Nope.

Price is too low for it to be anything but a TN panel, especially since it is NEC. It is not even on sale. Only Westinghouse and DoubleSight sells S-PVA panel LCD monitors for $500 or less when not on sale.

The telltale sign of it being a TN panel is the viewing angle which is less than 178/178.
July 21, 2008 3:02:16 PM

i have the next size down of that monitor the 21.5", and i used my PS2 in the composite and it looks just like it should, i also have my DVD player plugged in through the S-video port and that looks brilliant as well.

If you choose to plug in your 360 it will work fine, but you will only be able to set 720p and above on the HDMI.

i havnt seen the resolution on that monitor but i would guess 1680*1050?(correct me if im wrong please), if so then you wont get true 1080p cause the screen cant display a high enough resolution, its a small price to pay imo for the quality you get with this dell LCD though.
July 21, 2008 3:04:44 PM

jaguarskx said:
Nope.

Price is too low for it to be anything but a TN panel, especially since it is NEC. It is not even on sale. Only Westinghouse and DoubleSight sells S-PVA panel LCD monitors for $500 or less when not on sale.

The telltale sign of it being a TN panel is the viewing angle which is less than 178/178.


Um... the specs say the viewing angle is 178/178. Where do you see less than that?


Flakes said:
i have the next size down of that monitor the 21.5", and i used my PS2 in the composite and it looks just like it should, i also have my DVD player plugged in through the S-video port and that looks brilliant as well.

If you choose to plug in your 360 it will work fine, but you will only be able to set 720p and above on the HDMI.

i havnt seen the resolution on that monitor but i would guess 1680*1050?(correct me if im wrong please), if so then you wont get true 1080p cause the screen cant display a high enough resolution, its a small price to pay imo for the quality you get with this dell LCD though.


The monitor resolution is 1920 x 1200. So if that's the case then I guess it can run 1080p (assuming HDMI & Xbox 360 allow that). Thanks for telling me your experience.
a b U Graphics card
July 21, 2008 4:04:35 PM

Yep, it should be able to run full 1080P just fine (if you have the settings right to maintain the aspect ratio, it should have some small black bars at the top and bottom, but it will be true 1080p).

As for that NEC? Yes, it is specified as a 178/178, but if you read the reviews, the viewing angle really isn't as good as they claim. It certainly looks like it is a TN panel to me.
a c 365 U Graphics card
July 21, 2008 8:40:20 PM

mathiasschnell said:
Um... the specs say the viewing angle is 178/178. Where do you see less than that?



Sorry, must have been switching between looking at specs of various different monitors.

Anywaste, the NEC Display Solutions ASLCD24WMCX-BK is most certainly a TN panel. They probably claim that the monitor has 178/178 due to a special coating on the screen and only if you use a certain contrast ratio level. The coating will do nothing to improve color accuracy though.

Also, NEC is a premium brand so their monitors are generally more expensive than others. For example, S-PVA / P-MVA 24" starts at about $600, the NEC Display Solutions LCD2470WNX-BK uses a S-PVA panel and is priced around $760.

In addition, NEC is the only brand that produces a 24" LCD monitor that uses the highly coveted (by some people) S-IPS or H-IPS panel. The NEC 2490WUXi cost from $1,100 to $1,300.
July 21, 2008 8:49:50 PM

jaguarskx said:
In addition, NEC is the only brand that produces a 24" LCD monitor that uses the highly coveted (by some people) S-IPS or H-IPS panel. The NEC 2490WUXi cost from $1,100 to $1,300.


Yeah I saw that one. What's up with that LCD panel? Why is it so expensive?
a b U Graphics card
July 21, 2008 9:20:19 PM

S-IPS are the panels used in most 30's. They have slightly better color even than the S-PVA used in the better 24's, and somewhat better blacks, but cost quite a bit more. I don't think it would really be worth it in this case, though it might if you work with photos or videos for your job and need perfect colors. Realistically though, the S-PVA will be nearly as good as that for half the price. The difference between S-PVA and S-IPS is much smaller than the difference between either of them and TN.
a c 365 U Graphics card
July 22, 2008 12:36:35 AM

The NEC 2490WUXi also includes a lot of extra electronics "stuff" like a color look up table (LUT) which allows the monitor to choose from over 69 billion (umm... that is not a typo) colors, but the monitor still only displays 16.7m colors at one time.

It also includes an A-TW polarizer filter which basically decreases the white glare that the backlighting produces.

Auto adjusting backlighting to try to maintain consistent brightness as lighting in room changes. For example, daylight shining through a window in the room.

ColorComp is a technology that reduces uniformity imperfections by compensating for differences in color and luminance across the screen area.

There are other things too.

Basically, any NEC monitor that has the WUXi extension are geared towards graphics professional or the "pro-consumer" like myself who wants the best image quality possible within a reasonable price range.
July 22, 2008 12:47:24 AM

Yeeeeaaahhh... I think I'll just go with the 24" Dell Ultrasharp with all the bells & whistles.
a c 365 U Graphics card
July 22, 2008 12:51:38 AM

mathiasschnell said:
Yeeeeaaahhh... I think I'll just go with the 24" Dell Ultrasharp with all the bells & whistles.


Yeah, generally the better choice for the average consumer.
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