LCDs. Resolution and refresh rates, myths and facts?

LCDs. Resolution and refresh rates, myths and facts?

Post by ozg.. » Wed, 01 Jun 2005 13:55:52



Hi all -

I switched from CRTs to LCDs some time back, but I'm still confused
about LCDs and their refresh rates. There are contradictory posts and
webpages on the issue, so I thought I could post to this newsgroup.

Quote:>From my old CRT days, I know that the higher the refresh rates (75 Hz),

the better. Unfortunately, my Envision LCD flickers (goes black
occasionally) when I set my XF86Config for high horiz sync/vertical
refresh rates. On its right hand side, my SyncMaster does just fine
with 80kHz Horiz Sync / 75 Hz Vertical Refresh rates. CRT intuition
tells me that this is good. However, the manual states, "Recommended
Rate for vertical frequency: 60 Hz, an inapp. vertical frequency may
hurt your eyes."

Also, the technical chart says, "Horizontal frequency: Analog: 30 - 81
KHz, Digital: 30 - 63 KHz." So the digital frequency range is smaller
than the analog one. Why is that? And should I be [trying to] run my
LCDs with higher rates, or should I just stick to lower values? Does it
even make a difference?

thanks,

Ozgun.

 
 
 

LCDs. Resolution and refresh rates, myths and facts?

Post by Jacob Larse » Wed, 01 Jun 2005 17:16:43


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> Also, the technical chart says, "Horizontal frequency: Analog: 30 - 81
> KHz, Digital: 30 - 63 KHz." So the digital frequency range is smaller
> than the analog one. Why is that? And should I be [trying to] run my
> LCDs with higher rates, or should I just stick to lower values? Does it
> even make a difference?

On an LCD, it does not do much to raise the refresh rate. It does not
flicker like a CRT, so the only reason you should use a higher refresh
is if you have some fast animations like those in games. Additionally,
you will not get anything from going beyond 60Hz unless your screen can
go lower than 16ms (which is equivalent to 62.5Hz).

/Jacob
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LCDs. Resolution and refresh rates, myths and facts?

Post by Michael Heimin » Wed, 01 Jun 2005 18:20:40



Quote:> Hi all -
> I switched from CRTs to LCDs some time back, but I'm still confused
> about LCDs and their refresh rates. There are contradictory posts and
> webpages on the issue, so I thought I could post to this newsgroup.

In short, LCD have zero refresh, there's no technical reason to
do so, the way the picture is generated is different from a CRT.
You should be fine with setting refresh to 60Hz.

[..]

--
Michael Heiming (X-PGP-Sig > GPG-Key ID: EDD27B94)

#bofh excuse 422: Someone else stole your IP address, call
the Internet detectives!

 
 
 

LCDs. Resolution and refresh rates, myths and facts?

Post by Peter Christ » Wed, 01 Jun 2005 19:24:28



> On an LCD, it does not do much to raise the refresh rate. It does not
> flicker like a CRT, so the only reason you should use a higher refresh
> is if you have some fast animations like those in games. Additionally,
> you will not get anything from going beyond 60Hz unless your screen can
> go lower than 16ms (which is equivalent to 62.5Hz).

Actually, if you live in Europe (or any other 50 Hz country) there is a good
reason for using an alternative refresh rate, if the LCD monitor will allow
it. If you are viewing video, the refresh rate in Europe, Australasia, and
some other areas is 50 Hz, which can cause an objectionable strobing effect
with a 60 Hz refresh monitor. It causes a 10 Hz flicker, which although slight
on an LCD display, certainly gives me a headache after watching it for any
length of time! My own LCD allows a 75 Hz refresh, which virtually eliminates
the flicker on 50 Hz (25fps) video.

Some LCDs don't allow this, and stick at 60 Hz (my laptop does for example). In
this case, you just have to grin and buy the asprin.....!

--
Pete

(make the obvious amendments to reply!)

 
 
 

LCDs. Resolution and refresh rates, myths and facts?

Post by ozg.. » Mon, 06 Jun 2005 04:58:33


Thanks. All of this was very informative.