Archived from groups: alt.comp.periphs.videocards.nvidia (
More info?)
I voluntary to try
You need to know 3 things to understand!
1. How your eye(s) and brain work (partly)
2. How CRT work (partly)
3. How LCD work (partly)
4. How we define the term "Digital" and "Analogue" (partly)
1. When our eye receive a signal, our brain will store it for something
like 1/30 ( I don't know the exact figure) of a second. So, if you switch a
light on and off faster than 30 times per second, your brain will fool you
that the light is continuous. If you do it slower, you will not just see the
light on and off, but you are going to get a headache very soon as well.
Somehow this "headache" business remain until we see the light switching on
and off faster than 70 times per second.
2.The CRT is an analogue device, it work like the electron gun send a beam
of electrons to the phosphorus coated screen, when the phosphorus hit by
electrons, it glow and more(stronger) it glow brighter, no electron? No
glow! Therefore, the electron gun was quite busy to "sweep" through the
whole screen to generate a picture AND re-hit the same phosphorus to keep
them glow to maintain the picture. The rate it "sweep" through the whole
screen is call the refresh rate. As in 1, it require the refresh to be 30Hz
to fool our brain it's not glowing on and off but at this rate, it give us
headache. Increase the rate to 70Hz or high, it made us more conformable to
"see" a "illusion" of a picture!
3.LCD display is digital device. The colour LCD itself do not glow, it
require a backlight (fluorescent lamp) to be seen. When LCD is "off", it is
transparent, when you pass it with electricity aka "on", it change colour.
Each LCD in the display has its own circuit to control the on/off. That's
how LCD work. If you keep the backlight continue on, you just switch
different LCD to "on" to maintain the picture, no "refresh" require.
4. Any thing can be represent in 1 & 0 only can be translate to "ON" & "OFF"
and vice versa are define as "digital". Everything else are "Analogue".
Now the video card is working in a digital domain, simply send the digital
signal through the DVI interface to control each LCD's on/off to create a
"picture". It (almost) has nothing to do with refresh rate!
But the CRT is different, the video card have convert digital signal (on &
off) to analogue signal (VGA) to control the amount (how many/intensity) and
the duration (how long) of electrons hitting the phosphorus and "refresh"
everything for 70 times or more per second to generate a stable "illusion"
of a picture.
The availability of the refresh depend on 2 things, the D/A (digital to
analogue)converter on the video card and how good is the electron gun inside
the CRT.
I really don't know what the refresh rate setting in LCD for @@"
But I knew one thing, to display a series of different pictures to generate
a motion picture/animation, the refresh come in matter, the maximum frame
rate (frame per second/fps) can be display is same as the refresh rate
setting of your system and the higher the frame rate the smoother the
motion.
HTH
"Stephen SM WONG" <nospam@nospam.com>
???????
ine.LNX.4.58.0412310157310.6578@sha.wongstephen.com...
> Oh, thank you for all those who had replied in this
> newsgroup. I do find 60Hz refresh rate satisfactory on LCD,
> just curious to know how come the VGA signal and DVI signal
> will have different refresh rate limits.
>
> Wish you all a Happy New Year!
>
> Stephen SM Wong @ Hong Kong.
>
> On Thu, 30 Dec 2004, Jim wrote:
>
>> Refresh rates on LCDs are almost all 60Hz. Its not like a CRT where a
>> refresh of 60Hz will give you a headache. You should leave it at its
>> native
>> res and refresh or you will adversely affect picture quality. I would
>> guess
>> its not acutally doing above 60Hz its just telling you thats what the
>> video
>> card is sending and then converting it back down to 60Hz internally. By
>> the
>> way use DVI-D if you can it gives alot sharper picure over all.
>>
>>
>> "Stephen SM WONG" <nospam@nospam.com> wrote in message
>> news
ine.LNX.4.58.0412301757050.26556@sha.wongstephen.com...
>> > I've a FX5600 card and a Viewsonic VG712s LCD. The
>> > connection is thru DVI-D. And running Win2K and latest
>> > official Nvidia driver. I've only able to run at 60Hz
>> > refresh rate, is it normal?
>> >
>> > If I change the connection to VGA (thru the Dsub-15
>> > connector), I can run the refresh rate up to say 100Hz.
>> >
>> > In all case, the resolution is 1280x1024 (the native
>> > resolution of the LCD).
>> >
>> > Can anyone enlighten me, which is the limiting factor in the
>> > above setup? The FX5600 card? The TMDS encoder on the
>> > card? The LCD? The driver?
>> >
>> > Just want to know the "behind reason".
>> >
>> > Stephen SM Wong @ Hong Kong.
>>
>>
>>
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