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laptop - external lcd problem dear_tony 07-20-2006
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Posted by dear_tony on July 20, 2006, 2:39 pm
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 Hello,

When I connect external LCD (19", 1280x1024@60Hz) monitor to the laptop
via VGA port the image is fuzzy (very similar to the image which you
get when you are not using native resolution).

When I connect the same LCD monitor to the desktop computer through VGA
port (not DVI) image is sharp.

The laptop is Toshiba with NVIDIA 6600 graphic card, OS: Windows XP
SP2.
(Also, I tested one old HP laptop with ATI Radeon graphic card with the
same result.)

I adjusted the resolution to the external LCD native resolution
(1280x1024).

(The graphic card driver has feature to set one resolution for laptop's
lcd (1440x900) and another resolution for external monitor
(1280x1024).)

Any help would be appreciated.


Posted by Barry Watzman on July 20, 2006, 6:31 pm
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 I'm not sure that the external display resolution is applied unless the
internal display is turned off completely. Many video cards are
incapable of two different resolutions for the internal and external
display. So if both displays are operating, the external display is
scaled, which will produce fuzziness.

From your description, it sounds like the display is being scaled.
Many monitors can display onscreen the characteristics (resolution and
frequency) of the incomming signal. Does yours do this (it's often in a
menu somewhere), and if so, what is it?

Also turn "ClearType" ***OFF***, it makes things UN-clear, worse not
better. (Display properties, appearance tab, effects).


dear_tony@net.hr wrote:

> Hello,
>
> When I connect external LCD (19", 1280x1024@60Hz) monitor to the laptop
> via VGA port the image is fuzzy (very similar to the image which you
> get when you are not using native resolution).
>
> When I connect the same LCD monitor to the desktop computer through VGA
> port (not DVI) image is sharp.
>
> The laptop is Toshiba with NVIDIA 6600 graphic card, OS: Windows XP
> SP2.
> (Also, I tested one old HP laptop with ATI Radeon graphic card with the
> same result.)
>
> I adjusted the resolution to the external LCD native resolution
> (1280x1024).
>
> (The graphic card driver has feature to set one resolution for laptop's
> lcd (1440x900) and another resolution for external monitor
> (1280x1024).)
>
> Any help would be appreciated.
>

Posted by M.I.5¾ on July 21, 2006, 2:52 am
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> I'm not sure that the external display resolution is applied unless the
> internal display is turned off completely. Many video cards are incapable
> of two different resolutions for the internal and external display. So if
> both displays are operating, the external display is scaled, which will
> produce fuzziness.
>
> From your description, it sounds like the display is being scaled. Many
> monitors can display onscreen the characteristics (resolution and
> frequency) of the incomming signal. Does yours do this (it's often in a
> menu somewhere), and if so, what is it?
>

Assuming that you have the resolution and refresh exactly matching the
monotor, there is another possibility. Try forcing the monitor to
auto-detect the signal parameters. If the image is still fuzzy, look for a
setting on the monitor called 'clock', 'phase' or even 'clock phase' or some
similar description. Adjusting this may solve your problem.

For the curious: This adjustment causes the pixels in the video signal to
land exactly on the pixels on the display. Adjusting this (these) settings
moves the video pixels so that they land partly on one and partly on an
adjacent screen pixel. This makes the image fuzzy.

> dear_tony@net.hr wrote:
>
>> Hello,
>>
>> When I connect external LCD (19", 1280x1024@60Hz) monitor to the laptop
>> via VGA port the image is fuzzy (very similar to the image which you
>> get when you are not using native resolution).
>>
>> When I connect the same LCD monitor to the desktop computer through VGA
>> port (not DVI) image is sharp.
>>
>> The laptop is Toshiba with NVIDIA 6600 graphic card, OS: Windows XP
>> SP2.
>> (Also, I tested one old HP laptop with ATI Radeon graphic card with the
>> same result.)
>>
>> I adjusted the resolution to the external LCD native resolution
>> (1280x1024).
>>
>> (The graphic card driver has feature to set one resolution for laptop's
>> lcd (1440x900) and another resolution for external monitor
>> (1280x1024).)
>>
>> Any help would be appreciated.
>>



Posted by dear_tony on July 21, 2006, 4:56 am
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M=2EI.5=BE wrote:
> Assuming that you have the resolution and refresh exactly matching the
> monotor, there is another possibility.

Monitor's OSD menu claims that I am running optimal (native)
resolution: 1280x1024@60Hz.

> Try forcing the monitor to
> auto-detect the signal parameters. If the image is still fuzzy, look for=
a
> setting on the monitor called 'clock', 'phase' or even 'clock phase' or s=
ome
> similar description. Adjusting this may solve your problem.

I found Phase / Clock options but I could only get even worse results.

Using default parametars for Phase / Clock image is fuzzy but stable,
it doesn't flicker. I was adjusting Phase and Clock options and I did
managed to get sharp image but at the same time the screen started to
flicker as described in:
http://www.techmind.org/lcd/phasexplan.html .

So I guess that default Phase/Clock values are correct. :(

Thank you for your help, I am still searching for solution ...


Posted by Barry Watzman on July 21, 2006, 3:18 pm
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To properly adjust the dot clock frequency and phase of an analog LCD
monitor, download this test program:

www.winsite.com/bin/Info?500000030936

or (same site)

http://ns.winsite.net/bin/Info?500000030936

This program is variously known as CRTAT, CRTAT2, and CRT Align
(crtalign), and was written by Stephen Jenkins in about 1992 or 1993.
This is a very old Windows 3.1 program written in visual basic. It runs
under XP just fine, absolutely perfectly in fact, even with today's high
resolution monitors (you do need VBRUN300.DLL (the Visual basic version
3 runtime DLL library), which it may or may not come with the program
depending on where you download it from, but if you don't have
VBRUN300.DLL, it can be easily found on the web).

This program is totally non-invasive, it's "installation" makes NO
changes to your registry or to ANY system components or files. In fact,
if you just unzip the program and double click the exe file, it will run
fine without actual "installation" (but the program and the help file
need to be in the same directory, and VBRUN300.DLL needs to be available
in \Windows\System).

To use the program for this purpose, after installation, select the
leftmost of the 3 functions in the "Test" group (or "resolution" in the
drop-down menu) and then check both "mode" check-boxes.

When you display this pattern, you should see an absolutely perfect and
uniform field of alternating (but very, very fine) black and white
vertical bars each only one single pixel wide. If you see "moire"
distortion, or smearing, your display isn't adjusted correctly. Digital
monitors (with DVI interfaces) will always be "perfect". Analog
monitors will usually show an initial moire distortion pattern until
they are adjusted (dot clock frequency and phase). In most cases,
perfect adjustment can be achieved (and is "remembered" by the display),
but in some cases you can't achieve this. Note that the "auto"
(auto-adjust) function on almost all analog LCD monitors gets "close"
but usually does not get to the best possible adjustment.

[On many monitors, the dot clock frequency is called Horizontal size or
width. Phase is usually called Phase]

If you have an analog monitor and you don't use this program to adjust
your monitor, you are doing yourself a real disservice.

Two other comments:

First, you MUST run the video card only a the native pixel resolution of
the LCD panel. NO EXCEPTIONS OF ANY KIND ON THIS POINT, PERIOD.

Second, poor quality video cables are a huge issue with analog LCD
monitors. The cable issue is self explanatory, but MOST of the analog
cables offered for sale are "poor quality". You can almost tell the
quality by the thickness of the cable. You want something significantly
larger than a number 2 pencil .... maybe even approaching the size of a
garden hose (there are 5 individual coax cables inside a good analog
video cable, and the larger their individual diameters, the lower their
loss and capacitance). Unfortunately, really good video cables are both
hard to find and expensive.

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