New M6500 Discussion Thread

It could be a limitation of their PWM circuitry. Either way, that'd be up to the panel manufacturer.

 

True, this is why I really would like to know if the Samsungs (or other LGs) show a similar effect. To my eyes it's so obvious when the brightness is turned down to 120cd/m² that I can hardly believe people can't see it if the screen produces this effect.

Don't get me wrong, the screen as such is great and I think I could live with the RGB trail, but if there is any solution to get rid of it, it really would be a relief for my eyes.

 

That, I'm afraid, I can't help you with at all (especially since I'm in the "enemy" camp. >.>). I know long ago Bokeh compared the 2 screens, but I don't recall him mentioning any trails of the sort you see.

 

Yes....Bokeh was at my house when he compared the two screens....this is first I've heard of "trails".

 

No problem, and thanks for your help so far!

I googled a little and this is a common issue with LED backlights (from Wikipedia):

"LED backlights are often dimmed by applying pulse-width modulation to the supply current, switching the backlight off and on again like a fast strobe light. If the frequency of the pulse-width modulation is too low and or the user is very sensitive to flicker, this may cause discomfort and eye-strain, similar to the flicker of CRT displays[5]. This can be tested by a user simply by waving a hand or object in front of the screen. If the object appears to have sharply-defined edges as it moves, the backlight is strobing on and off at a fairly low frequency. If the object appears blurry, the display either has a continuously-illuminated backlight or it is operating at a frequency that is too high for the brain to perceive. The flicker can be reduced or eliminated by setting the display to full brightness, though this has a negative impact on image quality and battery life due to increased power consumption."

It seems that in a good design, the frequency is high enough to make this a non-issue. Actually, I haven't had any problems with screen fllcker, be it from CRTs (85Hz refresh) or CCFL LCDs since the 80s! So I don't think I am particularly sensitive.

If I lock my eyes to a particular point on the screen I can't see any flicker at all. As soon as I move my eyes around on a screen area with a dark background, any bright objects leave a strobed red green blue trail on the dark background. Even the grey of the following web site in combination with the bright vertical scroll bar to the right is enough to produce a strong effect on my screen (at 26% brightness):

Digital Cameras: Digital Photography Review, News, Reviews, Forums, FAQ

Maybe different batches of the screen have been produced with different backlight PWM frequencies??? Could this be Bokeh's "secret" behind the preference of the Samsung?

 

The new controlpoint software can change the refresh rate on the panel from 60 to 40hz to save power in certain power plans. I really don't like the 40hz setting. I doubt that this is what you are seeing, but I thought I would take a shot in the dark.

I prefer the Samsung because it is capable of producing more saturated colors than the LG. The LG is probably closer to neutral without any calibration. With calibration both are close to each other. The Samsung might have an edge in the reds, can't remember. I just happen to like the panel that can "be dialed up to 11".

 

Good point regarding 40Hz, hadn't thought of it. I checked and am pretty sure that my panel currently runs at the standard 60Hz.

I estimate that my backlighting runs at a frequency somewhere between 100Hz to 200Hz, high enough to eliminate "classic" flicker on bright areas but far too low to eliminate the strobing RGB trail on dark areas as soon as the eyes start to move. Maybe there are different versions of the screen with different frequencies around.

 

OK, silly question I know, but does anybody know a good source for the point stick caps on the M6500? I'm amazed at how fast mine has worn down (softer rubber?) and I need a replacement. I suppose I could order a few and take my chances...

Anybody know what model here would fit: Finger Mouse Dell | TrackStick Cap | Track Stick Cap | Dell Latitude Rubber Point Stick Pad & Cover :: SofPoint

Maybe this one: SKU: DL1100.42425 (27)?

Thanks,

Keith

 

Cheaper and faster if you get them from eBay. Search "dell trackpoint cap" (blue) and "thinkpad trackpoint cap" (red).

 

Well I don't think that would have worked. I finally conceded that I was going to have to pull the trackpoint cap off to look at the inside, and the M6500 uses the round post instead of the square or "double square" post of most Dells. Answered my own question I guess.

Keith