10ms = 100hz?

[jojofish]

Does a flat panel pixel response time of 10ms equate to the refresh rate of 100hz that is used to describe television CRTs. Or am I completely on the wrong track?

 

[p05esto]

I'm no expert but I think that is off track.

LCDs don't "refresh" so there's no similarity there. On a LCD a pixel (little light) just stays lit until it needs to change to another color. The time it takes to change colors or fade from black to white is the response time. Think of when you turn a light bulb off - you can almost see the element in the bulb dim out as the light goes off.

When it takes too long for the pixel to change color you get that ghosting effect as the light fades out to another color (trails man). A CRT keeps scanning or refreshing very quickly using a light beam so it's very quick (light speed) and there's no ghosting - just that annoying superfast flashing type effect that tires out your eyes.


<A HREF="http://www.proactivedesign.net/eric" target="_new">More than you want to know about me . . .</A>

 

[jojofish]

Thanks for that reply, it clears the technical issue, but I guess that I also had another aspect of the question in mind.

When LCDs achieve a pixel response time of 10ms (apparently close) will they achieve close to the perceived picture quality (i.e. crisp, no ghosting) of a 100hz CRT or will the fact that there is any detectable 'response' time mean that they will never equal CRTs in this respect?

 

[p05esto]

Again, I'm no expert but 100MHZ is very fast for a CRT. And NO I don't think that's equal to 10ms response time on a LCD. At 12ms there's still reported very slight ghosting (although acceptable) on a LCD so I'd guess 10ms is not that much faster and certainly not as good as 100MHZ CRT. A 75MHZ monitor will really not show any flicker or ghosting type efects.

The other thing to keep in mind is that like Toms mentioned you can't go just on response time as manufactures can stretch the truth and different types of panels look better than others at the same speed. I wouldn't even consider a LCD until you find a good review of it on Tom's as well as a couple other reputable review sites. My opinion anyway.

I'm not even sure you can say that a certain response time is equal to a CRT at (X)MHZ becaseu they are completely different animals. Maybe someone who knows can answer this specific point if there's any leveling point between the two.

<A HREF="http://www.proactivedesign.net/eric" target="_new">More than you want to know about me . . .</A>

 

[peacescience]

OK i´m not an expert but i´m gonna disagree, if anyone can proof my statement to be not valid at least we all will know more about this 10ms matter. Here we go:

1 second = 1000 miliseconds(ms)
therefore
a task that take 10 milisecond to complete should be able to be acomplished 100 times per second (1sec=1000ms, 1000ms: 10ms= 100times per second)

On the other side a 100 Hz crt measure points out that the screen is capable of refreshing its content 100 times per second.

CONCLUSION:
As long as i know the different natures of CRT and LCD technologies are irrelevant when comparing an uniform or common spec like the IMAGES PER SECOND. At this point the existence of two methods to get those images delivered (screen refresh for CRT and pixels response time for LCD) are superfluous because you are unsing only one measuring method TASKS PER SECOND.



PEACE&SCIENCE

 

[Aciv]

From what I understand, if an LCD had a true 10ms response time, then yes, it would roughly correlate to a 100 Hz refresh rate on a CRT. Unfortunately, due to the nature of current LCDs, it takes a different amount of time to transition from white to black than from one color to another. Typically, manufacturers tell you the best time that a pixel would change rather than the peak time, which would be more representative of the overall speed of the monitor.

With that said, most people need to really look for "ghosting" in order to actually see it on most quality 16ms or better LCDs. This "ghosting" looks similar to "tearing" on CRTs without V-sync. As always, it's usually better to see it for yourself on a friend's screen or at a decent store rather than depend on others' subjective views.

 

[peacescience]

That´s totally exact. The problem is that a 100hz crt always has a refresh rate of 100 images per second meanwhile an lcd response time is color depending PIXEL PER PIXEL.

- and that manufacturers use a mixture of several RESPONSE TIME CONCEPS - (more info on Tomshardware guide on the matter of LCD - response times)

so 10ms may be not comparable to another model with 16ms.

PEACE&SCIENCE

 

[flamethrower205]

You make it seem slightly convoluted. For clarity's sake, both go PIXEL BY PIXEL, but on a CRT this is done sequencially with beams for r, g, and b. So the beam is moving real fast and in say 1600x1200 pixels, that's 10ms/(1600x1200). An LCD has individual transistors controlling the pixels (acutally 3 subpixels) which can shift simultaneously more or less. Don't confuse this with what u said in that it seems as if it's 10ms for each pixel and in fact 1280x1024x10 ms (that'd be hella slow).

I totally agree with what has been said in that a CRT <i>will</i> redraw the image 100 times a second and that's the end of that. The LCD, however, applies differing voltages to the crystals to get them to shift a certain amount. Max voltage is going to black from white and vice versa. This voltage is lessened for grey values (when I say grey values btw I mean intermediary colors as well cause each pixel is nothing more than a combination of 3 monochromatic subpixels, each of which for simplicity's sake can be viewed on a white to black scale). Hence, we get a higher response time, and suddenly this 10ms brilliancy is no longer the case.

Also, p05esto, it's Hz, not MHz cause that'd imply 1,000,000x100 times a second.

Conclusion: Go with yer CRT if you need precision and wish to use it for gaming and photo work. Use an LCD for programming and nonheavy multimedia tasks.

SEX is like math. Add the bed, subtract the clothes, divide the legs, and hope you dont multiply

 

[peacescience]

WHAT I SAID:
-lcd response time is |---color---| depending PIXEL PER PIXEL.- (response time varies on each PIXEL [read cluster or every 3 subpixels] depending on which color it needs to produce)

WHAT U SAID:
-The LCD, however, applies differing voltages to the crystals to get them to shift a certain amount. Max voltage is going to black from white and vice versa. This voltage is lessened for grey values (when I say grey values btw I mean intermediary colors as well cause each pixel is nothing more than a combination of 3 monochromatic subpixels, each of which for simplicity's sake can be viewed on a white to black scale). Hence, we get a higher response time, and suddenly this 10ms brilliancy is no longer the case.

CONCLUSION:
You clarify with a long and really nice explanation wich a canned in a few words.


PEACE&SCIENCE

 

[flamethrower205]

If people know a little more it won't hurt, and it'll possiblt clear up some confusion regarding terminology and ambiguous statements. No need to get defensive (despite the irony of this statement :tongue: ).

SEX is like math. Add the bed, subtract the clothes, divide the legs, and hope you dont multiply<P ID="edit"><FONT SIZE=-1><EM>Edited by flamethrower205 on 04/28/04 00:01 AM.</EM></FONT></P>