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Originally Posted by RBG
Projector bulbs are like CRTs with long afterglows. Watch an incandescent light as it turns off to see that effect as the filament energy drains to zero. That is why you can't see the strobing 60 cycle current. Then watch a set of bright LED Christmas lights and many people, including me, can see a slight, annoying, flicker.
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I'm going to suggest to you that these annoying Christmas lights are made to flicker. Because I don't really think driving an LED without flicker is a difficult task to accomplish. I don't have a lot of experience with Christmas lights though, I'll admit.
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That's because the light does not decay into subsequent cycles. It goes to "off" as the polarity changes. The florescent light from an LCD screen is similar and thus must be increased in frequency to avoid the perceived power-cycle flicker. I believe the backlight runs about 100 cycles / second for that purpose.
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I think it's much higher than that on a CCFL. Do you think you can detect this flicker? It has absolutely nothing to do with the refresh rate or the frame rate anyway...
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Of course, when you are looking at any part of an LCD image that is white (to highlight the most obvious color), you are basically looking directly at the florescent light. It would drive you nuts if it was running at 24 cycles per second, in synch with the frame rate.
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If the frequency of the backlight was 24 Hz, yes, that would probably drive you nuts. But to do that something would have to be broken, and that's not the refresh rate anyway. The refresh rate could be 24 Hz, and it would look splendid with 24 FPS material.
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So LCD technology as they are generally built presently, still have to deal with refresh rates, only in a different way from CRTs & film projection.
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Well, for the backlight, they have to deal with the nature of AC the same way every fluorescent light you come across does. And they do this independent of the refresh rate.
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Here is a link to an article that actually refers to the LCD pixel panels themselves exhibiting flicker: "LCD Screens Don't Flicker, Or Do They?" Last para: "Contrary to popular belief, LCD panels do exhibit flicker."
http://tinyurl.com/44qy6n
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Your ability to find that one sentence and ignore everything else is unique. You really only had to go one sentence further: "Simple potentiometer adjustments can be made to minimize the effect since LCD flicker arises from an offset of the common voltage,
not a refresh signal. "
So unfortunately, refreshing an LCD at 120 HZ or even 1200 Hz isn't going to help with the form of flicker being discussed in that article. But fortunately, you can't see it anyway.
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I suppose if you remove all the technical artifacting from projection, televisions, interlaced monitors, progressive monitors and LCDs, yeah, you probably would get an acceptable image at a true 24 progressive frames per second.
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I know you can get an acceptable image at 24 Hz with nothing more exotic than the technology that was common several years ago, because I've seen it. And it's better than any 60 Hz TV I've ever seen, because it doesn't have that lopsided judder. But go to an electronics store and look for yourself.
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But even then, you'd have to deal with the choppiness inherent in most computer rendered video: a visible gap that can be seen between the moving object and its afterimage in the eye.
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Well, yeah, 24 FPS is choppy... even if you refresh it at 120 Hz on an LCD. In fact, I would say it is precisely as choppy at 120 Hz as 24 Hz. There is no, none, nada, zero difference.