Panasonic 2500 Hz Focused Field Drive in Plasma — A Similar Goal

Speaking of impulse-driven technologies, Panasonic Germany has several very interesting videos of various technologies of their high-end plasma (2500 Hz focussed field drive – FFD) and LCD displays (1600 Hz scanning backlight) – multiples of the European refresh rate of 50 Hz.  Although the Hz should be taken with a grain of salt, as actual measured motion blur reduction can fall short of the claims, the theory and science is still very real — compressing the impulses into a short time period.  It is very nicely explained in German by this Panasonic employee:

Some plasma displays such as Panasonic VT50 uses this. This plasma display focusses the subfield refreshes into a single 0.4 millisecond time period  (1/2500th of a second) — a very similiarly short time duration that the BlurBusters experimental ultrahigh-performing scanning backlight, is also targetting.

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7 comments on “Panasonic 2500 Hz Focused Field Drive in Plasma — A Similar Goal

  1. scanmaster says:

    One interesting observation I make about the Panasonic 1600Hz scanning backlight video:

    See 0:10 through 0:15 — the diagram suggests that several segments are illuminated at once, while only a few are turned off. My question to Panasonic — are the backlight segments illuminated for 1/1600th of a second? If not, these may not provide sufficient motion blur reduction benefit. In addition, this may not factor in backlight diffusion between adjacent segments, so the actual measured improvement may closer to an “800” rating (perceived motion blur equivalence to 800fps@800Hz) or even less.

  2. scanmaster says:

    A poster on AVSFORUM suggests that phoshpor decay is be a limiting factor for this plasma display — closer to 5 milliseconds for red phosphor. Clearly, it is important to take Hz ratings with a grain of salt, as actual measured motion clarity is often far less than manufacturer claims. However, the technologies are still very interesting, as we attempt to get to the ideal “CRT-sharp motion” in a flat panel display.

    It will be interesting to see what the phosphor decay limitations of white LED’s are; and how they compare to the phosphor decay of CRT’s. In time, I will do oscillscope+photodiode measurements, to generate a phosphor decay graph comparison between white LED’s, plasma display phosphors, and CRT phosphors.

  3. damag0r says:

    So, I got a Panasonic UT50… and this technology is very real. If I had to guess it’s reducing the blur by 80-85% or so… which is far better than what the Sony or Samsung LCDs are achieving.

    Sometimes it seems to totally eliminate the blur, other times where I would have seen 2-5 “blur ghosts” as I call them I only see 1. Then in many cases the blur is compressed into a much smaller area making it much less noticeable. Only in rare cases is it as bad as I was noticing on modern LCD displays.

    After buying and returning many LCDs and still noticing it on a DLP projector (but not quite as bad). I’m definitely keeping this Panasonic 50UT50…

    Only problem is the factory white balance settings on it are awful, but after fixing them in the service menu they look better than the Sony LCDs I tried did out of the box. Still annoying I had to spend so much time and had to go into the service menu to achieve this though. If Sony has anything going for them it is that their sets require only very simple normal menu tweaks to get them looking good color wise out of the box. Too bad the motion blur on them is as horrible as anything else… and at least with their XR 240 sets I wasn’t noticing an appreciable improvement as far as motion blur goes. Maybe the 960 ones are better, but those come in a minimum of 55″ size if I recall right and I doubt it is as good as the Panasonic plasma 2500 FFD.

  4. scanmaster says:

    I just went into a store and saw one of these Pansonic 2500FFD displays.

    Your assessment of 80-85% blur reduction is a relatively accurate guess (relative to a typical 60Hz LCD). I’d daresay a bit closer to 65-70% approximately relative to a very good 2ms LCD (running at 60hz but with interpolation turned off).

    I did an assessment of motion blur by watching a 600-pixel-per-second ticker scrolling occuring along the bottom edge of the screen (Taking 3 seconds to pan a 1920 pixel width screen). That’s 1.6ms per pixel of movement. There was 3 pixels of yellow-ghosting trailing (the RG phosphor decay artifact) behind movement occuring at 600 pixels per second. Here, 1.6ms times 3 equals 5ms — a common phosphor decay for RG phosphor in plasma.

    This would lead to an motion equivalence factor of 200; not quite to the claim of the “2500Hz” equivalence, due to the phosphor bottleneck. (formula = 1000ms/5ms = measured motion equivalence factor of 200). 200 is only 70% less motion blur than a “scientifically perfect 60Hz” sample-and-hold display.

    From my tests, I easily expect to have far less motion blur on LCD than even Panasonic 2500 FFD plasma, when using 150watt/sqft of backlight at 0.5ms strobed impulses per refresh on a 3D-capabel 120Hz LCD that already clears the vast majority of its pixel persistence well within its refresh (allowing me to completely bypass pixel persistence as the motion blur barrier).

    That said, the Panasonic 2500 FFD had the best motion I’ve ever seen in any plasma flat panel.

  5. scanmaster says:

    I did some recent tests. I also went into Future Shop. New LightBoost computer monitors have less motion blur. So the good news is that modern LightBoost displays with a motion synchronized strobe backlight (see for more info) successfully pull off the feat of bypassing LCD pixel persistence.

    baseline — 60 Hz LCD (16.7ms frame samples)
    50% less motion blur (2x less) — 120 Hz LCD (8.33ms frame samples)
    85% less motion blur (7x less) — 120 Hz LightBoost (2.4ms strobes)
    92% less motion blur (7x less) — 120 Hz LightBoost, set to 10% (1.4ms strobes)

    The motion blur on a Plasma is great, but not as good as CRT due to longer phosphor decay on a plasma (5ms) than on a CRT (1-2ms). There has now been several reports that for video games on a desktop computer monitor, LightBoost does an amazing job of eliminating motion blur — see LightBoost HOWTO. (LightBoost monitors are currently only available in 24″ to 27″ sizes).

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