Are there any progress being done on phosphor decay time?

I'm not sure what exactly you are looking for, maybe the issue you described is above me but I'll chime in anyway.

Current flat panel tech, be it LCD or Plasma, all has some sort of degradation over time. Plasma has the phosphor decay and LCD has half-life to the back lighting. Both technologies have an estimated 60,000 hour half life to the brightness scale. Meaning at 60k they will be half as bright as they are when new. Even the latest RP sets with the LED backlights are estimated 30k half life. So it seems that any TV technology we buy is going to have degradation in quality over time.....

If this doesn't address the issue you are looking at then please be gentle...

Also unsure of what you're referring to. Could you be more specific? Heavy use here (~12 hours/day) and could still get 5 to 10 years on a set. how much is set on and what are your expectations?

He is referring to the rise and fall time of the phosphor material. Rise time is how long the phosphor takes to reach full luminence when excited and the fall time is how long it takes the phosphor to stop luminescing after excitation ceases (also called decay). The problem with phosphor RGB displays (CRT and Plasma) is that the seperate RGB phosphors have different rise and fall times that make "SOME" people able to see the different decay times during motion (appearing as yellow trails or blue leading edges).

I'm surprised more people don't complain about this issue. I'm not saying it's a serious issue or anything, but considering the small things that bother people I would think more would be vocal about it. Or maybe there aren't many people who can even see it. I wasn't even aware of it until I got a plasma and started seeing it. It's bothersome to me but it's a negative that doesn't outweigh the positives. I'm also a person who sees major rainbows in DLP displays.

Most intriguing.

First I've heard of it.

The artifact presents itself as a yellowish trail behind moving edges on the screen. The reason is that the blue phosphor material stops emitting light much faster than the green and red phosphor material that can take several milliseconds to stop emitting light. Here is a chart plotting luminence versus time for all three phosphor materials on a 42" plasma display. You can see the PWM code as well as the trailing green and red luminence (combining to produce yellow trails). Note the quick rise time of the blue phosphor that contributes to blue leading edges.

Due to the time scale this artifact is very hard to detect for most people.




XVN5,

I would suspect the lack of research into fixing this issue may be driven by the lack of consumer complaint. The issue is a scientific fact but since the majority of consumers seem to not percieve the artifact there is little incentive to fix it. The unfortunate result is that consumers like you that find the artifact obvious, distracting, and essentially a turn-off to this technology are out of luck.

I've read only one patent (5 years old) on developing a fix to this problem and here is a snippet from it:

In the future, the development of new chemical phosphor powders could avoid such problems by making the green and red phosphors quicker. Nevertheless, today it is not possible by signal processing only to completely suppress this effect but one can try to reduce it.

One known solution from the former patent application FR 0010922 of Thomson multimedia is to compensate the coloured trail while modifying the blue component in the temporal domain.

The most cumbersome on the phosphor lag effect is not the trail behind moving objects but its colour. Another solution is therefore to add a complementary trail on the color trail in order to discolor it or to add to the pixels in front of the moving object a complementary correction at least for the cells having the fastest response. These solutions are disclosed in another European Patent Application of the applicant EP 01250237.3.

These ideas applied together in a PDP give very good results, but need the implementation of a motion estimator.

The object of the present invention is to disclose a solution that compensates for the differences between the time responses of the three phosphors without the need of a motion estimator.

I can see the yellow trails (more or less depending on the content), but for me it's not as annoying as DLP rainbows and a small price to pay for avoiding the many LCD picture quality issues.

I used to be able to see them quite a bit. But I have not seen them at all lately. Perhaps once the phosphors get broke-in they become faster?

Same here after a panel breaks in they do seem to get faster, that or I have gotten used to it. It is most noticeable in video games, but I have also seen it in a few movies, like 300. A youtube video of the problem, while it isn't this bad in person, it can still be annoying.

http://www.youtube.com/watch?v=3kyllx3VaI8

This might sound stupid, but I think the yellow trails actually give the picture a more cinematic quality. Not sure exactly why, or how to describe it, but it does look like a movie theater that way.

Of course I'd rather they weren't there, but it seems that CRTs and single chip DLPs are still the only display techs with almost perfect motion.