CurtPalme.com Home Theater Forum

[WanMan]

Plasma flat panel technology uses a mixture of noble gases that when excited turn into a plasma. This plasma gives off UV light that excites the metal halide coatings on the sub-pixels, which in turn give off a photon of color (red, green, and blue). I get all of this.

'Each cell on a plasma display has to be precharged before it is due to be illuminated (otherwise the cell would not respond quickly enough) and this precharging means the cells cannot achieve a true black.' I get that, too.

So, because the need for pre-charging is there then I interpret this to mean there is a small amount of plasma being generated, and in turn a small amount UV, and thus a small amount of visible light. So, the question is why not coat the metal halide phosphor layer with a UV filtering coating to which there is a threshold of UV needed (or or threshold of plasma energies)?

We know there is already a UV filter somewhere on the panel otherwise we'd be getting those tans we didn't ask for. Of course, I wonder now exactly how Pioneer is achieving better (reported, not observed) black levels. Anyone?

[macgyver655]

First I'll say that the pre charging that your calling it is so faint that you cannot see it unless the room is almost completely dark. So it is not even close to being bright enough to affect visible black level.

Second, I dont know where your getting your info from but I like to read it. It is somewhat contradictory to what I have read.
Such as metal halide and UV light.

[macgyver655]

changed for correctness.

[ecrabb]

[macgyver655]

[ecrabb]

I thought you were off in subtractive land.

SC

[WanMan]

[macgyver655]

The problem I have with your explanation is your statement that the UV photon gives off the light. The UV photon actually contacts the phosphor and the phosphors atom jumps to a higher level and releases the visible light. The UV photon never exits the chamber.

[macgyver655]

Another thing I might add is that the front glass on a plasma is tinted which darkens the affect of the panel prime. This would help in the affect of the prime on the black levels.

[WanMan]

[macgyver655]

[WanMan]

Hmm, I thought the initial paragraph described exactly the nature of pre-charge in a plasma panel. That's not much reading. But, if you wish to attribute the minimum black level attainable in a plasma flat panel to something else, I'd be more than interested in hearing about it. I have already asked you for this information once before.

[macgyver655]

[WanMan]

[macgyver655]

Oh, you want to see reading material from which my comments come from.

Well first we have the pre charge issue. That is from experience which is why I said try it for yourself. You can see the pre charge if you turn the lights off with no image but you cant with lights on. Better yet, send it a black image with room lights on and see if it looks black or if you can see the pre charge. You can read all you want but what your blacks look like is all that really matters.

As far as the UV comment I made, I believe I questioned your interpretation and I explained why. The process I explained can easily be found but I'll also comment again. The UV proton is not visible to humans. It is created in the plasma gas when more electrons are introduced causing an instability in the plasma atom which then throws off the UV proton. The only purpose of the UV proton is to collide with the phospher atom which then throws off visible light of the color based on the phospher coating mixture. The UV proton then no longer exists.

These words are not a copy and paste. These are my own words from the various plasma training manuals and documents I have already read years ago.

I will go back later and reread the wiki link you posted but I wll first say the wiki is not always a good source for accurate info. But I will reread it with an open mind but I'm not sure if what it said or what you said is why I contradicted it.