This has been a confusing matter to many, including myself, I started a thread a while ago, take a look at it, there's an explanation at page 3 (post 40) -
http://www.avforums.com/forums/plasm...et-sorted.html
Basically it has nothing, or at least very little to do with motion like Panasonic are advertising. It has very little to do with 100Hz, and it has a very minimal effect on the actual picture quality.
In effect, with 600 subfields, with a 100Hz source (which is 100 fields) you get 6 sub fields per field. During this field the pixel can only activate and then deactivate (light up and turn off) once. The more subfields you have per field the more accurately you can reproduce colour (with more shades) and pixel noise can be reduced in the process as well. That's what I've got from it anyway.
On the whole though, ignore it, it's pretty meaningless, it's just a big number and a 'hype word' (Hz). Since 100Hz and now 200Hz on LCDs is a huge buying point to the general consumer, the plasma manufacturers wanted to beat this with a bigger number, so they can get away with 600Hz. But not only is 600Hz different (which is why they're also labelled as 100Hz), but these things do different things on LCD and plasma anyway!
EDIT: This is the post, it explains it well, if you can understand it! It took me a few read throughs
Quote:
Originally Posted by a-LeXx This is indeed pure marketing, they needed a large number - they've got it. That this number does not mean anything - doesn't matter, nobody cares. And indeed - we see that everyone is confused now.
Ok, here is how it works:
Plasma screen can indeed only have it's pixels on or off. There is no half-on or something like this.
So, how are different shades being generated?
The answer is simple - for every field, ANY plasma is using a number of subfields. In earlier days e.g. 300 subfields, which made 5 subfields per field (60Hz operation mode).
So, how is the 'luminance' being genearted out of those subfields?
This is done by differnt algorithms, every manufacturer is using their own. Common thing between them is - it is using a modified pulse-width-modulation. Modified, becaue a plasma cell can only be activated once during the sequence of one field.
Assuming 600 Subfields and 100Hz feed, we have 6 Subfields per field.
So, what are valid subfield sequences for e.g. a green sub-pixel?
1-0-1-0-1-0 is not a valid sequence - since, as I mentioned, a cell can be only activated once.
0-0-1-1-1-0 is a valid sequence. Here the cell is activated once at a subfield #3 and is being de-activated at a subfiled #6
How exactly this activatinon/deactivation is being implemented with every panel, e.g. in the middle of the subfiled sequence, at beginning or dynamically, is intellectual property of manufacturers and is not being disclosed.
There are a number of patents existing on this subject matter. The sequence of the subfield activation is important for a level of artifacts like False Contouring or flicker with plasma screens.
As such, number of subfields (e.g. 600) doesn't tell anything. The only important thing is - how many subfields per field are being used.
For example 480 Subfields, but with a 60Hz refresh, is better (8 subfields per field) than 600 Subfields at 100Hz (only 6 subfields per field).
So please just try to ignore those irritating numbers born in the depths of the marketing department, they do not have anything to do with how the picture or movement look like on the screen.
-Alex |