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480hz Sub-field drive?

post #1 of 32
Thread Starter 
Hey guys, I'm moderately versed in television technology, and have almost settled on the Panasonic TH-50PZ800U, but there is one thing holding me back from finalizing my decision.

The one thing I do like about LCD technology, is the smooth motion (albeit a bit unnatural) you get from a 120hz processor.

Now, I've heard about this 480hz sub field drive from Panasonic...I know it isn't the same sort of thing as 120hz...but how does it compare in terms on minimizing motion blur?

That's the only thing holding me back from buying this TV TODAY.

Now, I've also been considering the Samsung PN50A550...now, would this 480hz technology that Panasonic offers make for a smoother image during high motion content, that this Samsung model would? And how would this Panasonic compare to an LCD with 120hz in that regard?

It's my first post here...thank you for the help guys.
post #2 of 32
Thread Starter 
Anyone?
post #3 of 32
post #4 of 32
Quote:
Originally Posted by AmateurWrestler View Post

Now, I've heard about this 480hz sub field drive from Panasonic...I know it isn't the same sort of thing as 120hz...but how does it compare in terms on minimizing motion blur?

I'll try and answer your question as well as subsequent probable questions

Where does the number come from? - As far as I know, every single commercial plasma display ever made uses 8 or more subfields to make up one frame of video/film. And when refreshing at 60Hz this equates to 480 subfields per second.

8 subfields per frame x 60 frames per second = 480 subfields per second = 480Hz

If it is not new to Plasma then why use it? - Marketing against 120Hz for LCD

Is it important to motion just like 120Hz? - No

Then why even use this number in marketing? - Good question! I suspect because it is bigger than 120 and has "Hz" at the end of it

Why is Plasma so good with motion then? - Plasma has a shorter duty cycle than LCD as well as a shorter display time than even 120Hz LCD


Quote:
Originally Posted by AmateurWrestler View Post

Now, I've also been considering the Samsung PN50A550...now, would this 480hz technology that Panasonic offers make for a smoother image during high motion content, that this Samsung model would?

No because of reason above. Also, Samsung also has 480Hz or more like every other plasma

Quote:
Originally Posted by AmateurWrestler View Post

And how would this Panasonic compare to an LCD with 120hz in that regard?

In theory motion blur should be better on the plasma but without the 3D-unnatural effect of the LCD
post #5 of 32
This is another way to describe the pulse-width modulation system that ALL plasma panels need to use in order to produce an image (it is called PWM).

A plasma TV doesn't produce shades of grey in the same manner as an LCD panel, the panel must cycle the image several times per frame to create the shades of grey, in the case of Panasonic they cycle the pixels 8 times for each frame: 8x60 frames = 480hz.

I have been told that this is a conservative rating and that the panels are actually cycling at 720Hz (12 bit or 12 cycles).

Either way, all panels must cycle at least 8 times per frame (8 bit) and so this is simply Panasonic creating a marketing story while others have sat on the bench and watched.

I do not feel that this is a deceptive marketing story because it is a way for Panasonic to explain their motion advantages to salespeople and customers without having to explain the switching topography of the device.

Hope this helps.
post #6 of 32
Damn you xrox, to fast and better than my post

One question for you, wouldn't the modulation speed of 8 frames or greater reduce the sample and hold effect?

If this is the case than wouldn't 480/720/960 Hz PWM be at least partly responsible for the motion response?
post #7 of 32
Quote:
Originally Posted by LXIX View Post

Damn you xrox, to fast and better than my post

One question for you, wouldn't the modulation speed of 8 frames or greater reduce the sample and hold effect?

If this is the case than wouldn't 480/720/960 Hz PWM be at least partly responsible for the motion response?

Actually, I like your post better. I have a hard time explaining stuff clearly. As for your question: the 480/720/960 Hz number gives no information about how long each pulse was emitting light. All it tells you is how many pulses there are. For instance, a 480 (8-pulse) display might fill the entire frame with light if each pulse was 1/8th the time of each frame. On the other hand each pulse could be 1/100000000 the time of each frame with off time in between each pulse. Both displays would have 480Hz but the first would have much greater motion blur.
post #8 of 32
Thanks xrox, that makes sense.
post #9 of 32
I've been reading through a bunch of patents on sub-field drives, and I don't yet have a "full" understanding of what goes into them. Here's what I've got so far:

For each frame displayed during 60 Hz playback, there are 8 sub-fields. Each sub-field contains a series of pulses designed to index and illuminate each pixel in the PDP. Within each subfield there are numerous voltage pulses designed to modulate the luminance of each subpixel within the pixel, which take into account phosphor luminance decay. It is not clear to me whether luminance is modulated by the amplitude of an analog voltage pulse during the subfield pulse train, or a series of discrete "digital" pulses.

If it is the analog case, then the voltage output on the panel is likely controlled by a digital-to-analog converter. If the 480 Hz subfield refreshes 8 times, there is no requirement that each of these refreshes is the same duration, nor carries the same luminance. In the end, the observed luminance is the weighted sum of the luminance of all 8 subfields. If each subfield is modulated by a 9-bit DAC (512 shades) then you would end up with a possible 4096 shades in the end and could claim to operate a 12-bit panel.

FXIX's intepretation suggests a digital pulse train, but does not add up. If the luminance is digitally modulated, then 480 Hz is not a fast enough cycle to produce 4096 shades at 60 fps. This would in fact require 246 kHz.
post #10 of 32
Quote:
Originally Posted by -Spiff- View Post

I've been reading through a bunch of patents on sub-field drives, and I don't yet have a "full" understanding of what goes into them. Here's what I've got so far:

We should share info, there are a few of us who read PDP patents on this board(D-Nice is another).

Quote:
Originally Posted by -Spiff- View Post

For each frame displayed during 60 Hz playback, there are 8 sub-fields

Depends on the manufacturer, pioneer uses 14 subfields.

Quote:
Originally Posted by -Spiff- View Post

Each sub-field contains a series of pulses designed to index and illuminate each pixel in the PDP

reset - address - sustain

Quote:
Originally Posted by -Spiff- View Post

Within each subfield there are numerous voltage pulses designed to modulate the luminance of each subpixel within the pixel, which take into account phosphor luminance decay. It is not clear to me whether luminance is modulated by the amplitude of an analog voltage pulse during the subfield pulse train, or a series of discrete "digital" pulses.

Luminance is modulated by the number of sustain pulses in each subfield. The number of sustain pulses = pulse width for a given subfield.

Quote:
Originally Posted by -Spiff- View Post

If the 480 Hz subfield refreshes 8 times, there is no requirement that each of these refreshes is the same duration, nor carries the same luminance.

The duration of each pulse is governed by the number of sustain pulses. 480Hz is just a number to describe the overal pulses per second (see previous posts)

Quote:
Originally Posted by -Spiff- View Post

In the end, the observed luminance is the weighted sum of the luminance of all 8 subfields. If each subfield is modulated by a 9-bit DAC (512 shades) then you would end up with a possible 4096 shades in the end and could claim to operate a 12-bit panel.

Lost me here. From what I know the number of possible shades is governed by either the number of subfield combinations (binary combinations) or the number of subfields (contiguous). Dither and error diffusion are added to jack up the number of possible shades.

Quote:
Originally Posted by -Spiff- View Post

FXIX's intepretation suggests a digital pulse train, but does not add up. If the luminance is digitally modulated, then 480 Hz is not a fast enough cycle to produce 4096 shades at 60 fps. This would in fact require 246 kHz.

480Hz is not the drive frequency. To find the drive frequency you need to look at the sustain pulse frequency. Furthermore, shades are not related to the drive frequency but rather the drive mode (Binary or Contiguous).


P.S. - Sorry to everyone who read all that, I know it is dry stuff to most
post #11 of 32
Thanks xrox! That clears a lot up. Never mind the DAC stuff I mentioned before.

The sustain pulse is a finite amplitude with a modified and distributed duration. The sustain pulse amplitude is enough to arc a sub-pixel plasma cell, which produces UV and excites the phosphors.

The number of shades must be defined per frame. For example, to display 4096 shades (12-bit) at 60 Hz, the minimum clock frequency for the sustain pulses would be approximately 256 kHz. This would mean phosphor decay times would be on the order of 4 microseconds. A quick google search on "plasma display phosphor decay times" gives a lower limit of 5 microseconds for green, which is apparently the slowest phosphor.

The luminance you observe has to do with the dithering of the luminance of the subfields. Dithering of sustain pulses within a 480 Hz subfield should be unnoticeable. However, in order to ensure that you don't see one frame blend into the next, you need to make sure some that some of the later sub-fields are essentially black. This leads to an observable duty cycle or "flicker".
post #12 of 32
In a nutshell, the system is designed to minimize resolution lost during motion reproduction, ensuring sharper and smoother visuals with over 900 lines of details. The PY800-series is also probably the first in America to field the BBE ViVA high-definition 3D (HD3D) software. This is an audio post-processing said to be compatible with all TV programs and capable of serving out musically accurate 3D imaging.
post #13 of 32
post #14 of 32
Quote:
Originally Posted by -Spiff- View Post

Within each subfield there are numerous voltage pulses designed to modulate the luminance of each subpixel within the pixel, which take into account phosphor luminance decay.

It sounds like this might be the reason behind the very subtle "dancing pixels" effect I see when I look very closely at a still picture?
post #15 of 32
Quote:
Originally Posted by xrox View Post

We should share info, there are a few of us who read PDP patents on this board(D-Nice is another).

Depends on the manufacturer, pioneer uses 14 subfields.

reset - address - sustain

Luminance is modulated by the number of sustain pulses in each subfield. The number of sustain pulses = pulse width for a given subfield.

The duration of each pulse is governed by the number of sustain pulses. 480Hz is just a number to describe the overal pulses per second (see previous posts)

Lost me here. From what I know the number of possible shades is governed by either the number of subfield combinations (binary combinations) or the number of subfields (contiguous). Dither and error diffusion are added to jack up the number of possible shades.

480Hz is not the drive frequency. To find the drive frequency you need to look at the sustain pulse frequency. Furthermore, shades are not related to the drive frequency but rather the drive mode (Binary or Contiguous).


P.S. - Sorry to everyone who read all that, I know it is dry stuff to most

Is contiguous driving what Pioneer calls CLEAR driving??
post #16 of 32
Quote:
Originally Posted by coltsfreak18 View Post

Is contiguous driving what Pioneer calls CLEAR driving??

Yes, contiguous means subfields are always one after another. Therefore the only combinations possible are:

0
0+1
0+1+2
0+1+2+3
.
.
etc up to 14

CLEAR driving uses a single reset pulse at the start of each frame and then uses contiguous driving.

Super Clear driving is similar but uses an address while display type driving

Advanced Super Clear driving ....... not sure on yet.
post #17 of 32
Quote:
Originally Posted by -Spiff- View Post

This would mean phosphor decay times would be on the order of 4 microseconds. A quick google search on "plasma display phosphor decay times" gives a lower limit of 5 microseconds for green, which is apparently the slowest phosphor.

Actually this is inaccurate, the phosphor decay time should be faster than the frequency, if it is 60Hz, the decay should take less than 16ms (miliseconds) (1/60). The 4 microseconds (or 3 microseconds if 5120 shades is the case) is only related to the activation of the sustain pulse, the response time.

Usually the only phosphor that decays faster than a millisecond is the blue phosphor, the most common used in PDPs is the divalent Europium-activated barium magnesium aluminate2+ (BaMgAl₁₀O₁₇:Eu²⁺). The red phosphor decay time is usually around 4-9ms. The most common red phosphor in PDPs is the Europium-activated yttrium, gadolinium borate {[(Y,Gd)BO₃:Eu³⁺]}.

Now, the green phosphor decay is the slowest, in general. The most commonly used is the Manganese-activated zinc silicate phosphor (Zn₂SiO₄ :Mn⁺), known as P1, which has an average decay time of about 14-22ms. Depending on the amount of the Mn it changes the decay time and its chromaticity. Faster decay means less precise color reproduction.

http://www.iitk.ac.in/asid06/proceed...rs/MB1_1-I.pdf
http://www.patentstorm.us/patents/56...scription.html

Quote:
Originally Posted by -Spiff- View Post

The luminance you observe has to do with the dithering of the luminance of the subfields. Dithering of sustain pulses within a 480 Hz subfield should be unnoticeable. However, in order to ensure that you don't see one frame blend into the next, you need to make sure some that some of the later sub-fields are essentially black. This leads to an observable duty cycle or "flicker".

THe doubt I have is related to the changes in Hz PDPs often do, like changing from 60Hz to 96Hz for 24p 4:4 pulldown. How the subfield drive behaves in this case, if it can't increase its frequency it has to decrease the number of subfields (therefore reducing the shades) or some other short of trickery. This is really interesting, 'cause it plays a role in the overall quality of these different Hz modes.
post #18 of 32
Quote:
Originally Posted by xrox View Post

I'll try and answer your question as well as subsequent probable questions

Where does the number come from? - As far as I know, every single commercial plasma display ever made uses 8 or more subfields to make up one frame of video/film. And when refreshing at 60Hz this equates to 480 subfields per second.

8 subfields per frame x 60 frames per second = 480 subfields per second = 480Hz

If it is not new to Plasma then why use it? - Marketing against 120Hz for LCD

Is it important to motion just like 120Hz? - No

Then why even use this number in marketing? - Good question! I suspect because it is bigger than 120 and has "Hz" at the end of it

Why is Plasma so good with motion then? - Plasma has a shorter duty cycle than LCD as well as a shorter display time than even 120Hz LCD


No because of reason above. Also, Samsung also has 480Hz or more like every other plasma

In theory motion blur should be better on the plasma but without the 3D-unnatural effect of the LCD

Thanks X!

Chris
post #19 of 32
Quote:
Originally Posted by xrox View Post

Lost me here. From what I know the number of possible shades is governed by either the number of subfield combinations (binary combinations) or the number of subfields (contiguous). Dither and error diffusion are added to jack up the number of possible shades.

xrox, I believe all the shades are the result of dithering, the luminance dithering and the halftonig (a dithering method) by the subfields.

Like Spiff said, if you have 8 subfields, and the PDP is capable of displaying 5120 shades, 640 "shades" should be achieved through the luminance dithering. Therefore the drive speed should be around ~ 320Khz. At this frequency we would get a response time of around 3µs.

Difficult to achieve would be the 262144 shades Samsung claims, with 8 subfields at least. I don't think Samsung (if the shade number is true) is using only subfields or the same Drive method.
post #20 of 32
European models don't have that technology.

They HOWEVER have something that they call as 100hz Double Scan (not that I even know what it does).

Anyways, this is what they say:

Quote:
Originally Posted by Panasonic Global Site (for Europe) View Post

A PDP driven at 50 hz causes an annoying flicker due to a shortage in the number of pictures displayed per second. Therefore, each picture is displayed twice as if the PDP is driven at 100hz Double Scan, i.e., the number of pictures is displayed is increased to reduce the flicker.

Or whatever it says

http://www.panasonic.net/avc/viera/features/europe.html
post #21 of 32
Quote:
Originally Posted by HighDeath View Post

xrox, I believe all the shades are the result of dithering, the luminance dithering and the halftonig (a dithering method) by the subfields.

Like Spiff said, if you have 8 subfields, and the PDP is capable of displaying 5120 shades, 640 "shades" should be achieved through the luminance dithering. Therefore the drive speed should be around ~ 320Khz. At this frequency we would get a response time of around 3µs.

Difficult to achieve would be the 262144 shades Samsung claims, with 8 subfields at least. I don't think Samsung (if the shade number is true) is using only subfields or the same Drive method.

What do you mean by "luminence dithering"? The KHz frequency in Plasma governs the sustain pulse frequency, not the number of shades.
post #22 of 32
Quote:
Originally Posted by Blackraven View Post

European models don't have that technology.

They HOWEVER have something that they call as 100hz Double Scan (not that I even know what it does).

Anyways, this is what they say:



Or whatever it says

http://www.panasonic.net/avc/viera/features/europe.html

Double scan means each frame is displayed twice to reduce flicker. This requires a rearranging of subfield strengths. I have the original patent on this. It is solely to reduce flicker by increasing the "effective" duty cycle.
post #23 of 32
Quote:
Originally Posted by xrox View Post

What do you mean by "luminence dithering"? The KHz frequency in Plasma governs the sustain pulse frequency, not the number of shades.

That is exactly what i am talking about, the sustain pulse and the luminance of the subfields. The sustain period controls the amount of luminance (brightness) adressed to a respect subfield.

post #24 of 32
Quote:
Originally Posted by HighDeath View Post

That is exactly what i am talking about, the sustain pulse and the luminance of the subfields. The sustain period controls the amount of luminance (brightness) adressed to a respect subfield.

Yes, exactly. I've just never heard this described as luminence dithering. That graphic describes binary ADS (binary address display seperate) driving. The number of gray levels (intrinsic to the subpixel) is determined by the binary combinations of 8 (ie 256 levels)

As far as sustain pulse numbers determining subfield width (Which I've already described in post #10) please review the following table:

post #25 of 32
Quote:
Originally Posted by xrox View Post

Yes, exactly. I've just never heard this described as luminence dithering. That graphic describes binary ADS (binary address display seperate) driving. The number of gray levels (intrinsic to the subpixel) is determined by the binary combinations of 8 (ie 256 levels)

As far as sustain pulse numbers determining subfield width (Which I've already described in post #10) please review the following table:


But that is it xrox, we are going through the same thing. The sustain pulse works in a AC frequency, hundreds of Khz, the combination of the pulses is the dithering of the luminance, since the width of the subfields and therefore the final tonality is the result of the of the "sum" of these pulses. While the combination of the subfields is the halftoning dithering.
post #26 of 32
Quote:
Originally Posted by HighDeath View Post

But that is it xrox, we are going through the same thing. The sustain pulse works in a AC frequency, hundreds of Khz, the combination of the pulses is the dithering of the luminance, since the width of the subfields and therefore the final tonality is the result of the of the "sum" of these pulses. While the combination of the subfields is the halftoning dithering.

Yes, I know it is AC. Like I said, I've never heard the subfield method described as dithering. And no, halftoning is not a combination of sufbfields.

We agree that the # of sustain pulses determine subfield width. Now do you agree that binary or contiguous combinations of subfields determine how many levels of gray a single subpixel can render?

And Halftoning (error diffusion or spacial/temporal dithering) uses a combination of pixels (usually 4) to render shades of gray.
post #27 of 32
Quote:
Originally Posted by xrox View Post

Yes, I know it is AC. Like I said, I've never heard the subfield method described as dithering. And no, halftoning is not a combination of sufbfields.

We are having a problem regarding the terms and names of the dithering method, i'll go into this without using an specific term.

So, let me expand a bit on this. The combination of the subfields generate the final tonality, in a similar way the combination os subpixels generate the final pixel color, as you said a group of pixels together to achieve the final intended shade through dithering.

The process of alternating the brightness (i'll use brightness here instead of luminance) of the combinated subfields effectively is the process behind the final shades rendered. Therefore the dithering and the halftoning. More bellow.

Quote:
Originally Posted by xrox View Post

We agree that the # of sustain pulses determine subfield width. Now do you agree that binary or contiguous combinations of subfields determine how many levels of gray a single subpixel can render?

Yes in part (i believe all, but there is something i want to clarify), there seems to be a confusion related to the ADS method. I believe in the end we will agree. But i am touching the point that the intensity of the combination of the sustain pulses is the main process behind the shades. it controls the brightness of the shades, therefore its tonality, the final shade. So, there are two process we are actually talking about, the first is the width of the subfields (related to the sustain pulses), and based on this width the combination of the subfields will render a shade (in a single subpixel). So this method of achieving a final width (brightness...) of the subfield and shade is Dithering from the beginning. All the methods used are randomizing the quantization error, the different intensities or widths that can be adressed are a representation of a "shade" data received by the PDP, that will be rendered through approximation achieved through combinations of widths of subfields and its combinations.

So, basically this everything is dithering, till we reach the final halftoning dithering of the combined pixels.


I don't know what you mean exactly by your last part, but error difusion, spatial dithering,... are indeed types of halftoning (like you mentioned), a cluster of dots (or whatever one wants to call) put together is an example. Another nice example from wikipedia can clarify why i used the term halftoning:

"Shades of gray were rendered by intermittently raising and lowering the pen, depending upon the luminance of the gray desired."

http://en.wikipedia.org/wiki/Error_diffusion

Nothing new there, for any of us, i believe we easily agree.
post #28 of 32
Quote:
Originally Posted by HighDeath View Post

We are having a problem regarding the terms and names of the dithering method, i'll go into this without using an specific term.

I get that feeling also......

Quote:
Originally Posted by HighDeath View Post

So, let me expand a bit on this. The combination of the subfields generate the final tonality of a subpixel, in a similar way the combination os subpixels generate the final pixel color, as you said a group of pixels together to achieve the final intended shade through dithering.

sounds good to me

Quote:
Originally Posted by HighDeath View Post

The process of alternating the brightness (i'll use brightness here instead of luminance) of the combinated subfields effectively is the process behind the final shades rendered. Therefore the dithering and the halftoning. More bellow.

I'm quite confused by your terminology use. I can only go by what I read on the subject and what I've wrote in this thread and many others comes from those papers. The individual subpixel brightness is modulated by combinations of subfields (Pulse Width Modulation -ADS). The final gray level the viewer sees is created by error diffusion + spacial dithering + rotational dithering of the original pixel data to adjacent pixels.

This is the correct terminology according to what I've read.

Quote:
Originally Posted by HighDeath View Post

Yes in part (i believe all, but there is something i want to clarify), there seems to be a confusion related to the ADS method. I believe in the end we will agree. But i am touching the point that the intensity of the combination of the sustain pulses is the main process behind the shades. it controls the brightness of the shades, therefore its tonality, the final shade. So, there are two process we are actually talking about, the first is the width of the subfields (related to the sustain pulses), and based on this width the combination of the subfields will render a shade (in a single subpixel). So this method of achieving a final width (brightness...) of the subfield and shade is Dithering from the beginning. All the methods used are randomizing the quantization error, the different intensities or widths that can be adressed are a representation of a "shade" data received by the PDP, that will be rendered through approximation achieved through combinations of widths of subfields and its combinations.

So, basically this everything is dithering, till we reach the final halftoning dithering of the combined pixels.

Sorry, I can't decipher that. You may be right on the money, but similar to above, I just can't understand the terminology.
post #29 of 32
Quote:
Originally Posted by xrox View Post

I'm quite confused by your terminology use. I can only go by what I read on the subject and what I've wrote in this thread and many others comes from those papers. The individual subpixel brightness is modulated by combinations of subfields (Pulse Width Modulation -ADS). The final gray level the viewer sees is created by error diffusion + spacial dithering + rotational dithering of the original pixel data to adjacent pixels.

This is the correct terminology according to what I've read.

That is the correct terminology, i just went through the process without the use of any specific terms to avoid any confusion of the terminology, as i said in my previous text.

The point i want to clarify in my view is related to the "classification" of the whole process as dithering. Since the beginning of the process everything is based on approximation and randomization of the Q error. So, we see the process in the same way, it couldn't be any different, the difference in our views, if any, reside in the classification of part of the process as dithering and the other as non-dithering. In my view, everything is based on dithering from the beginning.

There is something else i would like to talk to you about, the so called PWM noise, but i am really tired now, i'll bring this up tomorrow if you don't mind...
post #30 of 32
Quote:
Originally Posted by HighDeath View Post

That is the correct terminology, i just went through the process without the use of any specific terms to avoid any confusion of the terminology, as i said in my previous text.

The point i want to clarify in my view is related to the "classification" of the whole process as dithering. Since the beginning of the process everything is based on approximation and randomization of the Q error. So, we see the process in the same way, it couldn't be any different, the difference in our views, if any, reside in the classification of part of the process as dithering and the other as non-dithering. In my view, everything is based on dithering from the beginning.

Cool

Many people (actually most people) mistake rotational dithering for PWM noise.
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