Information in this thread is knowledge that was passed along to me, I do not have the engineering and design experience to claim any of this as 1st hand fact... so if this information is wrong... please correct it "IF" you are an Electrical Design Engineer who actually "knows". Not because you read it somewhere else on some other post, on some other website or on some review page done with biased opinions. I have yet to find an article on the "LCD vs. Plasma" debate that wasn't biased...
This has been a big debate on several threads across multiple forums. Everytime the subject of image blur and response time comes up, it seem everybody starts discussing this. So I did some digging and was able to speak wih an electrical engineer who works in this field (design, not a TV repair guy), and this is how he explained it to me....
From the begginning...
So the debate always revolves around Plasma vs. LCD, pixel response time and frame rate... (just paraphrasing the arguments here) Plasma has no blur due to pixel repsonse time, LCD has to introduce "tricks" to compete in this category... Refresh rates are not true... Plasma doesn't "need" any enhancements that have been introduced into the LCD market... on and on...
The rest of this is what I was told by an Electrical Engineering Design Major who works in AV field. Most of the advertising you see for ALL TVs is BS... It's marketing strategy to explain how it works to people who are shopping for a TV. Synchronizing frames of video with refresh rates of the TV simply does not happen...
Refresh Rates and video frames...
We are told by "advertising" that a 600Hz Plasma TV will take a 1080p/24 source and display each frame of video 25 times (24 x 25 = 600). And that a 240Hz LCD will take a 1080p/24 source and display each frame of video 10 times (24 x 10 = 240). This is a matter of coincidence ONLY. Let me explain.
For those who play video games on PC, you know that you can typically select an option to "sync every frame" of video with your display refresh rate to get smoother gameplay, and no tearing in the video frames. This is possible on a PC because the video card actually creates the video material AND controls the refresh rate, which means it can synchronize the two... A TV does not create the souce, it receives it from the Satellite, or Cable, or BluRay player or game system... or whatever other device that is sending the signal. The TV processes the video signal and displays the image to the screen. The advertising of each video frame being displayed "x" amount of times is simply marketing to explain to Joe Blow, what exactly a refresh rate is. Image processing and Refresh Rates are independant processes when it comes to TVs.
If you are watching a Blu-Ray, connected via HDMI, set to output 1080p/24... then the Blu-Ray player is sending 24 video frames per second (24Hz), and your TV is displaying 24 frames per second. If you are watching TV, the signal a 60Hz signal, and your TV is displaying 60 video frames per second, regardless of what material the original source was formatted. Now while your BluRay player is sending 24 video frames per second, and your TV is "processing" the signal of 24 video frames per second to be displayed, your TVs refresh rate is constantly operating to refresh the screen image that is processed by your TV. The two processes are not directly linked, they just work together in series to display a constant moving video image to your TV screen at what ever video frame rate happens to be sent to your TV. This is the standard, unmodified process with no Motion Smoothing or Interpolation.
What "is" the refresh rate of your TV??
If your LCD TV says 120Hz, then the refresh rate is 120Hz... If it says 240Hz, then it's 240Hz. And YES... even if it says 480Hz, the video screen (not processed image data) is refreshed at a rate of 480 times per second. The piece of hardware that controls "refresh rate" has no connection to the piece of hardware that sends the image data to the screen, other than the video data being sent "through" it, not "processed BY it". That being said, the refresh rate is a constant... you do not need to enable the "Motion Smoothing" on your LCD for it operate at 120Hz, 240Hz or 480Hz. This is simply more marketing because with the "Motion Smoothing" enabled, there is still less "blur" with this feature enabled regardless of the negative effects it may have on the picture.
For plasma it's a little different. EACH Idividual pixel is actually refreshed at 600Hz (YES 600 times per second). Effectively, that means the the entire video screen (not processed image data) is refreshed at a rate of 600Hz as well. Which is why Plasma does not need improvement in image "display" technology to address blur, because there is none. It litterally is already fast enough.
LCDs and Scanning backlights...
There is also a lot of information that says the 240Hz refresh rate of an LCD is acheived by combining 120 video frames and inserting black frames inbetween each video frame in each second. That's 120 video frames plus 120 black frames, to equal 240 frames per second (240Hz). Or 240 + 240 for 480Hz TVs. I was told that the scanning backlight is actaully a completely seperate process from the refresh rate. A 240Hz TV will refresh the actaul screen image 240 times per second wether that TV has scanning backlight technology or not. The explanation of intertwining the video frames and the "black frames" is simply another "advertising" explanation for Joe Blow. I did not ask him to explain the "scanning backlight", so I have no idea what it actauly does. But he said said it is a technology that actually has something to do directly with the "backlight" of the LCD TV, and nothing to do with the refresh rate (two seperate processes).
Are repsonse rate and refresh rate related? not really.
Plasma pixels are "refreshed" at 600Hz (1 / 600 = 0.00166666... sec, or 1.67ms) There are a few websites who say the pixel "response" time is 0.00167ms, which would equal 0.00000166666...sec). I read one of those and the author actually re-canted to state that he had a typo when stating 0.00167ms, and meant 1.67ms. By that logic, the pixels are refreshed as fast as they can respond, or change their state. Which also means that a Plasma pixel can change it's color 600 times per second. The engineer I spoke with confirmed 1.67ms, not 0.00167ms. Argue about it if you want, at either speed it doesn't really matter anyway.
The fastest LCDs are refreshed at 480Hz (1 / 480 = 0.002sec, or 2ms). However, the fastest pixel response (I've seen advertised) is 4ms, which would be closer to that 240Hz refresh rate. Can that be possible, 480Hz with a 4ms pixel response?... sure! It just means that the fastest Image change you will see on an LCD will be 240Hz. The state change (color change), or response of the pixel is seperate from the screen refresh rate of the LCD. So with a 4ms repsonse time, the most image changes possible would be 250 per second. And at a 480Hz refresh rate, the screen gets refreshed twice while the pixels are in the same state.
Remember, the video signal is displayed to the screen at the same rate it is delivered from the device (24Hz or 60Hz).
Motion Smoothing and Interpolation
It seems that early on in the development of 120Hz LCD TVs, these two technologies were viewd as one in the same. But recently they are two seperate processes. Motion Smoothing reduces the flicker caused by a true 24 frames per second display rate. Interpolation creates brand new video frames, which are estimated from the two adjacent video frames, in order to produce a "smoother" video playback (this creates the "video" or "soap opera" effect).
At true 24 frame per second, there is a visible flicker between the video frame changes which can be annoying for some people (including myself). Both LCD and Plasma TVs have "Motion Smoothing" technologies. Plasmas have Smoothing that runs at 48Hz, 72Hz, and 96Hz, to display each video frame 2, 3, and 4 times respectively to help reduce the flicker between the video frames. LCD TVs running at 240Hz, depending on the implementation, will process each video frame at 120Hz or 240Hz to display each video frame 5 or 10 times respectively to reduce the flicker between each video frame. This technology does NOT edit the original source video "data", it just refreshes each frame more often which reduces the amount of time the "black" frame flicker is seen, effectively creating a smoother video experience. (In my opinion, this works quite well in LCDs and Plasmas)
Inerpolation currently only exists in LCDs. This is the technology the take the 24 video frames per second, and uses a mathematical algorithm to create entirely new video frames to be added inbetween the original video frames. This effectively creates a smoother video effect by displaying more unique video frames per second which makes the video material seem smoother. This has two effects. The first is artifacting, or errors in the "newley created" video frames. This is mostly because the background image is estimated between the two frames... so it looks a little "off" when somebody walks across the screen. The second effect is that the movie now looks more like Video (60Hz) or a soap opera.
Both of these processes are handled by the video "image pocessing" of the TV. The video data is processes and delivered to the screen where the refresh rate make sre that the screen image i constantly displayed to the screen and the native refresh rate of 60Hz, 120Hz, 240Hz, 480Hz or 600Hz)
Conclusion
If there are any "Electrical Engineers" out there who are active in the field of AV design technology who can review this information, please clarify anything that is wrong and verify those things that are correct... Thanks!
This has been a big debate on several threads across multiple forums. Everytime the subject of image blur and response time comes up, it seem everybody starts discussing this. So I did some digging and was able to speak wih an electrical engineer who works in this field (design, not a TV repair guy), and this is how he explained it to me....
From the begginning...
So the debate always revolves around Plasma vs. LCD, pixel response time and frame rate... (just paraphrasing the arguments here) Plasma has no blur due to pixel repsonse time, LCD has to introduce "tricks" to compete in this category... Refresh rates are not true... Plasma doesn't "need" any enhancements that have been introduced into the LCD market... on and on...
The rest of this is what I was told by an Electrical Engineering Design Major who works in AV field. Most of the advertising you see for ALL TVs is BS... It's marketing strategy to explain how it works to people who are shopping for a TV. Synchronizing frames of video with refresh rates of the TV simply does not happen...
Refresh Rates and video frames...
We are told by "advertising" that a 600Hz Plasma TV will take a 1080p/24 source and display each frame of video 25 times (24 x 25 = 600). And that a 240Hz LCD will take a 1080p/24 source and display each frame of video 10 times (24 x 10 = 240). This is a matter of coincidence ONLY. Let me explain.
For those who play video games on PC, you know that you can typically select an option to "sync every frame" of video with your display refresh rate to get smoother gameplay, and no tearing in the video frames. This is possible on a PC because the video card actually creates the video material AND controls the refresh rate, which means it can synchronize the two... A TV does not create the souce, it receives it from the Satellite, or Cable, or BluRay player or game system... or whatever other device that is sending the signal. The TV processes the video signal and displays the image to the screen. The advertising of each video frame being displayed "x" amount of times is simply marketing to explain to Joe Blow, what exactly a refresh rate is. Image processing and Refresh Rates are independant processes when it comes to TVs.
If you are watching a Blu-Ray, connected via HDMI, set to output 1080p/24... then the Blu-Ray player is sending 24 video frames per second (24Hz), and your TV is displaying 24 frames per second. If you are watching TV, the signal a 60Hz signal, and your TV is displaying 60 video frames per second, regardless of what material the original source was formatted. Now while your BluRay player is sending 24 video frames per second, and your TV is "processing" the signal of 24 video frames per second to be displayed, your TVs refresh rate is constantly operating to refresh the screen image that is processed by your TV. The two processes are not directly linked, they just work together in series to display a constant moving video image to your TV screen at what ever video frame rate happens to be sent to your TV. This is the standard, unmodified process with no Motion Smoothing or Interpolation.
What "is" the refresh rate of your TV??
If your LCD TV says 120Hz, then the refresh rate is 120Hz... If it says 240Hz, then it's 240Hz. And YES... even if it says 480Hz, the video screen (not processed image data) is refreshed at a rate of 480 times per second. The piece of hardware that controls "refresh rate" has no connection to the piece of hardware that sends the image data to the screen, other than the video data being sent "through" it, not "processed BY it". That being said, the refresh rate is a constant... you do not need to enable the "Motion Smoothing" on your LCD for it operate at 120Hz, 240Hz or 480Hz. This is simply more marketing because with the "Motion Smoothing" enabled, there is still less "blur" with this feature enabled regardless of the negative effects it may have on the picture.
For plasma it's a little different. EACH Idividual pixel is actually refreshed at 600Hz (YES 600 times per second). Effectively, that means the the entire video screen (not processed image data) is refreshed at a rate of 600Hz as well. Which is why Plasma does not need improvement in image "display" technology to address blur, because there is none. It litterally is already fast enough.
LCDs and Scanning backlights...
There is also a lot of information that says the 240Hz refresh rate of an LCD is acheived by combining 120 video frames and inserting black frames inbetween each video frame in each second. That's 120 video frames plus 120 black frames, to equal 240 frames per second (240Hz). Or 240 + 240 for 480Hz TVs. I was told that the scanning backlight is actaully a completely seperate process from the refresh rate. A 240Hz TV will refresh the actaul screen image 240 times per second wether that TV has scanning backlight technology or not. The explanation of intertwining the video frames and the "black frames" is simply another "advertising" explanation for Joe Blow. I did not ask him to explain the "scanning backlight", so I have no idea what it actauly does. But he said said it is a technology that actually has something to do directly with the "backlight" of the LCD TV, and nothing to do with the refresh rate (two seperate processes).
Are repsonse rate and refresh rate related? not really.
Plasma pixels are "refreshed" at 600Hz (1 / 600 = 0.00166666... sec, or 1.67ms) There are a few websites who say the pixel "response" time is 0.00167ms, which would equal 0.00000166666...sec). I read one of those and the author actually re-canted to state that he had a typo when stating 0.00167ms, and meant 1.67ms. By that logic, the pixels are refreshed as fast as they can respond, or change their state. Which also means that a Plasma pixel can change it's color 600 times per second. The engineer I spoke with confirmed 1.67ms, not 0.00167ms. Argue about it if you want, at either speed it doesn't really matter anyway.
The fastest LCDs are refreshed at 480Hz (1 / 480 = 0.002sec, or 2ms). However, the fastest pixel response (I've seen advertised) is 4ms, which would be closer to that 240Hz refresh rate. Can that be possible, 480Hz with a 4ms pixel response?... sure! It just means that the fastest Image change you will see on an LCD will be 240Hz. The state change (color change), or response of the pixel is seperate from the screen refresh rate of the LCD. So with a 4ms repsonse time, the most image changes possible would be 250 per second. And at a 480Hz refresh rate, the screen gets refreshed twice while the pixels are in the same state.
Remember, the video signal is displayed to the screen at the same rate it is delivered from the device (24Hz or 60Hz).
Motion Smoothing and Interpolation
It seems that early on in the development of 120Hz LCD TVs, these two technologies were viewd as one in the same. But recently they are two seperate processes. Motion Smoothing reduces the flicker caused by a true 24 frames per second display rate. Interpolation creates brand new video frames, which are estimated from the two adjacent video frames, in order to produce a "smoother" video playback (this creates the "video" or "soap opera" effect).
At true 24 frame per second, there is a visible flicker between the video frame changes which can be annoying for some people (including myself). Both LCD and Plasma TVs have "Motion Smoothing" technologies. Plasmas have Smoothing that runs at 48Hz, 72Hz, and 96Hz, to display each video frame 2, 3, and 4 times respectively to help reduce the flicker between the video frames. LCD TVs running at 240Hz, depending on the implementation, will process each video frame at 120Hz or 240Hz to display each video frame 5 or 10 times respectively to reduce the flicker between each video frame. This technology does NOT edit the original source video "data", it just refreshes each frame more often which reduces the amount of time the "black" frame flicker is seen, effectively creating a smoother video experience. (In my opinion, this works quite well in LCDs and Plasmas)
Inerpolation currently only exists in LCDs. This is the technology the take the 24 video frames per second, and uses a mathematical algorithm to create entirely new video frames to be added inbetween the original video frames. This effectively creates a smoother video effect by displaying more unique video frames per second which makes the video material seem smoother. This has two effects. The first is artifacting, or errors in the "newley created" video frames. This is mostly because the background image is estimated between the two frames... so it looks a little "off" when somebody walks across the screen. The second effect is that the movie now looks more like Video (60Hz) or a soap opera.
Both of these processes are handled by the video "image pocessing" of the TV. The video data is processes and delivered to the screen where the refresh rate make sre that the screen image i constantly displayed to the screen and the native refresh rate of 60Hz, 120Hz, 240Hz, 480Hz or 600Hz)
Conclusion
If there are any "Electrical Engineers" out there who are active in the field of AV design technology who can review this information, please clarify anything that is wrong and verify those things that are correct... Thanks!
