Beware Of Phony LCD HDTV Refresh Rates

March 26th, 2012 · 39 Comments · 3D HDTV, LCD Flat Panel, LED LCD Flat Panels, News, Plasma

Buyers beware: top TV makers are quietly substituting industry standardized refresh rate specifications with their own artificial rate numbers, deceiving prospective buyers into purchasing an HDTV over a possibly better performing (but more honestly labeled) competing model.

These numbers, created by the marketing department, do little to explain a TV’s actual hardware capabilities.

Don’t get ripped off, read the following guide to help sort through the hype.

What is Refresh Rate?

Initially all LCDs (including LED LCD TVs) suffered from blurring with fast motion or panning in content. This is referred to as “motion blur.”  To reduce motion blur, manufacturers developed televisions that refresh (show) a new image faster than the standard rate of 60 times per section (stated as Hz or hertz). Using a technique called frame insertion, the TV creates new additional images that are inserted between the real, original image frames.  Television makers now offer HDTVs with refresh rates of 60, 120 or 240 Hz. The higher the rate, the less motion blur.

TV makers advertise these higher rates as a step-up feature, with 120 Hz TVs providing better motion performance than a 60 Hz version, and 240 Hz having less motion blur than 120Hz models. These numbers have been around long enough that prospective buyers see a number such as 120 or 240 on the box and assume it is the TV’s refresh rate. As such,  they expect to pay more for a higher refresh rate model.

TV makers use another technique to reduce perceived motion blur, called a scanning backlight or “black frame insertion,” often along with some additional, unspecified signal processing. These methods don’t change the refresh rate at all, instead they scan or turn off the backlight in a way that mimics some of the performance benefits of faster refresh Unfortunately, this doesn’t keep the biggest brands using their own made-up terms like “120 Clear Motion Rate” or 240 SPS “Scenes per second.” There is a significant hardware difference between a true 240 Hz refresh rate TV and a 240 “SPS” model that goes far beyond what the identical numbers imply. For example, a 240 SPS television likely has a 120 Hz refresh, but adds a “black frame insertion” feature that flashes the backlight in a way to justify calling the TV “240.”

TV makers claim their new ratings give consumers a better idea of how the TVs handle motion. They are implying that a “120 Clear Motion Rate” television is equivalent to a competing HDTV that actually displays a new frame 120 times per second by using a higher cost LCD panels and faster processors.

A number of 2012s models only supply this new rating on the TV box, and on TV makers’ respective websites, making it impossible for an informed and curious consumer to find out what their actually does. A number of TV makers have completely stopped listing the actual standardized refresh rate on certain models.

To say this another way, it would be like a car maker stating a car’s engine is a “6- cylinder equivalent,” based on some undisclosed testing criteria, but not actually disclosing how many cylinders the car actually has. Here are the specific deceptive manufacturer terms, broken down by company.

Year End Deals in TV, Video and Audio

Up to 25% Off Select HDTVs, Plus Free Shipping

Today’s Amazon Deals

Best Buy’s Hottest Deals

Amazon Prime

 Best Selling Soundbars and 5.1 Surround Systems

Best Selling Blu-ray Players

Sony

Sony uses the term Motionflow XR followed by a 240, 480 or 960 depending on the model. We contacted Sony to explain what these numbers mean.  A spokesperson cited three functions to determine the “XR” number:

“Frame insertion (interpolation),  LED backlighting blinking (line blinking), and Image Blur reduction via signal processing. So, for example, a Motionflow XR 960 can be found by multiplying the native refresh times four (240 x 4=960) or as Sony told us: “With frame interpolation, four distinct images in the same time period of 1/60th of a second. 240 Hz times 4 = 960″

We don’t understand this explanation, as it implies the TV creates at least 15 frames for every native frame, and we know of no TV signal processor with that kind of capability. 240 Hz is the most interpolation of any signal processors we are aware of available in any HDTV. Sony would not supply us with any type of test procedure used to determine how the Motionflow XR rate is created.

Sony has begun removing the true refresh rate in its specifications on the Sony website and substituting its proprietary a Motionflow XR number. For example its new KDL55EX640 only lists the TV as Motionflow XR240. Is this a 60 HZ model with backlight blinking and image blur processing, or a 120 Hz model with just backlight blinking? There is no way to tell definitively, unless you do what we did: We called to Sony customer service. They revealed this series has a native refresh rate of just 120 Hz.

Vizio

Vizio has begun to state on its boxes a number followed by SPS (Scenes Per Second). Nowhere on the box does it state a 240 SPS TV has a native refresh rate of 120 Hz (see top photo).

Considering we are still waiting for a response from a Vizio spokesperson for another inquiry we made over three weeks ago, we did not waste our time asking the company spokesperson another question that would be go unanswered at press time.

Samsung

Samsung uses the term “Clear Motion Rate” (CMR) followed by a 120, 240,480, 840 or 960. They too are dropping the true refresh rate on their website and on the product boxes of its 2012 models. (Verified by checking our  Costco and BJs warehouse clubs).

Samsung did supply us with a white paper that describes how they determine their methods for interpolating the CMR number. This method uses proprietary test signals (they did supply us with these test patterns). However, the description of test procedure lacked specificity and requires an unknown number and size of mirrors spinning with unknown rapidity on an unknown sized  turntable. These, and other omitted information, make duplicating Samsung’s tests impossible.

An example of Samsung’s box is its UN46EH6050. It states “Clear Motion Rate 120,” however we learned this TV has true refresh rate of 60 Hz.

Sharp

Sharp uses the term AquoMotion, such as AquoMotion 240. It is double the actual refresh rate. An AquoMotion 240 LED is really a 120 Hz refresh HDTV.

LG

According to the LG website, their TruMotion120 Hz and 240 Hz refresh rates on its 2012 HDTVs are actual refresh rates.  According to our tests we found the 120 Hz TruMotion provides a real refresh 60 Hz. We have not tested the higher end models but expect the 240 Hz models to be 120 Hz refresh and the 480Hz a 240 Hz refresh. For our tests and video go to our article here .

Panasonic

Panasonic lists the native rate on its 240 Hz panels and also lists “backlight scanning 1920″ as 240 refresh times 8 sections. Its lower end product such as the new E5 series the Panasonic website product  lists the panel drive as “60 backlight scanning” accurate except for omitting the “Hz” after 60. Its mid line ET5 model lists the panel drive as “360 backlight scanning” not mentioning this is a 120 Hz panel with three scanning sections to derive the 360 number.

Who Is Responsible?

We checked with a Costco spokesperson to determine who orders these misleading numbers on cartons, while omitting the lower true refresh rate. Is it the store or the vendor? The Costco spokesperson stated the vendor generates the text on TV boxes, Costco only makes requests regarding font style and size, but with no input on what specs the TV maker prints on the carton. If the vendor omits the refresh rate on the box, it’s not at the request of Costco.

What About Plasma

Plasmas create a picture in a completely different way than LEDs and LCDs. They do not suffer from motion blur. Plasma TV makers use a number based on the sub-fields plasmas use to create a frame. This number is typically 600. While this itself is somewhat misleading (it’s not 600 frames per second), it is marketed honestly, as we’ve only ever seen “600 Hz Sub-Frames” listed on boxes. If this is ever changed to 600 Hz, we promise to expose that as well. It’s worth noting that because plasmas don’t suffer from motion blur, this number is irrelevant anyway.

What to Do?

We were pleased to discover Best Buy, in its store signage, website, and circulars, continue to list accurately the true refresh rates of the HDTVs it carries. Amazon does this most of the time as well, but not in every case (such as the listing for the Sony EX640). If you see the words or initials SPS, Scenes Per Second, AquoMotion, Motionflow XR, Clear Motion Rate, or CMR you now know these numbers do not reflect the actual refresh rate of an HDTV. At best, they  are at least double the true number. The spec should read X Hz refresh rate.  Check and verify this important specification before purchasing your next TV. In all future HD Guru LCD TV reviews, we will list the actual refresh rate numbers, as well as the marketing claims.

 

 

Have a question for the HD Guru?
HD GURU|Email

 

Copyright ©2012 HD Guru Inc. All rights reserved. HDGURU is a registered trademark.

Tags:

39 Comments so far ↓

  • Mose

    Hello, I am considering Sony W670A which did not really specify Hz but only wrote Motionflow XR 200 on their website. please, what is the exact Hz for this set and what is your expert opinion of the set (42 inch W670A BRAVIA Internet LED backlight TV) in general. Hope to get a response soon, Thanks.

    We do not have any contacts within Sony outside the USA. So we have no way of knowing if it is 50 Hz or 100 Hz native LCD panel.

    We suggest contacting your Sony customer service to learn the native refresh rate.

    HD Guru

  • Meghan

    Looking to buy a new 55 inch TV for our den. I don’t want to get sucked into paying more for a TV when really I could get one that is just as good for a lower price. Really just looking for a great picture for watching sports and TV. We do not have a gaming system or watch a ton of movies from the blu-ray. Any suggestions?

  • Chris

    Is there any discernible difference between Samsung’s 720, 840, 960 & 1200 Clear Motion rates (all 240hz)?

  • Catz

    Thank you for posting this and everyone’s comments. I am in the market for a 32″ TV and been shopping around. Thanks to this blog, I’ve learned so much and you’ve saved me from purchasing fraudulent equipment.
    I don’t know how much to expect to pay for I did want high refresh and pixel display

    Though I don’t know what type of TV to get, LED LCD or Plasma or where to go to buy one in Houston Texas.

  • ian

    hi , just to let you know i bought a panasonic Viera TX-L42E6B LED HD, which states 100hz refresh rates, it only shows 50hz on the tv , i queried this with john lewis whom checked with panasonic their anwer was ” Thank you for your email regarding your Panasonic TX-L42E6B television. I am sorry to learn you are having a problem with the HZ rate of the television and I can understand how frustrating this must be.

    I have been in contact with Panasonic regarding your query. I have found out that television has a 100 Hz frame rate, which is the specification of the televisions picture quality. This is what you have seen on the advert specified. When your television is showing 50 Hz, this is a completely different aspect of the item. This is the general voltage of the television, which cannot be changed. This is why you have not been able to change this as the item has a fixed voltage.

    I would like to assure you that your television has a 100 Hz frame rate. There is little you can do to check this on the television but Panasonic have confirmed this the frame rate. Regrettably there is not a way to change the 50hz voltage as this is the fixed voltage of the television. “. this just proves what lies they tell.

  • Robinson R.

    I have a “360hz” LED Philips TV… is it true, or have I been played?

    There is no 360 Hz refresh LCD panel. Philips does not sell a 360 Hz TV . They do sell ones with 60 and 120 Hz + a scanning backlight and call the 60 Hz with scanning backlight 120 Hz PMR (Philips term of perfect motion rate) and the 240 Hz PMR (120 HZ refresh + scanning backlight)

    HD Guru

  • Eric

    You are only partly right… As I wasn’t hunting for a TV in 2012 I can’t say how things were then. But in September of 2013 I can say that most companies do tell you the true refresh rate. Their are less 240s on the market and the frame insertion methods are useful and most of the time can be turned off. So you get one that says 240 and it’s really 120. Thats not bad. You sound like a mad man rambling about things you don’t understand…

  • bw1

    Your position seems to be “we don’t understand it so it’s bull.” In some other forums, people who actually took the time to discuss the real science involved have a very different take on CMR values. Having the background to understand what they write, including the math involved, I’m more inclined to trust an opinion supported by actual information than your “it’s all mumbo jumbo” approach.

  • Sam M.

    Please check VIZIO 55” Class Razor LED™ Smart TV with Theater 3D®
    (54.64″ Diag.) MODEL NUMBER: M551D-A2R

    I got this with 3 yrs warranty for USD 999/-
    It says 240 Hz Refresh rate with Smooth Motion
    LED/LCD/Smart TV with 3D theater option.

    This is the latest model with VIZIO.
    Please suggest if this is my good choice or something comparable available in Samsung or Sony at that price ??

    Thank you.

  • Andrew

    BOB: No the 4ms you are reading is usually the amount of time the tv takes to go from grey to grey or black to black (response time)
    The Sharp TV model you mentioned is a 60hz unit.

    and for your second question. 720CMR on a Samsung LCD Tv would be the Clear Motion rate. It’s a proprietary number made up by Samsung. It’s most likely a 240hz TV. I have a Samsung with a 600 CMR and is a higher end 120hz TV. It should be a 1080p TV and will display 1080 resolution depending on the source used.

  • Bob B

    I have a Sharp Model LC46D62U. I purchased years ago. I think it still has one of the best pictures I have ever seen. The refresh rate on the specs is 4.0 ms refresh rate. What is that comparable to in HZ?

  • Bob B

    My neighbor just bought a new Samsung with CMR 720P. It is supposed to be a 1080P TV. So does the resolution drop to 720P when there is a lot of motion?

  • Rosemarie

    Very interesting article. I sent an email with several questions.

  • steve

    does anyone know if the new sony 4k tv (xbr65x900A) has the same processing as the xbr65hx950? i just got a 950 and have pretty bad motion blur on sports. was thinking of switching to 4k but if it has the same processing it would also have the motion blur. then i would probably need to go plasma instead – maybe the upcoming ZT60. thanks. steve.

  • Rob

    Hi! How about the Sony KLV- 32EX330 with a MotionFlow XR 100hz? The real refresh rate is 50hz only? TIA

  • Charlie B.

    tkmphoenix,

    your television is a 120hz television. you can go into the picture settings and adjust the motion. tcl47e5 is the one that is 60hz.

  • Charlie B.

    uchenna,

    the model ln40d550 is an 2011 model. all the 5 series of the samsungs are 60hz televisions. Once you dive into the 6 series and above that’s where you’ll get the 120hz+.

    the 6700 series lg is a trumotion 120hz. But if you have ever read the old articles about the lg’s black from insert, their televisions on such sets perform like 60hz televisions. It’s a frustrating thing in the market now because a lot of consumers aren’t aware of what they are buying. It’s always good to do a little research and find exactly what your putting your cash into.

  • Uchenna

    1. I hope you are not referring to me?
    2. There’s an igbo adage that goes, “Anyone who asks questions doesn’t miss his/her way”

    Mike, it’s advised you keep such observations to yourself. I don’t think the writer would’ve considered it necessary to write such an article if everyone was a geek and “all-knowing”.

  • Mike

    I read the article and then the comments. One thing really stands out. You are writing for intelligent people. Your readers do not seem too bright to me, if one is to judge by these comments.

  • Uchenna

    I want to purchase an LG 42″ -42LM6710. It lists a feature as “Trumotion (frame rate) 240GHz”. Do you think it actually is 120GHz? Do you think the TV can accept an input of 1080p/24 from a Bluray player?

    2. A cousin of mine has a 40″ Samsung LCD Series 5. What is your take on the refresh rate of the tv? ModelNo.: LA40d550K7R.

  • nadine

    I bought a 40″ hdtv from sharp model LC-40LE433U. It says it haw a refresh rate of 120hz but at the back of the tv it says 60hz. Is my tv 120hz or 60hz?
    Nadine

    The TV makers tell me this is a common question. The rear of the TV lists the power requirements of an HDTV. In the US it is AC (alternating current) in the 110-120 volt range at 60 HZ. This has nothing to do with a TVs refresh rate.

    To date we found the mis-labeling of 120 Hz on TVs that are really 60 HZ refresh based on our findings on tested LG 2012 model and by information we gathered around 2013 CES regarding its 2013 models. Our friend David Katzmeier at CNet found the latest 42 and 50-inch Vizios are labeled at 120 hz but his motion resolution tests give the same results of a 60 Hz TV.

    The only place to date we find fault with Sharp models is its classification of 240 Hz refresh models which when asked we are told they are 120 Hz refresh panels with a flashing backlight, not producing 240 separate images per second.

    HD Guru

  • seth

    I am looking at the a601i-a3 by vizio and am curious about its actual refresh rate. Everything i have found says 120 Hz Clear Motion. Nothing noted states sps or leaves off Hz, but Im still skeptical. Any information that can be offered would be appreciated.

    According to a review by our friend David Katzmaier at CNet the a601i-a3 increases motion resolution with the circuit on indicating it is 120 Hz. However unlike Samsungs and other brands you can’t get the TV to do 5-5 pulldown, only motion compensation created frame insertion meaning to lose judder in pans you have to live with the soap opera effect.

    We do not recommend any Vizio product because of reader complaints regarding warranty service. The issues range from very slow response to get a TV parts or repair, Vizio exchanging a broken TV for a refurbished unit in lieu of repairing it, to them telling set owners the cost of an out of warranty repair exceeds the replacement cost. Stay away and consider the 60-inch Sharp (Vizio uses a Sharp panel) or a Samsung or other tier 1 brand instead of tier 2 Vizio .
    If you insist on buying the Vizio, we recommend an extended warranty as without it, if the TV fails it become a very expensive boat anchor.

    HD Guru

  • tkmphoenix

    So I’m still confused. I just bought a Panasonic TC-L47E50 from Video Only, which promised 120Hz refresh. It also has their “360 backlight scanning”. I contacted Panasonic, and they tell me it has only 60Hz refresh. I can’t do a side by side, but the new Panasonic seems a little blurrier than my old Vizio. Do you knowledgeable folks think I should take it back

  • Tracy

    VIZIO M3D550KDE 55-inch 1080p 120Hz LED Smart 3D HDTV

    I am thinking about buying this tv. Is it a good one? If not what would you recommend. The price is $869. I want a 3d and smart tv with 120 hx(the right one) and 1080p. Please help!

  • Idol Fesoj

    I bought a Westinghouse UW40T8LW and it’s advertised as having 120hz, even the stickers on the TV itself says it is 120hz, but when I press info on the remote it is saying that it is running at 60Hz only. Westinghouse told me that it is because my input (FIOS HDTV) is only 60Hz. Is this just some bull so I will just go away or the TV is supposed to convert that signal to 120Hz as it is supposed to?

    The “info” button provides the rate of the input signal not the refresh rate as you were told. The only way to really tell if you are getting 120 Hz is with a motion pattern test disc which are not generally available to the public.

    An alternative would be to switch off the 120 Hz either by a menu item on the TV if available, or if not selecting a mode that doesn’t use the 120 Hz which is “game mode” on most displays. If you see more motion blur in game mode vs cinema or movie (assuming there is no other control) then the display is 120 Hz.

    HD Guru

  • Big K

    I need help. which one would you purchase?

    Both are on samsungs and on-sale

    #1 65″ at 120 hz (not smart) $1,500

    #2 60″ at 240hz (smart, 3d) $2k

    We would need to know the model numbers .

    HD Guru

  • Emil

    Let’s summarize it then..Will my predator eye see/notice/recognize/feel the difference between Samsung 8000’s Clear Motion Rate of 960Hz or NOT, comparing with their 7550’s CMR of 840Hz?
    The same for the colors — The 8000’s offer 30mil:1 while the 7550’s delivers 23mil:1
    Will my eyes care about such a “huge” deviation or its impossible the ask them to find the difference?

  • Mark Rejhon

    I created a new FAQ item to my Scanning Backlight FAQ on my BlurBusters Blog:

    Q: What is Samsung CMR 960 or Sony Motionflow XR 960?

    These names represents a motion clarity equivalence to a “X fps @ X Hz” display. These proprietary names/trademarks are used by some existing HDTV’s with scanning backlights, and are sometimes viewed as marketing exaggerations by some reviewers. Measurements often show that they do not reflect real-world benchmarks (e.g. contrast ratio claims versus actual measurement).

    However, there’s a honest actual scientific basis behind these numbers (see Science & References). These motion equivalence factors are more honest in describing motion blur reduction (under certain conditions) than using “Hz” terminology. Science has shown that motion blur reduction is directly proportional to the length of impulses. Many scientific tests have shown that halving the length of strobe impulses per refresh, halve eye-tracking-based motion blur. Therefore, the shorter the strobe per refresh, and the longer the black period between refresh, the more motion blur reduction occurs. Motion equivalence factors are, in theory, directly comparable to each other on different displays, provided certain assumptions are followed.

    [Edit note: This is to equalize the purpose of CRT strobes and LCD strobes (For the proper kind of motion-blur-elimination scanning backlight). This is another interpretation of the exact same formula, that is actually much simpler, provided certain assumptions are followed. See below for a list]

    The formula is very simple:

    . . . motion equivalence factor = 1 / length of strobe

    The honesty of the formula, relative to actual measured science, assumes the following three:

    *** One impulse per display point (pixel) per refresh, similar to CRT.
    Actual number of backlight strobe impulses can sometimes be more than one per refresh on certain types of scanning backlights (misrepresented factor). Backlight diffusion between adjacent scanning backlight rows, can also lead to multiple impulses for a given pixel reaching the human retinas (unintentional factor). Such factors reduces measurable motion resolution, because multiple impulses are equivalent to repeated frames.

    *** Full frame-rate material (e.g. 60fps @ 60Hz, or 240fps @ 240Hz)
    No repeated frames in the material, because repeated frames leads to increased perceived motion blur caused by eye-tracking. Thus, scanning backlights reduces motion blur during 60fps video games and sports broadcasts (e.g. hockey, football, NASCAR, red bull air races) far more than film-based material (e.g. 24fps non-interpolated). For video games, the graphics must be fast enough to do full frame rate (e.g. 60fps not 30fps).

    *** Source material is not the limiting factor in motion blur
    Video taken with a slow shutter speed, often have built-in motion blur. Overcompressed video also have built-in blur, too. To ensure these are not limiting factors, the camera shutter speed must be faster at the source, than the length of the impulse at the destination display, and the video should not contain visible compression-related motion blur. For video games, artifical GPU motion blur effects should be disabled.

    How this applies to Samsung/Sony “960” displays: Many displays using a “960” equivalence uses 240Hz refresh, combined with a scanning backlight that’s dark 75% of the time. The LED impulse length is 1/960 of a second, with a period of darkness of 3/960 second between impulses (strobe duty cycle of 1/240 second). This results in (1/1/960) which produces a motion equivalence factor of 960. The purpose of also doing a high interpolated framerate (240fps) is triple fold: It allows more impulses per second without needing a brighter backlight; it reduces scanning backlight flicker (240 Hz flicker instead of 60 Hz flicker); and it reduces stroboscopic effects. Also, other factors above, affect actual perceived motion blur reduction, such as backlight diffusion between adjacent scanning backlight sections.

    How this applies to CRT: It is already well known that 60fps @ 60Hz on a CRT, have much clearer-looking motion than even 240fps @ 240Hz on a LCD. This formula explains why CRT has far less motion blur than LCD — a CRT display has approximately a 1 millisecond phosphor decay. Such a display has motion fluidity that looks the same, to human eyes, as “CMR 1000″ or “Motionflow XR 1000″, or a 1000fps@1000Hz display! No wonder CRT motion is so sharp, even at only 60Hz!

    Thanks,
    Mark Rejhon
    BlurBusters Blog

  • Pob

    Marketing will always do this sort of thing but you need some kind of scale to make it clear that one is better than the other.

    I test all the TV’s I sell with multiple motion test patterns and the higher ‘motion’ number TV’s nearly always look better at even a glance than the lower models.

    I don’t think the technicalities of this article strictly matter because whatever term it is that the manufacturer is using, it’s having the desired effect on performance. They could call it ‘super secret magic pro’ technology if they wanted to but if it reduced the problem of blur, it would be a job well done.

    The real big problem with all this processing on modern TV’s is the amount of latency it produces.

  • Rick

    Well I wish I had found this article BEFORE buying my Vizio 46″ 240 “SPS” tv in Jan ’12. I’ve been taken and probably can’t return the thing now. The refresh rate was an important criteria to me as I watch a lot of sports and events that involve fast motion. I put off buying HD for a long time because none that I saw were better and displaying moving images than the old CRT. Granted, still images and overall display qualities are better, but I really hate that motion blur that comes with HDTV and I’m almost at too high of altitude for plasma displays so I didn’t want to push it. Since I’ve had my Vizio tv, I kept thinking it didn’t look any better than the 120Hz tv’s I’ve seen but thought maybe it was my inability. Now I’m just pissed! I thought it interesting that the author mentioned “marketing” came up with these terms to deceive customers. I’m usually very sensitive to these tactics as I see it all the time in the IT industry where I work, but they got me on this one. Totally B.S.’d me and I fell for it. Well, as the saying goes “Screw me once, phooey on you. Screw me twice…”, there won’t be a 2nd time Vizio. Trust me.

  • Anakin

    I can’t speak of 240+ that the tv claim but 120hz is clearly better in viewing running text than 60hz.

  • Steve

    GREAT ARTICAL. As a salesman i appriciate you getting the information out there so when the customers come in, it’s not an uphill battle explaining to them that the number on the box and online are not correct.

  • Stringfellow

    @AWx

    From varying resources, such as HDGURU, I understood that setting the Panasonic to 96Hz allowed for the cleanest reproduction of 1080p content. This option was available on the VT30, and will be probably be available on the VT50 too. In addition, I also understood that Pioneer used 72Hz, which allowed for the best reproduction of 1080p content. Certain Panasonic sets only offer the 48Hz setting, but I have read that this creates issues when reproducing 1080p content. In Panasonic models with the 48Hz setting, the 60Hz setting worked better.

    Therefore, I have two questions:
    (1) Why does Panasonic not have a 72Hz setting?
    (2) How does the Panasonic 96Hz setting work based on your description/explanation?

  • AWx

    Panasonic now have a new “marketing number” : 2000Hz and 2500Hz Focused Field Drive.

    Let’s get back to Plasma 101.

    To a display an frame, Plasma do temporal dithering, also call sub-fields. Let’s say a pixel can either be black or lit. No intermediary shades of 50% lit. To achieve a 50% lit pixel, the plasma can blink this pixel. And this is exactly what it does with sub-fields : it blinks its pixels 600 times a second. For a 60Hz source material that’s 10 blinking. With binary pixels (white or black), it means you can display 2^10=1024 shades of gray.

    The problem is that to display your image, you need to wait for the whole 10 sub-fields so you only have an actual 60Hz frame rate. A perfect 60Hz with no motion blur but nothing above 60Hz. You can reduce the number of sub-fields, down to 5 for true 120Hz. However, this reduces your color accuracy: from 1024 shades of gray, your are down to only 2^5=32. However, if your pixel can ALSO display different shades of gray itself, you can retain accuracy. With black, white, 33% and 66% gray – 4 shades – you revert to 4^5=1024 shades of gray while retaining a perfect 120Hz refresh rate and no motion blur linked to image retention (since plasma have NO image retention).

    The problem is that it stills requires the full frame duration and all the intermediary sub-fields to display your image.

    So we have 600Hz subfields and pixel that support multiple shades of gray. You can combine those 2 facts in numerous technics. For example, to display a 50% gray, what the best ? Light your pixels at 50% gray on all frames ? Of light them at 100% on half the subfields ?
    You can add a third trick : your subfields can have various lengths. One can be very small, for very subtle shades while one can be very long. For example, it can be 1, 2, 4, 8, 16, …, 512. So for a 50% gray, just blink your pixel during the sub-field with a duration of 512. And if your image is only filled with 50% gray, you can display it in a single (rather long) subfield. You still have a 120Hz (with 5 subfields max) or 60Hz (with 10 subfields max) but your image is actually flashed on the screen during only one subfield ! Even less motion blur since frames are separated from each other by 4 to 9 fully black subfields. There no “last subfield” of previous image very close to the “first subfield” of the following image.

    Now image your pixels are very advanced and can display a whole palette of shades. With a single long subfield, you can display whole image with details, however limited to 50% brigthness.
    And now, your pixels are really really advanced and much brighter than you managed before. Instead of increasing the display overall brightness or reduce the power efficiency, you focused this increased brightness in your single subfield. You can display an image in a single subfield, with the same brightness and color accuracy a previous generation required numerous subfields to achieve.

    You now have what Panasonic calls Focused Field Drive.

    You still have 600Hz subfields. You still can display 60Hz or 120Hz true images (from an actual 60Hz or 120Hz or interpolated from a lower frame rate source). But now an image is displayed in a mere 0.4ms and not spread across multiple subfields that could span to the whole frame duration. 0.4ms is a long subfield : shorter subfields last only 0.005ms.

    In Panasonic 2012 lineup, your plasma will try to fit your image in a single 0.4ms sub-field, depending on its content, based on overall brightness and required color accuracy. They call this Focused Field Drive (FFD).

    For GT50 and VT50, you have a 0.4ms subfield giving a 2500Hz FFD. For ST50, you have a 0.5ms subfield giving a 2000Hz FFD. Those Hz are not linked to actual number of images displayed but to the panel reactivity.

    ST50, GT50 and VT50 are using the 15th generation panel from Panasonic. They claim to support 24576 shades (they call them “steps of gradation”, only 12286 for the ST50) while the 14th generation from 2011 in ST30/GT30/VT30 supported “only” 6144 shades.

  • keith

    Great article. Only correction is that BestBuy circular advertises Samsung CMR as 120Hz for a 60Hz television.

  • Stringfellow

    HDGURU,

    First, thank you times one-million. I really appreciated this article. It is a blessing to have someone who does the truth-checking.

    Secondly, not that it is a big deal, but in the paragraph that starts with “What about Plasma” (HDGURU knows this already, but for readers who are new or not familiar), LED and LCD should be listed as LCD or LED-LCD.

    For readers that are not familiar, HDGURU has plenty of information on their site to explain this, but I will summarize it here. LED is a type of light-source used in lighting a LCD panel. Traditionally, LCD panels were lit using CCFL as the source, but most manufacturers are now trending toward LED as their source (edge-lit or full-array).

    Thank you, again, HDGURU.

  • Caddy man

    In most cases, paying extra for anything higher than a “true” 120 Hz refresh rate is a waste of money. Most viewers will not be able to discern any difference. It is all a marketing scam. This is how manufacturers and retailers try to justify higher price tags, and thus greater profit margins.

  • JMax

    Gary,

    Maybe it’s time to put the companies to the TEST – TRUE MOTION RESOLUTION. A few years ago this was done – the results were very telling. Since there is an actual standard of measurement, maybe we could get a full chart with actual resolution of the sets. A major undergoing, I am sure, but someone needs to tell the complete truth. So, if companies are turning to a non-standard measurement, the question remains, does it really make a difference? Is the resolution improved or is it actually worse? Maybe you and your colleagues could band together to get the full truth out.

    Thank you for keeping people informed with all that you do.

  • chew

    Thanks hdguru for telling the truth,it was sell pitch anyway,i should not be surprise.

Leave a Comment