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post #91 of 904 Old 05-01-2014, 01:49 PM
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Thank you for the history lesson. I appreciate it.

 

However we can't make bets and we should look at this (Updated Apr 21, 2014) : http://www.rtings.com/info/fake-refresh-rates-samsung-clear-motion-rate-vs-sony-motionflow-vs-lg-trumotion

 

Toshiba ClearScan 240 = Real Refresh Rate 240 Hz

 

Toshiba Active Motion Rate of 400/800 or more = Real Refresh Rate 200 Hz

 

In Europe they are definitely 200Hz. Would 240Hz in the USA would make the sets that more difficult to make (or expensive) ?

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post #92 of 904 Old 05-01-2014, 02:12 PM
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Originally Posted by proyal View Post

Thank you for the history lesson. I appreciate it.

However we can't make bets and we should look at this (Updated Apr 21, 2014) : http://www.rtings.com/info/fake-refresh-rates-samsung-clear-motion-rate-vs-sony-motionflow-vs-lg-trumotion

Toshiba ClearScan 240 = Real Refresh Rate 240 Hz

Toshiba Active Motion Rate of 400/800 or more = Real Refresh Rate 200 Hz

In Europe they are definitely 200Hz. Would 240Hz in the USA would make the sets that more difficult to make (or expensive) ?

If you would read the manual you would see that it states it doubles the native refresh rate. Which is 120hz, or 100hz if you are in Europe.
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post #93 of 904 Old 05-01-2014, 02:24 PM
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Would you actually see a difference between 100Hz / 120Hz and a 200Hz / 240Hz if no content is actually running at that kind of FPS ?

 

Would it be better to have a 60Hz screen that uses software to make the image feel more fluid like it was shot in actual 60 or 120 or 240 fps ?

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post #94 of 904 Old 05-01-2014, 02:29 PM
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Originally Posted by proyal View Post

Thank you for the history lesson. I appreciate it.

However we can't make bets and we should look at this (Updated Apr 21, 2014) : http://www.rtings.com/info/fake-refresh-rates-samsung-clear-motion-rate-vs-sony-motionflow-vs-lg-trumotion

Toshiba ClearScan 240 = Real Refresh Rate 240 Hz

Toshiba Active Motion Rate of 400/800 or more = Real Refresh Rate 200 Hz

In Europe they are definitely 200Hz. Would 240Hz in the USA would make the sets that more difficult to make (or expensive) ?

The link to that site is appreciated. The sarcasm is not.

If Toshiba delivers a true 240Hz native refresh rate (and is one of the few honest vendors on that spec in the industry), great. But as Reagan used to say, "Trust, but Verify."

Among other things, a 200Hz native panel (240Hz here in the US) cannot support an action rate of 1500. The action rate needs to be a multiple of the native refresh rate. So despite what the 'rtings' website says, if this Toshiba TV really has an action rate of 1500, the native refresh rate of the LCD cannot be higher than 100Hz.

In answer to your last question, I am not aware of any cost delta or specific difficulty of slowing down a US/Japan x60Hz refresh rate TV to a 50x refresh rate TV for the European standard. It's not that they take a European TV and 'speed it up' for the US and Japan - they take a US/Japan TV and 'slow it down' for the EU.
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post #95 of 904 Old 05-01-2014, 02:35 PM
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Originally Posted by proyal View Post

Would you actually see a difference between 100Hz / 120Hz and a 200Hz / 240Hz if no content is actually running at that kind of FPS ?

Would it be better to have a 60Hz screen that uses software to make the image feel more fluid like it was shot in actual 60 or 120 or 240 fps ?

You've got it backwards. You need a panel with a higher native refresh rate like 120 or 240 Hz to use software to speed up the 6-Hz video input and display smoother motion. This is called frame interpolation and results in a smother motion effect some object to called the 'Soap Opera Effect' (SOE).

The other way to reduce motion blur without introducing the Soap Opera Effect is to reduce the persistence of the pixel 'ON' time. This requires a scanning backlight an is where action rate comes in. If I have a bright enough backlight with 4 scanning segments, I can light up each quarter of the image for only 1/4 of the total 16.7ms frame time. The result is that each pixel will be ON for only 4.2ms instead of 16.7ms reducing the motion blur by about a factor of 4 (similar to what the motion blur would be on an LCD with a 240Hz native refresh rate). This is called the Effective Refresh rate and it also dims the image by the corresponding amount (so the image is only 1/4 as bright in this example). That is the reason than effective scanning backlight should be especially bright (700 Nits of the L7400U qualifies - more than double the typical LED/LCD backlight brightness).
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post #96 of 904 Old 05-01-2014, 02:38 PM
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Among other things, a 200Hz native panel (240Hz here in the US) cannot support an action rate of 1500. The action rate needs to be a multiple of the native refresh rate. So despite what the 'rtings' website says, if this Toshiba TV really has an action rate of 1500, the native refresh rate of the LCD cannot be higher than 100Hz.
I wouldn't bet on that. You should see the fuzzy math Panasonic was using to claim a 4200 BLS rate on the WT60 LCD last year. They had all sorts of non-integer numbers in the formula like 1.41x
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post #97 of 904 Old 05-01-2014, 03:37 PM
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Originally Posted by fafrd View Post


You've got it backwards. You need a panel with a higher native refresh rate like 120 or 240 Hz to use software to speed up the 6-Hz video input and display smoother motion. This is called frame interpolation and results in a smother motion effect some object to called the 'Soap Opera Effect' (SOE).

The other way to reduce motion blur without introducing the Soap Opera Effect is to reduce the persistence of the pixel 'ON' time. This requires a scanning backlight an is where action rate comes in. If I have a bright enough backlight with 4 scanning segments, I can light up each quarter of the image for only 1/4 of the total 16.7ms frame time. The result is that each pixel will be ON for only 4.2ms instead of 16.7ms reducing the motion blur by about a factor of 4 (similar to what the motion blur would be on an LCD with a 240Hz native refresh rate). This is called the Effective Refresh rate and it also dims the image by the corresponding amount (so the image is only 1/4 as bright in this example). That is the reason than effective scanning backlight should be especially bright (700 Nits of the L7400U qualifies - more than double the typical LED/LCD backlight brightness).

No sarcasm was present. You interpreted wrongly the text.

 

Reviews will be up soon in May so we will see.

I say it's true 240 / 200 Hz panel.

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post #98 of 904 Old 05-01-2014, 03:40 PM
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I wouldn't bet on that. You should see the fuzzy math Panasonic was using to claim a 4200 BLS rate on the WT60 LCD last year. They had all sorts of non-integer numbers in the formula like 1.41x


Agree. The mathematics behind those numbers are always secret and strange.

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post #99 of 904 Old 05-01-2014, 03:45 PM
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Originally Posted by fafrd View Post

Among other things, a 200Hz native panel (240Hz here in the US) cannot support an action rate of 1500. The action rate needs to be a multiple of the native refresh rate. So despite what the 'rtings' website says, if this Toshiba TV really has an action rate of 1500, the native refresh rate of the LCD cannot be higher than 100Hz.
I wouldn't bet on that. You should see the fuzzy math Panasonic was using to claim a 4200 BLS rate on the WT60 LCD last year. They had all sorts of non-integer numbers in the formula like 1.41x

I'd like to see that if you have a link.

Look, these suppliers can always lie outright (though that generally carries some liability on their part), but in general, the meaning of action rate is pretty straightforward (while how it translates into Effective Refresh Rate and resulting pixel persistence is not).

Action Rate = the rate at which action is taken on the backlight in terms of turning on or off segments of LEDs. That means that the number of segments is usually a factor (or a simple equation related to the number of segments) as is the native refresh rate (since whatever is done, it needs to be done for each panel refresh).

In the case of AMR 1500, it has to be some factor of the native refresh rate. It cannot be '7.5 x 200Hz refresh rate' It can either be '15 x 100Hz refresh rate' or '30 x 50Hz refresh rate' There are no high-end panels that have native refresh rates of 50 Hz anymore. 100Hz is pretty much the mainstream native refresh rate at the high-end. So I'm betting the L7400U is based on a panel with a 100Hz native refresh rate and not only a 50Hz native refresh rate. In any case, it is not a 200Hz native refresh rate.

15 is a funny factor, since the factors are usually a multiple of 2. But it doesn't really matter. It just mean that 100 times a second, 15 actions are taken on the backlight meaning segments are turned on or off (or usually both - some turned on while others are turned off).

The 200Hz (240Hz) refresh rate is the Effective Refresh Rate, meaning that pixels are on for no more than 1/2 of the 100Hz native refresh rate. With an Action Rate of 1500, I expect this to mean that pixels are never left ON for more than 7/15th of the full 10ms refresh time, meaning 4.7ms, meaning an effective refresh rate of 214Hz with a light output reduced from 700 Nits to 327 Nits.

Hopefully in some dark viewing setting, pixel persistence can be decreased even further for even less motion blur. At 5/15th the effective refresh rate would be increased 300Hz and the light output reduced to 233 (still more than bright enough for dark-room viewing) and at 3/15th the effective refresh rate would be increased to 500Hz and the light output reduced to 140 Nits (still bright enough for dark-room viewing).

The Panasonic WT60 claims an action rate of 4200Hz, a 16-segment scanning backlight, and an effective refresh rate of 240Hz (considered by that same website to be a 240Hz native refresh panel). 4200 does not divide evenly by 240 (17.5) while it does divide evenly by 120 (35) so the LCD panel has a native refresh rate of 120Hz, not 240Hz (despite what that website says).

So in the case of the WT60, backlight segments are controlled 35 times for each refresh.

To deliver an effective refresh rate of 240Hz, this panel cannot leave pixels on for any more than 17/35th of the time. That would result in pixel persistence of 4.05ms for en Effective Refresh Rate of 247Hz (and a backlight brightness reduction of 51.4%.

The backlight has 16 segments, so they probably use 16 action cycles to scan in the image a segment at a time and another 16 cycles to scan it back out. The additional 3 cycles are all OFF to allow for more time for refresh, or one is left with the entire panel ON and the other two are left for the entire panel OFF. Either way they would end up with 16/35 or 17/35 persistence which would deliver a true Effective Refresh Rate of >240Hz.

I have no idea what 1.41x could be a reference to.
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post #100 of 904 Old 05-01-2014, 04:11 PM
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Quote:
Originally Posted by proyal View Post

Quote:
Quote:
Originally Posted by fafrd View Post

You've got it backwards. You need a panel with a higher native refresh rate like 120 or 240 Hz to use software to speed up the 6-Hz video input and display smoother motion. This is called frame interpolation and results in a smother motion effect some object to called the 'Soap Opera Effect' (SOE).


The other way to reduce motion blur without introducing the Soap Opera Effect is to reduce the persistence of the pixel 'ON' time. This requires a scanning backlight an is where action rate comes in. If I have a bright enough backlight with 4 scanning segments, I can light up each quarter of the image for only 1/4 of the total 16.7ms frame time. The result is that each pixel will be ON for only 4.2ms instead of 16.7ms reducing the motion blur by about a factor of 4 (similar to what the motion blur would be on an LCD with a 240Hz native refresh rate). This is called the Effective Refresh rate and it also dims the image by the corresponding amount (so the image is only 1/4 as bright in this example). That is the reason than effective scanning backlight should be especially bright (700 Nits of the L7400U qualifies - more than double the typical LED/LCD backlight brightness).
No sarcasm was present. You interpreted wrongly the text.

Reviews will be up soon in May so we will see.
I say it's true 240 / 200 Hz panel.

My apologies then. Because you provided a link that contradicted the information of the CNET article I had found, I thought your reference to 'history lesson' was a sarcastic way of saying my information was out of date.

I value an active exchange and for sure, these TV vendors make all of this stuff as difficult to understand as they can.

I believe that in both the cases of Toshiba and Panasonic, at least, the rtings.com website is incorrect. Action Rate (or whatever the various vendors want to call it) must be an integer factor of native refresh rate. 3 months ago I was confused on this point as well. Rogo corrected me as I was attempting to understand the BLS technology of the Vizio Reference Series (also 15x, like the L7400U) so I'm just trying to keep the vendors honest.

And many of the reviewers do not understand this issue of refresh rate correctly either (witness rtings.com). The only way to truly test the native refresh rate of a panel is to feed it video at the target refresh rate and there are not any 240Hz video sources readily available. With a high-speed camera, they could measure whether backlight scanning is still active even in default mode, but they never do. The vendors consider 1/maximum-pixel-persistence to be the refresh rate, but it is not - that is the effective refresh rate. Vizio is more honest than most in this regard (at least in some places). If your panel cannot accept and display a new video frame 240 times a second, it is not a 'true' 240 Hz panel (though it does have an Effective Refresh Rate of 240Hz).

One way to measure the true native refresh rate of the panel is through the amount of motion interpolation supported. If a TV only supports an optional 1 frame of interpolation, it is only able to display distinct frames up to a maximum rate of 60x2 = 120Hz. If the TV support up to 3 frames of motion interpolation, it is able to display distinct frames up to a maximum of 6x4 =240Hz.

From that point of view, the Sony MotionFlow 960 is usually based on a true 240Hz LCD panel. It combines x3 motion interpolation with a 4-segment scanning backlight with an action rate of 960Hz.


Follow this link down to the description with picture of MotionFlow 800 (960 here in the US):http://www.sony-asia.com/microsite/bravia/led-backlit-lcd-tv-picture-quality.html

Doing that (3-frame motion interpolation) requires an LCD with a native refresh rate of 200Hz (240Hz here in the US). And in that case the Action rate will be an integer factor of the native refresh rate (4X in the case of MotionFlow 800/940).
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post #101 of 904 Old 05-01-2014, 04:32 PM
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I'd like to see that if you have a link.
Sure, the slide is in a YouTube video from the VE 2013 shoot-out where the Panasonic rep was giving his presentation. link

I did make a mistake though. It's 1.43x
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post #102 of 904 Old 05-01-2014, 05:21 PM
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I'd like to see that if you have a link.
Sure, the slide is in a YouTube video from the VE 2013 shoot-out where the Panasonic rep was giving his presentation. link

I did make a mistake though. It's 1.43x

Well I have to say you are right - that is the biggest bunch of malarkey I have ever seen!

They show 3 interpolated frames which implies a true 240Hz refresh panel.

They show an 8-segment scanning backlight versus their website which refers to '16 segments' but then they say '8 on each side' It's edge-lit, so at least that mystery can be more or less solved.

So most anyone else would call that an action rate of 1920Hz.

But then they give themselves an effective factor of 1.04X because of their fast refresh speed, another factor of 1.43x because of their backlight scanning speed and another factor of 1.49 because of their Black Insertion Length. All of which brings 1920 up to over 4200.

Whatever respect I may have ever had for Panasonic LCD, this presentation has destroyed it! Maybe they purposely spewed hokum to undermine the entire LED/LCD industry in defense of their plasma business.
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post #103 of 904 Old 05-01-2014, 06:14 PM
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Well I have to say you are right - that is the biggest bunch of malarkey I have ever seen!

They show 3 interpolated frames which implies a true 240Hz refresh panel.

They show an 8-segment scanning backlight versus their website which refers to '16 segments' but then they say '8 on each side' It's edge-lit, so at least that mystery can be more or less solved.

So most anyone else would call that an action rate of 1920Hz.

But then they give themselves an effective factor of 1.04X because of their fast refresh speed, another factor of 1.43x because of their backlight scanning speed and another factor of 1.49 because of their Black Insertion Length. All of which brings 1920 up to over 4200.

Whatever respect I may have ever had for Panasonic LCD, this presentation has destroyed it! Maybe they purposely spewed hokum to undermine the entire LED/LCD industry in defense of their plasma business.
I suspect other companies are playing just as fast and loose with their equivalent numbers and ratings. I wouldn't put too much faith in them or trying to back facts out of the numbers.
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post #104 of 904 Old 05-02-2014, 12:07 AM
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Even avjunkey (a Panasonic employee) on hdtvjunkie site is bashing Panasonic and is searching to move to another company. He said they fired people and closed factories to get to profit instead of correcting their mistakes and errors. Typical of big corporations.

 

Now : http://arstechnica.com/civis/viewtopic.php?p=26049695&sid=6d6da3c53a885369bf6ac0bae689b6b8#p26049695

 

* L9400 series for 4K, 58" and 65", "Radiance" panel, 10-bit, 240Hz, full-array LED backlight, HDMI 2.0, H.265.
* L9450, 84" only, lacks the "Radiance" panel.
* L8400, 58" only, lacks the "Radiance" panel and full-array LED back-light, 120hz.
* L7400 for regular HDTV (1080p), 55" only, "Radiance" panel, 240Hz, full-array LED backlight.
* L5400 for regular HDTV (1080p), 58" and 65" sizes, 240Hz.

 

http://hdguru.com/toshiba-2014-uhdtv-and-hdtv-lineup-unveiled/

 

According to all info even the L5400 will come with a 240HZ panel.

 

Toshiba really needed a reboot in their TV business and this may be their way of winning market share. Of course these could be false numbers but Toshiba usually didn't lie about numbers on the scale that other companies did, not to mention that it gives static contrast in specifications too.

 

Here some videos : http://forums.hdtvtest.co.uk/index.php?topic=8295.msg40443#msg40443

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post #105 of 904 Old 05-02-2014, 05:31 AM
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What about monitors, why do they come in 60Hz / 120Hz in both EU and USA ?

Isn't there a problem with avoiding noticeable beating/flicker there too ? ( some of them are indeed flicker free now a.k.a PWM free, but not sure if it's the same thing )

 

Found another confirmation from a french publication :

 

http://translate.google.com/translate?hl=en&sl=fr&u=http://www.hdfever.fr/2014/03/12/toshiba-l54/&prev=/search%3Fq%3Dhttp://www.hdfever.fr/2014/03/12/toshiba-l54/%26client%3Dfirefox-beta%26hs%3D3nY%26rls%3Dorg.mozilla:en-US:official%26channel%3Dsb

 

L5400 is 100/120Hz native

  • TOSHIBA 40L5435DG: € 599.00
  • TOSHIBA 48L5435DG: € 799.00

 

http://translate.google.com/translate?hl=en&sl=fr&u=http://www.hdfever.fr/2014/03/12/toshiba-l74/&prev=/search%3Fq%3Dhttp://www.hdfever.fr/2014/03/12/toshiba-l74/%26client%3Dfirefox-beta%26hs%3DvTt%26rls%3Dorg.mozilla:en-US:official%26channel%3Dsb

 

L7400 is 200/240Hz native

  • TOSHIBA 55L7453DG: € 1,299
  • TOSHIBA 47L7453DG: 999 €
  • TOSHIBA 42L7453DG: € 799

 

The speakers are of course reworked too.


The 4k sets however i have a doubt they can make them over 60Hz or maximum 120Hz.

Rec. 2020 is maximum 120Hz and i doubt these 4k are 100% rec 2020 compatible.

 

http://en.wikipedia.org/wiki/Rec._2020#Frame_rate

Also a very good read : http://www.tftcentral.co.uk/articles/pointers_gamut.htm

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post #106 of 904 Old 05-02-2014, 08:26 AM
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Direct Motion 120 for J8

Direct Motion 480 for Z8

 

Even if they use true 120Hz panel it is very important if the panel itself has fast response time like the Sony sets this year.

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post #107 of 904 Old 05-02-2014, 02:52 PM
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What about monitors, why do they come in 60Hz / 120Hz in both EU and USA ?
Isn't there a problem with avoiding noticeable beating/flicker there too ? ( some of them are indeed flicker free now a.k.a PWM free, but not sure if it's the same thing )
TFT LCDs are sample and hold displays. They don't inherently flicker. If the backlight PWM frequency (used for dimming) is close enough to a multiple of 60Hz you might get some flickering effects under the right conditions. Especially if the panel is 6 bits + FRC.
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Originally Posted by proyal View Post

What about monitors, why do they come in 60Hz / 120Hz in both EU and USA ?
Isn't there a problem with avoiding noticeable beating/flicker there too ? ( some of them are indeed flicker free now a.k.a PWM free, but not sure if it's the same thing )
FTF LCDs are sample and hold displays. They don't inherently flicker. If the backlight PWM frequency (used for dimming) is close enough to a multiple of 60Hz you might get some flickering effects under the right conditions. Especially if the panel is 6 bits + FRC.

TFT??

If you start strobing the backlight, I think you are back to needing to do so at some multiple of power grid frequency or you will see beating / flicker.
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post #109 of 904 Old 05-02-2014, 03:11 PM
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TFT??

If you start strobing the backlight, I think you are back to needing to do so at some multiple of power grid frequency or you will see beating / flicker.
Yes, TFT.

It depends on a large number of factors. Beating between what? Fluorescent lights and the backlight?

You're not going to get beating between the display and the backlight in a dark room. You can either move the backlight PWM frequency way higher than 60Hz. Or you can make it a multiple of 60Hz and sync it to the panel refresh.
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post #110 of 904 Old 05-02-2014, 03:27 PM
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TFT??

If you start strobing the backlight, I think you are back to needing to do so at some multiple of power grid frequency or you will see beating / flicker.
Yes, TFT.

It depends on a large number of factors. Beating between what? Fluorescent lights and the backlight?

You're not going to get beating between the display and the backlight in a dark room. You can either move the backlight PWM frequency way higher than 60Hz. Or you can make it a multiple of 60Hz and sync it to the panel refresh.

Yeah, beating with any light source that varies in intensity with the power grid AC frequency. Incandescent lights are now a thing of the past but I'm not sure whether there is any variation in 120V AC LED light output.

Of course you are right, in the dark there can't be any beating.

But to avoid any possibility of beating in an uncontrolled light situation, they are probably going to keep backlight strobing to a multiple of the LCD panel refresh rate which is going to stay a multiple of power grid frequency as far as the eye can see.

I was in Costco recently and under the bright florescents, one of the LED/LCDs I was staring at gave me a very weird beating-like visual effect that I found very disorienting and gave me a headache. Not sure what was going on since I could not control the set, but it might have been a European panel making its way here to the US. Whatever it was, it was very disturbing and I am pretty sure the bright florescent of the environment were a key contributing factor.
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post #111 of 904 Old 05-03-2014, 12:50 AM
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I still haven't found a flicker free TV unfortunately.

Only monitors : http://www.tftcentral.co.uk/articles/flicker_free_database.htm

 

I can confirm that In many Television sets like fafrd said the combination of PWM with software frame insertion and LED light of the panel leads to severe flickering of the screen like CRT style. Really giving headaches.

 

http://www.tftcentral.co.uk/advanced.htm (see Motion Interpolation 120Hz+)

 

If only we could get our hands on a flicker free TV this year.

 

http://www.tftcentral.co.uk/articles/pulse_width_modulation.htm

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post #112 of 904 Old 05-03-2014, 08:29 AM
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I am definitely not paying the premium Samsung, Sony, Panasonic, Sharp, LG are asking for their TV sets (brand name) in Europe.

Toshiba is very aggressive with their pricing policy like Vizio in USA.

 

I am looking for a 55" this year to replace a last generation 27" Samsung CRT. Hope it gets great reviews. Still very curios how may dimming zones does the 42", 47" and the 55" have. Probably more zones as the TV set becomes larger ?

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post #113 of 904 Old 05-04-2014, 02:28 AM
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One more thing, this TV is a direct LED with local dimming...that means it will have excellent screen uniformity (Backlight Uniformity) right ?

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post #114 of 904 Old 05-04-2014, 04:57 AM
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One more thing, this TV is a direct LED with local dimming...that means it will have excellent screen uniformity (Backlight Uniformity) right ?
Yes, it should have excellent backlight uniformity and no flashlighting.
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post #115 of 904 Old 05-04-2014, 05:21 AM
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I'd like to see that if you have a link.

Look, these suppliers can always lie outright (though that generally carries some liability on their part), but in general, the meaning of action rate is pretty straightforward (while how it translates into Effective Refresh Rate and resulting pixel persistence is not).

Action Rate = the rate at which action is taken on the backlight in terms of turning on or off segments of LEDs. That means that the number of segments is usually a factor (or a simple equation related to the number of segments) as is the native refresh rate (since whatever is done, it needs to be done for each panel refresh).

In the case of AMR 1500, it has to be some factor of the native refresh rate. It cannot be '7.5 x 200Hz refresh rate' It can either be '15 x 100Hz refresh rate' or '30 x 50Hz refresh rate' There are no high-end panels that have native refresh rates of 50 Hz anymore. 100Hz is pretty much the mainstream native refresh rate at the high-end. So I'm betting the L7400U is based on a panel with a 100Hz native refresh rate and not only a 50Hz native refresh rate. In any case, it is not a 200Hz native refresh rate.

15 is a funny factor, since the factors are usually a multiple of 2. But it doesn't really matter. It just mean that 100 times a second, 15 actions are taken on the backlight meaning segments are turned on or off (or usually both - some turned on while others are turned off).

The 200Hz (240Hz) refresh rate is the Effective Refresh Rate, meaning that pixels are on for no more than 1/2 of the 100Hz native refresh rate. With an Action Rate of 1500, I expect this to mean that pixels are never left ON for more than 7/15th of the full 10ms refresh time, meaning 4.7ms, meaning an effective refresh rate of 214Hz with a light output reduced from 700 Nits to 327 Nits.

Hopefully in some dark viewing setting, pixel persistence can be decreased even further for even less motion blur. At 5/15th the effective refresh rate would be increased 300Hz and the light output reduced to 233 (still more than bright enough for dark-room viewing) and at 3/15th the effective refresh rate would be increased to 500Hz and the light output reduced to 140 Nits (still bright enough for dark-room viewing).

The Panasonic WT60 claims an action rate of 4200Hz, a 16-segment scanning backlight, and an effective refresh rate of 240Hz (considered by that same website to be a 240Hz native refresh panel). 4200 does not divide evenly by 240 (17.5) while it does divide evenly by 120 (35) so the LCD panel has a native refresh rate of 120Hz, not 240Hz (despite what that website says).

So in the case of the WT60, backlight segments are controlled 35 times for each refresh.

To deliver an effective refresh rate of 240Hz, this panel cannot leave pixels on for any more than 17/35th of the time. That would result in pixel persistence of 4.05ms for en Effective Refresh Rate of 247Hz (and a backlight brightness reduction of 51.4%.

The backlight has 16 segments, so they probably use 16 action cycles to scan in the image a segment at a time and another 16 cycles to scan it back out. The additional 3 cycles are all OFF to allow for more time for refresh, or one is left with the entire panel ON and the other two are left for the entire panel OFF. Either way they would end up with 16/35 or 17/35 persistence which would deliver a true Effective Refresh Rate of >240Hz.

I have no idea what 1.41x could be a reference to.
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post #116 of 904 Old 05-04-2014, 02:12 PM
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Originally Posted by fafrd View Post

I'd like to see that if you have a link.

Look, these suppliers can always lie outright (though that generally carries some liability on their part), but in general, the meaning of action rate is pretty straightforward (while how it translates into Effective Refresh Rate and resulting pixel persistence is not).

Action Rate = the rate at which action is taken on the backlight in terms of turning on or off segments of LEDs. That means that the number of segments is usually a factor (or a simple equation related to the number of segments) as is the native refresh rate (since whatever is done, it needs to be done for each panel refresh).

In the case of AMR 1500, it has to be some factor of the native refresh rate. It cannot be '7.5 x 200Hz refresh rate' It can either be '15 x 100Hz refresh rate' or '30 x 50Hz refresh rate' There are no high-end panels that have native refresh rates of 50 Hz anymore. 100Hz is pretty much the mainstream native refresh rate at the high-end. So I'm betting the L7400U is based on a panel with a 100Hz native refresh rate and not only a 50Hz native refresh rate. In any case, it is not a 200Hz native refresh rate.

15 is a funny factor, since the factors are usually a multiple of 2. But it doesn't really matter. It just mean that 100 times a second, 15 actions are taken on the backlight meaning segments are turned on or off (or usually both - some turned on while others are turned off).

The 200Hz (240Hz) refresh rate is the Effective Refresh Rate, meaning that pixels are on for no more than 1/2 of the 100Hz native refresh rate. With an Action Rate of 1500, I expect this to mean that pixels are never left ON for more than 7/15th of the full 10ms refresh time, meaning 4.7ms, meaning an effective refresh rate of 214Hz with a light output reduced from 700 Nits to 327 Nits.

Hopefully in some dark viewing setting, pixel persistence can be decreased even further for even less motion blur. At 5/15th the effective refresh rate would be increased 300Hz and the light output reduced to 233 (still more than bright enough for dark-room viewing) and at 3/15th the effective refresh rate would be increased to 500Hz and the light output reduced to 140 Nits (still bright enough for dark-room viewing).

The Panasonic WT60 claims an action rate of 4200Hz, a 16-segment scanning backlight, and an effective refresh rate of 240Hz (considered by that same website to be a 240Hz native refresh panel). 4200 does not divide evenly by 240 (17.5) while it does divide evenly by 120 (35) so the LCD panel has a native refresh rate of 120Hz, not 240Hz (despite what that website says).

So in the case of the WT60, backlight segments are controlled 35 times for each refresh.

To deliver an effective refresh rate of 240Hz, this panel cannot leave pixels on for any more than 17/35th of the time. That would result in pixel persistence of 4.05ms for en Effective Refresh Rate of 247Hz (and a backlight brightness reduction of 51.4%.

The backlight has 16 segments, so they probably use 16 action cycles to scan in the image a segment at a time and another 16 cycles to scan it back out. The additional 3 cycles are all OFF to allow for more time for refresh, or one is left with the entire panel ON and the other two are left for the entire panel OFF. Either way they would end up with 16/35 or 17/35 persistence which would deliver a true Effective Refresh Rate of >240Hz.

I have no idea what 1.41x could be a reference to.
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You crack me up biggrin.gif

Hey did I see in the G thread that you picked up a 2014 LG? How do you like it? They all say 'LED Backlight' - do you believe your set is edge-lit or back-lit (direct of full-array)??
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post #117 of 904 Old 05-06-2014, 07:25 AM
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Will H.265 be any help for 1080p ? In order to make full HD available in countries that are behind the adoption curve ?

 

The L7400 comes with H.264 it seems. Does that mean it won't support H.265 ?

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post #118 of 904 Old 05-06-2014, 07:31 AM
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"Toshiba's flagship for 2014 is the L9400, available in 58-, 65-, and 84-inch iterations. This UHD TV utilizes a 240 Hz refresh rate"

 

"...the L8400 ... It does not, however, make use of the Radiance panel design. The L8400 is capped at a 120 Hz refresh rate, as well."

 

"Both UHD TVs are H.265 HEVC (High Efficiency Video Coding) and HDCP 2.2 compliant."

 

"The L7400 and L5400 both feature 240 Hz panels."

 

Read more in the link : http://televisions.reviewed.com/news/toshiba-puts-uhd-front-and-center-in-2014-tv-lineup

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post #119 of 904 Old 05-06-2014, 08:26 AM
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Will H.265 be any help for 1080p ? In order to make full HD available in countries that are behind the adoption curve ?
Theoretically once the encoders mature it should allow the same 1080p quality as H.264 at about half the bitrate. So, it could be of some benefit for streaming.
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The L7400 comes with H.264 it seems. Does that mean it won't support H.265 ?
Hard to say, but if it was going to have HEVC/H.265 support I think they would advertise that.
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post #120 of 904 Old 05-06-2014, 08:40 AM
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I am looking forward to people who begin to see these sets post their first impression. I called a PC Richards facility and they confirmed the 55L7400 units are at their stores. Unfortunately the store I called didn't have them set up on display yet... not to mention that I don't live close to the store to go and see one first hand.
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