Blur Busters Forums

thatoneguy wrote: ↑

23 Jul 2024, 05:40

Well yeah, but 50hz Plasma is still better than sample-and-hold.

Not anymore, for 360Hz+ OLEDs. On average, the 360Hz OLED sample and hold now outperforms plasma. The red/green phosphor has about 3ms persistence, creating the characteristic yellow ghosting.

thatoneguy wrote: ↑

23 Jul 2024, 05:40

And even most PAL 50hz CRTs used slower phosphors on average compared to their NTSC 60hz counterparts to combat flicker. I would say many Consumer CRT TVs had 4-5ms MPRT phosphors, about similar to Plasma but a bit better because of less trail.

Remember, phosphor persistence is generally measured to 90% fade, much like LCD GtG, so it is much less than 4-5ms MPRT. MPRT 1ms is very easy to achieve on an average CRT monitor. The 4-5ms numbers requires citation, as phosphor is a fade curve, and arbitrary MPRT cutoff points apply here (10%-90%) due to oscilloscope noise floors.

Chief Blur Buster wrote: ↑

24 Jul 2024, 00:37

Not anymore, for 360Hz+ OLEDs. On average, the 360Hz OLED sample and hold now outperforms plasma. The red/green phosphor has about 3ms persistence, creating the characteristic yellow ghosting.

I meant that 50hz Plasma > 50hz Sample and Hold

Chief Blur Buster wrote: ↑

24 Jul 2024, 00:37

Remember, phosphor persistence is generally measured to 90% fade, much like LCD GtG, so it is much less than 4-5ms MPRT. MPRT 1ms is very easy to achieve on an average CRT monitor. The 4-5ms numbers requires citation, as phosphor is a fade curve, and arbitrary MPRT cutoff points apply here (10%-90%) due to oscilloscope noise floors.

I’ve seen plenty of PAL CRT TVs so I know. Their motion was decent but not outstanding.
This doesn’t really apply to monitors, but for CRT TVs they usually had slower phosphor even in some NTSC sets.
People wonder how PAL region users were able to tolerate 50hz but in reality most of them simply used slower phosphors.

As in the human eye, an important property of the CRT phosphor is its persistence. The persistence of the phosphor layer is described as the duration of the luminance after the electron bombardment has stopped. Since the light produced does not disappear abruptly, but decreases slowly, persistence is measured until the time when the luminance produced decreases to 1% of its initial value. Phosphor persistence is a useful feature because it helps minimize the flicker, but it should not be longer in duration than the TV frame duration (40 ms) as we want reproduction of dynamic images whose movements would be blurred if the persistence were too long. The persistence of the majority of CRTs used these days is around 5 ms. This is a bit more complicated with color CRT monitors since not all the phosphors have the same persistence (the blue phosphor has the shortest), but they are all around 5 ms.

Apart from the persistence, other important properties of the phosphor used in TV monitors are efficiency and spectral characteristics.

Vlado Damjanovski, in CCTV (Third Edition), 2014

https://www.sciencedirect.com/topics/co ... phor-layer

BTW: Check my previous post in the LG 1440p 480hz OLED thread

thatoneguy wrote: ↑

24 Jul 2024, 01:23

I meant that 50hz Plasma > 50hz Sample and Hold

Oh, no argument there.

thatoneguy wrote: ↑

24 Jul 2024, 01:23

I’ve seen plenty of PAL CRT TVs so I know. Their motion was decent but not outstanding.

As in the human eye, an important property of the CRT phosphor is its persistence. The persistence of the phosphor layer is described as the duration of the luminance after the electron bombardment has stopped. Since the light produced does not disappear abruptly, but decreases slowly, persistence is measured until the time when the luminance produced decreases to 1% of its initial value. Phosphor persistence is a useful feature because it helps minimize the flicker, but it should not be longer in duration than the TV frame duration (40 ms) as we want reproduction of dynamic images whose movements would be blurred if the persistence were too long. The persistence of the majority of CRTs used these days is around 5 ms. This is a bit more complicated with color CRT monitors since not all the phosphors have the same persistence (the blue phosphor has the shortest), but they are all around 5 ms.

Apart from the persistence, other important properties of the phosphor used in TV monitors are efficiency and spectral characteristics.

Oh right.

Yes, 50Hz PAL TVs intentionally had slower persistence phosphors to make the flicker more tolerable. Good to be reminded. D'oh.

Also, I knew early NTSC TVs (e.g. 1950s color TVs) had high phosphor persistence, but I didn't know that persistence was kept high for a long time with PAL.

On CRT TV PAL since ~1980 until ~2010, the vertical bar/line is more (not motion) blur than horizontal. But the difference of motion blur between freeze and ultra fast *horizontally* motion by eyes pursuit is almost none.

Chief Blur Buster wrote: ↑

07 Aug 2024, 12:54

Yes, 50Hz PAL TVs intentionally had slower persistence phosphors to make the flicker more tolerable. Good to be reminded. D'oh.

Also, I knew early NTSC TVs (e.g. 1950s color TVs) had high phosphor persistence, but I didn't know that persistence was kept high for a long time with PAL.

Pretty sure it varied from brand to brand, from model to model.
I would assume at least that sets that had NTSC encoders on them(like many Sony Trinitrons) used the faster phosphors

That said I have heard from other Euros and Australians/PAL Users that 50hz flicker bothered them back in the day, but who knows what kind of CRTs they had.
We had a couple of sets in my home: a 20 inch Panasonic, a 26 inch or so Sony which was a beast and another 20-ish inch or so no-brand CRT, and also saw countless others at friends' homes, when I visited relatives etc.
Never had problems with flicker but I don't remember being blown away from their motion clarity either.
Maybe that's because I had no concept of motion clarity back then and didn't pay attention but... all I remember is that they weren't as blurry as sample-and-hold LCD but otoh I have no recollection of them having silky smooth crystal clear motion either.

I know for a fact that they put slower phosphors on many CRT TVs be it NTSC or PAL to combat broadcast 480i60/576i50 interlace flicker and obviously the PAL variants had to be even slower than the NTSC ones.
Some companies apparently eventually introduced 100hz sets but personally I don't remember seeing them in stores.

No matter how slow the persistence of a CRT phosphor, it still fades immediately after illumination, a cool-off period.

It's just a matter of how much flickerdepth you get with a 50Hz CRT. Even incandescent light bulbs flickered by about 5% - but the flicker depth was slightly higher in Europe countries. I've seen published data that showed lightbulbs flickered by a slight 6.5% dimming in between the brightness peaks, in relation to the AC crossing events (100 crossing events for 50Hz AC). That's the filament cooling off to the AC electricity (voltages follows a sinewave).

So longer persistence phosphors is less bothersome, just does not fully fix flicker. I'm not sure how deep the dimming was between refresh cycles, but it definitely couldn't stay at 100% illumination in between the raster scans.

^
Well, if we look at it that way then I suppose even a 120hz CRT doesn't technically fully fix flicker either
I'm not that knowledgeable about CRT phosphors, beyond the basics of persistence.
I know that there are some really long-persistence they used for terminals which apparently were so long persistence they never flickered, or so I've heard.

Never noticed any flicker with incandescent lights either, and to this day I still don't notice it whatsoever.
Whatever the case may be, the relatively longer phosphor persistence used in many (PAL or NTSC)consumer sets is probably enough to lessen the flicker enough to where it isn't as noticeable, at the expense of worse motion clarity of course but still.

thatoneguy wrote: ↑

11 Aug 2024, 20:15

^
Well, if we look at it that way then I suppose even a 120hz CRT doesn't technically fully fix flicker either
I'm not that knowledgeable about CRT phosphors, beyond the basics of persistence.
I know that there are some really long-persistence they used for terminals which apparently were so long persistence they never flickered, or so I've heard.

Never noticed any flicker with incandescent lights either, and to this day I still don't notice it whatsoever.
Whatever the case may be, the relatively longer phosphor persistence used in many (PAL or NTSC)consumer sets is probably enough to lessen the flicker enough to where it isn't as noticeable, at the expense of worse motion clarity of course but still.

TV CRT phosphor decay in slow motion:

https://www.youtube.com/watch?v=2czqYV3T_Kc

https://www.youtube.com/watch?v=6WOEgOX1E3c

Every CRT monitor I've ever owned clearly had faster decay, because even 60Hz would flicker very noticeably, while my 50Hz TVs were flickering much less. On the monitors, 100Hz looked about the same when it comes to flicker as the 50Hz TVs.

^
Yup, that checks out.
PC(or Broadcast/Pro) Monitors used faster phosphors, probably to reduce possibility of burn-in.
With TVs that wasn't as much of a concern for PC useage and such so brighter less flickery screens were preferred.