[l'pc]

Hello,

So I was looking around for computer monitors and found there were no computer monitors which featured an plasma (or oled) panel. They all seem to use LCD panels, either TN or some variant of IPS, even with high-end computer monitors.

Any idea why this is so ? I imagine it could be difficult to manufacture 23" plasma's for 100-300€, which I suppose is the segment which sells most, but isn't it possible to sell a 27" to 32" plasma at 600-800$ (even at 1080p) ? It is possible to market plasma TV with the same price and specs (but 60" of course.)

Is there a technical difficulty to manufacture smaller displays ? Or something else I have overlooked ?

Have a nice day !
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For Mods : Is there a reason why I can't post a new thread in the "Off Topic" subforum ? I intended to post this thread over there but got a permission error.

[peregrine]

The days of PDP (plasma display panel) are being numbered; most of the major companies are stopping the production. OLED production on the other hand, is still in its early days. They haven't reached the economical scale necessary to be competitive against LCD, hence the high prices.

With that aside, you definitely wouldn't want to use PDP as a computer monitor. Search for "plasma retention".

[PatK]

Here's a nice one.. and found a good article on displays yet to come

Plasma displays have issues with image retention and burn in, OLED's are just starting to come on stream, give them another few years to mature.

[noggin]

Hello,

So I was looking around for computer monitors and found there were no computer monitors which featured an plasma (or oled) panel. They all seem to use LCD panels, either TN or some variant of IPS, even with high-end computer monitors.

Any idea why this is so ? I imagine it could be difficult to manufacture 23" plasma's for 100-300€, which I suppose is the segment which sells most, but isn't it possible to sell a 27" to 32" plasma at 600-800$ (even at 1080p) ? It is possible to market plasma TV with the same price and specs (but 60" of course.)

Is there a technical difficulty to manufacture smaller displays ? Or something else I have overlooked ?

Yes - constructing small plasmas is tricky. It is an inherent limitation in their technology, as each RGB pixel is effectively a sealed cell of gas with electrodes that need to be fired. The smallest plasma I can remember was a 32" 4:3 Fujitsu made in the 90s, which was probably 640x480 resolution. For higher resolutions and/or smaller screen sizes you need even smaller pixels, which are very difficult to manufacture in volume. This is why plasmas were initially often lower resolution than similar sized LCDs (Full HD 1080p resolution LCDs were available earlier at a lower price point than 1920x1080 Plasmas, which were often still at nearer 720p resolution) Imagine trying to produce a 40" 3840x2160 plasma - where each cell is 1/4 the size of a Full HD display at that screen size, and having to ensure every single sub-pixel is sealed and has the correct amount of ionised gas in it. That's not easy. Or cheap.

I have seen a prototype 7680x4160 (i.e. 8K) SuperHiVision plasma, but it was 103" (2.6m) diagonal, and I suspect VERY expensive.

Plasma manufacture has all but ceased globally as LCDs offer a route to low-cost 4K that Plasma doesn't.

For PC use, image retention and burn-in (imagine the Windows start button and task bar permanently burned in) are also major barriers. Another issue that plasmas suffer from is that they don't have native greyscale - each RGB sub-pixel is either on or off, you can't control the brightness of the pixel. To simulate greyscale each TV frame or field is divided into multiple sub-fields allowing grey scale to be simulated by only illuminating the pixels for a percentage of the field duration (by switching on or off on a sub-field basis.) If you want 50% grey, you'd only illuminate for half (I think) of the duration of the frame/field. This means that they inherently flicker with some content at some refresh rates (which LCDs don't as they have a constant backlight). Because even with subfields you don't always get an 8 or 10 bit colour depth - dithering is also used to avoid banding, which means that PC pictures can look very noisy. (I've used a Windows PC on a plasma and it wasn't pleasant)

OLED is still low-yield and proving tricky to scale to a consumer price point. In the broadcast sector 17" and 25" OLED displays (1920x1080) have quickly replaced CRTs as quality monitoring devices (very high-end LCDs are also in use but OLED is often preferred), but they aren't cheap. They are also in 7" and 11" forms being used for studio camera viewfinders (the 7" models are 960x540, not sure about the 11"). They are excellent quality, but there are still question marks over their longevity, and they also potentially suffer from Image Retention/Burn In. They also, potentially, have refresh flicker (as they are light emissive, not transmissive, technologies)

[Starstream]

If looking for a display with good black levels (basically the reason for getting a plasma) on PC you could look around for displays with a VA panel, these aren't that common but do exist. MVA has better black levels than TN/IPS but it comes at a cost of high response time so bad for games but fine for video.

This site allows you to filter by preference it's reviews so for example the BenQ BL3200PT if you wanted something high end.

[noggin]

One thing I don't understand is why so many modern LCDs have so much processing that does little more than destroy picture quality? The first thing I do when trying to evaluate a display is switch off pretty much every optional processing function, put it in a manual picture mode, and turn the sharpness down to remove any artificial sharpening. Surprising how much better pictures can look then...

[l'pc]

Thanks for the quick and helpful information !

I had absolutely no idea you couldn't dim a plasma sub-pixel. And I must admit I know very little of VA panels. Thanks for pointing this out !

So I guess the short answer is that we may see pricy oled computer displays in the future.

@noggin : Yes, sadly this is something we are seeing quite a lot. Get a maximum wow-factor, no matter what sacrifices in quality you have to make. I must say that as long as the controls exist to make the device perform (close) to its optimum without having to invest more money or too much time, it won't bother me too much.

[noggin]

Thanks for the quick and helpful information !
I had absolutely no idea you couldn't dim a plasma sub-pixel. And I must admit I know very little of VA panels. Thanks for pointing this out !

That's why for many years you saw Plasmas marketed with "600Hz"(*) and LCDs marketed with "100Hz" or "200Hz" (scale 50->60 for the US market)

The (*) usual said in small letters "sub field" - as the plasma marketing teams included the sub-fields (that make up a single frame) in their refresh rate, whereas LCDs only quoted the number of different frames.

[l'pc]

So, if I got the math right there are per RGB subpixel only 24 subfields = 600Hz / 25fps. That would mean 24 subfields * 3 colors = 72 different color values per pixel (actually a little bit more if they use a bayer matrix since there are 2 green subpixel for every red or blue subpixel.)

That's seems very far from even 8-bit color coding… Where is my mistake ?

[skylarking]

I have two Dell U2711 monitors which are IPS based TFT screens and sitting in front of them can get very uncomfortable during summer.
My Poineer plasma TV screen also gets much much hotter than my Dell U2711 screens but obviously i don't sit as close to the TV.

I can't imagine sitting in front of any plasma monitor, if such devices existed, as they would boil me dry :?
As for OELD TV's, the ones i've seen get just as hot as my Pioneer TV, so unless something improves, they will also be uncomfortable devices to sit in front off.

So, the absence of plasma monitors is likley to do with people not being able to cope with working infront of these radiators and that inhibits their market to, well, zero.
Likely dito for OELD monitors, which i held such high hopes for this tech

Oh, i should also mention that the 600Hz subfield refresh rate is a measure of the rate used to refresh the pixles between each new frame.
Such refresh is needed as the plasma pixles (think of a flickering fluro tube) has a <2 millisecond responce time (and unless kept active will just as quickly go dark).
So if we have 60 frames per second video, this translates to a frame having to be active for every 17 milliseconds (and why we need to refresh the fluro's between frames).
As such, if we refresh the image within that frame 10 times, this translates to the marketing term of 600Hz subfield refresh rate.
Color is determined by a different meachnism as such, in part by how bright we fire each sub pixle and not related to the subfield refresh rate.
But i haven't looked into it to any great degree so may have missunderstood such aspects of plasma...

[noggin]

So, if I got the math right there are per RGB subpixel only 24 subfields = 600Hz / 25fps. That would mean 24 subfields * 3 colors = 72 different color values per pixel (actually a little bit more if they use a bayer matrix since there are 2 green subpixel for every red or blue subpixel.)

Plasmas don't use Beyer matrices usually, every pixel has a triplet of RGB subpixels. (Though some AMOLED displays use a pentile grid which has reduced blue-resolution ISTR)

However the sub-fields may not be equal duration, which allows a more binary PWM approach to greyscale. If you imagine one sub-field is 50% duration, one is 25% duration, one is 12.5% duration, you can then achieve something more clever.

That's seems very far from even 8-bit color coding… Where is my mistake ?

I think you are assuming equal duration sub-fields - don't think that is the case.

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As for OELD TV's, the ones i've seen get just as hot as my Pioneer TV, so unless something improves, they will also be uncomfortable devices to sit in front off.

I work with 17" and 25" OLEDs at work and they don't seem to get that warm. No problems sitting in front of them for a full day of work.

Oh, i should also mention that the 600Hz subfield refresh rate is a measure of the rate used to refresh the pixles between each new frame.
Such refresh is needed as the plasma pixles (think of a flickering fluro tube) has a <2 millisecond responce time (and unless kept active will just as quickly go dark).
So if we have 60 frames per second video, this translates to a frame having to be active for every 17 milliseconds (and why we need to refresh the fluro's between frames).
As such, if we refresh the image within that frame 10 times, this translates to the marketing term of 600Hz subfield refresh rate.
Color is determined by a different meachnism as such, in part by how bright we fire each sub pixle and not related to the subfield refresh rate.
But i haven't looked into it to any great degree so may have missunderstood such aspects of plasma...

I think you are mistaken re: greyscale. Plasma cells are either on or off. Grey scale is simulated by using the subfields. You can see this if you point a shuttered video camera at a plasma, as you can see the subfields clearly. In fact one issue with plasmas in TV studios is that some content can appear to flicker on camera as the sub-fields beat with the camera (particularly on cameras with mechanical shutters like the LDK series)

[black_eagle]

For those that want to know how a PDP sub-field drive works - http://palgong.knu.ac.kr/~plasma/Paperda...o_2004.pdf

Could be heavy going for some if you're not technically minded.

[Stereodude]

Plasma displays have issues with image retention and burn in, OLED's are just starting to come on stream, give them another few years to mature.

OLEDs has the same issues with burn-in as plasma. The first generation LG 55" OLED TVs also had issues with image retention as well. It's unclear if the 2nd gen models are better in regards to image retention or not.

[hossenfefer]

C.f. CD

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[PatK]

OLEDs has the same issues with burn-in as plasma. The first generation LG 55" OLED TVs also had issues with image retention as well. It's unclear if the 2nd gen models are better in regards to image retention or not.

Good to know, I heard that the first gen had issues with one colour losing brightness so it will be a while before this technology is fully mature. With the advent of the 5K iMac, it will not be too long for the rest of the industry to follow into retina territory for just about everything.