Why OLED?

[JJTye]

Im having doubts about OLED. Yes I know they make great images, but is there any real need for a screen to be as thin as card? After reading the online manual for the Sony OLED screen, yet again they warn about displaying static images for too long. I mean, LCD can give a very good picture and the screens themselves are thin, yet are pretty hard to get screen burn. I just fail to see what the real benefits of OLED really are.

Jason.

[NicolasB]

I just fail to see what the real benefits of OLED really are.1) Limitless contrast ratio: blacks are absolutely pure black, far better even than plasma screens, let alone LCD.

2) No viewing angle issues (unlike LCD).

3) Near-zero response time which will likely avoid LCD-style motion judder.

4) Wide, accurate colour gamut (unlike, say, traditional rear pro TVs which tend to run out of red).

5) Much lower power consumption and heat output than any rival tech.

6) No DLP rainbows.

7) Ultra-thin, and potentially even flexible, screens.

[winning formula]

It has a lot of advantages, but at the moment its too expensive to make a t.v. and i think the highest size reached so far is 37'' [nevermind I'm wrong, 40'' has been produced] Unfortunately LCD has just started selling like crazy and people don't like being introduced to a new, major technology just after investing in one. So, we could be waiting until 2015 until OLED is cheap enough to kick off and have potentially the same life span as an LCD which at the moment is only half.

[JJTye]

1) Limitless contrast ratio: blacks are absolutely pure black, far better even than plasma screens, let alone LCD.

2) No viewing angle issues (unlike LCD).

3) Near-zero response time which will likely avoid LCD-style motion judder.

4) Wide, accurate colour gamut (unlike, say, traditional rear pro TVs which tend to run out of red).

5) Much lower power consumption and heat output than any rival tech.

6) No DLP rainbows.

7) Ultra-thin, and potentially even flexible, screens.

Yes I can understand a few of those points, but is there any real need for a screen to be mega-thin? The electronic components themselves need to go somewhere as well. I mean; look at that Sony job. All the components are in a big boxy stand that truly negates the benefits of a flat screen!

Not only that, OLED is susceptible to screen burn, since the blue element/compound/phosphor/whatever will wear out faster than the red and green, so bright static logos (such as Sky News) will leave their mark. Judging by what I have read about OLED, it would get screen burn even quicker than Plasma!

Your point about LCD judder. Well on my Samsung LCD monitor, I have watched TV programmes on it, and I can hardly notice any judder at all. We have a 37" Samsung LCD at work and the picture is dead-close to Plasma quality. And they leave it on Sky News all day and it NEVER has screen burn. Plus the viewing angle is pretty good. Who wants to watch TV at a 170 degree angle anyway?

Now don't get me wrong. I think OLED has potential, but I just personally feel it doesn't offer any significant benefits over LCD or Plasma. Until they can make it screenburn proof and price it far cheaper than LCD or Plasma, then I don't think it will succeed. Even SED showed huge promise (since it borrows CRT technology in some respects) is somewhat dead and buried.

Jason.

[y2k]

I read that OLED wont last anywhere near as long as a plasma or LCD, supposed to only last about 6,000 hours when a lcd or plasma can last 10 times that.

[NicolasB]

The latest OLED displays do not suffer from screenburn or display ageing any more. Instead of using blue OLEDs they use white OLEDs with a blue filter. This gives a display lifespan signficantly longer than either LCD or plasma. It's a solved problem: move on. :)

The principal advantage OLED has over other techs is the absolutely black blacks which are vastly superior to any tech currently on the market. It also has all of the advantages plasma has over LCD without any of the disadvantages, and combines that with much lower power consumption.

The thinness of the screen is entirely uninteresting as far as I'm concerned. But colour accuracy and black level are extremely important.

[punkymunky]

Yes I can understand a few of those points, but is there any real need for a screen to be mega-thin? The electronic components themselves need to go somewhere as well. I mean; look at that Sony job. All the components are in a big boxy stand that truly negates the benefits of a flat screen!

Not only that, OLED is susceptible to screen burn, since the blue element/compound/phosphor/whatever will wear out faster than the red and green, so bright static logos (such as Sky News) will leave their mark. Judging by what I have read about OLED, it would get screen burn even quicker than Plasma!

Your point about LCD judder. Well on my Samsung LCD monitor, I have watched TV programmes on it, and I can hardly notice any judder at all. We have a 37" Samsung LCD at work and the picture is dead-close to Plasma quality. And they leave it on Sky News all day and it NEVER has screen burn. Plus the viewing angle is pretty good. Who wants to watch TV at a 170 degree angle anyway?

Now don't get me wrong. I think OLED has potential, but I just personally feel it doesn't offer any significant benefits over LCD or Plasma. Until they can make it screenburn proof and price it far cheaper than LCD or Plasma, then I don't think it will succeed. Even SED showed huge promise (since it borrows CRT technology in some respects) is somewhat dead and buried.

Jason.

Since you seem happy with your LCD I can understand why you would think that this new tech gives no advantages. Personally and I am not alone among AV enthusiasts, I can't stand LCD screens which are a quantam leap backwards in picture quality from my 20 year old Sony CRT. If you truly understand how the primary elements of picture quality are measured (and it's not in the number of pixels), you will understand that OLED promises to be the Holy Grail of flat TV, which may expalin why Sony is sinking every last yen into it.

[kiran_mk2]

The latest OLED displays do not suffer from screenburn or display ageing any more. Instead of using blue OLEDs they use white OLEDs with a blue filter. This gives a display lifespan signficantly longer than either LCD or plasma. It's a solved problem: move on. :)

Not true - white emitters are even more problematic than blue as they have to contain either blue and orange or blue, green and red - thereby you get all the problems of all the colours rolled into one!


Also, the reason Sony is sinking so much into OLED is cos they felt having to not only partner with some to produce LCDs, but partner with the Koreans really hurt their pride. If national pride wasn't so rife in East Asia, we wouldn't have the affordable LCD panels we have today.

[JJTye]

The latest OLED displays do not suffer from screenburn or display ageing any more. Instead of using blue OLEDs they use white OLEDs with a blue filter. This gives a display lifespan signficantly longer than either LCD or plasma. It's a solved problem: move on. :)

The principal advantage OLED has over other techs is the absolutely black blacks which are vastly superior to any tech currently on the market. It also has all of the advantages plasma has over LCD without any of the disadvantages, and combines that with much lower power consumption.

The thinness of the screen is entirely uninteresting as far as I'm concerned. But colour accuracy and black level are extremely important.

Im not sure how I feel about your first paragraph. Since OLED is an emissive technology, like the phosphors used in a Plasma or CRT, they would lose their brightness as they age, so I still feel that OLED is at risk from screen burn. Think about it. If you are watching a lot of Sky News, the logo and the horrific white line above the scrollbar are driving those areas of the screen much harder, so the fluorescent materials will dim faster and therefore leave their mark. (much the same way as CRT or Plasma)

Howver I agree with your comments about the black levels, contrast ratio and low power usage.

Jason.

[Stephen Neal]

I've not heard of any major problems with screen burn on large-format LED screens - as used in many TV studios (Sky's News Wall for example), where individual 3mm or 6mm diameter LEDs are used to make up the pixels in a screen. It may be that the emissive materials used in LEDs behave better in this regard to the phosphors used in plasmas, which seem to be themselves far more prone to this than those used on CRTs.

[JJTye]

It may be that the emissive materials used in LEDs behave better in this regard to the phosphors used in plasmas, which seem to be themselves far more prone to this than those used on CRTs.

I did indeed read somewhere (quote) "The electron beam in a CRT is much kinder to phosphors than the hot gases in a Plasma". Perhaps when a plasma is displaying a still image, the gas gets so hot in the area of the displayed still image, that it literally burns the surface of the phosphor, which subsequently results in burn-in.

Jason.

[David1943]

I read that OLED wont last anywhere near as long as a plasma or LCD, supposed to only last about 6,000 hours when a lcd or plasma can last 10 times that.

But we're living in a disposable society now in which many people want the latest technology and won't keep a screen for five, let alone ten or twenty years.

[NicolasB]

I did indeed read somewhere (quote) "The electron beam in a CRT is much kinder to phosphors than the hot gases in a Plasma". Perhaps when a plasma is displaying a still image, the gas gets so hot in the area of the displayed still image, that it literally burns the surface of the phosphor, which subsequently results in burn-in.It's true that plasmas do tend to be rougher on phophors than CRT used to be, but it's not because of "hot gases". The reason for this is the way that the phosphors are stimulated, and, in particular, the way that the brightness of a pixel is controlled. In a CRT device the phosphors are stimulated by a scanning electron beam, and brightness is controlled by varying the intensity of the beam. If the beam is turned up high then the phosphor glows brighter. If the beam is of lower intensity then the phosphor emits less light. High-intensity beams cause the phosphors to age faster, so you increase screen-burn if you turn the contrast up too high.

In a plasma screen the phosphors are excited by ultra-violet light which is created inside little cells of ionised gas. You can think of each sub-pixel as being like a miniature fluorescent bulb. One you thing you may know about fluorescent lights (including "low energy light bulbs") is that they don't work with dimmer switches: the cell that produces UV light is either full on, or full off, and there is no in-between state. The way a pixel's apparent brightness is controlled is by pulsing the UV light on and off repeatedly within each frame. If the cell is on most of the time, the pixels appears bright. If it is off most of the time it appears dim.

This is what makes plasmas susceptible to burn: for whatever period of time the phosphor is lit up, it is always lit to the maximum possible brightness level (not unlike turning up the contrast on a CRT too high).

This method is also what creates motion artefacts on some plasma screens. Some people can see rainbows on plasma; they're not as bad as single-chip-DLP rainbows, but they can be perceived sometimes, because the red, green and blue parts of the picture are not necessarily all on the screen at exactly the same time. (This is another advantage of SED or OLED).

[Stephen Neal]

It's true that plasmas do tend to be rougher on phophors than CRT used to be, but it's not because of "hot gases". The reason for this is the way that the phosphors are stimulated, and, in particular, the way that the brightness of a pixel is controlled. In a CRT device the phosphors are stimulated by a scanning electron beam, and brightness is controlled by varying the intensity of the beam. If the beam is turned up high then the phosphor glows brighter. If the beam is of lower intensity then the phosphor emits less light. High-intensity beams cause the phosphors to age faster, so you increase screen-burn if you turn the contrast up too high.


Yep - and in a CRT each phosphor area is only excited very briefly by the electron beam as it scans past.


In a plasma screen the phosphors are excited by ultra-violet light which is created inside little cells of ionised gas. You can think of each sub-pixel as being like a miniature fluorescent bulb. One you thing you may know about fluorescent lights (including "low energy light bulbs") is that they don't work with dimmer switches: the cell that produces UV light is either full on, or full off, and there is no in-between state.


(Or more accurately - fluorescent lamps don't work with conventional dimmer switches. They can be dimmed by using the same method as is used with plasmas - which is how you dim florries in TV studios - though you need different excitation electronics to conventional florries!)


The way a pixel's apparent brightness is controlled is by pulsing the UV light on and off repeatedly within each frame. If the cell is on most of the time, the pixels appears bright. If it is off most of the time it appears dim.


Yep - plasmas use "sub fields" to do this - effectively pulsing the screen at a much higher rate than the vertical refresh rate to generate a grey scale.


This is what makes plasmas susceptible to burn: for whatever period of time the phosphor is lit up, it is always lit to the maximum possible brightness level (not unlike turning up the contrast on a CRT too high).


Yep - if the area contains quite a lot of peak white (like a DOG) the phosphor is likely to be near continuously excited (which never happens with a CRT as it scans at a constant rate)


This method is also what creates motion artefacts on some plasma screens. Some people can see rainbows on plasma; they're not as bad as single-chip-DLP rainbows, but they can be perceived sometimes, because the red, green and blue parts of the picture are not necessarily all on the screen at exactly the same time. (This is another advantage of SED or OLED).

I haven't seen or heard of plasmas doing separate RGB refresh - however the subfields are obvious on many if you watch whilst chewing gum or eating - as the jerky motion of your head breaks the picture up into the sub-fields. Also if you point a TV camera at a plasma it is often possible to see the flickering. I worked with a bunch of plasmas that suffered terribly with on-screen flicker of saturated blue material - because only a few subfields were being used they "beat" with the camera refresh rate.

This sub-field issue is why plasmas often seem noisy (in video noise terms). Because they have to use sub-fields to deliver grey scale - some displays don't have enough sub-fields to deliver 8 or 10 bit dynamic range - and some often only deliver about 6 bits. To hide the banding this creates, some dithering is introduced (i.e. noise is added to hide sharp band boundaries) - which appears as noise.

[JagoPlasma]

why moan about the thinness of a tv? have you ever tried lifting a 42" plasma out of a box onto a stand? on your own?

bring on thin, light tvs!

[Phantoma]

5) Much lower power consumption and heat output than any rival tech.



I have read the opposite.
http://techon.nikkeibp.co.jp/article/HONSHI/20080226/148048/

Scroll down to the Power Consumption paragraph.

[red16v]

I detect a very broad feeling of opinion that CRTs don't suffer from screen burn - of course they can.

My own personal opinion of 'juddering effects' on LCD is that it is down to the electronics behind the panel. I have just evaluated a couple of Vutrix professional 32" LCD monitors utilising the very latest Hitachi panels - the motion electronics behind it being the best I've seen. Of course it comes at a price >£4k but the results are excellent. I would certainly have one in my front room if I could afford it - and I am a very big fan of crt tellys.

[onkeh]

Also, the reason Sony is sinking so much into OLED is cos they felt having to not only partner with some to produce LCDs, but partner with the Koreans really hurt their pride.

Uh, source?

[NicolasB]

I detect a very broad feeling of opinion that CRTs don't suffer from screen burn - of course they can.Of course. It's just that plasmas are worse.

[JJTye]

Of course. It's just that plasmas are worse.

I find it strange you saying that. My parents have a Panasonic plasma, and my dad watches Sky News on it 93% of the time and it has NEVER suffered any permanent burn-in. I do know that the Panasonic plasmas are almost as difficult as a CRT to suffer screen burn. I must admit i have never seen burn-in on any CRT television in my life. You would have to do something really stupid like leave a very high-contrast image on a CRT for months on end 24/7 to cause screen burn.

On a different note, im just curious why CRT rear-projection TVs burn-in so easily, when they also use CRTs (though 3 small CRTs for each colour - effectively 3 little TVs in the set each displaying red, green and blue)

Jason.

[red16v]

You would have to do something really stupid like leave a very high-contrast image on a CRT for months on end 24/7 to cause screen burn.

On a different note, im just curious why CRT rear-projection TVs burn-in so easily, when they also use CRTs (though 3 small CRTs for each colour - effectively 3 little TVs in the set each displaying red, green and blue)

Jason.

If you work in a broadcast environment (like I do) sometimes it's a matter of necessity rather than 'stupidity' that you leave the same picture on a crt - although I appreciate your comments were more likely directed towards a domestic environment.

In your crt projector you have 3 small crts with very high EHT voltages working at extraordinary brightness levels - that it why you may suffer from screen burn 'issues' rather more quickly than a normal crt telly.

[blearyeyes]

Think OLED is closer than we think:

http://www.techradar.com/news/computing-components/peripherals/samsung-promises-42-inch-oled-tvs-by-2010-171885

:)

[Spartacus]

The biggest issue with Flat Screens in my experience is the Sample and Hold error that is inherent with the technologies.

I have pretty good eyesight and can detect this on even the 2ms LCD monitors.

Until they fix this then I am sticking to a CRT TV.

Would OLED fix this? Not sure it would.

[Daytrader]

biggest thing for me is that it will be crt quality but better in hd and flat thin screen, we all know the only reason they moved on from crt and went for lcd/plasma was easier to make and store in warehouse/deliver etc, massive step backward lcd/plasma was, really gets my goat up :)