evaluation of the new Sony PVM OLED. luminance, color, timing, etc.

spacediver

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http://www.journalofvision.org/content/13/7/6.full

just read through this today. Impressive piece of work (both the study and the display).

key points:

*Black levels are ridiculously impressive (0.00003725 cd/m2, and even that may have been due to ambient reflections of other sources of radiation).

*Black crush is essentially non existent (fig 7)

*Doesn't use sample and hold (fig 19). The data shown is using 60hz timing, and while each frame thus lasts 16.7ms, the actual light impulse lasts about 7.5 ms. For a comparison to lightboost and regular sample and hold LCD, see http://www.blurbusters.com/faq/60vs120vslb/ (courtesy of Mark Rejhon).

*There is a change in luminance across the screen, but it is less than the CRT and LCD that they compared it against (fig 15).

*There is a moderate luminance shift dependent upon viewing angle, but they did not measure this for CRT/LCD for comparison. (fig 13)

*There is some color shift across the screen, especially so in the green (fig 14).

Also from the article:

We define here the viewing angle deviation as the difference between the measuring direction and the right angle to the screen, as shown in Figure 12a. Figure 13a shows the results, which indicate that as the viewing angle deviation moves from zero (i.e., at right angles to the screen), the luminance of a white, red, green, or blue target decreased monotonically. The rate of decrease of blue luminance was higher than that of other colors. When viewing the screen from 80° in the right or left direction (almost parallel to the screen), white on the screen was seen as bright cyan. We performed the same experiment using another PVM-2541 and found that the color shift is inherent in this model. Sony has announced that the successive model (PVM-2541A) will halve this color shift. However, when a very large field-of-view is required, projection onto a curved screen is likely to be a better solution than short viewing distances to a flat screen.


There's a fair amount of other stuff, but this is what I thought would interest you lot.
 
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sharknice

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Interesting stuff. It would be awesome if they released one capable of a higher frame rate and let you set the hold timings. I think it would be trivial to add it to the OSD.
 

spacediver

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Agreed. It's clear that OLED can produce much shorter impulses than 7.5 ms. They likely implemented the 7.5 ms to eliminate flicker at such a low refresh rate.

For what it's worth, the display being discussed here retails for about $5500.

http://www.abelcine.com/store/25-Sony-PVM-2541A-OLED-Professional-Display-Monitor/ (this is actually the updated "A" version so it's even better).

Hopefully we can get a enthusiast grade model suitable for gaming for under $1000 within 3 years.
 

Mark Rejhon

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Good stuff in this thread. And very accurate information about sample-and-hold.
Agreed. It's clear that OLED can produce much shorter impulses than 7.5 ms. They likely implemented the 7.5 ms to eliminate flicker at such a low refresh rate.
And probably to maximize the light output.
OLED will still have difficulty with 1ms strobe lengths while retaining sufficient brightness (for now).

That said, 7.5ms is not as good as Panasonic's best plasma displays. Still needs to reach about 4ms-5ms in order to match the best plasmas (red/green phosphor decay cycle -- from illumination to decay).

See Figure 20 of the page you linked to.
A moving black field effect is what's being done by these OLED displays, including Sony's Trimaster EL display.
There's a high speed video of this OLED rolling black field.
The rolling black field effect on these OLED's is roughly analoguous to the CRT scanning effect (see CRT vs LCD), though the scanning is "fatter" on the OLED due to the longer "on" time.
 
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Elledan

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It's great to see OLED bringing some innovation again to a mostly stagnant field. PDP isn't a bad technology, but OLED is just so much more promising in terms of display rate, image quality and power usage.
 

you2

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I thought that OLED suffered from rapid colour shift due to decay rate imbalance between the three prime colours. Did they solve that problem or will this $5K monitor go from neutral/cold colours to very warm colours in 3 years ?
 

Pastuch

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I love OLED: Great info below.

"A disadvantage of this OLED display is that the frequency of the frame presentation is fixed at 60 Hz, which is because it is a video monitor designed for a broadcasting studio. For precise psychophysical or physiological measurements, e.g., in motion detection experiments, a refresh rate of more than 100 Hz may be required. Recent LCD monitors receive video signals with a frequency of 120 Hz; however, at the same time, LCDs may hold an image during each frame, which produces perceived motion blur. For the OLED display, the sustained duration of each dot is approximately 7.5 ms, rather than the full 16.7 ms of each frame. The resulting black period is considered to contribute to producing the perception of smooth moving images with reduced motion blur, similar to black periods inserted by backlight scanning in some LCDs. Wang & Nikolic (2011) proposed using a 120 Hz LCD display to mimic a CRT scanning at 60 Hz by inserting alternate black frames. The produced luminance change on the screen was similar to that on the OLED display scanning at 60 Hz. Thus, some modern LCDs can be used to present visual stimuli under precise temporal control like the present OLED. In contrast, in CRTs, the light-emitting period in each pixel is less than a few milliseconds, as shown in Figure 19c, which is considerably shorter than that of the OLED display (or an LCD). We still believe that the smoothest motion will be observed on a CRT with a high refresh rate because of its shorter image-holding duration."
 

Mark Rejhon

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I love OLED: Great info below.

"A disadvantage of this OLED display is that the frequency of the frame presentation is fixed at 60 Hz, which is because it is a video monitor designed for a broadcasting studio. For precise psychophysical or physiological measurements, e.g., in motion detection experiments, a refresh rate of more than 100 Hz may be required. Recent LCD monitors receive video signals with a frequency of 120 Hz; however, at the same time, LCDs may hold an image during each frame, which produces perceived motion blur. For the OLED display, the sustained duration of each dot is approximately 7.5 ms, rather than the full 16.7 ms of each frame. The resulting black period is considered to contribute to producing the perception of smooth moving images with reduced motion blur, similar to black periods inserted by backlight scanning in some LCDs. Wang & Nikolic (2011) proposed using a 120 Hz LCD display to mimic a CRT scanning at 60 Hz by inserting alternate black frames. The produced luminance change on the screen was similar to that on the OLED display scanning at 60 Hz. Thus, some modern LCDs can be used to present visual stimuli under precise temporal control like the present OLED. In contrast, in CRTs, the light-emitting period in each pixel is less than a few milliseconds, as shown in Figure 19c, which is considerably shorter than that of the OLED display (or an LCD). We still believe that the smoothest motion will be observed on a CRT with a high refresh rate because of its shorter image-holding duration."

I have already written about some OLED's sample and hold issues -- Why Do Some OLED's Have Motion Blur?. That said, I am glad that some OLED's such as the Trimaster OLED can impulse-drive to reduce motion blur.

That said, the article writer has not yet tested LightBoost, which massively outperforms scanning backlights, by bypassing the backlight diffusion problem. LightBoost is currently one of the most efficient strobe backlights for LCD displays (Achievable true MPRT of 1.4ms!) -- it has less motion blur than plasma (Achievable MPRT of ~4-5ms due to red/green phosphor) & less motion blur than Trimaster OLED (Achievable MPRT closer to ~7ms).

The scientist should get into contact with Marc Repnow, a different scientist in Europe, testing modified LightBoost monitors as low-priced tachitoscopes for vision research.

But all the full-color monitor-size OLED's have more motion blur than LightBoost.
OLED still has more work to solve the motion blur issue.

BTW -- I will not argue that OLED's colors massively blow away the color-mediocre LightBoost displays though!
Much, much, much better color on OLED.
 
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CrabJuice

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There is also color shift depending on emittance relative to current. Which they might or might not solve with PWM. I guess that rolling/scanning thing is better than regular PWM but its still not ideal.
 

RadXge

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OLED seems so promising. Can't wait to pick one up once it becomes affordable.
 

Elledan

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I thought that OLED suffered from rapid colour shift due to decay rate imbalance between the three prime colours. Did they solve that problem or will this $5K monitor go from neutral/cold colours to very warm colours in 3 years ?

The lifespan of the blue component has increased considerably and should last about as long as an LCD backlight by now.

That said, LG at least has gone for white OLED tech with RGB filters, which completely negates the issue.
 
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