On Burn-In vs Image-Retention and LG's new pOLED displays

In September 2017 LG Display started shipping its new 6" 1440x2880 (538 PPI) pOLED displays, which are adopted so far by two smartphones - the LG V30 and Google's Pixel 2 XL. On paper these displays are superb, but actual reviews were rather dismal - to the point that some reviewers say that these are simply "bad displays".

Google Pixel 2 photo

The reviews mentioned bad color reproduction, graininess and problematic viewing angles - and many consumers also reported serious burn-in issues. Samsung has recently started a marketing campaign that says that LG OLED TVs also suffer from image retention problems. In this article we'll explain what is burn-in, the difference between burn-in and temporal image-retention and also try to shed some light on LG's latest OLED problems.

The soft home button of the Galaxy S8 moves around to avoid burn-in

Image retention ("Burn in") is one of the major drawbacks of OLED displays, and a static icon or very consistent displays are always a problem with such displays. When Samsung introduced the Galaxy S8 it implemented a soft home button, which caused some concerns.

Samsung Galaxy S8 photo

PhoneArena confirm that Samsung's home button actually moves around by a few pixels from time to time - obviously to prevent serious image retention. Samsung employed the same trick with its "always on" clock display in previous OLED phones. This is a good way to improve image retention - although it won't solve the problem completely as the icon only moves around by a few pixels each time.

LGD to use Ignis' circuit technology to enhance the performance of its OLED displays

IGNIS Innovation announced that it has signed a non-exclusive patent license agreement with LG Display. Ignis will provide LGD with access to its circuit technology to enhance the performance of OLED displays.

CSOT 5.5-inch MaxLife AMOLED prototypeCSOT 5.5-inch MaxLife AMOLED prototype

Ignis Innovation developed several OLED circuit technologies. It's basic technology involves OLED compensation, both external and internal - which can improve the power consumption and lifetime of OLED displays. The technology should also increase production yields and enhance the picture uniformity and stability.

LG Display aims to produce OLED panels for monitors in laptops by 2017

According to ETNews, LG display aims to start producing OLED panels for computer monitors and laptops. LG wants to diversify their OLED product lineup, and this seems like a logical next step. ETNws estimates that the first monitors will be released in 2016 or 2017.

Samsung SDI 12.1 inch laptop prototypeSamsung 12.1 inch laptop prototype, 2009

LG Display is currently focused to solve the burn-in problem inherent with OLEDs which is a problem with monitors. LG also sees blurred-images on their OLEDs when used with different image sizes and monitor frequencies and has to solve that as well. LGD will first produce monitor panels and notebooks will come next as prices will have to be lower for that market segment.

Where are the OLED monitors and OLED laptops?

An OLED-Info reader recently raised the question - where are the OLED laptops and OLED monitors? This is an interesting question. Samsung currently produces AMOLEDs ranging in size from 1.63" for wearables to 10.5" tablet displays and LG Display is mass producing 55", 65" and even 77" OLED TVs.

Samsung SDI 12.1 inch laptop prototypeSamsung 12.1 inch laptop prototype, 2009

It seems that technically there shouldn't be a problem producing 13-15 inch OLED panels for laptops or even 20-25 inch panels for monitors. In terms of pixel density, these panels will be simpler to make compared to Samsung's mobile phone panels. Even a 13" 4K laptop panel will require only 339 PPI - much lower than SDC's latest 5.1" QHD panels (577 PPI). And of course SDC can start with a 15" FHD panel (146 PPI) which is easier to produce.

Ignis finally starts shipping 55" AMOLED Maxlife demonstrators to display makers

A couple of months ago Ignis Innovation announced that they began producing some 55" OLED TV evaluation samples for display makers to test their MaxLife compensation technology. Now the company finally started shipping orders to customers (display makers and OEMs). Ignis hopes that display makers will adopt their technology for TV, mobile and tablet OLED displays.

According to IGNIS, this panel offers the world's lowest power consumption (20% lower than LG and Samsung's current OLED TVs), longest lifetime (a significant boost over existing OLED panels) and their technology can improve production yield and so lower production costs.

Ignis' 55" OLED TV samples arrive, company says their technology enables lifetime and efficiency boost

Last month Ignis Innovation announced that they began producing some 55" OLED TV evaluation samples for display makers to test their MaxLife compensation technology. The company now tells us that the first sample panel arrived at their offices, and they will start fulfilling orders (to display makers and OEMs) in about two weeks.

The company did some initial measurements, and they say that this panel offers the world's lowest power consumption (20% lower than LG and Samsung's current OLED TVs), longest lifetime (a significant boost over existing OLED panels). The panels are highly uniform (much better than the OLED TVs no the market).

Apple new patent describes placing photo-diodes between OLED pixels for ambient light and lifetime compensation

The US PTO published a new patent from Apple (filed in 2012) that describes how to use sensors to compensate for ambient lighting (see DisplayMate's related recent article) and lifetime brightness degradation in OLED displays. The patent describes that photo-diodes can be placed inside the OLED array or above and below it.

Putting photo-diodes inside the display will enable them to more accurately measure light levels. So if a part of the screen is dimmer than the rest of the screen (for example because only a part of the display is under direct light) - the photodiode will detect it and then the display brightness in that area can be increased. This is something that cannot be achieved with a single sensor. Those photodiodes can also be used to learn whether certain OLED pixels (or pixel groups) have lowered brightness due to aging. Then the display can compensate and drive these pixels higher.

Ignis demonstrates their MaxLife external compensation technology

Back in June 2012 I reported from SID on Ignis' Max Life technology. Max Life provides external compensation - that deals with OLED burn-in. The idea is to keep track of how much each pixel was used, and so it's possible to calculate the brightness loss in that particular pixel, and then drive this particular pixel correctly - to compensate. Ignis now released a nice video showing a 20" AMOLED panel (their own a-Si prototypes made by RiTDisplay) with a burn-in logo. When Max Life is turned on, the logo disappears:

Ignis explains that while Max Life theoretically makes the "eventual" lifetime (until the display burns out completely) worse, in practice it helps to make the device usable longer. Ignis says that the main problem is non-uniformity in brightness and not actual brightness.

Kyulux - Hyperfluoresence OLED emittersKyulux - Hyperfluoresence OLED emitters