Ghosted OLED screen – Image from rtings.com
There is absolutely no denying that big OLED screens are gorgeous, but people who know a thing or two about the technical side of displays have often noted there are some trade-offs for that.
The big one is cost. OLEDs, as well as Samsung’s quantum dot LCDs it has dubbed QLEDs, have super-premium price points.
Less often stated is the issue of burn-in or image retention – the after-effect of a screen developing ghost images of items that are stationary in the content presentation. Like a logo or watermark in a digital signage layout.
It is a problem that was around during the days when plasma displays were considered against LCDs for digital signage projects. And it is thought to be a problem these days for OLEDs.
Display industry consult Ken Werner has a really interesting post up on Display Daily about OLEDs and testing done on OLED TVs. The results show burn-in is, indeed, an issue.
Now, before relating some of that, it is important to note that the testing was done on TVs, not commercial OLED panels. And it is important to note that smart integrators and operators who go with OLED panels will know they need to have layouts and content presentation plans that ensure images are not static on screens.
The tests, as you will see below, involved running the same channels or feeds for 20 hours a day, week after week. Which is extreme, but then many signage networks are 24/7.
LG is pretty much the only mainstream commercial panel company marketing OLEDs, and for its part, says burn-in is only a factor if end-users are irresponsible. It suggests it is “possible to create image retention in almost any display if one really tries hard enough.”
LG also says there are some technical things, like subtle pixel shifting, it builds into its OLEDs to mitigate the risk. The company goes into all that here.
It’s also important to note, however, that LCDs don’t have this problem.
LG’s OLEDs bring some things to the table that, for some, make the risks worthwhile. They can be transparent, without needing back or edge lighting like transparent LCDs. They are impossibly thin and can be hung pretty much like wallpaper. And they are flexible, allowing for interestingly wavy surfaces.
Bottom line: it’s important to factor this technical stuff in, and plan for it, as opposed to just falling in love with the visual. If OLED is the perfect display canvas for the job, the people developing content need to know the do’s and don’ts around things like static visuals, to keep the ghosts at bay.
Menu boards would, for example, be a nutty use – because of the requirement for fixed images, but just as much, because of the cost versus LCDs that would do that job just fine.
Werner writes in Display Daily:
Since we (and many others) observed a serious logo burn-in problem on an LG OLED-TV set on the LG booth at SID Display Week this past May, many people in the display community have been rethinking the widely held belief that OLED-TV burn-in was a thing of the past.
But on January 24, 2018, Rtings.com had already begun a long-term burn-in test of six LG OLED-TVs, with one of six video streams playing on each set. The streams are Live CNN with the “OLED Light” set to 200 cd/m²; Live CNN with maximum screen brightness of 380 cd/m² as measured by Rtings with a checkerboad pattern; pre-recorded footbal games from a variety of channels; Live NBC; FIFA 18 Gameplay, which had some consistent fixed areas; and Call of Duty: WWII Gameplay. The sets are run in a five-hours-on/one-hour off cycle that repeats continuously. The test continues, with the Week 36 updates posted on October 4, 2018.
The October 4th photos show burn-in. The Live CNN (bright) set shows serious burn-in, especially on a solid 100% magenta screen, but it’s also bad on 100% red, 100% yellow, and 50% gray. The burn-in is moderate on a 100% blue screen, and barely visible on 100% cyan. (Please note that these judgments are being made from photos on Rtings.com’s website, not from the sets themselves. The Live CNN (200 cd/m²) TV also shows bad, but less bad, burn-in on the more sensitive colors. The sets subjected to the other four video streams show slight or no burn-in on the various color fields.
These sets have been running 20 hours per day for 36 weeks, which is a little over 5000 hours. You can look up the photos for any even-numbered week on the website. At week 30 (4200 hours), the burn-in on the Live CNN (bright) set was already severe; at Week 20 (2800 hours) it was significant. The culprit on the CNN screens were the always-on (or frequently on) areas at the bottom of the screen. Worst were the “Live CNN” logo in the lower right of the screen and the “Breaking News” bar in the lower left.
You can read Werner’s full post here …
Dave Haynes is the founder and editor of Sixteen:Nine, an online publication that has followed the digital signage industry for more than 13 years. Dave does strategic advisory consulting work for many end-users and vendors, and also writes for many of them. He’s based near Halifax, Nova Scotia.