OLED dot matrix display life?

[peter-h]

I see a fair number of these advertised on Alibaba/Aliexpress, at prices around $20, but there seem to be issues with them, like the one in the Voltcraft VC890 DVM which goes dim and dimmer over just a few years of very light usage.

I don't know whether this is normal with OLED displays, or whether there is something wrong with the ones used in Chinese DVMs.

Then I see some sold by e.g. Mouser (don't know how to create a clickable link, and the URL is very long)
https://www.mouser.co.uk/c/optoelectronics/displays/oled-displays-accessories/?q=oled&product=OLED%20Display%20Modules~~OLED%20Displays&resolution=128%20x%20128%7C~160%20x%20128%7C~256%20x%2064&rp=optoelectronics%2Fdisplays%2Foled-displays-accessories%7C~Product
which one would think can't be complete trash, but actually one Futaba data sheet gives a 4 month life to 50% brightness, which is a joke.

I am looking for an SPI-interfaced one, about 5cm x 5cm. There isn't a lot I can see, apart from ones which are self evidently junk.

[fourfathom]

It's a real problem, at least with the ones I've used.  I have one project where the same status message is displayed when the unit is idle (which is most of the time).  After a few months the "on" pixels are significantly dimmer than they originally were, and when the displayed image changes you can really see the difference.

So I am now reducing the brightness and/or displaying a screensaver that exercises all pixels equally when things are idle.  I am curious about the degradation rate at lower intensities, but haven't tested or researched this.  There are control messages you can send to the displays to control intensity, but apparently not all displays behave identically to these messages.  I'm using the little I2C 32x128 displays from various sources, similar to this:
https://www.amazon.com/gp/product/B08LQJ27XT

[james_s]

OLED displays are really best for intermittent applications, battery powered devices where the display is active while you are using it and then turns off. In continuous use they will wear relatively quickly although the actual lifespan seems to be highly variable.

[SiliconWizard]

Yep. Although they are not all made equal, lifespan is a general issue with those. It's no secret: https://en.wikipedia.org/wiki/OLED#Lifespan

Screensavers "that exercise all pixels equally when things are idle" are a bad idea. It will just help degrading all pixels more equally, if you think that's good. The best screensaver for those is complete OFF state.

[james_s]

The best screensaver has always been to turn the display off. They only ever really made sense on machines like the compact Macs that had a built in CRT that could not be separately powered off and even then the best screensaver would simply blank the display. Admittedly some of the screensavers on the market were cute and provided something interesting to look at in the background but in many cases they actually encouraged people to leave the monitor on rather than turn it off when not being used.

[wraper]

Some of these displays rapidly degrade even without any use. Others last quite well. Unfortunately it's hard to tell what you'll actually get. As example I can mention Keysight handheld DMM. Some lasted well, others had display rapidly degraded in a few years. Probably several compatible display models were used which made the difference.

[SiliconWizard]

james_s: Sure. Apart from looking cute (and yes, we all remember screensavers were once a whole new market! ), I can see one benefit: the user has a visual hint that the system is running. If the screen is off, it may not be so obvious.

If that's the point here for the OP, I'd suggest the following (which is what many mobile phones with OLED displays do for notifications): to show the system is "on" while the display is off, just use the display as you would use a LED (OLED displays are perfect for that): just flash a line of pixel every second, or something like this. It won't be as bad for lifespan as animating fancy stuff, and will draw minimal power on average as well. Maybe that's what the OP had in mind with their screensaver. But the point would just be briefly flashing simple shapes on screen. Even if it's always at the same spots (like a thin frame all around the display), if it's only briefly flashing, it'll be fine.

[SiliconWizard]

Some of these displays rapidly degrade even without any use.

Yes. The main issue is that they use organic materials. Their lifetime is by nature limited. But of course some manufacturers know how to do it better than others.

[fourfathom]

Screensavers "that exercise all pixels equally when things are idle" are a bad idea. It will just help degrading all pixels more equally, if you think that's good. The best screensaver for those is complete OFF state.

Yes, but my screensaver also dims the pixels to not-quite-off, and only a small percentage of the pixels are on so each one has about a 1% duty-cycle.  I want there to be some indication that the device is actually running. I figure it's an acceptable compromise.

[rsjsouza]

As others have said, OLED lifespan varies quite greatly and the Solomon models used by Keysight on their line of DMMs (and on some coffee machines) seems to have a wild variety of endurance, which could be caused by storage conditions (when defects are found in new or NOS units) or usage (mechanical or thermal shocks, or perhaps high humidity). Unfortunately from the reports mentioned in a few fora around the internet (including this one), it was never possible to isolate the root cause.

[richnormand]

Had a few devices with OLEDs from Keysight DMM to many small displays (used 24/7) in the lab to appliances at home. They all displayed ageing that was not appropriate as they were worst than fluorescent displays after a few years.
In the early days of OLED UV light and oxygen were killing them with the blue OLEDs being the most susceptible.

I still have a pretty old plasma TV used daily that looks as good as new but I wonder how well the "newer" OLED TVs are doing?
Is there data about OLED TV lifetime at this stage?

[james_s]

I only have one data point, my friend has an OLED TV he bought around 3 years ago, it still looks great but they mostly only use it to watch movies so it doesn't get a lot of hours.

[rpiloverbd]

Personally I like 0.95 inch RGB OLED (A) from waveshare electronics. That supports  SPI interface. Waveshare's products are QC passed as well. 

[peter-h]

This is really interesting... I never expected these replies!

So how do mobile phone makers achieve a life of at least a few years? Is it really due to the screen going blank after say 2 mins of non-use? That would not work for the "average young person" who might spend hours a day messaging, playing games, etc. And very expensive TVs use OLEDs and I can tell you half this country has the TV on 16hrs/day

I wonder if perhaps the key lies in

- specific materials
- the life increases dramatically if brightness is below a specific value

The evidence for assertion #2 lies in the way latest phones implement "flash" for selfies (the front camera): they illuminate the whole screen with an intense white which seems to be a lot brighter than the normal screen brightness.

It amazes me that after all this time we still don't seem to have a decent dot matrix display for industrial products, which "just works". LCD displays need a backlight, and work poorly in low temps so in some cases may need heating.

There is stuff like this
https://uk.farnell.com/lumex/ldm-6432-p3-ble4-1/led-dot-matrix-display-64-x-32/dp/2946522
Very big and very expensive. And variations such as this
https://www.adafruit.com/product/4732.

Then there is the decades-old and very pricey stuff like this
https://uk.rs-online.com/web/p/led-displays/4965175

[NiHaoMike]

I had a OLED backlit LCD something like 15 years ago, I used it as a stats display for a homemade router which wasn't a good use since the backlight faded to virtually useless after just a year or two. (That might be why those LCDs were crazy cheap at the time, something like $7 each.)

[amyk]

It amazes me that after all this time we still don't seem to have a decent dot matrix display for industrial products, which "just works". LCD displays need a backlight, and work poorly in low temps so in some cases may need heating.

VFDs are still very popular for that. Not cheap though.

...and there's inorganic LED matrix displays, which are also not cheap.

[james_s]

So how do mobile phone makers achieve a life of at least a few years? Is it really due to the screen going blank after say 2 mins of non-use? That would not work for the "average young person" who might spend hours a day messaging, playing games, etc. And very expensive TVs use OLEDs and I can tell you half this country has the TV on 16hrs/day

They use displays that cost hundreds of dollars, they had better last a bit longer than the typical $2 monochrome OLED displays. They are made using better materials, with a better controlled process and contain better electronics controlling them. They still have issues with screen burn but so did plasma TVs and before that CRT based rear projection sets and we lived with those for decades.

[wraper]

I had a OLED backlit LCD something like 15 years ago, I used it as a stats display for a homemade router which wasn't a good use since the backlight faded to virtually useless after just a year or two. (That might be why those LCDs were crazy cheap at the time, something like $7 each.)

Did they actually exist? Small LCDs had a LED backlight, for older types EL backlight was common, and that deteriorated quite fast.  Also I'm doubtful about OLED 15 years ago.

[NiHaoMike]

Did they actually exist? Small LCDs had a LED backlight, for older types EL backlight was common, and that deteriorated quite fast.  Also I'm doubtful about OLED 15 years ago.

It was sold in a surplus shop, the bluish glow was considered "futuristic" looking (compared to the yellowish green of LED backlit LCDs at the time) not too long before that. It had the standard 8 bit bus connection for a 2 row text LCD as well as a 12V input for the backlight supply. My guess is that some manufacturer of industrial or office machines ordered a bunch specifically to make their machines look "nicer" but then found out about the limited lifetime problem and ended up using something else. Also unusual was that the LCD needed about -3V on the contrast pin to get good contrast.

[wraper]

Did they actually exist? Small LCDs had a LED backlight, for older types EL backlight was common, and that deteriorated quite fast.  Also I'm doubtful about OLED 15 years ago.

It was sold in a surplus shop, the bluish glow was considered "futuristic" looking (compared to the yellowish green of LED backlit LCDs at the time) not too long before that. It had the standard 8 bit bus connection for a 2 row text LCD as well as a 12V input for the backlight supply. My guess is that some manufacturer of industrial or office machines ordered a bunch specifically to make their machines look "nicer" but then found out about the limited lifetime problem and ended up using something else. Also unusual was that the LCD needed about -3V on the contrast pin to get good contrast.

Bluish was the most common color of EL backlight. And 12V is about right for EL inverter input.

[peter-h]

EL backlights have a high failure rate, but fortunately LEDs do that job very well and last practically for ever.

I was reading about OLEDs and a major failure cause is moisture ingress, which kills them whether running or not. It is like EL displays getting an air leak, which happens when the epoxy seal fails, or the glass cracks.

Are there any non-organic LED dot matrix products, say 256x256, and I don't mean 30cm x 30cm which is obviously easy to do

[wraper]

EL backlights have a high failure rate, but fortunately LEDs do that job very well and last practically for ever.

I was reading about OLEDs and a major failure cause is moisture ingress, which kills them whether running or not. It is like EL displays getting an air leak, which happens when the epoxy seal fails, or the glass cracks.

Are there any non-organic LED dot matrix products, say 256x256, and I don't mean 30cm x 30cm which is obviously easy to do

There is microLED, available only in extremely expensive displays though. https://www.cnet.com/tech/home-entertainment/samsungs-huge-microled-tvs-start-at-110-inches-and-go-down-to-76/

[james_s]

Bluish was the most common color of EL backlight. And 12V is about right for EL inverter input.

I very much suspect that's what it was. I have several scanner radios with EL backlit LCD displays. Unfortunately it was common for these things to be left on 24/7 or at least most of the day so one of them was almost completely worn out and another is fairly dim. I replaced the worst one with a new strip and so far it's still holding up well. At the time most character LCD backlights used small incandescent lamps or green LEDs and were not particularly even. The EL backlight does produce a very nice pleasing glow that is very even, but the lifespan issue was never solved.

[peter-h]

Apart from LCD, what solutions are there for say a 256x256 dot matrix, colour?

Is there the equivalent of a plasma TV display?

[Gyro]

Is there the equivalent of a plasma TV display?

Nope, sorry. While physically possible to make one, the support electronics and power supplies would make it financially impractical for such a small display.

TFT LCD is as close as you'll get.