OLED dot matrix display life? - Page 1
Forum section: electronics / projects

author: peter-h
author_rank: Super Contributor
timestamp: December 03, 2021, 04:47:23 pm
content: 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~Productwhich 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.

author: fourfathom
author_rank: Super Contributor
timestamp: December 03, 2021, 05:41:39 pm
content: 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

author: james_s
author_rank: Super Contributor
timestamp: December 03, 2021, 05:51:41 pm
content: 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.

author: SiliconWizard
author_rank: Super Contributor
timestamp: December 03, 2021, 05:58:03 pm
content: 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#LifespanScreensavers "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.

author: james_s
author_rank: Super Contributor
timestamp: December 03, 2021, 06:00:22 pm
content: 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.

author: wraper
author_rank: Unknown
timestamp: December 03, 2021, 06:10:32 pm
content: 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.

author: SiliconWizard
author_rank: Super Contributor
timestamp: December 03, 2021, 06:16:22 pm
content: 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.

author: SiliconWizard
author_rank: Super Contributor
timestamp: December 03, 2021, 06:20:52 pm
content: Quote from: wraper on December 03, 2021, 06:10:32 pmYes. 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.

author: fourfathom
author_rank: Super Contributor
timestamp: December 03, 2021, 06:57:37 pm
content: Quote from: SiliconWizard on December 03, 2021, 05:58:03 pmYes, 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.

author: rsjsouza
author_rank: Super Contributor
timestamp: December 03, 2021, 08:58:22 pm
content: 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.

author: richnormand
author_rank: Unknown
timestamp: December 03, 2021, 11:17:37 pm
content: 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?

author: james_s
author_rank: Super Contributor
timestamp: December 03, 2021, 11:39:05 pm
content: 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.

author: rpiloverbd
author_rank: Regular Contributor
timestamp: December 04, 2021, 05:39:37 am
content: Personally I like 0.95 inch RGB OLED (A) from waveshare electronics. That supports SPI interface. Waveshare's products are QC passed as well.

author: peter-h
author_rank: Super Contributor
timestamp: December 04, 2021, 08:54:56 pm
content: 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/dayI wonder if perhaps the key lies in- specific materials- the life increases dramatically if brightness is below a specific valueThe 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 thishttps://uk.farnell.com/lumex/ldm-6432-p3-ble4-1/led-dot-matrix-display-64-x-32/dp/2946522Very big and very expensive. And variations such as thishttps://www.adafruit.com/product/4732.Then there is the decades-old and very pricey stuff like thishttps://uk.rs-online.com/web/p/led-displays/4965175

author: NiHaoMike
author_rank: Super Contributor
timestamp: December 04, 2021, 09:26:31 pm
content: 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.)

author: amyk
author_rank: Super Contributor
timestamp: December 05, 2021, 02:24:34 am
content: Quote from: peter-h on December 04, 2021, 08:54:56 pmVFDs are still very popular for that. Not cheap though....and there's inorganic LED matrix displays, which are also not cheap.

author: james_s
author_rank: Super Contributor
timestamp: December 05, 2021, 04:04:02 am
content: Quote from: peter-h on December 04, 2021, 08:54:56 pmThey 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.

author: wraper
author_rank: Unknown
timestamp: December 05, 2021, 10:08:09 am
content: Quote from: NiHaoMike on December 04, 2021, 09:26:31 pmDid 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.

author: NiHaoMike
author_rank: Super Contributor
timestamp: December 05, 2021, 04:26:34 pm
content: Quote from: wraper on December 05, 2021, 10:08:09 amIt 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.

author: wraper
author_rank: Unknown
timestamp: December 05, 2021, 04:52:57 pm
content: Quote from: NiHaoMike on December 05, 2021, 04:26:34 pmBluish was the most common color of EL backlight. And 12V is about right for EL inverter input.

author: peter-h
author_rank: Super Contributor
timestamp: December 05, 2021, 05:12:20 pm
content: 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

author: wraper
author_rank: Unknown
timestamp: December 05, 2021, 05:17:22 pm
content: Quote from: peter-h on December 05, 2021, 05:12:20 pmThere 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/

author: james_s
author_rank: Super Contributor
timestamp: December 05, 2021, 06:45:39 pm
content: Quote from: wraper on December 05, 2021, 04:52:57 pmI 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.

author: peter-h
author_rank: Super Contributor
timestamp: December 06, 2021, 09:27:56 pm
content: Apart from LCD, what solutions are there for say a 256x256 dot matrix, colour?Is there the equivalent of a plasma TV display?

author: Gyro
author_rank: Super Contributor
timestamp: December 06, 2021, 10:21:45 pm
content: Quote from: peter-h on December 06, 2021, 09:27:56 pmNope, 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.

author: rsjsouza
author_rank: Super Contributor
timestamp: December 06, 2021, 10:43:24 pm
content: When dinosaurs roamed the earth, plasma screens were one (then) promising alternative for portable computing: the Toshiba T3100 was one of them. IIRC you could choose any color, as long as it was orange.

author: james_s
author_rank: Super Contributor
timestamp: December 07, 2021, 12:06:58 am
content: I really wish somebody made a 19-20" 4:3 color plasma display, that would be fantastic as a replacement for worn out CRT displays in arcade games. LCD monitors look like crap in those.

author: Fraser
author_rank: Super Contributor
timestamp: December 07, 2021, 12:21:14 am
content: I own a logicube F-Sonix hard disk duplicator that uses an OLED display. You see a lot of these on eBay “sold as seen - untested” The reason is most have a failed display by now, including mineThe display fails to black on most of these units, with no sign of life left in it. The Electronics are working, it is the display that dies.I wanted to change the OLED display to an LCD equivalent but my knowledge of the display driver chips used on OLED displays and any compatibility between OLED and LCD driver chip protocols is zilchDoes anyone have experience of trying to fit a LCD display in place of an OLED type without having to change the firmware driving the display ? There is, of course, the possibility that the Logicube uses a custom display and driver but it would be interesting to know whether there is any compatibility across the two technologies where the communications with the display are concerned.Fraser

author: james_s
author_rank: Super Contributor
timestamp: December 07, 2021, 12:25:09 am
content: You're going to have to open it up and get a picture of the display in order for anyone to guess what it is. There is no clue visible from the face of the display. It's very possible that it is some completely standard off the shelf display.

author: Fraser
author_rank: Super Contributor
timestamp: December 07, 2021, 12:33:52 am
content: James_sYes, I completely agree. I was wondering whether anyone had experience in terms of the driver chips used on the OLED displays and whether any compatibility is known to exist between the two technologies when it comes to driving them. I am happy to do the leg work analysing the Logicube display and signals going to it but if the two display technologies are known to use completely different command sets, I know not to bother asking my timeI will dig out the Logicube and extract it’s display for some picturesFraser

author: amyk
author_rank: Super Contributor
timestamp: December 07, 2021, 01:27:23 am
content: There are definitely OLED and LCD controllers that use almost the same command set. You'll need either a part number on the display or logic analyser captures of the signals to figure out what it is.

author: TheMG
author_rank: Frequent Contributor
timestamp: December 07, 2021, 03:03:58 am
content: Quote from: peter-h on December 04, 2021, 08:54:56 pmI guess low temperature operation just isn't much of a consideration for manufacturers of such small general purpose displays.But it is definitely possible to make LCD displays that perform reasonably well is extreme cold temperatures. They are found in virtually every vehicle manufactured in the last few years. They do get a little sluggish at -40 but still perfectly usable for the display of general information and controls.

author: rsjsouza
author_rank: Super Contributor
timestamp: December 07, 2021, 03:05:55 am
content: Fraser, if you locate your unit, take a good look at its display and see if it matches one of the units mentioned in the long OLED/multimeter thread at:https://www.eevblog.com/forum/testgear/replacing-oled-screen-on-an-agilent-u1253a-multimeter/250/

author: peter-h
author_rank: Super Contributor
timestamp: December 07, 2021, 12:07:08 pm
content: There is not a lot in the TFT area, unless you are happy with very slow to update ones like thishttps://www.mouser.co.uk/datasheet/2/127/ediptft32-ae-1165627.pdfThat one is 10 years old, from Germany. Very slow SPI speed - 200kHz. No chance of building anything with moving graphics with that.Then there is this slightly newer one, from Australiahttps://www.mouser.co.uk/datasheet/2/451/4DLCD-32320240-Spec-V1.0-update_20180710-1608278.pdfbut no SPI speed spec that I can find.It doesn't look like a lot of firms work in this field. Maybe the Chinese own that market, but Mouser doesn't sell "cheap stuff"