E-paper/E-ink display reliability


#1

Hi,

I’m currently looking to a eink/epaper for my Pi zero to display the info from a BME680. I would like to get a refresh rate between 5 to 10 seconds.
I’v read about the reliability issue of the initial version of the Inky PiHat, thanks for the blog update a year ago on it.
I couldn’t find much problem with the Papirus one on the forum and web, are they more reliable ?

I’ve read that below 1 refresh per minutes, it’s advise to use an LCD screen, is it still the case ?

Thanks
Regards


#2

The minimum we’d recommend is 1 minute, but arguably it should be longer still. It’s not so much a question of relability as design intent- epaper was never designed to be refreshed at a high frequency, and thus there are lots and lots of drawbacks from attempting to do so. Have you ever used an ebook reader, and noticed how every few pages it will invert the whole screen? That’s a compromise found even at low refresh rates to prevent the build up of image retention and other display artefacts.

It’s certainly possible to update monochrome epaper at a high rate, but since you’re physically moving particles of ink you can’t really beat the physics and avoid any lasting damage. We haven’t subjected our displays to anything more than 30 second intervals for tens of thousands of cycles- so we just don’t know what might happen.

I suspect nobody has pushed a Papirus to the limits long enough to notice any drawbacks and the same applies to our displays. You may be fine, but there’s no telling for how long.

You’ll probably get bored of or replace/rebuild your project before you manage to damage the display, but I’d recommend an OLED or small LCD since at higher refresh rates you’re not really playing epaper to its advantages.

Here’s an interesting video about pushing these displays to their limits: https://www.youtube.com/watch?v=MsbiO8EAsGw


#3

Thanks for the feedback,
I’ll reduce the refreshing rate, it should do the job.