E-ink or LCD or OLED?

I thought it would be really helpful to have a thread that try to compare the different display technologies available to a microcontroller these days.

Let’s start with LCD, the most classic type. With the beige background and stuff. Probably found on your calculator, they don’t have excellent viewing angles or contrast, but nevertheless enable comfortable viewing even under direct sunlight (that is, if your screen have some kind of anti-glare or it’s reflecting the glare away from your eyes). Yes, you may have to fiddle with contrast for a little bit, but that’s about it.
Traditionally they will stop working when there is little/no light. To compensate, we have decided to add LEDs to the bottom to illuminate them in the dark.
The refresh rate isn’t incredibly high, but you can get some decent graphics running on a Ti-84 (games, too. although definitely not on 60Hz).
The colorful type are called IPS LCD and are basically your laptop display, scaled down a bit. Or the original colored ones on Gameboys. Those are actually genuinely cool.

Now, the OLED. Basically a grid of tiny LEDs. Fast response, incredible contrast, but emits light and … while the incredible contrast help in sunlight, the limited ability to adjust the brightness (just … why) make it kind if a eye strain in low-light or long-time viewing. Also, the way digital device dim a display by PWM isn’t particularly natural, although it helps somewhat if you put a large filter cap.

Now, E-ink. The least touched on one, I assume. And I might start by explaining how does it work here. And as it’s noted the refresh is insanely low (more of 2 fps than anything), but have the advantage of appearing basically like paper (which is good on the eyes) and only use power when changing pixels.

Now is the pricing.
OLED is generally cheaper, while some character matrix LCD displays beating them and e-ink generally on the more expensive side.

Obviously for “game” purposes a e-ink will not be a very good fit, but on … say, a temperature widget? mp3 player? clock?

I mean, “saving eyeballs” only make sense to a device you can spend hours staring at. And a temperature widget is not something a normal person will want to stare hours at.
But honestly, let me tell you how you would think.

  • LCD
  • IPS LCD
  • OLED
  • E-Ink

0 voters

I kinda wish the sharp memory lcds took off. They basically have the best parts of eink and lcd in one display: very low power (though not bistable like eink), high contrast, sunlight readable, and fast-ish refresh rate. Downsides are the tech seems to have fizzled out since barely any product uses them so prices are even higher, they require slightly more complex drive hw due to how they work, and they cant be backlit (only frontlit afaik). This is the type of display used in I believe some pebble watch models as well as the playdate.

2 Likes

There’s also Vacuum Fluorescent Displays (VFDs), the least popular of the bunch. They are usually at least as expensive as e-ink displays, have incredibly visible graphics in daylight, come in dot-matrix and character forms (Segmented displays, 16x2 LCD type character displays, and pixel-like displays). They look really fantastic and a little sci-fi, but they’re very smashable. Because the display is vacuum formed between two sheets of glass, it’s very easy to break. They’re not as easy to drive as other displays either, you need two voltage sources, one at about 2.4v AC to heat a filament and create an electron storm, and one at 24-50v DC to attract and repel those electrons from the phosphors to control what glows where.