Display technology


I was at a bookstore recently and marvelled at an electronic book reader that used e-ink technology. This is a low power, high resolution, highly reflective display technology.

It got me thinking how wonderful such a thing would be on a calculator. Does anyone know of any other interesting display technologies?


Yes, the contrast ratio of eINK is much better than normal LCD's.

There are several eINK type display technologies becoming available, unfortunately all of them are extremely pricey for DIY designs.



I own several e-ink devices, and while the stuff does have a power advantage over LCDs (under some circumstances), and possibly other advantages, contrast ratio is NOT one of them. The best you can currently get with the stuff is black on medium grey. It's fine under bright illumination, but I find that under typical room lighting that a good reflective LCD (e.g., hp 50g) is more readable than e-ink.

It is also extremely slow to update. Even the newer e-ink that is supposed to be faster than the previous generation is still extremely slow. I think if people had a calculator using e-ink they'd be very likely to complain about it. I'm not talking about animation, which would be impossible. Just pressing a number button or ENTER^ would take a noticeable fraction of a second for the display to update, vs. the nearly instantaneous update everyone is used to having with LCD (and with LED before that).

I expect that eventually e-ink technology will improve to where it has a good contrast ratio and fast refresh, but it ain't there yet.


How did you get'em?

Dev kits are thousands of dollars.



Built into e-book readers. They use the same panels as the dev kits. The early Sony readers used the earlier technology panel. The newer Sony readers and the Kindle use the current technology, which has slightly better contrast ratio, and is slightly faster, but still nowhere near as good as LCD.


Agreed with Eric here.

Previous discussions around this topic have concluded that the most likely use for e-ink displays in calculators would be to provide keycaps or menu labels that can be changed on the fly when the calculator goes from one mode into another, for example. Mode changes are much less frequent than display updates so would make sense from a power consumption point of view.

Putting the e-ink display into the keycaps would be tricky and expensive, I suspect. However, if the front bezel were made from transparent perspex then the menu labels could all be generated via an e-ink display attached to the underside, which would be a lot simpler from a technical point of view.

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