Electronic things are often most successful when they duplicate some non-electronic thing. Most screens, then, are poor replacements for paper. Except, of course, for E-paper. These displays have high contrast even in sunlight and they hold their image even with no power. When [smbakeryt] was looking at his daughter’s Etch-a-Sketch, he decided duplicating its operation would be a great way to learn about these paper-like displays.
You can see a video of his results and his findings below. He bought several displays and shows them all, including some three-color units which add a single spot color. The one thing you’ll notice is the displays are slow which is probably why they haven’t taken over the world.
The displays connect to a Raspberry Pi and many of the displays are meant to mount directly to a Pi. The largest display is nearly six inches and some of the smaller displays are even flexible. It appears the three color displays were much slower than the ones that use two colors. To combat the slow update speeds, some of the displays can support partial refresh.
The drawing toy uses optical encoders connected to the Raspberry Pi. The Python code is available. Even if you don’t want to duplicate the toy, the comparison of the displays is worth watching. We were really hoping he’d included an accelerometer to erase it by shaking, but you’ll have to add that feature yourself. By the way, in the video, he mentions the real Etch-a-Sketch might work with magnets. It doesn’t. It is an aluminum powder that sticks to the plastic until a stylus rubs it off.
We’ve seen these displays many times before, of course. If you are patient enough, you can even use them as Linux displays.
When I was 6 years old or so, I had some toy “writing pad” that did work with magnets – basically a magnetic version of Eink if I understand it right. I wonder if the availability of small but cheap neodymium magnets could be used to make a higher resolution version of that for more practical uses.
If I remember correctly, they had cells which contained a ‘piston’ that was either stuck to the bottom by a weakly magnetic sheet, or the top by static(?) once you used a magnetic stylus to overcome the field from the sheet.
I’ve never heard of this piston system, but there was the “magnadoodle” which used magnetophoresis; it was composed of a grid of cells containing iron filings and a “mysterious, milky goo” with, presumably, a high-ish viscosity. A magnet could be used to move the black filings up out of the goo, where they were visible, and a large, captive bar magnet with a handle could be swiped across the back of the “display” to pull it all back down, where it was invisible.
I don’t see how the OP’s neodymium could be used to increase the resolution or automate this, however.
Was it this?: https://imgur.com/gallery/bp7OR
I remember having one as a kid as well. I think most kids have tablets these days anyway.
Huh, I’ve been toying with Waveshare’s e-Ink displays myself recently, since I decided to write a proper Arduino-library covering most/all of the displays in one, relatively easy-to-use library. Really neat things, just wish they cost less and took less time to refresh the image. Even if they were as slow as they are now, there’d be a huge amount of things to use them for, if only their prices came down.
Link?
https://github.com/WereCatf/wInk
You have all technology available and done to make real the biggest improvement of etch-a-skech in this millenium: button to turn the “marker” on and off for non-draw moves. THAT would be so awesome that you canot even imagine!
But wasn’t backtracking your lines always part of the fun/challenge? It separated the artists from the rest of the kids who just said screw it and cut straight lines from one part of the drawing to another. (I distinctly remember doing both!) ;)
The real fun was drawing lines back to back so that you could clear an entire portion of the display and peek into the inner mechanics of the thing!
Here is another way… https://emergent.unpythonic.net/projects/01142347802#
I’d call it a Tech-a-Sketch