If I understood this correctly, a pixel that is "on" in the tactile array is not just raised up above the "off" level, it is actually vibrating up and down at somewhere between 250 and 300 Hz.
That certainly makes the mechanics complicated, an array of such pins is not exactly off the shelf today either, I think?
It feels like the rest of the system, including of course the optical part which was a major achievement back then with custom silicon to get 144 photodiodes on a single chip, are more or less trivial today. But the complexity of a mechanical "display" is still not something that is solved by mainstream components as far as I know.
I wonder how reliable they are, I hope it's "very" since people are still using mechanical devices from 15+ years ago for something as critical. :/
Edit: I found this link [1] which shows a cross-section of a sensing pin connected to a piezoelectric bimorph. I can't imagine packing 144 of that structure that closely together, though. But perhaps the device offsets the bimorphs from the array, connecting the pins and bimorphs mechanically.
YOu are right regarding the vibrating dots. Actually, that is what makes the Optacon special compared to say, a refreshable braille display. It is actually easier to feel small structures if they are vibrating.
However, one big disadvantage of that system was the resulting noise. Reading with an optacon is pretty noisy.
However, it gave blind people a sort of independence that does no longer exist today. Some Optacon users did their degree with just that device, and basically no external help.
These days, OCR is still not enough and you often need help from a sighted person to actually get your study material prepared.
> That certainly makes the mechanics complicated, an array of such pins is not exactly off the shelf today either, I think?
A solenoid is just a pin with an electro magnet wire wrapped around, put a spring on the pin to pull it back into the electro magnet and when you turn the magnet on it should vibrate.
A 100x100 grid of solenoids should cost under $100 they are fairly cheap, you might even be able to use a grid of wires and pins so they are addressable.
That certainly makes the mechanics complicated, an array of such pins is not exactly off the shelf today either, I think?
It feels like the rest of the system, including of course the optical part which was a major achievement back then with custom silicon to get 144 photodiodes on a single chip, are more or less trivial today. But the complexity of a mechanical "display" is still not something that is solved by mainstream components as far as I know.
I wonder how reliable they are, I hope it's "very" since people are still using mechanical devices from 15+ years ago for something as critical. :/
Edit: I found this link [1] which shows a cross-section of a sensing pin connected to a piezoelectric bimorph. I can't imagine packing 144 of that structure that closely together, though. But perhaps the device offsets the bimorphs from the array, connecting the pins and bimorphs mechanically.
[1] https://books.google.se/books?id=6dWjBQAAQBAJ&pg=PA309