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.

[1] https://books.google.se/books?id=6dWjBQAAQBAJ&pg=PA309