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New Graphic Displays for the Blind
An anonymous reader writes "Researchers from Spain have invented a new mechanism for graphical tactile displays for the blind. The displays use metallic films featuring various shape memory alloys which are produced layer by layer on silicon wafers using thin film technology. Display pixels are generated when the metallic film adjusts its curvature partially, similarly to bimetal snap plates for temperature switches. The movement of the films is then transferred to the touch panel via plastic pins und thus can be detected by the user."
Current braille displays use piezoelectric pins, not solenoids (pagers also use piezoelectric wafers to vibrate).
Piezoelectric pins are low-power, but also brittle. You can't get very good resolution because if you make them too tiny, they break. They also tend to have short lifetimes.
Solenoids are even bulkier, and draw more power, making them even less practical than piezo pins. Solenoids are good when you need a lot of punching power (which is why they're used for dot-matrix printer heads). They're overkill when you just want something a blind person can sense.
In 1999, two other Electrical Engineering students and I built something like this for our student design project. It used (guess what) shape memory alloys. It connected directly to the VGA output of a PC and averaged the color inputs to judge whether pixels should be raised or lowered.
It was only 8x8 pixels (just a prototype), but it was pretty awesome to move the mouse around and see those pins "do the wave".
The only drawback was the amount of heat it generated. Shape memory alloys change shape *because* of temperature difference (the change in temperature is not a side effect).
Even with a bunch of CPU fans cooling it, we were afraid our device would melt if we left it on for more than a few minutes.
It appears these folks have solved the heat/power problem with a design that requires power only when changing state. Nice work!
This is for use with CLI. As are todays braille displays.
Lots of fancy technology have tried to use tactile feedback for something useful for blind, but they have failed. The only useful tactile devise is really a braille display, and it displays single characters usually by moving 2X4 pieco-cells/pins up and down.
If you want to display a graphical interface, you really just map it down to one line of text (the line were your cursor is) - basically a CLI, and display it on an 80 character braille display.
Most other info (position, color, font-size etc) you either just discard, or display as sound.