High-resolution tactile displays

One of the ways in which some blind people interact with computers is via refreshable braille displays. But these tend to display at most 80 characters at once, and are apparently quite expensive.

So what alternatives can we come up with?

One approach, taken by Tactile Display Corporation is to try to increase the number of characters displayed (to many lines of text simultaneously) while reducing the cost. This is a reasonable goal, but surely we can do better. Why not aim for higher resolution?

The laptop screen I’m writing this on is 1366 pixels wide by 768 tall. When I look at the Wikipedia article on braille, it shows me some examples of braille characters. Each braille dot is represented not by a single black pixel, but by a disk of black pixels on a white background.

Present refreshable braille displays are effectively using a single pixel for each braille dot; therefore, they have to make the pixels large enough and far enough apart to be felt individually by someone who can read braille.

Would it be possible to make a tactile display of a size and resolution comparable to my laptop’s screen? Then, text could be displayed in braille, and images could also be represented to a certain degree by (for example) using areas raised further from the surface to represent darker patches on the screen.

Of course, I’m not the first to have thought of this idea. Here’s an article about a tactile display intended for images. That one had 3600 pixels (presumably 60 by 60), so that’s significantly lower than my laptop screen’s resolution. But that was more than ten years ago. What’s happening now?

One clever idea was to put the tactile feedback around a person’s finger (for example), rather than on a fixed display. I guess that this would require some tracking of where their finger is, so that the computer knows what feedback to send to their finger.

There are other tactile technologies designed for general use, rather than specifically for the blind. For example, controlling the friction that a user feels when moving their finger across a touchscreen, or nudging the screen to indicate when a user’s finger has hit an “object” on the screen. Neither of these change the shape of the screen, so it’s difficult to see how they could be used to display text, either as braille or in some other form that could be understood by a blind person.

One other promising innovation comes from Tactus Technology. They start with a flat touchscreen. Then, fluid can be pumped into areas of the screen, effectively pumping up “buttons” on the screen’s surface that the user can feel and press. The buttons can disappear again when they’re not needed.

I’m not sure, but my impression is that (so far) this only works with non-overlapping buttons in pre-defined positions on the screen, so although the buttons have rounded edges, this only gives the illusion of high resolution; it’s still not nearly high enough resolution to display braille, let alone images. But perhaps this “microfluidic” technology (whatever that means) can be used to make high-resolution tactile displays in future, benefitting both blind and sighted users of touchscreens.

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