In Braille, letters are encoded using a two-by-three matrix in which each character is represented by a different configuration of raised and absent dots at the six locations. To display these dots on a touch-screen device, Jussi Rantala of the University of Tampere in Finland and colleagues used a Nokia 770 Internet Tablet, which has a piezoelectric material built into the touch screen that vibrates when an electric signal is applied to it. The team installed software that represents a raised dot as a single pulse of intense vibration, and an absent dot as a longer vibration made up of several weaker pulses.
The team developed two methods: (1) the user moves a finger horizontally across the screen to detect the bumps, and (2) the finger stays still but the screen vibrates the sequence of six dots, each 360 milliseconds apart. In the latter method, once users got used to it, they could read a character in as little as 1.25 seconds.
The team's next step, says NewScientist
will be to present entire words and sentences. Screen-reading software is already available that "grabs" information displayed as text and turns it into speech. The same information could be turned into Braille characters on phones with vibrating touch screens.
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