Vibrating touch screen puts Braille at the fingertips
31 March 2009 by
Anil Ananthaswamy
TOUCH-SCREEN devices like the iPhone are great when you can see them, but not much good if you are blind. Now a new way of presenting Braille characters
on a mobile device could be the first step towards a Braille-ready touch-screen phone.
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
(see diagram).
To discover how visually impaired volunteers would prefer to receive these vibrations, the team developed two different presentation methods. In the first,
the user touches the screen on the left-hand side to read whether or not there is a bump in that position of the matrix, then moves their finger horizontally
across the screen to read the remaining five dots. "But it wasn't that easy to read," says Rantala.
In the second method, the user simply places a finger anywhere on the screen and holds it still. The phone then displays a character by vibrating the sequence
of six dots, each 360 milliseconds apart. "It took some time for them to start reading, because this representation is totally different from anything
else that they had previously used," says Rantala. But once the volunteers were used to it, they were able to speed it up and read a character in as little
as 1.25 seconds (IEEE Transactions on Haptics,
DOI: 10.1109/toh.2009.3).
Once the volunteers were used to the vibrations, they could read a letter in as little as 1.25 seconds
The team's next step 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, says Rantala.
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