---------- Forwarded message ----------
Date: Sun, 16 Oct 2005 19:10:17 +0200
From: Ari <aridamoulas@xxxxxxxxxxxx>
To: Linux for blind general discussion <blinux-list@xxxxxxxxxx>
Subject: Fw: Pocket Braille for people on the move: zb051015
----- Original Message -----
From: "TNAUK" <tnauk@xxxxxxxxxxxx>
To: "TNAUK" <tnauk@xxxxxxxxxxxx>
Sent: Saturday, October 15, 2005 7:04 PM
Subject: Pocket Braille for people on the move: zb051015
Pocket Braille for people on the move
The article below may be of general interest to TNAUK subscribers
- it is article number 35 of this week's New Scientist, ns051015.
#35 Pocket Braille for people on the move
Celeste Biever
AT LAST, the world's first portable electronic Braille display. It
is small enough to fit in a pocket and can even be rolled up like
a newspaper.
The display consists of a sheet of tiny plastic paddles that bend
in response to a voltage. It is designed to connect to a
cellphone or laptop, and could also replace the liquid crystal
screen of an ordinary PDA.
Existing dynamic displays for blind people use an array of pins
that pop up when stimulated by piezoelectric actuators. But the
smallest versions are the size of a phone book and weigh about
500 grams, mainly because of the rigid fibreglass board the
actuators are mounted on. 'It's moderately portable, but you
certainly can't put it in your pocket,' says Curtis Chang of the
National Federation for the Blind in Des Moines, Iowa. At $3800
each, they are also too expensive for most people. 'I think the
new display is a great idea,' Chang says.
It will almost certainly be cheaper. Created by Takao Someya and
his team at the University of Tokyo, the display is made entirely
of a flexible polymer and thin metal films. These layers can be
printed using low-cost deposition techniques, making a price tag
of as little as $100 a distinct possibility, says Someya.
The 16-centimetre-square prototype is just 1 millimetre thick and
weighs 5 grams. A grid of organic transistors sits on a polymer
membrane, with 144 plastic paddles on top. The entire device is
coated with thin rubber.
The paddles are made of a negatively charged polymer seeded with
positively charged lithium ions and sandwiched between two metal
electrodes (see Diagram). When a voltage is applied across the
electrodes, the lithium ions migrate to the negative electrode on
the lower side of the paddle. The result is a crowd of ions at
the bottom, which expands the polymer and makes it bend upwards.
On the tip of each paddle is a sphere under a millimetre across,
which rises when the paddle bends, causing a bump in the rubber
surface. When the current is switched off, the ions disperse back
into the polymer, the paddle straightens and the bump disappears.
The paddles take just under a second to move up or down, which is
acceptable for reading a book or a short message, but not for
someone working, says Chang. To make them move faster the
transistors need to be made smaller, so the electrons have less
distance to travel between the transistors' on and off state.
This might be possible using nanofabrication techniques, says
Someya.
Someya will present the device at the International Electron
Devices meeting in Washington DC in December.
The devices could also go beyond Braille and recreate whole scenes
on their surface, allowing the blind to feel images as well as
words. 'The idea is to create an array of tiny pixels,' says
Yoseph Bar-Cohen, an expert in Electro-active polymers at NASA's
Jet Propulsion Laboratory in Pasadena, California.
But he is concerned the force of the paddles in Someya's device
may be too weak. 'If a blind person cannot feel the movement of
the dots, the device will not be practical.'
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