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Information Technologies for Visually Impaired People
Figure 4: Transmission of Information by
Dorsal or Ventral Stimulation.
(although such a claim may be optimistic). Later other devices
based on this principle were marketed, such as the
"Visotoner" or its subsequent, more developed version, the
"Stereotoner". It worked by means of a camera that projected
an image onto an array of photo-receptors, each of
which was associated with a rising or falling frequency depending
on the position of the image. By passing the camera
over a line of text a user would hear sounds representing
the shape of each letter; for example the letter "v" would
be represented by a tone that started high, then fell, and
then rose again. Mauch Labs. Inc. ceased to manufacture
these devices in 1977.
Access to Written Information
Braille
The most commonly used method of reading for the blind
is braille, invented in 1827 by Louis Braille in France when
he was just 18 years old. It consists of a binary information
system using a cell of six raised dots (2x3) which is well
adapted to tactile exploration. A well trained blind person
can achieve reading speeds akin to those of sighted people.
The main drawbacks to the system was the space it occupied,
its difficulty to learn, and the cost of producing texts.
It was an indirect system of access to the written word
insofar as it required someone else to manually transcribe
the text (although a number of copies could be made at the
same time by putting two or three sheets in at the same time
and pressing harder).
In order to make reading faster and save space, some
countries developed a kind of shorthand braille. There are
specific coding systems to transcribe music scores or mathematical
texts, which need to overcome the problem caused
by the fact that braille is a linear system and music and maths
require multi-dimensional information to be represented
(matrices, fractions, five line staves). This information is
represented by a system of operators and parentheses.
Reproduction difficulties became a thing of the past with
the appearance of the braille printer and the thermoformer
– a kind of embossing photocopier.
The First Refreshable Braille Devices
In the mid seventies O. Tretiakoff invented an electronic
system of refreshable braille on a 12 character display. By
combining this display with a and audio cassette machine
and a 6-key braille keyboard he produced an innovative
device: the Digicassette. The braille was recorded on a cassette
and could be read on the 12 character braille display
(which was later increased to 20). This system made copying
easy and solved the problem of the sheer volume to be
stored. Later another US company came up with another,
similar system, the VersaBraille (see Figure 6), which was
equipped with a serial interface that allowed it to be connected
to a computer. The early cassette based recording
systems of Digicassette and VersaBraille were later upgraded
to floppy disk. These computer connectable refreshable
braille displays represented a major step towards Internet
accessible systems.
Generation of Interface Devices
Until relatively recently the quality of speech synthesis
was too poor to be used in assistive technology for the blind.
Today that problem no longer exists and an ever increasing
number of blind people are turning to this solution, which
is not incompatible with Braille and, while it falls short in
some areas, has some other very interesting advantages such
as ease of access, ease of indexing, and the possibility of
increasing reading speed. Today speech synthesis is a cheap
and simple way of electronically accessing any text document.
The refreshable braille systems used in Digicassette and
VersaBraille paved the way for modern day devices employed
as a means of accessing computerized systems directly
via a braille interface (see Figure 7).
Today practically all printed information is transmitted
through electronic media which, once legal and administrative
problems have been overcome, allows direct access
either by speech synthesis or by braille.
Figure 5: Use of the Optacon.
UPGRADE Vol. VIII, No. 2, April 2007 7