Mr. Buhrow is putting together a meeting of the Special Speaqualizer
Committee with represenatitives of a high tech company from Columbia,
MD. He will probably want to give the R&D Committee an update on this
project, either here, or at an upcoming meeting of this group.
I am continuing to stimulate interest in other project areas, when ever
there is an opportunity to speak to an interested group. On the third of
November, I had such an opportunity. The paragraphs below are excerpted
from the talk I gave at the Applied Physic Laboratory of Johns Hopkins
University. Since giving the talk, I have heard from a couple of
engineering groups, one wanting to build a tactual pencil, and one
wanting additional information about a device for producing tactile
graphics on paper, under control of a computer.
Here, in part, is what I said:
The following paragraphs are excerpts from:
PENCILS, PICTURES AND COMPUTERS
TECHNOLOGIES IN SIGHT FOR THE BLIND
by
T. V. CRANMER, Ph.D.
I The tactile Pencil
The first tool I will describe is the simplest in concept but may
prove to be quite difficult to implement. I speak of a tactile
equivalent of a pen or pen--an instrument for free-hand
production of raised dots, lines and other drawings. The need
for this device should be evident, so I will not take your time
arguing for its necessity.
..
..
..
... here is a description of the hypothetical tactual pencil
(TP).
It should be small enough to comfortably hold in one hand and
manipulate with precision--perhaps the size of a two-cell double-
a flashlight. It should be self contained. Moving the point of
the TP in contact with a suitable surface should result in
producing a continuous smooth line easily perceived by touch.
This solid line might have a width in the range of 10 to 20
thousandths of an inch and a height approximately one half its
width. These dimensions are estimates for an initial design and
may be varied to determine the optimum line size. It should be
possible to make raised marks on a variety of surfaces, such as
paper, wood, metal, and plastic.
The TP ink should be contained in a replaceable cartridge.
Several materials will have to be studied to select a suitable
combination to form the TP ink. We need something that adheres
to the drawing surface, can be touched immediately or nearly
immediately, adheres with reliability, possess sufficient
elasticity and flexibility to resist some practical limitation on
deforming the surface supporting the deposited lines, be non
toxic etc. Materials that undergo a change in volume as it is
extruded should be sought. I believe that a chemical reaction
resulting in adhesion, solidification and dimensional enlargement
triggered by a self contained catalyst offers an attractive
research path. In the end, it may be necessary to design a new
material for this application.
Some work has been done toward producing a hot-glue or hot-wax
based device for making raised lines. These devices may some day
be useful for sighted people, but I am not aware of their use by
anyone who is blind.
II Tactile Graphics
The second challenge for your consideration involves production
of tactile maps and other graphical images on paper using
standard computer software and databases. The CAD packages and
drawing programs already available are more than adequate for
creating or editing graphical files. The graphical libraries now
available on CD-ROMs leave nothing to be desired for our purpose.
However, the output device for producing the tactual drawing on
paper does not now exist.
The Pixel Master color printer manufactured for a time by Howtek,
Incorporated produced acceptable tactile drawings, albeit, very
slowly, and at high cost. Multiple passes were required to
achieve a line height of about six thousandths of an inch. We
produced several sample maps using images stored on a CD-ROM.
Selected maps were displayed on a PC screen, adjusted for size
and edited for detail to compensate for known requirements for
tactual presentation. The edited map was then sent to the Pixel
Master to produce the finished product. See exhibit
The Pixel Master was never optimized for our application. This
technology should be examined with a view toward producing the
graphic embosser needed to produce tactual illustrations in
Braille textbooks for blind children in the public school
systems.
The work in progress of Edward Anczowski shows promise. A
retired chemist from Xerox of Canada who enjoys continuing
support from his former employer is now approaching alpha testing
a process that involves dusting a page containing a wet ink image
with a fusible powder. The page is shaken to clear away powder
that does not cling to the adhesive ink. Finally, the page is
exposed to heat to fuse the powder into the tactile image.
The Anczowski process is capable of producing approximately six
11" by 17" tactile graphics per minute. It produces usable
drawings with one pass.
See exhibit
Anczowski has received some financial support from the Canadian
Government. This source may not be available much longer due to
the fact that Anczowski now works alone and does not have a
convincing business plan. He needs a trustworthy partner to
bring his process to market.
Older and simpler methods once produced good raised line drawings
of schematics for vacuum tubes, transistors, geometric figures
and a fair number of illustrations for textbooks. The best came
from Science for the Blind, produced by its founder Tom Benham,
and Recording for the Blind. The method was labor intensive,
requiring manipulation by hand of a drawing instrument consisting
of a spur-wheel mounted in a handle. The small toothed wheel was
rolled along the lines of a negative drawing with sufficient
pressure to cause the individual teeth of the wheel to penetrate
the paper to produce dotted lines on the back of the page.
Turning the page over revealed the tactual drawing--reversed to
produce a positive image.
See Exhibit
The R&D Committee of NFB has discussed the possibility of using
spur-wheel pens to modify a conventional computer controlled
plotter. By equipping the plotter with spurs of different
diameters and pitches, it should be possible to produce a useful
variety of tactile lines. It may be necessary to use some more
rugged parts to withstand the additional mechanical forces
required to control the spur-wheel pens. A well designed
mechanical tactile plotter could serve as the output device for
reproducing images taken from a CD-ROM database.
IV A Tactile Computer Display
I am moved to place in nomination for recognition as the most
significant technological advancement of the twentieth century
the ubiquitous cathode ray tube and its sophisticated descendants
now seen in rich varieties of visual displays. Were it not for
the discovery of electron beam excitable phosphors, that coat
video displays, television sets and personal computer screens,
electronic communication as we know it would still be a dream of
the future. I also contend that we who are blind can look
forward to the day when we can enjoy similar benefits from
discovery, or design of the perfect material that leads to the
development of the tactile metaphor for the visual display.
Materials scientists, please listen up. We need a tactile
computer screen for all the same reasons that you need a visual
computer screen.
We must somehow learn to control the physical characteristics of
a plane surface so as to cause patterns of Braille dots to appear
and disappear as needed to display braille text. We should also
be able to raise smooth feelable lines and just as easily make
them fade back into the surface of the tactile display. We must
be able to bring about these topographical changes through
applied electrical fields, by a scanning laser beam behind the
panel, through hydraulic, pneumatic, electrostatic or other
computer generated control signals.
Some materials have received tentative consideration for
application for a braille or tactile graphics display, including
electrorheological fluids (J. Fricke, Germany,) and phase
transition gels (Steven Leeb, at MIT.). Further work will
determine whether these materials are suitable for the task under
consideration. Whether or not these materials meet minimum
requirements, I believe that it is essential that basic research
be initiated to identify materials that have the desired
properties. It is equally important to focus significant
research efforts to custom design optimum materials for a general
purpose tactile display for personal computers.
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