kenneth.chrane at verizon.net
Tue Mar 3 01:47:32 UTC 2009
This is something we might do well to support.
New Optacon Design Ideas
*by James C. Bliss*
The Optacon was designed in the late sixties at the dawn of
integrated circuits, silicon photocell arrays, and before microprocessors.
design was based on extensive experiments with human subjects, blind and
sighted, that used computer simulation of various designs to determine the
most effective for reading text.
The final design incorporated a novel array of tactile stimulators composed
of piezoelectric reeds, or bimorphs, a custom integrated array of silicon
photocells, and custom integrated circuits of shift register/bimorph
The custom integrated circuits and unique piezoelectric reeds,
together with the small market, made the Optacon a difficult product to
source parts and manufacture. However, for those that mastered its use, the
Optacon filled an essential need. Even though the Optacon has been out of
production for over fifteen years, there are still over 150 avid users
trying to maintain their Optacons and demanding a new Optacon.
Now, almost 40 years after the original Optacon design, advances
in technology make possible a new Optacon design that could have greater
resolution, be easier to learn and use, and could have features that would
greatly extend the applications of use.
To reach the widest possible market, it is important to keep the
simplicity of the original Optacon while enabling new capabilities and
applications. Below are my thoughts on design possibilities that could be
considered. Not all of these ideas may be worth developing, but considering
them to assign priorities could help the process toward a new Optacon.
I. Resolution and Field of View
The original Optacon was designed around an array of 24 rows and
6 columns of pixels that drove a corresponding array of 24 rows and 6
columns of bimorph tactile stimulators. The 24 by 6 was based on tests
with human subjects that indicated this was the minimum number of pixels for
reading and tracking text at a practical speed. Actually, if you consider
24 pixels across a 0.1 inch letterspace, this is equivalent to only 240
dots/inch compared to the 300 dots/inch typically considered to be the
minimum needed for OCR. Also, the Optacon's 24 pixels across a 0.1 inch
letterspace is equivalent to a visual resolution of only 20/40.
In addition, reading with an Optacon requires the user to move
the hand held camera along a line of text. The limited field of view of the
Optacon camera requires this scan to be very precise; else the images of the
text are cut off. So reading would be easier and faster if the field of
view of a new design could be greater, thereby relaxing the precision needed
for line tracking.
Thus, for ease of tracking and reading a wider range of text
fonts and text quality, more pixels would certainly be better, analogous to
the greatly enhanced picture quality resulting from the recent television
change from a 480 line interlaced scan to a 1080 progressive line scan.
Fortunately, advances in technology make an improved resolution
and field of view possible at a reasonable cost. Therefore, I believe that
a goal of basing a new design on 36 vertical pixels to provide both improved
resolution and greater field of view should be considered.
Unfortunately, the Optacon II, which was designed by Canon, had
only a 20 by 5 array. This reduction in resolution and field of view was
one of the reasons reading is more difficult with it.
In the original Optacon design, the pixels were not square, but
rectangles that were twice as wide as they were high. This is because when
camera is moved along a horizontal line of text the letterspace is sampled
in the vertical direction, but an analog signal is obtained horizontally
across the letterspace. All of the image information can be obtained from
one column of pixels moved horizontally across the letterspace. However,
tests with human subjects clearly showed that reading accuracy increased as
more columns were added.
Based on these considerations, I suggest that a new design have
12 columns across the same horizontal field of view as the original Optacon.
Thus, the newly designed Optacon's pixels would be square, with the vertical
and horizontal resolutions being the same. The 36 by 12 array would
increase the number of pixels to 432, compared to the 144 in the original
Optacon, perhaps justifying a name for the new model as "Optacon HD" for
II. Tactile Array
In the past 40 years, there have been some significant advances
in piezoelectric materials. Several years
ago there was a study at Stanford University that indicated the bimorph
reeds in the Optacon tactile array could be half as long as in the original
design. This would allow incorporating the increased number of bimorphs in
approximately the same space as before.
A complaint about the Optacon has been the noise that it makes.
This noise comes from the bimorphs, which are being driven by a 250Hz square
wave, a frequency of maximum tactile sensitivity. This provides a strong
tactile sensation. The bimorph reeds were designed to be at near resonance
at this frequency to consume a minimum amount of power from the battery.
the Optacon design was finalized and production had begun, we discovered
this noise was greatly reduced if the bimorphs are driven with a 250Hz sine
wave instead of a square wave. This is because the human ear is much more
sensitive to the harmonics of a square wave than to the fundamental 250 Hz
frequency. However, we never had the opportunity to test whether there was
any detrimental effect on the tactile sensation when a sine wave drive is
used instead of a square wave. In a new design this should be tested and
the sine wave used if desirable.
At Telesensory the assembly of the tactile array was labor
intensive requiring considerable skill. Modern manufacturing techniques
including robotics could help reduce this cost.
III. Retina Module
When the Optacon was designed, no suitable integrated solid
state arrays of photocells were available, so a custom design was developed
in the Stanford Laboratories. Finding and maintaining sources for this
custom part at the relatively low quantities needed made Optacon production
difficult and expensive. Now integrated solid state arrays of photocells
are widely used in digital cameras, web cams, cell phones, etc. Thus in a
new design, a standard off-the-shelf part should be used if at all possible.
IV. Lens Modules
The original Optacon lens is not a true zoom lens because only
the lens is moved to change the magnification. This meant that the image is
only in true focus at two points along the zoom range and out of focus at
the ends and middle of the zoom range. The amount of out of focus is
sufficiently small to not be a problem given the low resolution of the
original Optacon retina. Because of the increased resolution I'm suggesting
in a new design, a better zoom system will be required. Actually, one of
the Optacon prototypes built at SRI and Stanford did have a zoom system that
moved both the lens and the retina to keep the image in true focus. This
did not change the size of the camera and would not be a significant
increase in cost after tooling for production.
Various lens modules, such as the typing attachment and CRT
screen module, were very important for the Optacon market because they
increased employment applications. While these particular accessory lens
modules are not as important today, others could be developed for producing
handwriting, reading LCD screens, viewing and taking pictures at a distance,
In addition to image signals from the Optacon camera, an
independent signal indicating camera movement should be considered. While
sometimes this can be derived from the camera images, there may be
situations in which it may be desirable to have signals from the lens module
Since the original Optacon was designed before microprocessors,
the electronics did not include a microprocessor, however Optacon II did and
any future designs most certainly would. In addition, a new design could
include some image storage as well as a port for an external memory
would enable camera scans to be stored for later retrieval and/or further
processing on a PC.
OCR and synthetic speech capability could be built into the
Optacon electronics. These capabilities, together with the storage
capability, means that the new design would need to have file handling and
other software built-in.
A very important control on an Optacon is the threshold, which
determines the photocell signal level between black and white. Especially
for poor quality print and for different colored print, how the threshold is
set can determine whether the text is readable or not. For precision
threshold setting, I think this part of the circuitry should be analog with
a high resolution potentiometer. Unfortunately, in Optacon II this control
was digital with too few bits for precision.
In addition to threshold and tactile stimulator intensity, there
would need to be some additional controls, or buttons, similar to those on a
"point and shoot" digital camera, for deleting images from storage, cycling
through a menu, etc.
A new design could have a port for the camera (possibly
wireless), a port for power (batteries could be charged in the Optacon or on
a separate charging station), a port for a memory stick, and a USB port for
sending camera images to a PC, for enabling the PC to write on the tactile
array, and for enabling new software to be installed in the Optacon.
The Optacon II design was an improvement in battery convenience
over the original Optacon and a new Optacon design could improve things
further. A system with readily available batteries that the user could
easily replace and charge should be the goal.
The Optacon II design was an improvement in packaging over the
original Optacon and a new Optacon design could improve things further.
IX. PC Software for the Optacon
By providing a new Optacon with a USB port where camera images
can be transferred to a PC and the PC can write tactile images on the
Optacon means that the basic simplicity of the Optacon can be maintained
while providing the possibility of adding many new features for expanding
Optacon use. Some examples are:
A. Optacon Reading Lessons and Speed Building
Optacon training was essential in producing so many people that
were successful in Optacon use. Teaching someone to use an Optacon
effectively was a labor intensive process. The most successful Optacon
training programs involved one teacher full time for every student for
several weeks. Since the seventies when these programs started, labor costs
have dramatically increased relative to the cost of technology.
However, with the widespread availability and increased
capability of PCs, it is now feasible to develop software that could
automate at least part of the training process. The PC could write letters,
words, and text on the Optacon tactile screen, build speed by presenting
these at various rates, test student progress, and provide feedback through
B. Speech and Braille Output
By OCR processing the images from scans from the Optacon camera,
the PC could provide speech or Braille output. Several tactile stimulators
could be combined to simulate a Braille dot on the Optacon's tactile screen.
Speech and Braille files could be stored in the PC in addition to image
C. Optacon Screen Reader Software
Optacon screen reader software could be developed in which
images from the PC screen were displayed on the Optacon tactile array. The
PC mouse could be used to move the field of view of the tactile image around
on the screen. This could be particularly useful in understanding screen
layout, viewing graphics on the screen, and in formatting documents.
I believe that developing and disseminating a new Optacon along
the lines described here would significantly enhance the educational and
vocational opportunities, as well a personal independence, of blind people
around the world. I've described a design that would preserve the basic
simplicity of the original Optacon, greatly improve the quality of the
tactile image, and make tracking along a line of text easier. By adding the
capabilities of memory storage and communication with a PC, new features
could be developed to make reading easier and faster through speech and
Braille, and that would expand Optacon applications. These design ideas
need to be evaluated by the blindness community.
My guess is that the development of this basic Optacon alone
could cost several million dollars. (The PC software and other accessories
could be developed later by third parties.) However, the relatively small
market coupled with the cost of development and the difficulties of selling
to this market will discourage private companies from taking on such a
project. The situation is analogous to that with low incidence diseases
where biopharmaceutical companies don't develop treatments unless there is
some consideration such as "orphan drug status".
The hope for bringing back a new Optacon might rest on obtaining
grant support for development and dissemination from private foundations or
government. For this to be viable would require strong support from the
blindness community and leadership from an organization with the capability
of accomplishing the task.
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