Optacon
The Optacon (OPtical to TActile CONverter)[1] is an electromechanical device that enables blind people to read printed material that has not been transcribed into Braille.
The Optacon user moves the camera module across a line of print, and an image of an area about the size of a letterspace is transmitted via the connecting cable to the main electronics unit.
The tactile array in the main electronics unit contains a 24-by-6 matrix of tiny metal rods, each of which can be independently vibrated by a piezoelectric reed connected to it.
The Optacon includes a knob to adjust the intensity at which the tactile array rods vibrate, a knob to set the image threshold between white and black needed to turn on the vibration of the rods in the tactile array, and a switch that determines whether images will be interpreted as dark print on a light background or as light print on a dark background.
In 1962, during a sabbatical year in Switzerland, Linvill visited an IBM laboratory in Germany, where he observed a high speed printer that used a set of small pins—like hammers—to print letters onto strips of paper.
A key aspect of Linvill's concept was to use vibrating piezoelectric reeds, called bimorphs, to move the pins in a two-dimensional array to produce tactile images.
The concept of a tactile optical scanning device can be traced back to 1915, as mentioned (and dismissed) in Fournier d'Albe's 1924 book, The Moon-Element.
Veteran's Administration, Prosthetic and Sensory Aids Service (PSAS), under Dr. Eugene Murphy, began funding the development of a reading machine for the blind.
However, in 1961 James Bliss had returned to SRI from MIT where he had done a doctoral dissertation in a group working on the application of technology for the problems of blindness.
These tactile stimulators were small air jets, which were ideal for research because their arrangement and spacing could easily be changed and the contact to the skin was always assured.
This higher level of funding was necessary to develop the custom integrated circuits that enabled the Optacon's small size, which was critical to its success.
Linvill's initial work with graduate students Alonzo and Hill indicated that a piezoelectric bimorph could be suitable as the transducer to convert an electrical signal into a mechanical motion.
The advantages of bimorphs were efficient transduction of electrical to mechanical energy (important for battery operation), small size, fast response, and relatively low cost.
Linvill calculated the length, width, and thickness of a bimorph reed necessary for a resonance frequency of 200 Hz that could produce enough mechanical energy to stimulate a fingertip above the threshold of the sense of touch.
The computer simulation presented tactile images of perfectly formed and aligned letters in a stream that moved across the bimorph array.
In considering the transition from the text being presented by the computer to the user moving a camera across a printed page, Bliss realized that there was a critical flaw in the design of the Veteran Administration Stereotoner.
From a practical standpoint, Roger's result was very fortunate because the higher frequencies were required for refresh rates fast enough for reading up to 100 words per minute and for use of bimorphs small enough to construct a 24-by-6 array that fit on a fingertip.
The question of whether 144 tactile stimulators on a fingertip could be independently distinguished led to a confrontation at a scientific conference between Bliss and Frank Geldard, a University of Virginia professor.
Both Bliss and Geldard were reporting similar reading rates, but in the days before high accuracy optical character recognition, the Optacon approach was much more practical.
In parallel with this human factors research was a pioneering effort to realize this design in a convenient portable unit, which would be critical for its success.
In July 1972, Harry Garland suggested a new design for the Optacon that incorporated the sensor, tactile array, and electronics in a single hand-held unit.
An effort was launched to develop a monolithic silicon retina with an array of 24-by-6 phototransistors about the size of one letter space so simple optics with no magnification could be used.
Basic research in integrated circuit technology available at that time had to be conducted, resulting in Ph.D. theses by several Stanford graduate students, including J. S. Brugler, J.
The phototransistors had to be sufficiently sensitive, fast enough for the required refresh rate, have a spectral response appropriate for detecting ink on paper, in a closely packed matrix without blind spots, and interconnected so only connections to the rows and columns were needed.
The low power electronics design in this unit was a joint effort by J. S. Brugler and W. T. Young which made possible about 12 hours of sustained operation from the rechargeable batteries.
This unit included an improved optical system and camera plus a tactile bimorph driven screen, both developed by James Baer and John Gill at SRI.
Several blind people in the Palo Alto community volunteered to participate, and Carolyn Weil was hired to coordinate, teach, and document this part of the project.
TeleSensory's initial sales were to provide Optacons for test evaluations for the U.S. Office of Education, St. Dunstan's for blinded veterans in London, England, the Berufsbildungswerk in Heidelberg, Germany, and Sweden.
Throughout the 1970s and into the 1980s, the Optacon underwent upgrades, and various accessories were added, including different lens modules to be used with the camera for reading text in a typewriter and on computer and calculator screens.
In 1985 Canon Inc. and Telesensory cooperated in the development of the Optacon II, which featured improved packaging and capabilities to interface to a computer (See Fig.
