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"The Electric Eye," A New Tool For Handicapped People

Creator: Wallace C. Douglas, M.D., and O.H. Caldwell (authors)
Date: October 1932
Publication: The Polio Chronicle
Source: Roosevelt Warm Springs Institute for Rehabilitation Archives
Figures From This Artifact: Figure 1


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This article, obtained through the generous co-operation of Mr. Caldwell, former member Federal Radio Commission, and now editor of "Electronics," gives a glimpse of the possibilities of that newest servant of man, the electric eye. Parals must usually devise their own mechanical helps. A new tool is here described, concerning which full data is available on request to the Architectural and Mechanical Hints Group of the National Patients' Committee.

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THE past year has seen a rapid increase in the number, diversity and ingenuity of application of light-sensitive devices. Suddenly electrical men and practical production superintendents seem to have come to realize the usefulness of this remarkable new tool -- the "electric eye" -- in taking the place of human scrutiny and human drudgery in the performance of many routine tasks.

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Daily, new uses are found for the photocell and the number of these applications already is so expanded that the "electric eye" bids fair to penetrate into every activity of industry and of every-day life. From the movies to the factory, from the racetrack to, the corner traffic light, from the laboratory to the kitchen, the photo-sensitive cell finds hundreds upon hundreds of uses.

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Light-sensitive devices are of several different classes, based upon widely different physical phenomena, and each class has special characteristics which adapt it for particular uses. These different kinds of "electric eyes" may be listed as follows:

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1. The photoelectric tube -- a vacuum or gaseous cell, with light-sensitive plate which emits electrons upon illumination. This stream of electron charges is then amplified by other tubes.

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2. The selenium cell -- the familiar element which changes its resistance with incident illumination, now, in its latest forms, sealed in vacuum-tight tubes.

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3. Photo-voltaic cells, or batteries, which produce a change in current flow with changes in illumination.

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4. Dry oxide plates (copper oxide, etc.,) which produce comparatively large, low-voltage currents when illuminated.

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Wherever a beam of light can be interrupted, modulated or controlled by some operation which is to be counted, detected or reproduced, a light-sensitive cell of some of the types just described can be employed, and this can be done without interfering with the action to be recorded. For example, if the pendulum of a master clock is to drive other clocks without being itself loaded, a beam of light and a photocell will accurately record the master pendulum's swings without imposing on pendulum or train the slightest interference with its movement.

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One of the most important future uses of the "electric eye" in point of numbers, will be that of controlling interior illumination. For years we have automatically adjusted the temperature of our rooms by means of thermostats. Is it any less logical or less important to control the intensity of the lighting in workrooms, schoolrooms, etc., by means of a "light-o-stat" or light-sensitive cell?

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While the home has been recognized as a vast field for the installation of electrical appliances and so of photoelectric devices, as yet few practical uses have been found.

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Photoelectric garage door-openers are handy things for the home drive-way and home garage in wet or cold weather. The driver has merely to turn his headlights on the secreted electric eye and presto, the door rolls open. But even such installation, practical as they are, will probably be confined to a relatively small proportion of the 19,000,000 homes now served with electricity.

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With so many uses being found for the "electric eye" in industry and everyday life, it needs only ordinary ingenuity and a bit of experimental application to find ways to enlist photo-sensitive devices in the service of invalid persons.

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For example, if there is a heavy door to be opened frequently, the invalid can merely lift his hand or interpose the shadow of his body, and presto -- the door flies open!

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The mere lifting of the hand or moving of the head may be used to ring a bell or send a signal to an outside attendant.

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Lights in the room may be arranged to come on automatically when it gets dark outside. Windows can be automatically closed at the coming of the morning light, so that the invalid will have a warm, comfortable room for breakfast.

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The invalid can have a warning if anyone is coming along an unseen corridor or entry way, it the electric eye is put on guard.

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But the main feature of the electric eye's usefulness is its flexibility of arrangement. Whenever there is work to be done that can be controlled by a shadow or a beam of light, the unsleeping electric eye can be put to work.

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