US 2721316 A
Description (OCR text may contain errors)
Oct. 18, SHAW METHOD AND MEANS FOR AIDING THE BLIND Filed June 9, 1953 INVENTOR. (Josey/z 0- 6/zaw United States Patent Ofilice 2,721,316 Patented Oct. 18, 1955 METHOD AND MEANS FOR AIDING THE BLIND Joseph D. Shaw, Cincinnati, Ohio Application June 9, 1953, Serial No, 360,438 Claims. 01. 340-213 The present invention relates to a system for aiding the blind, embodied in a portable unit and comprised essentially of a means for electrically stimulating a blind persons visual cerebral area through the operation of a light responsive means positioned for energization by the persons circumambient illumination.
It is an important object of this invention to provide a novel visual aid system for a blind person which will create for that person a perceptible image patterned after the general illumination and the intensity of light reflected from objects surrounding said blind. person.
Another object of this invention is to provide a light operated relay system adapted to transmit separate signals indicative of the intensity of light at given points inthe area immediately surrounding the blind person and to my system a photo-electric tube controls the intensity and/or the frequency of an electric stimulus whichis applied either directly by internal electrodes, or indirectly by external electrodes or an induction coil to the brain in the vision areas of a blind person. For the successful use of my system the vision area of the blind persons brain must not have atrophied and care should be taken during utilization of my system that the electrical stimulus produced thereby does not reach an intensity that would damage the said brain area.
Further objects and advantages of this invention will bebrought out and become apparent in the following specification, reference being'had to the accompanying drawing, in which:
Fig. 1 is a schematic wiring diagram of one form of the system for aiding the blind in accordance with my invention.
Fig. 2 is a wiring diagram of a modified form of my invention.
Fig. 3 illustrates diagrammatically another means for applying my system to the person of 'the blind.
Fig. 4 illustrates still another Way of applying my system to a blind person.
Referring now to Fig. l the drawing VT1 is a photoelectric cell or phototube having a cathode 1 which emits electrons when exposed to light and an anode 2 which attracts electrodes because the latter is operated at a positive potential. In this type of tube the number of electrons emitted by the said cathode and hence the voltage across the tube are proportioned to the amount of light falling on its sensitized surface. The phototube is positioned on the front of the person of the blind either by securing its socket piece directly to the clothing or mounting the socket upon a frame that may be readily secured to a part of the person. The circuit wire extensions for the phototube are indicated by the numerals 3 and 4 which connect the phototube to a trigger circuit 5 whose parts may be mounted in a case carried about the blind persons body or clothing. The trigger circuit is adapted to convert the voltage change in the phototube to electrical stimulating impulses that can be applied to the visual area of a blind persons brain through electrodes connected to the output of the trigger circuit. This trigger circuit comprises a battery EBi having one side connected to the anode lead 4 of the phototube and to a resistance R1 by a line 7, whilst the other side of said battery is connected to condensers C1 and C2 by a line 8. Condenser C1 is also connected to the cathode lead 3 of the phototube while condenser C2 is connected by a line 9 to the resistance R1. The grid 10 of a gas triode tube VT2 is connected to line 3 while its plate 11 is connected to the primary of a transformer T1, the opposed end of the transformer being connected to line 9 between its connections to the condenser C2 and the resistance R1. The secondary leads of the transformer are connected across a potentiometer P which in turn has each of its extended leads 12 and 13 electrically connected to a pair of conductors such as electrodes 14 and 15, respectively, applied either exteriorly or interiorly to the brain 16 in stimulating positions with respect to the vision area 17 of a blind person 18.
In the operation of my system the phototube is positioned upon the front of a blind person preferably on a portion of his body subjacent the head while the case enclosing the trigger circuit 5 may be attached to the clothing, mounted upon a belt, or suspended from the shoulders of the person in a suitable position on the back. The electrodes may terminate in a suitable plastic socket applied by surgery in and through the skull of the blind person, suitable electrical connections and flexible circuit wires connecting the parts together in any number of ways that will readily suggest themselves to those conversant with the art.
circumambient light impinging on the phototube VT1 allows the condenser C1 to be charged by battery EB1. The more light impinging on the phototube the faster the condenser C1 is charged. When the condenser C1 has been charged to a value such that the voltage across it is equal to the ignition potential of the gas triode tube VT2, said tube ignites and the condenser C2, which has been charged through resistance R1, now is discharged through the primary of the transformer T1 and the gas triode VT2. The more light impinging on the phototube VT1 the more rapidly the condenser C1 is charged to the ignition potential of the gase triode VT2. Accordingly the morerapidly the condenser C1 is charged to the ignition potential of the gas triode VT2, the more frequently the condenser C2 is discharged through the primary of the transformer T1. The discharge of the condenser C2 through the primary of the transformer T1 produces a voltage across the secondary of the transformer T1 which voltage is applied across the potentiometer P1. The output of the potentiometer P1 is connected to the electrodes 7 which are applied to the brain in the vision areas. When the brain is stimulated the person receives a sensation of light. Therefore the more intense the light the more frequently the brain is stimulated witha resulting sensation of light. If there is no light, sensation of light will be produced.
It is also contemplated that the frequency of the brain stimulus may have a constant value whilst variations in the intensity of the circumambient light impinging on the phototube will proportionately vary the intensity of said brain stimulus. Fig. 2 illustrates a system for accomplishing this objective wherein it will be noted that the phototube VT1 of the system shown in Fig. l is replaced by a resistance R2. A condenser C3 will therefore charge at a rate independent of the light intensity but dependent on the resistance R2. Accordingly the frequency of discharge of the condenser C3 and therefore of the stimulator is independent of the light intensity. However, :the secondary of the transformer T2 is applied" in series with a .circuit consisting .of the potentiometer P2 and a triode tube VTs. The grid 19 of the triode V'Tx is connected to its cathode 20 through the ,gridbias battery Bee and the resistance R3. A phototube VT4 is connectedfin serieswith the resistance R3 and a source of plate voltage BB2. When light impinges on the phototube VT4, more current exists in the phototube VT4; andiaccordingly more current exists in the resistance m With more current in the resistance R3, there isag'reater voltage across said resistance R3. When the phototube VT4.and theip'late voltage EB: are connected as in Fig, 3, the voltage across the resistance R3 tends to make'the rid; 19 'less negative withrespect to its cathode 20. Accordingly the triode VTs is able to conduct more readily and nowacts as a low resistance in' series with the pot'entiometer P2. Therefore the voltage to the electrodes will be increased. Accordingly as more light impinges on the phototube, the more intense is the stimulus. -This stimulus is applied through the electrodes to the brain as described in reference to Fig. 1. Accordingly the more intense the light the more intense the stimulus and the more intense the sensation of light.
An important variant of my invention is depicted diagrammatically in Fig. 3 of the drawing which shows a number of electrodes 20 applied to the brain 21 of a blind person such that each is located in a different part of the vision .area to form a kind of electrode pattern. Each electrode is connected to a circuit 50'which has either the constant frequency output of Fig. 2, and/or the variable frequency output of Fig. 1. Each of the circuits 0'hasan'individual phototube 22 and the phototubes are preferably mounted within a box 23- worn on the front of the person of the blind. The box is similar to a camera obscura in that it is interiorly darkened and'has a lens 24 positioned in an opening in its front wall which transmits images of external objects toward a back wall 25. This back wall carries the phototubes 22 which are mounted thereon in a pattern corresponding' to the pattern of the electrodes as applied to the brain. As indicated in Fig. 3 an output lead of each circuit 50' could'be connected to an indifl'erent part of the blind persons body thus providing a common electrode for each circuit 50 and requiring that but a single electrode be applied to the vision area of the brain to produce the required stimulus therefor. It will therefore beunderstood that ,circumambient'light will impinge with varying intensities on each of the phototubes in the pattern and each will inturn vary the intensity of the stimulus imparted by its particular electrode to the part of the vision area in which it is located thus producing a light and shadow pattern of sensation in the blind persons brain, who may with practice learn to translate the pattern into a meaning indicative of the general illumination and the positions of physical objects in his immediate surroundings.
The output of the stimulating circuits shown in Figs. 1 or 2, or a combination of both, would also be applied to the brain by an inductance coil 26 secured as shown in Fig. 4 to the exterior of the blind persons head by a band 27, or the like,
It -will' be seen from the above that I have provided a novel system for aiding the blind in that the blind will actually have a sensation of light whose intensity and pattern may be related by him to the physical objects immediately surrounding him. Further the electrical apparatus is relatively simple and can be compactly enclosed in a suitable light weight case for easy portability. It has been demonstrated that electrodes may be applied to the brain by an operation and that when in place they cause the person no discomfort because there ,are no pain receptors in the brain.
Having'described my invention in as clear and exact language as it is now possible for me to use, what is claimed is:
1. A system for aiding the blind comprising an electric conductor in stimulating position with respect to the vision area of a blind persons brain, a phototube exposed to the circumambient light of the blind person,
and a circuit connected to the phototube and adapted to translate the change in magnitude of the'current produced by the phototube into a variable sensitizing output current, and means connecting the conductor to the circuit and means for connecting each conductor with its re-' spective circuit output to thereby simultaneously produce variable, localized stimuli in the vision area of the blind persons-brain;
3.- A method for aiding the blind comprising subjectinga 'light' responsive means to the circumambient light of the blind person, causing a change to occur in the light responsive means in response to a change of intensity of the circumarnbient light, translating the change into stimuli whose values are altered proportionatelyby the change in the light responsive means, and subjecting the visual area of the blind persons brain to the efiect of the stimuli.
4. A methodior aiding the blind as set forth in claim- 3' characterized by the fact that the intensity of the stimuli is proportionally altered by the change in the light responsive means.
'5. A method for aiding the blind as set forth in claim 3 characterized by the fact that the frequency of the stimuli is proportionally altered by the change in the light responsive means.
References Cited in the file of this patent UNITED STATES PATENTS 1,820,357 .Lindstrom et a1 Aug. 25, 1931 2,249,572 Lieber July 15, 1 941 2,432,123' Potter Dec. 9, 1947 2,613,282 Scaife Oct. 7, 1952