US 2791762 A
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y 7, 1957 J. E. BERRY 2,791,762
SENSORY AID FOR THE BLIND Filed April 14, 1955 INVENTOR (2222 EBerr y ATTORNEYS SENSORY AID FOR TEE BLIND John Ervin Berry, Van Nuys, Califi, assignor to General Networks, North Hollywood, Calif., a corporation of California Application April 14, 1955, Serial No. 501,279
6 Claims. (Cl. 340-258) The primary object of this invention is to provide a sensory aid for blind persons, and more particularly, the provision of an electrically equipped cane or the like which senses and indicates the nature of the area surrounding the cane.
The invention embodies an oscillation system which is made to produce an audible tone upon the change of capacitance reflected into a circuit by means of a probing antenna. In other words, movement of an object or other variable factor in predeterminable relation to an apparatus embodying the invention, or movement of the apparatus relative to an object, causes variations in the capacity of the oscillating system, which in turn brings about variations in the frequency of oscillation of the system and such frequency variations provide audible tones.
With the use of a cane equipped with electrical apparatus according to this invention, a blind person may have better contact with his environment. As he moves through a room, along the sidewalk, across the street, etc., the omnipresent electrostatic fields of his immediate surroundings combine to have a definite, capacitive effect upon the probing antenna. Different surroundings will produce difierent capacitive effects, and therefore, a variety of audio tones are available.
These different tones soon become distinctive to a blind person, and each will apprise him of a particular condition in his surroundings. For example, they will inform him of the presence or approach of objects in his pathway and give him the relative distance to such objects. They will give him warning when he is ap proaching a sudden change of contour in his path or his surroundings and will provide a constant signal when he is walking along a sidewalk, for example, or beside a building. Thus, with this invention a blind person no longer needs to feel his way along with an ordinary cane in the conventional tapping manner.
Therefore, another object of this invention is to provide electrical apparatus for a blind person, so that he may easily be apprised of the condition of his surroundmgs.
More specifically, an object of the invention is to cause said electrical apparatus to produce an audible tone, the frequency of which is relative mainly to the non-atmospheric environment.
It is another object of this invention to produce said audible tone for the stated purposes by the principle of heterodyning.
Other objects of the invention and the full scope thereof will be apparent from the following specification and appended claims in combination with the appurtenant drawings in which:
Figure 1 illustrates exemplary apparatus embodying the invention; and
Figure 2 is a schematic drawing of an exemplary oscillation system suitable for practicing the invention.
In reference to Figure 1, there is shown an exemplary sensory aid in accordance with this invention comprising a cane 16 having a handle 12 and a leg portion 14. Affixed to the upper part of the leg 14 by clamps 16 2,791,762 Patented May 7, 1957 and 18 is an oscillation system in a unit 20. The antenna comprises a wire or flexible lead 22 which is mounted by antenna clips 24 to the leg 14 at intervals during its extension therealong from the oscillation unit 20 to the tip 26. Antenna 22-has a definite normal capacity, and this capacity is aifected by surrounding objects, the result of which is to change the frequency of the oscillation system in unit 20. Connected to unit 20 by connector 28 and leads 30 is a hearing aid type earphone 32 which reproduces audibly the result of frequency changes in the oscillation system. The audio frequency may be adjusted by tuning knob 34 (to be explained more fully hereinafter), and switch 36 turns the electrical unit 20 01f or on.
It will be appreciated that many varieties of oscillators may be utilized within the unit 20 to produce an audio tone, the only criterion being that the circuit be capable of responding suitably to changes reflected thereto by the antenna. Therefore, not only a regular audio oscillator but beat-frequency or heterodyne oscillators may be used. Figure 2 illustrates the use of heterodyning oscillators, this being the preferable method of obtaining the audio tones. The two oscillator circuits 4t) and 42 contained within dash lines 40 and 42", respectively, are each illustrated as a species of the well known Hartley oscillator. Again this is merely an exemplary showing, the shunt-feed Hartley, Colpitts, Meissner, tickler feedback, reverse feedback, tuned-plate, tuned-grid, crystal, magnetostriction, negative-resistance, relaxation, transistor, or saturable reactor oscillators, to name but a few, being just as suitable. lator circuits 4t and 42 are illustrated as being of the same type, no limitation thereto is intended since, for example, oscillator 40 could be a crystal controlled circuit while oscillator 42 could be any of the other type oscillators.
With reference now to Figure 2 in detail, .it will be noted that each exemplary oscillator circuit 40, 42 contains a pentode tube 44 whose screen grid is connected by a line 46 to its plate electrode 48 and whose suppressor grid is tied to its cathode 50. The filament 52 for each pentode 44 is supplied with heating power by batteries 54, respectively, and a double pole single throw switch 36 having a pole 56 in each filament-battery circuit.
Producing the oscillations in conjunction with each tube 44 is a tank circuit 58 for oscillation circuit 40 and a similar tank circuit 60 for oscillation circuit 42. Each tank circuit 58, 60 has an oscillator coil 62 which is tapped at points 64 and 66, the former tap being coupled by grid-leak condenser 68 to the control grid 70 and the latter via resistor 72 to cathode 50. Across the whole of coil 62 is connected a condenser to complete each tank circuit 58, 60. The condenser 74 in parallel with coil 62 in tank circuit 58 is preferably (but need not be) a variable condenser, as indicated by the arrow 76, and may be varied by the tuning knob 34 shown in Figure 1. However, the condenser 78, paralleling coil 62 in tank circuit 60, is preferably (but need not be) a fixed condenser, but attached to the tank circuit 60 at junction 61 is antenna 22 whose capacitance is effectively varied according to its surroundings, as previously explained. The effective capacity of antenna 22 may be considered to be in parallel with condenser '78 at all times and therefore effects the impedance of tank circuit 60 to vary the frequency thereof. Each tube 44 obtains its control grid 70 operating bias through resistor which is connected thereto and to the bottom of each coil 62.
The oscillations circuits 40 and 42 are connected in parallel with each other by interconnecting the tank circuits with a line 82 and the plate electrodes 48 with a line 84. Between lines 82 and 84 is connected the oscil- Also, even though the two oscillationsustaining battery 86-and"earphone-32,' each of which is paralleled by an R.-F. bypass condenser 88 and 90, respectively. Since the two oscillation circuits are in parallel, their frequencies of oscillation beat together and by well known heterodyne principles form a difference frequency when their frequencies'of oscillation differ in the least. The difference frequency is utilized directly, in this example, as the audio tone in'the earphone 32;
The operation of the sensory aid is as follows: The blind .personfirst turns on switch 36'WhlCl1 immediately allows each self-excited oscillation circuit 40, 42 to begin generating oscillations to produce anaudio tone in earphone 32 if the oscillations .in 'the'two circuits differ in frequency. The operator may then adjust reference oscillator 40 with tuning knob 34- to cause a definite and familiarly pitched audio tone (or, alternatively, a zero beat-no audio tone) to appear in earphone 32 while he has the cane leg 14, and consequently the antenna 22, related in a predetermined position to a predetermined object or the like. Upon moving the cane 'leg 14, the operator will hear a new audio tone if the surrounding objects, terrain, and/ or contours become different, since the effective antenna capacitance varies with the surroundings. In a short time, a blind person with his acute senses will be able to distinguish'a multitude of tones and relate each to particular surroundings.
The cane can, of course, be utilized in the conventional manner at the same time as it is being used in accordance with this invention. However, it is not necessary at all that a cane per se be used in the practice of this invention as long as the oscillation system has some sort of holder for the operator to handle and a movable antenna.-
higher the operating frequency of oscillation circuits 40" and 42, the less percentage change is necessary in the frequency of circuit 42, and consequently, in the antenna capacity, to produce the same audio-difference frequency.
Therefore, the system can be made to respond to changes insurroundings. when said changes are within predetermined large or small distance limits according to the operating frequency of thesystem. Satisfactory sensitivity has been found. .to' exist with apparatus of the type-illustrated when the operating frequency thereof was in the 75 kc. band. Values of circuit elements for operation at that frequency are as follows, although; it will be understood that'the invention is not limited. to the frequency noted or the values listed:
Tubes 44 CK-542 pentode Condensers 68." 150 mmf. Condenser 74 ()45 mmf. Condensers 78 Smmf.
Condenser 88, 1 mt.
Condenser 99 1 .002 mf.
Resistors 72 1200 ohms, /3 watt. Resistors 80 lmegohm, /3 Watt. Batteries 54 l /z volts.
Battery. 86 22 /2'volts.
Modifications of this invention not'described herein will become apparentto'those skilled in'the art." There fore, it is intended-thatthe'matter containedintheforegoing description be interpreted-its-illustrative and not tion systcnrforproducing frequencies in the audio range,-
said system having a tank circuit of variable impedance, and said frequencies in the audio range corresponding respectively to the variations of said tank circuit impedance, an antenna coupled to said tank circuit for varying the impedance thereof in accordance with the surroundings of said antenna, and means for holding said oscillation system and said antenna, said holding means comprising a cane-like structure.
2. A sensory aid for the blind comprising an oscillation system for producing frequencies in the audio range, an antenna coupled tothe oscillation system, said antenna having a variable effective capacitance and said frequencies in the audio range corresponding respectively to the variations of said effective capacitance, and means comprising a cane-like structure for holding said oscillation system and antenna, the arrangement being such that the effective capacitance of the antenna varies in accordance with its surroundings.
3. A sensory aid for the blind comprising an oscillatiQn"-system for producing difference frequencies in the audio range, an antenna connected to the oscillation systern, said antenna having a variable effective capacitance and'said difierence frequencies corresponding respectively to the variations of said effective capacitance, and'means comprising a cane-like structure for holding said oscillation system'and antenna, the arrangement being such'that the effective capacitance of the antenna varies in accordance with its surroundings.
lfA sensory'aid for the blind comprising a cane-like structure for holding a unit including a reference frequency oscillatorand' a variable frequency oscillator interconnected in parallel to produce difference frequencies in the audio rangefan'd an antenna connected to the vari able 'frequenc'y oscillator, said antenna having a variable effective capacitance and said difference frequencies corresponding respectively to the operating frequencies of said variable frequency oscillator and thereby to the variations of said effective capacitance, the arrangement being such that the effective capacitance of the antenna varie'sin accordance with its surroundings.
5. Ascnso'ry aid for the blind comprising a cane-like structure for holding a unit including an adjustable reference frequency oscillator and'a variable frequency oscillater'interoonnected in parallel to produce difference frequencie's in the audio range, and an antenna having a variable effective capacitance and said difference frequencies corresponding respectively to. the operating frequencies of saidvariable frequency oscillator and thereby to the variations of said effective capacitance, the arrangement being such that the effective capacitance of the antenna varies in accordance with its surroundings.
6. A sensory aid for the blind comprising a cane-like structure for holding a unit including a Hartley type reference frequency oscillator and a Hartley type variable frequency oscillator interconnected in parallel to produce difference frequencies in the audio range, means'to detect said'difference frequencies and an antenna having a variable effective capacitance and said difference frequencies corresponding respectively to the operating frequency of said variable frequency oscillator and thereby to the variations of saideifective capacitance, the arrangement being such that the effective capacitance of the antenna varies in accordance with its surroundings.
References Cited in the file of this patent UNITED STATES PATENTS 1,820,357 Lindstrom et a1. Aug-25,1931 2,112,826- Cook Apr. 5, 1938 2,238,041 Dickens Apr. 15, 1941 OTHER REFERENCES Article on pages 186 and 188 of the November 1954 issue of Electronics, titled, Cane Guides Sightless.