US2457456A

US2457456A - Reading aid for the blind

Info

Publication number: US2457456A
Application number: US669542A
Authority: US
Inventors: Leslie E Flory
Original assignee: RCA Corp
Current assignee: RCA Corp
Priority date: 1946-05-14
Filing date: 1946-05-14
Publication date: 1948-12-28
Anticipated expiration: 1965-12-28

Description

Dec. 28, 1948. L.. E. FLORY READING AID FOR THE BLIND Filed May 14, 1946 F1950 lli/VCV 1. INVENTOR. e E Hari( TKK ' 6J/z BY Patented Dec. 28A, 12948 Corporation of Ameri ca, a corporation of Dela- AplllicationMay 14, 1946,- Serial No. .669,542

17 claims. (olfato-41.5)

This invention relates to the art of converting Serial No. 560,472, filed October 26, 1944,'now` Patent No. 2,451,014, a device of the same general type is described and claimed. In the aforementioned device a lightbeam is caused to'scan each letter or other elementary area ofthe 'printed surfacebeing examined and the reflected light is employed to control the amplitude of an oscillator whose frequency is caused to vary synchronously with the movement of the scanning beam. The resultant output is an audible tone which is interrupted at the scanning frequency as the beam passes from white to blackgareas. Reading is accomplished by identifying the black area in terms of the frequency vof the tones produced during the scanning cycle. Some difficulty has been experienced heretofore in identifying the position of the black areas due to the presence of these scanning frequency interruptions, because they introduce a constant tone and a large number of harmonic frequencies into the output circuit, thus tending to confuse the tones and to make them partially indistinguishable. It is therefore the primary object of this invention to provide an improved reading aid which is free from these disadvantages.

In accordance with the present invention, an improved apparatus is provided in which `a plurality of separate oscillators for producingcurrents of distinguishable audible frequencies are controlled by direct current voltages produced by the frequency-modulated signal whose instantaneous frequency corresponds to thebeam position, so that a pure tone is produced representative of the instantaneous position of the beam. This tone is not interrupted at the scanning frequency and therefore it is, more easily identified.

The novel features `that are considered characteristic of this invention are set forth lwith particularly in the appended claims. The invention both as to its organization and method of operation, as well as additional objects and advantages thereof, will best be understood from the following description when read in connection with the accompanying drawings, in which Figure 1 is a schematic diagram of a reading aid inaccordance with this invention;

Figure 2 is a circuit diagram of a rectifier used in connection with Fig. 1; i

Figure 3 is an. alternativeembodiment employing a cathode ray tube; y

Figure 4 is a schematic diagram of a rectifier used inr connection with Figure 3; and

Figure 5 is a perspective view illustrating the movement ofa scanning beam across the printed line. T v

' Similar reference numerals are used i to identify similar elements throughout the several figures of the drawing.

`Referring now Vvto Fig. 1, a single line of a printedv page 4 is scanned' in a vertical direction by alight beam produced, for example, by a lamp l reliected'from a vibratory -mirror 5 focused on the page in a small spot by`a lens 3. The mirror is mounted for limited rotation about an axis perpendicular to the drawing and is held in a normalposition by a hairspring 1. An electromagnjet 9 ispositioned so as to react to the desired `degree onV the mirror when actuated by sweep'frequency currents produced by an oscillator Il. The mirror 5may vbe a metal mirror sofasto respond to the magnetic field produced by` the'electromagnet 9 or it may be a small glass mirrorv having attached thereto a small piece of iron or other magnetic material. The vibration of the mirroris adjusted so as to cause theV spot of, light I3 to scan successive elemental areas along a line I5 perpendicular to the printed matter, as illustrated in Fig. 5.v It will be understood that the lightsource, vibrating mirror and pickup'device, and such other, apparatus as may bedesired are mounted in a small container adapted to. be moved `by the user along theline of print in adirection perpendicular to the direction of scanning so as to cause the spot to scan successively adjacent areas and ultimately to coverythe entire -line'. The sweep frequency has such avalue that it is substantially above any frequericl7 generated by moving the scanner along the line'of letters, as for example, 600.cycles.`

Lightreilected fromv the surface of the page being scannedis' picked up by a Lucite rod l1 and fed to a phototube I9, the output of which is coupled through a resistance-capacitance network to the grid of 4an amplifier tube 2l. In actual practice the Lucite rod would be located approximately from the position illustrated so that the lightspot moves substantially parallel to its face. The output of amplifier 2i is coupled through a capacitor 23 to the first grid ofv a second amplifier 25 of the multigrid type.

The second grid o'fthi's amplifier is energized by area, it will be appreciated that thereflected light applied to the phototube will containI the frequency modulated currents corresponding at any instant to the position of the spot. These currents will be'amplified by amplifiers 55 and 51 and will therefore energize in turn all of the band pass filters and the rectifiers will then, in each case, apply a constant negative voltage to the grid of its associated audio oscillator. This negative voltage is sufficient ,toV prevent oscillations and no audio signal is therefore'applied to the output circuit, If the spot strikes a black area corresponding to the instant when the output of the frequency-modulated oscillator is passing through 125 kc., for example, nosignal will be applied to rectifier 6| no negative voltage will be developed and consequently oscillator 'H will go into operation and will produce an audio frequency in the output circuit. If the extent of the black area is suiiicient to cover the region which corresponds to the radio frequency bands represented by two or more band pass lters, the additional oscillators will be brought into operation as before and a musical tone will be produced representative of the location of the black area along the vertical scanning line.

A reading aid for the blind has thus been described which includes a spot of light for scanning an area in one direction While advancing the spot across the area in a direction at right angles thereto and for producing a plurality of currents of distinctive frequencies characteristic of the position of the spot and which are controlled in amplitude in accordance with the amount of light reflected from the area being scanned.

What I claim is:

1. The combination which includes means for producing a spot of light, means for moving said spot cyclically across an area in one direction while advancing said spot along said area in a direction at an angle to said one direction, means for producing a plurality of separate currents of distinctive frequencies, and means for controlling the amplitudes of said separate currents in accordance with the amount of light reflected from said area.

2. A device of the character described in claim l in which each of said currents is controlled by the light reflected from a different portion of said scanned area.

3. A device of the character described in claim 1 in which each of said currents is controlled by the light reflected from a dierent portion of said scanned area and maximum reflected light corresponds to minimum current amplitude.

4. The combination which includes means for scanning an area in one direction with a spot of light while advancing said spot across said area in a direction at an angle to the scanning direction; a source of oscillations; means for modulating the frequency of said oscillations in synchronism with the scanning movement of said spot; a plurality of frequency selective filter networks each responsive to a different frequency; means for applying said frequency modulated oscillations to said networks; means for varying the amplitude of said applied oscillations in accordance with the amount of light reflected from said area at any instant, means for producing currents of distinctive frequencies characteristic of each of said networks; and means for controlling individually the amplitudes of said currents in accordance with the variations of amplitude of said applied oscillations.

:5.1A device of the character described in claim 4 in which said currents have harmonically reflated frequencies corresponding to notes of a musical scale.

`6. A device of the character described inclaim 4 in which said means for applying said frequency modulated oscillations to said networks includes a thermionic tube Whose gain is varied in accordance with the amount of light reflected from said area.

'1. A device ofthe character described in claim 4 in which said currents Ahave a maximum amplitudewhen thelight reflected from said area is a minimum.

8. A device of the-character described in claim 4 in which said means for varying the amplitude of saidfapplied oscillations includes a phototube responsive to the amount of light reflected from said area.

9. A device of the character described in claim 4 in which said means for scanning an area in one direction with a beam of light includes a cathode ray tube for producing a moving spot of light, and means for focusing said spot on said area.

10. The combination which includes means for scanning an area with a Spot of light moving up and down at a fixed frequency while advancing said spot across said area in a direction perpendicular to the scanning direction; a source of oscillations having a nominal frequency substantially higher than said fixed frequency; means for modulating the frequency of said oscillations between predetermined limits synchronously with the scanning movement of said spot, a plurality of frequency selective filter networks each responsive to a different frequency .between said predetermined limits; means for applying said frequency modulated oscillations to said networks to induce -currents of distinctive frequencies in said networks; means for varying the amplitude of said applied oscillations in accordance with the amount of light reflected from said area at any instant; means for generating separate currents of distinctive frequencies characteristic of each of said networks; and means for controlling the amplitudes of said separate currents in accordance with the amplitude of said induced currents, respectively.

11. A device of the character described in claim 10 in which said nominal frequency is above the range of audibility, said fixed frequency is within the audible frequency; and the frequencies of said separate currents are harmonically related audible frequencies.

12. A device of the character described in claim 10 in which said means for controlling the amplitudes of said separate currents includes a means in circuit with each of said networks for rectifying said induced currents to produce D. C. voltages which control the amplitudes of respective ones of said separate currents.

13. A device of the character described in claim 10 which includes, in addition, means for converting said separate currents into audible tones.

14. A device of the character described in claim 10 in which the amplitudes of said separate currents are a maximum when the light reflected from said area at any instant is a minimum.

15. The combination which includes a cathode ray tube, means for producing a visible spot of light on the screen of said tube; a source of oscillations having a nominal frequency; means for modulating the frequency of said oscillations between predetermined limits, and for synchronous.

agrumes ly de'e'cting. said spotat a pred'eterminexed rate; means. for modulatingv the intensity of said vspotin-accorciance with 'said' frequency modulated oscillations; means for focusing saidr spot on a surfacecharacterized by having elemental areas of-dii'erent reflectivitywhereby the movement; of saidspot scans. saidsurface in a given direction, said surface. and said spot being relatively mov,- able in a direction perpendicular to said; given direction, and means responsive to the light/ reflected from said surface for producing` aA tone `criaracteristi-c of the position of said spot.

16.'l Ak device of the character described inclaim 15 in which said means responsive to the light reilected from said surface includes a phototube. 1

y 17. A. device of the character described in claim 151in;wh-ifch saidnieansresponsive to `tlrielight re- 8 nested from said surname-,for ,producing a ltone characteristic or the position ,ofgsaid spot; includes meansy for' generating a; pluralityof; separate audio frequencyv currents, ands-means forv controlling the amplitudes of lsaid currents; accordancewith the amount ,oflight. reflected fro-msaid surface'.v

' i ,l v x LESLIE E. lZiCZvRL-V REFERENCES CITED The following? references 'are' of recordin the me of this patent: STATES PATENTS.