Note: Descriptions are shown in the official language in which they were submitted.
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Tne invel-ltion relates to ~ si~ht ~id for Lhe blind in
whom the opt;c nervc still ex~ends to the regi.on of at least
one eye-socket. The r~maining parts of the optic pathway should
still function. The invention may be used b~. those whose eyeballs
have been removed.
Attempts have previously been made to restore a certait-
degree o~ visual faculty to persons blind in ~his way. To this
end, the ou~put signals from a television camera have been coupled
to the optic pathways v.ia probes connected by an operation to
said optic pathways ~ithin the skull. These experiments failed,
however, since the parts of the optic pathways to which the probes
are connected become unusable even after a relatively short period
of time, and the probe therefore has to he removed by operation.
Thus, ~fter a certain time there are no more parts of optical
i pathways to which the probes c~n be connected.
It is obvious that a sight aid for the blind would be
extremely valuable., Such a sight aicl is provided by the present
invention.
According to the invention there is provided a si~ht
aid for the blind, colnprising a vi.deo devlce for producing video
signals r~latin~ to the view in the fielcl of vision of said s~
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video device, an amplifier connected to the video device, a
transmitting aerial connected to the amr31ifier and arranged in .
the vlcinity of tlle c~re-sockeL, a receiver arranged near or in ~;
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the eye-socket and coupled electr~lncl~T-~ti.c.llly to .the trans~r,it:ting
aerial, the OUtptlt of said receiver having two outp-lt electroclex~
one of whi~h i s col.ipled via the lachrymal f~uid to a stil.1
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functioning part of the optical path~ays or Lo the end of the
~ptic nerveO
Practical tests carried out with the sight aid according to
the învention have shot~n th~t the afore-mentioned class of persons
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can ~ctually recognise objects with this aid. The resolving .`
power in the recognition of obj ects obviously depends on the
resolution of the video device. Letters approximately three
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~entimetres high can be recog~ ed by a patient using a CCD-
element (charge coupled ~evice) of the 3.atest type. A certain
~mount o~ practice on the part of the patient is also a help
in recognising objects, ~;
A principal a.dvantage of the slght aid according to the
lnvention is that the picture signals ~re coupled to the opti.cal
pathways via the lachr~nal fltli.d9 ~ncl accordillgly those parts
of the optlcal pathways involved in the coupling are llOt damaged.
One embocliment of the invention will now be described with
'O the aid of the accompanying drawings, in whi.ch:-
~ igure 1 is ~3 diagrammatic and perspectlv~ view o~ A frame
carrying the transmitting ~nit of a sight aid according to the
invent ion;
Figure 2 is a diagrammatic view of the optical arrangement
~5 ~nd CCD-element of the vidco device;
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Figure 3 is a block diagram of the electrica] circuitry --
in the transmittin~ unit''of the sight aid; '
-Figure 4 is a detailed block diagram of units 26 and 28
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of Figure 3;
Figure 5 is an electrical block diagram of the receiver _
with the output electrodes; and ,
Figure 6 is a diagrammatic section through the ocular
prosthesis unit in which the receiver is arranged.
Figure 1 shows a spectacles-type frame 2 whose side parts
0 3 and front part 4 accomodate the electronic components for the ,
' transmitting unit of the sight aid. Figure 1 ~lso shows dia-
grsmmatically an objective lens 5 for forming images of ob~ects
in the proximity of a blind person, on a likewise diagrammatically ~
represented CCD-element 6. A CCD-element is a photoelectric ~ '
component that can scan ~ picture formed on ~ ~creen'of the element
and produce a video output slgnal which depends on the brightness
values at the individual points of the screen. CCD-elements are ,
known per se and ar@ manufactured and marketed by, for example,
the Fa'irchild Camera and Instrument Corporation,
'O Figure 2 shows diagrammatically the optical device and the
CCD-element in their geometrical arrangement. The objective 5
i8 arranged 90 that the distance a can be varied in order to
form sharply defined images of objects at various distances on
,the sensitive surface oÇ the CCD-element 6. The picture field
angle ~ of the CCD-element 6 is for example 60 in the case of
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CCD 211 type mc~nufactul-ed by F~.ircl~ild can!er~ clncl In~t~lm~nt
Corporation. The front part ~ o~ the fr?me 2 is sho~ removed
from the CCD-el.ement 6 in Figu..e 2 so that ~he latter can be
seen more easlly. In actual fact the CCD-element partically sits
in the front part 4. The distance b~tween the objective 5 and
the CCD-element 6 is determined by the type o objeotive.
Figure 3 shows a block diagram of the electronic device
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of the transmitting unit of the sight aid. As has previously
been mentioned, the picture being transmitted to the blind person
ls formed by the objective 5 on the CCD-elernerlt 6. Fi~lre 3 shows
diagrammatically a CCD-element CCD 202 manufactured b~ Fairchild
Camera and Instrument Corporat;.on, the inputs being designated
as follows:
~ = posi.tlve input voltage
0H1 - horizontal, analog reglster-transport timlng pulse
0H2 ~ inverted, analog register-transport timing pulse
~R ~ scanning pulse
0P ~ picture backspace pulse and pictl~re element-reset pulse
0V1 - vertical, analog register-transport timing pulse
0V2 ~ inverted, analog register transport timing pulse
These input signals for the CCD 202 are pro~uced in a kno~
manner by a pulse generator 20 arl(3 control circuit 22, and
delivercd to the CCD 202. The time co-ord;.nation of the different .
input pulse trai.ns, the necess~ry volt~cs, and the like9 are
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given by the manufacturers of CcD-e]ements, to whom reference
should be made.
If the CCD-element 6 is controlLed with the said input
signals and if a picture is project~don the photosensitive
surface, CCD 202 delivers a video output signal via the line
24, and a compensation output signal via the line 24', These
signals are amplified in a wide band video amplifier 26 and
delivered to an output stage 28, and from there to a trans-
mitting coil 29. This transmitting coil 29 is connected at
10 one end to the output stage 28, and is earthed at the other
end.
Figure 4 shows a detailed block diagram of the wide band
video amplifier 26 and output stage 28 of Figure 3. The video
signal is delivered to an amplifier 30, which may for example
be an uA 733 type integrated circuit, via an impedance con-
15 verter consisting of a transistor 32 and a variable resistor34, and a capacitive coupling stage consi.sting of a capacitor
36 and a resis-tor 38. Corresponding to this, the compensation
signal from the CCD is applied to the inverting input of the
amplifier 30 via an impedance converter consisting of a trans-
20 sistor 40 and a variable resistor 42, and to a capacitivecoupling consisting of a condenser 44 and a resistor 46. The
impedance converter and capacitive coupling are in both cases
the same, and accordingly only the connection of the parts at
the non-inverting input of the amplifier 30 will be described.
25 The video signal is applied to the transistor base 32, the
collector being at the operating voltage
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and the emitter leading to the variable resistor 34. The other
end o the resistor 34 is e~rthed and its ~iper le~ds to the
capacitor 36. The resistor 38 is located betwee~ the capacitor
and the non-inverting input on the one hand, ~nd earth on the
other hand. A variable resistor is provided at the inputs 4 and
11 of the amplifier 30 in order to be able to adjust externally
the degree of amplification. Another way of adjusting the degree
of amplification is of course to ad~ust the input voltages via
the resistors 34 ànd 42. The positive operating voltage for the
amplif~er 30 is applied to the connection 10, and the negative
operating voltage of the amplifier 30 at the connection 5 of the
integrated circuit. A capacitor 50 and a terminating resistor
52 are provided at the output 8, both components being connected
in series and,the resistor being earthed.
The amplified video signal is derived from the output 7 of
the amplifier 30. A capacitor 54 for d.c. separation of the
following amplification stagc is first of all provided at the ~;
output 7. The capacitor 54 is connected to a resistor 56 which
is earthed.
The signal arising at the connection point between the
capacitor 54 and the resistor 56 is passed to the output stage ~
28, which in the present case is a push-pull output stage consisting F
of an NPN and a PNP transistor 60 and 62 respectively. The signal
p6s6e6 to the base contacts of tlle two transistors via a diode 64
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and a diode 66, ~ich are oricntated so that the NPN ~ransistor
60 receives the negative part of the signal vi.a the diode 64,
and the positive part of the signal is delivered to the transistor
62 via the diode 66. The resistors 68 and 70 serve to adjust
the base bias of the transistors 60 and 62. The collector of the
transistor 60 is at the positive reference voltage, whereas the
collector of the transistor 62 is at the negative reference voltage.
The emitter of the PNP transistor 60 is connected to a resistor 72,
and the emitter of the transistor 62 to a resistor 74. The other ~;
ends of the resistors are connected to one another and form the
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output of the output s~age 28. The signal arising at the output ~
i8 7 volts peak-to-pesk in ~he case of a circuit tested practically. !~F~.
It has been found that such a signal is suitable for feeding the ~:-
transmitting coil 29 and also for conveying signals to the
i receiving coil 82 (Figure 4).
The transmitting coil 29, which serves as a transmitting
aerial for the transmitting uni~ of the sight aid, consists of
two series-connected coils with 15 to 20 windings, the individual
windings having a diameter of ~ about 3 to 4 cm. One part of the
coil i8 arran8ed in the vicinity of tlle left eye-socket and the
other part of the coil in the vicinity of the right eye-socket, and
in such a way that the coils lie or. the inside of the front part
4 of the frame 2.
Figure 5 shows the elcctrical circuitry of the receiver 80.
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The receiver 80 has a rece;vi.ng coil ~2~ ~ capaci~or 84 collnected
in parallel there~o, and a di.ode 86 loc~ted bet~.een one en-l of
the receiving coil 82 and ~he Gapacitor 8~. In the practical
embodiment of the recelver about 50 m of wire are ~Yound to
S fo~n the coil 82, and the diode ~nd ce~acitor are chosen so that r
an optimum inductive coupling e~fect is a~hieved between the
transmittin~ co~l 29 and the r~ceiving coil 82. I~ith this optimum
coupling arran~ement the 7 ~Tolts peak to-peak on the transmitting -~
co~l 29 are sufficient for thc image si~nals from the receiver
.~ to affect the optic nerve. The OUtptlt of the receiver 80 is
formed by t~o electrodes 88~ 90. The electrodes ~8, 90 each
consists of approximately 25 cm long gold wire having a cross- .
section of 0.9 cm , wound toroidally, the cross-sectional ~idth of
the toroid being approximately 1 mm.
~ The spatial arrangement o.f the components o the receiver
80 in an ocular prosthesis member 92 is 5ho~m in ~`igure 6. The
back of the member 92, which ~aces the rear wall. of the eye-socket,
has a recess 94 in ~hlch one oul:put el.ectrode 88 is arranged in
the ~orm of a ri.ngO Tl~e recess 94 is closed by a plate 96 of
porous materi.al. The other output electrode ~0 is located ln
an annular ho].low space 98 e~ten(ling around the cornpletely sealed-
in receiving coil 82. The car~acitor ~4 and diode 86 are also
completely sealed in the prosthesis member 92. l~en the member
9 2 has been nssembled nnd the output elcctrodc h~s been connected
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up, a hole 100 is bored through the hollow space 98, which
is then filled with water. The hole 100 is then sealed so that
there is no longer any flow connection between the hollow space
98 and the recess 94. The recess 94 is filled with a li~uid
corresponding to lachrymal fluid, e.g. Optrik, and the plate 96
is impregnated with the same liquid. If the member 92 is now
inserted ln the eye-socket, the liquid in the recess 94 will be
continuously replaced by the lachrymal fluid produced by the
blind person himself. The output si~nal of the receiver 80 ~ ;
!O thus pass via the lachrymal fluid to the still functioning parts
of the optical pathways. The coupled signals are, as can be
seen from the above description, the output signals of the CCD-
element after amplificatlon, coupling to the receiver, ~nd ;
processing in the receiver circuit. These signals represent the L
result of a screen-like scanning of the light-sensitive surface
of the CCD-element, as is known.
The information transmitted via these signals to the optical
pathways is sufficient~ as has been shot~n by practical tests with
the sight aid according to the invention, to enable a person wearing
0 such a sight aid to see.
It shoul~ be mentioned that the invention is not restricted
to blind persons wllose eyeballs have been removed. If the
prosthesis member 92 is suitab]y designed, persons whose eyeballs
are still present but are completely non-functioning may also
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- see with the sight aid accordinc to the lnvention. In this case
too the picture signals from the recei~ter are coupled to the
still functioning parts o~ the optical p~thways, in particular
the optic nerve, via lachrymal fluid and, initially, via a
substitute fluid, for example Optrik.
The invention is obviously also not restricted to the
afore-mentioned type of CCD-element. Instead, video devices
corresponding to the latest state of the art will be used in
order to improve the resolving power of the sight aid. These
may or may not be CCD-elements. The sight aid is ready for
operation when a receiver is inserted. The visual faculty may
be further improved by employing two receivers, one receiver in
each case being coupled to part of the transmitting coil 29 It
is also within the scope of the invention to provide video devices
with separate transmitters and receivers, in order to provide ~
stereoscopic vislon. g
By choosing 8 particular CCD-element, a preferred freguency
range is established corresponding to the CCD-element. Such CCD-
elements whose maximum sensitivity is in the frequency range in
?O which the sensitivity of the human eye is greatestt will preferably
be chosen. On the other hand, the video device can also be
designed so that other frequency ranges are optimally used. By
virtue of the fact that the degree of amplification of the ampliier
Z6 can be adjusted, the sight aid can be adjusted if the brightness
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conditions alter. In other words, the signal lev~l at the output
of the receiver can always be maintained at the same value
irrespective of whether the user is in bright day-li.ght or in
a comparatively dark room.
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