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Патент USA US2114939

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April 19, 1938. '
A. A. RADTKE
2,114,939 ,
METHOD OF AND MEANS FOR OPTICALLY REPRODUCING SOUND
Filgd Dec. 27. 1922
s SheetQ-Sheet 1
April 19; 1938.
-'
A. A. RADTKE
>
2,114,939
METHOD OF AND MEANS FOR OPTICALLY REPRODUCING SOUND
Filed Dec. 2?. 1922
,
'
5 Sheets-Sheet 2
April 19, '1938.
A. A. RADTKE
2,114,939
METHOD OF AND MEANS FOR,OPTICALLY REPRODUCING SOUND
Filed Dec. 27. 1922
3 Sheets-Sheet 5
'
2,114,939
Patented Apr. 19, 1938
UNITED STATES PATENT ‘OFFICE
2,114,938
7
METHOD OF AND MEANS FOR OPTICALLY
REPRODUCING SOUND
Albert A. Badtkc, Chicago, 111., assignor, by mesne
assignments, "to Badtke Patents Corporation,
New York, N. Y., a corporation of New York
Application December 2'1, 1922, Serial No. 609,196
83 Claims.
' (Cl. 179-1003)
- This invention relates to means for recording
and reproducing sounds, especially musical
sounds and articulate speech.
5
The general object of the invention is to devise
a method of and provide means for the optical
recording and reproduction of sound, through
the instrumentality of a traveling photographic
strip, such as a motion picture ?lm.
Although I am aware that attempts have here
10 tofore been made to achieve this broad purpose, I
15
'20
seek, by the present invention, to provide an im
proved optical sound recording and reproducing
system which shall be free from the defects of
those heretofore proposed, practical and accurate
in its action, and which shall be readily capable
of commercial application to the production of
so called “talking motion pictures”, to the re—
cording of speeches, court proceedings, and for
proved type of record, in combination with an
improved method of causing its image to act
upon the photo-electric cell, whereby the cell is
kept constantly energized, and thus rendered still
more effective in its reproducing action.
Other objects of the invention will hereinafter
appear, as the description proceeds. In order
that the invention may be more readily under
stood, and its nature better comprehended, ref
erence is had to the accompanying illustrative 10
drawings, forming part of this speci?cation, and
in which:—
Fig. l is a diagrammatic view conventionally
showing one arrangement of my improved elec
tro-magnetic optical sound recording apparatus;
Fig. 2 is a similar view showing my improved
reproducing apparatus; >
.
other purposes for-which mechanical recording
Fig. 3 is a front view, on an enlarged scale,
showing one form the beam of light may take,
devices are now employed.
and illustrating the manner in which it is used
The invention contemplates impressing upon a
beam of light, by means of a telephone transmit
ter and an electro-magnetic device, fluctuations
or variations corresponding in frequency and in
tensity to the sounds to be ‘recorded, and pro
jecting this ?uctuating or vibrating beam of light
upon a traveling sensitized ?lm, so that a photo
graphic record is made. This record is then re
converted into sound by passing it in front of a
30 source of light, so that the resultant ?uctuating
beam is projected onto a light sensitive device
known as a photo-electric cell, the varying cur
rents thus set up corresponding to the pitch and
intensity of the original sound. These currents
are extremely feeble, however, and it is therefore
necessary to increase their strength. This I do
by cooperatively connecting the photo-electric cell
in circuit with a suitable thermionic ampli?er, to
which is also connected a telephone receiver
40 or “loud talker", in which the sounds are repro
duced.
A speci?c object of the invention is to so ar
range the circuit connections of the photo-elec
In
to produce a record on the ?lm;
Fig. 4 is a front elevation, on an enlarged scale,
of the photo-electric cell, showing my novel
shield attached thereto;
Fig. 5 is a conventional showing of a fragment
of the ?lm, having thereon a photographic rec
ord of such a nature as might be formed by the
spot of light shown in Fig. 3;
Fig. 6 is a diagrammatic view, somewhat simi
larhtoqliiigq‘l, ‘but showing a slightly diiferent
method of producing-the recording beam;
30
Fig. 7 is a view similar to Fig. 3, but showing
the shape of the beam illustrated in Fig. 6; and
Fig. 8 is a view similar to Fig. 5, but illustrat
ing a record of such a nature as might be formed
by the spot of light or image shown in Fig. '7.
Referring to the drawings in detail, and more
particularly to Fig. 1 thereof, I designates a
powerful electro-magnet of the horseshoe type,
supplied with current from suitable mains l0, 40
and having a pair of pole pieces 2 and 3. These
pole pieces are arranged with their ends in close
proximity and are preferably made tapering so
as to produce a very intense magnetic ?eld be
tric cell and ampli?er as to secure a maximum
45
.
This so arranged ’ tween them.
Suspended in any suitable way between the
circuit combining a photo-electric cell and am
pole pieces 2 and 3 is a bi-?lar conductor or
pli?er is important not only in sound reproduc
45 of eiiiciency in reproduction.
tion but is speci?cally itself'important and as
stated above an object of this invention particu
larly in that it is capable of transforming high
speed light variations through the feeble energy
responses of ‘a photo-electric cell into corre
sponding current impulses of substantial and
readily usable values.
Another speci?c object is to provide an im
55
looped ?lament I, preferably having its strands
extending parallel with the pole pieces. A tele
phone transmitter 1 associated with a suitable 50
battery 0, is arranged to receive the sound to be
recorded or transmitted, and serves to convert
such sounds in the well known way into variable
currents, which currents are impressed upon the
looped ?lament 4, either directly, or by means
2
2,114,939
of the usual transformer or induction coil I, 6.
In other words, sounds'striking the diaphragm
of the transmitter ‘I will cause currents to ?ow
in the ?lament l proportional in strength and
frequency to the intensity and pitch of the
sounds.
.I
.
. According to the well known law, that a cur
rent ?owing through a conductor in a magnetic
field will cause such conductor to move, it is ob
vious that the' looped ?lament 4, due to the vari
able currents which transverse it, will be thrown
into a state of vibration, such vibration being
synchronized with the vibrations of the sound
. which strike the diaphragm of the transmitter.
In order to transform the sound waves into
their optical equivalents, I propose to impress
upon a beam of light, ?uctuations corresponding
to the vibrations of the filament 4. This may be
done by interposing such ?lament directly in the
20 path of the beam of light so as to intercept it
to a greater or less extent, but as shown in the
drawings, I produce the desired e?ect by mount
ing a very small and light mirror 9 upon the
?lament 4, so that the mirror partakes of the
vibrations of the ?lament.
An electric lamp ll of the incandescent type
and preferably having ‘a concentrated ?lament
is supplied with current from the mains i0 and
is mounted in a housing II which is provided with
80 condensing lenses it of any suitable character.
Beyond the lenses I 3, I preferably provide the
housing with a projecting funnel shaped tube or
nozzle‘ I‘, having a restricted open end M through
which a small beam of light is projected onto the
35 mirror 9, as indicated by the dotted line 2:.
This incident beam is re?ected from the mir
ror 8 in some such direction as indicated by the
dotted line 1:, and is caused to fall upon a shield
of light stands still in the position shown in Fig.
3, and the ?lm it travels, it is obvious that a
photographic record will be made consisting of
but a simple band of uniform width, that is to
say, of a width equal to that of the beam or spot
of light a. When, however, this beam or spot of
light is caused to ?uctuate'or vibrate laterally,
as the ?lm moves, it is obvious that teeth or pro
jections will be formed photographically at each
side of the central band above referred to, as the l.
spot of light makes its excursions to one side or
the other of its central position.
.
In Fig. 5, I have endeavored to correctly repre
sent theappearance of a record strip produced
by the abovedescribed apparatus. The photo-~
graphic record on the strip, when developed, will
show a central band b having at each edge there
of a series of teeth or projections c, the length
of these teeth being proportional to the ampli~,
tude of the vibrations, that is, to the intensity of ;
the sound, and the distance between these teeth
being inversely proportional to the frequency of
the vibrations, that is, to the pitch of the sound.
Owing to the great di?iculty of properly repre
senting such a record by a line drawing, it is not
intended to convey the impression that Fig. 5
depicts an actual photographic record with any
substantial degree of accuracy, but it is intended
to merely represent in a conventional way the
general character of such a record, namely, that
it comprises a central band with teeth or projec
tions at opposite sides thereof. While in the
drawings it has been necessary to show these
teeth as sharply de?ned, in an actual record they
will, of course, be more or less “fuzzy”, and
vague in their form. The size and number of
these teeth or projections will, however, corre
spond actually with the intensity and pitch of
plate ll, having a narrow slit or slot 20 extending the sound being recorded.'
40 across the same. Behind the shield plate is, a
In Fig. 2, I have diagrammatically illustrated
photographically sensitized strip or ?lm i5 is an arrangement by means of which a photo
caused to travel, such strip or ?lm being of the graphic record of the type shown in Fig. 5 may
same nature as that commonly employed for _be converted again into sound. Referring to
motion pictures. For simplicity of illustration, ‘this ?gure, Ii’ designates the developed ?lm or
45 this strip I! is shown in Fig. l as being carried record strip, or rather, a positive print from such
upon two reels l6 and H, the latter reel being strip, and it is shown as wound upon the same
driven by an electric motor l8, supplied with. reels l6 and II, the latter being driven by a motor
current from the mains It. In practice, however, i8. A suitable lamp II is mounted in a housing
50
such an elementary arrangement would not, of
course, be operative because of the fact that the
reel ll would constantly increase in diameter as
the ?lm was wound upon it, and would thus
» cause the ?lm to travel past the slit 20 with an
l2’ having condensing lenses ill’ arranged in
front of an aperture it’, through which a con
centrated beam of light is projected. The record
strip I5’ is placed in the ‘path of this beam, and
is caused to travel past a slit 2| in a shield plate
ever increasing velocity. In an actual machine, , i9, similar to that described in connection with
55 the ?lm would, of course, be driven by'a sprocket
-wheel or the like, independent of the take-up
reel.
Referring now to Fig. 3, I have here endeavored
to illustrate the general appearance of a spot of
light caused by the projection of such a beam in
the manner described. It will be seen that this
spot of light, which I have designated a, is of
relatively great width and'length as compared
with the width of the slit 20, so that the larger
part of the spot of light falls upon the shield
plates II, and only a comparatively small part
passes through the narrow slit and impinges upon
the sensitized strip or film.
_
.
If, new, sounds such as music or articulate
speech are produced in front of the transmitter
‘I, themirror 9 will be caused to vibrate in syn
chronism with the-sound waves, and the spot of
light a, in Pig. -3, will be caused to ?uctuate or"
oscillate laterally from side to side,_ traveling
back-and forth along the slit 2.; when the spot
Fig. 1. That part of the beam of light passing
through the record strip and the slit 20 serves to
project the image of a n
w but ever changing
portion of the record upon suitable receiving
apparatus.
.
This receiving apparatus comprises as one of
its essential elements, what is known as a photo
electric cell, designated in its entirety by the
reference numeral II. This cell which is shown
diagrammatically in Fig. 2 and in more detail
in Fig. 4, comprises an evacuated glass vessel or
bulb having its inner surface coated with a light
responsive material, such as potassium, as indi
cated at 22. The inside of the bulb is usually
?rst silvered like a mirror and the potassium
coating is then applied thereto. Two electrodes 70
ane sealed into the glass and enter the interior
of the bulb, one of these electrodes, designated
at 2! in Fig.2, making contact with the sensi
tive coating of the cell and constituting the oath
ode, and the other electrode comprising a ring
.
2,114,939
shaped grid, supported at the center of the bulb,
as indicated at 24 in Fig. 2. It is not thought to
be necessary to devote further space to the dis
cussion of the details of construction or the the
ory of ‘operation of such a photo-electric cell, as
it has now become a well known piece of appa
ratus.
Su?ice it to say that when in darkness,
3
strip or screen the maximum variation will be
equal to the ratio between the combined area of
the teeth 0’ and practically zero. Thus, a much
greater percentage of variation can be obtained.
There is another important point to be noted,
however. I prefer to make the width of the strip
v23 slightly less than the width of the. central
the resistance between the cathode 25 and the
anode 24 is almost in?nite, but this resistance
10 is reduced and the cell rendered conductive~ in
portion b‘ of the image, so that even at those
moments when the image is without teeth or
projections c’, that is to say, in moments of 10
proportion, as light falls upon the active or sen- ' silence, the cell will never be wholly deenergized
sitive material with which the interior of the but will be maintained in an active condition by
cell is coated. That is to say, the stronger the reason of the slight leakage of. light past the
illumination of this sensitive coating, the greater screen or strip 23, such leakage being due to the
the conductivity of the path between the elec
trodes. Thus, when connected with a suitable
battery, and exposed to a ?uctuating beam of
light, correspondingly varying currents are caused
to flow through the cell.
Perhaps better ex
pressed-electrons are emitted by the cathode in
proportion to the quantity of light striking it
and they are attracted to and carried away by
the positive anode. This action has no inertia
and no lag but has almost no energy value.
In order that light may enter the cell and pro
v.
duce the e?ect just described; it is formed with
an uncoated area 23IL which is substantially
transparent, such transparent portion or “win
dow” being opposite the cathode 25.
The beam of light. projecting the ever vary
ing image of the photographic record on the
strip 15', is directed toward the window 2Z1a as
“indicated by the dotted line 2 in Fig. 2, so that
this ?uctuating or varying beam may produce
corresponding variations in the resistance of the
cell.
In Fig. 4, I have endeavored to indicate, by the
white area at the center, the appearance of the
spot of light caused by the projection of the ever
varying image of the photographic record, as the
?lm travels past the slit 20. It will be noted
that this image or spot of light comprises a cen
tral portion b’ corresponding to the central band
b in Fig. 5, and more or less of a tooth or pro
45 jection c’ on each side, corresponding to the
teeth or projections c in Fig. 5. As the ?lm trav
els past the slit, these projections 0' will, of
course, vary from instant to instant in length
slight overlapping of the central portion b’ of the 15
image beyond the side edges of the screen or
strip 23. I have foundv that the cell responds
more readily from a slightly energized condition
than from a condition of zero energization.
Referring again to Fig. 2, I propose to combine 20
with the photo-electric cell just described, one or
more ampli?ers of the thermionic type, one only
of such ampli?ers being shown in the drawings.
The ampli?er is designated in its entirety by
the reference numeral 29 and comprises the usual 25
grid 23, plate 31 and ?lament 35, the latter be
ing maintained at a suitable temperature by
means of a battery 36 and constitutes the cathode
of’ this thermionic electronic ampli?er. The grid
28 of the amplifier is connected directly by a 30
link-means shown in the form of a conductor 21
to the cathode 25‘of the photo-electric cell. The
battery employed in connection with the ampli
her and photo-electric cell is of any suitable volt
age and is shown as comprising three sections, 35
3!, 32, and 33. The voltage of the sections 3|
and 32 in series are applied to the electrodes of
the photo-electric cell, the negative side of the
section 3| being connected to a point 26 in the
conductor 21 through a high resistance 30, and 40
the positive side of section 32 being connected
at 32‘ by means of a conductor 40 with the anode
24 of the photo-electric cell. The filament 35 of
the ampli?er is connected by a conductor 34 to
the junction point 3|‘, and a telephone receiving 45
set 39, or other electro-magnetic sound produc
ing means is connected in circuit by means of a
conductor 33 with the plate 31 and the positive
side of the battery section 33.
It will be particularly noted that the imped 50
and width, while the central portion 1)’ of ‘the
image remains'practically constant. The vari
ations in the quantity of light thus entering the
window of the cell would probably be su?icient
ance 30, which is shown as a pure ohmic resist
to cause it to respond, but I‘have found that the
cell works very much more e?iectively it this
same order of magnitude as?that of the photo
central portion of the image be obliterated and
not permitted to act upon the cell. To this end,
I place across the window 23a of the cell, a strip
or band 23 of opaque material, such strip or band
extending parallel with the record ?lm and ‘be
ing of a width equal to or preie‘nbly slightly.
less than the width of the image b’ of the cen
tral band b of the record. The image of this
central band portion thus falls upon the opaque
strip 23 and hence is obscured and prevented from
entering the cell, the only light passing into the
cell .being that due to the teeth or projections c’.
It is obvious that such an arrangement produces
a much more elective operation of the cell be
cause with it the greatest percentage of varia
70 tion of the light is produced as successive .teeth
or projections of the image pass through the win
dow. Without the strip or screen 23, the maxi
mum variation of light would he only- in the ratio
of the area of the entire white spot to the area
of the central portion b’ thereof, while with the
ance,- must be relatively high and the best results
can be obtained when this resistance is of the
electric cell.
'
_
With apparatus arranged as above described
and as shown in Fig. 2, it will therefore be ap
parent that as the ?uctuating beam of light or
varying image is projected into the photo-electric
cell, the conductivity of this cell will be corre 00
spondingly varied and a pulsating current will be
caused to ?ow through the cell from the battery
sections 3| and 32 over the conductors 40 and
33', including the resistance 30. As the current
through this circuit varies, the presence of the
resistance 33 will cause the potential at the point
23 to rise and fall in proportion to changes in
the value of the current, and this varying poten
tial will be transmitted by the conductor 21 to
the_grid 33 of the ampli?er. Thus, in-__a well
known way, greatly modi?ed currents ar'etset up
through the receiver 33, such currents varying in
exact synchronism with the current variations in
the circuit through the photo-electric cell and
consequently in exact synchronlsm with the line
4
2,114,939
. tuations in the beam of light projected into such
v cell.
By this means, the photographic record on
the strip or ?lm It’ is recohverted into sound in
the receiver‘ 39. Thus, the sound originally im
pressed upon the transmitter 1 is electro-mag
netically and photographically recorded on a sen
sitized strip, and is then reproduced, with all of
impressed, such, for example as the re?ected
beam 1/ in Figs. 1 and 8,,may be caused toim
Dinge directly upon the photo-electric cell shown
in Figs. 2 and 4, instead of upon a photographic
record strip, thus constituting a method for the
optical transmission and reception of sound over
short distances, and it will be understood that I
its original qualities, by causing a positive print . regard this method as forming part of the present
of such record strip to produce a ?uctuating beam
.10 of light which acts upon a photo-electric cell,
thereby setting up feeble variable currents which
are then suitably ampli?ed and converted into
sound by an electronic ampli?er operating elec
tro-magnetic receiver.
-
,During the development of this invention, I ex
perimented with an incandescent lamp of that
“type in which the ?lament consists of a closely
woven helix of fine wire... and with such a lamp,
I succeeded in producing photographic sound rec
ords presenting an appearance quite different
from that shown in Fig. 5. . In Fig. 6, such a
helical ?lament is shown at 4|. By means of a
invention.
.
_
~
My continued experience with my combination
of photo-electric cell and electronic ampli?er in
high speed work shows that the photo-electric
cell electrode linked to the grid of the ampli?er
10'
’ imparts to the grid instantaneous potential
changes with only an average but more slowly 15
varying potential being maintained by the imped
ance 30. This impedance 3! ?oats the grid 2!
and imparts a normal negative bias by battery
sectionjl but holds it subject to instantaneous
potential changes in proportion to electrons emit— 20
ted by photo-electric cathode 22. This imped
ance It is an electron restorative impedance, elec-‘
trons ?owing under the electric motive force of
condensing lens 42 and tube 43, the image of the
?lament 4| is thrown upon the mirror 9, carried sources SI and 32.
‘
by the 'bi-?lar conductor 4, as indicated at :r.
It should be noted that no batteries are located 26
and this image is in turn re?ected onto the shield in the link means shown as conductors 2|, 2‘ and
plates I! as indicated at y, the image itself being 21. were any included ‘in this highly sensitive
designated at d.
connection the capacity coupling to ground and
In Fig. 7, I have endeavored to show an en-* the large parts (batteries) connected with cathode
larged detailed view of the appearance of this ~' 35 would shunt out nearly all high frequency po 30
fragment of the image of the ?lament ll as it tential variations. The grid 2! and its activating
appears when thrown upon the shield plates I! photo-electric cell electrode must freely iioat for
having the slit 20 formed in them. ' The image (1 faithful operation of the ampli?er.
,
comprises a bright ' zig-zag line having sharp
Although I have shown much only in diagram
points d’, corresponding to the convolutions of I contemplate the use of the best instrumentali
the helix of the original‘?lament. The slot 20_
known to the art for moving ?lm without
is preferably of such width as to permit only that ‘ties
change in speed,' producing steady light and sup
portion of the image corresponding to a single plying electric potentials. I have shown and de
convolution to pass through.
scribed how to use them for good results.
40
I have found that when such an image is vi
What I claim is:—
'
40
brated transversely of the record strip, sheet or
1. Means for converting a ?uctuating beam of
?lm by means of the variable currents in the bi
light into sound, comprising a photo-electric cell
?lar conductor 4, a record is produced having ‘on to which the beam is projected, a telephone
somewhat the general appearance as that indi
receiver, a source of current, and an electronic
cated in Fig. 8. This record comprises a central ‘ ampli?er. operatively connected with said cell,
band e of more or less uniform width, similar to
source of current, and receiver.
the band b in Fig. 5, but on eachside of this band
2. Means for converting a ?uctuating beam of
e are a large number of exceedingly ?ne teeth I.
light into sound, comprising a photo-electric cell
In practice, these teeth are so ?ne and so close
on to which the beam ~is projected, said cell hav
50 together that they present the appearance of a
ing a pair of electrodes, a current source having
series of light and dark lines. It is of course, opposite poles connected to said electrodes, an
impossible to properly represent this record in an electronic ampli?er having its grid connected di—
ink drawing, but Fig. 8 is intended to merely ,
rectly to one of said electrodes, and a telephone
indicate its general nature. In an actual record, receiver operatively associated with said ampli
of course, the central band and the teeth or lines
are not sharply de?ned, but are more or less hazy
3. The combination with means for producing '
and merge the one into the other. Moreover, at a beam of light ‘?uctuating with a frequency
certain parts of the film, the lines or teeth are corresponding to that of sound waves, of a photo;
crowded much more closely together than at .
electric 'cell comprising an evacuated vessel hav
other parts, thus corresponding to sounds of dif
ing a cathode having on its inner surface a light
?er.
ferent pitch. In this connection, it will, of course,
be understood that the travel of the ?lm or record
strip past theslip 20 is relatively slow, as com‘
pared with the frequency of vibration of audible
The slower the speed of travel of the ?lm,
obviously the smaller space a given record will
65 sound.
occupy.
'
From the foregoing, it will be seen'that I have
‘devised a novel and effective method for optically
recording and reproducing sound, including artic
ulate speech, audit is thought that the many ad-v
vantages and useful applications of the invention
will be apparent without further discussion.
It is, of course, obvious that the ?uctuating
75 beam of light on which ‘the sound vibrations are
~
‘
‘
sensitive coating containing an alkali metal, said
cell being so arranged that the ?uctuating beam
fallsv upon said lalkali'metal coating, a current
source suitably connected in a circuit including
said cell, whereby said ?uctuating beam sets up
variable currents ‘of feeble intensity, a several
element vacuum tube arranged to amplify such
feeble currents, and a device for converting into
' sound the currents thus ampli?ed.
_ 4. The combination with means for producing
v70
a beam of light ?uctuating with a frequency cor~
responding to that of sound waves, of a photo
electric cell arranged in the path of said beam.
said cell comprising an evacuated. vessel‘ having
a cathode having on its interior
a light 75
I.
5
2,114,939
sensitive coating containing an alkali metal, con
ltituting one electrode, and provided with another
electrode, a thermionic ampli?er having its grid
directly connected with one of said electrodes, a
current source suitably connected with said
ampli?er and with the other electrode, and a tele
phone receiver operatlvely associated with said
ampli?er.
.
5. Means for converting a ?uctuating beam of
10 light into sound comprising a photo-electric cell
on to which the beam is projected, said cell hav
ing a pair of electrodes, a battery, conductors
connecting‘ opposite poles of said battery with
said electrodes, one of said conductors containing
15 a relatively high ohmic resistance, a thermionic
ampli?er having its grid connected to said last
mentioned conductor at a. point between said
resistance and the cell electrode, and a telephone
receiver operatively connected in the plate circuit
ofsaid ampli?er.
-
6. The electro-optical method of reproducing
sound which comprises generating a beam of light
which ?uctuates in synchronism with the vibra
tions of the sound to be reproduced, causing such
?uctuating beam to set up,‘ in a suitable circuit,
electric currents varying in absolute synchronism
with said beam, thermionically amplifying such
currents, and converting the energy of the ampli
?ed currents into sound waves.
'7. The combination with a photo-electric cell
having two electrodes, and a current source con
nected with said electrodes, of means for amplify
ing feeble variations of current ?owing from said
battery through said cell comprising a purely
ohmic resistance inserted in the circuit between
the battery and one electrode, and ‘a thermionic
ampli?er having its grid connected directly with
said last mentioned electrode and its cathode with
an intermediate point of said current source.
8. The combination with a photo-electric cell
having two electrodes, and a current source con
nected with said electrodes, of means for amplify
ing feeble variations of current ?owing from said
current source through said cell comprising a
45 ?xed ohmic resistance of the same order of mag
nitude as that of said cell inserted in the circuit
between the battery and one electrode, and a
thermionic ampli?er having its grid connected
directly with said last mentioned electrode and
its cathode with an intermediate point of said
current source.
-
9. The method of effecting a photo-electric cell
by means of a ?uctuating beam of light, which
comprises obscuring the central part of said
beam, and exposing the cell only to that-part of
the beam of a width in excess of such obscured
portion.
10. The method of e?'ecting a photo-electric
cell by means of a ?uctuating beam of light which
varies in width from a de?nite ?xed minimum >
to an inde?nite maximum, said method compris
ing shielding the cell from being acted on by the
beam when at its minimum width, and exposing
it only to that variable portion of the beam which
exceeds such width.
_
11. The method of e?ecting a photo-electric
cell by means of a ?uctuating beam of light 0!
variable width, which comprises exposing the cell
to'those portions only of the beam which exceed
a de?nite minimum width.
12. The method of optically reproducing sound
which comprises setting up a ?uctuating beam of
light which varies in accordance with the sound,
75 and projecting this beam upon a photo-electric
cell in such a way that the cell is continuously
energized, whereby its conductivity never'drops
to zero, but varies between maximum and a
de?nite minimum.
-
'
13. A photo-electric cell comprising an evacu
ated vessel having its interior coated with light
responsive material, and having an uncoated area
constituting a “window", the central portion of
said window being opaque, with transparent por
tions at each side thereof.
14. A photo-electric cell comprising an evacu
ated vessel having its interior coated with light
responsive material, and having an uncoated area
constituting a “window”, and an opaque strip or
ll
shield extending centrally across said window.
15. The combination with means for generating
a ?uctuating beam of light which varies in width
from an inde?nite maximum to a definite mini
mum, of a photo-electric cell onto which said
beam is projected, said cell comprising an evacu
ated vessel having its interior coated with light
responsive material, and having a. transparent
“window” through which the light enters, and a
strip of opaque material of substantially the same
width as the said minimum width of the beam
extending across said window.
16. The combination with a record strip having
a transparent record thereon, said record com
prising a central band and teeth or projections
extending from each edge thereof, of means for
causing said record strip to travel, means for pro
jecting the image of said transparent record as
the strip travels past a slit, a photo-electric cell
having a transparent “window" on which said
image is projected, and an opaque strip or shield
of substantially the same width as the image of
the central band portion of said record extending
across the window and serving to prevent that
portion of the image from entering the window
and a?ecting the cell.
1'7. The combination with a circuit‘ having con
nected in series therein a photoelectric cell, a
20
25
30
35
40
source of electromotive force and an ohmic resist
ance, of a thermionic ampli?er having its grid
connected to said circuit at a point between the 45
ohmic resistance and the photoelectric cell, and
having its cathode connected to a point of inter
mediate potential in said source of electromotive
force.
'
18. Means for optically producing sound, in 50
cluding a. sheet or the like having relatively
opaque and transparent portions, a source of
light, a photo-electric cell comprising an evac
uated vessel having a cathode having on its inner
surface a light sensitive coating containing an
alkali metal, said source of light being so arranged
as to direct a beam upon said alkali metal coat
ing, and said sheet being interposed between said
source and said cell, means for rapidly moving
said sheet so as to cause the relatively opaque
and transparentportions thereof to successively
pass across the path of said beam at a speed equal
to the frequency of sound vibrations, a current
source suitably connected in a circuit including
said cell, whereby the ?uctuating beam produced 65
by said moving sheet sets up similarly varying
currents of feeble intensity, 9, three-element vac
uum tube arranged to amplify such feeble cur
rents, and a device for converting into sound the
70
currents thus ampli?ed.
19. The electro-optical method of producing
sound which comprises forming on a sheet or
strip a series of lines or hands having optical
properties in contrast with those of said sheet,
directing a beam of light upon said sheet, mov 75
6
2,114,989
ing said sheet in such manner as to cause said
beam, after leaving the sheet, to ?uctuate with a
frequency equal to that of sound vibrations, caus
ing such ?uctuating beam to set up, in a suitable
circuit, electric currents varying in absolute syn
~source having a connection with said cathode and
chronism with said beam, thermionically amplify
tial variations to said grid corresponding to those
which take place on said body in response to said
ing such currents, and converting the energy of
the ampli?ed currents into sound waves.
20. Sound producing apparatus comprising a
10 photoelectric cell having an anode and an alkali
cathode, means for illuminating the cell and for
varying such illumination at a rate correspond
ing to the frequency of sound waves, and a circuit
connected with the electrodes of said cell and con
15' taining a source of electricity, in which circuit
?ows a correspondingly varying feeble current
and an electronic ampli?er external to but cou
pled to said circuit.
.
.
21. Sound producing apparatus comprising,‘ in
combination, a photoelectric cell having an anode
and an alkali cathode, and capableof responding
' to light variations of a frequency equal to that-of
sound waves, a source of light for illuminating
said cell, a movable light-varying element inter
posed in the path of the light rays between said
sourceand' said cell, a circuit connected with the
leading to said cathode~body and the positive ter
minal of said sourcev leading to said anode; and
a link-means electrically connecting said cathode
body and said grid and adapted to impart poten
light impulses, whereby appreciable corresponding
impulses in electron-?ow to said plate are effected.
26. In combination a photo-electric couple in a 10..
cooperative atmosphere; a current-strength-con
troller operating by reason of changes in poten
tial; a link-means electrically connecting one elec
trode of said photo-electric couple with said our
rent-strength controller and adapted to impart
potential variations to said controller correspond‘
ing to those which take place on said electrode;
and provisions tending to produce and maintain a
negative normal potential for the cathode of said
‘photo-electric couple, but said provisionsbeing
20
incapable of maintaining an unchanged normal
potential upon that electrode of said photo-elec
tric couple which is electrically connected with
said current strength controller.
2'7. In combination a photo-electric-cathode
body exposable to light variations and in a coop-_
electrodes of said cell and containing a source of .' erative atmosphere; a grid ‘which controls a cur
current, an electronic ampli?er external to but rent flow by reason of potential; and a link
coupled with said circuit-and an electrical sound
producing device associated with said ampli?er
and operated by current ?uctuations correspond
ing with said light variations.
22. Sound producing apparatus comprising a
photoelectric cell having an anode and an alkali
85 cathode, means for illuminating the cell and for
varying such illumination at a rate corresponding
to the frequency of sound waves, an ampli?er, a
circuit connecting said cell with said ampli?er, a
sound producing device, and a circuit connecting
said ampli?er with said sound producing device.
23. Sound producing apparatus comprising, in
combination, a photo-electric cell having an an
ode ‘and an alkali cathode, a circuit connected
with the electrodes of said cell and containing a
45 source of current, an electrical sound producing
means between said cathode-body and said grid
to control the potential of said grid by potential 30
changes in said cathode-body; and provisions
in addition to said link-means tending to main
tain a fixed charge on said cathode-body.
28. Means in combination for transforming
light impulses into electric current impulses in
cluding an electron emitting cathode, a grid and
a plate: a plate circuit including a source of di
rect current and forming the circuit for said
current impulses; a photo-electric cathode-body;
an anode for said photo-electric cathode-body; an
electric connection between said photo-electric
cathode-body and said grid of such character as
to impart substantially instantaneously'a change
of potential in said photo-electric cathode-body
to said grid; provisions in, addition to said electric
connectlon‘between said photo-electric cathode
device operatively associated with said circuit, a
source of light for illuminating said cell,‘ and body and said grid for negatively charging said‘
means for causing the illumination of said cell ' photo-electric cathode-body; andprovisions for
to vary at‘ a rate corresponding to the frequency exposing said photo-electric cathode-body to light
ofsound waves, said means including a movable
element interposed in the path of the light rays
impulses, whereby substantially ' instantaneous
between said source and said cell.
light impulses are made by the instantaneous lib
24. Means in combination for transforming
light impulses into electric current impulses com-'
prising a cathode, a‘grid and a plate, a plate cir
eration of electrons from said photo-electric
cathode-body to e?ect simultaneous potential
changes upon said grid whichin turn e?‘ects cor
responding appreciable current changes in said
cuit including a‘ source of‘ current for the trav
erse of said electric current impulses; a photo
electrostatic potential changes in response to said
plate circuit.
'
electric body adapted to be subjected to light im
29. A method of transforming light variations
pulses; an envelope for maintaining said body in into electric current variations which comprises
a cooperative atmosphere; provisions tending to~ submitting a photo-electric body to the potential
. produce and maintain a negative normal potential
(50
restoring in?uence of a ‘source of negative charge
for said body but themselves incapable of main ~ capable of substantially completely restoring the
taining said potential when said body is being potential of said photo-electric body after elce- '
subjected to light; and a'link-means electrically - trons are emitted therefrom in response to light,
65 connecting said body and said grid and adapted. but incapable of maintaining the potential of said
to impart potential variations to said grid corre
photo-electric body when it is being subjected
sponding to those which take place on said body. > to light; subjecting said photo-electric body to
_ 25. In combination, a photo-electric couple the action of a variable source of light-and thereby
having an envelope to maintain it in a cooperative, effecting corresponding potential changes in said
atmosphere and comprising a photo-electric cath
photo- ectric body ; and imparting the ‘controlling
ode-body, adapted to be subjected to'lig'ht 1m .e?ect of ~said potential changes in said photo 70
pulses, and an anode; a cathode. a grid and a electric body to' thestream of cathode'emitted
plate; a source of direct current and aileakage free electrons of a’ plate circuit.
_ .
resistance connected in series Lwith said‘sphoto
30. In sound reproducing apparatus, the come
to
vi'is ,
electric couple, the negative terminal of said bination‘of a photoelectric cell having an alkali 75
7
2,114,939 '
cathode, means for illuminating the cell with
acoustically-modulated light, and a circuit in
cluding an electronic ampli?er which ampli?er
is connected with said cell in which said circuit
?ows a correspondingly modulated current.
31. In sound reproducing apparatus, the com
bination of a photoelectric cell having an alkali
cathode, a constant source of light, means for
uniformly progressing a ?lm between said source
and cell, said ?lm carrying a photographic sound
record of varying opacity, so that said cell is illu
minated by acoustically-modulated light, which
has passed through the ?lm, and a circuit includ
ing an ampli?er coupled with said cell in which
flows a correspondingly modulated current.
32. In sound reproducing apparatus, the com
bination of a photoelectric cell having an alkali
cathode, means for illuminating the cell with
acoustically-modulated light, an ampli?er. a cir
cuit connecting said cell with said ampli?er, a
sound reproducing device, and a circuit connect
ing said ampli?er with said sound reproducing
device.
-
-
,
33. In sound reproducing apparatus, the com—
said source of light and said cell for modulating
thelight reaching said cell from said source; said
strip carrying an optical sound record varying
lengthwise thereof, so that said cell is illuminated
by acoustically modulated light, which has
passed from said source to said strip and to said
cell; and a circuit connected with said cell and
including an electronic ampli?er in which ?ows
a correspondingly modulated direct current.
38. In sound reproducing apparatus, the com
bination of a photoelectric cell having an alkali
cathode, a constant source of light, means for
uniformly progressing a ?lm between said source
and cell, said ?lm carrying a photographic sound
record of varying opacity, ‘so that said cell is 15
illuminated by acoustically modulated light,
which has passed through said ?lm, and a direct
current ampli?er circuit connected with said cell
in which ?ows a correspondingly modulated di~
rect current.
\
_ -
20
39. In sound producing apparatus from an
optical record, an electrically operated sound
producer requiring modulated dynamic electrical
energy of substantial value for its operation; a
25
25 bination of a photoelectric cell having an alkali ' photoelectric cell having an anode and a cathode
cathode, means for illuminating the cell with
30
capable of emitting electrons in proportion to
acoustically-modulated light, an ampli?er, a cir
cuit connecting said cell with said ampli?er, and
a circuit connected with said ampli?er, in which
incident light and a protecting ‘enclosure having
?ows ampli?ed currents which vary correspond
ingly with the variations of said acoustically-mod
a direct current source of electric exciter po
tential for said photoelectric cell; a vacuum tube
ulated light.
’
34. In sound reproducing apparatus, the com
bination of a photoelectric cell having an alkali
cathode; a source of light substantially constant
relatively to variations within the audible range;
means for uniformly progressing a record strip
through the light ?eld between said source of light
and said cell; said strip carrying an optical sound
record varying lengthwise of said strip.. so that
said cell is illuminated by acoustically modulated
light which has passed from said source to said
strip and thence to said cell; and a circuit includ
ing an ampli?er coupled with said cell in which
flows a correspondingly modulated current.
35. In sound producing apparatus from an
optical record, an electrically operated sound
producer requiring modulated dynamic electrical
energy of substantial value for its operation; a
photoelectric cell having, an anode and a cath
ode capable of emitting electrons in proportion
to incident light and a protecting enclosure hav
ing a transparent portion adapted to expose said
cathode to light modulated by an optical record;
a transparent portion adapted to expose said
cathode to light modulated by an optical record;
ampli?er operatively connected with said sound
producer; and means operatively connecting said
source of exciter potential with said photoelectric
cell and linking said photoelectric cell with said
ampli?er operatively to cause modulated electron
emission from said cathode to e?fect the ?ow of
correspondingly modulated but greatly ampli?ed
currents from said ampli?er through said sound
producer-
'
40
40. In sound reproducing apparatus, the com
bination of a photoelectric cell having an alkali
cathode; means for illuminating said cell with
acoustically modulated light; an ampli?er; a di
rect current circuit connecting said cell with said 45
ampli?er; a sound reproducing device; and a
circuit connecting said ampli?er with said sound
reproducing device.
41. In sound reproducing apparatus, the com
bination of a photoelectric cell having an alkali 50
cathode; means for iluminating said cell with
acoustically modulated light; an ampli?er; a di
rect current circuit connecting said cell with said
ampli?er; and a circuit connected with said am
a source of electric exciter potential for said ' pli?er, in which circuit ?ow ampli?ed currents
‘ photoelectric cell‘: an ampli?er operatively con-' which vary correspondingly with the variations
’
nected with said sound producer; and means of said acoustically modulated light.
operatively connecting said source of exciter po
tential with said photoelectric cell and linking
(26 said photoelectric cell with said ampli?er opera
42. Apparatus operable over a substantial
period of time for transforming small light im
pulses into substantially relatively proportional
tively to cause modulated electron emission from - electric current impulses comprising cooperable
said cathode to eifect the ?ow of correspondingly electrodes of a photo-electric couple including a
photo-electric cathode and its anode, both in a
modulated but greatly ampli?ed currents from
said ampli?er through said sound producer.
_ cooperative atmosphere; a thermionic ampli?er
38. In sound reproducing apparatus,_the com
having a grid, a cathode and‘a plate; a plate cir
bination of a photoelectric cell having an alkali
cathode; means for illuminating said cell with
acoustically modulated light; and a circuit in
cuit for said relatively proportional current im
pulses; a restoration impedance of the order of
cluding an electronic ampli?er which ampli?er
is connected with said cell in which said circuit
?ows a correspondingly modulated direct current.
‘3'1. In sound reproducing apparatus, the com
magnitude'of the apparent impedance between
the electrodes of said photo-electric couple when
its said cathode is being subjected to said light
impulses and said impedance being electrically
connected between the cathode of said thermi
bination of a photoelectric cell having an alkali onic ampli?er and one of said electrodes of
~cathode; a source of light;_means for uniformly . said photo-electric couple; a link means free
progressing an optical record strip relatively to‘ from any substantial capacity coupling or other
00
8
' 2,114,939
coupling except said restoration'impedance with' ‘ subjected to said light impulses; a source of ex
said'cathode of said thermionic ampli?er and _ citing potential for said photo-electric couple
itself linking said one of said electrodes of said
photo-electric couple with the said grid of said
thermionic ampli?er; and a source of activating
electricity connected to the other electrode of
connected ‘at one terminal to the cathode of said
electronic ampli?er and through said restoration
impedance to said one of the electrodes of said
photo-electric couple which is linked to said grid
said photo-electric couple, to the cathode of said - and at the other terminal to the other electrode
thermionic ampli?er and through said restora
of said photo-electric‘couple; and provisions for
tion impedance to said one of said one of said
10 electrodes of said photo-electric couple.
43. The apparatus as de?ned in claim 42 fur
ther characterized by the fact that the link
means is a conductive connection.
"
44. Apparatus operable over a substantial pe
15 riod of time for transforming small light impulses
into substantially relatively proportional electric
current impulses comprising cooperable elec
biasing said grid relatively to its cathode with- ‘
out destroying the control " of its potential by said 10
photo-electric couple.
47.-Means for transforming rapid light im
pulses‘ into faithfully corresponding electrical im
pulses of practically usable magnitudes compris
ing a multi-electrode photo-electric device which 15
has at'least an electron emitting alkali cathode
and an electron collecting anode spaced ‘from
said-cathode in a rarefied cooperative atmos
phere with provisions for maintaining said coop
cooperative atmosphere; a thermionic ampli?er . erative atmosphere, in combination with an elec
having a grid, a cathode anda plate; a plate tronic ampli?er having a control electrode and
circuit for said relatively proportional current an output circuit in which said corresponding
impulses; a restoration impedance of. the order ‘electrical impulses of practically usable magni
of magnitude of the apparent impedance between' tude ?ow; a source of electric potential. and link
the electrodes of said photo-electric couple when means for applying an appropriate activating po
its said cathode is being subjected to said light tential directly to the electrodes of vsaid photo‘
impulses and said impedance being electrically. electric device independently from electronic flow
connected between the cathode of said thermionic in said electronic ampli?er and also for impart
ampli?er and one of said electrodes'oi said photo
ing the controlling effect of light responsive elec
trodes of a photo-electric couple includingi a
photo-electric cathode and its anode. both in a
electric couple; a link means free from any sub
stantial capacity coupling or other coupling ex
cept said restoration impedance with‘ said cathode
of said thermionic amplifier and itself linking
35
said one of said electrodes of said photo-electric
48. The combination for transforming rapid
couple with the said grid of said‘thermionlc am
pli?er; a source of activating electricity con
nected to the other electrode of said photo-elec
tric couple, to the cathode of said thermionic
light variations faithfully into corresponding
electrical variations of readily employable magni
ampli?er and through said restoration imped
40
tude including a spaced-electrode photo-electric
device having provisions for ?xing and maintain
ing its electrodes in a cooperative atmosphere;
ance to saidone of said ‘electrodes of said photo . an electronic ampli?er having parts including a
electric couple; and provisions‘ for selectively control grid, a cathode and an anode; a source of
biasing the average potential of said grid relaf electrical excitation for said photo-electric de
tively to its cathode.
_
45.’ Apparatus in combination for transform
45
tronic ?ow in said photo-electric device to said
control element of said electronic ampli?er to
effect the control of ampli?ed current impulses in
said output circuit of said electronic ampli?er.
ing light impulses into substantially correspond
ing appreciable current impulses over a substan
tial period of time including a photo-electric cou-'
ple having cooperating electrodes in a coopera
tive atmosphere including an anode and a photo
electric cathode; an electronic ampli?er having
a grid, a cathode and a plate; a link means con
vice; means for completing a vcircuit from said '
source to the electrodes of .said photo-electric
device independently of current flow in said elec
tronic ampli?er but including part of a variable
potential link means between said photo-electric _
device and said electronic ampli?er; potential
means and connections for setting a negative
bias for said control grid relatively to its cath
ode and for completing said variable potential
link means to impart output controlling poten
tial variations to said control grid in response to
necting one of the_electrodes of said photo-elec
tric couple directly with said grid; a restoration
impedance. of the order of magnitude of the ap ‘ varying electron .emissions from said cathode
66 parent impedance of said photo-electric couple ot‘sa'id photo-electric device when exposed to
.when subjected to said light impulses; .and a said light variations; and meanszior completing
source of exciting potential forsaid photo-elec
an output circuit for said electronic ampli?er-for ‘
tric couple connected at one terminal to the cath .the ?ow oi‘ electrical energy variation of readily
ode of said electronic amplifier and through said employable magnitude and corresponding faith
tully to said rapid‘ light variations.
restoration impedance ‘to said one‘ of the elec
trodes of said photo-electric couple which is '
49. Electric reproducing apparatus for utilizing
linked to said grid and at the other terminal to light variations corresponding ‘in frequency and
the other electrode of said photo-electric couple. relative variation to sound vibrations, the com
46. Apparatus in combination for transform ' bination of a photo-electric cell having plural
65 ing light impulses into substantially correspond
electrodes including an alkali cathode and an‘ 65
ing appreciable current impulses over a substan
. anode; an electronic ampli?er having an output
tial period of time including a photo-electric con‘
ple having cooperating electrodes in a cooperative
tions corresponding‘ to said light‘ variations}
atmosphere including an anode and a photo-elec
tric cathode;- an electronic ampli?er having a
photo~electric cell with said light variations: and
circuit, for the ?ow of ampli?ed current varia
means ior illuminating said cathode of said
grid, a cathode and a plate; a link means con-' .means including a source of electric energy for
necting one ‘of the electrodes of said photo-elec- ‘ activating-said photo-electric cell and for linking
tric couple with said grid; a-restoration imped
ance of the order of magnitude of the apparent
75 impedance of said photo-electnc couple when
the effect of electron emissions from said cathode
to control said electronic ampli?er independently
of electronic ?ow therein and maintaining said '
>9
2,114,9sc
link me'ans'substantially tree from capacity ecu
pling in shunt to said controlling e?ect.
50. Means for transforming rapid light im
_ tron ?owing in saidelectronic ampli?er to~ produce
ampli?ed current pulsations to said plate cor
_ responding to the pulsations oi the said light.
55. A photocell system comprising a photo
pulses into faithfully corresponding electrical
graphic sound record means, a record ‘track 5.
5 impulses of practically usable magnitudes com
prising, a. multi-electrode photo-electric device
which has at least an electron emitting alkali
cathode and an electron collecting anode spaced
from said cathode in a rare?ed cooperative at
thereon having a plurality of record traces re
garding the same sound, a shield cooperating
therewith and a photocell and ampli?er system
receiving light therefrom for the production of
a usable value of pulsating current correspond- l0
10 mosphere with provisions for maintaining said
cooperative atmosphere, in combination with an
electronic ampli?er having an output circuit in
which said corresponding electrical impulses ‘or
ing to the recorded sound, .
prising an' electron ampli?er member having
cathode grid ‘and plate electrodes, a plate out- 15
practically usable magnitude ?ow; sources of
ll electric potential and link means for applying
put circuit including a source of current; a photo
appropriate activating potentials to the electrodes
electric body, means for applying pulsating light
thereto, an anode and envelope cooperating there
of said photolelectric device and to said electronic
< ampli?er and for linking without ‘distortion the
with, circuit members and a source of potential
e?ects oi the electron emissions from said al-,
kali cathode to control the ampli?ed current im
pulses of said electronic ampli?er free and inde
pendently oi the ?ow- of electrons in said
electronic ampli?er in the activation of said
photo-electric device.
'
58. Means in combination‘ for transforming
light impulses into electric current impulses com
I
tending to produce and maintain a relative nega- 2o
tive potential on said photo-electric body but
incapable of maintaining said potential when said _
body-is illuminated and a link means connected
directly between said body and the grid of said
electron ampli?er member to impart potential 25
‘
51. In combination a plural electrode ‘photo
variations occurring on said body to said grid to
produce electric current pulsations in said plate
electric device having a partially evacuated en
velope enclosing an anode and a photo-electric
_ cathode body; means for applying light pulsa
tions to said cathode body; an electronic amplify
output circuit.
'
a
5'7. In combination, a photo-electric couple, a
potential-operated
'30 ing devic'e having anode, cathode and grid
current-strength-controller 30
device,la link means directly} electrically con- _
electrodes; a source of current and a high im
pedance connected in series with said photo-elec- ' necting an electrode'oi said photo-electric couple
with said current-strength-controller for" convey
'tric device; and a link means cooperating directly
between one of the electrodes of said photo-elec
tric device and the grid 01' said electronic
ing potential variations developed by said photo—
electric couple to said controller; and circuit v35
ampli?er to convey potential variations- of said' members tending to produce and maintain a
normal potential between the electrodes of said
electrode to said grid for in?uencing an electron
photo-electric couple but incapable of maintain
?ow in said electronic ampli?er to produce
ampli?ed current pulsations to said plate corre
40 sponding to the pulsations oi the said light.‘
ing a full potential therebetweem when said‘
photo-electric couple is illuminated with pulsat- _40
52. The combination as characterized in claim ing light rays but permitting said potential
51 but further de?ned by the fact that said link ‘
58. In combination, a photo-electric cathode
means is in the form of a direct current conduc
variations.
tive connection.
45
'~
53. In combination a plural electrode photo
.
,
-\
,
'
,_>
body, means for producing a cooperative atmos
electric device having a partially evacuated en
. rays applicable thereto, an electron ampli?er
device having a grid and a link means between '
said cathode body ‘for directly conveying potential .
variations produced on said cathode,‘ body to said ‘
Grid and a resistive current supply circuit to said 50
a source of current and a high impedance con-' cathode body tending to maintain a ?xed potential v
vice having anode, cathode and grid electrodes;
nected in series with said photo-electric device;
and a link means directly connected between
said cathode body and the grid of the said elec
55 tronic ampli?er to convey potential variations oi
said cathode‘ body to said grid for in?uencing an
_ electron ?ow in said electronic ampli?er to pro‘-,
duce ampli?ed current pulsations to said plate
corresponding to the pulsations oi the said light.
60
.
_~phere thérearound, a source. of pulsating light 45
velope enclosing an anode and ‘a photo-electric
cathode body; means for applying light pulsations
to said cathode body; an electronic ampli?er de
50
_
on said body but incapable of .doing'so when said
body is illuminated.
‘
,
-
I
59. In sound reproducing apparatus, the com-v
bination of a photoelectric cell having a photo- 55
electric cathode, an anode, an evacuated 'envelope/ ’
and an energizing means including a source of.
current cooperating therewith, means,‘ for illu- ,
minating the cell with acoustically modulated.
light, a circuit connected with-said cell in‘ which 60
"?ows a current'modulated inaccordance with the
velope enclosing an anode and a photo-electric modulations, of said light, an ampli?er system
connected to said circuit, and having an output
cathode body; means for applying light pulsa
tions to said cathode body; an electronic ampli?er circuit carrying an ampli?ed current having mod
54. In combination a pluralelectrode photo- '
electric device having a partially evacuated en
device having anode, cathode and grid electrodes;
ulations corresponding to the modulations of 55 '
a source of direct current and a high resistance
said light, and a. reproducergfor converting the
connected in series with said photo-electric de
modulations of said current into sound.
vice, the respective negative and positive terminals
of said source’ being connected respectively to
70 , said cathode body and said anode of said photo
'
60. In sound reproducing apparatus, the com
bination'of a photoelectric cell having a photo
electric alkali cathode, an anode and an evacuatq 70
ed container, is constant source 01' light projecting
electric device; and a direct current‘ conductive. .light
rays “upon said cell, a sound record having
connection, directly connected between said
cathode body and the grid of said electronic variable light controllingele'ments thereon cor-, I
ampli?er. to convey potential variations of said responding to an audible sound, means'ior trav-_
'75 cathode body to said grid for in?uencing an elec-' \ersing said sound record ‘in the path of said rays 75,
,
10
2,114,989 .
between said light and said cell to impress acous ' circuit connected with the plate of said ampli?er
tic modulations upon the lightreaching said cell, in which ?ows ampli?ed currents varying cor
a circuit connected with said cell having a source respondingly with the variations of said acous- '
01' energizing power therein and carrying a mod
tically modulated light.
ulated electric current corresponding to the mod
65. In sound reproducing apparatus, the com- Y,
ulations of said light rays produced by said bination of a photoelectric cell having an alkali
sound record, an electronic ampli?er system con~ cathode, .an anode and an evacuated container,
nected to said circuit having an output circuit in‘ means for illuminating the said cell cathode
which there ?ows ‘an ampli?ed current having with acoustically modulated light, on electronic '
10 modulations corresponding to‘ the modulations modi?er means having a cathode, an anode and
10
impressed upon said light rays by said record, a control electrode, a circuit connecting said cell
and a translating means for converting the mod - with the grid of said‘ ampli?er, a source or power
ulations of said output current into sound.
for said cell also connected in said circuit, an out
61. In sound reproducing apparatus, the com
put circuit connected with the plate of said am
15 bination of a photoelectric cell having a therm
pli?er in which ?ows ampli?ed currents varying
ionic alkali cathode, an anode and an evacuated correspondingly with the variations of said acous
container, a constant source of light projecting tically modulated light and a‘ translating device
light rays upon said cathode, a sound record com
connected to said plate circuit for converting the
prising members for variably controlling the said
20 light rays to provide an acoustically modulated
ampli?ed currents into sound.
.
_
>
66. The method of translating ?lm sound rec
light upon said cathode, means for traversing said ords intoelectrical eii'ects varying substantially
sound record past said light raysv at a substan
in accordance with the sounds originally recorded,
tially uniform rate of speed and a work circuit which comprises controlling the light falling on a
connected to said cell and carrying an electric _ light sensitive cell in accordance with consecutive
25 current modulated in accordance with the said portions of the ?lm sound record and in restrict?
sound record.‘
ing the light so falling on said cell substantially to
62. In sound reproducing apparatus, the com
light variations corresponding to the sounds origi
bination of a photoelectric cell having a therm
ionic alkali cathode, an anode and an evacuated
67. The process of reproducing sound, compris
30 container, a constant source of light projecting
ing impressing light from consecutive portions 01’
light rays upon the said cathode, a sound record a photographic record'upon a single light re
nally
comprising members for variably controlling the
said light rays to-provide an, acoustically mod
_ ulated light upon said cathode, means for travers
recorded.
_
w
-
'
V
a
sponsive device and corresponding to the origi
nally recorded sound.- pulsaticns > and simulta
neously obscuring the light- from said record in
excess of that _ corresponding to the original
substantially uniform ratev of speed, a worlr cir
cuit connected tosaid cell and carrying on elec
68. The. method or translating a photographic
tric current modulated in accordance with the ~ sound record of modulated light into electrical
said sound record, an electronic ampli?er system ‘impulses varying in accordance with the sounds
40, having a grid, a cathode, and an anode, circuit originally recorded, which comprises ?rst sub 40
members connecting said grid to said work cir- '
stantially suppressing the unmodulated com'po
35
ing said sound record past said light rays at a
sounds.
cult, and an output circuit connected to said
plate for carrying a current having ampli?ed
.
'
A
'
-‘
.'
mm of said modulated light record and later ~
translating said sound record into electrical im
modulations corresponding to the said sound pulses
which consist substantially wholly oi’ var
45 record.
iations corresponding to the sounds originally
63. In sound reproducing apparatus, the com
recorded to the substantial exclusion ‘of unmodu
bination of a photoelectric cell having a therm-‘~ ,lated e?ects by impressing consecutive portions
i'onic alkali cathode, an anode and an evacuated of said impulses upon the same light responsive
container, a constant source of light projecting ,
light rays upon the said cathode, a, sound record
comprising members for variably controlling the
said light rays to provide an acoustically mod
ulated light upon said cathode, means for trav
device, thereby translating said impulsesv into
sound,
'-
‘
~
-
69. In a sound translating system, the combi
50
nation of a source of light, a photo cell, an optical ~
record strip‘ movable therebetween, an
ersing said sound record past said light rays‘ sound
ampli?er
associated with said‘ cell and havinga
at 'a substantially uniform rate 01’ speed, a work control ‘electrode, means for supplying-a -poten-'
circuit connected to said cell and carrying an tialdi?erenc'e between the elaatrodes of said cell, 55
electric current modulated in accordance with the and connections for-‘polarizing said control elec-'
said sound record, an electronic ampli?er system , trode from said potential supplying means.
having a grid, a cathode,'and an anode, circuit
,
70.‘ In a. sound translating system, the combi
nation 01’ a photoelectric cell having a cathode
60 members connecting said- grid to said workcir
cuit, an output circuit'connected to said plate and anode, means for energizing said 'cell with
for carrying a current having ampli?ed mod -_ light
varying in accordance with sound waves, and
ulations corresponding to the said'sound record a circuit associated with the; electrodes of said' and a translating device connected to said out
cell and having an impedance substantially equal '
65 put circuit for converting the modulations of said
to the cell impedance. .
'
a
as
output current into sound. l.
,'
71. In a sound translating system-the combi
A 64. 'In sound reproducing vapparasitus, the com
bination oiI a photoelectric cell having an alkali
cathode, an anode and an evacuated container,
means ‘for illuminating the said cell‘ cathode with
nation 01' ‘a source of light, a photo cell, an optical ' '
sound record strip therebetween, a vacuum tube.
device having a control electrode associated with
said cell, and a current source and connections 70
acoustically modulated light, an electronic’ am
therefo‘r wherebysald current source serves the '
pli?er having a cathode, an anode and/a control double function or. polarizing said control ,elec-.
electrode, a circuit connecting said cell with the trode and said cell.
‘ I
,
.
of said ampli?er, a source-oi pcwer'for said < 72., The combination or a photo cell having
cell also connected in said circuit, and an output> cathode and anode‘ electrodes, a vacuum tubeld'e- "l6
11
8,114,089
on its interior-surface alight sensitive costing
vice connected therewith, and having cathode,
containing an alkali metal, constituting one elec
anode and control electrodes. and a three section
source of potential and connections whereby two
sections of said source furnish space current for
trode, and-provided with another electro'de,'a ‘
thermionic ampli?er having its grid directly con-,
nected with one'of said electrodes, a potential
source suitably connected with said ampli?er and
with the other electrode, and‘ a telephone receiver‘
said vacuum tube‘device, one of said last men
-_tioned sections and another section furnishes
space current to said photo cell and one of said
operatively associated with said ampli?er.
last mentioned sections furnishes a polarizing po
80. Means for optically producing sound, in
cluding a sheet or thelike having relatively
opaque and transparent portiona'a source of
light, a photo-electric cell comprising an evacu
tential for said control electrode.
73. The method of aifecting a photo-electric
cellbymeansof a?uctuating beamoflightwhich
‘varies-in width from a de?nite ?xed
to
an inde?nite maximum, said method comprising
shieldingasinglecelifrombeingactedonbythe
ated vessel having on its inner surface a light
. sensitive coating containing an alkali metal, said
beam when at its minimum width, and exposing
said single cell only to the consecutive portions of
the beam which exceed such width.
74. The method of affecting a single photo'
electric cell by means ofa ?uctuating beam of
sourceoflightbeingsoarrangedastodirecta
15
upon said alkalimetalcoatingand said sheet
being interposed'between said source and said
cell. means for rapidly moving said sheet so as
to cause the relatively opaque and transparent , _
light of variable width, which comprises exposing
said single cell to all those portions only of the
portions thereof to successively pass‘ across the so
beam which exceed a de?nite minimum width.
quency of sound vibrations, a potential source
suitable connected in a circuit including said cell.
'15. The method of optically reproducing sound
which comprises setting up a ?uctuating beam of
light which varies in accordance with the sound,
and projecting this beam upon a photo-electric
I cell ‘in such a way that the cell is continuously en
ergized, whereby its conductivity never drops to
zero, but varies between maximum and a de?nite
76. The combination with means for generating
a ?uctuating beam of light which varies in width
from an inde?nite maximum to a de?nite mini
mum, of a photo-electric cellonto which said
beam is projected, said cell comprising an evac
pathofsaidbeamataspeedequaltothefre-'
whereby‘v the ?uctuating beamproduce'd by said
moving sheet .sets up similarly varying currents
of feeble intensity. a three-element vacuum tube
arranged to amplify such feeble currents, and a
device for converting into sound the currents
thus ampli?ed.
_
,
81. The electro-optical method of producing
sound which comprises forming on a sheet or
strip a series of lines or hands having optical
uated vessel having its interior coated with light
properties in contrast with those of said sheet,
directing a beam of light upon said sheet, mov
ing saidsheet in such_manner as to cause said 35
beam, after leaving the sheet, to ?uctuate with
responsive material, and ' having a transparent
a frequency equal to-that of sound vibrations;
“window” through which the light enters, and a
causing such ?uctuating beam to set up, in a
strip of opaque materialof substantially the same
suitable circuit, electric currents varying in ab
solute ‘synchronism with said beam, thermioni
‘cally amplifying such currents. and converting
width as the'said minimum width of the beam
extending across said window.
7'7. The combination with a record strip having
a transparent record thereon, said record com
prising a central band and teeth or projections
extending from eachedge thereof, of means for
causing said record strip to travel, means for pro
jecting the image of said transparent record as
the strip travels past a slit, a photo-electric cell -.'
having a transparent "window” on which said
image is projected, and an opaque strip or- shield
of substantially the same width as the image of
the central band portion of said record extend
ing across the window and serving to prevent that
portion of the image from entering the window
and affecting the cell.
. '
_
-
‘78. The combination with means for producins
a beam of light ?uctuating with a frequency cor
responding to that of sound waves, of a photo
electric cell comprising an.evacuated vessel hav
ing on its inner surface a light sensitive coating
containing‘ an alkali metal, said cell being so
arranged that the ?uctuating beam falls upon
said alkali metal coating, a potential source suit
’ahly connected in a circuit including said cell.
the energy of the ampli?ed currents into sound v
waves.
‘
‘
_
-
82. Sound producing apparatus comprising a
photoelectric cell having an anode and an alkali
cathode, means for illuminating the cell and for
varying such illumination at a rate correspond
ing to the frequency of sound waves, an ampli?er,
a circuit connecting said cell with said ampli?er,
a sound producing device, and a circuit connect
ing said ampli?er with said sound producing
device.
-
'83. In sound producing apparatus from an op
tical record, an electrically operated sound_pro-'
ducer requiring modulated dynamic electrical
energy of substantial value for its operation; a
photo-electric cell having an anode and a oath-
ode capable of emitting electrons in proportion
to incident light and a protecting enclosure hav
ing a transparent portion adapted to expose said
cathode to light modulated by an optical record;
a direct current source of electric exciter poten
tial for said photo-electric cell; a vacuum tube
ampli?er operatively connected with said-sound
whereby said ?uctuating beam sets up variable. producer; and means operatively connecting s'ald
source of exciter potential with said photoelectric
currents of feeble intensity, a three-element vac
_ uum tube arranged to amplify such feeble curf
' rents, and a device for converting into soundthe
currents thus'ampli?ed.
I
e-
.
'79. The combination with means ‘for produc
ing a beam, of light ?uctuating with a frequency
corresponding to that of sound
of a photo
electric cell arranged in the path of said vbeam,
said cell comprising an evacuated vessel having _
cell and linking said photoelectric cell with said _
ampli?er operatively tolcausemodulated electron
emission from said cathode to effect the ?ow of
correspondingly modulated but greatly ampli?ed 7o
currents from said ampli?er through said sound‘
producer;
.
-
,
.
ALBERT A.
.
.
'
l2
'CERTIFIGA‘I‘E OF CORRECTION.
,Patent No. 241189589.
April 19, 1958.
ALBERT A. mum.
Since it appears from th'e'records of this Office that claims 2h, 25, 26,
2'; and 28 were held unpatentable to the patentee by the Board of Appeals
and that claims 75, 7.6,* T7, 81, 82 and 85 are duplicatee' respectively of‘
claims 12, l5, l6, 19, 22 and 59 of the patent, it is hereby certified that; ‘
claims 24, 25, 26, 27, 28‘, 75, T6, 77, 81, 82 and 85 were included in?the
patent by ‘error and that-the patent should be reachwithout these claims.
Signed and sealed this ‘1st day of November, A. D. 1958 .
'
Henry Van A'rsdale
(Seal)
> Acting Commissioner of Patent 5.
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