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Патент USA US2404839

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July 30, 1946.
_ J. H. HAMMOND, JR l
2,404,839
SECRECY COMMUNICATION SYSTEM
Filed Aug. 22, 1941
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July 30, 1946.
2,404,839
.1. H. HAMMOND, .1R
SECRECY COMMUNICATION SYSTEM
Filed Aug. 22, 1941
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JOHN HAYs HAMMoNn, JR.
July 30, 1946.
J, H_ HAMMOND, JR
2,404,839-
SECRECY COMMUNICATION SYSTEM
Filed Aug. 22, 1941
3 Sheets-Sheet 3
EY
Patented July 30, 1946
2,404,839
FFICE
UNITED STATES, «PATENT o
sEcREcY COMMUNICATION SYSTEM
John Hays Hammond, Jr., Gloucester, Mass.,
assignor to Radio Corporation o1' America -
1
Application August 22, 1941, serial No. 467,891 ‘
4 claims. (ci. 17a-_6.7)
2
This invention relates to secrecy communica- .
tion systems and more particularly to a system
for communicating messages by television.
'I'he invention further relates to means for in‘-
.
and 22> 'I‘he sprocket 2I is driven intermittently
by anintermittentcam and spider-follower 23 of
the early Powerstype, in which the throws are 10
cated 144° and 216° apart respectively. This
serting a message in a single frame of a television 5 mechanism is driven by a 3600 R. P. M. synchro
moving picture transmission system and means
for recording this message on a moving picture
film.
'
y
The invention’also relates to means for send
nous motor 24 thru a bevel gear and pinion 25-26
having a 5:1 ratio. Mounted on the shaft of the
motor 23 is 'a shutter disc 21 which is provided
with a slot 28.
I
'
_
ing a message as a single frame of a, television 10
Light from a source of illumination, such as
transmission system at a predetermined time and ‘
an electric arc 29 passes thru a lens system 30,
means for receiving the message on a photo
the light gate I9, film I1, and a second lens sys- »
graphic film.
tem 3| and is focused upon the iconoscope mosaic
32. The iconoscope I2 isof standard and well
15 known construction and is provided with the usual
The invention also consists in certain new and
horizontal and vertical deflection coils 35 and 36
original features of construction and combina
which are connected to the deflection amplifiers
tions of parts hereinafter set forth and claimed.
31.y `The iconoscope mosaic 32 is connected thru
Although the novel features which are believedv
an output circuit 38 to the amplifier I3.
to be characteristic of this invention will be par 20 A synchronizing generator 39 is connected to
ticularly pointed out in the claims appended here
the amplifier I 3 and controls the speed of the mo
to, the invention itself, as to its objects and ad
“ tor` 24. Control equipment 40 is -connected to the
vantages, the mode of its operation and the man
amplifier I3 and the transmitter I4 is provided
ner of its organization may be better understood
with the usual antenna 4I. A light souce 42 is
by referring to the followingr description taken 25 located near the gate I8 and is focused by‘a lens
'I'he invention also relates to a novel and im
proved television receiving system.
'
in connection with the accompanying drawings
forming a part thereof, in which
Figure 1 is a schematic diagram of a, typical
A 43 upon a photo-electric cell 454 which is connected
to the control potential means 46 which in turn
is connected to the lamplifier I3. The sound head
transmitter which may be utilizedin a system
41 is connected to the amplifier I3.
embodying the present invention. "
30
The ñlm I1 used in this invention may be the
Figure 2 illustrates a section of ñlm used in the
standard motion-picture ñlm with one or more
transmitter shown in Figure 1.
of the picture frames replaced by the message 50.
Figure 3 illustrates diagrammatically the se
(Figure 2.) This replacement may be done in
quence of events in the transmitter shown in Fig
any lmanner well'known in the art, such as cut
ure 1.
35 ting the film and inserting a section bearing the
Figure 4 is a schematic diagram of a. receiver
message.
embodying the present invention.
` Operation
Like reference characters denote like parts in
the several ñgures of the drawings.
In the operation of the transmitter shown in
In the following description and in the claims 40 Figure 1 the film I1 is movedintermittently by
parts will be identified by 'specific names for con
venience, but they are intended to be as generic
in their application toy similar parts as the art will
means of .the cam and~spider-follower 23. The
cam is driven at 12 revolutions per second by the
synchronous motor 24 which runs at 3600 R. P; M.
permit.
'I'his causes the ñlm I1 to be pulled down at un'
Referring to the accompanying drawings and 45 equal vintervals as the throws of the cam are lo-v
more particularly to Figure 1, a standard tele
`cated 144° and 216? apart. ’I'he motion of the
vision, film transmitter is shown comprising a mo
film` I1isshown at 5I in Figure 3 in which .the
tion picture projector II which projects a stand
shaded areas indicate the pull down motion. 'I'he
ard film upon an iconoscope camera I2, the out
light fromv the arc 29 after passing thru thegate
put circuit of which is connected to the necessary 50 I9 is chopped60 times per second «by the shutter
amplifiers I3 and radio transmitter I4.
21. The shutter 21 is so timed relative to the cam
The projector I I is provided with the usual feed
23 that the film I 1 is always stationary 'when the
and take up reels I5 and I6 upon which is wound
light flashes occur. The 'sequence of light flashes
the film I1. The film I1 passes thru two gates
-is indicated at 52 in Figure 3. These light flashes "
I8 and I9 and over a number of sprockets 20, 2l 55 are fofonly M205 second duration.
3
The chopped light after passing thru the shut
ter 21 is focused upon the iconoscope mosaic 32. `
This mosaic is scanned 60 times per second as
gears 91--98 which have a 1:5 ratio. The diner
ential 96 is operated by a lmurled knob 99. The
motor 95 is driven from a power ampliñer |00
indicated at 53 in Figure 3. The scanning periods
which is controlled by a frequency multiplier |6|
53 occur between the light flashes 52 so that the Cl connected to the sawtooth generators 10. The
television picture signal is produced and trans
sound recorder 82 is operated by a sound ampli
mitted during periods when no optical image is
fier |02 connected to the main amplifier 6|.
on the mosaic 32. During these periods, how
Operation
ever, an electrical image is present on the mosaic
In
the
operation
of
the receiver depicted in Fig
32 in the form of bound electrostatic charges on
the minute photo-sensitized silver globules com
_ure 4; the television program is received by the
antenna 86 and is fed to the main ampliiier 6|
prising the mosaic'32.
During the scanning periods the sensitized
which, for example, may consist of a first de
tector, three stages of intermediate frequency
mosaic 32 is scanned -by a moving beam of elec
amplification and a second detector and -syn
trons 55 which is caused to scan the image on the
chronizer. «'I'he output from the second detector
mosaic 32 by means of the deflection coils 35
is fed to the video ampliñer 62 where the pic
and 36 in a well known manner. The deilection
ture signal is ampliñed and fed directly to the
coils 35 and 36 are energized from the deñection
cathode ray tube 63. The second anode of the
amplifiers 31 which are controlled by the syn
chronizing generator 39 acting thru the amplifier 20 tube 63 is supplied with high voltage, for exam
|3. As the synchronizing generator 39 also con
' ple, 200 volts direct current, from the full wave
rectifier 66. Low voltage power may be supplied
trols the synchronous motor 24, the operator can to the tube 63 from a source not shown.
,make the short 1A200 second light flashes fall with
The canning and synchronous control auxil
in the 1/300 second intervals between the vertical'
scanning periods with some tolerance on each 25 iaries make use of the second stage of the second
detector, which may be used as a clipper rectifier
side as depicted in Figure 3.
to provide the synchronous pulses separated from
'I'his arrangement of moving film and scanning
the picture impulses. The output of the clipper
is necessary as the standard ñlm moves at the
rectiñer leads to the synchronous amplifier 'Il
aver‘age rate of 24 frames per second while the
television apparatus operates at 30 frames per 30 which acts to separate the vertical synchronous
pulses from the horizontal. The sawtooth gen
second and 60 fields per second, interlaced, so
erators 10 may include a blocking oscillator and
that the projector must flash a still picture on‘the
discharge tube which may be used to develop
mosaic every léo of a second with each flash last
sawtooth waves of voltage under control of the
ing about 9h00 second.
<
A fuller description of the construction and op 35 vertical impulses and a second blocking oscil
lator and discharge tube may be used to develop
eration of the transmitter is set forth on pages
sawtooth waves of voltage for the horizontal di
48-61 in the R. C. A. review, volume IV, 1939
rection. The outputs of these two circuits con
1940. It is to be understood that this particular
trol the vertical and horizontal deflection ampli
transmitter is described merely as an example
of a suitable system to which this invention may 40 ñers 69 which in turn control the operation of
the vertical and horizontal deflection coils 61 and
be applied and that other devices capable of
scanning a motion picture ñlm and transmitting
'I'he television picture is produced on the fluo
the scanned image may be used.
rescent screen of the cathode ray tube 63 in
The receiver embodying the present invention
is shown in Figure 4 as comprising an antenna 45 the usual manner, the picture signal being sup
plied by the video amplifier 62 and the cathode»
60 which is connected to the input of the ampli
ray beam being deflected by means of the coils
ñer 6|, the output of which passes thru a video
61 and 68. As already described the picture on
amplifler 62 to a cathode-ray tube 63. An oscil
the screen will consist of two images of frame
lator 65 is connected .to the amplifier 6| and a
high voltage supply source 66 is connected to the 50 |, three images of yframe 2, two images of frame
3, etc. As only one image of each frame is to be
tube 63,V The deñection coils 61 and 68 of the tube
photographed the disc 89 is provided with the
63 are connected to the deflection ampliñers 69
two slots 90 and 9|, which are 144° and 216° apart
which in turn are connnected to the sawtooth
respectively. The disc 89 is rotated at t’s the
generators r10. The sawtooth generators 18 are
controlled by the synchronous ampliñer 1| which 55 speed of the disc 21 (Figure 1) or one revolution
in 2/24 second. ’I'his speed of rotation is accom
is connected to the main amplifier 6|.
plished by driving the shaft 88 from a synchro
For making a photographic record of the pic
nous motor 95 thru a set of bevel gears 98-91
tures produced by the cathode ray xtube 63, a mov
having a 5:1 ratio. 'I'he motor 95 is driven in
ing picture camera apparatus 15 is provided.
The sensitized iilm 16 of this apparatus is un 60 synchronism with the motor 24 from the power
ampliñer |00, which is controlled by the fre
wound from a supply reel 11, passes over a sprock
quency multiplier |0|, which in turn is controlled
et 18, thru a. ñlm holder 19, over sprockets 80
by the sawtooth generators 10.
and 8|, thru a sound recorder 82 and is wound
The shaft 88 drives the cam 85 at the same
upon a take up reel 83'.
The sprocket 80 is driven intermittently by an 65 speed as the disc 89 by means of the 1:1 ratio
bevel gears 86--81. The cam 85 drives the
intermittent cam and spider follower 85, which is
sprocket 80 intermittently so that the ñlm 16 is
similar to the cam and spider-follower of Fig
drawn down twice during each revolution of the
ure 1. The cam 85 is' driven by a 1:1 ratio bevel
disc 89. This draw down motion takes place
gears 86--B1, the latter >being secured to a shaft
88 to which is attached a shutter disc 89. The 70 when the slots 90 and 9| are not in line with the
axis of the lens system 92-93. =The differential
shutter 89 is provided with two slots 90 and 9|
99 is used to obtain the proper relationship be
and passes between two lens 92 and 93 which focus
tween the slots 90 and 9| and the scanned
the television image upon the iilm 16. The shaft
images. When the slots 90 and 9| are in line
88 is driven from a 3600 R. P. M. synchronous
motor 95 thru a diiïerential 96 and a set of bevel 75 with the optical axis of the system one image of
5
.
«refinancel
each frame will be completely scanned on the
screen of the tube 63' and a photographic record
of each frame will therefore be made on the tllm
19 which will include the frame 50 containing
the message.
,
When the iilm 16 is developed and printed it
is slowly run thru a standard type of projector
until the frame 50 containing the desired mes
sage is projected on the screen where it may be
read or an enlarged photographic record of it
made.
The system may be operated for only a very
brief interval of time by opening the circuit oi.'
system could then be put in operation at a pre
determined time, the mechanical apparatus syn
chronized and as the message frame 50 ap
ñlm at the transmitter.
~
¿ 2. The method of secret communication which
comprises incorporating a message on a single
frame of a standard ymotion picture nlm, trans
mitting said message by television during an in
terval of about one-sixtieth of a second. receiving
the transmitted message at a remote point, n
transferring the same onto a sensitized motion
picture ñlm. and developing said'ñlm to thereby
reproduce said message. ‘
the video amplifier in the transmitter so that .
only the synchronizing signal is transmitted. The
6
and developing said film to reproduce said mes
sage together with the transmitted picture in’ the
frame ~sequence corresponding to' that of the
3. 'I'he method of secret communication which -
comprises. inserting a message between picture
frames on a standard motion picture ñlm, scan- .
ning said ñlm, transmitting the images thereof
' by television, receiving said images at a suitable
proaches the picture gate I9 the circuit of the
receiving point, impressing the same photograph
video amplifier could be automatically or man 20 ically on a, sensitized motion picture iìlm at said
ually closed and a few frames of the. picture
point, and developing said film to reproduce said
transmited which would include the message
message together with the transmitted picture
frame 50. In this way the signals would be
in the frame sequence corresponding to that of
transmitted for only a fraction of a second, thus
the ñlm at the transmitter.
A
increasing greatly the secrecy of the system as 25
4. The method of secret communication which
there would not be time for unauthorized per
comprises the steps o1' inserting a single ñlm
sons to tune in on the video signal.
~
frame area of a graphical message representa.
Although only a few of the various forms in
tion at predetermined spaced positions in a se
which this invention may be embodied have been
quence of iilm frame areas of pictorial repre
shown herein, it is to be understood that the 30 sentations, scanning all of the film frame areas
invention is not limited to any specific construc
of the graphical and pictorial representations in
tion but might be embodied in various forms
sequence to produce signalling energy repre
without departing from the spirit of the inven
tion or uthe scope of the appended claims.
What is called is:
1. The method of secret communication which
comprises inserting a. message on a single frame
sentative of the scanned iilm frames, and trans
mitting the produced signalling energy with the v
35 two groups oi' signals in an associated and inter
. mingled relationship whereby the signalling en- -
ergy representative of the graphical iilm frame
of a standard motion picture film, scanning said
areas -is substantially masked and rendered secret
nlm, transmitting the images thereof by tele
in the transmission by the predominating se
vision. receiving said images at a suitable receiv 40 quence of picture signalling energy..v `
' ~
ing point, impressing the same photographically
on a sensitized motion picture ñlm at said point.
JOHN HAYS HAMMOND, Jn. '
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