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Патент USA US2404939

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Juiy 3o, 1946.
W. F. BARES”
TELEVISION SIGNAL-TRANSLATING SYSTEM
Filed. Feb. 27', 1942
¿404,939
Patented Julyv 30, 1946
2,404,939
UNITED STATES PATENT OFFICE
2,404,939
TELEVISION SIGNAL-TRANSLATING
SYSTEM
William F. Bailey, Port Washington, N. Y., as
signor, by mesne assignments, to Hazeltine Re
search, Inc., Chicago, Ill., a corporation of Illi
nois
Application February 27, 1942, Serial No. 432,669
8 Claims.
1
This invention relates to a television signal
translating system and, more particularly, to a
video-frequency signal-translating system having
2
sired video-frequency signals, in spite of the
aforementioned expedients.
As a still further expedient, it has been pro
an improved characteristic effective in compen
sating for shading effects in the reproduced pic
posed to minimize the shading component in the
ture.
able, artiñcal compensating signal which may be
inserted in the video amplifier. It has been found
In video-frequency signal-generating systems,
especially those in which a camera tube having a
output signal of a camera tube by utilizing a suit
that such an artificial signal having a saw-tooth,
target electrode comprising a mosaic plate is em
exponential or parabolic Wave form may in some
Dloyed as the video-frequency signal generator, 10 cases be effective to reduce, to a limited extent,
there is produced, in addition to the desired
the undesired shading effect. In some instances
video-frequency signals corresponding to the
the compensating signal is a composite signal
image to be translated, an undesired, spurious
comprising a combination of these Wave forms,
signal, commonly known as a shading signal.
and having frequency components related to the
This undesired signal is produced, at least in part, 15 scanning frequencies of the signal generator.
by secondary electrons emitted from the target
This method of compensating has the disadvan
electrode during the scanning operation. The
tage that it requires elaborate and extensive
emitted secondary electrons rain back upon the
equipment which is both difficult and inconven
ient to operate successfully.
target electrode but, in general, this rain is not
uniform over the area of the target so that the 20 It is an object of the present invention, there
several elements of the target do not assume po
fore, to provide an improved television signal
tentials accurately representative of their respec
translating system Which is not subject to one or
more of the above-mentioned disadvantages.
tive degrees of illumination, Consequently, the
output signal of the cameraV tube includes an un
It is still another object of vthe invention to
desired component resulting in a shading effect 25 provide a television signal-translating system
having an improved arrangement for removing,
in the reproduced picture. Since the shading
at least in Dart, from the signal translated there
effect is produced in part by the scanning opera
by an undesirable component introduced into the
tion, the shading signal contains frequency com
signal in the signal generator and normally eiïec
ponents related to the scanning frequencies of the
system. The amplitude of the undesired signal 30 tive to produce a shading effect in the reproduced
picture.
under consideration is generally of a greater order
It is a still further object of the invention to
of magnitude than that of the desired video-fre
provide an improved method and means for
quency signal so that it is necessary to delete
translating television signals substantially free
from the composite output signal of the camera
tube those components which correspond to the 35 from components related to the scanning fre
quencies of the translating system and normally
undesired shading signal if high-quality image
effective to produce a shading effect in the repro
translation is to be attained.
duced picture.
For the purpose of minimizing shading effect of
the type under consideration, it has been pro 40 A specific object of this invention is to provide
in a television signal-translating system an auto
posed in the past to include a collector ring in the
camera tube having a circular shape symmetrical
with respect to the mosaic and particularly
adapted for collecting the secondary electrons.
It has also been proposed to use small values of
beam current in the camera tube to reduce the
shading effect. Another expedient resorted to for
the same purpose is to avoid scanning the edges
of the mosaic Where the variations in the rain
of electrons back to the mosaic are the greatest.
However, systems in which these DI‘OIJOSEÚS have
been utilized are subject to the disadvantage that
a substantial shading effect remains and that the
amplitude of the undesired shading signal pro
duced is generally greater than that of the de 55
matic means for shading correction which means
does not require the services of an operator re
gardless of the shading wave form.
In accordance with the invention, a television
signal-translating system includes a signal
translating channel having an input circuit and
an output circuit, and means for applying to the
input circuit a composite signal derived by scan
ning continuous lines of an image to be translated
which signal comprises video-signal components
Within a predetermined frequency range corre
sponding to images to be translated in the system
and undesirable shading components having fre
quencies within this range and related to a fre
quency of scanning of the image. |Also included
2,404,939
3
a power amplifier 24, and an antenna system 25,
2G ; all, with the exception of the translating stage
in the system are means having a frequency char
acteristic related to the above-mentioned scan
ning frequency for effectively removing from the
compo-site signal at least one lower frequency
2li which embodies the present invention as will
be described more fully hereinafter, are con
structed and arranged in accordance with con
component of the shading components and for
translating to the output circuit the resultant sig
nal which includes video-signal components hav
ing frequencies below the above-mentioned lower
frequency component and is substantially free
from each removed shading component.
ventional practice. Line-synchronizing pulses
and held-synchronizing pulses are derived from
line-frequency generator I3 and field-frequency
generator lli, respectively, and supplied to the
video-frequency amplifier 2l for translation with
the video-frequency signals generated in unit I0.
In accordance with a preferred embodiment of
the invention, a repeater circuit including a plu
Suitable means (not shown, but which may be
considered as included in the signal generator l0)
are also provided for developing a unidirectional
rality of trap circuits is coupled in the signal
translating channel. rI‘he trap circuits, which
background-illumination voltage and for insert
ing it into the developed video-frequency signal.
may be either series or parallel arrangements of ,
inductors and capacitances, are resonant at the
fundamental and at least one harmonic of the
line-scanning frequency and are effective to re
move from the translated signal components of
Neglecting for the moment details of opera
tion of the signal-translating stage 26, the sys
tem just described comprises the elements of a
television transmitter of conventional design and
the various parts thereof, which are illustrated
schematically, may be of well-known construc
tion, rendering a detailed description of their op
eration unnecessary. Brieiiy, however, the im
those frequencies which correspond to shading ~
components. A coupling circuit, which comprises
a stabilizing device coupled to the repeater circuit,
is provided and is effective to suppress shading
components related to the held-scanning fre
quency. To this end, the coupling circuit has a
time constant which is short with respect to the
age of a scene to be transmitted is focused on the
target of the signal generator I0 and scanning
field-scanning frequency and rejects components
currents are applied to the scanning elements Il
and I2 of the generator l0 to supply electro-mag
of the translated signal at that frequency.
For a better understanding of the invention,
netic fields which serve to deflect the scanning
together with other and further objects thereof, 30 ray in two directions normal to each other, there
reference is had to the following description taken
by to scan successively a series of ñelds of par
in connection with the accompanying drawing
allel lines upon the target. The de?lecting cur
and its scope Will be pointed out in the appended
rents, and hence the scanning fields, are of saw
tooth wave form providing relatively slow linear
claims.
In the accompanying drawing, Fig. 1 is a circuit
trace and rapid retrace scansions. Block-out im
pulses developed by generator I5 are applied to
diagram, partly schematic, of a television trans
mitting system including a circuit arrangement
the signal generator Iû to suppress or block out
the scanning beam during retrace portions of the
embodying the present invention; Fig. 2 is a cir
scanning cycles. The timing impulses developed
cuit diagram of a modification of the arrangement
of Fig. 1; Fig. 3 comp-rises a graph representing
by the generator I6 are applied to generators I3
certain operating characteristics of the circuit of
|5, inclusive, to lock these generators in synchro
Fig. 2; and Fig. 4 is a circuit diagram of a further
nism.
The photosensitive elements of the target of
modification of the arrangement of Fig. 1.
the signal generator IEI are electrically affected
Referring now more particularly to Fig. l of
to an extent dependent upon the varying values
the drawing, there is illustrated a television
transmitting system comprising a signal gener
of light at the corresponding elemental areas of
the image focused thereon so that, as the cath
ator Ii), which may be of conventional design in
ode-ray beam scans continuous image lines of
cluding a camera tube of the cathode-ray type,
the image on the target, Video-frequency signals
having a mosaic type target electrode and scan
ning elements Il and I2. For the purpose of i of correspondingly varying amplitude, and having
a frequency range determined by the images to
developing scanning currents for the signal gen
be translated, are developed in the generator I0.
erator III there are provided a line-frequency
The terms video signal or video-frequency signal,
saw-tooth wave generator I3 and a field-fre
as employed in the specification and claims, are
quency saw-tooth wave generator M, the output
circuits of these generators being connected to ; intended to designate a conventional picture sig
nal which is generated by the usual scanning
scanning elements II and I2, respectively, of the
operation. This terminology therefore excludes
signal generator IB in the usual manner. In or
a generated picture signal, the wave form of
der to block out the scanning ray of the generator
which is modified by interrupting the scanning
lil during retrace scanning periods, there is pro
vided a block-out wave generator I5 having an
beam by suitable means at a high frequency so
output circuit suitably connected to the signal
generator I0.
that the picture signal, in effect, modulates the
developed interrupting wave, this latter wave be
For the purpose of synchronizing the genera
tors there is provided a timing-impulse generator
I5 coupled to the input circuits of the generators
I3-I5, inclusive. Timing-impulse generator I6 is
preferably stabilized by means of a connection i'l
ing in the nature of a carrier wave.
image to be translated as in customary scan
ning practice. At the same time as the conven
to a suitable source of periodic voltage, for exam
tional video-frequency signals are generated, due
ple, the power-supply circuit or the synchroniz
ing-voltage source of a motion-picture mecha
nism where such is employed.
The inter
ruption of the scanning beam in the foregoing
manner therefore effectively prevents the beam
from scanning continuous image lines of the
70 to the above-mentioned secondary-electron ef
Connected in cascade to the generator I il, in
the order named, are a signal-translating stage
2S, a video-frequency amplifier 2|, a modulator
22, an associated carrier-frequency oscillator 23, 75
fect, shading signals having components related
to the line-scanning frequency and field-scanning
frequency and included within the frequency
range of the video-frequency signals are also
developed in the generator Ill. These developed
2,404,939
5
signals comprise a composite signal derived by
cuit of the signal-translating stage includes a
load resistor 4| and is suitably coupled to the
input terminals of video-frequency ampliñer 2|.
Operating potentials for tubes 21 and 28 are sup
the generator I0 and the unidirectional back
ground-illumination voltage which is developed
by suitable means included in the generator IG
is inserted in this signal. Thus, the video-fre Ul plied to their screens from suitable sources indi
-quency and shading-signal components, block
cated -l-Sc and to their anodes from suitable
out components, and unidirectional-background
sources indicated -l-B.
components are all derived from the signal gen
In considering the operation of the circuit of
erator I0 and applied to the signal-translating
Fig. 1, it will be assumed that composite signals
stage 29, wherein they are translated in accord 10 comprising video-signal components Within a
ance with the present invention and from which
predetermined frequency range corresponding to
they are applied to the video-frequency ampli
the images to be translated and undesired shad
fier 2|. synchronizing impulses derived from
ing components having frequencies within the
generators I3 and i4 are mixed With the video
range and related to the line-scanning and field
signal components in the combining video-fre
scanning frequencies of the signal generator l0
quency amplifier 2| and the resultant signal is
are applied negatively, that is, with the black
thereupon supplied to the modulator 22 wherein
level of the composite signal more negative than
it is impressed upon the carrier wave generated
the white level thereof, by way of coupling con
by the oscillator 23. The modulated carrier sig
denser 29 to the input circuit of the signal-trans
nal is then delivered to the power amplifier 2d. 20 lating channel and to tube 21, The time constant
for amplification and is impressed upon the an
of condenser 2S and grid-leak resistor 3G is such
tenna system 25, 2'5 to be radiated.
that the signal is not stabilized about its positive
Referring now more particularly to the signal
peaks in the input circuit of tube 21. The trap
translating stage 2Q embodying the :resent in
circuits included in the cathode circuit of tube
vention and provided for the purpose of remov
21 are effective to render the tube degenerative
ing shading components from the composite sig
to applied signal components of the fundamental
nal to be translated, this stage comprises a pair
frequency and the second harmonic, respec
of vacuum tubes 21 and 23, which are preferably
tively, of the line-scanning generator whereby
of the pentode type, coupled in cascade to pro
components of the composite signal at these fre
vide a signal-translating channel having an in
quencies, which correspond to components of the
undesired shading signal, are effectively removed
and do not appear in the repeated signal which
put circuit connected to signal generator Hi and
an output circuit connected to video-frequency
amplifier 2|.
The input circuit of the signal-translating
channel includes the signal-input electrode of
tube 21 and is coupled to the output circuit of
signal generator |ß by way of a coupling con
denser 29 and a grid-leak resistor 3d. Tube 21,
which functions as a signal repeater, is pro
vided with means having a frequency character'
istic related to one scanning frequency of the
signal generator lll to render the tube degener
ative to applied signal components of predeter
mined frequencies for attenuating from the com
posite signal applied thereto components having
a frequency related to the saine scanning fre
quency and corresponding to shading compo
nents in the signal output of generator it. Spe
cifically, there is provided in the cathode circuit
of repeater 21 a pair of parallel-resonant trap
circuits connected in series. The ñrst trap cir
is derived from the output circuit of tube 21.
Due to the phase-reversing characteristic of tube
21, the repeated signal is applied positively, that
is, with the black level of the signal more posi
tive than the white level thereof, by way of cou
pling condenser 3i) to tube 28 wherein the signal
is stabilized through grid rectification at the most
positive peaks of the signal. The time-constant
circuit comprising condenser 39 and leak resistor
4l! is effective to remove from the signal applied
to tube 28 components at the ñeld-scanning fre
quency which also correspond to components of
'. the shading signal. Thus, a composite signal
from which the undesirable shading components
have been removed is derived from the output
circuit of the signal-translating channel 2|) and
applied to video-frequency amplifier 2| for fur
cuit comprises a parallel combination of an in
ductor 3|, a condenser 32, and a damping re
sistor 33, and this trap circuit is tuned prefer
ably to the fundamental frequency of the line lll A,
frequency generator |3. The second trap circuit
comprises the parallel combination of an induc
tor 34, a condenser 35, and a resistor 36, and
this trap circuit is tuned preferably to the sec
ond harmonic of the line-scanning frequency. (SO
The damping resistors 33 and 3S are provided in
order to broaden the attenuation characteristics
of the trap circuits. The output circuit of tube
21 is provided with a load resistor 31 and is
coupled to the input circuit of tube 23 through
a time-constant circuit which comprises coupling
condenser 39 and grid-leak resistor 40. The time
constant of the circuit coupling tubes 21 and 28
is proportioned with respect to another scanning
frequency of the generator lll and, preferably,
the circuit is arranged to have a time constant
short with respect to the period of the ñeld
frequency generator I4 so that the coupling cir
cuit has a frequency characteristic related to
the field-scanning frequency. The output cir 75
ther amplification.
Therefore, it may be seen that the unit 20 is
effective to remove undesired shading compo
nents from a composite signal comprising both
desired video-signal components and undesired
shading components within the frequency range
of the video-signal components and related to a
frequency at which the image to be translated is
scanned, whereby the video-signal components
supplied to amplifier 2| are thus substantially
free from shading components caused by the
scanning operation at the signal generator.
In Fig. 2 there is disclosed a repeating network
embodying a modification of the invention which
may be substituted in the television transmit
ting system of Fig. 1 for the signal-translating
stage 20 by connecting the terminals indicated C
and D to the corresponding terminals of Fig. l.
The network includes a pair of vacuum-tube re
peaters 50 and 5| which preferably are of the
pentode type. The input electrode of tube '50 is
coupled through a coupling condenser E2 and a
grid-leak resistor 53 to the output circuit of gen
erator I0 and the signal output from tube 50 is
derived from a cathode load resistor 54 so that
the output signal has the same polarity as the
'2,404,939
7
8
input signal. The input circuit of tube 5| is
coupled in parallel with that of tube 50 and in
ing the fundamental, second, and third harmonics
of the line-scanning frequency which correspond
to shading components which are particularly
troublesome, whereby the video-signal compo
cludes a coupling condenser E5 and a leak re
sistor 5l. Also included in the input circuit of
tube 5l is a low-pass filter network comprising
series resistors E8 and SQ and shunt condensers
59 and (il. The output signal of tube 5l is de
rived from an anode load resistor 62 and, due to
nents of the composite signal are translated to
the output circuit of the signal-translating chan
nel substantially free from shading components
of frequencies related to the line-scanning fre
the phase-reversing characteristic of the tube,
quency.
the signal derived therefrom has a polarity oppo 10
In the modification of the invention disclosed
site to that of the signal-input thereto. A con
in Fig. 4, the means provided for attenuating
denser 63 is connected between the anode of tube
shading components comprises a pair of shunt
5l and the cathode of tube 53 whereby the tubes
connected series-resonant trap circuits coupled
are connected in phase opposition.
in the signal-translating channel, The ñrst trap
Tube 50 has a substantially uniform gain char
circuit includes an inductor "55? and condenser 'li
acteristic over the frequency range of the video
and is tuned, preferably, to the fundamental of
signal components while the filter 58 to @l causes
the line-scanning frequency, while the second
the tube 5I to have a gain characteristic related
trap circuit includes inductor 'i2 and condenser
to a frequency at which the image to be trans
'i3 tuned, preferably, to the second harmonic of
lated is scanned. Specifically, the low-pass nlter
the line-scanning frequency. The circuit of Fig.
58 to 6| is arranged to reject frequency compo
4 may be substituted for the signal-translating
nents of the applied signal which are of a fre
stage 2e in Fig. `l by connecting terminals C and
quencsr equal to or greater than the third har
i) to the correspondingly designated terminals
monic of line-frequency generator i3. The cou
of Fig. l. When this substitution has been
pling circuit associating the output circuits of
effected the composite signal applied to terminal
the repeater tubes 5t and lil has a frequency
C is translated and applied to video-frequency
characteristic related to another lfrequency at
amplifier El, but components of the signal hav
which the image to be translated is scanned and,
ing frequencies corresponding to the first and
specifically, the coupling circuit is arranged to
second harmonics of the line-scanning frequency
have a time constant which is short with re 30 and ccrresponding to shading components are
spect to the frequency of the field-scanning gen
attenuated by the trap circuits.
erator I4.
It is appreciated that in utilizing the principles
In considering the operation of the circuit of
and concepts of the invention, certain desired
Fig. 2, it will be seen that the composite signal,
picture components may be removed from the
defined above, is derived from signal generator
translated signal; that is, in attenuating fre
l0 and applied to tube 59 and that a signal of
quency components related to the undesired shad
the same polarity is developed across its cathode
ing signals components of the desired video sig
load 5e. The signal output of generator ! 0 is also
nals of the same frequency are simultaneously
applied to the input circuit of tube 5I, but the
attenuated. However, the deletion of such small
components of the signal having a frequency 40 portions of the relatively wide frequency band
equal to or greater than the third harmonic of
representative of the video signals to be trans
the line-scanning frequency are rejected by the
lated does not appreciably affect the picture con
low-pass filter 5B to Si and, therefore, do not
tent of the signal, That is, the frequency com
appear in the output circuit of tube 5i. Signal
ponents which are removed are of relatively low
components of the lower frequencies, however,
frequencies which control the shade of the pic
are translated in repeater 5l to substantially
ture rather than the picture details and, hence,
the same extent that these components are trans
the sharpness of the reproduced picture is not
lated in repeater
The signal output of tube
adversely affected. At the same time, removal
5| developed across the anode resistor 62 is of
of the shading components, particularly those
opposite polarity to that developed across cathode
related to the line-scanning frequency which are
resistor 54 of the tube 50 so that these outputs
most pronounced, enables the reproduction of a
when coupled together through condenser S3
translated image which is sufficiently improved
tend to cancel one another for the frequencies
over the reproduction of images wherein the
under consideration. Due to the above-defined
shading components have not been removed to
time constant of the coupling circuit, however,
coupling condenser 63 is effective to block com
ponents of the repeated signal of tube 5| of a fre
quency less than the fundamental of the line
scanning frequency and, since only components
of the applied signal having frequencies up to the
third harmonic of the line-scanning frequency
appear in the output circuit of the tube 5l, a
band of frequencies extending substantially from
the fundamental to the third harmonic of the
line-scanning frequency is effectively suppressed
in the output circuit of tubes 5l) and 5l . The out
put characteristic of the repeating network is
represented in Fig. 3 wherein f1, f2, and f3 indi
cate the fundamental, second, and third har
monics, respectively, of 'the line-scanning fre
quency.
Consequently, it may be seen that the repeat
ing network of Fig. 2 is effective to remove from
the composite signal applied thereto or appre
ciably to attenuate a band of frequencies includ
more than compensate the inherent loss of nat
uralness in the reproduction caused by the dele
tion of a portion of the video signals.
There has been included in the above-described
embodiments of the invention means for remov
ing from the composite signal frequency com
ponents corresponding to the fundamental, sec
ond, and third harmonics of the line-scanning
frequency, as well as components corresponding
to the fundamental and one or more harmonics
(55 of the field-scanning frequency. It is, of course,
to be understood that any desired combination
of frequency components related to scanning fre
quencies and corresponding to an undesired
shading signal may be similarly removed by re
arranging or increasing the number of the trap
circuits employed.
The specific embodiments
disclosed are merely illustrative of some possible
combinations.
Although the invention has been disclosed in
75 connection with a television transmission system,
2,404,939
9
10
it is to be further understood that the principles
and embodiments of the invention may be applied
With equal facility to a television receiving sys
tem to accomplish the purposes accomplished by
the invention when applied to a television trans
4. A television signal-translating system com
prising, a signal-translating channel having an
input circuit and an output circuit, means for
applying to said input circuit a composite signal
derived by scanning an image to be translated
mission system.
and comprising video-signal components with
in a predetermined frequency range correspond
While there has been described what is at pres
ing to images to be translated in said system and
ent considered to be the preferred embodiment
undesirable shading components having a fre
of this invention, it will be obvious to those skilled
in the art that various changes and modifications 10 quency within said range and related to a fre
quency of scanning of said image, a repeater cir
may be made therein without departing from
cuit in said channel, and a trap circuit included
the invention, and it is, therefore, aimed in the
in said repeater circuit and resonant at said fre
appended claims to cover all such changes and
quency within said range for attenuating fre
modiñcations as fall within the true spirit and
quency components corresponding to said shad
scope of the invention.
ing components, said repeater circuit being
What is claimed is:
adapted to translate to said output circuit the
1. A television signal-translating system com
resultant signal including video-signal compo
prising, a signal-translating channel having an
nents having a frequency below the fundamental
input circuit and an output circuit, means for
applying t0 said input circuit a composite signal 20 frequency of said scanning frequency and sub
stantially free from said shading components.
derived by scanning continuous image lines of an
5. A television signal-translating system com
image to be translated and comprising vvideo
prising, a signal-translating channel having an
signal components within a predetermined fre
input circuit and an output circuit, means for
quency range corresponding to images to be trans
applying to said input circuit a composite signal
lated in said system and undesirable shading
derived by scanning an image t0 be translated
components having frequencies within said range
and comprising video-signal components within
and related to a frequency of scanning of said
a predetermined frequency range corresponding
image, and means in said channel having a fre
to images to be translated in said system and
quency characteristic also related to said scan
ning frequency for effectively removing from said 30 undesirable shading components having a fre
quency within said range and related to a fre
composite signal at least one lower frequency
quency of scanning of said image, a repeater
component of said shading components and for
circuit in said channel comprising a vacuum
translating to said output circuit the resultant
tube repeater having a cathode circuit, a paral
signal Which includes video-signal components
lel-resonant trap circuit included in said cath
having frequencies below said lower frequency '
ode circuit and resonant at said frequency with
component and is substantially free from each
in said range for attenuating frequency compo
said removed shading component.
2. A television signal-translating system com
prising, a signal-translating channel having an
input circuit and an output circuit, means for 4 0
applying to said input circuit a composite signal
derived by scanning an image to be translated
and comprising video-signal components with
in a predetermined frequency range correspond
ing to images to be translated in said system and
undesirable shading components having a fre
quency within said range and related to a fre
nents corresponding to said shading components,
said repeater circuit being adapted to translate
to said output circuit the resultant signal sub
stantially free from said shading components.
6. A television signal-translating system oom
prising, a signal-translating channel having an
input circuit and an output circuit, means for
applying to said input circuit a composite sig
nal derived by scanning continuous image lines
of an image to be translated and comprising
video-signal components within a predetermined
quency of scanning of said image, a trap circuit
frequency range corresponding to images to be
in said channel resonant at said frequency with
in said range for attenuating frequency compo 50 translated in said system and undesirable shad
ing components having a frequency within said
nents corresponding to said shading components,
range and related to a frequency of scanning of
and means in said channel for translating to
said image, a repeater network in said channel,
said output circuit the resultant signal includ
a pair of repeaters in said network adapted to
ing video-signal components having a frequency
below the fundamental frequency of said scan 55 produce output signals of opposite polarity, one
of said repeaters having a substantially uniform
ning frequency and substantially free from said
gain characteristic over the frequency range of
shading components.
said video-signal components and the other of
3. A television signal-translating system com
said repeaters having a gain characteristic over
prising, a signal-translating channel having an
input circuit and an output circuit, means for 60 said range related to said scanning frequency,
output circuits for said repeaters, and means for
applying to said input circuit a composite signal
coupling said output circuits so that frequency
derived by scanning an image to be translated
components of said composite signal correspond
and comprising video-signal components within
ing to said shading components are removed in
a predetermined frequency range corresponding
to images to be translated in said system and 65 said repeater network, said repeater network
being adapted to translate to said output circuit
undesirable shading components having a fre
of said channel the resultant signal substan
quency within said range and related to a fre
tially free from said shading components.
quency of scanning of said image, and a series
7. A television signal-translating system com
resonant trap circuit connected in shunt to said
channel and resonant at said frequency within 70 prising, a signal-translating channel having an
input circuit and an output circuit, means for
said range for attenuating frequency compo
applying to said input circuit a composite signal
nents corresponding to said shading components,
derived by scanning continuous image lines of
said channel being adapted to translate to said
an image to be translated at a plurality of scan
output circuit the resultant signal substantially
75 ning frequencies and comprising video-signal
free from shading components.
2,404,939
lll
components within a predetermined frequency
range corresponding to images to he translated
in said system and undesirable shading com
ponents having frequencies in a given band with
in said range and related to one of said scan
ning frequencies, a repeater network in said
channel, a pair of repeaters in said network
adapted to produce output signals of opposite
polarity, one of said repeaters having a sub
stantially uniform gain characteristic over the
frequency range of said video-signal components
and the other of said repeaters having a gain
characteristic over said range related to one of
12
of an image to be translated, said scanning being
effected in one direction at a predetermined
line-scanning frequency and in another direc
tion normal to said mst-mentioned direction at
a predetermined field-scanning frequency and
said composite signal comprising video-signal
components within a predetermined frequency
range corresponding to images to be translated
in said system and undesirable shading _com
ponents having frequencies within said range
and related to said line-scanning and said ñeld
scanning frequencies, means in said channel hav
ing a frequency characteristic related to said
said scanning frequencies, output circuits for
line-scanning frequency for effectively removing
said repeaters, and a coupling circuit having a
time constant short with respect to the period cf
another of said scanning frequencies for cen~
necting said output circuits of said repeaters so
from said composite signal shading-signal fre
quency components related to said line-scanning
that frequency components within said band of
frequency, and means in said channel having a
frequency characteristic related to said field
scanning frequency for effectively removing from
frequencies are effectively removed from said 20 said composite signal shading-signal frequency
composite signal, said repeater network being
components related to said field-scanning ire
adapted to translate to said output circuit cf said
quency and for translating to said output circuit
channel the resultant signal substantially free
the resultant signal including video-signal com
from said shading components.
ponents having a frequency below the funda
8. A television signal-translating system corn 25 mental frequency of said line-scanning fre
prising, a signal-translating channel having an
quency and above the fundamental frequency of
input circuit and an output circuit, means for
said held-scanning frequency and substantially
applying to said input circuit a composite sig
free from said shading components,
nal derived by scanning continuous image lines
WILLIAM F. BAILEY.
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