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Патент USA US2407655

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sept. 17, 1946.
Y 2,407,654-
Filed March '29, 1940
Feier ßesezwo 4
Patented Sept. 17, 1946
Peter Deserno, Berlin, Germany; vested in the
Alien Property Custodian
Application March 29, 1940, Serial No. 32.6,565
In Germany March 17, 1939
3 Claims.
(Cl. 178-7.3)
In television receivers the automatic amplitude
regulation meets with diñiculties. The simple
An electron tube H, Fig. l, is the last stage of
the intermediate frequency amplifier of a tele
vision receiver. To this tube a ñnal tube G1 is
connected through a transformer T. Tube G1
expedient of forming a mean value of the high
frequency energy in order to produce the regu
lating voltage is not possible because the mean
value changes in accordance with `the luminosity
values of the picture. In the case of bright pic
tures the mean value would be greater than Iwith
is arranged to act as a rectifier in known man
ner. The potential arising at a resistance W
and a condenser K acts to control the anode cur
rent of tube Gi by means of a control grid thereof,
dark ones.
as will be seen in Fig. 1. In the cathode lead of
Transmitting arrangements are known which
the tube Gi a coupling resistance A is included
are based on the so-called gap synchronization,
which is grounded in unipolar fashion. At re
that is, a synchronizing method in which the pic
sistance'A a voltage arises that corresponds to
ture signals increase toward positive values from
the rectified frequency mixture containing pic
an amplitude that corresponds to the black value
ture and synchronizing signals. The curve UA
of the incoming signal voltage, while the syn
of this voltage is illustrated in Fig. 2.
chronizing signals are extended from the black 15
A choke coil D acts to cut off all those fre
value in the reverse direction toward the zero
quencies which are above line frequency. At
value. With these transmitting arrangements a
points P, Q a voltage UPQ, Fig. 3, is effective which
regulating voltage may be obtained by taking
has the synchronizing impulses segregated. 'I‘he
from the frequency mixture the amplitude which
maximum value of this voltage hence equals the
is equivalent to the black value. This amplitude 20 black Value of the incoming voltage, as will be
merely depends upon the magnitude of the re
understood from Fig. 3. Condenser C thus
ceived high frequency energy, being independ
charges to acquire a potential Uc that corre
ent of the luminosity values of the picture.
According to the invention, in order to pro
duce the regulating voltage equivalent to the
black value the synchronizing signals are ñltered
out from the rectified frequency mixture, which
sponds to the black value.
Rectiñer G2 prevents the condenser from dis
charging through resistance A. Condenser C
discharges over resistance R. whenever the dark
value changes. The dimensions are such that
condenser and resistance shall afford a time con
stant of about a second.
contains the picture and synchronizing signals,
by means of a choke device while the remainder
of this mixture is conveyed to a condenser in 30
The regulating voltage is derived from con
such manner that its potential shall rise to be
denser C, as indicated by the arrowed line QC,
come equal to the black value. To such end the
in order to be conveyed to a control tube or sev
voltage supplied to the condenser passes through
a rectifier which prevents back discharge of the
condenser over the feeding source, such as a cou
pling" resistance. The condenser is thus always
charged to the maximum value of the feeding
voltage. The voltage supplied to the condenser
is applied to it with such ,a polarity that its po
tential increases whenever the arriving voltage
varies toward the black value.
Thel choke device by which the synchronizing
eral such tubes.
What is claimed is:
1. A device for regulating the amplitudes in
television receivers by a voltage equivalent to the
black value of the incoming signal voltage, which
comprises means for rectifying a frequency mix
ture containing picture and synchronizing sig
nals, said means including an output resistor
having a positive and a negative terminal,` a rec
tilier having an anode connected to said positive
signals are filtered out from the rectified fre
terminal and a cathode, a storage circuit com
quency mixture is dimensioned to cut off all such
frequencies as are above line frequency. The 45 bination comprising a resistance and a condenser
connected in parallel, connections from one end
Voltage at the condenser will hence not be able
of said combination to said cathode and from the
to increase beyond the black value, the synchro
other end of said combination to said negative
nizing impulses having been segregated.
terminal, and a choke device for removing the
In order to enable the potential at the con
denser to decrease in accordance with the black 50 synchronizing signals from said frequency mix
ture, whereby the condenser is charged to a po
value whenever the receiving amplitude increases,
tential corresponding to said black value..
a resistance is connected in parallel with this
2. A device according to claim 1, wherein said
condenser. Such resistance and condenser are
choke device is adapted to cut olf all frequencies
calculated to afford a time constant that accords
with the duration of several picture periods, such 55 above line frequency.
as a second.
3. A device according to claim 1, wherein said
In the accompanying drawing, Fig. 1 is a cir
resistance and condenser combination is adapt
cuit diagram showing one embodiment of the
ed to aüord a time constant defined by the du
invention, while Figs. 2 and 3 illustrate curves
ration of a number of picture periods. `
referred to in explaining the function of this em 60
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