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Патент USA US2115866

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`May 3, 1938.
Original Filed Nof. 16, 1932
. )fg‘ mm,
Patented May 3, 1938
2,115,866 I
Heinz Lux, Berlin, Germany, assigner to Tele
funken Gesellschaft für Drahtlose Teiegraphie
m. b. H., Berlin, Germany, a corporation of
Original application November 16, 1932, Serial
No. 642,845. Divided and this application May
27, 1936, Serial No. 82,001. In Germany No
vember 17, 1931
6 Claims. (Cl. Z50-27.5)
- This application is a division of my applica
tion, Serial No. 642,845, filed Nov. 16, 1932, for
“Double grid electron tube andcircuit” which
has now matured into Patent No. 2,067,156.
In the methods discovered by Barkhausen and
Kurz forproducing oscillations by means of brak
ing fields, the electrons, as~is known, perform
pendulum movements around the highly positive
in such manner so as to be on a straight line
grid of a 3 electrode tube in which the anode
has the potential of the cathode or a weak nega
through grid 2 perpendicular with respect to
tive voltage. The electrons emitted by the ñla
ment participate, if they are not aifected by par
ticular measures, only to the smallest extent in
the pendulum movements, whereas the major
amount of electrons move in a straight line to
wards the grid where they produce heat and
thereby limit the loading capacity of the tube.
The proportion between the grid losses and the
oscillating power is about 100:1. An explanation
for this phenomenon can be found when con
sidering the electric ñeld between grid and fila
ment, the shape of which is shown in Figure 1.
All of the electrons which enter the straight or
only slightly curved fields will move to the grid
in a straightv line. Only at such places where
the lines of force have a considerable curvature,
the electrons do not follow the latter but main
tain, due to their mass inertia, the straight path
and then carry out the desired pendulum move
The object of the present invention is to pro
vide such field distribution so as to avoid as
much as possible straight lines of force extending
between the grid and the filament.
As a result
a larger-portion of the emitted electrons is caused
3. to carry out pendulum movements and the sup
ply of Ynon-oscillating electrons to the grid is
thereof. In order to obtain the desired field -dis
tribution it is suggested to provide for instance
a second grid between the filament and the posi
tive grid electrode. In Figure 2 the filament is
shown as l, the positive grid is shown as at 2 and
the anode of a S-electrode tube is designated at 3.
The wires of .the second grid li must be arranged
anode 3 and ñlament I. When a spiral shaped 10
grid is provided, two helices are obtained (Fig. 4)
which are of equal pitch but of a different diam
eter and the wires as such determine an-orthog
onal screw surface. Where a rod shaped grid is
used, as shown in Fig. 5 the single rods must be
in .the same radial plane. When these require-A
ments are fulfilled the field distribution follows
the course shown in dotted lines in Figure 2.
A deviation from this required arrangement would
however be of detrimental eiïect to- a tube, as
compared with a tube having only one grid. The
grid 4 may either be connected .to the cathode,
or may have a negative potential applied to it.
It will charge negatively as a free grid and thus
also fulfill its purpose.
In order to prevent the electrons from directly
impinging upon the grid, a screen may be pro
vided composed of dielectric materials such as
mica, glass or quartz whereby the shape must be
in accordance with the same principle as re
ferred to above in connection with a metallic
screen grid of the type shown in Figs. 4 and 5.
In Fig. 6 there is shown the modification just
described in connection with rod shaped grids.
The screen of dielectric material is indicated by
2E” and the positive grid of metal by 20".
The manner in which my improved double
grid tube may be used in a transmitter is illus
reduced. This causes a decrease of the grid load
and also an increase of the grid potential which
in turn enables a decrease of the wave length.
trated in Figure 3. Modulating audio frequency»
potentials from microphone 5 and audio fre 40
In the drawing Fig. 1 illustrates diagrammati
cally the electric field between the several elec-
through the transformer IIl.- The secondary of
quency amplifier 6 are applied to the anode 8v
trodes of a three-electrode tube. Fig. 2 illus
trates -diagrammatically a four-electrode tube
o according to the present invention, and the elec
transformer I I3 is connected in series with the
lead I2 maintaining the anode at a highly or
tric field between the electrodes thereof. Fig. 3
illustrates a practical embodiment of the tube
shown in Fig. 2 in connection with either a trans
filament I4 which is energized to an electron
emitting condition by the action of heater bat
mitting circuit or a receiving circuit.
The grid 2li through which the electrons make
their pendulum-like movements is maintained at 50
a highly positive potential by the action of source
2l applying a positive voltage to it through lead
22. Chokes 24 are provided to prevent undesired
iiow of high frequency current in the polarizing
Fig. 4 is a
detail view showing schematically the relation of
one form of a pair of grids according to the in
vention, Fig. 5 is a transverse sectional view show
ing the relation of another form of a pair of
grids according to the invention, and Fig. 6 is a
55 view similar to Fig. 5 and showing a modification
slightly negative potential with respect to the 45
tery I6 and filament voltage adjusting resistor I8.
leads and sources.
The added grid 25 according to my present in
vention is maintained either at filament potential
or at a slightly negative potential by the suitable
a radio frequency transformer and rectangle 6
would indicate apparatus including a second
tapping of lead 28 on to negative biasing source 30
or directly on to the filament lead 32. Oscillatory
energy will then be developed in the Lecher wire
sired, audio frequency amplifiers for actuating
loudspeaker 5. Here also the radio frequency
system 30 tuned by the action of short circuiting
condenser 32. A transmission line 34 may then
be coupled to the Lecher wire system as shown so
10 as to suitably load the same and feed into a radi
oscillator and second detector as well as, if de
transformer l0 may be placed, if desired, in series
with the inner grid 26 or outer grid 20.
What I claim is:
1. An electron discharge device comprising an
electron emitting electrode, an electron receiving 10
electrode in cooperative relation with said first
ating antenna 36.
Modulation is effected by Virtue of Variation in _ electrode, said electrodes being disposed one with
plate potential due to the action of transformer l 0
in the other, and insulating means interposed be
in series with the plate 8. If desired, the sec
tween only the aligned portions of said electrodes
15 ondary of the transformer IU may be inserted with for preventing the flow of electrons in a rectilinear
similar effect in the lead 28 for the negatively path between said electrodes.
maintained grid or grounded grid, or, in the lead
2. A Barkhausen oscillator comprising a cath
22 which maintains the grid 2U at a high positive ode, an electrode in juxtaposition to said cathode,
an electron receiving electrode intermediate said
It is to be noted that the perforations in the
cathode and said first electrode, and insulating
grids are arranged so as to be in line radially with
means adjacent said electron receiving electrode
respect to the filament. The alignment of the for preventing the. ñow of electrons thereto in a
perforations is indicated by the dot and dash rectilinear path from said cathode.
lines 40.
3. An electron discharge device comprising an
25 In the event that spiral grids are. used, they electron emitting electrode, an electron receiving
should be so wound as to be of the same pitch and
electrode, a third electrode outside of said electron
arranged so that when viewed in cross-section, the
receiving e1ectrode,-and an insulating shield ln
cross-sections will be in similar alignment as indi
termediate said electron emitting electrode and
cated in Figure 4. In the event that a rod-like
all portions of said electron receiving electrode
,., structure is used for grids, as shown in Figs. 5 and
in alignment with said electron emitting electrode.
6, the rods 26’ and 2U' of the respective grids in
4. An electron discharge device comprising a
Fig. 5 and the rods 26" and 2D" of the respective linear cathode, an electrode including a plurality
grids in Fig. 6 should be arranged so that they lie, of wires disposed parallel to one another and to
in cross-section, upon the same radial line run
said cathode and mounted in a cylindrical bound
35 ning through the cylindrical cathode or filament. ary about said cathode, and insulating shielding
If desired, as already indicated, the inner grid means between aligned portions of said cathode
(26, 26’ and 25") may be left floating, in which
and said Wires.
case electrons impinging thereon will give it the
5. An electron discharge device comprising a
desired negative polarization.
cathode, an anode and a pair of grid electrodes
Also, my improved tube may be used in a receiv
Which have their grid wires in alignment in re
' ing system in which case antenna 36 would be a
spect to the direction of electron flow, the grid
receiving antenna and the voltages and Lecher electrode next adjacent the cathode being formed
wire system 30 would be so adjusted that the tube of dielectric material.
would produce oscillations at the frequency of the
6. An electron discharge device comprising a
incoming waves. Hence, by virtue of an autodyne cathode, a cylindrical outer electrode surrounding
effect audio frequency energy may be derived from the cathode, a pair of grid electrodes concentri
transformer lß amplified by an audio frequency cally arranged about thecathode and interposed
ampliñer 6 and fed to a suitable translating device in the space between the outer electrode and the
or loudspeaker 5. Here also, the transformer l0
cathode, the -grid electrode next adjacent the
` may be placed in series with the other grid 26, or
outer electrode being formed of conductive mate
in series with the positively maintained rgrid 20. rial, and the grid electrode next adjacent the
Also, for receiving, it is not necessary that the cathode being formed of non-conductive material
oscillator oscillate at the mean frequency of the
and disposed in the path of the electron flow from
received waves. The tube may be adjusted by cathode to the conductive grid electrode whereby
55 means of the voltages applied and the Lecher
wire system to produce oscillations which will beat
at a high frequency with the incoming waves. In
that event, transformer I6 would be replaced by
the electron ñow between said electrodes in a rec
tilinear path is prevented.
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