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Патент USA US2140285

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DeC- 13, 1933-.
P. T. FARNSWORTH
2,140,285
MULTIPLIER COUPLING SYSTEM
Filed March 22, 1937
INVENTOR.
P/u‘lo '7.~ Far'nsworl‘h
I
,6
22
BY
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QWQW»
2,140,285
Patented Dec. 13, 1938
UNITED STATES '
PATENT OFFICE
2,140,285
I
mmrrruna COUPLING srsrrnvr
Philo ‘T. Farnsworth, Spring?eld Township
Montgomery County, Pa., assignor to Fame
worth Television Incorporated, San Francisco,
Calif., ‘a corporation of California
-
Application -March 22, 1937, Serial ‘No. 132330
(UL 250-36)
By connecting an external resonant circuit
My invention relates to electron multipliers,
between
anode and cathode, and by supplying
and more particularly to a means and method
of coupling an external circuit to the multiplier the anode with a source of potential more posi
in such a manner that variations in load have tive than the cathode, I have been able to cause
the device to self-oscillate by causing the oscil
a minimum effect on the operation of the multi
14 Claims.
5
lation within the cathode chamber of an elec
plier.
tron cloud which repeatedly impacts the cath
provide an electron multiplier and coupling ode to generate secondaries. The device will
therefor; to provide a means and method of ab reach an equilibrium value, maintain itself in 10
stracting power from an oscillating electron self-oscillation, and power can be drawn there
Among the objects of my invention ‘are: To
multiplier with a minimum of oscillation dis
turbance; to provide a‘ means and method of '
collecting electrons after electron multiplica
tion; to provide a means of coupling a standard
15 frequency oscillator to a power consuming cir
cult; and to provide a simple,‘ eillcient and
stable means and method of abstracting power
from an» electron multiplier.
My invention possesses numerous other ob
20 jects and features of advantage, some of which,
together with the foregoing, will be set forth in
the following description of specific apparatus
embodying and utilizingmy novel method. It
is therefore to be understood that my method is
25 applicable to other apparatus, and that I do
not limit myself, in any way, to the apparatus
ofv the present application, as I may adopt vari
ous other apparatus embodiments, utilizing the
method, vwithin the scope of the appended
30
claims.
.
Referring to the drawing:
-
Figure 1 is a longitudinal sectional view
through a preferred form of the tube of my in
vention, together with a diagrammatic circuit
35 for placing the device in operation.
Figure 2 is a cross sectional view, taken as in
from.
,
a In common with other generators, this oscil
lator is also sensitive to variations in load, and
it is desirable, therefore, when the device is being
used as a master oscillator or standard fre
quency oscillator feeding a power consuming
circuit which may vary in its demand, to take
precautions that the power absorbed shall not
interfere with the operation of the oscillator.
The present invention deals with a means and
method of abstracting power from an electron
multiplier, preferably a diode, in such a manner
that it will not, to any great extent, interfere
with the operation of the multiplier itself.
Broadly as to method, my invention comprises
oscillating a cloud of electrons against and away
from a cathode capable of generating secondary
electrons at a ratio greater than unity upon each
impact therewith,‘ collecting a portion of the
electrons, segregating another portion‘ of the
electrons and directing them away from the os
cillating structure, and thereafter collecting
them within a unipotential space.
‘
Broadly, as to apparatus, my invention com
prises a cathode capable of emitting secondaries
at a ratio greater than unity upon electron im
pact therewith, and an anode so positioned and
dicated by the line 2—-2 in Figure 1.
Figure 3 is an enlarged sectional view of a energized as to cause an oscillation of an elec
tron cloud against and away from the cathode.
portion of the device showing an alternative
Self-oscillation is preferably obtained by con-_
method
of
coupling
the
output
of
a
multiplier’
40
necting the anode and cathode with a resonant
to a transmission line.
In my prior Patent No. 2,071,516, granted circuit and energizing the anode to a potential
more positive than the cathode, or, putting it
February 23, 1937, entitled “Oscillation genera
tor,” I have described a cold cathode electron another way, in this particular case making the
cathode more negative than the anode, as I pre
multiplier capable of self-oscillation. One modi
iication of this device has been shown to be a fer to work with the anode at ground potential.
A portion of the oscillating cloud is collected by
diode, and in my application, Serial No. 132,327, the
anode; another portion passes through an
filed March 22, 1937, entitled Diode oscillator aperture
in the cathode into the interior of a
tube construction, I have described several forms
Faraday cylinder, and is there collected. The
which
this
diode
may
take,
a
preferred
form
.60 being merely a cathode cylinder enclosing’ an Faraday cylinder is maintained at a potential
apertured anode, the cylinder having its inner higher than either the anode or cathode of the
multiplier, and in my preferred form is con
surface sensitized for the generation of sec
ondary electrons at a ratio greater than unity nected by a resonant circuit to the cathode.
The advantages of such a means and method
M upon electron impact therewith.
2,140,285
may be more fully understood by direct refer
ence to the drawing, which shows two preferred
structural embodiments of my invention utiliz
ing my improved method.
In Figure 1, an envelope I, which may be a
cylinder, is normally closed at one end and has
the other end closed by a reentrant stem 2.
Carried on the stem 2 by appropriate supports
is a cylindrical cathode l‘ and an apertured
10 anode 6, .which in this case may be formed by
winding a fine refractory wire 6 on upright sup
ports ‘I. I also prefer to have the two electrodes
concentrically positioned with respect to each
other.
16
At one point in the surface of the cathode I
cut a cathode aperture, and partially close it
with a screen 9.
While the size and shape of
this aperture is not important, I prefer to utilize
an aperture shaped to match the open end of
a tubular collecting electrode ill, the open end
being positioned closely adjacent the screen 6
end of the cylinder and the lower electrons being
collected by the side walls without going to the
end. Furthermore, the cylinder has a distinct
focusing action, and as most of the electrons
passing through the screen 9 will be of high
velocity, they will liberate heat at the area of
collection. Inasmuch as the sensitive caesium
surface which I prefer to use is readily affected
adversely by heat, it is of great advantage to
have the hot spot where the majority of'elec 10
trons are collected, as faraway as possible from
The tubular electrode‘ is an eih
cient means of collecting all the electrons pass
ing through the screen 9, and at the same time
keeps the impact area heated by the high ve
locity electrons at a distance away from the
sensitized cathode surface.
As an example of the e?iciency of the device,
. the cathode.
coupled in this manner to an external circuit
such as H, I have found that when 600 volts 20
difference is utilized between the multiplier anode
and cathode, and 2000 volts between multiplier
outside thereof. I also prefer to position the anode and collector III, that. anode 6 will, in
aperture midway between the open ends of the . one embodiment, pick up ten milliamperes of
cathode, as it is here that the‘ maximum cone}? current, whereas the collector willv pick up two
centration of electrons usually occurs. Tubular milliamperes of current. This amount of‘power
electrode 10 is positioned in a side arm ll of may beli’abstracted with the oscillator with a
the envelope, and is‘ supported by a lead I2v enter-"a minimum of disturbance of the amplitude‘ or
ing the end of the side arm.
frequency of the oscillator, and therefore the
80
In order to operate the device, I prefer to variations in circuit II have little or no effect on
and extending away from the cathode on the
connect a multiplier resonant circuit l4 between the oscillator ~itself.
'
I
anode 6 and ground. A radio frequency ground
It is obvious that circuit I‘! may be the power
is provided for cathode 4 by the connection of consuming circuit in the device shown in Figure
by-pass condenser l5 between cathode 4 and ‘ 1. In Figure 3 I have shown a coupling means
ground. Collecting cylinder I0 is raised to a whereby the power collected by cylinder l0 may
relatively high positive potential by collecting be transferred directly into a tubular conductor,
source I6 in series with a collector resonant cir
for use-as desired. Here, the lead I! for the
cuit i‘l. Energizing the device as shown, it will tubular electrode in passes, preferably,‘ through
be found that the anode 6 is held at a D. 0. the side wall of the envelope I, leaving the end
ground potential, but is connected to the cathode wall 20 of the side arm ll clear. Under these
40
through the resonant circuit l4 and by-pass con
conditions a tubular conductor 2| may be slipped
denser l6. Cathode 6 is maintained at a fixed on over the side arm outside of the envelope
negative D. 0. potential but with a ground R. F. wall, and is capacitatively coupled to the collector
potential. Thus there will be very little coupling i0. In this case collector I0 is fed from source
between collecting cylinder Ill and anode 6. l6 through R. F. choke 22.
Under these conditions the diode combination of
The devices I have shown here illustrate, of
cathode l and anode 6 becomes a self-oscillator. course, only two particular forms of power con
I prefer to sensitize theinner surface of cath
.suming circuit. Other structures and other cir
ode I so that secondary electrons will be emitted cuits embodying my invention will be apparent
on electron impact therewith at a 1 to 1 ratio to those skilled in the art, and are deemed to
50
when electrons impact at about twenty volts ve
fall within the scope of my invention as defined
locity, and if I form the cathode I of silver, within the appended claims.
a
oxidize its surface, and sensitize the surface with
The invention, while described as applied to
caesium, I find that secondaries can be produced a multiplier diode, is obviously applicable to any
with ratios as large as 10 or 12 to 1 at higher electrode where electrons repeatedly and cycli
velocities.
cally impact the surface thereof with a velocity :1 ca
Due to the action of the resonant circuit I4, sumcient to pass through an aperture therein.
and the fact that anode 6 is at a potential more
positive than cathode 4, continuous oscillation
of the diode structure takes place as described
in my prior applications referred to above, with
the electrons repeatedly and cyclically impact
ing cathode l and producing secondaries, some
of which are constantly being collected by anode
I and being used to maintain self-oscillation.
However, in the vicinity of the aperture screen
6 some of the electrons approaching the surface
of the cathode at this point will, of course, pass
through the screen and enter the space enclosed
70 by collecting cylinder Ill, and eventually be
collected.
I prefer to utilize a tubular collector for sev
eral reasons.
First, electrons of all velocities
will be collected substantially simultaneously, the
TI higher velocityelectrons passing through to the
I claim:
.
1. In combination, an electron multiplier com
prising an envelope containing a- unipotential
cathode capable of emitting secondary electrons ~
at a ratio greater than unity upon electron im
pact therewith, and having an aperture therein,
an anode on one side of said cathode, external
circuit means for causing electrons to make con
tinuous cyclical impacts with said cathode at a ,
velocity sufficient to produce secondaries and sus
tain oscillation of said electrons, and a hollow
collector on the other side of said cathode hav
ing an open end adjacent said aperture to re
ceive electrons passing therethrough.
70
2. In combination, an electron multiplier com
prising an envelope containing a unipotential
cathode capable of emitting secondary electrons
at a ratio greater than unity upon electron im- 1|
3
2,140,285
pact therewith, and having an aperture therein,
having an open end adjacent said aperture to re
an anode on one side of said cathode, external
circuit means for causing electrons to make con
ceive electrons passing therethrough.
tinuous cyclical impacts with said cathode at a
velocity su?icient to produce secondaries and
sustain oscillation of said electrons, and an elon
gated tubular electrode extending away from said
_
’
7. In combination, an electron multiplier com
prising an envelope containing a unipotential
cathode capable of emitting secondary electrons
at a ratio greater than'unity upon electron im
pact therewith, and having a screened aperture
cathode and having an open end adjacent said ' therein, an anode on one side of said cathode, ex
aperture to receive electrons passing there
through.
3. In combination, an electron multiplier com
prising an envelope containing- a unipotential
cathode capable of emitting secondary electrons
at a ratio greaterthan unity upon electron im
15 pact therewith, and having an aperture therein,
an anode on one side of said cathode, external
circuit means for causing electrons to make con
tinuous cyclical impacts with said cathode at a
velocity sumcient to produce secondaries and
sustain oscillation of said electrons, an elongated
tubular electrode extending away from said cath
ode and having an open end'adjacent said aper
ture to receive electrons passing therethrough,
and an external circuit connected from said
cathode to said tubular electrode including a
source of positive potential for said electrode.
4. In combination, an electron multiplier com
prising an envelope containing a unipotential
cathode capable of emitting secondary electrons
at a ratio greater than unity upon electron. im
pact therewith, and ‘having an aperture therein,
an anode on one side of said cathode, external
circuit means for causing electrons to make con
tinuous cyclical impacts with said cathode at a
velocity suilicient to produce secondaries and
sustain oscillation of said electrons, an elongated
tubular electrode extending away from said cath
ode and having an open end adjacent said apere
ture to receive electrons passing therethrough, an
40 external circuit connected from said cathode to
said tubular electrode including a source of posi
tive potential for said electrode, and a circuit
resonant to the oscillation frequency, connecting
45
said tubular electrode to said cathode.
5. In combination, an electron multiplier com
prising an envelope containing a unipotential
cathode capable of emitting secondary electrons
at a ratio greater than unity upon electron im
pact therewith, and having an aperture therein,
an anode on one side of said cathode, external
circuit means for causing electrons to make
continuous cyclical impacts with said cathode at
a velocity sui‘iicient to produce‘ secondaries and
sustain oscillation of said electrons, an elongated
said aperture to receive electrons passing there
through.
,
,
a
8. In combination,.an electron multiplier com-_
prising an ‘envelope containing a unipotential
cathode capable of emitting secondary electrons
at a ratio greater than unity upon electron im— 20
pact therewith, and having a screened aperture
therein, an anode on one side of said cathode, ex;
ternal circuit means for causing electrons to make
continuous cyclical impacts with said cathode at
a velocity su?icie'nt to produce secondaries and 25
sustain oscillation of said electrons, an elongated
tubular electrode extending away from said cath
ode and having an open end adjacent said aper
ture to receive electrons passing therethrough,
and an external circuit connected from said cath 30
ode to said tubular electrode including a source
of positive potential for said electrode.
9. In'combination, an electron multiplier com
prising an envelope containing a unipotential
cathode capable of emitting secondary electrons 35
at a ratio greater than unity upon electron im
pact therewith, and having a screened aper
ture therein, an anode on one side of said cath
ode, external circuit means ior causing electrons
to make continuous cyclical impacts with said 40
cathode at a velocity sufficient to produce sec
ondaries and sustain oscillation of said electrons,
an elongated tubular electrode extending away
from said cathode and having an open end adja
cent said aperture to receive electrons passing 45
therethrough, an external circuit connected from.
said cathode to said tubular electrode including a
source of positive potential for said electrode, and
a circuit resonant to the oscillation frequency,
connecting said tubular electrode to said cathode. 50
10. In combination,’ an electron multiplier
comprising an'envelope containing a unipoten
tial cathode capable of emitting secondary elec
tubular electrode extending away ‘from said cath
trons at a ratio greater than unity upon electron
impact therewith, and having a screened aper 55
ode and having an open end adjacent said aper
ture to receive electrons passing therethrough, an
external circuit connected from said cathode to
said tubular electrode including a source of posi
tive potential for said electrode, a circuit resonant
to the oscillation frequency connecting said tubu
ode, external circuit means for causing electrons
to make continuous cyclical impacts with said
cathode at a velocity sufficient to produce sec
ondaries and sustain oscillation of said elec 60
trons, an elongated tubular electrode extending
lar electrode to said cathode, and a tubular con
ductor surrounding said tubular electrode outside
of said envelope.
85
ternal circuit means for causing electrons to
make continuous cyclical impacts with said cath-~ 10
ode at a velocity su?lcient to produce secondaries
and sustain oscillation of said electrons, and, an
elongated tubular electrode extending away from
said cathode and having an openfend adjacent
6. In combination, an electron multiplier com
prising an envelope containing a unipotential
cathode capable of emitting secondary electrons
at a ratio greater than unity upon electron im
pact therewith, and having a screened aperture
ture therein, an anode on one side of said cath
away from said cathode and having an open end
adjacent said aperture to receive electrons pass
ing therethrough, an external circuit connected
from said cathode to said tubular electrode in 65
cluding a source of positive potential for said
electrode, a circuit resonant to the oscillation
frequency connecting said tubular electrode to
said cathode, and a tubular conductor surround
ing said tubular electrode outside of said envelope.
an anode on one side of said cathode, ex
70 therein,
11. The method of abstracting power from an
ternal circuit means for causing electrons to
‘electron multiplier, which comprises oscillating a
make continuous cyclical impacts with said cath
ode at a velocity sumcient to produce secondaries cloud of electrons against and away from a sur
and sustain‘ oscillation of said electrons, and a face to produce secondary emission at a ratio
75 hollow collector on the other side of said cathode greater than unity at each impact therewith,
4
2,140,2as
collecting a portion of said electrons, utilizing the
energy of the collected portion to maintain oscil
lation of said cloud, directing another portion of
said electrons away from said surface, and col
lecting said latter electrons in a unipotential
space.
12. The method of abstracting power i'rom'an
electron multiplier, which comprises oscillating a
cloud of electrons against and away from a sur
face to produce, secondary emission at a ratio
greater than unity at each impact therewitnvcol
lecting a portion of said electrons, utilizing the
energy of the collected portion ‘to maintain oscil
lation of said cloud, directing another portion of
15 said electrons away from said surface,’ and elec
trostatically focusing said latter electrons on a
spot removed from said surface.
13. The method 01 abstracting power from an
electron multiplier, which comprises oscillating a
cloud of electrons, against and away from a sur
face to produce secondary emission at a ratio
greater than unity at each impact therewith, col.
lecting a portion of said electrons, utilizing the
energy of the collected portion to maintain oscil
lation of said cloud, directing another portion of
said electrons away from said‘ surface, and col
_ lecting all velocity components of said latter elec
trons at substantially the same time.
14. The method of abstracting power from an
electron multiplier, which comprises oscillating a
cloudoi’ electrons against and away from a sur
face to produce secondary emission at a ratio
greater than unity at each impact therewith, 001-‘
lecting a portion of said electrons, utilizing the
energy of the collected portion to maintain oscil
lation of said cloud, directing another portion of
said electrons away from said surface, collecting ll
all velocity components of said latter electrons at
substantially the same time, and utilizing the
energy of said latter electrons in a work circuit.
Piano '1'. FARNSWORTH.
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