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‘March 15, 1949.
. 2,464,420
Filed Dec. 31, 1943
Patented Mar. 15, 1 949
Richard L. Snyder, Jr., Princeton, N. J ., assignor
to Radio Corporation of America, a corporation
of Delaware
Application December 31, 1943, Serial No. 516,425
10 Claims. ( Cl. 250-150)
This invention relates to electron discharge de
vices and particularly to improvements in plural
trodes renders such tubes more complicated and
expensive than is now necessary or desirable.
beam cathode ray tubes of the type suitable for
“averaging-out” noise in radar and analogous sys
Accordingly, the principal object of the present
invention is to provide an improved plural-beam
cathode ray tube capable of “averaging-out” un
desired components from the signal waves or
tems for the communication of intelligence.
In the use of radar and similar equipment the
received signals are often affected by static and
other undesired extraneous electrical disturb
ances. Usually, radar and other “pulse” signal
trains are identical over a large number of operat
ingcycles and it has previously been proposed to
employ a tube capable of storing a large number
pulses in radar, radio and analogous systems for
the communication of intelligence, said tube being
characterized by the simplicity and economy of
10 its parts and by its trouble-free performance.
Other objects and advantages will be apparent
and the invention itself will be best understood
by reference to the following speci?cation and to
of these cycles in such a manner that the noise
?uctuations (which are usually random in char
acter) will integrate to some value close to zero,
while the‘ signals, which occur at regular inter
vals, are reinforced. When the stored cycles are
reproduced, the various Wanted parts of the signal
the accompanying partly diagrammatic sectional
view of a plural-beam cathode ray tube embody
ing the invention.
‘As indicated in the drawing, the present inven
tion contemplates and its practive provides a plu~
ral beam tube having a storage electrode consti
in the signal-to-noise ratio.
20 tuted simply of a sheet I of mica or equivalent
- Such noise reduction systems usually employ a
(1. e. opaque to electrons) insulating material and
plural-beam cathode ray tube for “averaging
a conductive signal plate or ?lm 3 which is
out” the noise and these tubes may be provided
mounted on or contiguous the back of the said
with storage electrodes of various types. By way
This storage electrode I, 3, is
of example: the storage electrode may comprise 25 mounted insheet.
the bulbous portion 5 of a highly
a “two-sided mosaic,” in which case the “put-on”
evacuated tube or envelope ‘I. The tube 1 is pro
and “take-off” beams are directed upon opposite
vided with two dependent‘hollow neck portions 9
sides of the screen (see British Patent 501,179).
and I I, within which the electron guns II! and I2,
Another tube heretofore employed in such a noise
respectively, are separately mounted. These
reduction system employs a single-sided eaesiated 30 “guns" I 0 and I2 may be of conventional ‘con
screen of special (“commutator type”) laminated
struction and, in any event, are each provided
construction. In’ this case both beams may im
either with a pair of horizontal and a pair of ver
coincide and produce considerable improvement
pinge upon the same side of the screen, prefer
tical de?ecting plates IIJH, IZH; IIlV, I2V, re
ably at different velocities (as to this see copend
spectively, or with magnetic de?ecting means for
ing application, Serial No. 492,658, ?led June 26, 35 imparting a scanning movement to the electron
1943). Alternatively, (as shown in application
beams from the separate guns Ill and I2. As in
Serial No. 496,741, ?led July 30, 1943, now U. S.
standard practice, grounded metallic coatings I3
Patent 2,416,914, issued March 4, 1947) , the stor
and I5 on the inner surface of the tube serve as
age screen may comprise a multiplicity of spaced
capacitor armatures upon which the signal is im
pressed by one beam, the second beam being ar
the second anodes for the guns II) and I2 re
The electron axis of the gun it is arranged at an
angle of substantially 90° with respect to the plane
of the target surface of the mica sheet I; thus its
manner calculated to “take-01f” the signal.
Irrespective of the advantages claimed for the 45 beam l4 strikes the said surface with normal inci
dence. The axis of the other gun I2 is elf-set
plural-beam cathode ray tubes of the prior art, it
slightly less than 90° from the axis of the gun III
may be said generally that the insulation and
and ‘is thus disposed at an acute angle (of from,
other problems incident to the construction and
1°, to say, 10°) with respect to the plane of the
use of their “mosaic type,” “commutator type”
and “multi-capacitor type’? signal-storage elec 60 target. The beam I6 from the gun l2 bombards
the same ora slightly larger area, of the target
ranged to scan the inter-armature space in a
surface I as does the beam I4 from the gun I0,
but with grazing incidence.
The bombarded side of the mica target I is
shielded by a pair of spaced apart plates I8, I8’
may be otherwise recorded as on a facsimile
machine (not shown).
It will be apparent from the foregoing that
the present invention provides an improved plural
beam cathode ray tube capable of “averaging
out" undesired components from the signal sur
which are arranged in parallel relation on op
posite sides of the path of the beam I4, and out
face or pulses in radan'radi-o and analogous sys
of the path of the beam I6. These plates I8, I8’
tems for the communication of intelligence and
are thus so arranged that they control the electro
that said tube is characterized by the‘simplicity
static ?eld on the gun side of the target; they
also serve :as collector electrodes for secondary 10 and economy of its parts and by its trouble-free
electrons from the said target.
It may also ?nd application in instances where
The relative potential distribution among the
in it is desirable to change the frequency of a
several electrodes is preferably (but not neces,—
radar signal. This need occurs when the outputs
sarily) as follows: gun cathodes—2000 volts, grid
of a number of radar equipments situated in dif
bias 9 to, say, 50 volts ?rst anodes-4700 volts
ferent locations must be correlated at a central
second anodes, collector plates (I8, I8’) and sig
station. Under these circumstances the high
nal plate (3) at about ground potential.
frequency radar signals are recorded at their nor
In operating the device of the invention», the
mal speed and taken off the record at a much
beam I4 is adjusted to such ahigh velocity that.
slower speed suitable for transmission over tele
the ratio of the secondary electrons to the pri
phone lines.
mary electrons is less than unity. The beam I6,
which strikes the target with grazing incidence,
has the same velocity as the beam I4 but because
it is grazing, as is well known, the secondary emis
sion ratio will be greater than unity. Therefore,
the normal beam I4 will act to charge the sur
face of the mica negative with respect to the col,
lectors I8, I8’ because the number of secondary
electrons leaving the surface of the‘ mica will be
I, claim as my invention:
1'. A storage electrode for a plural beam cathode
ray tube, said storage electrode comprising a tar
get consisting only of' an insulating material
which is opaque to electrons and a conductive
backplate for said insulating target.
2. The invention. as set forth in. claim 1 and
wherein said insulating material consists only of
less than the number of primary electrons. bom- . mica.
3. A storage device comprising an. evacuated
barding it. The opposite condition exists- in. the
a. storage electrode consistingv
region. bombarded by. the grazing electron beam
only of an insulating surface which is- opaque‘
I6. The grazing beam (I6) carries suf?cient cur
t_o.electrons.and a conductive backplate. for said
rent at all times to overcome the maximumnega
surface, means for generating a plurality of
tive charge that the normal beam I4 can put on
beams of. electrons within said envelope, and
means. for directing said plurality of electron
In operation, the static affected signal-bearing
beams, simultaneously, upon said. electron. opaque
waves are applied to the" grid ItiG of the gun
insulating surface.
I0. and modulate the beam It. and, thesaidv beam
4. A storage device comprising an evacuated
is. de?ected horizontally with, a linear sweep. at 4.0
envelope containing a storage. electrode. compris~
the same frequency as that of the operating. cycle
ing a. plane surface consisting only of aninsulat
of the radar or other equipment with. which the
ing material which is opaque to electronsrand- a
tube ‘l is associated. In addition, in. order. to
conductive backplate for said surface, and a.
spread the charged area on. the target I. for’ the
plurality of electron guns. mounted to project:
dual purpose of storing more charge and enlarg
their electronson theexposed side of said-insulat
ing thestorage area, this beam (I4) is_ deflected
ing surface.
in the vertical direction by a high frequency,
5. The invention. asset forth in claim, 4 and
voltage (which is applied to the verticaldeflecting
wherein the. axis of one of the said electron guns
plates 58V ina well-known. manner) well above
any frequency which. might be present in the 50 is disposed at an angle of substantially. 90° with
respect tov said insulating surface and the axis of
signal. The grazing beam_ I6, is unmodulated
the ‘other of said electron guns. ismounted at‘, any
but is preferably similarly spread or “fuzzedf’
acute angle with respect to said. surface.
so that its vertical displacementis. the sameor
6.. A. storage device comprising an evacuated.
greater than. that of the normal beam I4‘. The
horizontal de?ection of the grazing beam I?. is 5.5 envelopecontaining a storage electrode consisting;
only of. an insulating surface. which is-opaque. to.
equal‘ in amplitude and character tothatof the
electrons andaconductive backplate for saidzsure
normal beam 94. but, is preferably very much
face, means. for generating a. plurality. of. beams
lower in frequency. Under these conditions,.the
of. electrons within said envelope, means for.
normal beam puts the signal on the storage
electrode many times in the per-iodof horizontal 60 directing said electron beams upon said electron»
opaque insulating surface withv su?icient velocity
deflection of, the grazing or “take-off.” beam’ I61
to. cause the emission of secondary-electrons.
As mentioned above, the-grazing; beam I?-can
therefrom, and means for collecting, said sec..
always charge the mica surface I of: theitarget
to the collector potential. Thus, as the said-beam
'7. The’ invention as set forth in claim 6~ and:
I6 sweeps slowly over each portion of the target 65.
said collecting means comprises a pair
surface which has been charged by the normal
of-‘metalv plates ‘mounted in spaced: parallel‘ array
beam it, each of. saidportionsisdischarged and
on opposite sides of thepath of one of said beams
a displacement current flows, in. the circuit» of
and out-off the path of the other of said beams».
the back-plate 3. This displacement current. is
8. An electrondischarge devicecomprising an
a very low frequency facsimile of the original 7.0
evacuated" envelope containing an: electron gun;
signal in which the-noise or static; is-integrated
a- target consisting only. of; an. insulating surface.‘
or; balanced-out. The nQise-free-signal may; then
mountedin a: plane substantially normal-tothe»
be amplified‘ in the; usual manner and; viewed
axisv of: said .- gun. and‘ upon which. primary-elem
either with a» cathode ray ‘oscilloscope; (not
shown): having a lougrpersistent screen, or: it 7-6. trons fromssaida gun. are , adapted: to: impinge with:
a velocity calculated to release not more than one
secondary-electron for each impinging primary”
electron, a. second electron gun mounted along an
axis which forms an acute angle with said target
surface and adapted to project a second stream
The following references are of record in the
?le of this patent:
with a, velocity and at an angle calculated to
release more than one secondary-electron for
of primary-electrons upon said target surface 5
each impinging primary-electron from said sec
ond stream, and a metal backplate for said target 10
to which a displacement current is adapted to
?ow when said target surface is subjected to
bombardment with primary electrons from both
of said electron guns.
9. The invention as set forth in claim 8 and 15
wherein said ?rst mentioned electron-gun is pro
vided with means for directing its stream of elec
trons across said target at a certain rate and
signal upon said ?rst mentioned electron stream.
Bedford et a1 ______ __ Feb. 15, 1938
Gabor ___________ __ June .28, 1938
Vance et a1 ________ __ Feb. 21, 1939
Iams ______________ __ May 2,
Lubszynski ________ __ Dec. 2,
Hergenrother _____ __ Apr. 21,
Pierce ____________ __ July 20,
Teal _____________ __ Jan. 18,
said second mentioned electron-gun is provided
with means for directing its stream of electrons 20
across said target at a slower rate.
10. The invention as set forth in claim 8 and
wherein means are provided for impressing a
Donal, Jr. ___________ Jan. 2, 1945
Great Britain ______ __ Mar. '7, 1938
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