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. 24, 1946.
|. wóLFF
2,413,276
CATHODE RAY APPARATUS
Filed Nov. 19, 1942
2 Sheets-¿Sheet l
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„iugm
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INVENTOR
Wmo?
ATTORNEY
Dec. 24, 1946.
l. woLFF
2,413,276
CATHODE RAY APPARATUS
Filed Nov. 19, 1942
2 sheets-sheet 2
/
TTORNEY
¿naar
Patented Dec. 24, 1946
UNITED STATES PA’E'ENT
tries
2,413,276
oATHoDE-RAY APPARATUS
Irving Wolü, Princeton, N. J., assignor to Radio
Corporation of America, a corporation of Dela
Wall‘e
Application November 19, 1942, Serial No. 466,129
12 Claims. (Cl. 2511-155)
My invention relates to improvements in cath
ode ray tubes and apparatus and particularly to
tubes and apparatus and methods for developing
a curvilinear or circular time base utilized for in
dicating electrical phenomena.
It has been proposed in the prior art to utilize
a cathode ray tubehaving a target screen for
measurements or for picture transmission where
in the time base is evidenced by a closed curved
2
of the necessity of producing quadrature deflec
tion potentials which for circular traces must be
matched both as to quadrature relationship and
potential variations. Thus a change in frequency
in the applied quadrature deflection potentials
requires a change in the circuits developing these
potentials. In addition, the potentials for- such
deflection must be relatively high especially in
tubesY operating at relatively high voltage, to
trace either on a luminescent screen as shown by
obtain an intense trace on a luminescent screen.
Heymann, 2,200,745, or on a target of the mosaic
Such high potentials necessitate extensive equip
type as shown by Hickok, 2,272,842. Tubes hav«
ing luminescent screens wherein the cathode ray
beam is deflected to form a closed curved trace,
ment which is not only bulky but necessitates an
increase in the weight factor wherefsuch appa
ratus is utilized in aircraft applications.
y
In accordance with kmy invention I obtain `>a
curved deflection trace in a cathode ray tube by
such as a circle on the screen, have particular
application in radio position and distance indi
cating equipment wherein the distance or posi
tion is indicated by a radial deflection of the
beam from the normally produced circular trace.
It has been customary'to form such curved closed
traces utilizing quadrature deflection. For eX
ample, two mutually perpendicular'pairs of de- _
ilection plates are supplied with sine-wave po
tentials, one of which is in quadrature with the
directing an electron beam into an axial mag
netic or radial electrostatic vfield at an angle to
the axis and with its projection tangent toa
circle about the axis'of the field. I deflect the
beam to vary> the angle of entrance into the-field
to control and vary the pitch of the helical path
of the beam. More particularly, I have found
other. Such arrangements are not as iiexible as
that the degree of angular deflection imparted
to the beam is inversely proportional to the angle
desired and inv addition require rather critical
adjustment to maintain theV quadrature rela
the beam makes with a plane perpendicular to
the axis of the field. Still further, I direct the
tionship.
electron beam through the field thereby imparting
'
-
Among the objects of my invention are: to pro
an eifective rotation to the beam and I'so limit
vide apparatus for and a method of producing a 30 the field in length that the beam emerges from
curved time base for cathode ray beam deilec
the ñeld and continues in a‘direction determined
tion, to provide means for obtaining curved time
by the angle of entrance into the field and I then
intercept the beam by a target, such as of the
to phase delay or quadrature networks, to pro
luminescent type, to provide the curved time
vide apparatus wherein circular time base de 35 base. Following emergence from the field the
flection may be obtained without recourse to
electron beam may be given further radial de
critically adjusted circuits, to provide a highly
ilection, such as a signal deflection, to produce
bases for cathode ray deiiection without recourse
stable tube inherently capable of producing closed
deñection traces having uniform curvature to
indications of the phenomena to be observed.
The foregoing description of the principles of
provide a curved time axis in which substantially 40 my invention will be more readily appreciated by
any relationship may exist between angular po
references to Figure 1 wherein the apparatus or
sition and time, and to provide a method and
tube per se comprises an elongated envelopedy
means whereby a spiral time axis may be ob
having a neck portion 3 and a frusto-conical
tained. These and other objects, features, and
portion 5 which is provided at its closed end with
advantages of my invention will become evident 45 a luminescent screen l. The electron beam is
upon consideration of the following description
developed by an electron gun preferably disposed
and the accompanying drawings wherein:
to direct the-beam at an angle to the longitudinal
Figure 1 shows cathode ray apparatus, in sec
axis of the envelope portions 3 and 5 and to one
tional plan view, made and operated in accord
side thereof and comprises the conventional
ance with my invention; and
50 cathode 9, control electrode Il'connected'to the
Figure 2 is a perspective View, partially in sec
usual biasing source, a first anode I3 and a second
tion, of a greatly simplified embodiment of my
anode l5 so that the developed electron beam in
an undeflected position is directed preferably per
As indicated above, it is diificult to provide
pendicularly to a radius of a circle surrounding
closed curved traces in cathode ray tubes because 55 the axis andY at an angle to a plane normal to
invention.
Y
-
2,413,276
4
quency, timing, and amplitude of the applied
said longitudinal axis. The electron beam may be
signal.
grid modulated to vary the beam intensity such
It should be particularly noted that the voltage
as by applying potential variations across the
applied to the deflecting plates 25-21 may be of
terminals il, the shunt i9 shown in dashed lines
being provided when no modulation is applied. Ul any desired time function and that the rate of
angular deflection will approximately follow the
The electron beam is developed by applying po
same time function. To obtain uniform circular
tentials between the cathode and the first and
sweep a linear sawtooth deñection of amplitude
second anodes, such as by a battery or potential
sufñcient for one rotation may be used. However,
source 2! provided with a bleeder 23. Situated on
if it is desirable to spread any part of the scale,
either side of the electron gun axis I provide
means to deflect the electron beam such that
the rate of travel along said longitudinal axis de»
pends upon the degree of deflection. Such de~
flection means may comprise a pair of deflection
plates ESL-2l although magnetic deiiection means
may be provided in lieu thereof.
g In accordance with my invention I direct the
‘deflected beam into a longitudinal axial field such
as a magnetic iield of relatively long extent or
length developed by a coil 29 enclosing the prin
cipal portion of the neck section 3 between the
intersection of the electron gun envelope portion
and extending in the direction of the target or
screen 1. The beam upon entering this magnetic
an exponential or other type of sweep having non
uniform voltage change may be employed. Blank
ing circuits whose construction is well known in
the art may be used to eliminate the effect of the
return line by 4developing blanking signals which
are applied across the terminals il. A spiral
type of indication> either with uniform or non
uniform angular velocity may also readily be ob
tained with my tube. This result may be accom»
plished by imposing some of the sweep deflecting
voltage between the central radial deflecting elec
trode 39 and the electrode ¿l l. A fixed radial elec~
trostatic field may be used in place of the longi
tudinal magnetic iield in order to supply the
ñeld will follow helical paths over an extent de
radial force to cause the electrons to assume spiral
termined by the angle of incidence between the
entering beam and the longitudinal magnetic field
netic field is to be preferred because of better fo
paths. However, in general the longitudinal mag
cusing action.
A better understanding of the motion and tra
throughout the length of the field. Upon termi
jectory of the electron beam may be obtained by
nation of the helical path, the electron beam conn
reference to Figure 2 wherein an envelope en
tinues to the screen 'l along unconstrained paths
closes an electron gun 4 and target structure 8.
and impinges the screen at a position determined
In contradistinction to the previously described
by the original deflection such as by the plates
tube the electron gun 4 is located within the longi
25-21. Since the electron beam enters the field
at these different angles and follows a path whose 35 tudinal field developed by the coil ß, no deflection
being imparted to the beam since this showing is
extent is determined by this incident angle, the
merely for purposes of explanation. I position the
beam emerges at various points lying on a circle,
electron gun 4 to emit the electrons in a 'direc
the beam then continuing along diverging paths
so that the beam will follow a helical path
to the screen l.
The dashed lines show repre~
sentative beam paths for the 180 degrees of de
fiection by the plates 25--2l~ The electron beam
may be developed and deñected at relatively low
potentials and further accelerated along the
length of the envelope portions 3 and 5 by a
series of electrodes surrounding the beam. For
example, the electrodes 3 l-3'l may bein the form
of electrically conductive coatings positioned in
the order named in a direction from the electron
tion at an angle to the axial magnetic field and
tangential to a circle about the axial magnetic
ñeld. Only one beam path is shown since no
deflection of the beam is provided. Thus the
dashed line in Figure 2 represents the beam mo
tion along a helical trajectory intercepting the
, target 6 at the point IB, this helical path >being
of uniform diameter and pitch. It will be noted
that the projection of the beam paths on a plane
normal to the ñeld axis is always, tangentto the
beam path as it leaves the electron gun. How
gun to the screen and may be supplied with oper
ating potentials from the potential bleeder 23. 50 ever, assuming that the location of the electron
gun 4 is moved so that the beam is initiated at
Further electrodes of similar formation, such as
a dilferent angle to a plane normal to the longi
the electrodes 39 and lll, may be provided along
tudinal axial field, the radial 4deflection will be
the frusto-conical portion E and may likewise
different from that shown kand the point at which
be operated from the potential source 2l or bleeder
the beam intercepts the target will be displaced
23. While I have shown these electrodes as pro
from the point lll such as to the point l2. The
gressively more positive in the direction of the
movement of the electron gun to initiate the beam
screen, it will be appreciated that depending upon
at different angles to this plane is thus equiva
the length and diameter of these electrodes the
lent to deflecting the beam by the plates 25-21
potentials applied thereto will vary with differ»
in Figure 1 thereby causing the beam to describe
ent constructions although the final electrode or CH a path on the screen 'l as modified by radial den
electrodes such as 3B and ¿il are preferably operm
ated at high positive potentialsl with respect to `
the cathode 9 to obtain an intense luminous trace
on the screen l.
Following emergence of the electron beam from
the longitudinal magnetic field, radial deflection
components may be imparted to the beam by a
centrally disposed deñecticn electrode 43 to which
deilection potentials, such as representative of ~
signal deñection, may be applied with respect to
the surrounding electrode ¿i l. Thus the electrodes
4! and 43 provide a concentric system which de~
fleets the electron beam radially from the curved
path or trace to provide an indication of the fre~
ilection components applied between the elec
trodes 4I-43.
The amplitude, that is the diameter, oi’ the
trace may be controlled by varying the ratio be
tween the field strength, such as the magnetic
field delevoped by the coil 2@ and the potential
applied to the various electrodes determinative
of the electron beam velocity while the beam is
under the influence of the magneticñeld. For
example, the stronger the magnetic field devel
cned by the coil 253, the smaller will be the diam
eter of the trace developedppon the screen 'l for
a given beam velocity. Similarly, the lower the
velocity ,of the beam while under the influence
2,413,276
5
of the magnetic field, the smaller will be the di
ameter of the beam trace on the screen 1 for a
given magnetic field strength. Consequently, the
6
stantially parallel to and surrounding a longitu
dinal axis, developing an electron beam, direct
ing said beam into said field in a direction at an
diameter of the trace may be adjusted within the
angle to the said axis and tangentially to a right
spatial limits of the screen by controlling the Cl circular1 cylindrical surface surrounding said
ratio of the field strength to beam velocity. Pref
axis, varying said angle at which said beam in
erably, the magnetic ñeld strength is of the or
tercepts said ñeld to cause said beam to follow
der of 50 to 100 gausses, being relatively strong to
helical paths, and intercepting said beam with a
minimize eiîects produced by extraneous mag
target surface.
'
3. Cathode ray apparatus comprising an evac
netic fields. Furthermore, for particular con
structions it may be found that the fringe por
uated envelope, a target within said envelope
tion of the field developed by the coil 29 interacts
adapted to be impinged by an electron beam ap
proaching said target substantially about an
in the electron gun or deflection space so that
magnetic shielding means such as a slotted shield
axis normal thereto, electron beam forming
45 may be provided between the deñection plates
means within said envelope positioned to direct
25----21 and the magnetic coil 29. The effect of
an electron beam along an undeflected path at
the shield 45 may be extended by an external
an angle to the said axis, field means for estab
lishing a ñeld of force extending along said axis
shield as shown at 6l, the need for such shield
ing arrangements being determined by the dis
for rotating said electron beam around said'lon
gitudinal
and means adjacent said electron
tance between the deflection plates 25--21 and
gun for directing the electron beam at a varying
the coil 29.
‘
angle to said longitudinal axis in a plane paral
It will be appreciated that my method of elec
tron beam deflection is not dependent upon the
lel thereto and including said undeilected elec
tron beam path.
specific apparatus disclosed above, but that the
4. Cathode ray apparatus comprising an
method may be practiced entirely by hand. For
elongated evacuated envelope, a target near one
example, an electron beam developed in any
end of said envelope adapted to be impinged by
manner may be deflected by hand such as by
manually moving the electron gun through an
an electron beam, electron beam forming means
near the opposite end of said envelope positioned
angle in a predetermined plane, developing a
with its axis at an angle to the longitudinal axis
magnetic field such as forming a ñeld between ‘
of said envelope, ñeld means for establishing a
apertured pole faces to develop the helical mo
field of> force` for rotating said electron beam
tion of the beam, radially deflecting the beam by
around said longitudinal axis, and means adja
manually manipulating an electrostatic element
following emergence of the beam from the longi
cent said electron gun for directing the electron
beam at a varying angle to said longitudinal axis
tudinal magnetic field and intercepting the beam
in a single plane parallel thereto and including
to render it manifest.
said electron beam.
v
While I have described my invention with par
5. Cathode ray apparatus comprising an
ticular references to its use in tubes of the lu
minescent screen type, it will be appreciated that
evacuated envelope, a target near one end of and
its application is not so limited, the principles 40 transverse to an axis extending within said en
and advantages of my invention accruing equally
velope adapted to be impinged by an electron
to tubes of the television transmitting type
beam, electron beam forming means near the
opposite end of said envelope positioned to direct
shown by the above-mentioned Hickok patent.
an electron beam along a path at an angle to
In addition, while I have described my invention
particularly with respect to an axial magnetic
and offset from the said axis, means for estab
lishing a magnetic field having lines parallel to
ñeld, it will be appreciated that an axial elec
trostatic ñeld may be used substantially with
and surrounding said axis for rotating said elec
equal advantage. Such a ñeld may be developed
tron beam in a helical path around said axis,
between two concentric cylindrical electrodes
and means adjacent said electron gun for di
maintained at different potentials and extend- ,
recting the electron beam at a varying angle to
ing over the space occupied by the magnetic coil
said longitudinal axis in a plane parallel there
29 so that the electron beam is directed into the
to and including said electron beam path.
ñeld in a direction at an angle to the axis of the
6. Cathode ray apparatus comprising an
equipotential lines of the field and with its pro-`
elongated envelope, a target adjacent one end
jection tangent to a circle about the axis of the
of said envelope, an electron gun adjacent the
opposite end of said envelope positioned to de
field. Furthermore, while I have described only
two particular embodiments of my invention, it
velop and direct an electron beam at an angle to
will be appreciated that many variations thereof
and offset from said longitudinal axis, means
adjacent said gun and said longitudinal axis to
will occur to those skilled in the art and that my
invention is not limited to the speciñc apparatus 60 deilect the beam in a plane parallel to said axis
and magnetic means to develop a longitudinal
shown or its mode of operation except as set
magnetic iield extending from the point of inter
forth in the appended claims.
section most remote from said target and in a
I claim:
direction toward said screen, parallel to said
l. The method of defiecting an electron beam
over a target surface comprising sweeping the 65 plane, and surrounding said axis to direct said
beam toward said target along helical paths.
beam in a plane through a predetermined angle,
7. Cathode ray apparatus comprising an
developing an axial magnetic field having lines
evacuated
envelope, a luminescent target adja
of force in said plane but at an angle to said
cen't one end -and intercepting a Alongitudinal
beam and to one side of the centrally .disposed
axis of said ñeld to cause said beam to follow 70 axis Within said envelope, an electron gun in
cluding a plurality of apertured anodes with the
helical paths, and intercepting said beam with a
apertures aligned along a line disposed at an
target surface.
acute angle to the longitudinal axis of said en
2. The method of deflecting an electron beam
velope to develop and direct an electron beam
over a target surface comprising developing an
axial field having lines of force extending sub 75 in a plane parallel to said longitudinal axis, de
2,413,276
8
flection means to shift the direction of said
beam in said plane, magnetic means to develop
a longitudinal magnetic field substantially paral
lel with said axis and intercepting the plane of
deñection of said beam to sweep said beam in 5
screen, a pair of deflection plates adjacent said
electron gun to deflect the electron beam in a
plane intercepting said magnetic ñeld parallel to
the lines of force of said ñeld to cause said beam
to follow a multiple of helical paths intercepted
combination with said deñection means over a
by said screen in a curved trace thereon, and a
curved path on said target and a pair of tele
scoped concentric electrodes between said mag
netic means and said target to deflect said beam
in a direction radially of said longitudinal axis.
10
pair of telescoping concentric electrodes adapted
to have Aa signal deñection potential applied
therebetween positioned Without the magnetic ‘
ñeld developed by said coil and closely adjacent
8. Cathode ray apparatus comprising an
said luminescent screen to radially deflect said
evacuated envelope, a luminescent screen posi
electron beam from said curved trace.
tioned transversely of and at one end of said
10. The steps in the method which comprises,
envelope, an electron gun at the opposite end of
producing a ñeld, projecting an electron beam
said envelope positioned to develop and direct an 15 into said ñeld at an angle to the lines of force
electron beam alongV an initial path at an angle Y thereof, and causing the electrons of the beam
to said screen, an elongated magnetic field de
to travel in a helical path through said field and
veloping coil positioned with its longitudinal axis
cyclically varying said angle'to vary the path
substantially normal to said screen and at an
and cause the electron beam to pass through
angle to the initial path of Said beam to develop 20 a plane at a multiplicity of points of a continu
a magnetic iield in the path of said beam, a pair
ous curve around the axis of said field.
of oppositely disposed deflection plates, one on
11. The steps in the method which comprises,
either side of the undeñected path of said beam
producing a constant ñeld, projecting an electron
and adjacent said electron gun to deflect the
beam into said ñeld at an angle to the lines of
electron beam in a plane parallel to and offset
force thereof, and causing the electrons of the
from the axis of said magnetic coil, and a pair
beam to travel in a helical path through said
of concentric telescoping electrodes along said
field and cyclically varying said angle to vary
axis and closely adjacent said screen to radially
the path, and cause the electron beam to emerge
deñect said electron beam from the path on said
from the iield at a multiplicity of substantially
screen determined by the angle of deñection in 30 contiguous points of a circle having its centerV
said plane.
in the axis of said ñeld.
9. Cathode ray apparatus comprising an
12. 'I'he method of producing a circular trace
evacuated envelope, a luminescent screen at one
on a target which comprises, producing a constant
end of said envelope, an electron gun at the oppo-
field, projecting an electron beam into said ñeld
at an angle to the lines of force thereof, and
causing the electrons of the beam to travel in a
site end of said envelope positioned to develop
and direct an electron beam along an undeiiected
path not intercepted by said screen, a magnetic
ñeld generating coil surrounding a portion of
said envelope and positioned to develop a ñeld
having lines of force at an angle to and inter
cepting the undeñected path of said beam, elec
trode means in the region of said magnetic iield
to direct electrons in combination with said
ñeld along a helical path toward and upon said
helical path through said iield, cyclically varying
said angle to vary the path and cause the elec
tron beam to emerge from the ñeld at a mul
tiplicity of substantially contiguous points of a
circle having its center in the axis of said ñeld,
and causing the emerged ray to Strike said target.
IRVING WOLFF.
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