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Патент USA US2122555

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July 5','_193_8.
_
E. BR'L'JcHE '
BRAUN TUBE
2,122,555
'
Filed April 27, 1936
INVENTOQB
ERNST BRUCHE
A
R
Patented July 5, 1938
2,122,555
UNEED ?TA'l'ES PATENT OFFIQE
2,122,555
BRAUN TUBE
Ernst Briiche, Berlin-Reinickendorf, Germany,
assignor to Allgemeine Elektricitatz Gesell
schaft, Berlin, Germany, a corporation of Ger
many
Application April 27, 1936, Serial No. 76,632
In Germany April 27, 1935
3 Claims. (Cl. 250-275)
It has been suggested in the prior art to design is surrounded by an electrode 5 in the shape of
the accelerator system in Braun tubes in the an annular disk being kept at cathode potential.
form of an electron-optic immersion objective Both the cylinder 2 as well as cylinder 3 have
comprising two cylindrical electrodes. The ?rst bores through which leads and supporting means
one of these cylinders in this scheme is closely for the pairs of plates 6 and ‘I may be passed.
adjacent the cathode and it may, optionally, ex
tend beyond it, whereas the second cylinder The plates themselves are of but reduced size,
partly surrounds the former and extends beyond and they will thus not impair or disturb the shape
it. The second cylindrical electrode could also be of the potential seeing that the potential will be
nearly constant also at the points where the
10 replaced by an inside lining of the tube.
The potential curve on the axis of such an im
mersion objective is shown graphically in Fig. 1
of the drawing. The abscissa of the diagram
here shown corresponds to the axis of the sys»
tern, while the ordinate indicates the potential U.
Below the diagram is shown at the same time in
schematic form the system itself comprising the
cathode K and the cylinders Zl and Z2 to which
suitable potentials are applied. As can be seen
20 from the diagram, a rise of potential occurs be
tween the cathode K and the cylinder Zl. Along
Z! the shape of the potential curve is rectilinear
and nearly horizontal. Between Zl and Z2 there
happens another rise of potential. The lens
25 action of the system is governed by the electrical
?eld which arises at the said points of transition.
The rectilinear shape of the potential along Zl
(and also Z2) means that the potential surfaces
at the said points are placed perpendicularly (or
30 at right angles) to the axis of the system.
Now, according to this invention, in Braun
tubes equipped with electrode systems of the said
sort, at least the ?rst de?ection plate pair is dis
posed inside the ?rst cylinder (closest to the
DJ 01 cathode) at a point where the shape of the poten
tial is horizontal or practically so.
If the ?rst
cylinder is of su?icient size, it will be feasible to
mount also the second pair of plates inside this
cylinder. However, as a general rule it will be
suitable to place the second pair of plates pos
teriorly of the potential ?eld producing the lens
action.
The accommodation of the pair of plates inside
the cylinder at greatest proximity to the cathode
o?ers the advantage that the de?ection of the
electrons happens at points of low electron ve
locity, and that, moreover, the de?ection sys
plates are mounted.
I claim:
10
1. A cathode ray tube comprising, an envelope,
an electron emitter within the envelope and po
sitioned at one end thereof, a luminescent screen
also within the envelope and positioned at the
end thereof opposite the emitter, a pair of cylin
drical accelerating and focussing electrodes sup
ported within the tube in the region adjacent the
emitter and each longitudinally spaced there
from and telescopically positioned relative to each 20
other so that one cylinder partially surrounds
the other, said electrodes being adapted to have
applied thereto positive potentials relative to the
emitter to develop an electrostatic ?eld to form
the emitted electron stream into a sharply de
?ned spot focussing upon the screen, and a pair 25
of beam de?ecting electrodes positioned internally
of the cylindrical electrode nearest the emitter,
said de?ecting electrodes being located within the
cylindrical electrode in a region of electrical ?eld 30
distribution where the shape of the potential
characteristic is substantially uniform.
2. The tube claimed in claim 1 comprising in
addition a second pair of beam de?ecting elec
trodes positioned within the cylindrical electrode
most remote from the emitter.
3. A cathode ray tube comprising, an envelope,
an electron emitter within the envelope and po
sitioned at one end thereof, a luminescent screen
also within the envelope and positioned at the 40
end thereof opposite the emitter, a pair of cyl
indrical accelerating and focussing electrodes
tems are located as close as possible to the lens
supported within the tube in the region adjacent
the emitter and each longitudinally spaced there
from, said electrodes being adapted to have ap 45
plied thereto positive potentials relative to the
emitter to develop an electrostatic ?eld to form
which, as will be noted, is formed at points where
the ?rst cylinder passes over to the second. The
the emitted electron stream into a sharply de
?ned spot iocussing upon the screen, and a pair
oscillographic tube thus becomes extremely
of beam de?ecting electrodes positioned internal
sensitive.
ly of the cylindrical electrode nearest the emitter,
An exempli?ed embodiment of the tube here said de?ecting electrodes being located within the
disclosed is illustrated in Fig. 2. From the oath
cylindrical electrode in a region of electrical ?eld
55 ode l by the aid of the accelerative system 2, 3, an
distribution where the shape of the potential
electron pattern in the form of a luminous spot characteristic is substantially uniform, and a sec 55
is produced upon the screen 4. The cathode ond pair of beam de?ecting electrodes positioned
preferably is of the hollow type having a small within the cylindricalelectrode most remote from
and sharply bounded exit opening.
the emitter.
"
The cathode l, in order to improve the image,
ERNST BRUCHE.
60
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