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Патент USA US2131192

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SePt- 27, 1933-
K. SCHLESINGER
2,131,192
HIGH VACUUM TELEVISION TUBE
Filed May 4, 1935
2 Sheets-Sheet 1 .
Mia/M.
Sept. 27, 1938.
K. SCHLESINGER
2,131,192
HIGH VACUUM TELEVISION TUBE
Filed May 4, 1955
2 Sheets-Sheet 2
Patented Sept. 27, 1938
2,131,192
UNITED STATES PATENT OFFICE
2,131,192
r
'
HIGH VACUUM TELEVISION TUBE
. Kurt Schlesinger, Berlin, Germany, assignor to
Radioaktiengesellschaft D. S. Loewe, Berlin
Steglitz, Germany
Application May 4, 1935, Serial No, 19,817,
In Germany May a, 1934
5 Claims.
(Cl. 250-215)
ing plate Ill possesses a considerably wider aper
ture, so that the same is not touched by the
directly impinging cathode ray and a local heat
The present invention relates to a Braun tube
for television purposes which is preferably oper
ated in a highly evacuated condition, in which
electro-static ?elds are employed throughout for
ing of the bronze plate is prevented. In this way
5 producing and de?ecting the image point, and in
the danger of subsequent discharge of gas within
which all of the electrodes by means of which
the ?elds are produced aregarranged within the
tube, so that the tube is at once in an operable
condition without further external auxiliary de
10 vices, such as coils and the like.
The tube according to the invention, an embod
iment of which is illustrated by way of example
the tube is eliminated.
in Fig. 1, may, broadly speaking from the point
of view of physics, be divided into three parts:
15
?rst, the beam condensing device (“condenser"
in an optical sense) with control grid and per
forated diaphragm, secondly the reproducing
lens with tubular. member up to the anode, and
thirdly two de?ecting condensers.
20
‘
The indirectly heated cathode consists of a
small nickel hood I, which at its front end, the
diameter of which is 2 mm., is ground completely
?at and is furnished with a small recess 2 of .1
mm. only in‘ depth, which is ?lled up with a
2
highly emissive substance, for example a mixture
of earth alkaline oxides, such as are well known
in the art. In selecting the size of the recess 2
the size of the picture and the number of scan
ning lines are to be taken into consideration;
the exact calculation of the size of the emissive
3 O layer will be set forth below.
The glow hood 2
is heated by means of a preferably slotted spiral
3 arranged in the interior of the hood, which
may be insulated from 2 by a small insulating
tube (not shown) consisting for example of mag
nesia. The complete cathode is located exactly
in axial position within a control cylinder 4 by
the use of a cylindrical ?tting, so that the emis
sive surface is exactly aligned with the tube axis.
40 The cylinder 4, in turn, is ?tted by means of two
stamped collars 5 and 6 onto certain elements
‘
The aperture in the perforated diaphragm 9
onto which the cathode ray is projected with
varying intensity is reproduced by an electron
optical system on the screen, viz, by the electrode 10
system comprising electrodes ll, l2, l3 and It.
The main purpose of tubular member I I (bronze)
consists in screening the cathode ray traversing
the interior thereof against external electrostatic
?elds. ' The length which this member is to be 15
given may be readily calculated from the desired
scale of enlargement of the reproduction with a
given constructional length of the tube (see be
low). The tubular member H is linked up with
a lower positive bias than the main anode l4 and 20
preferably than the diaphragm it) also. The path
of the cathode ray does not undergo any electron
optical refraction within the tubular member,
since in accordance with the invention the diam
eter of the tubular member is selected to be large
as compared with the diaphragm aperture 9. It 25
is true that the applicant has been able to ascer
tain de?nitely that a wide tubular member of this
kind which is biased negatively in relation to the
rays is ineffective in practice only as regards rays
in the vicinity of the axis, i. e., the main bundle 30
of rays, whilst as regards such marginal ray as
stray to an‘ appreciable extent it effects an
auxiliary concentration which is very helpful for
a satisfactory operation of the tube. It is pos 35
sible, for example, to completely suppress by a
bias of this kind of the tubular member in rela
tion to the diaphragm the known halation eifects,
which otherwise will appear on the luminous
screen.
the whole of the tube system in itself, and car
By means of an intermediate diaphragm with
large aperture l2 and a short tubular extension
l3 in coniunction'with the double anode l4 situ
ries at a small distance from its upper end a dia
. ated in front of the tubular member the cathode
for example glass rods—provided for centering
45 phragm 1 having a narrow aperture, which dia
phragm is disposed in close neighbourhood of
the glow head I, for example at a distance of
within .5 mm. therefrom. The cylinder extends
beyond the grid diaphragm ‘I by a definite amount
8 (see below).
'
The cathode ray proceeding from 2 and con
trolled in its intensity by ‘I is preliminarily con
centrated by 8 and impinges on a narrow dia
phragm aperture 9 of approximately the same
size as the emissive surface 2. The diaphragm
plate carrying the aperture 9 consists of a com
pletely outgassed metal having a high fusing
point, for example molybdenum, which prefer
ably is welded on to a bronze supporting plate
60 Hi to form the diaphragm proper. The support
40
ray refraction proper is produced. The peculiar 45
form of the electrodes is the result of systematic
investigations of electron-optical lenses. The
problem which has been solved in this respect
consisted in the ?rst place in producing by elec
trical design and adjustment the effect of a 50
spherically corrected lens having for the margi
nal rays the same focal distance as for the cen
tral rays. Secondly no refraction should be ex—
erted on the electrons after leaving the main
anode l4, and thirdly it should be possible to 55
provide de?ecting plates behind the anode with
out the symmetry of rotation of the lens being
lost. (“Behind” means: more remote from the
cathode than.)
The lens l2, l3, I4 as shown satis?es these re
60
2
2,181,192
quirements as ‘soon as the correct difference in
potential has been adjusted between I! and i4,
potential ‘of opposite phase the plate leakage re
sistance 32 (not exceeding 100,000 ohms) is con
it being maintained. positive. in relation ‘to, II,‘
This adjustment, which determines the degree. oi,
electron optical refraction, is performed by means
nected; with the second control, grid 221~oi the
upper r'system‘of the twin‘. amplifier tube 20, the
of a potentiometer I 6 which is connected with the‘
tapping 32', exactly to the extent‘to which the
relaxation potential being reduced by means of a 6
terminal l5, and is connected between theearth 3 same has been/ampli?ed in the lower half of the
potential, which is simultaneously linked up with ‘ ,tube ‘24, 25 (ampli?cation factor‘l/D). There is
the diaphragm l0 and the anode ‘I4, and the po
accordingly obtainedat the working resistance 33
10 tential oi the cathode. The refractive iield is
‘i of; thesec‘ond; anode 22 the desired reverse relaxa
ited to the lens space (i. e., the space between the ‘ tion potential havingthe same amplitude but re
electrodes producing the lens) by virtue oi‘ the
10
verse phase. This reverse potential is conducted
to the second de?ecting plate It of the television
v‘tube through the medium of a second coupling
screened construction of the lens electrodes both
, towards the front as well as towards the rear. The
apertures may preferably be made not larger than condenser; this de?ecting plate being also earthed .
it
the largest cross-section of the electron bundle. through a leakage resistance 34 larger than 32.
The spherical correction of the lens ‘is obtained 1
By means‘ofl a similar‘relaxation arrangement
only ‘upon introduction of the'rear‘ intermediate likewise ‘comprising a countercadence ampli?er
diaphragm i2 into the tubular‘ member.“ lithe‘ ‘1 the ‘front pair of de?ecting plates l8, i9‘ is also
in reverse phase. It mustbe particu-., 20
as large as'the tubular extension it, the potential operated
larly emphasized that without such‘. reverse phase
levels have substantially the form of an inscribed circuit“ the problem does not appear capable of
spherical surface,‘and the lens acts as a‘ spheri
solution.“ The errorswhich‘ then occur, 1. e., in
cally corrected one, which is not true‘ii’ the inter
20 width of this diaphragm i2 is made approximatelyj .
'
the‘ case oi’ the usual single phase operation ‘are
lack of sharpness at‘the, edge by variation 01' the
focal distance, and a trapezoidal shape of the pic
mediate diaphragm l2 is omitted. It“ may be
added that the diaphragm l2 acts at ‘the same
‘25
time as a selection pupil by which those marginal ‘ ture‘.‘ These errors inthe image are‘ all avoided
rays are stopped‘which diverge‘too strongly.
byfreve‘rse phase operation of‘ the two de?ecting
The third requirement, viz, the? independency.‘ plates.‘
‘It is true that j‘the ‘mutual approach of
oi" the symmetry of the lens ?eld from the“?e1d‘s the ‘pairs
of plates, towards. ‘each other and the 80
of the de?ectingplates arranged behind the‘ anode anode should
not be driven farther than to within
I4, is obtained by-increasing the axial length of , two to three times the width oi‘mouth (distance
30
the anode to a certain extent by a small tube i5.
between, the rear edges, directed towards the
this manner the penetration of the ‘ileljizpf the
35 In‘
plates arranged behind the anode ll into ‘ e‘lens
cathode, of the plates of a pair of‘ de?ecting »
plates).
-
>
3]
‘
?eld is greatly reduced,‘ and it is‘ in fact accom- “
Improvements in "the‘operation at the plates.
plished that the stationary
image point, iwhichis
produced by the use oi’ a circular diaphragm 9, is may be obtained by giving them a suitable shape.
an undisturbed round point.
40
,
g,
‘i
v
‘ It is convenient‘ to disposethem in‘a tilted posi- , ~
.,
tion in relation to each other, asa certain gain
in their speci?c‘ sensitivity ‘(deflection in mm. per‘ 40
.
The de?ection of the cathode rays takes place
by means of two ‘plates i6,‘ i‘! in the horizontal‘
direction, and ‘l8. IS in the vertical direction.’ The
volt) is thereby obtained. Beyond this the sen
sitivity
‘of the de?ection is, ‘with the use of a re
de?ection is‘ unavoidably associated with simul,-, verse’ phase
circuit, twice as great as with a. usual
45
taneous 1 disturbances in the sharpness oi’ ‘the
circuit, 1, e., the anode battery potential 35,,may
image point at the edge ofthe image it, as hereto
fore usual, the one plate being connected with the
be halt as‘great as‘ usually, which is of particular
advantagein the case of short-ray high-vacuum
tubes in which the; de?ecting plates require to be
de?ecting voltage generator, the other plate is
earthed.
‘
,
'
.
.
,_
approached as near as possible towards the screen.
In accordance with the invention. it is possible
It has been found ‘that to avoid interfering dis
50 to overcome this ‘di?iculty, which heretofore has
placement of ‘the ray owing to wall charges a sil
prevented the construction of tubes operating
with purely electrostatic means, by, operating the
two plates in reverse phase with ‘respect to each
other. For this purpose there is, provided a special
relaxation oscillation apparatus, which consists,‘
for example as shown, of the twin‘ ampli?er tube
circuit including a twin tube 20.‘ Two independe .
'
anode I 4 or diaphragm III.;, The applicant has as- ,
‘ certained, ‘however, that this'silver‘coating‘ ‘re- ‘
quires to‘ ‘cover merely a part ‘of the bulb, viz, it '56
‘requires, to extend only irom‘the anode it up to‘
the ‘front ‘plates i8, i9, which already project into
interior'oi’ the bulb. Equally asimportant as
ranged about a common cathode. , Simple single‘ the
this screening is an outermagnetic screening oi’
ent grid-anode systems 22, 23 and“, 28 are ar
60
60
ver coating‘ 36 should be provided, which may
preferably be connected with earth,i. e., with the
grid systems with a reciprocalnoi ‘approximately
.
the tube by means 01’ an iron shield 31, which
2% incombination with a;mica disc screening . needs only to consist of ,a sheet of approximately
means 26, are fully su?icient. “ The one oi’ the two’ ‘
systems, for example, the lower one, is connected
1 mm. thickness having a good ‘magnetical con
directly with the relaxation condenser ‘20, which , ductivity, which, however, must be closed in annu-,
lar form (welded or drawn) ,and need merely ex
65 is charged through
the medium 01'. the resistance tend
from the hot cathode to the‘ anode.
.
21, and discharged‘ through the medium of a gas? .
The
shield
is
preferably,
likewise
connected
with
, ?lled grid-controlleddischarge device 29,01 that i earth. It isonly with the provision‘ of this shield
general type. a well known representative of which.
is the tube called "'I‘hyratron” (registered trade-H , that‘ it is ‘possible to operate the tube in any de
70 mark). The anode 25 of the‘ system here in ques sired position in irelationgytfo the magnetic earth
tion is connected with a working resistance 20 of
approximately 100,000‘ohms, and with the one ‘dc
?eeting plate I1 01' the television‘tube‘through the
‘ ?eld,‘ so thatparticular potentiometers for adjust
ing the position‘ of the centre oithe image are
unnecessary.
‘
or
70
‘
lack of‘sensitivenessagainst ?eld disturb
medium of a coupling condenser 3| . In order now . .
75 to obtain for the other de?ecting plate It an equal ances is favoured bythe extensive preliminary ‘
acceleration of the ray which iseil‘ected accord- 7
e
3
2,131,192
ing to the invention by the high positive potential
of the diaphragm 9.
Form of aperture is reproduced sharply; there
fore also square or hexagonal apertures may be
The light intensity and function of the whole
tube is essentially determined by the path of the
used.
'
rays between cathode and diaphragm. The rays
Current utilizationggg: m} gigg??gg :%
should be suitably in?uenced in this particular
Length of tubular member II approxi
region, 1. e., in such manner that as far as pos
sible all electrons in the ?rst place are passed
through the narrow aperture, and secondly con
Diameter of aperture of lens ll, l2____mm__
7
Tubular member extension 13 _______ __mm__
7
mately____ __
10 tinue to move in such a narrow cone that no stop
ping-of electrons occurs later neither in the lens
nor in the diaphragm and that all electrons reach
the screen in one de?nite image point. The bet
ter the form of the bundle obtained, the more
15 sensitive the de?ection may be made, as a. bundle
having a small cross section in the plate ?eld
practically is not subject to disturbances even in
__
mm
100
20 10
Diameter of tubular member ________ __mm__
Spacing between edge of tubular member and
anode __________________________ __mm__
7
Diameter of anode tube I5 __________ __mm__
Length of anode tube l5"; _________ __mm__
7
7
de?ecting plate _________________ __mm__
system ______________________ __mm__6 and 15
Length of rear de?ecting plates ____ __mm__ 35
having a large cross section in the region in ques
20 tion undergoes lateral distortions in such systems.
The applicant has found that the simple con
Width of mouth of front de?ecting plates
densing lens ‘I, 8, III as shown, which exactly cor
responds in its operation with the ‘main lens l2,
l3, I4, is capable of ful?lling the stated require
25 ments, but merely under the condition that the
free length of the ray between cathode and dia
phragm is not too small. The applicant has
Distance between rear plates system and
least 10 mm. This spacing is calculated in prac
30 tice by use of the simple diopter law on the basis
of the required width of bundle. One may in fact
obtain a survey on the conditions of ray propaga
tion as in?uenced by the condensing lens by draw
ing the most unfavourable rays from
edge of
35 the cathode spot over the edge of the di phragm
aperture. These rays must then undergo such a,
refraction in the condensing lenses as to pass
through the image producing lens and through the
space between the de?ecting plates.
40
With a large spacing 'I/ III as stated above and
the cylinder extension 8 necessary for spherically
correcting the condensing lens, which extension
?lls out approximately one-half of the spacing. it
is clear that the anode ?eldattracting the elec
trons is rather weakened. If only for this reason
alone the separate and ‘sumciently strong posi
tive bias of the diaphragm I0 is essential if it is
desired to obtain bright images. In particular
cases it may be necessary to provide a screening
50 grid diaphragm 38 together with a particular in
termediate cylinder 39, in order to be able to make
the requirement for suitably guiding of the ray
unobstructedly consistent with the requirement
for su?‘icient anodic strength of ?eld as is neces
55 sary for producing cathode rays of great intensity.
In the following it will be set forth in what
manner a tube according to the invention may be
dimensioned in practice.
Cathode spot ___________ -..-'- _________ __mm__
.4
Maximum total emlssionn' __________ __mA__
.8
Diameter of aperture in grid diaphragm
‘I _______________________________ __mm__. 2
Diameter of the front surface of cath
ode _____________________________ __mm__ 1.8
Spacing between grid and front surface of .
cathode _________________________ __mm__
.5
Cylinder extension 8 _______________ __mm__ 3
Diameter of aperture in diaphragm III for
75
line picture size 17x20 ____________ __mm__
20
screen __________________________ __mm__ 250
25
Anode potential _________________ __volts__ 2,000
Maximum power required _________ __watt__
1
Heating 4 volts, A. C. or D. C ______ __amp__ .4
Potential of tubular member, volts variable,
approx ______________________________ __
1,500
30
Sensitivity of de?ection per volt, approx- _mm__ .5
Voltage of supply battery of relaxation oscil
lation generator 35 ______________ __volts__ 8004
It is to be understood that the above data only
refer to a particular form of embodiment of the
tube according to the invention, to which the in
vention is in no way limited.
The individual parts of the system may be
mounted on the base of the tube and centered
in relation to each other preferably by the use of
insulating supporting means, which may prefer
ably consist of glass. The individual current
leads are preferably all taken to a socket secured
to the base of the tube. The current supply to
the metallic coating 36 is preferably e?ected so as
to avoid special fusing-in points by means of
springs ?xed to the electrode system and con
ductively connected for example with the anode.
These springs may at the same time serve for 50
supporting or guiding the system within the neck
of the tube. For this purpose they may be con
structed for example in the form of compara
tively strong, bent blade springs.
A practical and convenient technical form of 55
embodiment of the tube according to the inven
tion is illustrated by way of example in Fig. 2,
like references being given to like parts in the
two ?gures.
60
I claim:
1. A Braun tube more particularly for television
purposes comprising means including a cathode
disposed near one end of the tube for producing
a cathode ray, an image screen disposed at the
end of the tube opposite to that end near which 65
said cathode is disposed, and an electron-optical
lens system for projecting the cathode ray onto
said image screen in the form of a sharply de
tem comprising a tubular member having its axis 70
disposed in the direction from said cathode to
said screen and having a diameter which is con
phragm l0 _______________________ __mm__ 7
ISO-line picture size 14x18 _______ __mm__
front plates system __________ _-_____mm__
Spacing between anode I5 and luminous
?ned image point, said electron-optical lens sys
70 Spacing between edge of cylinder and dia-'
Diameter of aperture in diaphragm for 180
20
system ______________ __'_ ____ __mm__ 6 and 20
' found that the spacing ‘l/lll must amount to at
55
10
Width of mouth of rear de?ecting plates
highly sensitivev plate systems, whilst a bundle
60
15
Space between anode l5 and edge of rear
,
siderably larger than the diameter which the
cathode ray possesses when travelling through
.5’ said tubular member, an apertured disc shaped 75
.4
4
2,181,199
anode mounted perpendicularly tothe axis of
.
‘r
member facing said anode,
anode being
said tubular member, near said tubular member adapted to be supplied with a said
high positive po
between said tubular member and said image tential in relation to said cathode,
tubular
screen, and an apertured diaphragm separating member being adapted to besuppliedsaid
with a po
said tubular member into two parts and being tentiallpositiveiin relationv to ‘said cathode but
5
mounted near that
l
r
‘
‘
edge
of saidtubularv member.
negative in relation to said anode.:
facing said anode, said anode being adapted, to
4. A Braun tube more ‘particularly for‘televi
be‘ supplied with a-high positive potential in re
sion purposes comprising means including a cath
lation to said cathode, said tubular member being ode disposed near one endjof the tube for pro
10 adapted to be‘supplicd with a‘noientiai pqsitive ,ducing a cathode ray,
an image screen disposed 10
in relation to said cathode but negative in rela
atthe
end
of
the
tube‘opposite
to that end near
tion to said anode.
t
‘ l
‘
p
,
which‘said cathode is disposed, and an electron
2. A Braun tube more particularly for televi
optical lens system for projecting the cathode’ ray
sion purposes‘ comprising ‘means including a onto said image screen in. theform of ‘a sharply
15 cathode disposed .near one end of. the tube for defined image point, ‘ said electronvoptical ‘ lens
producing ‘a cathode ray, an image screen dis? system comprising a ‘tubular’ member, having itsv 16
posed at the end of the-tube opposite to that end
near which said cathode is disposed, and an
axis disposed in the direction from said cathode
to said screen and having a‘ diameter which is,
electron-optical lens system fortmf?iécting the considerably larger thanthe diameter which the
cathode my: onto said image screen‘ in the form
of a sharply de?ned image point, said electron
optical lens system comprising a tubular member
having its axis disposed’in the direction‘ from said
cathode to said screen and having a diameter
, which is considerably larger‘than the diameter
which the cathode ray possesses when travel
ling through said tubular member, an anode
mounted near said tubular member between said
tubular member and said image screen, said anode
comprising at its side facing said tubularmem
cathode‘ ray possesses when travelling ‘through 20
said tubular member, an ‘apertured disc-shaped,
anode mounted ‘perpendicularly to the axis of.
said tubular member near saidtubular member
‘between said tubular memberandsaid‘jmage
screen,‘ and an apertured diaphragm separating”25
said tubular member intoltwo parts‘ and being‘
mounted near that edge of said tubular member ‘
facing said, anode, both said anode and said
apertured diaphragm having apertures the cross,
her an apertured plate shaped portion disposed
sections of ‘which are substantially equal to the 30
perpendicularly to the axis of said,‘ tubular
member, said anode having a tube-like exten
respective planes of said apertures, said anode
being adapted‘to be. supplied with a high‘ posi
sion in the direction away from said tubular
member. and an apertured diaphragm‘ separat
ing said tubular member into two parts and being
mounted near that edge‘of said tubular‘member
facing said anode, said anode beingY‘adapted to
be supplied with a high positive potential in re
lation to said cathode. said tubular‘member‘bee
ing adapted to be supplied with apotential ‘posi
tive in relationto said cathode ‘but“negative in
relation to said anode.
‘
_‘
‘
‘
l
3. A Braun tube more particularly for televi
cross-sectionswhich the cathode ray has in-the;
tive potentiaiin relation to said cathode, said“
tubular member be
adapted to be supplied
with a potential ‘ positive in relation to said cath
ode but negative in relation tosaid anode._
‘5. A Braun tube more particularly for televi-l‘
sion purposes comprising means including‘ a oath-1 ‘
ode disposed near one end of J the tube for, pro
ducing a cathode ray, an image screen disposed 401
at the end of the tube opposite to' that end near ‘
which said cathode is disposed,and an electron-l
optical “ lens system for projecting'the cathode
sion purposes‘comprising means for producing a‘ - ray onto said image“, screen in the form of a
cathode ‘ray, means to ‘produce di?erent electric
?elds for in?uencing the cathode ray in different
axially consecutive zones of the tube; an image
screen disposed at one end of the tube to be hit?
by the cathode ray after the cathode‘ray has
passed through the mentioned’axially consecu—
sharply de?ned image, point, said electron-op;
this! lens system comprising; a tubular member
having its axis disposed in the direction from said
cathode to said screen and having ‘a diameter
which ‘is considerably largerthan the diameter
which the cathode ray pos‘sesseswhen traveling to
through said tubular member, an‘a‘pertured disc
shaped “anode mounted‘ perpendicularlyv to the
tive zones, an electrode system located in a space
of the Braun tube, both at the sides ‘of which
space facing said screen and facing away from , axis of said tubular ‘member near said tubular
55 said screen at least one of said ?elds isi‘located, member between said tubular member and‘said
said electrode ‘system comprising electrodes
adapted to produce an electron-optically ‘refrac
tive ?eld, and to at the same time screen. this
refractive held against the ?elds at the side of
60 said electrode system facing said screen as well
as at the‘side of said electrode system facing
away from said screen, said electrode system
65
image screen, and an apertured diaphragm sepa
rating‘ said tubular member into two parts and
beingzmounted near that edge of said tubular;
member facing said anode, both said anode and
‘ said apertured diaphragm having ‘apertures the‘
,cross-sections‘of which are, substantially equal
to the cross-sections which‘ the‘ ‘cathode ray has
comprising ‘a tubular member having its axis di
‘ in the respective planes of ‘ said apertures, the
rected towards said screen and having a diameter
distance of said apertured diaphragm. from the
edge of said tubular member facing said anode
which is considerably larger than the diameter
which the cathode ray possesses when travelling
through said tubular member, an apertured disc
shaped anode mounted perpendicularly to‘the
being approximately equal‘to the diameter of the‘ 65
aperture in said apertured diaphragm,‘ said anode ‘
being adapted to be supplied with a high posi
axis of said tubular member near said‘ tubular“ ' tive potential ‘in relation‘ to said‘ cathode, said
70 member between said tubular memberand said tubularmember being adapted to‘be supplied‘
image screen, and an apertured diaphragm sepa
with a potential positive in relation to saidcath 70
rating said‘ tubular member into two parts ,and ‘ ode but negativein relation to said anode. , ,
,
being mounted near that edge of said tubular
KURT SCHLESINGER.
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