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Патент USA US2130020

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sept. 13, 1938.
H. B, MCEUEN
2,130,020 _
' cATHoDE FILAMEÑT coNiï‘BoLFoR X-RAY TUBES
Filed March 13, 1934
'2 sheets-sheet 1
gmc/whoa',
Sept. 13, 1938.
-
l
H. B. MCEUEN
' 2,130,020
CATHODE FILAMENT CONTROL FOR X-RAY TÚBES
Filed Maron 13, 1954
2 sheetsàsheet 2
Patented Sept. 13, 1938
" -
UNlTED STATES PATENT OFFICE
2,130,020
CATHODE FILAMENT CONTROL FOR X-RAY
TUBES
Harry B. Mannen, Jacksonville, F1a.
Application March 13, 1934, Serial No. 715,340
s claims.
(o1. 25o-_35)
This invention is directed to an improvement
in X-ray apparatus, and particularly to the cathode thereof to provide for focusing and concentration of the cathode-filament stream relative to
5‘ the anode.
It is well understood that the input energy is
limited by the heat of the anode in the predeter-
mined focal area, and that provision has been
heretofore made for permissible increase of such
10j energy by mechanical cooling of the anode. While
such cooling is of material benefit in the desired
direction, it obviously does not and cannot permit the me of the ultimate amount of energy permissible for a given focal area of the anode.
I5 If, in addition to a proper cooling of the anode,
the cathode stream is focused for focal area and
at the same time distributed equally over such
area, to avoid undue heat at any one part of
such focal area, the input energy may be in2o- creased toward the permissible maximum without
liability of objectionable heat effects on the anode.
The primary object of the present invention is,
therefore, the >provision of means whereby the
Serial Number 702,989, and while such construc
tion is preferable, 'or at least desirable, it is to
be understood that the details hereinafter de
scribed are applicable to any construction of tube
or of cathode stem.
5"
’ To facilitate an understanding of the present
invention, the X-ray tube may be briefly stated
toinclude atube or casing I,in whichisarrangeda
cathode stem and assembly 2, and an anode stem
3. The tube proper vis made in sections, assembled 10~
in a manner to permit the interior of the tube
to be subjected to the necessary vacuum, and the
cathode stem, with which the present invention
is more particularly concerned, is formed adjaf
cent the filament or anode end with an insulat- l5
ing and seal-off section 4, preferably of glass, as
in Fig. 1.
In connection with the details of the present
invention, the cathode assembly includes a cath
ode stream distributing cup 5, having a wall 6, 20
of any desired or appropriate outline, such wall
being shown as of square outline in Fig. 2. This
wall is arranged substantially parallel to the
cathode stream may be controlled mechanically
25 and selectively for focusing and concentration or
distribution.
axis of the stem, and is connected to a rear Wall
l, substantially at right angles to the stem axis. 25
The rear wall "l is provided with a rearwardly
A further object is the provision of the adjusting means for control and operation at any
time without in any way affecting or interfering
3o, with the vacuum condition of the tube.
A further object is the provision of adjusting
means arranged wholly within the tube and normally locked against operation, together with
magnetic means arranged wholly outside of the
35 tube and selectively operable to withdraw the
lock of and operate the adjusting means.
extending sleeve B, which slidably fits on and
is guided by a conforming extension 9 project
ing forwardly from the insulating and seal-off
section 4. The distributing cup is thus mounted 3o
for sliding movement longitudinally of the stem,
'
and while the type of mounting described is de
sirable, it will be ,understood that any conven
tional or preferred Slidingly-gllided and Support
ing mounting may be used.
35
Arranged within the cup 5 is a cathode com
The invention is illustrated in the accompanying drawings, in which:-_Fig. l is a broken longitudinal section of the
40 cathode tube, illustrating particularly the adjusting means for the ñlaments.
prising a series of filament cups I0, one for each
filament. The ñlament cups are formed by par
Fig. 2 is a face View of the cathode.
Y
allel flat sections II, spaced apart and connected
at their rear ends, as at I2, all as shown in Figs. 40
2 and 3. These cups are connected to high po
l tential bar I‘I„but are not connected electrically
Fig. 3 is a section on the line 3--3 of Fig. 2.
Fig. 4 is a longitudinal section of the cathode
‘ 45.y stem.
Fig. 5 is a broken elevation showing a modiñcation.
to either of the filament bars I8 or I9, but sup
port these bars on insulators and carry Vthem
forward and backward with adjustment of the 45
filament cups. The auxiliary cup-s are movable
as a unit within the main cup and are sup
Fig. 6 is a diagrammatic view showing the relation of the improved cathode and the anode to
50 illustrate the control of the cathode stream.
ported forv such movement and to avoid undue
friction by rollers or like elements I3, arranged
between the distributing and auxiliary cups.
50
Fig. A7 is a detail View showing adjustment
ñnder.
.
The X-ray tube illustrated is of the general
construction described and claimed in my co-
55,v pending application filed December 18, 1933,
IThe filament cups have a rearwardly-extending
bar-like member I4, which passes through the
rear wall 'I of themain cup and is ñxed at `its
rear end in an insulating disk I5, slidable in an
insulating sleeve I6, »connected to the sleeve 8 55
2
2,130,020
of the main cup. A high potential rod extends
transversely of and across all auxiliary cups ID,
being arranged near the rear of such cups.
shaft 34, supported in bearings from the exten
Similar filament rods I3 and I9 are carried by
sion 9 of the seal-ofi' section 4.
the ñlament cups near the upper and lower ends
made in sections has an insulating connection
thereof, the rods I8 and I9 being directly sup
ported in insulators I8' carried by the cups. 'I'he
high potential lead 20 leads from the rear end
of the stem to and through the seal-off section
10 4, thence through and fixed in disk I5, then
through and fixed in bar I4, and is electrically
connected to the high potential rod I1. The
distributing cup is also provided with a rack 33,
with which cooperates a pinion 33', carried on a
This shaft, if
at 35', and the shaft may, and preferably is,
provided with locking means similar to that de
scribed in connection with shaft 26, though such
is not illustrated.
'I'he shafts 26 and 34 terminate at their lower 10
ends in a bar or disk 36 of magnetizable material.
Arranged for cooperation with the disks 36 are
filament leads 2I and 22 extend in parallel rela
operators, including rotatable shafts 38, having
tion to the high potential lead, being secured in
an operating handle 39 at the lower end.
15 the disk I5, and are connected to the rods I8
and I9. In the preferred form all leads are
fixed or embedded in the seal-olf section 4. in
The
upper end of each shaft is provided with a mag
will, if appropriately positioned and operated,
the disk I5, .and preferably pass through insu
compel movement of either shaft 26 or 34, as
lating bars I5', to prevent possible short circuit
selected, and thus compel the desired adjustment
20 between the leads.
The leads throughout an ap
propriate portion of their lengths are, in the
preferred form, of sinuous or convolute form, as
at 20’ in Fig. 1, to permit longitudinal adjust
ment of such leads without interfering with cur
25 rent flow. It will be noted that just beyond the
sinuous formation toward the filament cups, all
leads .are fixed or embedded in the insulator disk
I5, and that after passing through this disk the
high potential lead 20 terminates at rod I1, While
30 the filament leads 2I and 22 terminate at rods
I8 and I9, respectively.
The rods I1, I8, and I9 carry the ñlaments 23,
there being one such filament in each filament
cup, as shown in Fig. 2. The axial length of the
35 wall 6 of the distributing cup is greater than the
similar dimension of the ñlament cups, and it
will be obvious that the spread of the cathode
stream may be varied by the axial relation of
the distributing and filament cups. Obviously,v
40 also, the adjustment of the filament cups relative
to the anode will serve a focusing function. If,
of the parts described. The magnets are pref 20
erably mounted for appropriate cooperation with
the selected disk 36, and are designed to be
turned out of inliuencing relation on the disks.
The manually-operable rods for turning the mag
nets are of course to be of properly insulating
construction,y in order to protect the operator
against shock during operation. Each disk is
appropriately marked with edge markings at 36',
which cooperate with a mark 31' on the tube I,
to permit successive adjustments of identical 30
range, or initial adjustment according to prede
termined requisites. The mark 31' for the disk
36 on the shaft 26 is of sufficient length to coop
erate with the markings of that disk in any posi
tion assumed incident to the adjustment of the 35
main cup 5.
'
'
When it is desired to adjust the filament cups
for focusing the cathode stream on the anode, the
be selectively controlled, the focusing and also
operator will move the magnet 40, or the appro
priate magnet if more than one is used, into
magnetizable influence on the disk 36 of the shaft
26. The initial effect is to move the shaft longi
tudinally and thus release the lock. The mag
netic iniiuence then fixes the shaft and operating
45 the spread or concentration of the cathode stream
shaft, and Vby turning the latter the filament cups
therefore, means are provided by which move
ment of the distributing and filament cups can
can be governed.
It must be remembered, how
ever, that the cath-ode stream is in a vacuum,
which must not be disturbed, and also, to be
commercially effective, the selective adjustments
50 must be available at all times. This provision
forms one of the essential features of the present
invention.
To provide for the selective adjustment of the
filament cups for focusing, the bar member I4 is
55 formed with rack-teeth 24, and supported in
bearings 25, carried by the main cup 5, is a
shaft 26, on which is fixed a pinion 21 for cooper
ation with such rack. The shaft is either of insu
lating material, or is made in sections, connected
60 by an insulating sleeve. The lower end of the
shaft terminates adjacent the wall of the tube I.
It is desirable that means be provided for lock
ing the shaft against rotation when not in use,
for which purpose the lower bearing 25 is formed
65 on its lower surface with teeth 29, and the shaft
below the bearing is provided With a disk 3D
having similar teeth. 'I'he shaft is mounted for
limited vertical movement, and on the side above
the bearing is provided with a fixed collar 3I,
70 between which and the bearing is a spring 32.
The shaft, when free of other inñuence, will
be moved by the spring 32 to interiit with the
teeth on the disk and the teeth 29, thus holding
75
the shaft against rotation.
The sleeve 8 or equivalent projection from the
15
net 40, either permanent or electromagnet, which
may be moved in either direction. A similar op
eration in connection with shaft 34 will adjust
the main cup.
The rack and pinion connection between the
shafts 26 and 34 and the controlled parts, is
intended to be a conventional illustration of any
and all appropriate means for accomplishing this
result, it being understood that the purpose is
to provide a minute and easily controlled cooper
ation, and any means to this end is contemplated. 55
Furthermore, the locking means may be in any
conventional or desired form, so long as it is
automatically serviceable when the operation is
not desired and releasable when initiating such
operation.
60
If desired the glass insulating and seal-olf sec
tion 4 of the cathode stem may be provided with
embedded metallic sleeves 4I, and the leads, fila
ment and high potential, divided to permit ad
justment, as indicated in Fig. 5. These leads, in 65
dicated in Fig. 5, at 42, 43, and 44, may thus be of
usual wire construction, and to insure electrical
continuity at all times, each sleeve 4I is addition
ally connected to the movable portion of the lead
thereinV by a spring conductive strip 45.
70
'I‘he general construction of the cathode as
sembly will be to avoid any sharp edges, except
possibly in or on the anode-facing edges of the
filament cups, Where it may be found that nee
dle-like, short points will be formed to point
2,130,020
directly toward the anode and project but a very
slight distance beyond the main surface of the
cup edges. This detail of the filament cups is an
optional construction of the present invention,
but if used it will help electron emission at the
higher voltages and yet be controllable in being
directed at the focal area on the anode by the
focusing cups. In providing a construction to
avoid coronal discharge, it being understood that
10 at the higher voltages electron emission will
take place from all rough, sharp surfaces, the
edge of wall 6 of the distributing cup 5 will be
rounded, and a skirt portion 46 will be extended
rearwardly in line with such wall 6 for the full
15 length of the sleeve 8. This skirt will of course
be formed with slots to provide for shafts 26
and 34, this skirt providing an electrostatic shield
covering all sharp points and edges otherwise
and necessarily present. A11 exterior surfaces,
20 particularly of the shield will be highly polished
and rounded to prevent electron emission from
undesired portionsof the cathode.
With the construction described it is apparent
that any predetermined or required adjustment
25 of the filament cups or of the distributing cup,
or both, may be readily and easily secured at
any time, without loss of vacuum or disconnecting
any of the parts, and also while the X-ray tube is
in actual use. The capability of adjustment pro
30 vides for a very fine focus or a large focal area
on the anode. By the use of the scaled disk and
3
Having thus described the invention, what is
claimed as new is:
1. In a device of the character described, a
casing sealed from the surrounding atmosphere,
an anode in said casing, a cathode distributing
cup mounted within said casing for longitudinal
movement with respect thereto toward and from
said anode, means within said casing for mov
ing said cup longitudinally thereof toward and
from said anode to selected positions with re
spect thereto, said means including amagnet
izable member positioned adjacent the inner wall
of said casing, a cathode carried by and within
said cup, whereby said cup controls the distribu
tion of the cathode stream, and means wholly eX
ternal of said casing including a magnet located
adjacent the outer wall thereof in alignment with
said member for actuating said first named
means, whereby said cathode is simultaneously
moved to said selected positions with said cup. 20
2. In a device of the character described, a cas
ing sealed from the surrounding atmosphere, an
anode in said casing, a cathode mounted within
said casing for longitudinal movement with re
spect thereto toward and from said anode, means 25
within said casing for moving said cathode to
ward and from said anode to selected positions
with respect thereto, said means including a
magnetizable member positioned adjacent the
inner wall of said casing, and means wholly eX 30
ternal of said casing including a magnet located
fixed line, any previous adjustment can be sub _adjacent the outer wall thereof in alignment
sequently obtained without difñculty. Thus one with said member for actuating said first named
tube can be used for the lowest, highest, or any
35 intermediate milliamperage, with selected points
of adjustment for a predetermined energy.
Through ,the described control the cathode
stream is evenly distributed homogeneously over
the face of the anode throughout the selected
40 focal area, thus avoiding any centralization of
the heat.
The invention, while described in connection
with a cathode of an X-ray apparatus with mul
tiple filaments, is equally applicable to other
45 vacuum tubes, as for example, rectifier tubes and
the like, and is also equally effective with one or
any number of filaments.
The essential results of the construction de
scribed is the ability for adjusting in a tube yof
50 this character the size of the focal area on the
anode and the distribution of the cathode stream
relative to the selected focal area. Thus no small
area is forced to carry practically all the wattage
employed, but a more or less even distribution of
55 the heat is secured over the selected focal area,
and the more perfect this distribution the more
possible the use of the ultimate amount of energy
allowable for a given focal area on the anode.
While the cathode proper is shown as com
60 prising the filament cups with their filaments, it
is obvious that the invention may be practiced
with the use o-f other- types of cathodes. However,
the construction of the cathode disclosed herein
65
is preferred, and results in outstanding advan
tages.
means.
3. In a device of the character described, a 35
casing sealed from the surrounding atmosphere,
an anode in said casing, a cathode distributing
cup mounted within said casing for longitudinal
movement with respect thereto toward and from
said anode, means within said casing for moving 40
said cup longitudinally thereof toward and from
said anode to selected positions with respect
thereto, said means including a magnetizable
member positioned adjacent the inner wall of said
casing, actuating means wholly external of said 4.5
casing and operable therethrough for actuating
said ñrst named means, said actuating means
including a magnet located adjacent the- outer
wall thereof in alignment with said member for
actuating said first named means, a cathode 50
mounted within said cup for movement inde
pendently thereof toward and from said anode,
means within said casing for moving said cathode
independently of said cup toward and from said
anode to selected positions with respect thereto, 55
said last named means including a second mag
netizable member positioned adjacent the inner
wall of said casing, and actuating means for said
last named means located wholly externally of
said casing and operable therethrough, said last
named means including a magnet located adja
cent the outer wall thereof in alignment with said
second named member.
HARRY B. MCEUEN.
65
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