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Патент USA US2404905

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July 30, ‘1946.
2,404,905
H. D. GARRETSON
ELECTRICAL CIRCUIT ARRANGEMENT
Filed Jan. 31,‘ 1944
s
1726,». 1.
~
114/;
Patented July 30, 1946
2,404,905
UNITED STATES PATENT OFFICE
2,404,905
ELECTRICAL CIRCUIT ARRANGEMENT
Harry Douglas Garretson, Whitestone, N. Y.,
assignor to North American Philips Company,
Inc., Dobbs Ferry, N. Y.
Application January 31, 1944, Serial No. 520,524
3 Claims. (Cl. 250—103)
1
2
My invention relates to electrical circuit ar
My invention will be described in greater de
tail with reference to the appended drawing
forming part of the speci?cation and in which,
rangements for stabilizing the operating condi
tions of electron discharge tubes. An important
use of the invention is for stabilizing the anode
current of X-ray tubes and the invention will be
described in this connection.
There are several factors in?uencing the sta
Figure 1 illustrates a circuit arrangement in
accordance with the invention;
Figure 2 illustrates a modi?cation of the cir
cuit of Fig. 1 which permits independent adjust
bility of the anode current of X-ray tubes.
ment of the ?lament and anode voltages of an
Among these are variations of the supply voltage
X-ray tube at desired operating values.
of the tube and variations of the internal elec 10
The circuit arrangement shown in Fig. 1 com
trical properties of the tube. The latter varia
prises an X-ray tube l0 having a ?lamentary
tions are brought about chie?y by changes in
cathode H and an anode l2, a ?lament supply
the emission of the ?lamentary cathode of the
transformer [3 having primary and secondary
tube by reason of the change in resistance thereof
windings I 6 and I1, respectively, an anode supply
due to normal evaporation of the ?lament metal 15 transformer l4 having primary and secondary
and/or changes in the emission coen‘lcient due
windings l8 and 19, respectively, and a stabilizing
to localized heating of the ?lament by random.
compensator I 5 comprising two mutually coupled
ionic bombardment and the like.
While varia
windings 26 and 2|. The supply mains for op
erating the X-ray tube are indicated at 22 and 23.
tions of the supply Voltage may be corrected by
The secondary winding ll’ energizes the oathode I! and secondary winding l9 energizes the
anode l2 whereby one end of winding 59 is con
means of a suitable constant-voltage device in
terposed between the Voltage mains and the tube,
a similar simple expedient has not been available
for compensating the changes in the electrical
characteristics of the tube.
nected to the anode and the other end connected
to the cathode ll. One end of each of the pri
It is the object of my invention to provide a 25 mary windings l6 and I?! of the transformers I3
circuit arrangement for correcting variations of
and M respectively, is connected to the supply
the operating conditions of electron-discharge
main 22. The other end of winding I6 is con
devices.
nected to the supply main 23 through the wind
A more speci?c object of my invention is to
ing 28 of the stabilizing compensator l5 and
provide a novel circuit arrangement for counter 30 similarly, the other end of winding I8 is con~
balancing variations in the characteristics of X
nected to the terminal 23 through the winding
ray tubes and stabilizing the anode current there
2| of the stabilizing compensator.
of.
The stabilizing compensator serves to main
These and further objects of my invention will
tain the anode current of the X-ray tube at a
appear as the speci?cation progresses.
C19 substantially constant Value by reason of the
In accordance with the invention, the anode
mutual in?uences of the windings 2G and 2|. For
current of an X-ray tube is stabilized by the
example, assuming for the moment that an in
compensating action provided by two mutually
crease in the resistance of the ?lament has taken
dependent impedances one of which regulates the
place which change would normally decrease the
?lament voltage of the X-ray tube and the other
anode current because of the decreased heating
of which regulates the anode voltage. More spe
and consequently the decreased emission of the
ci?cally, the anode current of an X-ray tube is
?lament. Such a change in ?lament resistance
stabilized by means of two mutually coupled re
causes a decrease in ?lament current and conse
actors one of which is connected in series with
quently a decrease in the current ?owing through
the ?lament voltage supply and the other of
the primary winding I6 of the transformer l3.
which is connected in series with the anode volt
Since the ?lament supply current also passes
age supply. The two reactors are magnetically
through the winding 20, the decreased current
coupled in such a sense that an increase in anode
produces a decrease in the impedance of winding
current produces a compensating decrease in the
2! of the compensator l5 allowing a greater volt
?lament voltage and hence ?lament emission and 50 age to be impressed on the winding [8 of the
transformer 14 and hence impressing a greater
conversely a decrease in anode current due to a
0
l
decrease in ?lament current produces a compen
sating increase in anode voltage whereby the
counterbalancing action so effected maintains the
voltage on the anode l2.
When, for example, an increase in ?lament
emission occurs, for example, because of ionic
anode current at a substantially constant value. 55 bombardment of the ?lament producing addi
2,404,905
3
tional heating, it is found that a, similar stabiliz
ing effect is produced.
More particularly, the
instantaneously increased anode current causes
a larger than normal current to ?ow through
winding l8 and through winding 2i. rI‘he in
creased current through winding 2! increases the
effective impedance of winding ‘20 thereby lower
ing the voltage across winding I6 and conse
quently decreasing the ?lament voltage.
The arrangement shown in Fig. 2 comprises an
X-ray tube 30 having a ?lamentary cathode 3i
and an anode 32. For energizing the cathode 3!
there is provided a ?lament transformer 33 hav
electrically heated cathode having an electron
emissive coe?icient responsive to the temperature
thereof and an anode, circuit means to supply a
current for heating said cathode, circuit means
to supply a current for said anode, and means to
maintain the anode current of said discharge tube
at a substantially constant value comprising, an
impedance in series with the cathode supply cir
euit and an impedance in said anode supply cir
cuit, said impedances being mutually coupled and
being mutually dependent in value and being
adapted to vary the temperature of the cathode
and the anode voltage in an inverse manner pro
portional to changes in the anode current.
2. An electrical circuit arrangement compris
ment. The anode 32 is energized by a transformer 15
ing its secondary Winding connected to the ?la
34 having one leg of its secondary winding con
nected to the anode and the other end of the
ing an X-ray tube including a ?lamentary cathode
winding connected to the cathode 3!. The pri
connected to said ?lamentary cathode, a trans
former having one winding connected to said
anode and the cathode, said transformers each
having an additional winding connected to volt
age supply mains, and. a stabilizing compensator
having a winding connected in series with the
mains and the winding of the ?lament supply
mary winding of transformer 33 is energized
from the power mains 40—4l from a constant
voltage transformer 35 being connected thereto
through a ?lament-voltage regulating resistor 35
and winding 31 of a stabilizing compensator 39
in series. Transformer 34 is energized from the
and. an anode, a transformer having one winding
transformer 35 through the intermediary of an
adjustable autotransformer 42 the movable tap
transformer and having a second winding con
X~ray tube.
I do not wish to be limited thereto for obvious >
the winding of the ?lament supply transformer
and having a second winding connected in series
with the constant voltage transformer and the
winding of the anode supply transformer, said
modi?cations will occur to those skilled in the
art without departing from the spirit and scope
of the invention.
What I claim is:
1. An electrical circuit arrangement compris 55
ing an electron-discharge device including an
windings being mutually coupled in such a sense
that variations in anode current produce inverse
variations of the ?lament current, and the anode
current of the X-ray tube is thereby maintained
at a substantially constant value.
HARRY DOUGLAS GARRETSON.
nected in series with the mains and the winding
of the anode supply transformer, said windings
of which is connected to one end of the primary
being mutually coupled in such a sense that var
winding of transformer 34. The other end of
iations in anode current produce inverse varia
the winding of transformer 34 is returned to the
common terminal of the transformer 42 through 30 tions of the ?lament current, and the anode cur
rent of the X-ray tube is thereby maintained at
the winding 33 of the compensator 39.
a substantially constant value.
By means of the arrangement shown in Fig 2,
3. An electrical circuit arrangement compris
absolute stability of the operating characteristics
ing an X-ray tube having a ?lamentary cathode
of the X-ray tube is achieved and at the same
time a high degree of ?exibility permitting selec 35 and an anode, a transformer having one winding
connected to said ?lamentary cathode, a trans
tion of the anode current and anode voltage at
former having one winding connected to said
preselected values is realized. Thus the ?lament
anode and the cathode, a constant-voltage trans
temperature may be adjusted to any desired op»
former interconnecting said ?lament transformer
erating value by means of the resistor 36. The
anode voltage is similarly adjustable by means of 40 and said anode transformer to voltage supply
mains, means to adjust the voltage applied to said
the autotransformer 42. By means of the con
?lament to a predetermined selected value means
stant voltage transformer 35 the anode current is
to adjust the voltage supplied to said anode to a
stabilized against changes in the voltage of the
predetermined selected value, and a stabilizing
supply mains and by means of the stabilizing
compensator having a winding connected in se
compensator 39 the anode current is made inde- .
ries with the constant voltage transformer and
pendent of changes in the characteristics of the
While I have described my invention by means
of speci?c examples and in speci?c embodiments,
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