4456 4460.output

* GB784863 (A)
Description: GB784863 (A) ? 1957-10-16
Improvements in or relating to electron discharge devices employing photo-
conductivetargets
Description of GB784863 (A)
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The EPO does not accept any responsibility for the accuracy of data
and information originating from other authorities than the EPO; in
particular, the EPO does not guarantee that they are complete,
up-to-date or fit for specific purposes.
PATENT SPECIFICATION 78
Inventors: -HANS GERHARD LUBSZYNSKI and JOHN WARDLEY.
Date of filing Complete Specification: July 7, 1955.
Application Date: July 27, 1954 No 21832154.
Complete Specification Published: Oct 16,1957.
Index at Acceptance-Classes 37, K( 1 DUA: 2: 3 D: 3 R); and 39 ( 1),
D( 41 H: 7 F 2).
International Classification:-H Olj, I.
COMPLETE SPECIFICATION.
Improvements in or relating to Electron Discharge Devices Employing
Photo-Conductive Targets.
We, ELECTRIC & MUSICAL INDUSTRIES LIMITED, a British Company, of Blyth
Road, Hayes, Middlesex, do hereby declare the invention, for which we
pray that a patent may be granted to us, and the method by which it is
to be performed, to be particularly described in and by the following

statement:-
This invention relates to electron discharge devices employing
photo-conductive targets.
Devices of this kind have been proposed for television and similar
purposes in which the target comprises a layer of photo-conductive
material which is deposited on a transparent signal electrode formed
on a glass window of the envelope of the device and the target is
arranged to be scanned by a cathode ray tube so as to generate signals
in accordance with the point-to-point conductivity of the target when
an optical image is projected thereon In one form of device the
photoconductive layer is composed of antimony trisulphide which is
deposited in the form of a spongy layer The glass window of the
envelope in such devices is usually circular and the photo-conductive
layer is usually deposited over the whole area of the window.
In use, however, of such devices it is usually the practice to scan a
rectangular raster the orientation of which relatively to the window
depends on the disposition of the scanning means, which usually
comprise scanning coils surrounding the envelope of the device.
It is found when such devices are initially used or tested that if a
rectangular raster is scanned on the target whilst the latter is
illuminated uniformly, the scanned area has a lower resistance in the
dark and a greater sensitivity compared with the unscanned area
Furthermore, if a checker board image is projected on to the target
and scanned in lPrice 3 s 6 d l a rectangular raster, it is found that
the lighter areas of the scanned pattern have a lower resistance in
the dark and higher sensitivity compared with the darker areas of the
pattern These effects are permanent and are undesirable since it is
obvious that a uniform sensitivity and dark resistance should be
present over the whole of the area of the target, particularly since
after initial use of the device re-orientation of the scanned area may
occur.
The object of the present invention is to provide a method of treating
a photo-conductive target with a view to reducing the above-mentioned
effects.
According to the present invention there is provided a method of
treating a photoconductive target arranged on an electrically
conducting signal electrode with a view to imparting a substantially
uniform sensitivity and dark resistance to the target which comprises
bombarding substantially the whole area of the photo-conductive target
with a high beam current whilst setting up a voltage gradient through
the thickness of said target and whilst the target is illuminated with
a uniform illumination.
A voltage of the order of 150 volts with respect to the cathode may be
applied to the signal electrode in order to set up a high voltage

gradient through the thickness of said target, although preferably,
during treatment of the tube in accordance with the invention the
voltage of the signal electrode is varied from a low voltage to a high
voltage of the order of 150 volts and vice versa, In order that the
said invention may be clearly understood and readily carried into
effect, it will now be more fully described with reference to the
accompanying drawing which illustrates a typical form of electron
1,363 784,863 discharge device employing a photo-conductive target.
As shown in the drawing the reference numeral 1 indicates an evacuated
envelope having a glass end wall 2 on which is formed a transparent
signal electrode 3 having deposited thereon a photo-conductive target
4 which may consist of zinc sulphide or cadmium sulphide but
preferably consists of a spongy layer of antimony trisulphide having a
superimposed solid layer of antimony trisulphide Within the envelope 1
there is provided an anode 5, the end of which adjacent to the
photo-conductive target 4 is provided with a mesh 6 At the end of the
envelope 1 remote from the window 2 there is provided an electron gun
comprising a cathode 7, a cathode screen 8 and a limiter electrode 9
The cathode 1 serves to generate a beam of electrons which can be
scanned over the photo-conductive target 4 by means of scanning coils
10 The electron beam is maintained in focus by means of a solenoid
coil 11 The device shown in the drawing is 2 ' also provided with the
usual alignment coils 12.
In order to avoid the undesirable effects hereinbefore referred to,
the following procedure is adopted The device is conditioned for
operation by connecting the cathode 7 to a source at zero voltage, the
cathode shield to a source of voltage which may vary from 100 to zero
volts, the limiter electrode 9 to a positive source of 300 volts and
3.5 the anode 5 to a similar source of voltage.
The signal electrode 3 is connected to a source of voltage which can
be varied from 0 to 150 volts positive whereby a voltage gradient can
be set up through the thickness of the target 4 The usual current
supply is applied to the coil 11 and to the alignment coil 12 and a
suitable scanning waveform is applied to the coil 10 so as to enable
the whole of the target area to be bombarded with electrons The
electron beam is also defocused either by varying the normal current
supply of the solenoid 11 or by varying the voltage of the electrode 8
or both and the beam current is adjusted to a high value.
-50 With the device operating in this manner the whole of the target
area is then illuminated with a uniform illumination from a light
source indicated conventionally at 13, this illumination being of the
order of 15 to -5 200 foot candles, and the voltage applied to the
signal electrode 3 is then slowly made positive up to 150 volts and
down to zero volts several times, say 2 to 6 times during a period of

20 seconds whilst the whole area of the target is scanned with said
defocused beam The same process is then repeated with the target in
the dark The scanning beam may employ a beam current of several
microamperes, say up to 10 microamperes which is high compared with
the normal operating beam current of, say, one to two microamperes
Instead of applying a voltage to the signal plate 3 in order to set up
the voltage gradient through the target 4 a similar voltage gradient
can be established through the thickness of the photo-conductive
target 4 by applying a suitable negative voltage to the cathode 7 It
is desirable during the treatment of the device in the above manner to
ensure that the impedance of the photo-conductive target 4 does not
become too low, say as low as a few megohms (say 10), by employing too
much illumination from the source 13 The method described above is
found to result in an overall sensitivity gain of between 3 and 9 db
over an untreated target and retention of images is found to be
substantially avoided.
( 5 i O
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* GB784864 (A)
Description: GB784864 (A) ? 1957-10-16
Improvements in or relating to a device for supplying an electric out-put
quantity in dependence upon an electric in-put quantity
PATENT SPECIFICATION
7849864 Date of Application and filing Complete Specification July 27,
1954.
No 21987/54.

Application made in Germany on July 27, 1953.
Application made in Germany on July 1, 1954.
Complete Specification Published Oct 16, 1957.
I Ldex at Act u,:-Classes 38 ( 2), TIF, T 7 (A 3: A 7 A 9: C 2: CS);
38 ( 4), R( 4: 21 B 3: 67); and ( 4), lr 93 International
Classification: -GO Of H 02,L H 03 f.
COMPLETE SPECIFICATION
Improvements in or relating to a Device for Supplying an Electric
Out-Put Quantity in Dependence upon an Electric In-Put Quantity We,
SIEMENS-SCEUCKERTWERKE ARTIENGESELLSCHAFT, a German company, of Berlin
and Erlangen, Germany, do hereby declare the invention, for which we
pray that a patent may be granted to us, and the method by which it is
to be performed, to be particularly described in and by the following
statement: -
This invention relates to a device for supplying an output, in the
form of an electric control quantity in dependence upon deviations
from a standard value of an electric quantity which is to be regulated
and is supplied as an input to the device.
According to the present invention there is provided a device for
supplying an output, in the form of an electric control quantity, in
dependence upon deviations from a standard value of an electric
quantity which is to be regulated and is supplied as an input to the
device, wherein a magnetic bridge is provided, the arms of the bridge
including a permanent magnet acting as a source of a magnetic standard
value and an electromagnet arranged to be energised by said electric
quantity and to furnish a unidirectional flux accordingly, there being
provided a choke having a doublelimbed core arranged to act as a
diagonal of the bridge in such manner that the core carries, in the
same direction in each limb, a flux determined by the difference
between the flux of the permanent magnet and that of the
electromagnet, and wherein each limb of the chokce core is provided
with a winding so that the effective impedance of such windings is
controlled by said difference, said windings being arranged to carry
alternating current which constitutes, or is arranged to furnish, said
electric control quantity and, in consequence of the control upon said
effective impedance, is controllable in dependence upon the deviation
of said electric quantity from a standard value, the choke windings
being so connected that the alternating fluxes which they produce are
substanlly confined to the magnetic circlit which is constituted by
the choke core and which includes both limbs thereof.
Preferably, the two windings of the choke are electrically
series-connected Since the two alternating fluxes tend to become equal
owing to the use of a common core, the normal behaviour of a series
choke is disturbed, and a small alternating flux remains which flows

through the magnetic path provided by the arms of the bridge However,
this does not affect the satisfactory operation of the choke.
In the known arrangements the whole alternating flux must pass through
the arms of the bridge.
The effective permeability of the choke core, and hence the impedances
of the choke windings, varies according to the flux passing through
the choke Thus if an alternating auxiliary voltage is applied to the
choke windings, the alternating current which is set up in the choke
windings depends not only upon the value of that voltage but also upon
the value of the input quantity (that is, for example, the value of a
quantity to be regulated) which is converted in the electromagnet of
the bridge into a magnetic measurement value In order to obviate the
dependence upon the auxiliary voltage a second choke is preferably
employed to which is applied the input quantity (by means of an
electromagnet) and an auxiliary alternating voltage of the same value
as that applied: in the first choke and preferably being obtained from
the same source The difference between the alternating currents of the
two chokes, if necessary after rectification thereof, or a quantity
the value of which depends on such difference is employed as the
output quantity of control quantity of the device The second choke may
be pre-magnetised in dependence upon the quantity to be regulated In
this case, if the permanent magnet of the first choke develops a flux
greater than that of the associated electromagnet, and if 'the second
choke has no permanent magnet whereby the 784,864 advantage is
afforded that as the quantity to be regulated increases, a decrease in
the premagnetisation of the first choke core occurs, while an increase
in the premagnetisation of the core of the second choke occurs, so
that when the quantity to be regulated has a certain value the
premagnetisations of the two chokes and consequently also the
alternating currents in the windings of the chokes are equal The
differential effect of the currents in the windings of the two
respective chokes is then zero.
In order to obtain a substantially linear relationship between the
premagnetisation of the choke core and the quantity to be regulated,
one or more air-gaps are preferably provided in the magnetic circuit
and are formed in the second choke in the core thereof and in the core
of the electromagnet.
A simplification may be effected by employing an electromagnet, which
is energised in dependence upon the quantity to be regulated and is
common to both the magnetic circuit of the bridge and to the magnetic
circuit of the second choke.
For increasing the sensitivity of regulation, it may prove expedient
to energise the electromagnet additionally in dependence upon the
output quantity of the system, that is to say, to use a form of

feedback.
For obtaining a large working range with a changing value of an
auxiliary alternating voltage feeding the choke, and of the frequency
thereof, it is desirable to employ for the choke cores a material
having a magnetisation curve or hysteresis loop of approximately
rectangular form.
The permanent magnet is preferably constructed of high-grade
permanent-magnet material, such for example as the known
aluminium-nickel-cobalt alloys, with a view to reducing the space
occupied For the remaining parts of the magnetic circuits, apart from
the choke core and the permanent magnet, a magnetic material of low
coercivity, such for example as carbonyl iron, is preferably employed.
If a second choke is used for obviating the influences of fluctuations
of the auxiliary alternating voltage with which the first choke is
fed, and the second choke is fed with an alternating voltage of the
same value as the first voltage, and if the differential effect of the
alternating currents in the tvw chokes are employed as a control
quantity after rectification, an arrangement may be used in which a
separate rectifier is not required to rectify the current flowing
through each of the chokes, but, instead, a rectifier system common to
the two chokes may be employed, which feeds a control winding.
Thus, while, for example, a rectifier comprising four rectifying
elements can be employed in a bridge connection for each choke, a
total of only four rectifying elements need be utilised if the two
sets of leads by which the two chokes are fed with alternating
voltages, or windings generating these voltages, are connected
together at one pole In this case, like terminals, referred to the
direction 70 of the alternating voltages, can be coupled together, or
opposite terminals can be connected together A control winding, for
example which form part of a magnetic amplifier, is provided with a
centre tapping which 75 is joined to the connection point of the two
voltage sources or windings.
If like terminals of the windings or voltage sources are connected
together the whole current of each choke flows through the control 80
winding The difference between the two choke currents in the control
widding is thus effective as an ampere-turns difference at the
amplifier On the other hand, if a coupling between opposite terminals
of the windings or 85 alternating-voltage sources is employed, the
difference between the two rectified alternating currents flows
direclly through the control winding The control winding therefore
only requires to be designed for the difference of 90 the currents of
the chokes in this case.
For a better understanding of the invention and to show how the same
may be carried into effect, reference will now be made to the

accompanying drawings in which: 95 Fig 1 is a diagrammatic drawing of
an electromagnetic crontrolling device, Fig 2 is a diagrammatic
drawing of an electromagnetic controlling device with associated
circuits, 100 Fig 3 is a diagrammatic drawing of an electro-magnetic
controlling device with associated circuits, and Figs 4, 5 and 6 are
electric control circuits.
Referring now to the drawings, ln Figure 105 1, 1 designates a clhoki
core asszmbly with two working windings 2 and 3, tih of which are
arranged to carry alteona:ins current This choke assembly forms ahe
diagonal branch of a magnetic bridge, the arms of the bridge com 110
prising a permanent magnet 4, an electromagnet serving as an
actual-value converter and comprising a core 5 and a w-vinding 6, two
yoke pieces 7 and 3, and two air gaps 9 and 10.
The winding 6 carries a controlling d c 115 current derived from the
actual value, i e the quantity to be regulated The difference between
the magnetic fluxes prcluzed by the permanent magnet 4 and the
electromagnet ( 5-6) produces a premagnetising unidirec 120 tional
flux in the choke core 1, this flux acting in the same direction in
each limb of the choke.
However, the flux produced by the alternating current windings
circulates around the choke so that in any half-cycle, the
unidirectional and 125 alternating fluxes are additive in one limb and
oppositely directed in the other.
In one half-cycle of the alternating current, one limb of the choke
core therefore remains substantially saturated, and at the same time
130 784,864 the other limb is unsaturated and is capable of producing
a reactive voltage in the choke wind ing thereon The value of the
premagnetising unidirectional flux in the choke core depends upon the
value of the input quantity, that is, for example, on the quantity to
be regulated, due to the formation of the difference between the
unidirection fluxes of the permanent magnet and of the electromagnet,
so that an alternating current in the choke windings varies in
accordance with the in-put quantity.
In Figure 2, A is a controlling device corresponding to the one shown
in Figure 1, the same references have therefore been retained for like
parts for the sake of simplicity.
Associated with the device A is a second controlling device 13 in
which the core 11 of a choke has windings 12 and 13 Two yoke pieces 14
and 15 co-operate through air gaps 16 and 17 with the core 18 of an
electromagnet, the associated winding of which is designated by 19 The
winding 6 of the converter for the actual measurement value in the
form of the electromagnet ( 5-6) is fed, through a resistance 20, with
a current which depends upon, for example the quantity to be
regulated, from conductors 21 A current is produced, by the same

voltage as e:ists between conductors 21, and fed to the winding 19 of
the electromagnet ( 18-19) of the device B through the resistance 22.
The windings ( 2 and 3) of the device A are fed from secondary winding
23 a of a transformer 23, at the primary winding 23 b of which an
alternating voltage exists The windings 12 and 13 of the device B are
fed from another secondary winding 23 c of the transformer 23, which
winding supplies a voltage of the same value as that supplied by the
winding 23 a The choke current of the device A is rectified by a
fourelement rectifier 24 and Passed through a load The choke current
of the device B is rectified by a four-element rectifier 26 and passed
through a load 27 The two loads 25 and 27 may be, for example, control
windings of a magnetic amplifier which is to be controlled.
Alternatively, a separate control winding of a magnetic amplifier may
be connected to the terminals 28 and 29, and be supplied with a feed
voltage equal to the difference between the voltages across the load
resistances 25 and 27.
The device B co-operates with the device A so that a difference
voltage corresponding to the two altertating currents in the chokes of
the devices A and B is set up at the output, for examples at the
terminals 28 and 29 If the chokes of devices A and B are equally
premagnetised, the two choke currents are equal, regardless of the
value of the auxiliary alternating voltage applied to the transformer
or of the frequency of this voltage.
In Figure 3, like narts are again designated by the same reference
numerals, insofar as they are equivalent to the parts shown in Figures
1 and 2, with the exception of the two electromagnets ( 5-6) and (
18-19) of the devices A and B. In Figure 2 the devices A and B are
spati 70 ally independent units, but in Fig 3 they are shown as
permanently associated together as units A' and B', and they now have
a common electromagnet with a core 30 and a winding 31 which is fed
from terminals 21 through a 75 resistance 32 with a current derived
from the actual value The electromagnet has a further winding 33 which
is fed with a current derived from an output quantity of the system at
the ends of load resistances 25 and 27, so that the 80 output quantity
is fed back to the device.
The expenditure in a device as shown in Figure 3 is reduced in
relation to that of the device shown in Figure 2.
With an actual quantity of a predetermined 85 value at the terminals
21, the premagnetisation in the two chokices units A' and B' is equal
in value, so that the difference between their rectified alternating
currents is zero If the flux produced by the permanent magnet 4 is
greater 90 than that produced by the electromagnet, an increase of the
actual value at the terminals 21 brings about a decrease of
unidirectional flux in the choke core 1 so that the permeability of

this core increases Thus the impedance of 95 the windings 2 and 3
increases so that the chokice current of the unit A' decreases That of
the choke in unit B' also increases Conversely, if the actual value at
the terminals 21 decreases, the choke current of the unit A'100
increases, while that of the unit B' simultaneously decreases The
differential effect of the output currents acting through the loads 25
and 27 accordingly varies in value and direction in dependence upon
the deviation of the 105 actual value from a reference value,
predetermined by the permanent magnet.
It is expedient to employ a material for the choke cores, for example
1 and 11, having a hysteresis loop which is as far as possible rect
110 angular The yoke pieces 7, 8, 14 and 15 and the core of the
electromagnet 30 are preferably constructed of a material having low
coercivity.
The permanent magnet preferably consists of a material of high
coercivity with high remanent 115 induction, for example of an
aluminium-nickelcobalt alloy.
In Figure 4, 101 designates a transformer which feeds the windings of
two chokes 102 and 103 corresponding to the chokes of the 120 units
previously described Only the working windings of the chokes 102 and
103, which chokes correspond to the chokes A, B and A' B' of Figures 2
and 3 respectively, are shown.
One terminal of one secondary winding of the 125 transformer 101 is
connected to a like terminal of the other secondary winding The two
chokes are connected to a common rectifier system comprising
rectifying elements 104 a to 104 d The control winding 105 of a 130
784,864 magnetic amplifier is connected to the output of this
rectifier system 104 A centre tapping a of winding 105 is connected to
the common connection of the two secondary windings of the transformer
101 During one halfcycle of the alternating current, the current of
the choke 102 flows through the element 104 b and the upper half of
the control winding 105 to the common connecting point of the two
secondary windings of the transformer At the same time, the current in
the choke 103 flows through the element 104 d and the lower part of
the control winding 105 to the common connecting point of the two
secondary windings of the transformer 101 The arrows indicate the
magnetic energisations produced by the windings For the above
described halfcycle, the arrows are drawn as continuous lines.
During the other half-cycle, the currents flowing through the windings
produce magnetisations in the two halves of the winding 105 as
indicated by the broken-lined arrows.
In Figure 5, the same references have again been used for the same
parts as in Figure 4.
As will be seen from the figure, opposite terminals of the two

secondary windings of the transformer 101 are connected together in
this case In one half-cycle of the alternating current, the current
flows through the choke 102 and through the rectifier element 104 b,
and back through the upper half of the control winding 105 to the
common point of the two secondary windings At the same time, the
current flows by way of the choke 103 through the upper half of the
winding 105 and the rectifying element 104 c, back to that terminal on
the secondary side of the transformer which is associated with the
choke 103 This is indicated by the arrows drawn in continuous lines in
the figure.
It will be seen from this that only the difference between the
currents in the tw Vo chokes 102 and 103 flows through the upper half
of the control winding 105 In the other half43 cycle of the
alternating current, this difference current similarly flows through
the lower half of the control winding 105, as indicated by the
broken-lined arrows.
In this arrangement, the reztifie: elements are only subjected to a
very small inverse voltage, because the inverse voltage which the
elements 104 a and 104 d have to block in common is equal to the volt
drop in the forward direction across the elements 104 b and 104 e.
Figure 6 of the drawings illustrates a complete arrangement in which a
regulating arrangement as shown in Figures 4 or 5 is employed In this
arrangement, 106 is a device 6 C for supplying an electrical control
quantity which includes the arrangement shown in Figure 4 or Figure 5
with the exception of lthe control winding 105, which is formed in
this figure by two windings 107 and 108 109, 110 and 111 are
connecting conductors leading to a three-phase current supply system,
from which a load is fed through saturable regulating chokes 112 and a
transformer 113, through a rectifier 114 having a smoothing device 115
connected thereto and through the 70 terminals 116 and 117 The voltage
at the load terminals 116 and 117 is fed, as a quantity to be
regulated, through the conductors 118 and 119 to the regulating
arrangement 106 The actual value may be adjusted by variation of 75
the resistance 120 The aforesaid windings 107 and 108 form a control
winding of a magnetic amplifier 121 The said amnlifier also comprises
two working windings 123 and 124 fed by an alternating-current source
122, which 80 is so connected with rectifying elements 125 to 128 that
a direct voltage is supplied at the output terminals 129 and 130 of
the arrangement The amplifier feeds, through a resistance 131 a
control winding 132 having the terminal 85 connections a-b This
control winding is associated with the chokes 112, as may be seen
fromn the illustration this winding also being shown at the choke 112
The winding 132 is shown twice for ease of illustration A 90 further
winding 133 having the terminals c and d is fed in the oppsite

direction through the resistance 134 by the voltage across the
terminals 116, 117 This winding is also again shown with the same
reference 133 at the 95 chokes By reason of the fact that the chokes
112 are designed as so-called rectifier chokes, with which a
rectifying element is connected in series with each of the
alternating-current lworking windings, so that only one half-cycle 100
fisws through one of the working windings and only the other
half-cycle throuah the other workzing winding, a load-dependent
pre-magnetisation of the choke is obtained It will be assumed by way
of example in accordance with 105 the arrows placed above and below of
the windings 132 andl 133 and in accordance with the rectifier s-ymbol
placed ab:ve the winding 132 that in the hai,-cele of the alternating
current considered the rectifvin elements hay 11 C ing the forward
direction is effective for the load current The rectifying element
thus determnines the direction of the rremagnetisation, which is '3
roduced at the choke 112 in depnsdepne upon lead At the same time, the
115 winding 132 surplics, in the case assumed, a minagnetisation in
the direction of the arrow indicated above by this winding When the
voltage across the load terminals ( 116-117) increases, the
arrangement 10 supplies a con 120 trol current through the windings (
107-108) to the amnlifier 121 in the sense that the outnut voltage
across the terminals ( 129 130) and consequentlv the current through
the w.inding 132 in the direction rb-) increases 125 Thus thle
effective premagnertisation of the chokse 112 decreases so that the
impedance of its load windings increases This brings about an increase
in the voltage drop across the load windings of the choke 112 and
consequently 130 arms of the bridge including a permanent magnet
acting as a source of a magnetic standard value and an electromagnet
arranged to be energised by said electric quantity and to furnish a
unidirectional flux accordingly, there 70 being provided a choke
having a doublelimbed core arranged to act as a diagonal of the bridge
in such manner that the core car-.
ries, in the same direction in each limb, a flux determined by the
difference between the flux 75 of the permanent magnet and that of the
electromagnet, and wherein each limb of the choke core is provided
with a winding so that the effective impedance of such windings, is
controlled by said difference, said windings being 80 arranged to
carry alternating current which constitutes, or is arranged to
furnish, said electric control quantity and, in consequence of the
control upon said effective impedance, is controllable in dependence
upon the devia 85 tion of said electric quantity from a standard
value, the choke windings being so connected that the alternating
fluxes which they produce are substantially confined to the magnetic
circuit which is constituted by the choke core 90 and which includes

both limbs thereof.
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* GB784865 (A)
Description: GB784865 (A) ? 1957-10-16
Improvements in or relating to quick cooking rice
c; -% I N -, ' q 41 '
-7 4 4 PATENT SPE Ci FICATION 7894,g 5 Date of,, i tion and Filing
Ccmplet 6
Specification: Aug31, 1954 1 N'o2522/54.
Application made in United States of America on Sept IQ,; 953.
f Patent of Addition to No 657,691 dated April 22, 19 X 8 as imprc'er
use or modified by No 737,372 dated Feb 8, 195 'L Complete
Specification Published: Oct 16, 1957.
Index at Acceptance:-Class 58, A 3 B, AH( 3: 4 A: 4 C: 6 D).
International Classification:-B 02 b.
Improvements in or relating to Quick Cooking Rice.
E Ri ATA SPECIFICATION NO 784, 865

, line 42, for irt read air,.
Page 4, line 68, for,isomewhate read "scaeiat THE PAT Ei NT OFFICE,
25th A Tovember, 1957 in the external portions or sheath of the rice
grain should comprise moist, substantially completely gelatinized
starch in a completely pliable condition, as set forth in the
above-mentioned specification, the internal portions or core of the
grain need not be relatively brittle but may range from this condition
(i e, partially gelatinized and relatively brittle) to a condition of
substantially complete gelatinization and pliability.
If the internal portions have not been gelatinized at all, the degree
of brittleness is too high for the purpose of the present invention
But rice which has been soaked to 'n about 30 % moisture and then
steamed to fully gelatinize the exterior portions while the interior
portions are only slightly gelatinized, and also rice which has been
fully gelatinized, dried and then steamed briefly to moisten only the
exterior portions of the grain, are both suitable for application of
the step of mechanical compression So also is a rice grain having
fully pliable exterior portions along with interior portions of
substantially equal pliability Thus it will be seen further that the
moisture content of 34 ,% mentioned in the above specification is not
a limiting value.
According to the present invention there DB 00840/1 ( 22)/3606 150
111/57 R increase its moisture cunot Lrut LU a uuataial degree, say,
17-36 %, preferably 25 %, and steamed to partially or completely
gelatinize the rice and further increase its 65 moisture content, say,
by 1-8 %, but as a rule not to exceed 40,/o The rice is coimpressed
and then dried in any suitable manner.
2 Ungelatinized, milled rice is soaked to 70 increase its moisture
content to a substantial degree, say, 17-36 %, preferably 25 35 %, and
steamed to completely gelatinize the rice and further increase its
moisture content, say, by 1-8 %, but as a rule not to ex 75 ceed 40 %
The rice is mechanically compressed and placed in water to increase
its moisture content to 60-70 % On the other hand, after steaming as
above described, the rice may be soaked in water to raise its 80
moisture content to 60-70 % as above and thereafter compressed
Preferably, the rice is contacted with the soaking water while still
hot from the steaming since this provides the rice in an enlarged
condition which 85 greatly facilitates soaking At a moisture content
appreciably above 70 % the advantages of compression are not as great
as when the rice contains less moisture The rice is then dried in any
suitable manner, 90 PATENT SPECIFICATION
Dcte of Appiication and Filing Complete Specification: Aug31, 1954 No
25239/54.
Application made in United States of America on Sept 10, 1953.

(Patent of Addition to No 657,691 dated April 22, 1948 as improved
upon or modified by No 737,372 dated Feb 8, 1951).
Complete Specification Published: Oct 16, 1957.
Index at Acceptance:-Class 58, A 3 B, AH( 3: 4 A: 4 C: 6 D).
International Classification:-BO 2 b.
Improvements in or relating to Quick Cooking Rice.
1, A 1 AULLAH KHAN OZAI-DURRANI, a citizen of the United States of
America, of 7th Street, and Grand Avenue, Stuttgart, Arkansas, United
States of America, do hereby declare the invention, for which I pray
that a patent may be granted to me, and the method by which it is to
be performed, to be particularly described in and by the following
statement: -
This invention relates to a method of preparing a quick cooking rice
product and to the rice product itself.
The present invention is an improvement in or modification of earlier
Specification
Serial No 737,372.
It has been found that while the starch in the external portions or
sheath of the rice grain should comprise moist, substantially
completely gelatinized starch in a completely pliable condition, as
set forth in the above-mentioned specification, the internal portions
or core of the grain need not be relatively brittle but may range from
this condition (i e, partially gelatinized and relatively brittle) to
a condition of substantially complete gelatinization and pliability.
If the internal portions have not been gelatinized at all, the degree
of brittleness is too high for the purpose of the present invention
But rice which has been soaked to about 30 ,,, moisture and then
steamed to fully gelatinize the exterior portions while the interior
portions are only slightly gelatinized, and also rice which has been
fully gelatinized, dried and then steamed briefly to moisten only the
exterior portions of the grain, are both suitable for application of
the step of mechanical compression So also is a rice grain having
fully pliable exterior portions along with interior portions of
substantially equal pliability Thus it will be seen further that the
moisture content of 34 %,h mentioned in the above specification is not
a limiting value.
According to the present invention there is provided a process for
preparing qui 2 cooking rice which comprises suijectini rice grains,
having exterior portions of moist, substantially completely
gelantinized starch in a completely pliable condition and 50 interior
portions ranging from relatively brittle, at least partially
gelatinized starch to substantially completely gelatinized starch in a
completely pliable condition, to mechanical compression to distort and

modify 55 the structure of the rice grains without ducing them to a
flaked condition.
The following procedures illustrate by way of example various ways in
which the invention can be carried out: 60 1 Ungelatinized, milled
rice is soaked ti increase its moisture content to a substantial
degree, say, 17-36 %, preferably 25%, and steamed to partially or
completely gelatinize the rice and further increase its 65 moisture
content, say, by 1-8 %, but as a rule not to exceed 40 % The rice is
compressed and then dried in any suitable manner.
2 Ungelatinized, milled rice is soaked to 70 increase its moisture
content to a substantial degree, say, 17-36 %, preferably 25 35 %, and
steamed to completely gelatinize th 3 rice and further increase its
moisture content, say, by 1-8 %, but as a rule not to ex 75 ceed 40 %
The rice is mechanically compressed and placed in water to increase
its moisture content to 60-70 % On the other hand, after steaming as
above described, the rice may be soaked in water to raise its 80
moisture content to 60-70 % as above and thereafter compressed
Preferably, the rice is contacted with the soaking water while still
hot from the steaming since this provides the rice in an enlarged
condition which 85 greatly facilitates soaking At a moisture content
appreciably above 70 % the advantages of compression are not as great
as when the rice contains less moisture The rice is then dried in any
suitable manner,90 preferably at relatively high temperature cient to
raise the moisture content to about and air velocities 30 % Such
soaked grains have the non3 Ungelatinized, milled rice is soaked to
uniform moisture distribution described in increase its moisture
content to a substant our above specification, and when they are ial
degree, say, 17-36 %o, preferably 25-35 %, heated for brief periods,
the pliable sheath 70 and steamed briefly to render only the sur and
brittle core described in our above face portion of the grains pliable
and gelat specification are produced, as well as the inized The rice
is compressed, steamed for results of compression and drying therein
an additional period to complete gelatini described The same results
are obtained zation throughout the rice grains and then when parboiled
or otherwise pregelatinized 75 dried in any suitable manner Before dry
dry rice grains are moistened, compressed ing the rice may be soaked
in hot or cold and dried as in procedures 5 and 7 outwater as desired
to increase its moisture lined above.
content to 60-70 %O in which case it is pre But relatively long
periods of heating the ferably dried using relatively high tempera
soaked grains will produce grains that ares O tures and air velocities
substantially completely pliable throughout.
4 Dried, milled rice, either ungelatinized A similar condition is
produced when the or parboiled or otherwise gelatinized, is grains,

either ungelatinized or parboiled, placed in hot or boiling water to
raise the are placed in hot or boiling water to inmoisture content to
60-70 %, and in the crease their moisture content to about 60-85 case
of the former, effect gelatinization The 700, as in the fourth
procedure, and when rice is compressed and thereafter dried, pre
previously gelatinized rice is steamed long ferably at relatively high
temperatures and enough to increase its moisture content to air
velocities 17-25 /as in the sixth procedure in the 5 Dried, milled,
parboiled or otherwise eighth procedure on the other hand the 90
gelatinized rice is contacted briefly with external portions after
drying may be somewater to moisten the surface of the grains what less
moist and hence less pliable than and then steamed for a short period,
the the internal portions but are still sufficiently moistening and
steaming serving to increase pliable to prevent disintegration of the
the overall moisture content of the rice by grains during compression
95 1-5 %, the bulk of the moisture being con In the preferred
e-ibodilment of the incentrated at the surface of the grains The
vention, ungelatinized milled white rice (the rice is then
mechanically compressed and ordinary rice of commerce) is treawed
subdried in any suitable manner stantially as set foth in our above
specifica6 Dried, parboiled or otherwise gelatin tion except that the
moisture content after 100 ized rice is steamed for a sufficient time
to soaking ma sometimes be hioher than increase the overall moisture
content of the specified therein say 36 and mray somerice to 17-25 %'
and render the entire grain times be inceased during steaming by as
fully pliable The rice is then mechanically much as 8-,; at such
higher moisture concompressed and dried in any suitable man tents the
steaming period may be as little 105 ner In the case of rough rice,
the com as 3 minutes Compression of the grains pression step serves to
crack and loosen the then takes place between rolls as set forth hulls
which may be separated from the in our above specification.
grains in any conventional manner in the case of grains having
relatively 7 Dried, milled, parboiled or otherwise high moisture
contents, e g, in the neigh 10 gelatinized rice is placed in cold
water for a bourhood of 65 %, a press may be preperiod of time
sufficient fo raise its moisture ferred to rolls in order to avoid
undue disto 30-70 %, say, 30-60 minutes The rice is integration of the
grains.
then compressed and dried While any suitable drying method can be 8
Ungelatinized, milled rice is soaked to employed, circulation of
heated air through 115 increase its moisture content to a substanial a
bed of rice is highly efficient and usually degree, say 30 %,0,
steamed to substantially to be preferred Any temperature may be fully
gelatinize the grains throughout and used below that at which

scorching or disincrease its moisture content to about 350,',
coloration occurs say 375 4 f J O F ShrinkThe rice is then dried in
any conventional age may occur at temperatures of the order 120 manner
to 17-25 %, compressed and dried of 150 '-200 F, however and when the
It is preferred that a tempering step be em moisture content of the
rice is high, say ployed after the first drying step so that the 55-70
%, temperatures and air velocities of moisture distribution within the
grains may the order of 280 F and 200 ft /mill are be uniform and the
moisture of the exterior preferred In the case of relatively low 125
portions be thereby increased so that said moisture content, say 17-40
K, still higher portions will have greater pliability temperatures of
the order of 325 '-350 'F.
When it is desired to soak the rice prior have the advantage of
producing a slight ento steaming or cooking, 30 minutes soak largement
of the grains.
ing at room temperature is generally suffi EXAMPLE I 130 784,865
784,865 pounds of ungelatinized white rice ith a moisture content of
about 12 are placed in a 100 gallon vessel or tank together with about
60 gallons of water and allowed to soak for 30 minutes at room
Temperature ( 75 F) Thereafter the rice is transferred from the tank
to a screen and allowed to drain for 15 minutes At this point the rice
contains about 30 %,' of moisl: ture Satisfactory results are obtained
in accordance with this embodiment of the invention if the conditions
of soaking are varied so that the moisture content may range from
about 17 %, to about 36 %, preferable results are obtained at 25-35 %.
Then the rice is transferred to an 80 gallon autoclave and treated
with dry steam at 8 pounds gauge pressure for 5 minutes at the end of
which time the outer portions of the rice grains are substantially
completely gelatinized containing no birefringent material and the
inner portions while somewhat gelatinized still contain an appreciable
amount of ungelatinized starch granules or birefringent material The
overall moisture content of the grains after steaming is about 34 %- 7
Generally, rice prepared in this manner may have a moisture content of
about 17-40 %, and be suitable for compression The rice grains are
then removed from the cooker and transferred to a conveyor belt, being
spread out thereon in a layer about one grain thick The grains are
thus conveyed to and passed between smooth rolls set to reduce the
thickness of the grain to about % of their thickness before
compression.
After passing through the rolls the rice is dried in any conventional
manner to a stable moisture content of 10 to 14 % A convenient and
rapid way of effecting drying is to employ a forced draft, hot air
drier using ir at 325 -350 F, the drying being effected in 5-10
minutes The product has a density of 0 70 g /cc It is then packaged

and distributed in the usual commercial manner.
EXAMPLE II pounds of ungelatinized white rice with a moisture content
of about 12 % is placed in a 100 gallon vessel or tank together with
about 60 gallons of water and allowed to soak for 30 minutes at room
temperature ( 75 F) Thereafter, it is transferred from the tank to
another tank containing boiling water and boiled for about 10 minutes
to fully gelatinize an hydrate the grains raising their moisture
content to 65 % The rice is then cooled and transferred to a
horizontally moving screen o 60 from the end of which it falls onto
one of a pair of smooth compression rolls spaced apart sufficiently to
compress the grains to about 70 %, of their thickness before
compression In order to facilitate handling at to this point a stream
of cold water is played onto the same roll onto which the rice grains
are deposited so that at the time of compression the grains are in
effect slurriel in water this prevents the grains from sticking to the
rolls so that disintegration is 70 prevented oi at least minimized
From the rolls the compressed rice grains and the water fall onto a
horizontally moving screen The rice grains are drained in the first
tfew feet of their travel on the con-75 veyor Thereafter, hot air at a
temperature of about 285 F is blown upwardly through the bed of rice
grains at an air velocity of about 200 feet per minute If desired, at
a subsequent point in the screen's travels the 80 hot air may be
passed downwardly through the bed of rice grains In this manner, the
relatively enlarged size of the grains resulting from the complete
gelatinization and hydration of the rice is preserved to a great 85
degree and the rice is reduced to a stable moisture content of 10,14
%, the final product having a density of 0 25-0 45 g /cc.
EXAMPLE III 90 pounds of milled, parboiled or otherwise gelatinized,
dried rice with a moisture content of about 12,', are placed in an 80
gallon autoclave and steamed at 8 lbs,'sq.
in (gauge) for 8-10 mrinutes to raise the 95 moisture content thereof
to 22 % and render said grains completely pliable throughout
Thereafter, said grains are compressed by passing the same through
rolls, spaced so as to reduce the grains to about 60 %, of 100 their
thickness before compression, and the rice is dried to a stable
moisture content of 10-14 %, in the manner described in detail in
Example I above, the final product having a density of 0 70-0 75 g /cc
105 EXAMPLE IV pounds of milled, parboiled or otherwise gelatinized,
dried rice with a moisture content of about 12 % are placed in about
gallons of water contained in a 100 gal-110 lon tank at room
temperature ( 75 F) and allowed to soak in the water for two minutes
The soaked rice is then removed from the water, drained for a half
minute and placed in an 80 gallon autoclave and 15 steamed at 8 Ibs
/sq in (gauge) for 1-2 minutes to render the surface portion of the

grains pliable and increase the overall moisture content of the grains
by about %, the interior portions of the grains re-120 maining
substantially unchanged Therearter, said grains are compressed by
passing the same through rolls, spaced so as to reduce the grains to
about 80 % of their thickness before compression, and dried to 125 a
stable moisture content of 10-14 % in the manner described in detail
in Example I above.
EXAMPLE V pounds of milled, parboiled or other 130 wise gelatinized,
dried rice With a moisture content of about 12 'o are placed in about
gallons of water in a 100 gallon tank and allowed to remain therein
for about one hour at room temperature ( 75 F) and raise the moisture
content of the rice to 50, The rice is then drained for 15 minutes
Thereafter said grains are compressed by passing the same through
rolls, spaced so as to reduce the grains to about 80 ' of their
thickness before compression, and dried to a stable moisture content
of 10-14 ', in the manner described in detail in Example I above The
density of this product is O 65-0 75 g /cc.
EXAMPLE V 1 pounds of ungelatinized rice with a moisture content of 12
%, is placed in a 100 gallon tank together with 60 gallons of water
and soaked for 30 minutes at room temperature ( 75 F) Thereafter it is
transferred from the tank to a screen and allowed to drain for 15
minutes At this point the rice contains 30 %, moisture The rice is
transferred to an 80 gallon autoclave and treated w.ith steam at 8 lbs
/sq in for 10 minutes and completely gelatinized Thereafter the rice
is returned to the soaking tank and allowed to soak in the water for
an additional period of 20 minutes which serves to increase the
moisture content of the rice to about 65 ',, The rice is then removed
from the soaking water, drained for 15 minutes.
blasted with cold air to toughen the surfaces of the grains and then
subjected to mechanical compression by passing the same through rolls
spaced so as to reduce the grains to about 70, of their thickness
before compression and dried to a stable moisture content of 10-14-,
as described in detail in Example 11 above The density of this product
is 0 4 g /cc.
If desired, the rice may be soaked and 45steamed to fully gelatinize
the same, compressed and then soaked in water to fully hydrate the
same to 60-70, moisture and then dried.
Also, the rice may simply be soaked, steamed to fully gelatinize the
same, and then compressed and dried.
EXAMPLE Vli pounds of ungelatinized white rice with a moisture content
of about 12 %, is placed in a 100 gallon vessel or tank together with
about 60 gallons of water and allowed to soak for 30 minutes at room
temperature ( 75 F) Thereafter the rice is transferred from the tank
to a screen and allowed to drain for 15 minutes At this point the rice

contains about 30 % of moisture The rice is then transferred to an 80
gallon autoclave and steamed at 8 Ibs /sq.
in (gauge) for 5 minutes at the end of which time the outer portions
oi ile rice grains a,:
completely gelatinized ailnd the inner p):tions:h:ile some;haic
gelatinzedl still contain an appreciable amount of ungelatinizec
starch granules The rice grains are then 70 compressed by passing the
same through rolls spaced so as to reduce the grains tc about 70 ',,
of their thickneses before compression as described in detail in
Examples I and 11 above The rice is then returned 75 to the 80 gallon
autoclave and steamed for an additional 5-10 minutes to render the
same completely gelatinized throughout.
after which it is removed from the autoclave and dried to a stable
moisture content of 80 about 10-14 ', using the drying condition
described in Example 1 The density of this product is 0 50-0 70 g /cc.
I will be evident that at any appropriate stage in the process the
rice grains can be 85 washed with water or solvent extracted te
decrease their fat content and thereby decrease any problemn of
rancidificazion thamight exist Also any suitable antioxidant catn be
added if desired One very eff-90 ective method of eliminating any
possibility of a rancidity problem is to soak the rice il.
hot water, say, at 175 '-30 n F for 5-10 minutes This may be employed
at any stage of the process, but it is preferred that 95 it should
follow the preliminary soaking step which is employed in many of the
embodiments of the invention described above.
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* GB784866 (A)
Description: GB784866 (A) ? 1957-10-16
Improvements in and relating to electric circuit breakers

A high quality text as facsimile in your desired language may be available
amongst the following family members:
US2813951 (A)
US2813951 (A) less
__ 784,866 Date of Application and Filing Complete b 7 i $&' Date of
Applicatio Specification: Sept16, 1954 No 26877154.
y Application made in United States of America on Oct16, 1953.
Index at Acceptance: Class 38 ( 5), Bl L( 2 A: 5: 7 A 2: 7 86: 13), Bl
NID, International Classification:-HO In H 02 c B 2 (A 5 A 2: B 3: Bl
O: Bl I: C 6 X: C 8 B).
COMPLETE SPECIFICA Ti ON Improvements in and relating to Electric
Circuit Breakers.
We, IGRANIC ELECTRIC COMPANY LIMITED a British Company, of Elstow
Road, Bedford, in the County of Bedford, do hereby declare the
invention, for which we pray that a patent may be granted to us, and
the method by which it is to be performed, to be particularly
described in and by the following statement: -
This invention relates to electric circuit breakers, particularly
small circuit breakers adapted for use as motor starters.
The invention seeks to provide a simple, reliable and inexpensive
circuit breaker of this character.
A further object is the provision of a circuit breaker which is easy
to assemble, requires a relatively small number of working parts, and
is fully protected against deleterious effects from sparking and
external dust and dirt particles.
Other objects and advantages of the invention will appear hereinafter.
The invention consists broadly of an electric circuit breaker having a
movable contact mounted on and movable with an insulating contact
carrier and constantly biased towards closed circuit position, an

overcentre spring action manually operable to one position to overcome
said bias and move said contact carrier and contact to open circuit
position, and manually operable to another position to permit said
contact carrier and contact to move to closed circuit position under
said bias, current responsive means for moving said contact carrier
and contact to open circuit position in opposition to said bias,
independently of said overcentre spring action, and a housing for said
spring action, said housing having a guide for said contact carrier.
A preferred circuit breaker according to the invention has the
following general characteristics: the movable contact carrying
bridging members are loosely mounted 43 on an insulating contact
carrier which is slidably guided in the base and cover forming the
circuit breaker housing Such members are spring biased toward closed
circuk and with the contact carrier move back and forth in a path
substantially perpendicular 556 to the dividing plane between cover
and base This facilitates assembly of the circuit breaker The contact
carrier is moved toward the cover to open the normally closed contacts
by a manually controlled 5 overcentre spring action carried in the
base.
This action is installed in the base by the simple expedient of
axially sliding its main pivot into a bearing in the base while such
action is momentarily held in place The 60 action includes a contact
operating lever which engages with the contact carrier to move it to
opened position Such lever has an overload bar which in overload
conditions is engageable by an overload lock and 65 reset lever also
included in such action.
These levers, a spring support and a manually operated lever are all
mounted on the same pin in such action While there is a slight
tolerance built into the mechanism 70 to provide for wear of the
contacts, this is not sufficient to impart a hammer blow in the
opening of the contacts Instead the over-centre spring action imparts
a positive and instantaneous opening to the contacts 75 without the
necessity of damaging hammer blows which soon wear and break down such
small lightly constructed circuit breakers The base and the cover
completely enclose the contacts and all operating mem 80 bers, except
the handle of the manually operated lever, to protect them from dust
and dirt and to keep harmful sparking fully shielded.
For a more detail description of the said 8 $ preferred circuit
breaker reference should be made to the following description of a
specific embodiment read in connection with the accompanying drawings,
in which:
Fig 1 is a top plan view of a circuit 9 784,866 breaker embodying the
present invention with the manually operated lever in "offposition;
Fig 2 is a sectional view taken on the ine 2-2 of Fig 1; Fig 3 is a

sectional view taken on the line 2-2 of Fig 1 showing the parts as
positioned with the manually operated lever in "on" position; Fig 4 is
a sectional view taken on the line 2-2 of Fig I with the parts shown
in the osition assumed when the contacts have been opened by the
operation of the overload mechanism; Fig 5 is a sectional view taken
on the line 5-5 of Fig 3; Fig 6 is a sectional view taken on the line
6-6 of Fig 3; Fig 7 is a sectional view taken on the line 207-7 of Fig
5; Fig 8 is a sectional view taken on the line 8-8 of Fig 5; and Fig 9
is an exploded prospective view of the circuit breaker shown in Figs
1-8 (incl).
The circuit breaker illustrated in the drawings is a multiple pole
starter rated at approximately 1 horsepower, single phase on 115 and
230 volts Completely assembled it is approximately 1 inches wide, 21
inches 301 long and 2 inches high Such small circuit breaker has a
base 10 and a cover 12 formed of molded insulating material which are
secured to provide a housing for the complete circuit breaker
operating mechanism except the handle of the manually operated lever
On a flat portion of the base 10 facing the cover 12 there are mounted
fixed contacts 14 into the threaded supports of which are threaded
exterior ter4 Opinal screws 16 Between these contacts is a groove 18
for guiding the contact carrier.
Slots 20 transverse to such groove guide the finger of the contact
operating lever A projection 22 on the base 10 houses the 45thermal
release assembly A rectangular hole 24 accommodates the handle of the
manually operated lever and provides shoulders limiting the extreme
movements of such handle The overcentre spring action is held in the
base 10 during assembly of the circuit breaker by having an extending
end of the pivot of such action project into a bearing 26 in such base
Opposite this bearing is a cylindrical groove 27 which co-operates
with a similar cylinder groove in the cover to form the other bearing
for such pin.
The cover 12 has a recess 28 which accommodates the swinging elements
of the overcentre spring action At the bottom of this recess is a
groove 30 which guides the end of an overload lever The right hand w
all of such recess has a semi-cylindrical groove 32 (see Figs 4 and 8)
which pro-ides an abutment for the spring of the overcentre spring
action Adjacent to the recess 28 are a pair of spaced recesses 34 (see
Figs 6 and 7) terminating in cylindrical wells 36 which provide
operating space for the contact bridging members and their compression
springs Slots 38 co-operating 70 with the grooves 18 in tile base 10
provide the complete guide for the contact carrier bar A
semi-cylindrical bearing 40 in the cover 12 (see Fig 5) co-operates
with the semi-cylindrical bearing 27 in the base 1075 to form the
outer bearing for the main pivot of the overcentre spring action.

The movable contacts of the circuit breaker are mounted on a pair of
bridges 42 apertured loosely to slide on tongues 4480 on a contact
carrier 46 The carrier 46 is made of insulating material such as
melamine and is slidably guided in the groove i 8 and slots 38
simultaneously to mo-ve the bridges 42 in the recesses 34 with the
con-85 tacts thereon in alignment with respective pairs of the fixed
contacts 14 The bridges 42 are continuously urged toward the closed
circuit position shown in Figs 3, 6 and 7 by compression springs 48 It
is relatixely 90 simple to assemble the bridges 42, carrier 46 and
springs 48 The springs 48 are seated in the wells 36 of the cover The
bridges 42 are placed on the tongues 44 and the contact carrier 46
fitted in the grooves 95 18 of the base 10 When the cover 12 is placed
on the base i 0, the springs 48 will be properly compressed Tihe
contact carrier -46 has a centrally located slot 50 which engages a
giner on the coi;at operating 100 lever To aid in effecting its
movenent towa d circvit opned positicn Thb o vcrcentre spring a tio
intcltdes a manually cacrat d eet 52 to which is pivoted by a single
main pivot 74 a sprin 105 suport 70, a contact operating lever 82 and
an overload and reset lever 90 An overcentre spring 76 e:te-nds beweel
the brid Be of the spring support 70 and a spring yoke 62 pivoted to
the manually operated lever I 10 52 The manually operated lever 52 is
made of insulating material and has a hand engageable finger which in
the assembled condition projects outwardly of the lousing through the
hole 24 A pair of spaced l S shoulders 54 alternati rely en-ae the en
of hole 24 to establish the "off" and "on" position of the lever 52 A
pair of trunnions 56 with bearings 58 therein are saced by a groove 60
The latter slidably guides 120 the spring yoke 62 pivoted to the lever
52 by a pin 64 fitting in an elongated bearing 66 in the lever 52 and
passing through a hole 68 in such spring yoke The spring support 70 is
U-shaped and has a connect 125 ing bridge and a pair of legs
terminating in apertured ends 72 These ends straddle the trunnions 56
with the apertures aligned with bearings 58 and mounted on the main
pivot 74 The tension spring 76 has one end 130 784,866 anchored to the
bridge of support 70 and its other end engaged in a hole 78 in the
yoke 62 This yoke has an arcuate slot 80 fitting over the pin 74 which
permits it to swing about the pin 64 without interfering with the main
pivot 74 Such linkage will cause the spring support 70 to move back
and forth between its limit position of Fig.
2 and its limit position of Fig 3 upon swinging the lever 52 back and
forth between its open circuit position of Fig 2 and its closed
circuit position of Fig 3 Such motion after dead centre is reached is
very rapid.
In normal operation the motion of the spring support 70 is transmitted
to the contact carrier 46 by the contact operating lever 82 This lever

has a pair of supporting legs straddling the spring support 70 and 2 S
pivoted on the main pivot 74 Such contact operating lever 82 has an
extending finger 84 slidable in the slots 20 and seated in the slot 50
of the contact carrier 46 The bridge of lever 9 has an arcuate recess
86 which fits around the spring 76 to permit the clockwise edges of
the bridge to be engaged by the legs of the spring support 70 in the
normally operating "off" position of the circuit breaker of Fig 2 The
contact operating lever 82 also has an overload bar ,8 which is
engaged by the overload and reset lever 90 when the latter is released
upon an overload.
The overload and reset lever 90 has a main bridge with spaced
supporting leas 92 straddling the contact operating lever 82 and
pivoted on the main pivot 74 The lever 90 also has a spring anchor 94
with an outer supporting leg 96 also pivoted on the main pivot 74 A
tensioned overload spring 98 extends from the anchor 94 to a pin 100
secured in the base 10 A locking arm 102 formed as part of the lever
90 has a spring finger 104 normally engaged with a ratchet 106 of a
thermal release assembly 108.
Such -assembly is welr known The ratchet 106 is normally held against
rotation until the heater coil, connected to a terminal 110 and the
adjacent terminal 16, melts the eutectic solder upon occurrence of an
overload The ratchet 106 will then rotate and release the overload and
reset lever 90 which will, under influence of spring 98, operate to
open the circuit The terminal 110 is carried in a plate 112 to which
is threadedly fitted a terminal 114 for external connection.
To assemble the overcentre spring action, the spring yoke 62 is placed
in the groove and pin 64 inserted in bearing 66 through hole 68 Then
the spring 76 is secured to the anchor 78 The spring support 70,
contact operating lever 82 and overload and reset lever 90 are then
fitted over the trunnions 56 and the main pivot 74 inserted 65through
them and the bearings 58 until its inner end (left as viewed in Fig 9)
is flush with the inner of the legs 92 The spring 76 is then connected
to the support 70 The action is assembled as a unit into the base with
the handle of the lever'52 project 70 ing out of hole 24 The main
pivot 74 is then moved inwardly, so that its inner end slides into the
bearing 26 thus holding the action in place After the contact bar 46
and spring 98 are assembled in the base 10,75 the cover 12, with
bridges 42 and sorings 48 in place, is placed on the base 10 and
secured by screws 116 which are threaded into mounting strips 118.
Starting with the circuit breaker in the 80 "off" position, shown in
Figs I and 2 assume that the handle of the operating lever 52 is swung
from the "off" position to the "on" position shown in Fin 3 During the
first part of such movement the contact 85 operating lever 82 holds
the s Wring support 70 in the position shown in Fig 2 As the pin 64

moves clockwise about the main pivot 74, such pin pivot and anchoring
hole 78 approach a position of alignment with 90 the central axis of
spring 76 Before such alignment position is reached the force exerted
by springs 48 is sufficient to overcome the then opposing force of
spring 76, and movement of the contact carrier toward 95 closed
position results in the forced movement of lever 70 thr Jugh the
aforementioned aligned position to its opposite extreme position shown
in Fig 3 During the aforementioned movement pin 64 moves to en too
gage with the other end of slot 66 in lever 52.
Starting with the parts shown in the "on" position of Fig 3, movement
of operating lever 52 in the counter-clockwise direction 105 to the
"off" position shown in Fin 2 will cause pin 64, pivot 74 and hole 78
to be brought toward the aforementioned alignment position During such
movement pin 64 moves from the right end to the left end 110 of slot
66 thereby providing a slight lost motion action, offsetting any
retarding tendency caused by the speed or manner of movement of lever
52 Spring support 70 is held against the groove 32 as shown in 115 Fig
3 during the initial part of such movement As the alignment position
is passed, the tension of the spring 76 moves spring support 70
rapidly in the clockwise direction from such position, to the position
shown 120 in Fig 2 The legs of the spring support will contact the
bridge of operating lever 82 and swing it clockwise to the position
shown in Fig 2 with a rapid motion but without hammer action The
finger 84 in 125 stantly depresses the contact bar 46 with the
consequent opening of the contacts as the effective force of spring 76
is considerably greater than the combined effective force of springs
48 130 784,866 With the circuit breaker in the normall) "on" position
shown in Fig 3, an overloac will release the ratchet 106 and the
overload and reset lever 90 will instantly pivol under the influence
of spring 98 to the position shown in Fig 4 Its arm 102 will engage
the overload bar 88 and swing the contact operating lever 82 to the
circuit open position shown in Fig 4 This takes place without any
interference to or from the manually operated lever 52, the overcentre
spring 76, and the spring support 70 After the overload has been
removed and the solder in the thermal element hardened, the circuit
breaker may be reset This is accomplished by swinging the manually
operated lever 52 from the "on" position of Fig 4 to the "off"
position of Fig 2 This movement causes the left hand lower edge of
such lever to engage the bridge of the lever 90 and swing such lever
counter-clockwise to carry the arm 102 to the position shown in Fig 2,
so that the spring finger 104 will again engage with the ratchet 106
and hold such lever with energy stored in spring 98.
Lever 90 in so moving disengages from lever 82 and the latter
momentarily freed rotates a slight amount in the counter-clockwise

direction thereby permitting contact carrier 3046 to move a slight
amount toward contact closed position During the aforementioned
"resetting" operation, spring support 70 is caused to snap overcentre
to the position shown in Fig 2, and in so doing engages with lever 82
to drive the latter in the clockwise direction before it can move
freely any appreciable amount in the counter-clockwise direction.
It will be observed that because lever 90 can move lever 82, to
contact opening position independently of lever 52 and spring carrier
70, that the circuit breaker is of the "trip-free" type, that is to
say, the contacts cannot be closed by movement of lever 52 to "on"
position, following "resetting" operation of the latter if the thermal
element has not rehardened.
* Sitemap
* Accessibility
* Legal notice
* Terms of use
* 5.8.23.4; 93p
* GB784867 (A)
Description: GB784867 (A) ? 1957-10-16
Improvements in or relating to travelling-wave electron tubes
Date of Application and filing Complete Specification: Sept 23, 1954.
g W i rt i 9 No 27566/54.
Application made in United States of America on Sept 24, 1953.
Application made in United States of America on Oct 19, 1953.
Index at acceptance:-Classes 39 ( 1), D( 1 OD: 1 OF: 11: 16 A 1: 18 A:
40 F: 46 A); and 40 ( 8), WG.
International Classification:-H Olb, j.

Improvements in or relating to Travelling-Wave Electron Tubes We,
RAYTHEON MANUFACTURING COMPANY, a corporation organised under the laws
of the State of Delaware, United States of America, of Waltham, County
of Middlesex, Commonwealth of Massachusetts, United States of America,
do hereby declare the invention, for which we pray that a patent may
be granted to us, and the method by which it is to be performed, to be
particularly described in and by the following statement: -
This invention relates to a travelling-wave electron tube.
One of the commonly employed anode structures forming the signal wave
transmission network of a travelling-wave tube is a strapped solid
vane structure This anode structure includes an electrically
conductive supporting plate to which a plurality of equally spaced
substantially rectangular planar members or vanes, positioned
substantially normal to the supporting plate, are attached.
At points on the edges of alternate vanes near the free ends thereof
are connected two pairs of conductive straps which extend
longitudinally along the structure This anode structure is enclosed
within an evacuated envelope of a travelling-wave tube which includes
a negative electrode, a collector electrode, means for producing an
electron beam and necessary connections.
All other things being equal, it is desirable that the characteristic
impedance of a periodic anode network for use in a travelling-wave
tube amplifier or oscillator be as high as possible.
The characteristic impedance Zo normalized with respect to the
characteristic impedance Z, of each cavity or network section formed
between two adjacent anode vanes is a function of a design parameter a
For the strapped vane structure, xc is defined as coo Ls a = _ ( 1)
zoo where lr is the cutoff frequency lPrice 3 s 6 d l L, is the strap
inductance per network section Zo is the characteristic impedance of
the parallel conductor network section or cavity formed by two
adjacent vanes.
It is known that in the aforesaid prior structure it is not
practically feasible to increase the impedance by increasing a
indefinitely A value of a must be selected and maintained, for a
particular periodic delay network, which will permit that network to
transmit waves at all frequencies within the pass band at phase
velocities which are less than the phase velocity Vpx of the lower
cutoff or,, mode frequency.
The ratio of Z to Z O is a constant, for a given value of a and
wavelength In order to increase the characteristic impedance ZO,
therefore, it is necessary to increase Z also.
For the strapped vane network, Zo is given by S Zo=kh where s is the
spacing between vanes and h is the height of the vanes.
( 2) Since the separation of the vanes (i e, the pitch) determines the

velocity at cutoff and, hence, the velocity everywhere in the
operating range, the amount of separation is dictated by operating
voltage considerations It is undesirable to increase Zo by increasing
s since this increases the phase velocity and voltage of the amplifier
If h is reduced, on the other hand, the width of the vanes and the
electron beam is narrowed and it is difficult to obtain the desired
beam current.
According to the invention there is provided a travelling-wave
electron tube including a delay line having two ends between which
electromagnetic waves can travel on a route along said line but not
substantially on any other route, the line being adapted to propagate
electromagnetic waves and thereby produce an ultra-high frequency
field, the delay line com-
2 784,867 prising an electrically-conductive base and a plurality of
U-shaped electrical conductors which are arranged in a row along the
base and are each connected at both ends to the base so that said
conductors form with said base a series of delay line sections, the
tube further including means for producing a stream of electrons which
move in a path along the line but to one side of said delay line
sections so that there will be interaction between the electrons and
said field.
As compared with the conventional strapped vane network, the provision
of U-shaped conductive loops increases the impedance of the delay line
without changing the pitch or the height of the vanes.
In order to overcome the problem of heat dissipation resulting from
the smaller surface area of the vanes, the latter are preferably made
in the form of U-shaped tubular loops through which a cooling fluid
can be circulated Although the straps may be located externally or
internally near the ends of the loops, it is preferable to use a
single pair of spaced straps located near the centres of the loops The
decreased area of the opposing faces of adjacent loops can be achieved
by reducing the loop dimensions within limits compatable with physical
strength and efficient internal flow of cooling fluid.
A further improvement of this periodic delay network when used as an
anode in travellingwave tubes, may be effected by providing flat
surfaces on the outer surface of the loop cross arms, that is, along
the surface of the loop facing the electron stream.
From equations ( 1) and ( 2), it is evident that is the value of Z is
to increase and that of a is to remain constant, the strap inductance
L, or the cutoff frequency too must be increased Usually it is not
feasible to vary the cutoff frequency so that it is necessary to
increase the value of L O This may be accomplished in at least two
ways The number of straps may be reduced from four, as used in the
known periodic structures, for example, to a single pair of straps The

size of the straps may be decreased to achieve the desired increase in
L, In addition, the strap inductance may be increased by keeping the
straps as far away from the loops as possible except at the points of
connection In the case of linear straps, slotted portions may exist
therein over which the portion of the loop not connected thereto may
pass; the loops may also be bent to achieve the same result.
In a further construction, the shorted lines, which may be a half wave
length long at the lower cutoff frequency of the network, are made
with a triangular cross section which permits a high impedance circuit
to be maintained, as in the case of the interdigital delay line, while
providing the additional advantages of a more uniform direct current
electric field in the interaction space, a stronger radio frequency
field in the desired space harmonic, higher inductance of the strapped
coupling for a given strap size, and greater uniformity in the
manufacture of the circuit loops Moreover, by making the loops hollow,
the delay 70 network has advantages over the interdigital delay
structure in that it may be adapted for fluid cooling, thereby
permitting high thermal dissipation and high power capability.
Another construction involves an open wave 75 guide loaded at the open
face by a series of shorted transmission lines or loops of the type
previously described, each of which is substantially one half wave
length long at the upper cutoff wave length This loaded wave 80 guide
delay structure has been found to possess a higher impedance than that
of the strapped vane anode delay line of the first embodiment, with
resulting advantages in tube optics gain and efficiency Furthermore,
assembly of 85 the loaded wave guide structure is simpler than that of
the strapped vane structure, and the structural uniformity of the
loaded wave guide structure is superior to that of the strapped vane
structure This construction, 90 too, is amenable to fluid cooling and
consequently is capable of operation at relatively high power levels.
For a better understanding of the invention and to show how it may be
carried into effect, 95 the same will now be described with reference
to the accompanying drawings, in which:
Figures 1 and 2 are isometric views of two different periodic delay
networks, parts being broken away in each Figure for ease of illus 100
tration, Figure 3 is a longitudinal cross-sectional view of a
travelling-wave electron tube utilizing the period delay network of
Figure 1 as the anode, 105 Figure 4 (drawn in the inverted position
with respect to Figure 3) is a view corresponding to a part of Figure
3 and illustrating a modification of the periodic delay networks shown
in Figures 1 and 2, 110 Figure 5 shows diagrammatically a network
representing the equivalent circuit of the periodic delay network of
Figure 1, Figure 6 shows diagrammatically the equivalent circuit of a
single section of the net 115 Figures 7 to 9 are graphs illustrating

various characteristics of a periodic delay netFigure 10 is an
isometric view of a further 120 periodic delay network, part being
broken away for ease of illustration, Figure 11 is a detailed
isometric view showing a modification of the network shown in Figure
10, 125 Figure 12 is a cross-sectional view of a modified version of
the network shown in Figure 10, Figure 13 is an isometric view of a
further periodic delay network, part being broken 130 784,867 Instead
of resorting to an attenuative coating, the loops themselves may be
constructed of a material, such as iron, having a high attenuation
factor.
A pair of trough-shaped headers 20 and 21 70 are secured in
substantial alignment with the opposite ends of the network loops 14
and 14 ' to the under side of base 11, as by soldering, so as to form
a fluid-tight seal One end of each header is closed while the other
end is 75 connected to a fluid circulating pump (not shown) The fluid
is used for cooling the network and it passes along one header,
through each loop in parallel and back along the other header 80
Although the periodic delay network 10 has been shown as linear, it
should be understood that the network may also be circular to conform
to the usual practice in magnetron design.
In Fig 3, a travelling-wave tube amplifier 85 is shown which includes
as its anode the periodic network 10, previously described.
The structure serving as the anode of the travelling-wave amplifier
comprises a base 11 which forms one of the walls of an evacuated 90
envelope further including an oppositely disposed wall 27, end walls
28 and 29 and a pair of side walls, not shown Base 11 may be fastened
to the contiguous walls of the envelope by soldering or by means of
fastening 95 devices such as screws.
The inner conductor 31 of a coaxial input coupling device 30 extends
through an aperture 32 in the base 11 and is attached, as by
soldering, to one end of the first loop 14 a at 100 the input end of
the anode structure This loop, as well as the loop 14 N at the other
end of the structure, is solid as contrasted with the tubular loops in
between An output coupling device 40 is similarly attached to one end
of 105 the loop 14 N at the output end of the anode structure, as
shown in Fig 3 Positioned adjacent the input end of the anode 10 is a
cathode structure 35 having an electron emissive surface 36 The
cathode 110 structure 35 is supported by a hollow supporting cylinder
37 extending through an aperture in wall 27 of the tube envelope
Cylinder 37 surrounds a central conductor 38 which is connected to one
end of a heater coil, not shown, 115 positioned in thermal proximity
to the emissive surface 36.
An auxiliary electrode 44 is positioned substantially parallel to the
anode structure and spaced therefrom, as shown in Fig 3 120 Electrode

44 which is otherwise referred to as a ",sole," is trough-like and of
U-shaped cross-section, the bottom surface thereof being positioned
somewhat lower than the electron emissive surface 36 of the cathode
125 Sole 44 is supported relative to the remainder of the tube
envelope by means of a pair of supporting rods 46 rigidly attached to
the sole These rods are insulatedly supported with respect to wall 27
by means of metallic 130 away for ease of illustration, Figure 14 is a
cross-sectional view of the network shown in Figure 13, Figure 15 is a
detailed view of a portion of the network shown in Figure 13, Figure
16 is a cross-sectional view of a modified version of the network
shown in Figure 13, Figure 17 is a central longitudinal crosssectional
view of a travelling-wave tube incorporating a periodic delay network
as shown in Figure 10, Figure 18 is a central longitudinal
crosssectional view of a travelling-wave tube incorporating a periodic
delay network as shown in Figure 13, and Figure 19 illustrates a
cooling arrangement for a periodic delay network.
Referring now to the drawings, in Figure 1 a periodic delay network 10
includes an electrically conductive base 11 containing two rows of
aligned circular apertures 12 positioned adjacent opposite edges of
the base and extending clear through the same A plurality of
electrically conductive tubular U-shaped transmission loops 14 and 141
are disposed in a row along the base The pitch or spacing between
adjacent loops is preferably uniform throughout the length of the
structure The ends of each loop are inserted in oppositely disposed
apertures 12 in the base in a manner clearly shown in Fig 1.
A pair of spaced straps 15 and 15 ' extend along paths which pass near
the centres of the loop and they are attached to alternately arranged
loops 14 and 14 ', respectively These loops are preferably constructed
of straps of metal having a high thermal and electrical conductivity
Each of the straps 15, 151 is formed with a plurality of spaced
projecting portions 16, the spacing between centres of such portions
being substantially equal to the pitch of the loops 14 or the loop 14
' The portions of a strap between adjacent projecting portions will be
referred to as slotted portions The straps are connected at the
projecting portions, to the transmission loops, as by soldering In
order to couple together the odd numbered loops with one strap and the
even numbered loops with the other strap, the projecting portions of
one strap fall opposite the slotted portions of the other, as shown in
Fig 1 The straps 15 and 151 may, alternatively, be in the form of
loops of metal strip, as shown in Fig 2 The centre of each strap loop
of Fig 2 or the slotted portion of each of the straps of Fig 1, as the
case may be, is thus separated from the U-shaped loops 14 or 14 ', as
the case may be, by a relatively large amount, whereby a substantial
strap inductance is obtained.

Attenuation may be introduced into network 10 by means of a metallic
attenuating coating 18, such as graphite, deposited near the ends of
some of the transmission loops.
784,867 members 47 sealed, in turn, to ceramic seals 48 The latter are
each connected to an electrically conductive cylinder 49 which
surrounds rods 46 and is, in turn, fitted in a recess in wall 27.
Positioned beyond that end of sole 44 which is remote from the
cathode, and in substantial alignment with the sole is a collector
electrode 50 rigidly supported by means of a lead-in rod 51 extending
through an aperture in wall 27 and spaced from the wall Rod 51 is
supported relative to wall 27 by means of a conductive cup 52, a
ceramic cylinder 53 and a metallic cylinder 54 surrounding rod 51, the
parts being sealed together like the sole supporting devices
previously described.
A direct current electric field may be established between the anode
and the sole by connecting a source of direct current voltage, not
shown, therebetween The cathode is negative with respect to the anode
but may or may not be at the same potential as the sole.
A transverse magnetic field is produced in the space between the
periodic anode structure and the sole in a direction normal to the
electric field therebetween, that is to say, in a direction
perpendicular to the plane of the paper By proper adjustment of the
magnetic field, the electrons emitted from the cathode will be
directed along a path adjacent the loops of the anode structure
Interaction of the electron beam with a wave traversing the anode
structure will result in amplification within the travelling-wave
tube.
It is possible to eliminate the transverse magnetic field and to
operate the travellingwave tube as a non-magnetic amplifier.
The cathode-sole assembly shown in Fig 3 may be replaced by a
continuous cathode extending the length of the tube This is true
regardless of whether or not the tube utilizes a transverse magnetic
field.
An improvement in the periodic structure of Figs 1 to 3 is shown in
Fig 4 in which flat plates 60 are attached, as by brazing, each to the
outer edge of the cross arm of a corresponding transmission loop, that
is to say on that surface of the loop which is nearest the electron
stream These plates are substantially rectangular and may be
approximately the length of the loop cross arm The tubes may,
alternatively, be formed with flat surfaces instead of having flat
pieces attached thereto.
For example, the surface of the tubular loops facing the -electron
stream may be filed or machined down flat, provided, of course, that
the wall thickness of the loops is sufficiently large The composite

surface of the periodic structure formed by the several plates 60
which is presented to the interaction space of the travelling-wave
tube is substantially flat in the construction shown in Fig 4 rather
than a series of rounded surfaces, and the gap between adjacent plates
is quite small compared with the average distance between the rounded
surfaces of adjacent tubular loops of Figs 1 to 3 Since this composite
surface approaches a solid plane substantially equidistant at all
points from the sole of the travelling-wave tube, the direct current
electric field in the interaction space is comparatively uniform
Because of this uniform direct current field, a more uniform electron
beam is attained.
An analysis of the strapped loop periodic structure of Figs 1 to 3 may
be had by constructing a linear array of said loops which have been
straightened out, as schematically illustrated in Fig 5 The length of
the loops included between the two points of connection to base 11 is
designated as d while the distance of the straps from the ends of the
loop is designated as f The ratio of f to d, which is a feature of the
strap separation, is designated as k For example, if both straps were
located at the centre of the loops, the value of k would be 0 5.
A single network section is shown schematically in Fig 6 and may be
considered to be a parallel-plane shorted transmission line of
characteristic impedance Zen It is divided into two parallel paths by
the dotted line through point mn at which the strap 15 is connected to
loop 14 The impedances looking in both directions away from m are Z,
and Z The impedance Z between point m and point n, the point of
connection of strap 151 to loop 14 ', is equal to the parallel
combination of impedances Z, and Z 2, where and j Zc rn 2 'r Id A Z =j
Z c Pan _ 2 A LI-kd) A ( 3) ( 4) the impedance Z thus becomes j 7 C
ra,7 Ot Tkd Aran 2 ir f-kei) A tan 2,7 d t tan gff l-kd) A A ( 5) 105
The effect of the network design parameter z on the normalized
impedance of the Z.
periodic network of Fig 1, for a given wave length, normalized with
respect to the upper cutoff wave length A,, is shown in the graph 110
of Fig 7 The network impedance is increased as x is increased from 0 1
to 1 For example, at a normalized wave length of 09, the normalized
impedance increases from about 0 9 when =- 1 to approximately 2 7 115
when x = 1 This graph represents a periodic network having a value k=
0 4, as will be shown later The shape of the curves of Fig.
7 will be changed somewhat as the strap separation, or value k,
changes, as will be 120 784,867 held constant The curves of Fig 9
indicate that the impedance level of the system is 65 reduced when k
is reduced Since the value of k, as well as the value of a, affects
the shape of the curves, suitable values of k and a should be chosen
simultaneously in order to secure desirable network characteristics 70

Although the travelling-wave tube shown in Figure 3 is of linear
configuration, the principle of its construction can be applied to
other than linear travelling-wave tubes For example, a circular tube
may be used 75 Referring to Fig 10, a portion of a strapped loop
periodic relay structure 110 is shown which, like that shown in the
foregoing Figures 1 to 3, inclusive, consists of a plurality of
cavities or network sections formed by 80 adjacent U-shaped
transmission loops shorted at both ends by an electrically-conductive
member and having alternate loops interconnected by a pair of metal
straps In this case, however, the cross section of the loops 85 is
made substantially triangular, as shown in Figs 10 to 12.
The end portions 122 of each loop 112 and 1121 are inserted in
corresponding apertures 113 and 1131 in an electrically-conductive 90
base 111 and are secured thereto, as by brazing Since circular
apertures are readily obtainable by drilling holes in the base, the
end portions of the loops are preferably machined round It is
possible, of course, to 95 utilize triangular apertures in the base
plate or, in the event that fluid cooling is not desired, as in the
construction illustrated in Figure 10, to secure the ends of the loops
at the surface of the base 100 The first set of alternate loops are
interconnected by an electrically-conductive strap 114 while a second
set of alternate loops 112 ' are interconnected by a similar strap 114
'.
These straps may take the form shown in 105 Fig 10 in which
alternately disposed projecting portions 115 and 115 ' may be attached
to the under side of the corresponding loops, as by soldering
Alternatively, the straps may contain V-slots 117 into which the apex
of 110 the triangular loops may be inserted prior to soldering, as
shown in Fig 11.
The spacing of the straps 114 and 1141 partially determines the
characteristic impedance and velocity dispersion character 115 istics
of the network and the spacing selected will be governed by circuit
design considerations.
The reasons underlying the use of transmission loops of triangular
cross section will 120 now be stated As pointed out earlier, the
characteristic impedance Z of the strapped loop delay structure is
related to the characteristic impedance Z O of the cavity formed by
adjacent loops by a constant factor, at a given 125 wave length.
In order to increase Z and consequently the gain of a travelling-wave
amplifier utilizing evident from inspection of Fig 9, to be described
later.
The dispersion curve of the space harmonic of the travelling-wave
suitable for amplification, that is, the relationship between the wave
length and the phase velocity of the first harmonic of a wave

travelling along the periodic network 10 of the travelling-wave tube
of Fig 3 is shown in Fig 8 for various values of a The portion of the
dispersion curve representative of the component of the
travelling-wave suitable for operation of the travelling-wave tube as
an oscillator is not shown in Fig 8 but the two portions of the
dispersion curve representative of the fundamental and first space
harmonic are symmetrically located about a line passing VAT A, through
the origin ( = 0 and = 0) of the V A, curve and unity on the
normalized phase velocity axis and having a slope equal to the
reciprocal of twice the pitch of the periodic network.
As shown in Fig 8, the curves 81 and 82 for respective values of a of
0 1 and 0 2 are relatively flat over a wide range However, the
required phase velocity for most of the wave lengths in the pass band
is greater than that necessary for i-, mode oscillations so that
undesirable oscillations may be set up in the travelling-wave tube For
high values of a, for example for values of the order of 0 6 to 1, the
curves 86 to 90 are not flat over any substantial portion thereof and
the gain of an amplifier tube operating on these curves, even assuming
that oscillations will not occur, will vary considerably with
operating wave lengths.
For values of v in the range of 0 3 to 0 5, the curves are relatively
flat over a wide range of wave lengths, for example, between the
normalized wave lengths of approximately 75 and 95, as shown in curves
83 to 85 Hence, the degree of interaction between the electron beam
and the waves propagating along the anode structure, and consequently
the gain of the travelling-wave tube when used as an amplifier, remain
substantially constant over a wide band of frequencies when curves 83
to obtain In practice this means that the desired gain may be
accomplished over a wide band of frequencies using the same anode
voltage or the same magnetic field strength, if the tube utilizes a
transverse magnetic field.
A value of a equal to about 0 4 or 0 5 is satisfactory for the
periodic network represented in Fig 8.
As evidenced by equation ( 5), infra, the factor k of the strapped
loop periodic network has an effect upon the impedance level of the
network The effect of k on the impedance is shown in Fig 9 in which
graphs of normalized impedance versus normalized wave length for
various values of k from 0 1 to 0 5 are shown by curves 95 and 99,
respectively, when a is 784,867 6 784,867 this network as an anode, it
is necessary to increase the value of Z O A high impedance is also
desirable for a travelling-wave oscillator.
An expression for Ze, has been given earlier (equation 1) and it will
be seen that since a constant value of 7 is desirable, it is necessary
to increase the value of the strap inductance L, For the same pitch,

the average gap or distance between adjacent loops of triangular cross
section is considerably less than the average spacing in the case of
loops of circular or rectangular cross section The area of metallic
surfaces of the loop near the strap in the case of triangular loops is
decreased, that is, the effective length of the strap between adjacent
loops is increased As the spacing between adjacent loops is increased,
the inductance of the strap interconnecting the adjacent loops is
increased, for a given strap size, so that a higher impedance network
may be obtained The use of heavier straps is permitted as a result of
this increase in L.
In this connection, the strap' inductance may be further increased, as
pointed out in the first part of this specification, by keeping the
slotted portion 116 of the strap which is bridged by alternate loops
as far from the loop as possible The capacitance between a
triangular-section loop and a corresponding slotted portion of a strap
is less than that between a circular or rectangular-section loop and
the same slotted portion The inductance, which varies inversely as the
capacitance is consequently increased.
A further advantage of an anode periodic structure having
triangular-section loops is that a more uniform direct current
electric field in the interaction space of a travelling wave tube
utilizing the same may be obtained With loops of triangular cross
section, the composite surface of a periodic structure formed by the
several loops of the structure which is presented to the interaction
space of the travellingwave tube is substantially flat, rather than a
series of rounded surfaces as in the case of a structure using loops
of circular cross section.
Because the series of the loops facing the interaction space are flat,
the gap between adjacent network loops at said surface (in the average
gap) is considerably less than in the case of adjacent loops of
circular cross section In other words, the aforesaid composite surface
of the triangular loop network more nearly approaches a solid plane
substantially equdistant at all points from the cathode or sole of the
travelling wave tube Because of this comparative surface uniformity of
the triangular loop structure, the direct current electric field in
the interaction space is much more uniform than that obtainable when
the loops ofthe anode periodic structure are round.
Still another advantage of the anode structure using loops of
triangular cross section over structures using round loops is that the
space harmonic content of the electromagnetic wave in the interaction
space is made stronger.
A Fourier analysis of the radio frequency field between adjacent
network loops indicates that the amplitude of the space harmonics of
the field, relative to the fundamental, at a given 70 distance from

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