U.S. patent number 3,633,588 [Application Number 04/841,517] was granted by the patent office on 1972-01-11 for high-capacitance, low-inductance electrode for a short-wave therapeutic device.
This patent grant is currently assigned to Siemens Aktiengesellschaft. Invention is credited to Werner Haas.
United States Patent |
3,633,588 |
Haas |
January 11, 1972 |
HIGH-CAPACITANCE, LOW-INDUCTANCE ELECTRODE FOR A SHORT-WAVE
THERAPEUTIC DEVICE
Abstract
A short-wave therapeutic device is shown for the frequency range
of about 10 MHz. to 100 MHz. (3 to 30m. wavelength) which has an
inductivity and a capacity of such size that it is adequately in
resonance with the frequency used. The device is particularly
characterized by the use of a framelike-shaped armature made of a
wide strip to provide inductivity which is as small as possible
while making the capacity as large as possible by closely
superposing the end portions of the armature.
Inventors: |
Haas; Werner (Erlangen,
DT) |
Assignee: |
Siemens Aktiengesellschaft
(Erlangen, DT)
|
Family
ID: |
5698074 |
Appl.
No.: |
04/841,517 |
Filed: |
July 14, 1969 |
Foreign Application Priority Data
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Jul 13, 1968 [DT] |
|
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P 17 64 666.1 |
|
Current U.S.
Class: |
607/155 |
Current CPC
Class: |
A61N
1/06 (20130101); A61N 1/40 (20130101) |
Current International
Class: |
A61N
1/06 (20060101); A61N 1/40 (20060101); A61n
001/40 () |
Field of
Search: |
;128/404,405,413,422 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
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|
|
954,128 |
|
Apr 1964 |
|
GB |
|
718,637 |
|
Mar 1942 |
|
DD |
|
1,110,773 |
|
Jul 1961 |
|
DT |
|
Primary Examiner: Kamm; William E.
Claims
I claim:
1. In a short wave therapeutic device, an electrode having the
shape of at least one framelike armature consisting of a wide strip
and having closely superposed end portions to provide large
capacity and small inductivity.
2. An electrode in accordance with claim 1, wherein the armature is
shaped to substantially completely enclose a hollow space.
3. An electrode in accordance with claim 2, comprising a plurality
of armatures, said armatures being located mechanically one next to
the other, and means interconnecting said armatures electrically in
parallel.
4. An electrode in accordance with claim 3, wherein parts of the
armatures which touch each other are replaced by a part common to
two armatures.
5. An electrode in accordance with claim 3, wherein each end of an
armature consists of two plates equal in size and shape, whereby
the plates of one end are enclosed by the plates of the other end
and whereby the plates of both ends extend parallel to and opposite
each other.
Description
This invention relates to a device for producing short wave therapy
such as is required, for example, in conventional diathermy
applications, the removal of adipose tissue, and other applications
which are well known in the art.
In the conventional device utilized for this purpose there is
generally provided a short wave radiation generator which has a
frequency of about 10 to 100 megacycles and a wavelength of about 3
to 30 m., a treatment electrode, and means for coupling the
generator to the treatment electrode. Treatment electrodes have
been generally of two types: the condenser electrodes and the
loading coil section electrodes. Condenser electrodes are utilized
in connection with the so-called condenser field method in which
the person to be treated is placed in the high-frequency electrical
field between insulated electrodes and thus acts as a dissipative
dielectric. When the loading coil method is used, the person to be
treated is placed in the high-frequency magnetic field of a
coil.
Conventionally, when either of these methods is used, the open
circuit impedance of either the condenser electrode or the loading
coil electrode should not deviate too much from one another if both
types of electrodes are to be utilized in connection with the same
generator, since otherwise severe damage would occur to the
generator. Conventionally, however, it was quite easy to tune
loading coil section electrodes to resonance.
Therefore, conventionally, the art with respect to loading coil
section electrodes has not developed during the past years. It has
been conventionally believed that the short wave generators would
have to be equipped with tuning devices so that, upon change of the
load which was represented by the body disposed in operative
relationship with treatment electrodes, the energy transferred to
the body would be transferred optimally and any slow frequency
drift of the generator would again have to be equalized. The
conventionally automatic tuning device which has been developed for
this purpose is expensive, noisy, trouble prone and, furthermore, a
discrete time period is required until the tuning to resonance is
accomplished. Because of the continuous drift around the point of
resonance, in any automatic tuning device of this type, a uniform
transfer of energy to the body under treatment will not be
accomplished, which can cause problems such as insufficient heating
or burning.
The present loading coil section electrodes suffer from a further
disadvantage in that the fields which are created by such
electrodes will fade relatively rapidly so that a field of
sufficient strength will be present only within the immediate
proximity of the electrode. However, if the body under treatment is
brought into the immediate proximity of the electrode, the
electrical fields at this location are very large and heating of
the adipose tissue is too great. In order to produce a depth effect
which has been achieved in short wave lengths through the use of
open cavity resonators, a structure of this invention is required
and the conventional loading coil section electrodes will not be
satisfactory. The use of cavity resonators for the purposes of
invention is medically impossible because such cavity resonators
would have to be of size to correspond to an integral multiple of
half the operating wavelength, which, in the case of conventional
treatment wavelengths, would be 1.50 to 15 m. In addition, the
production of high-frequency energy in such wavelengths is
considerably more expensive and the transmission loss is
considerably greater than the frequency wavelength of about 3 to 30
m. mentioned in this specification.
By means of apparatus of this invention, a device has been created
for short wave therapy within the frequency range of about 10
megacycles and 100 megacycles. This device is free from the
disadvantages of the preceding structures, is cheaper to
manufacture and is suitable for many different types of treatments
such as, e.g., treatment for larger or smaller sections of the
human body. The heat produced by this invention is well controlled
and a depth, if desired, can be easily produced.
The invention may be briefly described as constituting a treatment
electrode, which is connected to a short wave generator. The
electrode has an inductance and capacity of proper size so that, at
the frequency used, it will be almost exactly in resonance so that
the capacity will be as large as possible and the inductance as low
as possible.
This statement is adequate for technical treatment, since when
constructing the electrodes of this invention, large capacities can
be easily produced because, since the inductance is low, the
condensers carry a far lower voltage load. While the capacity of
the electrode can not be infinitely increased because the plate
distances can not be reduced to minimal size because of thermal
expansion and danger of breakdown, nevertheless relatively large
capacities can be produced. The dimensions of the electrodes can
not be made too large and the magnitude of the high-frequency
voltage used limits the increase of capacity. Also, the type of
connection between the transmission line and the electrode must be
carefully considered because losses will occur in this area as
well. However, with the use of this invention, and with air
condensers, capacities in the neighborhood of 50 to 1,000 pF can be
produced.
As a matter of theory of this invention, and while the inventor
does not wish to be bound thereby, it is believed that, when the
capacitive part of the electrode is increased and the inductive
part decreased, the current intensity in the electrode becomes far
greater. Therefore the magnetic field created within the electrode
for the treatment becomes much stronger and a great penetration in
depth is achieved. Furthermore, the considerable increase in
current intensity will not produce the large amount of power loss
involved in conventional electrodes.
The electrode of this invention is made in the form of a large area
armature. The applicant has demonstrated that, in the proximity of
the limits of an electrode of such form, the strong magnetic field
produced by high-current intensity is rather homogenous and
therefore the field intensity decreases rather slows with growing
distance from the electrode, therefore excellent depth penetration
is achieved. The shaping of the electrode as a large area armature
has the further effect that the magnetic lines of flux are
generally perpendicular to the body surface to be treated so that
the electrical lines of force will run tangentially to the surface
of the body. For this reason, the electrode is only slightly
detuned when it is brought near to a patient or the patient is
removed from its vicinity. Therefore it is possible to provide a
connection between the electrode and the connecting line to the
generator in which the generator will change the power emitted,
depending upon the distance between the electrode and the patient
because of the transformation of the effective resistance in the
undamped circuit but the frequency will remain essentially
constant. Therefore the electrode made in accordance with this
invention can be used without automatic tuning means operatively
connected to the generator and short wave apparatus made in
accordance with this invention can be manufactured at far lower
cost. While these devices would normally not be suitable for use
with condenser electrodes, the advantages of this invention makes
the condenser field method obsolete.
Furthermore, if the end faces of such an electrode are placed in
confronting relationship with one another, the electrodes can be
made small, thereby increasing their applicability for various
types of treatment.
The above constitutes a brief description of this invention and the
principal objects and advantages thereof. Other objects and
advantages of this invention will become apparent to the reader of
this specification as the description proceeds.
The invention will now be described by reference to the
accompanying drawings, which are made a part of this
specification.
FIG. 1 is a perspective view of a short wave therapeutic device
made in accordance with this invention;
FIG. 2 is a top perspective view of a treatment electrode made in
accordance with this invention;
FIG. 3 is a front perspective view of an alternative type of
treatment electrode made in accordance with this invention;
FIG. 4 is a fragmentary cross-sectional view of the treatment
electrode shown in FIG. 3 taken along lines IV--IV of FIG. 3;
FIG. 5 is a fragmentary perspective view of the form of treatment
electrode shown in FIG. 3 as seen from below;
FIG. 6 is an exploded perspective view of another form of treatment
electrode according to this invention;
FIG. 7 is a fragmentary cross-sectional view taken along lines
VII--VII of FIG. 6;
FIG. 8 is a fragmentary cross-sectional view, on an enlarged scale,
taken along lines VIII--VIII of FIG. 6;
FIG. 9 is a perspective view of a long field radiating system
electrode made in accordance with this invention;
FIG. 10 is a cross-sectional view taken along line X--X of FIG.
9.
The invention will now be further described by reference to the
accompanying drawings. In this connection, however, the reader is
cautioned to note that the specific forms of this invention, as
shown in the drawings herein, are for illustrative purposes and for
purposes of example only. Various changes and modifications could
obviously be made within the spirit and scope of this
invention.
The device of this invention includes a generator within housing 1,
a carrying arm 2 which is connected to electrode housing 3, and a
power cable 4 for connection between the generator and the
electrode.
The electrode, in its simplest form, is shown in FIG. 2 and
consists of a frame strip member which represents an armature. The
ends 5 of this frame member are designed to overlap one another so
that their surfaces run parallel to one another for some distance.
Thus the electrode has a large capacity while the relatively wide
strip has only a slight inductance. A dielectric .epsilon. can be
disposed between the overlapping surfaces. The connection of the
high-frequency feedline can be made to the electrode in any known
manner. The strip used is polished, in order to obtain as smooth a
surface as possible, and can be thin and flexible, so that the
electrode-- sheathed in flexible, insulating plastic material-- can
be fitted to the form of the parts of the body to be treated. The
electrode shown has the following dimensions: width of frame b=200
mm.; length of frame 1=450 mm.; width c or d, resp., of conductor
strip 40 ... 45 mm.; material: aluminum, copper or silver-plated
strips; dielectric: air (polyethylene, polystryene, or A1.sub.2
0.sub.3 ceramic). Thickness of strip: s 1 mm. In the example shown,
the width of the conductor strip is equal on all sides of the
frame; it could also be selected differentially, it being
particularly suitable, for obtaining a largely homogeneous magnetic
field, to give them dimensions in inverse ratio as the lengths of
the framesides, i.e., c1=bd.
In the electrode according to FIG. 3, the armature is formed by the
frame parts 6a, 7, 8, 9 and 6b. At its open side, facing the
viewer, the loop is adjusted to the form of the body by a concave
arch. At the rear side, the electrode ends in an insulating plate
10. The connection of the coaxial feed cable 11 is arranged at the
side of the frame 18. The outer conductor 12 is flanged to the side
of the frame 8 by means of a metal angle 13. The inner conductor
extends inside of the electrode and is connected there to the
upward running strip 15, which then passes to the metal plate 16.
This plate corresponds in its form and size to the metal plate 17
arranged opposite it, with which it is connected mechanically and
conductively by means of the two metallic screw connections 18, 19.
The metallic tongues 22 and 23 are attached by metal rivet 24 to
the conductor part 6a, by way of the metal distance plates 20, 21.
These tongues 22, 23 are so narrow that they fit well through the
metal screw connections 18, 19 without touching same (see FIG. 3)
and maintain a distance from them, so that no electrical flashovers
will occur. To improve the stability over the entire length of the
tongues, they are also connected by way of metal rivet 24a. So that
the distance between the two tongues will remain constant, the
plate 25, which is made of insulating material, is inserted between
them. Not shown for reasons of clarity, but existing in reality are
plastic strips which are arranged between the metal parts shown to
maintain distance between them. Shown are only the distance rings
25a made of plastic material, which permit an intelligible drawing,
in contrast to the plastic strips.
Welded on to the frame side 9 is the metal plate 26 extending in
parallel to the frame part 6b. This plate 26 extends to the broken
line 26a shown in FIG. 5, and its lateral limits are extended to
tongues 26b and 26c. The plate 26 and its tongues 26b, 26c,
respectively, are mechanically connected to the parts 25a, 25 and
6b by means of screw connections 27; in addition, these screw
connections also form a conductive connection between 6b and 26
(26b, 26c). The metal plate 28 has slots 28a and 28b, formed and
arranged in such a manner that the bolts of the screw connections
27 serve as guide pieces engaging the slots for displacing the
plate 28 in the direction of the double arrow 29. By tightening of
the screw connection 27 the plate is stopped in the desired
position and thus the magnitude of the electrode capacity is
adapted to the requirements. The electrode is sheathed in a plastic
housing as usual (not shown).
In this exemplified embodiment, the wide frame sides 6 through 9
form the small inductance, while the metal parts 6b and 26 or 28,
respectively, form the one side, and the tongues 22, 23 connected
to 6a form the other side of the large capacity. By means of plates
16, 17 the inner conductor of the coaxial feedline is capacitively
coupled to the tongues 22, 23 and thus to the electrode.
The particular characteristic according to the invention in this
manner of manufacture of a large capacity is that practically no
dielectric losses occur, because the only dielectric used (except
for air) consists of the plate 25, which is situated in the
(electrically) almost field-free space, because the condenser
tongues 22, 23 have equal potential and the electrical lines of
force between 22, 23 on the one hand, and 6b and 26, 28 on the
other hand, do not run through this dielectric 25.
It can be seen from FIG. 6 that the electrode with the plastic
housing 30 can be sheathed according to the vertical broken lines.
The housing 30 has slots 33 on the sides 31 and 32 for the emission
of heat. The housing is also provided with borings 34 and the
electrodes have the corresponding threaded holes 35, so that the
housing may be connected with the electrode by means of screws (not
shown).
The electrode consists essentially of straight 79' angular metal
plates which are arranged in a certain manner of space arrangement
to one another by means of insulating plastic plates or plastic
strips. The metal plates bear reference numbers 36 through 41;
45-47, 51, 58, 59, 64, 66 (FIG. 7), the insulating plastic plates
are marked with reference numbers 67, 69, 72, 74 (FIG. 7) and the
plastic strips, as distance pieces, bear the numbers 75-79 (FIG.
6), 79' (FIGS. 6, 7).
The square-shaped form of the electrode is provided by a repeatedly
angular metal plate, whose individual sections are marked 36-41. At
42, 43, 44 there are welded to this metal plate the plates 45, 46,
47. The plate section 40 ends at the broken line 48 (FIG. 6) and
the upper and lower limits of this plate are continued as tongues
49, 50. Along these tongues and movable in the direction of the
double arrow 54 there is arranged the metal plate 51, which has
slots 52 and 53. It can be fastened in the desired position by
means of screws 55, 56. The plate 46 is bent at 57 and ends with
the plate section 58. Plate 59 runs parallel to the plate section
58; it is bent at 60 and it is welded with its bent part to the
inner conductor of the coaxial connection 62 shaped as a square bar
61; the outer conductor 63 of the coaxial connection is screwed to
the metal plate section 36. Plate 45 continues in the plate section
64; in addition, the plate 45 is welded to plate 66 and 65. Thus,
the plates 58, 59; the plates 39, 64, 66 and 46, as well as 45, 41,
47 and 40 and 51, respectively, run parallel to one another. The
distance between the plates 41 and 47 is determined by plastic
plate 67, whereby 41 and 47 are connected by means of a metal rivet
68 passing through plate 67. The distance between plates 64 and 66
is determined by plastic plate 69, whereby 64 and 66 are connected
by means of metal rivet 70 through plate 69. Plate 58 is connected
to plastic plate 72 by means of rivet 71, and plate 59 is attached
to plastic plate 74 by means of rivet 73. The plastic strips 75-79,
79' serve to maintain the distance, determining the distances,
e.g., between the sections 45, 67, 49 (FIG. 8) and thus between the
plates 40 and 49/50, respectively, and 47; 45 and 41; 39 and 64; 46
and 66; 72 and 74. The dimensions of the distances can be seen from
the drawing, which shows an exemplified electrode on a scale of
abt. 1:2. The plastic strips-- just as the strip 79' visible in
FIGS. 6 and 7-- are also present at the bottom end of the
electrode, which is not visible, and which is covered by the
plastic plate 80; these strips are not shown for the sake of
clarity of the drawing.
In FIG. 8 there is shown an enlarged section along lines VIII--VIII
of FIG. 6, to promote better understanding. The screw 55 (56)
serves to firmly attach to one another the sections 45, 76, 67, 75,
49, 51 (in a similar manner, sections 46, 78, 69, 77, 39 are
attached to one another by means of screw 81 and nut 82), and in
addition, the bolts of the screws 55 (56) constitute the guides for
the tracks 52, 53.
The magnetic field created for the treatment exits at the opening
covered with plastic plate 80, as well as at the side opposite to
this opening, which is closed by the housing cover 83.
By means of the movable metal plate 51 the capacity of the
electrode can be adjusted within certain limits and in this manner
the electrode can be brought to resonance at a certain
frequency.
FIG. 9 shows an electrode according to the invention, built out of
two electrodes, with which long sections for treatment, e.g., the
musculus erector trunci, can be heated.
This electrode consists of two armatures; these are formed of two
repeatedly bent strips with sections 84, 85, 86, 87, 88 as well as
89, 90, 91, 92. The parts 85 and 90 can also be replaced by a
single piece of strip. The sections 88 and 94 are welded together
at 93. The passing strip 97 is welded to the sections 87 and 92 at
95 and 96. The strip formed by sections 88 and 94 is connected to
strip 97 by metal rivets 99, 100 with plastic plate 98 serving as
separator between them.
Section 84 ends at the broken line 101; the lateral limits of this
section 84 are extended into tongues 102, 103 to which are attached
the threaded separator bolts 104, 105. These bolts serve as guide
pieces for the slots 107, 108 provided in plate 106; in this
manner, plate 106 is movable along the tongues 102, 103 in the
direction of the double arrow 109 and can be fastened by means of
knurled nuts 110, 111; it serves to adjust the capacity.
112 and 113 designate two metal plates which are conductively
connected by means of screw connections 114, 115, with plastic
strips 116, 117 as separators. The plastic strips are again present
near the rear opening of the electrode, which is closed by means of
plastic plate 118, and are designated there as 116' and 117'.
Additional plastic strips, which determine the distance between the
sections 84, (89) and the strip 97, as well as the distance between
strip 94 and metal plate 119 bear the reference numbers 120 and
121, and 120' and 121', respectively (FIG. 10).
The plates 119 and 84 (89) are connected to each other by means of
the metal screw connections 122, 123 122', 123') and through
inserting the plastic strips 120, 121 (or 120', 121' at the rear
side of the electrode, respectively) as well as plastic plate 98
sufficient mechanical strength and secure maintenance of distance
are assured. Plate 112 has a metal vane 124 to the free end 125 of
which there is soldered the inner conductor 126, shaped as a square
rod, of the coaxial connection 127. The outer conductor 128 is
attached by means of screws 129 to the metal angle 130 mounted on
the plastic rear wall 118, which metal angle in turn establishes,
by means of screws 131, the electrical connection to the armatures,
i.e., directly to the sections 84, 89. The plates 112, 113 serve
for the capacitive coupling of the high frequency energy into the
electrode. It must be noted that the large electrode capacity
formed of the plates 97, 88 (94) and the plates 84 (89) and 119
contains air as dielectric which produces good stability and slight
losses, and that the plastic plate 98 is situated outside the
electrical field, thus is not causing any dielectric losses. No
electrical fields of the capacity penetrate outside, either. The
dimensions of this electrode are: length 1=80 cm.; depth t=abt. 10
cm.; width b=abt. 10 cm.; thickness of sheet = abt. 1 mm.,
thickness of plastic plates and strips = abt. 1 ... 3 mm., plastic
material = polystyrene or ceramic; sheet (and strip) =
aluminum.
As usual, the electrode is provided with a plastic housing (if
required, with vent holes).
As conductor material for the electrodes, metal sheet is used
preferably, but within the framework of the invention it can be
replaced by metallized plastic material, wire netting, or similar
material. It is also within the framework of the invention to place
several armatures, e.g., one inside another; in this or
corresponding modifications, also according to the invention,
higher inductance and greater electrode losses and lesser degree of
effectiveness would have to be accepted.
To summarize, the electrodes according to the invention differ from
those used today in shortwave therapy in that medically a greater
depth effect of heating is achieved with a simultaneous, better fat
removal. For this purpose, electromagnetic resonators are used,
which have an opening, where there is an electromagnetic field that
is advantageous for the treatment. The natural vibrations excited
have in comparison with the known electrodes lesser voltages, small
intensities of the electric fields, high currents, and large
intensities of the magnetic fields, while showing the same capacity
on the body to be treated. The electrodes are "low-resistance,"
i.e., the inductances of the circuits are small, the capacities
large. So that no great losses occur through the high-current
intensities, large current-conducting surfaces are used. Through
the large magnetic field in the opening and preferably
perpendicular to the body under treatment, and the minor electrical
field there, good fat removal is obtained. A great depth of
penetration of the heating is also achieved through the magnetic
field intensity dropping only very slowly with increasing distance
from the opening. The magnetic field of the electrodes used in
short wave therapy drops very rapidly, because the current
conductors, in comparison with the desired depth of penetration,
have only small cross-sectional areas.
In the electrodes described here, the current is therefore
conducted over wide areas in relation to the desired depth of
penetration. It was determined in tests that the depth, in which
there is still produced one-half of the amount of heat as in the
immediate vicinity of the electrode, corresponds approximately to
the width of the armature, measured across the loop. A further
measure towards increasing the depth of penetration consists in
that the area set up by the current path is large. From the point
of view of circuit organization, such a reaction is achieved of the
electrodes to the generator with a different connection to the
electrodes of the of the bodies treated, that the secondary circuit
and its frequency fine-tuning of the usual short wave devices
becomes superfluous. This behavior is caused by an input reflection
factor of the radiating system, which at variable load on the
electrodes by the body under treatment changes its amount very
greatly and its angle only slightly so that the allowable range of
the Rieke diagram is not exceeded. This favorable course of the
reflection factor is due to considerably more magnetic than
electrical energy being stored in the interaction space in front of
the opening level in the uncharged electrode. The favorable course
of the reflection factor can be adjusted through the selection of
the coupling element and the tuning.
The energy emitted by the generator can be fed to the electrodes
over a coaxial cable or a two-wire circuit. The feeding of power
over the coaxial cable has the advantage of lesser radiation and
secure operation, while power feeding over a two-wire circuit
permits the connection of the electrodes to existing devices, above
all when the electrodes are detuned in he capacitive range.
The coupling of the natural vibrations of the radiating system with
the fields of the circuit can be effected over electrical or
magnetic probes. At overcritical coupling of the electrodes to the
circuit, the length of the circuit is about .nu. /4+n.nu. /2 for
electrical probes, about .nu. /2+n.nu. /2 for magnetic probes
(n-integral); through suitable dimensioning of the probe and the
tuning, the length of the circuit may be somewhat varied by these
values. The opposite applies to subcritical coupling. If the
electrode is coupled overcritically to the circuit, there will be
emitted by the generator, given proper tuning, a maximum output for
large volumes to be treated; the opposite takes place with critical
or subcritical coupling. The preceding considerations have been
effected under the condition that the generator is open circuit
stable. In the case of a short circuit stable generator the reverse
conditions apply for length of cable and coupling.
The efficiency of the radiating system, i.e., the ratio between the
power output to the patient and the power consumed in the electrode
is large, because in the interaction space in front of the opening
level a relatively large part of the entire magnetic energy is
being stored, in contrast to the known inductive electrodes, in
which a great part of the magnetic energy is stored in the
immediate vicinity of the conductors, due to the comparatively
small conductor sections.
The large capacities for large quantities of stored energy required
for the electrodes are executed as large air condensers and a
static or dynamic shielding of the capacity is provided, i.e., the
electrical fields cannot get outside of the electrode. There are
used, plate condensers in a closed metal box or in a dynamically
shielded metal box.
The foregoing sets forth the manner in which the objects of this
invention are achieve.
* * * * *