Year: 1894

page_text: Date of Application, 21st Dec., 1894
Complete Specification Left, 18th Mar., 1895-Accepted, 11th May, 1895
A communication by THE ACTIEN-GESELLSCHAFT FÜR FERNSPRECHPATENTE,
of 17, Niederwallstrasse, Berlin, in the Empire of Germany.
I WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., of The Agency for
Foreign Patent Solicitors, 6, Lord Street, Liverpool, and 6, Bank Street,
Manchester, both in the County of Lancaster, and 31, High Holborn, in the
County of Middlesex, Civil Engineer, do hereby declare the nature of this invention
to be as follows:-
1
The invention relates to improvements in telephones; the purpose of these
improvements being, first, to considerably simplify the construction of the apparatus,
and further, principally, to considerably increase their efficiency and sensibility,
the great advantage of which is particularly conspicuous in communicating to
considerable distances.
In the usual and well-known connection between the receiver and the induction-
coil of a micro-telephone, the connection of the receiver in series with the secondary
coil is objectionable, because the arriving currents, which are to be transformed into
sounding vibrations by the receiver, must pass through this secondary coil, the
resistance of which is so great as to greatly diminish the currents, before they
become effective within the receiver.
In transmitting telephonic communications, the current inducted in the induction
coil of the apparatus is again considerably reduced by the resistance of the receiver,
at the transmitting station, in addition to the inactive induction-coil of the receiving
station.
By connecting the receiver in parallel to the secondary coil, which connection has
also been employed, the loss referred to is partially avoided because the connection
in parallel greatly diminishes the resistance of the whole arrangement. But by
connecting the receiver in parallel another loss is noticeable as the current is
divided in such a manner, that the arriving currents not only flow through the
receiver, but partially also through the secondary coil, whereby the microphonic
currents which are naturally of only small intensity, are subject to a division, and
though an advantage is obtained by reducing the resistance, it is lost again in the
receiver by the said division of the current.
The improved system which forms the object of this invention principally
consists in uniting into one, both the receiver and the induction coil, whereby the
inconveniences before described are overcome. A polarized induction coil with an
iron diaphragm, constitutes the receiver and the secondary coil is connected in the
telephonic circuit. The microphone currents passing through the primary coil
induce currents in the secondary coil, which may be directly transformed into
sounding vibrations by another apparatus of similar construction, without
encountering other resistance than that of the line conductors.
This arrangement may be modified by the two coils being placed side by side,
instead of one over another. The primary coil which, during telephonic communi-
cation, receives current from the microphone, simultaneously acts to produce the
magnetism required in the receiver.
This improved system may be applied to telephonic apparatus of the usual
shape, having single-poled wire-cores. In the Bell-telephone shaped receiver the

page_text: magnetism produced by the primary coil, if microphones of small resistance are
employed, is even more intense than is required.
This improved system may also be applied to telephonic apparatus with double-
poled sheet-iron cores. In this construction, another peculiar effect is obtained,
which increases the intensity of the secondary currents. This effect is caused by
the fact, that, simultaneously with the undulations of the microphone-current,
within the primary circuit, the diaphragm is caused to vibrate, whereby, owing to
the coincidence of the vibrations of the microphone, the magnetic resistance within
the iron circuit is reduced.
The induced currents produced in the secondary circuit meet a strong, nearly
closed magnetic field, formed by the primary coil.
The construction of the double-poled type may be easily effected in such a
manner, that the poles are concentrically placed, the outer pole serving as a jacket
for the magnetizing coil which surrounds the inner pole. Both poles may be
conveniently constructed of laminated iron.
Dated this 20th day of December 1894
A communication by THE ACTIEN GESELLSCHAFT für FERNSPRECHPATENTE,
of 17, Niederwallstrasse, Berlin, in the Empire of Germany.
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., of The Agency for
Foreign Patent Solicitors, 6, Lord Street, Liverpool and 6, Bank Street,
Manchester, both in the County of Lancaster, and 31 High Holborn in the
County of Middlesex, Civil Engineer, do hereby declare the nature of this invention
and in what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement :—
The invention relates to improvements in telephones; the purpose of these
improvements being, first, to considerably simplify the construction of the apparatus,
and further, principally, to considerably increase their efficiency and sensibility,
the great advantage of which is particularly conspicuous in communicating to
considerable distances.
To explain the system of this invention, reference will be had to the accompanying
drawings, in which
Figure 1 is a diagrammatical view showing the receiver of a micro-telephonic
apparatus of usual construction connected in series with the secondary coil of the
induction coil ;
Figure 2 is a diagrammatical view showing the usual receiver in a micro-
telephonic apparatus with the secondary coil of the induction coil in parallel
connection;
Figure is a diagram showing the improved system of this invention;
Figure 4 is a diagram showing a modification in the arrangement of the coils in
the same;
Figures 5 and 6 illustrate two forms of telephonic receivers with single-poled
wire-cores, constructed according to this invention;
Figures 7 and 8 illustrate a telephonic receiver constructed according to this
invention, with a double-poled sheet-iron core, Figure 7 being a front elevation and
Figure 8 a section drawn to line a-b of Figure 7; and
Figure 9 a diagrammatical view of the connections of the telephonic apparatus,
showing the general arrangement of the plant.

page_text: In the usual and well-known connection between the receiver and the induction-
coil of a micro-telephone, the connection of the receiver T in series with the
secondary coils s, as shown in Figure 1, is objectionable, because the arriving
currents at I. L', which are to be transformed into sounding vibrations by the
receiver T, must pass through this secondary coil ss, the resistance of which
is so great as to greatly diminish the currents, before they become effective within
the receiver.
In transmitting telephonic communications, the current induced in the induction
coil ss, of the apparatus is again considerably reduced by the resistance of the
receiver T, at the transmitting station, in addition to the inactive induction-coil of
the receiving station.
By connecting the receiver T in parallel to the secondary coil, ss, as shown in
Figure 2, which connection has also been employed, the loss referred to is partially
avoided because the connection in parallel greatly diminishes the resistance of the
whole arrangement. But by connecting the receiver in parallel another loss is
noticeable as the current is divided in such a manner, that the arriving currents
at L L not only flow through the receiver T, but partially also through the
secondary coil, whereby the microphonic currents which are naturally of only small
intensity, are subject to a division, and though an advantage is obtained by
reducing the resistance, it is lost again in the receiver by the said division of the
current.
The improved system which forms the object of this invention principally
consists in uniting into one, both the receiver and the induction coil, whereby the
inconveniences before described are overcome. The system is illustrated by
Figure 3, wherein a polarized induction coil with an iron diaphragm, constitutes the
receiver and the secondary coils is connected in the telephonic circuit. The
microphone currents passing through the primary coil p p induce currents in
the secondary coil ss, which may be directly transformed into sounding vibrations
by another apparatus of similar construction, without encountering other resistance
than that of the line conductors.
This arrangement may be modified as shown in Figure 4, by the two coils being
placed side by side, instead of one over another. The primary coil p, which, during
telephonic communication, receives current from the microphone, simultaneously
acts to produce the maguetism required in the receiver.
This improved system may, as shown in Figures 5 and 6, be applied to telephonic
apparatus of the usual shape, having single-poled wire-cores, 1, 2, 3, being the
terminals of the improved coils. In the Bell-telephone shaped receiver (Figure 6)
the magnetism produced by the primary coil, if microphones of small resistance are
employed, is even more intense than is required.
This improved system may also, as shown in Figures 7 and 8, be applied to
telephonic apparatus with double-poled sheet-iron cores. In this construction,
another peculiar effect is obtained, which increases the intensity of the secondary
currents. This effect is caused by the fact, that, simultaneously with the undulations
of the microphone-current, within the primary circuit o p, Figure 8, the diaphragm
is caused to vibrate in the direction of the arrow whereby, owing to the coincidence
of the vibrations of the inicrophone, the magnetic resistance within the iron circuit
is reduced.
The induced currents produced in the secondary circuit as meet a strong, nearly
closed magnetic field, formed by the primary coil.
The construction of the double-poled type may be easily effected in such a
manner, that the poles are concentrically placed, the outer pole serving as a jacket
for the magnetizing coil which surrounds the inner pule. Both poles may be
conveniently constructed of laminated iron.
Figure 9 is a general plan showing the connection of a telephone line installed
according to this system, the great simplicity of the whole arrangement being
clearly visible.

page_text: Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, as communicated to me by my
foreign correspondents, I declare that what I claim is :-
1. A micro-telephonic apparatus, in which that part which transforms the current
of the microphonic circuit, also serves as that part of the receiver, which receives
the current, substantially as and for the purpose set forth.
2. A micro-telephonic apparatus, in which that part which transforms the current
of the microphonic circuit, also serves as that part of the receiver, which receives
the current, while the strong coil of the microphonic circuit, through which the
microphonic current flows, serves to produce the magnetism in the receiver, or to
increase said magnetism, where permanent magnets are employed, substantially as
and for the purpose set forth.
3. A micro-telephonic apparatus having a polarized iron circuit nearly closed by
an iron diaphragm and in which that part, which transforms the current of the
microphonic circuit, equally serves as the receiving part of the receiver, while the
primary coil of the microphonic circuit causes the iron diaphragm to vibrate
synchronically with the vibrations of the microphone, thus causing the magnetic
resistance in the iron to change simultaneously with the electric resistance, whereby
the intensity of the secondary circuits is increased, substantially as set forth.
Dated this 16th day of March 1895.