Improvements in Telephones.
Year: 1898

page_text: COMPLETE SPECIFICATION.
Improvements in Telephones.
We, JOSEF EXNER, Architect, and CARL KRAFT, Electrician, both of No. 23, Calea
Dorobantilor, Bucharest, in the Kingdom of Roumania, 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:-
This invention relates to improvements in telephones with a relieved membrane
or diaphragm, comprising an arrangement according to which the inertia or
socalled self-induction of the membrane is first reduced to a minimum whereby all
vibrations are received in a very clear and distinct manner and likewise reproduced.
Further, owing to the peculiar compulsory concentration of the magnetic lines of
force through the centre of the membrane, the inductions in the coils are much
stronger so that the vibrations of the diaphragm are also much stronger and the
sounds thereby produced are distinctly audible.
The effect of the strong steel magnets which are used in connection with this tele-
phone is that the influence of the working currents of neighbouring conductors
or of other weak induction-currents caused by neighbouring conductors is too weak
for altering or influencing these steel magnets so that the disturbing by-sounds
in consequence of neighbouring wires are entirely avoided.
Referring to the accompanying drawing:-
Fig. 1 is a front elevation of a telephone made in accordance with this invention.
Fig. 2 is a section on line x-x of Fig. 1.
Fig. 3 is an elevation of the diaphragm of this improved telephone, and
Fig. 4 is a modification of the annular steel magnet for a small hand telephone
made in accordance with this invention.
This improved telephone consists of an annular steel magnet aaaa, a non-
magnetic metallic ring b, the membrane e, and two pole shoes or tips d with the
induction-coils e.
The membrane or diaphragm e is not made of iron as the membranes heretofore
in use, but it consists of a non-magnetic metallic disc with a reinforced or non-
reinforced rim c¹ and a diametrically inserted narrow iron strip which divides
the whole membrane into two large non-magnetic fields but with which the strip
is firmly connected by hard solder. The membrane which is made in such manner
is of course very accurately finished so that the thickness thereof is perfectly
uniform throughout. The annular steel magnet is composed of 4 segmental or
quadrant-steel-magnets a in such manner that the poles of the same name lie near
5 each other. The whole magnet-ring aa aa has therefore two equal double
poles nn (north pole) and ss (south pole) which are situated opposite each other
diametrically. The membrane c is inserted between these magnet-rings aa aa and
the metallic (bronze) ring 6 in such manner that its iron strip c² metallically con-
nects the two double south poles ss and ss and thus forms one single strong south
0 pole.
The two north poles nnnn are each provided with one pole shoe or tip d the
pole shoe d of the one pole nn being situated in front of the membrane c with its
free end directed radially towards the centre of the membrane and the pole shoe d

page_text: ring AA and each of the latter being provided with a pole shoe D which is con-
nected with one of the poles N N opposed to the poles SS substantially as described
and shown in the drawing.
1000
W. P. THOMPSON & Co.,
322, High Holborn, London, W.C.,
Patent Agents for the Applicant.