IMPROVEMENTS IN TELEPHONIC RECEIVING APPARATUS
Year: 1882

page_text: PROVISIONAL SPECIFICATION left by Richard Theiler and Meinrad Theiler
at the Office of the Commissioners of Patents on the 21st March 1882.
RICHARD THEILER and MEINRAD THEILER, both of 86, Canonbury Road,
Islington, in the county of Middlesex "IMPROVEMENTS IN TELEPHONIC RECEIVING
APPARATUS
Our invention relates to an improved and simplified construction of telephone
receivers in which the tympanum or diaphragm, also the permanent magnet and
the ear-piece or funnel common to other telephones are entirely dispensed with.
In the telephone receivers of Reiss, Gray, Bell and other Inventors, the tympanum,
diaphragin or sounding board constituted a necessary part of the apparatus because
the electro magnet and armature constituting the remaining parts of the apparatus
were not constructed in such a manner that the vibrations of articulate speech
could be heard without the aid of a tympanum or other resonant surface. Our
telephone receiver consists only of an electro magnet to one pole of which we
usually fix a stem, or knob which can be conveniently inserted in the ear of the
listener. The vibrations of the electro magnet produced by the vibratory current
passing through the latter are thus directly communicated to the walls of the ear
and the effect of those vibrations upon the ear is not diminished by an intervening
air space as is unavoidably the case in telephones with tympanums or diaphragms.
The articulation of the sound received in this direct manner is more distinct and
of a more natural" timbre" than that communicated by a diaphragm or sounding
board. We construct our vibrating magnets of various forms. The simplest
consists in a small electro magnet of the usual U shape, provided with prolongations
of the poles that almost touch one another but are prevented by their rigidity from
doing so. The said stem or knob is fixed to one of the poles and may consist of
any substance, a good conductor of sound being the most suitable. In another
form of our telephone we provide only one pole of the electro magnet with a
prolongation (of considerable rigidity) and cause it to overlap the other pole in
such a manner that it almost touches the latter.
The stem or 'knob in this arrangement is fitted to the extremity of the said
prolongation. By making the said pole prolongation of suitable form it may be
applied directly to the ear without being fitted with a knob or stem. We also

page_text: dispense with the stem or knob by embedding the vibrating magnet in a block of
cane or other good conductor of sound.
The vibrations of the electro-magnet are in this case communicated to the end
of the fibres constituting the said conductor of sound and are distinctly heard by
applying the ear to the end or cross cut of the said block.
We arrange vibrating electro-magnets in various other forms without departing
from the main feature and novelty of our invention. It is however not necessary
that the vibrator be an electro magnet. We obtain very good results by attaching
a microphonic contact to the said stem or knob and connecting the former with a
battery and the primary circuit of an induction coil, the secondary circuit being
connected with the line and transmitter. We also prefer to use an induction coil
with the electro magnetic telephone described and dispense with a permanent
magnet by connecting the clectro-magnet with the primary circuit of the said
induction coil and a local battery while the secondary circuit is connected with the
line. As an induction coil is now generally used with the transmitting apparatus
we sometiines make use of the same coil for both the transmitter and the receiver
by either inserting the receiver in the primary circuit of the transmitter or by
winding the said coil with three distinct circuits; one for the transmitter, one for
the receiver and the third for the line.